O-GlcNAc transferase promotes vascular smooth muscle calcification through modulating Wnt/β-catenin signaling

Vascular calcification (VC), associated with high cardiovascular mortality in patients with chronic kidney disease (CKD), involves osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs). O-GlcNAcylation, a dynamic post-translational modification, is closely linked to cardiovascular diseases, including VC. However, the exact role and molecular mechanism of O-GlcNAc signaling in abnormal mineral metabolism-induced VC remain unclear. In the current study, we found that the levels of O-GlcNAc transferase (OGT) and global protein O-GlcNAcylation were significantly upregulated in the artery tissues of mouse calcification models and CKD patients with VC. To further delineate the in vivo role of OGT in VC, we generated Ogt smooth muscle cell-specific knockout mice and challenged them with 5/6 nephrectomy (5/6 Nx) or high-dose vitamin D3 to induce VC. Deletion of Ogt in VSMCs led to alleviated VC in response to 5/6 Nx or VD3. Moreover, elevated O-GlcNAcylation, induced by Thiamet-G, facilitated osteogenic transdifferentiation in VSMCs in response to phosphate, whereas OSMI-1, which reduces O-GlcNAcylation, exhibited an opposite phenotypic effect. Mechanistically, O-GlcNAc signaling enhanced the osteogenic conversion of VSMCs through regulation of canonical Wnt/β-catenin pathway. Indeed, β-catenin was O-GlcNAcylated by OGT and further increased its transcriptional activity in VSMCs. Furthermore, pharmacological activation of Wnt/β-catenin signaling largely reversed the diminished aortic calcification caused by Ogt ablation. Our findings demonstrate that smooth muscle O-GlcNAc signaling plays an important role in regulating hyperphosphatemia-induced VC and reveal that O-GlcNAcylation of β-catenin protein modulates its content and activity in VSMCs.