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PubMed2025

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

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.

Voltage-Dependent Anion Channel 2↗
PubMed2026

Exercise elicits mitonuclear protein imbalance and UPRmt in the liver of mice with obesity.

Mitochondrial dysfunction plays a critical role in the development of metabolic dysfunction-associated steatotic liver disease (MASLD). It has been proposed that mitochondrial unfolded-protein response (UPRmt) activation improves mitochondrial function in the liver. Growing evidence demonstrates that physical exercise effectively prevents and treats MASLD. However, the effects of exercise on UPRmt activation in the liver are unknown. Thus, we investigated the impact of aerobic training on the mechanisms involved in mitochondrial quality control in the liver in a mouse model of obesity. Liver transcript data from a genetic reference panel of BXD isogenic mice revealed a negative correlation between UPRmt-related genes and hepatic triacylglycerol content. In addition, the liver UPRmt markers were strongly associated with several mitochondrial-related genes in the hepatic tissue of BXD mice and humans. Notably, 4 weeks of aerobic exercise strongly impacted the liver metabolism, preventing intrahepatic lipid accumulation in HFD-fed mice. Physical exercise boosted the NAD-biosynthesis pathway, elicited the mitonuclear protein imbalance, stimulated the protein content of UPRmt-markers, including CLpP, Lonp1, and Yme1L1, and improved the mitochondrial proteostasis and function in the liver in HFD-fed mice. Thus, our findings link the mitonuclear protein imbalance and UPRmt activation in the liver to mitochondrial proteostasis and MASLD prevention in response to physical exercise.

Animals↗
PubMed2024

Platelet-derived mitochondria regulate lipid metabolism in nonalcoholic steatohepatitis through extracellular vesicles.

BACKGROUND AND AIMS: Immune system activation, along with lipotoxicity due to excessive lipid droplet (LD) accumulation in the liver, are key drivers of NASH. Extracellular vesicles (EVs) released by cells that carry biological signals contribute to intercellular communication. However, the roles of immune cell-derived EVs in the pathogenesis of NASH are unclear. APPROACH AND RESULTS: Platelets are abundant in blood. We explored the role of platelet-derived EVs (pEVs) in LD accumulation from 30 patients with nonalcoholic fatty liver disease of different severity as well as 20 healthy subjects, a rat model, and an in vitro cell-based assay. There was increased platelet activation, accompanied by pEVs release, in NASH patients/rat model, and palmitate-treated cells. The mitochondria in the platelets and pEVs from NASH patients/rats were increased but dysfunctional, including a reduction in fatty acid β-oxidation, inactivated acetyl-CoA carboxylase 2, and suppressed oxidative phosphorylation system complex II/III/IV activity. These damaged mitochondria could be transferred to hepatocytes through pEVs to increase the number of lipid droplet-bound mitochondria. An increase in dysfunctional lipid droplet-bound mitochondria in hepatocytes affects lipid metabolism, resulting in excessive LD accumulation, elevated mitochondrial reactive oxygen species production, and apoptosis. CONCLUSIONS: We offer a novel molecular mechanism that connects platelets, pEVs, and excessive LD accumulation to the development of NASH. Our results suggest that NASH progression may be alleviated by specifically inhibiting the production and release of pEVs, or by targeting pEV components and inhibiting their uptake. Additional experiments are required to confirm this potentiality.

Non-alcoholic Fatty Liver Disease↗
PubMed2026

Mitochondrial retrograde signal through GCN5L1 transition-mediated PPARγ stabilization promotes MASLD development.

Mitochondrial retrograde signaling plays crucial roles in maintaining metabolic homeostasis via regulating genome modification and oxidative responsive gene expression. In this study, we identified GCN5L1, a protein localized in both mitochondria and cytoplasm, and demonstrated its specific translocation from mitochondria to cytoplasm during lipid overload and high-fat diet feeding. Using transcriptome and proteome analyses, we identified that cytoplasmic GCN5L1 binds to and promotes the acetylation of PPARγ at lysine 289 (K289). This acetylation protected PPARγ from ubiquitination-mediated degradation by proteasome. GCN5L1 translocation enhanced protein stability of PPARγ and subsequently promoted lipid accumulation in both cultured cells and murine models. Our study further reveals that PPARγ-K289 mutation reduces the ubiquitination of PPARγ and exacerbates liver steatosis in mice. These findings unveil a mitochondrial retrograde signaling during lipid overload, which regulates the crucial lipogenic transcriptional factor. This discovery elucidates an unrecognized mitochondrial function and mechanism underlying hepatic lipid synthesis.

Animals↗
PubMed2025

p53 enhances DNA repair and suppresses cytoplasmic chromatin fragments and inflammation in senescent cells.

Genomic instability and inflammation are distinct hallmarks of aging, but the connection between them is poorly understood. Here we report a mechanism directly linking genomic instability and inflammation in senescent cells through a mitochondria-regulated molecular circuit involving p53 and cytoplasmic chromatin fragments (CCF) that are enriched for DNA damage signaling marker γH2A.X. We show that p53 suppresses CCF accumulation and its downstream inflammatory phenotype. p53 activation suppresses CCF formation linked to enhanced DNA repair and genome integrity. Activation of p53 in aged mice by pharmacological inhibition of MDM2 reverses transcriptomic signatures of aging and age-associated accumulation of monocytes and macrophages in liver. Mitochondrial ablation in senescent cells suppresses CCF formation and activates p53 in an ATM-dependent manner, suggesting that mitochondria-dependent formation of γH2A.X + CCF dampens nuclear DNA damage signaling and p53 activity. These data provide evidence for a mitochondria-regulated p53 signaling circuit in senescent cells that controls DNA repair, genome integrity, and senescence- and age-associated inflammation, with relevance to therapeutic targeting of age-associated disease.

Animals↗
PubMed2025

Impaired hematopoiesis and embryonic lethality at midgestation of mice lacking both lipid transfer proteins VPS13A and VPS13C.

VPS13 is the founding member of a family of proteins that mediate lipid transfer at intracellular membrane contact sites by a bridge-like mechanism. Mammalian genomes comprise 4 VPS13 genes encoding proteins with distinct localizations and function. The gene duplication resulting in VPS13A and VPS13C is the most recent in evolution and, accordingly, these two proteins are the most similar to each other. However, they have distinct subcellular localizations and their loss of function mutations in humans are compatible with life but result in two different age-dependent neurodegenerative diseases, chorea-acanthocytosis and Parkinson's disease, respectively. Thus, it remains unclear whether these two proteins have overlapping functions. Here, we show that while Vps13a KO and Vps13c KO mice are viable, embryonic development of Vps13a/Vps13c double knockout (DKO) mice is arrested at midgestation. Prior to death, DKO embryos were smaller than controls, were anemic and had a smaller liver, most likely reflecting defective embryonic erythropoiesis which at this developmental stage occurs primarily in this organ. Further analyses of erythroid precursor cells showed that their differentiation was impaired and that this defect was accompanied by activation of innate immunity as revealed by upregulation of interferon stimulated genes (ISGs). Additionally, the RIG-I and MDA5 components of dsRNA triggered innate immunity were found upregulated in the DKO fetal liver. Activation of innate immunity may result from loss of integrity of the membranes of intracellular organelles, such as mitochondria and autophagic lysosomes, or to impaired autophagy, due to the absence of these lipid transport proteins. The surprising and striking synthetic effect resulting for the combined loss of VPS13A and VPS13C suggests that despite of the different localization of these two proteins, the lipid fluxes that they mediate are partially redundant.

Animals↗
PubMed2026

Dietary effects on cytosolic and mitochondrial tRNA abundance and modification patterns across mouse tissues.

Transfer RNAs (tRNAs) are central to protein synthesis and are increasingly recognized as dynamic regulators of gene expression whose abundance and chemical modifications are subject to precise biological control. Here, we systematically investigate how two distinct dietary interventions, low-protein and high-fat diets, reshape the tRNA landscape across multiple mouse tissues, using RNA mass spectrometry and ordered two-template relay sequencing (OTTR-seq) to comprehensively profile cytosolic and mitochondrial tRNAs at single-nucleotide resolution. We reveal pronounced tissue-specific biases in tRNA isodecoder expression, including the unexpected presence of full-length cytosolic tRNAs in mature sperm with a distinct isotype composition. In somatic tissues such as liver and heart, dietary conditions alter both tRNA abundance and key modifications known to regulate decoding efficiency, whereas in reproductive tissues diet primarily affects the abundance of select tRNAs with comparatively limited changes in modification profiles. We further demonstrate that mitochondrial tRNAs are subject to diet-responsive changes in both abundance and modification status and that even subtle differences in dietary fat composition are sufficient to alter tRNA modification signatures. Together, these findings establish the tRNA epitranscriptome as a sensitive and tissue-specific sensor of nutritional state and provide a resource for understanding how dietary cues interface with translational regulation in somatic and reproductive tissues.

Male↗
PubMed2024

SUMOylation controls Hu antigen R posttranscriptional activity in liver cancer.

