bims-mitmed 2026-05-17 papers

bims-mitmed

Biomed News

on Mitochondrial medicine

Issue of 2026–05–17
23 papers selected by
Dario Brunetti, Fondazione IRCCS Istituto Neurologico

Single-molecule mitochondrial DNA imaging reveals heteroplasmy dynamics shaped by developmental bottlenecks and selection in vivo.
In the absence of mitochondrial fusion unequal segregation of mitochondria drives mtDNA loss.
170 Years of Mitochondrial Research and the Emergence of Mitochondrial Medicine.
Mitochondrial transfer technologies with molecular insights into clinical applications.
AMPK: a master regulator of mitochondrial quality and quantity.
Predicting recurrence risk of leigh syndrome using prenatal mtDNA heteroplasmy assessment.
Mammalian mtDNA gene expression: Concepts learned from in vivo models.
Mitochondrial morphology in human fibroblasts and induced pluripotent stem cells in Leigh syndrome: A comparative analysis.
Therapeutic Impact of Mitochondrial Transplants for Cardiovascular Diseases.
Therapeutic activity of a hematopoietic stem cell-delivered cell-penetrating frataxin in Friedreich's ataxia models.
α-Synuclein aggregates induce mitochondrial damage and trigger innate immunity to drive neuron-microglia communication.
Intra-mitochondrial glycolysis maintains mitochondrial function and underlies the pathogenesis of retinitis pigmentosa.
Therapeutic potential of mitochondrial transfer in reversing mutant-to-wild-type mtDNA ratio and improving mitochondrial dysfunction in 1555A>G mtDNA mutation-associated hearing loss.
Whole-blood NAD+ levels do not reflect healthy ageing.
Structural basis for prohibitin-mediated regulation of mitochondrial m-AAA protease.
Assessing Mitochondrial Respiratory Complex-Associated Function From Previously Frozen Mouse Placental Tissue.
Advancing Deep Variant Phenotyping of Mitochondrial Enzyme Complexes For Precision Medicine in Allogeneic Hematopoietic Stem-Cell Transplantation.
Human whole-blood NAD+ levels do not vary with age or lifestyle interventions.
MICU proteins facilitate calcium-dependent mitochondrial metabolon formation to regulate cellular energetics independently of MCU.
Transplantation of encapsulated mitochondria alleviates dysfunction in mitochondrial and Parkinson's disease models.
Mitochondrial ROS Production at Complexes I and III in Human Myocardium and Skeletal Muscle: A Distinct Pattern Compared with Rat Tissue.
Essential role of METTL3 in mitochondrial function and epigenetic regulation during preimplantation development in mice.
Placental Secretome: Uncovering the Vast Signals Shaping Fetal Metabolic Health Trajectory.

Dev Cell. 2026 May 13. pii: S1534-5807(26)00123-1. [Epub ahead of print]61(5): 1146-1161.e8

Single-molecule mitochondrial DNA imaging reveals heteroplasmy dynamics shaped by developmental bottlenecks and selection in vivo.

Rajini Chandrasegaram, Sara Gottardo, Abhilesh Dhawanjewar, Antony M Hynes-Allen, Beitong Gao, Suvagata Roy Chowdhury, Luis-Carlos Tábara, Michele Frison, Stavroula Petridi, Patrick F Chinnery, Julien Prudent, Hansong Ma, Jelle van den Ameele.

  Mitochondrial DNA (mtDNA) exists in many copies per cell, with cell-to-cell variability in mutation load, which is known as heteroplasmy. Developmental and age-related expansion of heteroplasmic mtDNA mutations contributes to the pathogenesis of mitochondrial and neurodegenerative diseases. Here, we describe an approach for in situ sequence-specific detection of single mtDNA molecules (mtDNA-single-molecule fluorescent in situ hybridization [smFISH]). We apply this method to visualize and measure mtDNA and heteroplasmy levels in situ at single-cell resolution in whole-mount Drosophila tissue and cultured human cells. In Drosophila, we identify a somatic mtDNA bottleneck during neurogenesis. This amplifies heteroplasmy variability between neurons, as predicted by a mathematical bottleneck model, predisposing individual neurons to a high mutation load. However, both during neurogenesis and oogenesis, mtDNA segregation is accompanied by purifying selection, promoting wild-type (WT) over pathogenic mtDNA. mtDNA-smFISH thus elucidates how developmental cell-fate transitions, accompanied by changes in cell morphology, behavior, and metabolism, can shape the transmission and selection of deleterious mtDNA variants.

Keywords:  Drosophila; bottleneck; heteroplasmy; mitochondria; mitochondrial DNA; mitochondrial disease; neurogenesis; oogenesis; purifying selection; single-molecule fluorescent in situ hybridization

DOI:  https://doi.org/10.1016/j.devcel.2026.03.011
EMBO Rep. 2026 May 14.

In the absence of mitochondrial fusion unequal segregation of mitochondria drives mtDNA loss.

