The Role of TSC Genes During Brain Development

描述（由申请人提供）：本提案的目标是：1）定义TSC基因用于控制神经元生成的机制，然后从神经祖细胞生成神经胶质细胞; 2）确定这些过程中的缺陷如何导致多发性硬化症（TSC）的皮质畸形。TSC是由TSC 1或TSC 2基因突变引起的，是癫痫和自闭症最常见的遗传原因。这些特征很可能是由于几乎所有患者都存在的大脑皮质畸形（结节）。以前的工作已经证明了严重的层状破坏与异常的神经胶质细胞，畸形神经元和“巨”细胞表达神经元以及神经胶质标记物的块茎。这些发现表明，TSC基因在特定神经元群体的产生以及神经祖细胞从神经元到胶质细胞生产的转换过程中起着关键作用。通常控制这一过程的机制还不清楚，但似乎与细胞周期退出和G1期的长度有关。增殖、总细胞周期长度和G1期持续时间由细胞周期蛋白、细胞周期蛋白依赖性激酶（cdk）和cdk抑制剂如p27 kip 1（p27）介导。值得注意的是，虽然Tsc 1或Tsc 2缺陷的成纤维细胞具有降低的p27水平和活性，但Tsc 1或Tsc 2缺陷的神经祖细胞中的类似改变尚未报道。我们的具体目标是：1）确定Tsd基因对神经祖细胞产生神经元和神经胶质的时间的作用，2）确定7sc 1缺陷型神经祖细胞中的G1持续时间和增殖，和3）确定7sc 7缺陷型神经祖细胞中的p27表达、亚细胞定位和功能。我们将通过在体内和体外研究7sc 1缺陷的神经前体细胞来实现这些目标。这些神经祖细胞分化的能力将使用谱系特异性标志物来确定。此外，我们将使用S期示踪剂来测量细胞周期长度，G1期持续时间，以及Tsc 1缺陷神经祖细胞小鼠中活跃增殖的细胞比例。最后，将确定p27表达、亚细胞定位和功能。候选人将利用这个K 08奖，通过与他的导师，范德比尔特大学神经科学研究社区的互动，并积极参与国家和国际发育神经生物学领导人，获得发育神经生物学方面的专业知识。总的来说，这个奖项应该使他成为一个独立的医生，科学家谁将成功地竞争未来的校外NIH资金。相关性：多发性硬化症（TSC）是一种遗传性疾病，其表现包括癫痫发作障碍、脑肿瘤、自闭症和发育迟缓。该建议旨在了解异常神经前体细胞对TSC的作用。这些发现可能对TSC患者以及患有癫痫发作障碍和自闭症的非TSC患者具有广泛的治疗意义。

DESCRIPTION (PROVIDED BY APPLICANT): The goals of this proposal are to 1) define mechanisms used by the TSC genes to control the generation of neurons and then glia from neural progenitor cells and 2) determine how defects in these processes result in cortical malformations in Tuberous Sclerosis Complex (TSC). TSC is caused by mutation of either the TSC1 or TSC2 genes and is the most common genetic cause of epilepsy and autism. These features are very likely due to cortical brain malformations (tubers) that are found in almost all patients. Previous work has demonstrated severe laminar disruptions within tubers with abnormal glia, dysmorphic neurons, and "giant" cells expressing neuronal as well as glia markers. These findings suggest that the TSC genes play a critical role during the generation of specific neuronal populations as well as the switch from neuronal to glia production by neural progenitor cells. Mechanisms that normally control this process are not well understood but appear linked to cell cycle exit and the length of G1. Proliferation, total cell cycle length, and G1 duration are mediated by cyclins, cyclin-dependent kinases (cdk), and cdk inhibitors such as p27kip1 (p27). Notably, while Tsc1 or Tsc2-deficient fibroblasts have decreased levels and activity of p27, similar alterations in Tsc1 or Tsc2-deficient neural progenitor cells have not been reported. Our Specific Aims are: 1) Determine the role of the Tsd gene on the timing of neuronal and glia production from neural progenitor cells, 2) determine G1 duration and proliferation in 7sc1-deficient neural progenitor cells, and 3) determine p27 expression, subcellular localization, and function in 7sc7-deficient neural progenitor cells. We will achieve these aims by studying 7sc1-deficient neural progenitor cells both in vivo and in vitro. The ability of these neural progenitor cells to differentiate will be determined using lineage specific markers. In addition, we will use S phase tracers to measure cell cycle length, G1 duration, and the proportion of cells that are actively proliferating in mice with Tsc1-deficient neural progenitor cells. Finally, p27 expression, subcellular localization, and function will be determined. The candidate will utilize this K08 Award to gain expertise in developmental neurobiology though interactions with his mentor, the Neuroscience research community at Vanderbilt University, and active involvement with national and international leaders in Developmental Neurobiology. Overall, this award should position him to become an independent physician-scientist who will successfully compete for future extramural NIH funding. Relevance: Tuberous Sclerosis Complex (TSC) is a genetic disease whose manifestations include seizure disorders, brain tumors, autism and developmental delay. This proposal seeks to understand the role of abnormal neural progenitor cells to TSC. These findings will likely have broad therapeutic implications for individuals with TSC as well as non-TSC patients with seizure disorders and autism.