Mitochondrial fusion, fission, and mitochondrial toxicity

Identification of SLC25A46 interaction interfaces with mitochondrial membrane fusogens Opa1 and Mfn2

Mitochondrial fusion requires the sequential merger of four bilayers to two. The outer-membrane solute carrier family 25 member (SLC25A46) interacts with both the outer and inner membrane dynamin family GTPases mitofusin 1/2 and optic atrophy 1 (Opa1). While SLC25A46 levels are known to affect mitochondrial morphology, how SLC25A46 interacts with mitofusin 1/2 and Opa1 to regulate membrane fusion is not understood. In this study, we use crosslinking mass spectrometry and AlphaFold 2 modeling to identify interfaces mediating an SLC25A46 interaction with Opa1 and Mfn2. We reveal that the bundle signaling element of Opa1 interacts with SLC25A46, and present evidence of an Mfn2 interaction involving the SLC25A46 cytosolic face. We validate these newly identified interaction interfaces and show that they play a role in mitochondrial network maintenance.

GRP78 mediates mitochondrial fusion and fission in cigarette smoke-induced inflammatory responses in airway epithelial cells

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is characterized by persistent airway inflammation, with cigarette smoke being a major contributor to epithelial injury. Recent studies have shown that abnormal mitochondrial function is closely linked to the onset and progression of airway inflammation. This study aims to explore the role and underlying molecular mechanisms of mitochondrial dynamics in cigarette smoke-induced airway inflammation.

MATERIALS AND METHODS

Human bronchial epithelial (HBE) cells were exposed to cigarette smoke extract (CSE) to assess the expression of mitochondrial fusion markers MFN2 and OPA1, the fission marker DRP1, and the glucose-regulated protein GRP78. The siRNA and pharmaceutics targeting DRP1, MFN2, and GRP78 were employed. Both cells and supernatants were analyzed for inflammatory factor levels and the related signaling pathways.

RESULTS

In this study, HBE cells exposed to CSE showed a significant decrease in the proteins MFN2 and OPA1 and an increase in DRP1. The inhibition of DRP1 expression mitigated inflammation while silencing MFN2 exacerbated it. This was similarly corroborated by the use of the DRP1 inhibitor mdivi-1 and the MFN2 activator leflunomide. Additionally, we proved that GRP78 played an important regulatory role as an essential endoplasmic reticulum protein, regulating the mitochondrial fusion/fission process and subsequently activating the NF-κB pathway to regulate airway inflammation.

DISCUSSION AND CONCLUSION

Taken together, these results suggested that the GRP78-mediated mitochondrial fusion and fission process played a vital role in cigarette smoke-induced airway inflammation and might be a potential therapeutic target in this regard.

FGF23 and Cell Stress in SaOS-2 Cells-A Model Reflecting X-Linked Hypophosphatemia Dynamics

Our study investigates the impact of FGF23 overexpression on SaOS-2 cells to elucidate its role in cellular stress and morphology, contributing to the understanding of skeletal pathologies like X-linked hypophosphatemia (XLH). Using transmission electron microscopy and protein analysis (Western blot), we analyzed the rough endoplasmic reticulum (rER) and mitochondria in SaOS-2 cells with FGF23 overexpression compared to controls. We found significant morphological changes, including enlarged and elongated rER and mitochondria, with increased contact zones, suggesting enhanced interaction and adaptation to elevated protein synthesis and secretion demands. Additionally, we observed higher apoptosis rates of the cells after 24-72 h in vitro and upregulated proteins associated with ER stress and apoptosis, such as CHOP, XBP1 (spliced and unspliced), GRP94, eIF2α, and BAX. These findings indicate a robust activation of the unfolded protein response (UPR) and apoptotic pathways due to FGF23 overexpression. Our results highlight the critical role of ER and mitochondrial interactions in cellular stress responses and provide new insights into the mechanistic link between FGF23 signaling and cellular homeostasis. In conclusion, our study underscores the importance of analyzing UPR-related pathways in the development of therapeutic strategies for skeletal and systemic diseases and contributes to a broader understanding of diseases like XLH.

Relationship between ferroptosis and mitophagy in acute lung injury: a mini-review

Acute lung injury (ALI) is one of the most deadly and prevalent diseases in the intensive care unit. Ferroptosis and mitophagy are pathological mechanisms of ALI. Ferroptosis aggravates ALI, whereas mitophagy regulates ALI. Ferroptosis and mitophagy are both closely related to reactive oxygen species (ROS). Mitophagy can regulate ferroptosis, but the specific relationship between ferroptosis and mitophagy is still unclear. This study summarizes previous research findings on ferroptosis and mitophagy, revealing their involvement in ALI. Examining the functions of mTOR and NLPR3 helps clarify the connection between ferroptosis and mitophagy in ALI, with the goal of establishing a theoretical foundation for potential therapeutic approaches in the future management of ALI.

Neurodegenerative disorders, metabolic icebergs, and mitohormesis

Neurodegenerative disorders are typically "split" based on their hallmark clinical, anatomical, and pathological features, but they can also be "lumped" by a shared feature of impaired mitochondrial biology. This leads us to present a scientific framework that conceptualizes Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD) as "metabolic icebergs" comprised of a tip, a bulk, and a base. The visible tip conveys the hallmark neurological symptoms, neurodegenerative regions, and neuronal protein aggregates for each disorder. The hidden bulk depicts impaired mitochondrial biology throughout the body, which is multifaceted and may be subdivided into impaired cellular metabolism, cell-specific mitotypes, and mitochondrial behaviours, functions, activities, and features. The underlying base encompasses environmental factors, especially modern industrial toxins, dietary lifestyles, and cognitive, physical, and psychosocial behaviours, but also accommodates genetic factors specific to familial forms of AD, PD, and ALS, as well as HD. Over years or decades, chronic exposure to a particular suite of environmental and genetic factors at the base elicits a trajectory of impaired mitochondrial biology that maximally impacts particular subsets of mitotypes in the bulk, which eventually surfaces as the hallmark features of a particular neurodegenerative disorder at the tip. We propose that impaired mitochondrial biology can be repaired and recalibrated by activating "mitohormesis", which is optimally achieved using strategies that facilitate a balanced oscillation between mitochondrial stressor and recovery phases. Sustainably harnessing mitohormesis may constitute a potent preventative and therapeutic measure for people at risk of, or suffering with, neurodegenerative disorders.

The bioenergetics of traumatic brain injury and its long-term impact for brain plasticity and function

Mitochondria provide the energy to keep cells alive and functioning and they have the capacity to influence highly complex molecular events. Mitochondria are essential to maintain cellular energy homeostasis that determines the course of neurological disorders, including traumatic brain injury (TBI). Various aspects of mitochondria metabolism such as autophagy can have long-term consequences for brain function and plasticity. In turn, mitochondria bioenergetics can impinge on molecular events associated with epigenetic modifications of DNA, which can extend cellular memory for a long time. Mitochondrial dysfunction leads to pathological manifestations such as oxidative stress, inflammation, and calcium imbalance that threaten brain plasticity and function. Hence, targeting mitochondrial function may have great potential to lessen the outcomes of TBI.

MCU inhibition protects against intestinal ischemia‒reperfusion by inhibiting Drp1-dependent mitochondrial fission

Intestinal ischemia‒reperfusion (IIR) injury is a common complication of surgery, but clear molecular insights and valuable therapeutic targets are lacking. Mitochondrial calcium overload is an early sign of various diseases and is considered a vital factor in ischemia‒reperfusion injury. The mitochondrial calcium uniporter (MCU), which is located on the inner mitochondrial membrane, is the primary mediator of calcium ion entry into the mitochondria. However, the specific mechanism of MCU in IIR injury remains to be clarified. In this study, we generated an IIR model using C57BL/6 mice and Caco-2 cells and found increases in the calcium levels and MCU expression following IIR injury. The specific inhibition of MCU markedly attenuated IIR injury. Moreover, MCU knockdown alleviates mitochondrial dysfunction by reducing oxidative stress and apoptosis. Mechanistically, MCU knockdown substantially reduced the translocation of Drp1 and thus its binding to Fis1 receptors, resulting in decreased mitochondrial fission. Taken together, our findings demonstrated that MCU is a novel upstream regulator of Drp1 in ischemia‒reperfusion and represents a predictive and therapeutic target for IIR.

The Mitochondrial Distribution and Morphology Family 33 Gene FgMDM33 Is Involved in Autophagy and Pathogenesis in Fusarium graminearum

The mitochondrial distribution and morphology family 33 gene (MDM33) regulates mitochondrial homeostasis by mediating the mitochondrial fission process in yeast. The wheat head blight Fusarium graminearum contains an FgMdm33 protein that is orthologous to Saccharomyces cerevisiae Mdm33, albeit its function remains unknown. We have reported here the roles of FgMdm33 in regulating fungal morphogenesis, mitochondrial morphology, autophagy, apoptosis, and fungal pathogenicity. The ΔFgmdm33 mutants generated through a homologous recombination strategy in this study exhibited defects in terms of mycelial growth, conidia production, and virulence. Hyphal cells lacking FgMDM33 displayed elongated mitochondria and a dispensable respiratory-deficient growth phenotype, indicating the possible involvement of FgMDM33 in mitochondrial fission. The ΔFgmdm33 mutants displayed a remarkable reduction in the proteolysis of GFP-FgAtg8, whereas the formation of autophagic bodies in the hyphal cells of mutants was recorded under the induction of mitophagy. In addition, the transcriptional expression of the apoptosis-inducing factor 1 gene (FgAIF1) was significantly upregulated in the ΔFgmdm33 mutants. Cumulatively, these results indicate that FgMDM33 is involved in mitochondrial fission, non-selective macroautophagy, and apoptosis and that it regulates fungal growth, conidiation, and pathogenicity of the head blight pathogen.

The mechanism of extracellular CypB promotes glioblastoma adaptation to glutamine deprivation microenvironment

Glioblastoma, previously known as glioblastoma multiform (GBM), is a type of glioma with a high degree of malignancy and rapid growth rate. It is highly dependent on glutamine (Gln) metabolism during proliferation and lags in neoangiogenesis, leading to extensive Gln depletion in the core region of GBM. Gln-derived glutamate is used to synthesize the antioxidant Glutathione (GSH). We demonstrated that GSH levels are also reduced in Gln deficiency, leading to increased reactive oxygen species (ROS) levels. The ROS production induces endoplasmic reticulum (ER) stress, and the proteins in the ER are secreted into the extracellular medium. We collected GBM cell supernatants cultured with or without Gln medium; the core and peripheral regions of human GBM tumor tissues. Proteomic analysis was used to screen out the target-secreted protein CypB. We demonstrated that the extracellular CypB expression is associated with Gln deprivation. Then, we verified that GBM can promote the glycolytic pathway by activating HIF-1α to upregulate the expression of GLUT1 and LDHA. Meanwhile, the DRP1 was activated, increasing mitochondrial fission, thus inhibiting mitochondrial function. To explore the specific mechanism of its regulation, we constructed a si-CD147 knockout model and added human recombinant CypB protein to verify that extracellular CypB influenced the expression of downstream p-AKT through its cell membrane receptor CD147 binding. Moreover, we confirmed that p-AKT could upregulate HIF-1α and DRP1. Finally, we observed that extracellular CypB can bind to the CD147 receptor, activate p-AKT, upregulate HIF-1α and DRP1 in order to promote glycolysis while inhibiting mitochondrial function to adapt to the Gln-deprived microenvironment.

Differentiation of cellular responses to particulate and soluble constituents in sunscreen products

Despite the growing awareness of potential human and environmental risks associated with sunscreens, identifying the specific constituents responsible for their potential toxicity is challenging. In this study, we applied three different types of sunscreens with contrasting compositions and compared the effects of their particulate and soluble fractions based on 15 cellular biomarkers of HaCaT cells. Multilinear regression analysis revealed that the internalized soluble fractions played a primary role in the overall cytotoxicity of sunscreen mixtures, which was primarily attributed to their biotransformation, generating metabolites with higher toxicity. The presence of plastic microspheres in sunscreens either inhibited the internalization of soluble fractions or led to their redistribution toward lysosomes. Conversely, subcellular toxicity resulting from the sunscreen mixture was predominantly influenced by particulates. Bio-transformable particulates such as ZnO dissolved in the organelles and induced higher subcellular toxicity compared to bioinert particulates such as microplastics. Subcellular biomarkers including lysosomal count, lysosomal size, mitochondrial count and mitochondrial shape emerged as the potential predictors of sunscreen presence. Our study provides important understanding of sunscreen toxicity by elucidating the differential impacts of particulate and soluble fractions in mixture contaminants.

Association of copy number variation in X chromosome-linked PNPLA4 with heterotaxy and congenital heart disease

BACKGROUND

Heterotaxy (HTX) is a thoracoabdominal organ anomaly syndrome and commonly accompanied by congenital heart disease (CHD). The aim of this study was to analyze rare copy number variations (CNVs) in a HTX/CHD cohort and to examine the potential mechanisms contributing to HTX/CHD.

METHODS

Chromosome microarray analysis was used to identify rare CNVs in a cohort of 120 unrelated HTX/CHD patients, and available samples from parents were used to confirm the inheritance pattern. Potential candidate genes in CNVs region were prioritized via the DECIPHER database, and PNPLA4 was identified as the leading candidate gene. To validate, we generated PNPLA4 -overexpressing human induced pluripotent stem cell lines as well as pnpla4 -overexpressing zebrafish model, followed by a series of transcriptomic, biochemical and cellular analyses.

RESULTS

Seventeen rare CNVs were identified in 15 of the 120 HTX/CHD patients (12.5%). Xp22.31 duplication was one of the inherited CNVs identified in this HTX/CHD cohort, and PNPLA4 in the Xp22.31 was a candidate gene associated with HTX/CHD. PNPLA4 is expressed in the lateral plate mesoderm, which is known to be critical for left/right embryonic patterning as well as cardiomyocyte differentiation, and in the neural crest cell lineage. Through a series of in vivo and in vitro analyses at the molecular and cellular levels, we revealed that the biological function of PNPLA4 is importantly involved in the primary cilia formation and function via its regulation of energy metabolism and mitochondria-mediated ATP production.

CONCLUSIONS

Our findings demonstrated a significant association between CNVs and HTX/CHD. Our data strongly suggested that an increased genetic dose of PNPLA4 due to Xp22.31 duplication is a disease-causing risk factor for HTX/CHD.

The Emerging Role of the Mitochondrial Respiratory Chain in Skeletal Aging

Maintenance of mitochondrial homeostasis is crucial for ensuring healthy mitochondria and normal cellular function. This process is primarily responsible for regulating processes that include mitochondrial OXPHOS, which generates ATP, as well as mitochondrial oxidative stress, apoptosis, calcium homeostasis, and mitophagy. Bone mesenchymal stem cells express factors that aid in bone formation and vascular growth. Positive regulation of hematopoietic stem cells in the bone marrow affects the differentiation of osteoclasts. Furthermore, the metabolic regulation of cells that play fundamental roles in various regions of the bone, as well as interactions within the bone microenvironment, actively participates in regulating bone integrity and aging. The maintenance of cellular homeostasis is dependent on the regulation of intracellular organelles, thus understanding the impact of mitochondrial functional changes on overall bone metabolism is crucially important. Recent studies have revealed that mitochondrial homeostasis can lead to morphological and functional abnormalities in senescent cells, particularly in the context of bone diseases. Mitochondrial dysfunction in skeletal diseases results in abnormal metabolism of bone-associated cells and a secondary dysregulated microenvironment within bone tissue. This imbalance in the oxidative system and immune disruption in the bone microenvironment ultimately leads to bone dysplasia. In this review, we examine the latest developments in mitochondrial respiratory chain regulation and its impacts on maintenance of bone health. Specifically, we explored whether enhancing mitochondrial function can reduce the occurrence of bone cell deterioration and improve bone metabolism. These findings offer prospects for developing bone remodeling biology strategies to treat age-related degenerative diseases.

Mitochondrial function and gastrointestinal diseases

Mitochondria are dynamic organelles that function in cellular energy metabolism, intracellular and extracellular signalling, cellular fate and stress responses. Mitochondria of the intestinal epithelium, the cellular interface between self and enteric microbiota, have emerged as crucial in intestinal health. Mitochondrial dysfunction occurs in gastrointestinal diseases, including inflammatory bowel diseases and colorectal cancer. In this Review, we provide an overview of the current understanding of intestinal epithelial cell mitochondrial metabolism, function and signalling to affect tissue homeostasis, including gut microbiota composition. We also discuss mitochondrial-targeted therapeutics for inflammatory bowel diseases and colorectal cancer and the evolving concept of mitochondrial impairment as a consequence versus initiator of the disease.

