Centrosome Regulation and Function Associated with Microcephaly

描述(申请人提供)：作为大脑的指挥中心，皮质的正常发育需要大量的神经元产生。这在很大程度上是通过位于发育中皮质脑室带(VZ)的放射状神经胶质前体细胞(RGPC)的不对称分裂实现的。虽然在过去的20年里，我们对RGPC分裂和皮质发育中的神经发生的了解已经取得了很大的进展，但我们对中心体的精确调控和功能的了解仍然有限。中心体是微管组织、细胞分裂和纤毛发生的关键亚细胞器。这项应用的目标是填补这一知识空白，这对于理解小头畸形的病因和病理生理学也是至关重要的。小头畸形是一种神经发育障碍，其特征是由于发育中的皮质神经元产生不足而导致脑体积变小。到目前为止，至少有8个常染色体隐性遗传性原发性小头症(MCPH)基因座和7个基因已被鉴定为常染色体隐性遗传性原发性小头畸形症(MCPH)。值得注意的是，所有已定义的MCPH基因都编码中心体蛋白，这突显了适当的中心体调节和功能在发育中的皮层正常神经元群体产生中的独特重要性。中心假设是，成熟的中心体对于维持VZ中的RGPC至关重要--RGPC是一种前体细胞--并确保它们在发育中的皮质中正确分裂和存活。这一假设是在申请人的实验室发表的初步数据的基础上提出的。在初步数据的指导下，这一假说将通过追求三个具体目标来检验：1)揭示间期和有丝分裂RGPC中的中心体特性和行为；2)确定RGPC中中心体的功能；以及3)探索RGPC中中心体行为的调节机制。这项应用的实验重点是利用最先进的成像和小鼠遗传学方法，全面了解RGPC在细胞周期中进行中心体的行为、功能和调节，以产生神经元并将其与小头症联系起来。截至撰写本文时，很少有此类研究的报道。本项目目标的实现不仅将为RGPC的分裂和皮质神经发生提供重要的认识，而且有助于明确遗传异常所致小头畸形的细胞学基础，从而为早期诊断和治疗提供新的思路。

DESCRIPTION (provided by applicant): Proper development of the cortex, the command center of the brain, entails extensive production of neurons. This is largely achieved through the robust asymmetric division of radial glial progenitor cells (RGPCs) residing in the ventricular zone (VZ) of the developing cortex. While excellent progress has been made over the past twenty years in our understanding of RGPC division and neurogenesis in the developing cortex, our knowledge of the precise regulation and function of the centrosome, a key subcellular organelle for microtubule organization, cell division and ciliogenesis, during cortical neurogenesis remains limited. The goal of this application is to fill this knowledge gap, which wil also be crucial for understanding the etiology and pathophysiology of microcephaly, a neuro-developmental disorder that is characterized by small brain size as a result of deficient neuron production in the developing cortex. To date, at least eight autosomal recessive primary microcephaly (MCPH) loci and seven genes have been identified for autosomal recessive primary microcephaly (MCPH). Remarkably, all the defined MCPH genes encode centrosomal proteins, underscoring the unique importance of proper centrosome regulation and function in the production of normal neuron populations in the developing cortex. The central hypothesis is that the mature centrosome is essential for maintaining RGPCs in the VZ - a progenitor cell niche - and ensuring their proper division and survival in the developing cortex. This hypothesis has been formulated on the basis of the strong published and preliminary data produced in the applicant's laboratory. Guided by preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Reveal centrosome properties and behavior in interphase and mitotic RGPCs; 2) Define the functions of the centrosome in RGPCs; and, 3) Explore the mechanisms that regulate centrosome behavior in RGPCs. The experimental focus of this application is to provide a comprehensive understanding of the behavior, function and regulation of the centrosome in RGPCs as they proceed through the cell cycle to produce neurons and link it to microcephaly, using state-of-the- art imaging and mouse genetic approaches. As of this writing, few such studies have been reported. Accomplishing the aims in this project will not only provide important insights into RGPC division and cortical neurogenesis, but also help to define the cellular basis of microcephaly caused by genetic abnormalities, and thereby provide new ideas for early diagnosis and treatment.