2014-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/648541摘要：轉錄因子Liver receptor homologue-1 (LRH-1) 屬於核受器NR5A家族之成員。LRH-1影響許多發育的過程，LRH-1缺失會造成胚胎的死亡。LRH-1主要表現於肝臟、胰臟、小腸、卵巢及前脂肪細胞。在肝臟，LRH-1調控很多基因的表現，影響了各種不同的代謝途徑，包括葡萄糖與脂肪代謝、膽酸生合成以及膽固醇恆定作用。此外，LRH-1表現於卵巢與前脂肪細胞，調控類固醇生成基因的表現，對於乳癌發展也有重要之影響。 細胞在接受環境的刺激與壓力，會引發應對的生理反應，轉錄因子調控基因的轉錄作用在此過程扮演關鍵的角色。因此，轉錄因子的表現量需能夠適時嚴密地調整，這可藉由各種不同方式達成。控制蛋白質穩定性與降解是調控轉錄因子的一種重要方法。在探討LRH-1蛋白質穩定性的研究中，我們以MG-132抑制蛋白酶體活性，會顯著地增加LRH-1蛋白質的量。給予泛素則可偵測到LRH-1與多泛素鍊結合，這說明了LRH-1會經由泛素-蛋白酶體路徑被降解。初期的研究，我們已找到幾個可能參與調控LRH-1蛋白質降解的E3泛素連接酶。本計畫將深入研究調控LRH-1蛋白質降解與穩定性的分子機制，並探討其對LRH-1功能之影響。基於LRH-1在肝臟諸多代謝功能有重要的作用，我們也將探討在某種生理狀況下，如胰島素刺激，LRH-1蛋白質量改變的調控機轉。計畫的主要研究目標包括： 目標一：研究CUL4-RING E3連接酶調控LRH-1降解的機制 目標二：研究Ndfip1調控LRH-1穩定性的機制 目標三：探討胰島素調控LRH-1穩定性的機制 透過此研究，我們將可清楚了解調控LRH-1蛋白質穩定性的分子機制以及LRH-1蛋白質量的變化在肝臟代謝作用的重要意義，對相關代謝疾病的了解與治療也可有所貢獻。<br> Abstract: LRH-1 (liver receptor homologue-1; NR5A2) is a member of the orphan nuclear receptor NR5A subfamily. LRH-1 is involved in multiple developmental processes and inactivation of LRH-1 results in embryonic lethality. LRH-1 is mainly expressed in liver, pancreas, intestine, ovary and preadipocytes. LRH-1 functions as a crucial transcriptional regulator affecting diverse metabolic pathways in the liver, including glucose and lipid metabolism, bile acid synthesis and cholesterol homeostasis. In addition, LRH-1 regulates the expression of genes required for steroid hormone biosynthesis in the ovary and preadipocytes and plays a role in breast tumor development. Transcription factors regulate gene transcription that plays a key role in controlling appropriate physiological response to extracellular modulators and stress. The levels of transcription factors are thus needed to be tightly regulated that can be controlled in various ways. The control of protein stability and degradation plays a crucial role in the regulation of a number of transcription factors. We previously studied the regulation of LRH-1 protein stability and observed that inhibition of proteasome activity by 26S proteasome inhibitor MG-132 dramatically increased the protein levels of LRH-1. Coexpression of LRH-1 with ubiquitin revealed that LRH-1 was conjugated with polyubiquitin, indicating that LRH-1 is degraded via ubiquitin-proteasome pathway. We have found some potential E3 ubiquitin ligases that may involved in the regulation of LRH-1 degradation. This proposal will study the molecular mechanisms to regulate the proteolysis and stability of LRH-1 protein and their consequences on the transcriptional control of LRH-1 target genes. Due to the important roles of LRH-1 in hepatic metabolism, we will further explore the mechanisms controlling LRH-1 protein levels under certain physiological conditions such as the insulin response. The specific aims are: Aim 1: To investigate the regulation of LRH-1 degradation by CUL4-RING E3 ligase Aim 2: To investigate the regulation of LRH-1 stability by Ndfip1 Aim 3: To elucidate the mechanism underlying insulin modulation in LRH-1 stability This study will gain insight into the regulation of LRH-1protein stability and the significance of LRH-1 alterations in hepatic metabolism. The efforts from this research should contribute to the understanding and therapeutic approaches in metabolic diseases.核受器 LRH-1泛素-蛋白酶體路徑cullin E3泛素連接酶Ndfip1蛋白質胰島素Liver receptor homologue-1 (LRH-1)ubiquitin-proteasome pathwaycullin E3 ligaseNdfip1insulin