Control of Neuronal Differentiation in the Cerebellum

描述(申请人提供)：小脑是最早发育的大脑区域之一，但在出生后几个月就成熟了。这一漫长的发育期使其容易受到出生前和出生后的干扰。这也使它易于研究；它的解剖学发展被很好地描述了。然而，从小脑干细胞向成熟神经元过渡的遗传控制在很大程度上仍然未知。将检查对照颗粒细胞的生成，即数量最多的中枢神经系统神经元。小脑起源于两个生发区：菱形唇区和脑室区，前者产生颗粒细胞，后者产生所有其他细胞。细胞在菱形唇部增殖，迁移到外生发层(EGL)，作为颗粒细胞前体(GCP)增殖，并在浦肯野神经元成为成熟颗粒细胞后迁移过去。我们假设，从增殖到分化的关键调控信号可以通过比较发生在菱形嘴唇和EGL的遗传变化来识别。我们知道Sonic hedgehog(Shh)是一种有效的GCP有丝分裂原，它表达Shh受体Patched1(PTCL)。PTCL功能降低可能导致GCPs异常增殖，导致髓母细胞瘤。利用Shh，我们已经确定了GCP从非增殖到增殖时发生的基因表达变化。Shh和PTCL早些时候在菱形嘴唇上的作用尚未被探索。从自我更新的前体细胞到分化的颗粒细胞的转变将通过以下几个方面进行分析：1)表征从小脑原基和菱形嘴唇分离的细胞的表型潜力，2)阐明控制这两个阶段之间过渡点的遗传程序，3)测试被确定为潜在调节基因的基因，以确定前体细胞如何停止增殖和开始分化。最终，为了在任何区域，从小脑到皮质，以治疗性的、定向的方式控制神经前体细胞，我们必须了解从增殖到分化的潜在机制。我的目标是发展分子生物学技能，以补充我之前的生理学和解剖学训练。作为一名新生儿专家，我将利用这些工具来研究神经发育中的关键问题。

DESCRIPTION (provided by applicant): The cerebellum is one of the earliest brain regions to develop, but it is mature many months after birth. This long developmental period makes it susceptible to pre- and post-natal disruptions. It also makes it highly amenable to study; its anatomical development is well described. However, genetic control of transitions from cerebellar stem cells to mature neurons remains largely unknown. The control granule cell generation, the most numerous CNS neurons, will be examined. The cerebellum arises from two germinal zones: The rhombic lip, giving rise to granule cells, and the ventricular zone, giving rise to all other cells. Cells proliferate at the rhombic lip, migrate to the external germinal layer (EGL), proliferate as granule cell precursors (GCPs) and migrate past the Purkinje neurons as they become mature granule cells. We hypothesize that key regulatory signals underlying the shift from proliferation to differentiation can be identified by comparing the genetic changes occurring at the rhombic lip and the EGL. We know that Sonic hedgehog (Shh) is a potent mitogen for GCPs, which express the Shh receptor, Patched1 (Ptcl). Reduced ptcl function may give rise to abnormal proliferation of GCPs, causing meduloblastoma. Using Shh we have already identified gene expression changes that occur as GCPs go from being non-proliferating to proliferating. A role for Shh and Ptcl earlier, at the rhombic lip, has not yet been explored. The transition from self-renewing precursor to differentiating granule cell will be analyzed by: 1) Characterizing the phenotypic potential of cells isolated from the cerebellar primordium and rhombic lip, 2) elucidating the genetic program controlling the transition points between these stages, and 3) testing genes identified as potential regulators to determine how progenitor cells cease proliferation and start to differentiate. Ultimately, to control neuronal precursor cells in a therapeutic, directed manner in any region, from cerebellum to cortex, we must understand the mechanisms underlying the shift from proliferation to differentiation. My goal is to develop molecular biology skills to complement my previous physiology and anatomy training. As a neonatologist, I will bring these tools to bear on critical issues in neurodevelopment.