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Barteczek P, Li L, Ernst AS, Böhler LI, Marti HH, Kunze R. Neuronal HIF-1α and HIF-2α deficiency improves neuronal survival and sensorimotor function in the early acute phase after ischemic stroke. J Cereb Blood Flow Metab 2017; 37:291-306. [PMID: 26746864 PMCID: PMC5363746 DOI: 10.1177/0271678x15624933] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 10/30/2015] [Accepted: 12/07/2015] [Indexed: 01/01/2023]
Abstract
Hypoxia-inducible factors mediate adaptive responses to ischemia, among others, by induction of anti- and pro-survival genes. Thus, the impact of HIF on neuronal survival upon stroke is controversial. Therefore, neuron-specific knockout mice deficient for Hif1a and Hif2a were exposed to inspiratory hypoxia or ischemia-reperfusion injury. Both Hif1a- and Hif2a-deficient mice showed no altered infarct and edema size, suggesting that both HIF-α subunits might compensate for each other. Accordingly, hypoxic HIF-target gene regulation was marginally affected with exception of anti-survival Bnip3 and pro-survival erythropoietin. In the early acute stage upon stroke, Hif1a/Hif2a double knockout mice exhibited significantly reduced expression of the anti-survival Bnip3, Bnip3L, and Pmaip1 Accordingly, global cell death and edema were significantly reduced upon 24 h but not 72 h reperfusion. Behavioral assessment indicated that Hif1a/Hif2a-deficient mice initially performed better, but became significantly more impaired after 72 h accompanied by increased apoptosis and reduced angiogenesis. Our findings suggest that in neurons HIF-1 and HIF-2 have redundant functions for cellular survival under ischemic conditions. By contrast, lack of anti-survival factors in Hif1a/Hif2a-deficient mice might protect from early acute neuronal cell death and neurological impairment, indicating a benefit of HIF-pathway inhibition in neurons in the very acute phase after ischemic stroke.
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Affiliation(s)
- Philipp Barteczek
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Lexiao Li
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Anne-Sophie Ernst
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Laura-Inés Böhler
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Hugo H Marti
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Reiner Kunze
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
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Karuppagounder SS, Alim I, Khim SJ, Bourassa MW, Sleiman SF, John R, Thinnes CC, Yeh TL, Demetriades M, Neitemeier S, Cruz D, Gazaryan I, Killilea DW, Morgenstern L, Xi G, Keep RF, Schallert T, Tappero RV, Zhong J, Cho S, Maxfield FR, Holman TR, Culmsee C, Fong GH, Su Y, Ming GL, Song H, Cave JW, Schofield CJ, Colbourne F, Coppola G, Ratan RR. Therapeutic targeting of oxygen-sensing prolyl hydroxylases abrogates ATF4-dependent neuronal death and improves outcomes after brain hemorrhage in several rodent models. Sci Transl Med 2016; 8:328ra29. [PMID: 26936506 DOI: 10.1126/scitranslmed.aac6008] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Disability or death due to intracerebral hemorrhage (ICH) is attributed to blood lysis, liberation of iron, and consequent oxidative stress. Iron chelators bind to free iron and prevent neuronal death induced by oxidative stress and disability due to ICH, but the mechanisms for this effect remain unclear. We show that the hypoxia-inducible factor prolyl hydroxylase domain (HIF-PHD) family of iron-dependent, oxygen-sensing enzymes are effectors of iron chelation. Molecular reduction of the three HIF-PHD enzyme isoforms in the mouse striatum improved functional recovery after ICH. A low-molecular-weight hydroxyquinoline inhibitor of the HIF-PHD enzymes, adaptaquin, reduced neuronal death and behavioral deficits after ICH in several rodent models without affecting total iron or zinc distribution in the brain. Unexpectedly, protection from oxidative death in vitro or from ICH in vivo by adaptaquin was associated with suppression of activity of the prodeath factor ATF4 rather than activation of an HIF-dependent prosurvival pathway. Together, these findings demonstrate that brain-specific inactivation of the HIF-PHD metalloenzymes with the blood-brain barrier-permeable inhibitor adaptaquin can improve functional outcomes after ICH in several rodent models.
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Affiliation(s)
- Saravanan S Karuppagounder
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Ishraq Alim
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Soah J Khim
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Megan W Bourassa
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Sama F Sleiman
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Roseleen John
- Department of Psychology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | | | - Tzu-Lan Yeh
- Department of Chemistry, University of Oxford, OX1 3TA Oxford, UK
| | | | - Sandra Neitemeier
- Institut fuer Pharmakologie and Klinische Pharmazie, Phillips-Universitaet Marburg, D 35032 Marburg, Germany
| | - Dana Cruz
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Irina Gazaryan
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | | | - Lewis Morgenstern
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Guohua Xi
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Richard F Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Timothy Schallert
- Department of Psychology, University of Texas at Austin, Austin, TX 78712, USA
| | - Ryan V Tappero
- Photon Sciences Directorate, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Jian Zhong
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Sunghee Cho
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Frederick R Maxfield
- Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Theodore R Holman
- Chemistry and Biochemistry, Department, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
| | - Carsten Culmsee
- Institut fuer Pharmakologie and Klinische Pharmazie, Phillips-Universitaet Marburg, D 35032 Marburg, Germany
| | - Guo-Hua Fong
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Yijing Su
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Guo-li Ming
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hongjun Song
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - John W Cave
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA
| | | | - Frederick Colbourne
- Department of Psychology, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Giovanni Coppola
- Department of Psychiatry, University of California at Los Angeles, CA 90095, USA
| | - Rajiv R Ratan
- Sperling Center for Hemorrhagic Stroke Recovery, Burke Medical Research Institute, White Plains, NY 10605, USA. Feil Family Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, USA.
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Terraneo L, Paroni R, Bianciardi P, Giallongo T, Carelli S, Gorio A, Samaja M. Brain adaptation to hypoxia and hyperoxia in mice. Redox Biol 2016; 11:12-20. [PMID: 27835780 PMCID: PMC5107733 DOI: 10.1016/j.redox.2016.10.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/23/2016] [Accepted: 10/27/2016] [Indexed: 12/13/2022] Open
Abstract
Aims Hyperoxic breathing might lead to redox imbalance and signaling changes that affect cerebral function. Paradoxically, hypoxic breathing is also believed to cause oxidative stress. Our aim is to dissect the cerebral tissue responses to altered O2 fractions in breathed air by assessing the redox imbalance and the recruitment of the hypoxia signaling pathways. Results Mice were exposed to mild hypoxia (10%O2), normoxia (21%O2) or mild hyperoxia (30%O2) for 28 days, sacrificed and brain tissue excised and analyzed. Although one might expect linear responses to %O2, only few of the examined variables exhibited this pattern, including neuroprotective phospho- protein kinase B and the erythropoietin receptor. The major reactive oxygen species (ROS) source in brain, NADPH oxidase subunit 4 increased in hypoxia but not in hyperoxia, whereas neither affected nuclear factor (erythroid-derived 2)-like 2, a transcription factor that regulates the expression of antioxidant proteins. As a result of the delicate equilibrium between ROS generation and antioxidant defense, neuron apoptosis and cerebral tissue hydroperoxides increased in both 10%O2 and 30%O2, as compared with 21%O2. Remarkably, the expression level of hypoxia-inducible factor (HIF)−2α (but not HIF-1α) was higher in both 10%O2 and 30%O2 with respect to 21%O2 Innovation Comparing the in vivo effects driven by mild hypoxia with those driven by mild hyperoxia helps addressing whether clinically relevant situations of O2 excess and scarcity are toxic for the organism. Conclusion Prolonged mild hyperoxia leads to persistent cerebral damage, comparable to that inferred by prolonged mild hypoxia. The underlying mechanism appears related to a model whereby the imbalance between ROS generation and anti-ROS defense is similar, but occurs at higher levels in hypoxia than in hyperoxia. Both oxygen scarcity and oxygen excess are harmful for the brain. Hypoxia increases ROS more than hyperoxia. Hypoxia increases the antioxidant defenses to an extent larger than hyperoxia. Both hypoxia and hyperoxia imbalance the ROS generation/ antiROS defense equilibrium. These findings have implications for those who need supplemental oxygen therapy.
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Affiliation(s)
- Laura Terraneo
- Department of Health Science, University of Milan, 20142 Milan, Italy
| | - Rita Paroni
- Department of Health Science, University of Milan, 20142 Milan, Italy
| | - Paola Bianciardi
- Department of Health Science, University of Milan, 20142 Milan, Italy
| | | | - Stephana Carelli
- Department of Health Science, University of Milan, 20142 Milan, Italy
| | - Alfredo Gorio
- Department of Health Science, University of Milan, 20142 Milan, Italy
| | - Michele Samaja
- Department of Health Science, University of Milan, 20142 Milan, Italy.
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Stabilization of Hypoxia-inducible Factor by DMOG Inhibits Development of Chronic Hypoxia-Induced Right Ventricular Remodeling. J Cardiovasc Pharmacol 2016; 67:68-75. [PMID: 26485211 DOI: 10.1097/fjc.0000000000000315] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND One important determinant of longevity in congenital heart disease is right ventricular (RV) function, and this is especially true in cyanotic congenital heart disease. However, there is a paucity of data concerning right ventricular remodeling (RVR) in the setting of chronic hypoxia. Dimethyloxalylglycine (DMOG) is a competitive inhibitor of hypoxia-inducible factor (HIF)-hydroxylated prolyl hydroxylase and has been shown to play an important role against ischemia-reperfusion myocardial injury. METHODS We tested the hypothesis that DMOG prevents the development RVR after chronic hypoxia exposure. Rats were injected with saline or DMOG and exposed to room air or continued hypoxia for 4 weeks. In addition, we explored the response of myocardial erythropoietin and its receptor to hypoxic exposure. RESULTS Treatment with DMOG attenuated myocardial fibrosis, apoptosis, and oxidative stress, which lead to enhanced RV contractile function. As an endpoint of HIF-dependent cardioprotection, a novel pathway in which nuclear factor kappa B links HIF-1 transcription was defined. CONCLUSIONS This study supports a role for HIF-1 stabilizers in the treatment of RVR and brings into question the commonly held concept that RVR follows a linear relationship with increased RV afterload.
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Prolyl-4-hydroxylase 2 and 3 coregulate murine erythropoietin in brain pericytes. Blood 2016; 128:2550-2560. [PMID: 27683416 DOI: 10.1182/blood-2016-05-713545] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/22/2016] [Indexed: 12/20/2022] Open
Abstract
A classic response to systemic hypoxia is the increased production of red blood cells due to hypoxia-inducible factor (HIF)-mediated induction of erythropoietin (EPO). EPO is a glycoprotein hormone that is essential for normal erythropoiesis and is predominantly synthesized by peritubular renal interstitial fibroblast-like cells, which express cellular markers characteristic of neuronal cells and pericytes. To investigate whether the ability to synthesize EPO is a general functional feature of pericytes, we used conditional gene targeting to examine the von Hippel-Lindau/prolyl-4-hydroxylase domain (PHD)/HIF axis in cell-expressing neural glial antigen 2, a known molecular marker of pericytes in multiple organs. We found that pericytes in the brain synthesized EPO in mice with genetic HIF activation and were capable of responding to systemic hypoxia with the induction of Epo. Using high-resolution multiplex in situ hybridization, we determined that brain pericytes represent an important cellular source of Epo in the hypoxic brain (up to 70% of all Epo-expressing cells). We furthermore determined that Epo transcription in brain pericytes was HIF-2 dependent and cocontrolled by PHD2 and PHD3, oxygen- and 2-oxoglutarate-dependent prolyl-4-hydroxylases that regulate HIF activity. In summary, our studies provide experimental evidence that pericytes in the brain have the ability to function as oxygen sensors and respond to hypoxia with EPO synthesis. Our findings furthermore suggest that the ability to synthesize EPO may represent a functional feature of pericytes in the brain and kidney.
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Erythropoietin production by PDGFR-β(+) cells. Pflugers Arch 2016; 468:1479-87. [PMID: 27220347 DOI: 10.1007/s00424-016-1829-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 01/19/2023]
Abstract
PDGFR-β-expressing cells of the kidneys are considered as a relevant site of erythropoietin (EPO) production. The origin of these cells, their contribution to renal EPO production, and if PDGFR-β-positive cells in other organs are also capable to express EPO are less clear. We addressed these questions in mice, in which hypoxia-inducible transcription factors were stabilized in PDGFR-β(+) cells by inducible deletion of the von Hippel-Lindau (Vhl) protein. Vhl deletion led to a 600-fold increase of plasma EPO concentration, 170-fold increase of renal EPO messenger RNA (mRNA) levels, and an increase of hematocrit values up to 70 %. Intrarenal localization of EPO-expressing cells coincided with the zonal heterogeneity and distribution of cells expressing PDGFR-β. Amongst a variety of extrarenal organs only adrenal glands showed significant EPO mRNA expression after Vhl deletion in PDGFR-β(+) cells. EPO mRNA, plasma EPO, and hematocrit fell to subnormal values if HIF-2α, but not HIF-1α, was deleted either alone or in combination with Vhl in PDGFR-β(+) cells. Treatment of mice with a prolyl-hydroxylase inhibitor caused an increase of EPO mRNA abundance and plasma EPO concentrations in wild-type mice and in mice lacking HIF-1α in PDGFR-β(+) cells but exerted no effect in mice lacking HIF-2α in PDGFR-β(+) cells. These findings suggest that PDGFR-β(+) cells are the only relevant site of EPO expression in the kidney and that HIF-2 is the essential transcription factor triggering EPO expression therein. Moreover, our findings suggest that PDGFR-β(+) cells elaborating EPO might arise from the metanephric mesenchyme, rather than from the neural crest.
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Zhao J, Bai Z, Feng F, Song E, Du F, Zhao J, Shen G, Ji F, Li G, Ma X, Hang X, Xu B. Cross-talk between EPAS-1/HIF-2α and PXR signaling pathway regulates multi-drug resistance of stomach cancer cell. Int J Biochem Cell Biol 2016; 72:73-88. [DOI: 10.1016/j.biocel.2016.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 12/27/2015] [Accepted: 01/15/2016] [Indexed: 01/14/2023]
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Dey S, Li X, Teng R, Alnaeeli M, Chen Z, Rogers H, Noguchi CT. Erythropoietin regulates POMC expression via STAT3 and potentiates leptin response. J Mol Endocrinol 2016; 56:55-67. [PMID: 26563310 PMCID: PMC4692057 DOI: 10.1530/jme-15-0171] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/12/2015] [Indexed: 01/02/2023]
Abstract
The arcuate nucleus of the hypothalamus is essential for metabolic homeostasis and responds to leptin by producing several neuropeptides including proopiomelanocortin (POMC). We previously reported that high-dose erythropoietin (Epo) treatment in mice while increasing hematocrit reduced body weight, fat mass, and food intake and increased energy expenditure. Moreover, we showed that mice with Epo receptor (EpoR) restricted to erythroid cells (ΔEpoRE) became obese and exhibited decreased energy expenditure. Epo/EpoR signaling was found to promote hypothalamus POMC expression independently from leptin. Herein we used WT and ΔEpoRE mice and hypothalamus-derived neural culture system to study the signaling pathways activated by Epo in POMC neurons. We show that Epo stimulation activated STAT3 signaling and upregulated POMC expression in WT neural cultures. ΔEpoRE mice hypothalamus showed reduced POMC levels and lower STAT3 phosphorylation, with and without leptin treatment, compared to in vivo and ex vivo WT controls. Collectively, these data show that Epo regulates hypothalamus POMC expression via STAT3 activation, and provide a previously unrecognized link between Epo and leptin response.
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Marina N, Kasymov V, Ackland GL, Kasparov S, Gourine AV. Astrocytes and Brain Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:201-7. [PMID: 27343098 DOI: 10.1007/978-1-4899-7678-9_14] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astrocytes provide the structural and functional interface between the cerebral circulation and neuronal networks. They enwrap all intracerebral arterioles and capillaries, control the flux of nutrients as well as the ionic and metabolic environment of the neuropil. Astrocytes have the ability to adjust cerebral blood flow to maintain constant PO2 and PCO2 of the brain parenchyma. Release of ATP in the brainstem, presumably by local astrocytes, helps to maintain breathing and counteract hypoxia-induced depression of the respiratory network. Astrocytes also appear to be involved in mediating hypoxia-evoked changes in blood-brain barrier permeability, brain inflammation, and neuroprotection against ischaemic injury. Thus, astrocytes appear to play a fundamental role in supporting neuronal function not only in normal conditions but also in pathophysiological states when supply of oxygen to the brain is compromised.
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Affiliation(s)
- Nephtali Marina
- Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Vitaliy Kasymov
- Neuroscience, Physiology & Pharmacology, University College London, London, UK
| | - Gareth L Ackland
- Experimental Medicine, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Sergey Kasparov
- Department of Physiology and Pharmacology, University of Bristol, Bristol, UK
| | - Alexander V Gourine
- Neuroscience, Physiology & Pharmacology, University College London, London, UK.
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Hypoxic Adaptation in the Nervous System: Promise for Novel Therapeutics for Acute and Chronic Neurodegeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:221-43. [PMID: 27343100 DOI: 10.1007/978-1-4899-7678-9_16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Homeostasis is the process by which cells adapt to stress and prevent or repair injury. Unique programs have evolved to sense and activate these homeostatic mechanisms and as such, homeostatic sensors may be potent therapeutic targets. The hypoxic response mediated by hypoxia inducible factor (HIF) downstream of oxygen sensing by HIF prolyl 4-hydroxylases (PHDs) has been well-studied, revealing cell-type specific regulation of HIF stability, activity, and transcriptional targets. HIF's paradoxical roles in nervous system development, physiology, and pathology arise from its complex roles in hypoxic adaptation and normoxic biology. Understanding how to engage the hypoxic response so as to recapitulate the protective mechanism of ischemic preconditioning is a high priority. Indeed, small molecules that activate the hypoxic response provide broad neuroprotection in several clinically relevant injury models. Screens for PHD inhibitors have identified novel therapeutics for neuroprotection that are ready to proceed to clinical trials for ischemic stroke. Better understanding the mechanisms of how to engage hypoxic adaption without altering development or physiology may identify additional novel therapeutic targets for diverse acute and chronic neuropathologies.
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Thushara Vijayakumar N, Sangwan A, Sharma B, Majid A, Rajanikant GK. Cerebral Ischemic Preconditioning: the Road So Far…. Mol Neurobiol 2015; 53:2579-93. [PMID: 26081149 DOI: 10.1007/s12035-015-9278-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 06/02/2015] [Indexed: 12/25/2022]
Abstract
Cerebral preconditioning constitutes the brain's adaptation to lethal ischemia when first exposed to mild doses of a subtoxic stressor. The phenomenon of preconditioning has been largely studied in the heart, and data from in vivo and in vitro models from past 2-3 decades have provided sufficient evidence that similar machinery exists in the brain as well. Since preconditioning results in a transient protective phenotype labeled as ischemic tolerance, it can open many doors in the medical warfare against stroke, a debilitating cerebrovascular disorder that kills or cripples thousands of people worldwide every year. Preconditioning can be induced by a variety of stimuli from hypoxia to pharmacological anesthetics, and each, in turn, induces tolerance by activating a multitude of proteins, enzymes, receptors, transcription factors, and other biomolecules eventually leading to genomic reprogramming. The intracellular signaling pathways and molecular cascades behind preconditioning are extensively being investigated, and several first-rate papers have come out in the last few years centered on the topic of cerebral ischemic tolerance. However, translating the experimental knowledge into the clinical scaffold still evades practicality and faces several challenges. Of the various preconditioning strategies, remote ischemic preconditioning and pharmacological preconditioning appears to be more clinically relevant for the management of ischemic stroke. In this review, we discuss current developments in the field of cerebral preconditioning and then examine the potential of various preconditioning agents to confer neuroprotection in the brain.
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Affiliation(s)
- N Thushara Vijayakumar
- School of Biotechnology, DBT-Centre for Bioinformatics, National Institute of Technology Calicut, Calicut, 673601, India
| | - Amit Sangwan
- School of Biotechnology, DBT-Centre for Bioinformatics, National Institute of Technology Calicut, Calicut, 673601, India
| | - Bhargy Sharma
- School of Biotechnology, DBT-Centre for Bioinformatics, National Institute of Technology Calicut, Calicut, 673601, India
| | - Arshad Majid
- Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, UK
| | - G K Rajanikant
- School of Biotechnology, DBT-Centre for Bioinformatics, National Institute of Technology Calicut, Calicut, 673601, India.
