title: Integrin activation and focal complex formation in cardiac hypertrophy.
abstract: Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.
authors.affiliation: Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina and the Ralph H. Johnson Department of Veterans Affairs MedicalCenter, Charleston 29425-2221, USA.
authors.forename: M
authors.initials: M
authors.lastname: Laser
authors.forename: C D
authors.initials: CD
authors.lastname: Willey
authors.forename: W
authors.initials: W
authors.lastname: Jiang
authors.forename: G
authors.initials: G
authors.lastname: Cooper
authors.forename: D R
authors.initials: DR
authors.lastname: Menick
authors.forename: M R
authors.initials: MR
authors.lastname: Zile
authors.forename: D
authors.initials: D
authors.lastname: Kuppuswamy
mesh_terms: D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D015153:Blotting, Western; D006332:Cardiomegaly / Q000378:metabolism*; D002415:Cats; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation; D005109:Extracellular Matrix / Q000473:pathology; D005353:Fibronectins / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases; D016023:Integrins / Q000378:metabolism* / Q000502:physiology*; D007797:Laminin / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D015513:Oncogene Proteins / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry; D019096:Vitronectin / Q000378:metabolism
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D005353:Fibronectins; D016023:Integrins; D007797:Laminin; C078332:Nck protein; D015513:Oncogene Proteins; D010455:Peptides; D011506:Proteins; D055765:Shc Signaling Adaptor Proteins; D019096:Vitronectin; D014443:Tyrosine; D003094:Collagen; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases