THROMBOSPONDIN 2; STRUCTURE EXPRESSION AND FUNCTION

人血小板反应蛋白（TSP）是一种高分子量的 一种糖蛋白（Mr 450，000），由三个相同的二硫键组成 键合的肽链 TSP是血小板α的一种成分， 颗粒和第二相的基本成分， 血小板聚集 TSP也由多种细胞合成 包括平滑肌细胞、内皮细胞和成纤维细胞。 在这些细胞中，合成的TSP被分泌和掺入 细胞外基质（ECM）。 然而，有一些 最近的工作表明，TSP可能有助于调节主动脉 平滑肌细胞（SMC）生长。 TSP也可以作为一个重点 对于ECM中的蛋白酶生成，其能够结合 纤溶酶原和组织纤溶酶原激活物（t-PA）。 由于TSP是血小板和血管壁的成分， 并参与血小板-血小板和血小板血管的相互作用 对它的研究应有助于更好地了解它的作用， 在生理和病理状态（血栓形成、动脉粥样化）中。 为了获得更多的知识， 调节TSP在血管壁中的合成 主要内容如下：1）研究肝素结合的作用 主动脉平滑肌细胞TSP的HBD结构域 增长 这些研究将使用一种细菌表达系统， 合成HBD。 分离的HBD将用于研究其 主动脉平滑肌细胞增殖的作用。 2)研究 TSP的基因结构，以更好地了解组织和 基因的进化。 问题包括：（a） 外显子编码不同的功能域？ B）TSP基因是否 通过基因复制等机制进化成现在的形式 和外显子重排 3)调查的机制， 血小板衍生生长因子（PDGF）增加TSP的合成， 主动脉平滑肌细胞。 PDGF是否通过增加TSPmRNA的表达而增加TSPmRNA的表达？ 转录速率或稳定TSP的mRNA？ 四、 通过使用以下方法定义TSP基因内的PDGF反应元件： 基因结构，包括假定的调控 与报告基因（细菌氯霉素乙酰基）融合的区域 转移酶（CAT））。 5)研究TSP与 使用纯化的蛋白质和分离的主动脉SMC的纤溶酶原 矩阵 6)利用肿瘤细胞利用TSP的能力 作为一种附着因子， 域上的TSP。

Human platelet thrombospondin (TSP) is a high molecular weight glycoprotein (Mr 450,000) composed of three identical disulphide bonded peptide chains. TSP is a constituent of platelet alpha- granules and an essential component of the secondary phase of platelet aggregation. TSP is also synthesized by a variety of cells including smooth muscle cells, endothelial cells and fibroblasts. In these cells the synthesized TSP is secreted and incorporated into the extracellular matrix (ECM). However there is some recent work which suggests that TSP may serve to regulate aortic smooth muscle cell (SMC) growth. TSP may also serve as a focus for protease generation in the ECM by its ability to bind both plasminogen and tissue plasminogen activator (t-PA). Since TSP is constituent of both the platelet and the vessel wall and involved in platelet-platelet and platelet vessel interactions its study should contribute to the better understanding of its role in both physiologic and pathologic states (thrombosis, atheroma). In order to gain greater knowledge about the structure and regulation of TSP synthesis in the vessel wall the following studies are proposed: 1) Investigation of the role of the heparin binding domain (HBD) of TSP with respect to aortic smooth muscle cell growth. These studies will use a bacterial expression system that synthesizes the HBD. The isolated HBD will be used to study its role in aortic smooth muscle cell proliferation. 2) Study of the gene structure of TSP to better understand the organization and evolution of the gene. Questions addressed will include, a) Do the exons code for seperate functional domains? b) Did the TSP gene evolve to its present form by mechanisms such as gene duplication and exon shuffling? 3) Investigate the mechanism by which platelet derived growth factor (PDGF) increases TSP synthesis in aortic SMC's. Does PDGF increase TSP mRNA by increasing the transcriptional rate or by stabilizing the mRNA for TSP? 4) Define the PDGF responsive elements within the TSP gene by use of gene constructions that consist of the putative regulatory region fused to a reporter gene (bacterial chloramphenicol acetyl transferase (CAT)). 5) Study the interaction of TSP with plasminogen using purified proteins and isolated aortic SMC matrices. 6) Exploit the ability of carcinoma cells which use TSP as an attachment factor in trying to localize the cell binding domain on TSP.