Mitochondrial fission, fusion, and stress

Mitochondrial damage and ER stress in CB1 receptor antagonist-induced apoptosis in human neuroblastoma SH-SY5Y cells

Cannabinoid receptor type 1 (CB1R) is the key modulator of neuronal viability. CB1R antagonists provide neuroprotective effects on neurotoxicity caused by e.g. neuronal injury. However, the underlying mechanisms and potential limitations of CB1R antagonism remain unclear. Here we investigated the impact of environmental conditions on CB1R antagonist effects. We have found that cell-permeable CB1R antagonists, rimonabant and AM251, induced cell death in human neuroblastoma SH-SY5Y cells under serum-free conditions. Mitochondrial morphological analysis revealed mitochondrial swelling characterized by their network fragmentation and cristae reduction. Phosphoproteomics analysis showed the ER stress signaling pathway PERK/eIF2α/ATF4/CHOP, leading to caspase-dependent apoptosis. These results suggest that CB1R antagonists promote apoptosis via mitochondrial damage and ER stress under serum-free conditions in SH-SY5Y cells. Our findings indicate that while CB1R antagonists may be neuroprotective in certain conditions, they may also pose a neurotoxic risk in environments characterized by cellular stress or nutrient deprivation.

Autophagy-targeting modulation to promote peripheral nerve regeneration

Nerve regeneration following traumatic peripheral nerve injuries and neuropathies is a complex process modulated by diverse factors and intricate molecular mechanisms. Past studies have focused on factors that stimulate axonal outgrowth and myelin regeneration. However, recent studies have highlighted the pivotal role of autophagy in peripheral nerve regeneration, particularly in the context of traumatic injuries. Consequently, autophagy-targeting modulation has emerged as a promising therapeutic approach to enhancing peripheral nerve regeneration. Our current understanding suggests that activating autophagy facilitates the rapid clearance of damaged axons and myelin sheaths, thereby enhancing neuronal survival and mitigating injury-induced oxidative stress and inflammation. These actions collectively contribute to creating a favorable microenvironment for structural and functional nerve regeneration. A range of autophagy-inducing drugs and interventions have demonstrated beneficial effects in alleviating peripheral neuropathy and promoting nerve regeneration in preclinical models of traumatic peripheral nerve injuries. This review delves into the regulation of autophagy in cell types involved in peripheral nerve regeneration, summarizing the potential drugs and interventions that can be harnessed to promote this process. We hope that our review will offer novel insights and perspectives on the exploitation of autophagy pathways in the treatment of peripheral nerve injuries and neuropathies.

Mitochondrial calcium uniporter regulates human fibroblast-like synoviocytes invasion via altering mitochondrial dynamics and dictates rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease that currently has no cure. Fibroblast-like synoviocytes (FLS), present in the RA synovium, play a pivotal role in RA pathogenesis. Notably, FLS in the RA patients (RA-FLS) exhibit characteristics similar to cancer cells, like enhanced migration, invasiveness, uncontrolled proliferation, resistance to apoptosis, and metabolic reprogramming. RA-FLS invasiveness is linked to radiographic joint damage in the patients, whereas inhibiting the FLS migration mitigates disease pathology. However, the molecular mechanisms underlying the migration and invasion capabilities of RA-FLS are not entirely understood. In this work, we have explored the function of mitochondrial calcium uniporter (MCU) and calcium signaling in FLS invasion. Our findings demonstrate a positive correlation between MCU expression and RA disease score. Interestingly, mitochondrial size was reduced, and peripheral localization was more pronounced in the RA-FLS when compared to the control FLS. Mitochondrial calcium import inhibition in the FLS by specific MCU inhibitor, Ruthenium-360 restored these altered mitochondrial dynamics and reduced the invasive phenotype. Through unbiased transcriptome analysis, we identified that MCU-mediated calcium signaling in RA-FLS leads to the enriched actin cytoskeleton and focal adhesion pathways responsible for the invasion phenotype, which can be effectively suppressed by inhibiting MCU. Additionally, we found that mitochondrial transport facilitator Miro1 binds to MCU in a calcium-dependent manner and regulates MCU-mediated mitochondrial dynamics and RA-FLS invasion. Experiments utilizing mice xenograft model demonstrated that MCU silencing diminishes the migration of RA-FLS toward the sites of inflammation in the immunocompromised SCID mice. Altogether, our findings highlight MCU as a promising therapeutic target to inhibit RA-FLS migration and RA progression.

7'-Hydroxyl substituted xanthones from Gentianella acuta revert hepatic steatosis in obese diabetic mice through preserving mitochondrial homeostasis

Mitochondrial dysfunction is a key contributor to the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Xanthones, bioactive flavonoids derived from various herbal medicines, are renowned for their anti-inflammatory, antioxidant, and anti-tumor properties. This study aimed to investigate the effects of xanthones isolated from Gentianella acuta on hepatic steatosis and the underlying mechanisms regulating mitochondrial function. We report that a xanthone fraction (400 mg/kg/day) effectively prevented obesity and hepatic steatosis in obese diabetic db/db mice in vivo. In vitro, xanthones inhibited lipid accumulation and mitochondrial dysfunction induced by high glucose (20 mM) and high palmitic acid (200 µM) in HepG2 cells. Mechanistically, norathyriol (NTR), a major in vivo metabolite of Gentianella acuta, inhibited the activity of dynamin-related protein 1 (Drp1), a protein associated with mitochondrial fission, and prevented its translocation from the cytoplasm to the mitochondria by inhibiting the orphan nuclear receptor (Nur77). Additionally, NTR increased the expression of the mitochondrial outer membrane protein FUN14 domain containing 1 (FUNDC1), which stimulated mitophagy to clear damaged or dysfunctional mitochondria under overnutrition conditions. We also discovered that reactive oxygen species (ROS) targeted FUNDC1, leading to mitochondrial damage, but this effect could be reversed by 7'-hydroxyl substituted xanthones. Collectively, 7'-hydroxyl substituted xanthones inhibited mitochondrial fission while promoting mitophagy, ultimately improving mitochondrial and liver function in diabetic hepatic steatosis. The modulation of mitochondrial function by 7'-hydroxyl substituted xanthones presents a novel approach for treating hepatic steatosis, particularly in diabetic conditions.

Ceria nanoparticles alleviate myocardial ischemia-reperfusion injury by inhibiting cardiomyocyte apoptosis via alleviating ROS mediated excessive mitochondrial fission

Reperfusion through thrombolytic therapy or primary percutaneous coronary intervention is commonly used to deal with acute myocardial infarction. However, the reperfusion procedure is accompanied by myocardial ischemia-reperfusion injury (MIRI). Currently, there is no therapeutics that can effectively deal with MIRI in clinical practice. Herein, the potential of ceria nanoparticles (CNPs) coated by different ligands in the treatment of rat MIRI is evaluated. The results demonstrate that CNPs can effectively modulate the oxidative stress in the heart tissue through the elimination of reactive oxygen species (ROS) and stimulation of endogenous antioxidant system. The inhibition of oxidative stress results in the reduction of p-Drp1 (Ser 616) which is critical in driving the fission and fragmentation of mitochondria. The improved mitochondrial dynamics saves the cardiomyocytes from apoptosis and reduces the acute injury of left ventricular wall during the MIRI. The ejection function of the left ventricle for both the short-term and long-term MIRI rats is well preserved. We therefore believe based on these results that the administration of CNPs is beneficial in the attenuation of MIRI during the acute stage. These findings provide useful information for the future fabrication of inorganic antioxidant nanomedicine for the treatment of MIRI.

Frequent Tetanic Exercise Through Electrical Muscle Stimulation May Reduce Immobilization-Induced Muscle Fibrosis by Suppressing Myonuclear Apoptosis

INTRODUCTION/AIMS

Immobilization-induced fibrosis is the primary pathogenesis of muscle contracture, and its trigger is myonuclear apoptosis. Tetanic exercise through electrical muscle stimulation may be able to mitigate myonuclear apoptosis; this could be an intervention strategy for Immobilization-induced fibrosis. In the present study, this was tested using rat skeletal muscles.

METHODS

Rats were divided into the control, immobilization, low-contraction frequency (LCF), and high-contraction frequency (HCF) groups. The soleus muscles were used as specimens.

RESULTS

The number of TUNEL-positive myonuclei was 0.36 ± 0.11, 4.66 ± 0.90, 4.25 ± 0.99, and 1.90 ± 0.46 in the control, immobilization, LCF, and HCF groups, respectively. The HCF group was lower than the immobilization and LCF groups (all p < 0.001). The number of myonuclei and cross-sectional area (CSA) in the HCF group was higher than in the immobilization and LCF groups (all p < 0.001). The number of macrophages, mRNA expression of IL-1β, TGF-β1, and α-SMA, and hydroxyproline contents in the HCF group was lower than in the immobilization and LCF groups (all p < 0.001). There were moderate to strong negative correlations between the number of TUNEL-positive myonuclei and the number of myonuclei and between the CSA and the number of macrophages. Moderate to strong positive correlations were found between the number of myonuclei and the CSA, the number of macrophages and IL-1β, IL-1β and TGF-β1, TGF-β1 and α-SMA, and α-SMA and hydroxyproline contents.