The role of glucagon-like peptide-1/GLP-1R and autophagy in diabetic cardiovascular disease

Diabetes leads to a significantly accelerated incidence of various related macrovascular complications, including peripheral vascular disease and cardiovascular disease (the most common cause of mortality in diabetes), as well as microvascular complications such as kidney disease and retinopathy. Endothelial dysfunction is the main pathogenic event of diabetes-related vascular disease at the earliest stage of vascular injury. Understanding the molecular processes involved in the development of diabetes and its debilitating vascular complications might bring up more effective and specific clinical therapies. Long-acting glucagon-like peptide (GLP)-1 analogs are currently available in treating diabetes with widely established safety and extensively evaluated efficacy. In recent years, autophagy, as a critical lysosome-dependent self-degradative process to maintain homeostasis, has been shown to be involved in the vascular endothelium damage in diabetes. In this review, the GLP-1/GLP-1R system implicated in diabetic endothelial dysfunction and related autophagy mechanism underlying the pathogenesis of diabetic vascular complications are briefly presented. This review also highlights a possible crosstalk between autophagy and the GLP-1/GLP-1R axis in the treatment of diabetic angiopathy.

Identification of SLC25A46 interaction interfaces with mitochondrial membrane fusogens Opa1 and Mfn2

Mitochondrial fusion requires the sequential merger of four bilayers to two. The outer-membrane solute carrier protein SLC25A46 interacts with both the outer and inner-membrane dynamin family GTPases Mfn1/2 and Opa1. While SLC25A46 levels are known to affect mitochondrial morphology, how SLC25A46 interacts with Mfn1/2 and Opa1 to regulate membrane fusion is not understood. In this study, we use crosslinking mass-spectrometry and AlphaFold 2 modeling to identify interfaces mediating a SLC25A46 interactions with Opa1 and Mfn2. We reveal that the bundle signaling element of Opa1 interacts with SLC25A46, and present evidence of a Mfn2 interaction involving the SLC25A46 cytosolic face. We validate these newly identified interaction interfaces and show that they play a role in mitochondrial network maintenance.

Pim-1 kinase protects the liver from ischemia reperfusion injury by regulating dynamics-related protein 1

Hepatic ischemia-reperfusion (IR) injury significantly impacts liver transplantation success, yet current treatments remain inadequate. This study explores the role of Proto-oncogene serine/threonine-protein kinase (Pim-1) in liver IR, an area previously unexplored. Utilizing a mouse liver IR in vivo model and a MIHA cell hypoxia-reoxygenation in vitro model, we observed that Pim-1 expression increases following IR, inversely correlating with serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Increased Pim-1 expression stabilizes mitochondrial membranes by modifying Drp1 phosphorylation, reducing mitochondrial fission and apoptosis, thereby mitigating liver damage. Additionally, we discovered that elevated Pim-1 expression is dependent on the trimethylation of histone H3 lysine 9 during liver IR. These findings underscore the importance and potential clinical application of targeting Pim-1 in treating hepatic IR, presenting a novel therapeutic avenue.

METTL3-mediated NDUFB5 m6A modification promotes cell migration and mitochondrial respiration to promote the wound healing of diabetic foot ulcer

BACKGROUND

Diabetic foot ulcer (DFU) is the most devastating complication of diabetes mellitus (DM) and plays a major role in disability and death in DM patients. NADH: ubiquinone oxidoreductase subunit B5 (NDUFB5) plays an important role in maintaining mitochondrial respiration, but whether it is involved in regulating the progression of advanced glycation end products (AGEs)-mediated DFU is still unclear.

METHODS

Firstly, the role of AGEs on cell viability, migration, and mitochondrial respiration in human umbilical vein endothelial cells (HUVECs) was explored in vitro. Next, NDUFB5 expression was detected in human samples and AGEs-treated HUVECs, and NDUFB5's effect on AGEs-induced HUVECs injury and skin wound in diabetic mice was further clarified. In addition, the role of m6A modification mediated by methyltransferase-like 3 (METTL3) in regulating NDUFB5 expression and AGEs-induced HUVECs injury was investigated.

RESULTS

NDUFB5 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs, whereas mitochondrial fusion promoter M1 facilitated cell viability, migration, and mitochondrial oxiadative respiration in NDUFB5 knockdown HUVECs. Meanwhile, NDUFB5 promotes skin wound healing in diabetic mice. Besides, METTL3-mediated m6A modification and insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) enhanced NDUFB5 expression in HUVECs. Furthermore, METTL3 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs by increasing NDUFB5.

CONCLUSION

METTL3-mediated NDUFB5 m6A modification inhibits AGEs-induced cell injury in HUVECs. METTL3 and NDUFB5 might serve as potential targets for DFU therapy in the future.

KLF13 Attenuates Lipopolysaccharide-Induced Alveolar Epithelial Cell Damage by Regulating Mitochondrial Quality Control via Binding PGC-1α

Sepsis is a clinically life-threatening syndrome, and acute lung injury is the earliest and most serious complication. We aimed to assess the role of kruppel-like factor 13 (KLF13) in lipopolysaccharide (LPS)-induced human alveolar type II epithelial cell damage and to reveal the possible mechanism related to peroxisome proliferator-activated receptor-γ co-activator 1-α (PGC-1α). In LPS-treated A549 cells with or without KLF13 overexpression or PGC-1α knockdown, cell viability was measured by a cell counting kit-8 assay. Enzyme-linked immunosorbent assay kits detected the levels of inflammatory factors, and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining measured cell apoptosis. Besides, mitochondrial reactive oxygen species (MitoSOX) and mitochondrial membrane potential were detected using MitoSOX red- and JC-1 staining. Expression of proteins related to mitochondrial quality control (MQC) was evaluated by western blot. Co-immunoprecipitation (Co-IP) assay was used to analyze the interaction between KLF13 and PGC-1α. Results indicated that KLF13 was highly expressed in LPS-treated A549 cells. KLF13 upregulation elevated the viability and reduced the levels of inflammatory factors in A549 cells exposed to LPS. Moreover, KLF13 gain-of-function inhibited LPS-induced apoptosis of A549 cells, accompanied by upregulated BCL2 expression and downregulated Bax and cleaved caspase3 expression. Furthermore, MQC was improved by KLF13 overexpression, as evidenced by decreased MitoSOX, JC-1 monomers and increased JC-1 aggregates, coupled with the changes of proteins related to MQC. In addition, Co-IP assay confirmed the interaction between KLF13 and PGC-1α. PGC-1α deficiency restored the impacts of KLF13 upregulation on the inflammation, apoptosis, and MQC in LPS-treated A549 cells. In conclusion, KLF13 attenuated LPS-induced alveolar epithelial cell inflammation and apoptosis by regulating MQC via binding PGC-1α.

Research progress on the protective effect of hormones and hormone drugs in myocardial ischemia-reperfusion injury

Ischemic heart disease (IHD) is a condition where the heart muscle does not receive enough blood flow, leading to cardiac dysfunction. Restoring blood flow to the coronary artery is an effective clinical therapy for myocardial ischemia. This strategy helps lower the size of the myocardial infarction and improves the prognosis of patients. Nevertheless, if the disrupted blood flow to the heart muscle is restored within a specific timeframe, it leads to more severe harm to the previously deprived heart tissue. This condition is referred to as myocardial ischemia/reperfusion injury (MIRI). Until now, there is a dearth of efficacious strategies to prevent and manage MIRI. Hormones are specialized substances that are produced directly into the circulation by endocrine organs or tissues in humans and animals, and they have particular effects on the body. Hormonal medications utilize human or animal hormones as their active components, encompassing sex hormones, adrenaline medications, thyroid hormone medications, and others. While several studies have examined the preventive properties of different endocrine hormones, such as estrogen and hormone analogs, on myocardial injury caused by ischemia-reperfusion, there are other hormone analogs whose mechanisms of action remain unexplained and whose safety cannot be assured. The current study is on hormones and hormone medications, elucidating the mechanism of hormone pharmaceuticals and emphasizing the cardioprotective effects of different endocrine hormones. It aims to provide guidance for the therapeutic use of drugs and offer direction for the examination of MIRI in clinical therapy.

Protective Effect of Nicotinamide Riboside on Glucocorticoid-Induced Glaucoma: Mitigating Mitochondrial Damage and Extracellular Matrix Deposition

Purpose

Glucocorticoid-induced glaucoma (GIG) is a prevalent complication associated with glucocorticoids (GCs), resulting in irreversible blindness. GIG is characterized by the abnormal deposition of extracellular matrix (ECM) in the trabecular meshwork (TM), elevation of intraocular pressure (IOP), and loss of retinal ganglion cells (RGCs). The objective of this study is to investigate the effects of nicotinamide riboside (NR) on TM in GIG.

