Keratinocyic growth factor (KGF) belongs to the FGF family and us activity appears to be restricted to epithelial cells. It elicits its biological properties through binding to the KGFR, a splicing transcript variant of the FGFR2. The presence of multiple isoforms of FGFR2. and the overlapping specificities of ihe FGFs respect to their receptors, do not allow the use of ami-FGFR antibodies as specific immunocytochemical tools. Here we use a chimeric protein, recently obtained by fusion of KGF to the HFc portion of an immunuglobulm G. to analyse the expression and distribution of KGFR on human cultured keratinocytes. The cells were cultured in ehemically defined medium and incubated with different Ca2+ concentrations to modulate their differentiation. We observed, both at immuno fluorescence and immunoe lee iron microscopic levels, and by western blot analysis of proliferation (K6) or differentiation (Ki and ioricrin) markers, that KGFR expression is up-modulated during keratinocyte differentiation. To better quantitate this effect, we performed a cytoftuorimetric analysis, which confirmed an increased KGFR signal in keratinocytes grown in 1.5 mM Ca3+, compared to ihose grown in 0.03 mM Ca2 + . Treatment with EGF further increased KGFR expression. Parallel findings were obtained at the transcript levels, examined by an RNAase protection assay using a specific cDNA probe. Our results suggest that EGF and KGF, although are both mitogenic on human keratinocytes, may act sequentially in the proliferation /differentiation program Irom basal 10 suprabasal cells.
|Publication status||Published - 1996|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology