Molecular mechanism of immune suppression by negative-feedback regulation

负反馈调节免疫抑制的分子机制

• 批准号: 15390156
• 负责人: SAITO Takashi
• 金额: $ 9.79万
• 依托单位: RIKEN (2004)Chiba University (2003)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15390156/
• 关键词: CTLA-4; Regulatory T cell; Gab2; Cbp; PAG; lipid raft; ITAM; T cell; Signal transduction; T細胞活性化; 免疫抑制; アダプター分子; co-stimulation; ラフト

To understand negative regulation of T cell activation, we have analyzed three molecules with inhibitory function, an inhibitory adaptor, Gab2,an inhibitory co-stimulation receptor, CTLA-4,and a newly ITAM^+ molecule, NFAM-1.Gab2 is phosphorylated by ZAP-70 upon TCR stimulation and mediated negative signals through recruitment of a phosphatase SHP-2. Furthermore, we found Gab2 associates with Grb2/Gads by competing with SLP-76,which is another inhibitory mechanism to mediate inhibition. Gab2-Tg mice show decreased T cell activation and block negative selection of thymocytes. These findings indicate that Gab2 function as an inhibitory adaptor for activation and development of T cells.We analyze the function of CTLA-4 in Treg function by establishing CTLA-4-Tg mice since Treg shows constitutive expression of CTLA-4 and could be involved in Treg-mediated suppression. In Tg mice, the number of Treg was reduced, but their suppressive function was not altered. In addition, by isolating Trig from CTLA-4-deficient thymocytes, we found that CTLA-4-/-Treg exhibited similar suppressive function. We concluded that CTLA-4 is not critical for suppressive function of Treg.We have developed a functional cloning system (NACS) using a reporter T cells expressing NFAT-GFP and a CD8-chimeric cDNA library, and cloned a new ITAM-bearing molecule, NFAM-1. When expressed in T or B cells, NFAM-1-ITAM was tyrosine-phosphorylated and recruited ZAP-70 or Syk upon stimulation. NFAM-1-Tg mice revealed strong blockade of development of B cells but not T cells. However, the NFAM-1-KO mice showed no significant defects of the development of both T and B cell development, suggesting that there is a redundancy with other molecules in vivo. NFAM-1 did not have any charged amino acid residues within the transmembrane region, it may represent a new family of ITAM^+ molecules.

为了了解T细胞激活的负调控，我们分析了三个具有抑制功能的分子，抑制性适配器Gab2，抑制性共刺激受体Gab2，CTLA-4，以及一个新的ITAM^+分子NFAM-1。Gab2在TCR刺激下被ZAP-70磷酸化，并通过募集磷酸酶SHP-2来介导负信号。此外，我们发现Gab2通过与SLP-76竞争而与Grb2/Gads结合，SLP-76是另一种介导抑制的抑制机制。Gb2-Tg小鼠表现出T细胞活性降低，胸腺细胞的阴性选择受阻。我们通过建立CTLA-4-TG小鼠来分析CTLA-4在Treg功能中的作用，因为Treg显示CTLA-4的结构性表达，并且可能参与Treg介导的抑制。在TG小鼠中，Treg的数量减少，但其抑制功能没有改变。此外，通过从CTLA-4缺乏的胸腺细胞中分离TRIG，我们发现CTLA-4-/-Treg具有类似的抑制功能。我们利用表达NFAT-GFP的报告T细胞和CD8-嵌合的cDNA文库构建了一个功能克隆系统，并克隆了一个新的ITAM分子NFAM-1。当在T或B细胞中表达时，NFAM-1-ITAM被酪氨酸磷酸化，并在刺激下募集ZAP-70或Syk。NFAM-1-TG小鼠对B细胞的发育有很强的抑制作用，但对T细胞的发育没有影响。然而，NFAM-1-KO小鼠没有表现出T细胞和B细胞发育的明显缺陷，这表明在体内与其他分子存在冗余。NFAM-1在跨膜区没有任何带电氨基酸残基，可能代表了一个新的ITAM^+分子家族。

项目成果

Fujii, T.: "Predominant role of Fc γ RIII in the induction of accelerated nephrotoxic glomerulonephritis."Kidney Intl.. 64. 1406-1416 (2003)

Fujii, T.：“Fc γ RIII 在诱导加速性肾毒性肾小球肾炎中的主要作用。”Kidney Intl.. 64. 1406-1416 (2003)

Matsumoto, K.: "Fc receptor-independent development of autoimmune glomerulonephritis in lupus-prone MRL lpr mice"Arthritis.Rheum.. 48・2. 486-494 (2003)

Matsumoto, K.：“狼疮倾向 MRL lpr 小鼠中自身免疫性肾小球肾炎的 Fc 受体依赖性发展”Arthritis.Rheum.. 48・2（2003）。

CD25^+CD4^+ regulatory T cells exert in vitro suppressive activity independently of CTLA-4

CD25^ CD4^ 调节性 T 细胞独立于 CTLA-4 发挥体外抑制活性

• 发表时间: 2005
• 期刊: Int.Immunol. (in press)
• 作者: Kataoka;H.
• 通讯作者: H.

NFAM1, a new ITAM^+ surface molecule that regulates development and signaling of B lymphocytes.

NFAM1 是一种新的 ITAM^ 表面分子，可调节 B 淋巴细胞的发育和信号传导。

• 发表时间: 2004
• 期刊: Proc.Natl.Acad.Sci.USA 101・(21)
• 作者: Ichinohe Takeshi et al.;Takasuka Naomi et al.;Ishizuka M. et al.;Ohtsuka M. et al.
• 通讯作者: Ohtsuka M. et al.

Predominant role of FcγRIII in the induction of accelerated nephrotoxic gloerulonephritis.

FcγRIII 在诱发加速性肾毒性肾小球肾炎中的主要作用。

• 发表时间: 2003
• 期刊: Kidney Intl. 64
• 作者: Fujii;T.
• 通讯作者: T.