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

HeLa cells transfected with plasminogen activator inhibitor-2 ( PAI-2 ) were protected from TNF- alpha-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.