ELUCIDATION OF IMMUNOGLOBULIN CLASS SWITCH RECOMBINATION AND SOMATIC HYPERMUTATIO

免疫球蛋白类别转换重组和体细胞超突变的阐明

• 批准号: 8099602
• 负责人: Jayanta Chaudhuri
• 金额: $ 46.46万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8099602
• 关键词: Address; Affect; Affinity; Alanine; Antibodies; Antibody Formation; Antigens; B-Cell Lymphomas; B-Cell Neoplasm; B-Lymphocytes; Bacterial Infections; Binding; Binding Proteins; Biochemical; Biological Assay; Catalytic Domain; Cells; Chromatin; Complex; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cytidine; DNA; DNA Double Strand Break; DNA-Binding Proteins; Deamination; Double Strand Break Repair; Elements; Enzyme Activation; Event; Future; Generations; Genes; Genetic Recombination; Health; Holoenzymes; Human; IgE; Immune response; Immunity; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin M; Immunoglobulin Somatic Hypermutation; Immunoglobulin Switch Recombination; Immunoglobulins; Immunologic Deficiency Syndromes; In Vitro; Knock-in Mouse; Lead; Lesion; Light; Lymphomagenesis; Malignant Neoplasms; Mature B-Lymphocyte; Measures; Mediating; Modeling; Mus; Mutant Strains Mice; Mutation; Oncogenes; Patients; Phosphoproteins; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Play; Point Mutation; Post-Translational Protein Processing; Predisposition; Process; Proteins; Public Health; Reaction; Recruitment Activity; Repetitive Sequence; Reporting; Research Proposals; Role; Series; Serine; Single-Stranded DNA; Specificity; Testing; Uridine; activation-induced cytidine deaminase; antigen binding; base; cofactor; constant region gene; design; genetic regulatory protein; in vivo; insight; mutant; novel; prevent; protein activation; repaired; replication factor A; research study; stem

DESCRIPTION (provided by applicant): To mount an optimum immune response, mature B lymphocytes undergo two genetic alterations in the forms of class switch recombination (CSR) and somatic hypermutation (SHM). CSR leads to the production of antibodies of various isotypes (IgG, IgE, IgA) while SHM results in the generation of antibody molecules with a much higher affinity for antigens. The B cell specific protein AID (activation induced deaminase) is essential to both processes. AID initiates CSR and SHM by deaminating cytidines within transcribed regions of the immunoglobulin locus. These lesions are then converted into point mutations during SHM or into DNA double strand breaks that serve as obligatory intermediates during CSR. Inactivation of AID leads to human immunodeficiency syndromes (Hyper-IgM2) where patients suffer from profound susceptibility to bacterial infections. On the other hand, deregulation of AID converts it into a general mutator and leads to mutations and translocations of oncogenes that have been implicated in mature B cell lymphomagenesis. An understanding of the processes that regulate AID activity is thus of utmost importance. The overall objective of this research proposal is to elucidate the mechanism by which AID activity is regulated during CSR and SHM. Recent studies have shown that protein kinase A (PKA) phosphorylates AID in vitro to activate its ability to bind its cofactor, the single-stand DNA binding protein Replication Protein A and mediate deamination of transcribed DNA substrates. To elucidate the role of AID phosphorylation in vivo, mice with a mutation in the AID phosphorylation site will be generated and analyzed for CSR and SHM. The mutant mouse will also be used in cellular and biochemical assays to delineate the function of phosphorylated AID in CSR and SHM. Finally, existing PKA mutants will be analyzed to test the hypothesis that AID phosphorylation by PKA is itself a highly regulated event and could potentially contribute to AID target specificity. Successful completion of the projects outlined in this proposal will provide mechanistic insights into reactions central to immunity and how aberrations in such physiological reactions can cause mature B cell tumors. PUBLIC HEALTH RELEVANCE: B cell lymphomas are the most common human malignancies. It is now clear that a large majority of B cell tumors arise due to mistargeted AID activity. Experiments proposed here will elucidate the role of AID in both immunity and cancer.

描述(由申请人提供)：为了获得最佳的免疫反应，成熟的B淋巴细胞经历了两种类型的基因改变，即类开关重组(CSR)和体细胞高突变(SHM)。CSR导致产生各种同种类型的抗体(Ig G、Ig E、Ig A)，而SHM导致产生与抗原亲和力高得多的抗体分子。B细胞特异性蛋白AID(激活诱导脱氨酶)在这两个过程中都是必不可少的。AID通过使免疫球蛋白基因转录区内的胞苷脱氨来启动CSR和SHM。然后，这些损伤在SHM期间被转换为点突变，或者在CSR期间被转换为DNA双链断裂，作为必需的中间产物。AID的灭活会导致人类免疫缺陷综合征(Hyper-IgM2)，患者对细菌感染非常敏感。另一方面，解除对AID的调控将其转变为一个通用的突变子，并导致癌基因的突变和易位，这些癌基因与成熟的B细胞淋巴瘤有关。因此，了解调节艾滋病活动的过程是至关重要的。这项研究计划的总体目标是阐明在CSR和SHM过程中AID活性的调节机制。最近的研究表明，蛋白激酶A(PKA)在体外磷酸化AID，激活其结合辅因子单链DNA结合蛋白复制蛋白A的能力，并介导转录的DNA底物的脱氨基。为了阐明AID磷酸化在体内的作用，将产生AID磷酸化位点突变的小鼠，并对其进行CSR和SHM分析。突变小鼠还将用于细胞和生化分析，以描述磷酸化AID在CSR和SHM中的功能。最后，将对现有的PKA突变体进行分析，以检验PKA对AID的磷酸化本身是一个高度调控的事件，并可能有助于AID靶标特异性的假设。这项提案中概述的项目的成功完成将为免疫中心的反应以及这种生理反应中的异常如何导致成熟的B细胞肿瘤提供机械性的见解。公共卫生相关性：B细胞淋巴瘤是最常见的人类恶性肿瘤。现在很清楚的是，绝大多数B细胞肿瘤是由于错误的AID活性引起的。这里提出的实验将阐明AID在免疫和癌症中的作用。