Epigenetic Mechanisms Regulating Chronic Intermittent Hypoxia-evoked Sympathetic Activation

项目摘要-项目4 项目4的总体目标是评估交感神经激活背后的表观遗传机制 由间歇性缺氧(IH)引起，这是睡眠呼吸暂停的主要表现。赖氨酸对组蛋白的修饰 乙酰化是一种主要的表观遗传机制。赖氨酸乙酰化是由组蛋白之间的平衡决定的 乙酰基转移酶(HATS)和组蛋白脱乙酰基酶(HDACs)。初步数据显示：a)IH抑制 HDAC活性对HAT活性几乎或没有影响，b)IH诱导组蛋白(H)-3，c)赖氨酸乙酰化 乙酰化是IH启动的一种早期表观遗传机制，d)抑制HDAC活性导致HIF-1- 稳定和转录。基于初步数据，项目4检验了IH诱发的假设 缺氧诱导因子-1的转录激活需要缺氧诱导因子-1α蛋白和组蛋白-3的赖氨酸乙酰化，进而 激活DNA甲基转移酶，导致DNA甲基化和持久的交感神经激活。这 假说将在大鼠嗜铬细胞瘤(PC)-12细胞培养、暴露于IH的完整大鼠和小鼠身上进行测试 表现为自发性睡眠呼吸暂停，并使用分子、生化和生理方法。研究 在Aim1中，评估IH如何抑制HDAC活性。AIM2中的实验确定了HDAC活性如何降低 由IH激活HIF-1介导的转录。目标3确定赖氨酸激活HIF-1的后果 乙酰化对IH引起的交感神经激活的影响。目的4确定赖氨酸乙酰化是否通过短期IH 通过长期的IH导致DNA甲基化。项目4的主要概念和技术创新是：a) 假设短期IH导致的赖氨酸乙酰化驱动长期IH诱导的DNA甲基化 在概念上是新颖的，并为自主神经的发展提供了新的机械论分子见解 睡眠呼吸暂停从可逆型到不可逆型背景下的功能障碍，以及b)评估 实验性高血压啮齿动物模型对表现为自然睡眠呼吸暂停的小鼠的意义。 项目4与项目1、2、3和4有紧密的主题联系，并利用核心B设施来展示 啮齿动物和细胞培养到IH。调查小组由分子生物学家、表观遗传学和 对建议的方法和轨道具有长期经验和专业知识的生理学家 由联合出版物证明的共同工作多年的记录。圆满完成 项目4预计将为疾病从可逆到 不可逆表型，目前尚无相关信息。

Project Summary- Project 4 The overall goal of the Project 4 is to assess the epigenetic mechanisms underlying sympathetic activation caused by intermittent hypoxia (IH), a major manifestation of sleep apnea. Histone modification by lysine acetylation is a major epigenetic mechanism. Lysine acetylation is determined by equilibrium between histone acetyltransferases (HATs) and histone deacetylases (HDACs). Preliminary data showed that: a) IH inhibits HDAC activity with little or no effect on HAT activity, b) IH induces lysine acetylation of histone (H)-3, c) lysine acetylation is an early epigenetic mechanism initiated by IH, and d) Inhibiting HDAC activity results in HIF-1- stabilization and transcription. Based on the preliminary data, Project 4 tests the hypothesis that IH-evoked HIF-1 transcriptional activation requires lysine acetylation of the HIF-1α protein and histone-3, which in turn activates DNA methyl transferases leading to DNA methylation and long-lasting sympathetic activation. This hypothesis will be tested in rat pheochromocytoma (PC)-12 cell cultures, intact rats exposed IH, and in mice exhibiting spontaneous sleep apnea and uses molecular, biochemical and physiological approaches. Studies in Aim1 assess how IH inhibits HDAC activity. Experiments in Aim2 determine how decreased HDAC activity by IH activates HIF-1-mediated transcription. Aim 3 determines the consequences of HIF-1 activation by lysine acetylation on IH-evoked sympathetic activation. Aim 4 determines whether lysine acetylation by short-term IH leads to DNA methylation by long-term IH. Major conceptual and technical innovations of the Project 4 are: a) the hypothesis that lysine acetylation by short-term IH drives the long-term IH-induced DNA methylation is conceptually novel, and provides new mechanistic molecular insights into the progression of autonomic dysfunction in the context of sleep apnea from a reversible to a non-reversible phenotype, and b) assessing the significance of findings from experimental rodent model of IH in mice exhibiting natural sleep apnea. Project 4 has tight thematic linkages with Projects 1, 2, 3, and 4 and utilizes Core B facilities for exposing rodents and cell cultures to IH. Investigative team consists of molecular biologists, epigenesists, and physiologists who have long-standing experience and expertise with the proposed approaches and a track record of working together for number years as evidenced by joint publications. Successful completion of the Project 4 is anticipated to provide much needed molecular basis for progression of disease from a reversible to non-reversible phenotype, wherein currently no information is available.