Concordant regulation of gene expression by hypoxia and 2-oxoglutarate-dependent dioxygenase inhibition: the role of HIF-1alpha, HIF-2alpha, and other pathways.
Studies of gene regulation by oxygen have revealed novel signal pathways that regulate the hypoxia-inducible factor (HIF) transcriptional system through post-translational hydroxylation of specific prolyl and asparaginyl residues in HIF-alpha subunits. These oxygen-sensitive modifications are catalyzed by members of the 2-oxoglutarate (2-OG) dioxygenase family (PHD1, PHD2, PHD3, and FIH-1), raising an important question regarding the extent of involvement of these and other enzymes of the same family in directing the global changes in gene expression that are induced by hypoxia. To address this, we compared patterns of gene expression induced by hypoxia and by a nonspecific 2-OG-dependent dioxygenase inhibitor, dimethyloxalylglycine (DMOG), among a set of 22,000 transcripts, by microarray analysis of MCF7 cells. By using short interfering RNA-based suppression of HIF-alpha subunits, we also compared responses that were dependent on, or independent of, the HIF system. Results revealed striking concordance between patterns of gene expression induced by hypoxia and by DMOG, indicating the central involvement of 2-OG-dependent dioxygenases in oxygen-regulated gene expression. Many of these responses were suppressed by short interfering RNAs directed against HIF-1alpha and HIF-2alpha, with HIF-1alpha suppression manifesting substantially greater effects than HIF-2alpha suppression, supporting the importance of HIF pathways. Nevertheless, the definition of genes regulated by both hypoxia and DMOG, but not HIF, distinguished other pathways most likely involving the action of 2-OG-dependent dioxygenases on non-HIF substrates.
Oxygen Sensing Group, The Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford OX3 7BN.
Gareth P
GP
Elvidge
Louisa
L
Glenny
Rebecca J
RJ
Appelhoff
Peter J
PJ
Ratcliffe
Jiannis
J
Ragoussis
Jonathan M
JM
Gleadle
D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D051792:Basic Helix-Loop-Helix Proteins; D015687:Cell Hypoxia / Q000235:genetics* / Q000502:physiology*; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007655:Ketoglutarate Dehydrogenase Complex / Q000037:antagonists & inhibitors*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000099162:Endothelial PAS Domain-Containing Protein 1
D000600:Amino Acids, Dicarboxylic; D051792:Basic Helix-Loop-Helix Proteins; D004791:Enzyme Inhibitors; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007655:Ketoglutarate Dehydrogenase Complex; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human; C040947:oxalylglycine