Biological definition of Fc receptor homologs

描述（由申请人提供）：此提案描述了一个为期五年的血液学学术生涯发展培训计划。该候选人是血液学/肿瘤学博士后，获得内科委员会认证。建议前两到三年在Max Cooper博士的指导下进行免疫学方面的研究培训，以扩大候选人在淋巴细胞和受体生物学方面的科学知识，以实现研究独立。该研究项目的重点是表征由B淋巴细胞表达的igg样受体多基因家族中的一个成员，该家族是由候选人根据其与经典免疫球蛋白Fc受体的同源性共同发现的。大多数这些基因编码的假定受体，暂时命名为Fc受体同源物（FcRH1-5），具有igg样结构域序列，表明Fc结合能力和细胞质结构域具有一致的激活或抑制基序的基于酪氨酸的序列。FcRH1-5在外周血淋巴组织和不同类型B系恶性肿瘤的B细胞分化过程中存在差异表达。FcRH3家族成员是本研究的重点，预计其编码1型糖蛋白，具有6个ig样结构域、一个不带电的跨膜段和一个细胞质结构域，其中包含基于酪氨酸的激活和抑制共识基序。FcR和FcRH家族成员的比较ig结构域分析表明，FcRH3可能具有Fc结合能力，初步研究支持这种可能性。为了确定哪些细胞表达FcRH3及其生化性质，将产生针对重组FcRH3蛋白的单克隆抗体。为了确认FcRH3的Fc受体能力，将使用纯化的不同同种型的人骨髓瘤igg及其Fc片段进行igg结合试验。原生表达FcRH3的细胞将用于免疫沉淀分析中寻找相关分子。抗fcrh3抗体和天然配体将用于受体连接研究，以检查细胞质酪氨酸一致基序的信号传导能力。本文提出的研究重点是一个家族成员的表达和功能，并作为未来表征其他7个Fc受体同源家族成员及其在正常和病理条件下的作用的原型模型。

DESCRIPTION (provided by applicant): This proposal describes a five-year training program for development of an academic career in Hematology. The candidate, a postdoctoral fellow in Hematology/Oncology, is board certified in Internal Medicine. Research training in Immunology under the supervision of Dr. Max Cooper is proposed for the first two to three years to expand the candidate's scientific knowledge in lymphocyte and receptor biology in order to achieve research independence. The research project focuses on characterization of one of the members of a multi-gene family of Ig-like receptors expressed by B lymphocytes that were co-discovered by the candidate on the basis of their homology with classical immunoglobulin Fc receptors. The putative receptors encoded by most of these genes, provisionally named Fc receptor homologs (FcRH1-5), have Ig-like domain sequences that suggest Fc binding capacity and cytoplasmic domains with tyrosine-based sequences possessing consensus activating or inhibitory motifs. FcRH1-5 are differentially expressed during B cell differentiation in peripheral lymphoid tissues and in different types of B lineage malignancies. FcRH3, the family member that is the focus of this proposal, is predicted to encode a type-I glycoprotein with six Ig-like domains, an uncharged transmembrane segment, and a cytoplasmic domain containing both activation and inhibitory tyrosine-based consensus motifs. Comparative Ig-domain analysis of FcR and FcRH family members suggests that FcRH3 may have Fc binding capacity, and pilot studies support this possibility. For use in determining which cells express FcRH3 and its biochemical nature, monoclonal antibodies will be produced against recombinant FcRH3 protein. In order to confirm the Fc receptor capacity of FcRH3, Ig-binding assays will be performed utilizing purified human myeloma Igs of different isotypes and their Fc fragments. Native FcRH3 expressing cells will be used to search for associated molecules in immunoprecipitation analyses. The anti-FcRH3 antibodies and the native ligands will be used in receptor ligation studies to examine the signaling capacity of the cytoplasmic tyrosine-based consensus motifs. The studies proposed here focus on expression and function of one family member, and serve as a prototypic model for future characterization of the other seven Fc receptor homolog family members and their roles in normal and pathologic conditions.