Keratinocyte-specific deletion of O-GlcNAc transferase reduces the subcutaneous adipocyte layer in mice.

O-linked N-acetylglucosamine (O-GlcNAc) modification is a dynamic post-translational modification that regulates diverse cellular processes, including transcription, signaling, and differentiation. Although O-GlcNAc transferase (OGT), the sole enzyme catalyzing O-GlcNAcylation, has been studied in various tissues, its role in epidermal homeostasis remains unclear. To address this, we generated skin keratinocyte-specific OGT knockout mice (K14-Cre; OGTfl/fl). These mice exhibited growth retardation and premature lethality around postnatal day 10. Histological analysis revealed a markedly reduced subcutaneous adipocyte layer without significant alterations in the epidermis or dermis. Immunohistochemistry confirmed the complete loss of O-GlcNAcylation in keratinocytes, while expression of major differentiation markers was largely preserved in neonatal skin. At embryonic day 17.5 (E17.5), however, knockout mice displayed impaired barrier formation, as evidenced by diminished toluidine blue uptake, along with increased keratin 10 expression. Furthermore, subcutaneous adipose tissue development was compromised in knockout skin, as demonstrated by reduced Oil Red O staining, which correlated with decreased β-catenin transcriptional activity in primary keratinocytes. Collectively, these findings demonstrate that keratinocyte OGT and O-GlcNAcylation are indispensable for proper skin barrier formation and for epidermal-dermal crosstalk required for adipogenesis, highlighting a previously unrecognized role of O-GlcNAcylation in skin homeostasis.