Lipid-Responsive E3 ubiquitin ligases in cholesterol metabolism and atheroscierosis

摘要 阐明影响动脉粥样硬化的胆固醇稳态的新控制机制将取得进展 我们对基本生理过程的理解，并可能为干预提供新的机会 在人类新陈代谢疾病中。我们建议对两者的作用机制和生理功能进行定义 两个新的E3泛素连接酶介导的新的LXR依赖的调节电路。分子机制 调节SREBP-2和LXR通路之间的串扰的机制还知之甚少。使用RNA 测序策略识别新的LXR靶点，我们发现了两个未鉴定的基因-Rnf145和 RNF186-这可能为LXR和SREBP信号之间的串扰提供关键途径。RNF145和 Rnf186编码环状结构域蛋白，预测为E3泛素连接酶；然而，他们的 泛素化靶点和生物功能尚不清楚。我们的初步数据显示， RNF145和RNF186是以前无法识别的SREBP-2信号调制器。Rnf145的操作 Rnf186在小鼠肝脏中的表达调节SREBP-2依赖的基因表达和血浆胆固醇 不同但相辅相成的机制。基于这些发现，我们提出了一系列分子， 细胞生物学和生理学研究确定RNF145和RNF186在胆固醇中的功能 稳态及其对LXR-SREBP串扰的贡献。目的一是阐明其功能和机制。 研究RNF145在脂代谢中的作用。目的2阐明RNF186的功能和作用机制 在脂肪新陈代谢方面。目的3确定RNF145和RNF186对LXR的生理意义。 SREBP串扰和动脉粥样硬化。

Abstract Elucidating new control mechanisms for cholesterol homeostasis that affect atherosclerosis will advance our understanding of fundamental physiological processes and may suggest new opportunities for intervention in human metabolic disease. We propose to define the mechanism of action and physiological function of two new LXR-dependent regulatory circuits mediated by two novel E3 ubiquitin ligases. Molecular mechanisms mediating crosstalk between the SREBP-2 and LXR pathways are poorly understood. Using an RNA sequencing strategy to identify new LXR targets, we have uncovered two uncharacterized genes–Rnf145 and Rnf186–that may mediate critical pathways for crosstalk between LXR and SREBP signaling. Rnf145 and Rnf186 encode RING domain-containing proteins predicted to be E3 ubiquitin ligases; however, their ubiquitination targets and biological function are unknown. Our preliminary data have revealed that both RNF145 and RNF186 are previously unrecognized modulators of SREBP-2 signaling. Manipulation of Rnf145 and Rnf186 expression in mouse liver regulates SREBP-2-dependent gene expression and plasma cholesterol levels by distinct but complementary mechanisms. Based on these findings, we propose a series of molecular, cell biological and physiological studies to define the functions of RNF145 and RNF186 in cholesterol homeostasis and their contribution to LXR-SREBP crosstalk. Aim 1 is to elucidate the function and mechanism of action of RNF145 in lipid metabolism. Aim 2 is to elucidate the function and mechanism of action of RNF186 in lipid metabolism. Aim 3 is to determine the physiological importance of RNF145 and RNF186 for LXR- SREBP crosstalk and atherosclerosis.