CONSTITUTIVE SYNTHESIS OF A 92-KDA KERATINOCYTE-DERIVED TYPE-IV COLLAGENASE IS ENHANCED BY TYPE-I COLLAGEN AND DECREASED BY TYPE-IV COLLAGEN MATRICES

Human keratinocytes synthesize interstitial collagenase, a 72-kDa gelatinase, and a recently described 92-kDa gelatinase/type IV collagenase. We examined the synthesis of this novel enzyme by basal keratinocytes apposed to plastic, basement membrane collagen (type IV), and interstitial dermal collagen (type I). Samples of conditioned medium were electrophoresed on a 10% polyacrylamide, gelatin-ladened zymogram. Protein bands with gelatin-cleaving properties were identified by clarification of the gel and quantified by densitometry. A 92-kDa band had marked gelatinolytic activity and increased in culture over 72 h. The identification of this 92-kDa band as type IV collagenase was demonstrated by Western immunoblotting using monospecific antibody to the 92-kDa type IV collagenase. Keratinocytes apposed to type I collagen exhibited a threefold increase in the synthesis of the 92-kDa enzyme compared to cultures apposed to type IV collagen and a 1.5-times increase compared to plastic. The specificity of this enhancement was shown by constant levels of other proteins (e.g., the 72-kDa gelatinase). This study denonstrates that cell-matrix interactions modulate the synthesis of a recently described, keratinocyte-derived, 92-kDa gelatinase and that specific collagen types (I versus IV) have opposite effects upon the synthesis of this enzyme.