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The FIH hydroxylase is a cellular peroxide sensor that modulates HIF transcriptional activity.

ABSTRACT: Hypoxic and oxidant stresses can coexist in biological systems, and oxidant stress has been proposed to activate hypoxia pathways through the inactivation of the 'oxygen-sensing' hypoxia-inducible factor (HIF) prolyl and asparaginyl hydroxylases. Here, we show that despite reduced sensitivity to cellular hypoxia, the HIF asparaginyl hydroxylase--known as FIH, factor inhibiting HIF--is strikingly more sensitive to peroxide than the HIF prolyl hydroxylases. These contrasting sensitivities indicate that oxidant stress is unlikely to signal hypoxia directly to the HIF system, but that hypoxia and oxidant stress can interact functionally as distinct regulators of HIF transcriptional output.

SUBMITTER: Masson N

PROVIDER: S-EPMC3323130 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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The FIH hydroxylase is a cellular peroxide sensor that modulates HIF transcriptional activity.

Masson Norma N Singleton Rachelle S RS Sekirnik Rok R Trudgian David C DC Ambrose Lucy J LJ Miranda Melroy X MX Tian Ya-Min YM Kessler Benedikt M BM Schofield Christopher J CJ Ratcliffe Peter J PJ

EMBO reports 20120301 3

Hypoxic and oxidant stresses can coexist in biological systems, and oxidant stress has been proposed to activate hypoxia pathways through the inactivation of the 'oxygen-sensing' hypoxia-inducible factor (HIF) prolyl and asparaginyl hydroxylases. Here, we show that despite reduced sensitivity to cellular hypoxia, the HIF asparaginyl hydroxylase--known as FIH, factor inhibiting HIF--is strikingly more sensitive to peroxide than the HIF prolyl hydroxylases. These contrasting sensitivities indicate ...[more]

PMID: 22310300

Similar Datasets

Screening chelating inhibitors of HIF-prolyl hydroxylase domain 2 (PHD2) and factor inhibiting HIF (FIH).

Project description:Two primary O(2)-sensors for humans are the HIF-hydroxylases, enzymes that hydroxylate specific residues of the hypoxia inducible factor-? (HIF). These enzymes are factor inhibiting HIF (FIH) and prolyl hydroxylase-2 (PHD2), each an ?-ketoglutarate (?KG) dependent, non-heme Fe(II) dioxygenase. Although the two enzymes have similar active sites, FIH hydroxylates Asn(803) of HIF-1? while PHD2 hydroxylates Pro(402) and/or Pro(564) of HIF-1?. The similar structures but unique functions of FIH and PHD2 make them prime targets for selective inhibition leading to regulatory control of diseases such as cancer and stroke. Three classes of iron chelators were tested as inhibitors for FIH and PHD2: pyridines, hydroxypyrones/hydroxypyridinones and catechols. An initial screen of the ten small molecule inhibitors at varied [?KG] revealed a non-overlapping set of inhibitors for PHD2 and FIH. Dose response curves at moderate [?KG] ([?KG]~K(M)) showed that the hydroxypyrones/hydroxypyridinones were selective inhibitors, with IC(50) in the ?M range, and that the catechols were generally strong inhibitors of both FIH and PHD2, with IC(50) in the low ?M range. As support for binding at the active site of each enzyme as the mode of inhibition, electron paramagnetic resonance (EPR) spectroscopy were used to demonstrate inhibitor binding to the metal center of each enzyme. This work shows some selective inhibition between FIH and PHD2, primarily through the use of simple aromatic or pseudo-aromatic chelators, and suggests that hydroxypyrones and hydroxypyridones may be promising chelates for FIH or PHD2 inhibition.

| S-EPMC3525482 | biostudies-literature

The role of factor inhibiting HIF (FIH-1) in inhibiting HIF-1 transcriptional activity in glioblastoma multiforme.

Project description:Glioblastoma multiforme (GBM) accounts for about 38% of primary brain tumors in the United States. GBM is characterized by extensive angiogenesis induced by vascular growth factors and cytokines. The transcription of these growth factors and cytokines is regulated by the Hypoxia-Inducible-Factor-1(HIF-1), which is a key regulator mediating the cellular response to hypoxia. It is known that Factor Inhibiting HIF-1, or FIH-1, is also involved in the cellular response to hypoxia and has the capability to physically interact with HIF-1 and block its transcriptional activity under normoxic conditions. Delineation of the regulatory role of FIH-1 will help us to better understand the molecular mechanism responsible for tumor growth and progression and may lead to the design of new therapies targeting cellular pathways in response to hypoxia. Previous studies have shown that the chromosomal region of 10q24 containing the FIH-1 gene is often deleted in GBM, suggesting a role for the FIH-1 in GBM tumorigenesis and progression. In the current study, we found that FIH-1 is able to inhibit HIF-mediated transcription of GLUT1 and VEGF-A, even under hypoxic conditions in human glioblastoma cells. FIH-1 has been found to be more potent in inhibiting HIF function than PTEN. This observation points to the possibility that deletion of 10q23-24 and loss or decreased expression of FIH-1 gene may lead to a constitutive activation of HIF-1 activity, an alteration of HIF-1 targets such as GLUT-1 and VEGF-A, and may contribute to the survival of cancer cells in hypoxia and the development of hypervascularization observed in GBM. Therefore FIH-1 can be potential therapeutic target for the treatment of GBM patients with poor prognosis.

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FIH-1-Mint3 axis does not control HIF-1 transcriptional activity in nucleus pulposus cells.

Project description:The objective of this study was to determine the role of FIH-1 in regulating HIF-1 activity in the nucleus pulposus (NP) cells and the control of this regulation by binding and sequestration of FIH-1 by Mint3. FIH-1 and Mint3 were both expressed in the NP and were shown to strongly co-localize within the cell nucleus. Although both mRNA and protein expression of FIH-1 decreased in hypoxia, only Mint3 protein levels were hypoxiasensitive. Overexpression of FIH-1 was able to reduce HIF-1 function, as seen by changes in activities of hypoxia response element-luciferase reporter and HIF-1-C-TAD and HIF-2-TAD. Moreover, co-transfection of either full-length Mint3 or the N terminus of Mint3 abrogated FIH-1-dependent reduction in HIF-1 activity under both normoxia and hypoxia. Nuclear levels of FIH-1 and Mint3 decreased in hypoxia, and the use of specific nuclear import and export inhibitors clearly showed that cellular compartmentalization of overexpressed FIH-1 was critical for its regulation of HIF-1 activity in NP cells. Interestingly, microarray results after stable silencing of FIH-1 showed no significant changes in transcripts of classical HIF-1 target genes. However, expression of several other transcripts, including those of the Notch pathway, changed in FIH-1-silenced cells. Moreover, co-transfection of Notch-ICD could restore suppression of HIF-1-TAD activity by exogenous FIH-1. Taken together, these results suggest that, possibly due to low endogenous levels and/or preferential association with substrates such as Notch, FIH-1 activity does not represent a major mechanism by which NP cells control HIF-1-dependent transcription, a testament to their adaptation to a unique hypoxic niche.

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

Project description: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-1alpha subunit for ubiquitination and proteasomal degradation. The activity of the HIF-1alpha 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-1alpha 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-1alpha transactivation function by recruiting histone deacetylases. Involvement of VHL in association with FIH-1 provides a unifying mechanism for the modulation of HIF-1alpha protein stabilization and transcriptional activation in response to changes in cellular O(2) concentration.

| S-EPMC312814 | biostudies-literature

Posttranslational hydroxylation of ankyrin repeats in IkappaB proteins by the hypoxia-inducible factor (HIF) asparaginyl hydroxylase, factor inhibiting HIF (FIH).

Project description:Studies on hypoxia-sensitive pathways have revealed a series of Fe(II)-dependent dioxygenases that regulate hypoxia-inducible factor (HIF) by prolyl and asparaginyl hydroxylation. The recognition of these unprecedented signaling processes has led to a search for other substrates of the HIF hydroxylases. Here we show that the human HIF asparaginyl hydroxylase, factor inhibiting HIF (FIH), also efficiently hydroxylates specific asparaginyl (Asn)-residues within proteins of the IkappaB family. After the identification of a series of ankyrin repeat domain (ARD)-containing proteins in a screen for proteins interacting with FIH, the ARDs of p105 (NFKB1) and IkappaBalpha were shown to be efficiently hydroxylated by FIH at specific Asn residues in the hairpin loops linking particular ankyrin repeats. The target Asn residue is highly conserved as part of the ankyrin consensus, and peptides derived from a diverse range of ARD-containing proteins supported FIH enzyme activity. These findings demonstrate that this type of protein hydroxylation is not restricted to HIF and strongly suggest that FIH-dependent ARD hydroxylation is a common occurrence, potentially providing an oxygen-sensitive signal to a diverse range of processes.

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Uncoupled O2-activation in the human HIF-asparaginyl hydroxylase, FIH, does not produce reactive oxygen species.

