Mitochondria-associated membranes in aging and senescence: structure, function, and dynamics

Calcium bridges built by mitochondria-associated endoplasmic reticulum membranes: potential targets for neural repair in neurological diseases

The exchange of information and materials between organelles plays a crucial role in regulating cellular physiological functions and metabolic levels. Mitochondria-associated endoplasmic reticulum membranes serve as physical contact channels between the endoplasmic reticulum membrane and the mitochondrial outer membrane, formed by various proteins and protein complexes. This microstructural domain mediates several specialized functions, including calcium (Ca 2+ ) signaling, autophagy, mitochondrial morphology, oxidative stress response, and apoptosis. Notably, the dysregulation of Ca 2+ signaling mediated by mitochondria-associated endoplasmic reticulum membranes is a critical factor in the pathogenesis of neurological diseases. Certain proteins or protein complexes within these membranes directly or indirectly regulate the distance between the endoplasmic reticulum and mitochondria, as well as the transduction of Ca 2+ signaling. Conversely, Ca 2+ signaling mediated by mitochondria-associated endoplasmic reticulum membranes influences other mitochondria-associated endoplasmic reticulum membrane-associated functions. These functions can vary significantly across different neurological diseases-such as ischemic stroke, traumatic brain injury, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease-and their respective stages of progression. Targeted modulation of these disease-related pathways and functional proteins can enhance neurological function and promote the regeneration and repair of damaged neurons. Therefore, mitochondria-associated endoplasmic reticulum membranes-mediated Ca 2+ signaling plays a pivotal role in the pathological progression of neurological diseases and represents a significant potential therapeutic target. This review focuses on the effects of protein complexes in mitochondria-associated endoplasmic reticulum membranes and the distinct roles of mitochondria-associated endoplasmic reticulum membranes-mediated Ca 2+ signaling in neurological diseases, specifically highlighting the early protective effects and neuronal damage that can result from prolonged mitochondrial Ca 2+ overload or deficiency. This article provides a comprehensive analysis of the various mechanisms of Ca 2+ signaling mediated by mitochondria-associated endoplasmic reticulum membranes in neurological diseases, contributing to the exploration of potential therapeutic targets for promoting neuroprotection and nerve repair.

Phosphatidylcholine Ameliorates Palmitic Acid-Induced Lipotoxicity by Facilitating Endoplasmic Reticulum and Mitochondria Contacts in Intervertebral Disc Degeneration

Background

Intervertebral disc degeneration (IDD) is a prevalent musculoskeletal disorder with substantial socioeconomic impacts. Despite its high prevalence, the pathogenesis of IDD remains unclear, and effective pharmacological interventions are lacking. This study aimed to investigate metabolic alterations in IDD and explore potential therapeutic targets by analyzing lipotoxicity-related mechanisms in nucleus pulposus (NP) cells.

Methods

Metabolomics and magnetic resonance spectroscopy were utilized to profile metabolic changes in NP tissues from advanced-stage IDD. Transcriptomics and metabolomics integration were performed to identify key regulatory pathways. In vitro experiments using human NP cells exposed to palmitic acid were conducted to evaluate endoplasmic reticulum (ER) stress, mitochondrial dysfunction, lipid droplet accumulation, and senescence. Phosphatidylcholine supplementation was tested for its ability to mitigate lipotoxicity, with ER-mitochondria interactions and mitochondrial oxidation capacity assessed as mechanistic endpoints.

Results

Our findings revealed an abnormal lipotoxic condition in NP cells from advanced-stage IDD. Furthermore, we identified abnormal accumulation of triglycerides and palmitic acid in NP cells from IDD. The palmitic acid accumulation resulted in endoplasmic reticulum stress, mitochondrial damage, lipid droplet accumulation, and senescence of NP cells. By integrating transcriptomics and metabolomics analyses, we discovered that phosphatidylcholine plays a role in regulating palmitic acid-induced lipotoxicity. Notably, phosphatidylcholine level was found to be low in the endoplasmic reticulum and mitochondria of advanced-stage NP cells. Phosphatidylcholine treatment alleviated palmitic acid-induced lipid droplet accumulation and senescence of NP cells by modulating ER-mitochondria contacts and mitochondrial oxidation capacity.

Conclusion

Phosphatidylcholine emerges as a potential therapeutic agent to counteract lipotoxic stress by modulating organelle interactions and mitochondrial function. These findings advance our understanding of IDD pathogenesis and provide a novel metabolic target for therapeutic development.

Visual Analysis of Research Hotspots and Trends on Mitochondria-Associated Membranes in the Past 20 Years-Focused on Neurodegenerative Diseases

The interaction between mitochondria and the endoplasmic reticulum is mediated by mitochondria-associated endoplasmic reticulum membranes (MAMs), which play a crucial role in regulating intracellular signal transduction and molecular interactions. This study employs bibliometric analysis to examine the research progress on MAMS and identify research hotspots and trends. A total of 1406 publications on MAMs were collected from the Web of Science Core Collection. Software such as CiteSpace, VOSviewer, and Scimago Graphica were utilized in the bibliometric analysis process. This study conducted a bibliometric analysis of over 20 years of MAM research, identifying the countries, institutions, authors, journals, and publications involved in the field. The number of publications on MAMs has been increasing annually since 2010, exhibiting a steady upward trend. The main contributors to this field are the USA, China, and Italy, with the journal Frontiers in Cell and Developmental Biology publishing the most publications. Common keywords include "endoplasmic reticulum stress," "Ca2 + ," "mitofusin2," "oxidative stress," "apoptosis," "autophagy," and "Alzheimer's disease." We found that the role of MAMs in neurodegenerative diseases has aroused great interest among researchers. The associations between calcium homeostasis, autophagy, mitochondrial dysfunction, and cell death with MAMs are also considered research hotspots and show broad research prospects. In addition, changes in MAM-resident proteins, including the mitochondria-ER tethering complex, Mfn2, and Sig-1R, have been highlighted as prominent research directions. The findings provide a comprehensive overview of research on MAMs and valuable insights for researchers, which is helpful for exploring future directions and trends in this field.

Restoring calcium crosstalk between ER and mitochondria promotes intestinal stem cell rejuvenation through autophagy in aged Drosophila

Breakdown of calcium network is closely associated with cellular aging. Previously, we found that cytosolic calcium (CytoCa2+) levels were elevated while mitochondrial calcium (MitoCa2+) levels were decreased and associated with metabolic shift in aged intestinal stem cells (ISCs) of Drosophila. How MitoCa2+ was decoupled from the intracellular calcium network and whether the reduction of MitoCa2+ drives ISC aging, however, remains unresolved. Here, we show that genetically restoring MitoCa2+ can reverse ISC functional decline and promote intestinal homeostasis by activating autophagy in aged flies. Further studies indicate that MitoCa2+ and Mitochondria-ER contacts (MERCs) form a positive feedback loop via IP3R to regulate autophagy independent of AMPK. Breakdown of this loop is responsible for MitoCa2+ reduction and ISC dysfunction in aged flies. Our results identify a regulatory module for autophagy initiation involving calcium crosstalk between the ER and mitochondria, providing a strategy to treat aging and age-related diseases.

The biomedical application of inorganic metal nanoparticles in aging and aging-associated diseases

Aging and aging-associated diseases (AAD), including neurodegenerative disease, cancer, cardiovascular diseases, and diabetes, are inevitable process. With the gradual improvement of life style, life expectancy is gradually extended. However, the extended lifespan has not reduced the incidence of disease, and most elderly people are in ill-health state in their later years. Hence, understanding aging and AAD are significant for reducing the burden of the elderly. Inorganic metal nanoparticles (IMNPs) predominantly include gold, silver, iron, zinc, titanium, thallium, platinum, cerium, copper NPs, which has been widely used to prevent and treat aging and AAD due to their superior properties (essential metal ions for human body, easily synthesis and modification, magnetism). Therefore, a systematic review of common morphological alternations of senescent cells, altered genes and signal pathways in aging and AAD, and biomedical applications of IMNPs in aging and AAD is crucial for the further research and development of IMNPs in aging and AAD. This review focus on the existing research on cellular senescence, aging and AAD, as well as the applications of IMNPs in aging and AAD in the past decade. This review aims to provide cutting-edge knowledge involved with aging and AAD, the application of IMNPs in aging and AAD to promote the biomedical application of IMNPs in aging and AAD.

The effect of mitochondrial-associated endoplasmic reticulum membranes (MAMs) modulation: New insights into therapeutic targets for depression

Depression is a prevalent mental disorder with high morbidity and mortality and its pathogenesis remains exactly unclarified. However, mitochondria and endoplasmic reticulum (ER) are two highly dynamic organelles that perform an indispensable role in the development of depression. Mitochondrial dysfunction and ER stress are recognized as vital pathological hallmarks in depression. The changes of intracellular activities such as mitochondrial dynamics, mitophagy, energy metabolism and ER stress are closely correlated with the progression of depression. Moreover, organelles interactions are conducive to homeostasis and cellular functions, and mitochondrial-associated endoplasmic reticulum membranes (MAMs) serve as signaling hubs of the two organelles and the coupling of the pathological progression. The main roles of MAMs are involved in metabolism, signal transduction, lipid transport, and maintenance of its structure and function. At present, accumulating studies elucidated that MAMs have gradually become a novel therapeutic target in treatment of depression. In the review, we focus on influence of mitochondria dysfunction and ER stress on depression. Furthermore, we discuss the underlying role of MAMs in depression and highlight natural products targeting MAMs as potential antidepressants to treat depression.

The context-dependent effect of cellular senescence: From embryogenesis and wound healing to aging

Aging is characterized by a steady loss of physiological integrity, leading to impaired function and increased vulnerability to death. Cell senescence is a biological process that progresses with aging and is believed to be a key driver of age-related diseases. Senescence, a hallmark of aging, also demonstrates its beneficial physiological aspects as an anti-cancer, pro-regenerative, homeostatic, and developmental mechanism. A transitory response in which the senescent cells are quickly formed and cleared may promote tissue regeneration and organismal fitness. At the same time, senescence-related secretory phenotypes associated with extended senescence can have devastating effects. The fact that the interaction between senescent cells and their surroundings is very context-dependent may also help to explain this seemingly opposing pleiotropic function. Further, mitochondrial dysfunction is an often-unappreciated hallmark of cellular senescence and figures prominently in multiple feedback loops that induce and maintain the senescent phenotype. This review summarizes the mechanism of cellular senescence and the significance of acute senescence. We concisely introduced the context-dependent role of senescent cells and SASP, aspects of mitochondrial biology altered in the senescent cells, and their impact on the senescent phenotype. Finally, we conclude with recent therapeutic advancements targeting cellular senescence, focusing on acute injuries and age-associated diseases. Collectively, these insights provide a future roadmap for the role of senescence in organismal fitness and life span extension.

Massage-Mimicking Nanosheets Mechanically Reorganize Inter-organelle Contacts to Restore Mitochondrial Functions in Parkinson's Disease

Parkinson's disease (PD) is exacerbated by dysfunction of inter-organelle contact, which depends on cellular responses to the mechanical microenvironment and can be regulated by external mechanical forces. Delivering dynamic mechanical forces to neural cells proves challenging due to the skull. Inspired by the effects of massage; here PEGylated black phosphorus nanosheets (PEG-BPNS), known for their excellent biocompatibility, biodegradability, specific surface area, mechanical strength, and flexibility, are introduced, which are capable of adhering to neural cell membrane and generating mechanical stimulation with their lateral size of 200 nm, exhibiting therapeutic potential in a 1-methyl-4-phenyl-1,2,3,6-te-trahydropyridine-induced PD mouse model by regulating inter-organelle contacts. Specifically, it is found that 200 nm PEG-BPNS, acting as "NanoMassage," significantly increase  plasma membrane tension, as evidenced by fluorescent lipid tension reporter fluorescence lifetime analysis. This mechanical force modulates actin reorganization, subsequently regulating the contacts between actin, mitochondria, and endoplasmic reticulum, further controlling mitochondrial fission and mitigating mitochondrial dysfunction in PD, exhibiting therapeutic efficacy via intranasal administration. These findings provide a noninvasive strategy for applying mechanical stimulation to deep brain areas and elucidate the mechanism of NanoMassage mediating inter-organelle contacts, suggesting the rational design of "NanoMassage" to remodel inter-organelle communications in neurodegenerative disease treatment.

Age-associated reduction in ER-Mitochondrial contacts impairs mitochondrial lipid metabolism and autophagosome formation in the heart

The accumulation of dysfunctional giant mitochondria is a hallmark of aged cardiomyocytes. This study investigated the core mechanism underlying this phenomenon, focusing on the disruption of mitochondrial lipid metabolism and its effects on mitochondrial dynamics and autophagy, using both naturally aging mouse models and etoposide-induced cellular senescence models. In aged cardiomyocytes, a reduction in endoplasmic reticulum-mitochondrial (ER-Mito) contacts impairs lipid transport and leads to insufficient synthesis of mitochondrial phosphatidylethanolamine (PE). A deficiency in phosphatidylserine decarboxylase (PISD) further hinders the conversion of phosphatidylserine to PE within mitochondria, exacerbating the deficit of PE production. This PE shortage disrupts autophagosomal membrane formation, leading to impaired autophagic flux and the accumulation of damaged mitochondria. Modulating LACTB expression to enhance PISD activity and PE production helps maintain mitochondrial homeostasis and the integrity of aging cardiomyocytes. These findings highlight the disruption of mitochondrial lipid metabolism as a central mechanism driving the accumulation of dysfunctional giant mitochondria in aged cardiomyocytes and suggest that inhibiting LACTB expression could serve as a potential therapeutic strategy for mitigating cardiac aging and preserving mitochondrial function.

Correlation of organelle interactions in the development of non-alcoholic fatty liver disease

Organelles, despite having distinct functions, interact with each other. Interactions between organelles typically occur at membrane contact sites (MCSs) to maintain cellular homeostasis, allowing the exchange of metabolites and other pieces of information required for normal cellular physiology. Imbalances in organelle interactions may lead to various pathological processes. Increasing evidence suggests that abnormalorganelle interactions contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the key role of organelle interactions in NAFLD has not been fully evaluated and researched. In this review, we summarize the role of organelle interactions in NAFLD and emphasize their correlation with cellular calcium homeostasis, lipid transport, and mitochondrial dynamics.

Connexin43 Contributes to Alzheimer's Disease by Promoting the Mitochondria-Associated Membrane-Related Autophagy Inhibition

The perturbed structure and function of mitochondria-associated membranes (MAM), instead of the amyloid cascade, have been gradually proposed to play a basic role in the pathogenesis of Alzheimer's disease (AD). Notably, autophagy inhibition is one of the main mechanisms of MAM dysfunction and plays an important role in neuronal injury. However, the upstream molecular mechanism underlying the MAM dysfunctions remains elusive. Here, we defined an unexpected and critical role of connexin43 (Cx43) in regulating the MAM structure. The expression levels of Cx43 and mitofusin-2 (MFN2, the MAM biomarker) increase significantly in 9-month-old APPswe/PS1dE9 double-transgenic AD model mice, and there is an obvious colocalization relationship. Moreover, both AD mice and cells lacking Cx43 exhibit an evident reduction in the MAM contact sites, which subsequently promotes the conversion from microtubule-associated protein 1 light-chain 3B I (LC3B-I) to LC3B-II via inhibition mTOR-dependent pathway and then initiates the generation of autophagosomes. Autophagosome formation ultimately promotes β-amyloid (Aβ) clearance and attenuates Aβ-associated pathological changes in AD, mainly including astrogliosis and neuronal apoptosis. Our findings not only reveal a previously unrecognized effect of Cx43 on MAM upregulation but also highlight the major player of MAM-induced autophagy inhibition in Cx43-facilitated AD pathogenesis, providing a novel insight into the alternative therapeutic strategies for the early treatment of AD.

The ultrastructural and proteomic analysis of mitochondria-associated endoplasmic reticulum membrane in the midbrain of a Parkinson's disease mouse model

Recent studies indicated that the dysregulation of mitochondria-associated endoplasmic reticulum membrane (MAM) could be a significant hub in the pathogenesis of Parkinson's disease (PD). However, little has been known about how MAM altered in PD. This study was aimed to observe morphological changes and analyze proteomic profiles of MAM in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse models. In MPTP-treated mice, transmission electron microscopy was applied for MAM ultrastructural visualization. Nano ultra-high performance liquid chromatography-tandem mass spectrum and bioinformatic analysis were adopted to obtain underlying molecular data of MAM fractions. The loosened, shortened and reduced MAM tethering was found in substantia nigral neurons from MPTP-treated mice. In midbrain MAM proteomics, 158 differentially expressed proteins (DEPs) were identified between two groups. Specific DEPs were validated by western blot and exhibited significantly statistical changes, aligning with proteomic results. Bioinformatic analysis indicated that membrane, cytoplasm and cell projection were three major localizations for DEPs. Biological processes including metabolism, lipid transport, and immunological and apoptotic signaling pathways were greatly affected. For consensus MAM proteins, the enriched pathway analysis revealed the potential relationship between neurodegenerative diseases and MAM. Several biological processes such as peroxisome function and clathrin-mediated endocytosis, were clustered, which provided additional insights into the fundamental molecular pathways associated with MAM. In our study, we demonstrated disrupted ER-mitochondria contacts in an MPTP-induced PD mouse model. The underlying signatures of MAM were revealed by proteomics and bioinformatic analysis, providing valuable insights into its potential role in PD pathogenesis.

