%0 Journal Article
%T Effect of O-Glycosylation and Sialylation Inhibitors on Classical NLS-Dependent Nuclear Protein Import in HT29-MTX Human Colon Cancer Cells
%A Benjamin Tam
%A Jonathan M. Rhodes and Lu-Gang Yu
%J Glycobiology Insights
%D 2012
%I 
%R 10.4137/GBI.S4891
%X Glycosylation, including O-linked, mucin type, has an import role in the function and activity of many proteins, particularly those that are secreted or transcellular. Previous studies have indicated that mucin-type O-linked glycans may also be carried by intracellular proteins such as the stress-related protein Orp150 that is involved in classical nuclear localization sequence (NLS)-dependent nuclear protein import. This study investigated the influence on NLS-dependent nuclear protein import of the potent O-glycosylation inhibitor, Benzyl-GalNAc; the sialylation inhibitor, 5¡¯CDP; the Golgi proton pump inhibitor, bafilomycin; and the pro-inflammatory cytokine, TNF¦Á. Treatment of the mucus-secreting human colon cancer HT29-MTX cells with each of these agents caused a global increase of the cellular core 1 carbohydrate structure (galactose ¦Â1,3 N-acetylgalactosamine), one of the precursor structures of the complex mucin-type glycans. Benzyl-GalNAc treatment also increased the expression of the core 1 structure on cell surface glycoconjugates and caused a generalised decrease in sialylation. Hsp70 nuclear translocation upon heat stress, a process that is mediated by the classical NLS pathway, was, however, not affected by pre-treatment of the cells with any of these agents. This suggests that O-linked and/or sialylated glycans are unlikely to be involved in the classical NLS-dependent protein import mechanism.
%U http://www.la-press.com/effect-of-o-glycosylation-and-sialylation-inhibitors-on-classical--nls-article-a2034