A Fourth Outcome: DNA Damage and the Differentiation of B Cells

第四个结果：DNA 损伤和 B 细胞的分化

基本信息

批准号：
8633428
负责人：
MICHAEL A TEITELL
金额：
$ 30.54万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-04-01 至 2016-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8633428
关键词：
Adult Antibodies Antibody Formation Antigen Receptors Antigens Apoptosis Ataxia-Telangiectasia-Mutated protein kinase Automobile Driving B Cell Proliferation B cell differentiation B lymphoid malignancy B-Cell Lymphomas B-Lymphocytes BCL6 gene Binding Biochemistry Biological Models Bone Marrow CDKN1A gene CREB1 gene Cancerous Cell Aging Cell Cycle Cell Cycle Arrest Cell Differentiation process Cell Maturation Cells Complex Coupling DNA DNA Damage DNA Double Strand Break DNA Repair Data Defect Defense Mechanisms Distal Double Strand Break Repair Event Family Family member Figs - dietary Gene Expression Gene Rearrangement Generations Genes Genetic Polymorphism Genetic Programming Genome Genotoxic Stress Human Immune response Immunoglobulin Class Switching Immunoglobulin Constant Region Immunoglobulin Genes Immunoglobulin Somatic Hypermutation Immunoglobulin Switch Recombination Immunoglobulins Infectious Agent Inherited Knockout Mice Left Lesion Link Location Lymphocyte Lymphoid Lymphoid Tissue Lymphomagenesis Malignant Neoplasms Mammalian Cell Marrow Mass Spectrum Analysis Mediating Memory B-Lymphocyte Modification Molecular Mus NBS1 gene Nonhomologous DNA End Joining Oncogenes Organ Outcome PRDM1 gene Pathologic Pathway interactions Phosphoproteins Physiological Pilot Projects Plasma Cells Process Proliferating Protein Kinase Proteins Reaction Receptor Gene Repression Role STK11 gene Sampling Signal Pathway Signal Transduction Somatic Mutation Spleen Structure Structure of germinal center of lymph node System T-Lymphocyte TP53 gene Testing Therapeutic Time Tonsil Transcription Repressor/Corepressor Tumor Suppressor Proteins V(D)J Recombination activation-induced cytidine deaminase adenylate kinase cell type clinically relevant endonuclease genome-wide improved in vitro testing in vivo insight lymph nodes member novel plasma cell differentiation pre-clinical precursor cell prevent programs public health relevance recombinase repaired residence response self-renewal senescence small hairpin RNA tumor tumorigenesis tumorigenic

项目摘要

DESCRIPTION (provided by applicant): During an immune response, B cells undergo rapid proliferation and remodeling of immunoglobulin (IG) genes within germinal centers (GCs) to generate memory B and plasma cells. Unfortunately, genotoxic stress associated with the GC reaction also promotes most B cell malignancies. We recently discovered that ATM, activated by AID-dependent DNA double stranded breaks (DSBs) during IG class switch recombination (CSR) in GC B cells, signals through LKB1 to inactivate CRTC2, a known transcriptional co-activator of CREB. Using genome-wide location analysis, we determined that CRTC2 inactivation unexpectedly represses a genetic program that controls GC B cell proliferation, self-renewal, and differentiation into antibody (Ab)-secreting plasma cells while opposing lymphomagenesis. Defects in this pathway were identified in pilot studies of human B cell lymphoma samples by ATM or LKB1 repression or by a recently identified somatic mutation or genetic polymorphism in CRTC2. These pathway alterations are predicted to result in increased GC B cell proliferation and impaired plasma cell differentiation, which will be tested here in vitro and in vivo. Our data show a new outcome for the DNA damage response (DDR) using B lymphocytes as the model system. It is known that DNA damage activates a cellular DDR, which determines 3 main cell fates: 1) transient cell cycle arrest with DNA repair and cycle reentry, 2) permanent exit from the cell cycle (senescence), or 3) apoptosis. Here, we propose to define key molecular determinants and the significance of an unexpected fourth outcome for DNA damage, which is to drive precursor cell maturation, in this case from a GC B cell to an Ab-secreting plasma cell. In a sense, this new outcome is a form of cell senescence, in that a cell with potentially tumorigenic DNA damage is forced out of a rapidly dividing precursor pool to protect the host from cancer. However, this fourth DDR option differs significantly from senescence by coupling with differentiation, which leads to an essential new function, Ab production against infectious agents. The pathway we identified is DSB-initiated ATM->LKB1->"X"->"Y"/CRTC2-> target gene expression that controls the transition from a GC B cell to a plasma cell. In Aim 1, we will identify ~85 kDa LKB1 direct target phosphoprotein "X" by candidate elimination from the 14 member AMPK family and/or by biochemistry- mass spectrometry analysis, followed by shRNA and over-expression studies in a unique human GC B cell differentiation system. In Aim 2, we will identify CREB-independent CRTC2-interacting "Y" factor(s) that control a gene program that mediates DSB-induced differentiation into plasma cells. These two identification and function aims are essential to complete this novel signaling pathway and to link with Aim 3 studies. In Aim 3, we provide pre-clinical and clinical relevance by analysis of a unique LKB1 B-lineage knockout (KO) mouse and we determine whether pathway defects in human GC B cell lymphomas result from inherited or somatic alterations. Overall, we dissect a new and unexpected fourth outcome for DNA damage- cell differentiation.

