Beta-Adrenergic Receptor Stimulation Transactivates Protease-Activated Receptor 1 via MMP-13 in Cardiac Cells
Background—Chronic β-adrenergic receptor (β-AR) overstimulation, a hallmark of heart failure, is associated with increased cardiac expression of matrix metalloproteinases (MMPs). MMP-1 has been shown to cleave and activate the protease-activated receptor 1 (PAR1) in non-cardiac cells. Here, we hypothesized that β-AR stimulation would result in MMP-dependent PAR1 transactivation in cardiac cells.
Methods and Results—β-AR stimulation of neonatal rat ventricular myocytes (NRVMs) or cardiac fibroblasts (CFs) with isoproterenol (ISO) transduced with an alkaline phosphatase-tagged PAR1 elicited a significant increase in AP-PAR1 cleavage. This ISO-dependent cleavage was significantly reduced by the broad-spectrum MMP inhibitor GM6001. Importantly, specific MMP-13 inhibitors also decreased AP-PAR1 cleavage in ISO stimulated NRVMs, as well as in NRVMs stimulated with conditioned-medium from ISO-stimulated CFs. Moreover, we found that recombinant MMP-13 stimulation cleaved AP-PAR1 in NRVMs at DPRS42↓43FLLRN. This also led to the activation of ERK1/2 pathway through Gαq in NRVMs and via the Gαq/ErbBR pathways in CFs. MMP-13 elicited similar levels of ERK1/2 activation, but lower levels of inositol phosphates generation, in comparison to thrombin. Finally, we demonstrated that either PAR1 genetic ablation or pharmacological inhibition of MMP-13 prevented ISO-dependent cardiac dysfunction in mice.
Conclusions—In this study, we demonstrate that β-AR stimulation leads to MMP-13 transactivation of PAR1 in both cardiac fibroblasts and cardiomyocytes and this likely contributes to pathological activation of Gαq- and ErbB receptor-dependent pathways in the heart. We propose that this mechanism may underly the development of β-AR overstimulation-dependent cardiac dysfunction.
- receptors, adrenergic, beta
- Cardiac Fibroblast
- Protease Activated Receptor
- Received September 8, 2011.
- Accepted April 13, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited