[EPAS1_HUMAN] Defects in EPAS1 are the cause of familial erythrocytosis type 4 (ECYT4) [MIM:611783]. ECYT4 is an autosomal dominant disorder characterized by increased serum red blood cell mass, elevated hemoglobin concentration and hematocrit, and normal platelet and leukocyte counts.
[EPAS1_HUMAN] Transcription factor involved in the induction of oxygen regulated genes. Binds to core DNA sequence 5'-[AG]CGTG-3' within the hypoxia response element (HRE) of target gene promoters. Regulates the vascular endothelial growth factor (VEGF) expression and seems to be implicated in the development of blood vessels and the tubular system of lung. May also play a role in the formation of the endothelium that gives rise to the blood brain barrier. Potent activator of the Tie-2 tyrosine kinase expression. Activation seems to require recruitment of transcriptional coactivators such as CREBPB and probably EP300. Interaction with redox regulatory protein APEX seems to activate CTAD.
Biological responses to oxygen availability play important roles in development, physiological homeostasis, and many disease processes. In mammalian cells, this adaptation is mediated in part by a conserved pathway centered on the hypoxia-inducible factor (HIF). HIF is a heterodimeric protein complex composed of two members of the basic helix-loop-helix Per-ARNT-Sim (PAS) (ARNT, aryl hydrocarbon receptor nuclear translocator) domain family of transcriptional activators, HIFalpha and ARNT. Although this complex involves protein-protein interactions mediated by basic helix-loop-helix and PAS domains in both proteins, the role played by the PAS domains is poorly understood. To address this issue, we have studied the structure and interactions of the C-terminal PAS domain of human HIF-2alpha by NMR spectroscopy. We demonstrate that HIF-2alpha PAS-B binds the analogous ARNT domain in vitro, showing that residues involved in this interaction are located on the solvent-exposed side of the HIF-2alpha central beta-sheet. Mutating residues at this surface not only disrupts the interaction between isolated PAS domains in vitro but also interferes with the ability of full-length HIF to respond to hypoxia in living cells. Extending our findings to other PAS domains, we find that this beta-sheet interface is widely used for both intra- and intermolecular interactions, suggesting a basis of specificity and regulation of many types of PAS-containing signaling proteins.
Structural basis for PAS domain heterodimerization in the basic helix--loop--helix-PAS transcription factor hypoxia-inducible factor.,Erbel PJ, Card PB, Karakuzu O, Bruick RK, Gardner KH Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15504-9. Epub 2003 Dec 10. PMID:14668441
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↑ Furlow PW, Percy MJ, Sutherland S, Bierl C, McMullin MF, Master SR, Lappin TR, Lee FS. Erythrocytosis-associated HIF-2alpha mutations demonstrate a critical role for residues C-terminal to the hydroxylacceptor proline. J Biol Chem. 2009 Apr 3;284(14):9050-8. doi: 10.1074/jbc.M808737200. Epub 2009, Feb 10. PMID:19208626 doi:10.1074/jbc.M808737200
↑ Percy MJ, Beer PA, Campbell G, Dekker AW, Green AR, Oscier D, Rainey MG, van Wijk R, Wood M, Lappin TR, McMullin MF, Lee FS. Novel exon 12 mutations in the HIF2A gene associated with erythrocytosis. Blood. 2008 Jun 1;111(11):5400-2. doi: 10.1182/blood-2008-02-137703. Epub 2008, Mar 31. PMID:18378852 doi:10.1182/blood-2008-02-137703
↑ Percy MJ, Furlow PW, Lucas GS, Li X, Lappin TR, McMullin MF, Lee FS. A gain-of-function mutation in the HIF2A gene in familial erythrocytosis. N Engl J Med. 2008 Jan 10;358(2):162-8. doi: 10.1056/NEJMoa073123. PMID:18184961 doi:10.1056/NEJMoa073123
↑ Percy MJ, Chung YJ, Harrison C, Mercieca J, Hoffbrand AV, Dinardo CL, Santos PC, Fonseca GH, Gualandro SF, Pereira AC, Lappin TR, McMullin MF, Lee FS. Two new mutations in the HIF2A gene associated with erythrocytosis. Am J Hematol. 2012 Apr;87(4):439-42. doi: 10.1002/ajh.23123. Epub 2012 Feb 24. PMID:22367913 doi:10.1002/ajh.23123
↑ Erbel PJ, Card PB, Karakuzu O, Bruick RK, Gardner KH. Structural basis for PAS domain heterodimerization in the basic helix--loop--helix-PAS transcription factor hypoxia-inducible factor. Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15504-9. Epub 2003 Dec 10. PMID:14668441 doi:10.1073/pnas.2533374100