Project description:The factor inhibiting HIF (FIH) is one of the primary oxygen sensors in human cells, controlling gene expression by hydroxylating the ?-subunit of the hypoxia inducible transcription factor (HIF). As FIH is an alpha-ketoglutarate dependent non-heme iron dioxygenase, oxygen activation is thought to precede substrate hydroxylation. The coupling between oxygen activation and substrate hydroxylation was hypothesized to be very tight, in order for FIH to fulfill its function as a regulatory enzyme. Coupling was investigated by looking for reactive oxygen species production during turnover. We used alkylsulfatase (AtsK), a metabolic bacterial enzyme with a related mechanism and similar turnover frequency, for comparison, and tested both FIH and AtsK for H(2)O(2), O(2)(-) and OH formation under steady and substrate-depleted conditions. Coupling ratios were determined by comparing the ratio of substrate consumed to product formed. We found that AtsK reacted with O(2) on the seconds timescale in the absence of prime substrate, and uncoupled during turnover to produce H(2)O(2); neither O(2)(-) nor OH were detected. In contrast, FIH was unreactive toward O(2) on the minutes timescale in the absence of prime substrate, and tightly coupled during steady-state turnover; we were unable to detect any reactive oxygen species produced by FIH. We also investigated the inactivation mechanisms of these enzymes and found that AtsK likely inactivated due to deoligomerizion, whereas FIH inactivated by slow autohydroxylation. Autohydroxylated FIH could not be reactivated by dithiothreitol (DTT) nor ascorbate, suggesting that autohydroxylation is likely to be irreversible under physiological conditions.

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Molecular and cellular mechanisms of HIF prolyl hydroxylase inhibitors in clinical trials.

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HIF prolyl-hydroxylase 2 is the key oxygen sensor setting low steady-state levels of HIF-1alpha in normoxia.

Project description:Hypoxia-inducible factor (HIF), a transcriptional complex conserved from Caenorhabditis elegans to vertebrates, plays a pivotal role in cellular adaptation to low oxygen availability. In normoxia, the HIF-alpha subunits are targeted for destruction by prolyl hydroxylation, a specific modification that provides recognition for the E3 ubiquitin ligase complex containing the von Hippel-Lindau tumour suppressor protein (pVHL). Three HIF prolyl-hydroxylases (PHD1, 2 and 3) were identified recently in mammals and shown to hydroxylate HIF-alpha subunits. Here we show that specific 'silencing' of PHD2 with short interfering RNAs is sufficient to stabilize and activate HIF-1alpha in normoxia in all the human cells investigated. 'Silencing' of PHD1 and PHD3 has no effect on the stability of HIF-1alpha either in normoxia or upon re-oxygenation of cells briefly exposed to hypoxia. We therefore conclude that, in vivo, PHDs have distinct assigned functions, PHD2 being the critical oxygen sensor setting the low steady-state levels of HIF-1alpha in normoxia. Interestingly, PHD2 is upregulated by hypoxia, providing an HIF-1-dependent auto-regulatory mechanism driven by the oxygen tension.

| S-EPMC175782 | biostudies-literature

Myeloperoxidase Modulates Hydrogen Peroxide Mediated Cellular Damage in Murine Macrophages.

Project description:Myeloperoxidase (MPO) is involved in the development of many chronic inflammatory diseases, in addition to its key role in innate immune defenses. This is attributed to the excessive production of hypochlorous acid (HOCl) by MPO at inflammatory sites, which causes tissue damage. This has sparked wide interest in the development of therapeutic approaches to prevent HOCl-induced cellular damage including supplementation with thiocyanate (SCN-) as an alternative substrate for MPO. In this study, we used an enzymatic system composed of glucose oxidase (GO), glucose, and MPO in the absence and presence of SCN-, to investigate the effects of generating a continuous flux of oxidants on macrophage cell function. Our studies show the generation of hydrogen peroxide (H2O2) by glucose and GO results in a dose- and time-dependent decrease in metabolic activity and cell viability, and the activation of stress-related signaling pathways. Interestingly, these damaging effects were attenuated by the addition of MPO to form HOCl. Supplementation with SCN-, which favors the formation of hypothiocyanous acid, could reverse this effect. Addition of MPO also resulted in upregulation of the antioxidant gene, NAD(P)H:quinone acceptor oxidoreductase 1. This study provides new insights into the role of MPO in the modulation of macrophage function, which may be relevant to inflammatory pathologies.

| S-EPMC7764223 | biostudies-literature

Factor inhibiting HIF (FIH) promotes lung cancer progression

Project description:Factor-inhibiting HIF (FIH) is an asparagine hydroxylase that acts on hypoxia-inducible factors (HIFs) to control cellular adaptation to hypoxia. FIH is expressed in several tumor types, but its impact in tumor progression remains largely unexplored. We observed that FIH was expressed on human lung cancer tissue. Deletion of FIH in mouse and human lung cancer cells resulted in an increased glycolytic metabolism, consistent with increased HIF activity. FIH-deficient lung cancer cells exhibited decreased proliferation. Analysis of RNA-Seq data confirmed changes in the cell cycle and survival and revealed molecular pathways that were dysregulated in the absence of FIH, including the upregulation of angiomotin (Amot), a key component of the Hippo tumor suppressor pathway. We show that FIH-deficient tumors were characterized by higher immune infiltration of NK and T cells compared with FIH competent tumor cells. In vivo studies demonstrate that FIH deletion resulted in reduced tumor growth and metastatic capacity. Moreover, high FIH expression correlated with poor overall survival in non-small cell lung cancer (NSCLC). Our data unravel FIH as a therapeutic target for the treatment of lung cancer.

2023-11-08 | GSE221505 | GEO

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