Nogo-B attenuates vascular calcification by activating NRF2-SLC7A11 to enhance antioxidant defense

OBJECTIVE: Vascular calcification (VC), characterized by abnormal calcium salts buildup in blood vessels, greatly raises the risk of adverse cardiovascular events. However, the mechanisms behind VC are not fully understood. Nogo-B, a member of the reticulon family, has been implicated in various pathological processes including intimal neovascularization, obesity, and metabolic-associated fatty liver disease. Yet, its role in VC has not been explored. APPROACH AND RESULTS: ). An ex vivo osteogenic model employing human arteries and an in vitro osteogenic model using human aortic smooth muscle cells (HASMCs) were both created under high phosphate conditions. Nogo-B expression was significantly downregulated in calcified human and mouse aortas, as well as in high phosphate-treated HASMCs. Additionally, SMC-specific knockout of Nogo-B exacerbated VC. Conversely, overexpressing Nogo-B suppressed osteogenic differentiation of HASMCs. Mechanistically, Nogo-B inhibited VC by upregulating the expression of the amino acid transporter SLC7A11. Nogo-B strongly interacts with SLC7A11 and promotes recruitment of the deubiquitinating enzyme OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1), thereby preventing K63-linked ubiquitination of SLC7A11 at K30. Furthermore, Nogo-B-mediated upregulation of SLC7A11 boosted intracellular glutathione (GSH) synthesis, which activated NRF2. NRF2 functions as a transcriptional enhancer of SLC7A11. Ultimately, Nogo-B activated antioxidant defense and alleviated oxidative stress to suppress vascular calcification. CONCLUSION: This study identifies Nogo-B as a novel regulator of VC. Nogo-B stabilizes the SLC7A11 protein by modulating OTUB1-mediated deubiquitination and enhances the GSH/NRF2 signaling axis, thereby promoting glutathione synthesis, reducing oxidative stress, and inhibiting the osteogenic differentiation of VSMCs and VC progression.