Histone Acetyltransferases p300 and CBP Coordinate Distinct Chromatin Remodeling Programs in Vascular Smooth Muscle Plasticity

Stasis and Inflammation in Varicose Vein Development: An Interleukin-Mediated Process from Intima to Media

INTRODUCTION

This study investigated the combination of venous stasis and inflammation in varicose vein development.

METHODS

The study included patients with primary varicose veins operated using high ligation and stripping of greater saphenous vein. All of them showed reflux at sapheno-femoral junction on preoperative Doppler ultrasound. Mesenteric veins from early or advanced gastric cancer specimens were used as control group. Inflammatory mediators expressed in the venous wall were measured via immunohistochemistry and compared between the two groups.

RESULTS

Thirty-five (59.3%) men and 24 women with a mean age of 52.8 years (range, 23-77 years) were included and 29 (49.2%) patients had edema or skin changes according to Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification and reporting standards for chronic venous disorders. The expression of interleukin 6 (IL-6) and transforming growth factor β1 (TGF-β1) in intima and those of IL-6 in media of greater saphenous veins increased, with statistically significant differences between the two groups (p < 0.001). IL-6 in media and TGF-β1 levels in intima were independent predictors of varicose veins (adjusted odds ratios 74.62 and 66.69, respectively).

CONCLUSION

Elevated venous pressure represented by reflux on Doppler ultrasound and increased expression of inflammatory cytokines including IL-6 in media and TGF-β1 in intima are associated with the development of varicose veins.

Genome-Wide Methylation Analysis Reveals a KCNK3-Prominent Causal Cascade on Hypertension

BACKGROUND

Despite advances in understanding hypertension's genetic structure, how noncoding genetic variants influence it remains unclear. Studying their interaction with DNA methylation is crucial to deciphering this complex disease's genetic mechanisms.

METHODS

We investigated the genetic and epigenetic interplay in hypertension using whole-genome bisulfite sequencing. Methylation profiling in 918 males revealed allele-specific methylation and methylation quantitative trait loci. We engineered rs1275988T/C mutant mice using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9), bred them for homozygosity, and subjected them to a high-salt diet. Telemetry captured their cardiovascular metrics. Protein-DNA interactions were elucidated using DNA pull-downs, mass spectrometry, and Western blots. A wire myograph assessed vascular function, and analysis of the Kcnk3 gene methylation highlighted the mutation's role in hypertension.

RESULTS

We discovered that DNA methylation-associated genetic effects, especially in non-cytosine-phosphate-guanine (non-CpG) island and noncoding distal regulatory regions, significantly contribute to hypertension predisposition. We identified distinct methylation quantitative trait locus patterns in the hypertensive population and observed that the onset of hypertension is influenced by the transmission of genetic effects through the demethylation process. By evidence-driven prioritization and in vivo experiments, we unearthed rs1275988 in a cell type-specific enhancer as a notable hypertension causal variant, intensifying hypertension through the modulation of local DNA methylation and consequential alterations in Kcnk3 gene expression and vascular remodeling. When exposed to a high-salt diet, mice with the rs1275988C/C genotype exhibited exacerbated hypertension and significant vascular remodeling, underscored by increased aortic wall thickness. The C allele of rs1275988 was associated with elevated DNA methylation levels, driving down the expression of the Kcnk3 gene by attenuating Nr2f2 (nuclear receptor subfamily 2 group F member 2) binding at the enhancer locus.

CONCLUSIONS

Our research reveals new insights into the complex interplay between genetic variations and DNA methylation in hypertension. We underscore hypomethylation's potential in hypertension onset and identify rs1275988 as a causal variant in vascular remodeling. This work advances our understanding of hypertension's molecular mechanisms and encourages personalized health care strategies.

Epigenetic Alteration of Smooth Muscle Cells Regulates Endothelin-Dependent Blood Pressure and Hypertensive Arterial Remodeling

Long-standing hypertension (HTN) affects multiple organ systems and leads to pathologic arterial remodeling, which is driven largely by smooth muscle cell (SMC) plasticity. Although genome wide association studies (GWAS) have identified numerous variants associated with changes in blood pressure in humans, only a small percentage of these variants actually cause HTN. In order to identify relevant genes important in SMC function in HTN, we screened three separate human GWAS and Mendelian randomization studies to identify SNPs located within non-coding gene regions, focusing on genes encoding epigenetic enzymes, as these have been recently identified to control SMC fate in cardiovascular disease. We identified SNPs rs62059712 and rs74480102 in the promoter of the human JMJD3 gene and show that the minor C allele increases JMJD3 transcription in SMCs via increased SP1 binding to the JMJD3 promoter. Using our novel SMC-specific Jmjd3-deficient murine model ( Jmjd3 flox/flox Myh11 CreERT ), we show that loss of Jmjd3 in SMCs results in HTN, mechanistically, due to decreased EDNRB expression and a compensatory increase in EDNRA expression. As a translational corollary, through single cell RNA-sequencing (scRNA-seq) of human arteries, we found strong correlation between JMJD3 and EDNRB expression in SMCs. Further, we identified that JMJD3 is required for SMC-specific gene expression, and loss of JMJD3 in SMCs in the setting of HTN results in increased arterial remodeling by promoting the SMC synthetic phenotype. Our findings link a HTN-associated human DNA variant with regulation of SMC plasticity, revealing therapeutic targets that may be used in the screening and/or personalized treatment of HTN.

