A paper1 recently published in Science explored the fascinating question of how the mitochondrial genome affects cellular function. The research work was carried out at the University Medical Center of Gottingen, led by Prof. Peter Rehling and Luis Daniel Cruz-Zaragoza (currently Professor at the Department of Biology, Université de Sherbrooke). Through a multi-institutional collaboration, the team developed a method to silence the translation of specific mitochondrial mRNAs selectively and used it to gain a deeper understanding of how mitochondria regulate translation.
Human mitochondria have their own small circular genome that encodes genes for essential proteins needed for oxidative phosphorylation. However, they are also involved in many other cellular functions, and most of the genes for those other functions are contained in the nuclear genome. The interactions of the two genomes are one of the most interesting open questions in biology today. Dissecting the translation of mitochondrial mRNAs has been challenging because standard methods (e.g., CRISPR) do not work inside mitochondria.
To overcome this challenge, the scientific team used synthetic peptide-morpholino chimeras to inhibit translation of specific mitochondrial genes. These synthetic molecules combine the phosphorodiamidate morpholino oligonucleotides directed against a specific mRNA with a mitochondrial targeting signal (or presequence). The chimeric molecules entered the mitochondria and blocked translation. By inhibiting the synthesis of each protein under different conditions, the researchers could ascertain the particular cellular response upon depletion.
With this study, the team identified proteins involved in the biogenesis and activity of the oxidative phosphorylation complexes. They also gained insights into how the cell deals with the loss of a key protein. Ultimately, the method can be applied to numerous other studies in mitochondrial biology.
Conversation with Dr. Cruz-Zaragoza
MitoWorld: Polymorpholino oligonucleotides are typically used as antisense oligonucleotides. Why did you decide to apply them for targeting the expression of mitochondrially encoded genes?
LDCZ: Close to 99% of proteins in the human mitochondria are encoded in the nuclear genome, translated in the cytosol, and imported into the mitochondria. Several genetic approaches are available to study and understand the function of this group of proteins, including CRISPR-Cas9, siRNA, epigenomic expression, and genomic integration. Those methods require the use of nucleic acids. Although transfecting nucleic acids into a cell is relatively straightforward, the same doesn’t apply to the mitochondria.
Mitochondria have two membranes: the outer mitochondrial membrane (OMM) and the inner mitochondrial membrane (IMM). The electron transport chain (ETC) is localized on the IMM. The activity of ETC generates a potential difference across the mitochondrial membrane, known as the mitochondrial membrane potential, making the IMM’s luminal side negatively charged. Therefore, it is no surprise that the introduction of nucleic acids into the mitochondria is highly inefficient, hindering efforts to apply genetic engineering to mitochondrial gene expression. Remarkably, researchers have developed several solutions based on proteins, such as base editors and mito-zinc finger protein nucleases.
We expected that non-charged oligonucleotides, such as phosphorodiamidate morpholino oligonucleotides, should be better imported into mitochondria. To target the morpholinos (MO) to the mitochondria, we initially fused the MO to a protein carrier via click chemistry, generating protein-MO chimeras. We applied this initial approach in isolated mitochondria.2
However, it did not escape our attention that a more versatile method was required for use in living cells. Therefore, building on our previous work, we optimized the chimera stability and efficiency by replacing the protein component with a mitochondrial targeting signal peptide.1
MitoWorld: What experiments do you have planned to extend this work?
LDCZ: It was thrilling to develop this expression-silencing project. For our recently published work, I had the opportunity to work with several talented graduate students. In addition, the collaborators who participated in our study are remarkable, combining expertise in proteomics (Bettina Warscheid’s group), microscopy (Stefan Jakob’s group), and transcriptomic data analysis (Michael Lidschreiber’s group). So, exciting work is in the making at University Medical Center of Gottingen.
I recently established my lab at the Université de Sherbrooke in Canada. As part of our research program, we will address the functional aspects of mitochondrial RNA life using the peptide-MO chimeras. We will follow an RNA-centered approach and examine how it correlates with the traditional protein-centered one. Luckily, Quebec, and Sherbrooke in particular, has an excellent group of scientists working in RNA biology as part of the RiboClub and the DNA to RNA Initiatives. Exciting times ahead!
MitoWorld: Were you able to link the loss of a specific protein to any human disease?
LDCZ: In our work, we explored the cellular response to challenges associated with the inhibition of subunits encoded in the mitochondrial genome. We have not yet made a direct comparison with mtDNA human disease models. However, it is an attractive problem that we, and other labs, will follow up on. One exciting aspect of our approach is the possibility of revealing and understanding, at the cellular level, the initial stages of defects in mitochondrial gene expression. In the field, researchers traditionally study patient-derived cells that have undergone long-term adaptation. However, silencing mitochondrial transcripts recapitulates the initial chronic depletion of proteins produced in the mitochondria, allowing us to examine how the cell responds and adapts to the challenge. In fact, one can study the onset of the disease in specialized cells, such as cardiomyocytes and hepatocytes. Therefore, this could be extended to other cell types, such as neurons and oocytes. This could contribute to the development of better therapies for mitochondrial diseases.
MitoWorld: Do you see any clinical or diagnostic applications for this methodology?
LDCZ: That is a great question. We can now tune the expression of specific genes encoded in mtDNA. This would allow for controlling the assembly rate of proteins with different genetic origins (nuclear and mtDNA) that form the respiratory complexes, which could be an avenue for treating disorders where the balance is lost. However, some aspects must be addressed before. The most important one is to show that the silencing approach is working in animal models.
MitoWorld: What drew you to mitochondria in the first place?
LDCZ: I have always been intrigued by the eukaryotic cell compartments. During my doctoral studies in Ralf Erdmann’s group at Ruhr-Universität Bochum, I investigated the peroxisome, focusing on its biogenesis mechanisms and function. I enjoyed it very much as part of the Marie Curie Initial Training Network PERFUME (PERoxisome, FUnction, MEtabolism). While attending conferences about protein targeting, I saw how exciting the research in mitochondria was. After finishing my PhD, I joined Prof. Rehling’s group to study mitochondrial protein import. Later, I became interested in working on mitochondrial gene expression. Combining my scientific interests in protein import and gene expression was central to devising the strategy of importing protein-MO chimeras to regulate mitochondrial gene expression.
References
1Cruz-Zaragoza LD, Dahal D, Koschel M, Boshnakovska A, Zheenbekova A, Yilmaz M, Morgenstern M, Dohrke JN, Bender J, Valpadashi A, Henningfeld KA, Oeljeklaus S, Kremer LS, Breuer M, Urbach O, Dennerlein S, Lidschreiber M, Jakobs S, Warscheid B, Rehling P (2025) Silencing mitochondrial gene expression in living cells. Science DOI: 10.1126/science.adr3498.
2Cruz-Zaragoza LD, Dennerlein S, Linden A, Yousefi R, Lavdovskaia E, Aich A, Falk RR, Gomkale R, Schöndorf T, Bohnsack MT, Ricarda Richter-Dennerlein R, Henning Urlaub H, Peter Rehling P (2021) An in vitro system to silence mitochondrial gene expression. Cell 184: 5824–5837.
A recent paper in Science Advances describes the findings of a research team led by Mondira Kundu, MD, PhD, at St. Jude Children’s Research Hospital. The study investigates how mitochondrial (mt) DNA mutations influence leukemia pathology. Unexpectedly, their research showed that a moderate burden of mtDNA mutations can enhance the development of leukemia. They also show that cancer can be re-initiated by inhibiting a specific enzyme in cells carrying a high burden of mtDNA mutations.
Cancers are highly energy dependent, with the mitochondria serving as the cell’s main energy producers. While most research into this connection has focused on mutations in nuclear DNA that affect mitochondrial function, Dr. Kundu’s team explored whether mutations directly in the mtDNA contribute to tumor development.
The researchers began with three lines of mice expressing a mutant exonuclease-inactive mitochondrial DNA polymerase (Polgmut) that lacks accurate proofreading ability. These lines possess either zero (Polgwt/wt), one (Polgwt/mut), or two (Polgmut/mut) copies of the mutated allele, resulting in a graded accumulation of mtDNA mutations. Hematopoietic progenitor cells (HPCs) were isolated from these mice and engineered to express NMyc, a member of the MYC family of transcription factors. Members of the MYC family are commonly dysregulated in many blood cancers, such as leukemia. By transplanting these HPCs into irradiated recipient mice, the team assessed the impact of different levels of mtDNA mutations on cellular metabolism and cancer development.
The findings were unexpected: while metabolism was reduced in mice with either heterozygous or homozygous mutant cells, mice with a moderate mutation load (Polgmut/wt) were more prone to tumor formation than those with a high mutation load (Polgmut/mut). Metabolic plasticity was affected by the number of mtDNA mutations and was critical to the tumorigenic potential of the HPCs. In essence, a moderate number of mutations makes cells more metabolically flexible and more carcinogenic, whereas extensive mutations diminish both their metabolic flexibility and cancerous potential.
Conversation with Dr. Kundu
MitoWorld. Your results are unexpected. Do you have any thoughts on why the partially damaged mitochondria would be beneficial to the cancer? Yes, it appears that partially damaged mitochondria create a unique metabolic environment that cancer cells can exploit. Moderate mitochondrial dysfunction may allow for metabolic reprogramming—enhancing glycolysis and other pathways that support rapid cell growth—without fully compromising energy production. This balance may give cancer cells a survival and growth advantage.
MitoWorld. Can you speculate on how the damaged mitochondria are able to increase their metabolic support for the tumors? Damaged mitochondria may trigger adaptive responses in cancer cells, activating alternative metabolic pathways and stress responses. For instance, partial mitochondrial dysfunction can increase the reliance on glycolysis (the Warburg effect) and other biosynthetic pathways, thereby supporting both energy needs and the synthesis of cellular building blocks required for proliferation. The cells remain metabolically flexible, which is crucial for tumor growth.
MitoWorld. You note both similar and different results with this mutation and different cancers. To what would you attribute those varying results? The impact of mtDNA mutations likely depends on the tissue context and the specific metabolic requirements of different cancers. Some tumors may be more resilient to mitochondrial dysfunction, while others are more dependent on intact mitochondrial metabolism. Additionally, the interplay between mtDNA mutations and nuclear gene mutations can vary, influencing how cells adapt metabolically and whether they become more or less tumorigenic.
