ndufa7 plays a critical role in cardiac hypertrophy

Circulating B Cell-Derived Small RNA Delivered by Extracellular Vesicles: A Dialogue Mechanism for Long-Range Targeted Renal Mitochondrial Injury in Obesity

The intricate processes that govern the interactions between peripatetic immune cells and distal renal injury in obesity are not fully understood. Employing transcriptomic analysis of circulating extracellular vesicles (EVs), a marked amplification of small RNA (miR-3960) is discerned within CD3-CD19+ B cells. This RNA is found to be preferentially augmented in kidney tissues, contrasting with its subdued expression in other organs. By synthesizing dual-luciferase reporter assay with co-immunoprecipitation analysis, it is pinpointed that miR-3960 specifically targets the nuclear gene TRMT5, a pivotal actor in the methylation of mitochondrial tRNA. This liaison instigates aberrations in the post-transcriptional modifications of mitochondrial tRNA, engendering deficiencies within the electron respiratory chain, primarily attributable to the diminution of the mitochondrial bioenergetic compound (NDUFA7) complex I. Such perturbations lead to a compromised mitochondrial respiratory capacity in renal tubular cells, thereby exacerbating tubular injury. In contrast, EV blockade or miR-3960 depletion markedly alleviates renal tubular injury in obesity. This investigation unveils a hitherto unexplored pathway by which obesity-induced circulating immune cells remotely manipulate mitochondrial metabolism in target organs. The strategic targeting of obese EVs or infiltrative immune cells and their specifically secreted RNAs emerges as a promising therapeutic avenue to forestall obesity-related renal afflictions.

Hhatl ameliorates endoplasmic reticulum stress through autophagy by associating with LC3

Endoplasmic reticulum (ER) stress, a common cellular stress response induced by various factors that interfere with cellular homeostasis, may trigger cell apoptosis. Autophagy is an important and conserved mechanism for eliminating aggregated proteins and maintaining protein stability of cells, which is closely associated with ER stress and ER stress-induced apoptosis. In this paper, we report for the first time that Hhatl, an ER-resident protein, is downregulated in response to ER stress. Hhatl overexpression alleviated ER stress and ER stress induced apoptosis in cells treated with tunicamycin or thapsigargin, whereas Hhatl knockdown exacerbated ER stress and apoptosis. Further study showed that Hhatl attenuates ER stress by promoting autophagic flux. Mechanistically, we found that Hhatl promotes autophagy by associating with autophagic protein LC3 (microtubule-associated protein 1A/1B-light chain 3) via the conserved LC3-interacting region motif. Noticeably, the LC3-interacting region motif was essential for Hhatl-regulated promotion of autophagy and reduction of ER stress. These findings demonstrate that Hhatl ameliorates ER stress via autophagy activation by interacting with LC3, thereby alleviating cellular pressure. The study indicates that pharmacological or genetic regulation of Hhatl-autophagy signaling might be potential for mediating ER stress and related diseases.

Novel insights into small open reading frame-encoded micropeptides in hepatocellular carcinoma: A potential breakthrough

Traditionally, non-coding RNAs (ncRNAs) are regarded as a class of RNA transcripts that lack encoding capability; however, advancements in technology have revealed that some ncRNAs contain small open reading frames (sORFs) that are capable of encoding micropeptides of approximately 150 amino acids in length. sORF-encoded micropeptides (SEPs) have emerged as intriguing entities in hepatocellular carcinoma (HCC) research, shedding light on this previously unexplored realm. Recent studies have highlighted the regulatory functions of SEPs in the occurrence and progression of HCC. Some SEPs exhibit inhibitory effects on HCC, but others facilitate its development. This discovery has revolutionized the landscape of HCC research and clinical management. Here, we introduce the concept and characteristics of SEPs, summarize their associations with HCC, and elucidate their carcinogenic mechanisms in HCC metabolism, signaling pathways, cell proliferation, and metastasis. In addition, we propose a step-by-step workflow for the investigation of HCC-associated SEPs. Lastly, we discuss the challenges and prospects of applying SEPs in the diagnosis and treatment of HCC. This review aims to facilitate the discovery, optimization, and clinical application of HCC-related SEPs, inspiring the development of early diagnostic, individualized, and precision therapeutic strategies for HCC.

