Mitochondrial Biogenesis Research Articles

Mitochondrial homeostatic imbalance-mediated developmental toxicity to H2S in embryonic zebrafish.

Hydrogen sulfide (H2S) is a pervasive environmental and industrial pollutant that poses a substantial threat to human health. Even short-term exposure to H2S can result in severe respiratory and neurological damage. However, the underlying mechanisms of its biotoxicity remain unclear. Our study demonstrated that continuous exposure to 30μM (1.02ppm), whin environmentally H2S concentration range, results in notable developmental toxicity, including high mortality rates, morphological deformities, and behavioral abnormalities, in zebrafish larvae. Through transcriptomic analysis, examination of mitochondrial structure and function, and tissue and cellular staining, we found that H2S exposure disrupted mitochondrial dynamics, autophagy, and biogenesis, leading to an imbalance in mitochondrial homeostasis. This disruption induced oxidative stress and extensive apoptosis. Nitric oxide (NO) is a multifunctional signaling molecule known to target and regulate mitochondrial regeneration. In our study, we discovered that sodium nitroprusside (SNP), an NO donor, can activate the NO-sGC-cGMP signaling pathway. This activation improves the homeostatic regulation of mitochondrial dynamics, autophagy, and biogenesis, thereby enhancing mitochondrial function and effectively mitigating H2S-induced biotoxicity. Our research not only elucidates the biotoxicity mechanisms of H2S exposure but also provides valuable insights into potential therapeutic strategies that alleviate or eliminate its toxic effects.

Unraveling morphine tolerance: CCL2 induces spinal cord apoptosis via inhibition of Nrf2 signaling pathway and PGC-1α-mediated mitochondrial biogenesis.

Morphine effectively relieves severe pain but leads to analgesic tolerance with long-term use.The molecular mechanisms underlying morphine tolerance remain incompletely understood. Existing literature suggests that chemokine CCL2, present in the spinal cord, plays a role in central nervous system inflammation, including neuropathic pain. Nevertheless, the precise mechanism through which CCL2 mediates morphine tolerance has yet to be elucidated. Consequently, this study aims to investigate the molecular pathways by which CCL2 contributes to the development of morphine analgesic tolerance. Rats were administered intrathecal morphine (10 μg/5 μl) twice a day for seven consecutive days to induce a model of morphine nociceptive tolerance. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression levels of CCL2 and its related mechanism molecules. Immunofluorescence was used to detect the localization of CCL2 in the spinal cord. Intrathecal injections of inhibitors or agonists to artificially regulate the expression of relevant molecules. The thermal tail-flick experiment was performed to evaluate morphine tolerance in rats. Morphine-induced CCL2 expression was significantly increased in spinal cord, while conversely, the expressions of Nrf2 and PGC-1a were downregulated. Immunofluorescence showed that the enhanced immune response of CCL2 mainly co-localized with neurons. In vivo, we confirmed that intrathecally injection of CCL2 inhibitor Bindarit could effectively alleviate the occurrence of apoptosis and alleviate morphine tolerance. Similarly, pretreatment with Nrf2 signaling pathway agonist Oltipraz and PGC-1α agonist ZLN005 also achieved similar results, respectively. ROS Fluorescence Assay Kit indicated that increasing the expression of PGC-1α could alleviate the occurrence of apoptosis by reducing the level of ROS. Our data emphasize that chemokine CCL2 inhibited the Nrf2 signaling pathway and PGC-1α-mediated mitochondrial biogenesis, alleviating the occurrence of apoptosis in spinal cord, thereby participating in morphine tolerance. This may provide new targets for the treatment of morphine tolerance.

5'tiRNA-33-CysACA-1 promotes septic cardiomyopathy by targeting PGC-1α-mediated mitochondrial biogenesis

BackgroundWe revealed for the first time that the expression of 158 tRNA-derived small RNAs (tsRNAs) was altered in septic cardiomyopathy (SCM) by microarray analysis, and we selected 5'tiRNA-33-CysACA-1, which was the most significantly up-regulated, as a representative to explore the roles and mechanisms of tsRNAs in SCM. MethodsWe constructed a sepsis model by cecum ligation and puncture (CLP) in mice and detected the expression of 5'tiRNA-33-CysACA-1 using quantitative real-time PCR (qRT-PCR). The supernatant generated after LPS stimulation of macrophages was used as the conditional medium (CM) to stimulate H9C2 and established the injured cell model. CCK-8 and LDH release assays were used to detect cell viability and cell death. Mitochondrial membrane potential (MMP), ATP production, ROS production, and Mitotracker Red mitochondrial morphology were assayed to assess mitochondrial function. Expression of mRNA for molecules related to the mitochondrial quality control system was verified by qRT-PCR. The mechanism by which 5'tiRNA-33-CysACA-1 regulates peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) expression was examined by western blot, mRNA stability analysis, and rescue experiments. ResultsExpression of 5'tiRNA-33-CysACA-1 was elevated in cardiac tissue and H9C2 cells during septic myocardial injury. Stimulation of the CM resulted in cardiomyocyte injury and impaired mitochondrial function. Transfection of 5'tiRNA-33-CysACA-1 mimic in CM further downregulated PGC-1α expression, inhibited mitochondrial biogenesis thereby impairing mitochondrial function and leading to decreased cardiomyocyte activity and increased cell death. In contrast, transfection of the inhibitor ameliorated the above biological processes. In addition, mRNA stability assay and bioinformatics analysis showed that 5'tiRNA-33-CysACA-1 led to a decrease in the stability of PGC-1α mRNA, which in turn downregulated the expression of PGC-1α and promoted the development of SCM. Conclusions5'tiRNA-33-CysACA-1 expression is upregulated in SCM and inhibits mitochondrial biogenesis by targeting PGC-1α and decreasing the stability of PGC-1α mRNA, leading to mitochondrial dysfunction and promoting the development of SCM.

Picrosides-rich fraction from Picrorhiza kurroa attenuates steatohepatitis in zebrafish and mice by modulating lipid metabolism and inflammation.

Non-alcoholic steatohepatitis (NASH) has become a serious public health concern with high global prevalence. The lack of safe and efficient treatment for the condition demands exploring new therapeutic solutions. In the present study, we investigated the protective efficacy of picrosides-rich fraction (PF) from Picrorhiza kurroa against steatohepatitis and revealed the molecular mechanism of action. PF was prepared and characterized using UPLC analysis. Initially, the efficacy of PF was studied on the zebrafish model of NASH. Further, a Methionine and Choline-Deficient (MCD) diet-induced NASH model in mice was employed to evaluate the hepatoprotective efficacy of PF by utilizing biochemical, histopathological and molecular studies. The UPLC analysis revealed the presence of 29.11% and 29.86% picroside I and II in the PF, respectively. In the zebrafish model of NASH, PF treatment reduced the hepatic lipid accumulation and modulated the expressions of lipogenic, inflammatory, oxidative, and cellular stress genes. Further, in MCD diet-induced NASH in mice, PF treatment showed a significant improvement in body weights and serum liver injury markers. Reduced degenerative changes and fibrous tissue was observed in the PF-treated groups. The downregulated expression of Srebp1c, Cd36, Fas, Chrebp, Pparγ, and Hnf4α showed anti-lipogenic potential of PF treatment. NASH development followed oxidative stress, mitochondrial dysfunction, and inflammation in the liver of mice. However, PF treatment encouraged mitochondrial biogenesis by upregulating Pgc1α, Tfam, and Nrf2 expressions. The elevated levels of NFκB, TNFα, IL6, TGFβ, and αSMA were also restored by PF, advocating its anti-inflammatory and anti-fibrogenic effect. The present study revealed that PF ameliorate the progression of NASH by increasing mitochondrial biogenesis and decreasing lipogenesis, hepatic inflammation, and fibrosis.

Cordycepin alleviates metabolic dysfunction-associated liver disease by restoring mitochondrial homeostasis and reducing oxidative stress via Parkin-mediated mitophagy.

