Duck Antibody Genes: Unusual Organization and Expression

鸭抗体基因：异常的组织和表达

• 批准号: 6755056
• 负责人: GREGORY W WARR
• 金额: $ 15.75万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6755056
• 关键词: Duck; Antibody; Genes; Unusual; Organization

DESCRIPTION (provided by applicant): The long-term goal of the proposed studies is to understand the genetic mechanisms controlling the expression of duck immunoglobulin genes. The duck has an immune response that can be characterized as ineffectual, which has significance for human health given the role of ducks (and other waterfowl) as carriers (or reservoirs) of diseases infectious for man. E.g., ducks constitute the only year-round reservoir of avian influenza A viruses, which are a source of genetic variation implicated in the emergence of novel influenza strains pathogenic to man. Understanding the molecular basis of the expression of duck antibodies will permit an understanding of their ineffectual antibody response and also contribute significantly to our understanding of the evolution of transcriptional control, an important aspect of comparative genomics. The duck has an unusual Ig heavy chain (IgH) locus, which has undergone significant rearrangement in its germline organization. The 3 constant (C) region genes are arranged mu-alpha-upsilon, with the alpha gene in reverse transcriptional orientation. This leads to unique problems of transcriptional control associated particularly with the control of class switch recombination. These are addressed in the Specific Aims of this proposal, and the hypotheses to be tested can be phrased as 3 questions: 1) Does the alpha gene have its own I-exon or does it rely on the bi-directional I-upsilon promoter to initiate class switching to IgA? 2) Have the signal transduction pathways that control Ig class-switching, by transcription from I-exon promoters, been conserved in vertebrate evolution? 3) The mammalian IgH locus contains transcriptional enhancers in both the JH to mu intron and 3' of the C-gene cluster. Where, in the duck IgH locus are the enhancers, what transcription factor-binding motifs do they contain, and how do they function? The approach involves identifying transcriptional control elements through functional analysis (i.e. their ability to drive transcription of a reporter gene), and the responsiveness of I-exon promoters to cytokine-induced class-switch signals. The specific motifs involved will be identified by site-directed mutagenesis, and the transcription factors binding these sites will be identified through EMSA/antibody supershift approaches. The results of these proposed studies will enhance our understanding of the molecular basis of the unusual antibody response of the duck, and provide insight into the evolution of transcriptional control in the vertebrate immune system.

描述（由申请人提供）：拟议研究的长期目标是了解控制鸭免疫球蛋白基因表达的遗传机制。鸭子的免疫反应可以说是无效的，鉴于鸭子（和其他水禽）作为人类传染性疾病的携带者（或储存者）的作用，这对人类健康具有重要意义。例如，鸭子是甲型禽流感病毒唯一的常年储存宿主，而甲型流感病毒是导致对人类致病的新型流感病毒株出现的遗传变异来源。了解鸭抗体表达的分子基础将有助于了解其无效的抗体反应，也有助于我们了解转录控制的进化，这是比较基因组学的一个重要方面。鸭子有一个不寻常的 Ig 重链 (IgH) 基因座，该基因座在其种系组织中经历了显着的重排。 3 个恒定 (C) 区基因按 mu-alpha-upsilon 排列，其中 alpha 基因处于逆转录方向。这导致了转录控制的独特问题，特别是与类别转换重组的控制相关的问题。这些在本提案的具体目标中得到解决，要测试的假设可以表述为 3 个问题：1) α 基因是否有自己的 I-外显子，或者是否依赖于双向 I-upsilon 启动子启动类别切换至 IgA？ 2) 通过 I-外显子启动子转录来控制 Ig 类别转换的信号转导途径在脊椎动物进化中是否得到了保守？ 3) 哺乳动物 IgH 基因座在 JH 至 mu 内含子和 C 基因簇的 3' 端均含有转录增强子。鸭 IgH 基因座中的增强子位于何处，它们包含哪些转录因子结合基序，以及它们如何发挥作用？该方法涉及通过功能分析（即它们驱动报告基因转录的能力）以及 I-外显子启动子对细胞因子诱导的类别转换信号的响应来识别转录控制元件。所涉及的特定基序将通过定点诱变来鉴定，并且结合这些位点的转录因子将通过EMSA/抗体超转移方法来鉴定。这些拟议研究的结果将增强我们对鸭子异常抗体反应的分子基础的理解，并深入了解脊椎动物免疫系统中转录控制的进化。