scholarly journals Xenon Upregulates Hypoxia Inducible Factor 1 Alpha in Neonatal Rat Brain under Normoxic Conditions

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Simona Valleggi ◽  
Chirag B. Patel ◽  
Andrea O. Cavazzana ◽  
Daqing Ma ◽  
Francesco Giunta ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Hypoxia Inducible Factor ◽  
Neonatal Rat ◽  
Transcript Analysis ◽  
Sprague Dawley ◽  
Organ Protection ◽  
Minute Exposure ◽  
Hypoxia Inducible Factor 1 ◽  
Significant Difference

Xenon can induce cell and organ protection through different molecular mechanisms related to oxygen level. We explored the effect of xenon on oxygen-related signalling in the central nervous system via hypoxia inducible factor 1 alpha (HIF-1α) and mammalian target of rapamycin (mTOR). Methods. Postnatal day 7 (P7) Sprague Dawley rats were exposed to 25% oxygen/75% nitrogen (air group) or 25% oxygen/75% xenon (treatment group) for 120 min. Brains were collected immediately (transcript analysis—relative real-time polymerase chain reaction) or 24 hours (protein analysis—immunohistochemistry) after the 120-minute exposure period; peak anesthetic preconditioning has been previously identified at 24 hours post-exposure. Results. HIF-1α transcript and protein levels were found to be increased in xenon-exposed compared to air-exposed brains. Sustained nuclear translocation of the protein, accounting for an increased activity of HIF-1α, was also noted. mTOR transcript analysis revealed no significant difference between xenon-exposed and air-exposed brains immediately after the 120-minute exposure. Conclusion. Our data suggest that xenon induces the upregulation of HIF-1α transcription and translation, which may contribute to xenon's neuroprotective preconditioning effect. However, given that xenon exposure did not affect mTOR transcription, further investigation into other signalling cascades mediating xenon’s effects on HIF-1α in developing brain is warranted.

scholarly journals HIF-1–dependent repression of equilibrative nucleoside transporter (ENT) in hypoxia

2005 ◽  
Vol 202 (11) ◽  
pp. 1493-1505 ◽  
Author(s):  
Holger K. Eltzschig ◽  
Parween Abdulla ◽  
Edgar Hoffman ◽  
Kathryn E. Hamilton ◽  
Dionne Daniels ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Molecular Mechanisms ◽  
Hypoxia Inducible Factor ◽  
Nucleoside Transporter ◽  
In Vivo Models ◽  
Equilibrative Nucleoside Transporter ◽  
Hypoxia Inducible Factor 1 ◽  
And Function

Extracellular adenosine (Ado) has been implicated as central signaling molecule during conditions of limited oxygen availability (hypoxia), regulating physiologic outcomes as diverse as vascular leak, leukocyte activation, and accumulation. Presently, the molecular mechanisms that elevate extracellular Ado during hypoxia are unclear. In the present study, we pursued the hypothesis that diminished uptake of Ado effectively enhances extracellular Ado signaling. Initial studies indicated that the half-life of Ado was increased by as much as fivefold after exposure of endothelia to hypoxia. Examination of expressional levels of the equilibrative nucleoside transporter (ENT)1 and ENT2 revealed a transcriptionally dependent decrease in mRNA, protein, and function in endothelia and epithelia. Examination of the ENT1 promoter identified a hypoxia inducible factor 1 (HIF-1)–dependent repression of ENT1 during hypoxia. Using in vitro and in vivo models of Ado signaling, we revealed that decreased Ado uptake promotes vascular barrier and dampens neutrophil tissue accumulation during hypoxia. Moreover, epithelial Hif1α mutant animals displayed increased epithelial ENT1 expression. Together, these results identify transcriptional repression of ENT as an innate mechanism to elevate extracellular Ado during hypoxia.

scholarly journals Chronic opioids regulate KATP channel subunit Kir6.2 and carbonic anhydrase I and II expression in rat adrenal chromaffin cells via HIF-2α and protein kinase A

2014 ◽  
Vol 307 (3) ◽  
pp. C266-C277 ◽  
Author(s):  
Shaima Salman ◽  
Alison C. Holloway ◽  
Colin A. Nurse
Keyword(s):  
Protein Kinase ◽  
Carbonic Anhydrase ◽  
Protein Kinase A ◽  
Chromaffin Cells ◽  
Time Course ◽  
Molecular Mechanisms ◽  
Hypoxia Inducible Factor ◽  
Neonatal Rat ◽  
Pcr Analysis ◽  
Kinase A

