EVOLUTIONARY MECHANISMS OF V AND C GENE DIVERSITY

V和C基因多样性的进化机制

• 批准号: 2178312
• 负责人: BARBARA A OSBORNE
• 金额: $ 17.89万
• 依托单位: UNIVERSITY OF MASSACHUSETTS AMHERST
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-01 至 1997-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2178312
• 关键词: B lymphocyte; animal genetic material tag; animal population genetics; biochemical evolution; cow; gene expression; gene rearrangement; genetic library; genetic manipulation; immunoglobulin genes; linkage mapping; molecular cloning; molecular genetics; nucleic acid probes; nucleic acid sequence; site directed mutagenesis

A hallmark of the vertebrate immune response is an ability to Create a diverse repertoire of immunoglobulin specificities. In mouse and human, this is accomplished by the somatic rearrangement of a large number of V(D)J gene segments. By combinatorial joining of gene segments in additional to junctional diversity occurring at the joining sites between gene segments, a spectrum of repertoires is generated. More recently, it has been recognized that these mechanisms of generating diversity are not utilized by all vertebrates. For example, chicken Ig light chain diversity is created by a single V(J) rearrangement followed by gene conversion of the rearranged V(J) gene using, as donors, 25 pseudogenes located immediately 5' to the V(J) gene. Rabbits use a similar strategy of gene conversion to create diversity although it appears that this species carry many more functional V genes than chicken. Sheep light chains also have been shown to undergo few V(J) gene rearrangements, but instead of generating diversity through gene conversion, appear to use somatic mutation in order to create a wide spectrum of specificities. Thus a wide variety of mechanisms are available to vertebrates for generation of diversity. This proposal addresses both the mechanism of generation of diversity and the site where B cell diversification occurs in cattle. Preliminary data are presented to demonstrate cattle express an extremely limited number of V genes and that diversification of these genes occur through either gene conversion or somatic mutation. A last goal of the proposed studies, is to address the control of light chain isotype expression. While data from mouse and human indicate that the preponderance of kappa light chain expression may be explained by the rearrangement of kappa genes before lambda, in species where lambda light chain is the predominant isotype, this question remains unresolved. Through the use of cloned kappa and lambda probes from cattle in conjunction with hybridomas expressing either cow isotype, this issue will be addressed.

脊椎动物免疫反应的一个标志是能够产生 免疫球蛋白特异性的多样性。 在小鼠和人类中， 这是通过大量的体细胞重排来完成的 V(D)J 基因片段。 通过基因片段的组合连接 除了连接部位发生的连接多样性之外 在基因片段之间，产生了一系列的指令集。更多的 最近，人们认识到这些产生机制 并非所有脊椎动物都利用多样性。 例如，鸡 Ig 轻链多样性是由单个 V(J) 重排产生的 通过重排 V(J) 基因的基因转换，使用 25 作为供体 假基因位于 V(J) 基因的 5' 端。兔子使用一个 类似的基因转换策略来创造多样性，尽管它 看来这个物种携带的功能性 V 基因比 鸡。 绵羊轻链也已被证明经历了很少的 V(J) 基因重排，但不是通过基因产生多样性 转换，似乎使用体细胞突变来创造广泛的 特异性的范围。因此，有多种机制 可用于脊椎动物产生多样性。 该提案解决了多样性生成的机制 以及牛体内 B 细胞多样化发生的部位。初步的 提供的数据表明牛的表达极其有限 V 基因的数量以及这些基因的多样化是通过 要么是基因转变，要么是体细胞突变。 拟议研究的最后一个目标是解决光的控制问题 链同种型表达。虽然来自小鼠和人类的数据表明 kappa 轻链表达的优势可以解释为 在 lambda 存在的物种中，kappa 基因在 lambda 之前重排 轻链是主要的同种型，这个问题仍然存在 未解决。通过使用克隆的 kappa 和 lambda 探针 牛与表达任一牛同种型的杂交瘤结合， 这个问题将得到解决。