bims-miptne 2025-03-16 papers

bims-miptne

Biomed News

on Mitochondrial permeability transition pore-dependent necrosis

Issue of 2025–03–16
fifteen papers selected by
Oluwatobi Samuel Adegbite, University of Liverpool

Calciprotein particle-induced calcium overload triggers mitochondrial dysfunction in endothelial cells.
Enhancement of mitochondrial calcium uptake is cardioprotective against maladaptive hypertrophy by retrograde signaling uptuning Akt.
Trifluoroacetic Acid Induced a Cyclophilin D-Dependent Cognitive Impairment in Mice.
Appraising histone H4 lysine 5 lactylation as a novel biomarker in breast cancer.
VDAC2 and Bak scarcity in liver mitochondria enables targeting hepatocarcinoma while sparing hepatocytes.
Functional Nucleic Acid Nanostructures for Mitochondrial Targeting: The Basis of Customized Treatment Strategies.
Lactate: A key regulator of the immune response.
Immune suppression sustained allograft acceptance requires PD1 inhibition of CD8+ T cells.
Programmable mRNA therapeutics for controlled epigenomic modulation of single and multiplexed gene expression in diverse diseases.
L- and D-Lactate: unveiling their hidden functions in disease and health.
Mitochondrial Dysfunction in Cardiovascular Diseases.
Exploring novel biomarkers and immunotherapeutic targets for biofeedback therapies to reveal the tumor-associated immune microenvironment through a multimetric analysis of kidney renal clear cell carcinoma.
Labeling of mitochondria for detection of intercellular mitochondrial transfer.
Identification of determinants for variability in mitochondrial biochemical complex activities.
Electron Microscopy to Visualize and Quantify Mitochondrial Structure and Organellar Interactions in Cultured Cells During Senescence.

J Physiol. 2025 Mar 09.

Calciprotein particle-induced calcium overload triggers mitochondrial dysfunction in endothelial cells.

Lian Feenstra, Laurent Chatre, Benoit Bernay, Julien Pontin, Mirjam F Mastik, Azuwerus van Buiten, Dalibor Nakládal, Bastiaan S Star, Jan-Luuk Hillebrands, Guido Krenning.

  Calciprotein particles (CPPs) are calcium- and phosphate-containing nanoparticles numbers of which are increased in patients with chronic kidney disease (CKD). CPPs have been associated with the development of vascular disease, although the underlying mechanisms are unknown. We previously showed that CPPs induce endothelial cell (EC) dysfunction by reducing nitric oxide (NO) bioavailability and generating superoxide (O2 .-). Here, we tested the hypothesis that CPPs induce mitochondrial calcium (Ca2+) overload, which may trigger mitochondrial dysfunction and, consequently, EC activation. Exposure of human umbilical vein ECs to CPPs resulted in significantly increased cytosolic and mitochondrial Ca2+ levels compared to vehicle-treated ECs. Proteome analysis demonstrated impaired endoplasmic reticulum calcium signalling, and decreased enrichment of proteins in the mitochondrial OXPHOS complexes I-III in CPP-exposed ECs. Respirometry data confirmed these findings and demonstrated decreased basal and maximal respiration in CPP-exposed ECs. This was accompanied by reduced mitochondrial membrane potential, reduced antioxidant capacity and loss of mitochondria. In the presence of cyclosporin A, a potent mitochondrial permeability transition pore inhibitor, CPP-induced EC activation and cell death were attenuated. Taken together, our data indicate that CPP-induced Ca2+ overload is an important trigger of mitochondrial dysfunction, and EC activation and cell loss, which eventually may contribute to the development of vascular diseases in CKD. Interventions that target CPP-induced mitochondrial dysfunction might preserve EC function and possibly alleviate the development of vascular diseases in CKD. KEY POINTS: Calciprotein particles (CPPs) are calcium- and phosphate-containing nanoparticles numbers of which are increased in patients with chronic kidney disease and which have been associated with the development of vascular disease. In this study, we tested the hypothesis that CPPs induce mitochondrial calcium (Ca2+) overload in endothelial cells, thereby triggering mitochondrial dysfunction and endothelial activation. We show that exposure of HUVECs (human umbilical vein endothelial cells) to CPPs results in increased cytosolic and mitochondrial Ca2+ levels, which is associated with alterations in mitochondrial processes (proteome analysis), cellular respiration, mitochondrial integrity and number. CPP-induced EC activation and cell death were attenuated in the presence of cyclosporin A, a potent mitochondrial permeability transition pore inhibitor. Our data indicate that CPP-induced Ca2+ overload triggers mitochondrial dysfunction, endothelial activation and cell loss. Interventions that target CPP-induced mitochondrial dysfunction might preserve EC function in chronic kidney disease.