At birth, asphyxial stressors such as hypoxia and hypercapnia are important physiological stimuli for adrenal catecholamine release that is critical for the proper transition to extrauterine life. We recently showed that chronic opioids blunt chemosensitivity of neonatal rat adrenomedullary chromaffin cells (AMCs) to hypoxia and hypercapnia. This blunting was attributable to increased ATP-sensitive K+ (KATP) channel and decreased carbonic anhydrase (CA) I and II expression, respectively, and involved μ- and δ-opioid receptor signaling pathways. To address underlying molecular mechanisms, we first exposed an O2- and CO2-sensitive, immortalized rat chromaffin cell line (MAH cells) to combined μ {[d-Arg2,Ly4]dermorphin-(1–4)-amide}- and δ ([d-Pen2,5,P-Cl-Phe4]enkephalin)-opioid agonists (2 μM) for ∼7 days. Western blot and quantitative real-time PCR analysis revealed that chronic opioids increased KATP channel subunit Kir6.2 and decreased CAII expression; both effects were blocked by naloxone and were absent in hypoxia-inducible factor (HIF)-2α-deficient MAH cells. Chronic opioids also stimulated HIF-2α accumulation along a time course similar to Kir6.2. Chromatin immunoprecipitation assays on opioid-treated cells revealed the binding of HIF-2α to a hypoxia response element in the promoter region of the Kir6.2 gene. The opioid-induced regulation of Kir6.2 and CAII was dependent on protein kinase A, but not protein kinase C or calmodulin kinase, activity. Interestingly, a similar pattern of HIF-2α, Kir6.2, and CAII regulation (including downregulation of CAI) was replicated in chromaffin tissue obtained from rat pups born to dams exposed to morphine throughout gestation. Collectively, these data reveal novel mechanisms by which chronic opioids blunt asphyxial chemosensitivity in AMCs, thereby contributing to abnormal arousal responses in the offspring of opiate-addicted mothers.

scholarly journals Effects of L-Theanine on Posttraumatic Stress Disorder Induced Changes in Rat Brain Gene Expression

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Tomás Eduardo Ceremuga ◽  
Stephanie Martinson ◽  
Jason Washington ◽  
Robert Revels ◽  
Jessica Wojcicki ◽  
...  
Keyword(s):  
Gene Expression ◽  
Posttraumatic Stress Disorder ◽  
Posttraumatic Stress ◽  
Molecular Mechanisms ◽  
Stress Disorder ◽  
Traumatic Event ◽  
Pcr Analysis ◽  
Sprague Dawley ◽  
Significant Difference ◽  
Induced Changes

Posttraumatic stress disorder (PTSD) is characterized by the occurrence of a traumatic event that is beyond the normal range of human experience. The future of PTSD treatment may specifically target the molecular mechanisms of PTSD. In the US, approximately 20% of adults report taking herbal products to treat medical illnesses. L-theanine is the amino acid in green tea primarily responsible for relaxation effects. No studies have evaluated the potential therapeutic properties of herbal medications on gene expression in PTSD. We evaluated gene expression in PTSD-induced changes in the amygdala and hippocampus of Sprague-Dawley rats. The rats were assigned to PTSD-stressed and nonstressed groups that received either saline, midazolam, L-theanine, or L-theanine + midazolam. Amygdala and hippocampus tissue samples were analyzed for changes in gene expression. One-way ANOVA was used to detect significant difference between groups in the amygdala and hippocampus. Of 88 genes examined, 17 had a large effect size greater than 0.138. Of these, 3 genes in the hippocampus and 5 genes in the amygdala were considered significant (P<0.05) between the groups. RT-PCR analysis revealed significant changes between groups in several genes implicated in a variety of disorders ranging from PTSD, anxiety, mood disorders, and substance dependence.

Mechanism of ischemic tolerance induced by hyperbaric oxygen preconditioning involves upregulation of hypoxia-inducible factor-1α and erythropoietin in rats

2008 ◽  
Vol 104 (4) ◽  
pp. 1185-1191 ◽  
Author(s):  
Guo-Jun Gu ◽  
Yun-Ping Li ◽  
Zao-Yun Peng ◽  
Jia-Jun Xu ◽  
Zhi-Min Kang ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Hyperbaric Oxygen ◽  
Target Gene ◽  
Molecular Mechanisms ◽  
Focal Cerebral Ischemia ◽  
Hypoxia Inducible Factor ◽  
Sprague Dawley ◽  
Triphenyltetrazolium Chloride ◽  
Time Points ◽  
Hypoxia Inducible Factor 1Α

We studied the effect of hyperbaric oxygen (HBO) preconditioning on the molecular mechanisms of neuroprotection in a rat focal cerebral ischemic model. Seventy-two male Sprague-Dawley rats were pretreated with HBO (100% O2, 2 atmospheres absolute, 1 h once every other day for 5 sessions) or with room air. In experiment 1, HBO-preconditioned rats and matched room air controls were subjected to focal cerebral ischemia or sham surgery. Postinjury motor parameters and infarction volumes of HBO-preconditioned rats were compared with those of controls. In experiment 2, HBO-preconditioned rats and matched room air controls were killed at different time points. Brain levels of hypoxia-inducible factor-1α (HIF-1α) and its downstream target gene erythropoietin (EPO) analyzed by Western blotting and RT-PCR as well as HIF-1α DNA-binding and transcriptional activities were determined in the ipsilateral hemisphere. HBO induced a marked increase in the protein expressions of HIF-1α and EPO and the activity of HIF-1α, as well as the expression of EPO mRNA. HBO preconditioning dramatically improved the neurobehavioral outcome at all time points (3.0 ± 2.1 vs. 5.6 ± 1.5 at 4 h, 5.0 ± 1.8 vs. 8.8 ± 1.4 at 8 h, 6.4 ± 1.8 vs. 9.7 ± 1.3 at 24 h; P < 0.01, respectively) and reduced infarction volumes (20.7 ± 4.5 vs. 12.5 ± 3.6%, 2,3,5-Triphenyltetrazolium chloride staining) after cerebral ischemia. This observation indicates that the neuroprotection induced by HBO preconditioning may be mediated by an upregulation of HIF-1α and its target gene EPO.

scholarly journals Induction and nuclear translocation of hypoxia-inducible factor-1 (HIF-1): heterodimerization with ARNT is not necessary for nuclear accumulation of HIF-1alpha

1999 ◽  
Vol 112 (8) ◽  
pp. 1203-1212 ◽  
Author(s):  
D. Chilov ◽  
G. Camenisch ◽  
I. Kvietikova ◽  
U. Ziegler ◽  
M. Gassmann ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Hypoxia Inducible Factor ◽  
Embryonic Stem ◽  
Nuclear Accumulation ◽  
Nuclear Compartment ◽  
Hypoxia Inducible Factor 1 ◽  
Aryl Hydrocarbon ◽  
Oxygen Homeostasis ◽  
Nuclear Extracts ◽  
Stable Association

Hypoxia-inducible factor-1 (HIF-1) is a master regulator of mammalian oxygen homeostasis. HIF-1 consists of two subunits, HIF-1alpha and the aryl hydrocarbon receptor nuclear translocator (ARNT). Whereas hypoxia prevents proteasomal degradation of HIF-1alpha, ARNT expression is thought to be oxygen-independent. We and others previously showed that ARNT is indispensable for HIF-1 DNA-binding and transactivation function. Here, we have used ARNT-mutant mouse hepatoma and embryonic stem cells to examine the requirement of ARNT for accumulation and nuclear translocation of HIF-1alpha in hypoxia. As shown by immunofluorescence, HIF-1alpha accumulation in the nucleus of hypoxic cells was independent of the presence of ARNT, suggesting that nuclear translocation is intrinsic to HIF-1alpha. Co-immunoprecipitation of HIF-1alpha together with ARNT could be performed in nuclear extracts but not in cytosolic fractions, implying that formation of the HIF-1 complex occurs in the nucleus. A proteasome inhibitor and a thiol-reducing agent could mimic hypoxia by inducing HIF-1alpha in the nucleus, indicating that escape from proteolytic degradation is sufficient for accumulation and nuclear translocation of HIF-1alpha. During biochemical separation, both HIF-1alpha and ARNT tend to leak from the nuclei in the absence of either subunit, suggesting that heterodimerization is required for stable association within the nuclear compartment. Nuclear stabilization of the heterodimer might also explain the hypoxically increased total cellular ARNT levels observed in some of the cell lines examined.

A new HIF-1 alpha variant induced by zinc ion suppresses HIF-1-mediated hypoxic responses

2001 ◽  
Vol 114 (22) ◽  
pp. 4051-4061
Author(s):  
Yang-Sook Chun ◽  
Eunjoo Choi ◽  
Eun-Jin Yeo ◽  
Jong Ho Lee ◽  
Myung-Suk Kim ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Consensus Sequence ◽  
Hypoxia Inducible Factor ◽  
Zinc Ion ◽  
Dominant Negative ◽  
Hypoxia Inducible Factor 1 ◽  
Aryl Hydrocarbon ◽  
Hypoxic Conditions ◽  
Alpha Variant ◽  
Inducible Genes

The expressions of hypoxia-inducible genes are upregulated by hypoxia-inducible factor 1 (HIF-1), which is a heterodimer of HIF-1α and HIF-1β/ARNT (aryl hydrocarbon receptor nuclear transporter). Under hypoxic conditions, HIF-1α becomes stabilized and both HIF-1α and ARNT are translocated into the nucleus and codimerized, binding to the HIF-1 consensus sequence and transactivating hypoxia-inducible genes. Other than hypoxia, cobalt and nickel, which can substitute for iron in the ferroprotein, induce the stabilization of HIF-1α and the activation of HIF-1. We found previously that, although zinc, another example of a metal substitute for iron, stabilized HIF-1α, it suppressed the formation of HIF-1 by blocking the nuclear translocation of ARNT. Here, we identify a new spliced variant of human HIF-1α that is induced by zinc. The isoform lacks the 12th exon, which produced a frame-shift and gave a shorter form of HIF-1α (557 amino acids), designated HIF-1αZ (HIF-1α induced by Zn). This moiety was found to inhibit HIF-1 activity and reduce mRNA expressions of the hypoxia-inducible genes. It blocked the nuclear translocation of ARNT but not that of endogenous HIF-1α, and was associated with ARNT in the cytosol. These results suggest that HIF-1αZ functions as a dominant-negative isoform of HIF-1 by sequestering ARNT in the cytosol. In addition, the generation of HIF-1αZ seems to be responsible for the inhibitory effects of the zinc ion on HIF-1-mediated hypoxic responses, because the expressed HIF-1αZ behaved in the same manner as zinc in terms of inhibited HIF-1 activity and ARNT translocation.

Association between hypoxia-inducible factor-1 alpha rs11549465 (1772 C>T) polymorphism and metabolic syndrome

2021 ◽  
pp. 1-15
Author(s):  
Uzma Zafar ◽  
Zaima Ali ◽  
Saba Khaliq ◽  
Khalid Lone
Keyword(s):  
Metabolic Syndrome ◽  
Hypoxia Inducible Factor ◽  
Control Group ◽  
Cross Sectional ◽  
Hypoxia Inducible Factor 1 ◽  
Increased Risk ◽  
Significant Difference ◽  
Venous Sample ◽  
In The Wild ◽  
The University

Abstract Objectives: To find the association of single nucleotide polymorphism of hypoxia-inducible factor-1 alpha, rs11549465 (1772 Cytosine > Thymine) with metabolic syndrome, and to compare the anthropometric and biochemical variables in different genotypes of hypoxia-inducible factor-1 alpha. Methods: The cross-sectional comparative study was conducted at the University of Health Sciences, Lahore, Pakistan, from July 2016 to April 2019, and comprised patients of metabolic syndrome selected from the Sheikh Zayed Hospital, Lahore. Healthy controls were also enrolled. Fasting venous sample was taken for the determination of study parameters. The genetic variant of hypoxia-inducible factor-1 alpha was analysed by restriction fragment length polymorphism polymerase chain reaction. Data was analysed using SPSS 22. Results: Out of 400 subjects, 200(50%) each were patients and controls. The frequency of CC genotype of hypoxia-inducible factor-1 alpha Cytosine > Thymine in patients was 166(83%) and in controls 147(73.5%); CT genotype was 34(17%) and 53(26.5%) respectively, while TT genotype was not observed. There was a significant association of the C allele and CC genotype (p=0.03) with the increased risk of metabolic syndrome (p=0.02). On comparison of study variables in the two genotypes, systolic blood pressure, anthropometric and lipid parameters were significantly higher in the wild CC genotype compared to CT in the control group (p<0.05), but there was no significant difference in the patients (p>0.05). Conclusion: Major allele C of hypoxia-inducible factor-1 alpha 1772 Cytosine > Thymine was found to be associated with increased risk of metabolic syndrome. Continuous...

scholarly journals Synaptic Injury in the Thalamus Accompanies White Matter Injury in Hypoxia/Ischemia-Mediated Brain Injury in Neonatal Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Na Liu ◽  
Xin Tong ◽  
Wanjie Huang ◽  
Jianhua Fu ◽  
Xindong Xue
Keyword(s):  
White Matter ◽  
White Matter Injury ◽  
Neonatal Rat ◽  
Morris Water Maze Test ◽  
Neonatal Rats ◽  
Sprague Dawley ◽  
Artery Ligation ◽  
Compensatory Response ◽  
Significant Difference ◽  
Hypoxia Ischemia

The broad spectrum of disabilities caused by white matter injury (WMI) cannot be explained simply by hypomyelination. Synaptic injury in the thalamus may be related to disabilities in WMI survivors. Neuronal injury in the thalamus has been found most commonly in autopsy cases of preterm WMI. We hypothesized that hypoxia/ischemia (HI) in neonatal rats results in synaptic abnormalities in the thalamus that contribute to disabilities in WMI survivors. We examined changes in synapses in a neonatal rat model of HI-induced WMI. Right common carotid artery ligation and hypoxia (8% oxygen for 2.5 hours (h)) were performed in three-day-old Sprague-Dawley rats. We found HI rats performed worse in the Morris water maze test than sham rats, suggesting long-term cognition impairment after HI injury. A loss of synapses in the thalamus accompanied by hypomyelination and oligodendrocytes (OLs) reduction was observed. At the ultrastructural level, reductions in active zone (AZ) length and postsynaptic density (PSD) thickness were detected at 2 weeks after HI exposure. Furthermore, increased expression of synaptophysin and PSD-95 in both groups was observed from 3 days (d) to 21 d after hypoxic/ischemic (HI) injury. PSD-95 expression was significantly lower in HI rats than in sham rats from 14 d to 21 d after HI injury, and synaptophysin expression was significantly lower in HI rats from 7 d to 14 d after HI injury. However, no significant difference in synaptophysin expression was observed between HI rats and sham rats at 21 d after HI injury. The results demonstrated synaptic abnormalities in the thalamus accompanied by hypomyelination in WMI in response to HI exposure, which may contribute to the diverse neurological defects observed in WMI patients. Although synaptic reorganization occurred as a compensatory response to HI injury, the impairments in synaptic transmission were not reversed.

scholarly journals NFAT3/c4-mediated excitotoxicity in hippocampal apoptosis during radiation-induced brain injury

2017 ◽  
Vol 58 (6) ◽  
pp. 827-833 ◽  
Author(s):  
Meiling Xu ◽  
Qiuhong Fan ◽  
Junjun Zhang ◽  
Yanfang Chen ◽  
Ruizhe Xu ◽  
...  
Keyword(s):  
Brain Injury ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Cranial Irradiation ◽  
Metastatic Carcinoma ◽  
Sprague Dawley ◽  
Whole Brain Irradiation ◽  
Activated T Cells ◽  
Radiation Induced ◽  
Hippocampal Apoptosis

Abstract Whole brain irradiation (WBI) has become an indispensible tool in the treatment of head and neck cancer, and it has greatly improved patient survival rate and total survival time. In addition, prophylactic cranial irradiation (PCI) has dramatically decreased the incidence of brain metastatic carcinoma. However, WBI may induce temporary functional deficits or even progressive, irreversible cognitive dysfunction that compromises the quality of life for survivors. Unfortunately, the exact molecular mechanisms for cognitive damage remain elusive, and no treatment or preventative measures are available for use in the clinic. In the present study, the nuclear factor of activated T cells isoform 4 (NFAT3/c4) was found to play a vital role in excitotoxic hippocampus cell apoptosis induced by radiation. Sprague–Dawley (SD) rats received 20 Gy WBI, after which we detected NFAT3/c4-mediated excitotoxicity. We found that radiation caused hippocampus excitotoxicity, resulting from overactivation of the N-methyl-D-aspartate receptor (NMDAR) and always accompanied by subsequent elevation of the intracellular calcium level and activation of calcineurin (CaN). P-NFAT3/c4 was the principal downstream target of CaN, including regulation of its nuclear translocation as well as transcriptional activities. Radiation recruited NMDAR/NFAT3/c4 activation and subsequent Bax induction in hippocampus cells. Once treated with the NFAT3/c4 inhibitor 11R-VIVIT peptide pre-irradiation, hippocampal proliferation and neuron survival (dentate gyrus cells in particular) were protected from radiation-induced injury, resulting in inhibition of the apoptosis marker Bax. Our principal aim was to illuminate the role of NFAT3/c4-mediated excitotoxicity in hippocampal apoptosis during radiation-induced brain injury. This study is the first time that radiation-induced activation of NFAT3/c4 has been recorded, and our results suggest that NFAT3/c4 may be a novel target for prevention and treatment of radiation-induced brain injury.

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