Mismatch Repair in V region mutation and isotype switch

V区突变和同种型转换中的错配修复

• 批准号: 6676250
• 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 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6676250
• 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(申请人提供)：对各种错配修复蛋白基因缺陷的小鼠的研究强烈表明，错配修复(MMR)通过影响抗体可变区基因的体细胞超突变(SHM)和类别切换重组(CSR)，在抗体多样性的产生中发挥重要作用。此外，MMR缺陷易患B细胞和T细胞恶性肿瘤。对小鼠MSH2和MSH6缺陷的研究导致了这样的假设，即SHM和CSR可能发生在两个阶段：一个是依赖AID的，导致热点中G和C的突变；另一个是依赖MMR的，导致所有碱基的突变，并不局限于热点基序。我建议检验这一假说，并通过检测外切核酸酶1缺陷的小鼠或表达MMR蛋白的突变使其结合ATP的能力失活的小鼠来了解MMR的作用。缺乏MMR活性的小鼠的表型可能部分反映了对B细胞的阳性和阴性选择，产生了更高亲和力或自身反应性抗体。因此，我还将研究错配修复的作用，并通过使每个已知的MMR蛋白失活并在抗体形成细胞中表达突变蛋白来剖析单个错配修复蛋白的影响，在抗体形成细胞中，突变抗体的阳性和阴性选择不会发生。我将使用MMR修复缺陷细胞来寻找与SHM有关的其他蛋白质。这些研究将为SHM和CSR的生化机制以及MMR在易感B细胞恶性肿瘤和其他癌症中的作用提供新的见解。