NERVE GROWTH CONE LOCOMOTION

轴突在发育和损伤后的伸展是一个先决条件 形成有功能的神经元回路。促进增长和 抑制性影响似乎对引导轴突伸展很重要 通过复杂的组织环境。这些影响发挥了他们的 通过调节生长锥的运动性来影响生长锥的结构 延伸轴突的尖端。在……方面取得了相当大的进展 识别和表征抑制性和易化性分子，以及 在某些情况下，传递其影响的第二信使 建议。相比之下，在确定 运动的分子效应器是这些的终极目标 细胞外的影响。该项目的总体目标是确定 并描述这些效应器和调节它们的分子， 并确定它们如何影响生长锥导航和轴突 分机。由于生长锥体产生的张力似乎有一个 在调节轴突延伸的速度和方向方面起着重要作用， 肌球蛋白I和II。尽管在生长过程中也存在其他机械酶 圆锥体的丰度、定位和机械力化学性质 肌球蛋白I和II使它们成为张力效应器的主要候选者 制作。第一个重点将是精确的亚型特异性 这些肌球蛋白的位置，使用定量 免疫荧光和免疫电子显微镜。第二个重点 这项建议的目的是研究肌球蛋白I和II在轴突中的作用 扩展，并检查轴突影响之间的对应关系 由生长锥体产生的伸展和拉伸生产。为此，肌球蛋白 I和II的功能会被抗体和反义干扰 抑制其机械酶活性的寡核苷酸或 分别为综合。抑制肌球蛋白II的功能 神经元系统对细胞的运动和形态有重大影响， 但无法确定这些影响是否相关 随着张力生产的减少。因此，这项工作将评估 这些扰动对以下方面的影响：1.轴突的大体形态 伸展，如轴突伸展速度，2.生长锥体的细微特征 可指示肌球蛋白I和II作用的部位的运动性，例如 由于生长锥外围的突起和回缩，以及3.张力 生长球果的产量。通过不仅描述最初的步骤 在调节生长锥体运动的同时，也最终 (效应器)步骤，期间成功干预的潜在地点 可以识别发育异常或处于再生失败状态。

Axon extension during development and following injury is a prerequisite for the formation of functional neuronal circuitry. Growth promoting and inhibitory influences appear to be important for directing axon extension through the complex tissue environment. These influences exert their effects by regulating the motility of the growth cone, the structure at the tips of extending axons. Considerable progress has been made in identifying and characterizing inhibitory and facilatory molecules, and in some cases, second messengers for transducing their effects have been suggested. In contrast, little progress has been made in identifying the molecular effectors of motility that are the ultimate targets of these extracellular influences. The overall aim of this project is to identify and characterize these effectors and the molecules that regulate them, and determine how they influence growth cone navigation and axon extension. Since tension produced by growth cones appears to have an important role in regulating the rate and direction of axon extension, myosins I and II. Although other mechanoenzymes are present in growth cones, the abundance, localization, and mechanochemical properties of myosin I and II make them leading candidates for effectors of tension production. The first emphasis will be on the precise isoform specific location of these myosins, determined using quantitative immunofluorescence and immunoelectron microscopy. The second emphasis of this proposal is to investigate the role of myosin I and II in axon extension, and to examine the correspondence between effects on axon extension and tension production by growth cones. To this end, myosin I and II function will be disrupted with antibodies and antisense oligonucleotide that inhibit their mechanoenzymatic activity or synthesis, respectively. Inhibiting the function of myosin II in non- neuronal systems had significant effects on cell motility and morphology, but it was not possible to determine whether these effects correlated with a decrease in tension production. Therefore, this work will assess the influence of these perturbations on: 1. gross aspects of axon extension, such as axon extension rate, 2. subtle features of growth cone motility that may indicate the site at which myosins I and II act, such as protrusion and retraction of growth cone periphery, and 3. tension production by growth cones. By characterizing not only the initial steps in the regulation of growth cone locomotion, but also the final (effector) steps, the potential sites for successful intervention during abnormal development or in regenerative failure can be identified.