Lisa Dengler, Francesco Padovani, Bianca Lemke, Rebecca Brugger, Alissa Benedikt, Benedikt Westermann, Boris Maček, Kurt M Schmoller, Jennifer C Ewald.

Mitochondrial biogenesis and inheritance must be tightly coordinated with cell division to maintain mitochondrial function and cell survival. The dynamics of the mitochondrial network, including fusion and fission, are essential for mitochondrial inheritance and quality control. In budding yeast, simultaneous inhibition of both processes compromises mitochondrial DNA (mtDNA) integrity, increasing the frequency of petite cells. Loss of fusion alone completely eliminates mtDNA. Although this has been known for decades, why mtDNA is lost remained unclear. Here, we examine the effects of impaired mitochondrial fusion by depleting the mitofusin Fzo1. By analyzing over thirty thousand single cells across their cell cycles, we show that Fzo1-depletion induces rapid mitochondrial fragmentation and loss of membrane potential, followed by progressive declines in mtDNA content and growth rate. During division, Fzo1-depleted daughters inherit disproportionately large mitochondrial amounts, leaving mothers with too little. This imbalance, combined with an inability to upregulate compensatory mtDNA synthesis, drives rapid mtDNA loss. Our results reveal how fusion defects cause mtDNA loss and mitochondrial dysfunction, which might have implications for diseases linked to impaired fusion.

DOI: https://doi.org/10.1038/s44319-026-00794-5
J Clin Pharmacol. 2026 May;66(5): e70209

170 Years of Mitochondrial Research and the Emergence of Mitochondrial Medicine.

Volkmar Weissig.

  One hundred and sixty-eight years lie between the first description of mitochondria as "pale roundish granules" and their eventual recognition as the "chief executive organelle" of the cell. Booming mitochondrial research during the last three decades has revealed that being the "powerhouse of the cell" is just one of many fundamental roles mitochondria play for cellular life. Mitochondria are at the crossroads of complex metabolic pathways; they regulate cellular signaling and innate immunity, and they determine whether a cell should divide, differentiate, or die. Human disorders caused by malfunctioning mitochondria have been described starting at the beginning of the 1960s, nowadays, it seems widely accepted that there are hardly any human diseases anymore that are not associated with dysfunctioning mitochondria. Even the process of aging seems to be controlled by this powerful organelle. This review is written for Pharmacologists, Physicians, and Healthcare Providers who are not familiar with mitochondrial biology and with the tremendous insights gained during the last three decades into the vital roles this cell organelle plays for life and death. It is aimed at raising awareness of still underappreciated mitochondrial diseases, which represent the largest group of inborn errors of metabolism.

Keywords:  aging; apoptosis; cellular signaling; drug development; energy metabolism; immunity; mitochondria; mitochondrial diseases

DOI:  https://doi.org/10.1002/jcph.70209
Stem Cells. 2026 May 07. pii: sxag026. [Epub ahead of print]

Mitochondrial transfer technologies with molecular insights into clinical applications.

Vahan Martirosian, Berney Peng, Michael A Teitell.

  Mitochondria are essential cell signaling, survival, and bioenergetic organelles that uniquely harbor a maternally inherited, multicopy genome called mitochondrial DNA (mtDNA). The occurrence or accumulation of mtDNA mutations underlies a spectrum of inherited and acquired mitochondrial syndromes and diseases and is increasingly recognized as a source of metabolic plasticity, clonal fitness, and therapy tolerance in cancer. Recent studies have revealed mitochondrial transfer as a potential mode of intercellular communication that could compensate for mtDNA mutation-associated mitochondrial dysfunction. Transfer of mitochondria can restore homeostasis in stressed recipient cells by rebuilding respiratory capacity, rebalancing redox state, and reshaping cell fate. Reported mechanisms of transfer include tunneling nanotubes, extracellular vesicles, cell fusion, and others, such as macropinocytosis. Here, we review and evaluate emerging technologies developed for mitochondrial transfer studies and define the impact of transfer on cell physiology and pathology. We discuss translational opportunities for mitochondrial transfer-based interventions, as well as how mitochondrial exchange may represent a new framework for understanding tumor heterogeneity, adaptation, and aggressiveness.

Keywords:  Mitochondria; Mitochondrial transfer; mtDNA; techniques; transplantation

DOI:  https://doi.org/10.1093/stmcls/sxag026
Trends Cell Biol. 2026 May 12. pii: S0962-8924(26)00066-8. [Epub ahead of print]

AMPK: a master regulator of mitochondrial quality and quantity.

Reuben J Shaw, Ian G Ganley, Julien Prudent, D Grahame Hardie.

