PKC? and PKC? regulate ADAM17-mediated ectodomain shedding of heparin binding-EGF through separate pathways.

ABSTRACT: Epidermal growth factor receptor (EGFR) signalling is initiated by the release of EGFR-ligands from membrane-anchored precursors, a process termed ectodomain shedding. This proteolytic event, mainly executed by A Disintegrin And Metalloproteases (ADAMs), is regulated by a number of signal transduction pathways, most notably those involving protein kinase C (PKC). However, the molecular mechanisms of PKC-dependent ectodomain shedding of EGFR-ligands, including the involvement of specific PKC isoforms and possible functional redundancy, are poorly understood. To address this issue, we employed a cell-based system of PMA-induced PKC activation coupled with shedding of heparin binding (HB)-EGF. In agreement with previous studies, we demonstrated that PMA triggers a rapid ADAM17-mediated release of HB-EGF. However, PMA-treatment also results in a protease-independent loss of cell surface HB-EGF. We identified PKC? as the key participant in the activation of ADAM17 and suggest that it acts in parallel with a pathway linking PKC? and ERK activity. While PKC? specifically regulated PMA-induced shedding, PKC? and ERK influenced both constitutive and inducible shedding by apparently affecting the level of HB-EGF on the cell surface. Together, these findings indicate the existence of multiple modes of regulation controlling EGFR-ligand availability and subsequent EGFR signal transduction.

SUBMITTER: Kveiborg M 

PROVIDER: S-EPMC3046143 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature