Biological definition of Fc receptor homologs

描述(由申请人提供)：本建议书描述了一项为期五年的血液学学术生涯发展培训计划。候选人是血液学/肿瘤学博士后，拥有内科委员会认证。在马克斯·库珀博士的指导下进行的免疫学研究培训建议在头两到三年内进行，以扩大候选人在淋巴细胞和受体生物学方面的科学知识，以实现研究独立性。该研究项目的重点是鉴定由B淋巴细胞表达的Ig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。大多数基因编码的受体，暂定为Fc受体同源物(FcRH1-5)，具有Ig样结构域序列，提示Fc结合能力和细胞质结构域，基于酪氨酸的序列具有共同的激活或抑制基序。FcRH1-5在B细胞分化过程中在外周淋巴组织和不同类型的B细胞系恶性肿瘤中差异表达。FcRH3是这一提议的重点家族成员，预计它编码一个I型糖蛋白，具有六个Ig样结构域、一个不带电荷的跨膜片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。对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，初步研究支持这一可能性。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蛋白的单抗。为了确定FcRH3的Fc受体能力，我们将利用纯化的不同类型的人骨髓瘤免疫球蛋白及其Fc片段进行Ig结合分析。天然表达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，以检查基于细胞质酪氨酸的共识基序的信号传递能力。这些研究集中在一个家族成员的表达和功能上，并为其他7个Fc受体同源家族成员的未来特征及其在正常和病理条件下的作用提供了原型模型。

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.