DISCUSSION

Frequent tetanic exercise might mitigate macrophage accumulation caused by myonuclear apoptosis and suppress immobilization-induced muscle fibrosis due to fibrosis-associated molecule overexpression.

Single-cell RNA sequencing-guided engineering of mitochondrial therapies for intervertebral disc degeneration by regulating mtDNA/SPARC-STING signaling

Intervertebral disc degeneration (IVDD) is a leading cause of discogenic low back pain, contributing significantly to global disability and economic burden. Current treatments provide only short-term pain relief without addressing the underlying pathogenesis. Herein we report engineering of biomimetic therapies for IVDD guided by single-cell RNA-sequencing data from human nucleus pulposus tissues, along with validation using animal models. In-depth analyses revealed the critical role of mitochondrial dysfunction in fibrotic phenotype polarization of nucleus pulposus cells (NPCs) during IVDD progression. Consequently, mitochondrial transplantation was proposed as a novel therapeutic strategy. Transplanted exogeneous mitochondria improved mitochondrial quality control in NPCs under pathological conditions, following endocytosis, separate distribution or fusion with endogenous mitochondria, and transfer to neighboring cells by tunneling nanotubes. Correspondingly, intradiscal mitochondrial transplantation significantly delayed puncture-induced IVDD progression in rats, demonstrating efficacy in maintaining mitochondrial homeostasis and alleviating pathological abnormalities. Furthermore, exogenous mitochondria were engineered with a bioactive, mitochondrial-targeting macromolecule to impart anti-oxidative and anti-inflammatory activities. The obtained multi-bioactive biotherapy exhibited significantly enhanced benefits in IVDD treatment, in terms of reversing IVDD progression and restoring structural integrity through the mtDNA/SPARC-STING signaling pathways. Overall, our engineered mitochondrial therapies hold great promise for treating IVDD and other musculoskeletal diseases linked to mitochondrial dysfunction.

Mitophagy in Alzheimer's disease and other metabolic disorders: A focus on mitochondrial-targeted therapeutics

Mitochondria, as central regulators of cellular processes such as energy production, apoptosis, and metabolic homeostasis, are essential to cellular function and health. The maintenance of mitochondrial integrity, especially through mitophagy-the selective removal of impaired mitochondria-is crucial for cellular homeostasis. Dysregulation of mitochondrial function, dynamics, and biogenesis is linked to neurodegenerative and metabolic diseases, notably Alzheimer's disease (AD), which is increasingly recognized as a metabolic disorder due to its shared pathophysiologic features: insulin resistance, oxidative stress, and chronic inflammation. In this review, we highlight recent advancements in pharmacological interventions, focusing on agents that modulate mitophagy, mitochondrial uncouplers that reduce oxidative phosphorylation, compounds that directly scavenge reactive oxygen species to alleviate oxidative stress, and molecules that ameliorate amyloid beta plaque accumulation and phosphorylated tau pathology. Additionally, we explore dietary and lifestyle interventions-MIND and ketogenic diets, caloric restriction, physical activity, hormone modulation, and stress management-that complement pharmacological approaches and support mitochondrial health. Our review underscores mitochondria's central role in the pathogenesis and potential treatment of neurodegenerative and metabolic diseases, particularly AD. By advocating for an integrated therapeutic model that combines pharmacological and lifestyle interventions, we propose a comprehensive approach aimed at mitigating mitochondrial dysfunction and improving clinical outcomes in these complex, interrelated diseases.

Hypoxia-induced mitochondrial dysfunction and mitophagy in the small yellow croaker (Larimichthys polyactis)

Mitophagy serves as a pivotal mechanism for regulating the quantity and quality of mitochondria within cells, exerting significant influence on various processes such as cell differentiation, oxidative stress, inflammatory responses, and apoptosis. Currently, research on whether and how fish activate mitophagy under hypoxic stress conditions is still insufficient. In this study, to determine the mechanisms whereby marine fish adapt to hypoxic environments from the perspective of mitophagy, we used the small yellow croaker (Larimichthys polyactis) as the research subject and combined in vivo (liver) and in vitro (small yellow croaker fry [SYCF] cell line) hypoxic stress experiments. Fish exposed to hypoxic conditions were found to be characterized by liver tissue damage, and we detected significant elevations in the levels of hydrogen peroxide in liver tissues and reactive oxygen species (ROS) in SYCF cells, along with significant reductions in mitochondrial membrane potential. These findings thus indicate that hypoxic stress leads to tissue damage, excessive ROS production, and mitochondrial damage. In further experiments, we pre-treated SYCF cells with the antioxidant N-acetylcysteine, which was found to effectively reduce ROS levels and prevented the loss of mitochondrial membrane potential, thereby indicating that ROS play a crucial role in hypoxic stress-induced mitochondrial damage. Subsequently, to investigate whether hypoxic stress activates mitophagy to remove damaged mitochondria, we examined changes in the mRNA expression of mitophagy-related genes (bnip3, lc3b, bnip3l, beclin1, fundc1, and ulk1) in the liver and SYCF cells of L. polyactis exposed to hypoxic stress, and detected a significant upregulation of the mRNA expression of these genes. Furthermore, examination of liver ultrastructure and changes in the co-localization of mitochondria and lysosomes in SYCF cells revealed that hypoxic stress induces the formation of autophagosomes and autolysosomes in the liver, with an enhanced co-localization of mitochondria and lysosomes being observed after 6 h of hypoxia, which gradually increased with a prolongation of hypoxic exposure. We have, for the first time, exhibited the formation process of autophagosomes and the subsequent formation of autolysosomes in fish under hypoxic stress. These findings reveal the induction of mitophagy in L. polyactis in response to hypoxic stress, and indicate that these fish may initiate a mitophagic response to remove damaged mitochondria, reduce excessive ROS accumulation, and maintain cellular homeostasis. Our findings will not only lay a biological foundation for the breeding of hypoxia-tolerant strains of L. polyactis but also provide new insights into the mechanisms underlying the adaptation of marine fish to hypoxic environments.

Mitochondria: An overview of their origin, genome, architecture, and dynamics

Mitochondria are traditionally viewed as the powerhouses of eukaryotic cells, i.e., the main providers of the metabolic energy required to maintain their viability and function. However, the role of these ubiquitous intracellular organelles far extends energy generation, encompassing a large suite of functions, which they can adjust to changing physiological conditions. These functions rely on a sophisticated membrane system and complex molecular machineries, most of which imported from the cytosol through intricate transport systems. In turn, mitochondrial plasticity is rooted on mitochondrial biogenesis, mitophagy, fusion, fission, and movement. Dealing with all these aspects and terminology can be daunting for newcomers to the field of mitochondria, even for those with a background in biological sciences. The aim of the present educational article, which is part of a special issue entitled "Mitochondria in aging, cancer and cell death", is to present these organelles in a simple and concise way. Complex molecular mechanisms are deliberately omitted, as their inclusion would defeat the stated purpose of the article. Also, considering the wide scope of the article, coverage of each topic is necessarily limited, with the reader directed to excellent reviews, in which the different topics are discussed in greater depth than is possible here. In addition, the multiple cell type-specific genotypic and phenotypic differences between mitochondria are largely ignored, focusing instead on the characteristics shared by most of them, with an emphasis on mitochondria from higher eukaryotes. Also ignored are highly degenerate mitochondrion-related organelles, found in various anaerobic microbial eukaryotes lacking canonical mitochondria.

Iridoid glycosides in kidney-tonifying Chinese medicinal herbs: Mechanisms and implications for Alzheimer's disease therapy

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is an incurable and irreversible type of dementia. Existing drugs cannot meet clinical needs; thus, developing new treatments is necessary. Traditional Chinese medicine (TCM) has been used in the prevention and treatment of AD. TCM holds the theory that "the kidney support brain function" and believes that dementia can be addressed from a kidney-based perspective. Kidney-tonifying herbs are a class of medicines that have the effect of tonifying the kidney and benefiting the brain. Some of these herbs have been shown to have anti-AD effects. Iridoid glycosides (IGs), which are important components of kidney-tonifying herbs, may have the potential to prevent and treat AD. However, their effects on AD have not yet been reviewed.

AIM OF THE REVIEW

This literature review provides a comprehensive summary of the potential of IGs in the prevention and treatment of AD. It also sets the foundation for future studies that will make the use of such drugs in clinical practice possible.

MATERIAL AND METHODS

Kidney-tonifying Chinese herbs were selected with reference to the Chinese Pharmacopoeia (2020 edition) and the textbook of Chinese Materia Medica (5th edition). Literature survey was conducted using PubMed, Web of Science, Google Scholar, and CNKI, with "Alzheimer's disease," "kidney-tonifying Chinese medicinal herbs," and "Iridoid Glycosides" as the primary keywords.

RESULTS

Kidney-tonifying herbal IGs include loganin, morroniside, verbenalin, cornuside, catalpol, rehmannioside A, geniposidic acid, and aucubin. These IGs have shown multiple pharmacological effects, including anti-AD effects. The effective mechanisms of IGs for AD treatment include anti-oxidative stress, inhibiting neuronal apoptosis, antagonizing amyloid neurotoxicity and tau protein hyperphosphorylation, regulating immune function, anti-inflammation, normalizing the function of the cholinergic nervous system, recuperating neurobiochemical, and regulating AD-related genes. Consequently, IGs can combat AD by modulating multiple targets and pathways.

