Mitochondrial Fission Process 1 controls inner membrane integrity and protects against heart failure

An atlas of the aging mouse proteome reveals the features of age-related post-transcriptional dysregulation

To what extent and how post-transcriptional dysregulation affects aging proteome remains unclear. Here, we provide proteomic data of whole-tissue lysates (WTL) and low-solubility protein-enriched fractions (LSF) of major tissues collected from mice of 6, 15, 24, and 30 months of age. Low-solubility proteins are preferentially affected by age and the analysis of LSF doubles the number of proteins identified to be differentially expressed with age. Simultaneous analysis of proteome and transcriptome using the same tissue homogenates reveals the features of age-related post-transcriptional dysregulation. Post-transcriptional dysregulation becomes evident especially after 24 months of age and age-related post-transcriptional dysregulation leads to accumulation of core matrisome proteins and reduction of mitochondrial membrane proteins in multiple tissues. Based on our in-depth proteomic data and sample-matched transcriptome data of adult, middle-aged, old, and geriatric mice, we construct the Mouse aging proteomic atlas ( https://aging-proteomics.info/ ), which provides a thorough and integrative view of age-related gene expression changes.

Current insights and future directions of LncRNA Morrbid in disease pathogenesis

Non-coding RNAs have emerged as important regulators of gene expression and contributors to many diseases. LncRNA Morrbid, a long non-coding RNA, has been widely studied in recent years. Current literature reports that lncRNA Morrbid is involved in various diseases such as tumors, cardiovascular diseases, inflammatory diseases and metabolic disorder. However, controversial conclusions exist in current studies. As a potential therapeutic target, it is necessary to comprehensively review the current evidence. In this work, we carefully review the literature on Morrbid and discuss each of the hot topics related to lncRNA Morrbid.

Liver kinase B1 (LKB1) regulates the epigenetic landscape of mouse pancreatic beta cells

Liver kinase B1 (LKB1/STK11) is an important regulator of pancreatic β-cell identity and function. Elimination of Lkb1 from the β-cell results in improved glucose-stimulated insulin secretion and is accompanied by profound changes in gene expression, including the upregulation of several neuronal genes. The mechanisms through which LKB1 controls gene expression are, at present, poorly understood. Here, we explore the impact of β cell-selective deletion of Lkb1 on chromatin accessibility in mouse pancreatic islets. To characterize the role of LKB1 in the regulation of gene expression at the transcriptional level, we combine these data with a map of islet active transcription start sites and histone marks. We demonstrate that LKB1 elimination from β-cells results in widespread changes in chromatin accessibility, correlating with changes in transcript levels. Changes occurred in hundreds of promoter and enhancer regions, many of which were close to neuronal genes. We reveal that dysregulated enhancers are enriched in binding motifs for transcription factors (TFs) important for β-cell identity, such as FOXA, MAFA or RFX6, and we identify microRNAs (miRNAs) that are regulated by LKB1 at the transcriptional level. Overall, our study provides important new insights into the epigenetic mechanisms by which LKB1 regulates β-cell identity and function.

MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels

Mitochondrial dynamics play a critical role in cell fate decisions and in controlling mtDNA levels and distribution. However, the molecular mechanisms linking mitochondrial membrane remodeling and quality control to mtDNA copy number (CN) regulation remain elusive. Here, we demonstrate that the inner mitochondrial membrane (IMM) protein mitochondrial fission process 1 (MTFP1) negatively regulates IMM fusion. Moreover, manipulation of mitochondrial fusion through the regulation of MTFP1 levels results in mtDNA CN modulation. Mechanistically, we found that MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains from the rest of the network. Subsequently, peripheral fission ensures their segregation into small MTFP1-enriched mitochondria (SMEM) that are targeted for degradation in an autophagic-dependent manner. Remarkably, MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and therefore to maintain adequate mtDNA levels within the cell.

