Carboxyl-terminal transactivation activity of hypoxia-inducible factor 1 alpha is governed by a von Hippel-Lindau protein-independent, hydroxylation-regulated association with p300/CBP.
Hypoxia-inducible factor 1 complex (HIF-1) plays a pivotal role in oxygen homeostasis and adaptation to hypoxia. Its function is controlled by both the protein stability and the transactivation activity of its alpha subunit, HIF-1 alpha. Hydroxylation of at least two prolyl residues in the oxygen-dependent degradation domain of HIF-1 alpha regulates its interaction with the von Hippel-Lindau protein (VHL) that targets HIF-1 alpha for ubiquitination and proteasomal degradation. Several prolyl hydroxylases have been found to specifically hydroxylate HIF-1 alpha. In this report, we investigated possible roles of VHL and hydroxylases in the regulation of the transactivation activity of the C-terminal activating domain (CAD) of HIF-1 alpha. We demonstrate that regulation of the transactivation activity of HIF-1 alpha CAD also involves hydroxylase activity but does not require functional VHL. In addition, stimulation of the CAD activity by a hydroxylase inhibitor, hypoxia, and desferrioxamine was severely blocked by the adenoviral oncoprotein E1A but not by an E1A mutant defective in targeting p300/CBP. We further demonstrate that a hydroxylase inhibitor, hypoxia, and desferrioxamine promote the functional and physical interaction between HIF-1 alpha CAD and p300/CBP in vivo. Taken together, our data provide evidence that hypoxia-regulated stabilization and transcriptional stimulation of HIF-1 alpha function are regulated through partially overlapping but distinguishable pathways.
Sang
Nianli
N
Cardeza Foundation for Hematologic Research, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5099, USA.
Fang
Jie
J
Srinivas
Vickram
V
Leshchinsky
Irene
I
Caro
Jaime
J
D017500:Adenovirus E1A Proteins / Q000378:metabolism; D001221:Aspartate Carbamoyltransferase / Q000378:metabolism; D015153:Blotting, Western; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D003676:Deferoxamine / Q000494:pharmacology; D004080:Dihydroorotase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006900:Hydroxylation; D000860:Hypoxia / Q000378:metabolism; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008025:Ligases / Q000502:physiology*; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors; D009097:Multienzyme Complexes / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors; D015533:Transcriptional Activation; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein
D017500:Adenovirus E1A Proteins; C033626:CAD trifunctional enzyme; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D020033:Protein Isoforms; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D006899:Mixed Function Oxygenases; D001221:Aspartate Carbamoyltransferase; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D004080:Dihydroorotase; D008025:Ligases; C497446:VHL protein, human; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing); D003676:Deferoxamine