Polypeptide GalNAc-T2 interacts with RNA polymerase II and enhances transcriptional activity

CEJAS RB; IRAZOQUI FJ

Buenos Aires

Simposio; First Argentinian Symposium of Glycobiology "GlycoAR 2014"; 2014

Polypeptide GalNAc-Transferases (GALNTs) initiates mucintype O-glycosylation in Golgi although they also could be located in other organelles. In this study we aimed to determine: nuclear localization of GALNT2, interaction of GALNT2 with RNA polymerase II (POL II), and the role of the GALNT2 lectin domain (LD) in relation to transcriptional activity. Western blot and confocal microscopy assays showed that GALNT2 is mainly present in Golgi but we could also detect this transferase in nucleus colocalizing with POL II. Due to the binding ability of LD of GALNTs, we analyzed the interaction GALNT2-POL II, and the effect of acetylation of GALNT2 on such interaction. Dot/far western blot and coimmunoprecipitation assays showed that GALNT2 binds to the C-terminal domain (CTD) of POL II, and that this binding was altered by acetylation. GALNT2 K521Q mutation (mimicking LD acetylation) had a similar effect. Finally we tested the role of GALNT2 LD in transcriptional activity by reporter gene assay. Correlation between high GALNT2 expression levels and enhanced transcriptional activity was observed, and this effect was abolished by K521Q mutation. In conclusion, GALNT2 is in nucleus, interacts with POL II CTD and this interaction is altered by acetylation of GALNT2. Since acetylation of GALNT2 LD affects transcriptional activity we could conclude that acetylation on LD could play a key role in this biological activity.