HYDROCORTISONE MODULATES THE EXPRESSION OF C-ETS-1 AND 72 KDA TYPE-IVCOLLAGENASE IN CHICKEN DERMIS DURING EARLY FEATHER MORPHOGENESIS

At the onset of chicken feather morphogenesis, dermal cells migrate al ong bundles of collagen fibers to colonize areas where bud outgrowth t akes place. Chicken embryos treated with hydrocortisone during the cri tical phase of dermal rearrangement show featherless skin areas in whi ch the dermis exhibits an increase of interstitial collagen. We had pr eviously demonstrated that c-ets-1 is a nuclear transcription factor e xpressed in the dermis at the beginning of feather morphogenesis. Here we study, by in situ mRNA hybridization, the expression of c-ets-1 in the dermis of chicken embryos treated with hydrocortisone. We found t hat, among the two distinct products (p54 and p68) encoded by the chic ken c-ets-1, the expression of the peg product increased while express ion of p54 decreased after hydrocortisone treatment. Since Ets-1 regul ates matrix-metalloproteinases genes, we analyzed the expression of th e 72 kDa type IV collagenase in both normal and hydrocortisone-treated embryos. We demonstrated that 72 kDa type IV collagenase mRNA express ion decreased in the dermis after hydrocortisone treatment and that it s expression correlated with that of p54(c-ets-1). Taken together, the se results indicate that hydrocortisone modulates c-ets-1 expression. In addition, they raise the interesting possibility that c-ets-1 might be involved in an altered pattern of feather development mediated by the accumulation of collagen due to a decrease in collagenase activiti es.