Immunoglobulin Constant Region Switch and Hypermutation in the Nurse Shark

护士鲨的免疫球蛋白恒定区转换和超突变

• 批准号: 8102776
• 负责人: ELLEN HSU
• 金额: $ 34.39万
• 依托单位: SUNY DOWNSTATE MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8102776
• 关键词: Alleles; Antibody Diversity; Antigen Receptors; Autoimmunity; Award; B-Lymphocytes; Biological Models; Cell surface; Cells; Complementary DNA; DNA; DNA Sequence Rearrangement; Data; Disease; Ensure; Enzymes; Event; Exclusion; Feedback; Frequencies; Gene Expression; Gene Structure; Gene Targeting; Genes; Genetic; Genomics; Health; Immune system; Immunization; Immunoglobulin Class Switching; Immunoglobulin Constant Region; Immunoglobulin Genes; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; J segment gene; Jaw; Lesion; Light; Longitudinal Studies; Lymphocyte; Malignant lymphoid neoplasm; Mammals; Mitosis; Mutate; Nature; Nurses; Nursing Models; Pathogenesis; Point Mutation; Process; Regulatory Pathway; Research; Resolution; Secure; Shark; Staging; Stretching; System; Time; V(D)J Recombination; Vertebrates; activation-induced cytidine deaminase; base; insight; mutant; novel; pathogen; receptor; recombinase; repaired; research study

DESCRIPTION (provided by applicant): The adaptive immune system is founded on lymphocytes expressing a vast array of antigen receptors that provide specific recognition in responding to pathogen. Receptor diversity is generated by V(D)J rearrangement and, in immunoglobulin (Ig) genes, post-rearrangement somatic hypermutation. In higher vertebrates mechanisms involving not only hierarchical activation of the 3 Ig loci but also feedback by a successful rearrangement are thought to restrict expression to one allele and one isotype (allelic and isotype exclusion). This process, which ensures primarily one receptor species per cell, is not well understood. Elucidating shared and divergent regulatory pathways in mammals and in sharks, representatives of the earliest vertebrates with a RAG recombinase-based immune system, will allow us to gain insight into the underlying principles upon which adaptive immune systems are constructed. Preliminary data suggest that shark B cells expressing one light (L) chain type at the cell surface also transcribe other L chain types. However, it is not clear how the more than 70 L chain miniloci in nurse shark are regulated. Specific Aim 1 is to examine L chain expression in single shark B cells and determine whether there is clonal expression of the antigen receptor. Some heavy (H) chain cDNA sequences contain V(D)J in combination with C regions different from what is anticipated from the established genomic organization. This genetic exchange occurs somatically and between distantly located IgH genes; it resembles the H chain switch recombination that exists in mammals. Specific Aim 2 is to determine the linkage relationship among the 15 IgH genes and investigate the mechanistic basis for the IgH chain switching process in sharks. Since the switching occurs at the same time as somatic hypermutation, it is hypothesized that both are initiated activation- induced cytidine deaminase. Hypermutation in shark Ig uniquely includes tandem changes of 2-5 bp stretches and sometimes non-templated insertions. To understand how these changes are generated, we will in Specific Aim 3 isolate activated B cells in G2/M phase of the cell cycle, looking for those carrying both mutated and parental V(D)J sequence. The proposed research is part of long-term studies on Ig gene expression in early vertebrates. Understanding the nature of B lymphocyte diversification mechanisms involving DNA breakage and repair will provide insight into the pathogenesis of disease states that include autoimmunity and lymphoid malignancies predisposed by aberrant translocations. PUBLIC HEALTH RELEVANCE: Our shark model system carries about 85 immunoglobulin genes that are targeted by enzymes introducing nicks or lesions in the course of generating antibody diversity. We have observed genetic exchange taking place between the distantly located loci. Studying these phenomena will help determine parameters for genetic exchange between non-allelic genes and give insight into the origins of somatic translocation events leading to disease states.

描述（由申请人提供）：自适应免疫系统建立在表达大量抗原受体的淋巴细胞上，这些抗原受体在反应病原体时提供了特定的识别。受体多样性是由V（D）J重排和免疫球蛋白（IG）基因产生的。在较高的脊椎动物机制中，不仅涉及3个Ig基因座的层次激活，而且还通过成功重排的反馈将表达限制为一个等位基因和一种同种型（等位基因和同型排除）。该过程确保每个细胞中主要是一种受体物种，但尚不清楚。在哺乳动物和鲨鱼中阐明共享和不同的调节途径，具有基于RAG重组酶的免疫系统的最早的脊椎动物的代表将使我们能够深入了解自适应免疫系统的构建的基本原理。初步数据表明，在细胞表面表达一种光（L）链类型的鲨鱼B细胞也转录其他L链类型。但是，尚不清楚如何调节护士鲨鱼中超过70升的链条微米。具体目的1是检查单鲨B细胞中的L链表达，并确定抗原受体是否有克隆表达。一些重的（H）链cDNA序列包含V（d）J与C区域结合使用的V（d）J，与已建立的基因组组织所预期的不同。这种遗传交换在体形和远处的IGH基因之间发生。它类似于哺乳动物中存在的H链开关重组。具体目的2是确定15个IGH基因之间的连锁关系，并研究鲨鱼中IGH链切换过程的机理基础。由于切换与躯体过度次数同时发生，因此假设这两者都是启动激活诱导的胞苷脱氨酶。鲨鱼IG中的超名是独特的，包括2-5 bp拉伸的串联变化，有时还包括未模拟的插入。为了了解这些变化是如何产生的，我们将在特定的AIM 3分离株中以G2/M相分离出活化的B细胞，以寻找携带突变和父母V（D）J序列的那些。拟议的研究是早期脊椎动物Ig基因表达的长期研究的一部分。了解涉及DNA断裂和修复的B淋巴细胞多样化机制的性质将为疾病状态的发病机理提供洞察，这些疾病状态包括自身免疫性和淋巴性恶性肿瘤。公共卫生相关性：我们的鲨鱼模型系统具有大约85种免疫球蛋白基因，这些基因是通过在产生抗体多样性过程中引入刻痕或病变的酶来靶向的。我们已经观察到远距离位点之间发生的遗传交换。研究这些现象将有助于确定非平行基因之间遗传交换的参数，并深入了解导致疾病状态的体细胞易位事件的起源。