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) keeps rising with only a few drugs available. The present study aims to investigate the effects and mechanisms of cordycepin on MASLD. Male C57BL/6 mice were induced with a 90-day high-fat diet (HFD) and intraperitoneal administration with streptozotocin to establish MASLD murine model. Then they were randomly divided into the HFD and cordycepin groups (15, 30, 45mg/kg). Cordycepin was orally given for 30days. Serum total cholesterol (TC), triacylglyceride (TG), and aspartate aminotransferase (AST) levels were measured. L02 cells were induced by oleate acid (OA) or lipopolysaccharides (LPS), and treated with cordycepin or combined with inhibitors including chloroquine, 3-Methyladenine, and compound C. Atg7 and Parkin were knocked down in L02 cells using siRNA. Oil Red O and Nile Red staining for measuring lipid deposition. Mitochondria were visualized by transfection with mCherry-TOMM20-N10. Quantitative real-time PCR, Western blotting, and immunofluorescence staining were used to determine expressions of key molecules in inflammation, lipid metabolism, mitochondria homeostasis, and oxidative stress. Cordycepin significantly mitigated lipid deposition and ballooning in the livers of MASLD mice. Serum TC, TG, and AST levels were decreased by cordycepin. Cordycepin alleviated OA-induced lipid deposition and LPS-induced inflammation in L02 cells, attenuated oxidative stress, promoted autophagy, and maintained the autophagic flux by activating AMP-activated protein kinase (AMPK). Cordycepin reduced the accumulation of impaired mitochondria by enhancing Parkin-dependent mitophagy and promoting mitochondrial biogenesis. Cordycepin alleviates MASLD by restoring mitochondrial homeostasis and reducing oxidative stress via activating the Parkin-mediated mitophagy.

MC16 promotes mitochondrial biogenesis and ameliorates acute and diabetic nephropathy.

Kidney disease (KD) is a leading cause of mortality worldwide, affecting 〉10% of the global population. Two of the most common causes of KD are diabetes and acute kidney injury (AKI), both of which induce mitochondrial dysfunction resulting in renal proximal tubular damage/necrosis. Thus, pharmacological induction of mitochondrial biogenesis (MB) may provide a therapeutic strategy to block the onset/progression of KD. Here, we evaluated the pharmacological and potential therapeutic effects of a novel MB-inducing oxindole agent, MC16. Primary cultures of rabbit renal proximal tubule cells (RPTCs) were used to evaluate the cellular signalling and MB-inducing effects of MC16. Mice were used to determine the MB-inducing effects of MC16 in vivo, and the metabolic effects of MC16 on the renal cortical metabolome. Mouse models of AKI and diabetic kidney disease (DKD) were used to demonstrate the therapeutic potential of MC16 to ameliorate acute and diabetic nephropathy. MC16 activated the PI3K-AKT-eNOS-FOXO1 axis and induced MB in RPTCs. MC16 induced MB and altered the renal cortical metabolome of mice. MC16 accelerated renal recovery, reduced vascular permeability, and diminished mitochondrial dysfunction following AKI. MC16 decreased diabetes-induced renal swelling, improved renal and mitochondrial function, and diminished interstitial fibrosis in DKD mouse models. MC16 is a novel compound that induces MB and ameliorates acute and diabetic nephropathy in mice. This study underscores that targeting MB following the onset of renal/metabolic insults may provide a therapeutic strategy to mitigate the onset and/or progression of KD.

Brain-derived neurotrophic factor drives muscle adaptation similar to aerobic training in mice.

This study, invivo and invitro, investigated the role of brain-derived neurotrophic factor (BDNF) in skeletal muscle adaptations to aerobic exercise. BDNF is a contraction-induced protein that may play a role in muscle adaptations to aerobic exercise. BDNF is involved in muscle repair, increased fat oxidation, and mitochondrial biogenesis, all of which are adaptations observed with aerobic training. The purpose of this study was two-pronged and investigated the skeletal muscle BDNF response to (1) acute and (2) chronic exercise in male C57BL/6J mice. It also examined if chronic BDNF treatment resulted in similar adaptations to chronic exercise. In aim 1, mice underwent a 2 hr. treadmill exercise bout. In aim 2, mice were assigned to one of four groups: (1) control (CON); (2) endurance training (ET; treadmill running 1 h/day, 5 days/wk); (3) BDNF (BDNF; 0.5 mg/kg·bw, 5 days/wk); (4) endurance training and BDNF (ET + BDNF) for 8 weeks. Results demonstrated that the soleus (SOL) had higher BDNF content compared with the extensor digitorum longus (EDL) and that SOL BDNF increased with acute exercise. After chronic exercise and BDNF treatment, treadmill testing to exhaustion demonstrated a main effect of BDNF and ET on increasing exercise capacity. Invitro contractile assessment of the EDL revealed BDNF treatment resulted in similar increases in the max rate of relaxation as ET. EDL force-frequency analysis showed ET + BDNF produced higher force than CON and BDNF, indicating an additive effect. BDNF increased EDL mitochondrial proteins, COXIV, and CS. These results demonstrate that BDNF contributes to muscle adaptations observed with ET.

Epstein-Barr virus-driven cardiolipin synthesis sustains metabolic remodeling during B cell transformation.

The Epstein-Barr virus (EBV) infects nearly 90% of adults globally and is linked to over 200,000 annual cancer cases. Immunocompromised individuals from conditions such as primary immune disorders, HIV, or posttransplant immunosuppressive therapies are particularly vulnerable because of EBV's transformative capability. EBV remodels B cell metabolism to support energy, biosynthetic precursors, and redox equivalents necessary for transformation. Most EBV-driven metabolic pathways center on mitochondria. However, how EBV regulates B cell mitochondrial function and metabolic fluxes remains unclear. Here, we show that EBV boosts cardiolipin (CL) biosynthesis, essential for mitochondrial cristae biogenesis, via EBV nuclear antigen 2/MYC-induced CL enzyme transactivation. Pharmacological and CRISPR genetic analyses underscore the essentiality of CL biosynthesis in EBV-transformed B cells. Metabolomic and isotopic tracing highlight CL's role in sustaining respiration, one-carbon metabolism, and aspartate synthesis. Disrupting CL biosynthesis destabilizes mitochondrial matrix enzymes pivotal to these pathways. We demonstrate EBV-induced CL metabolism as a therapeutic target, offering synthetic lethal strategies against EBV-associated B cell malignancies.

Limiting cap-dependent translation increases 20S proteasomal degradation and protects the proteomic integrity in autophagy-deficient skeletal muscle

ABSTRACT Postmitotic skeletal muscle critically depends on tightly regulated protein degradation to maintain proteomic stability. Impaired macroautophagy/autophagy-lysosomal or ubiquitin-proteasomal protein degradation causes the accumulation of damaged proteins, ultimately accelerating muscle dysfunction with age. While in vitro studies have demonstrated the complementary nature of these systems, their interplay at the organism levels remains poorly understood. Here, our study reveals novel insights into this complex relationship in autophagy-deficient skeletal muscle. We demonstrated that despite a compensatory increase in proteasome level in response to autophagy impairment, 26S proteasome activity was not proportionally enhanced in autophagy-deficient skeletal muscle. This functional deficit was partly attributed to reduced ATP levels to fuel the 26S proteasome. Remarkably, we found that activation of EIF4EBP1, a crucial inhibitor of cap-dependent translation, restored and even augmented proteasomal function through dual mechanisms. First, genetically activating EIF4EBP1 enhanced both ATP-dependent 26S proteasome and ATP-independent 20S proteasome activities, thereby expanding overall protein degradation capacity. Second, EIF4EBP1 activation caused muscle fiber transformation and increased mitochondrial biogenesis, thus replenishing ATP levels for 26S proteasome activation. Notably, the improved performance of the 20S proteasome in EIF4EBP1-activated skeletal muscle was attributed to an increased abundance of the immunoproteasome, a subtype specially adapted to function under oxidative stress conditions. This dual action of EIF4EBP1 activation preserved proteomic integrity in autophagy-deficient skeletal muscle. Our findings uncover a novel role of EIF4EBP1 in improving protein quality control, presenting a promising therapeutic strategy for autophagy-related muscular disorders and potentially other conditions characterized by proteostatic imbalance.

Recent advancements in the understanding of the alterations in mitochondrial biogenesis in Alzheimer's disease.

Alzheimer's disease (AD) is a common neurodegenerative disease characterized by progressive memory loss and cognitive decline. The processes underlying the pathophysiology of AD are still not fully understood despite a great deal of research. Since mitochondrial dysfunction affects cellular energy metabolism, oxidative stress, and neuronal survival, it is becoming increasingly clear that it plays a major role in the development of AD. This review summarizes the recent developments of mitochondrial dysfunction in AD, emphasizing mitochondrial biogenesis, dynamics, axonal transport, interactions between endoplasmic reticulum and mitochondria, mitophagy, and mitochondrial proteostasis. It emphasizes how tau and amyloid-beta (Aβ) proteins worsen mitochondrial and synaptic dysfunction by impairing adenosine triphosphate (ATP) synthesis, causing oxidative stress, and upsetting equilibrium. Additionally, important processes controlling mitochondrial activity and their correlation to the brain health are also discussed. One of the promising therapeutic approaches to lessen neurodegeneration and cognitive decline in AD is to improve mitochondrial activity. This study highlights possible directions for creating focused therapies to impede the advancement of AD through incorporating knowledge of mitochondrial biogenesis and its related mechanisms.

Prohibitins in infection: potential therapeutic targets.