MitoWorld. Your results show that inhibiting pyruvate dehydrogenase kinase improved the ability of the homozygous mutant to cause tumors. Does this observation have any therapeutic implications? While our findings are not immediately translatable to therapy, they do highlight the critical role of metabolic plasticity in leukemogenesis. The fact that inhibiting pyruvate dehydrogenase kinase (PDK) restored the proliferative capacity of homozygous mutant HPCs suggests that metabolic pathways can profoundly influence tumor development. This raises the possibility that targeting metabolic enzymes like PDK could one day be leveraged to modulate cancer cell growth, either by restricting the metabolic flexibility of cancer cells or by exploiting specific metabolic vulnerabilities. However, more research is needed, especially since the mutation burden in human leukemias typically comes from single mtDNA mutations, unlike the mouse model, where the burden comes from the cumulative effect of many mutations.
MitoWorld. What do you see as the next steps to follow up on this work? The next step is to introduce specific mtDNA mutations into primary cells and then add oncogenes. This will allow us to examine how individual mtDNA mutations—and their allele fractions—impact tumorigenesis. By better modeling the mutation patterns seen in human cancers, we can determine whether particular mtDNA mutations or metabolic states make cancer cells more susceptible to targeted metabolic therapies. Ultimately, this line of research could guide the development of new therapeutic strategies that exploit the metabolic dependencies created by mtDNA mutations in cancer cells.
MitoWorld. What attracted you to the study of mitochondria? As a hematopathologist, I have a strong interest in hematologic diseases, but my research has always spanned a variety of biological systems. My interest in mitochondria began during my postdoctoral fellowship in Craig Thompson’s lab, where I used red blood cell maturation as a model to study mitophagy—the process by which cells selectively remove damaged or superfluous mitochondria. That experience highlighted for me how central mitochondrial function and dysfunction are to cell biology and disease, including cancer. I am particularly intrigued by how cells sense and respond to mitochondrial dysfunction—especially when it’s caused by mtDNA mutations—and how these adaptive pathways can contribute to cancer development. Understanding the complex interplay between mitochondrial function and cellular responses not only deepens our knowledge of cancer biology but also points to new possibilities for therapeutic intervention.
Reference
Li-Harms X, Lu J, Fukuda Y, Lynch J, Sheth A, Pareek G, Kaminski MM, Ross HS, Wright CW, Smith AL, Wu H, Wang Y-D, Valentine M, Neale G, Vogel P, Pounds S, Schuetz JD, Ni M, Kundu M (2025) Somatic mtDNA mutation burden shapes metabolic plasticity in leukemogenesis. Science Advances 11(1): eads8489.
Biomedical evidence systematically collected from astronauts, mice and rats during and after extended time on the International Space, shorter trips (weeks), and even on much shorter trips such as SpaceX’s Inspiration 4 flights show mitochondrial stress.
If Elon Musk intends to plan for life on Mars or NASA plans for settlement on the Moon, they might want to consider one of the most interesting and mysterious parts of every cell in every complex organism (e.g. animals and plants), including us, mitochondria. This biological-physiological issue cannot be solved by successful SpaceX rocket launches or settlement selection. It’s not an engineering or planetary issue, but a deeply scientific and medical one.
Many scientists, philosophers, and writers have dreamed of a destiny for humanity that may exist beyond our home planet. All the global superpowers have their sites on the Moon, Mars and asteroids. Yet, the engineering, physics, material science, propulsion, planetary science and trajectories are still being mastered. In all these calculations, eventually requiring trillions in investment in engineering, there is something profoundly left out of the equation: humans and our bodies.
A MitoCast Interview with Chris Mason (WorldQuant Professor at Weill Cornell Medicine) and Afshin Beheshti (Director of Center for Space Biomedicine, Associate Director of McGowan Institute for Regenerative Medicine, and Professor of Surgery and Computational and Systems Biology at University of Pittsburgh) , top space biomedicine researchers who continue to form teams and pour over the astronaut (and mice and rat) data of those who have been in the International Space Station and on the shorter flights, tells a cautionary story, but also a focal point for countermeasures.
Listening to Mason and Beheshti, it is clear that the planned long space transits or moving off Earth will need to consider the health, function, and stress on the tiny mitochondria in each of our cells, and those of animal-nauts, which may need treatments or modifications to support life away from Earth.
Mitochondria are starting to make it into the news because of their role across the medical and health spectrum. Most people remember the biology class refrain, Powerhouse of the Cell, describing the mitochondrial role in energy production (Krebbs Cycle, ATP production). However, mitochondria, which number from 150 to 7000 per cell, depending on the tissue or organ, have deep regulatory roles in cell life and death, the immune system, and signaling in multiple ways.
Mitochondria are coming of age.
For the last twenty-years, the primary research domain has been the rare mitochondria DNA mutational diseases, primarily of childhood. However, that balance is shifting as mitochondria are now implicated in cardiac disease, diabetes, neurodegenerative diseases and in aging itself. While mitochondrial research rapidly gains ground in the search for cures for chronic diseases, health and diet, a current focus in U.S. policy, a rapidly growing parallel track runs in health and fitness circles and high-performance athletics.
Will Mitochondria Keep Us on Earth?
However, there is a certain amount of hubris to suggest that creatures specifically evolved on Earth within its gravitation, magnetic, atmospheric, biodiverse and radiation envelope would be suitable, or adaptable, to other environments, including life on the Moon or transit time to Mars. While both of those planetary objects have substantially lower gravity (Moon 1/6th, Mars 3/8th), they also either have no shielding from an atmosphere (the Moon) or very little (Mars) and have very different radiation and magnetic signatures and, of course, no known life forms.
As daunting as it was for the earliest human to migrate around the planet, chasing megafauna driven by some innate drive, leaving Earth is a very different biological, physiological and cultural challenge.
We asked Mason and Beheshti a few questions to go along with their longer MitoWorld Spotlight video.
MitoWorld: How did you end up focusing on life in Space and becoming experts in this emerging field?
Beheshti: Chris and I have been working together for almost a decade on various projects from Space biomedicine to COVID-19/Long COVID to cancer… We have had many papers in high impact journals and have put together two high profile paper packages one in Cell Press and the other in Nature Portfolio.
MitoWorld: How did you two end up working on NASA and other bio-data?
Mason: We met originally though some of the GeneLab working groups (now OSDR), working on a variety of projects for human and mouse genomics and other omics data analysis and then really to follow up on the Twins Study. This led to several sets of large-scale collaborations for the Biology of Spaceflight Cell Package in 2020, a range of papers and grants from 2019-current, and also the Nature Space Omics and Medical Atlas Resource in 2024.
Beheshti: Chris and I have been working together for almost a decade on various projects from Space biomedicine to COVID-19/Long COVID to cancer. We have had many papers in high impact journals and have put together two high profile paper packages one in Cell Press and the other in Nature Portfolio.
MitoWorld: How did you two become a team?
Mason: We kept dreaming of ways to integrate more data, leverage human and animal models for analysis, and how to engage the broader community more. We also kept making jokes during calls and enjoying each other’s company.
MitoWorld: Did NASA contract directly with you or through other entities for the work that ended up in the Omics Atlas?
Mason: We have about 12 NASA grants that have supported our work since 2014, but it was not a “contract,” but a grant, as well as NIH and NSF funding. We also had significant support from philanthropy (WorldQuant, Sloan, and Pershing Foundation)
MitoWorld: How were the writers and teams chosen to work on the key papers?
Mason: We offer a spot to everyone and anyone, but ideally get younger scientists to lead these papers and projects to help them propel their career.
MitoWorld: When did each of you become interested in life in space?
Mason: Ever since I was a kid! I went to Space Camp twice in elementary school, and loved genetics since middle school. I am grateful and honored I get to worked on the two things I love most, with people that are very enjoyable like Afshin!
Beheshti: I was always a Sci Fi fan so naturally when I started my journey with Space Biomedicine research in my second postdoc it was a great fit with my large interest in Science Fiction.
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Mason Lab Background: The Mason Lab performs research in three principal areas: (1) clinical genetics, (2) computational algorithms and data structures, and (3) synthetic biology. Clinical genetics work spans Mendelian diseases, aggressive cancers, novel viruses, and astronauts in the Space Omics and Medical Atlas (SOMA). Computational methods include new techniques in DNA/RNA sequencing, spatial imaging, planetary-scale metagenomics, and DNA/RNA base modifications. Synthetic biology research deploys new models for genome, cellular, and microbial ecosystem engineering, including synthetic T-cell systems, built environment modifications, and microbially optimized regolith. [Link]
Beheshti Background: Afshin Beheshti recently joined the University of Pittsburgh as a Professor of Surgery and Computational and Systems Biology, Director of the Space Biomedicine Program, and Associate Director at the McGowan Institute of Regenerative Medicine. In these roles, he will continue his ongoing projects and launch a new space biomedicine program at the University. With this new initiative he will create research opportunities to explore space health issues, research countermeasures to mitigate the damage caused by the space environment and develop outreach/education programs for space biology research. [link]
In a preprint article currently under review1, “Guardians of the mitochondria: Space mitochondria 2.0 systemic analysis reveals bioenergetic dysregulation across species,” a research team led by Afshin Beheshti (Director of Center for Space Biomedicine, Associate Director of the McGowan Institute for Regenerative Medicine, and Professor of Surgery and Computational and Systems Biology at the University of Pittsburgh) with co-senior author Chris Mason (WorldQuant Professor at Weill Cornell Medicine) explores the broad impacts of spaceflight on mitochondrial biology in humans and across a range of animal species to identify consistent effects of space exposure on the organelle and its influence on human health.
Astronauts returning to Earth after extended time in space suffer a number of stressors, including bone and muscle loss, cardiovascular and renal issues, circadian rhythm disruptions, potential long-term cancer risks, and ocular disorders. These health effects are thought to be caused by some combination of exposure to higher levels of radiation and reduced gravity. However, the exact mechanisms of how the conditions of space travel manifest in the physical symptoms in astronauts and other organisms are still unclear.
Previous work by Mason and Beheshti, including the “NASA Twins Study” and the “Space Omics and Medical Atlas,” measured biological characteristics in twin astronauts, Mark and Scott Kelly2 and then compared them to many additional cohorts and missions. The landmark Twins study tracked the astronauts over 340 days, while one flew on the international space station and the other remained on Earth. Surprisingly, the investigators identified mitochondrial respiration as one of the first and most important biological processes to be disrupted by spaceflight.
