Evidence of a compensatory regulation of colonic O-GlcNAc transferase and O-GlcNAcase expression in response to disruption of O-GlcNAc homeostasis.

O-GlcNAcylation is a post-translational modification of thousands of intracellular proteins that dynamically regulates many fundamental cellular processes. Cellular O-GlcNAcylation levels are regulated by a unique couple of enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which adds and removes the GlcNAc residue, respectively. Maintenance of O-GlcNAc homeostasis is essential to ensure optimal cellular function and disruption of this homeostasis has been linked to the etiology of several human diseases including cancer. The mechanisms through which the cell maintains O-GlcNAc homeostasis are not fully understood but several studies have suggested that a reciprocal regulation of OGT and OGA expression could be one of them. In this study, we investigated the putative regulation of OGT and OGA expression in response to disruption in O-GlcNAc homeostasis in colon. We provide in vitro and in vivo evidences that in colon cells, modulation of O-GlcNAcylation levels leads to a compensatory regulation of OGT and OGA expression in an attempt to restore basal O-GlcNAcylation levels. Our results also suggests that the regulation of colonic OGA expression in response to changes in O-GlcNAc homeostasis occurs mostly at the transcriptional level whereas OGT regulation seems to rely mainly on post-transcriptional mechanisms.