Loss of Endothelial FTO Antagonizes Obesity-Induced Metabolic and Vascular Dysfunction

Comprehensive analysis of the m6A demethylase FTO in endothelial dysfunction by MeRIP sequencing

N6-methyladenosine (m6A) is the most general post-transcriptional modification of eukaryotic mRNAs and long-stranded non-coding RNAs. In this process, It has been shown that FTO associates with the m6A mRNA demethylase and plays a role in diabetic vascular endothelial dysfunction. In the present study, we detected FTO protein expression in HUVECs by Western blot and found that FTO was highly expressed in all disease groups relative to the control group. To explore the mechanism of FTO in T2DM vasculopathy, we performed an analysis by methylated RNA immunoprecipitation sequencing (MeRIP-seq) to elucidate the role of aberrant m6A modification and mRNA expression in endothelial dysfunction. The results showed 202 overlapping genes with varying m6A modifications and varied mRNA expression, and GO and KEGG enrichment analysis revealed that these genes were predominantly enriched in pathways associated with T2DM complications and endothelial dysfunction. By an integrated analysis of MeRIP-seq and RNA-seq results, the IGV plots showed elevated kurtosis of downstream candidate gene modifications, which may be downstream targets for FTO to exercise biological functions. HOXA9 and PLAU mRNA expression levels were significantly down after FTO inhibition. In the current work, we set up a typological profile of the m6A genes among HUVECs as well as uncovered a hidden relationship between RNA methylation modifications for T2DM vasculopathy-associated genes. Taken together, this study indicates that endothelial functional impairment is present in T2DM patients and may be related to aberrant expression of FTO.

Epigenetic regulation of diverse regulated cell death modalities in cardiovascular disease: Insights into necroptosis, pyroptosis, ferroptosis, and cuproptosis

Cell death constitutes a critical component of the pathophysiology of cardiovascular diseases. A growing array of non-apoptotic forms of regulated cell death (RCD)-such as necroptosis, ferroptosis, pyroptosis, and cuproptosis-has been identified and is intimately linked to various cardiovascular conditions. These forms of RCD are governed by genetically programmed mechanisms within the cell, with epigenetic modifications being a common and crucial regulatory method. Such modifications include DNA methylation, RNA methylation, histone methylation, histone acetylation, and non-coding RNAs. This review recaps the roles of DNA methylation, RNA methylation, histone modifications, and non-coding RNAs in cardiovascular diseases, as well as the mechanisms by which epigenetic modifications regulate key proteins involved in cell death. Furthermore, we systematically catalog the existing epigenetic pharmacological agents targeting novel forms of RCD and their mechanisms of action in cardiovascular diseases. This article aims to underscore the pivotal role of epigenetic modifications in precisely regulating specific pathways of novel RCD in cardiovascular diseases, thus offering potential new therapeutic avenues that may prove more effective and safer than traditional treatments.

Regulatory roles of RNA methylation in vascular lesions in ocular and cardiopulmonary diseases

RNA methylation is a widespread regulatory mechanism that controls gene expression in physiological processes. In recent years, the mechanisms and functions of RNA methylation under diseased conditions have been increasingly unveiled by RNA sequencing technologies with large scale and high resolution. In this review, the fundamental concept of RNA methylation is introduced, and the common types of transcript methylation and their machineries are described. Then, the regulatory roles of RNA methylation, particularly N6-methyladenosine and 5-methylcytosine, in the vascular lesions of ocular and cardiopulmonary diseases are discussed and compared. The ocular diseases include corneal neovascularization, retinopathy of prematurity, diabetic retinopathy, and pathologic myopia; whereas the cardiopulmonary ailments involve atherosclerosis and pulmonary hypertension. This review hopes to shed light on the common regulatory mechanisms underlying the vascular lesions in these ocular and cardiopulmonary diseases, which may be conducive to developing therapeutic strategies in clinical practice.

RNA modifications in cellular metabolism: implications for metabolism-targeted therapy and immunotherapy

Cellular metabolism is an intricate network satisfying bioenergetic and biosynthesis requirements of cells. Relevant studies have been constantly making inroads in our understanding of pathophysiology, and inspiring development of therapeutics. As a crucial component of epigenetics at post-transcription level, RNA modification significantly determines RNA fates, further affecting various biological processes and cellular phenotypes. To be noted, immunometabolism defines the metabolic alterations occur on immune cells in different stages and immunological contexts. In this review, we characterize the distribution features, modifying mechanisms and biological functions of 8 RNA modifications, including N6-methyladenosine (m6A), N6,2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N4-acetylcytosine (ac4C), N7-methylguanosine (m7G), Pseudouridine (Ψ), adenosine-to-inosine (A-to-I) editing, which are relatively the most studied types. Then regulatory roles of these RNA modification on metabolism in diverse health and disease contexts are comprehensively described, categorized as glucose, lipid, amino acid, and mitochondrial metabolism. And we highlight the regulation of RNA modifications on immunometabolism, further influencing immune responses. Above all, we provide a thorough discussion about clinical implications of RNA modification in metabolism-targeted therapy and immunotherapy, progression of RNA modification-targeted agents, and its potential in RNA-targeted therapeutics. Eventually, we give legitimate perspectives for future researches in this field from methodological requirements, mechanistic insights, to therapeutic applications.

Obesogenic diet disrupts tissue-specific mitochondrial gene signatures in the artery and capillary endothelium

Endothelial cells (ECs) adapt to the unique needs of their resident tissue and metabolic perturbations, such as obesity. We sought to understand how obesity affects EC metabolic phenotypes, specifically mitochondrial gene expression. We investigated the mesenteric and adipose endothelium because these vascular beds have distinct roles in lipid homeostasis. Initially, we performed bulk RNA sequencing on ECs from mouse adipose and mesenteric vasculatures after a normal chow (NC) diet or high-fat diet (HFD) and found higher mitochondrial gene expression in adipose ECs compared with mesenteric ECs in both NC and HFD mice. Next, we performed single-cell RNA sequencing and categorized ECs as arterial, capillary, venous, or lymphatic. We found mitochondrial genes to be enriched in adipose compared with mesentery under NC conditions in artery and capillary ECs. After HFD, these genes were decreased in adipose ECs, becoming like mesenteric ECs. Transcription factor analysis revealed that peroxisome proliferator-activated receptor-γ (PPAR-γ) had high specificity in NC adipose artery and capillary ECs. These findings were recapitulated in single-nuclei RNA-sequencing data from human visceral adipose. The sum of these findings suggests that mesenteric and adipose arterial ECs metabolize lipids differently, and the transcriptional phenotype of the vascular beds converges in obesity due to downregulation of PPAR-γ in adipose artery and capillary ECs.NEW & NOTEWORTHY Using bulk and single-cell RNA sequencing on endothelial cells from adipose and mesentery, we found that an obesogenic diet induces a reduction in adipose endothelial oxidative phosphorylation gene expression, resulting in a phenotypic convergence of mesenteric and adipose endothelial cells. Furthermore, we found evidence that PPAR-γ drives this phenotypic shift. Mining of human data sets segregated based on body mass index supported these findings. These data point to novel mechanisms by which obesity induces endothelial dysfunction.

