INDUCTION AND ACTIVATION OF PROCOLLAGENASE IN RABBIT SYNOVIAL FIBROBLASTS AFTER TREATMENT WITH ACTIVE OXYGEN RELEASED BY XANTHINE XANTHINE-OXIDASE

Treatment of rabbit synovial fibroblasts with active oxygen (AO) relea sed by xanthine/xanthine oxidase resulted in an induction of procollag enase in these cells in concentrations ranging from 12.5 mu g/ml xanth ine plus 0.0025 U/ml xanthine oxidase to 50 mu g/ml xanthine plus 0.01 U/ml xanthine oxidase. Preceding this there was an accumulation of po ly(ADP-ribose) for the same concentration range of xanthine/xanthine o xidase. Furthermore, it was found that AO caused activation of the lat ent procollagenase to the active enzyme in concentrations ranging from 0.1 mu g/ml xanthine plus 0.00002 U/ml xanthine oxidase to 1 mu g/ml xanthine plus 0.0002 U/ml xanthine oxidase. It is suggested that poly( ADP-ribosyl)ation participates in the induction of procollagenase by r elaxing chromatin. Furthermore, it is proposed that AO activates laten t procollagenase under physiological conditions.