MOLECULAR BASES OF NEURONAL CONNECTIVITY

描述(改编自申请人摘要)：在正常情况下， 视网膜神经节细胞在损伤后不能再生轴突。 受损的轴突仅显示在损伤部位有流产的萌芽，并且在 几天后，细胞开始死亡。然而，晶状体的轻微损伤会产生 刺激众多神经节细胞在轴突切断后存活并 通过视神经再生轴突，这一领域通常被视为 对生长有抑制作用的。晶状体损伤激活常驻小胶质细胞并 浸润性巨噬细胞。已知这些细胞在多种情况下对 损伤的神经元，一些有益，另一些具有破坏性。具体目标1将 探讨晶状体损伤对轴突的促进作用 通过小胶质细胞、巨噬细胞或其他类型的细胞介导，并将 确定是否可以更改此响应的特定方面以增强 神经节细胞存活和轴突进一步生长。补充性研究 目标2将检测晶状体是否刺激细胞存活和轴突再生 可以通过增加细胞内水平的治疗来扩大穿刺量 第二信使，环磷酸腺苷，或防止神经胶质瘢痕形成的信使 在损伤部位。在更基本的层面上，目标3和4将调查 控制视网膜神经节细胞轴突生长的分子机制。 对低等脊椎动物的研究表明，AF-1是一种由 视神经胶质细胞，诱导视网膜神经节细胞表达一系列 生长相关基因和延长长轴突。大鼠脑内神经胶质细胞 哺乳动物的外周神经系统高度支持轴突生长， 使低分子量生长因子与AF-1相似或相同。目标3 将研究哺乳动物AF-1在视神经再生中的作用 高等脊椎动物。最后，对低等脊椎动物的研究也表明， 导致轴突生长的细胞内步骤涉及一种 嘌呤敏感机制。为了研究该激酶在体内的作用 控制哺乳动物视网膜神经节细胞的轴突生长，Aim 4将 分离该激酶，克隆其基因，并研究其在临床中的意义 构建显性-负性突变体和视神经再生 研究它在控制基因表达中的作用。这些研究将提供 对控制初级脑内轴突生长的基本机制的新认识 视觉通路，并增强我们在受伤后恢复视觉功能的能力 或者是青光眼。

DESCRIPTION (adapted from applicant's abstract): Under normal circumstances, retinal ganglion cells are unable to regenerate their axons after injury. Damaged axons show only abortive sprouting at the site of injury, and after a few days, cells begin to die. However, minor injury to the lens produces signals that stimulate numerous ganglion cells to survive axotomy and to regenerate their axons through the optic nerve, a territory generally viewed as being inhibitory to growth. Lens injury activates resident microglia and infilitrative macrophages. These cells are known to exert multiple effects on injured neurons, some beneficial and others destructive. Specific Aim 1 will investigate whether the axon-promoting effects of lens damage in the rat are mediated through microglia, macrophages, or other cell types, and will determine whether specific aspects of this response can be altered to enhance ganglion cell survival and axon growth even further. Complementary studies in Aim 2 will examine if cell survival and axon regeneration stimulated by lens puncture can be augmented by treatments that increase intracellular levels of the second messenger, cyclic AMP, or that prevent the formation of a glial scar at the lesion site. At a more basic level, Aims 3 and 4 will investigate the molecular mechanisms that control axon outgrowth in retinal ganglion cells. Research in lower vertebrates has shown that AF-1, a small factor secreted by optic nerve glia, induces retinal ganglion cells to express a constellation of growth-associated genes and to extend lengthy axons. Glial cells of the mammalian peripheral nervous system are highly supportive to axon growth, and make a low molecular weight growth factor similar or identical to AF-1. Aim 3 will investigate the role of mammalian AF-1 in optic nerve regeneration in higher vertebrates. Finally, studies in lower vertebrates also show that one of the intracellular steps leading to axon outgrowth involves a purine-sensitive mechanism. To investigate the role to this kinase in controlling axon outgrowth in mammalian retinal ganglion cells, Aim 4 will isolate the kinase, clone its gene, and investigate its' significance for optic nerve regeneration by constructing dominant-negative mutants and examining its role in controlling gene expression. These studies will provide new insights into the basic mechanisms that control axon growth in the primary visual pathway, and enhance our ability to restore visual function after injury or in glaucoma.