Pannexin-3 stabilizes the transcription factor Bcl6 in a channel-independent manner to protect against vascular oxidative stress

Targeted degradation regulates the activity of the transcriptional repressor Bcl6 and its ability to suppress oxidative stress and inflammation. Here, we report that abundance of endothelial Bcl6 is determined by its interaction with Golgi-localized pannexin 3 (Panx3) and that Bcl6 transcriptional activity protects against vascular oxidative stress. Consistent with data from obese, hypertensive humans, mice with an endothelial cell-specific deficiency in Panx3 had spontaneous systemic hypertension without obvious changes in channel function, as assessed by Ca2+ handling, ATP amounts, or Golgi luminal pH. Panx3 bound to Bcl6, and its absence reduced Bcl6 protein abundance, suggesting that the interaction with Panx3 stabilized Bcl6 by preventing its degradation. Panx3 deficiency was associated with increased expression of the gene encoding the H2O2-producing enzyme Nox4, which is normally repressed by Bcl6, resulting in H2O2-induced oxidative damage in the vasculature. Catalase rescued impaired vasodilation in mice lacking endothelial Panx3. Administration of a newly developed peptide to inhibit the Panx3-Bcl6 interaction recapitulated the increase in Nox4 expression and in blood pressure seen in mice with endothelial Panx3 deficiency. Panx3-Bcl6-Nox4 dysregulation occurred in obesity-related hypertension, but not when hypertension was induced in the absence of obesity. Our findings provide insight into a channel-independent role of Panx3 wherein its interaction with Bcl6 determines vascular oxidative state, particularly under the adverse conditions of obesity.

M6A plays a potential role in carotid atherosclerosis by modulating immune cell modification and regulating aging-related genes

RNA N6-methyladenosine (m6A) regulators play essential roles in diverse biological processes, including immune responses. Mounting evidence suggests that their dysregulation is intricately linked to numerous diseases. However, the role of m6A-associated genes in carotid atherosclerosis and their relationship with aging and immune cells remain unclear. Analyze the expression profiles of m6A-related genes in carotid atherosclerosis-related datasets. Based on the expression patterns of m6A-related genes, perform consistent clustering analysis of carotid atherosclerosis samples and investigate associated immune cell infiltration patterns and aging characteristics. Develop an m6A prediction model specific to carotid atherosclerosis and analyze the relationships between immune cells infiltration and aging features. The m6A methylation modification level exhibited a substantial decrease in early-stage carotid atherosclerosis samples compared to late-stage carotid atherosclerosis samples. Subsequently, two distinct m6A subtypes were defined through consensus clustering analysis, with the lower m6A modification level group showing associations with heightened immune cell infiltration and increased expression of aging-related genes. A model composed of five m6A-related genes was formulated, and the results indicated that this model possesses effective predictive and therapeutic capabilities for carotid atherosclerosis. Furthermore, the downregulation of YTHDC1 expression resulted in elevated expression of inflammatory factors and a decrease in the expression of the aging-related gene RGN. Single-cell data analysis suggests that the reduced expression of YTHDC1 may decrease the degradation of inflammation-related factors in macrophages, leading to a highly inflammatory state in the carotid artery wall. Furthermore, the sustained release of inflammatory factors may increase the expression of the aging-related gene RGN in vascular smooth muscle cells, further exacerbating the progression of atherosclerosis. A reduced level of m6A methylation modification could enhance inflammation and expedite cellular aging, thereby contributing to the development of carotid atherosclerosis.

Role of TRPV4 on vascular tone regulation in pathophysiological states

Vascular tone regulation is a key event in controlling blood flow in the body. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) help regulate the vascular tone. Abnormal vascular responsiveness to various stimuli, including constrictors and dilators, has been observed in pathophysiological states although EC and VSMC coordinate to maintain the exquisite balance between contraction and relaxation in vasculatures. Thus, investigating the mechanisms underlying vascular tone abnormality is very important in maintaining vascular health and treating vasculopathy. Increased intracellular free Ca2+ concentration ([Ca2+]i) is one of the major triggers initiating each EC and VSMC response. Transient receptor potential vanilloid family member 4 (TRPV4) is a Ca2+-permeable non-selective ion channel, which is activated by several stimuli, and is presented in both ECs and VSMCs. Therefore, TRPV4 plays an important role in vascular responses. Emerging evidence indicates the role of TRPV4 on the functions of ECs and VSMCs in various pathophysiological states, including hypertension, diabetes, and obesity. This review focused on the link between TRPV4 and the functions of ECs/VSMCs, particularly its role in vascular tone and responsiveness to vasoactive substances.

Advanced glycation end products impair bone marrow mesenchymal stem cells osteogenesis in periodontitis with diabetes via FTO-mediated N6-methyladenosine modification of sclerostin

BACKGROUND

Diabetes mellitus (DM) and periodontitis are two prevalent diseases with mutual influence. Accumulation of advanced glycation end products (AGEs) in hyperglycemia may impair cell function and worsen periodontal conditions. N6-methyladenosine (m6A) is an important post-transcriptional modification in RNAs that regulates cell fate determinant and progression of diseases. However, whether m6A methylation participates in the process of periodontitis with diabetes is unclear. Thus, we aimed to investigate the effects of AGEs on bone marrow mesenchymal stem cells (BMSCs), elucidate the m6A modification mechanism in diabetes-associated periodontitis.

METHODS

Periodontitis with diabetes were established by high-fat diet/streptozotocin injection and silk ligation. M6A modifications in alveolar bone were demonstrated by RNA immunoprecipitation sequence. BMSCs treated with AGEs, fat mass and obesity associated (FTO) protein knockdown and sclerostin (SOST) interference were evaluated by quantitative polymerase chain reaction, western blot, immunofluorescence, alkaline phosphatase and Alizarin red S staining.

RESULTS

Diabetes damaged alveolar bone regeneration was validated in vivo. In vitro experiments showed AGEs inhibited BMSCs osteogenesis and influenced the FTO expression and m6A level in total RNA. FTO knockdown increased the m6A levels and reversed the AGE-induced inhibition of BMSCs differentiation. Mechanically, FTO regulated m6A modification on SOST transcripts, and AGEs affected the binding of FTO to SOST transcripts. FTO knockdown accelerated the degradation of SOST mRNA in presence of AGEs. Interference with SOST expression in AGE-treated BMSCs partially rescued the osteogenesis by activating Wnt Signaling.

CONCLUSIONS

AGEs impaired BMSCs osteogenesis by regulating SOST in an m6A-dependent manner, presenting a promising method for bone regeneration treatment of periodontitis with diabetes.

Tissue-specific mechanisms of fat metabolism that focus on insulin actions

BACKGROUND

The accumulation of ectopic fats is related to metabolic syndromes with insulin resistance, which is considered as the first hit in obesity-related diseases. However, systematic understanding of the occurrence of ectopic fats is limited, since organisms are capable of orchestrating complicated intracellular signaling pathways to ensure that the correct nutritional components reach the tissues where they are needed. Interestingly, tissue-specific mechanisms lead to different consequences of fat metabolism with different insulin sensitivities.

