Distribution of O-GlcNAc transferase in the rat pancreas

O-GlcNAc transferase (OGT) catalyzes the attachment of N-acetylglucosamine monosaccharides to the hydroxyl group of serine or threonine residues of intracellular proteins and may play an important role in the hexosamine pathway. We examined the localization of OGT protein in the rat pancreas. Immunofluorescence staining with antibody raised against OGT stained both the exocrine acinar cells and endocrine islet cells. The acinar cell nucleus and the zymogen granule region were intensely stained. In the islets of Langerhans, especially in the A cells, intense staining with anti-OGT antibody was observed. Immune-electron microscopy showed the OGT to be restricted to the euchromatin of the nucleus and around the secretory granules of exocrine acinar cells and endocrine islet cells. These results suggest that OGT is involved in the regulation of transcription and of granular secretion. Thus. O-GlcNAcylated protein(s) may be an important component of the glucose-sensing mechanism in the pancreas.