EPICAN, A PROTEOGLYCAN FORM OF CD44 ON KERATINOCYTES

蛋白多糖在表皮角质形成细胞表面丰富， 其功能尚不清楚。 细胞-细胞粘附相互作用 在正常和病理组织组织中的中心作用。 Epican，a 新发现的硫酸乙酰肝素形式的CD 44，已被发现在 初步数据表明，epican可以发挥作用， 作为角质形成细胞上的粘附分子。 这项建议的目的是： I. 剖析表皮细胞介导的角质形成细胞的分子基础- 角质形成细胞粘附 我们建议a）确定粘附中的作用 透明质酸、共价连接的硫酸乙酰肝素和N- 连接的糖; B）鉴定表聚糖核心蛋白上的结合位点 或者通过产生表聚糖的缺失突变体， 转染角质形成细胞或通过使用合成肽组 和/或结构域特异性单克隆抗体以阻断细胞-细胞粘附; 二. 确定epican表达的功能后果， 角质形成细胞 我们建议测试表聚糖在a）细胞-细胞和 细胞-基质粘附B）生长调节和c）细胞和组织 通过在自发的角质形成细胞系中过度表达epican来观察形态学， 表达低水平的epican。 三. 确定epican表达的功能性后果， 通过检查a）在何种条件下epican是黑色素细胞 在黑素细胞上表达; B）表聚糖表达对生长的影响， 黑素细胞或黑素瘤细胞的形态和粘附特征。

Proteoglycans are abundant on the surface of epidermal keratinocytes, but their function is unknown. Cell-cell adhesive interactions play a central role in normal and pathologic tissue organization. Epican, a newly discovered heparan sulfate form of CD44, has been found on keratinocytes and preliminary data indicate that epican could function as an adhesion molecule on keratinocytes. The aims of this proposal are to: I. Dissect the molecular basis for epican-mediated keratinocyte- keratinocyte adhesion. We propose to a) determine the role in adhesion of hyaluronic acid, the covalently-linked heparan sulfate and the N- linked sugars; b) identify the binding site on the epican core protein either by creating deletion mutants of epican that prevent binding of transfectants to keratinocytes or by using panels of synthetic peptides and/or domain-specific monoclonal antibodies to block cell-cell adhesion; II. Determine the functional consequences of epican expression on keratinocytes. We propose to test the role of epican in a) cell-cell and cell-matrix adhesion b) growth regulation and c) cell and tissue morphology by overpressing epican in spontaneous keratinocyte lines that express low levels of epican. III. Determine that functional consequences of epican expression on melanocytes by examining a) the conditions under which epican is expressed on melanocytes; b) the effects of epican expression on growth, morphology and adhesive characteristics of melanocytes or melanoma cells.