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) released by xanthine/xanthine oxidase resulted in an induction of procollagenase in these cells in concentrations ranging from 12.5 micrograms/ml xanthine plus 0.0025 U/ml xanthine oxidase to 50 micrograms/ml xanthine plus 0.01 U/ml xanthine oxidase. Preceding this there was an accumulation of poly(ADP-ribose) for the same concentration range of xanthine/xanthine oxidase. Furthermore, it was found that AO caused activation of the latent procollagenase to the active enzyme in concentrations ranging from 0.1 micrograms/ml xanthine plus 0.00002 U/ml xanthine oxidase to 1 microgram/ml xanthine plus 0.0002 U/ml xanthine oxidase. It is suggested that poly(ADP-ribosyl)ation participates in the induction of procollagenase by relaxing chromatin. Furthermore, it is proposed that AO activates latent procollagenase under physiological conditions.