This new report aims to expand upon and generalize the prior findings by extracting mitochondrial function data from several studies of space exposure in a range of species, including humans (Guarnieri et al., in review). This large-scale, multi-institute study integrates an impressive collection of multi-omics data from humans, rodents, and other organisms before, during, and after returning from space. This rich dataset enables the authors to draw broader conclusions about how the mitochondria of people or animals will respond to spaceflight.
The authors show that effects of space exposure occur in a duration-dependent manner across species and tissues. More specifically, it causes accumulation of reactive oxygen species (ROS) and impairs mitochondrial oxidative phosphorylation (OxPhos), the series of enzymatic reactions that mitochondria use to extract the energy from the food we eat. Moreover, the cellular stress induced by ROS accumulation and OxPhos disruption causes the release of mitochondrial signals that trigger immune system abnormalities in astronauts and animals. Strikingly, the changes to OxPhos and immune activity are accompanied by epigenetic changes that influence mitochondrial gene expression and last for more than 14 weeks after astronauts return to Earth.
The severity of mitochondrial impairment was influenced by the genetic background of the animals exposed to the space environment. Mice with mutations leading to less robust mitochondrial antioxidant defenses against ROS experienced greater damage during space flight, suggesting certain biological pathways can be harnessed to stratify risk profiles and protect astronauts on future missions. To this end, the team tested if kaempferol, an antioxidant compound and stimulator of mitochondrial biogenesis, could reduce the damage from space exposure. Mice treated with kaempferol were protected from liver damage during spaceflight, and human liver organoids exposed to the compound in space lost less mass and retained their function, compared to their untreated counterparts.
This study differs from previous efforts in that it examines changes in mitochondrial biology in response to a range of space-exposure durations across species of animals. It emphasizes the need for and provides evidence of preventative measures and in-flight treatments that can protect astronauts from damage to their mitochondria during longer space missions. These methods and countermeasures will become more important as longer space flights are considered, and they may also shed light on Earth-bound disease mechanisms as well.
Discussion with Drs. Beheshti and Mason
MitoWorld: Space travel seems to affect multiple tissue and organ systems. Could you expand on the mechanisms underlying the effects on mitochondrial function? What work do you think should be done to better understand the conditions that lead to mitochondrial stress?
Beheshti: The two primary stressors in space that drive mitochondrial dysfunction are microgravity and space radiation. In our recent preprint, we highlight how the degree of mitochondrial disruption depends on the radiosensitivity of different tissues, suggesting that some tissues are more vulnerable than others. While both microgravity and radiation are likely to act synergistically, I believe radiation has a more pronounced and compounding impact on mitochondrial health. To better understand these mechanisms, we need studies that systematically compare the effects of microgravity and radiation, both independently and in combination. Additionally, ongoing research, including our own, is evaluating a range of mitochondrial-targeted supplements and therapies as potential countermeasures. I believe there’s strong potential to develop an optimized “mitochondrial cocktail,” a combination therapy tailored to protect against space-induced mitochondrial stress and, ultimately, safeguard astronaut health during long-duration missions.
MitoWorld: Different tissues seem to respond to space exposure in unique ways. Can you speculate on why our organs have different sensitivities to spaceflight? Furthermore, does the stress response to damage in one organ system feed forward to damage otherwise more resilient tissues?
Beheshti: As I mentioned earlier, different organs in the body have varying degrees of radiosensitivity, which helps explain why tissues respond differently to spaceflight. In our recent work, we outline how tissues, such as the spleen, skin, eyes, and immune-related organs, tend to be more radiosensitive, and denser tissues, such as muscle, bone, and brain, are generally more radioresistant. These differences have long been established in the field of radiation biology and translate well to the context of space radiation exposure. However, even the more resistant tissues are not immune. Given prolonged exposure to the space environment, we observed a widespread suppression of mitochondrial OxPhos across all tissues, including long-term effects after returning to Earth.
An important and often overlooked aspect is how damage in one organ system can propagate systemic stress. While we didn’t delve into this in the paper due to limited available data, the concept of a “bystander effect” from radiation biology is highly relevant here. This phenomenon describes how irradiated cells can transmit stress signals to neighboring non-irradiated cells, leading to secondary damage. Similar effects have been observed at the tissue level, suggesting that injury to more radiosensitive organs could exacerbate dysfunction in otherwise more resilient tissues. This kind of cascading, systemic stress response may play a significant role in how the body as a whole reacts to prolonged space exposure, and underscores the need for integrated, multi-organ studies to fully understand and mitigate these complex interactions.
Mason: Each organ system has distinct energetic requirements, and thus, we expect to see some heterogeneity in the response across tissues. Also, each organ ages at different rates, and so, this also is likely a function of mitochondrial function and complex biological interactions across multiple pathways and systems.
MitoWorld: Does mitochondrial morphology or dynamics change in the low-gravity conditions of spaceflight?
Beheshti: This is an important and still open question. At this time, we don’t have definitive data on how mitochondrial morphology or dynamics change under microgravity conditions, but it’s an area that absolutely warrants deeper investigation. In fact, we are currently conducting imaging experiments to address this very question, and we hope to provide new insights soon. Based on what we know about mitochondrial behavior under various stress conditions on Earth, I strongly suspect that mitochondrial morphology does change in microgravity. Disruptions in mitochondrial fission and fusion dynamics, alterations in cristae structure, and changes in network connectivity are all possible responses to the unique stresses of spaceflight. These changes could have significant downstream effects on energy production, redox balance, and apoptosis, ultimately impacting tissue health and resilience. Understanding these structural and functional adaptations will be key to developing targeted interventions to preserve mitochondrial health in space.
MitoWorld: It’s very interesting that the immune system is affected by mitochondrial stress induced by space flight and that epigenetic changes persist for weeks after astronauts return to Earth. Are returning astronauts more susceptible to infection after long-duration space missions, and does this pose a risk for infections threatening the viability of future space settlements and long-duration travel throughout the solar system?
Beheshti: Our findings suggest that mitochondrial dysfunction, particularly the long-term suppression of OXPHOS, plays a central role in disrupting immune function during and after spaceflight. This mitochondrial stress appears to impair the energy metabolism required for proper immune cell activation and response, leading to broader immune dysregulation. While our study highlights this link mechanistically, it raises the concern that astronauts may indeed be more susceptible to infections after long-duration missions. However, it’s important to note that direct evidence of increased infection rates in returning astronauts is still limited.
What is particularly concerning is that these mitochondrial and immune impairments persist for weeks after return to Earth, and are accompanied by sustained epigenetic changes. This suggests that the immune system does not immediately rebound post-flight, which could pose risks not only upon re-entry but also during extended missions, where access to medical intervention is limited. If such immune vulnerabilities are not properly mitigated, they could threaten the health of crew members and the overall viability of future deep space missions or permanent settlements.
Moving forward, more research is needed to directly measure susceptibility to infection post-flight and to identify reliable biomarkers that flag immune dysfunction early. We must also begin validating countermeasures, including mitochondrial-targeted therapies, that preserve or restore immune resilience in the space environment.
Mason: We don’t see longer risk of infection post-flight, but we and others do see a lot of viral activation in-flight, and changes in biological pathways related to immune function and activation.
MitoWorld: If astronauts, who are selected for being very physically fit and disciplined individuals, suffer ill health effects from long duration space travel, how would the physiological response to long-term spaceflight differ in a cross section of the population?
Beheshti: When it comes to mitochondrial dysfunction, I believe we would see similar core impacts across the general population, but the severity and resilience of the physiological response could vary widely, depending on baseline health, genetic predispositions, and other risk factors. Astronauts are among the most physically fit and medically screened individuals; yet, even they exhibit signs of mitochondrial stress, immune dysregulation, and other health effects during and after long-duration spaceflight. This suggests that members of the general population, who may have pre-existing conditions or less physiological reserve, could be even more vulnerable to the same stressors.
As Dr. Mason pointed out, the Inspiration4 mission, which was the first all-civilian crewed orbital mission, provided a glimpse into how non-career astronauts might respond to spaceflight. While it was a short-duration mission, it offered early indications that space-induced physiological changes are not limited to elite astronauts. If missions extend to months or years, as envisioned for Mars or deep-space travel, we can expect a wider range of biological responses and potentially more severe health challenges in a more diverse population.
This underscores the need for personalized countermeasures and comprehensive health monitoring tools that can accommodate a broader range of individuals. Future missions will likely include people of varied ages, health backgrounds, and genetic profiles. Understanding these differences and proactively developing adaptable therapies, particularly those targeting mitochondrial resilience, will be critical for the success and safety of long-duration human exploration throughout the solar system.
Mason: We saw that the Inspiration4 crew, which was an all-civilian crew, did just fine during a 3-day orbital mission, and so we are cautiously optimistic for future civilian crews. However, as noted above with the murine data and organ risk, the genetic background of the person and other medical factors should all be considered when assessing flight plans.
MitoWorld: This paper showed that an antioxidant and stimulator of mitochondrial biogenesis may have therapeutic benefit for astronauts. Are there any other pathways revealed by your work that you would like to target next to mitigate the damage from spaceflight?
Beheshti: Absolutely. While our study highlighted the therapeutic potential of compounds, such as kaempferol, an antioxidant and activator of mitochondrial biogenesis, our multi-omics analysis revealed additional pathways and molecular targets that warrant investigation as countermeasures. One key area involves the TCA cycle, which we found to be significantly disrupted across multiple tissues post-spaceflight, particularly at later recovery times. This dysfunction alters key metabolites, such as α-ketoglutarate and succinate, that compromise energy metabolism and act as epigenetic regulators, influencing long-term gene expression patterns.
We also observed suppression of mitochondrial protein import machinery (e.g., TOMM20, CHCHD4), MT-ribosome biogenesis, and Fe-S cluster biosynthesis—critical components for maintaining mitochondrial integrity. These are promising intervention points. Another major axis of dysfunction involves sustained activation of the HIF-1α/mTOR pathway, which shifts cellular metabolism from OXPHOS toward glycolysis in a maladaptive response to stress. Targeting this metabolic rewiring could help preserve energy efficiency and reduce cellular senescence.
Additionally, our work showed that mitochondrial damage leads to the release of DAMPs, such as mtDNA and mtdsRNA, which chronically activate innate immune responses (e.g., via cGAS-STING, NLRP3, and RIG-I/MDA5 pathways). This immune dysregulation could be addressed through strategies that reduce mtDAMP release or block downstream inflammatory cascades.
