Mismatch repair in V region mutation and isotype switching

V区突变和同种型转换中的错配修复

• 批准号: 7579404
• 负责人: MATTHEW D SCHARFF
• 金额: $ 32.46万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7579404
• 关键词: ATP phosphohydrolase; Affinity; Affinity Chromatography; Antibodies; Antigens; B cell differentiation; B-Cell Development; B-Cell Lymphomas; B-Lymphocytes; Base Excision Repairs; Base Pairing; Biochemical; Cell Cycle Stage; Cells; Characteristics; Complex; DNA; Data; Defect; EXO1 gene; Excision; G1 Phase; Generation of Antibody Diversity; Genes; Genetic; Genetic Recombination; Genome; Genome Stability; Immunoglobulin Class Switching; Immunoglobulin Genes; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulin Variable Region; Immunoglobulins; Immunoprecipitation; Induced Mutation; Infection; Investigation; Knock-in Mouse; Knock-out; Lead; Lymphoma; Lymphomagenesis; MLH1 gene; MSH2 gene; MSH6 gene; Malignant - descriptor; Mediating; Mismatch Repair; Missense Mutation; Molecular Analysis; Mus; Mutant Strains Mice; Mutate; Mutation; Organism; PMS2 gene; Phase; Phenotype; Play; Polymerase; Process; Production; Progress Reports; Proteins; Recruitment Activity; Replication-Associated Process; Rest; Role; Single-Stranded DNA; Somatic Mutation; Staging; Stretching; Structure of germinal center of lymph node; T-Cell Lymphoma; T-Lymphocyte; Work; activation-induced cytidine deaminase; base; cell type; endonuclease; pathogen; prevent; protein protein interaction; public health relevance; repaired; tumor

DESCRIPTION (provided by applicant): Germinal center B cells undergo a high rate of somatic mutation and recombination of their immunoglobulin genes that is responsible for the affinity maturation and isotype switching that generates protective antibodies. These processes are initiated by activation induced cytidine deaminase which generates G:U mismatches that are processed by replication, base excision repair and mismatch repair to produce the mutations required for somatic hypermutation of antibody variable and switch regions. Mismatch repair is responsible for ~60% of the total mutations and most of the mutations in A:T bases that lead to production of more effective antibodies. While mismatch repair normally maintains the integrity and stability of the genome, at the Ig gene it mediates extensive mutation and recombination. Here we propose to examine how germinal center B cells use mismatch repair to recruit error prone repair to specific regions of the immunoglobulin genes while continuing to maintain genomic stability in the rest of genome and to examine role of mismatch repair in the B cell lymphomagenesis. We will do this by: 1) determining how MSH6 and the other mismatch repair proteins interact with PCNA to recruit error prone repair to the immunoglobulin variable and switch regions, but not to other genes in mutating and switching germinal center B cells; 2) comparing the interactions of the mismatch repair proteins with each other and with other proteins in mutating and switching B cells and with those interactions in other types of cells; and 3) examining the characteristics of the lymphomas that arise in MSH6 deficient and mutant mice in order to understand how MSH6 protects B cells from lymphomagenesis. PUBLIC HEALTH RELEVANCE: To protect us from pathogenic organisms, it is necessary for us to produce antibodies to every possible antigen and to rapidly change those antibodies as the pathogen changes. We do this by introducing many mutations into the genes that encode the antibody molecules as we respond to infection and this genetic instability is accomplished mostly through a process called mismatch repair. We will use mice that have genetic defects in mismatch repair to examine how the generation of antibody diversity is accomplished.

描述(由申请人提供)：生发中心B细胞经历了高比率的体细胞突变和免疫球蛋白基因的重组，这是亲和力成熟和同型转换产生保护性抗体的原因。这些过程是由激活诱导的胞苷脱氨酶启动的，它产生G：U错配，通过复制、碱基切除修复和错配修复来产生抗体可变区和开关区的体细胞超突变所需的突变。错配修复是导致产生更有效抗体的A：T碱基突变总数的60%和大部分突变的原因。虽然错配修复通常维持基因组的完整性和稳定性，但在Ig基因，它介导了广泛的突变和重组。在这里，我们建议研究生发中心B细胞如何利用错配修复来招募容易出错的修复到免疫球蛋白基因的特定区域，同时继续维持基因组其余部分的基因组稳定性，并研究错配修复在B细胞淋巴瘤发生中的作用。我们将通过：1)确定MSH6和其他错配修复蛋白如何与增殖细胞核抗原相互作用，以招募容易出错的修复到免疫球蛋白可变和切换区，但不到生发中心B细胞的其他基因；2)比较错配修复蛋白彼此之间以及在突变和切换B细胞中与其他蛋白质的相互作用；以及3)检测在MSH6缺陷和突变的小鼠中出现的淋巴瘤的特征，以了解MSH6如何保护B细胞免受淋巴生成的影响。公共卫生相关性：为了保护我们免受病原体的侵害，我们有必要针对每一种可能的抗原产生抗体，并随着病原体的变化而迅速改变这些抗体。当我们对感染做出反应时，我们通过在编码抗体分子的基因中引入许多突变来做到这一点，而这种遗传不稳定性主要是通过一种称为错配修复的过程完成的。我们将使用在错配修复中有遗传缺陷的小鼠来检查抗体多样性的产生是如何完成的。