ETHANOL AND L1 MEDIATED NEURITE OUTGROWTH

这项工作的最终目标是确定L1，一种神经的作用 黏附分子，在酒精相关的神经发育障碍中。 患有这种疾病最严重形式的患者，胎儿酒精 综合征，具有惊人的熟悉的神经解剖学特征 那些L1有遗传缺陷的人。这些观察结果表明，第一语言发挥作用 在酒精相关性神经发育障碍发病机制中的作用。 我们的初步结果表明，乙醇抑制L1介导的神经突起 出生后大鼠在与社交饮酒相当的浓度下生长 第6天小脑颗粒神经元。L1是一种发育调节细胞 对正常神经迁移至关重要的表面糖蛋白，轴突 通过与自身或他人绑定来引导和形成轴突-神经束 细胞表面的分子。L1与自身的绑定之后是 对轴突生长至关重要的一连串信号事件。这些 级联可以分为两条路径：一条由几个人共同组成的路径 参与激活成纤维细胞生长的细胞黏附分子 因子受体和随后花生四烯酸的释放及其途径 L1所特有的，在细胞质结构域上的L1的磷酸化。我们的 假设乙醇通过以下方式干扰中枢神经系统的发育 改变L1介导的导致轴突形成的信号级联 外延生长。这一假说将在大鼠小脑颗粒细胞中得到验证 在ARND的大鼠模型中。使用轴突生长的分析， 免疫沉淀和Western印迹检测乙醇敏感性 将通过测定乙醇对以下方面的影响来测试公共途径：1) 其他细胞黏附分子刺激的轴突生长，2)水平 磷酸化酪氨酸修饰的蛋白质，以及3)磷酸化 成纤维细胞生长因子受体。对于L1独特的通路，在体外 将使用激酶分析、代谢标记和免疫细胞化学来 确定乙醇对：1)与L1相关的丝氨酸激酶的影响， 2)Li的丝氨酸和酪氨酸的磷酸化；3)L1与L1的结合 4)L1的细胞分布。体外实验将会 与活体实验相关。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介导的轴突生长的影响。

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.