Mitochondrial Structure and Function in Human Heart Failure

Despite clinical and scientific advancements, heart failure is the major cause of morbidity and mortality worldwide. Both mitochondrial dysfunction and inflammation contribute to the development and progression of heart failure. Although inflammation is crucial to reparative healing following acute cardiomyocyte injury, chronic inflammation damages the heart, impairs function, and decreases cardiac output. Mitochondria, which comprise one third of cardiomyocyte volume, may prove a potential therapeutic target for heart failure. Known primarily for energy production, mitochondria are also involved in other processes including calcium homeostasis and the regulation of cellular apoptosis. Mitochondrial function is closely related to morphology, which alters through mitochondrial dynamics, thus ensuring that the energy needs of the cell are met. However, in heart failure, changes in substrate use lead to mitochondrial dysfunction and impaired myocyte function. This review discusses mitochondrial and cristae dynamics, including the role of the mitochondria contact site and cristae organizing system complex in mitochondrial ultrastructure changes. Additionally, this review covers the role of mitochondria-endoplasmic reticulum contact sites, mitochondrial communication via nanotunnels, and altered metabolite production during heart failure. We highlight these often-neglected factors and promising clinical mitochondrial targets for heart failure.

Targeting complement C3a receptor resolves mitochondrial hyperfusion and subretinal microglial activation in progranulin-deficient frontotemporal dementia

Mutations in progranulin ( GRN ) cause frontotemporal dementia ( GRN -FTD) due to deficiency of the pleiotropic protein progranulin. GRN -FTD exhibits diverse pathologies including lysosome dysfunction, lipofuscinosis, microgliosis, and neuroinflammation. Yet, how progranulin loss causes disease remains unresolved. Here, we report that non-invasive retinal imaging of GRN -FTD patients revealed deficits in photoreceptors and the retinal pigment epithelium (RPE) that correlate with cognitive decline. Likewise, Grn -/- mice exhibit early RPE dysfunction, microglial activation, and subsequent photoreceptor loss. Super-resolution live imaging and transcriptomic analyses identified RPE mitochondria as an early driver of retinal dysfunction. Loss of mitochondrial fission protein 1 (MTFP1) in Grn -/- RPE causes mitochondrial hyperfusion and bioenergetic defects, leading to NF-kB-mediated activation of complement C3a-C3a receptor signaling, which drives further mitochondrial hyperfusion and retinal inflammation. C3aR antagonism restores RPE mitochondrial integrity and limits subretinal microglial activation. Our study identifies a previously unrecognized mechanism by which progranulin modulates mitochondrial integrity and complement-mediated neuroinflammation.

Mitochondrial quality control in human health and disease

Mitochondria, the most crucial energy-generating organelles in eukaryotic cells, play a pivotal role in regulating energy metabolism. However, their significance extends beyond this, as they are also indispensable in vital life processes such as cell proliferation, differentiation, immune responses, and redox balance. In response to various physiological signals or external stimuli, a sophisticated mitochondrial quality control (MQC) mechanism has evolved, encompassing key processes like mitochondrial biogenesis, mitochondrial dynamics, and mitophagy, which have garnered increasing attention from researchers to unveil their specific molecular mechanisms. In this review, we present a comprehensive summary of the primary mechanisms and functions of key regulators involved in major components of MQC. Furthermore, the critical physiological functions regulated by MQC and its diverse roles in the progression of various systemic diseases have been described in detail. We also discuss agonists or antagonists targeting MQC, aiming to explore potential therapeutic and research prospects by enhancing MQC to stabilize mitochondrial function.

Liver kinase B1 (LKB1) regulates the epigenetic landscape of mouse pancreatic beta cells

Liver kinase B1 (LKB1/STK11) is an important regulator of pancreatic β-cell identity and function. Elimination of Lkb1 from the β-cell results in improved glucose-stimulated insulin secretion and is accompanied by profound changes in gene expression, including the upregulation of several neuronal genes. The mechanisms through which LKB1 controls gene expression are, at present, poorly understood. Here, we explore the impact of β cell- selective deletion of Lkb1 on chromatin accessibility in mouse pancreatic islets. To characterize the role of LKB1 in the regulation of gene expression at the transcriptional level, we combine these data with a map of islet active transcription start sites and histone marks. We demonstrate that LKB1 elimination from β-cells results in widespread changes in chromatin accessibility, correlating with changes in transcript levels. Changes occurred in hundreds of promoter and enhancer regions, many of which were close to neuronal genes. We reveal that dysregulated enhancers are enriched in binding motifs for transcription factors important for β-cell identity, such as FOXA, MAFA or RFX6 and we identify microRNAs (miRNAs) that are regulated by LKB1 at the transcriptional level. Overall, our study provides important new insights into the epigenetic mechanisms by which LKB1 regulates β-cell identity and function.

