Regulation of Neurogenesis in TSC by mTORC1 and mTORC2

描述（申请人提供）：多发性硬化症（TSC）是一种由TSC 1或TSC 2基因突变引起的遗传性疾病。患者经常有严重的中枢神经系统表现，包括癫痫，智力残疾和自闭症。TSC患者大脑中的皮质畸形（“结节”）通常被认为是导致这些严重神经学表现的原因。以前的研究使用人体组织和转基因小鼠和斑马鱼模型，导致我们的重点是神经祖细胞/干细胞。神经前体细胞的缺失可以很容易地解释TSC患者脑内所见的细胞数量增加、非典型分化和神经元异位位置。已知几种信号传导途径在TSC中失调，尽管mTOR激酶的控制似乎最关键。最近的研究结果支持两种不同的蛋白质复合物，mTORC 1和mTORC 2内的mTOR异常。这些改变不同，因为我们发现Tsc 1缺陷小鼠神经祖细胞似乎增加了mTORC 1，但减少了mTORC 2信号。然而，mTORC 1和mTORC 2信号转导在TSC发病过程中的相对贡献仍然知之甚少。该提案的首要目标是确定mTORC 1和mTORC 2信号转导在TSC发病机制中的作用。这一目标直接涉及NINDS战略计划，寻求增加我们对正常大脑和神经系统如何发育的知识，这些过程如何在疾病中被破坏，以及这些信息是否可以导致更好的神经系统疾病治疗。为了实现这一目标，我们将使用两种转基因小鼠模型，其特征在于小鼠Tsc 1基因的失活以及诱导多能干细胞（iPSC），我们已经从由于TSC 1或TSC 2基因的功能缺失突变而患有TSC的患者中产生。小鼠和人类神经祖细胞的直接比较是该提议的一个关键方面，因为在进化过程中可能出现了大脑中mTOR信号传导控制的根本差异。 本项目的具体目的是：1）确定TSC 1/2突变型人和Tsc 1缺陷型小鼠神经祖细胞是否产生过量的神经元; 2）确定由TSC 1缺陷型和TSC 2缺陷型人和Tsc 1缺陷型小鼠神经祖细胞产生的神经元是否能够获得下层或上层身份，以及抑制mTORC 1信号传导是否可以恢复这些身份; 3）。确定mTORC 2信号传导单独降低是否足以导致小鼠和人类神经祖细胞的异常分化。 这些研究将大大增加我们对小鼠Tsc 1和人类TSC基因功能的理解。我们的建议有望在小鼠和人类细胞中确定异常的mTORC 1和mTORC 2信号通路，并为TSC患者开发更有效的治疗方法。

DESCRIPTION (provided by applicant): Tuberous Sclerosis Complex (TSC) is a genetic disease caused by mutation of the TSC1 or TSC2 genes. Patients frequently have severe CNS manifestations including epilepsy, intellectual disabilities and autism. Cortical malformations ("tubers") in the brains of patients with TSC are generally accepted as responsible for these severe neurological manifestations. Previous studies using human tissues and transgenic mouse and zebrafish models have led our focus on neural progenitor/stem cells. Abnormalities of neural progenitor cells may readily explain the increased cell number, atypical differentiation and ectopic position of neurons seen within the brain of patients with TSC. Several signaling pathways are known to be dysregulated in TSC though control of the mTOR kinase appears most critical. Recent findings support abnormalities of mTOR within two distinct protein complexes, mTORC1 and mTORC2. These alterations differ as we have found that Tsc1- deficient mouse neural progenitor cells appear to have increased mTORC1 but decreased mTORC2 signaling. However, the relative contribution of mTORC1 and mTORC2 signaling during the pathogenesis of TSC remains poorly understood. The overarching goal of this proposal is to determine the role of mTORC1 and mTORC2 signaling in the pathogenesis of TSC. This goal directly addresses the NINDS Strategic Plan by seeking to increase our knowledge of how the normal brain and nervous system develop, how these processes are subverted in disease and whether this information can lead to better treatments of neurological disorders. To achieve this goal we will use both transgenic mouse models featuring the inactivation of the mouse Tsc1 gene as well as induced pluripotent stem cells (iPSC) we have generated from patients with TSC due to loss of function mutations of the TSC1 or TSC2 genes. The direct comparison of mouse and human neural progenitor cells is a key aspect of this proposal as fundamental differences in the control of mTOR signaling in the brain likely arose during evolution. The Specific Aims of this project are to 1) Determine if TSC1/2-mutant human and Tsc1-deficient mouse neural progenitor cells generate excessive numbers of neurons; 2) Determine if neurons generated from TSC1-deficient and TSC2-deficient human and Tsc1-deficient mouse neural progenitors are able to acquire lower or upper layer identity and whether inhibition of mTORC1 signaling can restore these identities; 3). Determine if decreased mTORC2 signaling alone is sufficient to cause abnormal differentiation of mouse and human neural progenitor cells. These studies should greatly increase our understanding of the function of the mouse Tsc1 and human TSC genes. Our proposal is expected to define abnormal mTORC1 and mTORC2 signaling pathways in mouse and human cells and lead to the development of much more effective therapies for patients with TSC.