CATABOLISM OF INTACT FIBRILLIN MICROFIBRILS BY NEUTROPHIL ELASTASE, CHYMOTRYPSIN AND TRYPSIN

We present ultrastructural and biochemical evidence for the turnover o f intact fibrillin microfibrils by the serine proteinases, neutrophil elastase, chymotrypsin and trypsin. Rotary shadowing electron microsco py revealed that serine proteinase treatment of intact microfibrils is olated from foetal bovine skin resulted in extensive degradation. Micr ofibrils were destroyed by neutrophil elastase and effectively disrupt ed by chymotrypsin and trypsin, with no morphologically identifiable a rrays remaining. Evidence of defined fibrillin degradation products wa s obtained by Western blotting of these enzyme-treated fibrillin assem blies. Fibrillin immunoprecipitated from dermal fibroblast culture med ium was also comprehensively degraded by these enzymes. These observat ions demonstrate that serine proteinases are potent effecters for the physiological and pathological catabolism of microfibrils, and suggest a key role in elastic fibre degradation.