  The AMP-activated protein kinase (AMPK) may have arisen soon after the endosymbiosis event that generated eukaryotes, perhaps to allow the archaeal host to communicate its requirements for ATP to the bacterial endosymbionts that became mitochondria. Consistent with this, AMPK is now known to regulate most aspects of the mitochondrial life cycle. It drives fragmentation of the network by promoting fission and inhibiting fusion, increasing mitochondrial number while allowing isolation of dysfunctional fragments from the network. It promotes the biogenesis of new mitochondrial components while also regulating mitophagy, promoting the degradation of dysfunctional mitochondria and inhibiting the removal of functional mitochondria. We will discuss these new findings and propose that the regulation of mitochondria was an ancient function of AMPK originating in the early eukaryote.

Keywords:  endosymbiosis; mitochondrial biogenesis; mitochondrial fission; mitochondrial fusion; mitophagy; origin of eukaryotes

DOI:  https://doi.org/10.1016/j.tcb.2026.04.008
Mitochondrion. 2026 May 13. pii: S1567-7249(26)00055-3. [Epub ahead of print] 102165

Predicting recurrence risk of leigh syndrome using prenatal mtDNA heteroplasmy assessment.

Maria Shishimorova, Hong Ma, Amy Koski, Crystal Van Dyken, Nuria Marti Gutierrez, Daniel Frana, Ying Li, Daniel Eyberg, Sergei Tevkin, Tomonari Hayama, Eunju Kang, Paula Amato, Kevin Havlin, Christopher Goodier, Roger Newman, Sally Shields, Shoukhrat Mitalipov.

  Predicting recurrence risk for mitochondrial DNA (mtDNA) disorders is challenging because heteroplasmy levels can shift during development. We examined whether prenatal heteroplasmy measurements predict postnatal outcomes for the pathogenic m.13513G > A variant associated with Leigh syndrome. In a longitudinal family-based study involving three naturally conceived pregnancies, mtDNA heteroplasmy was assessed by chorionic villus sampling at 10-12 weeks of gestation and, when available, amniocentesis at 16 weeks, with follow-up in neonatal and postnatal tissues. Prenatal heteroplasmy levels below ∼30% were associated with unaffected outcomes, whereas an affected sibling exhibited near-homoplasmic variant loads in critical organs. These findings suggest prenatal heteroplasmy assessment may inform recurrence risk for the mtDNA m.13513G > A disorder.

Keywords:  Chorionic villus sampling; Heteroplasmy; Leigh syndrome; Mitochondrial DNA; Prenatal diagnosis

DOI:  https://doi.org/10.1016/j.mito.2026.102165
Biochim Biophys Acta Mol Cell Res. 2026 May 13. pii: S0167-4889(26)00056-X. [Epub ahead of print] 120158

Mammalian mtDNA gene expression: Concepts learned from in vivo models.

Diana Rubalcava-Gracia, Nils-Göran Larsson.

Mammalian mitochondrial DNA (mtDNA) expression is essential for oxidative phosphorylation (OXPHOS) and its in vivo regulation requires significant refinement. Here, we review key insights from mouse models carrying genetic modifications to the mtDNA expression machinery. While in vitro studies defined the basic machinery, mouse models reveal that mitochondrial transcription often exceeds immediate needs and may not be the primary rate-limiting step for OXPHOS biogenesis. Instead, mitochondria produce a transcript surplus regulated by nucleoid compaction and post-transcriptional stabilization. This apparent excess capacity is uncoupled from protein output under basal conditions but becomes critical during physiological stress or pathology. Using current and emerging genetic tools, researchers are now deciphering how regulatory layers coordinate to sustain systemic energy demands. These lessons highlight the importance of in vivo systems for identifying regulatory control points of mtDNA expression and developing targeted therapies for mitochondrial disorders.

DOI: https://doi.org/10.1016/j.bbamcr.2026.120158
Physiol Rep. 2026 May;14(9): e70911

Mitochondrial morphology in human fibroblasts and induced pluripotent stem cells in Leigh syndrome: A comparative analysis.

Fibi Meshrkey, Ajibola B Bakare, Raj R Rao, Shilpa Iyer.

  Mitochondria are dynamic organelles that regulate several vital cellular functions in both health and disease. Accurately quantifying different mitochondrial shapes using simple, affordable techniques remains challenging. We have previously developed a Mitochondrial Cellular Phenotype (MitoCellPhe) tool to quantify 24 different mitochondrial shapes, enabling sensitive analysis and quantification of mitochondrial phenotype in health, under stress, and in diseased conditions. This approach permits us to study the morphological changes, if any, associated with perturbations in the mitochondrial genome and function that contribute to mitochondrial diseases like Leigh Syndrome (LS), a fatal pediatric neurodegenerative and muscular disorder represented with different clinical phenotypes in infancy. Using images generated from normal and diseased fibroblasts and human induced pluripotent stem cells (hiPSCs) (undifferentiated), we have identified and characterized differences in morphologies between a healthy and diseased state in both undifferentiated hiPSCs and differentiated fibroblasts. These results will help us better understand the pathophysiology of devastating mitochondrial diseases like LS, especially in its early developmental stages.

