Endothelial PAS Domain-containing Protein Research Articles

Hypoxic-stabilized EPAS1 proteins transactivate DNMT1 and cause promoter hypermethylation and transcription inhibition of EPAS1 in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality globally. Although cigarette smoking is by far the most important risk factor for lung cancer, the aberrant expression of oncogenes and tumor suppressor genes contributes a great deal to tumorigenesis. Here, we reveal that aberrant expression of endothelial PAS domain-containing protein 1 ( EPAS1) gene, which encodes hypoxia inducible factor 2α, has a critical role in NSCLC. Our results showed EPAS1 mRNA was down-regulated in 82.5% of NSCLC tissues, and a new region of EPAS1 promoter was found to be highly methylated in lung cancer cell lines and NSCLC tissues. Moreover, the methylation rates were negatively correlated to EPAS1 mRNA expression in lung tissues. Further, demethylation analysis demonstrated EPAS1 was regulated by DNA methyltransferases (DNMTs) in NSCLC. In contrast, DNMT1 was verified as an EPAS1 target gene by chromatin immunoprecipitation assay and could be transactivated by stabilized EPAS1 proteins in hypoxic lung cells, thereby decreasing EPAS1 mRNA expression by methylation regulation. Collectively, our study suggests there might be a mechanism of negative-feedback regulation for EPAS1 in NSCLC. That is, hypoxic-stabilized EPAS1 proteins transactivated DNMT1, which further promoted the hypermethylation of EPAS1 promoter and decreased EPAS1 mRNA expression levels in NSCLC.-Xu, X.-H., Bao, Y., Wang, X., Yan, F., Guo, S., Ma, Y., Xu, D., Jin, L., Xu, J., Wang, J. Hypoxic-stabilized EPAS1 proteins transactivate DNMT1 and cause promoter hypermethylation and transcription inhibition of EPAS1 in non-small cell lung cancer.

Endothelial Epas1 Deficiency Is Sufficient To Promote Parietal Epithelial Cell Activation and FSGS in Experimental Hypertension.

FSGS, the most common primary glomerular disorder causing ESRD, is a complex disease that is only partially understood. Progressive sclerosis is a hallmark of FSGS, and genetic tracing studies have shown that parietal epithelial cells participate in the formation of sclerotic lesions. The loss of podocytes triggers a focal activation of parietal epithelial cells, which subsequently form cellular adhesions with the capillary tuft. However, in the absence of intrinsic podocyte alterations, the origin of the pathogenic signal that triggers parietal epithelial cell recruitment remains elusive. In this study, investigation of the role of the endothelial PAS domain-containing protein 1 (EPAS1), a regulatory α subunit of the hypoxia-inducible factor complex, during angiotensin II-induced hypertensive nephropathy provided novel insights into FSGS pathogenesis in the absence of a primary podocyte abnormality. We infused angiotensin II into endothelial-selective Epas1 knockout mice and their littermate controls. Although the groups presented with identical high BP, endothelial-specific Epas1 gene deletion accentuated albuminuria with severe podocyte lesions and recruitment of pathogenic parietal glomerular epithelial cells. These lesions and dysfunction of the glomerular filtration barrier were associated with FSGS in endothelial Epas1-deficient mice only. These results indicate that endothelial EPAS1 has a global protective role during glomerular hypertensive injuries without influencing the hypertensive effect of angiotensin II. Furthermore, these findings provide proof of principle that endothelial-derived signaling can trigger FSGS and illustrate the potential importance of the EPAS1 endothelial transcription factor in secondary FSGS.

176 Genotyping a SNP in the endothelial PAS domain-containing protein 1 (EPAS1) gene: is it associated with mean pulmonary arterial pressures in yearling Angus cattle?

176 Genotyping a SNP in the endothelial PAS domain-containing protein 1 (EPAS1) gene: is it associated with mean pulmonary arterial pressures in yearling Angus cattle?

