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.

导致癌症，衰老或两者兼而有之，通常是 不利于个人。 免疫球蛋白的突变 （IG）基因座是一个例外，因为它们产生了高亲和力 抗体，在记忆响应中很重要 病原体。 因此，在免疫球蛋白基因的段中 编码抗体的变量（v）区域，突变为 有利。 由于这种突变的出现为一百万倍 速率比其他基因座的正常自发突变率， 过程称为超名。 由于其高率及其 被专注于几个基因座，超称可以更轻松地访问 突变的直接原因，因此可以作为模型 一般的突变过程研究系统。 假定的免疫球蛋白催化过度突变 突变器系统或“突变器”。 人们认为这个突变器是 对一般DNA误差修复系统的不平衡。 这 靶向突变器作用的序列 免疫球蛋白基因座（增强子）与序列不同 看到突变器作用的地方（v（d）j段及其 侧翼序列）。 此外，在序列中 突变，有一些短伸展，甚至比 其他，这些所谓的热点可能代表序列 主题。 该应用的目的是在体外定义 转染系统以及体内，顺式和反式元件 用于免疫球蛋白基因座的超数。 特别是（i） 增强剂在主要内含子以及其他其他方面的作用 免疫球蛋白重链基因座的内含子序列将 被定义； （ii）目标基对或热点图主题 V区域将被确定； （iii）突变频率和 有和没有A 不匹配维修缺陷。