Metabolic inhibitors of <i>O</i>-GlcNAc transferase (OGT) that act <i>in vivo </i>implicate decreased <i>O</i>-GlcNAc levels in leptin-mediated nutrient sensing

O‐linked glycosylation of serine and threonine residues of nucleocytoplasmic proteins with N‐acetylglucosamine (O‐GlcNAc) residues is catalyzed by O‐GlcNAc transferase (OGT). O‐GlcNAc is conserved within mammals and is implicated in a wide range of physiological processes. Here we describe metabolic precursor inhibitors of OGT suitable for use both in cells and in vivo in mice. These 5‐thiosugar analogues of N‐acetylglucosamine are assimilated through a convergent metabolic pathway, most likely involving N‐acetylglucosamine‐6‐phosphate de‐N‐acetylase (NAGA) to generate a common OGT inhibitor within cells. Of these inhibitors, we show that 2‐deoxy‐2‐N‐hexanamide‐5‐thio‐D‐glucopyranoside (5SGlcNHex) acts in vivo to induce dose‐ and time‐dependent decreases in O‐GlcNAc levels in various tissues. Decreased O‐GlcNAc correlates, both in vitro within adipocytes and in vivo within mice, with lower levels of transcription factor Sp1 and the satiety‐inducing hormone leptin ‐ revealing a link between decreased O‐GlcNAc levels and nutrient sensing in peripheral tissues of mammals