Role of Pink1 in Regulating Osteoclast Differentiation during Periodontitis

Periodontitis has recently been recognized as an inflammatory disease caused by oxidative stress, with mitochondrial dysfunction being a key factor leading to oxidative stress. PTEN-induced kinase 1 (PINK1) is an essential protein for mitochondrial quality control, which protects cells from oxidative stress by inducing mitophagy to degrade damaged mitochondria, but its role in periodontitis has not been elucidated. This study aimed to explore the contribution and underlying mechanisms of Pink1 in regulating the differentiation and function of osteoclasts during periodontitis. Here we observed a significant downregulation of PINK1 expression in periodontitis-affected tissues. Then we constructed a periodontitis model in mice with fluorescently labeled mononuclear/macrophages, and the results showed that as the modeling time extended, the alveolar bone destruction gradually worsened and was accompanied by gradually decreased Pink1 expression in osteoclasts and a significantly increased osteoclast number. In vitro experiments further demonstrated a negative correlation between Pink1 and osteoclast differentiation. In addition, alveolar bone destruction in the Pink1 knockout mice was significantly more advanced than that in the littermate wild type mice after ligature-induced periodontitis and enhanced osteoclastogenesis and bone-resorptive capacity in vitro. RNA-sequencing analysis and in vitro validation revealed that the absence of Pink1 led to a decrease in oxidative phosphorylation levels and an enhancement of calcium-mediated signaling, specifically the calcineurin-NFATc1 pathway, via an intracellular calcium source. Further mechanistic studies found that the deficiency of Pink1 inhibited mitophagy but strengthened mitochondrial-endoplasmic reticulum coupling, which, by promoting the interaction of Mfn2-IP3R-VDAC1 proteins, increased the concentration of mitochondrial calcium ions, thereby triggering more active osteoclast differentiation. The aforementioned process can be reversed by the IP3R channel inhibitor Bcl-XL. These findings unveiled that Pink1 was involved in osteoclast differentiation by regulating mitochondrial calcium transport mediated by mitochondria-associated endoplasmic reticulum membranes, providing a new theoretical basis for the pathogenesis and treatment of periodontitis.

Mitochondria-associated endoplasmic reticulum membranes and myocardial ischemia: from molecular mechanisms to therapeutic strategies

Myocardial ischemia has the highest disease burden among all cardiovascular diseases making it a significant challenge to the global public health. It can result in myocardial cell damage and death due to impaired mitochondrial and endoplasmic reticulum (ER) functions. These two organelles are important regulators of cell death. In recent years, research has shifted from isolated studies of individual organelles to a more integrative approach, with a particular focus on their membrane contact sites-Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs). These dynamic microdomains play a crucial role in regulating material exchange and signal transduction between the endoplasmic reticulum and mitochondria. This review comprehensively describes the intricate structure of MAMs and their multifaceted roles in cellular pathophysiological processes. Particular focus was directed at the far-reaching effects of MAMs in regulating key pathological events including calcium homeostasis, mitochondrial dysfunction, ER stress, oxidative stress, and autophagy in ischemic heart disease (IHD). The potential treatment targets and regulatory mechanisms of MAMs were discussed and summarized, providing novel research directions and treatment approaches for improving myocardial ischemia-related diseases.

Systemic Rejuvenating Interventions: Perspectives on Neuroinflammation and Blood-Brain Barrier Integrity

The aging process results in structural, functional, and immunological changes in the brain, which contribute to cognitive decline and increase vulnerability to neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and stroke-related complications. Aging leads to cognitive changes and also affect executive functions. Additionally, it causes neurogenic and neurochemical alterations, such as a decline in dopamine and acetylcholine levels, which also impact cognitive performance. The chronic inflammation caused by aging contributes to the impairment of the blood-brain barrier (BBB), contributing to the infiltration of immune cells and exacerbating neuronal damage. Therefore, rejuvenating therapies such as heterochronic parabiosis, cerebrospinal fluid (CSF) administration, plasma, platelet-rich plasma (PRP), and stem cell therapy have shown potential to reverse these changes, offering new perspectives in the treatment of age-related neurological diseases. This review focuses on highlighting the effects of rejuvenating interventions on neuroinflammation and the BBB.

Mitochondrial fission and fusion in neurodegenerative diseases:Ca2+ signalling

Neurodegenerative diseases (NDs) are a group of disorders characterized by the progressive loss of neuronal structure and function. The pathogenesis is intricate and involves a network of interactions among multiple causes and systems. Mitochondria and Ca2+ signaling have long been considered to play important roles in the development of various NDs. Mitochondrial fission and fusion dynamics are important processes of mitochondrial quality control, ensuring the stability of mitochondrial structure and function. Mitochondrial fission and fusion imbalance and Ca2+ signaling disorders can aggravate the disease progression of NDs. In this review, we explore the relationship between mitochondrial dynamics and Ca2+ signaling in AD, PD, ALS, and HD, focusing on the roles of key regulatory proteins (Drp1, Fis1, Mfn1/2, and Opa1) and the association structures between mitochondria and the endoplasmic reticulum (MERCs/MAMs). We provide a detailed analysis of their involvement in the pathogenesis of these four NDs. By integrating these mechanisms, we aim to clarify their contributions to disease progression and offer insights into the development of therapeutic strategies that target mitochondrial dynamics and Ca2+ signaling. We also examine the progress in drug research targeting these pathways, highlighting their potential as therapeutic targets in the treatment of NDs.

Endoplasmic Reticulum-Mitochondria Crosstalk in Fuchs Endothelial Corneal Dystrophy: Current Status and Future Prospects

Fuchs endothelial corneal dystrophy (FECD) is a progressive and debilitating disorder of the corneal endothelium (CE) that affects approximately 4% of individuals over the age of 40. Despite the burden of the disease, the pathogenesis of FECD remains poorly understood, and treatment options are limited, highlighting the need for deeper investigation into its underlying molecular mechanisms. Over the past decade, studies have indicated independent contributions of endoplasmic reticulum (ER) and mitochondrial stress to the pathogenesis of FECD. However, there are limited studies suggesting ER-mitochondria crosstalk in FECD. Recently, our lab established the role of chronic ER stress in inducing mitochondrial dysfunction for corneal endothelial cells (CEnCs), indicating the existence of ER-mitochondria crosstalk in FECD. This paper aims to provide a comprehensive overview of the current understanding of how ER and mitochondrial stress contribute to FECD pathogenesis. The paper also reviews the literature on the mechanisms of ER-mitochondria crosstalk in other diseases relevant to FECD.

Mitochondria and the Repurposing of Diabetes Drugs for Off-Label Health Benefits

This review describes our current understanding of the role of the mitochondria in the repurposing of the anti-diabetes drugs metformin, gliclazide, GLP-1 receptor agonists, and SGLT2 inhibitors for additional clinical benefits regarding unhealthy aging, long COVID, mental neurogenerative disorders, and obesity. Metformin, the most prominent of these diabetes drugs, has been called the "Drug of Miracles and Wonders," as clinical trials have found it to be beneficial for human patients suffering from these maladies. To promote viral replication in all infected human cells, SARS-CoV-2 stimulates the infected liver cells to produce glucose and to export it into the blood stream, which can cause diabetes in long COVID patients, and metformin, which reduces the levels of glucose in the blood, was shown to cut the incidence rate of long COVID in half for all patients recovering from SARS-CoV-2. Metformin leads to the phosphorylation of the AMP-activated protein kinase AMPK, which accelerates the import of glucose into cells via the glucose transporter GLUT4 and switches the cells to the starvation mode, counteracting the virus. Diabetes drugs also stimulate the unfolded protein response and thus mitophagy, which is beneficial for healthy aging and mental health. Diabetes drugs were also found to mimic exercise and help to reduce body weight.

