TRANSGENIC ANALYSIS OF PLATELET RECEPTOR EXPRESSION

该项目的目标是定义和表征分子 巨核细胞生成和血小板生成的均数分析 血小板膜糖蛋白受体的体内表达。我们的研究 靶向膜多亚单位受体GP Ib-IX-V复合体 为血小板提供正常功能所必需的两种特性。 首先，GP Ib-IX-V支持血小板在血栓形成表面的黏附， 以失血性疾病为例的一个过程，这种疾病是由 先天缺乏受体或其配体，冯·威勒布兰德 因素。第二，GP Ib-IX-V在正常血小板中的假定作用 由异常巨型血小板的释放所提示的形态发生 与先天缺乏受体的情况相吻合，伯纳德- 苏利耶综合征。然而，导致血小板的机制 巨核细胞的释放和正常结构的维持 对再循环血小板的了解很少，主要是因为 缺乏检查和操纵这两个过程的体外模型。一个 这一建议的显著特点是利用体内的 用独特的模型检测血小板受体的表达 巨核细胞和血小板的细胞内环境。建议 研究将提供有关IN机制的基本信息 对GP Ib的体内调节支持确定 与转录有关的分子事件和/或因素 巨核细胞特异性基因(目标1和2)。其他实验将会 评估巨核细胞生成过程中Septin基因的表达。 这些都是由于人类分离蛋白的鉴定而成为可能的 巨核细胞表达的基因，它直接与 GP Ibβ亚基的表达(目标3)。我们还将测试 将血小板GP Ib-IX-V表达与正常联系起来的结构假说 通过提出实验来检查体内的血小板结构 α-蛋白的胞质结构域之间相互作用的相关性 小鼠血小板膜糖蛋白Ib亚基与细胞骨架 Bernard-Soulier综合征模型(目标4)。这些目标将是 通过联合使用巨核细胞特异性基因实现的 启动子，不同的GP Ibalpha分子在表面的表达 对小鼠血小板的影响，以及体内和体外实验 巨核细胞基因表达。这些研究将产生基本的 可应用于治疗策略的信息 影响巨核细胞生成和血小板的病理条件 制作。

The objectives of this project are to define and characterize molecular evens of megakaryocytopoiesis and platelet production by analyzing the in vivo expression of platelet glycoprotein (GP) receptors. Our studies target the GP Ib-IX-V complex, a membrane multi subunit receptor providing platelets with two properties essential for normal function. First, GP Ib-IX-V supports platelet adhesion on thrombogenic surfaces, a process exemplified by bleeding disorders which result from a congenital absence of the receptor or its ligand, von Willerbrand factor. Second, is an assumed role for GP Ib-IX-V in normal platelet morphogenesis, suggested by the release of abnormal giant platelets coinciding with the congenital absence of the receptor, the Bernard- Soulier syndrome. However, the mechanisms responsible for platelet release from the megakaryocyte and the maintenance of a normal structure of recirculating platelets are poorly understood primarily due to the lack of in vitro models to examine and manipulate either process. A distinctive feature of this proposal is the utilization of in vivo models to examine platelet receptor expression in the unique intracellular environment of the megakaryocyte and platelet. Proposed studies will provide fundamental information on the mechanisms of in vivo regulation of GP Ib supporting a long-term objective of defining molecular events and/or factors responsible for the transcription of megakaryocytic-specific genes (Aims 1 and 2). Other experiments will evaluate the expression of septin genes during megakaryocytopoiesis. These have been made possible by the identification of human septin genes expressed by megakaryocytes, which are directly linked to the expression of the beta-subunit of GP Ib (Aim 3). We will also test the structural hypothesis linking platelet GP Ib-IX-V expression to normal platelet structure by proposing experiments to examine the in vivo relevance of interactions between the cytoplasmic domain of the alpha- subunit of GP Ib and the platelet membrane cytoskeleton in a murine model of the Bernard-Soulier syndrome (Aim 4). These aims will be achieved through the combined use of megakaryocytic-specific gene promoters, the expression of variant GP Ibalpha molecules on the surface of murine blood platelets, and an examination of in vivo and in vitro megakaryocytic gene expression. These studies will generate basic information that can be applied to therapeutic strategies for pathological conditions affecting megakaryocytopoiesis and platelet production.