Keywords:  calciprotein particle (CPP); calcium ion; chronic kidney disease (CKD); endothelial cell; mitochondrial dysfunction; mitochondrion; vascular calcification

DOI:  https://doi.org/10.1113/JP287656
Proc Natl Acad Sci U S A. 2025 Mar 18. 122(11): e2402639122

Enhancement of mitochondrial calcium uptake is cardioprotective against maladaptive hypertrophy by retrograde signaling uptuning Akt.

Tania Zaglia, Antonio Campo, Nicola Moro, Vittoria Di Mauro, Giulia Borile, Roberta Menabò, Salvatore Antonucci, Laura Poli, Marika Campesan, Pierluigi Carullo, Sara Martinazzi, Giovanni B Luciani, Karin Hammer, Paola Pesce, Riccardo Bariani, Giuseppe Faggian, Lars Maier, Laura Ventura, Diego De Stefani, Cristina Mammucari, Rosario Rizzuto, Daniele Catalucci, Fabio Di Lisa, Marco Mongillo.

  Regulation of mitochondrial Ca2+ uptake is critical in cardiac adaptation to chronic stressors. Abnormalities in Ca2+ handling, including mitochondrial uptake mechanisms, have been implicated in pathological heart hypertrophy. Enhancing mitochondrial Ca2+ uniporter (MCU) expression has been suggested to interfere with maladaptive development of heart failure. Here, we addressed whether MCU modulation affects the cardiac response to pressure overload. MCU content was quantified in human and murine hearts at different phases of myocardial hypertrophy. Cardiac function/structure were analyzed after Transverse Aortic Constriction (TAC) in mice undergone viral-assisted overexpression or downregulation of MCU. In vitro and ex vivo assays determined the effect of MCU modulation on mitochondrial Ca2+ uptake, cellular phenotype and hypertrophic signaling. In human and murine hearts MCU levels increased in the adaptive phase of myocardial hypertrophy and declined in the failing stage. Consistently, modulation of MCU had a cell-autonomous effect in cardiomyocyte/heart adaptation to chronic overload. Indeed, upon TAC MCU-downregulation accelerated development of contractile dysfunction, interstitial fibrosis and heart failure. Conversely, MCU-overexpression prolonged the adaptive phase of hypertrophic response, as, in advanced stages upon TAC, hearts showed preserved contractility, absence of fibrosis and intact vascularization. In vitro and ex vivo analyses indicated that enhancement in mitochondrial Ca2+ uptake in cardiomyocytes entails "mitochondrion-to-cytoplasm" signals leading to ROS-mediated activation of Akt, which may explain the protective effects towards heart response to TAC. Enhanced mitochondrial Ca2+ uptake affects the compensatory response to pressure overload via retrograde mitochondrial-Ca2+/ROS/Akt signaling, thus uncovering a potentially targetable mechanism against maladaptive myocardial hypertrophy.

Keywords:  Akt; beta adrenergic receptor; heart failure; mitochondrial calcium uniporter; myocardial hypertrophy

DOI:  https://doi.org/10.1073/pnas.2402639122
Aging Dis. 2025 Feb 26.

Trifluoroacetic Acid Induced a Cyclophilin D-Dependent Cognitive Impairment in Mice.

Yun Li, Yichi Xu, Yuanlin Dong, Christa J Nehs, Zhongcong Xie, Yiying Zhang.