Methods

Primary human TM cells (pHTMs) and C57BL/6J mice responsive to GCs were utilized to establish in vitro and in vivo GIG models, respectively. The study assessed the expression of ECM-related proteins in TM and the functions of pHTMs to reflect the effects of NR. Mitochondrial morphology and function were also examined in the GIG cell model. GIG progression was monitored through IOP, RGCs, and mitochondrial morphology. Intracellular nicotinamide adenine dinucleotide (NAD+) levels of pHTMs were enzymatically assayed.

Results

NR significantly prevented the expression of ECM-related proteins and alleviated dysfunction in pHTMs after dexamethasone treatment. Importantly, NR protected damaged ATP synthesis, preventing overexpression of mitochondrial reactive oxygen species (ROS), and also protect against decreased mitochondrial membrane potential induced by GCs in vitro. In the GIG mouse model, NR partially prevented the elevation of IOP and the loss of RGCs. Furthermore, NR effectively suppressed the excessive expression of ECM-associated proteins and mitigated mitochondrial damage in vivo.

Conclusions

Based on the results, NR effectively enhances intracellular levels of NAD+, thereby mitigating abnormal ECM deposition and TM dysfunction in GIG by attenuating mitochondrial damage induced by GCs. Thus, NR has promising potential as a therapeutic candidate for GIG treatment.

Si-Wu-Tang attenuates hepatocyte PANoptosis and M1 polarization of macrophages in non-alcoholic fatty liver disease by influencing the intercellular transfer of mtDNA

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) represents a burgeoning challenge for public health with potential progression to malignant liver diseases. PANoptosis, an avant-garde conceptualization of cell deaths, is closely associated with mitochondrial damage and linked to multiple liver disorders. Si-Wu-Tang (SWT), a traditional Chinese herbal prescription renowned for regulating blood-related disorders and ameliorating gynecological and hepatic diseases, has been demonstrated to alleviate liver fibrosis by regulating bile acid metabolism and immune responses.

AIM OF THE STUDY

However, the mechanisms by which mtDNA is released from PANoptotic hepatocytes, triggering macrophage activation and hepatitis and whether this process can be reversed by SWT remain unclear.

MATERIALS AND METHODS

Here, sophisticated RNA-sequencing complemented by molecular approaches were applied to explore the underlying mechanism of SWT against NAFLD in methionine/choline-deficient diet (MCD)-induced mice and relative in vitro models.

RESULTS

We revealed that SWT profoundly repaired mitochondrial dysfunction, blocked mitochondrial permeability transition and mtDNA released to the cytoplasm, subsequently reversing hepatocyte PANoptosis and macrophage polarization both in MCD-stimulated mice and in vitro. Mechanically, loaded lipids dramatically promoted the opening of mPTP and oligomerization of VDAC2 to orchestrate mtDNA release, which was combined with ZBP1 to promote hepatocyte PANoptosis and also taken by macrophages to trigger M1 polarization via the FSTL1 and PKM2 combination. SWT effectively blocked NOXA signaling and reversed all these detrimental outcomes.

CONCLUSION

Our findings show that SWT protects against hepatitis-mediated hepatocyte PANoptosis and macrophage M1 polarization by influencing intrahepatic synthesis, release and intercellular transfer of mtDNA, suggesting a potential therapeutic strategy for ameliorating NAFLD.

Cortistatin protects against septic cardiomyopathy by inhibiting cardiomyocyte pyroptosis through the SSTR2-AMPK-NLRP3 pathway

BACKGROUND

Although the pathophysiological mechanism of septic cardiomyopathy has been continuously discovered, it is still a lack of effective treatment method. Cortistatin (CST), a neuroendocrine polypeptide of the somatostatin family, has emerged as a novel cardiovascular-protective peptide, but the specific mechanism has not been elucidated.

PURPOSE

The aim of our study is to explore the role of CST in cardiomyocytes pyroptosis and myocardial injury in sepsis and whether CST inhibits cardiomyocytes pyroptosis through specific binding with somastatin receptor 2 (SSTR2) and activating AMPK/Drp1 signaling pathway.

METHODS AND RESULTS

In this study, plasma CST levels were significantly high and were negatively correlated with N-terminal pro-B type natriuretic peptide (NT-proBNP), a biomarker for cardiac dysfunction, in patients with sepsis. Exogenous administration of CST significantly improved survival rate and cardiac function in mouse models of sepsis by inhibiting the activation of the NLRP3 inflammasome and pyroptosis of cardiomyocytes (decreased cleavage of caspase-1, IL-1β and gasdermin D). Pharmacological inhibition and genetic ablation revealed that CST exerted anti-pyroptosis effects by specifically binding to somatostatin receptor subtype 2 (SSTR2), thus activating AMPK and inactivating Drp1 to inhibit mitochondrial fission in cardiomyocytes.

CONCLUSIONS

This study is the first to report that CST attenuates septic cardiomyopathy by inhibiting cardiomyocyte pyroptosis through the SSTR2-AMPK-Drp1-NLRP3 pathway. Importantly, CST specifically binds to SSTR2, which promotes AMPK phosphorylation, inhibits Drp1-mediated mitochondrial fission, and reduces ROS levels, thereby inhibiting NLRP3 inflammasome activation-mediated pyroptosis and alleviating sepsis-induced myocardial injury.

Drp1: Focus on Diseases Triggered by the Mitochondrial Pathway

Drp1 (Dynamin-Related Protein 1) is a cytoplasmic GTPase protein encoded by the DNM1L gene that influences mitochondrial dynamics by mediating mitochondrial fission processes. Drp1 has been demonstrated to play an important role in a variety of life activities such as cell survival, proliferation, migration, and death. Drp1 has been shown to play different physiological roles under different physiological conditions, such as normal and inflammation. Recently studies have revealed that Drp1 plays a critical role in the occurrence, development, and aggravation of a series of diseases, thereby it serves as a potential therapeutic target for them. In this paper, we review the structure and biological properties of Drp1, summarize the biological processes that occur in the inflammatory response to Drp1, discuss its role in various cancers triggered by the mitochondrial pathway and investigate effective methods for targeting Drp1 in cancer treatment. We also synthesized the phenomena of Drp1 involving in the triggering of other diseases. The results discussed herein contribute to our deeper understanding of mitochondrial kinetic pathway-induced diseases and their therapeutic applications. It is critical for advancing the understanding of the mechanisms of Drp1-induced mitochondrial diseases and preventive therapies.

The current insights of mitochondrial hormesis in the occurrence and treatment of bone and cartilage degeneration

It is widely acknowledged that aging, mitochondrial dysfunction, and cellular phenotypic abnormalities are intricately associated with the degeneration of bone and cartilage. Consequently, gaining a comprehensive understanding of the regulatory patterns governing mitochondrial function and its underlying mechanisms holds promise for mitigating the progression of osteoarthritis, intervertebral disc degeneration, and osteoporosis. Mitochondrial hormesis, referred to as mitohormesis, represents a cellular adaptive stress response mechanism wherein mitochondria restore homeostasis and augment resistance capabilities against stimuli by generating reactive oxygen species (ROS), orchestrating unfolded protein reactions (UPRmt), inducing mitochondrial-derived peptides (MDP), instigating mitochondrial dynamic changes, and activating mitophagy, all prompted by low doses of stressors. The varying nature, intensity, and duration of stimulus sources elicit divergent degrees of mitochondrial stress responses, subsequently activating one or more signaling pathways to initiate mitohormesis. This review focuses specifically on the effector molecules and regulatory networks associated with mitohormesis, while also scrutinizing extant mechanisms of mitochondrial dysfunction contributing to bone and cartilage degeneration through oxidative stress damage. Additionally, it underscores the potential of mechanical stimulation, intermittent dietary restrictions, hypoxic preconditioning, and low-dose toxic compounds to trigger mitohormesis, thereby alleviating bone and cartilage degeneration.

lncRNA ZNF593-AS inhibits cardiac hypertrophy and myocardial remodeling by upregulating Mfn2 expression

lncRNA ZNF593 antisense (ZNF593-AS) transcripts have been implicated in heart failure through the regulation of myocardial contractility. The decreased transcriptional activity of ZNF593-AS has also been detected in cardiac hypertrophy. However, the function of ZNF593-AS in cardiac hypertrophy remains unclear. Herein, we report that the expression of ZNF593-AS reduced in a mouse model of left ventricular hypertrophy and cardiomyocytes in response to treatment with the hypertrophic agonist phenylephrine (PE). In vivo, ZNF593-AS aggravated pressure overload-induced cardiac hypertrophy in knockout mice. By contrast, cardiomyocyte-specific transgenic mice (ZNF593-AS MHC-Tg) exhibited attenuated TAC-induced cardiac hypertrophy. In vitro, vector-based overexpression using murine or human ZNF593-AS alleviated PE-induced myocyte hypertrophy, whereas GapmeR-induced inhibition aggravated hypertrophic phenotypes. By using RNA-seq and gene set enrichment analyses, we identified a link between ZNF593-AS and oxidative phosphorylation and found that mitofusin 2 (Mfn2) is a direct target of ZNF593-AS. ZNF593-AS exerts an antihypertrophic effect by upregulating Mfn2 expression and improving mitochondrial function. Therefore, it represents a promising therapeutic target for combating pathological cardiac remodeling.

