FTO overexpression inhibits apoptosis of hypoxia/reoxygenation-treated myocardial cells by regulating m6A modification of Mhrt

M6A modification in cardiovascular disease: With a focus on programmed cell death

N6-methyladenosine (m6A) methylation is one of the most predominant internal RNA modifications in eukaryotes and has become a hot spot in the field of epigenetics in recent years. Cardiovascular diseases (CVDs) are a leading cause of death globally. Emerging evidence demonstrates that RNA modifications, such as the m6A modification, are associated with the development and progression of many diseases, including CVDs. An increasing body of studies has indicated that programmed cell death (PCD) plays a vital role in CVDs. However, the molecular mechanisms underlying m6A modification and PCD in CVDs remain poorly understood. Herein, elaborating on the highly complex connections between the m6A mechanisms and different PCD signaling pathways and clarifying the exact molecular mechanism of m6A modification mediating PCD have significant meaning in developing new strategies for the prevention and therapy of CVDs. There is great potential for clinical application.

Xinyang tablet alleviated cardiac dysfunction in a cardiac pressure overload model by regulating the receptor-interacting serum/three-protein kinase 3/FUN14 domain containing 1-mediated mitochondrial unfolded protein response and mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Xinyang tablet (XYT) has been used for heart failure (HF) for over twenty years in clinical practice, but the underlying molecular mechanism remains poorly understood.

AIMS OF THE STUDY

In the present study, we aimed to explore the protective effects of XYT in HF in vivo and in vitro.

MATERIALS AND METHODS

Transverse aortic constriction was performed in vivo to establish a mouse model of cardiac pressure overload. Echocardiography, tissue staining, and real-time quantitative PCR (qPCR) were examined to evaluate the protective effects of XYT on cardiac function and structure. Adenosine 5'-triphosphate production, reactive oxygen species staining, and measurement of malondialdehyde and superoxide dismutase was used to detect mitochondrial damage. Mitochondrial ultrastructure was observed by transmission electron microscope. Immunofluorescence staining, qPCR, and Western blotting were performed to evaluate the effect of XYT on the mitochondrial unfolded protein response and mitophagy, and to identify its potential pharmacological mechanism. In vitro, HL-1 cells and neonatal mouse cardiomyocytes were stimulated with Angiotensin II to establish the cell model. Western blotting, qPCR, immunofluorescence staining, and flow cytometry were utilized to determine the effects of XYT on cardiomyocytes. HL-1 cells overexpressing receptor-interacting serum/three-protein kinase 3 (RIPK3) were generated by transfection of RIPK3-overexpressing lentiviral vectors. Cells were then co-treated with XYT to determine the molecular mechanisms.

RESULTS

In the present study, XYT was found to exerta protective effect on cardiac function and structure in the pressure overload mice. And it was also found XYT reduced mitochondrial damage by enhancing mitochondrial unfolded protein response and restoring mitophagy. Further studies showed that XYT achieved its cardioprotective role through regulating the RIPK3/FUN14 domain containing 1 (FUNDC1) signaling. Moreover, the overexpression of RIPK3 successfully reversed the XYT-induced protective effects and significantly attenuated the positive effects on the mitochondrial unfolded protein response and mitophagy.

CONCLUSIONS

Our findings indicated that XYT prevented pressure overload-induced HF through regulating the RIPK3/FUNDC1-mediated mitochondrial unfolded protein response and mitophagy. The information gained from this study provides a potential strategy for attenuating mitochondrial damage in the context of pressure overload-induced heart failure using XYT.

m6A control programmed cell death in cardiac fibrosis

N6-methyladenosine (m6A) modification is closely related to cardiac fibrosis. As the most common and abundant form of mRNA modification in eukaryotes, m6A is deposited by methylases ("writers"), recognized and effected by RNA-binding proteins ("readers"), and removed by demethylases ("erasers"), achieving highly dynamic reversibility. m6A modification is involved in regulating the entire biological process of target RNA, including transcription, processing and splicing, export from the nucleus to the cytoplasm, and enhancement or reduction of stability and translation. Programmed cell death (PCD) comprises many forms and pathways, with apoptosis and autophagy being the most common. Other forms include pyroptosis, ferroptosis, necroptosis, mitochondrial permeability transition (MPT)-dependent necrosis, and parthanatos. In recent years, increasing evidence suggests that m6A modification can mediate PCD, affecting cardiac fibrosis. Since the correlation between some PCD types and m6A modification is not yet clear, this article mainly introduces the relationship between four common PCD types (apoptosis, autophagy, pyroptosis, and ferroptosis) and m6A modification, as well as their role and influence in cardiac fibrosis.

Integrated analysis of differentially m6A modified and expressed lncRNAs for biomarker identification in coronary artery disease

N6-methyladenosine (m6A) is the most prevalent internal RNA modification in mammals. However, limited research has been conducted on the role of m6A in coronary artery disease (CAD). We conducted methylated RNA immunoprecipitation sequencing and RNA sequencing to obtain a genome-wide profile of m6A-modified long noncoding RNAs (lncRNAs) in human coronary artery smooth muscle cells either exposed to oxidized low-density lipoprotein treatment or not, and the characteristics of the expression profiles were explored using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. The predictive effects of seven selected lncRNAs on CAD were evaluated in peripheral blood mononuclear cells (PBMCs). The differentially m6A-modified and expressed lncRNAs related genes were predominantly enriched in small GTPase-mediated signal transduction, ErbB signaling, and Rap1 signaling. Additionally, the expression levels of uc003pes.1, ENST00000422847, and NR_110155 were significantly associated with CAD, with uc003pes.1 identified as an independent risk factor and NR_110155 as an independent protective factor for CAD. NR_110155 and uc003pes.1 in PBMCs have the potential to serve as biomarkers for predicting CAD.

