title: Epidermal growth factor receptor transactivation is required for mitogen-activated protein kinase activation by muscarinic acetylcholine receptors in HaCaT keratinocytes.
abstract: Non-neuronal acetylcholine plays a substantial role in the human skin by influencing adhesion, migration, proliferation and differentiation of keratinocytes. These processes are regulated by the Mitogen-Activated Protein (MAP) kinase cascade. Here we show that in HaCaT keratinocytes all five muscarinic receptor subtypes are expressed, but M1 and M3 are the subtypes involved in mitogenic signaling. Stimulation with the cholinergic agonist carbachol leads to activation of the MAP kinase extracellular signal regulated kinase, together with the protein kinase Akt. The activation is fully dependent on the transactivation of the epidermal growth factor receptor (EGFR), which even appears to be the sole pathway for the muscarinic receptors to facilitate MAP kinase activation in HaCaT cells. The transactivation pathway involves a triple-membrane-passing process, based on activation of matrix metalloproteases, and extracellular ligand release; whereas phosphatidylinositol 3-kinase, Src family kinases or protein kinase C do not appear to be involved in MAP kinase activation. Furthermore, phosphorylation, ubiquitination and endocytosis of the EGF receptor after cholinergic transactivation are different from that induced by a direct stimulation with EGF, suggesting that ligands other than EGF itself mediate the cholinergic transactivation.
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany. Wymke.Ockenga@biochemie.med.uni-giessen.de.
authors.forename: Wymke
authors.initials: W
authors.lastname: Ockenga
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany. Sina.Kuehne@biochemie.med.uni-giessen.de.
authors.forename: Sina
authors.initials: S
authors.lastname: Kühne
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany. simonebocksberger@web.de.
authors.forename: Simone
authors.initials: S
authors.lastname: Bocksberger
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany. Antje.Banning@biochemie.med.uni-giessen.de.
authors.forename: Antje
authors.initials: A
authors.lastname: Banning
authors.affiliation: Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany. Ritva.Tikkanen@biochemie.med.uni-giessen.de.
authors.forename: Ritva
authors.initials: R
authors.lastname: Tikkanen
mesh_terms: D002460:Cell Line; D004705:Endocytosis / Q000235:genetics; D004789:Enzyme Activation / Q000235:genetics; D004815:Epidermal Growth Factor / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D010766:Phosphorylation / Q000235:genetics; D011493:Protein Kinase C / Q000235:genetics; D011976:Receptors, Muscarinic / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*; D054875:Ubiquitination / Q000235:genetics; D019061:src-Family Kinases / Q000235:genetics
chemical_list: D011976:Receptors, Muscarinic; D004815:Epidermal Growth Factor; D019869:Phosphatidylinositol 3-Kinases; C512478:EGFR protein, human; D066246:ErbB Receptors; D019061:src-Family Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases