Histone deacetylase 9 is an epigenetic suppressor of intrarenal angiotensinogen, serving as a key mechanism in angiotensinogen augmentation in hypertension

组蛋白脱乙酰酶 9 是肾内血管紧张素原的表观遗传抑制因子，是高血压血管紧张素原增加的关键机制

• 批准号: 9008798
• 负责人: Ryosuke Sato
• 金额: $ 27.09万
• 依托单位: TULANE UNIVERSITY OF LOUISIANA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9008798
• 关键词: Address; Aldosterone; Angiotensinogen; Animal Model; Attenuated; Binding Sites; Cell model; Cells; Chronic; Clinical; Complex; Development; Disease; Dose; Down-Regulation; Enzymes; Epigenetic Process; Exhibits; Female; Gender; Genes; Genetic Transcription; Glucose; Goals; HDAC9 gene; Histone Deacetylase; Histone Deacetylation; Human; Hypertension; Immune; Infection; Infiltration; Injury; Interleukin-6; Kidney; Knockout Mice; Liver; Mediating; Morbidity - disease rate; Mus; Outcome; Plasma; Process; Rattus; Regulation; Renin; Renin-Angiotensin System; Rodent; Role; Small Interfering RNA; Specificity; Stimulus; System; Tissues; Transfection; Transgenic Mice; Tubular formation; Up-Regulation; activating transcription factor; cell type; cytokine; extracellular; gender difference; gender disparity; genetically modified cells; in vivo; inhibitor/antagonist; kidney cell; knock-down; male; mortality; nephrogenesis; novel; overexpression; promoter; public health relevance; research study; response; treatment duration

 DESCRIPTION (provided by applicant): Augmented intrarenal angiotensinogen (AGT) is a critical contributor to the activation of intrarenal renin- angiotensin system (RAS) which leads to the development of hypertension and associated tissue injury. Therefore, elucidating mechanisms underlying AGT upregulation is essential for the development of strategies to treat these diseases. Chronic Ang II elevation induces increased immune cell infiltration in the kidneys contributing to increase in intrarenal cytokine levels specifically interleukin 6 (IL-6). Notably, IL-6 is required for Ang II-induced AGT augmentation in renal proximal tubular cells (PTC). However, the cellular mechanisms underlying these complex interactions leading to AGT augmentation have not been delineated. Renal cortical AGT levels are lower in female rodents than in males under normal conditions; however, plasma and liver AGT levels do not exhibit this gender disparity, suggesting that kidneys have a unique mechanism inherent to establishing basal AGT levels. Our preliminary studies demonstrated that histone deacetylase 9 (HDAC9) levels are higher in the kidneys of female rats than those of male rats and that HDAC9 inhibitions by siRNA and an inhibitor resulted in augmentation of AGT levels in PTC. These results indicate that HDAC9 is a suppressor of intrarenal AGT expression. Since HDACs suppress gene transcription by histone-deacetylation, changes in HDAC levels alter accessibility of activated transcription factors to their binding sites on gene promoters. The preliminary study showed that HDAC9 levels are decreased by Ang II in PTC. Accordingly, we hypothesize that downregulation of HDAC9 by Ang II reduces the suppressive effects of HDAC9 on AGT expression. This allows other transcription factors activated by pathological stimuli, in particula IL-6, to augment AGT expression, thus leading to the progression of hypertension and associated tissue injury in Ang II-dependent hypertension. To address this hypothesis, we will establish that Ang II suppresses intrarenal HDAC9 levels during the development of Ang II-dependent hypertension using unique PTC and Ang II- dependent hypertensive animal models (Specific Aim 1). In addition, the proposed studies will demonstrate that Ang II-induced intrarenal HDAC9 downregulation is required for intrarenal AGT augmentation by synergistic effects of Ang II and IL-6 and consequent development of hypertension (Specific Aim 2). In these experiments, HDAC9 knockdown by siRNA and overexpression via AAV2 infection will be used to show that the HDAC9 knockdown and IL-6 synergistically augment AGT expression in PTC and that kidney-specific HDAC9 overexpression attenuates intrarenal AGT elevation facilitating consequent the development of kidney injury in Ang II-dependent hypertension. Gender differences of intrarenal HDAC9 regulation and its contribution to AGT regulation in hypertension will also be investigated in the projects. The results will establish the cardinal rol of intrarenal HDAC9 in the regulation of intrarenal AGT in Ang II-dependent hypertension and provide a mechanistic rationale for targeting HDAC9 to treat hypertension and RAS associated tissue injury.

 描述（由应用提供）：增强的肾内血管紧张素原（AGT）是培养肾上腺内血管紧张素系统（RAS）的关键因素，该系统导致 高血压和相关组织损伤的发展。因此，阐明AGT上调的基础机制对于制定治疗这些疾病的策略至关重要。慢性ANG II升高诱导会增加肾脏中的免疫球浸润，从而有助于肾内细胞因子水平升高，特别是白介素6（IL-6）。值得注意的是，ANG II诱导的肾近端肾小管细胞（PTC）中ANG诱导的AGT增强所必需的IL-6。然而，尚未描述这些复杂相互作用的基础机制。在正常情况下，雌性啮齿动物的肾皮质AGT水平低于男性。但是，血浆和肝AGT水平没有表现出这种性别差异，这表明肾脏具有建立基本AGT水平的独特机制。我们的初步研究表明，雌性大鼠肾脏的组蛋白脱乙酰基酶9（HDAC9）水平高于雄性大鼠的肾脏水平，而siRNA抑制HDAC9和抑制剂会导致PTC中AGT水平的增强。这些结果表明HDAC9是培养室内AGT表达的抑制剂。由于HDAC通过组蛋白二乙酰化抑制基因转录，因此HDAC水平的变化改变了激活的转录因子对基因启动子上结合位点的可访问性。初步研究表明，PTC中的ANG II提高了HDAC9水平。根据，我们假设ANG II对HDAC9的下调减少了HDAC9对AGT表达的抑制作用。这允许在颗粒IL-6中被病理刺激激活的其他转录因子增强AGT表达，从而导致ANG II依赖性高血压中高血压和相关组织损伤的进展。为了解决这一假设，我们将确定在使用独特的PTC和ANG II依赖性高血压动物模型的ANG II依赖性高血压的发展过程中，ANG II抑制了肾内HDAC9水平（特定目标1）。此外，拟议的研究将表明，ANG II和IL-6的协同作用以及随之而来的高血压发展需要ANG II诱导的肾内HDAC9下调（特定目标2）。 In these experiments, HDAC9 knockdown by siRNA and overexpression via AAV2 infection will be used to show that the HDAC9 knockdown and IL-6 synergistically augment AGT expression in PTC and that kidney-specific HDAC9 overexpression attenuates intrarenal AGT elevation supporting consequent the development of kidney injury in Ang II-dependent hypertension.在项目中，还将研究肾内HDAC9调节的性别差异及其对高血压AGT调节的贡献。该结果将确定肾内HDAC9在ANG II依赖性高血压中调节肾内AGT中的基本作用，并为靶向HDAC9治疗高血压和RAS相关组织损伤提供了机械原理。