1 research outputs found
Xyloglucan from Tropaeolum majus Seeds Induces Cellular Differentiation of Human Keratinocytes by Inhibition of EGFR Phosphorylation and Decreased Activity of Transcription Factor CREB
Xyloglucan
XG (molecular weight 462 kDa, 1,4-/1,4,6-(<i>p</i>Glc) linked
backbone, side chains of 1-<i>p</i>Xyl, 1,2-<i>p</i>Xyl, 1-<i>p</i>-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