title: Internalization of EGF receptor following lipid rafts disruption in keratinocytes is delayed and dependent on p38 MAPK activation.
abstract: The receptor for epidermal growth factor (EGF) plays an important role in epidermal keratinocytes and is known to move out of lipid raft after cholesterol depletion, leading to ligand-independent activation. Accumulation of evidence indicates the ability of EGF receptor (EGFR) to undergo internalization without participation of the ligand under the control of p38 MAPK during stress conditions. Since cholesterol depletion using methyl-beta-cyclodextrin is known to induce ligand-independent activation of EGFR in keratinocytes, we investigated by confocal microscopy and ligand-binding tests the processing and localization of EGFR following lipid raft disruption. Here, we report the dimerization and the slow internalization of the receptor accompanied by the delayed phosphorylation of tyrosine 1068 and its degradation by the proteasome. We also demonstrate the involvement of p38 MAPK during the process of internalization, which can be considered as a protective response to stress. Moreover, cholesterol-depleted keratinocytes recover their ability to proliferate during the recovery period that follows lipid raft disruption.
authors: Cell and Tissue Laboratory, URPHYM, University of Namur (FUNDP), Namur, Belgium.
authors: Sylviane
authors: S
authors: Lambert
authors: Hélène
authors: H
authors: Ameels
authors: Robert
authors: R
authors: Gniadecki
authors: Michel
authors: M
authors: Hérin
authors: Yves
authors: Y
authors: Poumay
mesh_terms: D045744:Cell Line, Tumor; D002784:Cholesterol / Q000172:deficiency; D019281:Dimerization; D004705:Endocytosis / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015603:Keratinocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D021962:Membrane Microdomains / Q000187:drug effects / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D047392:beta-Cyclodextrins; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D002784:Cholesterol; D006861:Hydrogen Peroxide; D066246:ErbB Receptors; D048051:p38 Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; C031215:betadex