Keywords:  mitochondria; morphology; networks; stem cells; structure

DOI:  https://doi.org/10.14814/phy2.70911
Int J Mol Sci. 2026 Apr 30. pii: 4018. [Epub ahead of print]27(9):

Therapeutic Impact of Mitochondrial Transplants for Cardiovascular Diseases.

Konstantina Antoniadou, Ioannis Shiammoutis, Christina Piperi.

  Mitochondria are vital organelles for human cells with fundamental roles in major metabolic processes such as calcium homeostasis, ATP production, apoptosis and signal transduction. Defective morphology and activity of these organelles have been tightly associated with the pathological onset of severe human disorders, including cardiovascular diseases. Targeting mitochondrial dysfunction has been an area of extensive research encompassing several approaches ranging from pharmacological agents to mitochondrial replacement techniques. Among them, mitochondrial transplantation has been a rapidly evolving approach, especially in the field of cardiovascular dysfunction for the restoration of injured or damaged myocardial cells. Various methods including tunneling nanotubes, nanoblade and "mitopunch" ensure the effective mitochondrial transfer from the donor to the recipient cell, with the internalization of the organelles, via endocytosis, enabling functional restoration. Results of preclinical and clinical trials involving mitochondrial transfer support the application of this technique in improving the function of the myocardium after damage caused by ischemia reperfusion injury. Herein, we discuss the beneficial role of mitochondrial transplantation in cardiovascular diseases and the current technical challenges of mitochondrial isolation, preservation, and targeted delivery, as well as their role in advancing precision medicine, offering a patient tailored therapeutic approach.

Keywords:  CVD; ischemia/reperfusion injury; mitochondrial replacement therapy; mitochondrial transplantation; mtDNA

DOI:  https://doi.org/10.3390/ijms27094018
Cell Rep Med. 2026 May 13. pii: S2666-3791(26)00220-X. [Epub ahead of print] 102803

Therapeutic activity of a hematopoietic stem cell-delivered cell-penetrating frataxin in Friedreich's ataxia models.

Jeffrey Pido-Lopez, Shefta E Moula, Enas Shaban, Konstantinos Stamatiou, Bethan J Critchley, Thomas E Whittaker, Stina Svensson, Sara Anjomani-Virmouni, Ester Kalef-Ezra, Lucinda Carr, Jane Hassel, Adrian J Thrasher, Manju A Kurian, Ian A Blair, Teerapat Rojsajjakul, Giorgia Santilli, Arturo Sala.

  Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by a GAA repeat expansion in the frataxin (FXN) gene, leading to reduced frataxin, a protein essential for mitochondrial function. We developed a replacement strategy using a fusion protein containing secretion and cell-penetrating sequences fused to the frataxin precursor. In vitro studies confirmed secretion, cellular penetration, mitochondrial localization, and rescue of biochemical defects and apoptosis in cells from patients with FRDA. The therapeutic cDNA was cloned into a lentiviral vector and used to transduce hematopoietic stem and progenitor cells (HSPCs) from YG8sR mice, an FRDA model. Autologous transplantation of modified HSPCs produced stable peptide secretion in the bloodstream and delayed the onset of motor coordination symptoms, accompanied by improved biochemical and anatomical parameters. Patient-derived CD34+ HSPCs transduced with the vector differentiated normally into macrophages and secreted the peptide. These results support a cell and gene therapy strategy for long-term stabilization of FRDA.

Keywords:  ataxia; behavioural assays; cell and gene therapy; cell-penetrating peptide; frataxin; hematopoietic stem cells; mitochondria; secretory peptide.; transplantation

DOI:  https://doi.org/10.1016/j.xcrm.2026.102803
Nat Commun. 2026 May 15.

α-Synuclein aggregates induce mitochondrial damage and trigger innate immunity to drive neuron-microglia communication.

Ranabir Chakraborty, Stephanie Maya, Veronica Testa, Jara Montero-Muñoz, Takashi Nonaka, Masato Hasegawa, Antonella Consiglio, Chiara Zurzolo.

Tunneling nanotubes (TNTs) enable direct intercellular transfer of macromolecules, organelles, and pathogenic protein aggregates. While α-synuclein (α-Syn) aggregates are known to promote TNT formation, the underlying mechanisms remain poorly defined. Here, using human neuronal and microglial cell lines, as well as iPSC-derived dopaminergic neurons and microglia, we show that α-Syn aggregates induce severe mitochondrial damage, leading to cytosolic release of mitochondrial DNA (mtDNA) and activation of the cGAS-STING-NF-κB-IRF3 pathway. This innate immune response drives actin cytoskeleton remodeling and the formation of TNT-like structures, promoting intercellular transfer of α-Syn from neurons to microglia. Additionally, neuronal cells transfer damaged mitochondria to microglia, where they undergo lysosome-mediated degradation. Neuron-to-microglia communication under α-Syn-induced stress also triggers a bystander inflammatory response in microglia, suggesting a neuroimmune activation. Our findings identify mitochondrial damage and STING-mediated inflammation as key drivers of TNT formation and α-Syn propagation, highlighting potential targets to modulate disease progression in Synucleinopathies.

