Synthetic transactivation screening reveals ETV4 as broad coactivator of hypoxia-inducible factor signaling.

ABSTRACT: The human prolyl-4-hydroxylase domain (PHD) proteins 1-3 are known as cellular oxygen sensors, acting via the degradation of hypoxia-inducible factor (HIF) ?-subunits. PHD2 and PHD3 genes are inducible by HIFs themselves, suggesting a negative feedback loop that involves PHD abundance. To identify novel regulators of the PHD2 gene, an expression array of 704 transcription factors was screened by a method that allows distinguishing between HIF-dependent and HIF-independent promoter regulation. Among others, the E-twenty six transcription factor ETS translocation variant 4 (ETV4) was found to contribute to PHD2 gene expression particularly under hypoxic conditions. Mechanistically, complex formation between ETV4 and HIF-1/2? was observed by mammalian two-hybrid and fluorescence resonance energy transfer analysis. HIF-1? domain mapping, CITED2 overexpression and factor inhibiting HIF depletion experiments provided evidence for cooperation between HIF-1? and p300/CBP in ETV4 binding. Chromatin immunoprecipitation confirmed ETV4 and HIF-1? corecruitment to the PHD2 promoter. Of 608 hypoxically induced transcripts found by genome-wide expression profiling, 7.7% required ETV4 for efficient hypoxic induction, suggesting a broad role of ETV4 in hypoxic gene regulation. Endogenous ETV4 highly correlated with PHD2, HIF-1/2? and several established markers of tissue hypoxia in 282 human breast cancer tissue samples, corroborating a functional interplay between the ETV4 and HIF pathways.

SUBMITTER: Wollenick K 

PROVIDER: S-EPMC3300025 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature