Research Paper Advance Articles

Figure 7. 1,25(OH)₂D₃ up-regulates the expression of Myod1 in C2C12 cells through VDR-mediated transcription. (A) Western blot showing changes in Myod1 protein levels in tibialis anterior muscles of 2-month-old WT, 1α(OH)ase^−/− and Sirt1^Tg1α(OH)ase^−/− mice and (B) quantitative analysis. (C, D) 10⁻⁸ M 1,25(OH)₂D₃ treatment upregulates Myod1 gene and protein expression in C2C12 cells. (Each experiment was conducted in five replicates). (E) Predicted VDR binding site (highlighted in yellow) in the Myod1 promoter region. (F) qPCR results showing enrichment of Myod1 in VDR chromatin immunoprecipitation. (G) Agarose gel electrophoresis of ChIP PCR products. (H) Schematic diagram showing construction of luciferase reporter plasmids containing the Myod1 promoter region. (I) Luciferase activity analysis. Each experiment was performed in triplicate. ^*p < 0.05; ^***p < 0.001, compared to control; ^#p < 0.05; ^###p < 0.001, compared to 1α(OH)ase^−/− mice or Vehicle.