DOI: https://doi.org/10.1038/s41467-026-73136-7
Nat Commun. 2026 May 12.

Intra-mitochondrial glycolysis maintains mitochondrial function and underlies the pathogenesis of retinitis pigmentosa.

Linghui Kong, Jiajian Liang, Dan Liu, Shanshan Jia, Hui Gu, Yiwen He, Wenting Luo, Songying Cao, Yizhang Dong, Chao Yang, Minghui Liao, Guojia Wan, Bo Du, Dongxue Ding, Wei Ma, Xiaowei Wei, Anhua Wu, Zhengwei Yuan.

Glycolysis is classically defined as a cytoplasmic process. Here, in our investigation of mitochondrial dysfunction in Retinitis Pigmentosa (RP), we report the unexpected discovery of a complete and functional glycolytic pathway operating inside mitochondria. Through CoIP-MS, polysome profiling, and [U-13C] glucose isotope tracing, we demonstrate that key glycolytic enzymes are locally translated and metabolically active within the organelle. Mechanistically, we show that the VWA8-PHB2-GRP75 complex is responsible for anchoring these enzymes, thereby sustaining intra-mitochondrial glycolysis and preserving mitochondrial function by regulating NAD+ levels and reactive oxygen species (ROS) homeostasis. In vivo, Vwa8 knockout in both mice and zebrafish abolishes this metabolic safeguard, leading to RP-like phenotypes that can be partially rescued by reactivating mitochondrial glycolysis. Collectively, these findings redefine the spatial compartmentalization of glucose metabolism and establish mitochondrial glycolysis as a therapeutic target for mitochondrial diseases.

DOI: https://doi.org/10.1038/s41467-026-72988-3
Sci Rep. 2026 May 13.

Therapeutic potential of mitochondrial transfer in reversing mutant-to-wild-type mtDNA ratio and improving mitochondrial dysfunction in 1555A>G mtDNA mutation-associated hearing loss.

Yujin Kim, Chang-Hee Kim, Dong Woo Nam, Bong Jik Kim, Ngoc-Trinh Tran, Jin Hee Han, Minyoung Kim, Shin-Hye Yu, Seo-Eun Lee, Jeong Seon Yeo, Iksun Kwon, Kyuboem Han, Chun-Hyung Kim, Young Cheol Kang, Byung Yoon Choi.

  Mitochondrial DNA (mtDNA) mutations are a major cause of sensorineural hearing loss (SNHL). The m.1555A >G mutation in the mitochondrial 12S rRNA gene is closely linked to nonsyndromic and aminoglycoside-induced hearing loss, leading to impaired oxidative phosphorylation (OXPHOS) and ATP production. Current treatments focus on auditory rehabilitation without addressing mitochondrial pathology. This study investigated mitochondrial transplantation as a therapeutic approach. Fibroblasts from two patients with homoplasmic m.1555A > G mutations identified during cochlear implant surgery received allogeneic mitochondria (PN-101) derived from human umbilical cord mesenchymal stem cells. Transplantation significantly increased intracellular ATP levels, complex I activity, and OXPHOS protein expression, while protecting against kanamycin-induced mitochondrial dysfunction. Importantly, PN-101 induced a heteroplasmy shift toward wild-type mtDNA, with repeated treatments sustaining and enhancing this effect. These findings demonstrate that PN-101-mediated mitochondrial transplantation improves mitochondrial bioenergetics and modulates mtDNA heteroplasmy in m.1555A > G mutant cells, suggesting a promising disease-modifying therapy for mtDNA-related hearing loss and a potential precision medicine approach.

Keywords:  Hearing loss; Heteroplasmy; Mitochondrial transplantation; PN-101; mtDNA 1555A >G mutation

DOI:  https://doi.org/10.1038/s41598-026-51402-4
Nat Metab. 2026 May 14.

Whole-blood NAD+ levels do not reflect healthy ageing.

DOI: https://doi.org/10.1038/s42255-026-01540-w
Nat Commun. 2026 May 13.

Structural basis for prohibitin-mediated regulation of mitochondrial m-AAA protease.

Dingyi Luo, Lvqin Zheng, Ming-Ao Lu, Ziyao Chen, Panpan Wang, Qiang Guo, Ning Gao.