The mitochondrial quality control system: a new target for exercise therapeutic intervention in the treatment of brain insulin resistance-induced neurodegeneration in obesity

Obesity is a major global health concern because of its strong association with metabolic and neurodegenerative diseases such as diabetes, dementia, and Alzheimer's disease. Unfortunately, brain insulin resistance in obesity is likely to lead to neuroplasticity deficits. Since the evidence shows that insulin resistance in brain regions abundant in insulin receptors significantly alters mitochondrial efficiency and function, strategies targeting the mitochondrial quality control system may be of therapeutic and practical value in obesity-induced cognitive decline. Exercise is considered as a powerful stimulant of mitochondria that improves insulin sensitivity and enhances neuroplasticity. It has great potential as a non-pharmacological intervention against the onset and progression of obesity associated neurodegeneration. Here, we integrate the current knowledge of the mechanisms of neurodegenration in obesity and focus on brain insulin resistance to explain the relationship between the impairment of neuronal plasticity and mitochondrial dysfunction. This knowledge was synthesised to explore the exercise paradigm as a feasible intervention for obese neurodegenration in terms of improving brain insulin signals and regulating the mitochondrial quality control system.

Prenatal arsenic metabolite exposure is associated with increased newborn mitochondrial DNA copy number: evidence from a birth cohort study

While mitochondria are susceptible to environmental detriments, little is known about potential associations between arsenic metabolites and mitochondria DNA copy number (mtDNAcn). We attempted to examine whether maternal urinary arsenic metabolite levels in different trimesters were related to neonatal cord blood mtDNAcn. We included 819 mother-newborn pairs embedded in an in-progress birth cohort survey performed from April 2014 to October 2016 in Wuhan, China. We determined maternal urinary arsenic species concentrations in different trimesters. We determined cord blood mtDNAcn using quantitative real-time polymerase chain reaction. In covariate-adjusted models, each one-unit increment of dimethylated arsenic (DMA) and total arsenic (TAs) in the third trimester was related to 8.43% (95% CI 1.13%, 16.26%) and 12.15% (95% CI 4.35%, 20.53%) increases in mtDNAcn, respectively. The dose-response trend with statistical significance was observed across tertiles of DMA and TAs in the third trimester with mtDNAcn (DMA percent changes (%Δ) = 25.60 (95% CI 6.73, 47.82), for the highest vs the lowest tertile (P = 0.02); TAs %Δ = 40.31 (95% CI 19.25, 65.10), for the highest vs the lowest tertile (P = 0.0002)). These findings may prove the relationships between prenatal arsenic species levels and neonatal mitochondrial dysfunction.

Aberrant expression of NEDD4L disrupts mitochondrial homeostasis by downregulating CaMKKβ in diabetic kidney disease

Disturbance in mitochondrial homeostasis within proximal tubules is a critical characteristic associated with diabetic kidney disease (DKD). CaMKKβ/AMPK signaling plays an important role in regulating mitochondrial homeostasis. Despite the downregulation of CaMKKβ in DKD pathology, the underlying mechanism remains elusive. The expression of NEDD4L, which is primarily localized to renal proximal tubules, is significantly upregulated in the renal tubules of mice with DKD. Coimmunoprecipitation (Co-IP) assays revealed a physical interaction between NEDD4L and CaMKKβ. Moreover, deletion of NEDD4L under high glucose conditions prevented rapid CaMKKβ protein degradation. In vitro studies revealed that the aberrant expression of NEDD4L negatively influences the protein stability of CaMKKβ. This study also explored the role of NEDD4L in DKD by using AAV-shNedd4L in db/db mice. These findings confirmed that NEDD4L inhibition leads to a decrease in urine protein excretion, tubulointerstitial fibrosis, and oxidative stress, and mitochondrial dysfunction. Further in vitro studies demonstrated that si-Nedd4L suppressed mitochondrial fission and reactive oxygen species (ROS) production, effects antagonized by si-CaMKKβ. In summary, the findings provided herein provide strong evidence that dysregulated NEDD4L disturbs mitochondrial homeostasis by negatively modulating CaMKKβ in the context of DKD. This evidence underscores the potential of therapeutic interventions targeting NEDD4L and CaMKKβ to safeguard renal tubular function in the management of DKD.

Environmental cadmium inhibits testicular testosterone synthesis via Parkin-dependent MFN1 degradation

Low testosterone (T) levels are associated with many common diseases, such as obesity, male infertility, depression, and cardiovascular disease. It is well known that environmental cadmium (Cd) exposure can induce T decline, but the exact mechanism remains unclear. We established a murine model in which Cd exposure induced testicular T decline. Based on the model, we found Cd caused mitochondrial fusion disorder and Parkin mitochondrial translocation in mouse testes. MFN1 overexpression confirmed that MFN1-dependent mitochondrial fusion disorder mediated the Cd-induced T synthesis suppression in Leydig cells. Further data confirmed Cd induced the decrease of MFN1 protein by increasing ubiquitin degradation. Testicular specific Parkin knockdown confirmed Cd induced the ubiquitin-dependent degradation of MFN1 protein through promoting Parkin mitochondrial translocation in mouse testes. Expectedly, testicular specific Parkin knockdown also mitigated testicular T decline. Mito-TEMPO, a targeted inhibitor for mitochondrial reactive oxygen species (mtROS), alleviated Cd-caused Parkin mitochondrial translocation and mitochondrial fusion disorder. As above, Parkin mitochondrial translocation induced mitochondrial fusion disorder and the following T synthesis repression in Cd-exposed Leydig cells. Collectively, our study elucidates a novel mechanism through which Cd induces T decline and provides a new treatment strategy for patients with androgen disorders.

Mitochondrial regulation of diabetic endothelial dysfunction: Pathophysiological links

Micro- and macrovascular complications frequently occur in patients with diabetes, with endothelial dysfunction playing a key role in the development and progression of the complications. For the early diagnosis and optimal treatment of vascular complications associated with diabetes, it is imperative to comprehend the cellular and molecular mechanisms governing the function of diabetic endothelial cells. Mitochondria function as crucial sensors of environmental and cellular stress regulating endothelial cell viability, structural integrity and function. Impaired mitochondrial quality control mechanisms and mitochondrial dysfunction are the main features of endothelial damage. Hence, targeted mitochondrial therapy is considered promising novel therapeutic options in vascular complications of diabetes. In this review, we focus on the mitochondrial functions in the vascular endothelial cells and the pathophysiological role of mitochondria in diabetic endothelial dysfunction, aiming to provide a reference for related drug development and clinical diagnosis and treatment.

Mitochondrial Fission in Nickel Nanoparticle-Induced Reproductive Toxicity: An In Vitro GC-1 Cell Study

Reproductive disorders and declining fertility rates are significant public health concerns affecting birth rates and future populations. Male infertility, often due to spermatogenesis defects, may be linked to environmental pollutants like nickel nanoparticles (Ni NPs). Ni NPs are extensively utilized across different industries. Nevertheless, their potential adverse effects cannot be overlooked. Previous studies have linked the reproductive toxicity induced by Ni NPs with disturbances in mitochondrial function. Mitochondrial division/fusion dynamics are crucial to their proper function, yet little is known about how Ni NPs perturb these dynamics and whether such perturbation contributes to the impairment of the male reproductive system. Herein, we demonstrated that the exposure of Ni NPs to the mouse-derived spermatogonia cell line (GC-1 cells) triggered DRP1-mediated mitochondrial division and the enhanced impairment of mitochondria, consequently promoting mitochondria-dependent cell apoptosis. Notably, both the mitochondrial division inhibitor (Mdivi-1) and lentiviral-transfected cells with low expression of Dnm1l-DK in these cells could mitigate the toxic effects induced by Ni NPs, pointing to the potential role of mitochondrial dynamics in Ni NP-induced reproductive toxicity. Collectively, our work contributes to the understanding of the mechanisms by which Ni NPs can impact male reproductive function and identifies mitochondrial division as a potential target for intervention.

