Polypeptide GalNAc-transferase-2 interacts with RNA polymerase II and enhances transcriptional activity

CEJAS, RB; ZLOCOWSKI N; IRAZOQUI FJ

Simposio; GlycoAr 2014; 2014

polypeptide GalNAc-Transferases (GALNTs) initiates the mucin-type O-glycosylation in the Golgi apparatus although has being reported that also could be located in other organelles (Gill et al, J Cell Biol, 2010; Gill et al, Trends Cell Biol, 2011; Gill et al, PNAS, 2013). In this study we aimed to determine nuclear localization of GALNT2, study the 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 co-localizing 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 co-immunoprecipitation 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 (that mimicks acetylation on the LD) 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. Since acetylation of GALNT2 LD affects transcriptional activity we could conclude that acetylation on LD could play a key role in this biological activity