Novel Role of Bscl2 in Cardiac Substrate Metabolism and Function

项目摘要 代谢紊乱是多种心肌病的基础。目前，尚无特效治疗方法 用于预防心肌病发作或进展为心力衰竭，心力衰竭是死亡的主要原因之一 世界各地的残疾人。BSCL 2/Seipin是一种高度保守的内质网蛋白，广泛分布于 与脂滴生物发生和甘油三酯（TG）代谢有关。然而，分子机器 负责BSCL 2调节的心脏脂质代谢尚未阐明。这批地址小说 BSCL 2、TG脂解和心脏线粒体功能之间的联系。我们发现心脏BSCL 2 缺失增加了脂肪甘油三酯脂肪酶（ATGL）的表达和脂肪酸（FA）的氧化，并导致TG 随着年龄的增长而减少和轻度心功能不全。然而，BSCL 2缺失完全挽救了致死性代谢 ATGL缺陷小鼠的心肌病。这是通过恢复心脏TG脂解和FA氧化来实现的， 表明在BSCL 2下游存在其它非ATGL TG脂肪酶/参与者。我们进一步雇用 Bscl 2基因敲入小鼠和蛋白质组学研究表明，Bscl 2与线粒体蛋白相互作用， 与存在于与线粒体（MAM）相关的ER膜中的蛋白质分离。因此， 假设BSCL 2介导不依赖于ATGL的TG催化剂、ER-线粒体偶联， 线粒体功能，从而心脏稳态和脂毒性心肌病。目标1将阐明 一种新的TG脂肪酶在心脏中的重要性和机制，它控制心脏甘油三酯水解， BSCL 2下游的FA氧化。目的2将确定BSCL 2是否与特定的线粒体相互作用 蛋白质在ER/线粒体接触位点介导线粒体功能和脂毒性心肌病。这 这项研究非常重要，因为它定义了BSCL 2介导的新组分和分子机制。 调节心脏TG代谢、MAM、线粒体代谢和心脏的ATGL非依赖性途径 功能，这可能为代谢性疾病的新治疗方法奠定知识基础。 心肌病

Project Summary Metabolic perturbations underpin a wide variety of cardiomyopathies. Currently, there are no specific treatments for preventing the onset or progression of cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. BSCL2/Seipin is a highly conserved endoplasmic reticulum (ER) protein widely implicated in lipid droplet biogenesis and triglyceride (TG) metabolism. However, the molecular machinery responsible for BSCL2-regulated cardiac lipid metabolism has not been elucidated. This grant addresses novel linkages between BSCL2, TG lipolysis, and mitochondrial function in the heart. We found that cardiac BSCL2 deletion elevates adipose triglyceride lipase (ATGL) expression and fatty acid (FA) oxidation, and causes TG reduction and mild cardiac dysfunction with age. However, BSCL2 deletion completely rescues lethal metabolic cardiomyopathy in ATGL-deficient mice. This was achieved by restoring cardiac TG lipolysis and FA oxidation, suggesting the presence of other non-ATGL TG lipase (s)/players downstream of BSCL2. We further employed Bscl2 knock-in mouse and proteomics and showed that BSCL2 interacts with mitochondrial protein and co- fractionates with proteins present in ER membranes associated with mitochondria (MAM). We, therefore, hypothesize that BSCL2 mediates ATGL-independent TG catabolism, ER-mitochondria coupling, and mitochondrial function thus cardiac homeostasis and lipotoxic cardiomyopathy. Aim 1 will elucidate the importance and mechanisms of a novel TG lipase in the heart that controls cardiac triglyceride hydrolysis and FA oxidation downstream of BSCL2. Aim 2 will define whether BSCL2 interacts with a specific mitochondrial protein at ER/mitochondria contact sites to mediate mitochondrial function and lipotoxic cardiomyopathy. This study is highly significant as it defines the novel components and molecular machinery of BSCL2-mediated ATGL-independent pathways that regulate cardiac TG metabolism, MAM, mitochondrial metabolism, and heart function, which can potentially lay an intellectual groundwork for novel therapeutic approaches to metabolic cardiomyopathy.