STRUCTURE & FUNCTION OF THE TSP-GPIV SYSTEM

我们实验室最近的工作取得了成功 血小板膜糖蛋白IV(GPIV、CD36、 GPIIIb)作为凝血酶敏感蛋白(TSP)的膜受体。这 TSP及其与细胞相互作用的应用研究进展 受体作为与血小板相关的细胞黏附过程的范例 聚集、细胞黏附与肿瘤转移。TSP是一个450 kD的 三聚体糖蛋白是血小板α颗粒的主要成分 并在活化的血小板表面表达，在那里它支持 不可逆的血小板聚集。TSP是由多种化合物合成的 细胞类型并被整合到生长细胞的基质中，在那里它 似乎可以调节细胞的生长、分化和黏附。定义 TSP与其细胞受体的相互作用对 理解TSP的功能。在初步研究中，我们有 在TSP内定义了一个负责与其交互的域 细胞受体GPIV。一种多肽的治疗意义 可能干扰TSP在肿瘤血小板聚集中的作用 转移是深层次的。在拟议的实验中，对 参与蜂窝TSP交互的TSP域将是 被追捕。具体地说，该提案中概述的实验将 解决以下问题： 1.TSP细胞结合域的鉴定的领域(S) 参与细胞结合的TSP将在研究测量中定义 TSP与合成TSP多肽的结合。 2.GPIV配体(TSP)结合域的鉴定 将使用交联研究来确定该基因的结构域(S) 与TSP相互作用的受体。 3.探讨TSP和GPIV在肿瘤细胞生物学中的作用 肿瘤细胞在TSP涂层表面的粘附性研究将被 以阐明该黏附系统在肿瘤细胞中的作用 转移。

Recent work in our laboratory has resulted in the successful isolation and identification of platelet glycoprotein IV (GPIV, CD36, GPIIIb) as a membrane receptor for thrombospondin (TSP). This application proposes study of TSP and its interaction with cellular receptors as a paradigm for cell adhesion processes relevant to platelet aggregation, cell adhesion and tumor metastasis. TSP is a 450 kD trimeric glycoprotein that is a major platelet alpha granule constituent and is expressed on the activated platelet surface where it supports irreversible platelet aggregation. TSP is synthesized by a variety of cell types and is incorporated into the matrix of growing cells where it appears to regulate cell growth, differentiation, and adhesion. Defining the interactions of TSP with its cellular receptors is critical to an understanding of the function of TSP. In preliminary studies, we have defined a domain within TSP that is responsible for its interaction with the cellular receptor GPIV. The therapeutic implications of a peptide that might interfere with TSP's role in platelet aggregation of tumor metastasis are profound. In the proposed experiments, an examination of TSP domains that participate in cellular TSP interactions will be pursued. Specifically, the experiments outlined in this proposal will address the following: 1.Identification of the cellular binding domains of TSP. The domain(s) of TSP that participate in cell binding will be defined in studies measuring the binding of TSP and synthetic TSP peptides. 2.Identification of the Iigand (TSP) binding domains of GPIV. Crosslinking studies will be used to identify the domain(s) of the receptor that interact with TSP. 3.Investigation of the role of TSP and GPIV in tumor cell biology. Studies on the adhesion of tumor cells to TSP coated surfaces will be performed to clarify the role of this adhesive system in tumor cell metastasis.