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Titomanlio L, Fernández-López D, Manganozzi L, Moretti R, Vexler ZS, Gressens P. Pathophysiology and neuroprotection of global and focal perinatal brain injury: lessons from animal models. Pediatr Neurol 2015; 52:566-584. [PMID: 26002050 PMCID: PMC4720385 DOI: 10.1016/j.pediatrneurol.2015.01.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 01/16/2015] [Accepted: 01/24/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND Arterial ischemic stroke occurs more frequently in term newborns than in the elderly, and brain immaturity affects mechanisms of ischemic injury and recovery. The susceptibility to injury of the brain was assumed to be lower in the perinatal period as compared with childhood. This concept was recently challenged by clinical studies showing marked motor disabilities after stroke in neonates, with the severity of motor and cortical sensory deficits similar in both perinatal and childhood ischemic stroke. Our understanding of the triggers and the pathophysiological mechanisms of perinatal stroke has greatly improved in recent years, but many factors remain incompletely understood. METHODS In this review, we focus on the pathophysiology of perinatal stroke and on therapeutic strategies that can protect the immature brain from the consequences of stroke by targeting inflammation and brain microenvironment. RESULTS Studies in neonatal rodent models of cerebral ischemia have suggested a potential role for soluble inflammatory molecules as important modulators of injury and recovery. A great effort is underway to investigate neuroprotective molecules based on our increasing understanding of the pathophysiology. CONCLUSION In this review, we provide a comprehensive summary of new insights concerning pathophysiology of focal and global perinatal brain injury and their implications for new therapeutic approaches.
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Affiliation(s)
- Luigi Titomanlio
- Pediatric Emergency Department, APHP, Robert Debré Hospital, Paris, France
- Inserm, U1141, F-75019 Paris, France
| | - David Fernández-López
- Department of Neurology, University of California San Francisco, San Francisco, CA, 94158-0663, USA
| | - Lucilla Manganozzi
- Pediatric Emergency Department, APHP, Robert Debré Hospital, Paris, France
- Inserm, U1141, F-75019 Paris, France
| | | | - Zinaida S. Vexler
- Department of Neurology, University of California San Francisco, San Francisco, CA, 94158-0663, USA
| | - Pierre Gressens
- Inserm, U1141, F-75019 Paris, France
- Univ Paris Diderot, Sorbonne Paris Cité, UMRS 676, F-75019 Paris, France
- PremUP, Paris, France
- Centre for the Developing Brain, King’s College, St Thomas’ Campus, London SE1 7EH, UK
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Matsuyama T, Tanaka T, Tatsumi K, Daijo H, Kai S, Harada H, Fukuda K. Midazolam inhibits the hypoxia-induced up-regulation of erythropoietin in the central nervous system. Eur J Pharmacol 2015; 761:189-98. [PMID: 26001375 DOI: 10.1016/j.ejphar.2015.05.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 05/08/2015] [Accepted: 05/18/2015] [Indexed: 12/29/2022]
Abstract
Erythropoietin (EPO), a regulator of red blood cell production, is endogenously expressed in the central nervous system. It is mainly produced by astrocytes under hypoxic conditions and has proven to have neuroprotective and neurotrophic effects. In the present study, we investigated the effect of midazolam on EPO expression in primary cultured astrocytes and the mouse brain. Midazolam was administered to 6-week-old BALB/c male mice under hypoxic conditions and pregnant C57BL/6N mice under normoxic conditions. Primary cultured astrocytes were also treated with midazolam under hypoxic conditions. The expression of EPO mRNA in mice brains and cultured astrocytes was studied. In addition, the expression of hypoxia-inducible factor (HIF), known as the main regulator of EPO, was evaluated. Midazolam significantly reduced the hypoxia-induced up-regulation of EPO in BALB/c mice brains and primary cultured astrocytes and suppressed EPO expression in the fetal brain. Midazolam did not affect the total amount of HIF proteins but significantly inhibited the nuclear expression of HIF-1α and HIF-2α proteins. These results demonstrated the suppressive effects of midazolam on the hypoxia-induced up-regulation of EPO both in vivo and in vitro.
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Affiliation(s)
- Tomonori Matsuyama
- Department of Anesthesia, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Tomoharu Tanaka
- Department of Anesthesia, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Kenichiro Tatsumi
- Department of Anesthesia, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hiroki Daijo
- Department of Anesthesia, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Shinichi Kai
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, MA 02114, USA
| | - Hiroshi Harada
- Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Kazuhiko Fukuda
- Department of Anesthesia, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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Abstract
Preconditioning (PC) using a preceding sublethal ischemic insult is an attractive strategy for protecting neurons by inducing ischemic tolerance in the brain. Although the underlying molecular mechanisms have been extensively studied, almost all studies have focused on neurons. Here, using a middle cerebral artery occlusion model in mice, we show that astrocytes play an essential role in the induction of brain ischemic tolerance. PC caused activation of glial cells without producing any noticeable brain damage. The spatiotemporal pattern of astrocytic, but not microglial, activation correlated well with that of ischemic tolerance. Interestingly, such activation in astrocytes lasted at least 8 weeks. Importantly, inhibiting astrocytes with fluorocitrate abolished the induction of ischemic tolerance. To investigate the underlying mechanisms, we focused on the P2X7 receptor as a key molecule in astrocyte-mediated ischemic tolerance. P2X7 receptors were dramatically upregulated in activated astrocytes. PC-induced ischemic tolerance was abolished in P2X7 receptor knock-out mice. Moreover, our results suggest that hypoxia-inducible factor-1α, a well known mediator of ischemic tolerance, is involved in P2X7 receptor-mediated ischemic tolerance. Unlike previous reports focusing on neuron-based mechanisms, our results show that astrocytes play indispensable roles in inducing ischemic tolerance, and that upregulation of P2X7 receptors in astrocytes is essential.
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Smeyne M, Sladen P, Jiao Y, Dragatsis I, Smeyne RJ. HIF1α is necessary for exercise-induced neuroprotection while HIF2α is needed for dopaminergic neuron survival in the substantia nigra pars compacta. Neuroscience 2015; 295:23-38. [PMID: 25796140 DOI: 10.1016/j.neuroscience.2015.03.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 03/05/2015] [Accepted: 03/07/2015] [Indexed: 02/05/2023]
Abstract
Exercise reduces the risk of developing a number of neurological disorders and increases the efficiency of cellular energy production. However, overly strenuous exercise produces oxidative stress. Proper oxygenation is crucial for the health of all tissues, and tight regulation of cellular oxygen is critical to balance O2 levels and redox homeostasis in the brain. Hypoxia Inducible Factor (HIF)1α and HIF2α are transcription factors regulated by cellular oxygen concentration that initiate gene regulation of vascular development, redox homeostasis, and cell cycle control. HIF1α and HIF2α contribute to important adaptive mechanisms that occur when oxygen and ROS homeostasis become unbalanced. It has been shown that preconditioning by exposure to a stressor prior to a hypoxic event reduces damage that would otherwise occur. Previously we reported that 3 months of exercise protects SNpc dopaminergic (DA) neurons from toxicity caused by Complex I inhibition. Here, we identify the cells in the SNpc that express HIF1α and HIF2α and show that running exercise produces hypoxia in SNpc DA neurons, and alters the expression of HIF1α and HIF2α. In mice carrying a conditional knockout of Hif1α in postnatal neurons we observe that exercise alone produces SNpc TH+ DA neuron loss. Loss of HIF1α also abolishes exercise-induced neuroprotection. In mice lacking Hif2α in postnatal neurons, the number of TH+ DA neurons in the adult SNpc is diminished, but 3months of exercise rescues this loss. We conclude that HIF1α is necessary for exercise-induced neuroprotection and both HIF1α and HIF2α are necessary for the survival and function of adult SNpc DA neurons.
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Affiliation(s)
- M Smeyne
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, United States
| | - P Sladen
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, United States
| | - Y Jiao
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, United States
| | - I Dragatsis
- Department of Physiology, The University of Tennessee Health Science Center, 894 Union Avenue, Memphis, TN 38163, United States
| | - R J Smeyne
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, United States.
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Sheldon RA, Sadjadi R, Lam M, Fitzgerald R, Ferriero DM. Alteration in Downstream Hypoxia Gene Signaling in Neonatal Glutathione Peroxidase Overexpressing Mouse Brain after Hypoxia-Ischemia. Dev Neurosci 2015; 37:398-406. [PMID: 25792071 DOI: 10.1159/000375369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 01/19/2015] [Indexed: 11/19/2022] Open
Abstract
We have previously shown that glutathione peroxidase (GPx) overexpressing mice (hGPx-tg) have reduced brain injury after neonatal hypoxia-ischemia (HI) as a consequence of reduced hydrogen peroxide accumulation. However, this protection is reversed with hypoxia preconditioning, raising the question of the roles of the genes regulated by hypoxia-inducible factor-1α (HIF-1α) and their transcription products, such as erythropoietin (EPO), in both the initial protection and subsequent reversal of protection. hGPx-tg and their wild-type (WT) littermates underwent the Vannucci procedure of HI brain injury at postnatal day 9 - left carotid artery ligation followed by exposure to 10% oxygen for 50 min. Brain cortices and hippocampi were subsequently collected 0.5, 4 and 24 h later for the determination of protein expression by Western blot for GPx, HIF-1α, HIF-2α, EPO, EPO receptor, ERK1/2, phospho-ERK1/2, spectrin 145/150 (as a marker of calpain-specific necrotic cell death), and spectrin 120 (as a marker of apoptotic cell death mediated via caspase-3). As expected, the GPx overexpressing mouse cortex had approximately 3 times the GPx expression as WT naïve. Also, GPx expression remained higher in the GPx overexpressing brain than WT at all time points after HI (0.5, 4, 24 h). HIF-1α was not significantly changed in hGPx-tg as a consequence of HI but decreased in the WT cortex 4 h after HI. HIF-2α decreased in the WT hippocampus after HI. EPO was higher in the GPx overexpressing cortex and hippocampus 30 min after HI compared to WT, but the EPO receptor was unchanged by HI. ERK1/2 phosphorylation increased in the hippocampus at 4 h after HI and in the cortex at 24 h after HI in both WT and hGPx-tg. Spectrin 145/150 was increased in the WT cortex at 4 and 24 h after HI, and spectrin 120 increased 24 h after HI, perhaps reflecting greater injury in the WT brain, especially at 24 h when brain injury is more evident. The effect of GPx overexpression does not appear to upregulate the HIF pathway, yet EPO was upregulated, perhaps via ERK. This might explain, in part, why cell death takes a necrotic or apoptotic path. This may also be an explanation for why the GPx overexpressing brain cannot be preconditioned. This information may prove valuable in the development of therapies for neonatal HI brain injury.