The posttranslational modification of proteins critically influences many biological processes and is a key mechanism that regulates the function of the RNA-binding protein Hu antigen R (HuR), a hub in liver cancer. Here, we show that HuR is SUMOylated in the tumor sections of patients with hepatocellular carcinoma in contrast to the surrounding tissue, as well as in human cell line and mouse models of the disease. SUMOylation of HuR promotes major cancer hallmarks, namely proliferation and invasion, whereas the absence of HuR SUMOylation results in a senescent phenotype with dysfunctional mitochondria and endoplasmic reticulum. Mechanistically, SUMOylation induces a structural rearrangement of the RNA recognition motifs that modulates HuR binding affinity to its target RNAs, further modifying the transcriptomic profile toward hepatic tumor progression. Overall, SUMOylation constitutes a mechanism of HuR regulation that could be potentially exploited as a therapeutic strategy for liver cancer.

Animals↗
PubMed2026

Hepatic ketogenic insufficiency blunts exercise-induced energy expenditure and alters mitochondrial proteins in skeletal muscle.

Ketone body (KB) utilization increases during fasting and exercise due to enhanced hepatic fatty acid oxidation and KB production via the rate-limiting mitochondrial enzyme hydroxymethylglutaryl-CoA synthase (HMGCS2). Since KB metabolism intersects with multiple metabolic pathways and skeletal muscle KB catabolism rises during exercise, we tested the hypothesis that liver-specific HMGCS2 knockouts (KO) would have reduced energy expenditure (EE) and changes in the mitochondrial proteome of skeletal muscle with chronic exercise through voluntary wheel running (VWR), time-restricted feeding (TRF), or both combined to boost hepatic KB production and utilization. Control (CON) and HMGCS2 knockout (KO) mice (n = 6-8 per group) underwent sedentary ad libitum feeding (SED + AL), SED + TRF, VWR + AL, and VWR + TRF for 16 wk, with whole body EE measured using indirect calorimetry. In CON mice, VWR increased total EE by 19.5% and nonresting EE by 50% under AL conditions, and total EE by 16% and nonresting EE by 47.9% under TRF conditions. However, the EE increases seen with VWR did not occur in KO mice. Proteomic analysis revealed that the loss of liver HMGCS2 significantly impacted proteins involved in metabolic processes within skeletal muscle, including reduced oxidative phosphorylation (OXPHOS) protein expression in SED KO mice compared with sedentary CON. Notably, VWR restored OXPHOS protein expression in the muscle of the liver HMGCS2 KO but did not alter it in the CON. Furthermore, muscle from liver HMGCS2 KO mice had elevated expression of glycolytic pathways in sedentary and VWR conditions. These results indicate that hepatic ketogenic deficiency (HMGCS2 KO) diminishes exercise-induced increases in EE and uniquely impacts baseline and exercise-related adaptations in the metabolic and mitochondrial proteome of skeletal muscle.

Hydroxymethylglutaryl-CoA Synthase↗
PubMed2025

Bidirectional shifts in Pm20d1 expression impact thermogenesis and metabolism.

BACKGROUND: Peptidase M20 domain containing 1 (PM20D1) is a secreted N-fatty acyl amino synthase and hydrolase that controls tissue and blood levels of N-fatty acyl amino acids. In brown adipocytes, N-fatty acyl amino acids bind to mitochondria and act as uncouplers of mitochondria, independent of UCP1. Interventions aimed at increasing or inhibiting PM20D1 expression considerably impact energy balance and metabolism; however, little is known about naturally occurring variants of the PM20D1/Pm20d1 gene and their impact on phenotype. METHODS: In vivo, gene expression of Pm20d1 in BALB/c, C57BL/6, and Ucp1 KO in brown adipose tissue and other metabolic tissues was measured. In vitro, transcriptional activity of Pm20d1 and brown adipocytes' oxygen consumption in primary culture were assessed. Human PM20D1 circulating levels were quantified. In silico analysis of the Pm20d1 gene sequencing and human polymorphisms associated with PM20D1 was performed. RESULTS: Here, we identified a gain-of-function variant in the Pm20d1 promoter region present in BALB/c mice and absent in C57BL/6 mice. The presence of this variant is accompanied by increased expression of Pm20d1 in brown and white adipose tissues, muscle, liver, and hypothalamus; moreover, it leads to increased cold tolerance and UCP1-independent brown adipose tissue mitochondrial respiration. Inhibition of Pm20d1 in brown adipose tissue results in defective cold tolerance in BALB/c, whereas the brown adipose tissue overexpression of Pm20d1 results in increased cold tolerance in C57BL/6 mice. In humans, variants of the PM20D1 gene are associated with changes in body mass index, whereas at least one variant in the promoter region is associated with increased body mass index and metabolic syndrome. CONCLUSION: Thus, PM20D1 plays a bidirectional role in regulating thermogenesis and body mass, and, at least in part, variants in the promoter region can partially explain the differences in PM20D1 expression and its impact on the metabolic phenotype.

