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RECEPTORS AND SIGNAL TRANSDUCTION

-Adrenergic receptor-stimulated apoptosis in adult cardiac myocytes involves MMP-2-mediated disruption of ₁ integrin signaling and mitochondrial pathway

¹Department of Physiology, James H. Quillen College of Medicine, James H. Quillen Veterans Affairs Medical Center, East Tennessee State University, Johnson City, Tennessee; and ²Department of Medicine, University of California San Diego School of Medicine, and Veterans Administration San Diego Healthcare System, San Diego, California

Submitted 13 May 2005 ; accepted in final form 1 September 2005

Stimulation of -adrenergic receptors (-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 -AR-stimulated apoptosis and that the apoptotic effects of MMP-2 are possibly mediated via its interaction with ₁ integrins. Herein we tested the hypothesis that MMP-2 impairs ₁ 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 -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 -AR-stimulated decreases in mitochondrial membrane potential. Overexpression of ₁ integrins using adenoviruses expressing the human _1A-integrin decreased -AR-stimulated cytochrome c release and apoptosis. Overexpression of ₁ integrins also inhibited apoptosis induced by purified active MMP-2. These data suggest that MMP-2 interferes with the ₁ integrin survival signals and activates JNK-dependent mitochondrial death pathway leading to apoptosis.

matrix metalloproteinases; focal adhesion kinase; c-Jun NH₂-terminal kinase; cytochrome c

This article has been cited by other articles:

				P. Krishnamurthy, V. Subramanian, M. Singh, and K. Singh {beta}1 Integrins Modulate {beta}-Adrenergic Receptor-Stimulated Cardiac Myocyte Apoptosis and Myocardial Remodeling Hypertension, April 1, 2007; 49(4): 865 - 872. [Abstract] [Full Text] [PDF]