Prohibitins (PHBs) are members of a highly conserved family of proteins, including prohibitin1 and prohibitin2. These proteins are predominantly localized in mitochondria, the nucleus, and cell membranes, where they play critical roles in mitochondrial biogenesis, apoptosis, immune regulation, and other biological processes. Recent studies have demonstrated that both PHB1 and PHB2 can act as a complex or independently to participate in the pathogen infection process. This review focuses on the regulatory roles of PHB1 and PHB2 in viral, bacterial, parasitic and fungal infections, providing a theoretical basis and innovative perspectives for a comprehensive understanding of the roles and mechanisms of PHB1 and PHB2 in the regulation of microbial infections. Due to exerting multiple functions, PHB proteins have been recognized as a potential target for therapeutic interventions, with the expectation that targeting PHB proteins will provide new strategies for the treatment of infection-related diseases.

The E3-ligase Siah2 activates mitochondrial quality control in neurons to maintain energy metabolism during ischemic brain tolerance

Mitochondrial quality control is crucial for the homeostasis of the mitochondrial network. The balance between mitophagy and biogenesis is needed to reduce cerebral ischemia-induced cell death. Ischemic preconditioning (IPC) represents an adaptation mechanism of CNS that increases tolerance to lethal cerebral ischemia. It has been demonstrated that hypoxia-induced Seven in absentia Homolog 2 (Siah2) E3-ligase activation influences mitochondrial dynamics promoting the degradation of mitochondrial proteins. Therefore, in the present study, we investigated the role of Siah2 in the IPC-induced neuroprotection in in vitro and in vivo models of IPC. To this aim, cortical neurons were exposed to 30-min oxygen and glucose deprivation (OGD, sublethal insult) followed by 3 h OGD plus reoxygenation (lethal insult). Our results revealed that the mitochondrial depolarization induced by hypoxia activates Siah2 at the mitochondrial level and increases LC3-II protein expression, a marker of mitophagy, an effect counteracted by the reoxygenation phase. By contrast, hypoxia reduced the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a marker of mitochondrial biogenesis, whereas its expression was increased after reoxygenation thus improving mitochondrial membrane potential, mitochondrial calcium content, and mitochondrial morphology, hence leading to neuroprotection in IPC. Furthermore, Siah2 silencing confirmed these results. Collectively, these findings indicate that the balance between mitophagy and mitochondrial biogenesis, due to the activation of the Siah2-E3-ligase, might play a role in IPC-induced neuroprotection.

Probiotic Limosilactobacillus reuteri DSM 17938 Alleviates Acute Liver Injury by Activating the AMPK Signaling via Gut Microbiota-Derived Propionate.

Limosilactobacillus reuteri DSM 17938 (L. reuteri DSM 17938) was one of the most widely used probiotics in humans for gastrointestinal disorders, but few studies have investigated its role in drug-induced liver injury (DILI). Here, we evaluated the efficacy of L. reuteri DSM 17938 using a mouse model of DILI induced by triptolide. Pregavage of L. reuteri DSM 17938 for 1 week remarkably lowered hepatic inflammatory cytokines level and oxidative stress, with diminished serum alanine transaminase and aspartate aminotransferase levels. Metabolomics and RT-qPCR analysis confirmed its ability in ameliorating TP-disrupted hepatic fatty acid β oxidation. Genome annotation of L. reuteri showed its ability to modulate energy metabolism. Targeted metabolomics demonstrated that L. reuteri DSM 17938 modified the short fatty acid profiles in cecum, especially enhancing propionate levels. Further experiments found that L. reuteri DSM 17938 can activate AMPK signaling by upregulating gut microbiota-derived propionate level, thus restoring impaired mitochondrial biogenesis and energy supply processes to recover energy homeostasis, which leads to diminished ROS production and oxidative stress injury in hepatocytes. Besides, AMPK inhibitor dorsomorphin abolished all the effects on propionate protecting mitochondria and energy metabolism. This study established probiotic therapy of L. reuteri DSM 17938 as a preventive intervention for DILI in clinical. We also revealed that L. reuteri DSM 17938 can activate AMPK signaling by propionate, facilitating a deeper understanding of the action mechanism of L. reuteri DSM 17938 against acute liver injury and contributing to the development of its postbiotics and wider applications.