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Affiliation(s)
- R Ann Sheldon
- Department of Pediatrics, UCSF Benioff Children's Hospital, University of California San Francisco, San Francisco, Calif., USA
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Milner E, Johnson AW, Nelson JW, Harries MD, Gidday JM, Han BH, Zipfel GJ. HIF-1α Mediates Isoflurane-Induced Vascular Protection in Subarachnoid Hemorrhage. Ann Clin Transl Neurol 2015; 2:325-37. [PMID: 25909079 PMCID: PMC4402079 DOI: 10.1002/acn3.170] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 12/11/2014] [Indexed: 01/05/2023] Open
Abstract
Objective Outcome after aneurysmal subarachnoid hemorrhage (SAH) depends critically on delayed cerebral ischemia (DCI) – a process driven primarily by vascular events including cerebral vasospasm, microvessel thrombosis, and microvascular dysfunction. This study sought to determine the impact of postconditioning – the phenomenon whereby endogenous protection against severe injury is enhanced by subsequent exposure to a mild stressor – on SAH-induced DCI. Methods Adult male C57BL/6 mice were subjected to sham, SAH, or SAH plus isoflurane postconditioning. Neurological outcome was assessed daily via sensorimotor scoring. Contributors to DCI including cerebral vasospasm, microvessel thrombosis, and microvascular dysfunction were measured 3 days later. Isoflurane-induced changes in hypoxia-inducible factor 1alpha (HIF-1α)-dependent genes were assessed via quantitative polymerase chain reaction. HIF-1α was inhibited pharmacologically via 2-methoxyestradiol (2ME2) or genetically via endothelial cell HIF-1α-null mice (EC-HIF-1α-null). All experiments were performed in a randomized and blinded fashion. Results Isoflurane postconditioning initiated at clinically relevant time points after SAH significantly reduced cerebral vasospasm, microvessel thrombosis, microvascular dysfunction, and neurological deficits in wild-type (WT) mice. Isoflurane modulated HIF-1α-dependent genes – changes that were abolished in 2ME2-treated WT mice and EC-HIF-1α-null mice. Isoflurane-induced DCI protection was attenuated in 2ME2-treated WT mice and EC-HIF-1α-null mice. Interpretation Isoflurane postconditioning provides strong HIF-1α-mediated macro- and microvascular protection in SAH, leading to improved neurological outcome. These results implicate cerebral vessels as a key target for the brain protection afforded by isoflurane postconditioning, and HIF-1α as a critical mediator of this vascular protection. They also identify isoflurane postconditioning as a promising novel therapeutic for SAH.
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Affiliation(s)
- Eric Milner
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108 ; Program in Neuroscience, Washington University School of Medicine St. Louis, Missouri, 63108
| | - Andrew W Johnson
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108
| | - James W Nelson
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108
| | - Michael D Harries
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108
| | - Jeffrey M Gidday
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108 ; Hope Center for Neurological Disorders, Washington University School of Medicine St. Louis, Missouri, 63108
| | - Byung Hee Han
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108 ; Hope Center for Neurological Disorders, Washington University School of Medicine St. Louis, Missouri, 63108
| | - Gregory J Zipfel
- Department of Neurological Surgery, Washington University School of Medicine St. Louis, Missouri, 63108 ; Hope Center for Neurological Disorders, Washington University School of Medicine St. Louis, Missouri, 63108 ; Department of Neurology, Washington University School of Medicine St. Louis, Missouri, 63108
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O'Shea RD, Lau CL, Zulaziz N, Maclean FL, Nisbet DR, Horne MK, Beart PM. Transcriptomic analysis and 3D bioengineering of astrocytes indicate ROCK inhibition produces cytotrophic astrogliosis. Front Neurosci 2015; 9:50. [PMID: 25750613 PMCID: PMC4335181 DOI: 10.3389/fnins.2015.00050] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/04/2015] [Indexed: 01/07/2023] Open
Abstract
Astrocytes provide trophic, structural and metabolic support to neurons, and are considered genuine targets in regenerative neurobiology, as their phenotype arbitrates brain integrity during injury. Inhibitors of Rho kinase (ROCK) cause stellation of cultured 2D astrocytes, increased L-glutamate transport, augmented G-actin, and elevated expression of BDNF and anti-oxidant genes. Here we further explored the signposts of a cytotrophic, “healthy” phenotype by data-mining of our astrocytic transcriptome in the presence of Fasudil. Gene expression profiles of motor and autophagic cellular cascades and inflammatory/angiogenic responses were all inhibited, favoring adoption of an anti-migratory phenotype. Like ROCK inhibition, tissue engineered bioscaffolds can influence the extracellular matrix. We built upon our evidence that astrocytes maintained on 3D poly-ε-caprolactone (PCL) electrospun scaffolds adopt a cytotrophic phenotype similar to that produced by Fasudil. Using these procedures, employing mature 3D cultured astrocytes, Fasudil (100 μM) or Y27632 (30 μM) added for the last 72 h of culture altered arborization, which featured numerous additional minor processes as shown by GFAP and AHNAK immunolabelling. Both ROCK inhibitors decreased F-actin, but increased G-actin labeling, indicative of disassembly of actin stress fibers. ROCK inhibitors provide additional beneficial effects for bioengineered 3D astrocytes, including enlargement of the overall arbor. Potentially, the combined strategy of bio-compatible scaffolds with ROCK inhibition offers unique advantages for the management of glial scarring. Overall these data emphasize that manipulation of the astrocyte phenotype to achieve a “healthy biology” offers new hope for the management of inflammation in neuropathologies.
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Affiliation(s)
- Ross D O'Shea
- Department of Physiology, Anatomy and Microbiology, La Trobe University Bundoora, VIC, Australia
| | - Chew L Lau
- Florey Institute of Neuroscience and Mental Health, University of Melbourne Parkville, VIC, Australia
| | - Natasha Zulaziz
- Department of Physiology, Anatomy and Microbiology, La Trobe University Bundoora, VIC, Australia
| | - Francesca L Maclean
- Research School of Engineering, The Australian National University Canberra, ACT, Australia
| | - David R Nisbet
- Research School of Engineering, The Australian National University Canberra, ACT, Australia
| | - Malcolm K Horne
- Florey Institute of Neuroscience and Mental Health, University of Melbourne Parkville, VIC, Australia ; Department of Neurology, St. Vincent's Hospital Fitzroy, VIC, Australia
| | - Philip M Beart
- Florey Institute of Neuroscience and Mental Health, University of Melbourne Parkville, VIC, Australia
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69
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PAN XINTING, ZHU QINGYUN, SUN YUNBO, LI LIANDI, ZHU YUNPENG, ZHAO ZHIHUI, ZUO JIANXIN, FANG WEI, LI KUN. PLGA/poloxamer nanoparticles loaded with EPAS1 siRNA for the treatment of pancreatic cancer in vitro and in vivo. Int J Mol Med 2015; 35:995-1002. [DOI: 10.3892/ijmm.2015.2096] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 02/03/2015] [Indexed: 11/06/2022] Open
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Nagaya Y, Aoyama M, Tamura T, Kakita H, Kato S, Hida H, Saitoh S, Asai K. Inflammatory cytokine tumor necrosis factor α suppresses neuroprotective endogenous erythropoietin from astrocytes mediated by hypoxia-inducible factor-2α. Eur J Neurosci 2014; 40:3620-6. [PMID: 25283246 DOI: 10.1111/ejn.12747] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/04/2014] [Accepted: 09/08/2014] [Indexed: 11/26/2022]
Abstract
Interest in erythropoietin (EPO) as a neuroprotective mediator has grown since it was found that systemically administered EPO is protective in several animal models of disease. However, given that the blood-brain barrier limits EPO entry into the brain, alternative approaches that induce endogenous EPO production in the brain may be more effective clinically and associated with fewer untoward side-effects. Astrocytes are the main source of EPO in the central nervous system. In the present study we investigated the effect of the inflammatory cytokine tumor necrosis factor α (TNFα) on hypoxia-induced upregulation of EPO in rat brain. Hypoxia significantly increased EPO mRNA expression in the brain and kidney, and this increase was suppressed by TNFα in vivo. In cultured astrocytes exposed to hypoxic conditions for 6 and 12 h, TNFα suppressed the hypoxia-induced increase in EPO mRNA expression in a concentration-dependent manner. TNFα inhibition of hypoxia-induced EPO expression was mediated primarily by hypoxia-inducible factor (HIF)-2α rather than HIF-1α. The effects of TNFα in reducing hypoxia-induced upregulation of EPO mRNA expression probably involve destabilization of HIF-2α, which is regulated by the nuclear factor (NF)-κB signaling pathway. TNFα treatment attenuated the protective effects of astrocytes on neurons under hypoxic conditions via EPO signaling. The effective blockade of TNFα signaling may contribute to the maintenance of the neuroprotective effects of EPO even under hypoxic conditions with an inflammatory response.
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Affiliation(s)
- Yoshiaki Nagaya
- Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan; Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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71
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Trollmann R, Richter M, Jung S, Walkinshaw G, Brackmann F. Pharmacologic stabilization of hypoxia-inducible transcription factors protects developing mouse brain from hypoxia-induced apoptotic cell death. Neuroscience 2014; 278:327-42. [PMID: 25162122 DOI: 10.1016/j.neuroscience.2014.08.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 07/25/2014] [Accepted: 08/15/2014] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Accumulation of hypoxia-inducible transcription factors (HIFs) by prolyl-4-hydroxylase inhibitors (PHI) has been suggested to induce neuroprotection in the ischemic rodent brain. We aimed to investigate in vivo effects of a novel PHI on HIF-regulated neurotrophic and pro-apoptotic factors in the developing normoxic and hypoxic mouse brain. METHODS Neonatal mice (P7) were treated with PHI FG-4497 (30-100mg/kg, i.p.) followed by exposure to systemic hypoxia (8% O2, 6h) 4h later. Cerebral expression of HIFα-subunits, specific neurotrophic and vasoactive target genes (vascular endothelial growth factor (VEGF), adrenomedullin (ADM), erythropoietin (EPO), inducible nitric oxide synthase (iNOS)) as well as pro-apoptotic (BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 gene (BNIP3), immediate early response 3 (IER3)) and migratory factors (chemokine receptor 4 (CXCR4), stromal cell-derived factor 1 (SDF-1)) was determined (quantitative real-time (RT)., Western blot analysis) in comparison to controls. Apoptotic cell death was analyzed by terminal desoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and cleaved caspase 3 (CC3) staining. RESULTS Under normoxic conditions, FG-4497 treatment significantly induced the accumulation of both HIF-1α and HIF-2α isoforms in developing mouse brain. In addition, there was a significant up-regulation of HIF target genes (VEGF, ADM, EPO, CXCR4, p<0.01) with FG-4497 treatment compared to controls supporting functional activation of the HIF proteins. Under hypoxia, differential target gene activation was observed in the developing brain including additive effects of FG-4497 and hypoxia on mRNA expression of VEGF and ADM as well as a dose-dependent down-regulation of iNOS. BNIP3 but not IER3 mRNA levels significantly increased in hypoxic brains pre-treated with high-dose FG-4497 compared to controls. Of special interest, FG-4497 treatment significantly diminished apoptotic cell death, quantified by TUNEL and CC3-positive cells, in hypoxic developing brains compared to controls. CONCLUSIONS PHI treatment modulates neurotrophic factors known to be crucially involved in hypoxia-induced cerebral adaptive mechanisms as well as early brain maturation. Pre-treatment with FG-4497 seems to protect the developing brain from hypoxia-induced apoptosis. Present observations provide basic information for further evaluation of neuroprotective properties of PHI treatment in hypoxic injury of the developing brain. However, potential effects on maturational processes need special attention in experimental research targeting HIF-dependent neuroprotective interventions during the very early stage of brain development.
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Affiliation(s)
- R Trollmann
- Department of Pediatrics, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany.
| | - M Richter
- Department of Pediatrics, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | - S Jung
- Department of Pediatrics, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany
| | | | - F Brackmann
- Department of Pediatrics, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany
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Wang L, Di L, Noguchi CT. Erythropoietin, a novel versatile player regulating energy metabolism beyond the erythroid system. Int J Biol Sci 2014; 10:921-39. [PMID: 25170305 PMCID: PMC4147225 DOI: 10.7150/ijbs.9518] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 06/04/2014] [Indexed: 12/12/2022] Open
Abstract
Erythropoietin (EPO), the required cytokine for promoting the proliferation and differentiation of erythroid cells to stimulate erythropoiesis, has been reported to act as a pleiotropic cytokine beyond hematopoietic system. The various activities of EPO are determined by the widespread distribution of its cell surface EPO receptor (EpoR) in multiple tissues including endothelial, neural, myoblasts, adipocytes and other cell types. EPO activity has been linked to angiogenesis, neuroprotection, cardioprotection, stress protection, anti-inflammation and especially the energy metabolism regulation that is recently revealed. The investigations of EPO activity in animals and the expression analysis of EpoR provide more insights on the potential of EPO in regulating energy metabolism and homeostasis. The findings of crosstalk between EPO and some important energy sensors and the regulation of EPO in the cellular respiration and mitochondrial function further provide molecular mechanisms for EPO activity in metabolic activity regulation. In this review, we will summarize the roles of EPO in energy metabolism regulation and the activity of EPO in tissues that are tightly associated with energy metabolism. We will also discuss the effects of EPO in regulating oxidative metabolism and mitochondrial function, the interactions between EPO and important energy regulation factors, and the protective role of EPO from stresses that are related to metabolism, providing a brief overview of previously less appreciated EPO biological function in energy metabolism and homeostasis.
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Affiliation(s)
- Li Wang
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Lijun Di
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Constance Tom Noguchi
- 2. Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, U.S.A
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73
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Abstract
Endocrine erythropoietin (Epo), which is synthesized in the kidney or liver of adult mammals, controls erythrocyte production and is regulated by the stress-responsive transcription factor Hypoxia Inducible Factor 2 (HIF-2). We previously reported that the lysine acetyltransferase Cbp is required for HIF-2α acetylation and efficient HIF-2 dependent Epo induction during hypoxia. We now show these processes require acetate-dependent acetyl CoA synthetase 2 (Acss2). In Hep3B hepatoma cells and in Epo-generating organs of hypoxic or acutely anemic mice, acetate levels increase and Acss2 is required for HIF-2α acetylation, Cbp/HIF-2α complex formation and recruitment to the Epo enhancer, and efficient Epo induction. In acutely anemic mice, acetate supplementation augments stress erythropoiesis in an Acss2-dependent manner. In acquired and genetic chronic anemia mouse models, acetate supplementation also increases Epo expression and resting hematocrits. Thus, a mammalian stress-responsive acetate switch controls HIF-2 signaling and Epo induction during pathophysiological states marked by tissue hypoxia.
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Kurt B, Gerl K, Karger C, Schwarzensteiner I, Kurtz A. Chronic hypoxia-inducible transcription factor-2 activation stably transforms juxtaglomerular renin cells into fibroblast-like cells in vivo. J Am Soc Nephrol 2014; 26:587-96. [PMID: 25071089 DOI: 10.1681/asn.2013111152] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
On the basis of previous observations that deletion of the von Hippel-Lindau protein (pVHL) in juxtaglomerular (JG) cells of the kidney suppresses renin and induces erythropoietin expression, this study aimed to characterize the events underlying this striking change of hormone expression. We found that renin cell-specific deletion of pVHL in mice leads to a phenotype switch in JG cells, from a cuboid and multiple vesicle-containing form into a flat and elongated form without vesicles. This shift of cell phenotype was accompanied by the disappearance of marker proteins for renin cells (e.g., aldo-keto reductase family 1, member 7 and connexin 40) and by the appearance of markers of fibroblast-like cells (e.g., collagen I, ecto-5'-nucleotidase, and PDGF receptor-β). Furthermore, hypoxia-inducible transcription factor-2α (HIF-2α) protein constitutively accumulated in these transformed cells. Codeletion of pVHL and HIF-2α in JG cells completely prevented the phenotypic changes. Similar to renin expression in normal JG cells, angiotensin II negatively regulated erythropoietin expression in the transformed cells. In summary, chronic activation of HIF-2 in renal JG cells leads to a reprogramming of the cells into fibroblast-like cells resembling native erythropoietin-producing cells located in the tubulointerstitium.
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Affiliation(s)
- Birguel Kurt
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Katharina Gerl
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Christian Karger
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | | | - Armin Kurtz
- Institute of Physiology, University of Regensburg, Regensburg, Germany
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Tsui AKY, Marsden PA, Mazer CD, Sled JG, Lee KM, Henkelman RM, Cahill LS, Zhou YQ, Chan N, Liu E, Hare GMT. Differential HIF and NOS responses to acute anemia: defining organ-specific hemoglobin thresholds for tissue hypoxia. Am J Physiol Regul Integr Comp Physiol 2014; 307:R13-25. [DOI: 10.1152/ajpregu.00411.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Tissue hypoxia likely contributes to anemia-induced organ injury and mortality. Severe anemia activates hypoxia-inducible factor (HIF) signaling by hypoxic- and neuronal nitric oxide (NO) synthase- (nNOS) dependent mechanisms. However, organ-specific hemoglobin (Hb) thresholds for increased HIF expression have not been defined. To assess organ-specific Hb thresholds for tissue hypoxia, HIF-α (oxygen-dependent degradation domain, ODD) luciferase mice were hemodiluted to mild, moderate, or severe anemia corresponding to Hb levels of 90, 70, and 50 g/l, respectively. HIF luciferase reporter activity, HIF protein, and HIF-dependent RNA levels were assessed. In the brain, HIF-1α was paradoxically decreased at mild anemia, returned to baseline at moderate anemia, and then increased at severe anemia. Brain HIF-2α remained unchanged at all Hb levels. Both kidney HIF-1α and HIF-2α increased earlier (Hb ∼70–90 g/l) in response to anemia. Liver also exhibited an early HIF-α response. Carotid blood flow was increased early (Hb ∼70, g/l), but renal blood flow remained relatively constant, only increased at Hb of 50 g/l. Anemia increased nNOS (brain and kidney) and endothelia NOS (eNOS) (kidney) levels. Whereas anemia-induced increases in brain HIFα were nNOS-dependent, our current data demonstrate that increased renal HIFα was nNOS independent. HIF-dependent RNA levels increased linearly (∼10-fold) in the brain. However, renal HIF-RNA responses (MCT4, EPO) increased exponentially (∼100-fold). Plasma EPO levels increased near Hb threshold of 90 g/l, suggesting that the EPO response is sensitive. Collectively, these observations suggest that each organ expresses a different threshold for cellular HIF/NOS hypoxia responses. This knowledge may help define the mechanism(s) by which the brain and kidney maintain oxygen homeostasis during anemia.
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Affiliation(s)
- Albert K. Y. Tsui
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Philip A. Marsden
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
- Department of Medicine, Division of Nephrology, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - C. David Mazer
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - John G. Sled
- Department of Medical Biophysics, University of Toronto, Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Keith M. Lee
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
| | - R. Mark Henkelman
- Department of Medical Biophysics, University of Toronto, Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Lindsay S. Cahill
- Department of Medical Biophysics, University of Toronto, Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Yu-Qing Zhou
- Department of Medical Biophysics, University of Toronto, Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Neville Chan
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
| | - Elaine Liu
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Gregory M. T. Hare
- Department of Anesthesia, St. Michael's Hospital, University of Toronto, Ontario, Canada
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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76
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Hempel C, Hoyer N, Kildemoes A, Jendresen CB, Kurtzhals JAL. Systemic and Cerebral Vascular Endothelial Growth Factor Levels Increase in Murine Cerebral Malaria along with Increased Calpain and Caspase Activity and Can be Reduced by Erythropoietin Treatment. Front Immunol 2014; 5:291. [PMID: 24995009 PMCID: PMC4062992 DOI: 10.3389/fimmu.2014.00291] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 06/03/2014] [Indexed: 12/20/2022] Open
Abstract
The pathogenesis of cerebral malaria (CM) includes compromised microvascular perfusion, increased inflammation, cytoadhesion, and endothelial activation. These events cause blood-brain barrier disruption and neuropathology and associations with the vascular endothelial growth factor (VEGF) signaling pathway have been shown. We studied this pathway in mice infected with Plasmodium berghei ANKA causing murine CM with or without the use of erythropoietin (EPO) as adjunct therapy. ELISA and western blotting was used for quantification of VEGF and relevant proteins in brain and plasma. CM increased levels of VEGF in brain and plasma and decreased plasma levels of soluble VEGF receptor 2. EPO treatment normalized VEGF receptor 2 levels and reduced brain VEGF levels. Hypoxia-inducible factor (HIF)-1α was significantly upregulated whereas cerebral HIF-2α and EPO levels remained unchanged. Furthermore, we noticed increased caspase-3 and calpain activity in terminally ill mice, as measured by protease-specific cleavage of α-spectrin and p35. In conclusion, we detected increased cerebral and systemic VEGF as well as HIF-1α, which in the brain were reduced to normal in EPO-treated mice. Also caspase and calpain activity was reduced markedly in EPO-treated mice.
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Affiliation(s)
- Casper Hempel
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital , Copenhagen , Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Nils Hoyer
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital , Copenhagen , Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Anna Kildemoes
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital , Copenhagen , Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Charlotte Bille Jendresen
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital , Copenhagen , Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen , Copenhagen , Denmark
| | - Jørgen Anders Lindholm Kurtzhals
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital , Copenhagen , Denmark ; Department of International Health, Immunology and Microbiology, University of Copenhagen , Copenhagen , Denmark
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77
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Zhang Y, Wang L, Dey S, Alnaeeli M, Suresh S, Rogers H, Teng R, Noguchi CT. Erythropoietin action in stress response, tissue maintenance and metabolism. Int J Mol Sci 2014; 15:10296-333. [PMID: 24918289 PMCID: PMC4100153 DOI: 10.3390/ijms150610296] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 05/23/2014] [Accepted: 05/28/2014] [Indexed: 12/20/2022] Open
Abstract
Erythropoietin (EPO) regulation of red blood cell production and its induction at reduced oxygen tension provides for the important erythropoietic response to ischemic stress. The cloning and production of recombinant human EPO has led to its clinical use in patients with anemia for two and half decades and has facilitated studies of EPO action. Reports of animal and cell models of ischemic stress in vitro and injury suggest potential EPO benefit beyond red blood cell production including vascular endothelial response to increase nitric oxide production, which facilitates oxygen delivery to brain, heart and other non-hematopoietic tissues. This review discusses these and other reports of EPO action beyond red blood cell production, including EPO response affecting metabolism and obesity in animal models. Observations of EPO activity in cell and animal model systems, including mice with tissue specific deletion of EPO receptor (EpoR), suggest the potential for EPO response in metabolism and disease.
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Affiliation(s)
- Yuanyuan Zhang
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Li Wang
- Faculty of Health Sciences, University of Macau, Macau SAR, China.
| | - Soumyadeep Dey
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Mawadda Alnaeeli
- Department of Biological Sciences, Ohio University, Zanesville, OH 43701, USA.
| | - Sukanya Suresh
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Heather Rogers
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Ruifeng Teng
- Mouse Metabolism Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Constance Tom Noguchi
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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78
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Silpanisong J, Pearce WJ. Vasotrophic regulation of age-dependent hypoxic cerebrovascular remodeling. Curr Vasc Pharmacol 2014; 11:544-63. [PMID: 24063376 DOI: 10.2174/1570161111311050002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 06/08/2012] [Accepted: 07/12/2012] [Indexed: 02/07/2023]
Abstract
Hypoxia can induce functional and structural vascular remodeling by changing the expression of trophic factors to promote homeostasis. While most experimental approaches have been focused on functional remodeling, structural remodeling can reflect changes in the abundance and organization of vascular proteins that determine functional remodeling. Better understanding of age-dependent hypoxic macrovascular remodeling processes of the cerebral vasculature and its clinical implications require knowledge of the vasotrophic factors that influence arterial structure and function. Hypoxia can affect the expression of transcription factors, classical receptor tyrosine kinase factors, non-classical G-protein coupled factors, catecholamines, and purines. Hypoxia's remodeling effects can be mediated by Hypoxia Inducible Factor (HIF) upregulation in most vascular beds, but alterations in the expression of growth factors can also be independent of HIF. PPARγ is another transcription factor involved in hypoxic remodeling. Expression of classical receptor tyrosine kinase ligands, including vascular endothelial growth factor, platelet derived growth factor, fibroblast growth factor and angiopoietins, can be altered by hypoxia which can act simultaneously to affect remodeling. Tyrosine kinase-independent factors, such as transforming growth factor, nitric oxide, endothelin, angiotensin II, catecholamines, and purines also participate in the remodeling process. This adaptation to hypoxic stress can fundamentally change with age, resulting in different responses between fetuses and adults. Overall, these mechanisms integrate to assure that blood flow and metabolic demand are closely matched in all vascular beds and emphasize the view that the vascular wall is a highly dynamic and heterogeneous tissue with multiple cell types undergoing regular phenotypic transformation.
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Affiliation(s)
- Jinjutha Silpanisong
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
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79
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Tudisco L, Della Ragione F, Tarallo V, Apicella I, D'Esposito M, Matarazzo MR, De Falco S. Epigenetic control of hypoxia inducible factor-1α-dependent expression of placental growth factor in hypoxic conditions. Epigenetics 2014; 9:600-10. [PMID: 24504136 DOI: 10.4161/epi.27835] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Hypoxia plays a crucial role in the angiogenic switch, modulating a large set of genes mainly through the activation of hypoxia-inducible factor (HIF) transcriptional complex. Endothelial cells play a central role in new vessels formation and express placental growth factor (PlGF), a member of vascular endothelial growth factor (VEGF) family, mainly involved in pathological angiogenesis. Despite several observations suggest a hypoxia-mediated positive modulation of PlGF, the molecular mechanism governing this regulation has not been fully elucidated. We decided to investigate if epigenetic modifications are involved in hypoxia-induced PlGF expression. We report that PlGF expression was induced in cultured human and mouse endothelial cells exposed to hypoxia (1% O 2), although DNA methylation at the Plgf CpG-island remains unchanged. Remarkably, robust hyperacetylation of histones H3 and H4 was observed in the second intron of Plgf, where hypoxia responsive elements (HREs), never described before, are located. HIF-1α, but not HIF-2α, binds to identified HREs. Noteworthy, only HIF-1α silencing fully inhibited PlGF upregulation. These results formally demonstrate a direct involvement of HIF-1α in the upregulation of PlGF expression in hypoxia through chromatin remodeling of HREs sites. Therefore, PlGF may be considered one of the putative targets of anti-HIF therapeutic applications.
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Affiliation(s)
- Laura Tudisco
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy
| | - Floriana Della Ragione
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed; Pozzilli, Italy
| | - Valeria Tarallo
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy
| | - Ivana Apicella
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy
| | - Maurizio D'Esposito
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed; Pozzilli, Italy
| | - Maria Rosaria Matarazzo
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy; Istituto di Ricovero e Cura a Carattere Scientifico Neuromed; Pozzilli, Italy
| | - Sandro De Falco
- Istituto di Genetica e Biofisica "Adriano Buzzati-Traverso"; National Research Council; Napoli, Italy
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80
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Abstract
A transient, ischemia-resistant phenotype known as "ischemic tolerance" can be established in brain in a rapid or delayed fashion by a preceding noninjurious "preconditioning" stimulus. Initial preclinical studies of this phenomenon relied primarily on brief periods of ischemia or hypoxia as preconditioning stimuli, but it was later realized that many other stressors, including pharmacologic ones, are also effective. This review highlights the surprisingly wide variety of drugs now known to promote ischemic tolerance, documented and to some extent mechanistically characterized in preclinical animal models of stroke. Although considerably more experimentation is needed to thoroughly validate the ability of any currently identified preconditioning agent to protect ischemic brain, the fact that some of these drugs are already clinically approved for other indications implies that the growing enthusiasm for translational success in the field of pharmacologic preconditioning may be well justified.
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81
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Li Q, Hakimi P, Liu X, Yu WM, Ye F, Fujioka H, Raza S, Shankar E, Tang F, Dunwoodie SL, Danielpour D, Hoppel CL, Ramírez-Bergeron DL, Qu CK, Hanson RW, Yang YC. Cited2, a transcriptional modulator protein, regulates metabolism in murine embryonic stem cells. J Biol Chem 2013; 289:251-63. [PMID: 24265312 DOI: 10.1074/jbc.m113.497594] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CREB-binding protein (CBP)/p300 interacting transactivator with glutamic acid (Glu) and aspartic acid (Asp)-tail 2 (Cited2) was recently shown to be essential for gluconeogenesis in the adult mouse. The metabolic function of Cited2 in mouse embryonic stem cells (mESCs) remains elusive. In the current study, the metabolism of glucose was investigated in mESCs, which contained a deletion in the gene for Cited2 (Cited2(Δ/-)). Compared with its parental wild type counterpart, Cited2(Δ/-) ESCs have enhanced glycolysis, alternations in mitochondria morphology, reduced glucose oxidation, and decreased ATP content. Cited2 is recruited to the hexokinase 1 (HK1) gene promoter to regulate transcription of HK1, which coordinates glucose metabolism in wild type ESCs. Reduced glucose oxidation and enhanced glycolytic activity in Cited2(Δ/-) ESCs correlates with defective differentiation during hypoxia, which is reflected in an increased expression of pluripotency marker (Oct4) and epiblast marker (Fgf5) and decreased expression of lineage specification markers (T, Gata-6, and Cdx2). Knockdown of hypoxia inducible factor-1α in Cited2(Δ/-) ESCs re-initiates the expression of differentiation markers T and Gata-6. Taken together, a deletion of Cited2 in mESCs results in abnormal mitochondrial morphology and impaired glucose metabolism, which correlates with a defective cell fate decision.
