Transcriptional Regulation by Angiotensin II in Vascular Smooth Muscle Cells

描述(申请人提供)：动脉粥样硬化性和高血压心血管疾病(心血管疾病)是发病率和死亡率的主要原因，也是我们医疗保健系统的严重压力。多肽激素血管紧张素II(Ang II)在这些病理过程中起主要作用，因为它在靶细胞如血管平滑肌细胞(VSMC)中具有收缩血管、促进氧化、促进生长和炎症的特性。一些研究已证实血管紧张素转换酶II通过1型受体(AT1R)在VSMC发挥作用的生化和信号机制。然而，AngII诱导病理基因转录调控的确切核表观遗传机制尚不清楚。人们越来越认识到染色质结构的深刻变化，包括组蛋白的表观遗传翻译后修饰(PTM)的变化，如组蛋白H3-赖氨酸甲基化(H3Kme)，可以调节基因的“活跃”或“不活跃”状态。最近的证据也证明了microRNAs(MiRs)在转录后机制对基因调控中的关键作用。我们的目标是评估Ang II作用中的表观遗传学和miR机制，以揭示新的治疗靶点。我们推测，组蛋白H3Kme的异常调节和关键miRs的异常表达是Ang II诱导的VSMC功能障碍与多种心血管疾病相关的原因之一。这将通过三个特定的目标进行测试，使用最先进的全基因组图谱和细胞培养中的生物信息学方法以及相关的小鼠模型。具体目的1是对血管紧张素转换酶II处理前后的VSMC中的关键染色质组蛋白H3Kme标记进行表观基因组图谱分析，评估调控这些标记的染色质酶，进而探讨它们在VSMC中的作用。具体目的2是分析血管紧张素转换酶II对血管平滑肌细胞的miR信号的响应，然后确定关键差异表达的miR的功能相关性。具体目标3是评估Ang II作用增强的特定小鼠模型，以确定AIMS 1和2中发现的表观遗传学标记和miR的体内相关性。完成后，拟议的工作将产生描述Ang II处理条件下VSMC表观遗传学和miR谱的新数据，并将新的下一代基因组测序技术引入血管生物学领域。这些结果可以增加我们对Ang II作用的理解，并确定可能被开发为高血压和动脉粥样硬化等心血管疾病临床治疗的新靶点。 与公共卫生相关：尽管有几种治疗方法可用，但动脉粥样硬化和高血压等心血管疾病的发病率正在飙升。此外，这些血管并发症在糖尿病人群中明显更高。加在一起，它们严重消耗了我们的医疗资源。由于血管紧张素II是这些病理过程中的主要参与者，我们建议确定新的表观遗传学和基于微型RNA的新机制，这些机制负责血管紧张素II诱导血管平滑肌细胞中病理基因的表达。我们将使用最先进的图谱技术来实现我们的特定目标，从而推进我们的长期目标，即确定心血管疾病的新机制和药物靶点。

DESCRIPTION (provided by applicant): Atherosclerotic and hypertensive cardiovascular diseases (CVDs) are major causes of morbidity and mortality and a severe strain on our healthcare system. The peptide hormone Angiotensin II (Ang II) plays a major role in these pathologies due to its vasoconstrictive, pro-oxidant, -growth and -inflammatory properties in target cells such as vascular smooth muscle cells (VSMC). Several studies have documented the biochemical and signaling mechanisms of Ang II actions via the type 1 receptor (AT1R) in VSMC. However, the precise nuclear epigenetic mechanisms involved in AngII induced transcriptional regulation of pathological genes are not clear. It is increasingly recognized that profound alterations in chromatin structure, including changes in epigenetic posttranslational modifications (PTMs) of histones, such as Histone H3 -lysine methylation (H3Kme) can regulate the "active" or "inactive" state of genes. Recent evidence has also demonstrated the key roles of microRNAs (miRs) in gene regulation by posttranscriptional mechanisms. Our goal is to evaluate such epigenetic and miR mechanisms in Ang II actions in order to unravel new therapeutic targets. We hypothesize that the dysregulation of histone H3Kme and aberrant expression of key miRs contribute to Ang II induced VSMC dysfunction associated with various CVDs. This will be tested via 3 Specific Aims using state-of-the-art genome-wide profiling and bioinformatics approaches in cell culture along with relevant mouse models. Specific Aim 1 is to perform epigenome profiling of key chromatin histone H3Kme marks in VSMC treated with and without Ang II, evaluate the chromatin enzymes regulating these marks, and then their functional roles in VSMC. Specific Aim 2 is to profile the miR signatures in VSMC in response to Ang II and then determine the functional relevance of key differentially expressed miRs. Specific Aim 3 is to evaluate specific mouse models of increased Ang II action in order to determine the in vivo relevance of the epigenetic marks and miRs uncovered in Aims 1 and 2. When completed, the proposed work will yield novel new data describing the epigenetic and miR profiles of VSMC under Ang II treated conditions, and also bring in new next generation genome sequencing technologies to the field of vascular biology. The results can increase our understanding of Ang II actions, and identify new targets that might be developed as clinical therapies for CVDs such as hypertension and atherosclerosis. PUBLIC HEALTH RELEVANCE: Despite the availability of several therapies, the rates of cardiovascular diseases such as atherosclerosis and hypertension are soaring. Furthermore, these vascular complications are significantly higher in the diabetic population. Together, they are a severe drain on our healthcare resources. Since Angiotensin II is a major player in these pathologies, we propose to identify novel new epigenetic and micro-RNA based mechanisms responsible for Angiotensin II- induced expression of pathologic genes in vascular smooth muscle cells. We will use state-of- the-art profiling technologies to achieve our Specific Aims and thereby advance our long-term goal to identify new mechanisms and drug targets for cardiovascular diseases.