AIM OF REVIEW

To summarize the mechanisms of fat deposition in different tissues including adipose tissue, subcutis, liver, muscle and intestines, in an attempt to elucidate interactive mechanisms involving insulin actions and establish a potential reference for the rational uptake of fat.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Tissue-specific fat metabolism serves as a trigger for developing abnormal fat metabolism or as a compensatory agent for regulating normal fat metabolism. Outcomes of de novo lipogenesis and adipogenesis differ in the subcutaneous adipose tissue (SAT), liver and muscle, with the participation of insulin actions. Overload of lipid metabolic capability results in SAT fat expansion, and ectopic fat accumulation implicates impaired lipo-/adipogenesis in SAT. Regulating insulin actions may be a key measure on fat deposition and metabolism in individuals.

FTO fuels diabetes-induced vascular endothelial dysfunction associated with inflammation by erasing m6A methylation of TNIP1

Endothelial dysfunction is a critical and initiating factor of the vascular complications of diabetes. Inflammation plays an important role in endothelial dysfunction regulated by epigenetic modifications. N6-methyladenosine (m6A) is one of the most prevalent epigenetic modifications in eukaryotic cells. In this research, we identified an m6A demethylase, fat mass and obesity-associated protein (FTO), as an essential epitranscriptomic regulator in diabetes-induced vascular endothelial dysfunction. We showed that enhanced FTO reduced the global level of m6A in hyperglycemia. FTO knockdown in endothelial cells (ECs) resulted in less inflammation and compromised ability of migration and tube formation. Compared with EC Ftofl/fl diabetic mice, EC-specific Fto-deficient (EC FtoΔ/Δ) diabetic mice displayed less retinal vascular leakage and acellular capillary formation. Furthermore, methylated RNA immunoprecipitation sequencing (MeRIP-Seq) combined with RNA-Seq indicated that Tnip1 served as a downstream target of FTO. Luciferase activity assays and RNA pull-down demonstrated that FTO repressed TNIP1 mRNA expression by erasing its m6A methylation. In addition, TNIP1 depletion activated NF-κB and other inflammatory factors, which aggravated retinal vascular leakage and acellular capillary formation, while sustained expression of Tnip1 by intravitreal injection of adeno-associated virus alleviated endothelial impairments. These findings suggest that the FTO-TNIP1-NF-κB network provides potential targets to treat diabetic vascular complications.

Is There a Relationship between Adverse Pregnancy Outcomes and Future Development of Atherosclerosis?

Cardiovascular disease is one of the main death causes globally. Effective cardiovascular risk management requires a thorough understanding of the mechanisms underlying the disorder. Establishing early markers of the disease allows a timely intervention and prevention of further atherosclerosis development. Multiple studies confirm the correlation between pregnancy disorders and cardiovascular disease in the postpartum period. Moreover, over 30% of women experience adverse pregnancy outcomes. Thus, the examination of the links between these conditions and atherosclerotic cardiovascular disease may help to identify gender-specific risk factors. In this review, we will explore the association between several adverse pregnancy outcome conditions and atherosclerosis. The current analysis is based on the data from several recent studies on the mechanisms behind gestational diabetes, hypertensive disorders of pregnancy, miscarriages, and stillbirths and their implications for the female cardiovascular system.

RNA modification: mechanisms and therapeutic targets

RNA modifications are dynamic and reversible chemical modifications on substrate RNA that are regulated by specific modifying enzymes. They play important roles in the regulation of many biological processes in various diseases, such as the development of cancer and other diseases. With the help of advanced sequencing technologies, the role of RNA modifications has caught increasing attention in human diseases in scientific research. In this review, we briefly summarized the basic mechanisms of several common RNA modifications, including m6A, m5C, m1A, m7G, Ψ, A-to-I editing and ac4C. Importantly, we discussed their potential functions in human diseases, including cancer, neurological disorders, cardiovascular diseases, metabolic diseases, genetic and developmental diseases, as well as immune disorders. Through the "writing-erasing-reading" mechanisms, RNA modifications regulate the stability, translation, and localization of pivotal disease-related mRNAs to manipulate disease development. Moreover, we also highlighted in this review all currently available RNA-modifier-targeting small molecular inhibitors or activators, most of which are designed against m6A-related enzymes, such as METTL3, FTO and ALKBH5. This review provides clues for potential clinical therapy as well as future study directions in the RNA modification field. More in-depth studies on RNA modifications, their roles in human diseases and further development of their inhibitors or activators are needed for a thorough understanding of epitranscriptomics as well as diagnosis, treatment, and prognosis of human diseases.

FTO Gene Polymorphisms and Their Roles in Acromegaly

The major causes of both morbidity and mortality in patients with acromegaly are cardiovascular diseases (CVDs). The polymorphisms of the fat mass and obesity-associated gene (FTO) are associated with obesity, as well as with an increased risk of CVDs. The aim of the study was to determine the relationship of risk alleles of four FTO gene polymorphisms with selected parameters of lipid and glucose metabolism as well as with IGF-1 and GH levels in the group of patients with acromegaly compared to the control group. The study group consisted of 104 patients with acromegaly and 64 healthy subjects constituting the control group. In the whole acromegaly group, the data reveal that the homozygous for risk allele carriers (rs1421085, rs9930506, rs9939609) as well as carriers of only one risk allele have lower IGF-1 concentrations. In the well-controlled acromegaly group, the homozygous for three risk allele carriers of FTO gene polymorphisms have lower HDL cholesterol concentration (rs1121980, rs1421085, rs993609). In the cured acromegaly group, homozygous risk allele carriers rs9930506 tend to have higher levels of total cholesterol and LDL cholesterol. These associations are not observed in the control group. Conclusion: there is an association between FTO gene polymorphisms and the metabolism of lipids, suggesting that the FTO gene may be associated with higher CVD risk in patients with acromegaly. In addition, there is an association between FTO gene polymorphisms and IGF-1, implying that FTO gene may influence/modify IGF-1 synthesis. Further investigation on a larger scale is required to provide more precise evidence.

Epitranscriptional Regulation: From the Perspectives of Cardiovascular Bioengineering

The central dogma of gene expression involves DNA transcription to RNA and RNA translation into protein. As key intermediaries and modifiers, RNAs undergo various forms of modifications such as methylation, pseudouridylation, deamination, and hydroxylation. These modifications, termed epitranscriptional regulations, lead to functional changes in RNAs. Recent studies have demonstrated crucial roles for RNA modifications in gene translation, DNA damage response, and cell fate regulation. Epitranscriptional modifications play an essential role in development, mechanosensing, atherogenesis, and regeneration in the cardiovascular (CV) system, and their elucidation is critically important to understanding the molecular mechanisms underlying CV physiology and pathophysiology. This review aims at providing biomedical engineers with an overview of the epitranscriptome landscape, related key concepts, recent findings in epitranscriptional regulations, and tools for epitranscriptome analysis. The potential applications of this important field in biomedical engineering research are 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.

