scholarly journals Placental but Not Heart Defects Are Associated with Elevated Hypoxia-Inducible Factor α Levels in Mice Lacking Prolyl Hydroxylase Domain Protein 2

2006 ◽  
Vol 26 (22) ◽  
pp. 8336-8346 ◽  
Author(s):  
Kotaro Takeda ◽  
Vivienne C. Ho ◽  
Hiromi Takeda ◽  
Li-Juan Duan ◽  
Andras Nagy ◽  
...  
Keyword(s):  
Heart Defects ◽  
Interventricular Septum ◽  
Hypoxia Inducible Factor ◽  
Giant Cells ◽  
Branching Morphogenesis ◽  
Mouse Development ◽  
Protein Levels ◽  
The Stability ◽  
Factor Α ◽  
Trophoblast Giant Cells

ABSTRACT PHD1, PHD2, and PHD3 are prolyl hydroxylase domain proteins that regulate the stability of hypoxia-inducible factor α subunits (HIF-α). To determine the roles of individual PHDs during mouse development, we disrupted all three Phd genes and found that Phd2 − / − embryos died between embryonic days 12.5 and 14.5 whereas Phd1 −/− or Phd3 −/− mice were apparently normal. In Phd2 − / − mice, severe placental and heart defects preceded embryonic death. Placental defects included significantly reduced labyrinthine branching morphogenesis, widespread penetration of the labyrinth by spongiotrophoblasts, and abnormal distribution of trophoblast giant cells. The expression of several trophoblast markers was also altered, including an increase in the spongiotrophoblast marker Mash2 and decreases in the labyrinthine markers Tfeb and Gcm1. In the heart, trabeculae were poorly developed, the myocardium was remarkably thinner, and interventricular septum was incompletely formed. Surprisingly, while there were significant global increases in HIF-α protein levels in the placenta and the embryo proper, there was no specific HIF-α increase in the heart. Taken together, these data indicate that among all three PHD proteins, PHD2 is uniquely essential during mouse embryogenesis.

scholarly journals HIF1α/TET1 Pathway Mediates Hypoxia-Induced Adipocytokine Promoter Hypomethylation in Human Adipocytes

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 134 ◽  
Author(s):  
Mohamed M. Ali ◽  
Shane A. Phillips ◽  
Abeer M. Mahmoud
Keyword(s):  
Dna Methylation ◽  
Interleukin 1 ◽  
Hypoxia Inducible Factor ◽  
Interferon Γ ◽  
The Body ◽  
Human Adipocytes ◽  
Protein Levels ◽  
Factor Α ◽  
Necrosis Factor

Obesity is associated with the accumulation of dysfunctional adipose tissue that secretes several pro-inflammatory cytokines (adipocytokines). Recent studies have presented evidence that adipose tissues in obese individuals and animal models are hypoxic, which may result in upregulation and stabilization of the hypoxia inducible factor HIF1α. Epigenetic mechanisms such as DNA methylation enable the body to respond to microenvironmental changes such as hypoxia and may represent a mechanistic link between obesity-associated hypoxia and upregulated inflammatory adipocytokines. The purpose of this study was to investigate the role of hypoxia in modifying adipocytokine DNA methylation and subsequently adipocytokine expression. We suggested that this mechanism is mediated via the DNA demethylase, ten-eleven translocation-1 (TET1), transcription of which has been shown to be induced by HIF1α. To this end, we studied the effect of hypoxia (2% O2) in differentiated subcutaneous human adipocytes in the presence or absence of HIF1α stabilizer (Dimethyloxalylglycine (DMOG), 500 μM), HIF1α inhibitor (methyl 3-[[2-[4-(2-adamantyl) phenoxy] acetyl] amino]-4-hydroxybenzoate, 30 μM), or TET1-specific siRNA. Subjecting the adipocytes to hypoxia significantly induced HIF1α and TET1 protein levels. Moreover, hypoxia induced global hydroxymethylation, reduced adipocytokine DNA promoter methylation, and induced adipocytokine expression. These effects were abolished by either HIF1α inhibitor or TET1 gene silencing. The major hypoxia-responsive adipocytokines were leptin, interleukin-1 (IL6), IL1β, tumor necrosis factor α (TNFα), and interferon γ (IFNγ). Overall, these data demonstrate an activation of the hydroxymethylation pathway mediated by TET1. This pathway contributes to promoter hypomethylation and gene upregulation of the inflammatory adipocytokines in adipocytes in response to hypoxia.

