Regulation of neurogenesis in the cerebellum

描述(申请人提供)发育神经生物学的一个基本方面，我们仍然不完全了解，是位置信息如何与神经遗传程序的局部调节相协调，以在大脑中建立特定的模式。在体内，这个问题在实验中可以在小脑中获得。近亲交配的小鼠品系表现出复杂但不变的小脑分叶模式，这种模式由一个简单的层状结构支撑，该结构由有限数量的已定义神经元亚型组成，有助于表征调节神经发生的潜在机制。用突变小鼠模型检测小脑皮质花纹的缺陷已经证实，小脑花纹与神经母细胞的分化程序密切相关，但调节是如何发生的仍不清楚。我们的初步结果表明，在轴突引导过程中，某些对调节膜/细胞骨架相互作用至关重要的分子也在调节对模式信息的神经源性反应中发挥重要作用。其中之一是神经系统特异的GAP-43蛋白。我们已经知道，GAP-43是分化的神经元对引起中枢神经系统模式形成的信号做出反应所必需的。例如，我们的GAP-43基因敲除小鼠无法在皮质或端脑连合形成地形图，因为在这两种情况下，GAP-43(-/-)神经元都无法对免疫球蛋白超家族(Ig-SF)介导的轴突生长和引导信号做出反应。然而，GAP-43(-/-)小鼠在小脑模式方面也有严重的缺陷，这种缺陷在轴突发生之前就很明显，但在神经发生受到细胞外模式程序的调控期间。这项基金的目的是为了了解当GAP-43缺失时小脑模式破坏的分子机制。我们描述了三个实验：第一，确定小脑发育的最早阶段，需要GAP-43功能。其次，为了研究小脑中已知的两种神经源性调节因子(bFGF和BDNF)是否在GAP-43缺失时发挥作用-我们已经知道bFGF需要GAP-43，BDNF可以刺激生长轴突中的GAP-43磷酸化。最后，我们将表征GAP-43的缺失如何影响LG-SF信号的转导，LG-SF信号在小脑神经元分化过程中调节细胞周期。这项研究将主要在印度进行，作为NIH#RO1 NS33118补助金的延伸。

DESCRIPTION (provided by applicant) A fundamental aspect of developmental neurobiology that we still do not fully understand is how positional information coordinates with local regulation of neurogenetic programs to establish specific patterns in the brain. In vivo, the issue is experimentally accessible in the cerebellum. Inbred mice strains show complex yet invariant patterns of cerebellar foliation that is underpinned by a simple laminar structure comprised of a limited number of defined neuronal subtypes, facilitating characterization of the underlying mechanisms regulating neurogenesis. Examining defects in patterning of cerebellar cortex using mutant mouse models has confirmed that cerebellar patterning is intimately tied to the differentiation program of the neuroblasts, but how regulation occurs is still unclear. Our preliminary results suggest that certain molecules crucial for regulating membrane/cytoskeletal interactions during axon guidance also play important roles in regulating the neurogenic response to patterning information. One of these is the nervous system-specific protein GAP-43. We already know that GAP-43 is required in order for differentiated neurons to respond to signals that give rise to patterning in the CNS. For example, our GAP-43 knockout mouse fails to form either topographic maps in cortex, or telencephalic commissures, because in both cases GAP-43 (-/-) neurons are unable to respond to immunoglobulin superfamily (Ig-SF) mediated axon outgrowth and guidance signals. However the GAP-43 (-/-) mouse also has severe defects in cerebellar patterning that are evident before axonogenesis but during the time that neurogenesis is being regulated by extracellular patterning programs. The objective of this FRICA grant is to understand the molecular mechanisms underlying the disruption of patterning in the cerebellum that occurs when GAP-43 is absent. We describe 3 experiments: First, to determine the earliest stage of cerebellar development that requires GAP-43 function. Second to investigate whether 2 known neurogenic regulators in the cerebellum (bFGF and BDNF) can function when GAP-43 is absent - we already know that bFGF requires GAP-43 and that BDNF can stimulate GAP-43 phosphorylation in growing axons. Finally we will characterize how absence of GAP-43 affects transduction of lg-SF signals that regulate the cell cycle in differentiating cerebellar neurons. This research will be performed primarily in India as an extension on NIH grant# RO1 NS33118.