Calcium balance through mutual orchestrated inter-organelle communication: A pleiotropic target for combating Alzheimer's disease

Dysfunctional intraneuronal organelles in Alzheimer's Disease (AD) propel aberrant calcium handling, triggering molecular miscommunication within organelles such as mitochondria, endoplasmic reticulum, and lysosomes. This disruption in organelle function not only impairs cellular homeostasis but also exacerbates neurodegenerative processes involving the accumulation of amyloid-β (Aβ) and hyperphosphorylated tau, amplifying the disease's vicious cycle. In this review, the concept of Mutual Orchestrated Inter-organelle Communication (MOIC) proposes potential therapeutic avenues for restoring Ca2+ homeostasis in AD, offering a theoretical framework for developing disease-modifying treatments. The intricate nature of AD necessitates a shift towards combination therapies targeting MOIC-associated pathways, presenting a more effective approach than monotherapy.

Mitochondrial Unfolded Protein Response (mtUPR) and Diseases

Mitochondria are the energy factories of cells, and their functions are closely related to cell homeostasis. The mitochondrial unfolded protein response (mtUPR) is a newly discovered mechanism for regulating mitochondrial homeostasis. When unfolded/ misfolded proteins accumulate in mitochondria, the mitochondria release signals that regulate the transcription of certain proteins in the nucleus, thereby inducing the correct folding or degradation of proteins in mitochondria. Many studies have also shown that an abnormality of mtUPR is closely related to the occurrence and development of diseases. Here, we summarized the pathways regulating mtUPR signaling and reviewed the research progress on mtUPR in diseases. Finally, we summarized the currently identified agonists and inhibitors of the mtUPR and discussed the potential of the mtUPR as a therapeutic target for diseases.

Myricetin Alleviates Silica-Mediated Lung Fibrosis via PPARγ-PGC-1α Loop and Suppressing Mitochondrial Senescence in Epithelial Cells

OBJECTIVE

Long-term inhalation of silica dust particles leads to lung tissue fibrosis, resulting in impaired gas exchange and increased mortality. Silica inhalation triggers the aging of epithelial cells (AECs), which is a key contributor to the development of pulmonary fibrosis. Myricetin, a flavonoid compound extracted from Myrica genus plants, possesses various biological activities, including antioxidant and immunomodulatory effects. However, the mechanisms underlying myricetin's ability to counter senescence and fibrosis need to be further studied.

EXPERIMENTAL APPROACH

In vivo, the antifibrotic and anti-senescence effects of myricetin were evaluated using a silica-induced pulmonary fibrosis mouse model. To further elucidate the mechanisms by which myricetin counteracts silica-induced senescence, in vitro experiments were conducted using AECs.

RESULTS

Our studies revealed that myricetin treatment alleviated silica-induced mortality, improved lung function, and reduced the severity of pulmonary fibrosis in mice. Immunofluorescence analysis suggests its potential in mitigating senescence of AECs. Under laboratory conditions, myricetin intervened in the cellular senescence pathway induced by silica dust by modulating mitochondrial function. It acted through the PPARγ-PGC1α axis, effectively reducing silica-induced mitochondrial oxidative stress in AECs, promoting mitophagy, and maintaining mitochondrial dynamics. However, the efficacy of myricetin was reversed under PPARγ siRNA intervention. Additionally, myricetin exhibited an enhancing effect on PPARγ and autophagy in animal models. Treatment with PPARγ and PGC-1α siRNA elucidated the role of myricetin in promoting the formation of a positive feedback loop between PPARγ and PGC-1α. Additionally, the PPARγ inhibitor GW9662 verified the in vivo effects of myricetin.

CONCLUSIONS

Myricetin activates PPARγ, forming a PPARγ-PGC-1α loop, which promotes mitophagy and maintains mitochondrial dynamics. This alleviates epithelial cell senescence induced by silica exposure, consequently mitigating silica-induced pulmonary fibrosis in mice.

Inter- and intracellular mitochondrial communication: signaling hubs in aging and age-related diseases

Mitochondria are versatile and complex organelles that can continuously communicate and interact with the cellular milieu. Deregulated communication between mitochondria and host cells/organelles has significant consequences and is an underlying factor of many pathophysiological conditions, including the process of aging. During aging, mitochondria lose function, and mitocellular communication pathways break down; mitochondrial dysfunction interacts with mitochondrial dyscommunication, forming a vicious circle. Therefore, strategies to protect mitochondrial function and promote effective communication of mitochondria can increase healthy lifespan and longevity, which might be a new treatment paradigm for age-related disorders. In this review, we comprehensively discuss the signal transduction mechanisms of inter- and intracellular mitochondrial communication, as well as the interactions between mitochondrial communication and the hallmarks of aging. This review emphasizes the indispensable position of inter- and intracellular mitochondrial communication in the aging process of organisms, which is crucial as the cellular signaling hubs. In addition, we also specifically focus on the status of mitochondria-targeted interventions to provide potential therapeutic targets for age-related diseases.

Tau proteins and senescent Cells: Targeting aging pathways in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease characterized by abnormal accumulation of tau proteins and amyloid-β, leading to neuronal death and cognitive impairment. Recent studies have implicated aging pathways, including dysregulation of tau and cellular senescence in AD pathogenesis. In AD brains, tau protein, which normally stabilizes microtubules, becomes hyperphosphorylated and forms insoluble neurofibrillary tangles. These tau aggregates impair neuronal function and are propagated across the brain's neurocircuitry. Meanwhile, the number of senescent cells accumulating in the aging brain is rising, releasing a pro-inflammatory SASP responsible for neuroinflammation and neurodegeneration. This review explores potential therapeutic interventions for AD targeting tau protein and senescent cells, and tau -directed compounds, senolytics, eliminating senescent cells, and agents that modulate the SASP-senomodulators. Ultimately, a combined approach that incorporates tau-directed medications and targeted senescent cell-based therapies holds promise for reducing the harmful impact of AD's shared aging pathways.

Human salivary histatin 1 regulating IP3R1/GRP75/VDAC1 mediated mitochondrial-associated endoplasmic reticulum membranes (MAMs) inhibits cell senescence for diabetic wound repair

RATIONALE

Difficulty in skin wound healing is a concern for diabetic patients across the world. Impaired mitochondrial dysfunction and aging-related vascular dysfunction in human umbilical vein endothelial cells (HUVECs) caused by oxidative stress are major impediments to diabetic wound healing. However, research on skin repair at the mechanistic level by improving mitochondrial function and inhibiting oxidative stress-induced HUVEC senescence remains lacking.

METHODS AND RESULTS

Human saliva effectively inhibits the natural aging of HUVECs through immunodepletion experiments. Histatin 1 (Hst1), a short peptide comprising 38 amino acids, is the primary component of human saliva that prevents HUVEC aging. Based on in vitro findings, Hst1 decreased staining for senescence-associated β-galactosidase activity and expression of mediators of senescence signaling, including p53, p21, and p16. Mechanistically, HUVEC senescence is associated with Hst1-modulated nuclear factor Nrf2 signaling as Hst1 induces ERK-mediated Nrf2 nuclear translocation through NADPH oxidase-dependent ROS regulation, reinforced Nrf2 antioxidant response, and suppressed oxidative stress. RNA sequencing identified that the mitochondrial-related gene set was enriched in the Hst1 group. Coimmunoprecipitation indicated that Hst1 delayed hydrogen peroxide-induced HUVEC senescence by inhibiting mitochondria-associated endoplasmic reticulum (ER) membrane formation mediated by inositol 1,4,5-trisphosphate receptor 1-glucose-regulated protein 75-voltage-dependent anion channel 1 (VDAC1) complex interactions. Furthermore, in aging HUVECs, Hst1 treatment or VDAC1 silencing with small interfering RNA hindered calcium (Ca2+) transfer from the ER to the mitochondria, thereby ameliorating mitochondrial Ca2+ overload and restoring mitochondrial function. In an in vivo mouse model of diabetes mellitus skin defects, Hst1 facilitated wound healing by stimulating the new blood vessel formation and impeding the expression of senescent biomarkers.

CONCLUSIONS

This study proposes a theoretical solution that Hst1 can restore mitochondrial function by inhibiting oxidative stress or cellular senescence, thereby promoting angiogenesis and diabetic wound repair.

Phillyrin promotes autophagosome formation in A53T-αSyn-induced Parkinson's disease model via modulation of REEP1

BACKGROUND

The preservation of autophagosome formation presents a promising strategy for tackling neurological disorders, such as Parkinson's disease (PD). Mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) serve not only as a focal point linked to various neurological disorders but also play a crucial role in supporting the biogenesis of autophagosomes.

PURPOSE

This investigation aimed to elucidate the neuroprotective properties of phillyrin against PD and its underlying mechanisms in promoting autophagosome formation.