Beyond antioxidants, we’re also exploring:
- SOD2 mimetics (e.g., MnTBAP, EUK8) to reduce oxidative damage,
- MicroRNA-based therapeutics (targeting miR-16-5p, miR-125b-5p, and let-7a-5p),
- PGC1α activators, such as epicatechin or TFEB/NRF1 inducers, and
- regulators of mtDNA replication and repair, including POLG co-factors.
These approaches offer a systems-level path forward. We’re now working to identify synergistic combinations, a kind of “mitochondrial cocktail,” to simultaneously stabilize bioenergetics, dampen inflammation, and promote mitochondrial renewal. These countermeasures are critical for astronaut health during deep space missions and for understanding and treating age-related mitochondrial decline here on Earth.
MitoWorld: You examined an extraordinary number of systems in this paper. What might be the next steps to follow up on this study?
Beheshti: This study was an ambitious effort to map systemic mitochondrial dysfunction across species, but it’s just the beginning. The next logical step is to expand these investigations into additional models that more closely simulate the conditions of deep space, particularly with higher radiation doses and longer exposure durations. These environments will allow us to better assess how prolonged mitochondrial suppression impacts organ function, immune resilience, and aging-like phenotypes.
Equally important is advancing the development and testing of mitochondrial-targeted countermeasures. While our results with kaempferol are promising, a broader, more systematic approach is needed. This includes evaluating combinations of antioxidants, metabolic modulators, gene expression regulators, and mitochondrial biogenesis enhancers across multiple tissues and models. I believe we’re on the cusp of identifying an optimal therapeutic mitochondrial cocktail that could protect against the chronic stressors of spaceflight.
I also want to take this opportunity to invite the broader mitochondrial and space biology communities to join us. Collaboration will be essential to accelerate the development of effective interventions. This is an open call. If you’re working on relevant pathways or therapeutics, let’s connect and build a coordinated strategy to move this field forward together.
Finally, space provides a unique and accelerated model of mitochondrial disease. The dysfunctions we observed in astronauts mirror and, in some cases, intensify those seen in patients with mitochondrial disorders. If we can validate countermeasures that work under the extreme conditions of space, there’s a strong potential to translate those findings back to Earth and develop novel treatments for patients suffering from mitochondrial diseases and related chronic conditions.
Mason: Replication is the cornerstone of good science, and so we want to continue to test these models in future missions, other animal cohorts, and in other cellular contexts.
MitoWorld: Aging induces changes in mtDNA over time and causes changes in the ratio of healthy mtDNA to damaged mtDNA, known as heteroplasmy. Would it be wise in future studies to look at heteroplasmic shifts and if they are permanent or seem to rebound once astronauts return to Earth?
Beheshti: Yes, indeed it will be. We have plans to further explore this.
Mason: Yes, we have seen some evidence of this already from prior missions, and this is an exciting area for future study.
References
1Guarnieri JW, Maghsoudi Z, et al. Guardians of the mitochondria: Space mitochondria 2.0 systemic analysis reveals bioenergetic dysregulation across species. Cell In review.
http://dx.doi.org/10.2139/ssrn.5087025
2Garrett-Bakelman FE, Darshi M, Green SJ, Gur RC, Lin L, Macias BR, McKenna MJ, Meydan C, Mishra T, Nasrini J, Piening BD (2019) The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight. Science 364(6436): eaau8650.
Do neurons help cancer spread? In a paper published in Nature, a multi-institution research team, led by Simon Grelet at the University of South Alabama, provides strong evidence for a key relationship between cancer cells and neurons. They showed that mitochondria migrate from neurons to cancer cells to increase the metabolism of the cancer cells.
Dr. Grelet’s team focused on the mitochondria in cancer cells. The spread of tumors requires a significant amount of energy, and mitochondria produce energy for the cells. Cancer cells are well-known for adapting their metabolism to fit changing conditions. However, this metabolic plasticity was thought to be due to changes within the tumor cells themselves. For example, they could obtain energy by glycolysis (a less efficient process for producing ATP in the cytoplasm) or by oxidative phosphorylation (a more efficient process in the mitochondria). However, cancer cells also receive outside help in the form of metabolites, growth factors and cytokines from other cells.
Previous experiments had shown that somehow the neurons aid tumor progress, but what really interested the Grelet team was a relatively new concept that mitochondria can move from cell to cell. When neurons were co-cultured with tumor cells, the neurons experience changes to their metabolism. The number of their mitochondria increases, and some are transferred to the tumor cells. How could this work?
The team first looked at a co-culture of an aggressive breast cancer cells and neurons. The neurons underwent a morphological change from globular to tubular structures, which indicated the cancer-induced differentiation of the neurons. Neuronal differentiation is associated with changes of metabolic programming from glycolysis to oxidative phosphorylation. These changes were also associated with the establishment of long neuron protrusions, forming a neural network in the culture in vitro, which reflects the establishment of a nerve-cancer crosstalk and suggests the communication or sharing of biological materials.
Next, the team used fluorescent-labeled mitochondria to show that the mitochondria migrated from neurons to cancer cells. These methods revealed additional insights into the transfers, but they had significant limitations. To overcome those limitations, the team developed MitoTRACER. This system used genetic engineering where the donor cell mitochondria carry a tag protein that, once transferred to the recipient cells, triggers an enzymatic reaction activating the permanent expression of a fluorescent protein. The trick is that, when mitochondria move from the neurons to the cancer cells, the red fluorescence is lost, and a green signal is permanently activated. Thus, it is easy to monitor cells with mitochondria that have migrated into a new cell.
Using this unique approach, the researchers have been able to investigate the fate of the recipient cells during the cancer progression cascade, and by fate mapping of the recipient cells from the primary tumor during metastasis progression in vivo. The researchers noted enrichment of acquired mitochondria in brain metastases that might indicate enhanced metabolic plasticity from those extra mitochondria. Neuronal mitochondria are more metabolically active and might better enable tumor cells to thrive in the brain environment. This approach allowed us to define the role of mitochondrial transfer in the primary tumor environment. This process generates a subset of highly efficient metastasis cells that succeed through the complex stops and that are resilient to the metastatic barriers to ultimately form distant metastases, which is the main driver of cancer-associated mortality.
In summary, this fascinating paper might have significant implications for future cancer therapies, and beyond the cancer context, the mitoTRACER approach could have broader applications in studying cell-cell transfer of mitochondria in health and disease to understand the physiopathological implications of these transfers better.
Discussion with Dr. Grelet
MitoWorld: Your paper brings to mind the work of Judah Folkman who showed that tumors need and encourage the formation of a blood supply to progress. What do you believe the tumor may be getting from the nerve cells?
Interesting comparison. Yes, there are definitely commonalities between cancer angiogenesis and cancer innervation. In fact, cancer can actively “call” neurons to innervate them. In the context of cancer, we recently showed that aggressive subtypes of breast cancer cells can secrete axon guidance molecules, including Semaphorin-4F, to promote cancer innervation. We also found that this increased nerve density is associated with enhanced metastasis (PMID: 34810279).
The role of axon guidance molecules in promoting cancer innervation was demonstrated years ago by Dr. Gustavo Ayala (PMID: 11746267; PMID: 24097862), who pioneered the field of cancer innervation and collaborated with us on this study. Since then, many studies, including our own, have confirmed the contribution of these molecules to cancer innervation and cancer aggressiveness. While increased nerve density is often associated with poor clinical outcomes, the underlying mechanisms have remained poorly understood. This gap in understanding is precisely what motivated us to conduct this study.
MitoWorld: The movement of mitochondria from cell to cell is still controversial. What do you think it will take to solidify the concept?
The idea of intercellular mitochondrial transfer remains controversial, largely due to the lack of robust tools and clear in vivo evidence. To solidify the concept, new rigorous and physiologically relevant approaches are needed. For example, genetic systems, such as our MitoTRACER approach, which allow for precise and conditional signaling of transfer events, open the avenue for lineage-based tracking of transferred cells in vivo. Such models are critical to move the field forward and to convincingly demonstrate that mitochondrial transfer is not merely an artifact, but a biologically meaningful process.
MitoWorld: How do you think the cells signal to each other to initiate the transfer of mitochondria?
A variety of signals could potentially be involved in initiating mitochondrial transfer, but these remain to be better defined. In the context of cancer innervation, axon guidance molecules may contribute; more generally, transfer events may occur as part of a stress or help response, or by hijacking existing physiological communication routes. These signals could include reactive oxygen species, cytokines, or changes in membrane potential or lipid composition. Cancer cells, for instance, can upregulate molecules involved in cell-cell contact to facilitate mitochondrial transfer, as elegantly demonstrated by Watson et al. (PMID: 37169842). Deciphering the molecular language of this intercellular request remains a critical next step for the field.
MitoWorld: These experiments seem to have ramifications for how the nuclear and mitochondrial genomes coordinate their activities. Do you think the communication between the donated mitochondria and the recipient cell also involves the donor genes?
Absolutely, and this is a topic that warrants further investigation. Mitochondrial transfer introduces not only a new metabolic organelle with all its associated machinery, but also foreign mitochondrial DNA into the recipient cell, raising important questions about nuclear–mitochondrial coordination. While the nuclear genome of the recipient cell continues to govern most mitochondrial functions, the donor mitochondria carry their own genome and organelle machinery, which in our case is fine-tuned for neuronal metabolism and may not be fully compatible. This mismatch could influence mitochondrial gene expression, protein stoichiometry, and ultimately, the bioenergetic output. Whether donor mitochondrial DNA or its transcripts actively modulate recipient cell behavior remains an open and fascinating question. Clarifying the extent and mechanisms of this intergenomic crosstalk is essential to fully understand the consequences of mitochondrial transfer.
MitoWorld: You note that more work is needed to determine if the effects of the donated mitochondria are related to metabolic efficiency or simply that there are more of them. Do you have any sense of which it might be?
In the context of neurons, it is likely a combination of both abundance and quality. On one hand, the increase in mitochondrial mass may help support basic energy demands, particularly under stress. On the other hand, the quality and origin of the donated mitochondria, such as their neuronal bioenergetic efficiency, may actively contribute to metabolic reprogramming in the recipient cell. In our system, the integration of neuronal mitochondria appears to enhance not only energy production but also metabolic plasticity, enabling cancer cells to better adapt to new microenvironments. Dissecting the relative roles of mitochondrial abundance versus functional impact will be key to understanding how mitochondrial transfer influences cell fate and behavior.
MitoWorld: Folkman used his findings to suggest that cancers could be treated by preventing angiogenesis, and that is now widely accepted. Do you have any thoughts on how your findings with neurons might be used to develop therapeutic strategies for cancer?
Yes, absolutely, that is the ultimate goal. There are several possible strategies. First, we can target tumor innervation itself, which supports cancer progression. Second, we can aim to block the intercellular transfer of mitochondria, which fuels cancer cell adaptation. Third, and perhaps most compelling, we can selectively target recipient cancer cells that have acquired unique metabolic or phenotypic traits as a result of mitochondrial uptake. These cells may represent a vulnerable subpopulation that could be eliminated through precision therapies. Together, these approaches offer a new framework for tackling cancer’s adaptability.
MitoWorld: You looked at breast cancer and melanoma cells, both highly metastatic cancer types. Is the neuronal connection equally valid in less metastatic cancers?
We also previously reported a link between cancer plasticity and cancer innervation (PMID:37046688). Our findings suggest that more aggressive cancer cells are more likely to establish neuronal connections and engage in mitochondrial transfers. This, in turn, may further amplify their aggressive behavior, creating a vicious cycle. The ability of these cells to co-opt neural signaling and reshape their metabolic and phenotypic programs reflects a high degree of plasticity that likely contributes to disease progression.
MitoWorld: Also your work focused on solid tumors. Is there anything to be learned about blood tumors?
Interesting point. Blood cancers reside in richly innervated niches, such as the bone marrow, where neurons regulate hematopoiesis and immune responses. So, similar mechanisms might shape the behavior of leukemia or lymphoma cells. However, this remains largely unexplored, and adapting lineage-tracing tools, such as MitoTRACER, to hematological models could open exciting new directions in the field.
Reference
Hoover G, Gilbert S, Curley O, Obellianne C, Lin MT, Hixson W, Pierce TW, Andrews JF, Alexeyev MF. Ding Y, Bu P, Behbod F, Medina D, Chang JT, Ayala G, Grelet S (2025) Nerve-to-cancer transfer of mitochondria during cancer metastasis. Nature
Dr. José Antonio Enríquez—known to his lab simply as Toño—leads the Functional Genetics of the Oxidative Phosphorylation System (GenOXPHOS) group at the Spanish National Centre for Cardiovascular Research (CNIC). Using large-scale bioinformatics, his lab investigates many aspects of mitochondria, including how their protein complexes assemble, the pathophysiology of mitochondrial diseases, and even the evolutionary history of mitochondrial proteins.
Toño’s path to mitochondrial science began at the University of Zaragoza, where he completed his PhD. He then moved to California for a postdoc at Caltech before returning to Zaragoza to establish his first lab as a Principal Investigator. About 15 years ago, he moved his lab to CNIC, where he continues to push the boundaries of mitochondrial biology.
When asked what drew him to this field, Toño recalled:
“When I finished my biology degree, I knew I wanted to dedicate my life to science, but my interests were broad. I wasn’t drawn to one specific topic or focused on curing a particular disease. I was more interested in understanding the logical rules behind life itself. During a lab rotation at the University of Zaragoza, I encountered mitochondrial DNA (mtDNA). I was fascinated by the fact that this tiny but essential chromosome lives outside the cell nucleus. The idea of an ‘outsider’ chromosome inside a eukaryotic cell sparked my curiosity, and that’s what brought me to mitochondrial research.”
Known for his passionate and fiercely curious nature, Toño fosters a lab culture that encourages creativity, independence, and open scientific debate. He pushes his lab members to think outside the box—not just in their experiments, but in how they approach problems, question assumptions, and imagine what might be possible. He thrives on “crazy” ideas and welcomes disagreement as a sign of engaged thinking. Weekly lab meetings often begin with him sharing a new paper, a philosophical question, or a hypothesis that came to him out of the blue.
What are the big questions ahead for mitochondrial research?
“Mitochondria continue to surprise us,” says Toño. “From their own unique DNA and divergent genetic code to their roles in apoptosis, signaling, and disease, there’s always something unexpected. The OxPhos system alone is remarkably complex in both structure and function.”
As for what’s coming next?
“I think the most important discoveries may still be ones we don’t expect. But if I had to name specific questions for the coming year, I’d point to three:
- Understanding how sodium (Na⁺) helps build the mitochondrial membrane potential,
- Figuring out how cells maintain different types of specialized mitochondria within a single cytoplasm, and
- Resolving the debate over whether mitochondria can move between cells in a physiologically meaningful way.”
A major breakthrough: SCAF1 and mitochondrial supercomplexes
One of the lab’s most exciting discoveries was identifying the protein SCAF1 (supercomplex assembly factor 1), which enables the physical interaction between two key components of the electron transport chain—complex III and complex IV.
“This was a big step in supporting our ‘plasticity model’ of how the mitochondrial electron transport chain is organized,” says Dr. Enríquez. “We were also excited to show that variations in mtDNA can influence metabolism and healthy aging. And our recent finding that respiration complex I acts as a sodium/hydrogen (Na⁺/H⁺) antiporter revealed that sodium plays a major role in building the mitochondrial membrane potential.”
Meet the GenOXPHOS Team:
The GenOXPHOS lab currently includes around 10 members, each pursuing their own research, but generally, the group can be divided into the following research directions.
Mitochondrial Supercomplexes and Their Role in Health
This team includes three graduate students, each using different strategies to understand how respiratory supercomplexes are assembled and what role they play in health and disease.
Carmen Morales Vidal studies a highly conserved supercomplex made up of respiratory complexes I and III, exploring the importance of this interaction in mammalian cells.
Paula Fernández-Montes Díaz focuses on a family of complex IV protein isoforms, each of which is responsible for a different conformation of complex IV. These variants allow tissues to fine-tune their metabolism based on specific energy needs.
Sara Natalia Jaroszewicz specializes in advanced super-resolution microscopy to visualize these supercomplexes inside intact cells. Until recently, this was only possible using indirect and often disruptive methods.
Heart-Specific Mitochondria
Located in a cardiovascular research center, the lab has a strong focus on heart-specific mitochondrial biology.
Dr. Michaela Veliova, a postdoctoral researcher, studies different subtypes of mitochondria within individual heart cells. She’s investigating how these subtypes form and function and what roles they play in disease.
Dr. Rebeca Acín, a senior scientist, examines the reversal of ATP synthesis, a process where ATP synthase (normally making ATP) starts breaking it down. While this may help with mitochondrial quality control, Rebeca is exploring its connection to disease. She’s also investigating how ATP synthase dimerization (its ability to form pairs) affects this reversal process.
Translational Research: From Discovery to Therapy
This part of the lab focuses on translating basic mitochondrial science into potential therapies.
Dr. Marta Pérez-Hernández Durán, a postdoctoral researcher, is studying a protein kinase called FGR that regulates the activity of mitochondrial complex II. Stress-dependent activation of FGR increases reactive oxygen species (ROS) production and stabilizes HIF1a, ultimately leading to increased release of inflammatory cytokines. Since inflammation is present in numerous heart diseases, Marta is testing whether blocking FGR could be a promising treatment.
Dr. Rebeca Acín is exploring another potential drug target. OMA1, a stress-activated mitochondrial protease can trigger fragmentation of mitochondria. She is examining whether modulating its activity could help prevent mitochondrial damage in disease.
Bioinformatics and Structural Modeling
This line of research seeks to uncover how mitochondrial structures and genetic interactions shape function and dysfunction.
Dr. Jose Luis Cabrera Alarcón, a postdoctoral researcher, studies evolutionary conservation of mitochondrial genes at the population level, with the aim of identifying how genetic incompatibilities between nuclear and mitochondrial genomes might contribute to disease.
Marina Rosa Moreno, a graduate student co-mentored by Dr. Enriquez and José Luis, studies the structural biology of respiratory chain complexes. Using computational modelling and cryo-electron microscopy, she investigates how the respiratory chain complexes assemble and how structural variations may affect energy production and pathology.
The Lab’s Backbone
A great research environment doesn’t just depend on bold ideas. It also relies on the people who keep things running. GenOXPHOS is supported by a dedicated technical team:
Dr. María Concepción Jiménez Gómez, the lab manager, keeps operations smooth and organized.
Eva Raquel Martínez brings deep expertise in histology and molecular biology techniques.
Dr. Raquel Martínez de Mena oversees tissue culture and cell maintenance.
María del Mar Muñoz Hernández, the lab’s mouse technician, specializes in advanced animal procedures critical for the in vivo and translational work.
MitoWorld: The text notes that you enjoy thinking about “crazy” ideas. What is the “craziest” idea that intrigues you now?
One idea I’ve had for years is to replace the electron transport chain, complex I, III, and IV, for only two proteins. One would be an NADH dehydrogenase from yeast (for example NDi1), and the other would be an alternative oxidase (AOX). These can move electrons from NADH to oxygen, bypassing the traditional complex I/III/IV pathway. But here’s the crazy part: they don’t pump protons. That’s where proteorhodopsin comes in. It’s a light-driven proton pump. So, the idea is to express NDi1 and AOX in mitochondria to maintain redox balance and electron flux, and then express proteorhodopsin to regenerate the proton gradient using light. That proton gradient could then be used by ATP synthase to produce ATP.
But it gets even crazier. What if the AOX or NDi1 steps themselves could be engineered to emit light as a byproduct of electron transport? Then proteorhodopsin could be activated by that endogenous light, creating a feedback loop: electrons generate light, light drives proton pumping, protons drive ATP synthesis. In theory, with only three proteins—NDi1, AOX, and proteorhodopsin—we could reconstruct a functional, energy-producing electron transport system in mammalian mitochondria.
It’s very ambitious—perhaps impossible—but it has fascinated me since I was a student. The goal isn’t just synthetic biology, but to explore whether we can dissect the respiratory chain’s functions: electron flux, proton pumping, and ATP synthesis. These functions are often tightly coupled, but in biology, it’s not always beneficial for them to be. If we could separate them, we might gain insight into how they contribute independently to mitochondrial and cellular physiology. Whether I’ll ever be able to do it before the end of my career, who knows?
MitoWorld: A controversial hypothesis is that mitochondria move from cell to cell and that these transfers might serve as the basis for therapies. Do you have any thoughts about that possibility?
We not only have thoughts, but we also have experiments. In cardiac tissue, for example, mitochondria are packaged into membrane-bound structures we call “exopheres” and released. These are then taken up by neighbouring macrophages, which degrade them in a tightly regulated process. It’s a form of quality control but not necessarily a functional mitochondrial donation.
We’ve also shown, with Francisco Sánchez-Madrid, that mitochondrial components, especially mtDNA, can be transferred via immune synapses. The recipient cell sees that mtDNA as a danger signal, triggering antiviral responses.
Now, some studies—particularly in cancer—suggest that mitochondria can be taken up by recipient cells and remain functional, contributing to cell survival. However, while labeled mitochondria seem to transfer between cells, there’s little definitive evidence that they remain functional in the recipient cells or integrate into their networks.
The effects observed may often be immune related rather than metabolic. For instance, injecting mitochondria into blood has been proposed as a therapy, but the doses used are minuscule compared to endogenous mitochondrial populations in cells. Any physiological effects are more likely immune-mediated than due to actual mitochondrial “colonization.”
So, I think mitochondrial transfer happens, yes, but mainly as a signaling or quality control process. The notion of mitochondria behaving like autonomous, transferrable symbionts is still speculative.
MitoWorld: Can you speculate on how cells might regulate the specialization of mitochondria?
Between cell types, it’s mostly transcriptional regulation: different cells express different mitochondrial proteins or isoforms. But even within a single cell, mitochondria can be very different. One possible explanation is temporal regulation. A cell might express different sets of mitochondrial proteins at different times (e.g., day vs. night), and since mitochondria are relatively long-lived, this might create functionally distinct subpopulations. Another possibility is spatial regulation. Mitochondria traveling to different parts of the cell might encounter localized signals (e.g., specific mRNAs, post-translational modifiers, or regulators of protein import) that tune their function to local demands. In principle, if mitochondrial transfer between cells were robust, one could imagine specialized mitochondria being produced in one cell type and shared with another. But again, that’s still speculative.
MitoWorld: The role of mitochondria in energy production ensures that they are critical to cell and organismal health. Do you have any thoughts on how this might translate directly to health and aging?
Here I take a somewhat contrarian view. I don’t believe mitochondria drive aging. Aging is ultimately a consequence of entropy, a physical rather than strictly biological phenomenon. Biological systems resist entropy via repair and homeostasis, but over time, these processes lose efficiency.
That said, mitochondrial dysfunction is certainly part of the picture. As the cell accumulates damage (e.g., lysosomal inefficiency, metabolic imbalance, chronic inflammation), mitochondrial quality suffers. But so does everything else. For example, if oxygenation drops in the blood, the heart compensates by beating harder. Chronic compensation leads to hypertrophy and, eventually, pathology. The failure isn’t just in one organ or cell type; it’s in the integrated function of the whole.
So, while supporting mitochondrial function can help maintain cellular health, it won’t “cure” aging. In other words, mitochondria reflect the overall fitness of the cell. They are important, yes, but not supreme. Many age-related interventions that “target mitochondria” probably act through broader systemic effects: diet, exercise, metabolic control.
MitoWorld: Reversal of ATP synthase is counterintuitive. As you note, it might suggest a role in mitochondrial quality control. Can you elaborate on this hypothesis?
This might seem controversial at first: consuming ATP to pump protons. But it makes sense when you consider that the mitochondrial membrane potential must be tightly regulated. If it drops too low, apoptosis can be triggered. If it gets too high, ROS levels rise. So, reverse ATP synthase activity is a safety valve. It helps maintain an optimal membrane potential, even if doing so costs energy. In this light, ATP synthase becomes not just a producer of energy but a key regulator of mitochondrial homeostasis.
MitoWorld: FGR and OM1A are encoded by the nuclear DNA and imported into the mitochondria. That suggests a complex process with multiple potential therapeutic targets. Do you have thoughts about the most effective mechanism to inhibit it if it is not simply the enzymatic activity?
The challenge is that these enzymes have multiple substrates. Inhibiting their entire activity entirely can have off-target effects. A better strategy is to selectively block their interaction with specific targets, while leaving other interactions intact. Now that we know their structures, we can start designing molecules that interfere with specific protein-protein interactions to disrupt pathological effects while preserving beneficial ones. This is a more nuanced and promising strategy for targeting multifunctional mitochondrial regulators.
MitoWorld: One of the key questions in mitochondrial biology is how the mitochondria and the nucleus work together to keep things running smoothly—or not—when something goes wrong. Do you think your population studies might help us understand that relationship better?
This is a very important question. One of the biggest challenges in mitochondrial biology is that most mitochondrial protein complexes are assembled from proteins encoded by two different genomes: the mitochondrial genome and the nuclear genome. This creates a need for very tight coordination between the two, despite the fact that they evolve at different rates and under different selective pressures.
From a population genetics perspective, we can use large datasets to ask: (I) Which positions in these proteins are highly conserved (i.e., intolerant to change)? (II) Which positions vary more across individuals or species (i.e., more permissive to variation)? Some variants in mtDNA are never observed in the population, suggesting they are incompatible with nuclear-encoded partners.
We recently created a database scoring every amino acid in mitochondrial and nuclear-encoded ETC proteins for its permissivity—how often it varies across species and individuals. This helps us identify evolutionarily constrained sites where mitonuclear compatibility is critical.
We also see that mitochondrial and nuclear subunits in physical contact tend to co-evolve, whereas regions not in contact evolve more independently. This helps us map critical interaction interfaces and might uncover regulatory hotspots we don’t yet understand.
So yes—population studies can teach us a lot about mitonuclear compatibility, evolutionary constraints, and potentially, disease susceptibility.
Preface:
If we consider that mitochondria are the power plants of the cell, it may come as no surprise that they house a complex array of molecular machines, fine-tuned to churn out copious amounts of energy. What is remarkable, however, is that the blueprints for this machinery are rolled up in two distinct genomes—one nuclear, the other mitochondrial. This dual-genome system presents both challenges and opportunities to the cell in its never-ending quest to produce energy and adapt to an ever-changing world.
Each day, we synthesize roughly our own body weight in adenosine triphosphate (ATP) molecules, the universal energy currency that powers nearly every biological function1. Mitochondria—abundant in virtually all human cells—are the primary source of this ATP, synthesizing it from the oxygen we breathe and the nutrients we consume. The molecular machines that perform this astonishing work, every moment of every day, are situated in the inner mitochondrial membrane (IMM) and are known as the respiratory complexes (RCs). Together, complexes I through IV create an electrochemical gradient of protons across the IMM; these protons subsequently pass through complex V, driving its rotary mechanism and catalyzing ATP synthesis.
For these RCs to function efficiently, nearly 100 protein subunits must assemble in the IMM—a feat made more complex by the need to coordinate expression across two separate genomes: the diploid nuclear genome and the numerous circular copies of mitochondrial (mt)DNA distributed throughout the dynamic mitochondrial network. Significant genetic mismatch between these genomes can result in mitonuclear incompatibility, disrupting OxPhos assembly and ATP production.
Although the molecular mechanism of OxPhos is coming into focus in increasingly granular detail, an ambitious new study—published in Cell Genomics, from the lab of José Antonio Enríquez—traces the fundamental role of evolution in shaping the RC subunits at both the population and individual levels2. Over the course of more than 6 years, the authors conducted detailed analyses of each of the OxPhos subunits, integrating comparative genomics, protein structural modeling, and rigorous statistical analysis to produce a comprehensive map of both the diversity and the evolutionary constraints operating within this critical energy-producing system.
Notably, examination of more than 2,500 genotypes in the 1000 Genomes Project revealed an unexpected plasticity in the extent to which individuals could assemble different versions of the OxPhos machinery, based on the inherent variability stemming from diploidy and heterozygosity (i.e., different versions of the same gene coming from maternal and paternal chromosomes). For example, over 90% of people analyzed in this study could assemble at least two configurations of complex I. In the cases of complexes IV and V, no individual could assemble only a single version of the molecular machines. Thus, contrary to prior assumptions, the OxPhos machinery is not a rigid structure but a dynamic ensemble, that assembles in multiple configurations, depending on an individual’s genetic makeup. Moreover, a systematic analysis of individual amino acid residues—encoded by mtDNA, X, or autosomal chromosomes—demonstrated that the mitochondrial genome, due to its elevated mutation rate, represents a key source of variation and adaptability in human populations.
To further probe the evolutionary dynamics of the OxPhos proteins, the authors developed a novel methodology, called ConScore, for evaluating the extent to which specific amino acid residues are conserved across evolution. How compatible OxPhos protein subunits may be with one another depends substantially on how well they fit together in the larger 3D macromolecular complexes. Therefore, interface residues (IFRs) represent key determinants of mitonuclear compatibility. While interface residues (IFRs) in nuclear-encoded subunits—particularly those encoded on autosomes—are highly conserved, those in mtDNA-encoded subunits are surprisingly variable. This increased plasticity likely reflects an evolutionary mechanism that facilitates compatibility between divergent nuclear and mitochondrial genomes, especially at heterologous binding sites.
Despite this flexibility observed in heterologous IFRs encoded by mtDNA, 65–75% of all OxPhos residues exhibit no variability. Moreover, for many OxPhos genes, one of the two alleles is preferentially expressed, a phenomenon known as allelic imbalance. This early developmental bias constrains which subunits are effectively produced, thereby limiting the potential variability at the protein level—even when multiple variants are present in the genome.
Overall, this study illuminates the evolutionary forces that shape the essential OxPhos machinery. It reveals how cells balance strict functional requirements with surprising structural plasticity—maintaining energy production while allowing adaptability through mechanisms like mtDNA variation, allelic imbalance, and isoform diversity. These findings deepen our understanding of mitochondrial biology and offer insights relevant to disease, aging, and speciation.
MitoWorld: Oxidative phosphorylation requires the coordinated assembly and activity of numerous protein subunits from the nuclear and mitochondrial genomes. What was the inspiration for your study, and what key gaps in knowledge did you aim to address at the outset?
Mito-nuclear incompatibilities are widely recognized not only as drivers of speciation but also as key contributors to mitochondrial diseases in humans. The goal of our study was to better understand the evolutionary trajectory of oxidative phosphorylation (OxPhos) from vertebrates to modern human populations at the finest possible resolution—down to individual amino acid residues. We focused on two main objectives. First, we aimed to identify evolutionary patterns among respiratory complexes or subunits, distinguishing them based on their coding genome or mode of inheritance (mtDNA-encoded, nuclear autosomal-encoded, or X-chromosome-linked). Second, we sought to refine the current understanding of functional constraint in human OxPhos proteins at the residue level, by comparing conservation patterns across nested phylogenetic scales: vertebrates, mammals, and primates. All analyses and interpretations were conducted with a strong emphasis on molecular 3D structures, which serve as the central framework of this work.
