p300 in Cardiac Development and Accelerated Cardiac Aging

TRAP1 drives smooth muscle cell senescence and promotes atherosclerosis via HDAC3-primed histone H4 lysine 12 lactylation

BACKGROUND AND AIMS

Vascular smooth muscle cell (VSMC) senescence is crucial for the development of atherosclerosis, characterized by metabolic abnormalities. Tumour necrosis factor receptor-associated protein 1 (TRAP1), a metabolic regulator associated with ageing, might be implicated in atherosclerosis. As the role of TRAP1 in atherosclerosis remains elusive, this study aimed to examine the function of TRAP1 in VSMC senescence and atherosclerosis.

METHODS

TRAP1 expression was measured in the aortic tissues of patients and mice with atherosclerosis using western blot and RT-qPCR. Senescent VSMC models were established by oncogenic Ras, and cellular senescence was evaluated by measuring senescence-associated β-galactosidase expression and other senescence markers. Chromatin immunoprecipitation (ChIP) analysis was performed to explore the potential role of TRAP1 in atherosclerosis.

RESULTS

VSMC-specific TRAP1 deficiency mitigated VSMC senescence and atherosclerosis via metabolic reprogramming. Mechanistically, TRAP1 significantly increased aerobic glycolysis, leading to elevated lactate production. Accumulated lactate promoted histone H4 lysine 12 lactylation (H4K12la) by down-regulating the unique histone lysine delactylase HDAC3. H4K12la was enriched in the senescence-associated secretory phenotype (SASP) promoter, activating SASP transcription and exacerbating VSMC senescence. In VSMC-specific Trap1 knockout ApoeKO mice (ApoeKOTrap1SMCKO), the plaque area, senescence markers, H4K12la, and SASP were reduced. Additionally, pharmacological inhibition and proteolysis-targeting chimera (PROTAC)-mediated TRAP1 degradation effectively attenuated atherosclerosis in vivo.

CONCLUSIONS

This study reveals a novel mechanism by which mitonuclear communication orchestrates gene expression in VSMC senescence and atherosclerosis. TRAP1-mediated metabolic reprogramming increases lactate-dependent H4K12la via HDAC3, promoting SASP expression and offering a new therapeutic direction for VSMC senescence and atherosclerosis.

Role of transcriptional cofactors in cardiovascular diseases

Cardiovascular disease is a main cause of mortality in the world and the highest incidence of all diseases. However, the mechanism of the pathogenesis of cardiovascular disease is still unclear, and we need to continue to explore its mechanism of action. The occurrence and development of cardiovascular disease is significantly associated with genetic abnormalities, and gene expression is affected by transcriptional regulation. In this complex process, the protein-protein interaction promotes the RNA polymerase II to the initiation site. And in this process of transcriptional regulation, transcriptional cofactors are responsible for passing cues from enhancers to promoters and promoting the binding of RNA polymerases to promoters, so transcription cofactors playing a key role in gene expression regulation. There is growing evidence that transcriptional cofactors play a critical role in cardiovascular disease. Transcriptional cofactors can promote or inhibit transcription by affecting the function of transcription factors. It can affect the initiation and elongation process of transcription by forming complexes with transcription factors, which are important for the stabilization of DNA rings. It can also act as a protein that interacts with other proteins to affect the expression of other genes. Therefore, the aim of this overview is to summarize the effect of some transcriptional cofactors such as BRD4, EP300, MED1, EZH2, YAP, SIRT6 in cardiovascular disease and to provide a promising therapeutic strategy for the treatment of cardiovascular disease.

Protein lysine acetyltransferase CBP/p300: A promising target for small molecules in cancer treatment

CBP and p300 are homologous proteins exhibiting remarkable structural and functional similarity. Both proteins function as acetyltransferase and coactivator, underscoring their significant roles in cellular processes. The function of histone acetyltransferases is to facilitate the release of DNA from nucleosomes and act as transcriptional co-activators to promote gene transcription. Transcription factors recruit CBP/p300 by co-condensation and induce transcriptional bursting. Disruption of CBP or p300 functions is associated with different diseases, especially cancer, which can result from either loss of function or gain of function. CBP and p300 are multidomain proteins containing HAT (histone acetyltransferase) and BRD (bromodomain) domains, which perform acetyltransferase activity and maintenance of HAT signaling, respectively. Inhibitors targeting HAT and BRD have been explored for decades, and some BRD inhibitors have been evaluated in clinical trials for treating hematologic malignancies or advanced solid tumors. Here, we review the development and application of CBP/p300 inhibitors. Several inhibitors have been evaluated in vivo, exhibiting notable potency but limited selectivity. Exploring these inhibitors emphasizes the promise of targeting CBP and p300 with small molecules in cancer therapy.