Mitochondrial function critically depends on protein quality control systems, with the m-AAA protease playing a key role at the inner mitochondrial membrane (IMM). The evolutionarily conserved prohibitins (PHBs) are essential modulators of this protease across species, yet the molecular mechanisms remain unclear. Here, we present the cryo-EM structure of the Chaetomium thermophilum PHB (CtPHB) complex, revealing a cage-like assembly composed of 11 copies of PHB1/PHB2 heterodimers. Electron microscopic and biochemical analyses suggest that m-AAA proteases are enclosed within the PHB complex through interactions mediated by their SPFH-interacting motif (SIM) exposed in the intermembrane space. Further in situ cryo-ET directly visualizes these cage-protease assemblies in native mitochondria. Disruption of their interface leads to elevated m-AAA protease activity and diminished mitochondrial stress resistance. These data establish PHB complexes as spatial organizers that compartmentalize m-AAA proteases in membrane microdomains to fine-tune proteolytic homeostasis. Our findings reveal the critical role of the PHB complex in maintaining mitochondrial proteostasis, providing a unified mechanistic model to explain and reconcile the pleiotropic and often contradictory phenotypes of PHB and m-AAA protease in mitochondrial physiology and various disease conditions.

DOI: https://doi.org/10.1038/s41467-026-73040-0
Bio Protoc. 2026 May 05. 16(9): e5667

Assessing Mitochondrial Respiratory Complex-Associated Function From Previously Frozen Mouse Placental Tissue.

Tina Podinic, Donald Xhuti, Cristina Monaco, Joshua P Nederveen, Sandeep Raha.

  The placenta is a metabolically active organ whose mitochondrial activity is tightly linked to fetal growth, oxygenation, and nutrient transport, mediating fetal susceptibility to environmental exposures. Accordingly, aberrant mitochondrial function has been implicated in the progression of placental dysfunction. However, existing respirometry platforms require primarily fresh or cryopreserved placental tissue and offer limited throughput, rendering these platforms impractical in the context of large-scale placental dissections. Here, we describe and validate a Seahorse XF approach for measuring mitochondrial respiration in previously frozen placentae, enabling the functional interrogation of placental mitochondria in prenatal studies. Our protocol fundamentally relies on the restoration of matrix substrates that are depleted due to increased mitochondrial membrane permeability following freeze-thaw cycles. We provide a strategy to assess complex I and II-associated respiration adapted for the Seahorse XFe24 Analyzer and further demonstrate comparable oxygen consumption readouts between fresh and frozen placentae. We further demonstrate distinct differences in the magnitude of oxygen consumption between fresh and frozen placentae in the absence of exogenous NADH. Taken together, we present a simplified and convenient protocol for the assessment of respiratory enzyme complex-associated respiration from archived placental tissue. Key features • This protocol is suitable for use with previously frozen mouse placental tissue. • Streamlined protocol for complex-associated respirometry assessments following large-scale placental dissections. • Respirometry data may be acquired in <4 hours.

Keywords:  Bioenergetics; Electron transport-chain enzyme activity; Fresh tissue; Frozen tissue; Metabolism; Mitochondria; Oxygen consumption; Placenta; Respiration; Respirometry

DOI:  https://doi.org/10.21769/BioProtoc.5667
Transpl Rep. 2025 Feb;pii: 100171. [Epub ahead of print]10(1):

Advancing Deep Variant Phenotyping of Mitochondrial Enzyme Complexes For Precision Medicine in Allogeneic Hematopoietic Stem-Cell Transplantation.

Jing Dong, Michael T Zimmermann, Neshatul Haque, Shahram Arsang-Jang, Wael Saber, Xiaowu Gai, Raul Urrutia.

Allogeneic hematopoietic stem-cell transplantation (allo-HCT), an early developed methodology for precision medicine, remains the only curative therapy for myelodysplastic syndromes (MDS). However, allo-HCT carries significant risks of morbidity and mortality due to relapse and transplant-related complications. Recurrent mutations in mitochondrial DNA (mtDNA) have been identified as significant prognostic indicators for MDS outcomes following allo-HCT. However, the biological mechanisms of mtDNA mutations remain unclear. Thus, here we performed deep variant phenotyping by integrating computational biophysics and structural genomics approaches to reveal the molecular mechanisms underlying mtDNA variant dysfunction. This emerging genomics discipline employs structural models, molecular mechanic calculations, and accelerated molecular dynamic simulations to analyze gene products, focusing on their structures and motions that determine their function. We applied this methodology on the variants in the mitochondria-encoded complex I genes that are associated with MDS pathobiology and prognosis after allo-HCT. Our results demonstrate that this approach significantly outperforms conventional analytical methods, providing enhanced and more accurate information to support the potential pathogenicity of these variants and better infer their dysfunctional mechanisms. We conclude that the adoption and further expansion of computational structural genomics approaches, as applied to the mitochondrial genome, have the potential to significantly increase our understanding of molecular mechanisms underlying the disease. Our study lays a foundation for translating mitochondrial biology into clinical applications, which will advance the integration of precision medicine with allo-HCT.

DOI: https://doi.org/10.1016/j.tpr.2025.100171
Nat Metab. 2026 May 14.

