Functional distinctions of IgM vs. IgG-containing B cell receptors

IgM 与包含 IgG 的 B 细胞受体的功能差异

• 批准号: 8077304
• 负责人: ROBERT C RICKERT
• 金额: $ 18.91万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8077304
• 关键词: Address; Adopted; Affinity; Antibodies; Antibody-Producing Cells; Antigens; Area; B-Cell Activation; B-Lymphocytes; Biochemical; Cell Line; Cellular biology; Clonal Expansion; Complex; Cytoplasmic Tail; Disease; Funding Mechanisms; Gene Silencing; Generations; Hen Egg Lysozyme; IgE; IgE Receptors; IgG Receptors; IgG1; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin D; Immunoglobulin G; Immunoglobulin M; Immunoglobulins; Knock-in Mouse; Life; Mass Spectrum Analysis; Mediating; Membrane; Memory; Memory B-Lymphocyte; Methods; Molecular; Mus; Outcome; Pathway interactions; Phosphoric Monoester Hydrolases; Phosphotyrosine; Physiological; Pilot Projects; Plasma Cells; Production; Property; Protein Binding; Protein Tyrosine Kinase; Proteins; Proteomics; Receptor Signaling; Receptors, Antigen, B-Cell; Relative (related person); Signal Transduction; Site; Specificity; Transgenic Mice; Tyrosine; Tyrosine Phosphorylation; Vaccines; base; chronic autoimmune disease; mouse model; novel; pathogen; public health relevance; receptor; research study

DESCRIPTION (provided by applicant): Molecular studies of memory B cell activation have been hampered by their relative scarcity and lack of effective technical approaches to unveil the distinctive activation pathways employed by memory versus naive B cells. Most memory B cells express IgG-containing B cell receptors, while naive B cells express IgM/IgD. Relative to IgM/IgD, IgG/IgE receptors have an extended cytoplasmic tail that contains conserved phosphotyrosine (pTyr) motifs and confers enhanced survival and proliferation. This proposal utilizes cutting edge proteomic approaches, gene silencing methods and mouse models to elucidate differences in IgM/IgD- versus IgG-based signaling. As tyrosine kinase/phosphatase activity is known to be critical for BCR signaling, our analysis is focused on determining differences in induced tyrosine phosphorylation of downstream substrates by IgG versus IgM/IgD receptors. Based upon our pilot studies we expect to discover three classes of novel pTyr residues: (1) Novel pTyr sites on known BCR signaling effectors; (2) pTyr sites on known proteins not previously associated with BCR signaling intermediates; and (3) pTyr sites on novel proteins. Proteins bearing these novel pTyr sites will be functionally characterized using gene silencing methods in B cell lines and primary IgG-expressing B cells. Further mass spectrometry methods will be applied to characterize proteins binding to the novel pTyr residues. Determining the functional importance and signaling properties of these effectors should greatly aid our understanding of how IgG expression directs memory B cell propagation and differentiation. PUBLIC HEALTH RELEVANCE: Project Narrative The efficacy of many vaccines depends upon the antigen-specific activation of long-lived memory B cells to rapidly differentiate into high-affinity antibody producing cells upon pathogen re-exposure. In chronic autoimmune diseases, production of pathogenic antibody may also be derived from the propagation and subsequent differentiation of memory B cells. Despite their importance, molecular studies of memory B cell activation have been hampered by their relative scarcity and lack of effective technical approaches to unveil the distinctive activation pathways employed by memory versus naove B cells. Most memory B cells express IgG-containing B cell receptors, while naove B cells express IgM/IgD. This proposal utilizes cutting edge proteomic approaches, gene silencing methods and mouse models to identify and evaluate differences in IgM/IgD- versus IgG-based signaling. As tyrosine kinase/phosphatase activity is known to be critical for BCR signaling, our analysis is focused on determining differences in induced tyrosine phosphorylation of downstream substrates by IgG versus IgM/IgD receptors. Determining the functional importance and signaling properties of these effectors should greatly aid our understanding of how IgG expression directs memory B cell propagation and differentiation.

描述（由申请人提供）：记忆B细胞激活的分子研究受到其相对稀缺性和缺乏有效的技术方法来揭示记忆与天真B细胞所采用的独特激活途径的有效技术方法。大多数记忆B细胞表达含IgG的B细胞受体，而天真的B细胞表达IgM/IgD。相对于IgM/IgD，IgG/IgE受体具有延伸的细胞质尾巴，其中含有保守的磷酸酪氨酸（PTYR）基序，并赋予增强的存活率和增殖。该建议利用最先进的蛋白质组学方法，基因沉默方法和小鼠模型来阐明基于IGM/IGD-基于IgG的信号传导的差异。由于已知酪氨酸激酶/磷酸酶活性对于BCR信号至关重要，因此我们的分析重点是确定IgG与IgM/IgD受体对下游底物诱导酪氨酸磷酸化的差异。基于我们的试点研究，我们期望发现三类的新型PTYR残基：（1）已知的BCR信号效应子上的新型PTYR位点； （2）以前与BCR信号中间体相关的已知蛋白质上的PTYR位点； （3）新型蛋白质上的PTYR位点。具有这些新型PTYR位点的蛋白质将在B细胞系和表达IgG的B细胞中使用基因沉默方法在功能上表征。将采用进一步的质谱法来表征与新型PTYR残基结合的蛋白质。确定这些效应子的功能重要性和信号传导特性应极大地帮助我们理解IgG表达如何指导记忆B细胞的传播和分化。 公共卫生相关性：项目叙述许多疫苗的功效取决于长期记忆B细胞的抗原特异性激活，以在病原体重新暴露时迅速区分成高亲和力抗体。在慢性自身免疫性疾病中，致病性抗体的产生也可能来自记忆B细胞的传播和随后的分化。尽管它们的重要性，但记忆B细胞激活的分子研究受到了它们的相对稀缺性和缺乏有效的技术方法来揭示记忆与NAOVE B细胞所采用的独特激活途径。大多数记忆B细胞表达含IgG的B细胞受体，而NaOVE B细胞表达IgM/IgD。该建议利用最先进的蛋白质组学方法，基因沉默方法和小鼠模型来识别和评估基于IgM/IgD-基于IgG的信号传导的差异。由于已知酪氨酸激酶/磷酸酶活性对于BCR信号至关重要，因此我们的分析重点是确定IgG与IgM/IgD受体对下游底物诱导酪氨酸磷酸化的差异。确定这些效应子的功能重要性和信号传导特性应极大地帮助我们理解IgG表达如何指导记忆B细胞的传播和分化。