Involvement of plasminogen activator inhibitor-1 in p300/p53-mediated age-related atrial fibrosis

Plasminogen activator inhibitor-1 (PAI-1), a key regulator of the fibrinolytic system, is also intimately involved in the fibrosis. Although PAI-1 may be involved in the occurrence of atrial fibrillation (AF) and thrombosis in the elderly, but whether it participated in aging-related atrial fibrosis and the detailed mechanism is still unclear. We compared the transcriptomics data of young (passage 4) versus senescent (passage 14) human atrial fibroblasts and found that PAI-1 was closely related to aging-related fibrosis. Aged mice and senescent human and mouse atrial fibroblasts underwent electrophysiological and biochemical studies. We found that p300, p53, and PAI-1 protein expressions were increased in the atrial tissue of aged mice and senescent human and mouse atrial fibroblasts. Curcumin or C646 (p300 inhibitor), or p300 knockdown inhibited the expression of PAI-1 contributing to reduced atrial fibroblasts senescence, atrial fibrosis, and the AF inducibility. Furthermore, p53 knockdown decreased the protein expression of PAI-1 and p21 in senescent human and mouse atrial fibroblasts. Our results suggest that p300/p53/PAI-1 signaling pathway participates in the mechanism of atrial fibrosis induced by aging, which provides new sights into the treatment of elderly AF.

Unlocking the secrets of aging: Epigenetic reader BRD4 as the target to combatting aging-related diseases

BACKGROUND

Aging, a complex and profound journey, leads us through a labyrinth of physiological and pathological transformations, rendering us increasingly susceptible to aging-related diseases. Emerging investigations have unveiled the function of bromodomain containing protein 4 (BRD4) in manipulating the aging process and driving the emergence and progression of aging-related diseases.

AIM OF REVIEW

This review aims to offer a comprehensive outline of BRD4's functions involved in the aging process, and potential mechanisms through which BRD4 governs the initiation and progression of various aging-related diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

BRD4 has a fundamental role in regulating the cell cycle, apoptosis, cellular senescence, the senescence-associated secretory phenotype (SASP), senolysis, autophagy, and mitochondrial function, which are involved in the aging process. Several studies have indicated that BRD4 governs the initiation and progression of various aging-related diseases, including Alzheimer's disease, ischemic cerebrovascular diseases, hypertension, atherosclerosis, heart failure, aging-related pulmonary fibrosis, and intervertebral disc degeneration (IVDD). Thus, the evidence from this review supports that BRD4 could be a promising target for managing various aging-related diseases, while further investigation is warranted to gain a thorough understanding of BRD4's role in these diseases.

A Small De Novo CNV Deletion of the Paternal Copy of FOXF1, Leaving lncRNA FENDRR Intact, Provides Insight into Their Bidirectional Promoter Region

Pathogenic single-nucleotide variants (SNVs) and copy-number variant (CNV) deletions involving the FOXF1 transcription factor gene or CNV deletions of its distant lung-specific enhancer are responsible for alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a rarely diagnosed lethal lung developmental disorder in neonates. In contrast to SNVs within FOXF1 and CNV deletions involving only the FOXF1 enhancer, larger-sized deletions involving FOXF1 and the adjacent, oppositely oriented lncRNA gene FENDRR have additionally been associated with hypoplastic left heart syndrome and single umbilical artery (SUA). Here, in an ACDMPV infant without any congenital heart defect or SUA, we identified a small 5 kb CNV deletion that removed the paternal allele of FOXF1 and its promoter, leaving FENDRR and its promoter intact. Reporter assay in the IMR-90 fetal cell line implied that the deletion may indeed not have significantly affected FENDRR expression. It also showed a polarization of the FOXF1-FENDRR inter-promoter region consisting of its ability to increase the transcription of FENDRR but not FOXF1. Interestingly, this transcription-stimulating activity was suppressed in the presence of the FOXF1 promoter. Our data shed more light on the interactions between neighboring promoters of FOXF1-FENDRR and possibly other divergently transcribed mRNA-lncRNA gene pairs.

Cigarette smoke extract induces the senescence of endothelial progenitor cells by upregulating p300

INTRODUCTION

Endothelial progenitor cells (EPCs) are the main source of endothelial cells. The senescence of EPCs is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cigarette smoke extract (CSE) can directly induce the dysfunction and increased expression of senescence-related markers in EPCs cultured in vitro. Histone acetyltransferase p300 is a transcriptional activator, and its changes can lead to cell senescence. The present study investigated whether CSE can induce the senescence of EPCs by upregulating p300.

METHODS

EPCs were isolated from bone marrow of C57BL/6J mice by density gradient centrifugation. The p300 inhibitor C646 and agonist CTPB were used to interfere with EPCs, cell cycle and apoptosis were detected by flow cytometry, the proportion of senile cells was counted by β-galactosidase staining, the protein expression of p300, H4K12, Cyclin D1, TERT and Ki67 were detected by western blot.

RESULTS

Compared with the control group, the cell cycle of CSE group and CTPB group were blocked, the apoptosis rate and early apoptosis rate were increased, the proportion of senile cells counted by β-galactosidase staining was increased, the expression of p300 and H4K12 protein were increased, the expression of Cyclin D1, TERT and Ki67 protein were decreased. C646 could partly alleviate the damages caused by CSE.

CONCLUSIONS

CSE may promote the apoptosis and senescence of EPCs by upregulating the expression of p300 and H4K12 protein, thus preventing the transition of EPCs from G1 phase to S phase, affecting telomerase synthesis, and reducing EPCs proliferation.

Cardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies

Heart failure is a leading cause of mortality and hospitalization worldwide. Cardiac fibrosis, resulting from the excessive deposition of collagen fibers, is a common feature across the spectrum of conditions converging in heart failure. Eventually, either reparative or reactive in nature, in the long-term cardiac fibrosis contributes to heart failure development and progression and is associated with poor clinical outcomes. Despite this, specific cardiac antifibrotic therapies are lacking, making cardiac fibrosis an urgent unmet medical need. In this context, a better patient phenotyping is needed to characterize the heterogenous features of cardiac fibrosis to advance toward its personalized management. In this review, we will describe the different phenotypes associated with cardiac fibrosis in heart failure and we will focus on the potential usefulness of imaging techniques and circulating biomarkers for the non-invasive characterization and phenotyping of this condition and for tracking its clinical impact. We will also recapitulate the cardiac antifibrotic effects of existing heart failure and non-heart failure drugs and we will discuss potential strategies under preclinical development targeting the activation of cardiac fibroblasts at different levels, as well as targeting additional extracardiac processes.

Epigenetic Regulation of Fibroblasts and Crosstalk between Cardiomyocytes and Non-Myocyte Cells in Cardiac Fibrosis

Epigenetic mechanisms and cell crosstalk have been shown to play important roles in the initiation and progression of cardiac fibrosis. This review article aims to provide a thorough overview of the epigenetic mechanisms involved in fibroblast regulation. During fibrosis, fibroblast epigenetic regulation encompasses a multitude of mechanisms, including DNA methylation, histone acetylation and methylation, and chromatin remodeling. These mechanisms regulate the phenotype of fibroblasts and the extracellular matrix composition by modulating gene expression, thereby orchestrating the progression of cardiac fibrosis. Moreover, cardiac fibrosis disrupts normal cardiac function by imposing myocardial mechanical stress and compromising cardiac electrical conduction. This review article also delves into the intricate crosstalk between cardiomyocytes and non-cardiomyocytes in the heart. A comprehensive understanding of the mechanisms governing epigenetic regulation and cell crosstalk in cardiac fibrosis is critical for the development of effective therapeutic strategies. Further research is warranted to unravel the precise molecular mechanisms underpinning these processes and to identify potential therapeutic targets.

Bibliometric analysis of trends in cardiac aging research over the past 20 years

BACKGROUND

In recent years, many studies have addressed cardiac aging and related diseases. This study aims to understand the research trend of cardiac aging and find new hot issues.

METHODS

We searched the web of science core collection database for articles published between 2003 and 2022 on the topic of "cardiac aging." Complete information including keywords, publication year, journal title, country, organization, and author were extracted for analysis. The VOS viewer software was used to generate network maps of keywords, countries, institutions, and author relationships for visual network analysis.

RESULTS

A total of 1002 papers were analyzed in the study. Overall, the number of annual publications on cardiac aging has increased since 2009, and new hot topics are emerging. The top 3 countries with the most publications were the United States (471 articles), China (209 articles) and Italy (101 articles). The University of Washington published the most papers (35 articles). The cluster analysis with author as the keyword found that the connections among different scholars are scattered and clustered in a small range. Network analysis based on keyword co-occurrence and year of publication identified relevant features and trends in cardiac aging research. According to the results of cluster analysis, all the articles are divided into 4 topics: "mechanisms of cardiac aging", "prevention and treatment of cardiac aging", "characteristics of cardiac aging", and "others." In recent years, the mechanism and treatment of cardiac aging have attracted the most attention. In both studies, animal models are used more often than in human populations. Mitochondrial dysfunction, autophagy and mitochondrial autophagy are hotspots in current research.

CONCLUSION

In this study, bibliometric analysis was used to analyze the research trend of cardiac aging in the past 20 years. The mechanism and treatment of cardiac aging are the most concerned contents. Mitochondrial dysfunction, autophagy and mitophagy are the focus of future research on cardiac aging.

Review: Acetylation Mechanisms andTargeted Therapies in Cardiac Fibrosis

Cardiac fibrosis is a common pathophysiological remodeling process that occurs in a variety of cardiovascular diseases and greatly influences heart structure and function, progressively leading to the development of heart failure. However, to date, few effective therapies for cardiac fibrosis exist. Abnormal proliferation, differentiation, and migration of cardiac fibroblasts are responsible for the excessive deposition of extracellular matrix in the myocardium. Acetylation, a widespread and reversible protein post-translational modification, plays an important role in the development of cardiac fibrosis by adding acetyl groups to lysine residues. Many acetyltransferases and deacetylases regulate the dynamic alterations of acetylation in cardiac fibrosis, regulating a range of pathogenic conditions including oxidative stress, mitochondrial dysfunction, and energy metabolism disturbance. In this review, we demonstrate the critical roles that acetylation modifications caused by different types of pathological injury play in cardiac fibrosis. Furthermore, we propose therapeutic acetylation-targeting strategies for the prevention and treatment of patients with cardiac fibrosis.

Metabolic Changes in Cardiac Aging

Cardiac aging is a natural process accompanied by cardiomyocyte hypertrophy and dysfunction. These changes can lead to adverse organ remodeling and ultimately lead to the development of heart failure. The study of cardiac aging is helpful to explore the mechanism of senescence and is of great significance for preventing cardiac aging. Cardiac aging is accompanied by changes in various metabolic functions. In this process, due to the change of metabolic substrates and enzyme activities, oxidative stress response increases, and reactive oxygen species (ROS) increases, accompanied by mitochondrial dysfunction and gene expression changes, so related protein metabolism also changes. Hormone metabolism and autophagy are also involved in the process of cardiac aging. Based on these findings, changes in diet, caloric restriction, improvement of mitochondrial function and promotion of autophagy have been proven to have positive effects in delaying cardiac aging. This article reviews the metabolic changes involved in the process of cardiac aging from different aspects, and briefly reviews the measures to improve cardiac aging.

Effects of the Acetyltransferase p300 on Tumour Regulation from the Novel Perspective of Posttranslational Protein Modification

p300 acts as a transcription coactivator and an acetyltransferase that plays an important role in tumourigenesis and progression. In previous studies, it has been confirmed that p300 is an important regulator in regulating the evolution of malignant tumours and it also has extensive functions. From the perspective of non-posttranslational modification, it has been proven that p300 can participate in regulating many pathophysiological processes, such as activating oncogene transcription, promoting tumour cell growth, inducing apoptosis, regulating immune function and affecting embryo development. In recent years, p300 has been found to act as an acetyltransferase that catalyses a variety of protein modification types, such as acetylation, propanylation, butyylation, 2-hydroxyisobutyration, and lactylation. Under the catalysis of this acetyltransferase, it plays its crucial tumourigenic driving role in many malignant tumours. Therefore, the function of p300 acetyltransferase has gradually become a research hotspot. From a posttranslational modification perspective, p300 is involved in the activation of multiple transcription factors and additional processes that promote malignant biological behaviours, such as tumour cell proliferation, migration, and invasion, as well as tumour cell apoptosis, drug resistance, and metabolism. Inhibitors of p300 have been developed and are expected to become novel anticancer drugs for several malignancies. We review the characteristics of the p300 protein and its functional role in tumour from the posttranslational modification perspective, as well as the current status of p300-related inhibitor research, with a view to gaining a comprehensive understanding of p300.

Emerging epigenetic therapies of cardiac fibrosis and remodelling in heart failure: from basic mechanisms to early clinical development

Cardiovascular diseases and specifically heart failure (HF) impact global health and impose a significant economic burden on society. Despite current advances in standard of care, the risks for death and readmission of HF patients remain unacceptably high and new therapeutic strategies to limit HF progression are highly sought. In disease settings, persistent mechanical or neurohormonal stress to the myocardium triggers maladaptive cardiac remodelling, which alters cardiac function and structure at both the molecular and cellular levels. The progression and magnitude of maladaptive cardiac remodelling ultimately leads to the development of HF. Classical therapies for HF are largely protein-based and mostly are targeted to ameliorate the dysregulation of neuroendocrine pathways and halt adverse remodelling. More recently, investigation of novel molecular targets and the application of cellular therapies, epigenetic modifications, and regulatory RNAs has uncovered promising new avenues to address HF. In this review, we summarize the current knowledge on novel cellular and epigenetic therapies and focus on two non-coding RNA-based strategies that reached the phase of early clinical development to counteract cardiac remodelling and HF. The current status of the development of translating those novel therapies to clinical practice, limitations, and future perspectives are additionally discussed.

