Expression of O-GlcNAcylation in pulp tissue and DPSCs of healthy dental organs.

Introduction: O-GlcNAcylation is a post-translational modification in which a single N-Acetyl-D-Glucosamine (GlcNAc) molecule is added to Ser or Thr residues of proteins. The O-N-acetylglucosaminyl transferase (OGT) enzyme is responsible for adding GlcNAc to the target proteins and N-acetyl-β-D-glucosaminidase (OGA) that removes the GlcNAc residue. O-GlcNAcylation has been described in the pathophysiology of several diseases; however, little has been studied in dental tissue. The aim of the present work is to characterise the product of O-GlcNAcylation and its enzymes at the tissue level in the dental pulp, as well as its expression in dental pulp stem cells (DPSCs) both in situ and in vitro. This enables the recognition of the behaviour of O-GlcNAcylation in pulp tissue without pathology.

Materials and methods: Pulp tissue was obtained from 10 healthy donors, and the expression of O-GlcNAc, OGT, and OGA was analysed using immunofluorescence with specific antibodies in different regions of the dental pulp. DPSCs were isolated, cultured, and identified with anti-STRO1 (antibody specific for human CD34+ cells, useful for DPSC identification). The expression of O-GlcNAc in DPSCs was confirmed in vitro through Western blot.

Results: Different regions of the dental pulp and DPSCs express O-GlcNAc and the enzymes OGT and OGA. O-GlcNAc and OGT expression was more prominent in the odontoblastic layer, cell-rich zone, and in the central core. OGA was distributed throughout the pulp tissue with lower immunoreactivity compared to OGT.

Conclusions: Our results suggest that O-GlcNAcylation may play a relevant role in human dental pulp homeostasis and in physiology of DPSCs.