CONCLUSION

Kidney-tonifying herbal IGs have great potential to combat AD.

Ormeloxifene induces mitochondrial fission-mediated pro-death autophagy in colon cancer cells

Ormeloxifene (ORM) is a nonsteroidal selective estrogen receptor modulator (SERM), developed by the CSIR-Central Drug Research Institute that is approved as an oral contraceptive. However, it has also shown promising anti-cancer activity, especially in breast cancer. Here, we have investigated the anti-cancer effect of ORM on colon cancer cells and show that its antiproliferative activity is mediated through mitochondrial fission and autophagy-associated cell death. We observed that ORM treatment led to an elevation in autophagy markers like LC3II, Beclin1, and Atg7. Autophagy induction and LC3II turnover were monitored by immunofluorescence staining and confocal microscopy. Transmission electron microscopy results confirmed the formation of autophagosomes and autophagolysosomes. Autophagic flux was confirmed by the increased expression of LC3II in cells co-treated with BafilomycinA1(autophagy inhibitor) and ORM. This was further corroborated using tandem mRFP-GFP-LC3 (tfLC3) transfection in DLD-1 cells. Interestingly, we observed that inhibition of autophagy reduced the apoptotic cell population, suggesting pro-death autophagy. ORM treatment caused notable ultrastructural alterations indicative of cellular stress. Notably, ORM triggered the generation of mitochondrial ROS, associated with increased levels of mitochondrial fission and a decrease in mitochondrial fusion proteins. Changes in mitochondrial dynamics were observed under the TEM, which included reduced mitochondrial size and increased mitochondrial number. Inhibition of mitochondrial fission resulted in enhanced cell survival and a concomitant decrease in the autophagic markers, implying that ORM-induced autophagy depends on mitochondrial fission. Taken together, our findings bring to light a novel mechanism where Ormeloxifene targets mitochondrial dynamics to promote autophagy-associated cell death in colon cancer cells.

Antibiotic erythromycin in fish: Pharmacokinetics, effects, and health risks

Erythromycin is a macrolide antibiotic commonly utilized in veterinary medicine and aquaculture. It functions by binding to the 50S subunit of 70S ribosomes, inhibiting protein synthesis and effectively treating numerous bacterial diseases. Due to the extensive use of erythromycin, it has been detected in various aquatic systems in recent years. Multiple studies have reported the occurrence of erythromycin resistance and its adverse effects on diverse aquatic organisms. Consequently, potential environmental health risks associated with erythromycin have garnered increasing attention. As an integral component of aquatic ecosystems, fish have been the subject of numerous reports regarding the bioaccumulation and adverse effects of erythromycin; however, these data have not been collated and interpreted. This report provides a comprehensive overview of the environmental fate of erythromycin, detection methods, pharmacokinetics, and impacts on fish. In addition to the therapeutic benefits against pathogens, acute or chronic exposure of fish to erythromycin at concentrations ranging from μg/L to mg/L disrupts the primary defense, antioxidant, and xenobiotic metabolism systems, leading to oxidative stress, cellular structural damage, and metabolic disorders, manifesting as cytotoxicity, organ toxicity, neurotoxicity, developmental toxicity, and reproductive toxicity. However, further in-depth studies are warranted to evaluate the therapeutic efficacy at relatively high levels, particularly when considering pathogens with developed resistance to erythromycin, as well as the long-term effects of erythromycin exposure at environmentally relevant concentrations in fish, thereby better assessing the health risks posed by erythromycin to fish and their consumers humans.

Ionizing radiation induces mild and dose-independent damage to mitochondria in newt cells

In addition to remarkable regenerative abilities, newts demonstrate a heightened tolerance to radiation compared to mammals. Mitochondria play profound role in cell survival when cells undergo environmental stresses. Thus, our study sought to elucidate the impact of ionizing radiation (IR) on the mitochondria of a newt model Pleurodeles waltl. Primary cells derived from limb tissue of P. waltl were exposed to 0, 5, 10, or 15 Gy X-ray and analyzed at 24h post-irradiation (PIR). Analysis using MitoTracker Red labeling revealed a maximal (p < 0.001) in mitochondrial fission in cells exposed to 5 Gy IR, while mitochondrial fission in cells exposed to 10 and 15 Gy IR was comparable (p < 0.01). Mitochondrial superoxide levels increased in a reverse dose-dependent manner; notably, cells treated with 5 Gy IR produced significantly (p < 0.05) higher mitochondrial superoxide. Mitochondrial membrane potential (ΔΨm) decreased significantly (p < 0.01) with similar extent across all IR-treated groups. Though ΔΨm declined, the ATP content was not changed due to IR. Result from the MTT assay indicated no impairment in mitochondrial activity. Cell counting data suggest negligible impact of IR on viability of cells; however, the phase contrast imaging revealed senescent like morphology of cells. Taken together, cells of P. waltl show mild changes in morphology and function of the mitochondria in response to IR, but seem highly tolerant.

Upregulations of SNAT2 and GLS-1 Are Key Osmoregulatory Responses of Human Corneal Epithelial Cells to Hyperosmotic Stress

Dry eye syndrome (DES) affects millions of people worldwide. However, as the cellular responses of the corneal epithelium under hyperosmotic stress remain unclear, this study investigated the proteomic changes between human corneal epithelial cells (HCECs) cultured with isosmotic and hyperosmotic media. Under hyperosmotic stress, HCECs increased expressions of sodium-coupled neutral amino acid transporter (SNAT2), glutaminase (GLS-1), and a few isoforms of heat shock protein and aldo-keto reductase family 1. The expressions of SNAT2 and GLS-1 were increased after 6 h of exposure to hyperosmotic stress but not by glutamine deprivation. The hyperosmotic stress increased intracellular levels of glutamine, mitochondrial superoxide, and mitochondrial membrane potential and induced mitochondrial fission in HCECs. Thus, the intracellular level of glutamine was elevated in the hyperosmotic stressed HCECs via the upregulation of SNAT2. Glutamine can act as an osmolyte to regulate the osmolarity of HCECs or be converted to glutamate by GLS-1 for the tricarboxylic acid cycle and oxidative phosphorylation to maintain ATP production under the hyperosmotic stress-induced mitochondrial fission. Thus, the increases in the expressions of SNAT2 and GLS-1 are key osmoregulations in HCECs upon the hyperosmotic stress and may act as corneal biomarkers for monitoring DES progression.

Mitochondria-dependent innate immunity: A potential therapeutic target in Flavivirus infection

Mitochondria, known as the powerhouse of cells, play a crucial role in host innate immunity during flavivirus infections such as Dengue, Zika, West Nile, and Japanese Encephalitis Virus. Mitochondrial antiviral signaling protein (MAVS) resides on the outer mitochondrial membrane which is triggered by viral RNA recognition by RIG-I-like receptors (RLRs). This activation induces IRF3 and NF-κB signaling, resulting in type I interferon (IFN) production and antiviral responses. Upon flavivirus infection, mitochondrial stress and dysfunction may lead to the release of mitochondrial DNA (mtDNA) into the cytoplasm, which serves as a damage-associated molecular pattern (DAMP). Cytosolic mtDNA is sensed by cGAS (cyclic GMP-AMP synthase), leading to the activation of the STING (Stimulator of Interferon Genes) pathway to increase IFN production and expand inflammation. Flaviviral proteins control mitochondrial morphology by controlling mitochondrial fission (MF) and fusion (MFu), disrupting mitochondrial dynamics (MD) to inhibit MAVS signaling and immune evasion. Flaviviral proteins also cause oxidative stress, resulting in the overproduction of reactive oxygen species (ROS), which triggers NLRP3 inflammasome activation and amplifies inflammation. Additionally, flaviviruses drive metabolic reprogramming by shifting host cell metabolism from oxidative phosphorylation (OxPhos) to glycolysis and fatty acid synthesis, creating a pro-replicative environment that supports viral replication and persistence. Thus, the present review explores the complex interaction between MAVS, mtDNA, and the cGAS-STING pathway, which is key to the innate immune response against flavivirus infections. Understanding these mechanisms opens new avenues in therapeutic interventions in targeting mitochondrial pathways to enhance antiviral immunity and mitigate viral infection.

Plaat1 deficiency reduces cardiac cardiolipin content and impairs exercise tolerance

Phospholipase A and acyltransferase 1 (PLAAT1) catalyzes O-transacylase, N-transacylase and phospholipase A1/2 reactions. We have demonstrated that PLAAT1 has O-transacylase activity in vitro using phosphatidylcholine as an acyl donor, and monolysocardiolipin (MLCL) as an acyl acceptor, generating cardiolipin. However, a role for PLAAT1 in cardiolipin regulation in vivo has not yet been reported. We generated Plaat1-deficient (Plaat1-/-) mice and studied males and females for gross morphological differences, food intakes, respiratory gas exchange, total energy expenditure, and voluntary activity. We also evaluated cardiac cardiolipin contents, levels of mitochondrial proteins, and exercise capacity. Sex-matched Plaat1-/- mice had highly similar body weights to their wildtype (Wt) littermates, although male Plaat1-/- mice ate less. Male and female Plaat1-/- hearts were 14.2% and 10.6% smaller, respectively. Cardiac cardiolipin levels were ∼1/3 lower in male and female Plaat1-/- mice compared to their sex-matched Wt littermates, largely due to lower cardiolipin linoleate. Levels of the mitochondrial protein SDHA were 13.8% and 16.3% lower in male and female Plaat1-/- mice, respectively. Both male and female Plaat1-/- mice had significantly lower oxygen consumption, carbon dioxide production, and total energy expenditure, and male Plaat1-/- mice had lower rearing activity than their sex-matched Wt littermates. While other measures of voluntary activity, including locomotion and ambulation did not differ significantly between genotypes, both males and females had reduced exercise tolerance. This work demonstrates a critical role for PLAAT1 in cardiac cardiolipin content and the regulation of energy metabolism and exercise tolerance in vivo.

A hidden cysteine in Fis1 targeted to prevent excessive mitochondrial fission and dysfunction under oxidative stress

Fis1-mediated mitochondrial localization of Drp1 and excessive mitochondrial fission occur in human pathologies associated with oxidative stress. However, it is not known how Fis1 detects oxidative stress and what structural changes in Fis1 enable mitochondrial recruitment of Drp1. We find that conformational change involving α1 helix in Fis1 exposes its only cysteine, Cys41. In the presence of oxidative stress, the exposed Cys41 in activated Fis1 forms a disulfide bridge and the Fis1 covalent homodimers cause increased mitochondrial fission through increased Drp1 recruitment to mitochondria. Our discovery of a small molecule, SP11, that binds only to activated Fis1 by engaging Cys41, and data from genetically engineered cell lines lacking Cys41 strongly suggest a role of Fis1 homodimerization in Drp1 recruitment to mitochondria and excessive mitochondrial fission. The structure of activated Fis1-SP11 complex further confirms these insights related to Cys41 being the sensor for oxidative stress. Importantly, SP11 preserves mitochondrial integrity and function in cells during oxidative stress and thus may serve as a candidate molecule for the development of treatment for diseases with underlying Fis1-mediated mitochondrial fragmentation and dysfunction.

Sestrin2 is a central regulator of mitochondrial stress responses in disease and aging

Mitochondria supply most of the energy for cellular functions and coordinate numerous cellular pathways. Their dynamic nature allows them to adjust to stress and cellular metabolic demands, thus ensuring the preservation of cellular homeostasis. Loss of normal mitochondrial function compromises cell survival and has been implicated in the development of many diseases and in aging. Although exposure to continuous or severe stress has adverse effects on cells, mild mitochondrial stress enhances mitochondrial function and potentially extends health span through mitochondrial adaptive responses. Over the past few decades, sestrin2 (SESN2) has emerged as a pivotal regulator of stress responses. For instance, SESN2 responds to genotoxic, oxidative, and metabolic stress, promoting cellular defense against stress-associated damage. Here, we focus on recent findings that establish SESN2 as an orchestrator of mitochondrial stress adaptation, which is supported by its involvement in the integrated stress response, mitochondrial biogenesis, and mitophagy. Additionally, we discuss the integral role of SESN2 in mediating the health benefits of exercise as well as its impact on skeletal muscle, liver and heart injury, and aging.

LRRC4 Deficiency Drives Premature Ovarian Insufficiency by Disrupting Metabolic Homeostasis in Granulosa Cells

Premature ovarian insufficiency (POI), defined by early loss of ovarian activity before the age of 40 years, is the leading cause of infertility and systematic aging in women, posing a public health challenge worldwide. However, its molecular etiology and therapeutic options are still lacking. Here, leucine-rich repeat containing 4 (LRRC4) is identified as a critical regulator of folliculogenesis expressed in granulosa cells (GCs), which contributes to ovarian reserve maintenance. LRRC4 deficiency triggers defective oocyte maturation and excessive follicular atresia through inhibition of GC differentiation and ultimately leads to POI. Mechanistically, LRRC4 balances mitochondrial fission and fusion to inhibit excessive mitophagy by promoting the K48-linked ubiquitination degradation of Yes-associated protein (YAP), thereby maintaining the metabolic homeostasis of mitochondrial aerobic respiration and glycolysis. Importantly, targeting LRRC4 normalized follicular development and ovarian function in POI model mice. In conclusion, these data reveal the novel pathogenesis of POI and suggest that LRRC4 is a potential target for the diagnosis and treatment of POI.

SIRT3-Mediated Deacetylation of DRP1K711 Prevents Mitochondrial Dysfunction in Parkinson's Disease

Dysregulation of mitochondrial dynamics is a key contributor to the pathogenesis of Parkinson's disease (PD). Aberrant mitochondrial fission induced by dynamin-related protein 1 (DRP1) causes mitochondrial dysfunction in dopaminergic (DA) neurons. However, the mechanism of DRP1 activation and its role in PD progression remain unclear. In this study, Mass spectrometry analysis is performed and identified a significant increased DRP1 acetylation at lysine residue 711 (K711) in the mitochondria under oxidative stress. Enhanced DRP1K711 acetylation facilitated DRP1 oligomerization, thereby exacerbating mitochondrial fragmentation and compromising the mitochondrial function. DRP1K711 acetylation also affects mitochondrial DRP1 recruitment and fission independent of canonical S616 phosphorylation. Further analysis reveals the critical role of sirtuin (SIRT)-3 in deacetylating DRP1K711, thereby regulating mitochondrial dynamics and function. SIRT3 agonists significantly inhibit DRP1K711 acetylation, rescue DA neuronal loss, and improve motor function in a PD mouse model. Conversely, selective knockout of SIRT3 in DA neurons exacerbates DRP1K711 acetylation, leading to increased DA neuronal damage, neuronal death, and worsened motor dysfunction. Notably, this study identifies a novel mechanism involving aberrant SIRT3-mediated DRP1 acetylation at K711 as a key driver of mitochondrial dysfunction and DA neuronal death in PD, revealing a potential target for PD treatment.

Mitochondrial Quality Control in Ovarian Function: From Mechanisms to Therapeutic Strategies

Mitochondrial quality control plays a critical role in cytogenetic development by regulating various cell-death pathways and modulating the release of reactive oxygen species (ROS). Dysregulated mitochondrial quality control can lead to a broad spectrum of diseases, including reproductive disorders, particularly female infertility. Ovarian insufficiency is a significant contributor to female infertility, given its high prevalence, complex pathogenesis, and profound impact on women's health. Understanding the pathogenesis of ovarian insufficiency and devising treatment strategies based on this understanding are crucial. Oocytes and granulosa cells (GCs) are the primary ovarian cell types, with GCs regulated by oocytes, fulfilling their specific energy requirements prior to ovulation. Dysregulation of mitochondrial quality control through gene knockout or external stimuli can precipitate apoptosis, inflammatory responses, or ferroptosis in both oocytes and GCs, exacerbating ovarian insufficiency. This review aimed to delineate the regulatory mechanisms of mitochondrial quality control in GCs and oocytes during ovarian development. This study highlights the adverse consequences of dysregulated mitochondrial quality control on GCs and oocyte development and proposes therapeutic interventions for ovarian insufficiency based on mitochondrial quality control. These insights provide a foundation for future clinical approaches for treating ovarian insufficiency.

Selenium-loaded porous silica nanospheres improve cardiac repair after myocardial infarction by enhancing antioxidant activity and mitophagy

Myocardial infarction (MI) is the leading cause of death globally, often resulting to significant loss of cardiac function. A key factor in the pathological progression of MI is the excessive generation of reactive oxygen species (ROS) by dysfunctional mitochondria. However, no antioxidant therapy has been approved for clinical treatment of MI to date. In this study, selenium-loaded porous silica nanospheres (Se@PSN) are synthesized as a novel therapeutic approach for MI. These nanospheres are capable of neutralizing various ROS, thereby reducing hypoxia-induced myocardial cell damage. Additionally, Se@PSN promote the upregulation of antioxidant proteins, providing sustained intracellular ROS scavenging, which helps reduce infarct size and preserve cardiac function post-MI. The sustained antioxidant effects of Se@PSN are attributed to their ability to safeguard mitochondrial function by modulating oxidative phosphorylation, mitochondrial dynamics, and mitophagy. The activation of mitophagy by Se@PSN is achieved through the upregulation of HIF-1α expression. In conclusion, Se@PSN show significant potential for clinical translation as a novel therapeutic strategy for MI.

Mitochondria-targeting materials and therapies for regenerative engineering

The hemostatic, inflammatory, proliferative, and remodeling phases of healing require precise spatiotemporal coordination and orchestration of numerous biological processes. As the primary energy generators in the cell, mitochondria play multifunctional roles in regulating metabolism, stress reactions, immunity, and cell density during the process of tissue regeneration. Mitochondrial dynamics involves numerous crucial processes, fusion, fission, autophagy, and translocation, which are all necessary for preserving mitochondrial function, distributing energy throughout cells, and facilitating cellular signaling. Tissue regeneration is specifically associated with mitochondrial dynamics due to perturbations of Ca2+, H2O2 and ROS levels, which can result in mitochondrial malfunction. Increasing evidence from multiple models suggests that clinical interventions or medicinal drugs targeting mitochondrial dynamics could be a promising approach. This review highlights significant advances in the understanding of mitochondrial dynamics in tissue regeneration, with specific attention on mitochondria-targeting biomaterials that accelerate multiple tissues' regeneration by regulating mitochondrial metabolism. The innovations in nanomaterials and nanosystems enhance mitochondrial-targeting therapies are critically examined with the prospects of modulating mitochondrial dynamics for new therapies in regenerative engineering.