Diabetes and Its Cardiovascular Complications: Potential Role of the Acetyltransferase p300

Diabetes has been shown to accelerate vascular senescence, which is associated with chronic inflammation and oxidative stress, both implicated in the development of endothelial dysfunction. This condition represents the initial alteration linking diabetes to related cardiovascular (CV) complications. Recently, it has been hypothesised that the acetyltransferase, p300, may contribute to establishing an early vascular senescent phenotype, playing a relevant role in diabetes-associated inflammation and oxidative stress, which drive endothelial dysfunction. Specifically, p300 can modulate vascular inflammation through epigenetic mechanisms and transcription factors acetylation. Indeed, it regulates the inflammatory pathway by interacting with nuclear factor kappa-light-chain-enhancer of activated B cells p65 subunit (NF-κB p65) or by inducing its acetylation, suggesting a crucial role of p300 as a bridge between NF-κB p65 and the transcriptional machinery. Additionally, p300-mediated epigenetic modifications could be upstream of the activation of inflammatory cytokines, and they may induce oxidative stress by affecting the production of reactive oxygen species (ROS). Because several in vitro and in vivo studies shed light on the potential use of acetyltransferase inhibitors, a better understanding of the mechanisms underlying the role of p300 in diabetic vascular dysfunction could help in finding new strategies for the clinical management of CV diseases related to diabetes.

Smooth muscle mineralocorticoid receptor as an epigenetic regulator of vascular ageing

AIMS

Vascular stiffness increases with age and independently predicts cardiovascular disease risk. Epigenetic changes, including histone modifications, accumulate with age but the global pattern has not been elucidated nor are the regulators known. Smooth muscle cell-mineralocorticoid receptor (SMC-MR) contributes to vascular stiffness in ageing mice. Thus, we investigated the regulatory role of SMC-MR in vascular epigenetics and stiffness.

METHODS AND RESULTS

Mass spectrometry-based proteomic profiling of all histone modifications completely distinguished 3 from 12-month-old mouse aortas. Histone-H3 lysine-27 (H3K27) methylation (me) significantly decreased in ageing vessels and this was attenuated in SMC-MR-KO littermates. Immunoblotting revealed less H3K27-specific methyltransferase EZH2 with age in MR-intact but not SMC-MR-KO vessels. These ageing changes were examined in primary human aortic (HA)SMC from adult vs. aged donors. MR, H3K27 acetylation (ac), and stiffness gene (connective tissue growth factor, integrin-α5) expression significantly increased, while H3K27me and EZH2 decreased, with age. MR inhibition reversed these ageing changes in HASMC and the decline in stiffness genes was prevented by EZH2 blockade. Atomic force microscopy revealed that MR antagonism decreased intrinsic stiffness and the probability of fibronectin adhesion of aged HASMC. Conversely, ageing induction in young HASMC with H2O2; increased MR, decreased EZH2, enriched H3K27ac and MR at stiffness gene promoters by chromatin immunoprecipitation, and increased stiffness gene expression. In 12-month-old mice, MR antagonism increased aortic EZH2 and H3K27 methylation, increased EZH2 recruitment and decreased H3K27ac at stiffness genes promoters, and prevented ageing-induced vascular stiffness and fibrosis. Finally, in human aortic tissue, age positively correlated with MR and stiffness gene expression and negatively correlated with H3K27me3 while MR and EZH2 are negatively correlated.

CONCLUSION

These data support a novel vascular ageing model with rising MR in human SMC suppressing EZH2 expression thereby decreasing H3K27me, promoting MR recruitment and H3K27ac at stiffness gene promoters to induce vascular stiffness and suggests new targets for ameliorating ageing-associated vascular disease.