MitoWorld: From an evolutionary perspective, what key differences did you identify between the mitochondrial and nuclear genomes?
The behavior of these two genomes shows distinct variation in relation to the respiratory complexes, most notably in complexes I (CI) and IV (CIV). Our findings suggest that mitochondrial DNA (mtDNA) functions not only as an evolutionary driver, facilitating speciation, but also exhibits a continuous dynamic role. This supports the hypothesis that the capacity for change (defined by the mutational rate of mtDNA) is a conserved trait. At the population level, this capacity for change enables mtDNA to undergo selective sweeps that help to balance the heterozygosity in nuclear-encoded OxPhos subunits. The result is the emergence and maintenance of viable mitonuclear combinations that highlight a cooperative, co-evolutionary process between the two genomes.
MitoWorld: Your study integrated genomic analyses with structural data. How did bringing together information from these different disciplines enhance your overall understanding of the OxPhos system?
Genetics or genomics and structural biology, although developed and studied as independent branches of biology, are deeply interconnected. Genetic changes often gain biological and evolutionary significance when they manifest as phenotypic traits, particularly through alterations in proteins, whose function is closely tied to their 3D structure. Moreover, certain evolutionary trends can only be observed by examining their impact on protein structures, such as the differential evolutionary patterns in binding sites.
MitoWorld: You used extensive datasets like the 1000 Genomes Project and gnomAD v3. Were there any limitations or biases in these datasets that might affect how we interpret the variability and constraints you observed?
Certainly, these databases, while representing a significant effort to cover human variability, are far from a comprehensive picture of the human genetic diversity. Therefore, we complemented human variation data with comparative analyses across other phylogenetic groups, anchoring our interpretations in evolutionary conservation and maintaining a focus on human protein structures. This cross-species perspective allows us to broaden our understanding of the functional significance of specific residues by examining their tolerance to change.
MitoWorld: Throughout your analysis, what results did you find most unexpected, and how did they shift your view of the respiratory complexes?
One of our most surprising findings was the prominent role of heterozygosity as a critical source of individual genetic variability, supported by analysis from the 1,000 Genomes Project. In a biological system, such as OxPhos, which is governed by the interplay and coevolution of two separate genomes, this observation raised the fundamental question about how such variability is managed at the molecular level. This led us to investigate allelic imbalance as a possible mechanism. To delve deeper, we focused on a pronounced example (hybrids between subspecies). Our findings revealed that allelic imbalance serves not only as an evolutionary means to mitigate heterozygosity but also as an indicator of additional regulatory complexity. It directly impacts the precise coordination required for the expression and assembly of multi-component systems; mismatches in this process may predispose to disease. Another striking result was how strongly selective pressures shape the 3D landscape of functional constraints within OxPhos complexes. This 3D map reflects the intricate evolutionary pressures at play on protein structure and function at the residue level.
MitoWorld: To evaluate the extent to which individual amino acid residues of the respiratory complexes are conserved, you developed a methodology called ConScore. Can you explain how this works and why it can shed light on the impact of mutations in different regions of a protein?
ConScore measures how conserved a specific position in a protein is, helping us to understand how likely it is to tolerate mutations. It combines information from variations in humans and other species (using sequence alignments) to show which changes at that position are allowed by evolution.
MitoWorld: How do you think that ConScore could be leveraged to characterize the genetic underpinnings of different pathologies associated with OxPhos dysregulation, such as mitochondrial diseases, cancer, or neurodegeneration?
Benchmarking results suggest that the ConScore can be directly applied to variant prioritization. However, to realize its full clinical potential, we envision two complementary directions for future development. First, we aim to evaluate its applicability beyond OxPhos components, extending its use to proteins that interact with OxPhos pathways. Second, we propose incorporating ConScore as a feature within machine-learning models to develop a more refined tool for assessing the pathogenicity of mutations.
MitoWorld: Mitochondrial transplantation or transfer involves the incorporation of mitochondria through different strategies, such as injection, vesicular transport, or intercellular bridges. Your study highlights the importance of mitonuclear incompatibility. How can we potentially optimize the coordinated expression and function of the hundred or so OxPhos subunits in the context of potential therapies?
Our previous work already found that this may be a relevant issue from a clinical point of view (PMID: 35236094; PMID: 32832682; PMID: 31588014; PMID: 27383793). Here we developed and refined in silico models of the OxPhos respiratory complexes that can be used to investigate ConScore-guided sequence variations in nuclear and mtDNA-encoded OxPhos components to anticipate compatibility issues, supporting further research in this area.
MitoWorld: Your work suggests that the high mutation rate of mtDNA is not just a vulnerability but may be an adaptive feature. Do you think that mtDNA mutability itself has been selected for during evolution?
The answer is yes. The symbiosis that led to the origin of eukaryotic cells incorporated mtDNA from the very beginning. Therefore, the mutation rate of each chromosome, including the mtDNA, has been optimized for evolutive success. This idea was also suggested by Wallace in 2010. In our study, we observed that, compared to nuclear-encoded subunits, the variability in mtDNA-encoded subunits is higher between species (with some exceptions, depending on the respiratory complex) and within human populations. Moreover, interface residues in mtDNA-encoded subunits show greater variability than other regions of the same proteins, suggesting a relaxation of selective constraints that is maintained even among humans.
These patterns support the idea that mtDNA mutability should not be understood as a vulnerability, but rather an evolved feature that contributes to functional flexibility and adaptive potential, especially in the context of mito-nuclear coevolution. The increased mutation rate in mtDNA could allow more rapid exploration of sequence space, enabling compensatory adaptations in response to changes in nuclear-encoded partners or environmental pressures. While more evidence is needed to confirm whether mtDNA mutability itself has been directly selected for, our results are consistent with the hypothesis that this feature plays an adaptive role in fine-tuning oxidative phosphorylation and maintaining mito-nuclear compatibility.
MitoWorld: What are some big outstanding questions relating to how evolution molds the OxPhos machinery?
Well, a challenge to address is investigating the functional differences in the OxPhos system among phylogenetic groups and their adaptive significance across various ecosystems. This exploration should occur at the residue, protein, respiratory complex, and supercomplex level.
References:
1. Lane, Nick (2018) Power, Sex, Suicide: Mitochondria and the Meaning of Life. Oxford University Press, Oxford, UK.
2. Cabrera-Alarcón JL, Rosa-Moreno M, Sánchez-García L, Agustín PH, Jiménez-Gómez MC, Martínez F, Sánchez-Cabo F, Enríquez JA (2025) Structural diversity and evolutionary constraints of oxidative phosphorylation. Cell Genom. 100945. doi: 10.1016/j.xgen.2025.100945. Epub ahead of print. PMID: 40614727.
We are happy to announce that Dr. Dane M. Wolf, recently an EMBO Long-Term Fellow at the University of Cambridge, is starting his own mitochondrial microscopy consultancy and will serve as MitoWorld’s Director of Microscopy.
Wolf is a mitochondrial biologist specializing in advanced imaging technologies. He completed his PhD at Boston University and University of California, Los Angeles, where he used live-cell super-resolution microscopy to study the structure-function relationship of mitochondrial cristae. As an EMBO Long-Term Fellow at the University of Cambridge, he investigated mitochondrial (mt)DNA dynamics using cutting-edge imaging approaches.
Wolf founded MitoGraphica, a scientific consultancy focused on mitochondrial image analysis and research, to support both academia and industry. He is deeply passionate about mitochondria and is committed to advancing and communicating our understanding of their vital roles in human health and longevity.
“In my lab, Dane became an imaging virtuoso,” said Dr. Orian Shirihai, Wolf’s PhD mentor, “not just because of his technical skill, but because of his creativity and attention to detail. What he’s built with MitoGraphica is a natural extension of his scientific work: a consultancy grounded in rigor, reliability, and precision. He brings not only innovation and vision, but also the discipline to deliver timely, well-documented, statistically sound solutions to complex image analysis challenges—something the field truly needs.”
MitoWorld: You assembled a nice slide deck (download PPTX) tour of some of the imagery you produced while at UCLA. Can you say a little bit about what we see in that deck?
Wolf: It’s an overview of the imaging that I performed at UCLA. The lab focused not only on the role of mitochondria in single cells, but also on how they regulate metabolism across the body. I spent a lot of time imaging a pancreatic β cell line (INS-1) and primary hepatocytes—which carry out the bulk of the liver’s metabolic activity. The deck also includes images of antibody-producing B cells undergoing mitosis in response to a stimulatory signal, along with super-resolution imaging of cristae, lipid droplets, lysosomes, and mtDNA in a variety of cell types.
The main takeaway from this set of images is that virtually all eukaryotic cells are densely populated with mitochondria. They inhabit the cell almost like individuals in a village—exhibiting complex behaviors, being born and dying, in a manner of speaking—and recent work suggests they take on specialized roles within the broader cellular environment. Remarkably, mitochondria can even travel between cells via membranous bridges or vesicles, coming to the aid of stressed neighbors.
MitoWorld: Which came first, your interest in mitochondria or imaging? How did the two evolve together for your work at UCLA and then Cambridge?
Wolf: I’ve been interested in the biology of aging for as long as I can remember. Since mitochondria are central to cellular homeostasis—and their dysfunction is closely linked to the systemic decline associated with aging—my interest in mitochondria came first. That said, it wasn’t until I began my PhD and saw live mitochondria under a confocal microscope that this interest grew from an abstract, academic curiosity into something visceral and compelling. There’s something truly captivating about looking through a microscope and watching thousands of mitochondria wiggle and dart around a field of cells, sometimes undergoing fusion and fission. In those moments, mitochondria seem to exhibit their own kind of behavior. That sense of wonder made me want to follow them more closely, and I became increasingly focused on developing approaches that would allow me to visualize them in greater spatiotemporal detail. The more clearly you can see them— really scrutinize their movements—the more their inner life begins to emerge, in surprising and often beautiful ways.
MitoWorld: During your PhD at UCLA in the Shirihai Lab, what were you trying to accomplish with imaging that you or the lab thought was beneficial, and how did this work add to the field of mitochondrial microscopy?