The extrahepatic markers in postmenopausal women with metabolic dysfunction-associated steatotic liver disease: A systematic review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent, multifactorial systemic metabolic disorder, now recognized as the most common chronic liver disease globally. Female susceptibility to MASLD varies across menstrual states, influenced by genetic factors, age, menopausal status, and physical activity. Postmenopausal women, experiencing a significant reduction in estrogen, are particularly vulnerable to metabolic imbalances, increasing their risk of MASLD, disease progression, liver fibrosis, insulin resistance, and adverse cardiovascular events compared to premenopausal women and age-matched men. This review systematically synthesizes current research on extrahepatic abnormalities associated with MASLD in postmenopausal women. This review identifies key extrahepatic markers associated with MASLD in postmenopausal women, highlighting gaps in current research and proposing targeted screening and management strategies. (Graphical Abstract).

Mn2O3 NPs-induced liver injury is potentially associated with gut microbiota dysbiosis in broiler chicken

Mn2O3 nanometer particles(Mn2O3 NPs), a new material, is widely used in medicine, electrochemical sensing and energy storage fields. The widespread use of Mn2O3 NPs has caused health concerns, and it is necessary to clarify the toxic mechanism of Mn2O3 NPs exposure. Our findings showed that Mn2O3 NPs exposure could lead to liver histological abnormalities, mitochondrial dysfunction in liver, as well as mitochondrial-mediated apoptosis, autophagy and mitochondrial dynamics disorder, and eventually lead to liver injury. At the same time, the ileal epithelium suffered physiological damage and inflammation after Mn2O3 NPs exposure, and the expression levels of genes and proteins related to intestinal barrier function (MUC1 ZO-1 Claudin1 and Occludin) were significantly down-regulated. Meanwhile, 16s sequencing analysis of intestinal bacteria showed that Mn2O3 NPs exposure caused significant changes in intestinal flora abundance. The Firmicutes/Bacteroidetes ratio increased, and the abundance of probiotics (Bacteroides, Bifidobacterium, Faecalibacterium) decreased, while the abundance of harmful bacteria (Streptococcus, Enterococcus, Pseudomonas) increased. The changes in these microflorae may potentially impact the development of liver injury. Altogether, these results provide novel insights into the potential mechanism of Mn2O3 NPs related hepatotoxicity induced by gut microbiota via the gut-liver axis, and contribute to a better interpretation of the health impact of Mn2O3 NPs.

OPA1 mutations in dominant optic atrophy: domain-specific defects in mitochondrial fusion and apoptotic regulation

BACKGROUND

Autosomal dominant optic atrophy (ADOA), a leading common inherited optic neuropathy, arises from progressive retinal ganglion cell degeneration, often linked to OPA1 mutations. OPA1, a mitochondrial GTPase, regulates mitochondrial fusion, crista structure, and apoptosis. While GTPase-related dysfunction is well-studied, the role of other OPA1 domains in ADOA pathology remains unclear.

METHODS

To investigate ADOA-linked OPA1 mutations, we assessed mitochondrial morphology, membrane potential, cytochrome c release, and cell viability in primary cortical neurons and N2a cells expressing OPA1 wild-type or mutant constructs. RNA sequencing and structural predictions (SWISS-MODEL) provided insights into molecular pathways and structural impacts.

RESULTS

Two ADOA-associated mutations were characterized: V465F (GTPase β-fold) and V560F (BSE α-helix). Both mutations impaired mitochondrial fusion and cell survival under apoptotic stimuli. Notably, the BSE-located V560F mutation caused greater deficits in membrane potential maintenance, earlier apoptosis, and distinct molecular pathway changes compared to V465F.

CONCLUSIONS

This study highlights the domain-specific impacts of OPA1 mutations on mitochondrial function and ADOA pathology, revealing unique roles of the BSE domain in apoptosis regulation and mitochondrial integrity. These findings provide insights into ADOA mechanisms and potential therapeutic targets.

The role and machine learning analysis of mitochondrial autophagy-related gene expression in lung adenocarcinoma

Objective

Lung adenocarcinoma (LUAD) continues to be a primary cause of cancer-related mortality globally, highlighting the urgent need for novel insights finto its molecular mechanisms. This study aims to investigate the relationship between gene expression and mitophagy in LUAD, with an emphasis on identifying key biomarkers and elucidating their roles in tumorigenesis and immune cell infiltration.

Methods

We utilized datasets GSE151101 and GSE203609 from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) associated with lung cancer and mitophagy. DEGs were identified using GEO2R, filtered based on criteria of P < 0.05 and log2 fold change ≥ 1. Subsequently, Weighted Gene Co-expression Network Analysis (WGCNA) was conducted to classify DEGs into modules. Functional annotation of these modules was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Gene Set Enrichment Analysis (GSEA) was applied to the most relevant module, designated as the greenyellow module. To identify critical biomarkers, machine learning algorithms including Random Forest, Least Absolute Shrinkage and Selection Operator (LASSO) regression, and Support Vector Machine (SVM) were employed. Validation of the findings was conducted using The Cancer Genome Atlas (TCGA) database, Human Protein Atlas (HPA), quantitative PCR (qPCR), and immune cell infiltration analysis via CIBERSORTx.

Results

Our analysis identified 11,012 overlapping DEGs between the two datasets. WGCNA revealed 11 modules, with the green-yellow module exhibiting the highest correlation. Functional enrichment analysis highlighted significant associations with FOXM1 signaling pathways and retinoblastoma in cancer. Machine learning algorithms identified COASY, FTSJ1, and MOGS as pivotal genes. These findings were validated using TCGA data, qPCR experiments, which demonstrated high expression levels in LUAD samples. Immunohistochemistry from HPA confirmed consistency between protein levels and RNA-seq data. Furthermore, pan-cancer analysis indicated that these genes are highly expressed across various cancer types. Immune infiltration analysis suggested significant correlations between these genes and specific immune cell populations.

Conclusion

COASY, FTSJ1 and MOGS have emerged as critical biomarkers in LUAD, potentially influencing tumorigenesis through mitophagy-related mechanisms and immune modulation. These findings provide promising avenues for future research into targeted therapies and diagnostic tools, thereby enhancing LUAD management.

Drp1 mitochondrial fission in astrocyte modulates behavior and neuroinflammation during morphine addiction

BACKGROUND

Mitochondrial dynamics in neurons accompanied by neuroinflammation has been proved as pivotal events during repeated morphine exposure, however, the relationship between mitochondrial dynamics and neuroinflammation still remains unknown.

METHODS

This study was designed to investigate the potential role of astrocyte Drp1 in neuroinflammation during morphine addiction. Nucleus accumbens (NAc) tissues were collected for immunofluorescence, transmission electron microscopy (TEM) and quantitative real-time polymerase chain reaction (qRT-PCR) to detect the expression of pro-inflammatory cytokines and mitochondrial fission proteins. Morphine-induced conditioned place preference (CPP) and open field test (OFT) were used to determine the effects of Mdivi-1, a selective inhibitor of mitochondrial fission protein Drp1 in the rewarding properties of morphine. Astrocyte-specific knockdown experiments by an adeno-associated virus (AAV) vector containing shRNADrp1-EGFP infusion were performed to determine the effects of astrocyte Drp1 in NAc of mice with morphine treatment.

RESULTS

In this study, we found that repeated morphine exposure induced mitochondrial fragmentation in neurons, astrocytes, and microglia in NAc, correlating with increased inflammatory markers and addictive behaviors. The application of Mdivi-1 effectively mitigated mitochondrial fragmentation and astrocyte-mediated neuroinflammation within the NAc, thereby alleviating morphine-induced addictive behaviors. Crucially, the astrocyte-specific knockdown of Drp1 in NAc significantly curtailed drug-seeking behavior and substantially reduced neuroinflammation.

CONCLUSIONS

Collectively, our findings suggest that alterations in mitochondrial dynamics, particularly within astrocytes, play an important role in regulating neuroinflammation associated with morphine addiction. This research offers novel insights into potential therapeutic strategies for addressing substance use disorder (SUD) by regulating mitochondrial dynamics within astrocyte.

