Regulation of adenylyl cyclase VII and its function in the immune system

腺苷酸环化酶 VII 的调节及其在免疫系统中的功能

• 批准号: 8053816
• 负责人: Li Jiang
• 金额: $ 31.54万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8053816
• 关键词: Adenylate Cyclase; Affect; B-Lymphocytes; Binding; Biochemical; Biological Assay; Birth; Bone Marrow; Cardiac; Cell Line; Cells; Chemotaxis; Co-Immunoprecipitations; Coupling; Cyclic AMP; Defect; Development; Drug Delivery Systems; Embryonic Development; Ensure; Enzymes; Functional disorder; Future; G-Protein-Coupled Receptors; G12 Protein; G13 Protein; GTP-Binding Proteins; Generations; Goals; Hematopoietic; Hybrids; Immune; Immune System Diseases; Immune response; Immune system; In Vitro; Knock-out; Knowledge; Link; Lung; Maps; Mediating; Mediator of activation protein; Membrane; Mental Depression; Molecular; Mus; Nature; Pathway interactions; Pharmaceutical Preparations; Phenotype; Physiological; Physiological Processes; Physiology; Play; Protein Isoforms; Protein Kinase C; Proteins; RNA Interference; Regulation; Regulatory Pathway; Role; Second Messenger Systems; Series; Signal Pathway; Signal Transduction; Symptoms; System; T-Cell Activation; Therapeutic Intervention; Tissues; Transplantation; Wild Type Mouse; Yeasts; addiction; adenylyl cyclase 7; base; cell type; combat; cytokine; design; immune function; in vitro Assay; in vivo; insight; macrophage; mutant; novel; protein protein interaction; public health relevance; reconstitution; response; scaffold; second messenger; success

DESCRIPTION (provided by applicant): The ubiquitous second messenger, cAMP, is an important modulator for the development of the immune system and for various immune responses. Its effects range from development of hematopoietic lineages to B cell and T cell activation, cytokine generation, and chemotaxis. To ensure the proper function of this second messenger it is regulated by numerous signaling pathways at multiple levels. Intracellular cAMP is synthesized by membrane-bound adenylyl cyclases (ACs) upon activation of the heterotrimeric G1s protein. There are nine membrane-bound ACs, each of which is distinctively regulated by a variety of pathways including Gi, G23, Ca2+, and protein kinase C. Thus the ACs can serve as key integrators for inputs from multiple pathways. Despite the crucial functions of cAMP in the immune system, its regulation is not well understood. We have recently discovered a novel pathway that regulates cAMP responses in several cell lines including primary macrophages derived from bone marrows. In these cells, activation of the G113 pathway by distinct G protein coupled receptors synergistically enhances Gs-activated synthesis of cAMP. This synergistic interaction converges on a specific isoform of adenylyl cyclase (AC), AC7, which is highly expressed in the immune system. This is the first demonstration that the G12/G13 subclass of G proteins can regulate cAMP responses and of a specific function for AC7. We also found that deficiency of AC7 in the immune system results in compromised immune responses, suggesting an important role of this AC isoform in the immune functions. We propose to determine the molecular mechanisms of AC7 regulation and to elucidate its physiological functions in the immune system. Three specific aims are proposed to achieve these goals. 1. We will dissect the molecular mechanisms of the interactions between the G12/13 pathway and AC7 using a variety of biochemical approaches. We will determine the requirements for this synergistic interaction to occur and the mechanism that turns off this transient interaction. 2. We will identify novel proteins involved in the regulation of AC7 activity by the G12/13 pathway using a combination of protein-protein interaction assays and an RNAi screen. 3. We will identify the defects in chimeric mice with AC7 deficient immune systems, define the causes of the defects in specific cell types, and ascertain the signaling pathways involved. We will also generate a conditional knockout strain of AC7 to use it for more advanced studies of AC7 functions in immune responses and eventual elucidation of the role of this cyclase in other tissues and cell types. Results from this study will help us better understand the regulation of cAMP and its physiological role in the immune system. Knowledge gained through elucidation of these novel pathways and regulatory paradigms will help identify selective drug targets for combating immune diseases. PUBLIC HEALTH RELEVANCE: Multiple drugs have been developed based on their abilities to modulate cAMP and they have successfully alleviated symptoms of several abnormal conditions, including selected cardiac conditions, pulmonary dysfunction, addiction, depression, and immune functions. This application will elucidate the mechanisms for a novel regulation of cAMP in immune cells and determine how this regulation affects immune functions in mice. Results from these studies will help identify novel targets for selective therapeutic intervention in immune diseases.

描述（由申请人提供）：普遍存在的第二信使cAMP是免疫系统发育和各种免疫应答的重要调节剂。其作用范围从造血谱系发育到B细胞和T细胞活化、细胞因子产生和趋化性。为了确保第二信使的正常功能，它受到多个水平的众多信号通路的调节。细胞内cAMP由膜结合腺苷酸环化酶（AC）在异源三聚体G1 s蛋白激活后合成。存在九种膜结合AC，其中每一种由多种途径（包括Gi、G23、Ca 2+和蛋白激酶C）独特地调节。因此，AC可以作为来自多个途径的输入的关键集成器。尽管cAMP在免疫系统中具有重要功能，但其调节作用尚不清楚。我们最近发现了一种新的途径，调节cAMP的反应，在几个细胞系，包括原代巨噬细胞来源于骨髓。在这些细胞中，不同的G蛋白偶联受体对G113通路的激活协同增强了GS激活的cAMP合成。这种协同相互作用集中在腺苷酸环化酶（AC）的特定同种型AC 7上，其在免疫系统中高度表达。这是第一次证明G蛋白的G12/G13亚类可以调节cAMP反应和AC 7的特异性功能。我们还发现，免疫系统中AC 7的缺乏导致免疫应答受损，表明该AC同种型在免疫功能中的重要作用。我们建议确定AC 7调节的分子机制，并阐明其在免疫系统中的生理功能。为实现这些目标，提出了三个具体目标。1.我们将使用各种生物化学方法来剖析G12/13通路和AC 7之间相互作用的分子机制。我们将确定这种协同相互作用发生的要求和关闭这种瞬时相互作用的机制。2.我们将使用蛋白质-蛋白质相互作用测定和RNAi筛选的组合来鉴定通过G12/13途径参与AC 7活性调节的新型蛋白质。3.我们将鉴定具有AC 7缺陷免疫系统的嵌合小鼠的缺陷，确定特定细胞类型缺陷的原因，并确定所涉及的信号通路。我们还将产生AC 7的条件性敲除菌株，以将其用于AC 7在免疫应答中的功能的更高级研究，并最终阐明这种环化酶在其他组织和细胞类型中的作用。这项研究的结果将有助于我们更好地了解cAMP的调节及其在免疫系统中的生理作用。通过阐明这些新的途径和调控模式获得的知识将有助于确定用于对抗免疫疾病的选择性药物靶点。 公共卫生关系：基于其调节cAMP的能力，已经开发了多种药物，并且它们已经成功地减轻了几种异常状况的症状，包括选定的心脏状况、肺功能障碍、成瘾、抑郁和免疫功能。本申请将阐明免疫细胞中cAMP的新调节机制，并确定这种调节如何影响小鼠的免疫功能。这些研究的结果将有助于确定免疫疾病选择性治疗干预的新靶点。