title: Xyloglucan from Tropaeolum majus Seeds Induces Cellular Differentiation of Human Keratinocytes by Inhibition of EGFR Phosphorylation and Decreased Activity of Transcription Factor CREB.
abstract: Xyloglucan XG (molecular weight 462 kDa, 1,4-/1,4,6-(pGlc) linked backbone, side chains of 1-pXyl, 1,2-pXyl, 1-p-Gal) was isolated from the seeds of Tropaeolum majus. XG (100 μg/mL) induced terminal cellular differentiation of human keratinocytes, as demonstrated by immunofluorescence staining and Western blot using cytokeratin 10 and involucrin as marker proteins. Differentiation was also induced by XG-derived oligosaccharides (degree of polymerization 7-9). Quantitative real-time polymerase chain reaction (qPCR) revealed the induction of gene expression of typical differentiation markers (cytokeratin, filaggrin, involucrin, loricrin, transglutaminase) in a time-dependent manner. Whole human genome microarray indicated that most of upregulated genes were related to differentiation processes. Microarray findings on selected genes were subsequently confirmed by qPCR. For identification of the molecular target of xyloglucan PAGE of keratinocyte membrane preparations was performed, followed by blotting with fluorescein isothiocyanate-labeled XG. XG interacting proteins were characterized by MS. Peptide fragments of epidermal growth factor receptor (EGFR) and integrin β4 were identified. Subsequent phospho-kinase array indicated that phosphorylation of EGFR and transcription factor cAMP response element-binding protein (CREB) was decreased in the XG-treated cells. Thus, the XG-induced differentiation of keratinocytes is proposed to be mediated by the inhibition of the phosphorylation of EGFR, leading to a dimished CREB activation, which is essential for the activation of cellular differentiation.
authors.affiliation: ‡University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, Corrensstrasse 48, D-48149 Münster, Germany.
authors.forename: Dominika M
authors.initials: DM
authors.lastname: Zacharski
authors.affiliation: ‡University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, Corrensstrasse 48, D-48149 Münster, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Brandt
authors.affiliation: ‡University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, Corrensstrasse 48, D-48149 Münster, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Esch
authors.affiliation: §University of Münster, Interdisciplinary Centre for Clinical Research, Core Unit Proteomics, Röntgenstr. 21, D-48149 Münster, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: König
authors.affiliation: #University of Münster, Institute for Hygiene, Robert-Koch-Strasse 41, D-48149 Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Mormann
authors.affiliation: ∥University Clinic Centre Bonn, Medical Clinic III, Centre for Internal Medicine, Sigmund-Freud-Str. 25, D-53127 Bonn, Germany.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Ulrich-Merzenich
authors.affiliation: ‡University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, Corrensstrasse 48, D-48149 Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hensel
mesh_terms: D002454:Cell Differentiation; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D000091344:Filaggrin Proteins; D005786:Gene Expression Regulation / Q000187:drug effects; D005936:Glucans / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012639:Seeds / Q000737:chemistry; D032388:Tropaeolum / Q000737:chemistry*; D014990:Xylans / Q000494:pharmacology*
chemical_list: C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D005936:Glucans; D014990:Xylans; C029353:xyloglucan; C512478:EGFR protein, human; D066246:ErbB Receptors