Fig. 5

HIF-1α activates transcription of Sox17. a Western blot analysis in control HLMVECs and HLMVECs for which CRISPR/Cas9 was used to delete HIFs. ECs were treated with the HIF prolyl hydroxylase inhibitor DMOG to induce HIF expression. DMOG (1 mM) increased HIF-1α and HIF-2α protein expression in control ECs but not in ECs lacking HIF-1α or HIF-2α. Induction of HIF expression was coupled to Sox17 upregulation. n = 3. b Quantification of a showed that protein expression of HIF-1α and HIF-2α in ECs was significantly increased by DMOG treatment. Sox17 showed a 2.5-fold increase in Sox17 expression control DMSO treated ECs. The increase in Sox17 was significantly reduced in HIF-1α-deleted ECs but preserved in HIF-2α-deleted ECs, indicating the importance of HIF-1α in mediating Sox17 expression. n = 3. c Representation of the SOX17 promoter region with 3 HREs indicated by circled numbers, and their respective sequences are displayed. d HLMVECs were exposed to normoxia or 1% O2 (hypoxia) for 8 h. Ch-IP assay followed by qPCR was performed to amplify the HRE regions in the SOX17 promoter. Studies were performed in ECs exposed to either normoxia or hypoxia. n = 3. e 293T cells were transfected with a HIF-1α overexpression plasmid containing SOX17 luciferase reporter constructs. Luciferase values were normalized to Renilla luciferase control reporter values. A schematic representation of corresponding deletion constructs is presented in the right panel. n = 3 and duplicates per sample. Results show that hypoxia activation of SOX17 HRE3 was required for Sox17 expression. **P < 0.01 and ***P < 0.001. Data are shown as mean ± SEM. Analysis was performed using two-way ANOVA with Bonferroni post-tests for (b, d, e)