Regulation of cell fate and function by sterol homeostasis

项目摘要 胆固醇稳态的丧失与许多神经发育和神经退行性疾病有关。 尽管胆固醇介导的作用的确切机制尚不清楚，虽然继承了 已知胆固醇合成酶内的突变会诱导神经发育缺陷， 这些生化缺陷导致的细胞表型背后的机制在很大程度上仍不明确， 细胞和功能水平。因此，描述胆固醇代谢在 神经发育和功能可能会对我们理解潜在的共同点产生重大影响。 疾病的发病机制。干细胞模型显示胆固醇的生化缺陷 合成途径代表了一种新生物学模型，用于研究异常甾醇水平与 导致细胞和功能缺陷的信号事件。使用诱导多能干细胞（iPSC）模型 由于DHCR 7和SC 5D突变，我们最近发现了甾醇生物合成的独特调节作用， 介导Wnt/β-catenin信号传导的蛋白质之间的功能相互作用。在这一建议中，我们将 在干细胞水平上检验胆固醇合成缺陷抑制正常神经发育的假设 通过抑制蛋白质-蛋白质相互作用，使分化模式向神经元细胞类型转变， 神经胶质细胞的消耗，同时抑制突触功能。该项目的目标1将利用基因组测序， 对人类iPSC衍生物和啮齿动物模型进行功能研究，以确定胆固醇稳态缺陷如何发生 调节神经的规格和功能。目标2将改变胆固醇的细胞效应与 通过蛋白质-脂质生物化学分析破坏蛋白质-蛋白质相互作用的体内平衡 互动。体内细胞模型也将定义动力学、特异性和下游信号传导事件 由胆固醇缺陷引起的。这些实验将极大地促进我们对 胆固醇和相关信号在调节神经发育和神经功能，而潜在的 阐明常见神经系统中胆固醇稳态变化的机制基础 疾病

PROJECT SUMMARY Loss of cholesterol homeostasis has been associated with a host of neurodevelopmental and neurodegenerative disorders, though the precise mechanisms underlying cholesterol-mediated effects are unclear. While inherited mutations within cholesterol synthetic enzymes are known to induce neurodevelopmental deficits, the mechanisms behind cellular phenotypes resulting from these biochemical deficits remain largely undefined at the cellular and functional level. Therefore, studies delineating the role of cholesterol metabolism in neurodevelopment and function could have a significant impact on our understanding of potential common mechanisms of disease pathogenesis. Stem cell models exhibiting biochemical defects in the cholesterol synthetic pathway represent a novel biological model to study interactions between abnormal sterol levels and signaling events leading to cellular and functional deficits. Using induced pluripotent stem cell (iPSC) models exhibiting DHCR7 and SC5D mutations, we recently uncovered a unique regulatory role for sterol biosynthesis in the functional interactions between proteins mediating Wnt/β-catenin signaling. Within this proposal, we will test the hypothesis that defects in cholesterol synthesis inhibit normal neurodevelopment at the stem cell level through inhibition of protein-protein interactions, shifting differentiation patterns toward neuronal cell types at the expense of glial cells while inhibiting synaptic function. Aim 1 of this project will utilize genomic sequencing and functional studies in human iPSC derivatives and rodent models to define how defects in cholesterol homeostasis regulate neural specification and function. Aim 2 will correlate the cellular effects of altered cholesterol homeostasis with disrupted protein-protein interactions through biochemical analyses of protein-lipid interactions., In vivo cellular models will also define the kinetics, specificity, and downstream signaling events resulting from cholesterol defects. These experiments will significantly advance our understanding of the role of cholesterol and associated signaling in regulating neurodevelopment and neuronal function, while potentially elucidating the mechanistic underpinnings of cholesterol homeostatic changes in common neurological diseases.