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Affiliation(s)
- Qiang Li
- From the Departments of Biochemistry
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82
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Yang C, Rahimpour S, Yu ACH, Lonser RR, Zhuang Z. Regulation and dysregulation of astrocyte activation and implications in tumor formation. Cell Mol Life Sci 2013; 70:4201-11. [PMID: 23420481 PMCID: PMC11113190 DOI: 10.1007/s00018-013-1274-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 01/11/2013] [Accepted: 01/22/2013] [Indexed: 01/06/2023]
Abstract
Astrocytic activation is a cellular response to disturbances of the central nervous system (CNS). Recent advances in cellular and molecular biology have demonstrated the remarkable changes in molecular signaling, morphology, and metabolism that occur during astrocyte activation. Based on these studies, it has become clear that the astrocyte activation process is regulated by a variety of signaling pathways, which result in metabolic support, wound healing and scar formation. While normal astrocyte activation pathways drive homeostasis and/or repair in the CNS, dysregulation of these pathways can lead to astrocyte abnormalities, including glioma formation with similar phenotypes as reactive astrocytes. We review the principle pathways responsible for astrocytic activation, as well as their potential contribution to tumor formation in the CNS.
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Affiliation(s)
- Chunzhang Yang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 3D20, Bethesda, Maryland 20892-1414 USA
| | - Shervin Rahimpour
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 3D20, Bethesda, Maryland 20892-1414 USA
| | - Albert C. H. Yu
- Neuroscience Research Institute, Key Laboratory of Neuroscience (Ministry of Education), Key Laboratory for Neuroscience (Ministry of Public Health), Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Russell R. Lonser
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 3D20, Bethesda, Maryland 20892-1414 USA
| | - Zhengping Zhuang
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 3D20, Bethesda, Maryland 20892-1414 USA
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83
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Porzionato A, Macchi V, Zaramella P, Sarasin G, Grisafi D, Dedja A, Chiandetti L, De Caro R. Effects of postnatal hyperoxia exposure on the rat dentate gyrus and subventricular zone. Brain Struct Funct 2013; 220:229-47. [PMID: 24135771 DOI: 10.1007/s00429-013-0650-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 10/04/2013] [Indexed: 12/27/2022]
Abstract
Premature newborns may be exposed to hyperoxia in the first postnatal period, but clinical and experimental works have raised the question of oxygen toxicity for the developing brain. However, specific analysis of hyperoxia exposure on neurogenesis is still lacking. Thus, the aim of the present study was to evaluate possible changes in the morphometric parameters of the main neurogenic sites in newborn rats exposed to 60 or 95 % oxygen for the first 14 postnatal days. The optical disector, a morphometric method based upon unbiased sampling principles of stereology, was applied to analyse cell densities, total volumes, and total cell numbers of the dentate gyrus (DG) and subventricular zone (SVZ). Apoptosis and proliferation were also studied by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling method and anti-ki67 immunohistochemistry, respectively. Severe hyperoxia increased the percentage of apoptotic cells in the DG. Moderate and severe hyperoxia induced a proliferative response both in the DG and SVZ, but the two neurogenic sites showed different changes in their morphometric parameters. The DG of both the hyperoxic groups showed lower volume and total cell number than that of the normoxic one. Conversely, the SVZ of newborn rats exposed to 95 % hyperoxia showed statistically significant higher volume and total cell number than SVZ of rats raised in normoxia. Our findings indicate that hyperoxia exposure in the first postnatal period affects both the neurogenic areas, although in different ways, i.e. reduction of DG and expansion of SVZ.
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Affiliation(s)
- Andrea Porzionato
- Section of Anatomy, Department of Molecular Medicine, University of Padova, Via A Gabelli 65, 35127, Padua, Italy
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84
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Hogan AM, Shipolini A, Brown MM, Hurley R, Cormack F. Fixing hearts and protecting minds: a review of the multiple, interacting factors influencing cognitive function after coronary artery bypass graft surgery. Circulation 2013; 128:162-71. [PMID: 23836829 DOI: 10.1161/circulationaha.112.000701] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Alexandra M Hogan
- MBBS, Developmental Cognitive Neuroscience Unit, UCL Institute of Child Health, 30 Guildford St, London, WC1E 6BT, United Kingdom.
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85
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A Recombinant Inhibitory Isoform of Vascular Endothelial Growth Factor164/165 Aggravates Ischemic Brain Damage in a Mouse Model of Focal Cerebral Ischemia. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:1010-24. [DOI: 10.1016/j.ajpath.2013.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 06/03/2013] [Accepted: 06/05/2013] [Indexed: 02/07/2023]
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86
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Befani C, Mylonis I, Gkotinakou IM, Georgoulias P, Hu CJ, Simos G, Liakos P. Cobalt stimulates HIF-1-dependent but inhibits HIF-2-dependent gene expression in liver cancer cells. Int J Biochem Cell Biol 2013; 45:2359-68. [PMID: 23958427 DOI: 10.1016/j.biocel.2013.07.025] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 07/01/2013] [Accepted: 07/29/2013] [Indexed: 01/08/2023]
Abstract
Hypoxia-inducible factors (HIFs) are transcriptional regulators that mediate the cellular response to low oxygen. Although HIF-1 is usually considered as the principal mediator of hypoxic adaptation, several tissues and different cell types express both HIF-1 and HIF-2 isoforms under hypoxia or when treated with hypoxia mimetic chemicals such as cobalt. However, the similarities or differences between HIF-1 and HIF-2, in terms of their tissue- and inducer-specific activation and function, are not adequately characterized. To address this issue, we investigated the effects of true hypoxia and hypoxia mimetics on HIF-1 and HIF-2 induction and specific gene transcriptional activity in two hepatic cancer cell lines, Huh7 and HepG2. Both hypoxia and cobalt caused rapid induction of both HIF-1α and HIF-2α proteins. Hypoxia induced erythropoietin (EPO) expression and secretion in a HIF-2-dependent way. Surprisingly, however, EPO expression was not induced when cells were treated with cobalt. In agreement, both HIF-1- and HIF-2-dependent promoters (of PGK and SOD2 genes, respectively) were activated by hypoxia while cobalt only activated the HIF-1-dependent PGK promoter. Unlike cobalt, other hypoxia mimetics such as DFO and DMOG activated both types of promoters. Furthermore, cobalt impaired the hypoxic stimulation of HIF-2, but not HIF-1, activity and cobalt-induced HIF-2α interacted poorly with USF-2, a HIF-2-specific co-activator. These data show that, despite similar induction of HIF-1α and HIF-2α protein expression, HIF-1 and HIF-2 specific gene activating functions respond differently to different stimuli and suggest the operation of oxygen-independent and gene- or tissue-specific regulatory mechanisms involving additional transcription factors or co-activators.
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Affiliation(s)
- Christina Befani
- Laboratory of Biochemistry, Faculty of Medicine, School of Health Sciences, University of Thessaly, Biopolis, Larissa 41110, Greece
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87
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Jones SM, Novak AE, Elliott JP. The role of HIF in cobalt-induced ischemic tolerance. Neuroscience 2013; 252:420-30. [PMID: 23916558 DOI: 10.1016/j.neuroscience.2013.07.060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/25/2013] [Accepted: 07/25/2013] [Indexed: 12/27/2022]
Abstract
Understanding the endogenous survival pathways induced by ischemic tolerance may yield targets for neuroprotection from stroke. One well-studied pathway reported to be evoked by preconditioning stimuli is the transcription factor HIF (hypoxia-inducible factor). However, whether HIF induction by ischemic insults is neuroprotective or toxic is still unclear. We examined the ability of three prolyl-hydroxylase inhibitors, which induce HIF, to protect hippocampal cultures from oxygen-glucose deprivation. Hippocampal cultures were exposed to ischemic preconditioning or various concentrations of cobalt chloride, deferoxamine (DFO) or dimethyloxylalyglycine (DMOG), prior to lethal oxygen-glucose deprivation (OGD). Cell survival of neurons and astrocytes was determined with dual-label immunocytochemistry. The induction of HIF targets was assessed in mixed as well as astrocyte-enriched cultures. Ischemic preconditioning, as well as low concentrations of cobalt and DFO, enhanced the survival of neurons following OGD. However, DMOG exacerbates OGD-induced neuronal death. At low concentrations, all three prolyl-hydroxylase (PHD) inhibitors increased the survival of astrocytes. Neuroprotective concentrations of cobalt induced the transcription of the cytokine erythropoietin (EPO) in astrocyte cultures. In addition, pretreatment with recombinant human erythropoietin (rH-EPO) also protected neurons from OGD. Our data suggest that HIF-induced EPO, released from astrocytes, protects neurons from OGD. However, the three PHD inhibitors each exhibited different neuroprotective profiles at low concentrations, suggesting that not all PHD inhibitors are created equal. The protective effects at low doses is reminiscent of HIF involvement in ischemic tolerance, in which sub-lethal insults induce HIF pathways resulting in neuroprotection, whereas the high-dose toxicity suggests that over-activation of HIF is not always protective. Therefore, the choice of inhibitor and dose may determine the clinical utility of these compounds. Deferoxamine exhibited little toxicity even at higher doses, and therefore appears a promising candidate for clinical use.
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Affiliation(s)
- S M Jones
- Swedish Medical Center, Englewood, CO 80113, USA.
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88
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Sun YY, Lin SH, Lin HC, Hung CC, Wang CY, Lin YC, Hung KS, Lien CC, Kuan CY, Lee YH. Cell type-specific dependency on the PI3K/Akt signaling pathway for the endogenous Epo and VEGF induction by baicalein in neurons versus astrocytes. PLoS One 2013; 8:e69019. [PMID: 23904909 PMCID: PMC3719842 DOI: 10.1371/journal.pone.0069019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/04/2013] [Indexed: 02/06/2023] Open
Abstract
The neuroprotective effect of baicalein is generally attributed to inhibition of
12/15-lipoxygenase (12/15-LOX) and suppression of oxidative stress, but recent
studies showed that baicalein also activates hypoxia-inducible factor-α (HIF1α)
through inhibition of prolyl hydrolase 2 (PHD2) and activation of the
phosphatidylinositide-3 kinase (PI3K)/Akt signaling pathway. Yet, the
significance and regulation of prosurvival cytokines erythropoietin (Epo) and
vascular endothelial growth factor (VEGF), two transcriptional targets of HIF1α,
in baicalein-mediated neuroprotection in neurons and astrocytes remains unknown.
Here we investigated the causal relationship between the PI3K/Akt signaling
pathway and Epo/VEGF expression in baicalein-mediated neuroprotection in primary
rat cortical neurons and astrocytes. Our results show that baicalein induced Epo
and VEGF expression in a HIF1α- and PI3K/Akt-dependent manner in neurons.