scholarly journals Neuroprotection by Dimethyloxalylglycine following Permanent and Transient Focal Cerebral Ischemia in Rats

2010 ◽  
Vol 31 (1) ◽  
pp. 132-143 ◽  
Author(s):  
Simon Nagel ◽  
Michalis Papadakis ◽  
Ruoli Chen ◽  
Lisa C Hoyte ◽  
Keith J Brooks ◽  
...  
Keyword(s):  
Focal Cerebral Ischemia ◽  
Hypoxia Inducible Factor ◽  
Artery Occlusion ◽  
Protein Levels ◽  
Transient Focal Cerebral Ischemia ◽  
Before And After ◽  
Magnetic Resonance Imaging Mri ◽  
The Stability ◽  
Endothelial Growth Factor ◽  
Endothelial Nitric Oxide

Dimethyloxalylglycine (DMOG) is an inhibitor of prolyl-4-hydroxylase domain (PHD) enzymes that regulate the stability of hypoxia-inducible factor (HIF). We investigated the effect of DMOG on the outcome after permanent and transient middle cerebral artery occlusion (p/tMCAO) in the rat. Before and after pMCAO, rats were treated with 40 mg/kg, 200 mg/kg DMOG, or vehicle, and with 40 mg/kg or vehicle after tMCAO. Serial magnetic resonance imaging (MRI) was performed to assess infarct evolution and regional cerebral blood flow (rCBF). Both doses significantly reduced infarct volumes, but only 40 mg/kg improved the behavior after 24 hours of pMCAO. Animals receiving 40 mg/kg were more likely to maintain rCBF values above 30% from the contralateral hemisphere within 24 hours of pMCAO. DMOG after tMCAO significantly reduced the infarct volumes and improved behavior at 24 hours and 8 days and also improved the rCBF after 24 hours. A consistent and significant upregulation of both mRNA and protein levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) was associated with the observed neuroprotection, although this was not consistently related to HIF-1α levels at 24 hours and 8 days. Thus, DMOG afforded neuroprotection both at 24 hours after pMCAO and at 24 hours and 8 days after tMCAO. This effect was associated with an increase of VEGF and eNOS and was mediated by improved rCBF after DMOG treatment.

Effect of chemical stabilizers of hypoxia-inducible factors on early lung development

2007 ◽  
Vol 293 (3) ◽  
pp. L557-L567 ◽  
Author(s):  
Freek A. Groenman ◽  
Martin Rutter ◽  
Jinxia Wang ◽  
Isabella Caniggia ◽  
Dick Tibboel ◽  
...  
Keyword(s):  
Lung Development ◽  
Hypoxia Inducible Factor ◽  
Iron Chelator ◽  
Branching Morphogenesis ◽  
Vegf Receptor ◽  
Low Oxygen ◽  
Prolyl Hydroxylases ◽  
Protein Levels ◽  
Terminal Buds ◽  
Airway Branching

Low oxygen stimulates pulmonary vascular development and airway branching and involves hypoxia-inducible factor (HIF). HIF is stable and initiates expression of angiogenic factors under hypoxia, whereas normoxia triggers hydroxylation of the HIF-1α subunit by prolyl hydroxylases (PHDs) and subsequent degradation. Herein, we investigated whether chemical stabilization of HIF-1α under normoxic (20% O2) conditions would stimulate vascular growth and branching morphogenesis in early lung explants. Tie2-LacZ (endothelial LacZ marker) mice were used for visualization of the vasculature. Embryonic day 11.5 (E11.5) lung buds were dissected and cultured in 20% O2 in the absence or presence of cobalt chloride (CoCl2, a hypoxia mimetic), dimethyloxalylglycine (DMOG; a nonspecific inhibitor of PHDs), or desferrioxamine (DFO; an iron chelator). Vascularization was assessed by X-gal staining, and terminal buds were counted. The fine vascular network surrounding the developing lung buds seen in control explants disappeared in CoCl2- and DFO-treated explants. Also, epithelial branching was reduced in the explants treated with CoCl2 and DFO. In contrast, DMOG inhibited branching but stimulated vascularization. Both DFO and DMOG increased nuclear HIF-1α protein levels, whereas CoCl2 had no effect. Since HIF-1α induces VEGF expression, the effect of SU-5416, a potent VEGF receptor (VEGFR) blocker, on early lung development was also investigated. Inhibition of VEGFR2 signaling in explants maintained under hypoxic (2% O2) conditions completely abolished vascularization and slightly decreased epithelial branching. Taken together, the data suggest that DMOG stabilization of HIF-1α during early development leads to a hypervascular lung and that airway branching proceeds without the vasculature, albeit at a slower rate.

scholarly journals Identification of a region on hypoxia-inducible-factor prolyl 4-hydroxylases that determines their specificity for the oxygen degradation domains

2007 ◽  
Vol 408 (2) ◽  
pp. 231-240 ◽  
Author(s):  
Diego Villar ◽  
Alicia Vara-Vega ◽  
Manuel O. Landázuri ◽  
Luis Del Peso
Keyword(s):  
Transcription Factors ◽  
Tertiary Structure ◽  
Hypoxia Inducible Factor ◽  
Domain Swapping ◽  
Dependent Manner ◽  
Low Oxygen ◽  
Protein Levels ◽  
The Stability

HIFs [hypoxia-inducible (transcription) factors] are essential for the induction of an adaptive gene expression programme under low oxygen partial pressure. The activity of these transcription factors is mainly determined by the stability of the HIFα subunit, which is regulated, in an oxygen-dependent manner, by a family of three prolyl 4-hydroxylases [EGLN1–EGLN3 (EGL nine homologues 1–3)]. HIFα contains two, N- and C-terminal, independent ODDs (oxygen-dependent degradation domains), namely NODD and CODD, that, upon hydroxylation by the EGLNs, target HIFα for proteasomal degradation. In vitro studies indicate that each EGLN shows a differential preference for ODDs, However, the sequence determinants for such specificity are unknown. In the present study we showed that whereas EGLN1 and EGLN2 acted upon any of these ODDs to regulate HIF1α protein levels and activity in vivo, EGLN3 only acted on the CODD. With the aim of identifying the region within EGLNs responsible for their differential substrate preference, we investigated the activity and binding pattern of different EGLN deletions and chimaeric constructs generated by domain swapping between EGLN1 and EGLN3. These studies revealed a region of 97 residues that was sufficient to confer the characteristic substrate binding observed for each EGLN. Within this region, we identified the minimal sequence (EGLN1 residues 236–252) involved in substrate discrimination. Importantly, mapping of these sequences on the EGLN1 tertiary structure indicates that substrate specificity is determined by a region relatively remote from the catalytic site.

Trophoblast giant cells express NF-?B2 during early mouse development

1999 ◽  
Vol 25 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Anna Muggia ◽  
Tambet Teesalu ◽  
Antonino Neri ◽  
Francesco Blasi ◽  
Daniela Talarico
Keyword(s):  
Giant Cells ◽  
Mouse Development ◽  
Early Mouse ◽  
Trophoblast Giant Cells

scholarly journals Deficiency in the p110α subunit of PI3K results in diminished Tie2 expression and Tie2-/-–like vascular defects in mice

Blood ◽  
2005 ◽  
Vol 105 (10) ◽  
pp. 3935-3938 ◽  
Author(s):  
Etienne Lelievre ◽  
Pierre-Marie Bourbon ◽  
Li-Juan Duan ◽  
Robert L. Nussbaum ◽  
Guo-Hua Fong
Keyword(s):  
Tyrosine Kinases ◽  
Branching Morphogenesis ◽  
Vascular Endothelial ◽  
Mouse Development ◽  
Protein Levels ◽  
Upstream Regulator ◽  
Phosphoinositide 3 Kinase ◽  
Endothelial Growth Factor

AbstractPhosphoinositide 3-kinase (PI3K) is activated by transmembrane tyrosine kinases such as vascular endothelial growth factor (VEGF) receptors and Tie2 (tunica intima endothelial kinase 2), both of which are key regulators of vascular development. However, the in vivo role of PI3K during developmental vascularization remains to be defined. Here we demonstrate that mice deficient in the p110α catalytic subunit of PI3K display multiple vascular defects, including dilated vessels in the head, reduced branching morphogenesis in the endocardium, lack of hierarchical order of large and small branches in the yolk sac, and impaired development of anterior cardinal veins. These vascular defects are strikingly similar to those in mice defective in the Tie2 signaling pathway. Indeed, Tie2 protein levels were significantly lower in p110α-deficient mice. Furthermore, RNA interference of p110α in cultured endothelial cells significantly reduced Tie2 protein levels. These findings raise the possibility that PI3K may function as an upstream regulator of Tie2 expression during mouse development.