描述（由申请人提供）：在免疫反应期间，B细胞经历生发中心（GC）内免疫球蛋白（IG）基因的快速增殖和重塑，以产生记忆B和血浆细胞。不幸的是，与GC反应相关的遗传毒性应激也促进了大多数B细胞恶性肿瘤。我们最近发现，在GC B细胞中IG类开关重组（CSR）期间，ATM通过辅助依赖性的DNA双链断裂（DSB）激活，通过LKB1信号，以使CRTC2（一种已知的转录共激活剂）通过LKB1发出信号。使用全基因组的位置分析，我们确定CRTC2灭活意外地压制了一个控制GC B细胞增殖，自我更新和分化为抗体（AB）分解血浆细胞的遗传程序。通过ATM或LKB1抑制或最近发现的CRTC2中的体细胞突变或遗传多态性，在人类B细胞淋巴瘤样品的试验研究中发现了该途径中的缺陷。预测这些途径改变会导致GC B细胞增殖增加和浆细胞分化受损，这将在这里在体外和体内进行测试。我们的数据显示了使用B淋巴细胞作为模型系统的DNA损伤反应（DDR）的新结果。众所周知，DNA损伤激活了一个细胞DDR，该细胞DDR决定了3个主要细胞命运：1）用DNA修复和循环再入的瞬时细胞周期停滞，2）2）永久退出细胞周期（衰老），或3）凋亡。在这里，我们建议定义关键分子决定因素，并在从GC B细胞到分泌AB分泌的浆细胞的DNA损伤的意外第四结果对DNA损伤的重要性。从某种意义上说，这种新结果是一种细胞衰老的一种形式，因为具有潜在的肿瘤DNA损伤的细胞被迫退出快速分裂的前体库以保护宿主免受癌症的侵害。但是，这第四个DDR选项与通过分化结合而与衰老有显着不同，这导致了基本的新功能，AB的产生对传染剂。我们确定的途径是DSB引起的ATM-> LKB1->“ X” - >“ Y”/CRTC2->靶基因表达，该途径控制从GC B细胞到血浆细胞的过渡。在AIM 1中，我们将通过14个成员AMPK家族和/或通过生物化学 - 质谱分析来确定〜85 kDa LKB1直接靶磷蛋白“ X”，然后在独特的人类GC B中进行SHRNA和过表达研究。细胞分化系统。在AIM 2中，我们将确定与CREB无关的CRTC2相互作用“ Y”因子，该因子控制一个基因程序，该基因程序介导DSB诱导的分化为浆细胞。这两个识别和功能目的对于完成这一新型信号通路并与AIM 3研究联系至关重要。在AIM 3中，我们通过分析独特的LKB1 B-Linege敲除（KO）小鼠提供临床前和临床相关性，并确定人GC B细胞淋巴瘤中的途径缺陷是由遗传性改变还是躯体变化引起的。总体而言，我们剖析了DNA损伤细胞分化的新的和意外的第四个结果。