Ginsenoside Rb1 attenuates erythropoietin-exacerbated vascular calcification in chronic kidney disease through BMP2-dependent Smad1/5/9 inhibition.

OBJECTIVE: Patients with chronic kidney disease (CKD) exhibit increased vascular calcification (VC) risks, worsened by high-dose erythropoietin (EPO). While EPO treats anemia, its role in VC pathogenesis remains unclear. Ginsenoside Rb1 (Rb1), a Panax ginseng compound with anti-calcification properties, may counteract EPO-induced VC through the GATA binding protein 6 (GATA6)/bone morphogenetic protein 2 (BMP2)/Smad1/5/9 pathway. This article aims to explore whether Rb1 could counteract EPO-induced VC through the GATA6/BMP2/Smad1/5/9 pathway. MATERIAL AND METHODS: Adenine-induced CKD rats and b-glycerophosphate-treated vascular smooth muscle cells (VSMCs) received EPO ± Rb1. Calcification was assessed through von Kossa/alizarin red staining. Smooth muscle protein 22-a (SM22a)/a-Smooth muscle actin (a-SMA) expression was measured by immunofluorescence and real-time-quantitative polymerase chain reaction (RT-qPCR). GATA6/BMP2/Smad1/5/9 activation was analyzed using RT-qPCR/Western blot. Rb1-BMP2 interactions were tested through biotin pulldown, micro-thermophoresis, and Co-immunoprecipitation (Co-IP). GATA6 knockdown validated pathway roles. RESULTS: High-dose EPO significantly worsened CKD-associated calcification and VSMC calcification (P < 0.01), suppressed SM22a and a-SMA expression levels, and activated the GATA6/BMP2/Smad1/5/9 pathway (P < 0.01). GATA6 knockdown reduced EPO-exacerbated calcification and modulated BMP2/Smad1/5/9 signaling (P < 0.01). Rb1 increased SM22a and a-SMA expression levels and inhibited Smad 1/5/9 phosphorylation (P < 0.01), without affecting GATA6 or BMP2 expression (P > 0.05). Molecular docking and Co-IP experiments revealed that Rb1 binds directly to BMP2, blocking its interaction with bone morphogenetic protein receptor and inhibiting Smad 1/5/9 phosphorylation (P < 0.01). CONCLUSION: Rb1 mitigates EPO-aggravated VC in CKD by disrupting BMP2/Smad1/5/9 signaling, positioning it as a promising molecular intervention strategy to reduce EPO-induced vascular toxicity.