M6a demethylase FTO regulates the oxidative stress, mitochondrial biogenesis of cardiomyocytes and PGC-1a stability in myocardial ischemia-reperfusion injury

ABSTRACT Objective Myocardial ischemia-reperfusion injury (MIRI) is a highly complex disease with high morbidity and mortality. Studying the molecular mechanism of MIRI and discovering new targets are crucial for the future treatment of MIRI. Methods We constructed the MIRI rat model and hypoxia/reoxygenation (H/R) injury cardiomyocytes model. RT–PCR and Western blot were used to investigate the expression of the fat mass and obesity-associated (FTO) gene. Electrocardiogram, echocardiography, triphenyltetrazolium chloride (TTC) staining and hematoxylin-eosin (HE) staining were used to assess the model and the effect of FTO overexpression. The generation of reactive oxygen species (ROS) and the levels of superoxide dismutase (SOD2), mitochondrial transcription factor (TFAM) and cytochrome c oxidase I (COXI) were detected to assess the oxidative stress and mitochondrial biogenesis. RNA immunoprecipitation (RIP) and RNA pulldown assays were used to identify the interaction of FTO and PGC-1a. The m6A dot blot, methylated RNA immunoprecipitation PCR (MeRIP-PCR) and RNA stability analysis were used to analyze the regulation of methylation of PGC-1a by FTO. Results FTO was downregulated in MIRI rats and H/R induced cardiomyocytes. Overexpression of FTO inhibited ROS level and increased the expression of SOD2, TFAM and COXI in vitro and in vivo. In addition, PGC-1a was identified as a downstream target of FTO. FTO enhanced the stability of PGC-1a mRNA through removing the m6A modification. Conclusion Our study revealed the role of FTO regulates the oxidative stress and mitochondrial biogenesis via PGC-1a in MIRI, which may provide a new approach to mitigating MIRI.

FAM43A coordinates mtDNA replication and mitochondrial biogenesis in response to mtDNA depletion.

Mitochondrial retrograde signaling (MRS) pathways relay the functional status of mitochondria to elicit homeostatic or adaptive changes in nuclear gene expression. Budding yeast have "intergenomic signaling" pathways that sense the amount of mitochondrial DNA (mtDNA) independently of oxidative phosphorylation (OXPHOS), the primary function of genes encoded by mtDNA. However, MRS pathways that sense the amount of mtDNA in mammalian cells remain poorly understood. We found that mtDNA-depleted IMR90 cells can sustain OXPHOS for a significant amount of time, providing a robust model system to interrogate human intergenomic signaling. We identified FAM43A, a largely uncharacterized protein, as a CHK2-dependent early responder to mtDNA depletion. Depletion of FAM43A activates a mitochondrial biogenesis program, resulting in an increase in mitochondrial mass and mtDNA copy number via CHK2-mediated upregulation of the p53R2 form of ribonucleotide reductase. We propose that FAM43A performs a checkpoint-like function to limit mitochondrial biogenesis and turnover under conditions of mtDNA depletion or replication stress.

Increased TSPO alleviates neuropathic pain by preventing pyroptosis via the AMPK-PGC-1α pathway

Neuropathic pain poses a significant clinical challenge, largely due to the incomplete understanding of its molecular mechanisms, particularly the role of mitochondrial dysfunction. Bioinformatics analysis revealed that pyroptosis and inflammatory responses induced by spared nerve injury (SNI) in the spinal dorsal horn play a critical role in the initiation and persistence of neuropathic pain. Among the factors involved, TSPO (translocator protein) emerged as a key regulator. Our experimental findings showed that TSPO expression was upregulated during neuropathic pain, accompanied by mitochondrial dysfunction, specifically manifested as impaired mitochondrial biogenesis, disrupted mitochondrial dynamics (including insufficient expression of mitochondrial biogenesis and fusion-related proteins, as well as significantly increased expression of fission-related proteins), and activation of pyroptosis. Pharmacological upregulation of TSPO, but not its downregulation, effectively alleviated SNI-induced pain hypersensitivity, improving mitochondrial function and reducing pyroptosis. Immunofluorescence staining confirmed that TSPO was primarily localized in astrocytes, and its expression mirrored the protective effects on mitochondrial health and pyroptosis prevention. PCR array analysis suggested a strong association between TSPO and the mitochondrial regulation pathway AMPK-PGC-1α. Notably, inhibition of AMPK-PGC-1α abolished TSPO effects on mitochondrial balance and pyroptosis suppression. Furthermore, Mendelian randomization analysis of GWAS data indicated that increased TSPO expression was linked to pain relief. Through drug screening, molecular docking, and behavioral assays, we identified zopiclone as a promising TSPO-targeting drug for pain treatment. In summary, this study enhances our understanding of the molecular interplay between TSPO, mitochondrial health, and neuropathic pain, highlighting TSPO as a potential therapeutic target for pain management.Graphical

