FUNCTIONAR ROFE OF C-FOS IN DIFFERENTIATION AND PROLIFERATION OF MATURE B CELLS

C-FOS 在成熟 B 细胞分化和增殖中的功能

基本信息

批准号：
09836001
负责人：
TOKUHISA Takeshi
金额：
$ 1.92万
依托单位：
CHIBA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09836001/
关键词：
c-Fos Mature B cells Transgenic mice Apoptosis Hematopoietic stem cells Dormant satae Inducible promoter 胚中心 B細胞クラススイッチ

项目摘要

c-Fos Induces Apoptosis in Germinal Center B CellsWe examined a role of c-Fos in differentiation of mature B cells into IgG producing cells using transgenic mice carrying the c-fos gene under the control of the IFN-a/b-inducible Mx promoter (Mx-c-fos) or the constitutive H-2^b promoter (H2-c-fos). Splenic B cells from Mx-c-fos mice were cultured with LPS and rlL-4, and IgG1^+ B cells were developed in the culture after d 3. When IEN-a/b was added in the culture from d 2, development of IgG1^+ B cells was perturbed and the number of apoptotic cells increased within 24 h, suggesting that c-Fos induces apoptosis in Ig class-switching B cells. To confirm the effect of c-Fos on the B cell differentiation in vivo, H2-c-fos mice were immunized with DNP-OVA.The mice produced primary IgM but not IgG anti-DNP Ab in sera and failed to generate germinal centers in spleen. The perturbation of germinal center formation in H2-c-fos mice was rescued by mating them with transgenic mice carrying the bcl … More -2 gene with the Ig promoter. However, primary IgG1 anti-DNP Ab production was still suppressed in doubly transgenic mice, suggesting that Bcl-2 can delay time of c-Fos-induced apoptosis in Ig class-switching B cells but cannot rescue the death. Since c-Fos is induced in mature B cells reacted with Ags and clonal deletion of self-reactive B cells in germinal centers is insensitive to Bcl-2, these results suggest that c-Fos plays a causal role in clonal deletion of germinal center B cells.Prolonged Expression of c-fos Suppresses Cell Cycle Entry of Dormant Hematopoietic Stem CellsThe proto-oncogene c-fos was transiently up-regulated in primitive hematopoietic stem (Lin^-Sca-1^+) cells stimulated with stem cell factor, interleukin-3, and interleukin-6. To investigate a role of the c-fos in hematopoietic stem cells, we used bone marrow (BM) cells from transgenic mice carrying the c-fos gene under the control of the interferon-a/b inducible Mx-promoter (Mx-c-fos), and fetal liver cells from c-fos-deficient mice. Prolonged expression of the c-fos in Lin^- Sca-1^+ BM cells inhibited factor dependent colony formation and hematopoiesis on a stromal cell layer by keeping them at G0/G1 phase of the cell cycle. These Lin^- Sca-1^+ BM cells on a stromal layer entered into the cell cycle whenever exogenous c-fos was down-regulated. However, ectopic c-fos did not perturb colony formation by Lin^- Sca-1^+ BM cells after they entered the cell cycle. Furthermore, endogenous c-fos is not essential to cell cycle progression of hematopoietic stem cells since the factor dependent and the stroma dependent hematopoiesis by Lin^- Sca-1^+ fetal liver cells from c-fos-deficient mice were not impaired. These results suggest that the c-fos induced in primitive hematopoietic stem cells negatively controls cell cycle progression and maintains them in a dormant state. Less

c-Fos 诱导生发中心 B 细胞凋亡我们使用在 IFN-a/b 诱导型 Mx 启动子控制下携带 c-fos 基因的转基因小鼠，检查了 c-Fos 在成熟 B 细胞分化为 IgG 产生细胞中的作用(Mx-c-fos) 或组成型 H-2^b 启动子 (H2-c-fos) 培养来自 Mx-c-fos 小鼠的脾 B 细胞。第 3 天后，LPS 和 rIL-4 以及 IgG1^+ B 细胞在培养物中发育。当从第 2 天开始在培养物中添加 IEN-a/b 时，IgG1^+ B 细胞的发育受到干扰，凋亡细胞的数量增加。细胞在 24 小时内增加，表明 c-Fos 诱导 Ig 类别转换 B 细胞凋亡。为了证实 c-Fos 对体内 B 细胞分化的影响，用 DNP-OVA 免疫 H2-c-fos 小鼠。小鼠血清中产生初级 IgM，但不产生 IgG 抗 DNP Ab，并且未能在脾脏中产生生发中心。H2-c-fos 小鼠中生发中心形成的扰动是。通过将它们与携带 bcl ... More -2 基因和 Ig 启动子的转基因小鼠交配而获救。然而，在双转基因中，初级 IgG1 抗 DNP 抗体的产生仍然受到抑制。小鼠，表明 Bcl-2 可以延迟 Ig 类别转换 B 细胞中 c-Fos 诱导的凋亡时间，但不能挽救死亡，因为 c-Fos 是在与 Ag 反应的成熟 B 细胞中诱导的，并且自身反应性克隆缺失。生发中心的 B 细胞对 Bcl-2 不敏感，这些结果表明 c-Fos 在生发中心 B 细胞的克隆缺失中发挥因果作用。 c-fos 的延长表达抑制细胞周期进入休眠造血干细胞原癌基因 c-fos 在干细胞因子、白细胞介素 3 和白细胞介素 6 刺激的原始造血干细胞 (Lin^-Sca-1^+) 中短暂上调。为了研究造血干细胞中的c-fos，我们使用了来自携带c-fos基因的转基因小鼠的骨髓（BM）细胞，这些细胞受造血干细胞的控制。干扰素-a/b 诱导型 Mx-启动子 (Mx-c-fos) 和来自 c-fos 缺陷小鼠的胎儿肝细胞 Lin^- Sca-1^+ BM 细胞中 c-fos 的延长表达抑制因子依赖性。通过将基质层上的这些 Lin^- Sca-1^+ BM 细胞保持在细胞周期的 G0/G1 期，在基质细胞层上进行集落形成和造血。然而，异位c-fos在进入细胞周期后不会干扰Lin^-Sca-1^+ BM细胞的集落形成。由于 c-fos 缺陷小鼠的 Lin^- Sca-1^+ 胎儿肝细胞的因子依赖性和基质依赖性造血作用并未受损，因此对造血干细胞的细胞周期进展至关重要。原始造血干细胞中诱导的 c-fos 负向控制细胞周期进程并将其维持在休眠状态。