title: β-adrenergic receptor stimulation transactivates protease-activated receptor 1 via matrix metalloproteinase 13 in cardiac cells.
abstract: 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 noncardiac cells. In the present study, we hypothesized that β-AR stimulation would result in MMP-dependent PAR1 transactivation in cardiac cells.
  
  
  RESULTS
  β-AR stimulation of neonatal rat ventricular myocytes (NRVMs) or cardiac fibroblasts with isoproterenol transduced with an alkaline phosphatase-tagged PAR1 elicited a significant increase in alkaline phosphatase-PAR1 cleavage. This isoproterenol-dependent cleavage was significantly reduced by the broad-spectrum MMP inhibitor GM6001. Importantly, specific MMP-13 inhibitors also decreased alkaline phosphatase-PAR1 cleavage in isoproterenol-stimulated NRVMs, as well as in NRVMs stimulated with conditioned medium from isoproterenol-stimulated cardiac fibroblasts. Moreover, we found that recombinant MMP-13 stimulation cleaved alkaline phosphatase-PAR1 in NRVMs at DPRS(42)↓(43)FLLRN. This also led to the activation of the ERK1/2 pathway through Gαq in NRVMs and via the Gαq/ErbB receptor pathways in cardiac fibroblasts. MMP-13 elicited similar levels of ERK1/2 activation but lower levels of generation of inositol phosphates in comparison to thrombin. Finally, we demonstrated that either PAR1 genetic ablation or pharmacological inhibition of MMP-13 prevented isoproterenol-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 that this likely contributes to pathological activation of Gαq and ErbB receptor-dependent pathways in the heart. We propose that this mechanism may underlie the development of β-AR overstimulation-dependent cardiac dysfunction.
authors.affiliation: University of Rochester School of Medicine and Dentistry, Aab Cardiovascular Research Institute, 601 Elmwood Ave, Box CVRI, Rochester, NY 14642, USA.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Jaffré
authors.forename: Alan E
authors.initials: AE
authors.lastname: Friedman
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Hu
authors.forename: Nigel
authors.initials: N
authors.lastname: Mackman
authors.forename: Burns C
authors.initials: BC
authors.lastname: Blaxall
mesh_terms: D000818:Animals; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000502:physiology; D006801:Humans; D008297:Male; D053509:Matrix Metalloproteinase 13 / Q000502:physiology*; D051379:Mice; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018739:Oncogene Proteins v-erbB / Q000502:physiology; D044463:Receptor, PAR-1 / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D015398:Signal Transduction; D015533:Transcriptional Activation
chemical_list: D018739:Oncogene Proteins v-erbB; D044463:Receptor, PAR-1; D011943:Receptors, Adrenergic, beta; D048049:Extracellular Signal-Regulated MAP Kinases; D053509:Matrix Metalloproteinase 13; D043802:GTP-Binding Protein alpha Subunits, Gq-G11