Modulating mitochondrial dynamics preserves cognitive performance via ameliorating iron-mediated brain toxicity in iron-overload rats

This study aimed to demonstrate the pharmacological efficacy of mitochondrial dynamics modulators, including the fission inhibitor Mdivi-1 and the fusion promoter M1, on parameters in brain and cognitive performance in rats with iron overload condition. Forty male Wistar rats were randomly categorized into two groups to receive either 10% dextrose in normal saline (control, n = 8) or iron dextran (100 mg/kg, Fe group, n = 32) via intraperitoneal injection for six weeks. During the fifth week of injection, rats in the Fe group were further categorized into four groups (n = 8 each) to subcutaneously injected with 1) vehicle (10% DMSO in normal saline), 2) deferoxamine (DFO) (25 mg/kg), 3) Mdivi-1 (1.2 mg/kg), or 4) M1 (2 mg/kg) for further two weeks. Behavioral tests, such as novel object recognition and Morris water maze, were performed post-treatment. Non-heme iron levels in plasma and parameters in the brain, including tight junction-related blood-brain barrier proteins, lipocalin-2, iron levels, ferroptosis, inflammation, mitochondrial function, dynamics, mitophagy, and Alzheimer-like proteins, were assessed. DFO mitigated iron overload condition and brain abnormalities, partially ameliorating cognitive decline. Mdivi-1 and M1 showed superior effects by preventing brain inflammation, LCN2 elevation, and mitochondrial dysfunction, restoring memory function (hippocampal-dependent manner) and spatial cognition (recognition manner). These findings indicate that modulating mitochondrial dynamics via fission inhibitor and fusion promoter could be promising novel pharmacological interventions for the brain in iron overload condition.

The Role of N6-Methyladenosine in Mitochondrial Dysfunction and Pathology

Mitochondria are indispensable in cells and play crucial roles in maintaining cellular homeostasis, energy production, and regulating cell death. Mitochondrial dysfunction has various manifestations, causing different diseases by affecting the diverse functions of mitochondria in the body. Previous studies have mainly focused on mitochondrial-related diseases caused by nuclear gene mutations or mitochondrial gene mutations, or mitochondrial dysfunction resulting from epigenetic regulation, such as DNA and histone modification. In recent years, as a popular research area, m6A has been involved in a variety of important processes under physiological and pathological conditions. However, there are few summaries on how RNA methylation, especially m6A RNA methylation, affects mitochondrial function. Additionally, the role of m6A in pathology through influencing mitochondrial function may provide us with a new perspective on disease treatment. In this review, we summarize several manifestations of mitochondrial dysfunction and compile examples from recent years of how m6A affects mitochondrial function and its role in some diseases.

Unraveling cell death mechanisms in traumatic brain injury: dynamic roles of ferroptosis and necroptosis

Traumatic brain injury (TBI) remains a major cause of mortality and long-term disability worldwide, with ferroptosis and necroptosis emerging as key drivers of secondary neuronal damage. Ferroptosis, characterized by iron-dependent lipid peroxidation and mitochondrial dysfunction, exacerbates oxidative stress and neuronal cell death. In parallel, necroptosis, mediated by receptor-interacting protein kinases (RIPK1 and RIPK3), amplifies inflammation through membrane rupture and the release of cellular components. Mitochondrial dynamics, involving fission and fusion processes, play a dual role in regulating these pathways. While mitochondrial fusion preserves cellular integrity and reduces oxidative stress, excessive mitochondrial fission driven by dynamin-related protein 1 (DRP1) accelerates necroptotic signaling and neuronal injury. This intricate interplay between ferroptosis, necroptosis, and mitochondrial dynamics highlights potential therapeutic targets. Modulating these pathways through tailored interventions could reduce neuronal damage, mitigate neuroinflammation, and improve functional outcomes in TBI patients. Advancing our understanding of these mechanisms is essential for developing precision therapies that address the complex pathology of traumatic brain injury.

Regulating Sirtuin 3-mediated mitochondrial dynamics through vanillic acid improves muscle atrophy in cancer-induced cachexia

Cancer cachexia is a cancer-associated disease characterized by gradual body weight loss due to pathologic muscle and fat loss, but effective treatments are still lacking. Here, we investigate the possible effect of vanillic acid (VA), known for its antioxidant, anti-inflammatory, and anti-obesity effects, on mitochondria-mediated improvement of cancer cachexia. We utilized cachexia-like models using CT26 colon cancer and dexamethasone. VA improved representative parameters of cancer cachexia including body weight loss and increased serum intereukin-6 levels. VA also attenuated muscle loss in the tibialis anterior and gastrocnemius muscles, inhibited proteolytic markers including muscle RING-finger protein-1 (MURF1) and muscle atrophy F-box (MAFbx) and improved mitochondrial function through alteration of sirtuins 3 (SIRT3) and mitofusin 1 (MFN1). Importantly, silencing the SIRT3 gene abolished the effect of VA, indicating that SIRT3 is important in the mechanism of action of VA. Overall, we suggest using VA as a novel therapeutic agent that can fundamentally treat and recover muscle atrophy in cancer cachexia patients.

Mitochondrial Responses to Conventional and Ultra-high Dose Rate (FLASH) Radiation

Purpose

Ultra-high dose rate (>40 Gy/s, FLASH) radiation therapy (RT) provides equivalent tumor control while reducing normal tissue toxicity relative to conventional dose rate (CONV) RT. However, the mechanisms underlying the observed FLASH effect are unknown. We hypothesized that the preservation of mitochondrial integrity in nontumorigenic cells by FLASH RT could be a key factor in reducing normal tissue toxicity and improving overall treatment outcomes.

Methods

We examined mitochondrial health and function after CONV and FLASH in vitro, ex vivo, and in vivo through assays of metabolic flux, mitochondrial membrane potential, mitochondrial reactive oxygen species (ROS), mitochondrial DNA damage and copy number, mitochondrial morphology, and tumor growth and survival.

Results

In in vitro assays, murine pancreatic cancer (PDAC) cells showed evidence of equal mitochondrial damage in response to CONV and FLASH, but nontumorigenic pancreatic cells were spared by FLASH. These results were recapitulated ex vivo, and mice treated with FLASH showed higher response rates and longer survival time than mice treated with CONV in an in vivo tumor model.

Conclusions

Collectively, these results suggest that FLASH spares mitochondrial function in nontumorigenic cells, but not in PDAC cells, relative to CONV. The preservation of mitochondrial integrity in nontumorigenic cells may be a key mechanism underlying the reduced normal tissue toxicity observed with FLASH RT.

Oxidant-Based Cytotoxic Agents During Aging: From Disturbed Energy Metabolism to Chronic Inflammation and Disease Progression

In humans, aging is an inevitable consequence of diminished growth processes after reaching maturity. The high order of biomolecules in cells and tissues is continuously disturbed by numerous physical and chemical destructive impacts. Host-derived oxidant-based cytotoxic agents (reactive species, transition free metal ions, and free heme) contribute considerably to this damage. These agents are under the control of immediately acting antagonizing principles, which are important to ensure cell and tissue homeostasis. In this review, I apply the concept of host-derived cytotoxic agents and their interplay with antagonizing principles to the aging process. During aging, energy metabolism and the supply of tissues with dioxygen and nutrients are increasingly disturbed. In addition, a chronic inflammatory state develops, a condition known as inflammaging. The balance between oxidant-based cytotoxic agents and protective mechanisms is analyzed depending on age-based physiological alterations in ATP production. Disturbances in this balance are associated with the development of age-related diseases and comorbidities. An enhanced production of reactive species from dysfunctional mitochondria, alterations in cellular redox homeostasis, and adaptations to hypoxia are highlighted. Examples of how disturbances between oxidant-based cytotoxic agents and antagonizing principles contribute to the pathogenesis of diseases in persons of advanced age are given.

Marine-Derived Bioactive Compounds: A Promising Strategy for Ameliorating Skeletal Muscle Dysfunction in COPD

Chronic obstructive pulmonary disease (COPD) is frequently accompanied by skeletal muscle dysfunction, a critical and severe extrapulmonary complication. This dysfunction contributes to reduced exercise capacity, increased frequency of acute exacerbations, and elevated mortality, serving as an independent risk factor for poor prognosis in COPD patients. Owing to the unique physicochemical conditions of the marine environment, marine-derived bioactive compounds exhibit potent anti-inflammatory and antioxidant properties, demonstrating therapeutic potential for ameliorating COPD skeletal muscle dysfunction. This review summarizes marine-derived bioactive compounds with promising efficacy against skeletal muscle dysfunction in COPD, including polysaccharides, lipids, polyphenols, peptides, and carotenoids. The discussed compounds have shown bioactivities in promoting skeletal muscle health and suppressing muscle atrophy, thereby providing potential strategies for the prevention and treatment of COPD skeletal muscle dysfunction. These findings may expand the therapeutic strategies for managing COPD skeletal muscle dysfunction.

Interleukin-13-mediated alterations in esophageal epithelial mitochondria contribute to tissue remodeling in eosinophilic esophagitis

Background

The significance of mitochondria in EoE pathobiology remains elusive.

Objective

To determine the impact of EoE inflammatory mediators upon mitochondrial biology in esophageal epithelium, the mechanisms mediating these effects, and their functional significance to EoE pathobiology.

Methods

Mitochondria were evaluated in human biopsies, MC903/Ovalbumin-induced murine EoE, and human esophageal keratinocytes. Esophageal keratinocytes were treated with EoE-relevant cytokines and JAK/STAT inhibitor ruxolitinib. To deplete mitochondria, 3D organoids generated from TFAM loxp/loxp mice were subjected ex vivo to Cre or siRNA against Transcription factor A, mitochondria (TFAM) was transfected into esophageal keratinocytes. Mitochondrial respiration, membrane potential, and superoxide levels were measured.

