Degradation of transglutaminase 2 by calcium-mediated ubiquitination responding to high oxidative stress

Abstract

Transglutaminase 2 (TG2) is a calcium-dependent enzyme that catalyzes the transamidation reaction. Conflicting pieces of evidence have been reported on the role of TG2 in apoptosis. In this report, we showed that TG2 increased in response to low level of oxidative stress, whereas TG2 diminished under high stress conditions. Monitoring TG2 expression, activity and calcium concentration in cells treated with A23187 revealed that the initial rise of calcium activates TG2 but subsequent calcium-overload induces degradation of TG2 via calcium-mediated polyubiquitination. These results indicate that the role of TG2 in apoptosis depends on the level of calcium influx triggered by oxidative stress. (C) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.