DGKα和ζ协同调控T细胞无能和调节性T细胞功能的分子机制

It is known that diacylglycerol (DAG) kinase (DGK) α or ζ negatively regulates T cell receptor (TCR)-medicated activation. Our preliminary data have shown that T cells deficient of both DGKα andζ (DGKα-/-ζ-/-) are spontaneously activated, DGKα-/-ζ-/- Tregs manifest abnormal phenotype and impaired function, correlating with elevated Erk1/2 activation,and DGKα-/-ζ-/- mice develop spontaneous autoimmune hepatitis (AIH) that can be adoptively transferred to T cell deficient mice by DGKα-/-ζ-/- T cells and that can also be suppressed by wild-type (WT) Tregs. Therefore,our central hypothesis in this application is that DGKα and ζ synergistically regulate DAG metabolism and play a pivotal role for peripheral T cell self-tolerance by promoting T cell anergy and Treg function. By use of conventional and conditional DGKα-/-ζ-/- mice as a model, we plan to test our central hypothesis by pursuing the following three specific aims: to determine how DGKα and ζ synergistically control T cell anergy for self-tolerance, to investigate mechanisms by which DGK activity contributes to T cell anergy, and to explore the mechanisms that regulate Treg function. The proposed studies should establish DGK activity as an important regulator for T cell anergy and Treg function, which will improve understanding of the mechanisms that regulate T cell anergy and Treg function,and are critically involved in the pathogenesis of autoimmune diseases,and thus identify therapeutic strategies for modulating T cell anergy and Treg function in order to treat autoimmune diseases and cancer.

甘油二酯激酶(DGKα)或ζ已知能负调控TCR介导的T细胞活化。我们前期研究显示：DGKαζ双缺失小鼠的T细胞能自发激活，Treg表型异常且功能障碍，并伴有Erk1/2过度活化；DGKαζ双缺失小鼠会发生自发性自身免疫性肝病(AIH)，且过继转移这些小鼠的T细胞至T细胞缺陷小鼠可诱发AIH，但野生型Treg可抑制该AIH的发生。因此，我们提出如下假说：DGKα和DGKζ协同调节DAG的代谢，通过诱导T细胞无能和促进Treg功能，在外周T细胞耐受中发挥决定性作用。我们拟借助DGKαζ双缺失小鼠及其条件性缺陷小鼠模型,阐明DGKα和DGKζ协同调控T细胞无能导致自身耐受的机制、DGK活性增强促进T细胞无能的机制、以及DGK调控Treg功能的机制。本课题有助于阐明T细胞外周耐受以及自身免疫性疾病发生发展的机制，并有望通过调控T细胞无能和Treg功能为自身免疫性疾病和肿瘤的有效治疗提供新策略。

CD4辅助性T（TH）细胞对于抵抗病原体的适应性免疫应答至关重要，同时也会导致自身免疫性疾病的发生发展。对于TCR下游信号如何调节TH分化我们仍然知之甚少。甘油二脂激酶（DGKs）催化甘油二脂转化为磷脂酸，我们以DGK剂量依赖的方式探索其对TH细胞分化产生的不同影响及其机制：DGKα或ζ缺失会选择性损害TH1的分化， 但对TH2和TH17的分化则无明显影响；在体外和体内同时敲除DGKα和ζ 则会促进TH1和TH17分化，导致气道炎症恶化；DGKα和ζ双缺失CD4 T细胞对TH1和TH17分化的异常调节至少部分是由mTOR复合体1-S6K1信号增强所引起的。因此，我们阐明了DGKα和ζ在Th细胞分化过程中的调控作用及其分子机制，从而为在与Th1和Th17细胞异常相关的自身免疫病中将DGKs作为潜在的治疗靶点提供了理论依据。