DROSOPHILA SENSORY NEURON DEVELOPMENT

我们正在研究果蝇神经系统发育过程中细胞粘附分子的功能。在上一个授权期内，我们克隆并鉴定了shotgun （shg）和faint sausage （as）。shg编码果蝇E-cadherin同源物DE- cadherin；fas编码了一个新的igg样蛋白超家族成员，我们将测试其粘附功能作为本提案的一部分。黏附分子，特别是经典的钙粘蛋白，如e -钙粘蛋白，在所有动物中都集中参与控制细胞分选、运动和分化。e -钙粘蛋白是一种肿瘤抑制基因。到目前为止，我们对钙粘蛋白在神经发育中的作用知之甚少；大多数的见解是从脊椎动物细胞培养系统的研究中获得的。我们对shg/ de -钙粘蛋白基因突变的鉴定使我们有机会分析该分子的功能，该分子在果蝇的整个制备过程中在神经外胚层和神经元亚群中表达。我们建议生成一组shg/DE-cadherin的构建体，并利用它们在特定的发育阶段和特定的组织中过度表达或去除该基因的功能。这些操作将使我们能够解决shg/ de -钙粘蛋白介导的粘附如何参与神经元祖细胞的确定和迁移、轴突寻路和突触发生。我们将进一步使用我们的构建，在胚胎和果蝇52细胞中，分析果蝇系统中cadherin/catenin复合物（CCC）磷酸化在细胞粘附中的作用。我们的初步数据表明，膜结合酪氨酸激酶DER （EGF受体的果蝇同源物）使CCC磷酸化，因为DER功能的丧失导致的表型与e -钙粘蛋白过度表达引起的表型非常相似。我们将研究DER是否直接与CCC结合（正如在脊椎动物细胞系中所显示的那样），以及它的激活是否会导致shg/ de -钙粘蛋白和/或连环蛋白的磷酸化。我们相信，我们对果蝇中shg/DE-cadherin的分析将进一步加深我们对经典钙粘蛋白功能的理解。CCC可能是果蝇EGFR活性的直接靶点，这将扩大我们对生长因子在胚胎发育中的功能的理解。

We are studying the function of cell adhesion molecules during the development of the nervous system in Drosophila. During the previous granting period we have cloned and characterized shotgun (shg) and faint sausage ((as). shg encodes the Drosophila E-cadherin homolog, DE- cadherin; fas encodes a novel member of the superfamily of Ig-like proteins for which we will test an adhesive function as part of this proposal. Adhesion molecules, in particular classic cadherins such as E-cadherin, are centrally involved in the control of cell sorting, motility and differentiation in all animals. E-cadherin acts as a tumor suppressor gene. So far little is known about the function of cadherins during neural development; most insight has been gained from the study of vertebrate cell culture systems. Our identification of mutations in the shg/DE-cadherin gene gives us the opportunity to analyze the function of this molecule, which is expressed in the neuroectoderm and subpopulations of neurons, in whole preparations of Drosophila. It is proposed to generate a set of constructs of shg/DE-cadherin and use them to either overexpress or remove the function of this gene at defined developmental stages and in defined tissues. These manipulations will allow us to address how shg/DE-cadherin mediated adhesion is involved in the determination and migration of neuronal progenitors, axonal pathfinding, and synaptogenesis. We will further use our constructs, in both embryos and Drosophila 52 cells, to analyze the role of phosphorylation of the cadherin/catenin complex (CCC) in cell adhesion in the Drosophila system. Our preliminary data suggest that the membrane bound tyrosine kinase DER (Drosophila homolog of the EGF receptor) phosphorylates the CCC, since loss" of DER function causes a phenotype that closely resembles the phenotype resulting from E-cadherin overexpression. We will investigate whether DER directly binds to the CCC (as has been shown in vertebrate cell lines) and whether its activation leads to phosphorylation of shg/DE-cadherin and/or catenins. We believe that our analysis of shg/DE-cadherin in Drosophila will further our understanding of the function of classic cadherins in general. The possibility that the CCC is an immediate target of EGFR activity in Drosophila would widen our understanding of the function of growth factors in embryonic development.