Epigenic Control of ENaC Transcription and Sodium Transport

ENaC 转录和钠转运的表观遗传控制

基本信息

批准号：
8039130
负责人：
WENZHENG ZHANG
金额：
$ 25.73万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-03-01 至 2014-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8039130
关键词：
5&apos Flanking Region Acid-Base Equilibrium Adult Age Aldosterone Alternative Splicing American American Heart Association Animals Apical Binding Binding Sites Birth Blood Pressure Cell membrane Cell surface Cells Cessation of life Chromatin Chromosomes, Human, Pair 9 Competitive Binding Complex Coupled Couples DNA DNA Binding Defect Development Down-Regulation Duct (organ) structure Epigenetic Process Epithelial Equilibrium Event Friends Genes Genetic Transcription Genetically Engineered Mouse Genome Glucocorticoid Receptor Goals Grant Histone H3 Homeostasis Homo Hypermethylation In Vitro Ion Channel Kidney Ligands Light Link MLL gene MLLT3 gene Mediating Methylation Methyltransferase Mineralocorticoid Receptor Mineralocorticoids Modeling Molecular Molecular Target Mus Mutation Nephrology Nuclear Nuclear Receptors Pathway interactions Phenotype Phosphorylation Physiological Play Proteins Pseudohypoaldosteronism Regulation Reporting Repression Research Series Sgk protein Signal Pathway Signal Transduction Site Societies Sodium Sodium Channel Syndrome Testing Text Transactivation Transcriptional Activation Transcriptional Regulation Translating Translations Variant absorption base blood pressure regulation chromatin modification derepression epithelial Na+ channel gene repression in vivo mRNA Expression malignant breast neoplasm mouse model neonate novel promoter public health relevance steroid hormone transcription factor uptake

项目摘要

DESCRIPTION (provided by applicant): The broad goal of this project is to define novel epigenetic mechanisms controlling Na+ homeostasis in mIMCD3 cells and in mouse kidney, with ENaC (epithelial sodium channel) as the model. The association of ENaC mutations with Liddle's syndrome and PHA-1 (pseudohypoaldosteronism type 1) as well as the tight and complex regulation of ENaC by aldosterone indicates the importance of ENaC in the regulation of Na+ balance and blood pressure. Aldosterone is a major regulator of Na+ absorption and acts primarily by controlling ENaC function at multiple levels, including transcription and cell surface expression. In the classical model, aldosterone enhances transcription by activating two distinct but similar types of NR (nuclear receptors): MR and GR (mineralocorticoid and glucocorticoid receptors). MR disruption in mouse leads to PHA-1 and animal death around day 10 after birth. Recently, we reported an alternative signaling pathway that couples aldosterone action to chromatin modifications and ENaC1 transcriptional activation through a series of events including reduction of histone H3 K79 methyltransferase Dot1a (disruptor of telomeric silencing 1) and putative transcription factor AF9 (ALL1-fused gene from chromosome 9), SGK1 (serum and glucocorticoid regulated kinase)-mediated phosphorylation of AF9 and thus downregulation of Dot1a-AF9 interaction, and targeted histone H3 K79 hypomethylation at the ENaC1 promoter in mIMCD3 cells. Despite these findings, the putative antagonism between the NR/aldosterone and Dot1a/AF9 complexes remains unaddressed; the correlation between aldosterone-stimulated ENaC transcription and ENaC activity is still not well defined; and the molecular defects derived from MR disruption that result in PHA-1 remain elusive. In this proposal, we intend to fill these gaps. In Aim 1, we will test the hypothesis that the NR-aldosterone and Dot1a-AF9 complexes mutually inhibit the DNA binding activity of their opponent through MR-AF9 and/or GR-AF9 interactions to dynamically control ENaC1 transcription in mIMCD3 cells; Aim 2 will test the hypothesis that changes in ENaC transcription translate into changes in ENaC activity in mIMCD3 cells; and Aim 3 will examine MR-/- mice more fully to test the hypothesis that the components in our new aldosterone network and other ENaC regulatory factors are deregulated by MR deficiency, which contributes to the development of PHA-1, and to confirm the mutual antagonism of the two complexes on ENaC transcription and activity as defined in Aim 1 and 2. Therefore, the proposed studies will 1) integrate the two modes of aldosterone action: activation of NR and relief of Dot1a-AF9-mediated repression; 2) link aldosterone action to chromatin-mediated ENaC transcriptional activation, enhanced ENaC activity and Na+ transport; and 3) shed new light on molecular mechanisms of PHA-1 development. PUBLIC HEALTH RELEVANCE Na+ balance is important for blood pressure control and is primarily achieved by the molecular action of the steroid hormone aldosterone on ENaC, an ion channel that transports Na+ through the cell membrane into the cells. The proposed studies are aimed to define novel mechanisms linking aldosterone action to chromatin modifications, transcriptional activation of ENaC, and enhanced Na+ uptake in mouse kidney, using one existing genetically engineered mouse model.

