SIGNAL TRANSDUCTION IN B CELL ACTIVATION

B 细胞激活中的信号转导

• 批准号: 3132102
• 负责人: John C Cambier
• 金额: $ 11.96万
• 依托单位: NATIONAL JEWISH HEALTH
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-12-01 至 1991-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3132102
• 关键词: B lymphocyte; T lymphocyte; antibody receptor; antigen presentation; binding proteins; biological signal transduction; calcium transporting ATPase; gene expression; genetic manipulation; guanosine triphosphate; histocompatibility antigens; immunoglobulin D; immunoglobulin M; laboratory mouse; leukocyte activation /transformation; membrane activity; membrane proteins; phospholipase C; phosphorylation; protein kinase C; protooncogene; tissue /cell culture; transfection

B lymphocyte membrane immunoglobulins (mIg) appear to play multiple roles in the generation of humoral immune responses. They focus antigen for subsequent internalization, processing and expression in the context of Ia. The also transduce transmembrane signals which lead to increased expression of proto-oncogenes and Ia antigens, and in some situations to B cell proliferation. Since the last renewal of this grant, many of the principal elements of the transduction cascade utilized by mIg have been defined. These include phosphoinositide hydrolysis, Ca++ mobilization, and protein kinase C activation. However, the basis by which mIg binding initiates this cascade remains an enigma. In view of the relatively small size of the cytoplasmic portion of mIg and mIgM and mIgD, it seem likely that these molecules utilize secondary transducer molecules analogous to the T cell T3 complex and/or GTP- binding (N) proteins to mediate the activation of phosphoinositide hydrolysis. Our preliminary studies indicate that mIgM and mIgD are associated with accessory molecules in the plasma membrane, and that these molecules are phosphorylated following ligand binding to mIg. Further evidence suggests that phosphorylation of these molecules may lead to receptor desensitization. We propose to define these molecules and explore the possibility that they and/or GTP-binding proteins function as transducer molecules utilize a newly-developed isolated membrane system to study the role of GTP and GTP-binding proteins in mIg coupling to phosphoinositide hydrolysis. Receptor desensitization, as evidenced by the failure of cells to mobilize Ca++ in response to ligand, will be characterized in terms of kinetics, and inducing-ligand specificity requirements. MIg associated phosphoproteins will be characterized following isolation from normal B cells and B lymphomas by copurification with mIg using anti-immunoadsorbents. Finally we will utilize cloned transfectants of mutant IgM genes to determine Ig structural requirements for signal transduction and receptor desensitization, and for association with mIg accessory molecules and N proteins. These studies should allow mapping of mIg domains involved in signal transduction and regulation of receptor sensitivity. They should also provide insight regarding the role of accessory molecules and N proteins in these processes.

B淋巴细胞膜免疫球蛋白（mIg）似乎发挥多种作用， 在产生体液免疫应答中的作用。 他们专注 用于随后内化、加工和表达的抗原 在Ia的背景下。 同样， 导致原癌基因和Ia表达增加 抗原，并且在某些情况下抑制B细胞增殖。 以来 这项补助金的最后一次更新，许多主要内容， 已经定义了mIg所利用的转导级联。 这些 包括磷酸肌醇水解、Ca++移动和蛋白质 激酶C激活。 然而，mIg结合的基础 如何启动这一级联仍然是个谜。 考虑到 mIg和mIgM的胞质部分相对较小 和mIgD，这些分子似乎利用了第二 类似于T细胞T3复合物和/或GTP的转导分子， 介导磷酸肌醇活化的结合（N）蛋白 水解 我们的初步研究表明，mIgM和mIgD 与质膜中的辅助分子相关， 这些分子在配体结合后被磷酸化 到MG。 进一步的证据表明， 分子可能导致受体脱敏。 我们建议 定义这些分子并探索它们和/或 GTP结合蛋白作为转换分子发挥功能， 新开发的分离膜系统用于研究GTP的作用 与磷酸肌醇偶联的mIg和GTP结合蛋白 水解 受体脱敏，如失败所证明 细胞动员Ca++响应配体，将是 在动力学和诱导配体特异性方面表征 要求. 将对MIg相关磷蛋白进行表征 从正常B细胞和B淋巴瘤中分离后， 使用抗免疫吸附剂与mIg共纯化。 最后我们 将利用突变IgM基因的克隆转染子来确定 信号转导和受体的IG结构要求 脱敏，并与mIg辅助分子结合 N蛋白质。 这些研究应该可以定位mIg结构域 参与信号传导和受体调节 灵敏度 他们还应该提供关于角色的见解， 辅助分子和N蛋白在这些过程中。