title: Heterotrimeric G proteins directly regulate MMP14/membrane type-1 matrix metalloprotease: a novel mechanism for GPCR-EGFR transactivation.
abstract: Agonist stimulation of G protein-coupled receptors (GPCRs) can transactivate epidermal growth factor receptors (EGFRs), but the precise mechanisms for this transactivation have not been defined. Key to this process is the protease-mediated "shedding" of membrane-tethered ligands, which then activate EGFRs. The specific proteases and the events involved in GPCR-EGFR transactivation are not fully understood. We have tested the hypothesis that transactivation can occur by a membrane-delimited process: direct increase in the activity of membrane type-1 matrix metalloprotease (MMP14, MT1-MMP) by heterotrimeric G proteins, and in turn, the generation of heparin-binding epidermal growth factor (HB-EGF) and activation of EGFR. Using membranes prepared from adult rat cardiac myocytes and fibroblasts, we found that MMP14 activity is increased by angiotensin II, phenylephrine, GTP, and guanosine 5'-O-[γ-thio]triphosphate (GTPγS). MMP14 activation by GTPγS occurs in a concentration- and time-dependent manner, does not occur in response to GMP or adenosine 5'-[γ-thio]triphosphate (ATPγS), and is not blunted by inhibitors of Src, PKC, phospholipase C (PLC), PI3K, or soluble MMPs. This activation is specific to MMP14 as it is inhibited by a specific MMP14 peptide inhibitor and siRNA knockdown. MMP14 activation by GTPγS is pertussis toxin-sensitive. A role for heterotrimeric G protein βγ subunits was shown by using the Gβγ inhibitor gallein and the direct activation of recombinant MMP14 by purified βγ subunits. GTPγS-stimulated activation of MMP14 also results in membrane release of HB-EGF and the activation of EGFR. These results define a previously unrecognized, membrane-delimited mechanism for EGFR transactivation via direct G protein activation of MMP14 and identify MMP14 as a heterotrimeric G protein-regulated effector.
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Overland
authors.affiliation: From the Departments of Pharmacology and Medicine, University of California at San Diego, La Jolla, California 92093 pinsel@ucsd.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Insel
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D066257:Heparin-binding EGF-like Growth Factor / Q000378:metabolism*; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D041681:NIH 3T3 Cells; D037342:Pertussis Toxin / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D061251:Primary Cell Culture; D055503:Protein Multimerization; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D015533:Transcriptional Activation; D014966:Xanthenes / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D066257:Heparin-binding EGF-like Growth Factor; D034741:RNA, Small Interfering; D014966:Xanthenes; D000804:Angiotensin II; D010656:Phenylephrine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; C007820:gallein; D037342:Pertussis Toxin; C483803:Egfr protein, rat; D066246:ErbB Receptors; D053511:Matrix Metalloproteinase 14
keywords: Epidermal Growth Factor Receptor (EGFR); G Protein-coupled Receptor (GPCR); Matrix Metalloproteinase (MMP); Membrane Protein; Signal Transduction