Studies of nuclear receptor corepressor, NRIP1, in vitamin A signaling pathways

描述（由申请人提供）：视黄酸（RA）是维生素A的生物活性形式，对多种生物过程至关重要。RA与核受体、视黄酸受体（RAR）和类视黄酸受体X（RXR）结合，通过触发辅调节因子的募集来调节靶基因的表达，辅调节因子主要通过染色质重塑和修饰靶基因的调节区域来起作用。核受体相互作用蛋白1（Nuclear Receptor Interacting Protein 1，NRIP 1，最初称为RIP 140）是一种配体依赖性共阻遏物，即它以配体依赖性方式抑制靶基因表达的激素诱导。该项目的长期目标是了解维生素A信号的稳态控制机制。该提案的重点是由RIP 140和与激素受体形成复合物的辅激活因子（如RIP 140-RAR/RXR复合物和辅激活因子-RAR/RXR复合物）协调的染色质重塑事件，以及几种新发现的翻译后修饰在受体/辅调节因子活性调节中的生物学意义。本文将探讨两个问题：1）RIP 140在细胞凋亡诱导的染色质重塑中的作用机制。2)蛋白质修饰如何调节RIP 140的生物活性？将使用野生型和遗传修饰细胞（包括RIP 140敲除（RIP-/-）和TRAP 220敲除（TRAP-/-）细胞）以及P19细胞中siRNA介导的基因敲减作为主要实验系统。含有激素反应元件（HRE）的染色质片段将是检查的目标，以解决生理相关背景下的机制细节。这些研究将通过协调形成特定的转录因子复合物，为激素（维生素A和甲状腺激素）的串扰提供机制见解。这些研究还将揭示潜在的新信号和细胞因子，这些信号和细胞因子对细胞分化程序至关重要，维生素A和其他内分泌因子在细胞分化程序中发挥着重要作用。从这些研究中获得的知识也可用于了解受激素和营养因素影响或涉及激素和营养因素的临床疾病，例如代谢疾病，这些研究还将描述营养素（例如维生素A）在维持人类健康方面的作用。公共卫生相关性：视黄酸（RA）是维生素A的生物活性形式，对多种生物过程至关重要。RA通过染色质重塑调节靶基因表达发挥作用，该染色质重塑涉及核受体相互作用蛋白1（NRIP 1，最初称为RIP 140）。该项目的长期目标是了解维生素A信号的稳态控制机制。目前的建议侧重于NRIP 1的功能作用，从机械的角度来看。从这些研究中获得的知识也可以应用于了解受激素和营养因素影响或涉及激素和营养因素的临床疾病，如代谢疾病。这些研究还将阐明营养素，如维生素A，在维持人类健康方面的作用。

DESCRIPTION (provided by applicant): Retinoic acid (RA), the biologically active form of Vitamin A, is essential for a variety of biological processes. RA binds to nuclear receptors, retinoic acid receptor (RAR) and retinoid receptor X (RXR), to regulate target gene expression by triggering recruitment of coregulators that act, primarily, through chromatin remodeling and modification on the regulatory regions of target genes. Nuclear Receptor Interacting Protein 1 (NRIP1, originally known as RIP140) is a ligand-dependent co-repressor, i.e. it represses hormonal induction of target gene expression in a hormone-dependent manner. The long-term goal of this project is to understand the mechanisms underlying homeostatic control of vitamin A signaling. The proposal focuses on chromatin remodeling events orchestrated by RIP140 and coactivators that form complexes with hormone receptors, such as RIP140-RAR/RXR complex and coactivator-RAR/RXR complexes, as well as the biological significance of several newly identified post-translational modifications in the modulation of receptor/coregulator activities. Two questions will be addressed: 1) how does RIP140 function in hormone-induced chromatin remodeling? 2) How does protein modification regulate the biological activity of RIP140? Wild type and genetically modified cells, including RIP140-knockout (RIP-/-) and TRAP220-knockout (TRAP-/-) cells, as well siRNA mediated gene knockdown in P19 cells will be used as the principal experimental systems. Chromatin segments containing hormone response elements (HREs) will be the targets of examination to address mechanistic details in a physiologically relevant context. These studies will provide mechanistic insights into crosstalk of hormones (vitamin A and thyroid hormones) via coordinated formation of specific transcription factor complexes. These studies will also uncover potentially novel signals and cellular factors that are critical to cell differentiation program where vitamin A and other endocrine factors play vital roles. Knowledge gained from these studies could also be applied to understand clinical diseases that are affected by, or involve, hormonal and nutritional factors, such as metabolic diseases, the studies will also delineate the role of nutrients, such as vitamin A, in the maintenance of human health. PUBLIC HEALTH RELEVANCE: Retinoic acid (RA), the biologically active form of Vitamin A, is essential for a variety of biological processes. RA functions by regulating target gene expression through chromatin remodeling that involves Nuclear Receptor Interacting Protein 1 (NRIP1, originally known as RIP140). The long-term goal of this project is to understand the mechanisms underlying homeostatic control of vitamin A signaling. The current proposal focuses on the functional role of NRIP1 from a mechanistic stand point. Knowledge gained from these studies could also be applied to understand clinical diseases that are affected by, or involve, hormonal and nutritional factors, such as metabolic diseases. The studies will also delineate the role of nutrients, such as vitamin A, in the maintenance of human health.