HIF1A-dependent overexpression of MTFP1 promotes lung squamous cell carcinoma development by activating the glycolysis pathway

Introduction

Mitochondrial fission process 1 (MTFP1) is an inner mitochondrial membrane (IMM) protein implicated in the development and progression of various tumors, particularly lung squamous cell carcinoma (LUSC). This study aims to provide a more theoretical basis for the treatment of LUSC.

Methods

Through bioinformatics analysis, MTFP1 was identified as a novel target gene of HIF1A. MTFP1 expression in LUSC was examined using The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Proteomics Data Commons (PDC) databases. The Kaplan-Meier plotter (KM plotter) database was utilized to evaluate its correlation with patient survival. Western blot and chromatin immunoprecipitation (ChIP) assays were employed to confirm the regulatory relationship between MTFP1 and HIF1A. Additionally, cell proliferation, colony formation, and migration assays were conducted to investigate the mechanism by which MTFP1 enhances LUSC cell proliferation and metastasis.

Results

Our findings revealed that MTFP1 overexpression correlated with poor prognosis in LUSC patients(P < 0.05). Moreover, MTFP1 was closely associated with hypoxia and glycolysis in LUSC (R = 0.203; P < 0.001, R = 0.391; P < 0.001). HIF1A was identified as a positive regulator of MTFP1. Functional enrichment analysis demonstrated that MTFP1 played a role in controlling LUSC cell proliferation. Cell proliferation, colony formation, and migration assays indicated that MTFP1 promoted LUSC cell proliferation and metastasis by activating the glycolytic pathway (P < 0.05).

Conclusions

This study establishes MTFP1 as a novel HIF1A target gene that promotes LUSC growth by activating the glycolytic pathway. Investigating MTFP1 may contribute to the development of effective therapies for LUSC patients, particularly those lacking targeted oncogene therapies.

Progression of herpesvirus infection remodels mitochondrial organization and metabolism

Viruses target mitochondria to promote their replication, and infection-induced stress during the progression of infection leads to the regulation of antiviral defenses and mitochondrial metabolism which are opposed by counteracting viral factors. The precise structural and functional changes that underlie how mitochondria react to the infection remain largely unclear. Here we show extensive transcriptional remodeling of protein-encoding host genes involved in the respiratory chain, apoptosis, and structural organization of mitochondria as herpes simplex virus type 1 lytic infection proceeds from early to late stages of infection. High-resolution microscopy and interaction analyses unveiled infection-induced emergence of rough, thin, and elongated mitochondria relocalized to the perinuclear area, a significant increase in the number and clustering of endoplasmic reticulum-mitochondria contact sites, and thickening and shortening of mitochondrial cristae. Finally, metabolic analyses demonstrated that reactivation of ATP production is accompanied by increased mitochondrial Ca2+ content and proton leakage as the infection proceeds. Overall, the significant structural and functional changes in the mitochondria triggered by the viral invasion are tightly connected to the progression of the virus infection.

Identifying Acss1, Mtfp1 and Oxct1 as key regulators and promising biomarkers of sarcopenia in various models

Mitochondrial dysfunction plays a critical role in muscular homeostasis, but the molecular mechanism underlying mitochondrial dynamics and sarcopenia awaits to be uncovered. We all know that malnutrition, cachexia, and type 2 diabetes are significant contributors to the development of sarcopenia.Therefore, we analyzed a bioinformatic analysis on cathectic differentially expressed genes (cDEGs), fasted differentially genes (fDEGs) and mitochondria-related genes. The overlapping genes identified were then validated by RT-qPCR and Western blotting experiments in various sarcopenia mice models and used to predict aging-related muscle loss in humans. First, the correlation analysis and PPI network indicated 6 overlapping candidates (Bdh1, Gdap1, Acss1, Mtfp1, Idh2, Oxct1) may constitute a regulatory effect in mitochondrial dynamics and muscle wasting. Next, we successfully established fasted, Lewis lung carcinoma (LLC) and Diabetes Mellitus (DM) induced sarcopenia mice models and verified that Acss1, Mtfp1 and Oxct1 shared common and significant variation tendency in these sarcopenia mice models. Further-more, Pearson correlation analysis showed that Acss1 was negatively related to the weight of gastrocnemius while Mtfp1 and Oxct1 displayed a significantly positive correlation with gastrocnemius weight in sarcopenic mice model induced by LLC, fasting and DM. What's more, ROC analysis based on human aging-related datasets indicated Acss1, Mtfp1, Oxct1 had outstanding diagnostic capabilities for sarcopenia. In general, we identified three hub genes (Acss1, Mtfp1 and Oxct1) that are strongly associated with mitochondrial dysfunction in sarcopenia and may provide novel and reliable indicators for screening, diagnosis, and prognosis, as well as potential therapeutic targets for patients with sarcopenia.

