Determining hepatocyte-specific mechanisms by which Ube4A regulates NAFLD/NASH

项目总结 肥胖是NAFLD/NASH的主要风险因素。在肥胖患者中，能量积累会导致代谢功能障碍 和内质网(ER)和氧化应激，导致组织炎症和损伤，这是 纳什的特征。DNA损伤反应和未折叠蛋白反应是维持完整性的关键 细胞基因组和蛋白质组。内质网通过内质网相关蛋白的降解来维持蛋白稳定，并 未折叠的蛋白质反应。代谢功能障碍改变内质网相关蛋白降解和未折叠蛋白 反应，导致内质网应激，半胱氨酸天冬氨酸酶激活和细胞死亡。此外，氧化应激增加 增强DNA损伤诱导的细胞死亡。确定这些途径如何整合以决定细胞代谢 生存是查克拉博蒂实验室的长期目标。这项提议的目标是破译这一角色 E3泛素连接酶Ube4A在IP6K1蛋白介导的肥胖肝细胞代谢功能障碍中的作用 DNA损伤反应和未折叠蛋白反应介导肝细胞存活和NAFLD/NASH。 最重要的假设是Ube4A维持代谢动态平衡，保护肝细胞免受 应激导致死亡，延缓肥胖和NAFLD/NASH的发展和进展。其基本原理是 确定Ube4A在NAFLD/NASH中的作用及其调节肝细胞的机制 新陈代谢和生存将提供新的治疗机会。我们的具体目标将检验以下几点 假设：(目的1)测试全身和肝细胞Ube4A缺失对代谢功能障碍的影响， 目的2)探讨Ube4A介导的IP6K1抑制机制和 对小鼠代谢紊乱和非酒精性脂肪肝/非酒精性脂肪肝的影响；(目的3)破译 Ube4A调节肝细胞存活。这一贡献意义重大，具有变革性，因为这是意料之中的 揭示一条调节肥胖、胰岛素抵抗和肝脏脂肪变性的新途径的作用 区分该通路对NAFLD/NASH的肝细胞特异性影响。此外，这是第一步， 明确Ube4A如何调节肝细胞代谢和存活的机制，以及肥胖如何 IP6K1蛋白在体内受到调节。这些令人兴奋的发现可能会导致开发新的治疗方法 肥胖症和NAFLD/NASH的治疗方法。拟议的研究是创新的，因为它将利用令人兴奋的新技术 解开调节细胞新陈代谢和存活的新途径的工具，这与治疗相关 对许多疾病都有广泛的影响。

Project summary Obesity is a major risk factor for NAFLD/NASH. In obesity, energy accumulation causes metabolic dysfunction and endoplasmic reticulum (ER) and oxidative stress, leading to tissue inflammation and injury, which are hallmarks of NASH. The DNA damage response and unfolded protein response are vital to maintain the integrity of cellular genome and proteome. The ER maintains proteostasis via ER-associated protein degradation and unfolded protein response. Metabolic dysfunction alters ER-associated protein degradation and unfolded protein response, leading to ER stress, caspase activation and cell death. Moreover, increased oxidative stress enhances DNA damage-induced cell death. Defining how these pathways integrate to dictate cell metabolism and survival is the long-term goal of The Chakraborty lab. The objective of this proposal is to decipher the role of the E3 ubiquitin ligase Ube4A in the obesogenic IP6K1 protein-mediated hepatocyte metabolic dysfunction and DNA damage response and unfolded protein response mediated hepatocyte survival and NAFLD/NASH. The overarching hypothesis is that Ube4A maintains metabolic homeostasis and protects hepatocytes from stress-induced death, delaying the development and progression of obesity and NAFLD/NASH. The rationale is that determining the role of Ube4A in NAFLD/NASH and the mechanisms by which it regulates hepatocyte metabolism and survival will provide new therapeutic opportunities. Our specific Aims will test the following hypotheses: (Aim 1) Test the impact of whole-body- and hepatocyte-Ube4A deletion on metabolic dysfunction, liver injury, and NAFLD/NASH in mice; (Aim 2) Determine mechanisms of Ube4A-mediated IP6K1 inhibition and its impact on metabolic dysfunction and NAFLD/NASH in mice; (Aim 3) Decipher the mechanisms by which Ube4A regulates hepatocyte survival. The contribution is significant and transformative because it is expected to unravel the role of a novel pathway that regulates obesity, insulin resistance and hepatic steatosis and distinguish the hepatocyte-specific impact of this pathway on NAFLD/NASH. Moreover, it is the first step to defining the mechanisms of how Ube4A regulates hepatocyte metabolism and survival and how the obesogenic protein IP6K1 is modulated in vivo. These exciting findings could lead to development of new therapeutic approaches to treat obesity and NAFLD/NASH. The proposed research is innovative as it will utilize exciting new tools to unravel a novel pathway that regulates cell metabolism and survival, which is therapeutically relevant and has broad implications for many diseases.