Study on transcriptional regulation in CD40 signaling.

CD40信号传导转录调控的研究。

• 批准号: 12670295
• 负责人: TSUBATA Takeshi
• 金额: $ 2.11万
• 依托单位: Tokyo Medical and Dental University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12670295/
• 关键词: lymphocyte; transcription; apoptosis; NF-kB; promoter; CD40; kip1; cell cycle; NF-KB; klp1; c-Myc; Bリンパ球; 転写因子; p27^<Kip>; 標的遺伝子

CD40 signaling plays an essential role in immune responses. CD40 signaling activates various signaling molecules such as the transcription factor NF-kB. However, it is not yet elucidated how these signaling molecules regulate the target genes. It is also not yet clear how the products of the target genes are involved in immune responses. Previously, we demonstrated that CD40 signaling reduces the mRNA level of the cell cycle inhibitor kip1. First, we addressed the molecular mechanisms for the repression of kip1 by CD40 signaling. We assessed the promoter activity of the kip1 gene by luciferace assay using 3T3 cells, and demonstrated that NF-kB repress the kip1 promoter. Further the region containing -581 to -348 in the kip1 promoter carry two NF-kB recognition sequences and the promoter activity in this region is suppressed by NF-kB. This suggests that this region may play a role in CD40-mediated suppression of the kip1 level. However, NF-kB-mediated suppression still occurs even if the NF-kB site is mutated. Thus, how NF-kB represses the promoter activity in this region is still unclear. Next, we assessed the role of kip1 repression in CD40-mediated B cell proliferation and survival. Since p27kip1 inhibits CDKs essential fur cell cycle progression, kip1 repression may play a role in B cell proliferation induced by CD40 signaling. CD40 signaling induces survival of the B cells including the B cell line WEHI-231 by abrogating antigen receptor-mediated apoptosis. When we expressed kip1 in WEHI-231 cells using a retrovirus vector, survival of antigen receptor-ligated WEHI-231 cells is partially impaired. This indicates that kip1 suppression is required for fully restore antigen receptor-induced apoptosis by CD40 signaling. Taken together kip1 repression appears to involve NF-kB and play a role in proliferation and survival of B cells.

CD40 信号传导在免疫反应中发挥着重要作用。 CD40 信号传导激活各种信号分子，例如转录因子 NF-kB。然而，目前尚未阐明这些信号分子如何调节靶基因。目前还不清楚靶基因的产物如何参与免疫反应。之前，我们证明 CD40 信号传导会降低细胞周期抑制剂 kip1 的 mRNA 水平。首先，我们探讨了 CD40 信号传导抑制 kip1 的分子机制。我们使用 3T3 细胞通过荧光素酶测定评估了 kip1 基因的启动子活性，并证明 NF-kB 抑制 kip1 启动子。此外，kip1启动子中包含-581至-348的区域携带两个NF-kB识别序列，并且该区域的启动子活性被NF-kB抑制。这表明该区域可能在 CD40 介导的 kip1 水平抑制中发挥作用。然而，即使 NF-kB 位点发生突变，NF-kB 介导的抑制仍然会发生。因此，NF-kB 如何抑制该区域的启动子活性仍不清楚。接下来，我们评估了 kip1 抑制在 CD40 介导的 B 细胞增殖和存活中的作用。由于 p27kip1 抑制 CDK 必需的细胞周期进程，因此 kip1 抑制可能在 CD40 信号传导诱导的 B 细胞增殖中发挥作用。 CD40 信号传导通过消除抗原受体介导的细胞凋亡来诱导 B 细胞（包括 B 细胞系 WEHI-231）的存活。当我们使用逆转录病毒载体在 WEHI-231 细胞中表达 kip1 时，抗原受体连接的 WEHI-231 细胞的存活受到部分损害。这表明 kip1 抑制是通过 CD40 信号传导完全恢复抗原受体诱导的细胞凋亡所必需的。综上所述，kip1 抑制似乎涉及 NF-kB，并在 B 细胞的增殖和存活中发挥作用。

项目成果

Tsubata T: "Rapid B cell apoptosis induced by antigen receptor ligation does not require Fas(CD95/APO-1), the adaptor protein FADD/MORT1 or CrmA-sensitive caspases but is defective in both MRL-+/+ and MRL-lpr/lpr mice"Int. Immunol.. 12. 517-526 (2000)

Tsubata T：“抗原受体连接诱导的快速 B 细胞凋亡不需要 Fas(CD95/APO-1)、接头蛋白 FADD/MORT1 或 CrmA 敏感的半胱天冬酶，但 MRL- / 和 MRL-lpr/lpr 均存在缺陷

Tsubata T: "B cell tolerance and autoimmunity"Rev.Immunogenet.. 2. 18-25 (2000)

Tsubata T：“B 细胞耐受性和自身免疫”Rev.Immunogenet.. 2. 18-25 (2000)

Tsubata T: "Rapid B cell apoptosis induced by antigen receptor ligation does not require Fas (CD95/APO-1),the adapter protein FADD/MORT1 or CrmA-sensitive caspases but is defective in both MRL-+/+ and MRL-lpr/lpr mice"Int.Immunol.. 12. 517-526 (2000)

Tsubata T：“抗原受体连接诱导的快速 B 细胞凋亡不需要 Fas (CD95/APO-1)、接头蛋白 FADD/MORT1 或 CrmA 敏感的半胱天冬酶，但 MRL- / 和 MRL-lpr/lpr 都有缺陷

Higuchi T: "Cutting Edge : Ectopic expression of CD40 llgand on B calls induces lupus-likeautolmmune disease"J. Immunol. 168. 9-12 (2002)

Higuchi T：“前沿：B 细胞上 CD40 配体的异位表达诱导狼疮样自身免疫性疾病”J.

Tsubata T: "Molecular mechanisms for apoptosis induced by siganling through the B cell antigen receptor"Int. Rev. Immunol.. Vol.20 No.6. 791-803 (2001)

Tsubata T：“信号通过 B 细胞抗原受体诱导细胞凋亡的分子机制”Int。