Alteration of m6A-Tagged RNA Profiles in Bone Originated from Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is a devastating complication. This study aimed to unravel the veil of the N⁶-methyladenine (m⁶A) modification in PJI. Synovium, synovial fluid, sonication fluid and bone samples were collected intraoperatively from Staphylococcus aureus PJI and aseptic failure (AF) patients. The overall m⁶A level was detected by the m⁶A RNA methylation quantification kit, and the expression of m⁶A-related genes was quantified by real-time PCR and Western blot. Finally, an epitranscriptomic microarray and bioinformatics analysis were performed. We showed that there was a significant difference in overall m⁶A level between the PJI group and the AF group (PJI group had a higher overall m⁶A level). The expression level of METTL3 was higher in the PJI group than that in the AF group. There were 2802 differential m⁶A-modified mRNAs. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differential m⁶A-modified mRNAs were significantly enriched in the NOD-like receptor signaling pathway, Th17 cell differentiation and the IL-17 signaling pathway, which indicates that the m⁶A modification might be involved in the processes of infection and immune response, bone metabolism and programmed cell death in PJI. In summary, the present work demonstrated that m⁶A modification plays a role in PJI and might be a therapeutic target for developing effective treatment strategies.

Vascular Smooth Muscle TRPV4 (Transient Receptor Potential Vanilloid Family Member 4) Channels Regulate Vasoconstriction and Blood Pressure in Obesity

BACKGROUND

Vascular endothelium and smooth muscle work together to keep the balance of vasomotor tone and jointly maintain vascular homeostasis. Ca²⁺-permeable ion channel TRPV4 (transient receptor potential vanilloid family member 4) in endothelial cells regulates endothelium-dependent vasodilation and contraction in various states. However, how vascular smooth muscle cell TRPV4 (TRPV4_SMC) contributes to vascular function and blood pressure regulation in physiological and pathologically obese condition has not been fully studied.

METHODS

We generated smooth muscle TRPV4-deficient mice and developed diet-induced obese mice model and analyzed the role of TRPV4_SMC in intracellular Ca²⁺ ([Ca²⁺]_i) regulation and vasoconstriction. Vasomotor changes of mouse mesenteric artery were measured by wire, and pressure myography. [Ca²⁺]_i were measured by fluo-4 staining. Blood pressure was recorded by telemetric device.

RESULTS

Vascular TRPV4_SMC played different roles in regulating vasomotor tone than endothelial TRPV4 due to their different features of [Ca²⁺]_i regulation. Loss of TRPV4_SMC attenuated U46619- and phenylephrine-induced contraction, suggesting its involvement in regulating vascular contractility. Mesenteric arteries from obese mice showed SMC hyperplasia, suggesting an increased level of TRPV4_SMC. Loss of TRPV4_SMC did not influence the development of obesity but protected mice from obesity-induced vasoconstriction and hypertension. In arteries deficient in SMC TRPV4, SMCs F-actin polymerization and RhoA dephosphorylation were attenuated under contractile stimuli. Moreover, SMC-dependent vasoconstriction was inhibited in human resistance arteries with TRPV4 inhibitor application.

CONCLUSIONS

Our data identify TRPV4_SMC as a regulator of vascular contraction in both physiological states and pathologically obese mice. TRPV4_SMC contributes to the ontogeny of vasoconstriction and hypertension induced by TRPV4_SMC over-expression in obese mice mesenteric artery.

Genetic architecture for skeletal muscle glycolytic potential in Chinese Erhualian pigs revealed by a genome-wide association study using 1.4M SNP array

Introduction: Muscle glycolytic potential (GP) is a key factor affecting multiple meat quality traits. It is calculated based on the contents of residual glycogen and glucose (RG), glucose-6-phosphate (G6P), and lactate (LAT) contents in muscle. However, the genetic mechanism of glycolytic metabolism in skeletal muscle of pigs remains poorly understood. With a history of more than 400 years and some unique characteristics, the Erhualian pig is called the “giant panda” (very precious) in the world’s pig species by Chinese animal husbandry.

Methods: Here, we performed a genome-wide association study (GWAS) using 1.4M single nucleotide polymorphisms (SNPs) chips for longissimus RG, G6P, LAT, and GP levels in 301 purebred Erhualian pigs.

Results: We found that the average GP value of Erhualian was unusually low (68.09 μmol/g), but the variation was large (10.4–112.7 μmol/g). The SNP-based heritability estimates for the four traits ranged from 0.16–0.32. In total, our GWAS revealed 31 quantitative trait loci (QTLs), including eight for RG, nine for G6P, nine for LAT, five for GP. Of these loci, eight were genome-wide significant (p < 3.8 × 10−7), and six loci were common to two or three traits. Multiple promising candidate genes such as FTO, MINPP1, RIPOR2, SCL8A3, LIFR and SRGAP1 were identified. The genotype combinations of the five GP-associated SNPs also showed significant effect on other meat quality traits.

Discussion: These results not only provide insights into the genetic architecture of GP related traits in Erhualian, but also are useful for pig breeding programs involving this breed.

Amount of Pannexin 1 in Smooth Muscle Cells Regulates Sympathetic Nerve-Induced Vasoconstriction

BACKGROUND

Panx1 (pannexin 1) forms high conductance channels that secrete ATP upon stimulation. The role of Panx1 in mediating constriction in response to direct sympathetic nerve stimulation is not known. Additionally, it is unknown how the expression level of Panx1 in smooth muscle cells (SMCs) influences α-adrenergic responses. We hypothesized that the amount of Panx1 in SMCs dictates the levels of sympathetic constriction and blood pressure.

METHODS

To test this hypothesis, we used genetically modified mouse models enabling expression of Panx1 in vascular cells to be varied. Electrical field stimulation on isolated arteries and blood pressure were assessed.

RESULTS

Genetic deletion of SMC Panx1 prevented constriction by electric field stimulation of sympathetic nerves. Conversely, overexpression of Panx1 in SMCs using a ROSA26 transgenic model increased sympathetic nerve-mediated constriction. Connexin 43 hemichannel inhibitors did not alter constriction. Next, we evaluated the effects of altered SMC Panx1 expression on blood pressure. To do this, we created mice combining a global Panx1 deletion, with ROSA26-Panx1 under the control of an inducible SMC specific Cre (Myh11). This resulted in mice that could express only human Panx1, only in SMCs. After tamoxifen, these mice had increased blood pressure that was acutely decreased by the Panx1 inhibitor spironolactone. Control mice genetically devoid of Panx1 did not respond to spironolactone.

CONCLUSIONS

These data suggest Panx1 in SMCs could regulate the extent of sympathetic nerve constriction and blood pressure. The results also show the feasibility humanized Panx1-mouse models to test pharmacological candidates.

mRNA Metabolism and Hypertension

Hypertension is the most frequent cardiovascular risk factor all over the world. It remains a leading contributor to the risk of cardiovascular events and death. In the year 2015, about 1.5 billion of adult people worldwide had hypertension (as defined by office systolic blood pressure ≥ 140 mmHg or office diastolic blood pressure ≥ 90 mmHg). Moreover, the number of hypertensive patients with age ranging from 30 to 79 years doubled in the last 30 years (from 317 million men and 331 million women in the year 1990 to 652 million men and 626 million women in 2019) despite stable age-standardized prevalence worldwide. Despite such impressive growth, the proportion of controlled hypertension is very low. A better understanding of the pathogenesis of hypertension may contribute to the development of innovative therapeutic strategies. In this context, alterations of the messenger RNA metabolism have been recently evaluated as contributors to the pathogenesis of hypertension, and pharmacological modulation of RNA metabolism is under investigation as potential and novel therapeutic armamentarium in hypertension.

