Role of TRAF1 in signaling by TNFR2 family members

描述(申请人提供)：肿瘤坏死因子及其同系物在多种生物学过程中发挥重要作用，包括急性时相反应、细胞生长和凋亡、炎症和淋巴细胞激活。肿瘤坏死因子有两种受体：TNFR1和TNFR2。TNFR2是一类跨膜蛋白家族，具有胞内区，缺乏死亡结构域。每个TNFR2家族受体可能与一个或多个TRAF信号转导分子相关联。TRAF2、TRAF3、TRAF5和TRAF6参与了核转录因子-kappaB和AP-1的信号转导和激活。对TRAF1的功能知之甚少，除了它主要表达在活化的淋巴细胞中，并与TNFR家族的许多不同成员有关，包括TNFR2、CD27、CD30、4-1BB、OX-40、HVEM、TRANCE-R、XEDAR、AITR等。TRAF1还与EB病毒潜伏膜蛋白1(LMP1)结合。为了阐明TRAF-1的功能，我们建立了TRAF-1缺陷小鼠。与野生型T细胞相比，TRAF1缺陷的T细胞在抗CD3刺激下表现出明显的增殖。来自TRAF1缺陷小鼠的激活的T细胞，而不是来自其正常后代的激活的T细胞，通过增殖和激活核因子-kappaB和AP-1来响应肿瘤坏死因子。此外，TRAF1基因缺陷小鼠的皮肤对肿瘤坏死因子诱导的T细胞介导的坏死高度敏感。综上所述，这些发现表明TRAF1是肿瘤坏死因子信号的负调节因子。我们建议应用最先进的知识和技术来进一步了解T和B淋巴细胞中TRAF1的功能。我们计划解决三个重要问题： 1.TRAF1负性调控TNFR2信号的确切生化机制是什么？我们将研究TRAF1抑制TNFR2信号转导的分子机制。我们将确定TRAF1在没有TNFR2的情况下由TNFR2进行的信号转导中的作用，以及在没有TNFR2的情况下由TNFR1进行的信号转导中的作用。为此，我们将用缺乏TNFR1或TNFR2.2的小鼠培育TRAF1缺陷小鼠。TRAF1可能对T细胞上表达的其他TNFR2家族成员具有类似的功能，包括OX40、4-1BB、CD30和CD27。同样，与OX40-/-小鼠相反，TRAF1-/-小鼠在过敏性哮喘模型中表现出高反应。我们建议在体外和体内确定TRAF1在OX40信号转导中的作用。TRAF1在EBV LMP1信号转导中起什么作用？我们将分析TRAF1在EB病毒LMP1信号转导和B细胞中的作用。

DESCRIPTION (provided by applicant): Tumor Necrosis Factor (TNF) and it homologues play important roles in a wide array of biological processes including the acute phase response, cell growth and apoptosis, inflammation and lymphocyte activation. TNF has two receptors: TNFR1and TNFR2. TNFR2 represent a family of transmembrane proteins with intracellular region, which lack a death domain. Each of TNFR2 family receptors may associate with one or several TRAF signal transduction molecules. TRAF2, TRAF3, TRAF5, and TRAF6 were shown to participate in signal transduction and activation of NF-kappaB and AP-1 transcription factors. Little is known about TRAF1 function except it is predominantly expressed in activated lymphocytes and is associated with a number of distinct members of the TNFR family, including TNFR2, CD27, CD30, 4-1BB, OX-40, HVEM, TRANCE-R, XEDAR, AITR and others. TRAF1 also binds to latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV). To elucidate the function of TRAF 1 we have generated TRAF 1-deficient mice. Compared to wild type T cells, TRAF1-deficient T cells exhibit markedly increased proliferation to anti-CD3 stimulation. Activated T cells from TRAF1-deficient mice, but not from their normal littermates, responded to TNF by proliferation and activation of NF-kappaB and AP-1. Furthermore, skin from TRAF1-deficient mice was hypersensitive to TNF-induced T-cell mediated necrosis. Taken together, these findings suggest that TRAF1 is a negative regulator of TNF signaling. We propose to apply state of the art knowledge and techniques to further understand TRAF1 function in T and B lymphocytes. We plan to address three important questions: 1. What is the precise biochemical mechanism of TRAF1 negative regulation of TNFR2 signaling? We will study the molecular mechanism of inhibition of TNFR2 signaling by TRAF1. We will determine the role of TRAF1 in signal transduction by TNFR2 in the absence of TNFR1 and signal transduction by TNFR1 in the absence of TNFR2. For this purpose we will breed TRAF1-deficient mice with mice deficient in TNFR1 or TNFR2.2. TRAF1 might have similar function for other members of TNFR2 family expressed on T cells, including OX40, 4- 1bb, CD30, and CD27. Then again, TRAF1-/- mice, in opposite to OX40-/- mice, were hyperresponsive in a model of allergic asthma. We propose to determine the role of TRAF1 in OX40 signaling in vitro and in vivo.3. What is the role of TRAF1 in signaling by EBV LMP1? We will analyze the role of TRAF1 in EBV LMP1 signaling and B cell.