HIF1α Promotes BMP9-Mediated Osteoblastic Differentiation and Vascularization by Interacting with CBFA1

Figure 6

Identification and verification of Runx2 as an early downstream target of HIF1α enhanced by BMP9 in iMEFs. (a) ChIP analysis showed that Runx2 is a direct target of HIF1α signaling in iMEFs. iMEFs were transfected with Ad-BMP9 and Ad-HIF1α for 36 h, followed by formaldehyde crosslinking. The crosslinked cells were lysed and subjected to enzymolysis and immunoprecipitation with an anti-HIF1α or IgG antibody, the pulled down composite was subjected to gel electrophoresis and imaging, and primers for the Runx2 promoter region were used in the ChIP assay. (b) The recovered chromatin DNA fragments were used for qPCR amplification with 4 primers specific for the mouse Runx2 promoter. (c) Luciferase reporter assay results showed the effect of HIF1α and/or Runx2 on the transcriptional activities of the firefly/Renilla luminescence reporter. (d) The transcription factor Runx2 cannot activate the promoter of HIF1α. The transcription factor HIF1α can activate the promoter of Runx2 ().

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