Regulation of Bile Acid Metabolism and Signaling in Metabolic Diseases

项目摘要 糖尿病和非酒精性脂肪肝(NAFLD)与肝脏脂肪和胆固醇密切相关 积聚、肝细胞器功能障碍、低度炎症和血脂异常。患有疾病的患者 糖尿病和非酒精性脂肪性肝病患心血管疾病的风险明显更高，这仍然是主要原因 世界范围内的死亡。肝脏胆汁酸的合成是肝脏胆固醇分解代谢的唯一主要机制 尸体。此外，胆汁酸作为信号分子，关键地控制代谢动态平衡和 炎症反应。针对胆汁酸动力学和信号转导的不同治疗方法 这些途径在治疗代谢性和慢性肝病方面显示出巨大的前景。然而，如何 调控肝胆汁酸信号转导通过不同途径影响复杂代谢网络 其作用机制尚不完全清楚。显然需要新的机械洞察力来 为开发有效的胆汁酸疗法奠定分子基础。这项研究的目标是 明确转录因子EB(TFEB)在调节肝脏胆汁酸代谢中的新作用。TFEB 属于基本螺旋-环-螺旋亮氨酸拉链转录因子家族，最近被发现 作为不同类型细胞中溶酶体生物发生的营养和压力感应主调节因子，这导致了 我们对溶酶体通路如何动态调节的理解发生了范式转变 以各种营养和压力信号来维持细胞内环境的稳定。目前的研究表明，TFEB可能 成为治疗神经退行性疾病、溶酶体储存疾病和新陈代谢疾病的有吸引力的靶点 疾病。然而，TFEB在调节复杂的肝脏代谢中的作用还不完全清楚。 而TFEB对肝脏胆汁酸代谢的调节作用尚未见报道。在这里我们发现TFEB是一个 强烈的胆汁酸合成诱导剂，肝脏TFEB本身受肠道胆汁酸感应的抑制 激素FGF15/19。这种肠道-肝脏信号串扰的识别导致了一个有趣的新概念 以此调控环为靶点增强肝脏TFEB功能和改善代谢 动态平衡。首次确定肝脏TFEB是一种新的胆汁酸敏感性的三个特定目标 转录因子及其在肠道-肝脏胆汁酸信号串扰调节中的关键作用 代谢，并进一步确定其病理生理学意义和治疗意义 信号调节环路。这项研究将通过AAV8介导的几种实验性小鼠模型 肝细胞特异性基因传递、组织特异性基因敲除和药物治疗 接近了。这些模型将结合生理学、分子生物学和细胞进行研究。 生物技术和无偏见的蛋白质组学方法。通过采用这些最先进的模型和 技术，我们的工作假设可以得到严格的检验，并将获得新的机械论见解。

Project Summary Diabetes and non-alcoholic fatty liver disease (NAFLD) are closely associated with hepatic fat and cholesterol accumulation, hepatocyte organelle dysfunction, low grade inflammation, and dyslipidemia. Patients with diabetes and NAFLD have significantly higher risk of cardiovascular disease, which remains the leading cause of death worldwide. Hepatic bile acid synthesis is the only major cholesterol catabolism mechanism in the body. Furthermore, bile acids act as signaling molecules to critically control metabolic homeostasis and inflammatory response. Different therapeutic approaches targeting the bile acid dynamics and signaling pathways have shown great promise for treating metabolic and chronic liver diseases. However, how modulating the enterohepatic bile acid signaling impacts the complex metabolic network via distinct mechanism of actions is still incompletely understood. New mechanistic insights are clearly needed to establish the molecular basis for developing effective bile acid-based therapies. The goal of this study is to define a new role of Transcriptional Factor EB (TFEB) in the regulation of hepatic bile acid metabolism. TFEB belongs to the basic helix-loop-helix leucine zipper family of transcriptional factors and was recently identified as a nutrient and stress-sensing master regulator of lysosomal biogenesis in various cell types, which has led to a paradigm shift in our understanding of how lysosomal pathways can be dynamically regulated in response to various nutrient and stress signals to maintain cellular homeostasis. Current studies suggest that TFEB may be an attractive target for treating neurodegenerative diseases, lysosomal storage disease, and metabolic diseases. However, the role of TFEB in regulating the complex hepatic metabolism is incompletely understood, and the TFEB regulation of hepatic bile acid metabolism has not been explored. Here we found that TFEB is a strong inducer of bile acid synthesis, and hepatic TFEB itself is inhibited by the intestine bile acid sensing hormone FGF15/19. Identification of this gut-liver signaling crosstalk has led to an interesting new concept of pharmacologically targeting this regulatory loop to enhance hepatic TFEB function and improve metabolic homeostasis. Three specific aims are designed to first establish that liver TFEB is a novel bile acid sensing transcriptional factor and a key effector in the gut-liver bile acid signaling crosstalk regulation of liver metabolism, and further determine the pathophysiological significance and therapeutic implications of this signaling regulatory loop. This study will employ several experimental mouse models through AAV8-mediated hepatocyte-specific gene delivery, tissue-specific genetic knockout, and pharmacological treatment approaches. These models will be investigated with a combination of physiological, molecular biology, and cell biology techniques and unbiased proteomics approaches. By employing these state-of-the-art models and techniques, our working hypothesis can be rigorously tested and new mechanistic insights will be obtained.