Mitochondria in Mesenchymal Stem Cells: Key to Fate Determination and Therapeutic Potential

Mesenchymal stem cells (MSCs) have become popular tool cells in the field of transformation and regenerative medicine due to their function of cell rescue and cell replacement. The dynamically changing mitochondria serve as an energy metabolism factory and signal transduction platform, adapting to different cell states and maintaining normal cell activities. Therefore, a clear understanding of the regulatory mechanism of mitochondria in MSCs is profit for more efficient clinical transformation of stem cells. This review highlights the cutting-edge knowledge regarding mitochondrial biology from the following aspects: mitochondrial morphological dynamics, energy metabolism and signal transduction. The manuscript mainly focuses on mitochondrial mechanistic insights in the whole life course of MSCs, as well as the potential roles played by mitochondria in MSCs treatment of transplantation, for seeking pivotal targets of stem cell fate regulation and stem cell therapy.

A state-of-the-science review of using mitochondrial DNA copy number as a biomarker for environmental exposure

Mitochondria are bioenergetic, biosynthetic, and signaling organelles in eukaryotes, and contain their own genomes, mitochondrial DNA (mtDNA), to supply energy to cells by generating ATP via oxidative phosphorylation. Therefore, the threat to mitochondria' integrity and health resulting from environmental exposure could induce adverse health effects in organisms. In this review, we summarized the association between mtDNA copy number (mtDNAcn), and environmental exposures as reported in the literature. We conducted a literature search in the Web of Science using [Mitochondrial DNA copy number] and [Exposure] as two keywords and employed three selection criteria for the final inclusion of 97 papers for review. The consensus of data was that mtDNAcn could be used as a plausible biomarker for cumulative exposures to environmental chemical and physical agents. In order to furtherly expand the application of mtDNAcn in ecological and environmental health research, we suggested a series of algorithms aiming to standardize the calculation of mtDNAcn based on the PCR results in this review. We also discussed the pitfalls of using whole blood/plasma samples for mtDNAcn measurements and regard buccal cells a plausible and practical alternative. Finally, we recognized the importance of better understanding the mechanistic analysis and regulatory mechanism of mtDNAcn, in particular the signals release and regulation pathways. We believe that the development of using mtDNAcn as an exposure biomarker will revolutionize the evaluation of chronic sub-lethal toxicity of chemicals to organisms in ecological and environmental health research that has not yet been implemented.

Mitochondrial metabolism in neural stem cells and implications for neurodevelopmental and neurodegenerative diseases

Mitochondria are cytoplasmic organelles having a fundamental role in the regulation of neural stem cell (NSC) fate during neural development and maintenance.During embryonic and adult neurogenesis, NSCs undergo a metabolic switch from glycolytic to oxidative phosphorylation with a rise in mitochondrial DNA (mtDNA) content, changes in mitochondria shape and size, and a physiological augmentation of mitochondrial reactive oxygen species which together drive NSCs to proliferate and differentiate. Genetic and epigenetic modifications of proteins involved in cellular differentiation (Mechanistic Target of Rapamycin), proliferation (Wingless-type), and hypoxia (Mitogen-activated protein kinase)-and all connected by the common key regulatory factor Hypoxia Inducible Factor-1A-are deemed to be responsible for the metabolic shift and, consequently, NSC fate in physiological and pathological conditions.Both primary mitochondrial dysfunction due to mutations in nuclear DNA or mtDNA or secondary mitochondrial dysfunction in oxidative phosphorylation (OXPHOS) metabolism, mitochondrial dynamics, and organelle interplay pathways can contribute to the development of neurodevelopmental or progressive neurodegenerative disorders.This review analyses the physiology and pathology of neural development starting from the available in vitro and in vivo models and highlights the current knowledge concerning key mitochondrial pathways involved in this process.

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatment of diabetes and its complications: An update since 2010

Diabetes, characterized as a well-known chronic metabolic syndrome, with its associated complications pose a substantial and escalating health and healthcare challenge on a global scale. Current strategies addressing diabetes are mainly symptomatic and there are fewer available curative pharmaceuticals for diabetic complications. Thus, there is an urgent need to identify novel pharmacological targets and agents. The impaired mitochondria have been associated with the etiology of diabetes and its complications, and the intervention of mitochondrial dysfunction represents an attractive breakthrough point for the treatments of diabetes and its complications. Natural products (NPs), with multicenter characteristics, multi-pharmacological activities and lower toxicity, have been caught attentions as the modulators of mitochondrial functions in the therapeutical filed of diabetes and its complications. This review mainly summarizes the recent progresses on the potential of 39 NPs and 2 plant-extracted mixtures to improve mitochondrial dysfunction against diabetes and its complications. It is expected that this work may be useful to accelerate the development of innovative drugs originated from NPs and improve upcoming therapeutics in diabetes and its complications.

G-quadruplex in mitochondria as a possible biomarker for mitophagy detection

Mitochondrial autophagy (mitophagy) is a key physiological process that maintains the homeostasis of mitochondrial quality and quantity. Monitoring mitophagy is of great significance for detecting cellular abnormalities and developing therapeutic drugs. However, there are still very few biomarkers specifically developed for monitoring mitophagy. Here, we propose for the first time that mitochondrial G-quadruplex may serve as a biomarker for mitophagy detection, and develope a fluorescent light-up probe AMTC to monitor mitophagy in live cells. During mitophagy, AMTC fluorescence is significantly enhanced, but once mitophagy is inhibited, its fluorescence immediately decreases. The fluorescence behavior of AMTC implicates an increase in the formation of mitochondrial G-quadruplex during mitophagy. This inference has also been supported by the other two G-quadruplex probes. Taken together, this work provides a new possible biomarker and detection tool for the study of mitophagy.

FOXO1 reduces STAT3 activation and causes impaired mitochondrial quality control in diabetic cardiomyopathy

AIMS

To investigate the role of FOXO1 in STAT3 activation and mitochondrial quality control in the diabetic heart.

METHODS

Type 1 diabetes mellitus (T1DM) was induced in rats by a single intraperitoneal injection of 60 mg · kg-1 streptozotocin (STZ), while type 2 diabetes mellitus (T2DM) was induced in rats with a high-fat diet through intraperitoneal injection of 35 mg · kg-1 STZ. Primary neonatal mouse cardiomyocytes and H9c2 cells were exposed to low glucose (5.5 mM) or high glucose (HG; 30 mM) with or without treatment with the FOXO1 inhibitor AS1842856 (1 μM) for 24 hours. In addition, the diabetic db/db mice (aged 8 weeks) and sex- and age-matched non-diabetic db/+ mice were treated with vehicle or AS1842856 by oral gavage for 15 days at a dose of 5 mg · kg-1  · d-1 .

RESULTS

Rats with T1DM or T2DM had excessive cardiac FOXO1 activation, accompanied by decreased STAT3 activation. Immunofluorescence and immunoprecipitation analysis showed colocalization and association of FOXO1 and STAT3 under basal conditions in isolated cardiomyocytes. Selective inhibition of FOXO1 activation by AS1842856 or FOXO1 siRNA transfection improved STAT3 activation, mitophagy and mitochondrial fusion, and decreased mitochondrial fission in isolated cardiomyocytes exposed to HG. Transfection with STAT3 siRNA further reduced mitophagy, mitochondrial fusion and increased mitochondrial fission in HG-treated cardiomyocytes. AS1842856 alleviated cardiac dysfunction, pathological damage and improved STAT3 activation, mitophagy and mitochondrial dynamics in diabetic db/db mice. Additionally, AS1842856 improved mitochondrial function indicated by increased mitochondrial membrane potential and adenosine triphosphate production and decreased mitochondrial reactive oxygen species production in isolated cardiomyocytes exposed to HG.

CONCLUSIONS

Excessive FOXO1 activation during diabetes reduces STAT3 activation, with subsequent impairment of mitochondrial quality, ultimately promoting the development of diabetic cardiomyopathy.

Global trends and hotspots in the field of mitochondrial dynamics and hepatocellular carcinoma: A bibliometric analysis from 2007 to 2023

BACKGROUND

Mitochondria are dynamic organelles, and mitochondrial dynamics are important for the maintenance of mitochondrial inheritance and function. Recently, an increasing number of studies have shown that mitochondrial dynamics play an important role in the occurrence and development of hepatocellular carcinoma (HCC). However, bibliometric analyses of mitochondrial dynamics in HCC are scarce. Therefore, we conducted a bibliometric analysis to explore the current global research status and trends in mitochondrial dynamics and HCC.