Development of an in vitro model to study muscle maladaptation to overtraining

Introduction Physical training stimulates skeletal muscle mitochondrial biogenesis and protein synthesis, inducing beneficial adaptations and promoting performance. However, in some cases when the training load is higher than required, the outcome may lead to non-functional overreaching – a state in which performance may be transiently reduced. This condition is relatively common especially among endurance athletes, and if protracted would result in the development of the overtraining syndrome (OTS), whose impact on skeletal muscle metabolism and function is still unknown. Muscle soreness, increased inflammation and reduced muscle mass are often reported. It has been reported that regeneration of skeletal muscle fibres is impaired, probably through a change in energy metabolism (Grobler et al., 2004). For instance, altered mitochondrial structure and function have been suggested (Grobler et al., 2004). The aim of the present project is to determine the molecular mechanisms underlying skeletal muscle maladaptation’s in response to simulated exercise in vitro. Methods Using a model developed in our laboratory (Zanou et al., 2021), we electrically stimulated C2C12 myotubes (a mouse skeletal muscle cell line) to simulate endurance exercise (Zanou et al., 2021). For simulated training (s-T) the stimulation was applied once daily, for three consecutive days. For simulated overtraining (s-OT), the stimulation was applied three times per day for three consecutive days. Mitochondrial biogenesis biomarkers have been measured, alongside proteomics analysis and mitochondrial respiration. Results In the in vitro s-T model, we observed the expected beneficial adaptations to training, which include myotube hypertrophy, increased fast and slow-twitch myosin heavy chain protein content, and increased mitochondrial respiration. Our proteomics data highlighted many positive adaptations, including upregulation of the muscle contractile and mitochondrial proteins. Immunofluorescence staining of F-actin and of the mitochondrial outer membrane protein Tom20, clearly showed robust F-actin structure and regular mitochondrial distribution in response to s-T. Interestingly, s-OT model presented myotube atrophy, and a decrease in fast and slow-twitch myosin heavy chain protein content. Mitochondrial respiration was increased in s-T and showed a clear trend versus reduction in s-OT. Our proteomics data revealed many downregulated proteins pathways in s-OT including muscle contractile and mitochondrial pathways. Immunofluorescence staining also revealed disrupted F-actin structure and aberrant mitochondrial aggregation in response to s-OT. Conclusions s-T recapitulates training positive adaptations, whereas s-OT recapitulates many of the muscle maladaptation observed in overtraining. Our next studies in human OTS muscle will validate key findings from our in vitro s-OT model and guide our mechanistic investigations into the molecular mechanisms of OTS.

HYQTD Drug-containing Serum Alleviates H2O2-induced Endothelial Oxidative Damage by Increasing Mitochondrial ATP Synthesis and Inhibiting ROS.

Atherosclerosis (AS) is caused by the endothelium injury associated with oxidative stress. Previous studies have shown that the Phlegm-Eliminating and Stasis- Transforming Decoction (Huayu Qutan Decoction, HYQTD) has mitochondrial protective function. The objective of this research was to explore how HYQTD drug-containing serum (HYQTD-DS) could potentially protect mitochondrial energy production in endothelial cells (ECs) from injury caused by hydrogen peroxide (H2O2)-induced oxidative damage in AS through SIRT1/PGC-1α/ Nrf2 pathway. After preparation of containing serum, the cells were divided into various categories, such as control group, H2O2 group (an oxidative damage model), HYQTD group, Selisistat (EX527, a SIRT1 inhibitor) combined with H2O2 group, and EX527 combined with HYQTD group. The evaluation of oxidative stress involved measuring reactive oxygen species (ROS) and malondialdehyde (MDA) generation, as well as Superoxide Dismutase (SOD) activity. Mitochondrial function and ultrastructure were measured by Transmission electron microscopy (TEM), mitochondrial membrane potential (MMP), rate of oxygen consumption (OCR), respiratory chain complex activities, and ATP production. The key proteins and gene levels in the SIRT1/PGC-1α/Nrf2 pathway was quantified by quantitative real-time PCR (RT-PCR) and Western blotting analysis. We found oxidative stress, mitochondrial damage, and mitochondrial energy disorder in H2O2-induced ECs. However it indicated a marked reversal after pretreated with HYQTD-DS. Mechanistically, EX527 induced increased oxidative stress, worse mitochondrial dysfunction, and less ATP synthesis. We demonstrated that HYQTD-DS attenuated oxidative stress, improved mitochondrial function, and up-regulated mitochondrial ATP synthesis by activating SIRT1/PGC- 1α/Nrf2 pathway-induced mitochondrial biogenesis and its downstream NADH dehydrogenase (ubiquinone) flavoprotein 2 (NDV2).

