Control of Neuronal Differentiation in the Cerebellum

描述（由申请人提供）：小脑是最早发育的大脑区域之一，但它在出生后几个月才成熟。这一漫长的发育期使其容易受到产前和产后的干扰。这也使得它非常适合研究;它的解剖学发展被很好地描述。然而，从小脑干细胞到成熟神经元的转变的遗传控制在很大程度上仍然是未知的。将检查对照颗粒细胞生成，即数量最多的CNS神经元。小脑起源于两个生发区：菱形唇，产生颗粒细胞，脑室区，产生所有其他细胞。细胞在菱形唇增殖，迁移到外胚层（EGL），增殖为颗粒细胞前体（GCPs），并迁移通过浦肯野神经元，因为它们成为成熟的颗粒细胞。我们假设，关键的调控信号的基础上的转变，从增殖分化，可以确定通过比较发生在菱形唇和EGL的遗传变化。我们知道Sonic hedgehog（Shh）是GCPs的有效促分裂原，GCPs表达Shh受体Patched 1（Ptcl）。ptcl功能降低可能引起GCP的异常增殖，引起髓母细胞瘤。使用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在菱形唇早期的作用尚未被探索。从自我更新前体到分化颗粒细胞的转变将通过以下方式进行分析：1）表征从小脑原基和菱形唇分离的细胞的表型潜力，2）阐明控制这些阶段之间的转变点的遗传程序，以及3）测试被鉴定为潜在调节因子的基因以确定祖细胞如何停止增殖并开始分化。最终，为了在从小脑到皮层的任何区域以治疗性的、定向的方式控制神经元前体细胞，我们必须了解从增殖到分化的转变背后的机制。我的目标是发展分子生物学技能，以补充我以前的生理学和解剖学培训。作为一名神经发育学家，我将利用这些工具来解决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.