GENETIC VARIATION IN B LYMPHOCYTE ONTOGENY

B 淋巴细胞个体发育的遗传变异

• 批准号: 2395402
• 负责人: MATTHIAS R WABL
• 金额: $ 25.94万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-04-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2395402
• 关键词: B lymphocyte; DNA repair; cell differentiation; gene mutation; gene rearrangement; genetic enhancer element; immunoglobulin genes; laboratory mouse; northern blottings; polymerase chain reaction; tissue /cell culture; transcription factor; transfection

Leading to cancer, aging, or both, somatic mutations are usually detrimental to the individual. Mutations at the immunoglobulin (Ig) loci are an exception, because they generate high affinity antibodies, which are important in memory responses to pathogens. Thus, in the segments of immunoglobulin genes that encode the variable (V) regions of antibodies, mutations are beneficial. Since such mutations arise at a million times higher rate than the normal, spontaneous mutation rate at other loci, the process is called hypermutation. Due to its high rate and to its being focused to a few loci, hypermutation allows easier access to the proximate causes of mutation and may thus serve as a model system for studies of the mutational process in general. Hypermutation is catalyzed by the putative immunoglobulin mutator system, or "mutator". This mutator is thought to put an imbalance onto the general DNA error repair system. The sequences that target the action of the mutator to the immunoglobulin locus ( enhancers) differ from the sequences where the mutator action is seen (the V (D) J segments and their flanking sequences). Furthermore, within the sequences to be mutated, there are short stretches that are even more mutable than the others, and these so-called hot spots may represent sequence motifs. The objective of this application is to define, in an in vitro transfection system as well as in vivo, cis and trans-acting element for hypermutation at the immunoglobulin loci. Specifically, (I) the role of the enhancer in the major intron as well as other other intronic sequences at the immunoglobulin heavy-chain locus will be defined; (ii) the target base pairs, or hot spot motifs, within the V regions will be identified; and (III) mutation frequencies and profiles will be assessed in monoclonal mice with and without a mismatch repair deficiency.

体细胞突变通常会导致癌症、衰老或两者兼而有之 对个人不利。 免疫球蛋白突变 (Ig) 位点是一个例外，因为它们产生高亲和力 抗体，对记忆反应很重要 病原体。 因此，在免疫球蛋白基因片段中 编码抗体的可变（V）区，突变是 有利。 由于此类突变的发生率高出一百万倍 率高于其他位点的正常自发突变率， 过程称为超突变。 由于其高利率和 集中于几个位点，超突变可以更容易地访问 突变的直接原因，因此可以作为模型 一般突变过程研究系统。 超突变由假定的免疫球蛋白催化 突变系统，或“突变体”。 该突变体被认为放置了一个 一般 DNA 错误修复系统的不平衡。 这 将突变子的作用定位到的序列 免疫球蛋白位点（增强子）与序列不同 可以看到增变作用的地方（V (D) J 片段及其 侧翼序列）。 此外，在序列内 突变，有一些短的延伸甚至比 其他的，这些所谓的热点可能代表序列 主题。 本申请的目的是在体外定义 转染系统以及体内顺式和反式作用元件 用于免疫球蛋白位点的超突变。 具体来说，（一） 增强子在主要内含子以及其他内含子中的作用 免疫球蛋白重链位点的内含子序列将 被定义； (ii) 目标碱基对，或热点基序， V区将被识别； (III) 突变频率和 将在有或没有的单克隆小鼠中评估概况 错配修复缺陷。