Identification of interaction between PAI-2 and IRF-3.

HeLa cells transfected with plasminogen activator inhibitor 2 ( PAI 2 ) were protected from TNF α induced apoptosis. The apoptosis protection by PAI 2 is dependent on a 33 amino acids fragment between helix C and D of PAI 2, which may be due to the interaction of PAI 2 with some intracellular proteins. In this study, the yeast two hybrid system was used to screen a HeLa cells cDNA library constructed during apoptosis with the fragment between helix C and D of PAI 2 as bait. We retrieved a clone that encodes 98 amino acids of C terminus of interferon regulatory factor 3 (IRF 3). Co immunoprecipitation experiments confirmed the interaction between PAI 2 and IRF 3 in vivo. IRF 3 belongs to a family of the IRF transcription factors and has been shown to participate in a large number of biological processes. These data suggest that IRF 3 may be involved in the apoptosis protection and antiviral function of PAI 2.