METHODS

ER and mitochondria co-localization was assessed via fluorescent staining. Annexin V-fluorescein isothiocyanate (FITC) fluorescence was employed to quantify accessible cardiolipin (CL) on mitochondrial surfaces. The levels of CL within the MAM fraction of SH-SY5Y cells were evaluated using a CL probe assay kit. Monodansylcadaverine staining was utilized to detect autophagosome formation in SH-SY5Y cells. In an A53T-alpha-synuclein (αSyn)-induced PD mouse model, the anti-PD properties of phillyrin were assessed using open field, pole climbing, and rotarod tests, as well as immunohistochemistry staining of TH+ neurons in the brain sections.

RESULTS

In A53T-αSyn-treated SH-SY5Y cells, phillyrin facilitated autophagosome formation by suppressing CL externalization and restoring MAM integrity. Phillyrin enhanced the localization of receptor expression-enhancing protein 1 (REEP1) within MAM and mitochondria, bolstering MAM formation. Increased REEP1 levels in mitochondria, attributed to phillyrin, enhanced the interaction between REEP1 and NDPK-D, thereby reducing CL externalization. Furthermore, phillyrin exhibited a dose-dependent enhancement of motor function in mice, accompanied by an increase in the abundance of dopaminergic neurons within the substantia nigra.

CONCLUSIONS

These findings illuminate phillyrin's ability to enhance MAM formation through upregulation of REEP1 expression within MAM, while concurrently attenuating CL externalization via the REEP1-NDPK-D interaction. These mechanisms bolster autophagosome biogenesis, offering resilience against A53T-αSyn-induced PD. Thus, our study advances the understanding of phillyrin's complex mechanisms and underscores its potential as a therapeutic approach for PD, opening new avenues in natural product pharmacology.

Mitochondrial disruption resulting from Cepharanthine-mediated TOM inhibition triggers ferroptosis in colorectal cancer cells

BACKGROUND

Chemotherapy for colorectal cancer (CRC) urgently needs low-toxicity and highly effective phytomedicine. Cepharanthine (Cep) shown to have multiple anti-tumor effects, including colorectal cancer, whose pivotal mechanisms are not fully understood. Herein, the present work aims to reveal the impact of Cep on the mitochondrial and anti-injury functions of CRC cells.

METHODS

The TOM70/20 expression was screened by bioinformatic databases. SW480 cells were utilized as the colorectal cancer cell model. The expression of TOM70/20 and the downstream molecules were measured by western blots (WB). The ferroptosis was analyzed using Transmission electron microscopy (TEM), C11-BODIPY, PGSK, and DCFH-DA probes, wherein the detection was performed by flow cytometry and laser confocal microscopy. The anti-cancer efficacy was conducted by CCK-8 and Annexin-V/PI assay. The rescue experiments were carried out using Fer-1 and TOM70 plasmid transfection.

RESULTS

Bioinformatic data identified TOM20 and TOM70 were highly expressed in colorectal cancer, which could be down-regulated by Cep. Further findings disclosed that Cep treatment destroyed the mitochondria and inactivated the NRF2 signaling pathway, an essential pathway for resistance to ferroptosis, thereby promoting reactive oxygen species (ROS) generation in CRC cells. As a result, prominent ferroptosis could be observed in CRC cells in response to Cep, which thereby led to the reduced cell viability of cancer cells. On the contrary, recovery of TOM70 dampened the Cep-elicited mitochondria damage, ferroptosis, and anti-cancer efficacy.

CONCLUSION

In summary, Cep-mediated TOM inhibition inactivates the NRF2 signaling pathway, thereby triggering ferroptosis and achieving an anti-colorectal cancer effect. The current study provides an innovative chemotherapeutic approach for colorectal cancer with phytomedicine.

Interplay of α-Synuclein Oligomers and Endoplasmic Reticulum Stress in Parkinson'S Disease: Insights into Cellular Dysfunctions

Oligomeric forms of α-synuclein (α-syn) are critical in the formation of α-synuclein fibrils, exhibiting neurotoxic properties that are pivotal in the pathogenesis of Parkinson's disease (PD). A salient feature of this pathology is the disruption of the protein folding capacity of the endoplasmic reticulum (ER), leading to a perturbation in the ER's protein quality control mechanisms. The accumulation of unfolded or misfolded proteins instigates ER stress. However, the onset of ER stress and the consequent activation of the Unfolded Protein Response (UPR) and Endoplasmic Reticulum-Associated Degradation (ERAD) pathways do not merely culminate in apoptosis when they fail to restore cellular homeostasis. More critically, this condition initiates a cascade of reactions involving ER-related structures and organelles, resulting in multifaceted cellular damage and, potentially, a feedback loop that precipitates neuroinflammation. In this review, we elucidate the interplay between UPR and ERAD, as well as the intricate crosstalk among the ER and other organelles such as mitochondria, lysosomes, and the Golgi apparatus, underscoring their roles in the neurodegenerative process.

GRP75-dependent mitochondria-ER contacts ensure cell survival during early mouse thymocyte development

Mitochondria and endoplasmic reticulum contacts (MERCs) control multiple cellular processes, including cell survival and differentiation. Based on the observations that MERCs were specifically enriched in the CD4-CD8- double-negative (DN) stage, we studied their role in early mouse thymocyte development. We found that T cell-specific knockout of Hspa9, which encodes GRP75, a protein that mediates MERC formation by assembling the IP3R-GRP75-VDAC complex, impaired DN3 thymocyte viability and resulted in thymocyte developmental arrest at the DN3-DN4 transition. Mechanistically, GRP75 deficiency induced mitochondrial stress, releasing mitochondrial DNA (mtDNA) into the cytosol and triggering the type I interferon (IFN-I) response. The IFN-I pathway contributed to both the impairment of cell survival and DN3-DN4 transition blockage, while increased lipid peroxidation (LPO) played a major role downstream of IFN-I. Thus, our study identifies the essential role of GRP75-dependent MERCs in early thymocyte development and the governing facts of cell survival and differentiation in the DN stage.

MAMs and Mitochondrial Quality Control: Overview and Their Role in Alzheimer's Disease

Alzheimer's disease (AD) represents the most widespread neurodegenerative disorder, distinguished by a gradual onset and slow progression, presenting a substantial challenge to global public health. The mitochondrial-associated membrane (MAMs) functions as a crucial center for signal transduction and material transport between mitochondria and the endoplasmic reticulum, playing a pivotal role in various pathological mechanisms of AD. The dysregulation of mitochondrial quality control systems is considered a fundamental factor in the development of AD, leading to mitochondrial dysfunction and subsequent neurodegenerative events. Recent studies have emphasized the role of MAMs in regulating mitochondrial quality control. This review will delve into the molecular mechanisms underlying the imbalance in mitochondrial quality control in AD and provide a comprehensive overview of the role of MAMs in regulating mitochondrial quality control.

A promising anti-tumor targeting on ERMMDs mediated abnormal lipid metabolism in tumor cells

The investigation of aberrations in lipid metabolism within tumor has become a burgeoning field of study that has garnered significant attention in recent years. Lipids can serve as a potent source of highly energetic fuel to support the rapid growth of neoplasia, in where the ER-mitochondrial membrane domains (ERMMDs) provide an interactive network for facilitating communication between ER and mitochondria as well as their intermembrane space and adjunctive proteins. In this review, we discuss fatty acids (FAs) anabolic and catabolic metabolism, as well as how CPT1A-VDAC-ACSL clusters on ERMMDs participate in FAs transport, with a major focus on ERMMDs mediated collaborative loop of FAO, Ca2+ transmission in TCA cycle and OXPHOS process. Here, we present a comprehensive perspective on the regulation of aberrant lipid metabolism through ERMMDs conducted tumor physiology might be a promising and potential target for tumor starvation therapy.

Mitochondria in Aging and Alzheimer's Disease: Focus on Mitophagy

Alzheimer's disease (AD) is characterized by the accumulation of amyloid β and phosphorylated τ protein aggregates in the brain, which leads to the loss of neurons. Under the microscope, the function of mitochondria is uniquely primed to play a pivotal role in neuronal cell survival, energy metabolism, and cell death. Research studies indicate that mitochondrial dysfunction, excessive oxidative damage, and defective mitophagy in neurons are early indicators of AD. This review article summarizes the latest development of mitochondria in AD: 1) disease mechanism pathways, 2) the importance of mitochondria in neuronal functions, 3) metabolic pathways and functions, 4) the link between mitochondrial dysfunction and mitophagy mechanisms in AD, and 5) the development of potential mitochondrial-targeted therapeutics and interventions to treat patients with AD.