Studies have linked inhalation anesthesia and surgery to increased cognitive impairment, particularly in the elderly. Our previous research showed that isoflurane, but not desflurane, affected cognitive function in mice by modulating cyclophilin D (CypD), a key regulator of the mitochondrial permeability transition pore (mPTP) and mitochondrial function. Both anesthetics metabolize into trifluoroacetic acid (TFA), which is associated with cognitive deficits. However, the specific role of CypD in the TFA-induced mitochondrial dysfunction and cognitive impairments is unclear. This study aims to explore the interaction between TFA, CypD, and cognitive function in neurons and mice. TFA was administered to 2-3-month-old wild-type (WT) and CypD knockout (KO) female and male mice at 120 μg/kg and to primary cultured neurons from these mice at 10 μM. Immunofluorescence staining and Western blot analyses assessed the impact of TFA on the levels of CypD, voltage-dependent anion channel (VDAC), adenine nucleotide translocase (ANT), reactive oxygen species (ROS), and caspase-3 activation in neurons, along with cognitive function assessments in mice. The data from the present study demonstrated cognitive impairments in mice following TFA treatment. Elevated CypD and ROS levels were observed post-TFA exposure, alongside the TFA-induced caspase-3 activation in WT neurons and mice. Notably, the absence of CypD significantly mitigated these effects. The findings suggest that TFA-induced mitochondrial dysfunction, caspase-3 activation, and subsequent cognitive impairments rely on CypD expression, particularly in the hippocampus of mice. This study illuminates the molecular pathways influenced by anesthesia-related compound TFA and its impact on cognitive function.

DOI: https://doi.org/10.14336/AD.2024.1430
Sci Rep. 2025 Mar 10. 15(1): 8205

Appraising histone H4 lysine 5 lactylation as a novel biomarker in breast cancer.

Ya Zhu, Yuping Fu, Fengzhen Liu, Sha Yan, Ruili Yu.

  Background Posttranslational modifications of histone lysine (K) have integral connections with cell metabolism, and participate in the carcinogenesis of various cancers. This study focuses on evaluating the expression of histone H4 lys 5 lactylation (H4K5lac) and its clinical role in breast cancer (BC). Methods During this research, immunohistochemistry (IHC) and immunoblotting, utilizing a specific primary anti-L-lactyl-histone H4 (Lys 5) rabbit monoclonal antibody, were employed to assess H4K5lac expression in BC tissue chips. H4K5lac expression in the peripheral blood mononuclear cells (PBMCs) of BC patients was investigated through immunoblotting. Results IHC revealed upregulation of histone H4K5lac in both triple-negative breast cancer (TNBC) and non-TNBC tissues, with positive rate of 91.40% [170/(150 + 19 + 17)] and 93.64% (103/110) in TNBC and non-TNBC tissues, respectively. The expression of H4K5lac demonstrated positive correlations with lymph nodes (%), and Ki-67 expression. Survival analysis indicated a negative correlation between H4K5lac expression and overall survival (OS) time in both TNBC (HR [hazard ratio] = 2.773, 95%CI [confidence interval]: 1.128-6.851, P = 0.0384) and non-TNBC cases (HR = 2.156, 95%CI: 1.011-4.599, P = 0.0275). Furthermore, elevated levels of H4K5lac were observed in the PBMCs of BC cases, and H4K5lac expression is positively correlated with serum lactate and carcinoma embryonic antigen (CEA) levels. Conclusions Histone H4K5lac exhibits increased levels in both BC tissues and PBMCs, suggesting its potential as a promising biomarker for BC. This study might pave the way toward novel lactylation treatment strategies in BC.

Keywords:  Biomarker; Breast cancer; Histone H4K5lac; Lactylation; Prognosis

DOI:  https://doi.org/10.1038/s41598-025-92666-6
Nat Commun. 2025 Mar 11. 16(1): 2416

VDAC2 and Bak scarcity in liver mitochondria enables targeting hepatocarcinoma while sparing hepatocytes.

Shamim Naghdi, Piyush Mishra, Soumya Sinha Roy, David Weaver, Ludivine Walter, Erika Davies, Anil Noronha Antony, Xuena Lin, Gisela Moehren, Mark A Feitelson, Christopher A Reed, Tullia Lindsten, Craig B Thompson, Hien T Dang, Jan B Hoek, Erik S Knudsen, György Hajnóczky.

