Biology:EPAS1

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Short description: Protein-coding gene in the species Homo sapiens


A representation of the 3D structure of the protein myoglobin showing turquoise α-helices.
Generic protein structure example

Endothelial PAS domain-containing protein 1 (EPAS1, also known as hypoxia-inducible factor-2alpha (HIF-2α)) is a protein that is encoded by the EPAS1 gene in mammals. It is a type of hypoxia-inducible factor, a group of transcription factors involved in the physiological response to oxygen concentration.[1][2][3][4] The gene is active under hypoxic conditions. It is also important in the development of the heart, and for maintaining the catecholamine balance required for protection of the heart. Mutation often leads to neuroendocrine tumors.

However, several characterized alleles of EPAS1 contribute to high-altitude adaptation in humans.[5][6] One such allele, which has been inherited from Denisovan archaic hominins, is known to confer increased athletic performance in some people, and has therefore been referred to as the "super athlete gene".[7]

Function

The EPAS1 gene encodes one subunit of a transcription factor involved in the induction of genes regulated by oxygen, and which is induced as oxygen concentration falls (hypoxia). The protein contains a basic helix-loop-helix protein dimerization domain as well as a domain found in signal transduction proteins which respond to oxygen levels. EPAS1 is involved in the development of the embryonic heart and is expressed in endothelial cells that line the walls of blood vessels in the umbilical cord.

EPAS1 is also essential for the maintenance of catecholamine homeostasis and protection against heart failure during early embryonic development.[4] Catecholamines regulated by EPAS1 include epinephrine and norepinephrine. It is critical that the production of catecholamines remain in homeostatic conditions so that both the delicate fetal heart and the adult heart do not overexert themselves and induce heart failure. Catecholamine production in the embryo is related to control of cardiac output by increasing the fetal heart rate.[8]

Alleles

A high percentage of Tibetans carry an allele of EPAS1 that improves oxygen transport. The beneficial allele is also found in the extinct Denisovan genome, suggesting that it arose in them and entered the modern human population through hybridization.[9]

The Himalayan wolf[10] and the Tibetan mastiff[11] have inherited an altitude-adaptive allele of the gene from interbreeding with a ghost population of an unknown wolf-like canid. The EPAS1 allele is known to confer an adaptive advantage to animals living at high-altitudes.[10]

Clinical significance

Mutations in the EPAS1 gene are related to early-onset neuroendocrine tumors such as paragangliomas, somatostatinomas and/or pheochromocytomas. The mutations are commonly somatic missense mutations that locate in the primary hydroxylation site of HIF-2α, which disrupt the protein hydroxylation/degradation mechanism, and leads to protein stabilization and pseudohypoxic signaling. In addition, these neuroendocrine tumors release erythropoietin (EPO) into circulating blood, and lead to polycythemia.[12][13]

Mutations in this gene are associated with erythrocytosis familial type 4,[4] pulmonary hypertension, and chronic mountain sickness.[14] There is also evidence that certain variants of this gene provide protection for people living at high altitude such as in Tibet.[5][6][15] The effect is most profound among the Tibetans living in the Himalayas at an altitude of about 4,000 metres above sea level, the environment of which is intolerable to other human populations due to 40% less atmospheric oxygen.

A study by UC Berkeley identified more than 30 genetic factors that make Tibetans' bodies well-suited for high-altitudes, including EPAS1. [16] Tibetans suffer no health problems associated with altitude sickness, but instead produce low levels of blood pigment (haemoglobin) sufficient for less oxygen, more elaborate blood vessels,[17] have lower infant mortality,[18] and are heavier at birth.[19]

EPAS1 is useful in high altitudes as a short term adaptive response. However, EPAS1 can also cause excessive production of red blood cells leading to chronic mountain sickness that can lead to death and inhibited reproductive abilities. Some mutations that increase its expression are associated with increased hypertension and stroke at low altitude, with symptoms similar to mountain sickness. Populations living permanently at high altitudes experience selection on EPAS1 for mutations which reduce the negative fitness consequences of excessive red blood cell production.[15]

Interactions

EPAS1 has been shown to interact with aryl hydrocarbon receptor nuclear translocator[20] and ARNTL.[21]

References

  1. ↑ "Endothelial PAS domain protein 1 (EPAS1), a transcription factor selectively expressed in endothelial cells". Genes & Development 11 (1): 72–82. January 1997. doi:10.1101/gad.11.1.72. PMID 9000051. 
  2. ↑ "Characterization of a subset of the basic-helix-loop-helix-PAS superfamily that interacts with components of the dioxin signaling pathway". The Journal of Biological Chemistry 272 (13): 8581–93. March 1997. doi:10.1074/jbc.272.13.8581. PMID 9079689. 
  3. ↑ "Novel exon 12 mutations in the HIF2A gene associated with erythrocytosis". Blood 111 (11): 5400–2. June 2008. doi:10.1182/blood-2008-02-137703. PMID 18378852. 
  4. ↑ 4.0 4.1 4.2 "Entrez Gene: EPAS1 endothelial PAS domain protein 1". https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=2034. 
  5. ↑ 5.0 5.1 "Sequencing of 50 human exomes reveals adaptation to high altitude". Science 329 (5987): 75–8. July 2010. doi:10.1126/science.1190371. PMID 20595611. Bibcode: 2010Sci...329...75Y. 
  6. ↑ 6.0 6.1 "Genetic variants in EPAS1 contribute to adaptation to high-altitude hypoxia in Sherpas". PLOS ONE 7 (12): e50566. 2012. doi:10.1371/journal.pone.0050566. PMID 23227185. Bibcode: 2012PLoSO...750566H. 
  7. ↑ Algar, Jim (1 July 2014). "Tibetan 'super athlete' gene courtesy of an extinct human species". Tech Times. http://www.techtimes.com/articles/9659/20140703/tibetan-super-athlete-gene-came-from-extinct-human-species.htm. 
  8. ↑ "The hypoxia-responsive transcription factor EPAS1 is essential for catecholamine homeostasis and protection against heart failure during embryonic development". Genes & Development 12 (21): 3320–4. November 1998. doi:10.1101/gad.12.21.3320. PMID 9808618. 
  9. ↑ "Admixture facilitates genetic adaptations to high altitude in Tibet". Nature Communications 5: 3281. 2014-02-10. doi:10.1038/ncomms4281. PMID 24513612. Bibcode: 2014NatCo...5.3281J. 
  10. ↑ 10.0 10.1 "Ancient Hybridization with an Unknown Population Facilitated High-Altitude Adaptation of Canids". Molecular Biology and Evolution 37 (9): 2616–2629. September 2020. doi:10.1093/molbev/msaa113. PMID 32384152. 
  11. ↑ "Genomic Analysis Reveals Hypoxia Adaptation in the Tibetan Mastiff by Introgression of the Grey Wolf from the Tibetan Plateau". Molecular Biology and Evolution 34 (3): 734–743. December 2016. doi:10.1093/molbev/msw274. PMID 27927792. https://zenodo.org/record/895655. 
  12. ↑ "Somatic HIF2A gain-of-function mutations in paraganglioma with polycythemia". The New England Journal of Medicine 367 (10): 922–30. September 2012. doi:10.1056/NEJMoa1205119. PMID 22931260. 
  13. ↑ "Novel HIF2A mutations disrupt oxygen sensing, leading to polycythemia, paragangliomas, and somatostatinomas". Blood 121 (13): 2563–6. March 2013. doi:10.1182/blood-2012-10-460972. PMID 23361906. 
  14. ↑ "Autosomal dominant erythrocytosis and pulmonary arterial hypertension associated with an activating HIF2 alpha mutation". Blood 112 (3): 919–21. August 2008. doi:10.1182/blood-2008-04-153718. PMID 18650473. 
  15. ↑ 15.0 15.1 "Natural selection on EPAS1 (HIF2alpha) associated with low hemoglobin concentration in Tibetan highlanders". Proceedings of the National Academy of Sciences of the United States of America 107 (25): 11459–64. June 2010. doi:10.1073/pnas.1002443107. PMID 20534544. Bibcode: 2010PNAS..10711459B. 
  16. ↑ "Five myths about Mount Everest". Washington Post. 24 April 2014. https://www.washingtonpost.com/opinions/five-myths-about-mount-everest/2014/04/24/9a30ace2-caf5-11e3-a993-b6b5a03db7b4_story.html. "cites https://news.berkeley.edu/2010/07/01/tibetan_genome/ Tibetans adapted to high altitude in less than 3,000 years" 
  17. ↑ "Andean, Tibetan, and Ethiopian patterns of adaptation to high-altitude hypoxia". Integrative and Comparative Biology 46 (1): 18–24. February 2006. doi:10.1093/icb/icj004. PMID 21672719. 
  18. ↑ "Higher offspring survival among Tibetan women with high oxygen saturation genotypes residing at 4,000 m". Proceedings of the National Academy of Sciences of the United States of America 101 (39): 14300–4. September 2004. doi:10.1073/pnas.0405949101. PMID 15353580. 
  19. ↑ "Two routes to functional adaptation: Tibetan and Andean high-altitude natives". Proceedings of the National Academy of Sciences of the United States of America 104 (Suppl 1): 8655–60. May 2007. doi:10.1073/pnas.0701985104. PMID 17494744. 
  20. ↑ "Characterization of a subset of the basic-helix-loop-helix-PAS superfamily that interacts with components of the dioxin signaling pathway". The Journal of Biological Chemistry 272 (13): 8581–93. March 1997. doi:10.1074/jbc.272.13.8581. PMID 9079689. 
  21. ↑ "The basic-helix-loop-helix-PAS orphan MOP3 forms transcriptionally active complexes with circadian and hypoxia factors". Proceedings of the National Academy of Sciences of the United States of America 95 (10): 5474–9. May 1998. doi:10.1073/pnas.95.10.5474. PMID 9576906. Bibcode: 1998PNAS...95.5474H. 

Further reading

External links

This article incorporates text from the United States National Library of Medicine, which is in the public domain.



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