SLOW AXONAL TRANSPORT IN CNS DEVELOPMENT

当代医学的一个主要问题是再生的失败 受损的中枢神经系统轴突 细胞骨架蛋白具有核心作用 在发育过程中和损伤后的轴突生长。 的 细胞骨架元件的传递过程是矢量的; 转录、翻译和组装主要发生在细胞中， 体和产物输出到轴突重要的地方 发生翻译后修饰。 然后细胞骨架 通过缓慢的轴突运输持续移动到末端。 损伤后，这种矢量过程必须应用细胞骨架 元素到生长区域，以便形成新的轴突。 哺乳动物中枢神经系统再生的可能解释之一 失败之处在于这个矢量过程的某些方面 次优 我们建议继续进行研究， 通过对CNS系统进行纵向研究， 它经历了一个关键的发展时期， 再生失败，通过比较研究， 外周神经元 仓鼠的皮质脊髓系统提供 CNS模型，因为这些神经元完全在出生后加工轴突 并保持受伤后的再生能力， 产后2周。 在这个关键时期之后， 再生障碍和永久性功能丧失。 我们将首先 检测低分子和高分子的mRNA水平的变化， 重量神经纤维蛋白，两种不同的β微管蛋白和 肌动蛋白在皮质脊髓神经元正常发育过程中的作用 cDNA探针定量原位杂交。 这将 提供关于转录的最初出现的信息， 产品，线索的程度，主要细胞骨架基因是 转录共调节，以及发生的靶向变化， 在这个系统重新生长的关键时期。 发育中的皮质脊髓神经元的免疫化学研究 特异性单克隆抗体将补充mRNA的研究 通过检查主要的表达和修改来改变 细胞骨架蛋白 第二，我们将切断皮质脊髓 不同发育阶段的神经元， 细胞骨架基因表达的变化 用cDNA探针杂交。 免疫化学研究将 提供有关蛋白质产品及其变化的信息， 翻译后修饰（如NF磷酸化）， 受伤后的结果。 第三，我们将进行比较研究 背根神经节（DRG）细胞对 确定分子变化

A major problem in contemporary medicine is the failure of regrowth of injured CNS axons. Cytoskeletal proteins have a central role in axonal growth both during developmental and after injury. The process of delivery of cytoskeletal elements is vectorial; transcription, translation and assembly occur largely in the cell body and the products are exported to the axon where important posttranslational modifications occur. The cytoskeleton then continually moves by slow axonal transport to the terminal. Following injury, this vectorial process must apply cytoskeletal elements to the growing regions in order for a new axon to form. One of the possible explanations for mammalian CNS regenerative failure is that some aspect of this vectorial process is suboptimal. We propose to continue studies which examine this hypothesis by conducting both longitudinal studies of a CNS system which undergoes a critical period of development in which regeneration fails and by comparative studies that examine injured peripheral neurons. The hamster corticospinal system provides the CNS model since these neurons elaborate axons entirely postnatally and maintain the ability to regenerate after injury for the first 2 postnatal weeks. After that critical period, injury results in regenerative failure and permanent functional loss. We will first examine changes in the mRNA levels of the low and high molecular weight neurofliament proteins, two different beta tubulins and actin during normal development of corticospinal neuronals using quantitative in situ hybridization with cDNA probes. This will provide information on the initial appearance of transcriptional products, clues on the extent to which major cytoskeletal genes are transcriptionally coregulated, and target changes which occur during the critical period for regrowth of this system. Immunochemical studies of developing corticospinal neurons with specific monoclonal antibodies will complement the studies of mRNA changes by examining both the expression and modification of major cytoskeletal proteins. Second, we will axotomize corticospinal neurons at different developmental stages and determine how cytoskeletal gene expression changes using quantitative in situ hybridization with cDNA probes. Immunochemical studies will provide information about the protein products and changes in their posttranslational modifications (such as NF phosphorylation) that result after injury. Third, we will conduct comparative studies of the injury response of the dorsal root ganglion (DRG) cell to determine the molecular changes mounted