Regulation of Bile Acid Metabolism and Signaling in Metabolic Diseases

项目摘要 糖尿病和非酒精性脂肪性肝病（NAFLD）与肝脏脂肪和胆固醇密切相关 在某些实施方案中，所述药物可用于治疗肝细胞蓄积、肝细胞器功能障碍、低度炎症和血脂异常。患者 糖尿病和NAFLD的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胆汁酸合成是胆固醇代谢的唯一主要机制。 身体此外，胆汁酸作为信号分子来严格控制代谢稳态， 炎症反应。针对胆汁酸动力学和信号传导的不同治疗方法 已经显示出治疗代谢和慢性肝病的巨大前景。但如何 调节肝肠胆汁酸信号通过不同的途径影响复杂的代谢网络， 其作用机制尚不完全清楚。显然需要新的机械见解， 为开发有效的基于胆汁酸的疗法建立分子基础。本研究的目的是 定义转录因子EB（TFEB）在调节肝胆汁酸代谢中的新作用。TFEB 属于碱性螺旋-环-螺旋亮氨酸拉链转录因子家族， 作为各种细胞类型中溶酶体生物发生的营养和应激感应主调节剂， 我们对溶酶体途径如何在反应中动态调节的理解发生了范式转变， 各种营养和压力信号来维持细胞内稳态。目前的研究表明，TFEB可能 是治疗神经变性疾病、溶酶体贮积病和代谢性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尚不完全清楚， TFEB对肝胆汁酸代谢的调节作用尚未研究。我们发现TFEB是一个 胆汁酸合成的强诱导剂，并且肝TFEB本身被肠胆汁酸感应抑制 激素FGF 15/19。对这种肠-肝信号串扰的识别导致了一个有趣的新概念， 靶向该调节环以增强肝脏TFEB功能并改善代谢 体内平衡设计了三个具体目标，以首先确定肝脏TFEB是一种新的胆汁酸传感 肝胆汁酸信号转导调控中的转录因子和关键效应子 代谢，并进一步确定病理生理学意义和治疗意义，这 信号调节环本研究将采用几种实验小鼠模型，通过AAV 8介导的 肝细胞特异性基因递送、组织特异性基因敲除和药物治疗 接近。这些模型将结合生理学、分子生物学和细胞生物学进行研究。 生物技术和无偏见的蛋白质组学方法。通过使用这些最先进的模型， 技术，我们的工作假设可以得到严格的测试和新的机制的见解将获得。

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.