A novel hypoxia response element regulates oxygen-related repression of tissue factor pathway inhibitor in the breast cancer cell line MCF-7

BackgroundHypoxia is one of the most pervasive physiological stresses in solid tumors. We have previously demonstrated that tissue factor (TF) pathway inhibitor (TFPI) expression was transcriptionally repressed by the activation of hypoxia inducible factor (HIF)-1α under hypoxic conditions. However, the role of HIF-2α, also known as endothelial PAS domain-containing protein 1 (EPAS1), on TFPI expression remains unclear. AimTo explore the role of HIF-2α/EPAS1 in the regulation of TFPI expression under hypoxia in breast cancer cells. Methods and resultsQuantitative RT-PCR showed that total TFPI mRNA and protein levels were decreased by the overexpression of HIF-2α/EPAS1 in MCF7 cells. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay indicated a HIF-2α/EPAS1 responsive region located in the TFPI promoter region at −170 to +21 relative to the transcriptional start site. Subsequent mutagenesis demonstrated a functional hypoxia response element (HRE) 5′-AAACAGGA-3′ for HIF-2α/EPAS1 within the TFPI promoter located at −45 to −38. In breast cancer patients, a positive correlation between HIF-2α/EPAS1 and total TFPI mRNA expression was observed by using gene expression analysis. ConclusionsThis study provides evidence that HIF-2α/EPAS1 is involved in the regulation of TFPI gene expression in breast cancer cells, suggesting that the activation of coagulation and the increased risk of thrombosis observed in breast cancer patients may correlate with local hypoxic regulation of coagulation factors and their inhibitors.

Abstract 5475: Functional profiling of germline EPAS1 variants associated with pheochromocytoma and paraganglioma

Abstract Background: Endothelial PAS domain-containing protein 1 (EPAS1), encoding hypoxia-inducible transcription factor 2-alpha (HIF2α), is involved in regulation of cellular hypoxia responses and has been shown to play a role in several cancers including renal cell cancer and pheochromocytoma/paraganglioma (PPGL). HIF2 levels are tightly regulated, being low in normoxia but increased in hypoxia. Studying heritable PPGL syndromes has uncovered diverse genetic events that lead to oxygen-independent HIF stabilization. Using massively parallel sequencing, we noted several germline EPAS1 variants that occurred in subjects also carrying pathogenic mutations in either VHL or SDHB. In addition, two distinct EPAS1 variants were identified in separate individuals who did not harbor germline mutation in other known susceptibility genes. We therefore investigated whether these variants affected EPAS1 function. Method: Six different EPAS1 variants were identified in the germline of patients with PPGL; p.His194Arg, p.Arg247Ser, p.Phe374Tyr, p.Thr766Pro, p.Pro785Thr and p.Ile789Val. GFP-tagged HIF2α expressing constructs - expressing either empty vector, wildtype or mutant HIF2α- were generated (including positive control p.Pro531Thr) and transfected into HEK293 cells. HEK293 cells transfected with wildtype HIF2α were also subjected to hypoxic conditions for use as a positive control. Co-immunoprecipitation followed by Western blotting analyses were performed to determine whether: a) HIF2α mutants are still able to interact with VHL and ARNT; and b) HIF2α mutants are stabilized under normoxia. Candidate target gene expression (CCND1 and SLC2A) was measured by RT-qPCR. Results: Western blot analyses showed that p.Arg247Ser, p.Phe374Tyr, p.Pro531Thr and p.Pro785Thr amino acid changes in HIF2α were all more stable than wild-type HIF2α under normoxia. Co-IP of HIF2α with VHL showed significantly reduced interaction with p.Arg247Ser and p.Pro531Thr (p<0.05). Co-IP of HIF2α with ARNT failed to show any effect on interaction occurring as a result of the HIF2α variants. Interestingly only p.Pro531Thr was able to induce CCND1 and SLC2A gene expression (p<0.05). Conclusion: Germline EPAS1 variants p.Arg247Ser and p.Phe374Tyr share some functional features in common with the known oncogenic somatic variant p.Pro531Thr. These variants may therefore be functionally relevant to developing cancers that are dependent upon pseudo-hypoxia. Whether any of these EPAS1 variants will affect response to HIF2α antagonist therapies is yet unknown and may be of importance. Citation Format: Edward Kim, Diana E. Benn, Roderick J. Clifton-Bligh, Trisha Dwight. Functional profiling of germline EPAS1 variants associated with pheochromocytoma and paraganglioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5475. doi:10.1158/1538-7445.AM2017-5475

0169 Pulmonary arterial pressure in yearling Angus cattle managed at high altitude: Study of a non-synonymous SNP in the oxygen-dependent degradation domain of the endothelial PAS domain-containing protein 1 gene

