Factors and DNA Motifs in Ig Class Switch

Ig 类别转换中的因素和 DNA 基序

• 批准号: 7533006
• 负责人: Amy L Kenter
• 金额: $ 39.25万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7533006
• 关键词: Attention; B-Cell Activation; B-Lymphocytes; Binding; Chromatin; Chromosomal translocation; Chromosome Pairing; Chromosomes; Complex; DNA; DNA Repair; DNA Sequence Rearrangement; DNA lesion; DNA repair protein; Dominant-Negative Mutation; Ectopic Expression; Enhancers; Equilibrium; Event; Exclusion; Genes; Genetic; Genetic Recombination; Genetic Transcription; Histone Acetylation; Histone Deacetylase; Histone H4; Histones; Homologous Gene; Humoral Immunities; IGH@ gene cluster; Immune system; Immunoglobulin Class Switching; Immunoglobulin Constant Region; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; Investigation; Laboratories; Lead; Mature B-Lymphocyte; Methods; Modification; Molecular; Molecular Conformation; Mus; Mutation; Oncogenic; Phase; Preparation; Process; Proteins; Range; Recruitment Activity; Regulatory Element; Repetitive Sequence; Resolution; Role; Site; Specificity; Structure; Synapses; Synaptosomes; TNFRSF5 gene; Techniques; Testing; Thinking; Tissues; Transcript; activation-induced cytidine deaminase; chromatin remodeling; complement C2a; cytokine; in vivo; inhibitor/antagonist; novel; promoter; repaired; scaffold

DESCRIPTION (provided by applicant): Humoral immunity is dependent on the expression of immunoglobulin (Ig) to fend off pathogenic challenges. The humoral immune system has evolved to produce Ig with a broad repertoire of binding specificities. Class switch recombination (CSR) is used to attain diversity of Ig effector function and tissue localization. The murine IgH constant region locus is organized: 5'-V(D)J-C¿-Cd-C?3-C?1-C?2b-C?2a-Ce-Ca-3'. CSR involves an intra-chromosomal deletional rearrangement that focuses on regions of repetitive switch (S) DNA located upstream of each CH gene (with the exception of Cd). The process of CSR can be thought of as composed of three phases including, initiation, S/S synapsis and resolution and repair. AID induced DNA lesions at S regions initiates the process. I propose to examine events leading to S/S synapsis, and discern chromatin modifications associated with transcription and DNA repair. Using the chromosome conformation capture technique (3C), my laboratory has newly investigated the long- range interactions between the 5 intronic enhancer (E¿) located between the VH and CH genes and the 3'Ea enhancer located at the 3'-end of the IgH locus together with the various GLT promoters. We find that in B cells, the E¿ and 3'Ea enhancers are in close spatial proximity forming a unique chromosomal loop configuration. B cell activation leads to recruitment of the germline transcript (GLT) promoters to the E¿: 3'Ea complex in a cytokine dependent fashion. This structure facilitates S/S synapsis since S¿ is proximal to E¿ and the downstream S region are co-recruited with the targeted GLT promoter to the E¿: 3'Ea complex. We propose that GLT promoter association with the E¿: 3'Ea complex creates an architectural scaffolding that promotes S/S synapsis during CSR and these interactions are dependent on the stabilizing influence of AID. Chromatin remodeling is an important regulatory mechanism controlling the accessibility of S DNA to AID. We have defined histone modifications differentially found in the S and C regions. Our studies indicate chromatin accessibility is correlated with increased histone acetylation and H3K4me3 at the S regions whereas reduced accessibility is associated with hypoAc and the H3K36me3 mark downstream of the S region. We will study the causual relationship between accessibility and these histone modifications. NARRATIVE: Humoral immunity is dependent on the expression of immunoglobulin (Ig) to fend off pathogenic challenges. The humoral immune system has evolved to produce Ig with a broad repertoire of binding specificities. We study the molecular processes by which new types of Ig are expressed.

描述（由申请人提供）：体液免疫依赖于免疫球蛋白（Ig）的表达来抵御病原体挑战。体液免疫系统已进化为产生具有广泛结合特异性的 Ig。为了实现 Ig 效应子功能和组织定位的多样性，小鼠 IgH 恒定区基因座的组织方式为：5'-V(D)J-C¿ -Cd-C?3-C?1-C?2b-C?2a-Ce-Ca-3' 涉及染色体内删除重排，该重排集中于位于每个 CH 上游的重复开关 (S) DNA 区域。 CSR 的过程可以被认为是由三个阶段组成，包括启动、S/S 突触以及 AID 诱导的 S 区 DNA 损伤启动该过程。检查导致 S/S 突触的事件，并辨别与转录和 DNA 修复相关的染色质修饰，我的实验室最近研究了位于的 5 个内含子增强子 (E¿) 之间的长程相互作用。在 VH 和 CH 基因之间以及位于 IgH 基因座 3' 端的 3'Ea 增强子以及各种 GLT 启动子中，我们发现在 B 细胞中，E¿和 3'Ea 增强子在空间上非常接近，形成独特的染色体环结构，B 细胞激活导致种系转录物 (GLT) 启动子募集到 E¿ ：3'Ea 复合物以细胞因子依赖性方式促进 S/S 突触，因为 S¿接近于 E¿下游 S 区域与目标 GLT 启动子共同招募至 E¿ ：我们建议 GLT 启动子与 E¿ 结合。 ：3'Ea 复合物创建了一个在 CSR 过程中促进 S/S 突触的结构支架，并且这些相互作用依赖于 AID 的稳定影响。染色质重塑是控制 S DNA 对 AID 的可及性的重要调节机制。我们的研究表明染色质可及性与 S 区组蛋白乙酰化和 H3K4me3 的增加相关，而可及性的降低与hypoAc 和H3K36me3 标记位于 S 区下游。 叙述：体液免疫依赖于免疫球蛋白 (Ig) 的表达来抵御致病性挑战。我们研究新型 Ig 表达的分子过程。