Thermogenesis↗
PubMed2026

Plasticity of hepatic metabolism in Arctic char (Salvelinus alpinus) in response to cyclic hypoxia.

The emergence of cyclic hypoxia puts aquatic organisms' homeostasis under significant strain. Energetic metabolism as well as protein synthesis and folding are particularly altered during hypoxia, while reoxygenation imposes an oxidative challenge. Currently, little is known about how hypoxia-sensitive organisms respond to large oxygen fluctuations. Our previous work on Arctic char revealed that this salmonid, despite being strongly affected by acute hypoxia and reoxygenation (H/R), can successfully reestablish homeostasis, notably through adjustments to hepatic mitochondrial metabolism. However, the mechanisms underlying this acclimation remain poorly understood. We hypothesized that Arctic char remodel their hepatic proteome to optimize energy metabolism, reorganize oxygen-demanding pathways, and maintain cellular homeostasis during repeated H/R cycles. By exposing Arctic char to two or fifteen days of diel cyclic hypoxia, we confirmed this species' limited capacity to respond to acute H/R. Nevertheless, after fifteen cycles, fish adjusted their energetic metabolism through coordinated regulation of carbohydrate and lipid pathways and upregulation of amino acid metabolism. Mitochondrial metabolism was strongly reorganized, particularly at the ubiquinone-Complex III interaction level, alongside adjustments in proline utilization and protein processing. Moreover, protein processing and folding pathways were stimulated in both mitochondria and the endoplasmic reticulum. However, chronic cyclic hypoxia may still promote non-mitochondrial ROS production, DNA replication stress, and impaired immune function. This study highlights how a hypoxia-sensitive fish progressively reorganizes its metabolism and oxygen-demanding pathways to establish a phenotype adapted to chronic cyclic hypoxia, while also revealing the physiological costs associated with this acclimation.

Animals↗
PubMed2024

Macrothrombocytopenia with leukocyte inclusions in a patient with Wilson disease: a case report and literature review.

BACKGROUND: Wilson disease (WD) is an autosomal recessive disorder caused by homozygous or compound heterozygous mutations in ATP7B. Clinical manifestations primarily involve liver and nervous system lesions, with rarely observed hematologic manifestations. CASE PRESENTATION: In the present case, a patient with WD presented with thrombocytopenia, giant platelets, and Döhle-like cytoplasmic inclusions in the leukocytes. Initially, the May-Hegglin anomaly was considered; however, whole-exome sequencing did not reveal any mutation in the MYH9 gene but a heterozygous mutation was found in (C.2804 C > T, p.T935M) in the ATP7B gene. After two years, the patient developed tremors in his hands, lower limb stiffness, and foreign body sensation in the eyes. Additionally, Kayser-Fleischer rings in the corneal limbus were detected by slit-lamp examination. Copper metabolism test indicated a slight decrease in serum ceruloplasmin. Transmission electron microscopy revealed that the inclusion bodies of leukocytes were swollen mitochondria. Mass spectrometry analysis showed that the copper levels were almost 20-fold higher in the leukocytes of the patient than in those of the control group. Based on the Leipzig scoring system, a diagnosis of WD was confirmed. Zinc sulfate treatment ameliorated the patient's symptoms and enhanced platelet, serum ceruloplasmin, and albumin levels. CONCLUSIONS: In conclusion, this case represents the first documented instance of WD presenting as thrombocytopenia, giant platelets, and Döhle-like cytoplasmic inclusions in the leukocytes. Excessive cellular copper accumulation likely underlies these findings; however, understanding precise mechanisms warrants further investigation.

Humans↗
PubMed2026

Proteins as Regulators of Metabolic Changes in Sepsis: Alterations in Body Fluids, Immune Cells, and Organs through the Eyes of Proteomics.

Sepsis is a life-threatening syndrome characterized by a dysregulated host response to infection and profound metabolic alterations that contribute to immune dysfunction and organ failure. This Review synthesizes proteomic evidence on sepsis-associated alterations in proteins involved in metabolic pathways across circulating biofluids, immune cells, and organs. Across plasma and urine, proteomic studies identify disturbances in lipoprotein-associated pathways, redox homeostasis, mitochondrial function, and substrate metabolism, indicating that protein signatures of metabolic dysregulation are systemic and detectable across biofluids. In immune cells, monocytes and neutrophils, proteomic analyses reveal a shift toward glycolysis with concurrent impairment of mitochondrial pathways alongside phenotype-dependent differences in lipid and redox-related programs. Organ-level studies further show that metabolic responses are heterogeneous, with distinct trajectories in the kidney, heart, liver, lung, skeletal muscle, and brain. These observations support the concept that sepsis involves compartment-specific remodeling of metabolism-associated protein networks rather than a single convergent metabolic state. Proteomics also highlights potential translational opportunities by identifying metabolism-associated proteins linked to disease severity, clinical phenotypes, and biologically distinct patient subgroups, although the current evidence remains largely exploratory and context-dependent. Overall, proteomics provides a complementary framework for understanding the molecular regulation of sepsis-associated metabolic dysfunction and may refine biological stratification and therapeutic targeting, particularly when integrated with longitudinal sampling and multiomic data.

Humans↗
PubMed2025

Mitochondrial dysfunction fuels drug resistance in adult T-cell acute lymphoblastic leukemia.

BACKGROUND: T-cell acute lymphoblastic leukemia (T-ALL) is a relatively rare hematological malignancy, characterized by the uncontrolled proliferation of immature T lymphoblasts and associated with a generally unfavorable prognosis. Our previous research has demonstrated that decreased mitochondrial activity is associated with the aggressiveness of T-ALL tumors. However, the mechanisms underlying this phenomenon and its contribution to treatment resistance remain largely elusive. METHODS: We have built up the largest known T-ALL tumor bank, with a median follow-up of 32 months, including our transcriptomic data from 79 newly sequenced tumors that adds to the 54 publicly accessible samples. Computational analyses and a series of functional assays were performed to investigate the molecular links between altered mitochondrial activity and drug resistance. RESULTS: The transcriptomic analysis revealed that down-regulation of mitochondrial activity is a potent driver of ABCB1 activation, a gene strongly associated with multidrug resistance. In tumors with low mitochondrial activity, the impaired fatty acids β-oxidation leads to intracellular lipid accumulation, which is directly involved in ABCB1 activation. Indeed, our data show that lipid neo-synthesis and accumulation promotes the activation of lipogenic transcription factors, liver X receptors (LXRs), which act as drivers of ABCB1 expression. Tumor data analyses confirmed that high ABCB1 expression in tumour samples is indeed associated with reduced mitochondrial gene expression, lipid droplet enrichment, increased tumour aggressiveness, and significantly shorter patient survival. CONCLUSIONS: Our study demonstrates that reduced mitochondrial activity drives multidrug resistance in adult T-ALL via lipid-mediated activation of ABCB1. These findings enhance our understanding of the biology of aggressive T-ALL and provide insight into mechanisms of resistance to conventional chemotherapy. Consequently, we propose that targeting de novo lipogenesis and restricting dietary fats, such as caprylic acid, may help overcome treatment resistance in patients with T-ALL exhibiting low mitochondrial activity. TRIAL REGISTRATION: The clinical trial was registered under the identifiers ChiCTR-ONRC-14004968 and ChiCTR2000031553 at ClinicalTrials.gov.

Adult↗
PubMed2025

Correction of pathogenic mitochondrial DNA in patient-derived disease models using mitochondrial base editors.

Mutations in the mitochondrial genome can cause maternally inherited diseases, cancer, and aging-related conditions. Recent technological progress now enables the creation and correction of mutations in the mitochondrial genome, but it remains relatively unknown how patients with primary mitochondrial disease can benefit from this technology. Here, we demonstrate the potential of the double-stranded DNA deaminase toxin A-derived cytosine base editor (DdCBE) to develop disease models and therapeutic strategies for mitochondrial disease in primary human cells. Introduction of the m.15150G > A mutation in liver organoids resulted in organoid lines with varying degrees of heteroplasmy and correspondingly reduced ATP production, providing a unique model to study functional consequences of different levels of heteroplasmy of this mutation. Correction of the m.4291T > C mutation in patient-derived fibroblasts restored mitochondrial membrane potential. DdCBE generated sustainable edits with high specificity and product purity. To prepare for clinical application, we found that mRNA-mediated mitochondrial base editing resulted in increased efficiency and cellular viability compared to DNA-mediated editing. Moreover, we showed efficient delivery of the mRNA mitochondrial base editors using lipid nanoparticles, which is currently the most advanced non-viral in vivo delivery system for gene products. Our study thus demonstrates the potential of mitochondrial base editing to not only generate unique in vitro models to study these diseases, but also to functionally correct mitochondrial mutations in patient-derived cells for future therapeutic purposes.

Humans↗