Dysregulation of FLVCR1a-dependent mitochondrial calcium handling in neural progenitors causes congenital hydrocephalus

Congenital hydrocephalus (CH), occurring in approximately 1/1,000 live births, represents an important clinical challenge due to the limited knowledge of underlying molecular mechanisms. The discovery of novel CH genes is thus essential to shed light on the intricate processes responsible for ventricular dilatation in CH. Here, we identify FLVCR1 (feline leukemia virus subgroup C receptor 1) as a gene responsible for a severe form of CH in humans and mice. Mechanistically, our data reveal that the full-length isoform encoded by the FLVCR1 gene, FLVCR1a, interacts with the IP3R3-VDAC complex located on mitochondria-associated membranes (MAMs) that controls mitochondrial calcium handling. Loss of Flvcr1a in mouse neural progenitor cells (NPCs) affects mitochondrial calcium levels and energy metabolism, leading to defective cortical neurogenesis and brain ventricle enlargement. These data point to defective NPCs calcium handling and metabolic activity as one of the pathogenetic mechanisms driving CH.

Triethylene Glycol Squalene Improves Hair Regeneration by Maintaining the Inductive Capacity of Human Dermal Papilla Cells and Preventing Premature Aging

De novo hair follicle (HF) regeneration, achieved through the replenishment of the dermal papilla (DP), acknowledged as the principal orchestrator of the hair growth cycle, is emerging as a prospective therapeutic intervention for alopecia. Nonetheless, multiple attempts have shown that these cells lose key inductive properties when cultured in a two-dimensional (2D) monolayer, leading to precocious senescence engendered by oxidative stress and inflammatory processes. Consequently, the three-dimensional (3D) spheroid technique is presently widely employed for DP cell culture. Nevertheless, substantiating the regenerative potential of these cells within the hair follicle (HF) milieu remains a challenge. In this current study, we aim to find a new approach to activate the inductive properties of DP cells. This involves the application of hair-growth-stimulating agents that not only exhibit concurrent protective efficacy against the aging process but also induce HF regeneration. To achieve this objective, we initially synthesized a novel highly amphiphilic derivative derived from squalene (SQ), named triethylene glycol squalene (Tri-SQ). Squalene itself is a potent antioxidant and anti-inflammatory compound traditionally employed as a drug carrier for alopecia treatment. However, its application is limited due to its low solubility. Subsequently, we applied this newly synthesized derivative to DP cells. The data obtained demonstrated that the derivative exhibits robust antioxidant and anti-inflammatory activities while concurrently promoting the expression of genes associated with hair growth. Moreover, to further assess the hair regrowth inductive properties of DP cells, we cultured the cells and treated them with Tri-SQ within a 3D spheroid system. Subsequently, these treated cells were injected into the previously depilated dorsal area of six-week-old male C57BL/6 mice. Results revealed that 20 days postinjection, a complete regrowth of hair in the previously hairless area, particularly evident in the case of 3D spheroids treated with the derivative, was observed. Additionally, histological and molecular analyses demonstrated an upregulation of markers associated with hair growth and a concurrent decrease in aging hallmarks, specifically in the 3D spheroids treated with the compound. In summary, our approach, which involves the treatment of Tri-SQ combined with a 3D spheroid system, exhibited a notably robust stimulating effect. This effect was observed in the induction of inductive properties in DP cells, leading to HF regeneration, and concurrently, it demonstrated an inhibitory effect on cellular and follicular aging.

A tripartite organelle platform links growth factor receptor signaling to mitochondrial metabolism

One open question in the biology of growth factor receptors is how a quantitative input (i.e., ligand concentration) is decoded by the cell to produce specific response(s). Here, we show that an EGFR endocytic mechanism, non-clathrin endocytosis (NCE), which is activated only at high ligand concentrations and targets receptor to degradation, requires a tripartite organelle platform involving the plasma membrane (PM), endoplasmic reticulum (ER) and mitochondria. At these contact sites, EGFR-dependent, ER-generated Ca2+ oscillations are sensed by mitochondria, leading to increased metabolism and ATP production. Locally released ATP is required for cortical actin remodeling and EGFR-NCE vesicle fission. The same biochemical circuitry is also needed for an effector function of EGFR, i.e., collective motility. The multiorganelle signaling platform herein described mediates direct communication between EGFR signaling and mitochondrial metabolism, and is predicted to have a broad impact on cell physiology as it is activated by another growth factor receptor, HGFR/MET.

Dialogue between mitochondria and endoplasmic reticulum-potential therapeutic targets for age-related cardiovascular diseases

Mitochondria-associated endoplasmic reticulum membranes (MAMs) act as physical membrane contact sites facilitating material exchange and signal transmission between mitochondria and endoplasmic reticulum (ER), thereby regulating processes such as Ca2+/lipid transport, mitochondrial dynamics, autophagy, ER stress, inflammation, and apoptosis, among other pathological mechanisms. Emerging evidence underscores the pivotal role of MAMs in cardiovascular diseases (CVDs), particularly in aging-related pathologies. Aging significantly influences the structure and function of the heart and the arterial system, possibly due to the accumulation of reactive oxygen species (ROS) resulting from reduced antioxidant capacity and the age-related decline in organelle function, including mitochondria. Therefore, this paper begins by describing the composition, structure, and function of MAMs, followed by an exploration of the degenerative changes in MAMs and the cardiovascular system during aging. Subsequently, it discusses the regulatory pathways and approaches targeting MAMs in aging-related CVDs, to provide novel treatment strategies for managing CVDs in aging populations.

DDAH-1 maintains endoplasmic reticulum-mitochondria contacts and protects dopaminergic neurons in Parkinson's disease

The loss of dopaminergic neurons in the substantia nigra is a hallmark of pathology in Parkinson's disease (PD). Dimethylarginine dimethylaminohydrolase-1 (DDAH-1) is the critical enzyme responsible for the degradation of asymmetric dimethylarginine (ADMA) which inhibits nitric oxide (NO) synthase and has been implicated in neurodegeneration. Mitochondrial dysfunction, particularly in the mitochondria-associated endoplasmic reticulum membrane (MAM), plays a critical role in this process, although the specific molecular target has not yet been determined. This study aims to examine the involvement of DDAH-1 in the nigrostriatal dopaminergic pathway and PD pathogenesis. The distribution of DDAH-1 in the brain and its colocalization with dopaminergic neurons were observed. The loss of dopaminergic neurons and aggravated locomotor disability after rotenone (ROT) injection were showed in the DDAH-1 knockout rat. L-arginine (ARG) and NO donors were employed to elucidate the role of NO respectively. In vitro, we investigated the effects of DDAH-1 knockdown or overexpression on cell viability and mitochondrial functions, as well as modulation of ADMA/NO levels using ADMA or ARG. MAM formation was assessed by the Mitofusin2 oligomerization and the mitochondrial ubiquitin ligase (MITOL) phosphorylation. We found that DDAH-1 downregulation resulted in enhanced cell death and mitochondrial dysfunctions, accompanied by elevated ADMA and reduced NO levels. However, the recovered NO level after the ARG supplement failed to exhibit a protective effect on mitochondrial functions and partially restored cell viability. DDAH-1 overexpression prevented ROT toxicity, while ADMA treatment attenuated these protective effects. The declines of MAM formation in ROT-treated cells were exacerbated by DDAH-1 downregulation via reduced MITOL phosphorylation, which was reversed by DDAH-1 overexpression. Together, the abundant expression of DDAH-1 in nigral dopaminergic neurons may exert neuroprotective effects by maintaining MAM formation and mitochondrial function probably via ADMA, indicating the therapeutic potential of targeting DDAH-1 for PD.

Connection Between HIV and Mitochondria in Cardiovascular Disease and Implications for Treatments

HIV infection and antiretroviral therapy alter mitochondrial function, which can progressively lead to mitochondrial damage and accelerated aging. The interaction between persistent HIV reservoirs and mitochondria may provide insight into the relatively high rates of cardiovascular disease and mortality in persons living with HIV. In this review, we explore the intricate relationship between HIV and mitochondrial function, highlighting the potential for novel therapeutic strategies in the context of cardiovascular diseases. We reflect on mitochondrial dynamics, mitochondrial DNA, and mitochondrial antiviral signaling protein in the context of HIV. Furthermore, we summarize how toxicities related to early antiretroviral therapy and current highly active antiretroviral therapy can contribute to mitochondrial dysregulation, chronic inflammation, and poor clinical outcomes. There is a need to understand the mechanisms and develop new targeted therapies. We further consider current and potential future therapies for HIV and their interplay with mitochondria. We reflect on the next-generation antiretroviral therapies and HIV cure due to the direct and indirect effects of HIV persistence, associated comorbidities, coinfections, and the advancement of interdisciplinary research fields. This includes exploring novel and creative approaches to target mitochondria for therapeutic intervention.

