Training in Neurogenetics: Function of NUP107 in Human and Mouse

描述(由申请人提供)：不同物种之间的相对大脑大小差异很大，了解这些差异的基础是神经科学中一个有趣的话题。有可能通过研究直接影响大脑大小调节的紊乱来确定大脑大小的决定因素。常染色体隐性遗传性原发性小头症(MCPH)的特征是大脑发育异常减少。目前的数据表明，MCPH是发育中的皮质神经上皮内神经发生缺陷的结果；神经发生的中断可能是由于模式形成、细胞增殖、细胞存活、细胞分化、细胞迁移或细胞生长方面的缺陷造成的。利用近交系MCPH家系的纯合性图谱，我们的实验室已经确定了核孔蛋白107(NUP107)的突变，该基因以前与人类疾病无关。我建议研究这种罕见的遗传疾病，以深入了解人类的神经发生、智力残疾的原因，以及人类和我们在世的近亲之间在大脑大小和认知能力方面的进化。我已经确定了这种突变对mRNA剪接和蛋白质稳定性的影响，并从患者和对照成纤维细胞中产生了诱导多能干细胞(IPSCs)；IPSCs可用于制造携带NUP107突变的人类神经前体细胞(NPs)。由于脑大小与神经发生的动力学有关，我们希望将NUP107突变对MCPH小鼠和人类模型中NP群体的影响联系起来。为了帮助比较物种间的结果，我产生了条件NUP107基因陷阱等位基因(NUP107GT)的嵌合小鼠。在这一应用中，我建议检验以下假设：1.NUP107突变导致有丝分裂后神经元数量减少，原因是PAX6/SOX1/Nestin NP池耗尽，导致神经发生缺陷。2.在分化(PAX6/SOX1/Nestin)NP时，NUP107是顶端/基底轴定位所必需的。3.NUP107缺失严重影响早期对称的神经干细胞增殖，而不会导致后期不对称分裂的缺陷 公共卫生相关性：原发性小头畸形是一种神经发育障碍，可能是由于神经发生改变，导致大脑生长严重减慢。我已经确定了一个新的致病基因NUP107，并提议研究诱导多能干细胞和基因敲除小鼠来模拟这种人类疾病。

DESCRIPTION (provided by applicant): Relative brain size differs considerably between species and understanding the basis of these differences is a fascinating topic in neuroscience. It is possible to identify determinants of brain size by investigating disorders that directly affect its regulation. Autosomal recessive primary microcephaly (MCPH) is characterized by an abnormally a reduction of brain growth. Current data suggests that MCPH is the result of deficient neurogenesis within the neuroepithelium of the developing cortex; disruptions to neurogenesis can result from defects in pattern formation, cell proliferation, cell survival, cell differentiation, cell migration, or cell growth. Using homozygosity mapping in inbred MCPH families, our laboratory has identified a mutation in Nucleoporin 107 (NUP107), a gene not previously linked to human disease. I propose to study this rare genetic disorder to lead to insight in human neurogenesis, causes of intellectual disability, and evolution between humans and our closest living relatives in regards to brain size and cognitive ability. I have already characterized the effect of this mutation on mRNA splicing and protein stability and have generated induced pluripotent stem cells (iPSCs) from patients and control fibroblasts; iPSCs can be used to make human neural progenitors (NPs) harboring the NUP107 mutation. Because brain size has been linked to the kinetics of neurogenesis, we would like to correlate the NUP107 mutation effects on the NP populations between mouse and human models of MCPH. To aid in the comparison of results between species, I have generated chimeric mice for a conditional NUP107 gene trap allele (NUP107GT). In this application, I propose to test the following hypotheses: 1. NUP107 mutations lead to a decrease in the number post-mitotic neurons due to a depletion of the PAX6+/SOX1+/NESTIN+ NP pool resulting in defective neurogenesis 2. NUP107 is required for apical/basal spindle orientation in differentiating (PAX6+/SOX1+/NESTIN+) NPs 3. NUP107 depletions severely affect early, symmetrical neural stem cell proliferation without a resulting defect in later, asymmetric divisions PUBLIC HEALTH RELEVANCE: Primary microcephaly is a neurodevelopmental disorder presumably due to altered neurogenesis and causing a great reduction in brain growth. I have identified a new causative gene, NUP107, and propose to study induced-pluripotent stem cells and knockout mice to model this human disease.