Altered expression of tissue-type plasminogen activator and type 1 inhibitor in astrocytes of mouse cortex following scratch injury in culture

The expression of plasminogen and plasminogen activators (PG/PAs) in reacti ve astrocytes was examined following scratch injury. In response to injury, casein-degrading activity could be observed around astrocytes. The protein expression of tissue-type plasminogen activator (tPA) was up-regulated, wh ile the free form of urokinase-type plasminogen activator (uPA) was not det ected. Consistent with these findings, results obtained with zymograph assa y also revealed that tPA activity, but not uPA activity, was up-regulated. Moreover, the addition of 6-amino-caproitic acid (EACA) to casein-covered a strocytes significantly prevented the recovery of the injured astrocytes in a dose-dependent manner. Taken together, our data demonstrate that the exp ression of PG/PAs in cultured astrocytes is regulated following injury, sug gesting that caseinolytic activity is an essential component during the pro cess of astrocyte recovery. (C) 2000 Elsevier Science Ireland Ltd. All righ ts reserved.