Target gene selectivity of hypoxia-inducible factor-alpha in renal cancer cells is conveyed by post-DNA-binding mechanisms.
Inactivation of the von Hippel-Lindau tumour suppressor in renal cell carcinoma (RCC) leads to failure of proteolytic regulation of the alpha subunits of hypoxia-inducible factor (HIF), constitutive upregulation of the HIF complex, and overexpression of HIF target genes. However, recent studies have indicated that in this setting, upregulation of the closely related HIF-alpha isoforms, HIF-1alpha and HIF-2alpha, have contrasting effects on tumour growth, and activate distinct sets of target genes. To pursue these findings, we sought to elucidate the mechanisms underlying target gene selectivity for HIF-1alpha and HIF-2alpha. Using chromatin immunoprecipitation to probe binding to hypoxia response elements in vivo, and expression of chimaeric molecules bearing reciprocal domain exchanges between HIF-1alpha and HIF-2alpha molecules, we show that selective activation of HIF-alpha target gene expression is not dependent on selective DNA-binding at the target locus, but depends on non-equivalent C-terminal portions of these molecules. Our data indicate that post-DNA binding mechanisms that are dissimilar for HIF-1alpha and HIF-2alpha determine target gene selectivity in RCC cells.
Lau
K W
KW
The Henry Wellcome Building for Molecular Physiology, Oxford, UK.
Tian
Y-M
YM
Raval
R R
RR
Ratcliffe
P J
PJ
Pugh
C W
CW
D051792:Basic Helix-Loop-Helix Proteins; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D007680:Kidney Neoplasms / Q000235:genetics*; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D014157:Transcription Factors; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human