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引人入胜的话题。通过研究直接影响大脑调节的疾病，有可能确定大脑大小的决定因素。常染色体隐性原发性小头畸形（MCPH）的特点是大脑生长异常减少。目前的数据表明，MCPH是发育中的皮层神经上皮内神经发生缺陷的结果；神经发生的破坏可由模式形成、细胞增殖、细胞存活、细胞分化、细胞迁移或细胞生长的缺陷引起。利用近交MCPH家族的纯合子作图，我们的实验室发现了核孔蛋白107 （NUP107）的突变，这是一个以前与人类疾病无关的基因。我建议研究这种罕见的遗传疾病，以深入了解人类神经发生，智力残疾的原因，以及人类与我们最亲近的亲戚在大脑大小和认知能力方面的进化。我已经描述了这种突变对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可用于制造含有NUP107突变的人类神经祖细胞（NPs）。由于脑大小与神经发生动力学有关，我们希望将NUP107突变对小鼠和人类MCPH模型之间NP群体的影响联系起来。为了帮助比较物种之间的结果，我为条件NUP107基因诱捕等位基因（NUP107GT）生成了嵌合小鼠。在本申请中，我建议测试以下假设：1。由于PAX6+/SOX1+/NESTIN+ NP池的耗尽，NUP107突变导致有丝分裂后神经元数量减少，从而导致神经发生缺陷2。在分化（PAX6+/SOX1+/NESTIN+） NPs中，NUP107是决定顶端/基础纺锤体方向所必需的。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

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.