REGULATION OF THYMOCYTE APOPTOSIS BY THROMBOXANE A2

血栓烷A2对胸腺细胞凋亡的调节

• 批准号: 2886027
• 负责人: ROSLYN B MANNON
• 金额: $ 8.68万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2886027
• 关键词: T lymphocyte; apoptosis; autoimmunity; biological signal transduction; cell differentiation; genetically modified animals; immune tolerance /unresponsiveness; laboratory mouse; organ culture; receptor; receptor expression; thromboxanes; thymus

DESCRIPTION: Training Plan: The clonal deletion of autoreactive thymocytes (negative selection) results from the induction of programmed cell death or apoptosis. This process is important for achieving tolerance within an individual. While loss of self-tolerance may result in autoimmune disease, the induction of tolerance to alloantigens may result in permanent organ graft acceptance. Recent studies suggest that thromboxane A2 (TxA2) produced in the thymic microenvironment may regulate thymic maturation. Thromboxane synthase, the final catalytic enzyme involved in TxA2 synthesis, is expressed within the thymus. Moreover, the thymus expresses high levels of the thromboxane receptor (TxR), far above that of other tissues tested. Finally, TxR expression has been localized to immature thymocytes and exposure of these cells to TxA2 induces apoptosis. Therefore, the hypothesis is that TxA2 binds to its receptor and, through specific signaling pathways, regulates cellular processes important to T cell maturation and selection. The goals of this project are to identify the biochemical characteristics and ontogeny of the TxR in thymocytes and identify the function of TxA2 in thymocyte development. To investigate this hypothesis, three specific aims are proposed: (1) To characterize the signal transduction pathways coupled to the TxR in thymocytes. In these studies, the signal transduction pathways coupled to the TxR in freshly isolated thymocytes will be identified by microphysiometry and active second messenger coupling confirmed by standard biochemical assays. (2) To identify which signals activated by TxR cause apoptosis in thymocytes. These studies will directly determine which of the second messengers (identified in specific aim I) mediate apoptosis of thymocytes in vitro. (3) To define the effects of TxA2 on thymocyte maturation in vitro. Using fetal thymic organ culture as a model of thymic development, the applicant will directly test the role of TxA2 in influencing the development of T cells. T cell receptor transgenic mice will be used to specifically examine the role of TxA2 in controlling negative selection of autoreactive T cell precursors. This project is expected to provide novel information regarding the expression and function of the TxR in thymocytes and the effective role of TxA2 in regulating T cell maturation. It is hoped that understanding of the role of lipid mediators in the thymic development may suggest new strategies in preventing autoimmune disease and in the induction of transplantation tolerance to organ allografts.

描述： 训练计划：自身反应性胸腺细胞的克隆删除（阴性 选择）是程序性细胞死亡诱导的结果或 细胞凋亡。这个过程对于在一定范围内实现耐受性非常重要 个人。 虽然自我耐受性的丧失可能会导致自身免疫性疾病 疾病时，诱导对同种抗原的耐受可能会导致 永久性器官移植接受。最近的研究表明，血栓素 胸腺微环境中产生的 A2 (TxA2) 可能调节胸腺 成熟。 血栓素合酶，涉及的最终催化酶 TxA2 合成中，在胸腺内表达。 此外，胸腺 表达高水平的血栓素受体 (TxR)，远高于此 测试的其他组织。 最后，TxR 表达已本地化为 未成熟的胸腺细胞和这些细胞暴露于 TxA2 诱导 细胞凋亡。 因此，假设 TxA2 与其受体结合，并通过 特定的信号通路，调节重要的细胞过程 T 细胞的成熟和选择。 该项目的目标是 鉴定 TxR 的生化特征和个体发育 胸腺细胞并确定 TxA2 在胸腺细胞发育中的功能。 为了研究这一假设，提出了三个具体目标：(1) 表征与 TxR 偶联的信号转导途径 胸腺细胞。 在这些研究中，信号转导途径耦合 新鲜分离的胸腺细胞中的 TxR 将通过以下方式鉴定 微生理测量学和主动第二信使耦合证实 标准生化测定。 (2) 识别哪些信号被激活 TxR 导致胸腺细胞凋亡。 这些研究将直接决定 哪个第二信使（在特定目标 I 中确定）进行调解 体外胸腺细胞凋亡。 (3) 定义 TxA2 对 胸腺细胞在体外成熟。 使用胎儿胸腺器官培养作为 胸腺发育模型，申请人直接测试作用 TxA2 对 T 细胞发育的影响。 T细胞受体 转基因小鼠将用于专门检查 TxA2 在 控制自身反应性 T 细胞前体的阴性选择。 该项目预计将提供有关 胸腺细胞中TxR的表达、功能及有效作用 TxA2 在调节 T 细胞成熟中的作用。 希望大家理解 脂质介质在胸腺发育中的作用可能提示新的 预防自身免疫性疾病和诱导的策略 对同种异体器官移植的移植耐受。