Modulation of T Cell Activation and Tolerance by DRAK2

DRAK2 对 T 细胞激活和耐受性的调节

• 批准号: 6983696
• 负责人: Craig Michael Walsh
• 金额: $ 27.56万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6983696
• 关键词: CD95 molecule; T cell receptor; apoptosis; arthritis; autoimmune disorder; autoimmunity; developmental immunology; genetically modified animals; immune tolerance /unresponsiveness; immunomodulators; laboratory mouse; leukocyte activation /transformation; lymphocyte proliferation; phosphorylation; protein localization; protein protein interaction; serine threonine protein kinase; superantigens; transcription factor

Although immune tolerance is clearly important for the prevention of autoimmunity and the maintenance of lymphocyte homeostasis, suprisingly little is known about the intracellular signaling pathways that are involved. To this end, we have identified DRAK2, a serine/threonine kinase that is highly enriched in lymphoid tissues. As a member of the DAP family of kinases, DRAK2 induces apoptosis upon ectopic expression in certain cell lines. In mice with an engineered deficiency in DRAK2, a number of important defects in T lymphocyte development and activation are apparent. T cells derived from these mice are hyperproliferative to suboptimal stimulation through the T cell receptor, indicating an unexpected role in T cell quiescence for this kinase. In accord with this finding, DRAK2-/- mice have an increased proportion of activated T cells in peripheral lymphoid organs. Furthermore, DRAK2-deficient T cells proliferate in the absence of costimulatory signals normally required for T cell activation. We have found that whereas wildtype T cells require crosslinking of both the T cell receptor (TCR) and CD28 for a rapid and sustained calcium response, DRAK2-deficient T cells require only stimulation via the TCR. Paradoxically, clonal expansion following superantigen exposure is dramatically defective in DRAK2-deficient T cells. This defective responsiveness to superantigen is due to enhanced activation-induced cell death (AICD). We are curious about the mechanisms by which DRAK2 interferes with T cell activation and how its activity may modulate immune tolerance. We will determine if known T cell activation pathways are defective in DRAK2-/- mice. We will characterize the kinase biochemically to determine its mode of action. Finally, we will assess the consequences of its absence when AICD is blocked. These results are aimed at providing a more thorough understanding of negative regulation of T cell activation, and how such negative regulation contributes to immune tolerance.

虽然免疫耐受对于预防自身免疫和维持淋巴细胞稳态显然是重要的，但令人惊讶的是，对所涉及的细胞内信号传导途径知之甚少。为此，我们鉴定了DRAK 2，一种在淋巴组织中高度富集的丝氨酸/苏氨酸激酶。作为DAP激酶家族的成员，DRAK 2在某些细胞系中异位表达时诱导细胞凋亡。在DRAK 2工程缺陷的小鼠中，T淋巴细胞发育和活化中的许多重要缺陷是明显的。来自这些小鼠的T细胞过度增殖至通过T细胞受体的次优刺激，表明该激酶在T细胞静止中的意想不到的作用。与这一发现雅阁的是，DRAK 2-/-小鼠的活化T细胞比例增加， 外周淋巴器官中的细胞。此外，DRAK 2缺陷型T细胞在缺乏T细胞活化通常所需的共刺激信号的情况下增殖。我们已经发现，野生型T细胞需要T细胞受体（TCR）和CD 28两者的交联以实现快速和持续的钙应答，而DRAK 2缺陷型T细胞仅需要通过TCR的刺激。巧合的是，超抗原暴露后的克隆扩增在DRAK 2缺陷型T细胞中是显著缺陷的。这种对超抗原的缺陷性反应是由于增强的活化诱导细胞死亡（AICD）。我们对DRAK 2干扰T细胞活化的机制以及其活性如何调节免疫耐受感到好奇。我们将确定已知的T细胞活化途径在DRAK 2-/-小鼠中是否有缺陷。我们将对激酶进行生物化学表征，以确定其作用模式。最后，我们将评估当AICD被阻断时它的缺失的后果。这些结果旨在提供对T细胞活化的负调控的更透彻的理解，以及这种负调控如何有助于免疫耐受。