描述（由申请人提供）：该项目的总体目标是以 ENaC（上皮钠通道）为模型，定义控制 mIMCD3 细胞和小鼠肾脏中 Na+ 稳态的新型表观遗传机制。 ENaC 突变与 Liddle 综合征和 PHA-1（1 型假性醛固酮增多症）的关联以及醛固酮对 ENaC 的严格而复杂的调节表明 ENaC 在 Na+ 平衡和血压调节中的重要性。醛固酮是 Na+ 吸收的主要调节剂，主要通过在多个水平（包括转录和细胞表面表达）控制 ENaC 功能来发挥作用。在经典模型中，醛固酮通过激活两种不同但相似类型的 NR（核受体）来增强转录：MR 和 GR（盐皮质激素和糖皮质激素受体）。小鼠的 MR 破坏导致 PHA-1 和动物出生后第 10 天左右死亡。最近，我们报道了一条替代信号通路，通过一系列事件将醛固酮作用与染色质修饰和 ENaC1 转录激活结合起来，包括减少组蛋白 H3 K79 甲基转移酶 Dot1a（端粒沉默干扰素 1）和假定的转录因子 AF9（来自 ALL1 的融合基因） 9 号染色体），SGK1（血清和糖皮质激素调节激酶）介导的 AF9 磷酸化，从而下调 Dot1a-AF9 相互作用，并靶向 mIMCD3 细胞中 ENaC1 启动子处的组蛋白 H3 K79 低甲基化。尽管有这些发现，NR/醛固酮和 Dot1a/AF9 复合物之间假定的拮抗作用仍未得到解决。醛固酮刺激的 ENaC 转录与 ENaC 活性之间的相关性尚未明确； MR 破坏导致 PHA-1 产生的分子缺陷仍然难以捉摸。在本提案中，我们打算填补这些空白。在目标 1 中，我们将测试以下假设：NR-醛固酮和 Dot1a-AF9 复合物通过 MR-AF9 和/或 GR-AF9 相互作用相互抑制对手的 DNA 结合活性，从而动态控制 mIMCD3 细胞中的 ENaC1 转录；目标 2 将检验以下假设：ENaC 转录的变化会转化为 mIMCD3 细胞中 ENaC 活性的变化；目标 3 将更全面地检查 MR-/- 小鼠，以检验我们的新醛固酮网络中的成分和其他 ENaC 调节因子因 MR 缺陷而失调的假设，这有助于 PHA-1 的发育，并确认相互之间的相互作用。两种复合物对 ENaC 转录和活性的拮抗作用如目标 1 和 2 中所定义。因此，拟议的研究将 1) 整合醛固酮作用的两种模式：激活 NR 和缓解Dot1a-AF9介导的抑制； 2) 将醛固酮作用与染色质介导的 ENaC 转录激活、增强的 ENaC 活性和 Na+ 转运联系起来； 3) 揭示 PHA-1 发育的分子机制。公共卫生相关性 Na+ 平衡对于血压控制很重要，主要是通过类固醇激素醛固酮对 ENaC 的分子作用来实现的，ENaC 是一种将 Na+ 通过细胞膜转运到细胞中的离子通道。拟议的研究旨在利用一种现有的基因工程小鼠模型，确定将醛固酮作用与染色质修饰、ENaC 转录激活以及小鼠肾脏中 Na+ 吸收增强联系起来的新机制。