Regulation of keratinocyte differentiation by O-GlcNAcylation

• O-GlcNAcylation is dynamically involved in keratinocyte differentiation.
• O-GlcNAcylation of Sp-1 is decreased in keratinocyte differentiation.
• O-GlcNAcylated Sp-1 is an inactive form in keratinocyte differentiation.

BackgroundO-linked β-N-acetylglucosamine (O-GlcNAc) modification is one of the posttranslational modification, emerging as an important regulatory mechanism in various cellular events.ObjectiveWe attempted to investigate whether O-GlcNAcylation is involved in keratinocyte differentiation.MethodsImmunohistochemistry and Western blot were performed to demonstrate O-GlcNAcylation in keratinocyte differentiation.ResultsDuring calcium-induced keratinocyte differentiation, overall O-GlcNAcylation was decreased in a temporal manner. We focused our attention on transcription factor Sp-1, which is implicated in keratinocyte differentiation. Total Sp-1 level did not change during keratinocyte differentiation. However, O-GlcNAcylated Sp-1 was decreased in a keratinocyte differentiation-dependent manner. Interestingly, transcriptional activity of Sp-1, in terms of involucrin and loricrin promoter activities, was markedly increased by overexpression of O-GlcNAcase (OGA). In addition, membrane permeable non-O-GlcNAcylated Sp-1 did show transcriptional activity, while membrane permeable O-GlcNAcylated Sp-1 did not, suggesting O-GlcNAcylated Sp-1 is an inactive form in keratinocyte differentiation.ConclusionOur results reveal that O-GlcNAcylation is a dynamic regulatory mechanism for keratinocyte differentiation.