Figure 5.

NBP promotes HIF-1α ubiquitination in H₂O₂-treated cells.

(A) PC12 cells were treated with 200 µM H₂O₂ for 4 hours. The cells were pretreated with 40 µM NBP for 24 hours. The mRNA expression of Bnip3 and Bax were detected by real-time polymerase chain reaction. GAPDH mRNA was used as the internal control. Data normalized by control group are presented as mean ± SD. The experiment was repeated three times. **P < 0.01, ***P < 0.001 (one-way analysis of variance followed by Bonferroni correction). (B) Analysis of HIF-1α ubiquitination (Ub) by immunoblot analysis. (C) Chromatin immunoprecipitation-polymerase chain reaction analysis of HIF-1α binding to Bnip3 and Bax promoters using antibodies against HIF-1α in PC12 cells. Bax: BCL2-associated X; Bnip3: BCL2 interacting protein 3; CTL: control; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HIF-1α: hypoxia-inducible factor 1-alpha; IP: immunoprecipitation; NBP: Dl-3-n-butylphthalide.