Differential Expression of TGF-beta Isoforms During Differentiation of HaCaT Human Keratinocyte Cells: Implication for the Separate Role in Epidermal Differentiation

ABSTRACT

The three mammalian isoforms of transforming growth factor-beta (TGF-beta1, beta2, beta3) are potent regulators of cell growth, differentiation, and extracellular matrix deposition. To study their role in skin differentiation, we investigated the expression of TGF-beta isoforms on cell growth and differentiation induction of the human keratinocyte cell line, HaCaT by elevating the Ca2+ concentration. An ELISA and RT-PCR assay revealed secreted TGF-beta 1 protein and TGF-beta1 mRNA were increased during calci-um-induced differentiation. In contrast, major differences were seen for TGF-beta 2 and TGF-beta 3 mRNA which were decreased during differentiation, but TGF-beta 2 and TGF-3beta protein were not evident on an ELISA. These results suggest different functions for each TGF-beta isoforms in epidermal differentiation, such that TGF-beta 1 is associ-ated with the more differentiated state, and TGF-beta 2 and TGF-beta 3 may be associ-ated the more proliferated state.