Mechanisms of Adhesion GPCR Action

粘附 GPCR 作用机制

• 批准号: 10569532
• 负责人: Gregory Gordon Tall
• 金额: $ 36.66万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10569532
• 关键词: ADGR1 gene; Adherence; Adhesions; Adhesives; Agonist; Anabolism; Animal Model; Anticoagulants; Binding; Binding Sites; Biochemical; Biological Assay; Biotinylation; Blood; Blood Coagulation Disorders; Blood Platelets; Blood Vessels; Blood coagulation; Blood flow; Brain; C-terminal; Cell membrane; Cells; Coagulation Process; Collagen; Collagen Receptors; Complex; Coupled; Data; Defect; Dependence; Dissociation; Engineering; Event; Exposure to; Extracellular Matrix; G-Protein-Coupled Receptors; GTP-Binding Proteins; Hemorrhage; Hemostatic function; Human; Immobilization; In Vitro; Injury; Knockout Mice; Knowledge; Ligands; Mass Spectrum Analysis; Measures; Mediating; Modeling; Molecular; Mus; Mutagenesis; N-terminal; Peptides; Physiological; Physiology; Platelet Activation; Proteolysis; Receptor Activation; Role; Series; Shapes; Signal Transduction; Signaling Protein; Site; Surface; Testing; Theoretical model; Thrombosis; Thrombus; Tissues; Transmembrane Domain; Tube; Ultraviolet Rays; Whole Blood; Work; antagonist; cell motility; crosslink; experience; experimental study; extracellular; follow-up; high throughput screening; in vitro activity; in vivo; member; mimetics; mouse model; pharmacologic; programs; protease-activated receptor 4; protein reconstitution; receptor; response; small molecule libraries; tool; transmission process; vascular injury; wound; wound healing

Summary/Abstract: GPR56/ADGRG1 is a deorphanized brain Adhesion G protein Coupled Receptor (AGPCR) with a physiological ligand, collagen. We present new evidence that GPR56 is present on the surface of human and mouse platelets. This is very intriguing considering that autonomous platelet activation that leads to clot formation is mediated by platelet interactions with collagen that becomes exposed at sites of vessel injury. We found that pharmacological activation of platelet GPR56 is sufficient to elicit the physiological platelet activation program required for wound healing (hemostasis) and blood clotting (thrombosis). Moreover, Gpr56 knockout mice have a severe bleeding disorder and dramatic defects in clot formation in mouse vessel wall injury models. We hypothesize that GPR56 is the platelet collagen receptor that mediates the initial G protein 12/13-dependent platelet shape changes while platelets roll/translocate along exposed collagen to their site of stable adhesion at the lagging edges of blood vessel wounds. We will investigate platelet GPR56-mediated G protein signaling, platelet shape changes, in vitro platelet activation, and the role of GPR56 in mouse models of hemostasis and thrombosis. We found compelling preliminary evidence that platelets from Gpr56 knockout mice are dramatically defective in adhering to an immobilized collagen surface when mouse blood is flowed over the surface at high shear force. We propose that GPR56 is not directly involved in stable platelet adhesion, but as platelets tumble across the collagen surface, GPR56 is stimulated to cause the shape changes that allow platelets to then stably adhere via distinct non-GPCR collagen receptors. Before discovering GPR56 on platelets we proposed a general model of AGPCR activation that required anchoring of the receptor N-termini, and shear force-mediated receptor dissociation that leads to exposure of the AGPCR tethered agonists to induce G protein signaling. The conditions experienced by platelet-borne GPR56 align remarkably well with this theoretical model. Our work also includes conducting biochemical studies using newly developed photo-crosslinking agonist probes to define the agonist binding sites of the related AGPCRs, GPR56 and GPR114.

摘要/摘要：GPR56/ADGRG1是一个去孤儿脑粘附G蛋白偶联受体（AGPCR）。