Characteristic increase in nucleocytoplasmic protein glycosylation by O-GlcNAc in 3T3-L1 adipocyte differentiation

O-Linked β-N-acetylglucosaminylation (O-GlcNAcylation) of nucleocytoplasmic proteins is a ubiquitous post-translational modification in multicellular organisms studied so far. Since aberrant O-GlcNAcylation has a link with insulin resistance, it is important to establish the status of O-GlcNAcylation in differentiation of mesenchymal cells such as preadipocytes. In this study, we found a differentiation-dependent drastic increase in the level of O-GlcNAcylation in mouse 3T3-L1 preadipocytes. The occurrence of the increase in O-GlcNAcylation, which correlated with the expression of C/EBPα, was in part due to increased expression of O-GlcNAc transferase. In addition to the well-known O-GlcNAcylated proteins such as nucleoporins and vimentin, pyruvate carboxylase, long chain fatty acid-CoA ligase 1, and Ewing sarcoma protein were identified as the proteins which are heavily O-GlcNAcylated with the adipocyte differentiation. Both adipocyte differentiation and the differentiation-dependent increase in O-GlcNAcylation were blocked by 6-diazo-5-oxo-norleucine. These results suggest that O-GlcNAcylation particilates, at least in part, in adipogenesis.

Research highlights
► The levels of glycosylation by O-GlcNAc increase drastically in adipogenesis.
► The timing of increase in the glycosylation correlates with C/EBPalpha expression.
► The increase in the glycosylation is in part due to increased expression of O-GlcNAc transferase.
► Several heavily O-GlcNAc-modified proteins with the adipocyte differentiation were identified.
► An indirect inhibitor of the glycosylation blocks adipogenesis.