Results

We find evidence of increased mitochondria in esophageal epithelium of patients with EoE and mice with EoE-like inflammation. In esophageal keratinocytes, IL-4 and IL-13 increase mitochondrial mass. IL-13 increases mitochondrial biogenesis in a JAK/STAT-dependent manner. In 3D organoids, IL-13 limits squamous cell differentiation (SCD), and this is blunted upon TFAM depletion. IL-13 decreases mitochondrial respiration and superoxide level, although mitochondria remain intact. IL-13-mediated suppression of superoxide was abrogated upon TFAM depletion in esophageal keratinocytes.

Conclusions

We report that increased mitochondrial mass is a feature of EoE. Among EoE-relevant cytokines, IL-13 is the primary driver of increased mitochondrial mass in esophageal keratinocytes by promoting mitochondrial biogenesis in a JAK/STAT-dependent manner. IL-13-mediated accumulation of mitochondria impairs SCD in esophageal keratinocytes and also suppresses oxidative stress, a factor that is known to induce SCD. These findings identify a novel mechanism through which IL-13 promotes EoE-associated epithelial remodeling.

Clinical Implication

These findings further lay a foundation for exploration of level of esophageal epithelial mitochondria as a predictive biomarker for response to dupilumab.

Capsule summary

IL-13 promotes mitochondrial biogenesis in esophageal epithelium, contributing to impaired squamous cell differentiation.

Single-organelle visualization tracking natural glycosaminoglycans within mitochondria-lysosome crosstalk for inflammatory homeostasis

Glycosaminoglycans (GAGs), as natural products with diverse biological activities, play a significant role in regulating inflammatory homeostasis. Nevertheless, the mechanism underlying their intracellular anti-inflammatory properties remains unclear. Herein, we propose a single-organelle visualization tracking framework, leveraging an advanced fluorescent imaging technology combined with labeling methods to dynamically trace the subcellular regulatory mechanisms of GAGs in eliminating inflammatory markers, such as reactive oxygen species (ROS). By utilizing conventional fluorescein isothiocyanate (FITC)-labeled GAGs, we successfully achieved in situ single-organelle visualization of the subcellular localization and intracellular activities of GAGs. Our findings revealed that GAGs enter lysosomes and increase their number and activity, with chondroitin sulfate (CS) exhibiting particularly prominent effects. Significantly, we visually depict that CS-loaded lysosomes selectively cleave ROS-enriched terminal mitochondria, driving mitochondrial fission and reprogramming. These results corroborate that CS regulate mitochondria-lysosome crosstalk to control mitochondrial quality, thereby maintaining intracellular inflammatory homeostasis. Collectively, our work presents an evidence on the single-organelle visualization and regulatory mechanism of GAGs, thereby offering novel perspectives and avenues for researching other natural products.

Mitochondrion-Targeted Type I Photodynamic Therapy for Agonist Independent cGAS-STING Activation

CGAS-STING agonists generally lead to hyperimmunity and systemic toxicity, hindering their immunotherapeutic outcomes. Herein, a mitochondrion-targeted nanoagonist (termed HABH) containing boron dipyrromethene (BODIPY)-derived type I photosensitizer (BDP) and Au nanoparticle-engineered hollow mesoporous silica (HMSN/AuNPs) has been fabricated for light-controlled mitochondrial stress-inducing and agonist-independent cGAS-STING pathway activation. The HABH nanoagonist can actively target tumor tissues and release the mitochondrion-targeted BDP. Under light illumination, BDP achieves type I photodynamic therapy (PDT) in mitochondria, generating massive hydroxyl radicals (•OH) and inducing mitochondrial stress in an oxygen-independent manner, promoting the release of mitochondrial DNA (mtDNA). Simultaneously, the HMSN/AuNPs act as dual nanozymes to derive cascade reactions for •OH production, elevating the intracellular oxidative state, and together with the BDP-induced mitochondrial stress, finally evoking the cGAS-STING pathway and facilitating the release of type I interferon. In the orthotopic breast tumor models, the HABH nanoagonist achieved intratumoral and systemic immunoactivation for eradicating primary tumors and preventing metastasis tumors. Therefore, the constructed mitochondrion-targeted nanoagonist enabled light-controlled and agonist-independent cGAS-STING activation, providing a paradigm for photoimmunotherapy.

Vitamin D Alleviates Heavy Metal-Induced Cytotoxic Effects on Human Bone Osteoblasts Via the Induction of Bioenergetic Disruption, Oxidative Stress, and Apoptosis

Cadmium (Cd) and lead (Pb) are heavy metals (HMs) that persistently contaminate the ecosystem, and bioaccumulation in bones is a health concern. We used biochemical and molecular assays to assess the cytoprotective effect of vitamin D (VD) on Cd- and Pd-induced chemical toxicity of human bone osteoblasts in vitro. Exposing Cd and Pb to human osteoblast cultures at concentrations of 0.1-1000 µM for 24-72 h significantly reduced osteoblast viability in an exposure time- and concentration-dependent manner. The cytotoxic effect of Cd on osteoblasts was more severe than Pb's, with 72-h exposure estimated half maximal effective concentration (EC50) of 8 and 12 µM, respectively, and VD (1 and 10 nM) alleviated cytotoxicity. Bioenergetics assays of ATP, mitochondrial membrane potential, and mitochondrial complex I and III activity showed that both Cd and Pb (1 and 10 µM) inhibited cellular bioenergetics after 72-h exposure. Cd and Pb increased lipid peroxidation and reactive oxygen species with reduced catalase/superoxide dismutase antioxidant activities and increased activity of caspases -3, -8, and -9. Co-treatment with VD (1 and 10 nM) counteracted bioenergetic disruption, oxidative damage, and apoptosis in a concentration-dependent manner. These findings suggest that VD is effective in managing the toxic effects of environmental pollutants and in treating bone diseases characterized by oxidative stress, apoptosis, and bioenergetic disruption.

Rescue of mitochondrial dysfunction through alteration of extracellular matrix composition in barth syndrome cardiac fibroblasts

Fibroblast-ECM (dys)regulation is associated with a plethora of diseases. The ECM acts as a reservoir of inflammatory factors and cytokines that mediate molecular mechanisms within cardiac cell populations. The role of ECM-mitochondria crosstalk in the development and progression of cardiac disorders remains uncertain. We evaluated the influence of ECM produced by stromal cells from patients with the mitochondrial cardiomyopathy (Barth syndrome, BTHS) and unaffected healthy controls on cardiac fibroblast (CF) metabolic function. To do this, cell-derived matrices CDMs were generated from BTHS and healthy human pluripotent stem cell-derived CFs (hPSC-CF) and used as cell culture substrates. BTHS CDMs negatively impacted the mitochondrial function of healthy hPSC-CFs while healthy CDMs improved mitochondrial function in BTHS hPSC-CFs. Mass spectrometry comparisons identified 5 matrisome proteins differentially expressed in BTHS compared to healthy CDM. Our results highlight a key role for the ECM in disease through its impact on mitochondrial function.

Human amniotic membrane scaffold enhances adipose mesenchymal stromal cell mitochondrial bioenergetics promoting their regenerative capacities

The human amniotic membrane (hAM) has been applied as a scaffold in tissue engineering to sustain stem cells and enhance their regenerative capacities. We investigated the molecular and biochemical regulations of mesenchymal stromal cells (MSCs) cultured on hAM scaffold in a three-dimensional (3D) setting. Culture of adipose-MSCs (AMSCs) on decellularized hAM showed significant improvement in their viability, proliferative capacity, resistance to apoptosis, and enhanced MSC markers expression. These cultured MSCs displayed altered expression of markers associated with pro-angiogenesis and inflammation and demonstrated increased potential for differentiation into adipogenic and osteogenic lineages. The hAM scaffold modulated cellular respiration by upregulating glycolysis in MSCs as evidenced by increased glucose consumption, cellular pyruvate and lactate production, and upregulation of glycolysis markers. These metabolic changes modulated mitochondrial oxidative phosphorylation (OXPHOS) and altered the production of reactive oxygen species (ROS), expression of OXPHOS markers, and total antioxidant capacity. They also significantly boosted the urea cycle and altered the mitochondrial ultrastructure. Similar findings were observed in bone marrow-derived MSCs (BMSCs). Live cell imaging of BMSCs cultured in the same 3D environment revealed dynamic changes in cellular activity and interactions with its niche. These findings provide evidence for the favorable properties of hAM as a biomimetic scaffold for enhancing the in vitro functionality of MSCs and supporting their potential usefulness in clinical applications.

Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity

Mitochondrial fission and fusion are tightly regulated to specify mitochondrial abundance, localization, and arrangement during cell division as well as in the diverse differentiated cell types and physiological states. However, the regulatory pathways for such mitochondrial dynamics are less explored than the mitochondrial fission and fusion components. Here we report a large-scale screen for genes that regulate mitochondrial fission. Mitochondrial fission defects cause a characteristic uneven fluorescent pattern in embryos carrying mitochondrial stress reporter genes. Using this uneven activation, we performed RNAi screens that identified 3 kinase genes from a ~ 500-kinase library and another 11 genes from 3,300 random genes that function in mitochondrial fission. Many of these identified genes play roles in chromosome segregation. We found that chromosome missegregation and genome instability lead to dysregulation of mitochondrial fission, possibly independent of DRP-1. ATL-1, the C. elegans ATR orthologue, plays a potentially protective role in alleviating the mitochondrial fission defect caused by chromosome missegregation. This establishes a screening paradigm for identifying mitochondrial fission regulators, which reveals the potential role of ATR in surveilling mitochondrial fission to mitigate dysregulation caused by improper chromosome segregation.

