SLOW AXONAL TRANSPORT IN CNS DEVELOPMENT

当代医学的一个主要问题是再生失败。 受损的中枢神经系统轴突。细胞骨架蛋白起着核心作用 在发育期间和损伤后的轴突生长中。这个 细胞骨架元素的传递过程是矢量化的； 转录、翻译和组装主要发生在细胞内 身体和产品被输出到轴突的重要部位 翻译后修饰会发生。然后是细胞骨架 通过缓慢的轴突运输不断地移动到终末。 损伤后，这一向量过程必须应用细胞骨架。 元素到生长区，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 失败的是，这个向量过程的某些方面 不太理想。我们建议继续研究这一点 通过对CNS系统进行两项纵向研究来提出假说 它经历了一个关键的发展时期 再生失败和通过检查受伤的比较研究 外周神经元。仓鼠皮质脊髓系统为 中枢神经系统模型，因为这些神经元完全在出生后阐述轴突 并保持第一次受伤后再生的能力 出生后2周。在这段关键时期过后，受伤会导致 再生功能衰竭和永久性功能丧失。我们将首先 检测低分子和高分子细胞的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中的应用 用cdna探针进行定量原位杂交。这将是 提供有关转录的初始外观的信息 产品，关于主要细胞骨架基因在多大程度上 转录共调控，并以发生的改变为目标 在这一系统重新成长的关键时期。 发育中的皮质脊髓神经元的免疫化学研究 特异性单抗将是对信使核糖核酸研究的补充 通过检查MAJOR的表达和修饰来进行更改 细胞骨架蛋白。第二，我们将切断皮质脊髓的轴突 不同发育阶段的神经元并确定如何 细胞骨架基因表达变化的原位定量研究 与cDNAs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(如核因子磷酸化) 结果伤后。三是开展比较研究 背根神经节(DRG)细胞对 确定安装的分子变化

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