Potential targets for the treatment of MI: GRP75-mediated Ca2+ transfer in MAM

After myocardial infarction (MI), there is a notable disruption in cellular calcium ion homeostasis and mitochondrial function, which is believed to be intricately linked to endoplasmic reticulum (ER) stress. This research endeavors to elucidate the involvement of glucose regulated protein 75 (GRP75) in post-MI calcium ion homeostasis and mitochondrial function. In MI rats, symptoms of myocardial injury were accompanied by an increase in the activation of ER stress. Moreover, in oxygen-glucose deprivation (OGD)-induced cardiomyocytes, it was confirmed that inhibiting ER stress exacerbated intracellular Ca2+ disruption and cell apoptosis. Concurrently, the co-localization of GRP75 with IP3R and VDAC1 increased under ER stress in cardiomyocytes. In OGD-induced cardiomyocytes, knockdown of GRP75 not only reduced the Ca2+ levels in both the ER and mitochondria and improved the ultrastructure of cardiomyocytes, but it also increased the number of contact points between the ER and mitochondria, reducing mitochondria associated endoplasmic reticulum membrane (MAM) formation, and decreased cell apoptosis. Significantly, knockdown of GRP75 did not affect the protein expression of PERK and hypoxia-inducible factor 1α (HIF-1α). Transcriptome analysis of cardiomyocytes revealed that knockdown of GRP75 mainly influenced the molecular functions of sialyltransferase and IP3R, as well as the biosynthesis of glycosphingolipids and lactate metabolism. The complex interaction between the ER and mitochondria, driven by the GRP75 and its associated IP3R1-GRP75-VDAC1 complex, is crucial for calcium homeostasis and cardiomyocyte's adaptive response to ER stress. Modulating GRP75 could offer a strategy to regulate calcium dynamics, diminish glycolysis, and thereby mitigate cardiomyocyte apoptosis.

Deciphering mitochondrial dysfunction: Pathophysiological mechanisms in vascular cognitive impairment

Vascular cognitive impairment (VCI) encompasses a range of cognitive deficits arising from vascular pathology. The pathophysiological mechanisms underlying VCI remain incompletely understood; however, chronic cerebral hypoperfusion (CCH) is widely acknowledged as a principal pathological contributor. Mitochondria, crucial for cellular energy production and intracellular signaling, can lead to numerous neurological impairments when dysfunctional. Recent evidence indicates that mitochondrial dysfunction-marked by oxidative stress, disturbed calcium homeostasis, compromised mitophagy, and anomalies in mitochondrial dynamics-plays a pivotal role in VCI pathogenesis. This review offers a detailed examination of the latest insights into mitochondrial dysfunction within the VCI context, focusing on both the origins and consequences of compromised mitochondrial health. It aims to lay a robust scientific groundwork for guiding the development and refinement of mitochondrial-targeted interventions for VCI.

Correlation between Mitochondria-Associated Endoplasmic Reticulum Membrane-Related Genes and Cellular Senescence-Related Genes in Osteoarthritis

BACKGROUND

The role of mitochondria-associated endoplasmic reticulum membrane (MAM) formation in the development of osteoarthritis (OA) is yet unclear.

METHODS

A mix of bioinformatics methods and in vitro experimental methodologies was used to study and corroborate the role of MAM-related genes and cellular senescence-related genes in the development of OA. The Gene Expression Omnibus database was used to obtain the microarray information that is relevant to the OA. Several bioinformatic methods were employed to carry out function enrichment analysis and protein-protein correlation analysis, build the correlation regulatory network, and investigate potential relationships between MAM-related genes and cellular senescence-related genes in OA. These methods also served to identify the MAM-related and OA-related genes (MAM-OARGs).

RESULTS

For the additional functional enrichment analysis, a total of 13 MAM-OARGs were detected. The correlation regulatory network was also created. Hub MAM-OARGs were shown to have a strong correlation with genes relevant to cellular senescence in OA. Results of in vitro experiments further demonstrated a positive correlation between MAM-OARGs (PTPN1 and ITPR1) and cellular senescence-related and OA-related genes.

CONCLUSIONS

As a result, our findings can offer new insights into the investigations of MAM-related genes and cellular senescence-related genes, which could be linked to the OA as well as brand-new potential treatment targets.

Mitochondria-associated endoplasmic reticulum membranes as a therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are currently the leading cause of death worldwide. In 2022, the CVDs contributed to 19.8 million deaths globally, accounting for one-third of all global deaths. With an aging population and changing lifestyles, CVDs pose a major threat to human health. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are communication platforms between cellular organelles and regulate cellular physiological functions, including apoptosis, autophagy, and programmed necrosis. Further research has shown that MAMs play a critical role in the pathogenesis of CVDs, including myocardial ischemia and reperfusion injury, heart failure, pulmonary hypertension, and coronary atherosclerosis. This suggests that MAMs could be an important therapeutic target for managing CVDs. The goal of this study is to summarize the protein complex of MAMs, discuss its role in the pathological mechanisms of CVDs in terms of its functions such as Ca2+ transport, apoptotic signaling, and lipid metabolism, and suggest the possibility of MAMs as a potential therapeutic approach.

Mitochondria: A Potential Rejuvenation Tool against Aging

Aging is a complex physiological process encompassing both physical and cognitive decline over time. This intricate process is governed by a multitude of hallmarks and pathways, which collectively contribute to the emergence of numerous age-related diseases. In response to the remarkable increase in human life expectancy, there has been a substantial rise in research focusing on the development of anti-aging therapies and pharmacological interventions. Mitochondrial dysfunction, a critical factor in the aging process, significantly impacts overall cellular health. In this extensive review, we will explore the contemporary landscape of anti-aging strategies, placing particular emphasis on the promising potential of mitotherapy as a ground-breaking approach to counteract the aging process. Moreover, we will investigate the successful application of mitochondrial transplantation in both animal models and clinical trials, emphasizing its translational potential. Finally, we will discuss the inherent challenges and future possibilities of mitotherapy within the realm of aging research and intervention.

Ferroptosis mechanisms and regulations in cardiovascular diseases in the past, present, and future

Cardiovascular diseases (CVDs) are the main diseases that endanger human health, and their risk factors contribute to high morbidity and a high rate of hospitalization. Cell death is the most important pathophysiology in CVDs. As one of the cell death mechanisms, ferroptosis is a new form of regulated cell death (RCD) that broadly participates in CVDs (such as myocardial infarction, heart transplantation, atherosclerosis, heart failure, ischaemia/reperfusion (I/R) injury, atrial fibrillation, cardiomyopathy (radiation-induced cardiomyopathy, diabetes cardiomyopathy, sepsis-induced cardiac injury, doxorubicin-induced cardiac injury, iron overload cardiomyopathy, and hypertrophic cardiomyopathy), and pulmonary arterial hypertension), involving in iron regulation, metabolic mechanism and lipid peroxidation. This article reviews recent research on the mechanism and regulation of ferroptosis and its relationship with the occurrence and treatment of CVDs, aiming to provide new ideas and treatment targets for the clinical diagnosis and treatment of CVDs by clarifying the latest progress in CVDs research.

SYNJ2BP ameliorates intervertebral disc degeneration by facilitating mitochondria-associated endoplasmic reticulum membrane formation and mitochondrial Zn2+ homeostasis

Nucleus pulposus (NP) cell function-loss is one main contributor during intervertebral disc degeneration (IDD) progression. Both mitochondria and endoplasmic reticulum (ER) play vital roles in sustaining NP cell homeostasis, while the precise function of ER-mitochondria tethering and cross talk in IDD remain to be clarified. Here, we demonstrated that a notable disruption of mitochondria-associated ER membrane (MAM) was identified in degenerated discs and TBHP-induced NP cells, accompanied by mitochondrial Zn2+ overload and NP cell senescence. Importantly, experimental coupling of MAM contacts by MFN2, a critical regulator of MAM formation, could enhance NLRX1-SLC39A7 complex formation and mitochondrial Zn2+ homeostasis. Further using the sequencing data from TBHP-induced degenerative model of NP cells, combining the reported MAM proteomes, we demonstrated that SYNJ2BP loss was one critical pathological characteristic of NP cell senescence and IDD progression, which showed close relationship with MAM disruption. Overexpression of SYNJ2BP could facilitate MAM contact organization and NLRX1-SLC39A7 complex formation, thus promoted mitochondrial Zn2+ homeostasis, NP cell proliferation and intervertebral disc rejuvenation. Collectively, our present study revealed a critical role of SYNJ2BP in maintaining mitochondrial Zn2+ homeostasis in NP cells during IDD progression, partially via sustaining MAM contact and NLRX1-SLC39A7 complex formation.

