Hepatocellular carcinoma (HCC) is an aggressive malignancy characterized by profound metabolic reprogramming, mitochondrial dysfunction, and resistance to both conventional and immune-based therapies. Mitochondria play a central role in HCC development by coordinating bioenergetics, redox balance, mitochondrial dynamics, quality control, and immunometabolic signaling.Accumulating evidence indicates that disruption of mitochondrial fission, fusion, and mitophagy promotes tumor growth, metastasis, and therapeutic resistance through metabolic remodeling and adaptive stress responses. Enhanced mitochondrial fission, largely mediated by DRP1 and its associated adaptors, favors glycolytic reprogramming, reactive oxygen species (ROS) accumulation, and invasive behavior, whereas impaired fusion compromises oxidative phosphorylation efficiency.Alterations in mitochondrial DNA (mtDNA) integrity and nucleoid organization further exacerbate mitochondrial dysfunction. These changes can trigger inflammatory signaling through cytosolic mtDNA release and contribute to remodeling of the tumor microenvironment. Mitophagy exhibits context-dependent roles in HCC: it may suppress tumor initiation by removing damaged mitochondria, yet under stress conditions such as hypoxia or nutrient deprivation, it supports tumor survival and adaptation.Beyond tumor-intrinsic effects, mitochondrial metabolism plays a key role in shaping the tumor immune microenvironment. It regulates immunometabolism, antigen presentation, ROS signaling, and immune cell differentiation, thereby influencing immune evasion and responsiveness to immunotherapy.Collectively, mitochondrial pathways are emerging as actionable targets for overcoming immunosuppression and therapeutic resistance. This review integrates current knowledge on mitochondrial dynamics, metabolism, mtDNA regulation, mitophagy, and immunometabolic crosstalk in HCC, and discusses emerging strategies to exploit mitochondrial vulnerabilities for improved clinical outcomes.
Pancreatic cancer has recently been observed to have a rise in incidence and prevalence in terms of cancer-related mortality worldwide. Pancreatic ductal adenocarcinoma (PDAC) is the most prevalent type of pancreatic cancer and is considered highly aggressive. Although recent advancements in chemotherapy, radiation therapy, and immunotherapy provide increased options for treatment, the survival rate of pancreatic cancer compared to other types of malignancies is still relatively low. Especially for PDAC, surgical resection is the only curative therapy considered, but most of these tumors are diagnosed at an advanced stage and are therefore ineligible for surgery. Emerging evidence demonstrates that mitochondrial reprogramming is a central driver of PDAC progression, influencing metabolic plasticity, redox balance, mitochondrial dynamics, and therapy resistance. This review discusses how mitochondrial changes promote PDAC and emerging therapies targeting mitochondria, particularly those that modulate mitochondrial function and metabolism. A deeper understanding of mitochondrial reprogramming may provide novel biomarkers and therapeutic opportunities, ultimately improving early detection and treatment outcomes in PDAC.
Background Mitochondrial cardiomyopathy (MCM), a common subtype of mitochondrial disorders accounting for 20-40% of cases, presents significant diagnostic and therapeutic challenges due to genetic heterogeneity and variable clinical phenotypes. Methods We conducted a comprehensive analysis of the clinical, histopathological, molecular, and genetic characteristics of a 23-year-old male with maternally inherited hypertrophic cardiomyopathy (HCM) associated with the homoplasmic m.9997 T > C variant. Results The patient exhibited early-onset exercise intolerance, arrhythmias, and cardiac dysfunction. Cardiac Magnetic Resonance Imaging confirmed asymmetric HCM with left ventricular enlargement. Genetic analysis identified a homoplasmic m.9997T > C variant across multiple tissues (blood, urine, mucosa, muscle). Muscle biopsy revealed typical mitochondrial abnormalities, and reduced expression of complex IV subunits. Conclusion Our findings support the pathogenic association of the homoplasmic m.9997T > C variant in HCM and highlight the clinical significance of homoplasmic mtDNA mutations in tissue-specific mitochondrial disorders, contributing to the broader understanding of homoplasmic mutations in mitochondrial disease.