Vascular remodelling in cardiovascular diseases: hypertension, oxidation, and inflammation

Optimal vascular structure and function are essential for maintaining the physiological functions of the cardiovascular system. Vascular remodelling involves changes in vessel structure, including its size, shape, cellular and molecular composition. These changes result from multiple risk factors and may be compensatory adaptations to sustain blood vessel function. They occur in diverse cardiovascular pathologies, from hypertension to heart failure and atherosclerosis. Dynamic changes in the endothelium, fibroblasts, smooth muscle cells, pericytes or other vascular wall cells underlie remodelling. In addition, immune cells, including macrophages and lymphocytes, may infiltrate vessels and initiate inflammatory signalling. They contribute to a dynamic interplay between cell proliferation, apoptosis, migration, inflammation, and extracellular matrix reorganisation, all critical mechanisms of vascular remodelling. Molecular pathways underlying these processes include growth factors (e.g., vascular endothelial growth factor and platelet-derived growth factor), inflammatory cytokines (e.g., interleukin-1β and tumour necrosis factor-α), reactive oxygen species, and signalling pathways, such as Rho/ROCK, MAPK, and TGF-β/Smad, related to nitric oxide and superoxide biology. MicroRNAs and long noncoding RNAs are crucial epigenetic regulators of gene expression in vascular remodelling. We evaluate these pathways for potential therapeutic targeting from a clinical translational perspective. In summary, vascular remodelling, a coordinated modification of vascular structure and function, is crucial in cardiovascular disease pathology.

Effect of DNA methylation on the osteogenic differentiation of mesenchymal stem cells: concise review

Mesenchymal stem cells (MSCs) have promising potential for bone tissue engineering in bone healing and regeneration. They are regarded as such due to their capacity for self-renewal, multiple differentiation, and their ability to modulate the immune response. However, changes in the molecular pathways and transcription factors of MSCs in osteogenesis can lead to bone defects and metabolic bone diseases. DNA methylation is an epigenetic process that plays an important role in the osteogenic differentiation of MSCs by regulating gene expression. An increasing number of studies have demonstrated the significance of DNA methyltransferases (DNMTs), Ten-eleven translocation family proteins (TETs), and MSCs signaling pathways about osteogenic differentiation in MSCs. This review focuses on the progress of research in these areas.

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.

HAT and HDAC: Enzyme with Contradictory Action in Neurodegenerative Diseases

In view of the increasing risk of neurodegenerative diseases, epigenetics plays a fundamental role in the field of neuroscience. Several modifications have been studied including DNA methylation, histone acetylation, histone phosphorylation, etc. Histone acetylation and deacetylation regulate gene expression, and the regular activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs) provides regulatory stages for gene expression and cell cycle. Imbalanced homeostasis in these enzymes causes a detrimental effect on neurophysiological function. Intriguingly, epigenetic remodelling via histone acetylation in certain brain areas has been found to play a key role in the neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. It has been demonstrated that a number of HATs have a role in crucial brain processes such regulating neuronal plasticity and memory formation. The most recent therapeutic methods involve the use of small molecules known as histone deacetylase (HDAC) inhibitors that antagonize HDAC activity thereby increase acetylation levels in order to prevent the loss of HAT function in neurodegenerative disorders. The target specificity of the HDAC inhibitors now in use raises concerns about their applicability, despite the fact that this strategy has demonstrated promising therapeutic outcomes. The aim of this review is to summarize the cross-linking between histone modification and its regulation in the pathogenesis of neurological disorders. Furthermore, these findings also support the notion of new pharmacotherapies that target particular areas of the brain using histone deacetylase inhibitors.

Rapid profiling of transcription factor-cofactor interaction networks reveals principles of epigenetic regulation

Transcription factor (TF)-cofactor (COF) interactions define dynamic, cell-specific networks that govern gene expression; however, these networks are understudied due to a lack of methods for high-throughput profiling of DNA-bound TF-COF complexes. Here we describe the Cofactor Recruitment (CoRec) method for rapid profiling of cell-specific TF-COF complexes. We define a lysine acetyltransferase (KAT)-TF network in resting and stimulated T cells. We find promiscuous recruitment of KATs for many TFs and that 35% of KAT-TF interactions are condition specific. KAT-TF interactions identify NF-κB as a primary regulator of acutely induced H3K27ac. Finally, we find that heterotypic clustering of CBP/P300-recruiting TFs is a strong predictor of total promoter H3K27ac. Our data supports clustering of TF sites that broadly recruit KATs as a mechanism for widespread co-occurring histone acetylation marks. CoRec can be readily applied to different cell systems and provides a powerful approach to define TF-COF networks impacting chromatin state and gene regulation.

Epigenetics in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a critical complication that poses a significant threat to the health of patients with diabetes. The intricate pathological mechanisms of DCM cause diastolic dysfunction, followed by impaired systolic function in the late stages. Accumulating researches have revealed the association between DCM and various epigenetic regulatory mechanisms, including DNA methylation, histone modifications, non-coding RNAs, and other epigenetic molecules. Recently, a profound understanding of epigenetics in the pathophysiology of DCM has been broadened owing to advanced high-throughput technologies, which assist in developing potential therapeutic strategies. In this review, we briefly introduce the epigenetics regulation and update the relevant progress in DCM. We propose the role of epigenetic factors and non-coding RNAs (ncRNAs) as potential biomarkers and drugs in DCM diagnosis and treatment, providing a new perspective and understanding of epigenomics in DCM.

Nuclear Control of Vascular Smooth Muscle Cell Plasticity during Vascular Remodeling

Control of vascular smooth muscle cell (SMC) gene expression is an essential process for establishing and maintaining lineage identity, contractility, and plasticity. Most mechanisms (epigenetic, transcriptional, and post-transcriptional) implicated in gene regulation occur in the nucleus. Still, intranuclear pathways are directly impacted by modifications in the extracellular environment in conditions of adaptive or maladaptive remodeling. Integration of extracellular, cellular, and genomic information into the nucleus through epigenetic and transcriptional control of genome organization plays a major role in regulating SMC functions and phenotypic transitions during vascular remodeling and diseases. This review aims to provide a comprehensive update on nuclear mechanisms, their interactions, and their integration in controlling SMC homeostasis and dysfunction. It summarizes and discusses the main nuclear mechanisms preponderant in SMCs in the context of vascular disease, such as atherosclerosis, with an emphasis on studies employing in vivo cell-specific loss-of-function and single-cell omics approaches.