Aryl hydrocarbon receptor: Linking environment to aging process in elderly patients with asthma

ABSTRACT

Aging is a significant risk factor for various diseases, including asthma, and it often leads to poorer clinical outcomes, particularly in elderly individuals. It is recognized that age-related diseases are due to a time-dependent accumulation of cellular damage, resulting in a progressive decline in cellular and physiological functions and an increased susceptibility to chronic diseases. The effects of aging affect not only the elderly but also those of younger ages, posing significant challenges to global healthcare. Thus, understanding the molecular mechanisms associated with aging in different diseases is essential. One intriguing factor is the aryl hydrocarbon receptor (AhR), which serves as a cytoplasmic receptor and ligand-activated transcription factor and has been linked to the aging process. Here, we review the literature on several major hallmarks of aging, including mitochondrial dysfunction, cellular senescence, autophagy, mitophagy, epigenetic alterations, and microbiome disturbances. Moreover, we provide an overview of the impact of AhR on these hallmarks by mediating responses to environmental exposures, particularly in relation to the immune system. Furthermore, we explore how aging hallmarks affect clinical characteristics, inflammatory features, exacerbations, and the treatment of asthma. It is suggested that AhR signaling may potentially play a role in regulating asthma phenotypes in elderly populations as part of the aging process.

AGK2 pre-treatment protects against thioacetamide-induced acute liver failure via regulating the MFN2-PERK axis and ferroptosis signaling pathway

BACKGROUND

Acute liver failure (ALF) is an unpredictable and life-threatening critical illness. The pathological characteristic of ALF is massive necrosis of hepatocytes and lots of inflammatory cells infiltration which may lead to multiple organ failure.

METHODS

Animals were divided into 3 groups, normal, thioacetamide (TAA, ALF model) and TAA + AGK2. Cultured L02 cells were divided into 5 groups, normal, TAA, TAA + mitofusin 2 (MFN2)-siRNA, TAA + AGK2, and TAA + AGK2 + MFN2-siRNA groups. The liver histology was evaluated with hematoxylin and eosin staining, inositol-requiring enzyme 1 (IRE1), activating transcription factor 6β (ATF6β), protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) and phosphorylated-PERK (p-PERK). C/EBP homologous protein (CHOP), reactive oxygen species (ROS), MFN2 and glutathione peroxidase 4 (GPX4) were measured with Western blotting, and cell viability and liver chemistry were also measured. Mitochondria-associated endoplasmic reticulum membranes (MAMs) were measured by immunofluorescence.

RESULTS

The liver tissue in the ALF group had massive inflammatory cell infiltration and hepatocytes necrosis, which were reduced by AGK2 pre-treatment. In comparison to the normal group, apoptosis rate and levels of IRE1, ATF6β, p-PERK, CHOP, ROS and Fe2+ in the TAA-induced ALF model group were significantly increased, which were decreased by AGK2 pre-treatment. The levels of MFN2 and GPX4 were decreased in TAA-induced mice compared with the normal group, which were enhanced by AGK2 pre-treatment. Compared with the TAA-induced L02 cell, apoptosis rate and levels of IRE1, ATF6β, p-PERK, CHOP, ROS and Fe2+ were further increased and levels of MFN2 and GPX4 were decreased in the MFN2-siRNA group. AGK2 pre-treatment decreased the apoptosis rate and levels of IRE1, ATF6β, p-PERK, CHOP, ROS and Fe2+ and enhanced the protein expression of MFN2 and GPX4 in MFN2-siRNA treated L02 cell. Immunofluorescence observation showed that level of MAMs was promoted in the AGK2 pre-treatment group when compared with the TAA-induced group in both mice and L02 cells.

CONCLUSIONS

The data suggested that AGK2 pre-treatment had hepatoprotective role in TAA-induced ALF via upregulating the expression of MFN2 and then inhibiting PERK and ferroptosis pathway in ALF.

Vitamin D ameliorates age-induced nonalcoholic fatty liver disease by increasing the mitochondrial contact site and cristae organizing system (MICOS) 60 level

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease. Despite intensive research, considerable information on NAFLD development remains elusive. In this study, we examined the effects of vitamin D on age-induced NAFLD, especially in connection with mitochondrial abnormalities. We observed the prevention of NAFLD in 22-month-old C57BL/6 mice fed a vitamin D3-supplemented (20,000 IU/kg) diet compared with mice fed a control (1000 IU/kg) diet. We evaluated whether vitamin D3 supplementation enhanced mitochondrial functions. We found that the level of mitochondrial contact site and cristae organizing system (MICOS) 60 (Mic60) level was reduced in aged mice, and this reduction was specifically restored by vitamin D3. In addition, depletion of Immt, the human gene encoding the Mic60 protein, induced changes in gene expression patterns that led to fat accumulation in both HepG2 and primary hepatocytes, and these alterations were effectively prevented by vitamin D3. In addition, silencing of the vitamin D receptor (VDR) decreased the Mic60 levels, which were recovered by vitamin D treatment. To assess whether VDR directly regulates Mic60 levels, we performed chromatin immunoprecipitation and reporter gene analysis. We discovered that VDR directly binds to the Immt 5' promoter region spanning positions -3157 to -2323 and thereby upregulates Mic60. Our study provides the first demonstration that a reduction in Mic60 levels due to aging may be one of the mechanisms underlying the development of aging-associated NAFLD. In addition, vitamin D3 could positively regulate Mic60 expression, and this may be one of the important mechanisms by which vitamin D could ameliorate age-induced NAFLD.

Oxidative stress and the role of redox signalling in chronic kidney disease

Chronic kidney disease (CKD) is a major public health concern, underscoring a need to identify pathogenic mechanisms and potential therapeutic targets. Reactive oxygen species (ROS) are derivatives of oxygen molecules that are generated during aerobic metabolism and are involved in a variety of cellular functions that are governed by redox conditions. Low levels of ROS are required for diverse processes, including intracellular signal transduction, metabolism, immune and hypoxic responses, and transcriptional regulation. However, excess ROS can be pathological, and contribute to the development and progression of chronic diseases. Despite evidence linking elevated levels of ROS to CKD development and progression, the use of low-molecular-weight antioxidants to remove ROS has not been successful in preventing or slowing disease progression. More recent advances have enabled evaluation of the molecular interactions between specific ROS and their targets in redox signalling pathways. Such studies may pave the way for the development of sophisticated treatments that allow the selective control of specific ROS-mediated signalling pathways.

The role of endoplasmic reticulum stress, mitochondrial dysfunction and their crosstalk in intervertebral disc degeneration

Low back pain (LBP) is a pervasive global health issue. Roughly 40% of LBP cases are attributed to intervertebral disc degeneration (IVDD). While the underlying mechanisms of IVDD remain incompletely understood, it has been confirmed that apoptosis and extracellular matrix (ECM) degradation caused by many factors such as inflammation, oxidative stress, calcium (Ca2+) homeostasis imbalance leads to IVDD. Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are involved in these processes. The initiation of ER stress precipitates cell apoptosis, and is also related to inflammation, levels of oxidative stress, and Ca2+ homeostasis. Additionally, mitochondrial dynamics, antioxidative systems, disruption of Ca2+ homeostasis are closely associated with Reactive Oxygen Species (ROS) and inflammation, promoting cell apoptosis. However, numerous crosstalk exists between the ER and mitochondria, where they interact through inflammatory cytokines, signaling pathways, ROS, or key molecules such as CHOP, forming positive and negative feedback loops. Furthermore, the contact sites between the ER and mitochondria, known as mitochondria-associated membranes (MAM), facilitate direct signal transduction such as Ca2+ transfer. However, the current attention towards this issue is insufficient. Therefore, this review summarizes the impacts of ER stress and mitochondrial dysfunction on IVDD, along with the possibly potential crosstalk between them, aiming to unveil novel avenues for IVDD intervention.

Age-Related Macular Degeneration and Mitochondria-Associated Autoantibodies: A Review of the Specific Pathogenesis and Therapeutic Strategies

Age-related macular degeneration (AMD) is a severe retinal disease that causes irreversible visual loss and blindness in elderly populations worldwide. The pathological mechanism of AMD is complex, involving the interactions of multiple environmental and genetic factors. A poor understanding of the disease leads to limited treatment options and few effective prevention methods. The discovery of autoantibodies in AMD patients provides an opportunity to explore the pathogenesis and treatment direction of the disease. This review focuses on the mitochondria-associated autoantibodies and summarizes the functional roles of mitochondria under physiological conditions and their alterations during the pathological states. Additionally, it discusses the crosstalk between mitochondria and other organelles, as well as the mitochondria-related therapeutic strategies in AMD.