title: Genome-wide analysis of HIF-2α chromatin binding sites under normoxia in human bronchial epithelial cells (BEAS-2B) suggests its diverse functions.
abstract: Constitutive functional HIF-2α was recently identified in cancer and stem cell lines under normoxia. In this study, BEAS-2B, a bronchial epithelial cell line, was shown to constitutively express active HIF-2α under normoxia and exhibit markers of pluripotency including Oct-4, Nanog, and sphere formation. Oct-4 expression was reduced after knockdown of HIF-2α under normoxia. Global enrichment analysis of HIF-2α demonstrated the diverse functions of HIF-2α under normoxia. Bioinformatics analysis of the enriched loci revealed an enhancer role of HIF-2α binding sites, involvement of HIF-2α interacting proteins, and enriched de novo motifs which suggest the diverse role of HIF-2α in pseudohypoxia. The low ratio of the discovered loci overlapping with those revealed in cancer cell lines 786-O (16.1%) and MCF-7 (15.9%) under hypoxia indicated a prevailing non-canonical mechanism. Hypoxia had positive, marginal or adverse effects on the enrichment of the selected loci in ChIP-PCR assays. Deletion of the N-terminal activation domain (N-TAD) of HIF-2α disrupted the reporting activity of two of the loci annotated to ELN and ANKRD31. Hypoxia incurring abundance variation of HIF-2α may misrepresent the N-TAD functions as canonical hypoxia inducible features via C-TAD activation. Elucidation of the pseudohypoxia functions of constitutive HIF-2α is useful for resolving its role in malignancy and pluripotency.
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Meng-Chang
authors.initials: MC
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology, Cheng Hsin General Hospital, Taipei, Taiwan.
authors.forename: Hsin-Ju
authors.initials: HJ
authors.lastname: Huang
authors.affiliation: Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, 11031 Taiwan.
authors.forename: Tzu-Hao
authors.initials: TH
authors.lastname: Chang
authors.affiliation: Department of Anesthesiology, Cheng Hsin General Hospital, Taipei, Taiwan.|Department of Pharmacology, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Hsieh-Chou
authors.initials: HC
authors.lastname: Huang
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Shen-Yuan
authors.initials: SY
authors.lastname: Hsieh
authors.affiliation: Department and Graduate Institute of Biochemistry, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Yi-Siou
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Department and Graduate Institute of Biochemistry, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Wei-Yuan
authors.initials: WY
authors.lastname: Chou
authors.affiliation: School of Pharmacy, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Chiao-Hsi
authors.initials: CH
authors.lastname: Chiang
authors.affiliation: School of Public Health, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Ching-Huang
authors.initials: CH
authors.lastname: Lai
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, 11490 Taiwan.|Department and Graduate Institute of Biochemistry, National Defense Medical Center, Taipei, 11490 Taiwan.|School of Public Health, National Defense Medical Center, Taipei, 11490 Taiwan.
authors.forename: Chia-Yang
authors.initials: CY
authors.lastname: Shiau
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D001980:Bronchi / Q000473:pathology*; D063646:Carcinogenesis; D002454:Cell Differentiation; D015687:Cell Hypoxia / Q000235:genetics*; D002843:Chromatin / Q000378:metabolism*; D019295:Computational Biology; D004847:Epithelial Cells / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D055106:Genome-Wide Association Study; D057809:HEK293 Cells; D006801:Humans; D061986:MCF-7 Cells; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D002843:Chromatin; D050814:Octamer Transcription Factor-3; D034741:RNA, Small Interfering; D000099162:Endothelial PAS Domain-Containing Protein 1