GOLPH3 Participates in Mitochondrial Fission and Is Necessary to Sustain Bioenergetic Function in MDA-MB-231 Breast Cancer Cells

In this study, we investigated the inter-organelle communication between the Golgi apparatus (GA) and mitochondria. Previous observations suggest that GA-derived vesicles containing phosphatidylinositol 4-phosphate (PI(4)P) play a role in mitochondrial fission, colocalizing with DRP1, a key protein in this process. However, the functions of these vesicles and potentially associated proteins remain unknown. GOLPH3, a PI(4)P-interacting GA protein, is elevated in various types of solid tumors, including breast cancer, yet its precise role is unclear. Interestingly, GOLPH3 levels influence mitochondrial mass by affecting cardiolipin synthesis, an exclusive mitochondrial lipid. However, the mechanism by which GOLPH3 influences mitochondria is not fully understood. Our live-cell imaging analysis showed GFP-GOLPH3 associating with PI(4)P vesicles colocalizing with YFP-DRP1 at mitochondrial fission sites. We tested the functional significance of these observations with GOLPH3 knockout in MDA-MB-231 cells of breast cancer, resulting in a fragmented mitochondrial network and reduced bioenergetic function, including decreased mitochondrial ATP production, mitochondrial membrane potential, and oxygen consumption. Our findings suggest a potential negative regulatory role for GOLPH3 in mitochondrial fission, impacting mitochondrial function and providing insights into GA-mitochondria communication.

METTL3 boosts mitochondrial fission and induces cardiac fibrosis after ischemia/reperfusion injury

METTL3, an RNA methyltransferase enzyme, exerts therapeutic effects on various cardiovascular diseases. Myocardial ischemia-reperfusion injury (MIRI) and subsequently cardiac fibrosis is linked to acute cardiomyocyte death or dysfunction induced by mitochondrial damage, particularly mitochondrial fission. Our research aims to elucidate the potential mechanisms underlying the therapeutic actions of METTL3 in MIRI, with focus on mitochondrial fission. When compared with Mettl3flox mice subjected to MIRI, Mettl3 cardiomyocyte knockout (Mettl3Cko) mice have reduced infarct size, decreased serum levels of myocardial injury-related factors, limited cardiac fibrosis, and preserved myocardial ultrastructure and contractile/relaxation capacity. The cardioprotective actions of Mettl3 knockout were associated with reduced inflammatory responses, decreased myocardial neutrophil infiltration, and suppression of cardiomyocyte death. Through signaling pathway validation experiments and assays in cultured HL-1 cardiomyocytes exposed to hypoxia/reoxygenation, we confirmed that Mettl3 deficiency interfere with DNA-PKcs phosphorylation, thereby blocking the downstream activation of Fis1 and preventing pathological mitochondrial fission. In conclusion, this study confirms that inhibition of METTL3 can alleviate myocardial cardiac fibrosis inflammation and prevent cardiomyocyte death under reperfusion injury conditions by disrupting DNA-PKcs/Fis1-dependent mitochondrial fission, ultimately improving cardiac function. These findings suggest new approaches for clinical intervention in patients with MIRI.

Mtfp1 ablation enhances mitochondrial respiration and protects against hepatic steatosis

Hepatic steatosis is the result of imbalanced nutrient delivery and metabolism in the liver and is the first hallmark of Metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is the most common chronic liver disease and involves the accumulation of excess lipids in hepatocytes, inflammation, and cancer. Mitochondria play central roles in liver metabolism yet the specific mitochondrial functions causally linked to MASLD remain unclear. Here, we identify Mitochondrial Fission Process 1 protein (MTFP1) as a key regulator of mitochondrial and metabolic activity in the liver. Deletion of Mtfp1 in hepatocytes is physiologically benign in mice yet leads to the upregulation of oxidative phosphorylation (OXPHOS) activity and mitochondrial respiration, independently of mitochondrial biogenesis. Consequently, liver-specific knockout mice are protected against high fat diet-induced steatosis and metabolic dysregulation. Additionally, Mtfp1 deletion inhibits mitochondrial permeability transition pore opening in hepatocytes, conferring protection against apoptotic liver damage in vivo and ex vivo. Our work uncovers additional functions of MTFP1 in the liver, positioning this gene as an unexpected regulator of OXPHOS and a therapeutic candidate for MASLD.