Differences between normal tissues and invading tumors that allow tumor targeting while saving normal tissue are much sought after. Here we show that scarcity of VDAC2, and the consequent lack of Bak recruitment to mitochondria, renders hepatocyte mitochondria resistant to permeabilization by truncated Bid (tBid), a Bcl-2 Homology 3 (BH3)-only, Bcl-2 family protein. Increased VDAC2 and Bak is found in most human liver cancers and mitochondria from tumors and hepatic cancer cell lines exhibit VDAC2- and Bak-dependent tBid sensitivity. Exploring potential therapeutic targeting, we find that combinations of activators of the tBid pathway with inhibitors of the Bcl-2 family proteins that suppress Bak activation enhance VDAC2-dependent death of hepatocarcinoma cells with little effect on normal hepatocytes. Furthermore, in vivo, combination of S63845, a selective Mcl-1 inhibitor, with tumor-nectrosis factor-related, apoptosis-induncing ligand (TRAIL) peptide reduces tumor growth, but only in tumors expressing VDAC2. Thus, we describe mitochondrial molecular fingerprint that discriminates liver from hepatocarcinoma and allows sparing normal tissue while targeting tumors.

DOI: https://doi.org/10.1038/s41467-025-56898-4
Molecules. 2025 Feb 24. pii: 1025. [Epub ahead of print]30(5):

Functional Nucleic Acid Nanostructures for Mitochondrial Targeting: The Basis of Customized Treatment Strategies.

Wanchong He, Siyu Dong, Qinghua Zeng.

  Mitochondria, as vital organelles, play a central role in subcellular research and biomedical innovation. Although functional nucleic acid (FNA) nanostructures have witnessed remarkable progress across numerous biological applications, strategies specifically tailored to target mitochondria for molecular imaging and therapeutic interventions remain scarce. This review delves into the latest advancements in leveraging FNA nanostructures for mitochondria-specific imaging and cancer therapy. Initially, we explore the creation of FNA-based biosensors localized to mitochondria, enabling the real-time detection and visualization of critical molecules essential for mitochondrial function. Subsequently, we examine developments in FNA nanostructures aimed at mitochondrial-targeted cancer treatments, including modular FNA nanodevices for the precise delivery of therapeutic agents and programmable FNA nanostructures for disrupting mitochondrial processes. Emphasis is placed on elucidating the chemical principles underlying the design of mitochondrial-specific FNA nanotechnology for diverse biomedical uses. Lastly, we address the unresolved challenges and outline prospective directions, with the goal of advancing the field and encouraging the creation of sophisticated FNA tools for both academic inquiry and clinical applications centered on mitochondria.

Keywords:  FNA nanostructures; customized treatment strategy; mitochondria

DOI:  https://doi.org/10.3390/molecules30051025
Immunity. 2025 Mar 11. pii: S1074-7613(25)00075-5. [Epub ahead of print]58(3): 535-554

Lactate: A key regulator of the immune response.

Alba Llibre, Salih Kucuk, Atrayee Gope, Michelangelo Certo, Claudio Mauro.

  Lactate, the end product of both anaerobic and aerobic glycolysis in proliferating and growing cells-with the latter process known as the Warburg effect-is historically considered a mere waste product of cell and tissue metabolism. However, research over the past ten years has unveiled multifaceted functions of lactate that critically shape and impact cellular biology. Beyond serving as a fuel source, lactate is now known to influence gene expression through histone modification and to function as a signaling molecule that impacts a wide range of cellular activities. These properties have been particularly studied in the context of both adaptive and innate immune responses. Here, we review the diverse roles of lactate in the regulation of the immune system during homeostasis and disease pathogenesis (including cancer, infection, cardiovascular diseases, and autoimmunity). Furthermore, we describe recently proposed therapeutic interventions for manipulating lactate metabolism in human diseases.

Keywords:  immune regulation; lactate; lactate sensing; lactate signaling; lactylation

DOI:  https://doi.org/10.1016/j.immuni.2025.02.008
J Immunol. 2025 Jan 01. 214(1): 192-198

Immune suppression sustained allograft acceptance requires PD1 inhibition of CD8+ T cells.

Hilary Miller-Handley, Gavin Harper, Giang Pham, Lucien H Turner, Tzu-Yu Shao, Abigail E Russi, John J Erickson, Mandy L Ford, Koichi Araki, Sing Sing Way.