RNA methylation in vascular disease: a systematic review

Despite the rise in morbidity and mortality associated with vascular diseases, the underlying pathophysiological molecular mechanisms are still unclear. RNA N6-methyladenosine modification, as the most common cellular mechanism of RNA regulation, participates in a variety of biological functions and plays an important role in epigenetics. A large amount of evidence shows that RNA N6-methyladenosine modifications play a key role in the morbidity caused by vascular diseases. Further research on the relationship between RNA N6-methyladenosine modifications and vascular diseases is necessary to understand disease mechanisms at the gene level and to provide new tools for diagnosis and treatment. In this study, we summarize the currently available data on RNA N6-methyladenosine modifications in vascular diseases, addressing four aspects: the cellular regulatory system of N6-methyladenosine methylation, N6-methyladenosine modifications in risk factors for vascular disease, N6-methyladenosine modifications in vascular diseases, and techniques for the detection of N6-methyladenosine-methylated RNA.

Smooth muscle cell FTO regulates contractile function

The fat mass and obesity gene (FTO) is a N6-methyladenosine RNA demethylase that was initially linked by Genome-wide association studies to increased rates of obesity. Subsequent studies have revealed multiple mass-independent effects of the gene, including cardiac myocyte contractility. We created a mouse with a conditional and inducible smooth muscle cell deletion of Fto (Myh11 Cre+ Ftofl/fl) and did not observe any changes in mouse body mass or mitochondrial metabolism. However, the mice had significantly decreased blood pressure (hypotensive), despite increased heart rate and sodium, and significantly increased plasma renin. Remarkably, the third-order mesenteric arteries from these mice had almost no myogenic tone or capacity to constrict to smooth muscle depolarization or phenylephrine. Microarray analysis from Fto-/--isolated smooth muscle cells demonstrated a significant decrease in serum response factor (Srf) and the downstream effectors Acta2, Myocd, and Tagln; this was confirmed in cultured human coronary arteries with FTO siRNA. We conclude Fto is an important component to the contractility of smooth muscle cells.NEW & NOTEWORTHY We show a key role for the fat mass obesity (FTO) gene in regulating smooth muscle contractility, possibly by methylation of serum response factor (Srf).

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.

Exercise training ameliorates myocardial phenotypes in heart failure with preserved ejection fraction by changing N6-methyladenosine modification in mice model

Heart failure with preserved ejection fraction (HFpEF) shows complicated and not clearly defined etiology and pathogenesis. Although no pharmacotherapeutics have improved the survival rate in HFpEF, exercise training has become an efficient intervention to improve functional outcomes. Here, we investigated N6-methyladenosine (m6A) RNA methylation modification in a “two-hit” mouse model with HFpEF and HFpEF with exercise (HFpEF + EXT). The manner of m6A in HFpEF and HFpEF + EXT hearts was explored via m6A-specific methylated RNA immunoprecipitation followed by high-throughput and RNA sequencing methods. A total amount of 3992 novel m6A peaks were spotted in HFpEF + EXT, and 426 differently methylated sites, including 371 hypermethylated and 55 hypomethylated m6A sites, were singled out for further analysis (fold change >2, p < 0.05). According to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, unique m6A-modified transcripts in HFpEF + EXT were associated with apoptosis-related pathway and myocardial energy metabolism. HFpEF + EXT had higher total m6A levels and downregulated fat mass and obesity-related (FTO) protein levels. Overexpression of FTO cancels out the benefits of exercise in HFpEF + EXT mice by promoting myocyte apoptosis, myocardial fibrosis and myocyte hypertrophy. Totally, m6A is a significant alternation of epitranscriptomic processes, which is also a potentially meaningful therapeutic target.

Intermittent hypoxia-induced METTL3 downregulation facilitates MGLL-mediated lipolysis of adipocytes in OSAS

Intermittent hypoxia (IH) is the core pathological feature of obstructive sleep apnea syndrome (OSAS), and insulin resistance (IR) is the most common metabolic complication of OSAS. Studies have shown that the levels of free fatty acids (FFAs), which are mainly released from adipocytes by lipolysis, are elevated in OSAS and play an important role in the development of IR. However, whether and how IH regulates adipocyte lipolysis in OSAS is not clear. Here, we revealed that the apnea hypopnea index was positively correlated with the serum levels of FFAs and FFA release from adipocytes in OSAS. In addition, IH facilitated lipolysis and FFA release from adipocytes by downregulating the level of METTL3. METTL3 downregulation impaired N6-methyladenosine (m6A) levels in MGLL mRNA and reduced MGLL expression, thereby promoting lipolysis. In addition, we identified YTHDF2 as the m6A reader that interacts with MGLL mRNA, accelerating its degradation. Furthermore, our data showed reduced levels of METTL3 and elevated levels of MGLL in the adipose tissues of OSAS patients and indicated an effect of METTL3 on lowering FFA levels and improving IR in rats with chronic IH. In conclusion, our study provides new insights into the development and treatment of IR in OSAS.

Association of AGTR1 gene methylation and its genetic variant in Chinese farmer with hypertension: A case-control study

The objective was to determine the potential associations of the angiotensin II receptor type 1 (AGTR1) gene polymorphism, methylation, and lipid metabolism in Chinese farmers with hypertension. A case-control study was conducted in Wuzhi county of Henan province in China in 2013 to 2014. A total of 1034 local residents (35-74 years, 386 hypertensive cases, and 648 normotensive subjects) were enrolled in this study. Triglyceride (TG), total cholesterol (TC), high-density lipoprotein, and low-density lipoprotein were measured using automatic chemistry analyzer. The AGTR1 gene promoter methylation level was measured using quantitative methylation-specific polymerase chain reaction method. The single nucleotide polymorphism rs275653 was genotyped with TaqMan probe assay at an applied biosystems platform. The gender, body mass index (BMI), TG, TC, and family history of hypertension in the hypertension group were significantly higher than those in control group (P < .05). No significant difference was observed in the distribution of AGTR1 rs275653 polymorphism in the hypertension and controls (P > .05). The AGTR1 gene methylation in subjects carrying different genotypes was not significantly observed (P > .05). The logistic regression analysis found the AGTR1 gene methylation level was negative correlation with hypertension in the present study (odds ratio, 0.946, 95% confidence interval, 0.896-0.999) through adjusting for age, gender, BMI, education, smoking, alcohol drinking, fruit and vegetable intake, pickles intake, and family history of hypertension. The association of AGTR1 gene hypomethylation and essential hypertension was observed in Chinese farmers; no significant difference was observed in the distribution of AGTR1 rs275653 polymorphism.

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.

