scholarly journals Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibition: Robust New Target or Another Big Bust for Stroke Therapeutics?

2012 ◽  
Vol 32 (7) ◽  
pp. 1347-1361 ◽  
Author(s):  
Saravanan S Karuppagounder ◽  
Rajiv R Ratan
Keyword(s):  
Oxidative Stress ◽  
Functional Outcomes ◽  
Hemorrhagic Stroke ◽  
Hypoxia Inducible Factor ◽  
Iron Chelators ◽  
Adaptation To Hypoxia ◽  
Prolyl Hydroxylases ◽  
Stroke Models ◽  
Transcriptional Adaptation ◽  
Compensatory Programs

A major challenge in developing stroke therapeutics that augment adaptive pathways to stress has been to identify targets that can activate compensatory programs without inducing or adding to the stress of injury. In this regard, hypoxia-inducible factor prolyl hydroxylases (HIF PHDs) are central gatekeepers of posttranscriptional and transcriptional adaptation to hypoxia, oxidative stress, and excitotoxicity. Indeed, some of the known salutary effects of putative ‘antioxidant’ iron chelators in ischemic and hemorrhagic stroke may derive from their abilities to inhibit this family of iron, 2-oxoglutarate, and oxygen-dependent enzymes. Evidence from a number of laboratories supports the notion that HIF PHD inhibition can improve histological and functional outcomes in ischemic and hemorrhagic stroke models. In this review, we discuss this evidence and highlight important gaps in our understanding that render HIF PHD inhibition a promising but not yet preclinically validated target for protection and repair after stroke.

scholarly journals Carboxyl-Terminal Transactivation Activity of Hypoxia-Inducible Factor 1α Is Governed by a von Hippel-Lindau Protein-Independent, Hydroxylation-Regulated Association with p300/CBP

2002 ◽  
Vol 22 (9) ◽  
pp. 2984-2992 ◽  
Author(s):  
Nianli Sang ◽  
Jie Fang ◽  
Vickram Srinivas ◽  
Irene Leshchinsky ◽  
Jaime Caro
Keyword(s):  
Hypoxia Inducible Factor ◽  
Adaptation To Hypoxia ◽  
Physical Interaction ◽  
Prolyl Hydroxylases ◽  
Von Hippel Lindau ◽  
Hypoxia Inducible Factor 1 ◽  
Transactivation Activity ◽  
Oxygen Homeostasis ◽  
Stimulation Of

ABSTRACT Hypoxia-inducible factor 1 complex (HIF-1) plays a pivotal role in oxygen homeostasis and adaptation to hypoxia. Its function is controlled by both the protein stability and the transactivation activity of its alpha subunit, HIF-1α. Hydroxylation of at least two prolyl residues in the oxygen-dependent degradation domain of HIF-1α regulates its interaction with the von Hippel-Lindau protein (VHL) that targets HIF-1α for ubiquitination and proteasomal degradation. Several prolyl hydroxylases have been found to specifically hydroxylate HIF-1α. In this report, we investigated possible roles of VHL and hydroxylases in the regulation of the transactivation activity of the C-terminal activating domain (CAD) of HIF-1α. We demonstrate that regulation of the transactivation activity of HIF-1α CAD also involves hydroxylase activity but does not require functional VHL. In addition, stimulation of the CAD activity by a hydoxylase inhibitor, hypoxia, and desferrioxamine was severely blocked by the adenoviral oncoprotein E1A but not by an E1A mutant defective in targeting p300/CBP. We further demonstrate that a hydroxylase inhibitor, hypoxia, and desferrioxamine promote the functional and physical interaction between HIF-1α CAD and p300/CBP in vivo. Taken together, our data provide evidence that hypoxia-regulated stabilization and transcriptional stimulation of HIF-1α function are regulated through partially overlapping but distinguishable pathways.

Hypoxia. 1. Intracellular sensors for oxygen and oxidative stress: novel therapeutic targets

2011 ◽  
Vol 300 (2) ◽  
pp. C226-C231 ◽  
Author(s):  
Toshio Miyata ◽  
Shunya Takizawa ◽  
Charles van Ypersele de Strihou
Keyword(s):  
Oxidative Stress ◽  
Defense Mechanisms ◽  
Tissue Injury ◽  
Hypoxia Inducible Factor ◽  
Oxygen Metabolism ◽  
Related Factor ◽  
Novel Therapy ◽  
Prolyl Hydroxylases ◽  
Hypoxic Tolerance ◽  
And Oxidative Stress

A variety of human disorders, e.g., ischemic heart disease, stroke, kidney disease, eventually share the deleterious consequences of a common, hypoxic and oxidative stress pathway. In this review, we utilize recent information on the cellular defense mechanisms against hypoxia and oxidative stress with the hope to propose new therapeutic tools. The hypoxia-inducible factor (HIF) is a key player as it activates a broad range of genes protecting cells against hypoxia. Its level is determined by its degradation rate by intracellular oxygen sensors prolyl hydroxylases (PHDs). There are three different PHD isoforms (PHD1–3). Small molecule PHD inhibitors improve hypoxic injury in experimental animals but, unfortunately, may induce adverse effects associated with PHD2 inhibition, e.g., angiogenesis. As yet, no inhibitor specific for a distinct PHD isoform is currently available. Still, the specific disruption of the PHD1 gene is known to induce hypoxic tolerance, without angiogenesis and erythrocytosis, by reprogramming basal oxygen metabolism with an attendant decreased oxidative stress in hypoxic mitochondria. A specific PHD1 inhibitor might therefore offer a novel therapy against hypoxia. The nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) regulates the basal and inducible expression of numerous antioxidant stress genes. Disruption of its gene exacerbates oxidative tissue injury. Nrf2 activity is modulated by Kelch-like ECH-associated protein 1 (Keap1), an intracellular sensor for oxidative stress. Inhibitors of Keap 1 may prove therapeutic against oxidative tissue injury.

scholarly journals Competitive HIF Prolyl Hydroxylase Inhibitors Show Protection against Oxidative Stress by a Mechanism Partially Dependent on Glycolysis

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ann-Louise Bergström ◽  
Karina Fog ◽  
Thomas Nikolaj Sager ◽  
Anne Techau Bruun ◽  
Kenneth Thirstrup
Keyword(s):  
Oxidative Stress ◽  
Hypoxia Inducible Factor ◽  
Large Degree ◽  
Cell Types ◽  
Prolyl Hydroxylase ◽  
Adaptation To Hypoxia ◽  
Cellular Effects ◽  
Competitive Inhibitors ◽  
Inhibitor Compounds ◽  
Hif Prolyl Hydroxylase

The hypoxia inducible factor 1 (HIF-1) is a central transcription factor involved in the cellular and molecular adaptation to hypoxia and low glucose supply. The level of HIF-1 is to a large degree regulated by the HIF prolyl hydroxylase enzymes (HPHs) belonging to the Fe(II) and 2-oxoglutarate-dependent dioxygenase superfamily. In the present study, we compared competitive and noncompetitive HPH-inhibitor compounds in two different cell types (SH-SY5Y and PC12). Although the competitive HPH-inhibitor compounds were found to be pharmacologically more potent than the non-competitive compounds at inhibiting HPH2 and HPH1, this was not translated into the cellular effects of the compounds, where the non-competitive inhibitors were actually more potent than the competitive in stabilizing and translocatingHIF1αto the nucleus (quantified with Cellomics ArrayScan technology). This could be explained by the high cellular concentrations of the cofactor 2-oxoglutarate (2-OG) as the competitive inhibitors act by binding to the 2-OG site of the HPH enzymes. Both competitive and non-competitive HPH inhibitors protected the cells against 6-OHDA induced oxidative stress. In addition, the protective effect of a specific HPH inhibitor was partially preserved when the cells were serum starved and exposed to 2-deoxyglucose, an inhibitor of glycolysis, indicating that other processes than restoring energy supply could be important for the HIF-mediated cytoprotection.

scholarly journals Roles of HIF and 2-Oxoglutarate-Dependent Dioxygenases in Controlling Gene Expression in Hypoxia

Cancers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 350
Author(s):  
Julianty Frost ◽  
Mark Frost ◽  
Michael Batie ◽  
Hao Jiang ◽  
Sonia Rocha
Keyword(s):  
Gene Expression ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Regulator ◽  
Hydroxylase Activity ◽  
Control Of Gene Expression ◽  
Prolyl Hydroxylases ◽  
Chromatin Organisation ◽  
Sense And Respond ◽  
Almost All ◽  
And Function

Hypoxia—reduction in oxygen availability—plays key roles in both physiological and pathological processes. Given the importance of oxygen for cell and organism viability, mechanisms to sense and respond to hypoxia are in place. A variety of enzymes utilise molecular oxygen, but of particular importance to oxygen sensing are the 2-oxoglutarate (2-OG) dependent dioxygenases (2-OGDs). Of these, Prolyl-hydroxylases have long been recognised to control the levels and function of Hypoxia Inducible Factor (HIF), a master transcriptional regulator in hypoxia, via their hydroxylase activity. However, recent studies are revealing that dioxygenases are involved in almost all aspects of gene regulation, including chromatin organisation, transcription and translation. We highlight the relevance of HIF and 2-OGDs in the control of gene expression in response to hypoxia and their relevance to human biology and health.

scholarly journals Association of EGLN1 gene with high aerobic capacity of Peruvian Quechua at high altitude

