Cited by 1,385Cancer, Hypoxia, and MetabolismKruppel-like factors researchErythropoietin and Anemia Treatment

FIH-1: a novel protein that interacts with HIF-1α and VHL to mediate repression of HIF-1 transcriptional activity

Open access
Mahon, Patrick C., Hirota, Kiichi, Semenza, Gregg L.·2001·Genes & Development

Abstract

Hypoxia-inducible factor 1 (HIF-1) is a master regulator of oxygen homeostasis that controls angiogenesis, erythropoiesis, and glycolysis via transcriptional activation of target genes under hypoxic conditions. O 2 -dependent binding of the von Hippel-Lindau (VHL) tumor suppressor protein targets the HIF-1α subunit for ubiquitination and proteasomal degradation. The activity of the HIF-1α transactivation domains is also O 2 regulated by a previously undefined mechanism. Here, we report the identification of factor inhibiting HIF-1 (FIH-1), a protein that binds to HIF-1α and inhibits its transactivation function. In addition, we demonstrate that FIH-1 binds to VHL and that VHL also functions as a transcriptional corepressor that inhibits HIF-1α transactivation function by recruiting histone deacetylases. Involvement of VHL in association with FIH-1 provides a unifying mechanism for the modulation of HIF-1α protein stabilization and transcriptional activation in response to changes in cellular O 2 concentration.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper identifies FIH-1, a 349-amino-acid protein that binds HIF-1α and VHL and represses HIF-1 transcriptional activity. It proposes that VHL and FIH-1 act as corepressors by recruiting histone deacetylases, unifying O₂-dependent control of HIF-1α stability and transactivation.

Key findings

  • A yeast two-hybrid screen of 2 × 10⁶ transformants identified FIH-1 from a 2.98-kb human brain cDNA encoding a 349-amino-acid protein; the FIH1 gene maps to chromosome 10q24 and consists of eight exons and seven introns spanning 14 kb.
  • FIH-1 binds HIF-1α residues 531–826, with optimal binding requiring TAD-C; residues 757–826 are sufficient, whereas TAD-N (531–575) and TAD-C alone (786–826) did not bind.
  • FIH-1 inhibits HIF-1α transactivation in 293 and Hep3B reporter assays at 1% O₂; antisense FIH-1 increases reporter expression, and FIH-1 inhibits GalA (HIF-1α 531–826) under both 20% and 1% O₂.
  • FIH-1 binds VHL at a distinct site (VHL residues 1–155 sufficient for FIH-1 binding; 1–213 required for efficient HIF-1α binding), and VHL plus FIH-1 cooperatively repress GalL (HIF-1α 531–575); VHL binds HDAC-1, HDAC-2, and HDAC-3 and recruits HDACs to HIF-1α.

Methods

  • Yeast two-hybrid assay using GAL4 DBD–HIF-1α(576–826) bait and a human brain cDNA prey library; 2 × 10⁶ transformants screened for histidine auxotrophy and α-galactosidase expression.
  • In vitro GST pull-down assays with ³⁵S-labeled HIF-1α, FIH-1, VHL, and HDAC proteins; some GST-HIF-1α fusions were preincubated with reticulocyte lysate to induce proline hydroxylation.
  • Transient transfection of HEK293 and Hep3B cells with p2.1 or pG5ElbLuc reporters and GAL4–HIF-1α fusion constructs, exposed to 20% or 1% O₂; immunoprecipitation and immunoblot assays for protein interactions.

Limitations

  • Stated: coimmunoprecipitation of FIH-1 and HIF-1α was detected in cells overexpressing these proteins, so no conclusion can be drawn as to whether the interaction is regulated by cellular O₂ concentration; VHL expression may have been limiting, and no interaction of VHL with FIH-1 or HIF-1α could be demonstrated under those conditions.
  • Stated: whether O₂-dependent interaction of HIF-1α and VHL is required for recruitment of FIH-1 remains unanswered; an alternative but not mutually exclusive hypothesis is that FIH-1 and VHL recruit distinct HDAC complexes.
  • Evident: many interaction and repression conclusions rely on overexpression and in vitro binding assays; FIH-1’s weaker HDAC binding and the possibilities that it interacts with HDAC-4–7, another corepressor, or possesses intrinsic HDAC activity are speculative and not demonstrated.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1101/gad.924501

Cites

46 of 46 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 7 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    VHL and FIH-1 interact with histone deacetylases.

    “Interaction of VHL and FIH-1 with histone deacetylases.”
    Quote in the paperSubstantial claim
  • Findingown data

    FIH-1 and VHL functionally interact to repress HIF-1α transactivation domain function.

    “Functional interaction of FIH-1 and VHL to repress HIF-1␣ transactivation domain function.”
    Quote in the paperSubstantial claim
  • Findingown data

    FIH-1 affects HIF-1-mediated reporter gene transcription.

    “Effect of FIH-1 on HIF-1-mediated reporter gene transcription.”
    Quote in the paperSubstantial claim
  • Findingown data

    FIH-1, HIF-1α, and VHL interact in vitro.

    “Interaction of FIH-1, HIF-1␣, and VHL in vitro.”
    Quote in the paperSubstantial claim
  • Findingown data

    FIH-1 was identified by yeast two-hybrid screen.

    “Identification of FIH-1 by yeast two-hybrid screen.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The physical interaction of bait and prey proteins within yeast cells functionally reconstitutes an active GAL4 transcription factor, resulting in expression of genes containing upstream GAL4-binding sites that mediate histidine auxotrophy and α-gal expression.
  • May combine two claims. 4
  • Classified as probably not a substantial claim. 3
  • May combine two claims.

    Findingown data

    FIH-1 was identified as a 349-amino-acid protein encoded by a 2.98-kb human cDNA.

    “Nucleotide sequence analysis revealed that the prey vector contained a 2.98-kb human cDNA encoding a 349-amino-acid protein that was subsequently designated FIH-1 (GenBank accession no.AF395830).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The FIH1 gene is located at human chromosome 10q24 and consists of eight exons and seven introns spanning 14 kb.

    “Analysis of genomic DNA sequences deposited in Gen-Bank revealed that the FIH1 gene is present in contig NT 008635, which is mapped to human chromosome 10q24, and consists of eight exons and seven introns that span 14 kb of DNA.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Neither FIH-1 nor VHL alone inhibits GalL-mediated transactivation, whereas the combination of FIH-1 and VHL results in significant transcriptional repression.

    “Neither FIH-1 nor VHL alone inhibited GalL-mediated transactivation, whereas the combination of FIH-1 and VHL resulted in significant transcriptional repression.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    FIH-1 is expressed in multiple cell types.

    “EST data indicate that FIH-1 is expressed in multiple cell types derived from adrenal, bladder, brain (adult and fetal), breast, colon, embryo, foreskin, germ cell, heart, kidney, lung, lymph, marrow, muscle, nerve, ovary, parathyroid, prostate, skin, testis, tonsil, and uterus.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    VHL and FIH-1 mediate negative regulation of HIF-1α protein stability and transcriptional activity under nonhypoxic conditions.

    “Negative regulation of HIF-1␣ protein stability and transcriptional activity under nonhypoxic conditions mediated by VHL and FIH-1.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Elongins B and C and cullin 2 are required for E3 ubiquitin-protein ligase activity, whereas HDACs repress transactivation.
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Residues 576-785 of HIF-1α comprise an inhibitory domain whose deletion increases transactivation domain function especially under nonhypoxic conditions.

    “Residues 576-785 comprise an inhibitory domain the deletion of which increases transactivation domain function especially under nonhypoxic conditions (Jiang et al. 1997).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Jiang et al. 1997

      Not checked in the free run.

6 of 6
  • The paper relies on this without support.

    HIF-1 activity is induced by hypoxia in all cell types.

    “Because HIF-1 activity is induced by hypoxia in all cell types, the interaction of HIF-1 with other proteins is likely to play a major role in determining its biological activity.”
  • The paper relies on this without support.

    HIF-1α contains basic helix-loop-helix (bHLH) and PAS domains required for dimerization and DNA binding, a proline/serine/threonine-rich protein stabilization domain (PSTD), two transactivation domains (TAD-N and TAD-C), and an inhibitory domain (ID) that negatively regulates transactivation domain function under nonhypoxic conditions.

    “HIF-1␣ contains basic helix-loop-helix (bHLH) and PAS domains that are required for dimerization and DNA binding, a proline/serine/threonine-rich protein stabilization domain (PSTD), two transactivation domains (TAD-N and TAD-C), and an inhibitory domain (ID) that negatively regulates transactivation domain function under nonhypoxic conditions.”
  • The paper relies on this without support.

    Elongins B and C and cullin 2 are required for E3 ubiquitin-protein ligase activity, whereas HDACs repress transactivation.

    “Elongins B and C and cullin 2 are required for E3 ubiquitin-protein ligase activity, whereas HDACs repress transactivation.”
  • The paper relies on this without support.

    The physical interaction of bait and prey proteins within yeast cells functionally reconstitutes an active GAL4 transcription factor, resulting in expression of genes containing upstream GAL4-binding sites that mediate histidine auxotrophy and α-gal expression.

    “The physical interaction of the bait and prey proteins within yeast cells functionally reconstitutes an active GAL4 transcription factor, resulting in the expression of genes that contain upstream GAL4-binding sites and mediate histidine auxotrophy (his + ) and ␣-gal expression.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • FIH-1 remains capable of binding the CAD under conditions without excess Fe(II) and 2-oxoglutarate.

    “although it remains capable of binding the CAD under these conditions (Mahon et al. 2001).”

    From FIH-1 is an asparaginyl hydroxylase enzyme that regulates the transcriptional activity of hypoxia-inducible factor (2002) · cites this paper as Mahon et al. 2001

    The “Interaction of FIH-1 with HIF-1α in vitro” section reports binding to HIF-1α fragments that include the C-terminal activation domain (CAD), but says the isolated domain (residues 786–826) did not bind FIH-1. The paper does not establish binding specifically under conditions without excess Fe(II) and 2-oxoglutarate. Page numbers are not available in our copy. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • HIF transcriptional activity is also regulated by a second oxygen-sensitive hydroxylation event mediated by FIH-1.

    “HIF transcriptional activity is also regulated by a second oxygen-sensitive hydroxylation event mediated by factor inhibiting HIF-1 (FIH-1) (Mahon et al., 2001;Lando et al., 2002).”

    From Therapeutic targeting of hypoxia and hypoxia-inducible factors in cancer (2016) · cites this paper as Mahon et al., 2001

    The Abstract and Discussion describe FIH-1 as a negative regulator of HIF-1α transcriptional activity associated with oxygen-dependent regulation. They do not identify FIH-1 as mediating a second hydroxylation event; the hydroxylation discussed in the paper is oxygen-dependent hydroxylation of Pro 564 in connection with VHL binding. Page numbers are unavailable in our copy. (LLM, conf=0.89)

    Experimental — accuracy not yet measured
  • FIH-1-mediated repression attenuates HIF transcriptional activity during early reoxygenation, acting as a buffer that limits excessive metabolic activation and oxidative stress during the transition from hypoxia to normoxia.

    “This mechanism attenuates HIF transcriptional activity during early reoxygenation, acting as a buffer that limits the excessive metabolic activation and oxidative stress during the transition from hypoxia to normoxia”

    From HIF inhibition: Current strategies and clinical challenges (2026) · cites this paper as [52]

    The section “FIH-1 inhibits transcriptional activation mediated by HIF-1α in human cells” reports that FIH-1 reduced HIF-dependent reporter expression. The Discussion also describes FIH-1 and VHL as repressing HIF-1α activity under nonhypoxic conditions. The paper does not establish that this occurs during early reoxygenation or that it buffers metabolic activation or oxidative stress during the transition to normoxia. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • FIH-1 functions at lower oxygen tensions than PHDs and hydroxylates a single asparagine residue within the C-terminal transactivation domain of HIF-1α, consequently limiting engagement of transcriptional co-activator complexes.

    “FIH-1 functions at lower oxygen tensions than PHDs and hydroxylates a single asparagine residue within the C-terminal transactivation domain of HIF-1α, consequently limiting engagement of transcriptional co-activator complexes [52,53]”

    From HIF inhibition: Current strategies and clinical challenges (2026) · cites this paper as [52]

    The Discussion and in-vitro interaction section (page numbers unavailable) show that FIH-1 interacts with the C-terminal region of HIF-1α and represses its transactivation function; the paper also identifies coactivators that bind the C-terminal transactivation domain. Our copy does not establish that FIH-1 hydroxylates an asparagine, blocks coactivator engagement by that mechanism, or functions at lower oxygen tensions than PHDs. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • The machinery regulating ODD and CAD appears to be linked.

    “Although the two modes of regulation can be apparently uncoupled from each other through the construction of chimeras containing either the ODD or the CAD, the machinery regulating the two appears to be linked (Mahon et al. 2001).”

Cites

Flagged first, then by citations

1 of the 47 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

Authors
Mahon, P. C., Hirota, K., & Semenza, G. L.
Affiliations
Johns Hopkins University (US)
Venue
Genes & Development
Published
2001-10-15
Volume
15
Issue
20
Pages
2675-2686
ISSN
  • 0890-9369 (ISSN-L)
  • 1549-5477
OpenAlex
W2089692551
Cited by
1,385
References
47
Citations by year
2026: 23 · 2025: 31 · 2024: 40 · 2023: 52 · 2022: 63 · 2021: 71 · 2020: 58 · 2019: 64 · 2018: 47 · 2017: 50 · 2016: 61 · 2015: 60 · 2014: 54 · 2013: 56 · 2012: 59
Type
posted content
Language
en
Open access
Locations
  • Genes & Development (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Uehara Memorial Foundation
  • National Institutes of Health (5r01dk039869-16)
  • National Institute of Diabetes and Digestive and Kidney Diseases (R01 DK39869)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › Cancer, Hypoxia, and Metabolism
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Kruppel-like factors research
  • Health Sciences › Medicine › Hematology › Erythropoietin and Anemia Treatment
Keywords
FIH-1, HIF-1α, VHL, HIF-1, transcriptional repression, histone deacetylase, corepressors, oxygen sensing, protein-protein interaction, ubiquitination, proteasomal degradation, oxygen homeostasis
MeSH terms
Amino Acid Sequence, Animals, Cells, Cultured, DNA-Binding Proteins, Fungal Proteins, Gene Expression Regulation, Glutathione Transferase, Histone Deacetylases, Humans, Mixed Function Oxygenases, Ligases, Luciferases, Molecular Sequence Data, Nuclear Proteins, Oxygen, Protein Conformation, Rabbits, Repressor Proteins, Reticulocytes, Saccharomyces cerevisiae, Transcription Factors, Transcription, Genetic, Signal Transduction, Transcriptional Activation, Cell Hypoxia, Polymerase Chain Reaction, Sequence Homology, Amino Acid, DNA Primers, Two-Hybrid System Techniques, Tumor Suppressor Proteins, Saccharomyces cerevisiae Proteins, Ubiquitin-Protein Ligases, Von Hippel-Lindau Tumor Suppressor Protein, Hypoxia-Inducible Factor 1, alpha Subunit, In Vitro Techniques

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review