HUC-MSC preserves erectile function by restoring mitochondrial mass of penile smooth muscle cells in a rat model of cavernous nerve injury via SIRT1/PGC-1a/TFAM signaling

BackgroundCavernous nerve injury-induced erectile dysfunction (CNI-ED) is a common complication following radical prostatectomy and severely affects patients’ quality of life. The mitochondrial impairment in corpus cavernosum smooth muscle cells (CCSMCs) may be an important pathological mechanism of CNI-ED. Previous studies have shown that transplantation of human adipose derived stem cells (ADSC) can alleviate CNI-ED in a rat model. However, little is known about the effect of human umbilical cord mesenchymal stem cells (hUC-MSC) on CNI-ED. It remains unclear whether hUC-MSC can ameliorate mitochondrial damage in CCSMCs. In this study, we aimed to investigate the impacts of hUC-MSC on the mitochondrial mass and function of CCSMCs, as well as elucidate its underlying molecular mechanism.MethodsThe CNI-ED rat model was established by bilaterally crushing cavernous nerves. Subsequently, hUC-MSC were transplanted into the cavernosum and ADSC were injected as a positive control group. Erectile function evaluation and histological detection were performed 4 weeks after cell transplantation. In vitro, CCSMCs underwent hypoxia and were then co-cultured with ADSC or hUC-MSC using a transwell system. The mitochondrial mass and function, as well as signaling pathways, were investigated. To explore the role of the SIRT1/PGC-1α/TFAM pathway in regulating mitochondrial biogenesis of CCSMCs, we knocked down SIRT1 by siRNA.ResultsThe administration of hUC-MSC significantly improved erectile function of CNI-ED rats and reduced the ratio of collagen to smooth muscle. Specifically, hUC-MSC treatment restored mitochondrial mass and function in CCSMCs injured by CNI or hypoxia, and inhibited the apoptosis of CCSMCs. Mechanistically, the application of hUC-MSC activated SIRT1/PGC-1α/TFAM pathway both in rat penile tissues and CCSMCs. In addition, knockdown of SIRT1 in CCSMCs abolished the protective effects of hUC-MSC on mitochondrial mass and function, while leading to an increase in cellular apoptosis.ConclusionshUC-MSC contribute to the recovery of erectile function in CNI-ED rats by restoring mitochondrial mass and function of CCSMCs through the SIRT1/PGC-1α/TFAM pathway. Our present study offers new insights into the role and molecular mechanisms of hUC-MSC in regulating mitochondrial homeostasis, thereby facilitating the restoration of the erectile function in CNI-ED.

Expression profiling of circular RNAs in sepsis-induced acute gastrointestinal injury: insights into potential biomarkers and mechanisms

This study aimed to investigate the role of circular RNAs (circRNAs) in sepsis-induced acute gastrointestinal injury (AGI), focusing on their potential as biomarkers and their involvement in disease progression. Peripheral blood samples from 14 patients with sepsis-induced AGI and healthy volunteers were collected. RNA sequencing was performed to profile circRNA and miRNA expression. Differential expression analysis identified key regulatory RNAs. Functional enrichment analysis was conducted to explore biological pathways, and circRNA-miRNA interaction networks were constructed. Significant differences in circRNA and miRNA expression profiles were observed between sepsis-induced AGI patients and healthy controls. Several circRNAs, including hsa_circ_0008381 and hsa_circ_0071375, exhibited stepwise expression increases correlating with AGI severity. Functional enrichment analysis indicated that the host genes of differentially expressed circRNAs are involved in key biological processes like protein ubiquitination, organelle maintenance, and cellular signaling pathways such as mitochondrial biogenesis and lipid metabolism. CircRNA-miRNA interaction networks suggested their role as miRNA sponges, regulating key downstream processes. This study demonstrated the potential of circRNAs as diagnostic biomarkers and therapeutic targets for sepsis-induced AGI. Further research is warranted to validate their clinical utility and unravel their mechanistic roles in AGI progression.