Translational Regulation in Initial Stages of the Neuronal Injury Response. Mus musculus

Transcriptional events leading to outgrowth of neuronal axons have been intensively studied, but the role of translational regulation in this process is not well understood. Here we use translatome analyses by ribosome pull-down and protein synthesis characterization by metabolic isotopic labeling to study nerve injury and axon outgrowth proteomes in rodent dorsal root ganglia (DRG) and sensory neurons. We identify over 1600 gene products that are primarily translationally regulated in DRG neurons after nerve injury, many of which contain a 5’UTR CERT motif, implicating the translation initiation factor Eif4e in the injury response. We further identified approximately 200 proteins that undergo robust de novo synthesis in the initial stages of axon growth. ApoE is one of the highly synthesized proteins in neurons, and inhibition of its signaling affects axon outgrowth. These findings suggest prominent roles for translational regulation in initial stages of the neuronal injury response and axon extension. Overall design: Use Ribotag mice to identify cell type specific translatomes within dorsal root ganglia and observe their change following an injury to the sciatic nerve调控神经元轴突生长的转录事件已得到广泛研究，但翻译调控在该过程中的作用尚未被充分阐释。 本研究通过核糖体下拉（ribosome pull-down）实验开展翻译组（translatome）分析，并结合代谢同位素标记（metabolic isotopic labeling）技术完成蛋白质合成表征，以探究啮齿类动物背根神经节（dorsal root ganglia, DRG）及感觉神经元中，与神经损伤和轴突生长相关的蛋白质组特征。 研究团队鉴定出1600余种在神经损伤后，背根神经节神经元中主要受翻译调控的基因产物，其中多数含有5'非翻译区（5’UTR）CERT基序，提示翻译起始因子（translation initiation factor）Eif4e参与了神经元的损伤应答过程。 本研究进一步鉴定出约200种在轴突生长初始阶段发生显著从头合成（de novo synthesis）的蛋白质。 载脂蛋白E（ApoE）是神经元中合成水平较高的蛋白质之一，其信号通路的抑制会对轴突生长产生影响。 上述研究结果表明，翻译调控在神经元损伤应答与轴突延伸的初始阶段发挥着关键作用。 实验整体设计：利用RiboTag小鼠（Ribotag mice）鉴定背根神经节内的细胞类型特异性翻译组，并观察坐骨神经（sciatic nerve）损伤后，该组织翻译组的动态变化。