UNCOORDINATE EXPRESSIONS OF TYPE-I AND TYPE-III COLLAGENS, COLLAGENASE AND TISSUE INHIBITOR OF MATRIX METALLOPROTEINASE-1 ALONG IN-VITRO PROLIFERATIVE LIFE-SPAN OF HUMAN SKIN FIBROBLASTS - REGULATION BY ALL-TRANS-RETINOIC ACID

In vitro human skin fibroblasts aging was characterized by a continuou s increase of collagenase mRNA levels. On the contrary, TIMP-1 mRNA le vel decreased only at late passages (> 65 % of proliferative life span ). Type I and III mRNA levels showed a high variability depending on c ell strains studied. However, type I and III collagen expressions vari ed parallely. All-trans retinoic acid (RA) decreased collagenase expre ssion and stimulated TIMP-1 expression. Under RA action, high variabil ity in mRNAs levels encoding type I and III collagens was observed wit h HSF passages. However, RA tended to correct variations in collagens expressions observed along HSF life span.