Suppression of keratin 15 expression by transforming growth factor beta in vitro and by cutaneous injury in vivo.

Transforming growth factor beta (TGF-beta) is a multifunctional cytokine which plays an important role in cutaneous wound repair. To gain insight into the mechanisms of action of this growth and differentiation factor in the skin, we searched for genes which are regulated by TGF-beta1 in cultured HaCaT keratinocytes. Using the differential display RT-PCR technology we identified a gene which was strongly downregulated by TGF-beta1. The identified cDNA includes sequences of the keratin 15 (K15) gene which encodes a component of the cytoskeleton of basal cells in stratified epithelia. Surprisingly, our cDNA also included an unknown sequence. Since this cDNA lacks an open reading frame, the corresponding mRNA is likely to be nonfunctional. However, we also demonstrate a strong negative regulation of the expression of the published, functional K15 variant. Expression of K15 was also suppressed by tumor necrosis factor alpha (TNF-alpha) and to a lesser extent by epidermal growth factor (EGF) and keratinocyte growth factor (KGF). By contrast, the major basal type I keratin, K14, was upregulated by TGF-beta1, whereas TNF-alpha, EGF, and KGF had no effect. Consistent with the in vitro data, we found a significant reduction of the K15 mRNA levels after skin injury, whereas K14 expression increased during the wound healing process. Immunostaining revealed the presence of K15 in all basal cells of the epidermis adjacent to the wound, but not in the hyperproliferative epithelium above the granulation tissue. These data demonstrate that K15 is excluded from the activated keratinocytes of the hyperthickened wound epidermis, possibly as a result of increased growth factor expression in injured skin.

Werner S ，Munz B 《EXPERIMENTAL CELL RESEARCH》

Caveolin-1 and -2 expression is differentially regulated in cultured keratinocytes and within the regenerating epidermis of cutaneous wounds.

Gassmann MG ，Werner S 《EXPERIMENTAL CELL RESEARCH》

The Mad1 transcription factor is a novel target of activin and TGF-beta action in keratinocytes: possible role of Mad1 in wound repair and psoriasis.

Werner S ，Beer HD ，Mauch C ，Lüscher B ，Werner S ... -  《ONCOGENE》

Growth factor-regulated expression of enzymes involved in nucleotide biosynthesis: a novel mechanism of growth factor action.

Gassmann MG ，Stanzel A ，Werner S 《ONCOGENE》

Epidermal growth factor receptor ligands regulate keratin 8 expression in keratinocytes, and transforming growth factor alpha mediates the induction of keratin 8 by the v-rasHa oncogene.

Cheng C ，Tennenbaum T ，Dempsey PJ ，Coffey RJ ，Yuspa SH ，Dlugosz AA ... -  《-》