DROSOPHILA SENSORY NEURON DEVELOPMENT

我们正在研究细胞黏附分子在果蝇神经系统发育过程中的作用。在之前的授权期内，我们克隆了猎枪(Shg)和淡淡香肠(AS)，并对其进行了鉴定。SHG编码果蝇E-钙粘蛋白同系物DE-钙粘蛋白；FAS编码Ig样蛋白超家族中的一个新成员，作为这一提议的一部分，我们将测试其黏附功能。黏附分子，特别是经典的钙粘附素，如E-钙粘附素，在所有动物中都集中参与控制细胞的分选、运动和分化。E-钙粘附素是一种肿瘤抑制基因。到目前为止，人们对钙粘附素在神经发育过程中的作用知之甚少；大多数洞察力都来自于对脊椎动物细胞培养系统的研究。我们对shg/DE-cadherin基因突变的鉴定使我们有机会分析该分子在整个果蝇标本中的功能，该分子表达在神经外胚层和神经元亚群中。有人建议产生一组shg/DE-cadherin的构建体，并使用它们在特定的发育阶段和特定的组织中过度表达或移除该基因的功能。这些操作将使我们能够解决ShG/DE-钙粘附素介导的黏附如何参与神经元前体细胞的确定和迁移、轴突路径寻找和突触形成。我们将进一步使用我们在胚胎和果蝇52细胞中的构建物来分析钙粘附素/连环蛋白复合体(CCC)的磷酸化在果蝇系统中细胞黏附中的作用。我们的初步数据表明，膜结合的酪氨酸激酶DER(EGF受体的果蝇同源物)使CCC磷酸化，因为DER功能的丧失会导致一种与E-钙粘蛋白过度表达所导致的表型非常相似的表型。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-钙粘附素的分析将进一步加深我们对经典钙粘附素一般功能的理解。CCC是果蝇EGFR活性的直接靶点的可能性将扩大我们对生长因子在胚胎发育中的作用的理解。

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.