0169 Pulmonary arterial pressure in yearling Angus cattle managed at high altitude: Study of a non-synonymous SNP in the oxygen-dependent degradation domain of the endothelial PAS domain-containing protein 1 gene

EPSA1 AND VPF GENES EXPRESSION DURING EMBRYONIC AND LARVAL DEVELOPMENT PERIOD OF BELUGA, HUSO HUSO

Background: The Endothelial PAS domain-containing protein 1 (EPSA1) is the key transcriptional regulator of hypoxic response and Vascular Permeability Factor (VPF) is an important growth factor for vascular development and angiogenesis. OBJECTIVES: In the present study, the levels of the EPSA1 coding gene and VPF transcripts were evaluated during Larval development of Beluga, Huso huso. METHODS: Samples at 12 developmental time-points including 1, 2, 4 days before hatch (eyed eggs), fresh hatched larvae (0), and larvae 1, 3, 6, 10, 15, 20, 25 and 50 days post-hatching were collected and stored in a −80 °C freezer until RNA extraction. Changes in EPSA1 and VPF mRNA expression were studied and differences in normalized mRNA expression levels among the different developmental stages of H. huso were analyzed by one-way analysis of variance (ANOVA). RESULTS: The transcripts of EPSA1 and VPF were detected in all developmental time-points of H. huso from embryos to fingerling fish. Our results revealed that the mRNA expression of EPSA1 and VPF was low during embryonic development and then upregulated significantly at the time of hatch and early larval time-points, whereas in the late larval development stages they started to decline. CONCLUSIONS: This study showed that there is an association between the EPSA1 and VPF mRNA expression during larval development of H. huso. The up regulation of EPSA1 and VPF transcripts at the time of hatch and during yolk sac fry development of H. huso is likely tied to the role of them in vasculogenesis and angiogenesis.

Expression of MicroRNA‐148a and its Target Gene EPAS1 (Endothelial PAS domain‐containing protein 1) in Intestinal Cells in Response to Bifidobacterium bifidum MIMBb75

Bifidobacterium bifidum MIMBb75 is a probiotic strain isolated from healthy human feces. We have previously shown that this strain modulates the composition of the gut microbiota, a core probiotic benefit. Though, molecular mechanisms underlying effects specific to this strain are unknown, particularly at the transcriptional and post‐transcriptional (microRNA, miRNA) level. We found that the expression of intestinal miRNA, including miR‐148a, depends on the presence of the microbiota. MiR‐148a is a proposed biomarker of intestinal health. One of its target genes, EPAS1, also called HIF2α (Hypoxia‐Inducible Factor 2α) is a pro‐inflammatory and pro‐carcinogenic transcription factor.The aim of this study was to investigate the effect of B. bifidum MIMBb75 on the intestinal expression of miR‐148a and EPAS1 in vitro and in vivo.The expression levels of miR‐148a and EPAS1 were assessed by qPCR using RNA extracted from Caco‐2 cells incubated with B. bifidum MIMBb75, B. bifidum NCC390 or B. longum NCC 2705 (cell ratio of 10:1) or control vehicle for 1, 4 and 24 hours at 37°C. To prove that EPAS1 gene expression changes do indeed depend on miR‐148a modulation by B. bifidum MIMBb75, miRNA silencing was performed via transfection of miR‐148a inhibitor in Caco‐2 cells for 72h, followed by incubation of transfected cells with B. bifidum MIMBb75. In addition, C57BL/6J male mice were gavaged for 2 or 14 days with 108 colony forming units of B. bifidum MIMBb75/day or vehicle alone and sacrificed by cervical dislocation. Caecum was used for RNA extraction and gene expression analysis as described above.Of the three strains tested, only B. bifidum MIMBb75 showed a significant upregulation of miR‐148a after 1 and 4 hours of co‐incubation with Caco‐2 cells (P <0.01), but not at 24h. Oral administration of B. bifidum MIMBb75 increased significantly miR‐148a expression in the caecum after 2 days (P< 0.05) but not after 14 days of probiotic administration, which was accompanied by a decrease of EPAS1 expression (P<0.01) at day 2. In vitro silencing of miR‐148a using miRNA inhibitor constructs reversed EPAS1 downregulation.This study brings a new concept of strain‐ and time‐dependent bifidobacteria‐host crosstalk via microRNA. Because early exposure to B. bifidum MIMBb75 repressed the expression of EPAS1, this probiotic may be helpful in intestinal inflammatory conditions associated with EPAS1 over‐expression, such as colitis. Probiotic‐dependent regulation of host gene expression via miRNA may open the way to new therapeutic avenues.Support or Funding InformationNSERC, JP Bickell Foundation, Lawson Family Chair in Microbiome Nutrition Research