  Organ transplant recipients require continual immune-suppressive therapies to sustain allograft acceptance. Although medication nonadherence is a major cause of rejection, the mechanisms responsible for graft loss in this clinically relevant context among individuals with preceding graft acceptance remain uncertain. Here, we demonstrate that skin allograft acceptance in mice maintained with clinically relevant immune-suppressive therapies, tacrolimus and mycophenolate, sensitizes hypofunctional PD1hi graft-specific CD8+ T cells. Uninterrupted immune-suppressive therapy is required because drug discontinuation triggers allograft rejection, replicating the requirement for immune-suppressive therapy adherence in transplant recipients. Graft-specific CD8+ T cells in allograft-accepted mice show diminished effector differentiation and cytokine production, with reciprocally increased PD1 expression. Allograft acceptance-induced PD1 expression is essential, as PDL1 blockade reinvigorates graft-specific CD8+ T cell activation with ensuing allograft rejection despite continual immune-suppressive therapy. Thus, PD1 sustained CD8+ T cell inhibition is essential for allograft acceptance maintained by tacrolimus plus mycophenolate. This necessity for PD1 in sustaining allograft acceptance explains the high rates of rejection in transplant recipients with cancer administered immune checkpoint inhibitors targeting PD1/PDL1, highlighting shared immune suppression pathways exploited by tumor cells and current therapies for averting allograft rejection.

Keywords:  T cells (cells); costimulation (processes); rodent (animal); transplantation (processes)

DOI:  https://doi.org/10.1093/jimmun/vkae007
Nat Commun. 2025 Mar 13. 16(1): 2517

Programmable mRNA therapeutics for controlled epigenomic modulation of single and multiplexed gene expression in diverse diseases.

Charles W O'Donnell, Jeremiah D Farelli, Houda Belaghzal, Justin Chen, Lauren Beech, James Sullivan, Chevaun Morrison-Smith, Stephen Siecinski, Adam Katz, Samuel Mildrum, Mayur Gurnani, Prachi Dhanania, Caitlyn R Webb, Giuliana Castello Coatti, Pranjali Rumale, Daniel F G Costa, Marcus I Gibson, Yaoyu E Wang, Joseph V Newman, Thomas G McCauley.

Pathogenic gene dysregulation can be attributed to chromatin state change that pre-transcriptionally regulates expression. Recent breakthroughs elucidating the rules governing this DNA control layer, an epigenetic code, unlock a modality in precision medicine to target gene dysregulation across myriad diseases. Here we present a modular platform to design programmable mRNA therapeutics, Epigenomic Controllers (EC), that control gene expression through directed epigenetic change. By leveraging natural mechanisms, ECs tune expression levels of one or multiple genes with durable effect of weeks-to-months in female mice following a single dose. We design and characterize ECs to multiple target genes and identify an EC that effectively inhibits the cancer- and inflammatory-disorder-associated multi-gene cluster CXCL1-8. With precision targeting of NF-kB signaling and identification of homologous murine surrogates, ECs significantly reduce neutrophil migration in vivo during acute lung inflammation in female mice. A platform approach to EC design for epigenomic modulation expands treatment frontiers for diverse gene targets, including those considered "undruggable."

DOI: https://doi.org/10.1038/s41467-025-57920-5
Cell Commun Signal. 2025 Mar 12. 23(1): 134

L- and D-Lactate: unveiling their hidden functions in disease and health.

Jianting Li, Peng Ma, Zhizhen Liu, Jun Xie.

  Lactate, once considered a mere byproduct of anaerobic metabolism, is now recognized as a critical signaling molecule with diverse roles in physiology and pathology. There are two stereoisomers of lactate: L- and D-lactate. Recent studies have shown that disruptions in these two lactate stereoisomers have distinct effects on health and disease. L-lactate is central to glycolysis and energy transfer through the Cori cycle but also acts as the dominant lactylation isomer induced by glycolysis, influencing metabolism and cell survival. Although less studied, D-lactate is linked to metabolic disorders and plays a role in mitochondrial dysfunction and oxidative stress. This review focuses on both L- and D-lactate and examines their biosynthesis, transport, and expanding roles in physiological and pathological processes, particularly their functions in cancer, immune regulation, inflammation, neurodegeneration and other diseases. Finally, we assess the therapeutic prospects of targeting lactate metabolism, highlighting emerging strategies for intervention in clinical settings. Our review synthesizes the current understanding of L- and D-lactate, offering insights into their potential as targets for therapeutic innovation.

Keywords:  D-lactate; Epigenetic; L-lactate; Lactylation; Metabolism

DOI:  https://doi.org/10.1186/s12964-025-02132-z
Int J Mol Sci. 2025 Feb 23. pii: 1917. [Epub ahead of print]26(5):

Mitochondrial Dysfunction in Cardiovascular Diseases.

