Enhancer of zeste homolog 2-mediated epigenetic activation of acid sphingomyelinase in endothelial dysfunction during obesity

肥胖期间内皮功能障碍中 zeste 同源物 2 介导的酸性鞘磷脂酶表观遗传激活的增强剂

基本信息

批准号：
10664949
负责人：
Xiang Li
金额：
$ 44.71万
依托单位：
UNIVERSITY OF HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10664949
关键词：
7-ketocholesterol Abbreviations Adhesions Applications Grants Arteries Atherosclerosis Blood Vessels CASP1 gene Cardiovascular system Carotid Arteries Cell membrane Cells Ceramide Signaling Pathway Ceramides DNA DNA Methylation DNA Modification Methylases Defect Development Diabetes Mellitus Endothelial Cells Endothelium Enhancers Enzymes Epigenetic Process Gene Expression Genes High Fat Diet Homologous Gene Human Hydrolysis Hyperlipidemia Hypertension IL18 gene Immunohistochemistry Impairment Inflammasome Inflammatory Response Injury Interleukin-1 beta Knock-out Knockout Mice Lesion Mediating Membrane Metabolic Metabolism Methylation Molecular Morbidity - disease rate Mus Nonesterified Fatty Acids Nucleotides Obesity Oxidation-Reduction Palmitates Pathogenesis Pathologic Pathway interactions Patients Pattern Phenotype Prevention Production Proteins Reactive Oxygen Species Regulation Role Signal Pathway Signal Transduction Signaling Molecule Smooth Muscle Smooth Muscle Myocytes Sphingolipids Sphingomyelins Testing Time Transcriptional Regulation Umbilical vein Vascular Diseases Vasodilation acid sphingomyelinase arterial stiffness cardiovascular risk factor endothelial dysfunction endothelial stem cell epigenetic regulation histone methylation histone methyltransferase insight marenostrin monocyte mortality novel novel therapeutic intervention obesity development receptor therapeutic target vascular injury

项目摘要

Project Summary Endothelial dysfunction is an early defect in obesity, which is a major contributor to increased cardiovascular morbidity and mortality such as arterial stiffness, atherosclerosis, and hypertension. Recent studies have demonstrated a critical role of acid sphingomyelinase (ASM)-ceramide signaling in instigation of Nlrp3 inflammasomes and endothelial dysfunction during obesity and diabetes. The present proposal seeks to explore a novel mechanism mediating transcriptional control of ASM gene expression in ECs and determine how dysregulated ASM expression and activity promote vascular injury in obesity. Enhancer of zeste homolog 2 (Ezh2) is a histone methyltransferase that normally suppresses methylated genes, serving as a crucial epigenetic regulatory mechanism in gene expression. In preliminary studies, we found that loss of Ezh2 function increased ASM expression and ceramide levels in the intima leading to neointimal lesions in the carotid arteries of mice fed high fat diet (HFD). Such Ezh2-mediated suppression of ASM gene expression and ceramide signaling were also confirmed in cultured ECs. Based on these observations, we propose a hypothesis that loss of endothelial Ezh2 function upregulates ASM gene expression and augments ceramide production under hyperlipidemic conditions, which trigger Nlrp3 inflammasome activation and produce endothelial injury resulting in subsequent neointimal lesions on the carotid arterial wall. To test this hypothesis, the following Specific Aims are proposed. Specific Aim 1 will determine whether endothelial ASM activation due to loss of Ezh2 function contributes to endothelial dysfunction or injury at the early stage of obesity using endothelium-specific Ezh2 knockout mice (Ezh2ecKO) and their wild type littermates. Specific Aim 2 attempts to test how Ezh2-regulated ASM activation leads to endothelial dysfunction or injury by studying the role of ceramide and ceramide-enriched membrane rafts, Nlrp3 inflammasome activation, pyroptosis, endothelium- dependent vasodilation, inter-endothelial junction disruption, and adaptive endothelial progenitor cell landing or differentiation. In Specific Aim 3, we will explore the molecular mechanisms by which loss of Ezh2 function activates ASM with a main focus on the roles of histone and DNA methylation in cultured ECs from Ezh2ecKO mice and their wild type littermates. The findings will provide new insights into the pathogenesis of endothelial dysfunction and identify Ezh2-ASM pathway as therapeutic target for prevention or treatment of vaculopathy associated with obesity.

项目概要内皮功能障碍是肥胖的早期缺陷，是心血管疾病增加的主要原因发病率和死亡率，例如动脉硬化、动脉粥样硬化和高血压。最近的研究有证明酸性鞘磷脂酶 (ASM)-神经酰胺信号传导在 Nlrp3 的激活中发挥关键作用肥胖和糖尿病期间的炎症小体和内皮功能障碍。本提案旨在探索介导 EC 中 ASM 基因表达转录控制的新机制并确定 ASM 表达和活性失调如何促进肥胖中的血管损伤。 zeste同系物的增强剂 2 (Ezh2) 是一种组蛋白甲基转移酶，通常抑制甲基化基因，是一个关键的基因表达的表观遗传调控机制。在初步研究中，我们发现 Ezh2 的丢失功能增加内膜中的 ASM 表达和神经酰胺水平，导致内膜新生内膜损伤喂食高脂肪饮食（HFD）的小鼠的颈动脉。这种 Ezh2 介导的 ASM 基因表达抑制神经酰胺信号传导也在培养的 EC 中得到证实。基于这些观察，我们提出了假设内皮 Ezh2 功能丧失会上调 ASM 基因表达并增强神经酰胺在高脂血症条件下产生，触发 Nlrp3 炎性体激活并产生内皮损伤导致随后颈动脉壁上的新生内膜损伤。为了检验这个假设，提出以下具体目标。具体目标1将确定内皮ASM是否激活由于 Ezh2 功能丧失，导致肥胖早期阶段的内皮功能障碍或损伤内皮特异性 Ezh2 敲除小鼠 (Ezh2ecKO) 及其野生型同窝小鼠。具体目标 2 次尝试通过研究 Ezh2 调节的 ASM 激活如何导致内皮功能障碍或损伤神经酰胺和富含神经酰胺的膜筏、Nlrp3 炎性体激活、焦亡、内皮- 依赖性血管舒张、内皮间连接破坏和适应性内皮祖细胞着陆或分化。在具体目标 3 中，我们将探讨 Ezh2 功能丧失的分子机制激活 ASM，主要关注 Ezh2ecKO 培养 EC 中组蛋白和 DNA 甲基化的作用小鼠及其野生型同窝小鼠。这些发现将为内皮细胞疾病的发病机制提供新的见解。功能障碍并确定 Ezh2-ASM 通路作为预防或治疗血管病变的治疗靶点与肥胖有关。