O-GlcNAc transferase regulates transcriptional activity of human Oct4

Abstract

O-linked β-N-acetylglucosamine (O-GlcNAc) is a single sugar modification found on many different classes of nuclear and cytoplasmic proteins. Addition of this modification, by the enzyme O-linked N-acetylglucosamine transferase (OGT), is dynamic and inducible. One major class of proteins modified by O-GlcNAc is transcription factors. O-GlcNAc regulates transcription factor properties through a variety of different mechanisms including localization, stability and transcriptional activation. Maintenance of embryonic stem (ES) cell pluripotency requires tight regulation of several key transcription factors, many of which are modified by O-GlcNAc. Octamer-binding protein 4 (Oct4) is one of the key transcription factors required for pluripotency of ES cells and more recently, the generation of induced pluripotent stem (iPS) cells. The action of Oct4 is modulated by the addition of several post-translational modifications, including O-GlcNAc. Previous studies in mice found a single site of O-GlcNAc addition responsible for transcriptional regulation. This study was designed to determine if this mechanism is conserved in humans. We mapped 10 novel sites of O-GlcNAc attachment on human Oct4, and confirmed a role for OGT in transcriptional activation of Oct4 at a site distinct from that found in mouse that allows distinction between different Oct4 target promoters. Additionally, we uncovered a potential new role for OGT that does not include its catalytic function. These results confirm that human Oct4 activity is being regulated by OGT by a mechanism that is distinct from mouse Oct4.

Stem cell fate determination through protein O-GlcNAcylation

“…By using mRNA expression analysis and serial chromatin-immunoprecipitation coupled with sequencing (ChIP-seq), the authors showed that O-GlcNAcylated Oct4 directly regulated transcription of 29 genes, including key regulators of pluripotency such as Nanog, Klf5, Klf2, Tbx3, Tcl1 and Nr5a2 [73]. Another study confirmed that human OCT4 is positively regulated by OGT and identified several novel sites O-GlcNAcylated on OCT4 [74]. Together, these findings provided evidence that OCT4 O-GlcNAcylation functions as a pluripotency regulator, adjusting the transcription of pluripotency-related genes in response to external stimuli.…”

Metabolic Regulation of Stem Cells and Differentiation: A Forkhead Box O Transcription Factor Perspective

“…Moreover, in ESCs, glycolysis and glutaminolysis contribute to pluripotency maintenance by direct regulation of jumonji C domain-containing histone demethylases ( JHDMs), teneleven-translocase (TET) DNA demethylases, and core pluripotency factors (20,32,35,70,75,109,152,173). This direct regulation occurs in at least three different ways.…”

“…O-GlcNAcylation positively regulates TET1, thereby promoting pluripotency (152,173). Furthermore, O-GlcNAcylation potentiates the activity of the core pluripotency factors OCT4 and SOX2 as well (32,70).…”

Crosstalk between phosphorylation and O‐GlcNAcylation: friend or foe

“…Protein O-GlcNAcylation plays essential roles in the regulation of transcriptional activity [37][38][39][40], neuronal function [40], epigenetic regulation [41], modulation of protein-protein interactions [16], and the response to external stress factors [42]. Moreover, protein O-GlcNAcylation is very sensitive to the availability of uridine diphospho-N-acetylglucosamine, the GlcNAc donor for O-GlcNAcylation [43] and downstream metabolite of glucose, hence O-GlcNAcylation is often referred to as a nutrient sensor in cells [20, 43,44].…”