Genetic Pathways in Ceramide-Associated Lipotoxic Cardiomyopathy and Heart Failure

总结 心脏病是美国男性和女性死亡的主要原因。肥胖是 快速增长的流行病和心肌病和心力衰竭发展的主要危险因素。的 肥胖相关的心肌病的病理学与脂肪的异常心脏积聚有关， 脂毒性代谢物。预防这种脂毒性作用是心脏病治疗干预的潜在途径 疾病和心力衰竭。然而，心脏脂毒性的分子机制仍然难以捉摸。 在本提案中，我们寻求通过利用我们建立的、强大的 神经酰胺和高脂饮食（HFD）诱导的脂毒性心肌病（LCM）的果蝇心脏模型， 显示在哺乳动物LCM中观察到的LCM样病理，包括收缩性受损和 在任何一种饮食中，甘油三酯脂肪和鞘脂神经酰胺的积累。果蝇是一种 具有高度保守的代谢途径和心脏生理学的通用遗传模型系统，非常适合于 解决LCM的基本机制。尽管如此，我们将在人类中验证我们在果蝇中的发现。 来源于诱导多能干细胞（hiPSC-CM）的心肌细胞，以获得进一步的人类相关的 深入了解LCM的机制（与共同研究者Alexandre Colas博士合作-见信）。 在神经酰胺-蛋白质陷阱实验中，我们确定了3个丰富的假定神经酰胺相互作用的本体 蛋白质（180种推定的重叠小鼠-人CIP）：（1）肌节调节蛋白（40种CIP），包括 肌球蛋白伴侣蛋白Uncoordinated-45 b（Unc 45 b），（2）代谢调节蛋白（33 CIP），包括脂肪 酸性合成酶FcP，和（3）凋亡和DNA损伤反应（DDR）蛋白（21种CIP）。事实上， 果蝇心脏中的心脏Unc 45过表达或FcDNARNAi敲低可防止神经酰胺诱导的LCM。LCM- 诱导和阈下致敏神经酰胺和高脂肪治疗将用于询问上述 参与LCM的CIP。这将是详细确定神经酰胺 与这3类蛋白质相互作用，以及如何破坏或保护心脏功能和体内平衡。 目的是构建和测试肌原纤维维持/脂肪生成/脂肪变性为中心的调控网络 加权与新的CIP，我们将在我们的LCM模型进一步实验评估。

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.