Unravelling the impact of RNA methylation genetic and epigenetic machinery in the treatment of cardiomyopathy

Cardiomyopathy (CM) represents a heterogeneous group of diseases primarily affecting cardiac structure and function, with genetic and epigenetic dysregulation playing a pivotal role in its pathogenesis. Emerging evidence from the burgeoning field of epitranscriptomics has brought to light the significant impact of various RNA modifications, notably N6-methyladenosine (m6A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N1-methyladenosine (m1A), 2'-O-methylation (Nm), and 6,2'-O-dimethyladenosine (m6Am), on cardiomyocyte function and the broader processes of cardiac and vascular remodelling. These modifications have been shown to influence key pathological mechanisms including mitochondrial dysfunction, oxidative stress, cardiomyocyte apoptosis, inflammation, immune response, and myocardial fibrosis. Importantly, aberrations in the RNA methylation machinery have been observed in human CM cases and animal models, highlighting the critical role of RNA methylating enzymes and their potential as therapeutic targets or biomarkers for CM. This review underscores the necessity for a deeper understanding of RNA methylation processes in the context of CM, to illuminate novel therapeutic avenues and diagnostic tools, thereby addressing a significant gap in the current management strategies for this complex disease.

N6-Methyladenosine Methylation of mRNA in Cell Apoptosis

Apoptosis, a highly controlled homeostatic mechanism that eliminates single cells without destroying tissue function, occurs during growing development and senescence. N6-methyladenosine (m6A), as the most common internal modification of eukaryotic mRNA, fine-tunes gene expression by regulating many aspects of mRNA metabolism, such as splicing, nucleation, stability, translation, and degradation. Remarkably, recent reports have indicated that aberrant methylation of m6A-related RNA may directly or indirectly influence the expression of apoptosis-related genes, thus regulating the process of cell apoptosis. In this review, we summarized the relationship between m6A modification and cell apoptosis, especially its role in the nervous system, and analyzed the limitations of the current research.

Increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress

N6-methyladenosine (m6A) RNA modification is a new epigenetic molecular mechanism involved in various biological or pathological processes. Exposure to aluminum (Al) has been considered to promote neuronal apoptosis resulting in cognitive dysfunction, yet whether m6A modification participates in the underlying mechanism remains largely unknown. Here, rats exposed to aluminum-maltolate [Al(mal)3] for 90 days showed impaired learning and memory function and elevated apoptosis, which were related to the increased m6A level and decreased fat mass and obesity-associated protein (FTO, an m6A demethylase) in the hippocampus. Accordingly, similar results presented in PC12 cells following Al(mal)3 treatment and FTO overexpression relieved the increased apoptosis and m6A level in vitro. Next, we identified brain-derived neurotrophic factor (BDNF) as the functional downstream target of FTO in a m6A-dependent manner. Furthermore, it was found that as the onset of aluminum neurotoxicity, oxidative stress may be the upstream regulator of FTO in aluminum-induced apoptosis. Taken together, these results suggest that increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress.

m6A epitranscriptomic and epigenetic crosstalk in cardiac fibrosis

Cardiac fibrosis, a crucial pathological characteristic of various cardiac diseases, presents a significant treatment challenge. It involves the deposition of the extracellular matrix (ECM) and is influenced by genetic and epigenetic factors. Prior investigations have predominantly centered on delineating the substantial influence of epigenetic and epitranscriptomic mechanisms in driving the progression of fibrosis. Recent studies have illuminated additional avenues for modulating the progression of fibrosis, offering potential solutions to the challenging issues surrounding fibrosis treatment. In the context of cardiac fibrosis, an intricate interplay exists between m6A epitranscriptomic and epigenetics. This interplay governs various pathophysiological processes: mitochondrial dysfunction, mitochondrial fission, oxidative stress, autophagy, apoptosis, pyroptosis, ferroptosis, cell fate switching, and cell differentiation, all of which affect the advancement of cardiac fibrosis. In this comprehensive review, we meticulously analyze pertinent studies, emphasizing the interplay between m6A epitranscriptomics and partial epigenetics (including histone modifications and noncoding RNA), aiming to provide novel insights for cardiac fibrosis treatment.

Epitranscriptomic regulation in fasting hearts: implications for cardiac health

Cardiac tolerance to ischaemia can be increased by dietary interventions such as fasting, which is associated with significant changes in myocardial gene expression. Among the possible mechanisms of how gene expression may be altered are epigenetic modifications of RNA - epitranscriptomics. N6-methyladenosine (m6A) and N6,2'-O-dimethyladenosine (m6Am) are two of the most prevalent modifications in mRNA. These methylations are reversible and regulated by proteins called writers, erasers, readers, and m6A-repelled proteins. We analysed 33 of these epitranscriptomic regulators in rat hearts after cardioprotective 3-day fasting using RT-qPCR, Western blot, and targeted proteomic analysis. We found that the most of these regulators were changed on mRNA or protein levels in fasting hearts, including up-regulation of both demethylases - FTO and ALKBH5. In accordance, decreased methylation (m6A+m6Am) levels were detected in cardiac total RNA after fasting. We also identified altered methylation levels in Nox4 and Hdac1 transcripts, both of which play a role in the cytoprotective action of ketone bodies produced during fasting. Furthermore, we investigated the impact of inhibiting demethylases ALKBH5 and FTO in adult rat primary cardiomyocytes (AVCMs). Our findings indicate that inhibiting these demethylases reduced the hypoxic tolerance of AVCMs isolated from fasting rats. This study showed that the complex epitranscriptomic machinery around m6A and m6Am modifications is regulated in the fasting hearts and might play an important role in cardiac adaptation to fasting, a well-known cardioprotective intervention.