Targeting epigenetics in diabetic cardiomyopathy: Therapeutic potential of flavonoids

The pathophysiological mechanisms of diabetic cardiomyopathy have been extensively studied, but there is still a lack of effective prevention and treatment methods. The ability of flavonoids to protect the heart from diabetic cardiomyopathy has been extensively described. In recent years, epigenetics has received increasing attention from scholars in exploring the etiology and treatment of diabetes and its complications. DNA methylation, histone modifications and non-coding RNAs play key functions in the development, maintenance and progression of diabetic cardiomyopathy. Hence, prevention or reversal of the epigenetic alterations that have occurred during the development of diabetic cardiomyopathy may alleviate the personal and social burden of the disease. Flavonoids can be used as natural epigenetic modulators in alternative therapies for diabetic cardiomyopathy. In this review, we discuss the epigenetic effects of different flavonoid subtypes in diabetic cardiomyopathy and summarize the evidence from preclinical and clinical studies that already exist. However, limited research is available on the potential beneficial effects of flavonoids on the epigenetics of diabetic cardiomyopathy. In the future, clinical trials in which different flavonoids exert their antidiabetic and cardioprotective effects through various epigenetic mechanisms should be further explored.

Rg3 regulates myocardial pyruvate metabolism via P300-mediated dihydrolipoamide dehydrogenase 2-hydroxyisobutyrylation in TAC-induced cardiac hypertrophy

The failing heart is characterized by an increase in glucose uptake and glycolytic rates that is not accompanied by a concomitant increase in glucose oxidation. Lower coupling of glucose oxidation to glycolysis possibly owes to unchanged or reduced pyruvate oxidation in mitochondria. Therefore, increasing pyruvate oxidation may lead to new therapies for heart disease. Dihydrolipoamide dehydrogenase (DLD) is a component of the pyruvate dehydrogenase complex (PDH). DLD mutations or defects are closely associated with metabolic diseases. However, few studies explore the effects of DLD mutants or acylation status on PDH activity and pyruvate metabolism. P300 is protein 2-hydroxyisobutyryltransferases in cells, and P300-dependent lysine 2-hydroxyisobutyrylation of glycolytic enzymes affects glucose metabolism. However, there are no relevant reports on the effect of 2-hydroxyisobutyrylation on the energy metabolism of heart failure, and it is worth further in-depth study. In this study, we showed that 2-hydroxyisobutyrylation is an essential protein translational modification (PTM) that regulates the activity of pyruvate dehydrogenase complex (PDHc). In a mouse model of transverse aortic constriction (TAC)-induced cardiac hypertrophy, the 2-hydroxyisobutylation of DLD was significantly increased, related to the decrease in PDH activity. In addition, our data provide clear evidence that DLD is a direct substrate of P300. As one of the main active ingredients of ginseng, ginsenoside Rg3 (Rg3) can reduce the 2-hydroxyisobutylation levels of DLD and restore the PDH activity by inhibiting the acyltransferase activity of P300, thereby producing beneficial effects whenever the heart is injured. Therefore, this study suggests a novel strategy for reversing myocardial hypertrophy.

Acetyltransferase p300 regulates atrial fibroblast senescence and age-related atrial fibrosis through p53/Smad3 axis

Atrial fibrosis induced by aging is one of the main causes of atrial fibrillation (AF), but the potential molecular mechanism is not clear. Acetyltransferase p300 participates in the cellular senescence and fibrosis, which might be involved in the age-related atrial fibrosis. Four microarray datasets generated from atrial tissue of AF patients and sinus rhythm (SR) controls were analyzed to find the possible relationship of p300 (EP300) with senescence and fibrosis. And then, biochemical assays and in vivo electrophysiological examination were performed on older AF patients, aging mice, and senescent atrial fibroblasts. The results showed that (1) the left atrial tissues of older AF patients, aging mouse, and senescence human atrial fibroblasts had more severe atrial fibrosis and higher protein expression levels of p300, p53/acetylated p53 (ac-p53)/p21, Smad3/p-Smads, and fibrosis-related factors. (2) p300 inhibitor curcumin and p300 knockdown treated aging mouse and senescence human atrial fibroblasts reduced the senescence ratio of atrial fibroblasts, ameliorated the atrial fibrosis, and decreased the AF inducibility. In contrast, over-expression of p300 can lead to the senescence of atrial fibroblasts and atrial fibrosis. (3) p53 knockdown decreased the expression of aging and fibrosis-related proteins. (4) Co-immunoprecipitation and immunofluorescence showed that p53 forms a complex with smad3 and directly regulates the expression of smad3 in atrial fibroblasts. Our findings suggest that the mechanism of atrial fibrosis induced by aging is, at least, partially dependent on the regulation of p300, which provides new sights into the AF treatment, especially for the elderly.

