Fig. 1: Phosphorylated CHK2 sustains HIF-1α under hypoxic conditions.
From: ROS-ATM-CHK2 axis stabilizes HIF-1α and promotes tumor angiogenesis in hypoxic microenvironment
A Western blotting of HIF-1α, p-CHK2 Thr68, CHK2, VEGF. For all Western blotting, β-actin was used as a loading control. 1% O2 was performed in HEK293 cells and HEK293-CHK2-KO cells for indicated times. B Western blotting of HIF-1α, p-CHK2 Thr68 and CHK2. HEK293 cells were stimulated by 1% O2, CHK2 inhibitor and combination for 6 h. C, D Flow cytometric analysis of ROS levels and median fluorescence intensity of ROS expression. H1299 cells were stimulated by 1% O2 with or without NAC for 6 h. **p < 0.01. E Western blotting of p-ATM S1981, ATM, HIF-1α, p-CHK2 Thr68 and CHK2. HEK293 cells were pretreated with NAC for 4 h and then cultured in 1% O2 for 6 h. F Western blotting of p-ATM S1981, ATM, HIF-1α, p-CHK2 Thr68 and CHK2. H1299 cells were transfected with the indicated shRNA and exposed to 1% O2 for indicated times. G Western blotting of p-ATM S1981, ATM, HIF-1α, p-CHK2 Thr68 and CHK2. HEK293 and HEK293-CHK2-KO cells were exposed to 1% O2 or combination with ATM inhibitor for 6 h. RT-qPCR analysis of PKM2 (H), PDK1 (I) and BNIP3 (J) mRNA in CHK2-deficient or wildtype HEK293 cells treated with or without hypoxia for 6 h. **p < 0.01, n.s. not significant. K Dual-luciferase reporter gene experiment of PKM2, PDK1 and BNIP3. HEK293-CHK2-KO cells were co-transfected with reporter gene and CHK2 plasmid under normoxia (21% O2) and hypoxia (1% O2). **p < 0.01, n.s. not significant.
