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Immunoglobulin gene expression and recombinational events in the nurse shark

护士鲨的免疫球蛋白基因表达和重组事件

基本信息

批准号：
9322603
负责人：
ELLEN HSU
金额：
$ 28.26万
依托单位：
SUNY DOWNSTATE MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-01-01 至 2020-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9322603
关键词：
Adaptive Immune System Address Alleles Antibody Diversity Antigen Receptors Autoimmunity B-Lymphocytes Biological Models Cells Chondrichthyes Complex DNA Data Development Disease Distant Elements Enzymes Event Evolution Exclusion Feedback Gene Cluster Gene Expression Gene Silencing Gene Structure Gene Targeting Generations Genes Genetic Genetic Crossing Over Genetic Recombination Genetic Transcription Genome Genomics Germ Cells Growth Human Immune Immunoglobulin Class Switching Immunoglobulin Genes Immunoglobulin M Immunoglobulin Somatic Hypermutation Immunoglobulin Switch Recombination Immunoglobulins Individual Jaw Lead Lesion Lymphocyte Lymphocyte Activation Messenger RNA Modeling Mus Nature Nurses Oocytes Pathogenesis Pathway interactions Pattern Process Proteins Recording of previous events Regulation Research Shark Site Somatic Cell Specificity System Tetrapoda Transcript Translating V(D)J Recombination Vertebrates activation-induced cytidine deaminase adaptive immunity autoreactivity base experimental study immunoglobulin receptor insertion/deletion mutation insight lymphoid neoplasm pathogen receptor tumorigenesis

项目摘要

Lymphocytes express a vast repertoire of antigen receptors, but only one species of receptor is allowed per cell in order for them to respond specifically to pathogens. The diversity of the receptors is generated by V(D)J rearrangement and, in immunoglobulin (Ig) genes, further altered by post- rearrangement somatic hypermutation (SHM) and class switch recombination. All these processes involve DNA strand breakage. It is important to understand the regulation of these pathways, which are part of normal B lymphocyte development. Missteps in the process have been shown to influence or directly initiate oncogenesis. The proposed research is to be done in sharks, representatives of the earliest vertebrates with an adaptive immune system based on V(D)J recombination. Whereas in mouse and human systems there are 3 Ig loci with hundreds of rearranging genes, sharks have a unique Ig gene organization of up to 200 loci, each one containing very few (2-4) recombining elements. This organizational disparity between cartilaginous fishes and tetrapods affords a unique opportunity to gain insight into the complex process governing Ig gene expression by elucidating shared and divergent regulatory mechanisms. Specific Aims 1 and 3 focus on patterns of activity among the many miniloci (27 IgH, 51 IgL) during V(D)J rearrangement. The Ig genes in individual B cells will be examined at the genomic and mRNA level in order to understand interplaying factors that bring about the Ig receptor ultimately expressed. Because preliminary results indicate that more Ig genes appear to be activated than strictly required to make a single functional receptor, experiments are proposed to 1) find if the commonly accepted linkage of rearrangement with transcriptional activity is decoupled in this instance, as part of the regulatory process, and 2) establish if DNA recombination is additionally employed to incapacitate unwanted (e.g. auto-reactive) Ig genes. Specific Aim 2 investigates recombination events in shark B cells initiated by activation-induced cytidine deaminase (AID). AID causes SHM and insertions/deletions not only at the genes encoding the Ig receptor but multiple other Ig sites, so that nicks and double-strand breaks are introduced throughout the genome after lymphocyte activation. We discovered that VDJ from one IgH can be expressed with the C region from another IgH, occurring sometimes after unequal crossing-over between the spatially distant genes. We propose isolating the recombination products that do not encode the receptor, including non- expressed reciprocal products of crossing-over events, in order to clarify the conditions under which partner genes are targeted for recombination. Understanding normal processes in shark B cells that lead to genetic exchange between non-allelic genes is fundamental to understanding pathogenesis of disease states such as autoimmunity and predisposal to lymphoid tumors by aberrant translocations involving Ig genes.

淋巴细胞表达大量的抗原受体，但只有一种受体是每个细胞允许这样做，以便它们对病原体做出特异性反应。受体的多样性是由V(D)J重排产生，在免疫球蛋白(Ig)基因中，进一步由后重排体细胞超突变(SHM)和类切换重组。所有这些过程都涉及到 DNA链断裂。重要的是要了解这些通路的调节，它们是 B淋巴细胞发育正常。这一过程中的失误已被证明影响或直接引发致癌作用。这项拟议的研究将在鲨鱼身上进行，鲨鱼是最早的脊椎动物的代表，具有基于V(D)J重组的自适应免疫系统。而在老鼠和人类系统中， 3个Ig基因座，有数百个重排基因，鲨鱼有一个独特的Ig基因组织，多达200个基因座，每一种都含有极少的(2-4)重组元件。这种组织结构上的差异软骨鱼和四足动物提供了一个独特的机会来洞察这个复杂的过程通过阐明共有的和不同的调节机制来控制Ig基因的表达。具体目标1和3侧重于许多小圈子(27个IGH，51个IGL)在 V(D)J重排。单个B细胞中的Ig基因将在基因组和mRNA水平上进行检测为了了解导致Ig受体最终表达的相互作用因素。因为初步结果表明，似乎有更多的免疫球蛋白基因被激活，而不是制造单个免疫球蛋白的严格要求功能受体，建议进行实验以1)找出普遍接受的重排连锁在这种情况下，转录活性是分离的，作为调控过程的一部分，以及2)确定是否 DNA重组还被用来使不需要的(例如，自身反应的)免疫球蛋白基因丧失能力。特异性目标2研究由激活诱导的鲨鱼B细胞中的重组事件胞苷脱氨酶(AID)。援助导致SHM和插入/缺失不仅仅是在编码Ig的基因上受体，但有多个其他Ig位点，因此缺口和双链断裂被引入整个淋巴细胞激活后的基因组。我们发现来自一个IGH的VDJ可以用C来表示区域，有时发生在空间距离的不等交换之后基因。我们建议分离不编码受体的重组产物，包括非表示交换事件的互惠产品，以澄清合作伙伴在什么情况下基因是重组的目标。理解鲨鱼B细胞中导致遗传的正常过程非等位基因之间的交换是理解这种疾病发病机制的基础通过涉及Ig基因的异常易位，对淋巴肿瘤进行自身免疫和预处理。