Recent Advances of m6A Demethylases Inhibitors and Their Biological Functions in Human Diseases

N6-methyladenosine (m6A) is a post-transcriptional RNA modification and one of the most abundant types of RNA chemical modifications. m6A functions as a molecular switch and is involved in a range of biomedical aspects, including cardiovascular diseases, the central nervous system, and cancers. Conceptually, m6A methylation can be dynamically and reversibly modulated by RNA methylation regulatory proteins, resulting in diverse fates of mRNAs. This review focuses on m6A demethylases fat-mass- and obesity-associated protein (FTO) and alkB homolog 5 (ALKBH5), which especially erase m6A modification from target mRNAs. Recent advances have highlighted that FTO and ALKBH5 play an oncogenic role in various cancers, such as acute myeloid leukemias (AML), glioblastoma, and breast cancer. Moreover, studies in vitro and in mouse models confirmed that FTO-specific inhibitors exhibited anti-tumor effects in several cancers. Accumulating evidence has suggested the possibility of FTO and ALKBH5 as therapeutic targets for specific diseases. In this review, we aim to illustrate the structural properties of these two m6A demethylases and the development of their specific inhibitors. Additionally, this review will summarize the biological functions of these two m6A demethylases in various types of cancers and other human diseases.

N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) as a Novel Mediator of Statin Effects in Human Endothelial Cells

BACKGROUND

N6-methyladenosine (m6A) plays a critical role in various biological processes. However, no study has addressed the role of m6A modification in the statin-induced protection of endothelial cells (ECs).

METHODS

Quantitative real-time polymerase chain reaction and Western blotting analyses were used to study the expression of m6A regulatory genes in atorvastatin-treated ECs. Gain- and loss-of-function assays, methylated RNA immunoprecipitation analysis, and dual-luciferase reporter assays were performed to clarify the function of FTO (fat mass and obesity-associated protein) in ECs.

RESULTS

Atorvastatin decreased FTO protein expression in ECs. The knockdown of FTO enhanced the mRNA and protein expression of KLF2 (Kruppel-like factor 2) and eNOS (endothelial NO synthase) but attenuated TNFα (tumor necrosis factor alpha)-induced VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) expression, as well as the adhesion of monocytes to ECs. Conversely, FTO overexpression significantly upregulated the mRNA and protein levels of VCAM-1 and ICAM-1, downregulated those of KLF2 and eNOS, and strongly attenuated the atorvastatin-mediated induction of KLF2 and eNOS expression. Subsequent investigations demonstrated that KLF2 and eNOS are functionally critical targets of FTO. Mechanistically, FTO interacted with KLF2 and eNOS transcripts and regulated their expression in an m6A-dependent manner. After FTO silencing, KLF2 and eNOS transcripts with higher levels of m6A modification in their 3' untranslated regions were captured by YTHDF3 (YT521-B homology m6A RNA-binding protein 3), resulting in mRNA stabilization and the induction of KLF2 and eNOS protein expression.

CONCLUSIONS

FTO might serve as a novel molecular target to modulate endothelial function in vascular diseases.

Targeting Epigenetic Mechanisms in Vascular Aging

Environment, diseases, lack of exercise, and aged tendency of population have becoming crucial factors that induce vascular aging. Vascular aging is unmodifiable risk factor for diseases like diabetes, hypertension, atherosclerosis, and hyperlipidemia. Effective interventions to combat this vascular function decline is becoming increasingly urgent as the rising hospitalization rate caused by vascular aging-related diseases. Fortunately, recent transformative omics approaches have enabled us to examine vascular aging mechanisms at unprecedented levels and precision, which make our understanding of slowing down or reversing vascular aging become possible. Epigenetic viz. DNA methylation, histone modifications, and non-coding RNA-based mechanisms, is a hallmark of vascular aging, its deregulation leads to aberrant transcription changes in tissues. Epigenetics mechanisms by mediating covalent modifications to DNA and histone proteins, consequently, influence the sensitivity and activities of signaling pathways in cells and tissues. A growing body of evidence supports correlations between epigenetic changes and vascular aging. In this article, we will provide a comprehensive overview of epigenetic changes associated with vascular aging based on the recent findings with a focus on molecular mechanisms of action, strategies to reverse epigenetic changes, and future perspectives.

Smoking Status and Type 2 Diabetes, and Cardiovascular Disease: A Comprehensive Analysis of Shared Genetic Etiology and Causal Relationship

OBJECTIVE

This study aimed to explore shared genetic etiology and the causality between smoking status and type 2 diabetes (T2D), cardiovascular diseases (CVDs), and related metabolic traits.

METHODS

Using summary statistics from publicly available genome-wide association studies (GWASs), we estimated genetic correlations between smoking status and T2D, 6 major CVDs, and 8 related metabolic traits with linkage disequilibrium score regression (LDSC) analysis; identified shared genetic loci with large-scale genome-wide cross-trait meta-analysis; explored potential shared biological mechanisms with a series of post-GWAS analyses; and determined causality with Mendelian randomization (MR).

RESULTS

We found significant positive genetic associations with smoking status for T2D (Rg = 0.170, p = 9.39 × 10^-22), coronary artery disease (CAD) (Rg = 0.234, p = 1.96 × 10^-27), myocardial infarction (MI) (Rg = 0.226, p = 1.08 × 10^-17), and heart failure (HF) (Rg = 0.276, p = 8.43 × 10^-20). Cross-trait meta-analysis and transcriptome-wide association analysis of smoking status identified 210 loci (32 novel loci) and 354 gene-tissue pairs jointly associated with T2D, 63 loci (12 novel loci) and 37 gene-tissue pairs with CAD, 38 loci (6 novel loci) and 17 gene-tissue pairs with MI, and 28 loci (3 novel loci) and one gene-tissue pair with HF. The shared loci were enriched in the exo-/endocrine, cardiovascular, nervous, digestive, and genital systems. Furthermore, we observed that smoking status was causally related to a higher risk of T2D (β = 0.385, p = 3.31 × 10^-3), CAD (β = 0.670, p = 7.86 × 10^-11), MI (β = 0.725, p = 2.32 × 10^-9), and HF (β = 0.520, p = 1.53 × 10^-6).

CONCLUSIONS

Our findings provide strong evidence on shared genetic etiology and causal associations between smoking status and T2D, CAD, MI, and HF, underscoring the potential shared biological mechanisms underlying the link between smoking and T2D and CVDs. This work opens up a new way of more effective and timely prevention of smoking-related T2D and CVDs.

The Association of Waist Circumference and the Risk of Deep Vein Thrombosis

Objective

In this study, we aimed to use a two sample Mendelian randomization (MR) method to identify a potentially causality between waist circumference and the risk of deep vein thrombosis (DVT).

Methods

With a two‐sample MR approach, we analyzed the summary data. The main analysis was performed by using the summary genetic data from two large consortium cohorts. Three MR approaches were used to explore MR estimates of waist circumference for DVT (inverse‐variance weighted [IVW] approach, weighted median method and MR‐Egger method). A total of 224 single nucleotide polymorphisms (SNPs) were identified associated with the level of waist circumference at statistical significance (P < 5*10⁻⁸; linkage disequilibrium r² < 0.1).

Results

The result of IVW indicated the positive association between waist circumference and the risk of DVT (OR 1.012, 95% CI 1.009–1.014, P 7.627E-17). The other two methods were observed with consistent result. MR-Egger regression analysis indicated that no evidence for the presence of directional horizontal pleiotropy. Additionally, DVT was not a causal factor for waist circumference.

