Abstract
While the functions of hypoxia-inducible factor 1α (HIF1α)/aryl hydrocarbon receptor nuclear translocator (ARNT) and HIF2α/ARNT (HIF2) proteins in activating hypoxia-inducible genes are well established, the role of other transcription factors in the hypoxic transcriptional response is less clear. We report here for the first time that the basic helix-loop-helix-leucine-zip transcription factor upstream stimulatory factor 2 (USF2) is required for the hypoxic transcriptional response, specifically, for hypoxic activation of HIF2 target genes. We show that inhibiting USF2 activity greatly reduces hypoxic induction of HIF2 target genes in cell lines that have USF2 activity, while inducing USF2 activity in cells lacking USF2 activity restores hypoxic induction of HIF2 target genes. Mechanistically, USF2 activates HIF2 target genes by binding to HIF2 target gene promoters, interacting with HIF2α protein, and recruiting coactivators CBP and p300 to form enhanceosome complexes that contain HIF2α, USF2, CBP, p300, and RNA polymerase II on HIF2 target gene promoters. Functionally, the effect of USF2 knockdown on proliferation, motility, and clonogenic survival of HIF2-dependent tumor cells in vitro is phenocopied by HIF2α knockdown, indicating that USF2 works with HIF2 to activate HIF2 target genes and to drive HIF2-depedent tumorigenesis.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Basic Helix-Loop-Helix Transcription Factors / agonists
-
Basic Helix-Loop-Helix Transcription Factors / genetics*
-
Basic Helix-Loop-Helix Transcription Factors / metabolism
-
CREB-Binding Protein / genetics
-
CREB-Binding Protein / metabolism
-
Cell Line, Tumor
-
Cell Proliferation
-
Cell Survival / genetics
-
Cell Transformation, Neoplastic / genetics
-
Cell Transformation, Neoplastic / metabolism
-
Cell Transformation, Neoplastic / pathology
-
Humans
-
Hypoxia / genetics*
-
Hypoxia / metabolism
-
Hypoxia / pathology
-
Mice
-
Mice, Knockout
-
Plasmids
-
Promoter Regions, Genetic
-
Protein Binding
-
RNA Polymerase II / genetics
-
RNA Polymerase II / metabolism
-
RNA, Small Interfering / genetics
-
RNA, Small Interfering / metabolism
-
Signal Transduction / genetics*
-
Transcriptional Activation*
-
Transfection
-
Upstream Stimulatory Factors / antagonists & inhibitors
-
Upstream Stimulatory Factors / genetics*
-
Upstream Stimulatory Factors / metabolism
-
p300-CBP Transcription Factors / genetics
-
p300-CBP Transcription Factors / metabolism
Substances
-
Basic Helix-Loop-Helix Transcription Factors
-
RNA, Small Interfering
-
USF2 protein, human
-
Upstream Stimulatory Factors
-
endothelial PAS domain-containing protein 1
-
CREB-Binding Protein
-
CREBBP protein, human
-
p300-CBP Transcription Factors
-
p300-CBP-associated factor
-
RNA Polymerase II