The role of mitochondrial dynamics in disease

Mitochondria are multifaceted and dynamic organelles regulating various important cellular processes from signal transduction to determining cell fate. As dynamic properties of mitochondria, fusion and fission accompanied with mitophagy, undergo constant changes in number and morphology to sustain mitochondrial homeostasis in response to cell context changes. Thus, the dysregulation of mitochondrial dynamics and mitophagy is unsurprisingly related with various diseases, but the unclear underlying mechanism hinders their clinical application. In this review, we summarize the recent developments in the molecular mechanism of mitochondrial dynamics and mitophagy, particularly the different roles of key components in mitochondrial dynamics in different context. We also summarize the roles of mitochondrial dynamics and target treatment in diseases related to the cardiovascular system, nervous system, respiratory system, and tumor cell metabolism demanding high-energy. In these diseases, it is common that excessive mitochondrial fission is dominant and accompanied by impaired fusion and mitophagy. But there have been many conflicting findings about them recently, which are specifically highlighted in this view. We look forward that these findings will help broaden our understanding of the roles of the mitochondrial dynamics in diseases and will be beneficial to the discovery of novel selective therapeutic targets.

Cardioprotective effects of Moku-boi-to and its impact on AngII-induced cardiomyocyte hypertrophy

Cardiomyocyte hypertrophy, induced by elevated levels of angiotensin II (AngII), plays a crucial role in cardiovascular diseases. Current therapeutic approaches aim to regress cardiac hypertrophy but have limited efficacy. Widely used Japanese Kampo medicines are highly safe and potential therapeutic agents. This study aims to explore the impact and mechanisms by which Moku-boi-to (MBT), a Japanese Kampo medicine, exerts its potential cardioprotective benefits against AngII-induced cardiomyocyte hypertrophy, bridging the knowledge gap and contributing to the development of novel therapeutic strategies. By evaluating the effects of six Japanese Kampo medicines with known cardiovascular efficiency on AngII-induced cardiomyocyte hypertrophy and cell death, we identified MBT as a promising candidate. MBT exhibited preventive effects against AngII-induced cardiomyocyte hypertrophy, cell death and demonstrated improvements in intracellular Ca2+ signaling regulation, ROS production, and mitochondrial function. Unexpectedly, experiments combining MBT with the AT1 receptor antagonist losartan suggested that MBT may target the AT1 receptor. In an isoproterenol-induced heart failure mouse model, MBT treatment demonstrated significant effects on cardiac function and hypertrophy. These findings highlight the cardioprotective potential of MBT through AT1 receptor-mediated mechanisms, offering valuable insights into its efficacy in alleviating AngII-induced dysfunction in cardiomyocytes. The study suggests that MBT holds promise as a safe and effective prophylactic agent for cardiac hypertrophy, providing a deeper understanding of its mechanisms for cardioprotection against AngII-induced dysfunction.

Novel insights into the involvement of mitochondrial fission/fusion in heart failure: From molecular mechanisms to targeted therapies

Mitochondria are dynamic organelles that alter their morphology through fission (fragmentation) and fusion (elongation). These morphological changes correlate highly with mitochondrial functional adaptations to stressors, such as hypoxia, pressure overload, and inflammation, and are important in the setting of heart failure. Pathological mitochondrial remodeling, characterized by increased fission and reduced fusion, is associated with impaired mitochondrial respiration, increased mitochondrial oxidative stress, abnormal cytoplasmic calcium handling, and increased cardiomyocyte apoptosis. Considering the impact of the mitochondrial morphology on mitochondrial behavior and cardiomyocyte performance, altered mitochondrial dynamics could be expected to induce or exacerbate the pathogenesis and progression of heart failure. However, whether alterations in mitochondrial fission and fusion accelerate or retard the progression of heart failure has been the subject of intense debate. In this review, we first describe the physiological processes and regulatory mechanisms of mitochondrial fission and fusion. Then, we extensively discuss the pathological contributions of mitochondrial fission and fusion to heart failure. Lastly, we examine potential therapeutic approaches targeting mitochondrial fission/fusion to treat patients with heart failure.