METHODS

Global publications on mitochondrial dynamics and HCC published between 2007 and May 2023 were retrieved from the Web of Science Core Collection (WoSCC) database. Bibliometric analysis was performed using Bibliometrix, VOSviewer, and CiteSpace to analyze the numbers, citations, countries, institutions, authors, journals, references, and keywords.

RESULTS

A total of 518 publications were retrieved fromthe WoSCC database. China and The Fourth Military Medical University were the most productive countries and institutions. Zorzano, A published the most literature whereas Chen, HC was the author with the highest number of co-citations. Plos One was the most popular journal, whereas the Journal of Biological Chemistry had the highest number of co-citations. The most frequently used keyword was "mitochondria". Further analysis of the references and keywords showed that the molecular mechanisms linking them to drug therapy targets should be the focus of future studies.

CONCLUSIONS

Research on mitochondrial dynamics in HCC has received much attention, and many studies have been published. However, research on mitochondrial dynamics and HCC has been limited by insufficient regional development imbalances and global cooperation. Nevertheless, future research on mitochondrial dynamics and HCC is promising, especially regarding the molecular mechanisms of mitochondrial fission and fusion and how to link the currently known molecular mechanisms with drug therapy targets for HCC.

Mitochondrial disturbance related to increased caspase-1 of CD4+T cells in HIV-1 infection

BACKGROUND

In HIV-1 infection, more than 95% of CD4+T cells die of caspase-1 mediated pyroptosis. What governs the increased susceptibility of CD4+T cells to pyroptosis is poorly understood.

METHODS

Blood samples were obtained from 31 untreated HIV-infected patients (UNT), 29 antiretroviral therapy treated HIV-infected patients (ART), and 21 healthy control donors (HD). Plasma levels of IL-18 and IL-1β, caspase-1 expression, mitochondrial mass (MM) and mitochondrial fusion/fisson genes of CD4+T subsets were measured.

RESULTS

A significantly higher IL-18 level in plasma and MM level of CD4+T cells were found in HIV-infected patients (UNT and ART) compared to HD, and the MMhigh phenotype was manifested, related to increased caspase-1 expression. Moreover, the increased MM was more pronounced in the early differentiated and inactivated CD4+T cells. However, higher MM was not intrinsically linked to T cell differentiation disorder or excessive activation of the CD4+T cells. Mechanistically, the increased MM was significantly correlated with an elevated level of expression of the mitochondrial fusion gene mitofusin1.

CONCLUSION

An increase in MM was associated with heightened sensitivity of CD4+T cells to pyroptosis, even in early differentiated and inactivated CD4+T cells, in patients with HIV-1 infection, regardless of whether patients were on antiretroviral therapy or not. These new revelations have uncovered a previously unappreciated challenge to immune reconstitution with antiretroviral therapy.

Mechanisms Governing Oligodendrocyte Viability in Multiple Sclerosis and Its Animal Models

Multiple sclerosis (MS) is a chronic autoimmune inflammatory demyelinating disease of the central nervous system (CNS), which is triggered by an autoimmune assault targeting oligodendrocytes and myelin. Recent research indicates that the demise of oligodendrocytes due to an autoimmune attack contributes significantly to the pathogenesis of MS and its animal model experimental autoimmune encephalomyelitis (EAE). A key challenge in MS research lies in comprehending the mechanisms governing oligodendrocyte viability and devising therapeutic approaches to enhance oligodendrocyte survival. Here, we provide an overview of recent findings that highlight the contributions of oligodendrocyte death to the development of MS and EAE and summarize the current literature on the mechanisms governing oligodendrocyte viability in these diseases.

Critical contribution of mitochondria in the development of cardiomyopathy linked to desmin mutation

BACKGROUND

Beyond the observed alterations in cellular structure and mitochondria, the mechanisms linking rare genetic mutations to the development of heart failure in patients affected by desmin mutations remain unclear due in part, to the lack of relevant human cardiomyocyte models.

METHODS

To shed light on the role of mitochondria in these mechanisms, we investigated cardiomyocytes derived from human induced pluripotent stem cells carrying the heterozygous DESE439K mutation that were either isolated from a patient or generated by gene editing. To increase physiological relevance, cardiomyocytes were either cultured on an anisotropic micropatterned surface to obtain elongated and aligned cardiomyocytes, or as a cardiac spheroid to create a micro-tissue. Moreover, when applicable, results from cardiomyocytes were confirmed with heart biopsies of suddenly died patient of the same family harboring DESE439K mutation, and post-mortem heart samples from five control healthy donors.

RESULTS

The heterozygous DESE439K mutation leads to dramatic changes in the overall cytoarchitecture of cardiomyocytes, including cell size and morphology. Most importantly, mutant cardiomyocytes display altered mitochondrial architecture, mitochondrial respiratory capacity and metabolic activity reminiscent of defects observed in patient's heart tissue. Finally, to challenge the pathological mechanism, we transferred normal mitochondria inside the mutant cardiomyocytes and demonstrated that this treatment was able to restore mitochondrial and contractile functions of cardiomyocytes.

CONCLUSIONS

This work highlights the deleterious effects of DESE439K mutation, demonstrates the crucial role of mitochondrial abnormalities in the pathophysiology of desmin-related cardiomyopathy, and opens up new potential therapeutic perspectives for this disease.

The role of mitochondrial dysfunction in macrophages on SiO2 -induced pulmonary fibrosis: A review

Several epidemiologic and toxicological studies have widely regarded that mitochondrial dysfunction is a popular molecular event in the process of silicosis from different perspectives, but the details have not been systematically summarized yet. Thus, it is necessary to investigate how silica dust leads to pulmonary fibrosis by damaging the mitochondria of macrophages. In this review, we first introduce the molecular mechanisms that silica dust induce mitochondrial morphological and functional abnormalities and then introduce the main molecular mechanisms that silica-damaged mitochondria induce pulmonary fibrosis. Finally, we conclude that the mitochondrial abnormalities of alveolar macrophages caused by silica dust are involved deeply in the pathogenesis of silicosis through these two sequential mechanisms. Therefore, reducing the silica-damaged mitochondria will prevent the potential occurrence and fatality of the disease in the future.

Mitochondrial Fragmentation as a Key Driver of Neurodegenerative Disease

Mitochondrial form and function are intricately linked through dynamic processes of fusion and fission, and disruptions in these processes are key drivers of neurodegenerative diseases, like Alzheimer's. The inability of mitochondria to transition between their dynamic forms is a critical factor in the development of pathological states. In this paper, we focus on the importance of different types of mitochondrial phenotypes in nervous tissue, discussing how mitochondria in Alzheimer's disease are "stuck" in certain patterns and how this pattern maintains itself. Understanding the specific roles and transitions between mitochondrial forms, including tiny, networked, and hyperfused, is crucial in developing new therapies aimed at restoring mitochondrial homeostasis. By targeting these dynamics, we may be able to intervene early in the disease process, offering novel avenues for preventing or treating neurodegeneration.

The underestimated role of mitochondria in vitiligo: From oxidative stress to inflammation and cell death

Vitiligo is an acquired depigmentary disorder characterized by the depletion of melanocytes in the skin. Mitochondria shoulder multiple functions in cells, such as production of ATP, maintenance of redox balance, initiation of inflammation and regulation of cell death. Increasing evidence has implicated the involvement of mitochondria in the pathogenesis of vitiligo. Mitochondria alteration will cause the abnormalities of mitochondria functions mentioned above, ultimately leading to melanocyte loss through various cell death modes. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in mitochondrial homeostasis, and the downregulation of Nrf2 in vitiligo may correlate with mitochondria damage, making both mitochondria and Nrf2 promising targets in treatment of vitiligo. In this review, we aim to discuss the alterations of mitochondria and its role in the pathogenesis of vitiligo.