The association and application of sonodynamic therapy and autophagy in diseases

Sonodynamic therapy (SDT) is a new non-invasive treatment method proposed based on photodynamic therapy (PDT). It has advantages such as high precision, strong tissue penetration, minimal side effects, and good patient compliance. With the maturation of nanomedicine, the application of nanosonosensitizers has further propelled the development of SDT. In recent years, people have developed many new types of sonosensitizers and explored the mechanisms of SDT. Among them, the studies about the relationship between autophagy and SDT have attracted increasing attention. After the SDT, cells usually undergo autophagy as a self-protective mechanism to resist external stimuli and reduce cell damage, which is beneficial for the treatment of atherosclerosis (AS), diabetes, and myocardial infarction but counterproductive in cancer treatment. However, under certain treatment conditions, excessive upregulation of autophagy can also promote cell death, which is beneficial for cancer treatment. This article reviews the latest research progress on the relationship between SDT and autophagy in cancers, AS, diabetes, and myocardial infarction. We also discuss and propose the challenges and prospects in enhancing SDT efficacy by regulating autophagy, with the hope of promoting the development of this promising therapeutic approach.

RNA modification m6Am: the role in cardiac biology

Epitranscriptomic modifications have recently emerged into the spotlight of researchers due to their vast regulatory effects on gene expression and thereby cellular physiology and pathophysiology. N⁶,2'-O-dimethyladenosine (m⁶Am) is one of the most prevalent chemical marks on RNA and is dynamically regulated by writers (PCIF1, METTL4) and erasers (FTO). The presence or absence of m⁶Am in RNA affects mRNA stability, regulates transcription, and modulates pre-mRNA splicing. Nevertheless, its functions in the heart are poorly known. This review summarizes the current knowledge and gaps about m⁶Am modification and its regulators in cardiac biology. It also points out technical challenges and lists the currently available techniques to measure m⁶Am. A better understanding of epitranscriptomic modifications is needed to improve our knowledge of the molecular regulations in the heart which may lead to novel cardioprotective strategies.

Studies on the fat mass and obesity-associated (FTO) gene and its impact on obesity-associated diseases

Obesity has become a major health crisis in the past ∼50 years. The fat mass and obesity-associated (FTO) gene, identified by genome-wide association studies (GWAS), was first reported to be positively associated with obesity in humans. Mice with more copies of the FTO gene were observed to be obese, while loss of the gene in mice was found to protect from obesity. Later, FTO was found to encode an m6A RNA demethylase and has a profound effect on many biological and metabolic processes. In this review, we first summarize recent studies that demonstrate the critical roles and regulatory mechanisms of FTO in obesity and metabolic disease. Second, we discuss the ongoing debates concerning the association between FTO polymorphisms and obesity. Third, since several small molecule drugs and micronutrients have been found to regulate metabolic homeostasis through controlling the expression or activity of FTO, we highlight the broad potential of targeting FTO for obesity treatment. Improving our understanding of FTO and the underlying mechanisms may provide new approaches for treating obesity and metabolic diseases.

Epigenetic regulation of programmed cell death in hypoxia-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe progressive disease that may cause early right ventricular failure and eventual cardiac failure. The pathogenesis of PAH involves endothelial dysfunction, aberrant proliferation of pulmonary artery smooth muscle cells (PASMCs), and vascular fibrosis. Hypoxia has been shown to induce elevated secretion of vascular endothelial growth factor (VEGF), leading to the development of hypoxic PAH. However, the molecular mechanisms underlying hypoxic PAH remain incompletely understood. Programmed cell death (PCD) is a natural cell death and regulated by certain genes. Emerging evidence suggests that apoptotic resistance contributes to the development of PAH. Moreover, several novel types of PCD, such as autophagy, pyroptosis, and ferroptosis, have been reported to be involved in the development of PAH. Additionally, multiple diverse epigenetic mechanisms including RNA methylation, DNA methylation, histone modification, and the non-coding RNA molecule-mediated processes have been strongly linked to the development of PAH. These epigenetic modifications affect the expression of genes, which produce important changes in cellular biological processes, including PCD. Consequently, a better understanding of the PCD processes and epigenetic modification involved in PAH will provide novel, specific therapeutic strategies for diagnosis and treatment. In this review, we aim to discuss recent advances in epigenetic mechanisms and elucidate the role of epigenetic modifications in regulating PCD in hypoxia-induced PAH.

RNA m6A methylation regulators in sepsis

N6-methyladenosine (m6A) modification is a class of epitope modifications that has received significant attention in recent years, particularly in relation to its role in various diseases, including sepsis. Epigenetic research has increasingly focused on m6A modifications, which is influenced by the dynamic regulation of three protein types: ‟Writers" (such as METTL3/METTL14/WTAP)-responsible for m6A modification; ‟Erasers" (FTO and ALKBH5)-involved in m6A de-modification; and ‟Readers" (YTHDC1/2, YTHDF1/2/3)-responsible for m6A recognition. Sepsis, a severe and fatal infectious disease, has garnered attention regarding the crucial effect of m6A modifications on its development. In this review, we attempted to summarize the recent studies on the involvement of m6A and its regulators in sepsis, as well as the significance of m6A modifications and their regulators in the development of novel drugs and clinical treatment. The potential value of m6A modifications and modulators in the diagnosis, treatment, and prognosis of sepsis has also been discussed.

Critical roles of m6A methylation in cardiovascular diseases

Cardiovascular diseases (CVDs) have been established as a major cause of mortality globally. However, the exact pathogenesis remains obscure. N6-methyladenosine (m⁶A) methylation is the most common epigenetic modification on mRNAs regulated by methyltransferase complexes (writers), demethylase transferases (erasers) and binding proteins (readers). It is now understood that m⁶A is a major player in physiological and pathological cardiac processes. m⁶A methylation are potentially involved in many mechanisms, for instance, regulation of calcium homeostasis, endothelial function, different forms of cell death, autophagy, endoplasmic reticulum stress, macrophage response and inflammation. In this review, we will summarize the molecular functions of m⁶A enzymes. We mainly focus on m⁶A-associated mechanisms and functions in CVDs, especially in heart failure and ischemia heart disease. We will also discuss the potential application and clinical transformation of m⁶A modification.

