Role of mPAR6 Polarity CNS Neuronal Migration

年轻的神经元从它们产生的地方迁移到 他们建立成人大脑的回路是发育的关键一步。迁移缺陷 导致了一系列人类出生缺陷，从严重的智力迟钝到微妙的学习能力 残疾，以及大量的癫痫。我们的实验室致力于了解 控制迁移的基因，希望能深入了解正常发育中的这一关键步骤。 我们使用小脑颗粒神经元的迁移作为模型系统来检查 神经胶质引导的神经元迁移的分子控制。神经元极性的建立是 启动神经元沿着神经胶质引导沿着迁移的步骤。筛选在颗粒中起作用的基因 神经元迁移显示极性信号复合物mPar 6a的高水平表达 神经元退出周期并建立极性。In C.在秀丽隐杆线虫中，建立了一组6种PAR蛋白 前/后不对称性和控制随后的不对称细胞分裂。PAR蛋白是 在进化过程中保持不变。 在初步研究（Solecki等人，2004）中，我们发现mParGa信号传导复合物是 位于迁移的小脑颗粒神经元的中心体，在那里它协调 当神经元沿沿着胶质纤维迁移时中心体和细胞核的运动。在 在提出的研究中，我们将研究mParGa复合物的其他组分，aPKC α和Par 3， 在迁移的颗粒神经元的极性上。mPartxx在细胞分裂中的作用表明， 靶向功能丧失突变体和shRNA实验将是不可行的。因此我们将 使用Roger Tsien开发的一种新方法，将一种结合 将ReAshS染色到mParGq中，并使用发色团辅助的光灭活， 激光照射到中心体中的PmParGa。对于这些实验，我们将生成TC-mPar 6a BAG转基因小鼠，能够对颗粒细胞和皮层神经元进行研究。在最后一组 在实验中，我们将研究在颗粒细胞中表达的受体/配体系统，其与 mParGa复合物、EphB配体肝配蛋白-B1和肝配蛋白-B2。这些实验将 提供了新的信息，调节神经元迁移在皮层地区的发展 个脑袋

The migration of young neurons from sites where they are generated into the positions where they establish the circuitry of the adult brain is a critical step in development. Defects in migration cause a host of human birth defects, ranging from severe mental retardation to subtle learning disabilities, as well as a large number of the epilepsies. Our lab has focused on understanding the genes that control migration, in the hope that insights into this key step in normal development. We use the migration of the cerebellar granule neuron as a model system to examine the molecular control of glial-guided neuronal migration. The establishment of neuronal polarity is a key step in initiating neuronal migration along the glial guide. Screens for genes that function in granule neuron migration revealed high levels of expression of the polarity signaling complex mPar6a neurons exiting the cycle and establishing polarity. In C. elegans, a set of 6 PAR proteins establish anterior/posterior asymmetries and control subsequent asymmetric cell divisions. PAR proteins are conserved throughout evolution. In Preliminary Studies (Solecki et al, 2004), we discovered that the mParGa signaling complex is localized in the centrosome of migrating cerebellar granule neurons, where it coordinates the movement of the centrosome and the nucleus as the neuron migrates along the glial fiber. In the proposed research, we will study the other components of the mParGa complex, aPKC^ and Par3, in the polarity of migrating granule neurons. The role of mPartxx in cell division suggests that targeted loss of function mutants and shRNA experiments will not be feasible. We will therefore use a novel method developed by Roger Tsien to incorporate a genetic tag (TC) which binds the dye ReAshS, into mParGq and use chromophore-assisted light inactivation with a monochromatic laser to inactivate mParGa in the centrosome. For those experiments, we will generate TC-mPar6a BAG transgenic mice, enabling studies on granule cells and cortical neurons. In a final group of experiments, we will study a receptor/ligand system expressed in granule cells which interacts with the mParGa complex, the EphB ligands ephrin-B1 and ephrin-B2. Together, these experiments will provide novel information on the regulation of neuronal migration in cortical regions of developing brain.