Alzheimer's disease is a progressive neurological disorder characterized by two main neuropathological hallmarks: neurofibrillary tangles and amyloid plaques. Both are protein aggregates, composed mainly of hyperphosphorylated Tau and the amyloid fragment Aβ, respectively. NMNAT (Nicotinamide mononucleotide adenylyltransferase) is an endogenous enzyme involved in the conversion of NMN to NAD. It is known for its neuroprotective functions, particularly against axonal degeneration. We have previously shown that different isoforms of NMNAT can protect cells from neurotoxic stress caused by protein aggregates by acting as chaperones. Accordingly, the mitochondrial-localized isoform NMNAT3 exhibits potent chaperone activity, which antagonizes the aggregation of a wide spectrum of pathological amyloid client proteins in culture, including Tau and amyloid beta. Although mostly cytosolic, Aβ has also been detected in mitochondria and mitochondrial membranes. To investigate whether NMNAT3 could serve as a neuroprotective factor in amyloid pathology in vivo, we overexpressed NMNAT3 in two different models: a Drosophila model overexpressing APP and PS1 in developing photoreceptors, and the 3xTg-AD mouse, in which NMNAT3 was expressed in forebrain neurons and which accumulates neurofibrillary tangles and plaques in the hippocampus and cortex. When expressed in the Drosophila eye, APP accumulated in a location- and time-dependent manner, and co-expression of NMNAT3 decreased the total number of aggregates. When expressed in the mouse brain, NMNAT3 did not affect amyloid plaque number or volume; nonetheless, it altered APP processing, leading to the accumulation of oligomers and soluble C-terminal fragments. We conclude that the effects of NMNAT3 on APP differ between models, likely due to differences in access to the sites of protein aggregation and the neuronal environments between flies and mice.
Mitochondrial respiratory chain inhibitors (MRCIs) are indispensable for studying cellular bioenergetics and its effects on various cellular processes. However, their off-target (those not mediated by respiratory chain inhibition) effects remain incompletely understood, even though their comprehension is crucial for the accurate interpretation of experimental outcomes. Here, we use four isogenic cell line pairs, which either have mitochondrial DNA (mtDNA) or lack it (ρ+ or ρ0 cells, respectively), to assess the possible off-target effects of widely used MRCIs antimycin A, oligomycin A, rotenone, and carbonyl cyanide m-chlorophenylhydrazone (CCCP). We examined clonogenic growth of ρ0 cells and ρ+ cells under conditions that either require the functional respiratory chain or do not. Unexpectedly, ρ0 cells were sensitive to rotenone and antimycin A, even though these cells lack functional complex I and complex III, respectively, suggesting a nonspecific effect of these drugs. Furthermore, ρ0 cells were more sensitive to CCCP than their ρ+ counterparts. Intriguingly, the loss of the clonogenic potential in ρ+ 143B cells could not be precisely correlated to the decrement of the mitochondrial inner membrane potential. These findings underscore the significance of off-target effects of MRCIs, which must be carefully considered when designing, conducting, and interpreting experiments involving these inhibitors.
Mitochondrial homeostasis is essential for cell survival and metabolic balance. This review systematically examines the molecular mechanisms, pathological correlations, and regulatory relationships among three major processes: mitochondrial homeostasis, lipoacylation modification, and mitochondrial overheating (excess energy). Mitochondrial dynamic balance adapts to energy demands through division mediated by Drp1, as well as regulation by Mfn1/2 and OPA1 for fusion. Lipoacylation activates PDH and α-KGDHC, which ensures metabolic efficiency and reduces ROS. Overheating characterized by increased ATP/ADP ratios, an enhanced ETC reducing state, and ROS accumulation, disrupts the first two processes and creates a vicious cycle. This network disorder is a common pathological basis for neurodegenerative diseases (such as CMT2A, AD), cardiovascular diseases (such as dilated cardiomyopathy), and metabolic diseases (such as type 2 diabetes and NAFLD). However, the details of these sensing pathways regulation remain unclear and require further investigation. This review aims to provide a theoretical framework for researching and treating diseases related to mitochondrial dysfunction.