Zebrafish: A smart tool for heart disease research

The increasing prevalence of heart disease poses a significant threat to human survival and safety. However, the current treatments available for heart disease are quite limited. Therefore, it is of great importance to utilize suitable animal models that can accurately simulate the physiological characteristics of heart disease. This would help improve our understanding of this disease and aid in the development of new treatment methods and drugs. Zebrafish hearts not only exhibit similarities to mammalian hearts, but they also share ~70% of homologous genes with humans. Utilizing zebrafish as an alternative to costly and time-consuming mammalian models offers numerous advantages. Zebrafish models can be easily established and maintained, and compound screening and genetic methods allow for the creation of various economical and easily controlled zebrafish and zebrafish embryonic heart disease models in a short period of time. Consequently, zebrafish have become a powerful tool for exploring the pathological mechanisms of heart disease and identifying new effective genes. In this review, we summarize recent studies on different zebrafish models of heart disease. We also describe the techniques and protocols used to develop zebrafish models of myocardial infarction, heart failure, and congenital heart disease, including surgical procedures, forward and reverse genetics, as well as drug and combination screening. This review aims to promote the utilization of zebrafish models in investigating diverse pathological mechanisms of heart disease, enhancing our knowledge and comprehension of heart disease, and offering novel insights and objectives for exploring the prevention and treatment of heart disease.

Mitochondrial heterogeneity in diseases

As key organelles involved in cellular metabolism, mitochondria frequently undergo adaptive changes in morphology, components and functions in response to various environmental stresses and cellular demands. Previous studies of mitochondria research have gradually evolved, from focusing on morphological change analysis to systematic multiomics, thereby revealing the mitochondrial variation between cells or within the mitochondrial population within a single cell. The phenomenon of mitochondrial variation features is defined as mitochondrial heterogeneity. Moreover, mitochondrial heterogeneity has been reported to influence a variety of physiological processes, including tissue homeostasis, tissue repair, immunoregulation, and tumor progression. Here, we comprehensively review the mitochondrial heterogeneity in different tissues under pathological states, involving variant features of mitochondrial DNA, RNA, protein and lipid components. Then, the mechanisms that contribute to mitochondrial heterogeneity are also summarized, such as the mutation of the mitochondrial genome and the import of mitochondrial proteins that result in the heterogeneity of mitochondrial DNA and protein components. Additionally, multiple perspectives are investigated to better comprehend the mysteries of mitochondrial heterogeneity between cells. Finally, we summarize the prospective mitochondrial heterogeneity-targeting therapies in terms of alleviating mitochondrial oxidative damage, reducing mitochondrial carbon stress and enhancing mitochondrial biogenesis to relieve various pathological conditions. The possibility of recent technological advances in targeted mitochondrial gene editing is also discussed.

Mitochondrial Dysfunction in Cardiac Diseases and Therapeutic Strategies

Mitochondria are the main site of intracellular synthesis of ATP, which provides energy for various physiological activities of the cell. Cardiomyocytes have a high density of mitochondria and mitochondrial damage is present in a variety of cardiovascular diseases. In this paper, we describe mitochondrial damage in mitochondrial cardiomyopathy, congenital heart disease, coronary heart disease, myocardial ischemia-reperfusion injury, heart failure, and drug-induced cardiotoxicity, in the context of the key roles of mitochondria in cardiac development and homeostasis. Finally, we discuss the main current therapeutic strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction, including pharmacological strategies, gene therapy, mitochondrial replacement therapy, and mitochondrial transplantation. It is hoped that this will provide new ideas for the treatment of cardiovascular diseases.

Trim65 attenuates isoproterenol-induced cardiac hypertrophy by promoting autophagy and ameliorating mitochondrial dysfunction via the Jak1/Stat1 signaling pathway

Pathological cardiac hypertrophy is a major cause of heart failure, and there is no effective approach for its prevention or treatment. The Trim family is a recently identified family of E3 ubiquitin ligases that regulate cardiac hypertrophy. Trim65, which is a memberof the Trim family, previous studies have not determined whether Trim65 affects cardiac hypertrophy. In this study, the effects of Trim65 on isoproterenol (ISO)-induced cardiac hypertrophy and the underlying mechanisms were investigated. In contrast to C57BL/6 mice, Trim65-knockout (Trim65-KO) mice developed more severe myocardial hypertrophy, fibrosis and cardiac dysfunction after being intraperitoneally injected with ISO for 2 weeks. Transmission electron microscopy (TEM) revealed that the autophagic flux was inhibited, mitochondria were swollen, and mitochondrial cristae were lost or decreased in the myocardium of Trim65-KO mice. In vitro studies demonstrated that overexpression of Trim65 inhibited ISO-induced cardiomyocyte hypertrophy by increasing mitochondrial density and membrane potential, and the Stat1 inhibitor fludarabine attenuated the effect of Trim65 knockdown on ISO-induced cardiomyocyte hypertrophy by reducing Reactive oxygen species (ROS) production and increasing the mitochondrial density and membrane potential. Our findings provide the first link between Trim65 and mitochondria, and we found for the first time that Trim65 inhibits mitochondria-dependent apoptosis and autophagy via the Jak1/Stat1 signalling pathway, ultimately attenuating ISO-induced cardiac hypertrophy; this effect of Trim65 might be mediated via the regulation of Jak1 ubiquitination. Taking these findings together, we suggest that genes that are related to mitochondria-dependent apoptosis and that are associated with Trim65 could be promising therapeutic targets for cardiac hypertrophy.