Emerging Role and Mechanism of the FTO Gene in Cardiovascular Diseases

The fat mass and obesity-associated (FTO) gene was the first obesity-susceptibility gene identified through a genome-wide association study (GWAS). A growing number of studies have suggested that genetic variants of FTO are strongly associated with the risk of cardiovascular diseases, including hypertension and acute coronary syndrome. In addition, FTO was also the first N⁶-methyladenosine (m6A) demethylase, suggesting the reversible nature of m6A modification. m6A is dynamically deposited, removed, and recognized by m6A methylases, demethylases, and m6A binding proteins, respectively. By catalyzing m6A demethylation on mRNA, FTO may participate in various biological processes by modulating RNA function. Recent studies demonstrated that FTO plays a pivotal role in the initiation and progression of cardiovascular diseases such as myocardial fibrosis, heart failure, and atherosclerosis and may hold promise as a potential therapeutic target for treating or preventing a variety of cardiovascular diseases. Here, we review the association between FTO genetic variants and cardiovascular disease risk, summarize the role of FTO as an m6A demethylase in cardiovascular disorders, and discuss future research directions and possible clinical implications.

Gene polymorphisms associated with heterogeneity and senescence characteristics of sarcopenia in chronic obstructive pulmonary disease

BACKGROUND

Sarcopenia, or loss of skeletal muscle mass and decreased contractile strength, contributes to morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). The severity of sarcopenia in COPD is variable, and there are limited data to explain phenotype heterogeneity. Others have shown that COPD patients with sarcopenia have several hallmarks of cellular senescence, a potential mechanism of primary (age-related) sarcopenia. We tested if genetic contributors explain the variability in sarcopenic phenotype and accelerated senescence in COPD.

METHODS

To identify gene variants [single nucleotide polymorphisms (SNPs)] associated with sarcopenia in COPD, we performed a genome-wide association study (GWAS) of fat free mass index (FFMI) in 32 426 non-Hispanic White (NHW) UK Biobank participants with COPD. Several SNPs within the fat mass and obesity-associated (FTO) gene were associated with sarcopenia that were validated in an independent COPDGene cohort (n = 3656). Leucocyte telomere length quantified in the UK Biobank cohort was used as a marker of senescence. Experimental validation was done by genetic depletion of FTO in murine skeletal myotubes exposed to prolonged intermittent hypoxia or chronic hypoxia because hypoxia contributes to sarcopenia in COPD. Molecular biomarkers for senescence were also quantified with FTO depletion in murine myotubes.

RESULTS

Multiple SNPs located in the FTO gene were associated with sarcopenia in addition to novel SNPs both within and in proximity to the gene AC090771.2, which transcribes long non-coding RNA (lncRNA). To replicate our findings, we performed a GWAS of FFMI in NHW subjects from COPDGene. The SNP most significantly associated with FFMI was on chromosome (chr) 16, rs1558902A > T in the FTO gene (β = 0.151, SE = 0.021, P = 1.40 × 10-12 for UK Biobank |β= 0.220, SE = 0.041, P = 9.99 × 10-8 for COPDGene) and chr 18 SNP rs11664369C > T nearest to the AC090771.2 gene (β = 0.129, SE = 0.024, P = 4.64 × 10-8 for UK Biobank |β = 0.203, SE = 0.045, P = 6.38 × 10-6 for COPDGene). Lower handgrip strength, a measure of muscle strength, but not FFMI was associated with reduced telomere length in the UK Biobank. Experimentally, in vitro knockdown of FTO lowered myotube diameter and induced a senescence-associated molecular phenotype, which was worsened by prolonged intermittent hypoxia and chronic hypoxia.

CONCLUSIONS

Genetic polymorphisms of FTO and AC090771.2 were associated with sarcopenia in COPD in independent cohorts. Knockdown of FTO in murine myotubes caused a molecular phenotype consistent with senescence that was exacerbated by hypoxia, a common condition in COPD. Genetic variation may interact with hypoxia and contribute to variable severity of sarcopenia and skeletal muscle molecular senescence phenotype in COPD.

Sonodynamic therapy reduces cardiomyocyte apoptosis through autophagy activated by reactive oxygen species in myocardial infarction

Myocardial infarction (MI) is lethal to patients because of acute ischemia and hypoxia leading to cardiac tissue apoptosis. Autophagy played a key role in MI through affecting the survival of cardiomyocytes. LncRNA-MHRT (myosin heavy-chain-associated RNA transcripts) was specific to the heart and cardiomyocytes, and inhibition of lncRNA-MHRT transcription under pathological stimuli could cause cardiac hypertrophy and even heart failure (HF). Sonodynamic therapy (SDT) is a new and developing medical technique that utilizes low-intensity ultrasound to locally activate a preloaded sonosensitizer. Our group previously reported that SDT could regulate autophagy. In this study, we investigated whether SDT could reduce MI-induced cardiomyocyte apoptosis via activating autophagy pathway. SDT improved cardiac function and suppresses MI-induced cardiomyocyte apoptosis. SDT alleviated MI-induced cardiomyocyte apoptosis by improving autophagy. MHRT mediated the inhibiting effect of SDT on cardiomyocyte apoptosis via activating autophagy pathway. Our data reveal a novel effect that SDT protects against MI and confirm that SDT reduces MI-induced cardiomyocyte apoptosis via activating MHRT-mediated-autophagy. Thus, our findings also indicate that SDT may be used as a potential method for treatment of post-myocardial infarction heart failure.

Cerebroprotective Role of N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) After Experimental Stroke

BACKGROUND

FTO (fat mass and obesity-associated protein) demethylates N6-methyladenosine (m6A), which is a critical epitranscriptomic regulator of neuronal function. We previously reported that ischemic stroke induces m6A hypermethylation with a simultaneous decrease in FTO expression in neurons. Currently, we evaluated the functional significance of restoring FTO with an adeno-associated virus 9, and thus reducing m6A methylation in poststroke brain damage.

METHODS

Adult male and female C57BL/6J mice were injected with FTO adeno-associated virus 9 (intracerebral) at 21 days prior to inducing transient middle cerebral artery occlusion. Poststroke brain damage (infarction, atrophy, and white matter integrity) and neurobehavioral deficits (motor function, cognition, depression, and anxiety-like behaviors) were evaluated between days 1 and 28 of reperfusion.