Mitochondrial Ca2+ plays important roles in shaping intracellular Ca2+ signaling and modulating energy metabolism. Dysregulated mitochondrial Ca2+ dynamics have been increasingly implicated in the pathogenesis of neurodegenerative disorders. To unravel how mitochondrial Ca2+ participates in the processes of neural activity and neurodegeneration, it is essential but challenging to monitor its dynamics in vivo. Recent advances in two-photon microscopy and genetically encoded Ca2+ indicators have enabled high-resolution imaging of mitochondrial Ca2+ in the brain. Here, we present a comprehensive protocol for in vivo imaging and analysis of mitochondrial Ca2+ dynamics in neurons of awake mice. This protocol provides detailed methodologies for indicator delivery, chronic cranial window implantation, two-photon imaging, and downstream data analysis. By offering a standardized and reproducible workflow, this protocol aims to facilitate investigation of mitochondrial Ca2+ dynamics in vivo in both physiological and pathological contexts.
LONP1 is a conserved mitochondrial AAA + protease central to mitochondrial proteostasis. This review summarizes its structural features, protease-chaperone functions, and roles in metabolic regulation (heme/sulfur/steroid pathways) and disease. In cancer, LONP1 overexpression drives tumor progression via metabolic reprogramming, EMT induction, metastasis, and therapy resistance, establishing it as a pan-cancer therapeutic target. Inhibitors face delivery and selectivity challenges, prompting future strategies like mitochondrial-targeted delivery and allosteric modulators. Research directions include mechanistic studies and clinical translation for cancer and neurodegenerative disorders.
Mitochondria play central roles in the physiology of eukaryotic cells. Mitochondrial membrane potential, in turn, is a key driver of mitochondrial physiology. We previously developed a system to localize voltage-sensitive fluorophores to mitochondria based on the hydrolysis of labile acetoxymethyl (AM) esters. One potential problem with this system is the premature hydrolysis of the labile AM ester prior to accumulation in the mitochondria. A possible solution is to replace the AM ester with a bulky cyclopropylmethylacetoxy (CPM) ester, which resists uncatalyzed hydrolysis but can be removed by certain esterases. When paired with exogenous expression of mitochondrially-targeted esterases like porcine liver esterase (PLE), this chemical-genetic hybrid approach can improve localization to mitochondria. In this manuscript, we use superresolution microscopy to show that a variety of proteins, including esterases from pig and bacteria can be effectively localized to mitochondria. Further, we establish that a CPM-modified rhodamine voltage reporter (RhoVR-CPM) shows improved localization to mitochondria in cells expressing mitochondrially-targeted esterases. Finally, RhoVR-CPM can be paired with fluorescence lifetime imaging microscopy (FLIM) to map changes in mitochondrial membrane potential.
The origin and expansion of mitochondrial somatic variants, influenced by tissue-specific mutagenesis and selection, are not well understood despite their relevance to aging and age-related diseases. Postmitotic tissues, such as skeletal muscles, are particularly underexplored, even though mtDNA variant evolution in these tissues can differ significantly from that in proliferative tissues. To address this, we analyzed mitochondrial heteroplasmy in skeletal muscle samples from an osteoarthritic cohort (N = 105). We observed that the age-related dynamics of two famous variants m.189A > G and m.408T > A in our cohort is indistinguishable from their dynamics in random control cohort, suggesting that they are not a cause of muscular problems, but rather mark the age-related processes in muscles. We also observed that when adjusted by age and gender, carriers of these variants tend to have higher BMI, body weight, and muscle strength than non-carriers. Putting together all the lines of evidence, we propose that these variants are able to rapidly expand through selfish dynamics, which is especially pronounced in hypertrophic muscle fibers of individuals with higher body weight. Further investigation is necessary to clarify this hypothesis.