Insights into dietary phytochemicals targeting Parkinson's disease key genes and pathways: A network pharmacology approach

Parkinson's disease (PD) is a complex neurological disease associated with the degeneration of dopaminergic neurons. Oxidative stress is a key player in instigating apoptosis in dopaminergic neurons. To improve the survival of neurons many dietary phytochemicals have gathered significant attention recently. Thus, the present study implements a comprehensive network pharmacology approach to unravel the mechanisms of action of dietary phytochemicals that benefit disease management. A literature search was performed to identify ligands (i.e., comprising dietary phytochemicals and Food and Drug Administration pre-approved PD drugs) in the PubMed database. Targets associated with selected ligands were extracted from the search tool for interactions of chemicals (STITCH) database. Then, the construction of a gene-gene interaction (GGI) network, analysis of hub-gene, functional and pathway enrichment, associated transcription factors, miRNAs, ligand-target interaction network, docking were performed using various bioinformatics tools together with molecular dynamics (MD) simulations. The database search resulted in 69 ligands and 144 unique targets. GGI and subsequent topological measures indicate histone acetyltransferase p300 (EP300), mitogen-activated protein kinase 1 (MAPK1) or extracellular signal-regulated kinase (ERK)2, and CREB-binding protein (CREBBP) as hub genes. Neurodegeneration, MAPK signaling, apoptosis, and zinc binding are key pathways and gene ontology terms. hsa-miR-5692a and SCNA gene-associated transcription factors interact with all the 3 hub genes. Ligand-target interaction (LTI) network analysis suggest rasagiline and baicalein as candidate ligands targeting MAPK1. Rasagiline and baicalein form stable complexes with the Y205, K330, and V173 residues of MAPK1. Computational molecular insights suggest that baicalein and rasagiline are promising preclinical candidates for PD management.

Involvement of Histone Acetyltransferase 1 (HAT1) in the Spermatogenesis of Non-Condensed Nuclear Sperm in Chinese Mitten Crab, Eriocheir sinensis

Chinese mitten crab, Eriocheir sinensis, is a decapod crustacean with a special, non-condensated nucleus in the sperm. Studies have shown that the nuclear compact state of male germ cells during the spermatogenesis is closely related to histone modification. To explore the possible role of histone acetyltransferase 1 (HAT1) in the chromatin organization during the E. sinensis spermatogenesis, we took the testis tissues of both adult and juvenile crabs as the materials of study and analyzed the biological functions of HAT1 by whole transcriptome sequencing and bioinformatics, then further analyzed the expression and distribution of HAT1 using the methods of RT-qRCR, western blotting, and immunofluorescence location. The results showed that HAT1 is an alkaline-unstable hydrophilic protein. It was predicted to interact with a variety of histones and chromosome assembly proteins, including Asf1b, Chaf1b, and Hist1h3f, and is involved in many biological functions pertaining to chromatin dynamics such as chromatin organization, DNA dependent nucleosome assembly, DNA conformational changes, and so on. HAT1 was up-regulated in the adult testes compared to the juvenile (n = 3, P < 0.05). HAT1 was mainly located in the nuclei of male germ cells of E. sinensis. As spermatogenesis proceeded, the expression of HAT1 decreased and even disappeared in the nuclei (n = 3, P < 0.05). HAT1 is an important player in histone acetylation, which facilitates chromatin alteration in a three-dimensional conformation. The expression of HAT1 in different male germ cells might indicate the chromatin dynamics at the diversity stages of spermatogenesis. The high expression of HAT1 at the early stages of E. sinensis spermatogenesis hints the active involvement in chromatin organization, while its progressively reduced expression accompanied by the progression of spermatogenesis suggests a relatively gradual stabilization and stereotyping of chromatin. As for the disappearance of HAT1 in mature sperm with non-condensed nuclei, the reduction in histones targeted by HAT1 or histone acetylation may be an important initiator.

Protein-protein interaction network-based integration of GWAS and functional data for blood pressure regulation analysis

BACKGROUND

It is valuable to analyze the genome-wide association studies (GWAS) data for a complex disease phenotype in the context of the protein-protein interaction (PPI) network, as the related pathophysiology results from the function of interacting polyprotein pathways. The analysis may include the design and curation of a phenotype-specific GWAS meta-database incorporating genotypic and eQTL data linking to PPI and other biological datasets, and the development of systematic workflows for PPI network-based data integration toward protein and pathway prioritization. Here, we pursued this analysis for blood pressure (BP) regulation.

METHODS

The relational scheme of the implemented in Microsoft SQL Server BP-GWAS meta-database enabled the combined storage of: GWAS data and attributes mined from GWAS Catalog and the literature, Ensembl-defined SNP-transcript associations, and GTEx eQTL data. The BP-protein interactome was reconstructed from the PICKLE PPI meta-database, extending the GWAS-deduced network with the shortest paths connecting all GWAS-proteins into one component. The shortest-path intermediates were considered as BP-related. For protein prioritization, we combined a new integrated GWAS-based scoring scheme with two network-based criteria: one considering the protein role in the reconstructed by shortest-path (RbSP) interactome and one novel promoting the common neighbors of GWAS-prioritized proteins. Prioritized proteins were ranked by the number of satisfied criteria.

