Genetic Pathways in Ceramide-Associated Lipotoxic Cardiomyopathy and Heart Failure

摘要 心脏病是美国男性和女性死亡的主要原因。肥胖是 疫情迅速增长，是发展成心肌病和心力衰竭的主要风险因素。这个 肥胖相关心肌病的病理与心脏脂肪异常堆积和 脂毒性代谢物。预防这种脂毒性效应是心脏治疗干预的潜在途径 疾病和心力衰竭。然而，心脏脂肪毒性的分子机制仍然不清楚。 在这项建议中，我们寻求通过利用我们已建立的、强大的 果蝇心脏神经酰胺和高脂饮食(HFD)诱导的脂毒性心肌病(LCM)模型 在哺乳动物LCM中观察到的LCM样病理，包括收缩能力受损和升高 无论哪种饮食，都会积累甘油三酯脂肪和神经鞘脂神经酰胺。果蝇是一种极端的 具有高度保守的代谢途径和心脏生理的通用遗传模型系统，非常适合于 阐述LCM的基本机制。然而，我们将在人类果蝇身上验证我们的发现 诱导多能干细胞(hiPSC-CMS)来源的心肌细胞获得进一步的人类相关 对LCM机制的见解(与共同研究员Alexandre Colas博士合作--见Letter)。 在神经酰胺-蛋白质陷阱实验中，我们确定了3个可能的神经酰胺相互作用的丰富本体论 蛋白质(180个假定重叠的鼠-人CIPS)：(1)肌瘤调节蛋白(40个CIPS)，包括 肌球蛋白伴侣-45b(Unc45b)，(2)代谢调节蛋白(33CIPS)，包括脂肪 酸性合成酶FASN；(3)细胞凋亡和DNA损伤反应(DDR)蛋白(21CIP)。确实，我发现 在苍蝇心脏中，心脏Unc45的过度表达或FASN RNAi敲除可阻止神经酰胺诱导的LCM。LCM- 将使用诱导性和阈值下敏化神经酰胺和高脂治疗来询问上述情况。 参与LCM的CIPS。这将是详细确定神经酰胺的机制的第一步。 与这3类蛋白质相互作用，以及这如何破坏或保护心脏功能和体内平衡。 其目标是构建和测试以肌原纤维维持/脂肪生成/细胞凋亡为中心的调控网络 我们将在我们的LCM模型中进一步对其进行实验评估。

Summary Heart disease is the leading cause of mortality in the United States in both men and women. Obesity is rapidly growing epidemic and a major risk factor for the development of cardiomyopathies and heart failure. The pathology of obesity-related cardiomyopathies is associated with abnormal cardiac accumulation of fat and lipotoxic metabolites. Preventing such lipotoxic effects is a potential avenue for therapeutic intervention in heart disease and heart failure. However, the molecular mechanisms of cardiac lipotoxicity remain elusive. In this proposal, we seek to address these gaps in knowledge by leveraging our established, robust Drosophila heart models of ceramide- and high-fat-diet (HFD)-induced lipotoxic cardiomyopathy (LCM), which exhibit LCM-like pathology observed in mammalian LCM, including compromised contractility and elevated accumulation of both triglyceride fat and sphingolipid ceramide with either diet. Drosophila is an extremely versatile genetic model system with highly conserved metabolic pathways and cardiac physiology, well suited to address fundamental mechanisms of LCM. Nevertheless, we will validate our findings in Drosophila in human cardiomyocytes that are derived from induced pluripotent stem cell (hiPSC-CMs) to gain further human relevant insights into the mechanisms of LCM (in collaboration with co-Investigator Dr. Alexandre Colas – see letter). In ceramide-protein trap experiments we identified 3 enriched ontologies of putative ceramide interacting proteins (180 putative overlapping mouse-human CIPs): (1) sarcomeric regulatory proteins (40 CIPs), including the myosin chaperone Uncoordinated-45b (Unc45b), (2) metabolic regulatory proteins (33 CIPs), including fatty acid synthase FASN, and (3) apoptosis & DNA damage response (DDR) proteins (21 CIPs). Indeed, found that cardiac Unc45 overexpression or FASN RNAi knockdown in the fly heart prevents ceramide-induced LCM. LCM- inducing and subthreshold-sensitizing ceramide and high fat treatments will be used to interrogate the above CIPs in participating in LCM. This will be the first step in determining in detail the mechanisms how ceramide interacts with these 3 classes of proteins and how that disrupts or protects cardiac function and homeostasis. The goal is to construct and test a myofibrillar maintenance/lipogenesis/ apoptosis-centric regulatory network weighted with novel CIPs, which we will experimentally evaluate further in our LCM models.