Region-specific mitophagy in nucleus pulposus, annulus fibrosus, and cartilage endplate of intervertebral disc degeneration: mechanisms and therapeutic strategies

Intervertebral disc degeneration (IVDD) is a prevalent condition contributing to various spinal disorders, posing a significant global health burden. Mitophagy plays a crucial role in maintaining mitochondrial quantity and quality and is closely associated with the onset and progression of IVDD. Well-documented region-specific mitophagy mechanisms in IVDD are guiding the development of therapeutic strategies. In the nucleus pulposus (NP), impaired mitochondria lead to apoptosis, oxidative stress, senescence, extracellular matrix degradation and synthesis, excessive autophagy, inflammation, mitochondrial instability, and pyroptosis, with key regulatory targets including AMPK, PGC-1α, SIRT1, SIRT3, Progerin, p65, Mfn2, FOXO3, NDUFA4L2, SLC39A7, ITGα5/β1, Nrf2, and NLRP3 inflammasome. In the annulus fibrosus (AF), mitochondrial damage induces apoptosis and oxidative stress mediated by PGC-1α, while in the cartilage endplate (CEP), mitochondrial dysfunction similarly triggers apoptosis and oxidative stress. These mechanistic insights highlight therapeutic strategies such as activating Parkin-dependent and Ub-independent mitophagy pathways for NP, enhancing Parkin-dependent mitophagy for AF, and targeting Parkin-mediated mitophagy for CEP. These strategies include the use of natural ingredients, hormonal modulation, gene editing technologies, targeted compounds, and manipulation of related proteins. This review summarizes the mechanisms of mitophagy in different regions of the intervertebral disc and highlights therapeutic approaches using mitophagy modulators to ameliorate IVDD. It discusses the complex mechanisms of mitophagy and underscores its potential as a therapeutic target. The objective is to provide valuable insights and a scientific basis for the development of mitochondrial-targeted drugs for anti-IVDD.

Association of Mitochondrial DNA Copy Number in Peripheral Blood with Risk and Prognosis in Acute Aortic Syndrome

Previous studies have reported that mitochondrial DNA copy number (mtDNA-CN) of blood was associated with a series of aging-related diseases. However, it remains unknown whether mtDNA-CN can be a potential biomarker of acute aortic syndromes (AASs). The mtDNA-CN in blood of 190 male patients with AAS and 207 healthy controls were detected by standardized real-time quantitative PCR-based assay. The mtDNA sequencing data of blood and myocardial muscle in 134 individuals were used to analyze mtDNA somatic mutations in blood. mtDNA-CN in peripheral blood was negatively correlated with age of individuals. Further analysis based on next-generation sequencing data demonstrated numbers and heteroplasmy of mtDNA mutations were positively correlated with age. Remarkably, mtDNA-CN of patients with AAS was lower than that of healthy controls. Logistic regression also showed that mtDNA-CN was independently associated with risk of AAS. During follow-up, patients with the lowest mtDNA-CN quartile had a hazard ratio of 2.543 for all-cause-mortality and 1.964 for composite end points compared with the other patients. Moreover, multivariate Cox regression indicated that lowest mtDNA-CN quartile was independently associated with all-cause mortality in patients with AAS. Our study demonstrated a negative correlation between mtDNA-CN and age. Moreover, lower mtDNA-CN in peripheral blood was significantly associated with higher risk and worse prognosis of AAS. It provided crucial evidence supporting the potential of mtDNA-CN as a novel biomarker of AAS.

Fam163a knockdown and mitochondrial stress in the arcuate nucleus of hypothalamus reduce AgRP neuron activity and differentially regulate mitochondrial dynamics in mice

AIM

Mitochondria play key roles in neuronal activity, particularly in modulating agouti-related protein (AgRP) and proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARC), which regulates food intake. FAM163A, a newly identified protein, is suggested to be part of the mitochondrial proteome, though its functions remain largely unknown. This study aimed to investigate the effects of Fam163a knockdown and mitochondrial dysfunction on food intake, AgRP neuron activity, and mitochondrial function in the hypothalamus.

METHODS

Male C57BL/6 and AgRP-Cre mice received intracranial injections of either Fam163a shRNA, rotenone, or appropriate controls. Behavioral assessments included food intake, locomotor activity, and anxiety-like behaviors. qRT-PCR was used to quantify the expression of the genes related to food intake, mitochondrial biogenesis, dynamics, and oxidative stress. Blood glucose, serum insulin, and leptin levels were measured. Electrophysiological patch-clamp recordings were used to assess the AgRP neuronal activity.

RESULTS

Fam163a knockdown in the ARC increased the cumulative food intake in short term (first 7 days) without altering the 25-day food intake and significantly increased the Pomc mRNA expression. Fam163a silencing significantly reduced leptin levels. Both Fam163a knockdown and rotenone significantly reduced the firing frequency of AgRP neurons. Neither Fam163a silencing nor rotenone altered locomotor or anxiety-like behaviors. Fam163a knockdown and rotenone differentially altered the expression of mitochondrial biogenesis-, mitophagy-, fusion-, and oxidative stress-related genes.

CONCLUSION

Hypothalamic FAM163A may play a role in modulating AgRP neuronal activity through regulating mitochondrial biogenesis, dynamics, and redox state. These findings provide insights into the role of FAM163A and mitochondrial stress in the central regulation of metabolism.

Mitochondrial dynamics: Molecular mechanism and implications in endometriosis

Endometriosis affects about 10 % of women of reproductive age, leading to a disabling gynecologic condition. Chronic pain, inflammation, and oxidative stress have been identified as the molecular pathways involved in the progression of this disease, although its precise etiology remains uncertain. Although mitochondria are considered crucial organelles for cellular activity, their dysfunction has been linked to the development of this disease. The purpose of this review is to examine the functioning of the mitochondrion in endometriosis: in particular, we focused on the mitochondrial dynamics of biogenesis, fusion, and fission. Since excessive mitochondrial activity is reported to affect cell proliferation, we also considered mitophagy as a mechanism involved in limiting disease development. To better understand mitochondrial activity, we also considered alterations in circadian rhythms, the gut microbiome, and estrogen receptors: indeed, these mechanisms are also involved in the development of endometriosis. In addition, we focused on recent research about the impact of numerous substances on mitochondrial activity; some of them may offer a future breakthrough in endometriosis treatment by acting on mitochondria and inhibiting cell proliferation.

Mitochondrial fission produces a Warburg effect via the oxidative inhibition of prolyl hydroxylase domain-2

Excessive mitochondrial fission and a shift to a Warburg phenotype are hallmarks of pulmonary hypertension (PH), although the mechanistic link between these processes remains unclear. We show that in pulmonary arterial endothelial cells (PAEC), Drp1 overexpression induces mitochondrial fission and increases glycolytic ATP production and glycolysis. This is due to mitochondrial reactive oxygen species (mito-ROS)-mediated activation of hypoxia-inducible factor-1α (HIF-1α) signaling, and this is linked to hydrogen peroxide (H2O2)-mediated inhibition of prolyl hydroxylase domain-2 (PHD2) due to its cysteine 326 oxidation and dimerization. Furthermore, these findings are validated in PAEC isolated from a lamb model of PH, which are glycolytic (Shunt PAEC), exhibit increases in both H2O2 and PHD2 dimer levels. The overexpression of catalase reversed the PHD2 dimerization, decreased HIF-1α levels, and attenuated glycolysis in Shunt PAEC. Our data suggest that reducing PHD2 dimerization could be a potential therapeutic target for PH.

Young bone marrow transplantation delays bone aging in old mice

Recent discoveries have shown that systemic manipulations, such as parabiosis, blood exchange, and young plasma transfer, can counteract many hallmarks of aging. This rejuvenation effect has been attributed to circulatory factors produced by cells from both hematopoietic and non-hematopoietic lineages. However, the specific involvement of bone marrow (BM) or hematopoietic cells in producing such factors and their effects on aging is still unclear. We developed a model of aged mice with transplanted young or old BM cells and assessed the impact on the aging process, specifically on energy metabolism and bone remodeling parameters. The donor BM cell engraftment in the aged mice was confirmed by flow cytometry using a transplanted cell-specific marker (green fluorescent protein). Energy metabolism was assessed using Oxymax indirect calorimetry system after 3 months of transplantation. Tibiae and L3-L4 vertebrae were analyzed using micro-CT, a three-point bending test and bone histomorphometry. Moreover, bone marrow proteome was assessed using proteomics, and blood serum/plasma was collected and analyzed using the Luminex assay. Our results showed that while the effect on energy metabolism was insignificant, rejuvenating the BM through young bone marrow transplantation reversed age-associated low bone mass traits in old mice. Specifically, young bone marrow transplantation improved bone trabecular microarchitecture both in tibiae and vertebrae of old mice and increased the number of osteoblasts and osteoclasts compared to old bone marrow transplantation. In conclusion, young bone marrow cells may represent a future therapeutic strategy for age-related diseases such as osteoporosis. The findings of this study provide important insights into our understanding of aging.