ETHANOL AND L1 MEDIATED NEURITE OUTGROWTH

这项工作的最终目标是确定L1的作用，一个神经 粘附分子在酒精相关神经发育障碍中的作用。 患有这种疾病最严重形式的患者，胎儿酒精 综合征，具有神经解剖学特征，这是惊人的熟悉， L1基因缺陷的人。这些观察结果表明，L1发挥 在酒精相关的神经发育障碍的发病机制中的作用。 我们的初步结果表明，乙醇抑制L1介导的神经突， 在与大鼠出生后社交饮酒浓度相当的浓度下生长 第6天小脑颗粒神经元L1是一种发育调节细胞 表面糖蛋白对于适当的神经迁移、轴突 通过与自身或他人结合来引导和轴突束形成 分子在细胞表面。L1与自身结合后， 神经突生长的关键信号事件的级联。这些 级联可分为两个途径：一个途径共同的几个 涉及成纤维细胞生长激活的细胞粘附分子 因子受体和随后的花生四烯酸释放，以及途径 L1特有的磷酸化L1的胞质结构域。我们 一种假说认为，乙醇通过以下方式破坏中枢神经系统发育： 改变L1介导的信号级联， 结果这一假设将在大鼠小脑颗粒细胞中进行检验 在ARND大鼠模型中。使用神经突生长的分析， 免疫沉淀和Western印迹，乙醇敏感性的 将通过确定乙醇对以下方面的影响来测试常见途径：1） 由其他细胞粘附分子刺激的神经突生长，2）水平 磷酸酪氨酸修饰的蛋白质，和3）磷酸化的蛋白质， 成纤维细胞生长因子受体对于L1独特通路，体外 激酶测定、代谢标记和免疫细胞化学将用于 确定乙醇对以下的影响：1）与L1相关的丝氨酸激酶， 2)L1的丝氨酸和酪氨酸磷酸化，3）L1与 锚蛋白，和4）L1的细胞分布。体外实验将 与体内实验相关。这些实验将提供 关于乙醇抑制的潜在机制的重要信息 对L1介导的神经突生长的影响。

The ultimate goal of this work is to identify the role of L1, a neural adhesion molecule, in alcohol related neurodevelopmental disorder. Patients with the most severe form of this disorder, fetal alcohol syndrome, possess neuroanatomic features which are strikingly familiar to those with genetic defects in L1. These observations suggest that L1 plays a role in the pathogenesis of alcohol related neurodevelopmental disorder. Our preliminary results show that ethanol inhibits L1 mediated neurite outgrowth at concentrations comparable to social drinking in rat postnatal day 6 cerebellar granule neurons. L1 is a developmentally regulated cell surface glycoprotein which is critical for proper neural migration, axon guidance and axon-fascicle formation through binding to itself or other molecules at the cell surface. Binding of L1 to itself is followed by cascades of signaling events critical for neurite outgrowth. These cascades can be divided into two pathways: A pathway common to several cell adhesion molecules involving activation of the fibroblast growth factor receptor and subsequent release of arachidonic acid, and pathways unique to L1 with phosphorylation of L1 on the cytoplasmic domain. Our hypothesis is that ethanol disrupts central nervous system development by altering those L1 mediated signaling cascades which lead to neurite outgrowth. This hypothesis will be tested in rat cerebellar granule cells and in a rat model of ARND. Using assays of neurite outgrowth, immunoprecipitation and Western blot, the ethanol sensitivity of the common pathway will be tested by determining the effect of ethanol on: 1) neurite outgrowth stimulated by other cell adhesion molecules, 2) levels of phosphotyrosine modified proteins, and 3) phosphorylation of the fibroblast growth factor receptor. For the L1 unique pathways, in vitro kinase assays, metabolic labeling, and immunocytochemistry will be used to determine the effects of ethanol on: 1) serine kinases associated with L1, 2) the serine and tyrosine phosphorylation of LI, 3) the binding of L1 to ankyrin, and 4) the cellular distribution of L1. In vitro experiments will be correlated to in vivo experiments. These experiments will provide important information on the underlying mechanism of ethanol's inhibitory effect on L1 mediated neurite outgrowth.