Differential Contribution of N- and C-Terminal Regions of HIF1α and HIF2α to Their Target Gene Selectivity

Abstract

Cellular response to hypoxia is controlled by the hypoxia-inducible transcription factors HIF1α and HIF2α. Some genes are preferentially induced by HIF1α or HIF2α, as has been explored in some cell models and for particular sets of genes. Here we have extended this analysis to other HIF-dependent genes using in vitro WT8 renal carcinoma cells and in vivo conditional Vhl-deficient mice models. Moreover, we generated chimeric HIF1/2 transcription factors to study the contribution of the HIF1α and HIF2α DNA binding/heterodimerization and transactivation domains to HIF target specificity. We show that the induction of HIF1α-dependent genes in WT8 cells, such as CAIX (CAR9) and BNIP3, requires both halves of HIF, whereas the HIF2α transactivation domain is more relevant for the induction of HIF2 target genes like the amino acid carrier SLC7A5. The HIF selectivity for some genes in WT8 cells is conserved in Vhl-deficient lung and liver tissue, whereas other genes like Glut1 (Slc2a1) behave distinctly in these tissues. Therefore the relative contribution of the DNA binding/heterodimerization and transactivation domains for HIF target selectivity can be different when comparing HIF1α or HIF2α isoforms, and that HIF target gene specificity is conserved in human and mouse cells for some of the genes analyzed.

Decrease of Intracellular Glutamine by STF-62247 Results in the Accumulation of Lipid Droplets in von Hippel-Lindau Deficient Cells

“…We also investigated the expression of SLC7A5 and the chaperone SLC3A2 which work in tandem with SLC1A5 to export glutamine and drive leucine uptake necessary for proliferation and mTORC1 regulation although this mechanism seems to be cell type-dependent ( 61 ). SLC7A5 has also been shown to be regulated through HIF-2α ( 46 , 62 ). Our results showed decrease of the three SLC at the mRNA level in response to STF in VHL- cells while their levels are either unchanged or stimulated in VHL+.…”

Analysis of the Hypoxic Response in a Mouse Cortical Collecting Duct-Derived Cell Line Suggests That Esrra Is Partially Involved in Hif1α-Mediated Hypoxia-Inducible Gene Expression in mCCDcl1 Cells

“…Despite a similar conserved consensus DNA binding site, HIF-1 and HIF-2 bind different but overlapping sets of sites in chromatin and transactivate only partially overlapping patterns of gene expression. It has been suggested that both the DNA-binding and heterodimerization domain as well as the transactivation domain contribute to HIFα isoform selectivity and accordingly target gene selectivity [39]. Correspondingly, Ortmann and coworkers have recently demonstrated HIF-selective recruitment through its PAS-B domain of the histone 3 lysine 4 (H3K4) methyltransferase SET1B, resulting in site-specific H3K4 methylation and rapid activation of HIF target genes [40].…”

The Underexplored Landscape of Hypoxia-Inducible Factor 2 Alpha and Potential Roles in Tumor Macrophages: A Review

“…Inactivation of the VHL tumor suppressor gene is the signature initiating event in clear cell renal cell carcinoma (ccRCC), which is the most common form of kidney cancer [ 66 ]. VHL mutation leads to abnormal constitutive stabilization of HIF-1α and HIF-2α proteins in normal oxygen conditions.…”