Elucidation of the molecular mechanisms of negative regulation of autoantibody production by novel lgM receptor

阐明新型IgM受体负调节自身抗体产生的分子机制

• 批准号: 18590465
• 负责人: HONDA Shin-ichiro
• 金额: $ 2.46万
• 依托单位: University of Tsukuba
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18590465/
• 关键词: Fc receptor; IgM; Immune-complex; B cells; B細胞; 自己抗体

B cells obtained from NP-specific BCR knock-in mice (QM mice) were cultured with IgM-immunecomplex and analyzed for their upregulation of CD86 activation marker. While stimulation of B cells with the antigen alone up-regulated the expression of CD86 in an antigen dose-dependent manner, the IgM IC down-modulated the CD86 expression compared with that induced with antigen alone. This down-modulation was abrogated by pre-treatment of B cells with anti-Fcα□μR^□ mAb that was able to block IgM binding. Thus, IgM-IC down-regulates BCR-mediated activation of B cells by co-ligation of BCR and Fcα□μR. Next we generated transfectants of A20. 2J, a B cell lymphoma cell line, stably expressing WT Fcα□μR (A20-WT) or mutant Fcα□μR lacking the cytoplasmic portion (A20-Δ Cyt), and examined BCR-mediated Ca^<2□> influx by flow cytometry. Cross-linking BCR induced Ca^<2□> influx in A20-WT, However, co-ligation of BCR and Fcα□μR downregulated Ca^<2□> influx in A20-WT, In contrast, this inhibition was not observed in A20-Δ Cyt. These results suggested that Fcα□μR suppressed BCR-mediated signaling and their cytoplasmic region was indispensable for this suppression. To investigate Fcα□μR-mediated signaling for negative regulation of B cells, we examined whether the threonine residue in the cytoplasmic region of Fcα□μR was phosphorylated in A20-WT after co-ligation of BCR and Fcα□μR, as Ca^<2□> influx was suppressed in this case. We observed enhanced threonine phosphorylation 1 min after co-ligation of BCR and Fcα□μR by antibodies, although we did not observe such an enhanced threonine phosphorylation after cross-linking BCR alone. These results suggest that the threonine residue might be involved in a negative regulation of B cells by Fcα□μR.

将从NP特异性BCR敲入小鼠（QM小鼠）获得的B细胞与IgM-免疫复合物一起培养，并分析它们对CD 86活化标志物的上调。虽然单独用抗原刺激B细胞以抗原剂量依赖性方式上调CD 86的表达，但与单独用抗原诱导的表达相比，IgM IC下调CD 86的表达。通过用能够阻断IgM结合的抗Fc α□μR^□ mAb预处理B细胞，可以消除这种下调。因此，IgM-IC通过BCR和Fcα□μR的共连接下调BCR介导的B细胞活化。接下来，我们产生A20的转染子。2 J，一种B细胞淋巴瘤细胞系，稳定表达WT Fcα□μR（A20-WT）或缺乏胞质部分的突变型Fcα□μ R（A20-Δ Cyt），并通过流式细胞术检测BCR介导的Ca^<2□>内流。交联BCR可诱导A20-WT细胞内Ca^<2□>内流，而BCR与Fcα□μR共连接可下调A20-WT细胞内Ca^<2□>内流，而A20-Δ Cyt细胞内未观察到这种抑制作用。这些结果表明，Fcα□μR抑制BCR介导的信号转导，其胞浆区是这种抑制不可或缺的。为了研究Fcα □μ R介导的信号传导对B细胞的负调节，我们检查了在BCR和Fcα□μR共连接后，A20-WT中Fcα□μR胞质区域中的苏氨酸残基是否被磷酸化，因为在这种情况下Ca^<2□>内流被抑制。我们观察到在通过抗体共连接BCR和Fcα□μR后1分钟，苏氨酸磷酸化增强，尽管我们在单独交联BCR后没有观察到这种增强的苏氨酸磷酸化。这些结果提示，苏氨酸残基可能参与Fcα□μR对B细胞的负调控。

项目成果

LFA-1-dependent lipid rafts recruitment of DNAM-1 (CD226) in CD4+ T cell.

CD4 T 细胞中 DNAM-1 (CD226) 的 LFA-1 依赖性脂筏募集。

• 发表时间: 2006
• 期刊: lnt. lmmunoL 18
• 作者: Cho Y ;et. al.;Shirakawa J et-al.
• 通讯作者: Shirakawa J et-al.

LFA-1-dependent lipid rafts recruitment of DNAM-1(CD226) in CD4+ T cell.

CD4 T 细胞中 DNAM-1（CD226）的 LFA-1 依赖性脂筏募集。

• 发表时间: 2006
• 期刊: Int. Immunol. 18
• 作者: Shirakawa J;et. al.;Shibuya A et al.;Cho Y et al.;Shirakawa J et al.
• 通讯作者: Shirakawa J et al.

Negative regulation of IgA production by the FcauR, an Fc receptor IgA and IgM.

FcauR、Fc 受体 IgA 和 IgM 对 IgA 产生的负调节。

• 发表时间: 2007
• 作者: KURITA;Naoki;et. al.
• 通讯作者: et. al.

ITIM-bearing Immunoglobulin-like receptor, MAIT-I(CD300a) modulates the inflammatory responses in murine sepsis

携带 ITIM 的免疫球蛋白样受体 MAIT-I(CD300a) 调节小鼠脓毒症的炎症反应

• 发表时间: 2007

A critical role of DNAM-1 in tumor immunosurveillance

DNAM-1 在肿瘤免疫监视中的关键作用

• 发表时间: 2007
• 作者: A Shibuya;C Nakahashi;N Totsuka;S Tahara-Hanaoka.;Honda S. et.al.;Can I et.al.;Iguchi A et.al.
• 通讯作者: Iguchi A et.al.