Effects of RAGE Deletion on the Cardiac Transcriptome during Aging

Cardiac aging is characterized by increased cardiomyocyte hypertrophy, myocardial stiffness, and fibrosis, which enhance cardiovascular risk. The receptor for advanced glycation end-products (RAGE) is involved in several age-related diseases. RAGE knockout (Rage−/−) mice show an acceleration of cardiac dimension changes and interstitial fibrosis with aging. This study identifies the age-associated cardiac gene expression signature induced by RAGE deletion. We analyzed the left ventricle transcriptome of 2.5-(Young), 12-(Middle age, MA), and 21-(Old) months-old female Rage−/− and C57BL/6N (WT) mice. By comparing Young, MA, and Old Rage−/− versus age-matched WT mice, we identified 122, 192, and 12 differently expressed genes, respectively. Functional inference analysis showed that RAGE deletion is associated with: (i) down-regulation of genes involved in antigen processing and presentation of exogenous antigen, adaptive immune response, and cellular responses to interferon beta and gamma in Young animals; (ii) up-regulation of genes related to fatty acid oxidation, cardiac structure remodeling and cellular response to hypoxia in MA mice; (iii) up-regulation of few genes belonging to complement activation and triglyceride biosynthetic process in Old animals. Our findings show that the age-dependent cardiac phenotype of Rage−/− mice is associated with alterations of genes related to adaptive immunity and cardiac stress pathways.

EP300 promotes renal tubular epithelial cell fibrosis by increasing HIF2α expression in diabetic nephropathy

Renal tubular damage occurs early in diabetic nephropathy (DN) and may play a key role in the progression of kidney disease. E1A binding protein P300 (EP300) gene polymorphism correlates with the development and advancement of DN. We will explore the expression and relationship of EP300 and hypoxia-inducible factor 2 α (HIF2α) and the possible mechanism in the progression of DN. We studied the expression of EP300 and HIF2α in the renal tubules of patients with DN. At the cellular level, the interaction between EP300 and HIF2α were identified, and their relationship with cellular fibrosis was validated. Furthermore, we examined the effect of altered EP300 expression on downstream HIF2α and renal tubular fibrosis in vivo and in vitro. EP300 and HIF2α were strongly expressed in the renal tubules of DN patients and in HK-2 cells, and EP300 protein bound to the HIF2α gene in the nucleus. Adenovirus-mediated EP300 inhibition or overexpression downregulated or upregulated HIF2α expression in HK-2 cells, respectively. When EP300 was overexpressed in HK-2 cells, inhibition of HIF2α did not change the EP300 level, but the fibrotic marker was downregulated. In DN mice, silencing EP300 inhibited HIF2α expression levels and renal tubular fibrosis progression. In conclusion, this study defined that EP300 could promote renal tubular epithelial cell fibrotic processes by increasing HIF2α expression in DN.

Nicotinamide Mononucleotide Alleviates Cardiomyopathy Phenotypes Caused by Short-Chain Enoyl-Coa Hydratase 1 Deficiency

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ECHS1 hydrates medium- and short-chain enoyl CoAs and catalyzes the oxidation of fatty acids and branched-chain amino acids.

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The mechanism driving ECHS1 deficiency–associated cardiomyopathy was investigated using conventional biochemistry and molecular biology methods, including immunoprecipitation and polymerase chain reaction.

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Echs1 heterogeneous knockout mice displayed cardiac dysfunction as evaluated by echocardiography.

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ECHS1 deficiency causes cardiomyopathy by enhancing p300-mediated H3K9ac.

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ECHS1 deficiency–induced cardiomyopathy can be prevented using an intervention approach targeting H3K9ac.

Short-chain enoyl-CoA hydratase 1 (ECHS1) deficiency plays a role in cardiomyopathy. Whether ECHS1 deficiency causes or is only associated with cardiomyopathy remains unclear. By using Echs1 heterogeneous knockout (Echs1^+/-) mice, we found that ECHS1 deficiency caused cardiac dysfunction, as evidenced by diffuse myocardial fibrosis and upregulated fibrosis-related genes. Mechanistically, ECHS1 interacts with the p300 nuclear localization sequence, preventing its nuclear translocation in fibroblasts. ECHS1 deficiency promotes p300 nuclear translocation, leading to increased H3K9 acetylation, a known risk factor for cardiomyopathy. Nicotinamide mononucleotide–mediated acetylation targeting suppressed ECHS1 deficiency–induced cardiomyopathy phenotypes in Echs1^+/- mice. Thus, enhancing p300-mediated H3K9ac is a potential interventional approach for preventing ECHS1 deficiency–induced cardiomyopathy.

