TY - JOUR

T1 - PKCa and PKCd regulate ADAM17-mediated ectodomain shedding of heparin binding-EGF through separate pathways

AU - Kveiborg, Marie

AU - Instrell, Rachael

AU - Rowlands, Christina

AU - Howell, Michael

AU - Parker, Peter J

PY - 2011

Y1 - 2011

N2 - 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 PKCa as the key participant in the activation of ADAM17 and suggest that it acts in parallel with a pathway linking PKCd and ERK activity. While PKCa specifically regulated PMA-induced shedding, PKCd 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.

AB - 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 PKCa as the key participant in the activation of ADAM17 and suggest that it acts in parallel with a pathway linking PKCd and ERK activity. While PKCa specifically regulated PMA-induced shedding, PKCd 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.

U2 - 10.1371/journal.pone.0017168

DO - 10.1371/journal.pone.0017168

M3 - Journal article

C2 - 21386996

VL - 6

SP - e17168

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 2

ER -