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CD45 ISOFORM REGULATION OF T CELL ACTIVATION

T 细胞激活的 CD45 同工型调节

基本信息

批准号：
2457633
负责人：
DAVID LEITENBERG
金额：
$ 9.87万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-08-01 至 1999-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/2457633
关键词：
CD antigens CD4 molecule T cell receptor T lymphocyte antigen presenting cell biological signal transduction cell adhesion immunoprecipitation laboratory mouse leukocyte activation /transformation protein isoforms protein tyrosine phosphatase tissue /cell culture transfection western blottings

项目摘要

Ligation of the T cell antigen receptor (TcR) does not result in a single series of events, but rather can lead to a wide variety of different outcomes including proliferation, cytotoxicity, apoptosis, distinct patterns of lymphokine secretion, and anergy. The precise mechanisms responsible for regulating these different outcomes remains unclear. One molecule important in regulating T cell activation is CD45, a family of high molecular weight transmembrane glycoproteins consisting of a cytoplasmic tail containing two domains with protein tyrosine phosphatase activity, and a variable external domain encoded in three exons which are differentially expressed due to post-transcriptional alternative RNA splicing. This gives rise to a variety of different isoforms whose expression is regulated during T cell development and following T cell activation, and is correlated with different T cell effector functions. The cytoplasmic tyrosine phosphatase domains of CD45 appear to be critical for T cell activation since mutant T cells which lack CD45 are refractory to T cell receptor signaling, and since signaling events are restored following transfection with CD45, or with heterochimeric molecules which lack the external domains but retain the tyrosine phosphatase domains. These data indicate that the common cytoplasmic domain of CD45 is directly involved in the regulation of second messenger generation after signaling through the TcR, however, the role of the variable isoforms of CD45 in regulating T cell activation is uncertain. There are two main hypotheses for this role (not mutually exclusive) which are to be explored in this proposal. The first hypothesis is that the different isoforms of CD45 may regulate signaling by preferentially associating with other cell surface molecules on the same cell (such as CD4). A second hypothesis is that the different isoforms may be involved in regulating adhesion during cell-cell interactions and perhaps influence T cell interactions with different antigen presenting cell populations. In order to test these hypotheses, a series of T cell transfectants will be made which express different CD45 isoforms on cells with a defined T cell receptor. The effect of individual CD45 isoforms on antigen-specific T cell activation will be determined. Transfectants will also be constructed which express different extracellular isoforms of CD45 linked to the membrane by a glycolsyl phosphatidyl inositol linked anchor. These cells will be used to determine the role of the extracellular domains in the absence of the cytoplasmic phosphatase domains, and to produce soluble CD45 isoforms which will be used as a probe to detect isoform specific CD45 ligands, and evaluated for the ability to modulate antigen-specific T cell activation. These studies on the regulation of T cell activation have broad applicability to fields of cancer pathogenesis, autoimmunity, and infectious disease.

T细胞抗原受体(TCR)的连接不会导致单个一系列事件，而不是可以导致各种各样不同的结果包括增殖，细胞毒性，凋亡，不同的淋巴因子的分泌模式，以及无能。精确的机械装置负责监管这些不同结果的人目前仍不清楚。一调节T细胞活化的重要分子是CD45，它是一类高相对分子质量的跨膜糖蛋白含有蛋白酪氨酸磷酸酶两个结构域的细胞质尾巴活动，以及编码在三个外显子中的可变外部结构域，这三个外显子是转录后选择性RNA引起的差异表达拼接。这导致了各种不同的异构体，它们的在T细胞发育过程中和随后的T细胞中表达受到调节激活，并与不同的T细胞效应器功能相关。 CD45的胞质酪氨酸磷酸酶结构域似乎是关键的对于T细胞激活，因为缺乏CD45的突变T细胞是难治的 T细胞受体信号，由于信号事件被恢复在用CD45或与异构体分子(其缺少外部结构域，但保留酪氨酸磷酸酶结构域。这些数据表明，CD45的共同胞质结构域直接参与信号转导后第二信使生成的调节然而，通过TCR，CD45的不同亚型在调节T细胞激活尚不确定。有两个主要的假设对于这一角色(不是相互排斥的)，将在本求婚。第一种假设是CD45的不同亚型可能优先与其他细胞表面结合调节信号传导同一细胞上的分子(如CD4)。第二个假设是不同的异构体可能参与调节细胞-细胞间的黏附相互作用，并可能影响T细胞与不同的抗原提呈细胞群。为了检验这些假说，一个将制备一系列表达不同CD45的T细胞转染体具有明确T细胞受体的细胞上的亚型。个人的影响将确定抗原特异性T细胞激活的CD45亚型。转化子也将被构建成表达不同的 CD45胞外异构体通过乙醇基连接到膜上磷脂酰肌醇连接锚。这些单元格将用于确定胞外区在胞浆缺失中的作用磷酸酶结构域，并产生可溶性CD45亚型，这将是用作探针来检测异构体特异性CD45配体，并对调节抗原特异性T细胞激活的能力。这些研究关于T细胞活化调控的研究具有广泛的领域适用性癌症发病机制、自身免疫和感染性疾病。