mRNA transport and local translation after axotomy

描述（由申请人提供）：神经元可以通过靶向mrna到亚细胞结构域来局部产生新的蛋白质，从而在空间上调节基因表达。虽然在树突腔室中最具特征，但最近的研究证明轴突腔室也能够局部合成蛋白质。这种局部轴突蛋白合成受改变轴突生长的细胞外刺激调节。从基于蛋白质组学的研究中，我们已经确定了在培养的DRG神经元的再生轴突中合成的大量蛋白质。轴突中局部合成的蛋白质的新知识使我们能够询问mrna的转运和特定mrna的翻译如何在轴突中受到调节。该提议的中心假设是，神经元通过特异性地改变mrna进入生长轴突的转运和新蛋白质的合成，来调节轴突亚结构域的蛋白质组成，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，我将讨论细胞外刺激对轴突mRNA运输的调节，并验证mRNA转运到再生轴突的假设，即通过受体介导的信号转导途径作用的细胞外信号调节了mRNA转运到再生轴突。其次，我将测试轴突内蛋白质合成的特异性以及轴突蛋白质合成受环境刺激差异调节的假设。我将重点分析编码结构蛋白（β -actin， peripherin和vimentin）和损伤反应蛋白（HSP70， grp78/BiP和Importin Beta1）的轴突mrna，这些蛋白在轴突生长中起着核心作用。

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.