G-protein Regulation of the Phosphatidyl Inositol (3,4,5) Trisphosphate Signal

磷脂酰肌醇 (3,4,5) 三磷酸信号的 G 蛋白调节

• 批准号: 7335638
• 负责人: JAMES Carlton GARRISON
• 金额: $ 27.95万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7335638
• 关键词: Adenosine; Adhesions; Adrenergic Receptor; Alanine; Amino Acids; Blood Platelets; Cell Line; Cell Shape; Cell membrane; Cell physiology; Cells; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Enzymes; Event; G-Protein-Coupled Receptors; GTP-Binding Proteins; Generations; Goals; Hematopoietic; In Vitro; Knockout Mice; Laboratories; Ligands; Link; Lipids; Membrane; Molecular; Mutate; Neutrophil Activation; PH Domain; PTEN gene; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Protein Isoforms; Protein Kinase; Protein Kinase C; Proto-Oncogene Proteins c-akt; Recombinant Proteins; Regulation; Relative (related person); Research; Research Personnel; Role; Shapes; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Specificity; Transmembrane Domain; Work; cell motility; dimer; eosinophil; inositol-1,4,5-trisphosphate 5-phosphatase; insight; macrophage; mast cell; methionyl-leucyl-phenylalanine; migration; myo-inositol-1 (or 4)-monophosphatase; neutrophil; receptor; receptor coupling; research study; response; src Homology Region 2 Domain; stoichiometry

G protein coupled receptors provide both positive and negative regulation of hematopoietic cells. In cells such as neutrophils, macrophages, mast cells and platelets, the p110y isoform of phosphatidylinositol (4,5) 3-kinase (Ptdlns 3-kinase) plays a major role in cell activation, shape changes and migration via generation of phosphatidylinositol (3,4,5) trisphosphate (PIPs). This lipid is an important signal that activates the phosphatidylinositol dependent protein kinase, PDK-1, leading to phosphorylation of protein kinase B and a host of cell responses. The levels of PIP3 in the membrane of these cells are also tightly controlled by a SH2 domain containing inositol 5-phosphatase, SHIP, that is regulated by multiple mechanisms. Activation of G protein coupled receptors linked to Gi stimulates the p110y isoform of Ptdlns 3-kinase 40-60 fold by releasing specific py dimers. Activation of G protein coupled receptors linked to Gs raise cyclic AMP and can markedly inhibit the response of hematopoietic cells to stimulatory ligands. Our research has provided clear evidence of the specific isoforms of the Py dimer which activate the p110y isoform of Ptdlns 3 kinase. Recent experiments uncover the exciting result that both the p110y isoform of Ptdlns 3-kinase and SHIP can be phosphorylated by the cyclic AMP dependent protein kinase. The ability of the Py dimer to activate p101/p110y is inhibited by phosphorylation. Phosphorylation of SHIP activates the enzyme. These results provide a possible molecular explanation for the ability of cyclic AMP to inhibit the response of hematopoietic cells. The goal for this project is to determine the importance of these phosphorylation events in cell function. This goal will be approached via 2 Specific Aims. Aim-1a: To determine the effects of phosphorylation on the activity of Ptdlns 3-Kinase in vitro. Aim-1b: To understand how phosphorylation of Ptdlns 3-Kinase regulates the function of the enzyme in three cell lines. Aim-2a: To explore the effects of phosphorylation on the activity of SHIP in vitro. Aim-2b: To understand how phosphorylation of SHIP regulates its function in the intact cell. Completion of these Aims will provide considerable understanding of the molecular events regulating the levels of PIP3 in all cells and should reveal mechanisms by which G protein coupled receptors stimulate and inhibit the function of hematopoietic cells.

G蛋白偶联受体对造血细胞有正调控和负调控作用。在细胞