Cross-talk between EPAS-1/HIF-2α and PXR signaling pathway regulates multi-drug resistance of stomach cancer cell

EPAS-1/HIF-2α (Endothelial PAS domain-containing protein 1/hypoxia-inducible transcription factors 2α) is a transcription factor expressed in a wide range of human cancers, including stomach cancer. Although EPAS-1 has been studied for years, its function in oncogenic transformation processes needs to be further investigated. In this study, we found that EPAS-1 would promote the growth of stomach cancer cell line BGC-823. Our results revealed that EPAS-1 interacts with Pregnane X Receptor (PXR), a nuclear receptor that regulates multiple genes’ transcription involved in multi-drugs resistance (MDR) process. Protein-protein interaction between EPAS-1 and PXR was identified by co-immunoprecipitation and GST-pull down assays. By this interaction, EPAS-1 recruited PXR to its response elements in promoter/enhancer regions of CYP3A4, a PXR target gene. Over-expression of EPAS-1 increased the expression of PXR responsive genes, enhanced the proliferation of BGC-823 cells and boosted the resistance of BGC-823 cells against the cytotoxicity of chemotherapeutic drugs, e.g. Mitomycin C and Paclitaxel. Reduction of EPAS-1 level via its siRNA disrupted the proliferation, and enhanced the susceptibility of BGC-823 cells to those chemotherapeutic drugs. Our findings suggested that EPAS-1 and PXR may cooperatively participate in development and especially MDR process of stomach cancer. These findings may contribute to more effective targeted drugs discovery for the stomach cancer therapy.

TLR4 Overexpression Inhibits Endothelial PAS Domain-Containing Protein 1 Expression in the Lower Respiratory Tract of Patients with Chronic COPD

Background/Aims: The study was designed to explore the potential relationship of TLR4 and endothelial PAS domain-containing protein 1 (EPAS1) in vivo and vitro experiments. Methods: Bronchoalveolar lavage fluid (BALF) samples were collected from 55 chronic obstructive pulmonary disease (COPD) patients and 25 healthy subjects. The differential cell count was performed using Wright-Giemsa staining. The expression levels of TLR4 and TLR5 were detected by RT-qPCR. The levels of methylation and mRNA expression of EPAS1 were assayed by bisulfite sequencing PCR and real-time PCR. The correlation of TLR4 and EPAS1 was also analyzed in TLR 4-overexpressing endothelial cells. Results: The results showed that the number of neutrophils, lymphocytes and macrophages and expression of TLR 4 were significantly increased in lower respiratory tract of COPD patients. Moreover, decreased EPAS1 mRNA and increased EPAS1 promoter methylation were detected in COPD, which were closely associated with increased TLR4 expression. According to in vitro experiments, TLR 4 inhibited EPAS1 mRNA expression and promoted promoter methylation in endothelial cells. Conclusion: These findings suggest that TLR4 over-expression decreased EPAS1expression which contributes to the progress of COPD.

Gene-environment interaction of genome-wide association study-identified susceptibility loci and meat-cooking mutagens in the etiology of renal cell carcinoma.

Meat-cooking mutagens may be associated with renal cell carcinoma (RCC) risk. In the current study, the authors examined associations between meat-cooking mutagens, genetic susceptibility variants, and risk of RCC. The authors used 659 newly diagnosed RCC cases and 699 healthy controls to investigate the association between dietary intake of meat-cooking mutagens and RCC. They examined whether associations varied by risk factors for RCC and genetic susceptibility variants previously identified from genome-wide association studies. Odds ratios and 95% confidence intervals were estimated using tertiles of intake of dietary polycyclic aromatic hydrocarbons/heterocyclic amines. Dietary intake of the mutagenic compounds 2-amino-3,8-dimethylimidazo-(4,5-f) quinoxaline (MeIQx) and 2-amino-1 methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) were found to be significantly associated with an increased risk of RCC (odds ratios across tertiles: 1.00 [referent], 1.28 [95% confidence interval, 0.94-1.74], and 1.95 [95% confidence interval, 1.43-2.66] [P for trend <.001], respectively; and 1.00 [referent], 1.41 [95% confidence interval, 1.04-1.90], and 1.54 [95% confidence interval, 1.14-2.07] [P for trend =.02], respectively). The authors observed evidence of interactions between PhIP and RCC susceptibility variants in 2 genes: inositol 1,4,5-trisphosphate receptor, type 2 (ITPR2) (rs718314; multiplicative P for interaction = .03 and additive P for interaction =.002) and endothelial PAS domain-containing protein 1 (EPAS1) (rs7579899; additive P for interaction =.06). The intake of meat may increase the risk of RCC through mechanisms related to the cooking compounds MeIQx and PhIP. These associations may be modified by genetic susceptibility to RCC. Further research is necessary to understand the biological mechanisms underlying these interactions.

