The human oxygen sensing machinery and its manipulation

Chowdhury, Rasheduzzaman; Hardy, Adam P.; Schofield, Christopher J.

doi:10.1039/b701676j

Cited by 95 publications

(90 citation statements)

References 59 publications

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“…The inactive analog D-NAME had no effect, ruling out the possibility that L-NAME is acting through some nonspecific mechanism. This suggests that the initial burst of superoxide caused by 20-HETE is generated by NOS, presumably by NOS uncoupling, as suggested by Cheng et al (12). Our results indicate that rapid superoxide generation induced by 20-HETE via NOS triggers a series of biochemical events, which are reflected in the changes in VEGF, NADPH oxidase activation, and HIF-1␣ upregulation.…”

Section: Discussionsupporting

confidence: 79%

“…In separate experiments, we confirmed that stimulation with exogenous VEGF leads to HIF-1␣ upregulation in the ECs that we used. Among the genes regulated by HIF, VEGF is one of the most important regulator of neovascularization responses by ECs and EC survival (12,18,19,29). The 20-HETE induction of HIF-1␣ expression requires the prior increases in VEGF synthesis and release.…”

Section: Discussionmentioning

confidence: 99%

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20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Guo

Scicli

Sheng

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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20-HETE increases the expression of VEGF in human dermal microvascular endothelial cells (ECs). Since VEGF is regulated by hypoxia inducible factor (HIF)-1, we studied whether 20-HETE also upregulates HIF-1α using the stable 20-HETE analog 20-hydroxyeicosa-5( Z),14( Z)dienoic acid (WIT003; 1–10 μM) and found that it induced a marked increase in HIF-1α protein levels. The increases in VEGF after the addition of WIT003 preceded the changes in HIF-1α, and the increases in HIF-1α were prevented by a VEGF neutralizing antibody. This suggests that 20-HETE first causes increases in VEGF, which then, in turn, cause the upregulation of HIF-1α. Stimulation with exogenously added VEGF also led to an upregulation of HIF-1α. Incubation with the MEK1/ERK1/2 inhibitor U-0126 (10 μM) completely abolished the increases in VEGF and thus HIF-1α, suggesting the involvement of ERK1/2 activation. The addition of WIT003 resulted in a rapid and sustained increase in superoxide formation. When WIT003 was added in the presence of the nitric oxide (NO) synthase (NOS) inhibitor N-nitro-l-arginine, no changes in superoxide, VEGF, or HIF-1α were observed. This suggests that NOS is responsible for the early changes in superoxide induced by WIT003. Furthermore, WIT003 induced the expression of the NADPH oxidase subunit p47 phox in ECs before the increases in HIF-1α. Incubation with polyethylene glycol-superoxide dismutase (400 U/ml), apocynin (100 μM), diphenylene iodonium (10 μM), or p47 phox downregulation with small interfering (si)RNA all inhibited the increases in HIF-1α expression. This indicates that the early changes in superoxide lead to VEGF increases and thereby NADPH oxidase-dependent superoxide production, which is required for HIF-1α upregulation. We also found that the higher HIF-1α expression induced by WIT003 was accompanied by higher expression of erythropoietin receptor and angiopoietin-2 proteins. These increases were caused by HIF-1α because their levels were markedly decreased by siRNA downregulation of HIF-1α. 20-HETE may be a novel nonhypoxic regulator of HIF-1α and HIF-1α-regulated genes in ECs.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Guo

Scicli

Sheng

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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“…Under normoxic conditions, the HIF-1␣ subunit is synthesized and subjected to hydroxylation on proline residue 402 and/or 564 by prolyl hydroxylase domain (PHD) proteins (principally PHD2) that use O 2 and ␣-ketoglutarate as substrates (FIGURE 1A) to catalyze a dioxygenase reaction in which one oxygen atom is inserted into the proline residue and the other oxygen atom is inserted into ␣-ketoglutarate to form succinate and CO 2 (12,30). The protein OS-9 binds to both PHD2 and HIF-1␣, thereby facilitating hydroxylation (4).…”

