mRNA transport and local translation after axotomy

描述（由申请人提供）：神经元可以通过将mRNA靶向亚细胞结构域以局部产生新蛋白质来空间调节基因表达。虽然最好的特点是在树突室，最近的研究已经证明，轴突室也能够局部蛋白质合成。这种局部的轴突蛋白质合成受细胞外刺激物的调节，这些刺激物改变轴突的生长。从蛋白质组学为基础的研究，我们已经确定了大量的蛋白质，在培养的DRG神经元的再生轴突中合成。这些关于在轴突中局部合成的蛋白质的新知识使我们能够了解mRNA的运输和特定mRNA的翻译是如何在轴突中调节的。该提议的中心假设是，神经元通过特异性改变mRNA向生长轴突的转运以及直接在生长轴突中合成新蛋白质来调节轴突子域的蛋白质组成，以响应环境线索。我将用两个具体目标来检验这个假设。首先，我将解决的调控轴突的mRNA运输细胞外刺激和测试的假设，即运输到再生轴突的mRNA是由细胞外信号通过受体介导的信号转导通路。其次，我将测试轴突内蛋白质合成的特异性和轴突蛋白质合成受环境刺激差异调节的假设。我将集中这些分析轴突mRNA编码的结构蛋白（β-肌动蛋白，外周蛋白和波形蛋白）和损伤反应蛋白（HSP 70，grp 78/BiP和Importin β 1），在轴突生长中发挥核心作用。

DESCRIPTION (provided by applicant): Neurons can spatially regulate gene expression by targeting mRNAs to subcellular domains to locally generate new proteins. Although best characterized in the dendritic compartment, recent studies have proven that the axonal compartment is also capable of local protein synthesis. This localized axonal protein synthesis is regulated by extracellular stimuli that alter axonal growth. From proteomics-based studies, we have identified a substantial number of proteins that are synthesized in the regenerating axons of cultured DRG neurons. This new knowledge of the proteins that are locally synthesized in axons allows us to ask how transport of mRNAs and translation of specific mRNAs is regulated in the axons. The central hypothesis of this proposal is that neurons modulate the protein makeup of axonal subdomains in response to environmental cues by specifically altering transport of mRNAs into, and synthesis of new proteins directly in, growing axons. I will test this hypothesis with two specific aims. First, I will address the regulation of axonal mRNA trafficking by extracellular stimuli and test the hypothesis that transport of mRNAs into the regenerating axon is modulated by extracellular signals acting through receptor-mediated signal transduction pathways. Second, I will test the specificity of intra-axonal protein synthesis and the hypothesis that axonal protein synthesis is differentially regulated by environmental stimuli. I will focus these analyses on axonal mRNAs encoding structural proteins (Beta-actin, peripherin and vimentin) and injury-response proteins (HSP70, grp78/BiP and Importin Beta1) that play central roles in axonal growth.