Mitochondria-associated endoplasmic reticulum membranes (MAMs): Possible therapeutic targets in heart failure

Mitochondria-associated endoplasmic reticulum membranes (MAMs) are formed by physical connections of the endoplasmic reticulum and mitochondria. Over the past decades, great breakthroughs have been made in the study of ER-mitochondria communications. It has been identified that MAM compartments are pivotal in regulating neurological function. Accumulating studies indicated that MAMs participate in the development of cardiovascular diseases. However, the specific role of MAMs in heart failure remains to be fully understood. In this article, we first summarize the structural and functional properties of MAM and MAM-associated proteins. We then focus on the roles of MAMs in myocardial infarction, cardiomyopathy and heart failure, and discuss the involvement of MAMs in disease progression and treatment. Elucidating these issues may provide important insights into therapeutic intervention of heart failure.

Respirasome Proteins Are Regulated by Sex-Hormone Interactions in the Brain

The existence of sex differences in disease incidence is attributed, in part, to sex differences in metabolism. Uncovering the precise mechanism driving these differences is an extraordinarily complex process influenced by genetics, endogenous hormones, sex-specific lifetime events, individual differences and external environmental/social factors. In fact, such differences may be subtle, but across a life span, increase susceptibility to a pathology. Whilst research persists in the hope of discovering an elegant biological mechanism to underpin sex differences in disease, here, we show, for the first time, that such a mechanism may be subtle in nature but influenced by multiple sex-specific factors. A proteomic dataset was generated from a gonadectomized mouse model treated with Tibolone, a menopausal hormone therapy. Following functional enrichment analysis, we identified that Alzheimer's disease and the electron transport chain-associated pathways were regulated by sex-hormone interactions. Specifically, we identified that the expression of three respirasome proteins, NDUFA2, NDUFA7 and UQCR10, is significantly altered by compounding factors that contribute to sex differences. These proteins function in bioenergetics and produce reactive oxygen species, which are each dysregulated in many diseases with sex differences in incidence. We show sex-specific reprogrammed responses to Tibolone following gonadectomy, which primarily influence the expression of proteins contributing to metabolic pathways. This further infers that metabolic differences may underpin the observed sex differences in disease, but also that hormone therapy research now has potential in exploring sex-specific interventions to produce an effective method of prevention or treatment.

Mitochondrial Cardiomyopathy: Molecular Epidemiology, Diagnosis, Models, and Therapeutic Management

Mitochondrial cardiomyopathy (MCM) is characterized by abnormal heart-muscle structure and function, caused by mutations in the nuclear genome or mitochondrial DNA. The heterogeneity of gene mutations and various clinical presentations in patients with cardiomyopathy make its diagnosis, molecular mechanism, and therapeutics great challenges. This review describes the molecular epidemiology of MCM and its clinical features, reviews the promising diagnostic tests applied for mitochondrial diseases and cardiomyopathies, and details the animal and cellular models used for modeling cardiomyopathy and to investigate disease pathogenesis in a controlled in vitro environment. It also discusses the emerging therapeutics tested in pre-clinical and clinical studies of cardiac regeneration.

Genomes of Two Flying Squid Species Provide Novel Sights into Adaptations of Cephalopods to Pelagic Life

Pelagic cephalopods have evolved a series of fascinating traits, such as excellent visual acuity, high-speed agility, and photophores for adaptation to open pelagic oceans. However, the genetic mechanisms underpinning these traits are not well understood. Thus, in this study, we obtained high-quality genomes of two purpleback flying squid species (Sthenoteuthis oualaniensis and Sthenoteuthis sp.), with sizes of 5450 Mb and 5651 Mb, respectively. Comparative genomic analyses revealed that the S-crystallin subfamily SL20-1 associated with visual acuity in the purpleback flying squid lineage was significantly expanded, and the evolution of high-speed agility for the species was accompanied by significant positive selection pressure on genes related to energy metabolism. These molecular signals might have contributed to the evolution of their adaptative predatory and anti-predatory traits. In addition, the transcriptomic analysis provided clear indications of the evolution of the photophores of purpleback flying squids, especially the recruitment of new genes and energy metabolism-related genes which may have played key functional roles in the process.