Han-Mo Yang.

  Mitochondrial dysfunction is increasingly recognized as a central contributor to the pathogenesis of cardiovascular diseases (CVDs), including heart failure, ischemic heart disease, hypertension, and cardiomyopathy. Mitochondria, known as the powerhouses of the cell, play a vital role in maintaining cardiac energy homeostasis, regulating reactive oxygen species (ROS) production and controlling cell death pathways. Dysregulated mitochondrial function results in impaired adenosine triphosphate (ATP) production, excessive ROS generation, and activation of apoptotic and necrotic pathways, collectively driving the progression of CVDs. This review provides a detailed examination of the molecular mechanisms underlying mitochondrial dysfunction in CVDs, including mutations in mitochondrial DNA (mtDNA), defects in oxidative phosphorylation (OXPHOS), and alterations in mitochondrial dynamics (fusion, fission, and mitophagy). Additionally, the role of mitochondrial dysfunction in specific cardiovascular conditions is explored, highlighting its impact on endothelial dysfunction, myocardial remodeling, and arrhythmias. Emerging therapeutic strategies targeting mitochondrial dysfunction, such as mitochondrial antioxidants, metabolic modulators, and gene therapy, are also discussed. By synthesizing recent advances in mitochondrial biology and cardiovascular research, this review aims to enhance understanding of the role of mitochondria in CVDs and identify potential therapeutic targets to improve cardiovascular outcomes.

Keywords:  cardiovascular disease; mitochondrial dynamics; mitochondrial dysfunction; oxidative stress

DOI:  https://doi.org/10.3390/ijms26051917
Discov Oncol. 2025 Mar 13. 16(1): 311

Exploring novel biomarkers and immunotherapeutic targets for biofeedback therapies to reveal the tumor-associated immune microenvironment through a multimetric analysis of kidney renal clear cell carcinoma.

Guobing Wang, Jinbang Huang, Haiqing Chen, Chenglu Jiang, Lai Jiang, Wenqi Feng, Gang Tian.

   BACKGROUND: Kidney renal clear cell carcinoma (KIRC) constitutes the primary subtype of renal cell carcinoma, representing 75% to 80% of cases and carrying a substantial cancer-specific mortality rate of up to 24%. Despite advancements in treatment options, KIRC displays notable resistance to conventional therapies, emphasizing the need for innovative targeted immunotherapeutic strategies. Chromatin regulators (CRs), pivotal proteins controlling gene expression and critical biological processes, play a crucial role in the initiation and progression of KIRC. This study employed a multi-omics approach to evaluate the impact of CR-associated genes on KIRC prognosis.
METHODS: The study utilized the TCGA-KIRC dataset and employed LASSO Cox regression to construct and validate a prognostic model that focuses on genes influencing KIRC prognosis. The research investigated interactions among gene characteristics, clinical parameters, the tumor microenvironment, targeted immunotherapy, and drug responsiveness. Experimental validation, encompassing various techniques such as cell culture, transient transfection, qPCR, Transwell assays, confirmed the robust predictive capability of the BRD9 gene.
RESULTS: The analysis identified the risk score of CRs as an independent factor determining KIRC prognosis. Furthermore, the study introduced a predictive Nomogram model that integrates clinical attributes and risk assessment. Significantly, BRD9 exhibited substantially elevated expression within KIRC cells, underscoring its role in driving cancer cell proliferation, invasion, and migration. These findings suggest the potential for tailored immunotherapy targeting BRD9 in the treatment of KIRC.
CONCLUSION: This study presents an innovative prognostic framework for KIRC based on multi-omics approaches, seamlessly incorporating CRs. This model holds promise for improving the accuracy of prognosis prediction for KIRC patients, laying a robust foundation for the development of targeted immunotherapies.

Keywords:  Biofeedback therapy; Cancer management; Kidney renal clear cell carcinoma; Personalized therapies; Precision therapy; Tumor microenvironment; Tumour heterogeneity

DOI:  https://doi.org/10.1007/s12672-025-02090-5
Methods Cell Biol. 2025 ;pii: S0091-679X(24)00143-2. [Epub ahead of print]194 1-17

Labeling of mitochondria for detection of intercellular mitochondrial transfer.

