mTOR complexes in oligodendrocyte differentiation

描述（由申请人提供）：在中枢神经系统中，少突胶质细胞用髓鞘包裹轴突，以促进动作电位传导。在发育过程中轴突髓鞘形成的建立涉及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传导机制才刚刚开始阐明。我们实验室的先前数据表明，哺乳动物雷帕霉素靶蛋白（mTOR）对少突胶质细胞分化至关重要。mTOR是PI 3 K/Akt的下游靶点，通过与衔接蛋白raptor（mTORC 1）或rictor（mTORC 2）的复合物调节许多细胞类型中的细胞生长和增殖。mTORC 1和mTORC 2存在于少突胶质细胞祖细胞中，并且先前的数据表明在分化期间每个复合物的不同功能。我的假设是，这两个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，并且mTOR信号传导对于髓鞘再生和发育髓鞘形成至关重要。通过在原代少突胶质细胞培养物中使用siRNA敲低复杂特异性蛋白，将在体外表征mTORC 1和mTORC 2敲低的作用。将产生携带嵌合mTOR和CNP-Cre转基因或诱导型PLP-Cre转基因的双基因小鼠，用于体内mTOR的少突胶质细胞特异性敲低。这些系统将用于研究特异性缺失mTOR对分化和髓鞘形成的影响。这些研究的完成将阐明mTOR如何在体内少突胶质细胞分化、髓鞘形成和髓鞘再生中发挥作用。第一个目标是研究mTORC 2在调节分化过程中不可或缺的转录因子中的作用。目的2将评估mTORC 2对细胞骨架和过程生长的调节。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。这些研究将进一步了解少突胶质细胞的分化，并提供目标，以追求治疗性治疗的神经病理学，影响少突胶质细胞和髓鞘形成。 公共卫生相关性：本申请提出确定mTOR信号传导在少突胶质细胞分化和髓磷脂产生中的作用。轴突的髓鞘包裹对于其传导是必不可少的，并且在新生儿缺氧缺血和多发性硬化中被破坏或损坏。了解mTOR的作用将为治疗性治疗提供靶点，以增强少突胶质细胞分化并促进这些中枢神经系统病理中的髓鞘再生。

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. PUBLIC HEALTH RELEVANCE: This application proposes to determine the role of mTOR signaling in oligodendrocyte differentiation and production of myelin. Myelin wrapping of axons is essential for their conductance and is disrupted or damaged in neonatal hypoxia-ischemia and in multiple sclerosis. Understanding the effects of mTOR will provide targets for therapeutic treatment to enhance oligodendrocyte differentiation and promote remyelination in these central nervous system pathologies.