Involvement of cystatin C in oxidative stress-induced apoptosis of cultured rat CNS neurons

Oxidative stress is involved in neuronal degeneration in cerebrovascular in jury, neuropathology and aging. When rat CNS neurons were cultured in a hig h (50%) oxygen atmosphere, the neurons died. This high oxygen-induced cell death showed features of apoptotic cell death, characterized by DNA fragmen tation, and was blocked by inhibitor of protein synthesis. We found that cy statin C and HuC mRNA, the products of which are an inhibitor of cysteine p roteases and an RNA binding protein, respectively, were up-regulated in neu rons cultured in the high oxygen atmosphere. In the present study, we focus ed on cystatin C. Cystatin C protein levels were also increased in neurons cultured in the high oxygen atmosphere. In situ hybridization with an RNA p robe for rat cystatin C and immunocytochemistry with anti-human cystatin C antibody showed that microtubule-associated protein 2 (MAP2)-positive neuro ns expressed cystatin C mRNA and protein, respectively, in the high oxygen atmosphere. These results indicated that oxidative stress stimulates an inc rease in cystatin C expression in cultured neurons, and that cystatin C mig ht have important roles in regulation of apoptosis elicited by oxidative st ress. (C) 2000 Elsevier Science B.V. All rights reserved.