Heterotrimeric G Proteins Directly Regulate MMP14/Membrane Type-1 Matrix Metalloprotease: A Novel Mechanism for GPCR-EGFR Transactivation [Cell Biology]

March 10th, 2015 by Overland, A. C., Insel, P. A.

Agonist stimulation of 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 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 GTPγS. MMP14 activation by GTPγS occurs in a concentration and time-dependent manner, does not occur with GMP or ATPγS stimulation and is not blunted by inhibitors of Src, PKC, 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 direct activation of recombinant MMP14 by purified βγ subunits. GTPγS-stimulated activation of MMP14 also results in membrane release of HB-EGF and 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.
  • Posted in Journal of Biological Chemistry, Publications
  • Comments Off on Heterotrimeric G Proteins Directly Regulate MMP14/Membrane Type-1 Matrix Metalloprotease: A Novel Mechanism for GPCR-EGFR Transactivation [Cell Biology]