Conclusion

In summary, we used the GWAS genetic data from two large consortium cohorts and indicated the positive association between waist circumference and DVT. Further researches are needed to investigate potential mechanism and clarify the role of waist circumference on DVT.

LuHui Derivative, A Novel Compound That Inhibits the Fat Mass and Obesity-Associated (FTO), Alleviates the Inflammatory Response and Injury in Hyperlipidemia-Induced Cardiomyopathy

Hyperlipidemia is a major risk factor for metabolic disorders and cardiovascular injury. The excessive deposition of saturated fatty acids in the heart leads to chronic cardiac inflammation, which in turn causes myocardial damage and systolic dysfunction. However, the effective suppression of cardiac inflammation has emerged as a new strategy to reduce the impact of hyperlipidemia on cardiovascular disease. In this study, we identified a novel monomer, known as LuHui Derivative (LHD), which reduced the serum levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and reduced lipid deposition in cardiomyocytes. In addition, LHD treatment improved cardiac function, reduced hyperlipidemia-induced inflammatory infiltration in cardiomyocytes and suppressed the release of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). From a mechanistic perspective, cluster of differentiation 36 (CD36), an important cell surface receptor, was identified as a downstream target following the LHD treatment of palmitic acid-induced inflammation in cardiomyocytes. LHD specifically binds the pocket containing the regulatory sites of RNA methylation in the fat mass and obesity-associated (FTO) protein that is responsible for elevated intracellular m⁶A levels. Moreover, the overexpression of the N6-methyladenosine (m⁶A) demethylase FTO markedly increased CD36 expression and suppressed the anti-inflammatory effects of LHD. Conversely, loss-of-function of FTO inhibited palmitic acid-induced cardiac inflammation and altered CD36 expression by diminishing the stability of CD36 mRNA. Overall, our results provide evidence for the crucial role of LHD in fatty acid-induced cardiomyocyte inflammation and present a new strategy for the treatment of hyperlipidemia and its complications.

Relevance of N6-methyladenosine regulators for transcriptome: Implications for development and the cardiovascular system

N6-methyladenosine (m6A) is the most abundant and well-studied internal modification of messenger RNAs among the various RNA modifications in eukaryotic cells. Moreover, it is increasingly recognized to regulate non-coding RNAs. The dynamic and reversible nature of m6A is ensured by the precise and coordinated activity of specific proteins able to insert ("write"), bind ("read") or remove ("erase") the m6A modification from coding and non-coding RNA molecules. Mounting evidence suggests a pivotal role for m6A in prenatal and postnatal development and cardiovascular pathophysiology. In the present review we summarise and discuss the major functions played by m6A RNA methylation and its components particularly referring to the cardiovascular system. We present the methods used to study m6A and the most abundantly methylated RNA molecules. Finally, we highlight the possible involvement of the m6A mark in cardiovascular disease as well as the need for further studies to better describe the mechanisms of action and the potential therapeutic role of this RNA modification.

Targeting epigenetics and lncRNAs in liver disease: From mechanisms to therapeutics

Early onset and progression of liver diseases can be driven by aberrant transcriptional regulation. Different transcriptional regulation processes, such as RNA/DNA methylation, histone modification, and ncRNA-mediated targeting, can regulate biological processes in healthy cells, as well also under various pathological conditions, especially liver disease. Numerous studies over the past decades have demonstrated that liver disease has a strong epigenetic component. Therefore, the epigenetic basis of liver disease has challenged our knowledge of epigenetics, and epigenetics field has undergone an important transformation: from a biological phenomenon to an emerging focus of disease research. Furthermore, inhibitors of different epigenetic regulators, such as m⁶A-related factors, are being explored as potential candidates for preventing and treating liver diseases. In the present review, we summarize and discuss the current knowledge of five distinct but interconnected and interdependent epigenetic processes in the context of hepatic diseases: RNA methylation, DNA methylation, histone methylation, miRNAs, and lncRNAs. Finally, we discuss the potential therapeutic implications and future challenges and ongoing research in the field. Our review also provides a perspective for identifying therapeutic targets and new hepatic biomarkers of liver disease, bringing precision research and disease therapy to the modern era of epigenetics.

Changes in N6-Methyladenosine Modification Modulate Diabetic Cardiomyopathy by Reducing Myocardial Fibrosis and Myocyte Hypertrophy

In this study, we aimed to systematically profile global RNA N6-methyladenosine (m⁶A) modification patterns in a mouse model of diabetic cardiomyopathy (DCM). Patterns of m⁶A in DCM and normal hearts were analyzed via m⁶A-specific methylated RNA immunoprecipitation followed by high-throughput sequencing (MeRIP-seq) and RNA sequencing (RNA-seq). m⁶A-related mRNAs were validated by quantitative real-time PCR analysis of input and m⁶A immunoprecipitated RNA samples from DCM and normal hearts. A total of 973 new m⁶A peaks were detected in DCM samples and 984 differentially methylated sites were selected for further study, including 295 hypermethylated and 689 hypomethylated m⁶A sites (fold change (FC) > 1.5, P < 0.05). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway analyses indicated that unique m⁶A-modified transcripts in DCM were closely linked to cardiac fibrosis, myocardial hypertrophy, and myocardial energy metabolism. Total m⁶A levels were higher in DCM, while levels of the fat mass and obesity-associated (FTO) protein were downregulated. Overexpression of FTO in DCM model mice improved cardiac function by reducing myocardial fibrosis and myocyte hypertrophy. Overall, m⁶A modification patterns were altered in DCM, and modification of epitranscriptomic processes, such as m⁶A, is a potentially interesting therapeutic approach.

Adipose Tissue-Endothelial Cell Interactions in Obesity-Induced Endothelial Dysfunction

Obesity has a strong impact on the pathogenesis of cardiovascular disease, which raises enthusiasm to understand how excess adiposity causes vascular injury. Adipose tissue is an essential regulator of cardiovascular system through its endocrine and paracrine bioactive products. Obesity induces endothelial dysfunction, which often precedes and leads to the development of cardiovascular diseases. Connecting adipose tissue-endothelial cell interplay to endothelial dysfunction may help us to better understand obesity-induced cardiovascular disease. This Mini Review discussed (1) the general interactions and obesity-induced endothelial dysfunction, (2) potential targets, and (3) the outstanding questions for future research.

RNA modifications in cardiovascular diseases, the potential therapeutic targets

More than one hundred RNA modifications decorate the chemical and topological properties of these ribose nucleotides, thereby executing their biological functions through post-transcriptional regulation. In cardiovascular diseases, a wide range of RNA modifications including m⁶A (N6-adenosine methylation), m⁵C (5-methylcytidin), Nm (2'-O-ribose-methylation), Ψ (pseudouridine), m⁷G (N7-methylguanosine), and m¹A (N1-adenosine methylation) have been found in tRNA, rRNA, mRNA and other noncoding RNA, which can function as a novel mechanism in metabolic syndrome, heart failure, coronary heart disease, and hypertension. In this review, we will summarize the current understanding of the regulatory roles and significance of several types of RNA modifications in CVDs (cardiovascular diseases) and the interplay between RNA modifications and noncoding RNA, epigenetics. Finally, we will focus on the potential therapeutic strategies by using RNA modifications.