Human whole-blood NAD+ levels do not vary with age or lifestyle interventions.

Maria M Trętowicz, Angelique M L Scantlebery, Bauke V Schomakers, Kaan D Eroğlu, Michel van Weeghel, Vera Spek, Kasper T Vinten, Luc Legon, Evrim Coskun, Fernando Millan-Domingo, Gloria Olaso-Gonzalez, Maria Carmen Gomez-Cabrera, Silvia Montoro-García, Clara Noguera-Navarro, André B P van Kuilenburg, Sofia Moco, Juliette C van Hattum, Harald T Jørstad, Mohammed Benali, Jantine van der Helder, Esmee J M Biersteker, Maheswary Muniandy, Kirsi H Pietiläinen, Eija Pirinen, P Eline Slagboom, Marian Beekman, Joris Deelen, Rubén Zapata-Pérez, Peter J M Weijs, Michael Tieland, Georges E Janssens, Riekelt H Houtkooper.

Nicotinamide adenine dinucleotide (NAD+) levels in blood and tissues are widely proposed to decline with age, yet evidence in human blood is inconsistent. Using a rigorously validated ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry system that accounts for real-world analytical variability, we quantify NAD+ across seven independent human cohorts. We find that whole-blood NAD+ levels remain remarkably stable with age and across lifestyle interventions, but change in response to nicotinamide riboside supplementation, as expected. Our results challenge the utility of blood NAD+ levels as a biomarker of ageing or lifestyle factors.

DOI: https://doi.org/10.1038/s42255-026-01537-5
Nat Metab. 2026 May 13.

MICU proteins facilitate calcium-dependent mitochondrial metabolon formation to regulate cellular energetics independently of MCU.

Henry M Cohen, Benjamin Gottschalk, Carmen Choya-Foces, Adam Chatoff, Anya Wilkinson, Elena Berezhnaya, Joanne F Garbincius, Adyson Johnson, Tyler L Stevens, Jordan E Howe, Hailey Lesniak, Anna Schmidt, Jennyfer Ngo, Emily Megill, Dhanendra Tomar, Nathaniel W Snyder, Wolfgang F Graier, John W Elrod.

Mitochondrial matrix Ca2+ concentration ([Ca2+]m) is theorized to be an essential regulator of mitochondrial metabolism by positively regulating key mitochondrial dehydrogenases. However, ablation or functional inhibition of the mitochondrial calcium uniporter channel (mtCU) fails to significantly perturb basal metabolism and is largely phenotypically silent in the absence of stress. Here we demonstrate that MICU proteins, the reported gatekeepers of mtCU, function in coordination to impart calcium-dependent regulation to FADH2-dependent mitochondrial dehydrogenases through metabolon formation independently of the mtCU and [Ca2+]m. Our results demonstrate that MICU proteins differentially localize to mitochondrial microdomains and form heterodimers and interactomes in response to intermembrane space Ca2+ binding their respective EF-hand domains. Using an equimolar expression platform coupled with unbiased proteomics, we reveal unique interactomes for MICU1/MICU2 versus MICU1/MICU3 heterodimers and demonstrate that MICU proteins control coupling of mitochondrial glycerol-3-phosphate dehydrogenase and succinate dehydrogenase/complex II and impart calcium-dependent changes in activity. We propose that MICU-mediated mitochondrial metabolons are a fundamental system facilitating matching of mitochondrial energy production with cellular demand and is the primary physiological calcium signaling mechanism regulating homeostatic energetics, not mtCU-dependent changes in [Ca2+]m.

DOI: https://doi.org/10.1038/s42255-026-01513-z
Cell. 2026 May 14. pii: S0092-8674(26)00521-0. [Epub ahead of print]

Transplantation of encapsulated mitochondria alleviates dysfunction in mitochondrial and Parkinson's disease models.

Shiwei Du, Qi Long, Yanshuang Zhou, Jiangqin Fu, Hao Wu, Liang Yang, Yaohang Xie, Yingzhe Ding, Maolei Zhang, Jingyi Guo, Mengfei Wang, Jiajun Lin, Mingli Hu, Jian Zhang, Deyang Yao, Wei Li, Feixiang Bao, Ge Xiang, Yi Wu, Yile Huang, Haozhao Liang, Rui Wang, Heying Li, Baodan Chen, Chong Li, Junwei Wang, Jiwei Zhang, Dajiang Qin, Jianwei Sun, Yun Zhu, Fei Sun, Wuming Wang, Gang Lu, Wai-Yee Chan, Hui Zhao, Chenli Liu, Xingguo Liu.

DOI: https://doi.org/10.1016/j.cell.2026.05.004
Cells. 2026 May 01. pii: 830. [Epub ahead of print]15(9):

Mitochondrial ROS Production at Complexes I and III in Human Myocardium and Skeletal Muscle: A Distinct Pattern Compared with Rat Tissue.

