title: Attenuation of focal adhesion kinase signaling following depletion of agonist-sensitive pools of phosphatidylinositol 4,5-bisphosphate.
abstract: The effect of phosphoinositide depletion on focal adhesion kinase (FAK) signaling was investigated in two neuronal cell lines. Treatment of either SH-SY5Y neuroblastoma cells or PC12 cells with wortmannin, at a concentration that inhibits phosphatidylinositol 4-kinase activity, led to a selective depletion of phosphatidylinositol 4-phosphate without significantly altering phosphatidylinositol 4,5-bisphosphate (PIP2) content. An enhanced tyrosine phosphorylation of FAK elicited by agonist occupancy of phospholipase C-coupled receptors (muscarinic cholinergic in SH-SY5Y neuroblastoma or bradykinin in PC12 cells) was blocked completely by wortmannin. Under the above conditions, phosphoinositide resynthesis was prevented, and as a consequence, receptor stimulation led to a marked depletion of PIP2. In contrast, the increased tyrosine phosphorylation of FAK elicited by agents that do not activate phospholipase C (phenylarsine oxide, lysophosphatidic acid, or phorbol ester) persisted in the presence of wortmannin. However, the ability of these agents to elicit an increase in FAK phosphorylation was also prevented if PIP2 was depleted by activation of a phospholipase C-coupled receptor in the presence of wortmannin. The results suggest that agonist-sensitive pools of PIP2 must be maintained for FAK signaling to occur in response to a mechanistically diverse range of stimuli.
authors.affiliation: Department of Pharmacology and Neuroscience Laboratory, Mental Health Research Institute, University of Michigan, Ann Arbor 48104-1687, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Linseman
authors.forename: S D
authors.initials: SD
authors.lastname: Sorensen
authors.forename: S K
authors.initials: SK
authors.lastname: Fisher
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001152:Arsenicals / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism; D016716:PC12 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D019000:Phosphotyrosine / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D001152:Arsenicals; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D008246:Lysophospholipids; D009219:Myosin-Light-Chain Kinase; D019869:Phosphatidylinositol 3-Kinases; D019269:Phosphatidylinositol 4,5-Diphosphate; D000081082:Phosphoinositide-3 Kinase Inhibitors; D019000:Phosphotyrosine; D017027:Protein Tyrosine Phosphatases; D011505:Protein-Tyrosine Kinases; D011950:Receptors, Cholinergic; D013755:Tetradecanoylphorbol Acetate; D000077191:Wortmannin; C029341:oxophenylarsine; C496050:PTK2 protein, human; C496052:Ptk2 protein, rat