MECHANISM OF CYTOKINE INDUCED B CELL DIFFERENTIATION

这个项目的长期目标是了解 是终末分化和细胞周期控制的基础 B细胞向浆细胞分化。活体内，终末 B细胞分化的特征是Ig合成增加 分泌，减少表面Ig和MHC类H的表达， 形态成熟和细胞周期停滞。尽管有这样的知识， 其潜在的机制还不是很清楚。白介素6(IL-6) 在晚期B细胞分化中具有生理作用，这一点很明显 过度表达转基因小鼠的浆细胞增多症 IL-6与IL-6缺陷的继发性免疫球蛋白反应缺陷 老鼠。我们已经证明，刺激人类B淋巴母细胞 用IL-6体外重现B细胞终末的主要特征 体内分化。这项提议的目的是澄清 IL-6信号转导调节免疫球蛋白的机制 在B细胞中合成。 IL-6信号被认为是由两个 途径：快速和瞬时的JakStat途径涉及 潜伏转录因子STAT3和STAT3的激活 STAT1，以及一个更稳定的NF-IL6途径，涉及基础- 亮氨酸拉链转录因子NF-IL6。尽管如此 尽管有大量的信息，但仍有两个关键问题尚未解决。 一个是关于这两条路径之间的关系，以及 另一种是启动子特异性的测定。 每条路径。根据我们的初步研究，我们 假设瞬时JAK-STAT通路和 稳定的核因子-白介素6通路在功能上偶联 对IL-6的生理反应通过顺序激活 激活和抑制下游基因的核因子-白介素6 根据核因子-白介素6亚型的比例和 核因子-IL6和JUN之间的二聚化。 假设，我们建议(L)阐明两者之间的耦合 Jak-Stat途径和NF-IL6途径，通过确定 STAT3和他汀类及丝氨酸的需要量 立即激活核因子-IL-6的磷酸化 启动子，(2)确定核因子-IL-6和Jun在 稳定的IL-6信号，以及(3)研究生理 核因子-IL-6亚型在免疫球蛋白合成调控中的作用 通过研究免疫球蛋白启动子的激活和抑制 体内和体外的核因子-IL-6亚型。这些研究应该 提供对以下机制的重要洞察 免疫系统中的细胞因子信号转导和 B细胞终末分化。

The long term goal of this project is to understand the mechanism that underlies differentiation and cell cycle control during terminal differentiation of B cells to plasma cells. In vivo, terminal differentiation of B cells is characterized by increases in Ig synthesis and secretion, reduction in surface Ig and MHC class H expression, morphological maturation and cell cycle arrest. Despite this knowledge, the underlying mechanism is not well understood. Interluekin-6 (IL-6) has a physiologic role in late stage B cell differentiation, as evident by the development of plasmacytosis in transgenic mice overexpressing IL-6 and by the deficiencies in secondary Ig responses in IL-6-deficient mice. We have shown that stimulation of human B lymphoblastoid cells with IL-6 in vitro recapitulates the major hallmarks of B cell terminal differentiation in vivo. The objective of this proposal is to elucidate the mechanism by which IL-6 signals are transduced to regulate Ig synthesis in B cells. The IL-6 signals are thought to be transduced by two pathways: the rapid and transient JakStat pathway involving activation of the latent transcription factors Stat3 and Statl, and a more stable NF-IL6 pathway involying the basic- leucine zipper transcription factor NF-IL6. Despite this wealth of information, two crucial issues remain unresolved. One concerns the relationship between the two pathways and the other the determination of the promoter specificity in each pathway. Based on our preliminary studies, we hypothesize that the transient Jak-Stat pathway and the stable NF-IL6 pathways are functionally coupled for physiologic responses to IL-6 by sequential activation of NF-IL6, which activates and inhibits downstream genes according to the ratio of NF-IL6 isoforms and by dimerization between NF-IL6 and Jun. To test this hypothesis, we propose to (l) elucidate the coupling between the Jak-Stat pathway and the NF-IL6 pathway, by determining the requirement of Stat3 and Statl and serine phosphorylation for the immediate activation of the NF-IL-6 promoter, (2) determine the roles of NF-IL6 and Jun in stable IL-6 signaling, and (3) investigate the physiologic roles of NF-IL6 isoforms in the regulation of Ig - synthesis by studying the activation and inhibition of Ig promoters by NF-IL6 isoforms in vitro and in vivo. These studies should provide significant insight into the the mechanisms that underlie cytokine signaling in the immune system and terminal differentiation of B cells.