title: beta-Adrenergic receptor-stimulated apoptosis in adult cardiac myocytes involves MMP-2-mediated disruption of beta1 integrin signaling and mitochondrial pathway.
abstract: Stimulation of beta-adrenergic receptors (beta-AR) induces apoptosis in adult rat ventricular myocytes (ARVMs) via the JNK-dependent activation of mitochondrial death pathway. Recently, we have shown that inhibition of matrix metalloproteinase-2 (MMP-2) inhibits beta-AR-stimulated apoptosis and that the apoptotic effects of MMP-2 are possibly mediated via its interaction with beta1 integrins. Herein we tested the hypothesis that MMP-2 impairs beta1 integrin-mediated survival signals, such as activation of focal adhesion kinase (FAK), and activates the JNK-dependent mitochondrial death pathway. Inhibition of MMP-2 using SB3CT, a selective gelatinase inhibitor, significantly increased FAK phosphorylation (Tyr-397 and Tyr-576). TIMP-2, tissue inhibitor of MMP-2, produced a similar increase in FAK phosphorylation, whereas treatment of ARVMs with purified active MMP-2 significantly inhibited FAK phosphorylation. Inhibition of MMP-2 using SB3CT inhibited beta-AR-stimulated activation of JNKs and levels of cytosolic cytochrome c. Treatment of ARVMs with purified MMP-2 increased cytosolic cytochrome c release. Furthermore, inhibition of MMP-2 using SB3CT and TIMP-2 attenuated beta-AR-stimulated decreases in mitochondrial membrane potential. Overexpression of beta1 integrins using adenoviruses expressing the human beta1A-integrin decreased beta-AR-stimulated cytochrome c release and apoptosis. Overexpression of beta1 integrins also inhibited apoptosis induced by purified active MMP-2. These data suggest that MMP-2 interferes with the beta1 integrin survival signals and activates JNK-dependent mitochondrial death pathway leading to apoptosis.
authors.affiliation: Dept. of Physiology, James H. Quillen College of Medicine, East Tennessee State Univ., PO Box 70576, Johnson City, TN 37614, USA.
authors.forename: Bindu
authors.initials: B
authors.lastname: Menon
authors.forename: Mahipal
authors.initials: M
authors.lastname: Singh
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ross
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Johnson
authors.forename: Krishna
authors.initials: K
authors.lastname: Singh
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D045304:Cytochromes c / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D015870:Gene Expression; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D008564:Membrane Potentials / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D019012:Integrin beta1; D061965:Matrix Metalloproteinase Inhibitors; D011943:Receptors, Adrenergic, beta; D045304:Cytochromes c; D051416:Focal Adhesion Protein-Tyrosine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2