scholarly journals USP29 is a novel non-canonical Hypoxia Inducible Factor-α activator

2020 ◽  
Author(s):  
Amelie S Schober ◽  
Inés Martín-Barros ◽  
Teresa Martín-Mateos ◽  
Encarnación Pérez-Andrés ◽  
Onintza Carlevaris ◽  
...  
Keyword(s):  
Hypoxia Inducible Factor ◽  
Proteasomal Degradation ◽  
Low Oxygen ◽  
Independent Manner ◽  
Α Subunit ◽  
Von Hippel Lindau ◽  
Specific Protease ◽  
Translational Activator ◽  
The Stability ◽  
Factor Α

AbstractHypoxia Inducible Factor (HIF) is the master transcriptional regulator that orchestrates cellular adaptation to low oxygen. HIF is tightly regulated via the stability of its α-subunit, which is subjected to oxygen-dependent proline hydroxylation by Prolyl-Hydroxylase Domain containing proteins (PHDs/EGLNs), and ultimately targeted for proteasomal degradation through poly-ubiquitination by von-Hippel-Lindau protein (pVHL). However, sustained HIF-α signalling is found in many tumours independently of oxygen availability pointing towards the relevance of non-canonical HIF-α regulators. In this study, we establish the Ubiquitin Specific Protease 29 (USP29) as direct post-translational activator of HIF-α in a variety of cancer cell lines. USP29 binds to HIF-α, decreases poly-ubiquitination and thus protects HIF-α from proteasomal degradation. Deubiquitinating activity of USP29 is essential to stabilise not only HIF-1α but also HIF-2α, via their C-termini in an oxygen/PHD/pVHL-independent manner. Furthermore, in prostate cancer samples the expression of USP29 correlates with the HIF-target gene CA9 (carbonic anhydrase 9) as well as disease progression and severity.

scholarly journals 016.Role of cited genes in placental morphogenesis: studies in null mutant mice

2004 ◽  
Vol 16 (9) ◽  
pp. 16
Author(s):  
S. L. Dunwoodie ◽  
S. L. Withington ◽  
D. B. Sparrow ◽  
A. N. Scott ◽  
J. I. Preis ◽  
...  
Keyword(s):  
Hypoxia Inducible Factor ◽  
Giant Cells ◽  
Maternal Blood ◽  
Postnatal Period ◽  
Null Mutant ◽  
Placental Development ◽  
Null Mutant Mice ◽  
And Function ◽  
Trophoblast Giant Cells ◽  
Null Mutants

Cited1 and Cited2 interact with CBP and p300. CBP/p300 bind numerous proteins and evidence exists, for Cited2 at least, that Cited binding prevents the binding of other proteins to CBP/p300. Since CBP/p300 interact with many proteins, can acetylate protein and DNA, and act as a ubiquitin ligase, it is likely that Cited1 and Cited2 function at a number of sites during development. We have generated mice that carry a null mutant allele for each of these genes. Analysis of null mutant embryos demonstrates that both Cited1 and Cited2 are required for normal embryonic development and survival. Although both Cited1 and Cited2 are expressed in the developing embryo and placenta, it appears that abnormal placental development and function is the cause of embryonic death. The defect that develops in the placentas of Cited1 null mutants is not apparent until late in gestation (16.5dpc). Cited1 null mutants are smaller than controls at birth and die during the early postnatal period. The placentas of these mutants are disorganised, with spongiotrophoblasts projecting in to the labyrinthine layer. In addition, resin casts of the maternal blood spaces within these placentas revealed extremely enlarged blood sinuses. We are searching for factors that could result in the increased size of the maternal blood sinuses. Cited2 null placentas and embryos are significantly smaller than controls; mutants die 3/4 the way through gestation (15.5dpc). The null mutant placentas have proportionally fewer spongiotrophoblasts, trophoblast giant cells and invasive trophoblasts. In addition, resin casts of fetal vasculature of the placenta reveal that the capillary network is underdeveloped. Through the isolation of trophoblast stem (TS) cells we are exploring the possibility that TS cell proliferation and/or differentiation is impaired due to a lack of Cited2. We suspect that the development of the phenotype may relate to the Hypoxia Inducible Factor-1a (HIF1a) transcription factor as Cited2 expression is induced by HIF1 and it acts to negatively regulate its activity.

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