Shared genetic etiology and causality between body fat percentage and cardiovascular diseases: a large-scale genome-wide cross-trait analysis

BACKGROUND

Accumulating evidences have suggested that high body fat percentage (BF%) often occurs in parallel with cardiovascular diseases (CVDs), implying a common etiology between them. However, the shared genetic etiology underlying BF% and CVDs remains unclear.

METHODS

Using large-scale genome-wide association study (GWAS) data, we investigated shared genetics between BF% (N = 100,716) and 10 CVD-related traits (n = 6968-977,323) with linkage disequilibrium score regression, multi-trait analysis of GWAS, and transcriptome-wide association analysis, and evaluated causal associations using Mendelian randomization.

RESULTS

We found strong positive genetic correlations between BF% and heart failure (HF) (Rg = 0.47, P = 1.27 × 10^- 22) and coronary artery disease (CAD) (Rg = 0.22, P = 3.26 × 10^- 07). We identified 5 loci and 32 gene-tissue pairs shared between BF% and HF, as well as 16 loci and 28 gene-tissue pairs shared between BF% and CAD. The loci were enriched in blood vessels and brain tissues, while the gene-tissue pairs were enriched in the nervous, cardiovascular, and exo-/endocrine system. In addition, we observed that BF% was causally related with a higher risk of HF (odds ratio 1.63 per 1-SD increase in BF%, P = 4.16 × 10-04) using a MR approach.

CONCLUSIONS

Our findings suggest that BF% and CVDs have shared genetic etiology and targeted reduction of BF% may improve cardiovascular outcomes. This work advances our understanding of the genetic basis underlying co-morbid obesity and CVDs and opens up a new way for early prevention of CVDs.

RNA Modification by m6A Methylation in Cardiovascular Disease

Cardiovascular disease is currently the leading cause of death worldwide, and its underlying regulatory mechanisms remain largely unknown. N⁶-Methyladenosine (m⁶A) RNA methylation is an epigenetic modification involved in the splicing, nuclear export, translational regulation, and degradation of RNA. After the initial identification of m⁶A RNA methylation in 1974, the rise of next-generation sequencing technology to detect m⁶A throughout the transcriptome led to its renewed recognition in 2012. Since that time, m⁶A methylation has been extensively studied, and its functions, mechanisms, and effectors (e.g., METTL3, FTO, METTL14, WTAP, ALKBH5, and YTHDFs) in various diseases, including cardiovascular diseases, have rapidly been investigated. In this review, we first examine and summarize the molecular and cellular functions of m⁶A methylation and its readers, writers, and erasers in the cardiovascular system. Finally, we discuss future directions for m⁶A methylation research and the potential for therapeutic targeting of m⁶A modification in cardiovascular disease.

Cellular and Functional Effects of Insulin Based Therapies and Exercise on Endothelium

Endothelial dysfunction is a hallmark of type 2 diabetes that can have severe consequences on vascular function, including hypertension and changes in blood flow, as well as exercise performance. Because endothelium is also the barrier for insulin movement into tissues, it acts as a gatekeeper for transport and glucose uptake. For this reason, endothelial dysfunction is a tempting area for pharmacological and/or exercise intervention with insulin-based therapies. In this review, we describe the current state of drugs that can be used to treat endothelial dysfunction in type 2 diabetes and diabetes-related diseases (e.g., obesity) at the molecular levels, and also discuss their role in exercise.

The epitranscriptome of long noncoding RNAs in metabolic diseases

Long noncoding RNAs (lncRNAs) have abundant content and extensive functions that regulate the expression of genes at multiple levels. Recently, transcriptome-wide analysis confirmed that RNA can undergo various chemical modifications in response to stimulation by the environment that further determine the action mechanisms of RNAs and expand the diversity of the transcriptome. Modifications that occur in lncRNAs can affect their expression and the regulation of downstream molecules by changing the secondary structure, splicing, degradation or molecular stability of lncRNAs. During the development of metabolic diseases, reversible RNA modifications show a complex transcriptional landscape. Although a wide quantity and variety of lncRNA modifications have been identified, the knowledge regarding their underlying actions in alcohol use disorders (AUDs), osteoporosis, obesity, and cardiovascular disease (CVD) is still in its infancy. Herein, we will focus on the epitranscriptomic modifications that occur on lncRNAs and the crosstalk between them that affect metabolic diseases.

Vascular Smooth Muscle FTO Promotes Aortic Dissecting Aneurysms via m6A Modification of Klf5

Background: Aortic dissecting aneurysm (ADA) represents an aortic remodeling disease with a high mortality rate. Fat mass and obesity-associated protein (FTO) exerts RNA demethylation function to regulate gene expression related to stem cell differentiation, DNA damage repair, and tumorigenesis, but the role of FTO in ADA is still unclear.

Methods: The expression and location of FTO in 43 ADA tissues and 11 normal tissues were determined by RT-qPCR, WB, immunohistochemistry, and immunofluorescence staining. Detecting proliferation and migration of VSMCs. M6A methylated RNA immuno-precipitation qRT-PCR and dual luciferase reporter assay were performed for determining m6A level and interaction between m6A modulation and Klf5 mRNA, respectively.

Results: FTO are highly expressed in VSMCs. FTO was positively correlated with BMI, triglyceride, and D-dimer (all P < 0.05). Functionally, both AngII-induced FTO expression and over expression of FTO promote cell proliferation and migration, whereas knockdown of FTO inhibits these functions. Mechanically, we identified Krüppel-like factor 5 (Klf5) as a target of FTO mediating m6A modification. Overexpression of FTO reduced m6A modification on Klf5 mRNA and promoted Klf5 mRNA expression. Furthermore, the p-GSK3β and Klf5 levels increased after FTO overexpression. Finally, knockdown of FTO suppresses the p-GSK3β levels and Klf5 expression regardless of AngII treatment.

Conclusions: Our study revealed that FTO expression significantly contributes to the phenotype conversion of VSMCs and the ADA by the demethylation function (m6A), thereby providing a novel therapeutic target.

The critical roles of m6A modification in metabolic abnormality and cardiovascular diseases

N6-methyladenosine (m6A) RNA methylation is an emerging area of epigenetics, which is a reversible and dynamic modification mediating by ‘writers’ (methylase, adding methyl groups, METTL3, METTL14, and WTAP), ‘erasers’ (demethylase, deleting methyl groups, FTO and ALKBH5), and ‘readers’ (YTHDF1-3, YTHDC1 and YTHDC2). Recent studies in human, animal models and cell levels have disclosed a critical role of m6A modification in regulating the homeostasis of metabolic processes and cardiovascular function. Evidence from these studies identify m6A as a candidate of biomarker and therapeutic target for metabolic abnormality and cardiovascular diseases (CVD). Comprehensive understanding of the complexity of m6A regulation in metabolic diseases and CVD will be helpful for us to understand the pathogenesis of CVD. In this review, we discuss the regulatory role of m6A in metabolic abnormality and CVD. We will emphasize the clinical relevance of m6A dysregulation in CVD.