Control of cell fate by progenitor mitosis length and microcephaly-linked genes during cortical development

摘要 -- 小头畸形是一种普遍的发育性认知障碍，目前还没有可用的治疗方法。至少12个基因 人类原发性隐性小头畸形症的基础，需要新的努力来理解 这些基因在大脑皮层发育中的功能。在小鼠的皮质发育过程中， 放射状胶质干细胞自我更新并在胚胎之间产生神经元和中间祖细胞 E11.5天和E18.5天建立皮质。小头畸形连锁基因在细胞周期控制中具有功能，并且 与中心体/微管纺锤体纤维有关。我们的实验室最近发现延长了 放射状胶质中的有丝分裂可以改变细胞命运，导致细胞凋亡，并增强小鼠的小头畸形，提示 小头畸形患者皮质发育改变的可能机制。这方面的研究目标是 建议进一步表征干细胞分化是如何受到长时间有丝分裂的影响，并 了解小鼠的小头畸形基因模型是否会改变皮质干细胞有丝分裂的持续时间和细胞命运。 通过对特定靶点放射状胶质细胞有丝分裂的药理延迟1及功能分析 小头畸形症基因Lis1和CDK5Rap2在特异靶2中，我将检验径向Glia命运的假设 选择受到发育过程中有丝分裂持续时间的影响，小头畸形症相关基因可以控制 调节放射状胶质细胞有丝分裂决定细胞命运。初步数据表明，长时间的有丝分裂可以改变 放射状胶质分裂产生的神经元类型，改变了兴奋性神经元类型的正常发展 一代。此外，小头症基因Lis1的过表达改变了放射状胶质细胞有丝分裂的长度 也改变了神经源性分裂与增生性分裂的比例。目前还不太清楚它是如何 与小头畸形相关的基因是人类疾病的基础，但这些初步结果表明细胞发生了变化。 小头畸形症患者皮质发育异常的原因是有丝分裂时间延长所致。完工后 在建议的目标中，我们将对小头畸形症基因的功能有关键的见解，这将使 未来对有效治疗的研究。此外，我们还将进一步了解有丝分裂持续时间的作用。 在大脑皮层发育期间。

Abstract   Microcephaly is a prevalent developmental cognitive disorder, with no available treatment. At least 12 genes underlie cases of primary recessive microcephaly in humans, and new efforts are needed to understand the function of these genes in the context of cortical development. During cortical development in the mouse, Radial Glia stem cells self-renew and produce both neurons and intermediate progenitors between Embryonic Days E11.5 and E18.5 to build the cortex. Microcephaly-linked genes have functions in cell cycle control, and are associated with centrosomes/microtubule spindle fibers. Our lab has recently discovered that prolonged mitosis in Radial Glia can alter cell fate, cause apoptosis, and potentiate microcephaly in mice, suggesting a plausible mechanism for altered cortical development in microcephaly. The goal of the research in this proposal is to further characterize how stem cell differentiation is affected by prolonged mitosis and to understand if microcephaly gene models in mice alter cortical stem cell mitosis duration and cell fate. Through pharmacologic delay of mitosis in Radial Glia in Specific Aim 1 and functional analysis of microcephaly genes Lis1, and Cdk5rap2 in Specific Aim 2, I will test the hypothesis that Radial Glia fate choice is influenced by mitosis duration across development, and that microcephaly-linked genes can control cell fate decisions by modulating Radial Glia mitosis. Preliminary data indicate prolonged mitosis can change the type of neuron produced by Radial Glia division, altering the normal progression of excitatory neuron type generation. Additionally, overexpression of Lis1, a microcephaly gene, alters length of mitosis in Radial Glia as well as alters the proportion of neurogenic versus proliferative divisions. It is not well understood how microcephaly-linked genes underlie the human disorder, but these preliminary results suggest altered cell fates due to prolonged mitosis can explain abnormal cortical development in microcephaly. Upon completion of the proposed aims, we will have critical insight into the function of microcephaly genes which will enable future studies toward effective treatment. Additionally we will further understand the role of mitosis duration during cortical development.