TRANSIENT OVEREXPRESSION OF CATALASE DOES NOT INHIBIT TNF-INDUCED OR PMA-INDUCED NF-KAPPA-B ACTIVATION

H2O2 has been proposed as a second messenger involved in cell signalin g for NF-kappa B activation. In the present study, this hypothesis was tested by transiently overexpressing catalase, a specific scavenger o f H2O2, in COS-1 cells. A mammalian expression vector was constructed by incorporating catalase gene from pCAT10 clone into the unique EcoRI site of the pSG5 vector which contains the SV-40 promoter. Transient transfection of the catalase expression vector by the DEAE-dextran met hod led to a four-fold increase in catalase activity and catalase cont ent as detected by immunoblot analysis, This level of increase was det ected in both nuclear/mitochondrial- and cytosolic/microsomal fraction s. Overexpression of catalase, however, did not block TNF- or PMA-indu ced NF-kappa B activation. These results weaken the hypothesis that H2 O2 is a second messenger for TNF- and PMA-signaling for NF-kappa B act ivation. (C) 1995 Academic Press, Inc.