Isamu Taiko, Chika Takano, Shingo Hayashida, Kazunori Kanemaru, Toshio Miki.

  The phenomenon of intercellular transfer of mitochondria has been reported and has attracted significant interest in recent years. The phenomena involve a range of physiological and pathological conditions, such as tumor growth, immunoregulation, and tissue regeneration. There is speculation on the potential restoration of cellular energy status through the transfer of healthy mitochondria from donor cells to cells with impaired mitochondria. Multiple mechanisms and routes of mitochondria transfer have been suggested, including direct cell-to-cell connections, extracellular vesicles, and cell fusion. However, there is limited understanding regarding the precise mechanisms behind mitochondrial transfer, particularly the initiation signals and the associated processes. In order to explore these fundamental mechanisms of mitochondrial transfer, it is imperative to employ techniques that enable direct labeling of mitochondria. Here, we present a detailed methodology utilizing fluorescent protein tagging to visualize mitochondria. The molecular biological techniques applied in this study entail the precise localization of mitochondria with reduced cytotoxicity. This approach facilitates the direct observation of transferred mitochondria through fluorescent and confocal microscopy. The described method can be readily implemented in other mammalian cell types with few modifications, enabling the continuous monitoring of mitochondrial trafficking processes over an extended period.

Keywords:  Amniotic epithelial cells; Mitochondria; Mitochondrial transfer

DOI:  https://doi.org/10.1016/bs.mcb.2024.05.001
Biochim Biophys Acta Bioenerg. 2025 Mar 09. pii: S0005-2728(25)00019-2. [Epub ahead of print]1866(2): 149553

Identification of determinants for variability in mitochondrial biochemical complex activities.

Sandra Monica Bach de Courtade, Marte Eikenes, Ying Sheng, Tuula A Nyman, Yngve Thomas Bliksrud, Katja Scheffler, Lars Eide.

  Diagnostics of mitochondrial disease requires a combination of clinical evaluations and biochemical characterization. However, the large normal variation in mitochondrial complex activity limits the precision of biochemical diagnostics. Thus, identifying factors that contribute to such variations could enhance diagnostic accuracy. In comparison, inbred mice demonstrate much less variations in brain mitochondrial activity, but a clear reduction with age. Interestingly, pretreatment of mouse brain mitochondria with the detergent dodecyl maltoside abolishes the reduction. We therefore postulated that DDM pretreatment could be valuable tool for distinguishing between variations caused by posttranslational modifications and those caused by genetic heterogeneity. In this study, we evaluated the effects of age, DDM sensitivity, oxidative damage and single nucleotide polymorphism on biochemical complex activity and the proteome of human muscle mitochondria, which serve as reference standards for mitochondrial diagnostics. Our results indicate that mtDNA variants are the primary contributors to the diversity in biochemical activity in human muscle mitochondria from healthy individuals.

Keywords:  Dodecyl maltoside; ETC; Heteroplasmy; Mitochondrial function; mtDNA damage

DOI:  https://doi.org/10.1016/j.bbabio.2025.149553
Methods Mol Biol. 2025 ;2906 229-242

Electron Microscopy to Visualize and Quantify Mitochondrial Structure and Organellar Interactions in Cultured Cells During Senescence.

Christina Glytsou.

  Mitochondria are multifunctional organelles that play a crucial role in numerous cellular processes, including oncogene-induced senescence. Recent studies have demonstrated that mitochondria undergo notable morphological and functional changes during senescence, with mitochondria dysregulation being a critical factor contributing to the induction of this state. To elucidate the intricate and dynamic structure of these organelles, high-resolution visualization techniques are imperative. Electron microscopy offers nanometer-scale resolution images, enabling the comprehensive study of organelles' architecture. This chapter provides a detailed guide for preparing fixed samples from cultured cells for electron microscopy imaging. It also describes various quantification methods to accurately assess organellar parameters, including morphometric measurements of mitochondrial shape, cristae structure, and mitochondria-endoplasmic reticulum contact sites. These analyses yield valuable insights into the status of subcellular organelles, advancing our understanding of their involvement in cellular senescence and disease.

Keywords:  EM sample preparation; Electron microscopy; MERCs; Mitochondria visualization; Mitochondrial structure

DOI:  https://doi.org/10.1007/978-1-0716-4426-3_13