Molecular Mechanisms Regulating Immunoglobulin Diversification

调节免疫球蛋白多样化的分子机制

• 批准号: 10359676
• 负责人: Bao Q Vuong
• 金额: $ 39.25万
• 依托单位: CITY COLLEGE OF NEW YORK
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10359676
• 关键词: ATM activation; ATM deficient; ATM function; Acetylation; Adaptive Immune System; Affect; Affinity; Antibodies; Antibody Therapy; Antibody-mediated protection; Antigens; Autoantibodies; Autoimmune Diseases; B-Cell Activation; B-Cell Lymphomas; B-Lymphocytes; Base Excision Repairs; Binding; CRISPR/Cas technology; Cell membrane; Cells; Clone Cells; Code; Complement; Cyclic AMP-Dependent Protein Kinases; DNA; DNA Damage; DNA Repair; Data; Deoxycytidine; Development; Disease; Enzymes; Genes; Genetic Recombination; Genome Stability; Human; Hyperimmunoglobulin M Syndrome; IgE; Immune response; Immune system; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin Genes; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; Immunologic Deficiency Syndromes; Immunotherapy; Infection; Innate Immune System; Ionizing radiation; Lead; Ligation; Lupus; MSH2 gene; Malignant Neoplasms; Mammals; Mature B-Lymphocyte; Mediating; Microbe; Mismatch Repair; Modeling; Molecular; Mutation; Mutation Spectra; Natural Killer Cells; Pathogenicity; Pathway interactions; Phosphorylation; Phosphotransferases; Process; Production; Proteins; Proto-Oncogenes; Publishing; Reaction; Receptor Cell; Recruitment Activity; Research; Specificity; Surface Immunoglobulins; System; T-Lymphocyte; V(D)J Recombination; Vaccines; Viral Cancer; Virus Diseases; Work; activation-induced cytidine deaminase; amino group; antigen-specific T cells; ataxia telangiectasia mutated protein; base; congenital immunodeficiency; design; genome integrity; macrophage; microbial; recruit; response; tool; vaccine-induced antibodies

ABSTRACT In mammals, the innate and adaptive immune systems are functionally coordinated to protect them from pathogenic microbial infections. Cells of the innate immune system, such as macrophages and natural killer cells, recognize foreign molecules non-specifically and respond quickly to eliminate the microbe. In contrast, T and B cells of the adaptive immune system respond more slowly but recognize a unique molecule (or antigen) on the microbe. Antigen recognition activates and expands a T or B cell clone. The development of antigen specific T and B cells is genetically programmed through a somatic DNA recombination process called V(D)J recombination, which allows T cells to express antigen specific receptors and B cells to produce plasma membrane-bound immunoglobulins, which are more commonly known as antibodies. Antigen-activated B cells can further alter the immunoglobulin (Ig) coding genes through class switch recombination (CSR) and somatic hypermutation (SHM). CSR alters the isotype of the expressed Ig from the default IgM to IgG, IgE, or IgA through a DNA break and ligation reaction. SHM introduces untemplated mutations within the Ig variable coding regions to permit the selection of high affinity Ig. Both CSR and SHM require the activity of activation- induced cytidine deaminase (AID), an enzyme that removes the amino group on deoxycytidine bases in DNA. AID-deficiency leads to a primary immunodeficiency (Hyper-IgM syndrome) in humans and a complete block in CSR and SHM. Dysregulated AID activity generates mutations and translocations in proto-oncogenes that lead to mature B cell lymphomas. More recently, AID has been shown to regulate autoantibody production in models of lupus. Our research has shown that AID is phosphorylated directly by PKA (cAMP-dependent Protein Kinase A) and this phosphorylation promotes the interaction of AID with base excision repair proteins. In addition, our published work showed that the PKA-mediated phosphorylation of AID is dependent on the DNA break response kinase ATM (ataxia telangiectasia mutated). However, the molecular pathway that controls ATM-dependent PKA phosphorylation of AID and the subsequent formation of DNA breaks within the Ig genes that are required for CSR is unknown. This proposal seeks to identify how ATM-dependent and PKA-directed AID phosphorylation allows B cells to generate DNA breaks only in the Ig genes to generate antibody-mediated immunity. The results from this research will allow us to develop more effective vaccines and antibody-based therapies to treat diseases, such as viral infections and cancer.

摘要 在哺乳动物中，先天免疫系统和适应性免疫系统在功能上相互协调， 防止病原微生物感染。先天免疫系统的细胞，如 巨噬细胞和自然杀伤细胞，非特异性地识别外来分子， 快速清除微生物。相反，适应性免疫系统的T和B细胞 反应较慢，但识别微生物上的独特分子（或抗原）。抗原 识别激活并扩增T或B细胞克隆。抗原特异性T细胞的研究进展 而B细胞是通过一种称为“DNA重组”的体细胞DNA重组过程进行基因编程的。 V（D）J重组，其允许T细胞表达抗原特异性受体和B细胞表达抗原特异性受体， 产生质膜结合的免疫球蛋白，其通常被称为 抗体的抗原活化的B细胞可进一步改变免疫球蛋白（IG）编码基因 通过类别转换重组（CSR）和体细胞超突变（SHM）。CSR改变了 通过DNA断裂将表达的IG同种型从默认IgM变为IgG、IgE或伊加， 连接反应SHM在IG可变编码区内引入非模板突变， 允许选择高亲和力的IG。CSR和SHM都需要活化活性- 诱导胞苷脱氨酶（AID），一种去除脱氧胞苷上氨基的酶 DNA中的碱基艾滋病缺陷导致原发性免疫缺陷（高IgM综合征）， 人类以及CSR和SHM的完整模块。AID活性失调导致突变 以及导致成熟B细胞淋巴瘤的原癌基因易位。最近， 已经显示在狼疮模型中调节自身抗体的产生。我们的研究 显示AID直接被PKA（cAMP依赖性蛋白激酶A）磷酸化， 磷酸化促进AID与碱基切除修复蛋白的相互作用。此外，本发明还提供了一种方法， 我们已发表的工作表明，PKA介导的AID磷酸化依赖于 DNA断裂反应激酶ATM（共济失调毛细血管扩张突变）。然而，分子 一种控制AID的ATM依赖性PKA磷酸化和随后的 CSR所需的IG基因内DNA断裂的形成是未知的。这 一项提案试图确定ATM依赖性和PKA指导的AID磷酸化如何允许B 细胞产生DNA断裂，仅在IG基因中产生抗体介导的免疫。的 这项研究的结果将使我们能够开发出更有效的疫苗和抗体 治疗疾病的疗法，如病毒感染和癌症。