ß-catenin is O-GlcNAc glycosylated at Serine 23: implications for ß-catenin's subcellular localization and transactivator function.

ABSTRACT

BACKGROUND: We have previously reported that ß-catenin is post-translationally modified with a single O-linked attachment of ß-N-acetyl-glucosamine (O-GlcNAc). We showed that O-GlcNAc regulated ß-catenin's subcellular localization and transcriptional activity. OBJECTIVE: The objectives of this investigation were to identify the putative O-GlcNAc sites of ß-catenin and the relevance of identified sites in the regulation of ß-catenin's localization and transcriptional activity. METHOD: Missense mutations were introduced to potential O-GlcNAc sites of pEGFP-C2-N-Terminal- or pEGFP-C2-Wild Type-ß-catenin by site-directed mutagenesis. We determined the levels of O-GlcNAc-ß-catenin, subcellular localization, interaction with binding partners and transcriptional activity of the various constructs. RESULTS: Serine 23 of ß-catenin was determined as a site for O-GlcNAc modification which regulated its subcellular distribution, its interactions with cellular partners and consequently its transcriptional activity. SIGNIFICANCE: O-GlcNAcylation of Serine 23 is a novel regulatory modification for ß-catenin's subcellular localization and transcriptional activity. This study is the first report to characterize site specific regulation of ß-catenin by the O-GlcNAc modification.