title: Focal adhesion kinase facilitates platelet-derived growth factor-BB-stimulated ERK2 activation required for chemotaxis migration of vascular smooth muscle cells.
abstract: The focal adhesion (FAK) non-receptor protein-tyrosine kinase (PTK) links both extracellular matrix/integrin and growth factor stimulation to intracellular signals promoting cell migration. Here we show that both transient and stable overexpression of the FAK C-terminal domain termed FRNK (FAK-related non-kinase) inhibits serum and platelet-derived growth factor (PDGF)-BB-induced vascular smooth muscle cell (SMC) migration in wound healing and in vitro Boyden Chamber chemotaxis assays, respectively. Expression of FRNK, but not a point mutant of FRNK (FRNK L1034S), disrupted the formation of a complex containing both FAK and the activated PDGF-beta receptor and resulted in reduced tyrosine phosphorylation of endogenous FAK at the Tyr-397 binding site for Src family PTKs. As demonstrated using FAK-deficient and FAK-reconstituted fibroblasts, FAK positively contributed to PDGF-BB-stimulated ERK2/MAP kinase activity, and in SMCs, ERK2/MAP kinase activity was required for PDGF-BB-stimulated chemotaxis. Stable expression of FRNK but not FRNK L1034S expression in SMCs lowered the extent and duration of stimulated ERK2/MAP kinase activation at low but not at high PDGF-BB concentrations. Importantly, stable expression of FRNK in SMCs did not affect SMC morphology or proliferation in culture. Because the increased migration of vascular SMCs in response to extracellular matrix proteins and growth factors contributes to neointima formation, our results show that FAK inhibition by FRNK expression may provide a novel approach to regulate abnormal vascular SMC migration in vivo.
authors.affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Hauck
authors.forename: D A
authors.initials: DA
authors.lastname: Hsia
authors.forename: D D
authors.initials: DD
authors.lastname: Schlaepfer
mesh_terms: D000818:Animals; D000077214:Becaplermin; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival; D002633:Chemotaxis; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014945:Wound Healing
chemical_list: D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D019950:Mitogen-Activated Protein Kinase 1