O-GlcNAcylation of TLR4 inhibits osteogenic differentiation of periodontal ligament stem cells.

Abstract

Toll-like receptor 4 (TLR4)-mediated inflammatory responses are associated with diabetes and periodontitis, which are dysregulated by O-GlcNAcylation. This study aimed to investigate the effects of O-GlcNAc transferase (OGT)-mediated TLR4 O-GlcNAcylation on the osteogenesis of periodontal ligament stem cells (PDLCs). PDLCs were treated with high glucose (HG) to establish a cell model. Osteogenic differentiation was evaluated using western blotting, an alkaline phosphatase activity assay, and an alizarin red S staining assay. The regulation of OGT on the O-GlcNAcylation of TLR4 was analyzed using co-immunoprecipitation, immunoprecipitation, western blotting, and immunofluorescence staining. The results showed that HG inhibited osteogenic differentiation and promoted inflammatory response. Knockdown of OGT promoted osteogenic differentiation of HG-treated PDLCs. OGT interacted with TLR4 and increased the O-GlcNAcylation and protein levels of TLR4 in the cytomembrane of PDLCs. Moreover, silenced TLR4 reversed the effects on osteogenic differentiation induced by OGT in HG-treated PDLCs. O-GlcNAcylation of TLR4 induced by OGT suppresses osteogenic differentiation of PDLCs after HG stimulation. The findings suggest a promising strategy for treating DP.