Fig. 5

TAZ activates SOX2 transcription by directly binding its promoter in HNSCC cells. a Interaction between endogenous TAZ and TEAD4 protein was identified in Cal27 and Fadu cells immunoprecipitation (IP) assay using indicated antibodies. Representative images were shown. b Increased luciferase activities of SOX2 promoter reporter were detected in HEK293T cells transfected with TAZ, TEAD4 plasmid alone or in combination. c Increased luciferase activities of SOX2 promoter reporter were observed in HEK293T cells transfected with increased amount of TEAD4 plasmid. d TAZ constructively active plasmid (TAZ^4SA) induced luciferase activities of SOX2 promoter reporter, while its mutant (TAZ^4SA+S51A) failed. e, f Two binding sites in SOX2 promoter region for TAZ/TEAD4 in Cal27 were identified by ChIP PCR assay Cal27 cells transfected with TAZ were lysed and subjected to ChIP assay using indicated antibodies and PCR or qPCR primers e. The precipitated DNA samples were amplified by qPCR, and then compared f. 1% of total chromatin extract (input) was used as positive control, while normal IgG was used as negative control for IP assay. g Mutations of binding sites in SOX2 promoters significantly abrogated the increased luciferase activities induced by TAZ and TEAD4 plasmids. h Schematic model depicting that TAZ-TEAD4 complex binds with SOX2 promoter and in turn facilitates its transcription. Data were presented as mean ± SD from 3 independent experiments. *P < 0.05, **P < 0.01