RESULTS

The meta-database includes 6687 variants linked with 1167 BP-associated protein-coding genes. The GWAS-deduced PPI network includes 1065 proteins, with 672 forming a connected component. The RbSP interactome contains 1443 additional, network-deduced proteins and indicated that essentially all BP-GWAS proteins are at most second neighbors. The prioritized BP-protein set was derived from the union of the most BP-significant by any of the GWAS-based or the network-based criteria. It included 335 proteins, with ~ 2/3 deduced from the BP PPI network extension and 126 prioritized by at least two criteria. ESR1 was the only protein satisfying all three criteria, followed in the top-10 by INSR, PTN11, CDK6, CSK, NOS3, SH2B3, ATP2B1, FES and FINC, satisfying two. Pathway analysis of the RbSP interactome revealed numerous bioprocesses, which are indeed functionally supported as BP-associated, extending our understanding about BP regulation.

CONCLUSIONS

The implemented workflow could be used for other multifactorial diseases.

SWI/SNF Complex in Vascular Smooth Muscle Cells and Its Implications in Cardiovascular Pathologies

Mature vascular smooth muscle cells (VSMC) exhibit a remarkable degree of plasticity, a characteristic that has intrigued cardiovascular researchers for decades. Recently, it has become increasingly evident that the chromatin remodeler SWItch/Sucrose Non-Fermentable (SWI/SNF) complex plays a pivotal role in orchestrating chromatin conformation, which is critical for gene regulation. In this review, we provide a summary of research related to the involvement of the SWI/SNF complexes in VSMC and cardiovascular diseases (CVD), integrating these discoveries into the current landscape of epigenetic and transcriptional regulation in VSMC. These novel discoveries shed light on our understanding of VSMC biology and pave the way for developing innovative therapeutic strategies in CVD treatment.

Branched-chain amino acid catabolic defect in vascular smooth muscle cells drives thoracic aortic dissection via mTOR hyperactivation

Metabolic reprogramming of vascular smooth muscle cell (VSMC) plays a critical role in the pathogenesis of thoracic aortic dissection (TAD). Previous researches have mainly focused on dysregulation of fatty acid or glucose metabolism, while the impact of amino acids catabolic disorder in VSMCs during the development of TAD remains elusive. Here, we identified branched-chain amino acid (BCAA) catabolic defect as a metabolic hallmark of TAD. The bioinformatics analysis and data from human aorta revealed impaired BCAA catabolism in TAD individuals. This was accompanied by upregulated branched-chain α-ketoacid dehydrogenase kinase (BCKDK) expression and BCKD E1 subunit alpha (BCKDHA) phosphorylation, enhanced vascular inflammation, and hyperactivation of mTOR signaling. Further in vivo experiments demonstrated that inhibition of BCKDK with BT2 (a BCKDK allosteric inhibitor) treatment dephosphorylated BCKDHA and re-activated BCAA catabolism, attenuated VSMCs phenotypic switching, alleviated aortic remodeling, mitochondrial reactive oxygen species (ROS) damage and vascular inflammation. Additionally, the beneficial actions of BT2 were validated in a TNF-α challenged murine VSMC cell line. Meanwhile, rapamycin conferred similar beneficial effects against VSMC phenotypic switching, cellular ROS damage as well as inflammatory response. However, co-treatment with MHY1485 (a classic mTOR activator) reversed the beneficial effects of BT2 by reactivating mTOR signaling. Taken together, the in vivo and in vitro evidence showed that impairment of BCAA catabolism resulted in aortic accumulation of BCAA and further caused VSMC phenotypic switching, mitochondrial ROS damage and inflammatory response via mTOR hyperactivation. BCKDK and mTOR signaling may serve as the potential drug targets for the prevention and treatment of TAD.

Ginkgolide B Blocks Vascular Remodeling after Vascular Injury via Regulating Tgfβ1/Smad Signaling Pathway

Coronary artery disease (CAD) is the most prevalent cardiovascular disease worldwide, resulting in myocardial infarction (MI) and even sudden death. Following percutaneous coronary intervention (PCI), restenosis caused by vascular remodeling is always formed at the stent implantation site. Here, we show that Ginkgolide B (GB), a naturally occurring terpene lactone, effectively suppresses vascular remodeling and subsequent restenosis in wild-type mice following left carotid artery (LCA) injury. Additional experiments reveal that GB exerts a protective effect on vascular remodeling and further restenosis through modulation of the Tgfβ1/Smad signaling pathway in vivo and in human vascular smooth muscle cells (HVSMAs) but not in human umbilical vein endothelial cells (HUVECs) in vitro. Moreover, the beneficial effect of GB is abolished after incubated with pirfenidone (PFD, a drug for idiopathic pulmonary fibrosis, IPF), which can inhibit Tgfβ1. In Tgfβ1-/- mice, treatment with pirfenidone capsules and Yinxingneizhi Zhusheye (including Ginkgolide B) fails to improve vascular remodeling and restenosis. In conclusion, our data identify that GB could be a potential novel therapeutic agent to block vessel injury-associated vascular remodeling and further restenosis and show significant repression of Tgfβ1/Smad signaling pathway.

Unveiling the Hidden Landscape of Arterial Diseases at Single-Cell Resolution

High-resolution single-cell technologies have shed light on the pathogenesis of cardiovascular diseases by enabling the discovery of novel cellular and transcriptomic signatures associated with various conditions, and uncovering new contributions of inflammatory processes, immunity, metabolic stress, and risk factors. We review the information obtained from studies using single-cell technologies in tissues with atherosclerosis and aortic aneurysms. Insights are provided on the biology of endothelial, smooth muscle, and immune cells in the arterial intima and media. In addition to cellular diversity, numerous examples of plasticity and phenotype switching are highlighted and presented in the context of normal cell functions.

Acetyltransferases CBP/p300 Control Transcriptional Switch of β-Catenin and Stat1 Promoting Osteoblast Differentiation

CREB-binding protein (CBP) (CREBBP) and p300 (EP300) are multifunctional histone acetyltransferases (HATs) with extensive homology. Germline mutations of CBP or p300 cause skeletal abnormalities in humans and mice. However, the precise roles of CBP/p300 in bone homeostasis remain elusive. Here, we report that conditional knockout of CBP or p300 in osteoblasts results in reduced bone mass and strength due to suppressed bone formation. The HAT activity is further confirmed to be responsible for CBP/p300-mediated osteogenesis using A-485, a selective inhibitor of CBP/p300 HAT. Mechanistically, CBP/p300 HAT governs osteogenic gene expression in part through transcriptional activation of β-catenin and inhibition of Stat1. Furthermore, acetylation of histone H3K27 and the transcription factor Foxo1 are demonstrated to be involved in CBP/p300 HAT-regulated β-catenin and Stat1 transcription, respectively. Taken together, these data identify acetyltransferases CBP/p300 as critical regulators that promote osteoblast differentiation and reveal an epigenetic mechanism responsible for maintaining bone homeostasis. © 2023 American Society for Bone and Mineral Research (ASBMR).

Inhibiting CBP Decreases AR Expression and Inhibits Proliferation in Benign Prostate Epithelial Cells

(1) Background: CREB-binding protein (CBP) is a key transcriptional coactivator of androgen receptors (AR). We conducted this study to investigate the effects of CBP on AR expression and proliferation in benign prostatic hyperplasia (BPH) prostate epithelial cells. (2) Methods: By analyzing a published data set, we found that CBP was closely related to the gene expression of AR in prostate cells. We enrolled 20 BPH patients who underwent transurethral resection of the prostate (TURP) in Peking University First Hospital in 2022, and analyzed the expressions of CBP and AR in BPH prostate tissues. Then, we used ICG-001 and shRNA to inhibit CBP in prostate epithelial cells (BPH-1 cells and RWPE-1 cells), and conducted immunofluorescence, cell viability assay, flow cytometry analysis, and Western blot to analyze the effects of CBP on AR expression and proliferation in prostate epithelial cells. We also studied the interaction between CBP and AR through a co-immunoprecipitation assay. (3) Results: CBP is consistent with AR in expression intensity in prostate tissues. Inhibiting CBP decreases AR expression, and induces proliferation inhibition, apoptosis, and cell cycle arrest in BPH prostate epithelial cells. The co-immunoprecipitation assay showed that CBP binds with AR to form transcription complexes in prostate epithelial cells. (4) Conclusions: Inhibiting CBP decreases AR expression and inhibits proliferation in benign prostate epithelial cells. CBP may be a potential target to affect AR expression and the proliferation of prostate epithelial cells in BPH.

P4HA2-induced prolyl hydroxylation of YAP1 restricts vascular smooth muscle cell proliferation and neointima formation

Vascular smooth muscle cell (VSMC) proliferation and neointima formation play significant roles in atherosclerosis development and restenosis following percutaneous coronary intervention. Our team previously discovered that TEA domain transcription factor 1 (TEAD1) promotes vascular smooth muscle differentiation, which is necessary for vascular development. Conversely, aberrant YAP1 activation upregulates the platelet-derived growth factor receptor beta to encourage VSMC proliferation and neointima formation. In this study, we aimed to investigate the molecular mechanisms of YAP1/TEAD signaling during neointima formation. Our research focused on the prolyl 4-hydroxylase alpha 2 (P4HA2) and its downstream target, Yes-associated protein 1 (YAP1), in regulating VSMC differentiation and neointima formation. Our results indicated that P4HA2 reduction leads to VSMC dedifferentiation and promotes neointima formation after injury. Furthermore, we found that P4HA2-induced prolyl hydroxylation of YAP1 restricts its transcriptional activity, which is essential to maintaining VSMC differentiation. These findings suggest that targeting P4HA2-mediated prolyl hydroxylation of YAP1 may be a promising therapeutic approach to prevent injury-induced neointima formation in cardiovascular disease.

Neointima abating and endothelium preserving - An adventitia-localized nanoformulation to inhibit the epigenetic writer DOT1L

Open vascular reconstructions such as bypass are common treatments for cardiovascular disease. Unfortunately, neointimal hyperplasia (IH) follows, leading to treatment failure for which there is no approved therapy. Here we combined the strengths of tailoring nanoplatforms for open vascular reconstructions and targeting new epigenetic mechanisms. We produced adhesive nanoparticles (ahNP) that could be pen-brushed and immobilized on the adventitia to sustainably release pinometostat, an inhibitor drug selective to the epigenetic writer DOT1L that catalyzes histone-3 lysine-79 dimethylation (H3K79me2). This treatment not only reduced IH by 76.8% in injured arteries mimicking open reconstructions in obese Zucker rats with human-like diseases but also avoided the shortcoming of endothelial impairment in IH management. In mechanistic studies, chromatin immunoprecipitation (ChIP) sequencing revealed co-enrichment of the histone mark H3K27ac(acetyl) and its reader BRD4 at the gene of aurora kinase B (AURKB), where H3K79me2 was also enriched as indicated by ChIP-qPCR. Accordingly, DOT1L co-immunoprecipitated with H3K27ac. Furthermore, the known IH driver BRD4 governed the expression of DOT1L which controlled AURKB's protein level, revealing a BRD4- > DOT1L- > AURKB axis. Consistently, AURKB-selective inhibition reduced IH. Thus, this study presents a prototype nanoformulation suited for open vascular reconstructions, and the new insights into chromatin modulators may aid future translational advances.