Harnessing the Power of Stem Cell Models to Study Shared Genetic Variants in Congenital Heart Diseases and Neurodevelopmental Disorders

Advances in human pluripotent stem cell (hPSC) technology allow one to deconstruct the human body into specific disease-relevant cell types or create functional units representing various organs. hPSC-based models present a unique opportunity for the study of co-occurring disorders where “cause and effect” can be addressed. Poor neurodevelopmental outcomes have been reported in children with congenital heart diseases (CHD). Intuitively, abnormal cardiac function or surgical intervention may stunt the developing brain, leading to neurodevelopmental disorders (NDD). However, recent work has uncovered several genetic variants within genes associated with the development of both the heart and brain that could also explain this co-occurrence. Given the scalability of hPSCs, straightforward genetic modification, and established differentiation strategies, it is now possible to investigate both CHD and NDD as independent events. We will first overview the potential for shared genetics in both heart and brain development. We will then summarize methods to differentiate both cardiac & neural cells and organoids from hPSCs that represent the developmental process of the heart and forebrain. Finally, we will highlight strategies to rapidly screen several genetic variants together to uncover potential phenotypes and how therapeutic advances could be achieved by hPSC-based models.

Mesenchymal Stem Cell Therapy in Diabetic Cardiomyopathy

The incidence and prevalence of diabetes mellitus (DM) are increasing worldwide, and the resulting cardiac complications are the leading cause of death. Among these complications is diabetes-induced cardiomyopathy (DCM), which is the consequence of a pro-inflammatory condition, oxidative stress and fibrosis caused by hyperglycemia. Cardiac remodeling will lead to an imbalance in cell survival and death, which can promote cardiac dysfunction. Since the conventional treatment of DM generally does not address the prevention of cardiac remodeling, it is important to develop new alternatives for the treatment of cardiovascular complications induced by DM. Thus, therapy with mesenchymal stem cells has been shown to be a promising approach for the prevention of DCM because of their anti-apoptotic, anti-fibrotic and anti-inflammatory effects, which could improve cardiac function in patients with DM.

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.

Protein acetylation in cardiac aging

Biological aging is attributed to progressive dysfunction in systems governing genetic and metabolic integrity. At the cellular level, aging is evident by accumulated DNA damage and mutation, reactive oxygen species, alternate lipid and protein modifications, alternate gene expression programs, and mitochondrial dysfunction. These effects sum to drive altered tissue morphology and organ dysfunction. Protein-acylation has emerged as a critical mediator of age-dependent changes in these processes. Despite decades of research focus from academia and industry, heart failure remains a leading cause of death in the United States while the 5 year mortality rate for heart failure remains over 40%. Over 90% of heart failure deaths occur in patients over the age of 65 and heart failure is the leading cause of hospitalization in Medicare beneficiaries. In 1931, Cole and Koch discovered age-dependent accumulation of phosphates in skeletal muscle. These and similar findings provided supporting evidence for, now well accepted, theories linking metabolism and aging. Nearly two decades later, age-associated alterations in biochemical molecules were described in the heart. From these small beginnings, the field has grown substantially in recent years. This growing research focus on cardiac aging has, in part, been driven by advances on multiple public health fronts that allow population level clinical presentation of aging related disorders. It is estimated that by 2030, 25% of the worldwide population will be over the age of 65. This review provides an overview of acetylation-dependent regulation of biological processes related to cardiac aging and introduces emerging non-acetyl, acyl-lysine modifications in cardiac function and aging.

Inhibition of p300 by Garcinol Protects against Cisplatin-Induced Acute Kidney Injury through Suppression of Oxidative Stress, Inflammation, and Tubular Cell Death in Mice

Emerging evidence suggests that epigenetic mechanisms such as histone modification are crucially involved in the pathophysiology of acute kidney injury (AKI). The histone acetyltransferase p300 regulates several biological processes through the acetylation of histones or transcription factors. However, the role of p300 in cisplatin-induced AKI remains poorly understood. Therefore, we investigated the effects of garcinol, a potent p300 inhibitor, on cisplatin-induced AKI and explored the mechanisms. Administration of garcinol significantly reversed the upregulation of p300 and increased acetylation of histone H3, along with amelioration of renal dysfunction and histopathological injury in the kidneys of cisplatin-injected mice. Garcinol also attenuated oxidative stress and reduced expression of pro-oxidant enzymes. In addition, garcinol reduced the elevated production of cytokines and chemokines and suppressed immune cell accumulation together with downregulation of vascular adhesion molecules. These beneficial effects of garcinol were associated with a reduction in acetylation of the p65 subunit of nuclear factor kappa-B. Further, garcinol significantly inhibited apoptosis and caspase-3 activation, with a decrease in p53 acetylation in cisplatin-injected mice. Taken together, we demonstrated that the inhibition of p300 by garcinol ameliorated cisplatin-induced renal injury, presumably through epigenetic mechanisms. These results suggest that garcinol might be a potential preventive agent for cisplatin-induced AKI.