DNA REPAIR AND SOMATIC MUTATION IN ANTIBODY VARIABLE GENES

抗体可变基因中的 DNA 修复和体细胞突变

• 批准号: 6097872
• 负责人: PATRICIA J GEARHART
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6097872
• 关键词: DNA repair; gel electrophoresis; gene expression; gene mutation; genetically modified animals; hybridomas; laboratory mouse; molecular cloning; nucleic acid sequence; polymerase chain reaction; restriction endonucleases; southern blotting; ultraviolet radiation

Somatic hypermutation of variable (V) genes, which encode a portion of immunoglobulin molecules, occurs at a frequency that is a million times greater than mutation in other genes. The molecular mechanism that introduces these mutations is unknown. The project had two major aims. The first goal was to study hypermutation in mice deficient for DNA repair enzymes to see if the frequency and pattern of mutation was different from wildtype mice. The frequency of mutation in V genes from mice deficient for the nucleotide excision repair protein, XPA, and mismatch repair proteins, PMS2, MSH2, and MLH1, was similar to that of wildtype mice, indicating that neither of these repair pathways generates hypermutation. However, the pattern of mutation was altered in the mismatch repair-deficient mice compared to wildtype mice. The results suggest that the hypermutation pathway frequently introduces tandem mutations which are then corrected by a PMS2-dependent repair process, and frequently mutates G C basepairs which are then corrected by a MSH2-dependent pathway. The second goal was to analyze hypermutation in V genes from old and young humans to determine if the frequency or pattern of mutation changes with age. The frequency of mutation was identical in both groups, indicating that old humans have hypermutated antibodies with high affinity for antigens. The spectra of mutation in old humans was different than that of young humans, suggesting that mismatch repair decreases with age.

可变(V)基因的体细胞超突变， 编码一部分免疫球蛋白分子，发生在 比其他基因突变大一百万倍的频率 基因。导致这些突变的分子机制是 未知。该项目有两个主要目标。第一个目标是 研究DNA修复酶缺陷小鼠的高突变 看看突变的频率和模式是否与 野生型老鼠。小鼠V基因突变频率的研究 缺乏核苷酸切除修复蛋白XPA和 错配修复蛋白PMS2、MSH2和MLH1类似于 野生型小鼠，表明这两种基因都不能修复 途径会产生超突变。然而，这种模式 错配修复缺陷小鼠的突变发生了改变 与野生型小鼠相比。结果表明， 高突变途径经常引入串联突变 然后通过依赖于PMS2的修复过程进行校正，以及 频繁地改变G C基准面，然后由 MSH2依赖途径。第二个目标是分析 老年人和年轻人V基因超突变的研究 如果突变的频率或模式随着年龄的变化而变化。这个 两组的突变频率是相同的，表明 老年人具有高亲和力的高度突变的抗体 抗原。老年人的突变谱不同于 年轻人的这种情况，表明错配修复减少 随着年龄的增长。