Altered Smooth Muscle Cell Histone Acetylome by the SPHK2/S1P Axis Promotes Pulmonary Hypertension

BACKGROUND

Epigenetic regulation of vascular remodeling in pulmonary hypertension (PH) is poorly understood. Transcription regulating, histone acetylation code alters chromatin accessibility to promote transcriptional activation. Our goal was to identify upstream mechanisms that disrupt epigenetic equilibrium in PH.

METHODS

Human pulmonary artery smooth muscle cells (PASMCs), human idiopathic pulmonary arterial hypertension (iPAH):human PASMCs, iPAH lung tissue, failed donor lung tissue, human pulmonary microvascular endothelial cells, iPAH:PASMC and non-iPAH:PASMC RNA-seq databases, NanoString nCounter, and cleavage under targets and release using nuclease were utilized to investigate histone acetylation, hyperacetylation targets, protein and gene expression, sphingolipid activation, cell proliferation, and gene target identification. SPHK2 (sphingosine kinase 2) knockout was compared with control C57BL/6NJ mice after 3 weeks of hypoxia and assessed for indices of PH.

RESULTS

We identified that Human PASMCs are vulnerable to the transcription-promoting epigenetic mediator histone acetylation resulting in alterations in transcription machinery and confirmed its pathological existence in PH:PASMC cells. We report that SPHK2 is elevated as much as 20-fold in iPAH lung tissue and is elevated in iPAH:PASMC cells. During PH pathogenesis, nuclear SPHK2 activates nuclear bioactive lipid S1P (sphingosine 1-phosphate) catalyzing enzyme and mediates transcription regulating histone H3K9 acetylation (acetyl histone H3 lysine 9 [Ac-H3K9]) through EMAP (endothelial monocyte activating polypeptide) II. In iPAH lungs, we identified a 4-fold elevation of the reversible epigenetic transcription modulator Ac-H3K9:H3 ratio. Loss of SPHK2 inhibited hypoxic-induced PH and Ac-H3K9 in mice. We discovered that pulmonary vascular endothelial cells are a priming factor of the EMAP II/SPHK2/S1P axis that alters the acetylome with a specificity for PASMC, through hyperacetylation of histone H3K9. Using cleavage under targets and release using nuclease, we further show that EMAP II-mediated SPHK2 has the potential to modify the local transcription machinery of pluripotency factor KLF4 (Krüppel-like factor 4) by hyperacetylating KLF4 Cis-regulatory elements while deletion and targeted inhibition of SPHK2 rescues transcription altering Ac-H3K9.

CONCLUSIONS

SPHK2 expression and its activation of the reversible histone H3K9 acetylation in human pulmonary artery smooth muscle cell represent new therapeutic targets that could mitigate PH vascular remodeling.

H3.3B controls aortic dissection progression by regulating vascular smooth muscle cells phenotypic transition and vascular inflammation

Aortic dissection is a devastating cardiovascular disease with a high lethality. Histone variants maintain the genomic integrity and play important roles in development and diseases. However, the role of histone variants in aortic dissection has not been well identified. In the present study, H3f3b knockdown reduced the synthetic genes expression of VSMCs, while overexpressing H3f3b exacerbated the cellular immune response of VSMCs induced by inflammatory cytokines. Combined RNA-seq and ChIP-seq analyses revealed that histone variant H3.3B directly bound to the genes related to extracellular matrix, VSMC synthetic phenotype, cytokine responses and TGFβ signaling pathway, and regulated their expressions. In addition, VSMC-specific H3f3b knockin aggravated aortic dissection development in mice, while H3f3b knockout significantly reduced the incidence of aortic dissection. In term of mechanisms, H3.3B regulated Spp1 and Ccl2 genes, inducing the apoptosis of VSMCs and recruiting macrophages. This study demonstrated the vital roles of H3.3B in phenotypic transition of VSMCs, loss of media VSMCs, and vascular inflammation in aortic dissection.

circACTA2 inhibits NLRP3 inflammasome-mediated inflammation via interacting with NF-κB in vascular smooth muscle cells

circACTA2 derived from the smooth muscle α-actin gene plays an important role in the regulation of vascular smooth muscle cell (VSMC) phenotype. The activation of NLRP3 inflammasome is involved in VSMC phenotypic switching. However, the mechanistic relationship between circACTA2 and NLRP3 inflammasome during vascular remodeling remains poorly understood. Here, we showed that circACTA2 was down-regulated in human intimal hyperplasia. circACTA2 overexpression in circACTA2 transgenic mice significantly decreased the neointimal hyperplasia induced by vascular injury, which is concomitant with a decrease in IL-18, IL-1β, TNF-α, and IL-6 levels. Gain- and loss-of-function studies revealed that circACTA2 alleviated VSMC inflammation by suppressing the activation of NLRP3 inflammasome. Mechanistically, circACTA2 inhibited the expression of NF-κB p65 and p50 subunits and interacted with p50, which impedes the formation of the p50/p65 heterodimer and nuclear translocation induced by TNF-α, thus resulting in the suppression of NLRP3 gene transcription and inflammasome activation. Furthermore, circACTA2 overexpression mitigated inflammation via repressing NLRP3 inflammasome-mediated VSMC pyroptosis. Importantly, employing a decoy oligonucleotide to compete with circACTA2 for binding to p50 could attenuate the expression of NLRP3, ASC, and caspase-1. These findings provide a novel insight into the functional roles of circACTA2 in VSMCs, and targeting the circACTA2-NF-κB-NLRP3 axis represents a promising therapeutic strategy for vascular remodeling.