Mitochondrial dynamics, encompassing fusion and fission processes, are crucial to cancer’s metabolic adaptation and progression. This review explores the intricate relationship between mitochondrial function and tumor biology, emphasizing the significance of mitochondria as central regulators of cellular metabolism and signaling. We discuss the dual role of the reactive oxygen species produced by mitochondria in facilitating tumor growth and mediating oxidative stress, which can result in cell damage. The balance between mitochondrial fusion mediated by proteins such as mitofusins (MFN1, MFN2) and OPA1 and fission regulated by dynamin-related protein 1 (DRP1) is critical for maintaining mitochondrial integrity and cellular homeostasis in the face of metabolic demands and environmental stressors. Furthermore, we highlight how alterations in mitochondrial dynamics are associated with cancer cell proliferation, survival, and resistance to therapy, particularly under hypoxic conditions prevalent in the tumor microenvironment. By elucidating the mechanisms underlying mitochondrial dynamics in cancer, this review aims to provide insights that could lead to innovative therapeutic strategies targeting mitochondrial functions to improve cancer treatment outcomes.
Adenosine triphosphate (ATP) is essential for almost all life forms. In our article, we discuss (i) insights into the bioenergetics of ATP generation, including an extended view of proton currents during oxidative phosphorylation (OXPHOS), (ii) experimental work showing the ability of several biological structures to perform extra-mitochondrial OXPHOS, (iii) the role of mitochondria-derived vesicles (MDVs) in extra-mitochondrial OXPHOS, and (iv) the relevance of these aspects for the interpretation of the human brain map of mitochondrial density and ATP-synthesizing capacity. In our opinion, extra-mitochondrial OXPHOS and MDVs are important topics for future research that will significantly expand our picture of cellular bioenergetics.
Mitochondrial diseases (MDs) are a significant patient burden and are linked to the dysregulation of various metabolic processes and cellular energy production. Additionally, mitochondria play a central role in regulating immune function and inflammatory response. This study aimed to examine the connection between MD and immune dysfunction, including inflammation as a specific immune response to infection. A scoping literature review and retrospective chart review were conducted. The scoping review followed the five-stage methodology framework by Arksey and O'Malley, extracting 1823 articles from PubMed using Covidence as managing software, with full texts of 10 articles analyzed. A retrospective patient chart review was conducted on 92 patients with a confirmed diagnosis of MD from the Children's Hospital of Eastern Ontario. The scoping review identified cases of MDs associated with inflammation, including individuals with POLG-associated disease. Immune dysfunction was observed in a subset of complex MDs, particularly in individuals with biallelic variation in POLGF and ATAD3A, who had a heavy burden of disease. The results from both the scoping and retrospective chart reviews suggest an association between complex MD and altered inflammatory and immune functions.
Numerous mitochondrial DNA (mtDNA) variants are associated with cancers, yet the causal link remains inconclusive. Using DddA-derived cytosine base editors, we induced de novo truncating mutations in MT-ND5 in HEK293 cells, establishing heteroplasmy, the coexistence of mutant and wild-type mtDNA. This study aimed to investigate the full molecular etiology following these deleterious mtDNA mutations, particularly in oncogenesis. We found that low to moderate heteroplasmic levels of the mutants were sufficient to impair mitochondrial functions and alter cellular redox status. Cellular adaptation to elevated ROS (Reactive Oxygen Species), energy crisis, and altered redox status was observed across varying heteroplasmy levels. Increased oncogenic potential was confirmed through in vitro oncogenesis and in vivo xenograft assays. Transcriptomic analysis revealed upregulated migration, invasion, and genome instability pathways, and downregulated ROS scavenging pathways. Our results demonstrate that MT-ND5 mutations drive cancer progression by increasing cellular ROS and genome instability, and by altering the redox balance and epigenetic landscapes.