Ivan Mihanovic, Jasna Marinovic, Cristijan Bulat, Bruno Luksic, Zlatko Marovic, Marko Ljubkovic.

  Mitochondrial reactive oxygen species (ROS) play a central role in cardiac ischemia/reperfusion injury, heart failure, and arrhythmogenesis, while also serving essential signaling functions under physiological conditions. Among the eleven identified mitochondrial ROS-producing sites, complexes I and III are considered the major contributors, particularly under conditions of impaired electron flow. However, much of the existing knowledge comes from rodent models or cultured cells and is often assumed to apply to humans. Here, ROS production from complexes I and III was measured directly in human myocardial and skeletal muscle biopsies and compared with corresponding rat tissues under identical experimental conditions. Hydrogen peroxide generation was quantified using Amplex UltraRed, with simultaneous monitoring of mitochondrial respiration using a Clark-type oxygen electrode. Across all examined mechanisms-reverse and forward electron transport at complex I and the ubiquinol oxidation site of complex III, rat tissues produced more ROS than human tissues, consistent with their higher respiratory rates. However, the dominant ROS-producing sites differed: in rats, complex III was the primary source, whereas in human tissues the highest ROS production occurred during reverse electron transport at complex I. When normalized to respiration, human tissues showed relatively greater ROS generation at complex I but markedly lower production at complex III. These direct measurements of mitochondrial ROS production in human myocardium provide new insight into cardiac redox physiology and may explain the limited clinical translation of cardioprotective strategies targeting mitochondrial ROS production, such as interventions aimed at modulating reperfusion injury or preconditioning.

Keywords:  complex I; complex III; human myocardium; mitochondrial ROS hierarchy; mitochondrial reactive oxygen species; skeletal muscle

DOI:  https://doi.org/10.3390/cells15090830
Reproduction. 2026 May 14. pii: xaag059. [Epub ahead of print]

Essential role of METTL3 in mitochondrial function and epigenetic regulation during preimplantation development in mice.

Dan Liu, Xinyao Chen, Yuwei Gao, Haoxue Wang, Naojiro Minami, Shinnosuke Honda, Shuntaro Ikeda.

  Methyltransferase-like 3 (METTL3) is a key enzyme involved in N6-methyladenosine (m6A) RNA modification. METTL3 affects mitochondrial function via its well-known contribution to RNA translation and stability. Since METTL3 is essential for proper gene expression and mitochondrial function, we hypothesized that METTL3 plays a role in mouse preimplantation development via mitochondrial function and RNA metabolism. Mettl3-targeting antisense oligonucleotides were introduced to one-cell stage embryos to knock down its expression in mouse embryos. The resultant embryos were subjected to the detection analysis of m6A, Hippo signaling, histone methylation, mitochondrial reactive oxygen species (mtROS), mitochondrial DNA (mtDNA) copy number and membrane potential at the morula stage. RNA sequencing was also conducted to identify differentially expressed genes in Mettl3 knockdown embryos. Mettl3 knockdown resulted in significant developmental impairments, including decreased blastocyst formation, reduced cell number, elevated mtROS levels, and increased mtDNA copy number. Histone H3 lysine 27 trimethylation levels, a repressive histone mark, were also altered in the nuclei of knockdown embryos. Reanalysis of public RIP-seq data revealed that METTL3 inhibition alters m6A in transcripts of Hippo signaling key components and H3K27me3 modifiers in mouse preimplantation embryos. Additionally, Mettl3 knockdown altered the expression of genes related to RNA metabolism, mitochondrial activity, and protein folding. Our findings highlight the essential role of METTL3 in preimplantation development by influencing cell proliferation, mitochondrial function, and epigenetic regulation.

Keywords:  METTL3; N6-methyladenosine; mitochondria; preimplantation embryo

DOI:  https://doi.org/10.1093/reprod/xaag059
Curr Opin Physiol. 2026 Jun;pii: 100944. [Epub ahead of print]48

Placental Secretome: Uncovering the Vast Signals Shaping Fetal Metabolic Health Trajectory.

Seokwon Jo, Emilyn U Alejandro, Megan Beetch.

  Predisposition to metabolic disease may start during pregnancy, when the intrauterine environment profoundly influences fetal development. The placenta secretes an array of proteins, hormones, metabolites, and extracellular vesicles that coordinate maternal adaptation and fetal development. Beyond classical hormones, emerging evidence reveals a broader placental secretome that regulates metabolic tissue maturation and programming. Maternal health dynamically shapes placental signaling, influencing fetal growth and long-term health trajectory. Advances in proteomics, organoids, and maternal-fetal sampling uncover secretion patterns and networks critical for fetal health programming. Understanding how the placental secretome shapes offspring health trajectories provides a crucial window for intervention to stop the intergenerational cycle of metabolic disease.

Keywords:  DOHaD; Hormone; Metabolism; Placenta; Secretome

DOI:  https://doi.org/10.1016/j.cophys.2026.100944