Section: Continuous Hypoxiamentioning

confidence: 99%

Regulation of Oxygen Homeostasis by Hypoxia-Inducible Factor 1

2009

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Metazoan organisms are dependent on a continuous supply of O2 for survival. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that regulates oxygen homeostasis and plays key roles in development, physiology, and disease. HIF-1 activity is induced in response to continuous hypoxia, intermittent hypoxia, growth factor stimulation, and Ca2+ signaling. HIF-1 mediates adaptive responses to hypoxia, including erythropoiesis, angiogenesis, and metabolic reprogramming. In each case, HIF-1 regulates the expression of multiple genes encoding key components of the response pathway. HIF-1 also mediates maladaptive responses to chronic continuous and intermittent hypoxia, which underlie the development of pulmonary and systemic hypertension, respectively.

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“…Plant P4Hs have a ϳ30% sequence identity to the catalytic domain of the C-P4H ␣-subunits (11,12), and they also resemble C-P4Hs in that they hydroxylate proline-rich polypeptides and are located in the lumen of the endoplasmic reticulum (2). HIF-P4Hs, on the other hand, are cytoplasmic and nuclear enzymes (8,9) that act on proline residues in -Leu-X-X-Leu-Ala-Pro-motifs in HIF-␣ (13,14). C-P4Hs hydroxylate the central proline of the -X-Pro-Gly-repeats of collagen polypeptides, typically generating about 100 4Hyp residues in polypeptides with a length of about 1000 amino acids.…”

Section: R-hydroxyproline (4hyp)mentioning

confidence: 99%

The Crystal Structure of an Algal Prolyl 4-Hydroxylase Complexed with a Proline-rich Peptide Reveals a Novel Buried Tripeptide Binding Motif

Koski

Hieta

Hirsilä

et al. 2009

Journal of Biological Chemistry

128

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Plant and algal prolyl 4-hydroxylases (P4Hs) are key enzymes in the synthesis of cell wall components. These monomeric enzymes belong to the 2-oxoglutarate dependent superfamily of enzymes characterized by a conserved jelly-roll framework. This algal P4H has high sequence similarity to the catalytic domain of the vertebrate, tetrameric collagen P4Hs, whereas there are distinct sequence differences with the oxygen-sensing hypoxia-inducible factor P4H subfamily of enzymes. We present here a 1.98-Å crystal structure of the algal Chlamydomonas reinhardtii P4H-1 complexed with Zn 2؉ and a proline-rich (SerPro) 5 substrate. This ternary complex captures the competent mode of binding of the peptide substrate, being bound in a lefthanded (poly)L-proline type II conformation in a tunnel shaped by two loops. These two loops are mostly disordered in the absence of the substrate. The importance of these loops for the function is confirmed by extensive mutagenesis, followed up by enzyme kinetic characterizations. These loops cover the central Ser-Pro-Ser tripeptide of the substrate such that the hydroxylation occurs in a highly buried space. This novel mode of binding does not depend on stacking interactions of the proline side chains with aromatic residues. Major conformational changes of the two peptide binding loops are predicted to be a key feature of the catalytic cycle. These conformational changes are probably triggered by the conformational switch of Tyr 140 , as induced by the hydroxylation of the proline residue. The importance of these findings for understanding the specific binding and hydroxylation of (X-Pro-Gly) n sequences by collagen P4Hs is also discussed.

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The human oxygen sensing machinery and its manipulation

Cited by 95 publications

References 59 publications

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

20-HETE can act as a nonhypoxic regulator of HIF-1α in human microvascular endothelial cells

Regulation of Oxygen Homeostasis by Hypoxia-Inducible Factor 1

The Crystal Structure of an Algal Prolyl 4-Hydroxylase Complexed with a Proline-rich Peptide Reveals a Novel Buried Tripeptide Binding Motif

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