Histone acetyltransferase P300 deficiency promotes ferroptosis of vascular smooth muscle cells by activating the HIF-1α/HMOX1 axis

BACKGROUND

E1A-associated 300-kDa protein (P300), an endogenous histone acetyltransferase, contributes to modifications of the chromatin landscape of genes involved in multiple cardiovascular diseases. Ferroptosis of vascular smooth muscle cells (VSMCs) is a novel pathological mechanism of aortic dissection. However, whether P300 regulates VSMC ferroptosis remains unknown.

METHODS

Cystine deprivation (CD) and imidazole ketone erastin (IKE) were used to induce VSMC ferroptosis. Two different knockdown plasmids targeting P300 and A-485 (a specific inhibitor of P300) were used to investigate the function of P300 in the ferroptosis of human aortic smooth muscle cells (HASMCs). Cell counting kit-8, lactate dehydrogenase and flow cytometry with propidium iodide staining were performed to assess the cell viability and death under the treatment of CD and IKE. BODIPY-C11 assay, immunofluorescence staining of 4-hydroxynonenal and malondialdehyde assay were conducted to detect the level of lipid peroxidation. Furthermore, co-immunoprecipitation was utilized to explore the interaction between P300 and HIF-1α, HIF-1α and P53.

RESULTS

Compared with normal control, the protein level of P300 was significantly decreased in HASMCs treated with CD and IKE, which was largely nullified by the ferroptosis inhibitor ferrostatin-1 but not by the autophagy inhibitor or apoptosis inhibitor. Knockdown of P300 by short-hairpin RNA or inhibition of P300 activity by A-485 promoted CD- and IKE-induced HASMC ferroptosis, as evidenced by a reduction in cell viability and aggravation of lipid peroxidation of HASMCs. Furthermore, we found that hypoxia-inducible factor-1α (HIF-1α)/heme oxygenase 1 (HMOX1) pathway was responsible for the impacts of P300 on ferroptosis of HASMCs. The results of co-immunoprecipitation demonstrated that P300 and P53 competitively bound HIF-1α to regulate the expression of HMOX1. Under normal conditions, P300 interacted with HIF-1α to inhibit HMOX1 expression, while reduced expression of P300 induced by ferroptosis inducers would favor HIF-1α binding to P53 to trigger HMOX1 overexpression. Furthermore, the aggravated effects of P300 knockdown on HASMC ferroptosis were largely nullified by HIF-1α knockdown or the HIF-1α inhibitor BAY87-2243.

CONCLUSION

Thus, our results revealed that P300 deficiency or inactivation facilitated CD- and IKE-induced VSMC ferroptosis by activating the HIF-1α/HMOX1 axis, which may contribute to the development of diseases related to VSMC ferroptosis.

Transcriptomic and physiological analyses reveal temporal changes contributing to the delayed healing response to arterial injury in diabetic rats

Objective

Atherosclerosis is a leading cause of mortality in the rapidly growing population with diabetes mellitus. Vascular interventions in patients with diabetes can lead to complications attributed to defective vascular remodeling and impaired healing response in the vessel wall. In this study, we aim to elucidate the molecular differences in the vascular healing response over time using a rat model of arterial injury applied to healthy and diabetic conditions.

Methods

Wistar (healthy) and Goto-Kakizaki (GK, diabetic) rats (n = 40 per strain) were subjected to left common carotid artery (CCA) balloon injury and euthanized at different timepoints: 0 and 20 hours, 5 days, and 2, 4, and 6 weeks. Noninvasive morphological and physiological assessment of the CCA was performed with ultrasound biomicroscopy (Vevo 2100) and corroborated with histology. Total RNA was isolated from the injured CCA at each timepoint, and microarray profiling was performed (n = 3 rats per timepoint; RaGene-1_0-st-v1 platform). Bioinformatic analyses were conducted using R software, DAVID bioinformatic tool, online STRING database, and Cytoscape software.

Results

Significant increase in the neointimal thickness (P < .01; two-way analysis of variance) as well as exaggerated negative remodeling was observed after 2 weeks of injury in GK rats compared with heathy rats, which was confirmed by histological analyses. Bioinformatic analyses showed defective expression patterns for smooth muscle cells and immune cell markers, along with reduced expression of key extracellular matrix-related genes and increased expression of pro-thrombotic genes, indicating potential faults on cell regulation level. Transcription factor-protein-protein interaction analysis provided mechanistic evidence with an array of transcription factors dysregulated in diabetic rats.

Conclusions

In this study, we have demonstrated that diabetic rats exhibit impaired arterial remodeling characterized by a delayed healing response. We show that increased contractile smooth muscle cell marker expression coincided with decreased matrix metalloproteinase expression, indicating a potential mechanism for a lack of extracellular matrix reorganization in the impaired vascular healing in GK rats. These results further corroborate the higher prevalence of restenosis in patients with diabetes and provide vital molecular insights into the mechanisms contributing to the impaired arterial healing response in diabetes. Moreover, the presented study provides the research community with the valuable longitudinal gene expression data bank for further exploration of diabetic vasculopathy.

Clonal Hematopoiesis and the Heart: a Toxic Relationship

PURPOSE OF REVIEW

Clonal hematopoiesis (CH) refers to the expansion of hematopoietic stem cell clones and their cellular progeny due to somatic mutations, mosaic chromosomal alterations (mCAs), or copy number variants which naturally accumulate with age. CH has been linked to increased risk of blood cancers, but CH has also been linked to adverse cardiovascular outcomes.

