CD45 ISOFORM REGULATION OF T CELL ACTIVATION

T 细胞激活的 CD45 同工型调节

• 批准号: 2057597
• 负责人: DAVID LEITENBERG
• 金额: $ 9.69万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2057597
• 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

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) 的连接不会产生单一的 一系列事件，而是可能导致各种不同的事件 结果包括增殖、细胞毒性、细胞凋亡、不同的 淋巴因子分泌模式和无反应性。精确的机制 负责调节这些不同结果的责任仍不清楚。一 CD45 是调节 T 细胞活化的重要分子 高分子量跨膜糖蛋白由 细胞质尾部含有两个带有蛋白酪氨酸磷酸酶的结构域 活性，以及​​编码在三个外显子中的可变外部域，它们是 由于转录后替代RNA而差异表达 拼接。这产生了多种不同的亚型，其 表达在 T 细胞发育和 T 细胞发育过程中受到调节 激活，并且与不同的 T 细胞效应功能相关。 CD45 的细胞质酪氨酸磷酸酶结构域似乎至关重要 用于 T 细胞激活，因为缺乏 CD45 的突变 T 细胞是难治性的 T 细胞受体信号转导，并且由于信号转导事件恢复 用 CD45 或异嵌合分子转染后 缺乏外部结构域，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 参与信号传导后第二信使生成的调节 然而，通过 TcR，CD45 的可变异构体的作用 调节 T 细胞活化尚不确定。有两个主要假设 对于这个角色（不互相排斥），将在本节中探讨 提议。第一个假设是 CD45 的不同亚型可能 通过优先与其他细胞表面结合来调节信号传导 同一细胞上的分子（例如 CD4）。第二个假设是 不同的亚型可能参与细胞间粘附的调节 相互作用，并可能影响 T 细胞与不同的相互作用 抗原呈递细胞群。为了检验这些假设， 将制备表达不同 CD45 的一系列 T 细胞转染子 具有特定 T 细胞受体的细胞上的亚型。个人效果 CD45亚型对抗原特异性T细胞激活的影响将被确定。 还将构建表达不同的转染子 CD45 的胞外亚型通过乙二醇基与膜连接 磷脂酰肌醇连接锚。这些细胞将用于确定 细胞外结构域在缺乏细胞质的情况下的作用 磷酸酶结构域，并产生可溶性 CD45 亚型， 用作检测异构体特异性 CD45 配体的探针，并进行评估 调节抗原特异性 T 细胞激活的能力。这些研究 T细胞活化调节的研究具有广泛的应用领域 癌症发病机制、自身免疫和传染病。