Mismatch Repair in V region mutation and isotype switch

V区突变和同种型转换的错配修复

• 批准号: 6925507
• 负责人: MATTHEW D SCHARFF
• 金额: $ 33.44万
• 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 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6925507
• 关键词: B lymphocyte; DNA binding protein; DNA repair; adenosinetriphosphatase; antibody formation; cell line; enzyme activity; enzyme linked immunosorbent assay; exonuclease; flow cytometry; gene mutation; gene rearrangement; gene targeting; genetically modified animals; high performance liquid chromatography; immunoglobulin G; immunoglobulin isotypes; laboratory mouse; protein structure function

DESCRIPTION (provided by applicant): Studies in mice that are genetically defective in various mismatch repair proteins strongly suggest that mismatch repair (MMR) plays a major role in the generation of antibody diversity through its affect on somatic hypermutation (SHM) of antibody variable region genes and on class switch recombination (CSR). In addition, deficiencies in MMR predispose to B and T cell malignancies. Studies with of mice MSH2 and MSH6 deficiencies have lead to the hypothesis that SHM and perhaps CSR occur in two phases: one that is AID dependent and results in mutations in G and C in hotspots and a second that depends upon MMR and results in mutations in all bases and is not restricted to hot spot motifs. I propose to test this hypothesis and learn more about the role of MMR by examining mice that are defective in exonuclease 1 or are expressing MMR proteins that have mutations that inactivate their ability to bind ATP. It is possible that the phenotypes of mice lacking MMR activity is partly the reflection of positive and negative selection for B cells making higher affinity or self reactive antibodies. I will therefore also study the role of mismatch repair and dissect out the impact of individual mismatch repair protein by inactivating each of the known MMR proteins and expressing mutant proteins in antibody-forming cells in culture where the positive and negative selection of mutated antibodies will not occur. I will use the MMR repair deficient cells to search for additional proteins that are involve in SHM. These studies should provide new insights into the biochemical mechanisms of SHM and CSR and the role of MMR in predisposing to B cell malignancies and other cancers.

描述（由申请人提供）：在各种不匹配修复蛋白中遗传缺陷的小鼠的研究强烈表明，错配修复（MMR）通过对抗体多样性的产生来产生抗体超女性（SHM）抗体可变区域基因和类转换重组（CSR）的重要作用。另外，MMR的缺陷易受B和T细胞恶性肿瘤。对小鼠MSH2和MSH6缺乏的研究导致了以下假设：SHM或也许CSR在两个阶段中发生：一个依赖性依赖性，并导致热点中G和C的突变，第二个取决于MMR，并导致所有碱基中的突变，并且不限于热点斑点主题。我建议通过检查在核酸外切酶1中有缺陷的小鼠或表达具有使其结合ATP结合的能力的突变的MMR蛋白来检验MMR作用的更多信息，并进一步了解MMR的作用。缺乏MMR活性的小鼠的表型可能部分反映了产生更高亲和力或自我反应性抗体的B细胞的阳性和阴性选择。因此，我还将研究不匹配修复的作用，并通过灭活每种已知的MMR蛋白和在抗体形成细胞中表达突变蛋白在突变抗体的阳性和负选择的抗体形成细胞中表达突变蛋白来剖析单个不匹配修复蛋白的影响。我将使用MMR修复缺陷的细胞来搜索涉及SHM中的其他蛋白质。这些研究应提供有关SHM和CSR的生化机制的新见解，以及MMR在B细胞恶性肿瘤和其他癌症中的作用。