The interconnections between the microtubules and mitochondrial networks in cardiocerebrovascular diseases: Implications for therapy

Microtubules, a highly dynamic cytoskeleton, participate in many cellular activities including mechanical support, organelles interactions, and intracellular trafficking. Microtubule organization can be regulated by modification of tubulin subunits, microtubule-associated proteins (MAPs) or agents modulating microtubule assembly. Increasing studies demonstrate that microtubule disorganization correlates with various cardiocerebrovascular diseases including heart failure and ischemic stroke. Microtubules also mediate intracellular transport as well as intercellular transfer of mitochondria, a power house in cells which produce ATP for various physiological activities such as cardiac mechanical function. It is known to all that both microtubules and mitochondria participate in the progression of cancer and Parkinson's disease. However, the interconnections between the microtubules and mitochondrial networks in cardiocerebrovascular diseases remain unclear. In this paper, we will focus on the roles of microtubules in cardiocerebrovascular diseases, and discuss the interplay of mitochondria and microtubules in disease development and treatment. Elucidation of these issues might provide significant diagnostic value as well as potential targets for cardiocerebrovascular diseases.

The intra-mitochondrial O-GlcNAcylation system rapidly modulates OXPHOS function and ROS release in the heart

Protein O-GlcNAcylation is increasingly recognized as an important cellular regulatory mechanism, in multiple organs including the heart. However, the mechanisms leading to O-GlcNAcylation in mitochondria and the consequences on their function remain poorly understood. In this study, we use an in vitro reconstitution assay to characterize the intra-mitochondrial O-GlcNAc system without potential cytoplasmic confounding effects. We compare the O-GlcNAcylome of isolated cardiac mitochondria with that of mitochondria acutely exposed to NButGT, a specific inhibitor of glycoside hydrolase. Amongst the 409 O-GlcNAcylated mitochondrial proteins identified, 191 display increased O-GlcNAcylation in response to NButGT. This is associated with enhanced Complex I (CI) activity, increased maximal respiration in presence of pyruvate-malate, and a striking reduction of mitochondrial ROS release, which could be related to O-GlcNAcylation of specific subunits of ETC complexes (CI, CIII) and TCA cycle enzymes. In conclusion, our work underlines the existence of a dynamic mitochondrial O-GlcNAcylation system capable of rapidly modifying mitochondrial function.

An in vitro assay in isolated heart mitochondria reveals that O-GlcNAcase inhibitor NButGT rapidly increases protein O-GlcNAcylation leading to increased respiratory capacity and complex I activity and decreased ROS release.

miR-731 modulates the zebrafish heart morphogenesis via targeting Calcineurin/Nfatc3a pathway

BACKGROUND

Zebrafish miR-731 is orthologous of human miR-425, which has been demonstrated to have cardio-protective roles by a variety of mechanisms. The miR-731 morphants show pericardium enlargement, and many DEGs (differentially expressed genes) are enriched in 'Cardiac muscle contraction' and 'Calcium signaling pathway', implying that miR-731 plays a potential role in heart function and development. However，the in vivo physiological role of miR-731 in the heart needs to be fully defined.

METHODS

Zebrafish miR-731 morphants were generated by morpholino knockdown, and miR-731 knockout zebrafish was generated by CRISRP/Cas9. We observed cardiac morphogenesis based on whole-mount in situ hybridization. Furthermore, RNA-seq and qRT-PCR were used to elucidate the molecular mechanism and analyze the gene expression. Double luciferase verification and Western blot were used to verify the target gene.

RESULTS

The depletion of miR-731 in zebrafish embryos caused the deficiency of cardiac development and function, which was associated with reduced heart rate, ventricular enlargement and heart looping disorder. In addition, mechanistic study demonstrated that Calcineurin/Nfatc3a signaling involved in miR-731 depletion induced abnormal cardiac function and developmental defects.

CONCLUSION

MiR-731 regulates cardiac function and morphogenesis through Calcineurin/Nfatc3a signaling.

GENERAL SIGNIFICANCE

Our studies highlight the potential importance of miR-731 in cardiac development.

