mTOR complexes in oligodendrocyte differentiation

描述（由申请人提供）：中枢神经系统中，少突胶质细胞以髓鞘包裹轴突，促进动作电位传导。轴突髓鞘形成在发育过程中涉及到少突胶质细胞的增殖、分化和髓鞘的产生。控制这一过程的细胞内信号机制才刚刚开始被阐明。我们实验室先前的数据表明，哺乳动物雷帕霉素靶点（mTOR）对少突胶质细胞分化至关重要。mTOR是PI3K/Akt的下游靶点，通过与衔接蛋白raptor （mTORC1）或rictor （mTORC2）的复合物调节多种细胞类型的细胞生长和增殖。mTORC1和mTORC2存在于少突胶质细胞祖细胞中，先前的数据表明每种复合物在分化过程中具有不同的功能。我的假设是，这两种mTOR复合物在少突胶质细胞分化过程中具有重要而独特的功能，mTOR信号传导对于髓鞘再生和发育性髓鞘形成至关重要。通过在原代少突胶质细胞培养中使用siRNA敲低复杂特异性蛋白，将在体外表征敲低mTORC1和mTORC2的效果。在体内制备携带flox -mTOR和CNP-Cre转基因或诱导型PLP-Cre转基因的双基因小鼠，用于少突胶质细胞特异性敲除mTOR。这些系统将用于研究mTOR特异性缺失对分化和髓鞘形成的影响。这些研究的完成将阐明mTOR在体内少突胶质细胞分化、髓鞘形成和再髓鞘形成中的作用。第一个目的是研究mTORC2在调控分化过程中不可或缺的转录因子中的作用。目的2将评估mTORC2对细胞骨架和过程生长的调控。目的3将利用体内模型来确定mTOR敲低对发育期间和脱髓鞘损伤后的分化和髓鞘形成的影响。少突胶质细胞分化在新生儿缺氧缺血和多发性硬化症中被破坏，说明需要详细了解所涉及的机制过程。这些研究将进一步加深对少突胶质细胞分化的理解，并为影响少突胶质细胞和髓磷脂形成的神经病变的治疗提供靶点。

DESCRIPTION (provided by applicant): Oligodendrocytes envelop axons with a myelin sheath in the central nervous system to facilitate action potential conduction. The establishment of axon myelination during development involves oligodendrocyte proliferation, differentiation, and production of myelin. The intracellular signaling mechanisms governing this process are only beginning to be elucidated. Previous data in our laboratory demonstrated mammalian target of rapamycin (mTOR) as essential for oligodendrocyte differentiation. mTOR, a downstream target of PI3K/Akt, regulates cell growth and proliferation in a number of cell types through complexes with adaptor proteins raptor (mTORC1) or rictor (mTORC2). mTORC1 and mTORC2 are present in oligodendrocyte progenitors and previous data indicate different functions for each complex during differentiation. My hypothesis is that the two mTOR complexes have essential and distinct functions during oligodendrocyte differentiation and that mTOR signaling is essential for remyelination as well as developmental myelination. Through the use of siRNA knockdown of complex specific proteins in primary oligodendrocyte cultures the effects of knockdowns of mTORC1 and mTORC2 will be characterized in vitro. Bigenic mice carrying floxed-mTOR and either a CNP-Cre transgene or an inducible PLP-Cre transgene will be created for oligodendrocyte specific knockdown of mTOR in vivo. These systems will be used to investigate the effects of specific deletion of mTOR on differentiation and myelination. Completion of these studies will elucidate how mTOR functions in oligodendrocyte differentiation, myelination and remyelination in vivo. The first aim will investigate the role of mTORC2 in the regulation of transcription factors integral to the differentiation process. Aim 2 will assess mTORC2 regulation of the cytoskeleton and process outgrowth. Aim 3 will utilize in vivo models to determine the effects of mTOR knockdown on differentiation and myelination during development and following a demyelinating injury. Oligodendrocyte differentiation is disrupted in neonatal hypoxia-ischemia and in Multiple Sclerosis, illustrating a need for a detailed understanding of the mechanistic processes involved. These studies will further the understanding of oligodendrocyte differentiation and provide targets to pursue for therapeutic treatments of neuropathologies that impact oligodendrocytes and myelin formation.