2019 ◽  
Vol 116 (48) ◽  
pp. 24006-24011 ◽  
Author(s):  
Tom D. Brutsaert ◽  
Melisa Kiyamu ◽  
Gianpietro Elias Revollendo ◽  
Jenna L. Isherwood ◽  
Frank S. Lee ◽  
...  
Keyword(s):  
Natural Selection ◽  
Aerobic Capacity ◽  
Cellular Response ◽  
Hypoxia Inducible Factor ◽  
Total Sample ◽  
Causal Variant ◽  
Analysis Of Covariance ◽  
Adaptation To Hypoxia ◽  
Spurious Association ◽  
Factor Α

Highland native Andeans have resided at altitude for millennia. They display high aerobic capacity (VO2max) at altitude, which may be a reflection of genetic adaptation to hypoxia. Previous genomewide (GW) scans for natural selection have nominated Egl-9 homolog 1 gene (EGLN1) as a candidate gene. The encoded protein, EGLN1/PHD2, is an O2 sensor that controls levels of the Hypoxia Inducible Factor-α (HIF-α), which regulates the cellular response to hypoxia. From GW association and analysis of covariance performed on a total sample of 429 Peruvian Quechua and 94 US lowland referents, we identified 5 EGLN1 SNPs associated with higher VO2max (L⋅min−1 and mL⋅min−1⋅kg−1) in hypoxia (rs1769793, rs2064766, rs2437150, rs2491403, rs479200). For 4 of these SNPs, Quechua had the highest frequency of the advantageous (high VO2max) allele compared with 25 diverse lowland comparison populations from the 1000 Genomes Project. Genotype effects were substantial, with high versus low VO2max genotype categories differing by ∼11% (e.g., for rs1769793 SNP genotype TT = 34.2 mL⋅min−1⋅kg−1 vs. CC = 30.5 mL⋅min−1⋅kg−1). To guard against spurious association, we controlled for population stratification. Findings were replicated for EGLN1 SNP rs1769793 in an independent Andean sample collected in 2002. These findings contextualize previous reports of natural selection at EGLN1 in Andeans, and support the hypothesis that natural selection has increased the frequency of an EGLN1 causal variant that enhances O2 delivery or use during exercise at altitude in Peruvian Quechua.

scholarly journals Hypoxia-inducible factor prolyl hydroxylases as targets for neuroprotection by “antioxidant” metal chelators: From ferroptosis to stroke

2013 ◽  
Vol 62 ◽  
pp. 26-36 ◽  
Author(s):  
Rachel E. Speer ◽  
Saravanan S. Karuppagounder ◽  
Manuela Basso ◽  
Sama F. Sleiman ◽  
Amit Kumar ◽  
...  
Keyword(s):  
Hypoxia Inducible Factor ◽  
Metal Chelators ◽  
Prolyl Hydroxylases

Biochemical characterization of human HIF hydroxylases using HIF protein substrates that contain all three hydroxylation sites

2011 ◽  
Vol 436 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Melissa B. Pappalardi ◽  
Dean E. McNulty ◽  
John D. Martin ◽  
Kelly E. Fisher ◽  
Yong Jiang ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Hypoxia Inducible Factor ◽  
Prolyl Hydroxylase ◽  
Transactivation Domain ◽  
Prolyl Hydroxylases ◽  
Proline Residue ◽  
Protein Substrates ◽  
Steady State Kinetic ◽  
Asparaginyl Hydroxylase

The HIF (hypoxia-inducible factor) plays a central regulatory role in oxygen homoeostasis. HIF proteins are regulated by three Fe(II)- and α-KG (α-ketoglutarate)-dependent prolyl hydroxylase enzymes [PHD (prolyl hydroxylase domain) isoenzymes 1–3 or PHD1, PHD2 and PHD3] and one asparaginyl hydroxylase [FIH (factor inhibiting HIF)]. The prolyl hydroxylases control the abundance of HIF through oxygen-dependent hydroxylation of specific proline residues in HIF proteins, triggering subsequent ubiquitination and proteasomal degradation. FIH inhibits the HIF transcription activation through asparagine hydroxylation. Understanding the precise roles and regulation of these four Fe(II)- and α-KG-dependent hydroxylases is of great importance. In the present paper, we report the biochemical characterization of the first HIF protein substrates that contain the CODDD (C-terminal oxygen-dependent degradation domain), the NODDD (N-terminal oxygen-dependent degradation domain) and the CAD (C-terminal transactivation domain). Using LC-MS/MS (liquid chromatography–tandem MS) detection, we show that all three PHD isoenzymes have a strong preference for hydroxylation of the CODDD proline residue over the NODDD proline residue and the preference is observed for both HIF1α and HIF2α protein substrates. In addition, steady-state kinetic analyses show differential substrate selectivity for HIF and α-KG in reference to the three PHD isoforms and FIH.

Abstract TP102: Modulation of Neuroinflammation by Haptoglobin Reduces Oxidative Stress and Improves ICH Outcomes

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Jenna Leclerc ◽  
Alex Dang ◽  
Juan Santiago-Moreno ◽  
Sylvain Dore
Keyword(s):  
Oxidative Stress ◽  
Heme Oxygenase ◽  
Functional Outcomes ◽  
Ferric Iron ◽  
Heme Oxygenase 1 ◽  
High Morbidity ◽  
Blood Components ◽  
Autologous Whole Blood ◽  
The Brain ◽  
Histological Staining

Intracerebral hemorrhage (ICH) is a stroke subtype associated with high morbidity and mortality. With breakdown of the blood-brain barrier and entry of toxic blood components and metabolites within the brain, a highly oxidative environment ensues and leads to a toxic neuroinflammatory cascade. A major cause of the debilitation following brain hemorrhage is due to the direct toxicity of blood components, notably hemoglobin (Hb), the most upstream precipitating factor in the cascade. The acute phase plasma protein haptoglobin (Hp) binds Hb and inhibits its cytotoxic, pro-oxidative, and pro-inflammatory properties. In this study, we investigated whether the local and specific overexpression of Hp would aid in the safe detoxification and clearance of free Hb, thereby protecting the neuropil from Hb-mediated oxidative stress and improving ICH outcomes. Hp was overexpressed locally within the brain using uniquely designed adeno-associated viral vectors and ICH was induced using the intrastriatal autologous whole blood injection model. Functional outcomes were assessed by a 24-point neurological deficit score. At 72h post-hemorrhage, mice were sacrificed and brains collected for histological staining. Hp-overexpressing mice demonstrated smaller lesion volumes (p<0.05) with less blood accumulation (p<0.05) and improve neurologic status after ICH (p<0.05) when compared to an identically treated control group (n=11-13/group). Histological staining for Iba-1, GFAP, heme oxygenase-1, 4-hydroxynonenal, ferric iron, and myeloperoxidase was performed and revealed: 1) significantly less heme oxygenase-1 expression and lipid peroxidation, 2) a trend towards reduced peripheral neutrophil infiltration, 3) significantly increased cortical microgliosis and cortical and striatal astrogliosis, and 4) no changes in ferric iron content or striatal microgliosis. In conclusion, Hp overexpression in the brain reduces ICH-induced brain injury and improves functional outcomes. Locally modulating brain Hp levels could represent an important clinically relevant strategy for the treatment of ICH.

Toxicity assessment of metallic nickel nanoparticles in various biological models: An interplay of reactive oxygen species, oxidative stress, and apoptosis

2021 ◽  
pp. 074823372110110
Author(s):  
Shabnoor Iqbal ◽  
Farhat Jabeen ◽  
Abdul Shakoor Chaudhry ◽  
Muhammad Ajmal Shah ◽  
Gaber El-Saber Batiha
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Nickel Nanoparticles ◽  
Hypoxia Inducible Factor ◽  
Reactive Oxygen Species Generation ◽  
Reactive Oxygen ◽  
Volume Ratio ◽  
Nuclear Factor Κb ◽  
Metallic Nickel ◽  
Oxygen Species

Nickel nanoparticles (Ni-NPs) are widely used for multiple purposes in industries. Ni-NPs exposure is detrimental to ecosystems owing to widespread use, and so their toxicity is important to consider for real-world applications. This review mainly focuses on the notable pathophysiological activities of Ni-NPs in various research models. Ni-NPs are stated to be more toxic than bulk forms because of their larger surface area to volume ratio and are reported to provoke toxicity through reactive oxygen species generation, which leads to the upregulation of nuclear factor-κB and promotes further signaling cascades. Ni-NPs may contribute to provoking oxidative stress and apoptosis. Hypoxia-inducible factor 1α and mitogen-activated protein kinases pathways are involved in Ni-NPs associated toxicity. Ni-NPs trigger the transcription factors p-p38, p-JNK, p-ERK1/2, interleukin (IL)-3, TNF-α, IL-13, Fas, Cyt c, Bax, Bid protein, caspase-3, caspase-8, and caspase-9. Moreover, Ni-NPs have an occupational vulnerability and were reported to induce lung-related disorders owing to inhalation. Ni-NPs may cause serious effects on reproduction as Ni-NPs induced deleterious effects on reproductive cells (sperm and eggs) in animal models and provoked hormonal alteration. However, recent studies have provided limited knowledge regarding the important checkpoints of signaling pathways and less focused on the toxic limitation of Ni-NPs in humans, which therefore needs to be further investigated.

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