RECENT FINDINGS

A combination of clinical outcome studies and mouse models have offered strong evidence that CH mutations either correlate with or cause atherosclerosis, diabetes mellitus, chronic kidney disease, heart failure, pulmonary hypertension, aortic aneurysm, myocardial infarction, stroke, aortic stenosis, poor outcomes following transcatheter aortic valve replacement (TAVR) or orthotopic heart transplant, death or need of renal replacement therapy secondary to cardiogenic shock, death from cardiovascular causes at large, and enhance anthracycline cardiac toxicity. Mechanistically, some adverse outcomes are caused by macrophage secretion of IL-1β and IL-6, neutrophil invasion of injured myocardium, and T-cell skewing towards inflammatory phenotypes. CH mutations lead to harmful inflammation and arterial wall invasion by bone marrow-derived cells resulting in poor cardiovascular health and outcomes. Blockade of IL-1β or JAK2 signaling are potential avenues for preventing CH-caused cardiovascular morbidity and mortality.

Deficiency of thrombospondin-2 alleviates intimal hyperplasia in mice by modulating vascular smooth muscle cell proliferation and migration

Thrombospondin-2 (Tsp2), a glycoprotein in the extracellular matrix, plays a critical role in the maintenance of vascular homeostasis. However, its role in the pathogenesis of cardiovascular disorders such as intimal hyperplasia is not fully elucidated. This study, therefore, aims to explore the effect of Tsp2 on intimal hyperplasia and its associated underlying mechanisms. Intimal hyperplasia (IH) was established using a modified wire-mediated femoral artery injury model. Immunofluorescence and qPCR identified upregulated Tsp2 expression in the injured femoral artery compared with the uninjured femoral artery. Similarly, TSP2 expression was also increased in human samples from the atherosclerotic femoral artery and colocalized with vascular smooth muscle cells (VSMCs). Compared with the wild-type littermates, Tsp2 knockout mice displayed a mitigated IH in the injured femoral artery, as demonstrated by a decreased neointimal area and intimal/median ratio. Primary mouse VSMCs were cultured to explore the mechanism by which Tsp2 influenced IH in vitro. PDGF-stimulated VSMCs presented an elevated Tsp2 expression and enhanced migration and proliferation. However, Tsp2 knockdown by siRNA blocked the increased migration and proliferation of VSMCs. Further analysis identified an association between Notch3 and IH when the intracellular domain of Notch3 (Nicd3) was upregulated in PDGF-stimulated VSMCs and femoral arteries with IH in human tissues. Along with the overexpression and downregulation of Tsp2, the Nicd3 expression was also up and downregulated accordingly. Tsp2 was associated with IH and may serve as a therapeutic target for IH. Downregulation of Tsp2 could mitigate the progression of IH by modulating the proliferation and migration of VSMCs.

Vascular smooth muscle cells in intimal hyperplasia, an update

Arterial occlusive disease is the leading cause of death in Western countries. Core contemporary therapies for this disease include angioplasties, stents, endarterectomies and bypass surgery. However, these treatments suffer from high failure rates due to re-occlusive vascular wall adaptations and restenosis. Restenosis following vascular surgery is largely due to intimal hyperplasia. Intimal hyperplasia develops in response to vessel injury, leading to inflammation, vascular smooth muscle cells dedifferentiation, migration, proliferation and secretion of extra-cellular matrix into the vessel's innermost layer or intima. In this review, we describe the current state of knowledge on the origin and mechanisms underlying the dysregulated proliferation of vascular smooth muscle cells in intimal hyperplasia, and we present the new avenues of research targeting VSMC phenotype and proliferation.

Integrating epigenetics and metabolomics to advance treatments for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating vascular disease with multiple etiologies. Emerging evidence supports a fundamental role for epigenetic machinery and metabolism in the initiation and progression of PAH. Here, we summarize emerging epigenetic mechanisms that have been identified as contributors to PAH evolution, specifically, DNA methylation, histone modifications, and microRNAs. Furthermore, the interplay between epigenetics with metabolism is explored while new crosstalk targets to be investigated in PAH are proposed that highlight multi-omics strategies including integrated epigenomics and metabolomics. Therapeutic opportunities and challenges associated with epigenetics and metabolomics in PAH are examined, highlighting the role that epigenetics and metabolomics have in facilitating early detection, personalized dietary plans, and advanced drug therapy for PAH.

TET enzymes regulate skeletal development through increasing chromatin accessibility of RUNX2 target genes

The Ten-eleven translocation (TET) family of dioxygenases mediate cytosine demethylation by catalyzing the oxidation of 5-methylcytosine (5mC). TET-mediated DNA demethylation controls the proper differentiation of embryonic stem cells and TET members display functional redundancy during early gastrulation. However, it is unclear if TET proteins have functional significance in mammalian skeletal development. Here, we report that Tet genes deficiency in mesoderm mesenchymal stem cells results in severe defects of bone development. The existence of any single Tet gene allele can support early bone formation, suggesting a functional redundancy of TET proteins. Integrative analyses of RNA-seq, Whole Genome Bisulfite Sequencing (WGBS), 5hmC-Seal and Assay for Transposase-Accessible Chromatin (ATAC-seq) demonstrate that TET-mediated demethylation increases the chromatin accessibility of target genes by RUNX2 and facilities RUNX2-regulated transcription. In addition, TET proteins interact with RUNX2 through their catalytic domain to regulate cytosine methylation around RUNX2 binding region. The catalytic domain is indispensable for TET enzymes to regulate RUNX2 transcription activity on its target genes and to regulate bone development. These results demonstrate that TET enzymes function to regulate RUNX2 activity and maintain skeletal homeostasis.

Here the authors investigate the role of the TET family of DNA demethylases in mammalian skeletal development. They find that loss of TETs leads to hypermethylation that results in decreased chromatin accessibility of RUNX2 target genes, repressing osteoblast differentiation and leading to skeletal defects in mouse such as short limbs.