Wolf: In Orian’s lab, there has always been a strong emphasis on mitochondrial dynamics—how mitochondria move, divide, and fuse. As a PhD student, I was fortunate to have a great deal of freedom to explore, and at UCLA, we had access to cutting-edge super-resolution imaging technologies. One of these systems, Airyscan, allowed us to visualize mitochondria beyond the optical diffraction limit, opening up new possibilities for studying their complex internal structures in live cells.
By optimizing this technology, we developed methods to resolve the inner mitochondrial membrane in living cells. Using membrane-potential-sensitive dyes, we discovered that cristae—the characteristic folds of the inner membrane—were more polarized than other regions, and that individual cristae within the same mitochondrion could display distinct membrane-potential signatures. This supported a new model of the proton motive force, in which the electrical potential that drives ATP synthesis is compartmentalized at individual cristae. In this model, each crista functions like a miniature battery within the larger mitochondrion—much like how a Tesla battery pack is made up of many smaller battery cells (see Wolf et al., 2019).
This level of compartmentalization is thought to enhance energy efficiency. Just as importantly, it provides a form of bioenergetic buffering—if one crista becomes damaged or dysfunctional, it doesn’t compromise the entire organelle. Crista-level autonomy hadn’t been fully appreciated before, and this work added a new layer of understanding to mitochondrial resilience and function.
MitoWorld: Can you briefly describe the range of imaging techniques that you used to investigate mitochondria and how they aid in fundamental research?
Wolf: The imaging techniques that we used are primarily Airyscan and structured illumination microscopy (SIM), two different types of extended or super-resolution microscope. Airyscan employs a 32-channel GaAsP detector array in place of a traditional single-point detector, allowing it to capture more spatial information from the Airy disk of emitted light. Each detector element collects light from a slightly different position, and the combined data are computationally reconstructed to enhance both resolution and signal-to-noise ratio. This approach enables imaging beyond the diffraction limit, down to approximately 120 nm in the x-y plane. Airyscan is also highly sensitive, allowing us to image mitochondria using relatively low laser power. This reduced phototoxicity was critical for measuring membrane potential, as mitochondria are prone to depolarization when exposed to laser-induced stress.
SIM, by contrast, works by projecting striped patterns of light onto a sample from multiple angles and phases. These patterns create moiré interference with fine cellular structures, effectively shifting high-resolution information into a detectable range. By capturing a series of these patterned images and applying computational reconstruction, SIM achieves resolution beyond the optical diffraction limit—down to approximately 120 nm or roughly twice the resolution of conventional confocal microscopy.
Without super-resolution techniques, we wouldn’t be able to resolve the fine details of mitochondrial architecture without resorting to electron microscopy, which requires fixation or freezing, ruling out real-time measurements of structure and function. To truly understand something, you have to see how it moves. Super-resolution microscopy allows us to visualize the dynamics of mitochondria’s innermost structures, shedding light on core aspects of their function.
MitoWorld: What other works of yours might be forthcoming?
Wolf: In many ways, my work in Cambridge built upon the skill set I developed at UCLA. I applied a combination of super-resolution and 4D imaging to investigate the dynamics of the mitochondrial genome. This work is still unpublished, so I can’t go into detail just yet, but I’m looking forward to sharing it with the community, as I believe it offers new insights into fundamental aspects of mitochondrial function.
MitoWorld: Where do you think the field will go over the next 5 years? What do you hope to perfect and investigate over this time?
Wolf: Naturally, it is difficult to predict where the field will go. But if I had to guess, I’d say mitochondrial biology will become increasingly integrated with other disciplines. There’s a growing recognition that mitochondria are fundamental to a wide range of cellular functions, and mitochondrial dysfunction has emerged as a hallmark of an expanding list of diseases.
We’ve known since the mid-20th century that mitochondria are the cell’s powerhouses. A conceptual leap at the end of that century was the realization that they also play a central role in determining whether a cell lives or dies. The 21st century has brought about a renaissance in mitochondrial biology, with new discoveries revealing their involvement in diverse physiological contexts—from maintaining stem cell identity to driving specific cancer behaviors through shifts in metabolic activity.
I’m particularly interested in the role of mitochondria in the aging process. Finding new ways to preserve or rescue mitochondrial function, especially under stress, will likely be essential in efforts to combat age-related diseases such as neurodegeneration. And of course, I am always working to stay at the forefront of imaging technology, as visualizing mitochondrial behavior in ever-increasing detail continues to unlock new insights.
MitoWorld: How do you hope to shape your business, and what services can you bring to labs to improve or design their microscopy for cutting-edge research?
Wolf: After studying mitochondria for over a decade, I’ve come to appreciate that mitochondrial shape is a powerful indicator of function. This isn’t surprising—structure and function are fundamentally intertwined. Understanding how and why mitochondria change shape can reveal important clues about their physiological state, which in turn affects cellular and even organismal homeostasis.
That said, accurately measuring mitochondrial morphology is far from trivial. It requires not only high-quality imaging, but also the expertise to use specialized analysis platforms capable of segmenting and quantifying complex mitochondrial networks. Interpreting these changes—and uncovering the mechanisms behind them—can be especially challenging for researchers who aren’t specialists in mitochondrial dynamics or function.
Given the growing interest in mitochondria across both industry and academia, I founded www.MitoGraphica.com to make this expertise more accessible. The goal is to support researchers who want to image mitochondria but need guidance, as well as those who already have images but require expert help with analysis and interpretation. Ultimately, progress in both basic biology and therapeutic development depends on rigorous experimental design and accurate data. I want MitoGraphica to be a reliable resource—ensuring that anyone studying mitochondrial function has access to the tools, insights, and support needed to do it well.
If our website is MitoWorld, the Mechanisms of Mitochondrial DNA Mutation and Repair conference was the introductory gathering of what could be called “mtDNA World.”
The organizers, Patrick Chinnery (Cambridge), Agnel Sfeir (Sloan Kettering) and Michal Minczuk (Cambridge), emphasized that this conference focused solely on mtDNA is a first of its kind.
“This brand-new conference will focus on understanding how mitochondrial DNA mutations occur in the germ line and somatic tissues with age and how they contribute to common diseases, including neurodegeneration and cancer. The conference will also cover mitochondrial DNA’s molecular and cellular consequences and new approaches to repair and remove mutations.” [conference website]
The global mitochondria conference circuit generally is focused on mitochondria themselves (often in primary mitochondrial disease) in all their complexity with a smaller percentage of presentations on mtDNA itself. In Nashville, June 1–5, about 75 individuals representing labs globally, went deep into a range of heteroplasmy dynamics over lifetimes and in various disease and dysfunction cases. There was a sense of the importance of mtDNA and its relationship with the nuclear DNA as a primary and secondary driver of disease and dysfunction and also as part of the fundamental aging process.
“The result was an interactive meeting that highlighted the current multi-functional nature of mtDNA (beyond its known role in ATP production) and the cutting-edge new techniques and approaches now available to understand how mtDNA genes are expressed, how mtDNA mutations contribute to human physiology and pathology, and how we can now edit mtDNA or otherwise modulate this maternally inherited genome to improve human health,” said Gerry Shadel (Salk Institute).
The conference was very participatory and, since it was held in Nashville, ended with an evening of line dancing.
In the words of some of the organizers and attendees:
Agnel Sfeir, Organizer, Sloan Kettering
The meeting exceeded our expectations in every way. The quality of the science, the level of engagement, and the sense of community were truly exceptional. One of our goals was to create a space that fostered open discussion across disciplines and career stages, and I think we succeeded, which was evident by the engagement of trainees, the quality of their presentations, and the insightful questions they asked.
Dmitry Temiakov, Thomas Jefferson University
The conference’s exclusive focus on mitochondrial DNA was both timely and highly valuable for the scientific community. By concentrating on mtDNA, the meeting brought together researchers across diverse disciplines—from genetics and structural biology to clinical medicine—who might otherwise not engage in direct dialogue. This focused format fostered in-depth discussions on unresolved questions, including the mechanisms underlying mitochondrial diseases, maternal inheritance, and the role of mtDNA in inflammation and aging.
Maria Falkenberg, The Falkenberg Lab, University of Gothenburg
The meeting was a unique and refreshing experience, being the first to focus only on mtDNA. It gave space for interesting discussions that went all the way from basic science to possible new treatments. The talks covered many parts of mtDNA biology, from how it is maintained to how it can be targeted in disease. It was great to see the community come together around a topic that is often included in bigger meetings, but not usually the main focus.
Gerald Shadel, Salk Institute
Our genome comprises nuclear and mitochondrial DNA, both of which are essential for life and contribute to human diseases and aging. The biology and genetics of mtDNA is complex due to it being present in multiple (often thousands) copies/cell and its sequence dynamically changing in our bodies as we age. While there are many meetings on nucleic acids (DNA and RNA), genetics and even mitochondria, rarely is mtDNA a central theme. This FASEB meeting was therefore unique by focusing a lens on mtDNA and effectively bringing together many of the senior researchers who have long influenced our understanding of mtDNA with exciting new investigators in the field.
Carlos T. Moraes, University of Miami
It was right time for a meeting focused on my favorite genome (mtDNA). There have been so many advances in our understanding and manipulation of mtDNA in the last few years, and it was exhilarating to hear and discuss them with experts and colleagues. My recent area of work is mtDNA editing, and new techniques have opened a whole area of investigations and therapeutic development. As always, new knowledge raises many questions, so this meeting was a great forum to generate new ideas and how to overcome barriers, such as the off-target edits of mtDNA base editing.
Amutha Boominathan, MitoSENS
The conference provided a comprehensive overview of recent advances in mitochondrial DNA research, with a strong focus on its role in cellular function and pathology. A key highlight was the application of advanced sequencing technologies to resolve mitochondrial heteroplasmy at the single-cell level and to establish genotype-phenotype correlations. It brought together students and junior and established researchers, with particular emphasis on emerging topics, such as mitochondrial regulation of immune responses, novel metabolic functions, and targeted approaches to silence/modulate the mitochondrial genome. The meeting was highly interactive and engaging. Looking forward to the follow-up!
Olvia Conway, Duke University
This meeting was extremely valuable to me as a trainee because of the networking and learning opportunities available. My mtDNA project is a new area for the lab, so this meeting was a way to meet others focused on this topic, receive feedback on some of my early work, and determine in which direction the field is heading. I am grateful for the opportunity to talk to other scientists during the conference sessions, and I am planning on implementing many of the suggestions I received. This was my first meeting as a graduate student, and I had a great experience.