DMSA-coated IONPs trigger oxidative stress, mitochondrial metabolic reprograming and changes in mitochondrial disposition, hindering cell cycle progression of cancer cells

There is increasing interest in modulating the redox homeostasis of tumors since high levels of reactive oxygen species (ROS) make them more vulnerable to changes in these species. Nanomedicine offers promise in this context as such applications may provoke biological responses that induce ROS production. Indeed, iron oxide nanoparticles (IONPs) can induce ROS accumulation through the so-called Fenton reaction of iron, further augmenting the ROS in tumors and overloading the antioxidant system beyond its capacity, thereby driving oxidative stress to a level that is incompatible with cell survival. Here, three different coatings for IONPs were compared to assess their intrinsic capacity to induce ROS production in cells. Of these coatings, dimercaptosuccinic acid-coated IONPs (DMSA-NPs) provoked the strongest ROS production, which was associated with the ability to reprogram the metabolism of cancer cells. This latter phenomenon involved shutting-down oxidative phosphorylation (OXPHOS), shifting mitochondrial morphology towards a more elongated phenotype, reducing the total mitochondrial mass and ultimately, blocking cell proliferation by inducing G0/G1 cell cycle arrest. Consequently, the data obtained highlights the importance of studying the chemical properties of IONPs, presenting DMSA-NPs as a novel tool to induce oxidative stress in cancer cells and alter their cell fate.

TORC1 mediated regulation of mitochondrial integrity and calcium ion homeostasis by Wat1/mLst8 in S. pombe

The mTOR complexes play a fundamental role in mitochondrial biogenesis and cellular homeostasis. Wat1, an ortholog of mammalian Lst8 is an important component of TOR complex and is essential for the regulation of downstream signaling. Earlier we reported the role of Wat1 in oxidative stress response. Here, we have shown that the abrogation of wat1 causes respiratory defects and mitochondrial depolarization that leads to a decrease in ATP production. The confocal and electron microscopy in wat1Δ cells revealed the fragmented mitochondrial morphology implying its role in mitochondrial fission. Furthermore, we also showed its role in autophagy and the maintenance of calcium ion homeostasis. Additionally, tor2-287 mutant cells also exhibit defects in mitochondrial integrity indicating the TORC1-dependent involvement of Wat1 in the maintenance of mitochondrial homeostasis. The interaction studies of Wat1 and Tor2 with Por1 and Mmm1 proteins revealed a plausible cross-talk between mitochondria and endoplasmic reticulum through the Mitochondria-associated membranes (MAM) and endoplasmic reticulum-mitochondria encounter structure (ERMES) complex, involving TORC1. Taken together, this study demonstrates the involvement of Wat1/mLst8 in harmonizing various mitochondrial functions, redox status, and Ca2+ homeostasis.

Hepatotoxicity of the Pesticide Avermectin Exposure to Freshwater-Farmed Carp: Evidence from In Vivo and In Vitro Research

Avermectin (AVM) is presently one of the most extensively employed insecticides across the globe. A number of toxicity research studies of AVM have been carried out in freshwater-farmed carp; however, there are currently no toxicity studies on the liver. This investigation aims to replicate an acute liver injury model induced by AVM in carp, subsequently analyzing the adverse effects imposed on the nontarget species while delving into potential mechanisms underlying its toxicity. In this study, we found that AVM-exposed carp liver tissue showed cellular hydration degeneration and necrosis and reduced the viability of hepatocyte L8824. Second, AVM induced oxidative stress in carp, and AVM stimulation led to reactive oxygen species (ROS) accumulation and Ca2+ overload in hepatocyte L8824, suggesting that AVM exposure induces mitochondrial dysfunction in hepatocytes. AVM induced inflammation in carp liver tissue by inducing mitochondrial kinetic disruption, which triggered hepatic tissue injury. AVM induced autophagy and apoptosis in carp liver tissue and ROS mediated AVM-induced autophagy and apoptosis. The formation of autophagy attenuated the AVM-induced liver injury. In conclusion, the present study elucidated the hepatotoxicity and potential mechanisms of freshwater aquaculture carp exposed to the pesticide AVM, emphasized the importance of monitoring pesticide AVM contamination in freshwater aquaculture aquatic environments, and provided theoretical references for the targeted prevention of AVM-induced toxicity in carp.

Effects of triclosan exposure on stem cells from human exfoliated deciduous teeth (SHED) fate

Triclosan (TCS), a widely used broad-spectrum antibacterial agent and preservative, is commonly found in products and environments. Widespread human exposure to TCS has drawn increasing attention from researchers concerning its toxicological effect. However, minimal studies have focused on the impact of TCS exposure on human stem cells. Therefore, the aim of the present study was to evaluate the effects of TCS exposure on stem cells from human exfoliated deciduous teeth (SHED) and its molecular mechanisms. A series of experimental methods were conducted to assess cell viability, morphology, proliferation, differentiation, senescence, apoptosis, mitochondrial function, and oxidative stress after SHED exposure to TCS. Furthermore, transcriptome analysis was applied to investigate the response of SHED to different concentrations of TCS exposure and to explore the molecular mechanisms. We demonstrated that TCS has a dose-dependent proliferation and differentiation inhibition of SHED, while promoting cellular senescence, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and oxidative stress, as well as significantly induces apoptosis and autophagy flux inhibition at high concentrations. Interestingly, no significant morphological changes in SHED were observed after TCS exposure. Transcriptome analysis of normal and TCS-induced SHED suggested that SHED may use different strategies to counteract stress from different concentrations of TCS and showed significant differences. We discovered that TCS mediates cellular injury of SHED by enhancing the expression of PTEN, thereby inhibiting the phosphorylation levels of PI3K and AKT as well as mTOR expression. Collectively, our findings provide a new understanding of the toxic effects of TCS on human stem cell fate, which is important for determining the risk posed by TCS to human health.

SIRT4 is a regulator of human skeletal muscle fatty acid metabolism influencing inner and outer mitochondrial membrane-mediated fusion

OBJECTIVE

The mitochondrial phenotype, governed by the balance of fusion-fission, is a key determinant of energy metabolism. The inner and outer mitochondrial membrane (IMM) fusion proteins optic atrophy 1 (OPA1) and Mitofusin 1 and 2 (Mfn1/2) play an important role in this process. Recent evidence also shows that Sirtuin 4 (SIRT4), located within the mitochondria, is involved in the regulation of fatty acid oxidation. The purpose of this study was to determine if SIRT4 expression regulates inner and outer mitochondrial-mediated fusion and substrate utilization within differentiated human skeletal muscle cells (HSkMC).

MATERIAL AND METHODS

SIRT4 expression was knocked down using small interfering RNA (siRNA) transfection in differentiated HSkMC. Following knockdown, mitochondrial respiration was determined by high-resolution respirometry (HRR) using the Oroboros Oxygraph O2k. Live cell confocal microscopy, quantified using the Mitochondrial Network Analysis (MiNA) toolset, was used to examine mitochondrial morphological change. This was further examined through the measurement of key metabolic and mitochondrial morphological regulators (mRNA and protein) induced by knockdown.

RESULTS

SIRT4 knockdown resulted in a significant decrease in LEAK respiration, potentially explained by a decrease in ANT1 protein expression. Knockdown further increased oxidative phosphorylation and protein expression of key regulators of fatty acid metabolism. Quantitative analysis of live confocal imaging of fluorescently labelled mitochondria following SIRT4 knockdown supported the role SIRT4 plays in the regulation of mitochondrial morphology, as emphasized by an increase in mitochondrial network branches and junctions. Measurement of key regulators of mitochondrial dynamics illustrated a significant increase in mitochondrial fusion proteins Mfn1, OPA1 respectively, indicative of an increase in mitochondrial size.

CONCLUSIONS

This study provides evidence of a direct relationship between the mitochondrial phenotype and substrate oxidation in HSkMC. We identify SIRT4 as a key protagonist of energy metabolism via its regulation of IMM and OMM fusion proteins, OPA1 and Mfn1. SIRT4 knockdown increases mitochondrial capacity to oxidize fatty acids, decreasing LEAK respiration and further increasing mitochondrial elongation via its regulation of mitochondrial fusion.

DNM1L variant presenting as adolescent-onset sensory neuronopathy, spasticity, dystonia, and ataxia

DMN1L encodes for dynamin-like protein 1 (DLP1) which plays a key role in perixosomal and mitochondrial fission. Individuals with heterozygous variants in DNM1L present with a wide range of neurologic symptoms, including encephalopathy, epilepsy, and motor deficits. Here we report on a woman presenting with adolescence onset of sensory neuronopathy, spasticity, dystonia, and ataxia. Trio genome sequencing identified a heterozygous variant in DNM1L (NM_012062.3 c.121G>A/p.Val41Met) which was thought to be pathogenic. This case describes the latest known symptomatic onset of DMN1L-related disease described in literature. We highlight our approach to a challenging diagnostic workup and interpretation of a specific variant that has not been previously reported. Furthermore, the case highlights the diagnostic importance of utilizing genomic sequencing and research studies for patients with rare disease.