RESULTS

FTO overexpression significantly decreased the poststroke m6A hypermethylation. More importantly, exogenous FTO substantially decreased poststroke gray and white matter damage and improved motor function recovery, cognition, and depression-like behavior in both sexes.

CONCLUSIONS

These results demonstrate that FTO-dependent m6A demethylation minimizes long-term sequelae of stroke independent of sex.

The Mechanism and Role of N6-Methyladenosine (m6A) Modification in Atherosclerosis and Atherosclerotic Diseases

N6-methyladenosine (m6A) modification is a newly discovered regulatory mechanism in eukaryotes. As one of the most common epigenetic mechanisms, m6A's role in the development of atherosclerosis (AS) and atherosclerotic diseases (AD) has also received increasing attention. Herein, we elucidate the effect of m6A on major risk factors for AS, including lipid metabolism disorders, hypertension, and hyperglycemia. We also describe how m6A methylation contributes to endothelial cell injury, macrophage response, inflammation, and smooth muscle cell response in AS and AD. Subsequently, we illustrate the m6A-mediated aberrant biological role in the pathogenesis of AS and AD, and analyze the levels of m6A methylation in peripheral blood or local tissues of AS and AD, which helps to further discuss the diagnostic and therapeutic potential of m6A regulation for AS and AD. In summary, studies on m6A methylation provide new insights into the pathophysiologic mechanisms of AS and AD, and m6A methylation could be a novel diagnostic biomarker and therapeutic target for AS and AD.

Emerging roles of the RNA modifications N6-methyladenosine and adenosine-to-inosine in cardiovascular diseases

Cardiovascular diseases lead the mortality and morbidity disease metrics worldwide. A multitude of chemical base modifications in ribonucleic acids (RNAs) have been linked with key events of cardiovascular diseases and metabolic disorders. Named either RNA epigenetics or epitranscriptomics, the post-transcriptional RNA modifications, their regulatory pathways, components, and downstream effects substantially contribute to the ways our genetic code is interpreted. Here we review the accumulated discoveries to date regarding the roles of the two most common epitranscriptomic modifications, N⁶-methyl-adenosine (m⁶A) and adenosine-to-inosine (A-to-I) editing, in cardiovascular disease.

Regulation of N6-Methyladenosine after Myocardial Infarction

Development of heart failure (HF) after myocardial infarction (MI) is responsible for premature death. Complex cellular and molecular mechanisms are involved in this process. A number of studies have linked the epitranscriptomic RNA modification N6-methyladenosine (m6A) with HF, but it remains unknown how m6A affects the risk of developing HF after MI. We addressed the regulation of m6A and its demethylase fat mass and obesity-associated (FTO) after MI and their association with HF. Using liquid chromatography coupled to mass spectrometry, we observed an increase of m6A content in the infarcted area of rat hearts subjected to coronary ligation and a decrease in blood. FTO expression measured by quantitative PCR was downregulated in the infarcted hearts. In whole blood samples collected at the time of reperfusion in MI patients, m6A content was lower in patients who developed HF as attested by a 4-month ejection fraction (EF) of ≤40% as compared to patients who did not develop HF (EF > 50%). M6A content was higher in females. These results show that m6A measured in blood is associated with HF development after MI and motivate further investigation of the potential role of m6A as a novel epitranscriptomics biomarker and therapeutic target of HF.

Epitranscriptomics Changes the Play: m6A RNA Modifications in Apoptosis

Apoptosis is a form of programmed cell death that is essential for cellular and organismal homeostasis. Any irregularities that disturb the balance between apoptosis and cell survival have severe implications, such as improper development or life-threatening diseases. Thus, it is highly critical to maintain a proper rate of apoptosis throughout development. In fact, several complex transcriptional and posttranscriptional mechanisms exist in eukaryotes to critically regulate the rate of apoptotic processes. Recent studies suggest that not only RNA sequences but also their modifications, such as m⁶A methylation, play a fundamental role in these transcriptional and posttranscriptional processes. A specific set of proteins, called writer, eraser, and reader of m⁶A marks, modulate the rate of apoptosis by determining the m⁶A repertoire and the fate of certain transcripts associated with apoptosis. In this Review, we will cover the dynamic m⁶A RNA modifications and their impact on modulation of apoptosis.

m6A Methylation in Cardiovascular Diseases: From Mechanisms to Therapeutic Potential

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Recent studies have shown that n6-methyladenosine (m6A) plays a major role in cardiovascular homeostasis and pathophysiology. These studies have confirmed that m6A methylation affects the pathophysiology of cardiovascular diseases by regulating cellular processes such as differentiation, proliferation, inflammation, autophagy, and apoptosis. Moreover, plenty of research has confirmed that m6A modification can delay the progression of CVD via the post-transcriptional regulation of RNA. However, there are few available summaries of m6A modification regarding CVD. In this review, we highlight advances in CVD-specific research concerning m6A modification, summarize the mechanisms underlying the involvement of m6A modification during the development of CVD, and discuss the potential of m6A modification as a therapeutic target of CVD.

m6A RNA methylation: A dynamic regulator of cardiac muscle and extracellular matrix

Post-transcriptional modifications encompass a large group of RNA alterations that control gene expression. Methylation of the N⁶-Adenosine (m⁶A) of mRNA is a prevalent modification which alters the life cycle of transcripts. The roles that m⁶A play in regulating cardiac homeostasis and injury response are an active area of investigation, but it is clear that this chemical modification is a critical controller of fibroblast to myofibroblast transition, cardiomyocyte hypertrophy and division, and the structure and function of the extracellular matrix. Here we discuss the latest findings of m⁶A in cardiac muscle and matrix.

N6-Methyladenosine RNA Methylation in Cardiovascular Diseases

N6-methyladenosine (m6A) modification is the most universal and abundant post-transcriptional modification of eukaryotic RNA and occurs mainly at the consensus motif RR (m6A) CH (R = A or G, H = A, C, or U) in long internal exons, near stop codons, or in the 3' untranslated region (UTR). "Writers," "erasers," and "readers" are responsible for the occurrence, removal, and recognition of m6A modification, respectively. Substantial evidence has shown that m6A RNA modification can exert important functions in physiological and pathological processes. Cardiovascular diseases (CVDs) are a wide array of disorders affecting heart or vessels, including atherosclerosis (AS), hypertension (HT), ischemia/reperfusion (I/R) injury, myocardial infarction (MI), stroke, cardiac hypertrophy, heart failure (HF), and so on. Despite the advances in lipid-lowering drugs, antihypertensives, antiplatelet agents, and anticoagulation therapy, CVDs are still the leading cause of death worldwide. Recent studies have suggested that m6A modification of RNA may contribute to the pathogenesis of CVDs, providing a novel research insight for CVDs. Herein, we provide an up-of-date summarization of the molecular mechanism of m6A and the roles of m6A in different types of CVDs. At last, we propose that m6A might be a potiential biomarker or therapeutic target for CVDs.

Senolytics Cocktail Dasatinib and Quercetin Alleviate Human Umbilical Vein Endothelial Cell Senescence via the TRAF6-MAPK-NF-κB Axis in a YTHDF2-Dependent Manner

INTRODUCTION

Senescent cells play a key role in the initiation and development of various age-related diseases. Human umbilical vein endothelial cells (HUVECs) senescence is closely associated with age-related cardiovascular diseases. Accumulating evidence has demonstrated that senolytics, the combination of dasatinib and quercetin (D+Q), could selectively eliminate senescent cells. N6-methyladenosine (m6A), the most abundant internal transcript modification, greatly influences RNA metabolism and modulates gene expression. We aimed to investigate whether RNA m6A functions in lipopolysaccharide (LPS)-induced HUVECs senescence and D+Q suppress HUVECs senescence by regulating RNA m6A.

METHODS

Senescence-associated β-galactosidase activity, western blot, and real-time quantitative polymerase chain reaction were performed to demonstrate that D+Q suppress HUVECs senescence. Methylated RNA immunoprecipitation (MeRIP)-qPCR assay and RIP-qPCR confirmed that RNA m6A plays a key role in the suppression of HUVECs senescence by D+Q. Chromatin immunoprecipitation and mRNA stability assay were carried out to prove that D+Q alleviate HUVECs senescence in a YTHDF2-dependent manner.

RESULTS

Here, we demonstrate that D+Q alleviate LPS-induced senescence in HUVECs via inhibiting autocrine and paracrine of the senescence-associated secretory phenotype (SASP). We further confirm that D+Q alleviate HUVECs senescence via the TNF receptor-associated factor 6 (TRAF6)-MAPK pathway. Mechanically, this study validates that D+Q suppress SASP by upregulating m6A reader YTHDF2. Besides, YTHDF2 regulates the stability of MAP2K4 and MAP4K4 mRNAs.

CONCLUSION

Collectively, we first identified that D+Q alleviate LPS-induced senescence in HUVECs via the TRAF6-MAPK-NF-κB axis in a YTHDF2-dependent manner, providing novel ideas for clinical treatment of age-related cardiovascular diseases.

Emerging Roles and Mechanism of m6A Methylation in Cardiometabolic Diseases

Cardiometabolic diseases (CMDs) are currently the leading cause of death and disability worldwide, and their underlying regulatory mechanisms remain largely unknown. N6-methyladenosine (m6A) methylation, the most common and abundant epigenetic modification of eukaryotic mRNA, is regulated by m6A methyltransferase, demethylase, and the m6A binding protein, which affect the transcription, cleavage, translation, and degradation of target mRNA. m6A methylation plays a vital role in the physiological and pathological processes of CMDs. In this review, we summarize the role played by m6A methylation in CMDs, including obesity, hypertension, pulmonary hypertension, ischemic heart disease, myocardial hypertrophy, heart failure, and atherosclerosis. We also describe mechanisms that potentially involve the participation of m6A methylation, such as those driving calcium homeostasis, circadian rhythm, lipid metabolism, autophagy, macrophage response, and inflammation. m6A methylation and its regulators are expected to be targets for the treatment of CMDs.

Alteration of N6-Methyladenosine mRNA Methylation in a Human Stem Cell-Derived Cardiomyocyte Model of Tyrosine Kinase Inhibitor-Induced Cardiotoxicity

Background

N⁶-methyladenosine (m⁶A) plays important roles in various cardiovascular diseases (CVDs), including cardiac hypertrophy and heart failure. Sunitinib (SUN) is a tyrosine kinase inhibitor (TKI) that is widely used in the treatment of different types of solid and blood tumors, but its efficacy is restricted by a concomitant rise in cardiotoxicities. However, the methylation modification of m⁶A messenger RNA (mRNA) in cardiomyocytes treated with TKI has not been investigated.

Methods

The global m⁶A methylation level of SUN-induced cardiotoxicity was detected by m⁶A dot blot and colorimetric methylation assay. MeRIP-Seq (methylated RNA immunoprecipitation sequencing) and RNA-seq (RNA sequencing, input) were employed to depict the landscapes of transcriptome and epitranscriptome in TKI. Changes in major m⁶A-related enzymes were detected by qRT-PCR and Western blot. In addition, the effects of FTO on SUN-induced cardiotoxicity were evaluated by gain and loss of function studies.

Results

In this study, we observed that the m⁶A methylation level was significantly elevated in SUN-treated human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and paralleled a positively correlated cellular damage level. Through a genome-wide analysis of m⁶A mRNA methylation by methylated RNA immunoprecipitation sequencing (MeRIP-seq) and input RNA sequencing (RNA-seq), we identified a total of 2,614 peaks with significant changes, of which 1,695 peaks were significantly upregulated and 919 peaks were significantly downregulated. Quantitative reverse transcription PCR (RT-qPCR), immunofluorescence, and Western blotting revealed that the RNA demethylase fat mass and obesity-associated protein (FTO) was downregulated, whereas the RNA methylases methyltransferase-like 14 (METTL14) and wilms' tumor 1-associating protein (WTAP) were upregulated. Furthermore, gain- and loss-of-function studies substantiated that FTO is cardioprotective in TKI.

Conclusion

This study deciphered the methylation modification of m⁶A mRNA in hiPSC-CMs post-TKI treatment and determined that FTO may be a promising therapeutic target for TKI-induced cardiotoxicity.

Vitamin D3 Suppresses Human Cytomegalovirus-Induced Vascular Endothelial Apoptosis via Rectification of Paradoxical m6A Modification of Mitochondrial Calcium Uniporter mRNA, Which Is Regulated by METTL3 and YTHDF3

Human cytomegalovirus (HCMV) infection can induce apoptosis of vascular endothelial cells, which may be the most important element of development and progression of reported atherosclerosis caused by HCMV. As there are no specific drugs to clear HCMV infection, exploration of relevant drugs and mechanisms that can intervene in HCMV-induced atherosclerosis is urgently needed. The present study confirmed that vitamin D3 protected vascular endothelial cells from HCMV-induced apoptosis by inhibiting endoplasmic reticulum (ER) and mitochondrial apoptosis pathway. Mechanistically, HCMV infection could induce aberrantly elevated m6A modification, especially the increases of methyltransferases-“writers” (METTL3) and m6A binding proteins-“readers” (YTHDF3). METTL3 methylates mitochondrial calcium uniporter (MCU), the main contributor to HCMV-induced apoptosis of vascular endothelial cells, at three m6A residues in the 3′-UTR, which promotes the association of the YTHDF3 with methylated MCU mRNA and subsequently increases the translation and expression of MCU. Further analysis shows that ALKBH5 is the demethylases-“eraser” of MCU mRNA, which can negatively regulate the m6A modification process of MCU. Conversely, vitamin D3 downregulated the METTL3 by inhibiting the activation of AMPK, thereby inhibiting the m6A modification of MCU and cell apoptosis. Our findings extend the understanding of m6A driven machinery in virus-induced vascular endothelium damage and highlight the significance of vitamin D3 in the intervention of HCMV-induced atherosclerosis.

m6A demethylase FTO regulates the apoptosis and inflammation of cardiomyocytes via YAP1 in ischemia-reperfusion injury

Reperfusion therapy after acute myocardial infarction can induce myocardial ischemia-reperfusion injury (IRI). Novel evidence has illustrated that N6-methyladenosine (m6A) modification modulates the myocardial IRI progression. Here, our study focuses on the role of m6A methyltransferase fat mass and obesity-associated protein (FTO) in myocardial ischemia/reoxygenation injury and explores potential regulatory mechanisms. Results discovered that FTO down-expressed in myocardial IRI mice and hypoxia/reoxygenation (H/R)-induced cardiomyocytes. Functionally, FTO overexpression attenuated the H/R-induced apoptosis and inflammation of cardiomyocytes. Mechanistically, methylated RNA immunoprecipitation quantitative polymerase chain reaction (MeRIP-qPCR) assay and RIP assay revealed that Yap1 mRNA acted as the target of FTO in cardiomyocytes. Moreover, FTO uninstalled the methylation of Yap1 mRNA, and enforced the stability of Yap1 mRNA. Taken together, our study reveals the role of FTO in H/R-induced myocardial cell injury via m6A-dependent manner, which may provide a new approach to improve myocardial IRI.

Role of N6-methyladenosine Modification in Cardiac Remodeling

Cardiac remodeling is the critical process in heart failure due to many cardiovascular diseases including myocardial infarction, hypertension, cardiovascular disease and cardiomyopathy. However, treatments for heart failure focusing on cardiac remodeling show relatively limited effectiveness. In recent decades, epitranscriptomic modifications were found abundantly present throughout the progression of cardiac remodeling, and numerous types of biochemical modifications were identified. m6A modification is the methylation of the adenosine base at the nitrogen-6 position, and dysregulation of m6A modification has been implicated in a wide range of diseases. However, function of m6A modifications still remain largely unknown in cardiac diseases, especially cardiac remodeling. LncRNAs are also shown to play a vital role in the pathophysiology of cardiac remodeling and heart failure. The crosstalk between lncRNAs and m6A modification provides a novel prospective for exploring possible regulatory mechanism and therapeutic targets of cardiac remodeling. This review summarizes the role of m6A modification in cardiac remodeling in the current researches.

Emerging role of m6 A modification in cardiovascular diseases

Cardiovascular diseases (CVDs) contribute to the leading cause of death worldwide. Despite significantly improvements in CVDs diagnosis and treatment, a continued effort to explore novel therapeutic strategies is urgently need. N6-methyladenosine (m⁶ A) RNA methylation, well known as the most prevalent type of RNA modifications, involved in RNA stability, nuclear exports, translation and decoy, plays a crucial role in the pathogenesis of a variety of diseases, including CVDs, cancer and drug resistance. Here, our article summarizes cellular functions of m⁶ A modulators and recent research progress concerning the functions and mechanisms of m⁶ A methylation in CVDs, in hope of providing references for exploring novel therapeutic approaches and potential biomarkers in the treatment of CVDs. This article is protected by copyright. All rights reserved.

Increased m6A-RNA methylation and FTO suppression is associated with myocardial inflammation and dysfunction during endotoxemia in mice

Endotoxemia triggers life-threatening immune and cardiovascular response that leads to tissue damage, multi-organ failure, and death. The understanding of underlying molecular mechanisms is still evolving. N6-methyladenosine (m6A)-RNA modification plays key regulatory role in numerous biological processes. However, it remains unclear whether endotoxemia alters RNA methylation in the myocardium. In the current study, we investigated the effect of lipopolysaccharide (LPS)-induced endotoxemia on m6A-RNA methylation and its implications on myocardial inflammation and left ventricular (LV) function. Following LPS administration, mice showed increases in m6A-RNA methylation in the myocardium with a corresponding decrease in the expression of fat mass and obesity-associated protein (FTO, an m6A eraser/demethylase). The changes were associated with a significant increase in expression of myocardial inflammatory cytokine genes, such as IL-6, TNF-α, IL-1β, and reduced LV function. Moreover, rat cardiomyoblasts (H9c2) exposed to LPS showed similar changes (with increase in m6A-RNA methylation and inflammatory cytokine genes, whereas downregulation of FTO). Furthermore, methylated RNA immunoprecipitation assay showed hypermethylation and increase in the expression of IL-6 and TNF-α genes in LPS-treated H9c2 cells as compared to untreated cells. Interestingly, FTO knockdown in cardiomyocytes mimicked the above effects. Taken together, these data suggest that endotoxemia-induced m6A methylation might play a critical role in expression of cardiac proinflammatory cytokines, and modulation of m6A methylation might limit myocardial inflammation and dysfunction during endotoxemia.

RNA Methylations in Cardiovascular Diseases, Molecular Structure, Biological Functions and Regulatory Roles in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality in the world. Despite considerable progress in the diagnosis, treatment and prognosis of CVDs, new diagnostic biomarkers and new therapeutic measures are urgently needed to reduce the mortality of CVDs and improve the therapeutic effect. RNA methylations regulate almost all aspects of RNA processing, such as RNA nuclear export, translation, splicing and non-coding RNA processing. In view of the importance of RNA methylations in the pathogenesis of diseases, this work reviews the molecular structures, biological functions of five kinds of RNA methylations (m6A, m5C, m1a, m6am and m7G) and their effects on CVDs, including pulmonary hypertension, hypertension, vascular calcification, cardiac hypertrophy, heart failure. In CVDs, m6A “writers” catalyze the installation of m6A on RNAs, while “erasers” remove these modifications. Finally, the “readers” of m6A further influence the mRNA splicing, nuclear export, translation and degradation. M5C, m1A, m6Am and m7G are new types of RNA methylations, their roles in CVDs need to be further explored. RNA methylations have become a new research hotspot and the roles in CVDs is gradually emerging, the review of the molecular characteristics, biological functions and effects of RNA methylation on CVDs will contribute to the elucidation of the pathological mechanisms of CVDs and the discovery of new diagnostic markers and therapeutic targets of CVDs.

Epitranscriptomics of Ischemic Heart Disease-The IHD-EPITRAN Study Design and Objectives

Epitranscriptomic modifications in RNA can dramatically alter the way our genetic code is deciphered. Cells utilize these modifications not only to maintain physiological processes, but also to respond to extracellular cues and various stressors. Most often, adenosine residues in RNA are targeted, and result in modifications including methylation and deamination. Such modified residues as N-6-methyl-adenosine (m6A) and inosine, respectively, have been associated with cardiovascular diseases, and contribute to disease pathologies. The Ischemic Heart Disease Epitranscriptomics and Biomarkers (IHD-EPITRAN) study aims to provide a more comprehensive understanding to their nature and role in cardiovascular pathology. The study hypothesis is that pathological features of IHD are mirrored in the blood epitranscriptome. The IHD-EPITRAN study focuses on m6A and A-to-I modifications of RNA. Patients are recruited from four cohorts: (I) patients with IHD and myocardial infarction undergoing urgent revascularization; (II) patients with stable IHD undergoing coronary artery bypass grafting; (III) controls without coronary obstructions undergoing valve replacement due to aortic stenosis and (IV) controls with healthy coronaries verified by computed tomography. The abundance and distribution of m6A and A-to-I modifications in blood RNA are charted by quantitative and qualitative methods. Selected other modified nucleosides as well as IHD candidate protein and metabolic biomarkers are measured for reference. The results of the IHD-EPITRAN study can be expected to enable identification of epitranscriptomic IHD biomarker candidates and potential drug targets.

Role of N6-Methyladenosine RNA Modification in Cardiovascular Disease

Despite treatments being improved and many risk factors being identified, cardiovascular disease (CVD) is still a leading cause of mortality and disability worldwide. N⁶-methyladenosine (m⁶A) is the most common, abundant, and conserved internal modification in RNAs and plays an important role in the development of CVD. Many studies have shown that aabnormal m⁶A modifications of coding RNAs are involved in the development of CVD. In addition, non-coding RNAs (ncRNAs) exert post-transcriptional regulation in many diseases including CVD. Although ncRNAs have also been found to be modified by m⁶A, the studies on m⁶A modifications of ncRNAs in CVD are currently lacking. In this review, we summarized the recent progress in understanding m⁶A modifications in the context of coding RNAs and ncRNAs, as well as their regulatory roles in CVD.

The evolving landscape of N6-methyladenosine modification in the tumor microenvironment

The tumor microenvironment (TME), controlled by intrinsic mechanisms of carcinogenesis and epigenetic modifications, has, in recent years, become a heavily researched topic. The TME can be described in terms of hypoxia, metabolic dysregulation, immune escape, and chronic inflammation. RNA methylation, an epigenetic modification, has recently been found to have a pivotal role in shaping the TME. The N⁶-methylation of adenosine (m⁶A) modification is the most common type of RNA methylation that occurs in the N⁶-position of adenosine, which is the primary internal modification of eukaryotic mRNA. Compelling evidence has demonstrated that m⁶A regulates transcriptional and protein expression through splicing, translation, degradation, and export, thereby mediating the biological processes of cancer cells and/or stromal cells and characterizing the TME. The TME also has a crucial role in the complicated regulatory network of m⁶A modifications and, subsequently, influences tumor initiation, progression, and therapy responses. In this review, we describe the features of the TME and how the m⁶A modification modulates and interacts with it. We also focus on various factors and pathways involved in m⁶A methylation. Finally, we discuss potential therapeutic strategies and prognostic biomarkers with respect to the TME and m⁶A modification.