Endothelial PAS domain-containing protein 1 confers TKI-resistance by mediating EGFR and MET pathways in non-small cell lung cancer cells

Mutations in epidermal growth factor receptor (EGFR) rendering it constitutively active is one of the major causes for metastatic non-small-cell lung cancer (NSCLC), and EGFR-targeted therapies utilizing tyrosine kinase inhibitors (TKIs) are often used clinically as the first-line treatment. But approximately half of NSCLC patients develop resistance to these therapies, where the MET proto-oncogene is amplified by EGFR through the hypoxia-inducible factor (HIF)-1α. Here we report that endothelial PAS domain-containing protein 1 (EPAS1), with 48% sequence identity to HIF-1α, specifically binds to TKI-resistant T790M EGFR, but not to wild-type EGFR, in NSCLC cell lines. Expression of EPAS1 enhances amplification of MET when simultaneously expressed with T790M EGFR but not with wild-type EGFR, and this enhancement is independent of ligand binding domain of EGFR. MET amplification requires EPAS1, since EPAS1 knock-down reduced MET levels. When NSCLC cells expressing T790M EGFR were treated with TKIs, reduced EPAS1 levels significantly enhanced the drug effect, whereas over-expression of EPAS1 increased the drug resistant effect. This EPAS1-dependent TKI-resistance was abolished by knocking-down MET, suggesting that EPAS1 does not cause TKI-resistance itself but functions to bridge EGFR and MET interactions. Our findings suggest that EPAS1 is a key factor in the EGFR-MET crosstalk in conferring TKI-resistance in NSCLC cases, and could be used as a potential therapeutic target in TKI-resistant NSCLC patients.

Prognostic potential of DNA methylation and transcript levels of HIF1A and EPAS1 in colorectal cancer.

Hypoxic conditions during the formation of colorectal cancer may support the development of more aggressive tumors. Hypoxia-inducible factor (HIF) is a heterodimeric complex, composed of oxygen-induced HIFα and constitutively expressed HIFβ subunits, which mediates the primary transcriptional response to hypoxic stress. Among HIFα isoforms, HIF1α (HIF1A) and endothelial PAS domain-containing protein 1 (EPAS1) are able to robustly activate hypoxia-responsive gene signatures. Although posttranslational regulation of HIFα subunits is well described, less is known about their transcriptional regulation. Here, molecular analysis determined that EPAS1 mRNA was significantly reduced in primary colonic adenocarcinoma specimens compared with histopathologically nonneoplastic tissue from 120 patients. In contrast, no difference in HIF1A mRNA levels was observed between cancerous and noncancerous tissue. Bisulfite DNA sequencing and high-resolution melting analysis identified significant DNA hypermethylation in the EPAS1 regulatory region from cancerous tissue compared with nonneoplastic tissue. Importantly, multivariate Cox regression analysis revealed a high HR for patients with cancer with low EPAS1 transcript levels (HR, 4.91; 95% confidence interval, CI, 0.42-56.15; P = 0.047) and hypermethylated EPAS1 DNA (HR, 33.94; 95% CI, 2.84-405.95; P = 0.0054). Treatment with a DNA methyltransferase inhibitor, 5-Aza-2'-deoxycytidine (5-aza-dC/Decitabine), upregulated EPAS1 expression in hypoxic colorectal cancer cells that were associated with DNA demethylation of the EPAS1 regulatory region. In summary, EPAS1 is transcriptionally regulated by DNA methylation in colorectal cancer. DNA methylation and mRNA status of EPAS1 have novel prognostic potential for colorectal cancer.

Endothelial PAS Domain-Containing Protein 1 (EPAS1) Gene Polymorphisms and Response to Anti-VEGF Therapy in the Comparison of AMD Treatments Trials (CATT)

The efficacy of the intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents bevacizumab and ranibizumab has revolutionized the treatment of neovascular age-related macular degeneration. Results from the Comparison of AMD Treatments Trials (CATT), the Alternative Treatments to Inhibit VEGF in Patients with Age-Related Choroidal Neovascularisation (IVAN) trial, and other multicenter randomized clinical trials that compared bevacizumab and ranibizumab indicate that both drugs provide dramatic and lasting visual improvements for patients. However, results from these trials also make clear that there is individual variation in the initial response to therapy and in the durability of the clinical effect. Genetic assessment of participants in these trials provides an ideal opportunity to investigate pharmacogenetic associations using rigorously defined phenotypic data.

Oxidative stress at high altitude: genotype&amp;ndash;phenotype correlations

Oxidative stress at high altitude: genotype&ndash;phenotype correlations Priyanka Pandey,1,2 MA Qadar Pasha1,2 1CSIR-Institute of Genomics and Integrative Biology, Delhi, India; 2Department of Biotechnology, University of Pune, Ganeshkhind, Pune, India Abstract: It has been well-documented that the hypobaric hypoxic environment at high altitude (HA) causes stress to both the permanent residents of HA and the sojourners. This oxidative stress primarily disturbs the oxygen-sensing and vascular homeostasis pathways, thereby upsetting normal human physiology, especially in sojourners. These environmental challenges have caused dynamic evolutionary changes within natives of HA, allowing them to develop adaptive plasticity. This review focuses on the genomic and biochemical features of the molecules involved in the oxygen-sensing and vascular homeostasis pathways with respect to HA pulmonary edema (HAPE) and adaptation. We review the role of genetic markers such as HIF-prolyl hydroxylase 2, endothelial PAS domain-containing protein 1, endothelial nitric oxide synthase, endothelin 1, cytochrome b-245 alpha polypeptide, and glutathione S-transferase pi 1, as well as three circulatory biomarkers (nitric oxide, endothelin 1, and 8-iso-prostaglandin F2&alpha;), by highlighting approaches such as candidate gene and genome-wide, adopted in deciphering the pathways. A disagreement between the two approaches has also been highlighted. In addition, we discuss that an overrepresentation of wild-type alleles in HA natives and mutant alleles of same polymorphisms in HAPE patients implies that the allelic variants at the same locus are involved in adaptation and HAPE, respectively. Moreover, healthy sojourners present a number of genomic features similar to HA natives, further strengthening the concept of genetic predisposition. A trend in correlation between protective and risk alleles and altered levels of circulatory markers clearly documents the phenomenon of genotype&ndash;phenotype correlations. We conclude that the genetic and biochemical markers discussed here both could prove to be potential targets for future diagnostic and therapeutic interventions. Keywords: high altitude, oxidative stress, pulmonary edema, sojourners, natives

Oxygen sensing pathway: genetic adaptation at high‐altitude

Residents of Himalayas have evidence of selection of genetic variants and the genes of oxygen sensing pathway have emerged favorite candidates. Candidate gene and genome‐wide association studies (GWAS) have substantiated the involvement of endothelial PAS domain‐containing protein 1 (EPAS1) and HIF‐1 prolyl hydroxylase 2 (EGLN1) in adaptation to and disorders of hypobaric hypoxia. The case‐control design enumerated the selection of EGLN1 T allele of rs480902 and C allele of rs479200 in HA population (P=4.01E‐07). Conversely, the variants were overrepresented in HAPE (P&lt;0.05). Other two candidates of this pathway namely endothelial nitric oxide synthase (NOS3) and endothelin‐1 (ET‐1) also associated. The alleles 298Glu of 298Glu/Asp and 4b of 4b/4a polymorphisms of NOS3, G of 2288G/T polymorphism and longer‐repeats of (CT)n–(CA)n repeat of ET‐1 were overrepresented in natives (P≤0.05); whereas, alleles 298Asp, 4a, T, and shorter‐repeats of respective gene polymorphisms were associated with HAPE (P≤0.05). Plasma NO, ET‐1 levels differentially associated with the variants. These studies clearly demonstrate the evolutionary selection of genetic variants in Tibetans that helped them achieve physiological profile similar to normoxic condition. This work was funded by Council of Scientific and Industrial Research, India.