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The three mammalian isoforms of transforming growth factorβ(TGFβ1, β2, β3) are potent regulators of cell growth, differentiation, and extracellular matrix deposition. To study their role in skin differentiation, we investigated the expression of TGF-β isoforms on cell growth and differentiation induction of the human keratinocyte cell line, HaCaT by elevating the Ca(2+) concentration. An ELISA and RT-PCR assay revealed secreted TGF-β 1 protein and TGF-β 1 mRNA were increased during calcium-induced differentiation. In contrast, major differences were seen for TGF-β 2 and TGF-β 3 mRNA which were decreased during differentiation, but TGF-β 2 and TGF-β3 protein were not evident on an ELISA. These results suggest different functions for each TGF-β isoforms in epidermal differentiation, such that TGF-β 1 is associated with the more differentiated state, and TGF-β 2 and TGF-β 3 may be associated the more proliferated state.
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