TOB2对TLR介导的免疫反应的调控作用及其分子机制

The innate immune response acts as a sentinel for the host defense. Once a microbe has overcome the physical and chemical barriers of host, it’s PAMPs (pathogen-associated molecular patterns) immediately be recognized by PRRs (pattern recognition receptors). And after a series of signal transduction，which finally lead to the production of I type interferon and inflammatory cytokines. TOB2 is a member of the BTG/TOB family of anti-proliferative (APRO) proteins that regulate cell growth. But, the function of TOB2 in innate immune system is still not elucidated. We have demonstrated that TOB2 expression was substantially induced with stimulation of LPS (TLR4 ligand) in thioglycolate-elicited mouse primary peritoneal macrophages. siRNA knockdown of endogenous TOB2 expression resulted in augmented expression of IFN-β, TNF-α and IL-6 in TLR3/4-activated primary peritoneal macrophages, but not in RLR-activated primary peritoneal macrophages. These data suggest that TOB2 may be involved in the regulation of TLR3/4 signaling and production of IFN-β while not in RLR signaling. However, the underlying molecular mechanisms and the functions is not clear. In this following proposal, we plan to use animal model and various of cells combining with varieties of molecular techniques to explore the functions of TOB2 in the producton of IFN-β and inflammatory cytokines by TLR3/4. We will also identify the molecules that are targeted by TOB2 in TLR3/4 signaling to reveal the possible molecular mechanims. Our study is the first to explore the functions of the BTG/TOB family in the reguation of innate immune resonses and may provide a new approach for the prevention of endotoxin shock and autoimmune disease using gene transfection.

固有免疫是机体抗病原微生物感染的“第一道防线”。 当病原微生物入侵时，其病原相关分子模式可被模式识别受体识别，最终导致IFN-β及炎性细胞因子的产生。TOB2作为BTG/TOB抗增殖蛋白家族的成员之一，在固有免疫中的调控作用目前尚未见报道。我们前期实验发现，TLR4的配体LPS可诱导巨噬细胞中TOB2的表达；干扰巨噬细胞中TOB2的表达可显著增强LPS、poly(I:C)介导的IFN-β、TNF-α、IL-6表达，但对SeV、VSV介导的影响不大。提示TOB2可能参与TLR3/4通路而不参与RLR通路，但其分子调控机制还不清楚。本研究利用动物模型、细胞模型和多种分子生物学技术系统探讨TOB2在TLR信号通路中的调控作用并揭示其可能的分子机制。本研究首次提出BTG/TOB家族成员可参与固有免疫信号转导调控，可为寻找基因转染防止内毒素休克、自身免疫性疾病等的免疫调节疗法提供新途径。

固有免疫系统中Toll样受体的激活对消除入侵的微生物至关重要。然而，不受控制的Toll样受体活化可能导致自身免疫和炎症性疾病。在本研究中，我们发现TOB / BTG家族的成员TOB2可以通过竞争性抑制MyD88、TRIF和下游信号分子的结合来负向调节TLR信号通路。抑制TOB2表达可导致MAPKs、NF-kB及IRF3等转录因子的活化，从而增强促炎细胞因子的表达。此外,LPS刺激可增强TOB2与信号分子TRAF6、TRAF3、MyD88及TRIF的结合。体内实验表明,TOB2-/-小鼠更容易感染内毒素休克。本研究首次提出BTG/TOB家族成员可参与固有免疫信号转导调控，可为寻找基因转染防止内毒素休克、自身免疫性疾病等的免疫调节疗法提供新途径。