Downregulation of a mitochondrial micropeptide, MPM, promotes hepatoma metastasis by enhancing mitochondrial complex I activity

We and others have shown that MPM (micropeptide in mitochondria) regulates myogenic differentiation and muscle development. However, the roles of MPM in cancer development remain unknown. Here we revealed that MPM was downregulated significantly in human hepatocellular carcinoma (HCC) tissues and its decrease was associated with increased metastasis potential and HCC recurrence. Gain- and loss-of-function investigations disclosed that in vitro migration/invasion and in vivo liver/lung metastasis of hepatoma cells were repressed by restoring MPM expression and increased by silencing MPM. Mechanism investigations revealed that MPM interacted with NDUFA7. Mitochondrial complex I activity was inhibited by overexpressing MPM and enhanced by siMPM, and this effect of siMPM was attenuated by knocking down NDUFA7. The NAD⁺/NADH ratio, which was regulated by complex I, was reduced by MPM but increased by siMPM. Treatment with the NAD⁺ precursor nicotinamide abrogated the inhibitory effect of MPM on hepatoma cell migration. Further investigations showed that miR-17-5p bound to MPM and inhibited MPM expression. miR-17-5p upregulation was associated with MPM downregulation in HCC tissues. These findings indicate that a decrease in MPM expression may promote hepatoma metastasis by increasing mitochondrial complex I activity and the NAD⁺/NADH ratio.

The Mysterious Multitude: Structural Perspective on the Accessory Subunits of Respiratory Complex I

Complex I (CI) is the largest protein complex in the mitochondrial oxidative phosphorylation electron transport chain of the inner mitochondrial membrane and plays a key role in the transport of electrons from reduced substrates to molecular oxygen. CI is composed of 14 core subunits that are conserved across species and an increasing number of accessory subunits from bacteria to mammals. The fact that adding accessory subunits incurs costs of protein production and import suggests that these subunits play important physiological roles. Accordingly, knockout studies have demonstrated that accessory subunits are essential for CI assembly and function. Furthermore, clinical studies have shown that amino acid substitutions in accessory subunits lead to several debilitating and fatal CI deficiencies. Nevertheless, the specific roles of CI’s accessory subunits have remained mysterious. In this review, we explore the possible roles of each of mammalian CI’s 31 accessory subunits by integrating recent high-resolution CI structures with knockout, assembly, and clinical studies. Thus, we develop a framework of experimentally testable hypotheses for the function of the accessory subunits. We believe that this framework will provide inroads towards the complete understanding of mitochondrial CI physiology and help to develop strategies for the treatment of CI deficiencies.

Zebrafish Heart Failure Models

Heart failure causes significant morbidity and mortality worldwide. The understanding of heart failure pathomechanisms and options for treatment remain incomplete. Zebrafish has proven useful for modeling human heart diseases due to similarity of zebrafish and mammalian hearts, fast easily tractable development, and readily available genetic methods. Embryonic cardiac development is rapid and cardiac function is easy to observe and quantify. Reverse genetics, by using morpholinos and CRISPR-Cas9 to modulate gene function, make zebrafish a primary animal model for in vivo studies of candidate genes. Zebrafish are able to effectively regenerate their hearts following injury. However, less attention has been given to using zebrafish models to increase understanding of heart failure and cardiac remodeling, including cardiac hypertrophy and hyperplasia. Here we discuss using zebrafish to study heart failure and cardiac remodeling, and review zebrafish genetic, drug-induced and other heart failure models, discussing the advantages and weaknesses of using zebrafish to model human heart disease. Using zebrafish models will lead to insights on the pathomechanisms of heart failure, with the aim to ultimately provide novel therapies for the prevention and treatment of heart failure.

The protective effect of isosteviol sodium on cardiac function and myocardial remodelling in transverse aortic constriction rat

Pathological hypertrophy contributes to heart failure and there is not quite effective treatment to invert this process. Isosteviol has been shown to protect the heart against ischaemia-reperfusion injury and isoproterenol-induced cardiac hypertrophy, but its effect on pressure overload-induced cardiac hypertrophy is still unknown. Pressure overload induced by transverse aortic constriction (TAC) causes cardiac hypertrophy in rats to mimic the pathological condition in human. This study examined the effects of isosteviol sodium (STVNa) on cardiac hypertrophy by the TAC model and cellular assays in vitro. Cardiac function test, electrocardiogram analysis and histological analysis were conducted. The effects of STVNa on calcium transient of the adult rat ventricular cells and the proliferation of neonatal rat cardiac fibroblasts were also studied in vitro. Cardiac hypertrophy was observed after 3-week TAC while the extensive cardiac dysfunction and electronic remodelling were observed after 9-week TAC. Both STVNa and sildenafil (positive drug) treatment reversed the two process, but STVNa appeared to be more superior in some aspects and did not change calcium transient considerably. STVNa also reversed TAC-induced cardiac fibrosis in vivo and TGF-β1-induced fibroblast proliferation in vitro. Moreover, STVNa, but not sildenafil, reversed impairment of the autonomic nervous system induced by 9-week TAC.