Baicalein also protected neurons against excitotoxicity in a PI3K- and
Epo/VEGF-dependent manner without affecting neuronal excitability. In contrast,
at least a 10-fold higher concentration of baicalein was needed to induce
Epo/VEGF production and PI3K/Akt activity in astrocytes for protection of
neurons. Moreover, only baicalein-induced astrocytic VEGF, but not Epo
expression requires HIF1α, while PI3K/Akt signaling had little role in
baicalein-induced astrocytic Epo/VEGF expression. These results suggest distinct
mechanisms of baicalein-mediated Epo/VEGF production in neurons and astrocytes
for neuroprotection, and provide new insights into the mechanisms and potential
of baicalein in treating brain injury in vivo.
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Affiliation(s)
- Yu-Yo Sun
- Division of Neurology, Department of Pediatrics, the Center for
Neurodegenerative Disease, Emory University School of Medicine, Atlanta,
Georgia, United States of America
| | - Shang-Hsuan Lin
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
| | - Hung-Cheng Lin
- Graduate Institute of Medical Sciences, Taipei Medical University,
Taipei, Taiwan
| | - Chia-Chi Hung
- Graduate Institute of Medical Sciences, Taipei Medical University,
Taipei, Taiwan
| | - Chen-Yu Wang
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
| | - Yen-Chu Lin
- Institute of Neuroscience, National Yang-Ming University, Taipei,
Taiwan
| | - Kuo-Sheng Hung
- Department of Neurosurgery, Taipei Medical University Wan Fang Hospital,
Taipei, Taiwan
| | - Cheng-Chang Lien
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
- Institute of Neuroscience, National Yang-Ming University, Taipei,
Taiwan
| | - Chia-Yi Kuan
- Division of Neurology, Department of Pediatrics, the Center for
Neurodegenerative Disease, Emory University School of Medicine, Atlanta,
Georgia, United States of America
| | - Yi-Hsuan Lee
- Department and Institute of Physiology, National Yang-Ming University,
Taipei, Taiwan
- Brain Research Center, National Yang-Ming University, Taipei,
Taiwan
- * E-mail:
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89
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Günter CI, Bader A, Dornseifer U, Egert S, Dunda S, Grieb G, Wolter T, Pallua N, von Wild T, Siemers F, Mailänder P, Thamm O, Ernert C, Steen M, Sievers R, Reichert B, Rahmanian-Schwarz A, Schaller H, Hartmann B, Otte M, Kehl V, Ohmann C, Jelkmann W, Machens HG. A multi-center study on the regenerative effects of erythropoietin in burn and scalding injuries: study protocol for a randomized controlled trial. Trials 2013; 14:124. [PMID: 23782555 PMCID: PMC3653694 DOI: 10.1186/1745-6215-14-124] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 03/07/2013] [Indexed: 11/13/2022] Open
Abstract
Background Although it was initially assumed that erythropoietin (EPO) was a hormone that only affected erythropoiesis, it has now been proposed that EPO plays an additional key role in the regulation of acute and chronic tissue damage. Via the inhibition of inflammatory reactions and of apoptosis, stem cell recruitment, advancement of angiogenesis and growth factor release, EPO enhances healing and thus restitutio ad integrum after trauma. Human skin contains EPO receptors and is able to synthesize EPO. We therefore hypothesize that EPO is able to optimize wound healing in thermally injured patients. Methods/Design This is a large, prospective, randomized, double-blind, multi-center study, funded by the German Federal Ministry of Education and Research, and fully approved by the designated ethics committee. The trial, which is to investigate the effects of EPO in severely burned patients, is in its recruitment phase and is being carried out in 13 German burn care centers. A total of 150 patients are to be enrolled to receive study medication every other day for 21 days (EPO 150 IU/kg body weight or placebo). A follow-up of one year is planned. The primary endpoint of this study is the time until complete re-epithelialization of a defined skin graft donor site is reached. Furthermore, clinical parameters such as wound healing, scar formation (using the Vancouver scar scale), laboratory values, quality of life (SF-36), angiogenic effects, and gene- and protein-expression patterns are to be determined. The results will be carefully evaluated for gender differences. Discussion We are seeking new insights into the mechanisms of wound healing in thermally injured patients and more detailed information about the role EPO plays, specifically in these complex interactions. We additionally expect that the biomimetic effects of EPO will be useful in the treatment of acute thermal dermal injuries. Trial registration EudraCT Number: 2006-002886-38, Protocol Number: 0506, ISRCT Number: http://controlled-trials.com/ISRCTN95777824/ISRCTN95777824.
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90
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Vascular growth factors in neuropsychiatry. Cell Mol Life Sci 2013; 70:1739-52. [PMID: 23475069 DOI: 10.1007/s00018-013-1281-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 01/28/2013] [Accepted: 01/28/2013] [Indexed: 01/03/2023]
Abstract
Recent advances in understanding the cellular and molecular basis of psychiatric illnesses have shed light on the important role played by trophic factors in modulating functional parameters associated with disease causality and drug action. Disease mechanisms are now thought to involve multiple cell types, including neurons and endothelial cells. These functionally distinct but interactively coupled cell types engage in cellular cross talk via shared and common signaling molecules. Dysregulation in their cellular signaling pathways influences brain function and alters behavioral performance. Multifunctional trophic factors such as VEGF and EPO that possess both neurotrophic and angiogenic actions are of particular interest due to their ability to rescue structural and plasticity deficits in neurons and vasculature. Obtaining insight into the behavioral, cellular and molecular actions of multi-functional trophic factors has the potential to open new and transformative therapeutic approaches.
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91
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Kurt B, Paliege A, Willam C, Schwarzensteiner I, Schucht K, Neymeyer H, Sequeira-Lopez MLS, Bachmann S, Gomez RA, Eckardt KU, Kurtz A. Deletion of von Hippel-Lindau protein converts renin-producing cells into erythropoietin-producing cells. J Am Soc Nephrol 2013; 24:433-44. [PMID: 23393316 DOI: 10.1681/asn.2012080791] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
States of low perfusion pressure of the kidney associate with hyperplasia or expansion of renin-producing cells, but it is unknown whether hypoxia-triggered genes contribute to these changes. Here, we stabilized hypoxia-inducible transcription factors (HIFs) in mice by conditionally deleting their negative regulator, Vhl, using the Cre/loxP system with renin-1d promoter-driven Cre expression. Vhl (−/−(REN)) mice were viable and had normal BP. Deletion of Vhl resulted in constitutive accumulation of HIF-2α in afferent arterioles and glomerular cells and HIF-1α in collecting duct cells of the adult kidney. The preglomerular vascular tree developed normally, but far fewer renin-expressing cells were present, with more than 70% of glomeruli not containing renin cells at the typical juxtaglomerular position. Moreover, these mice had an attenuated expansion of renin-producing cells in response to a low-salt diet combined with an ACE inhibitor. However, renin-producing cells of Vhl (−/−(REN)) mice expressed the erythropoietin gene, and they were markedly polycythemic. Taken together, these results suggest that hypoxia-inducible genes, regulated by VHL, are essential for normal development and physiologic adaptation of renin-producing cells. In addition, deletion of Vhl shifts the phenotype of juxtaglomerular cells from a renin- to erythropoietin-secreting cell type, presumably in response to HIF-2 accumulation.
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Affiliation(s)
- Birguel Kurt
- Institute of Physiology, University of Regensburg, D-93053 Regensburg, Germany.
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92
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Abstract
A classic physiologic response to systemic hypoxia is the increase in red blood cell production. Hypoxia-inducible factors (HIFs) orchestrate this response by inducing cell-type specific gene expression changes that result in increased erythropoietin (EPO) production in kidney and liver, in enhanced iron uptake and utilization and in adjustments of the bone marrow microenvironment that facilitate erythroid progenitor maturation and proliferation. In particular HIF-2 has emerged as the transcription factor that regulates EPO synthesis in the kidney and liver and plays a critical role in the regulation of intestinal iron uptake. Its key function in the hypoxic regulation of erythropoiesis is underscored by genetic studies in human populations that live at high-altitude and by mutational analysis of patients with familial erythrocytosis. This review provides a perspective on recent insights into HIF-controlled erythropoiesis and iron metabolism, and examines cell types that have EPO-producing capability. Furthermore, the review summarizes clinical syndromes associated with mutations in the O(2)-sensing pathway and the genetic changes that occur in high altitude natives. The therapeutic potential of pharmacologic HIF activation for the treatment of anemia is discussed.
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Affiliation(s)
- Volker H Haase
- Department of Medicine, Vanderbilt School of Medicine, Nashville, TN, USA.
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93
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Benderro GF, Tsipis CP, Sun X, Kuang Y, LaManna JC. Increased HIF-1α and HIF-2α Accumulation, but Decreased Microvascular Density, in Chronic Hyperoxia and Hypercapnia in the Mouse Cerebral Cortex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 789:29-35. [DOI: 10.1007/978-1-4614-7411-1_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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94
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Abstract
The hematopoietic growth factor erythropoietin (Epo) circulates in plasma and controls the oxygen carrying capacity of the blood (Fisher. Exp Biol Med (Maywood) 228:1-14, 2003). Epo is produced primarily in the adult kidney and fetal liver and was originally believed to play a role restricted to stimulation of early erythroid precursor proliferation, inhibition of apoptosis, and differentiation of the erythroid lineage. Early studies showed that mice with targeted deletion of Epo or the Epo receptor (EpoR) show impaired erythropoiesis, lack mature erythrocytes, and die in utero around embryonic day 13.5 (Wu et al. Cell 83:59-67, 1995; Lin et al. Genes Dev. 10:154-164, 1996). These animals also exhibited heart defects, abnormal vascular development as well as increased apoptosis in the brain suggesting additional functions for Epo signaling in normal development of the central nervous system and heart. Now, in addition to its well-known role in erythropoiesis, a diverse array of cells have been identified that produce Epo and/or express the Epo-R including endothelial cells, smooth muscle cells, and cells of the central nervous system (Masuda et al. J Biol Chem. 269:19488-19493, 1994; Marti et al. Eur J Neurosci. 8:666-676, 1996; Bernaudin et al. J Cereb Blood Flow Metab. 19:643-651, 1999; Li et al. Neurochem Res. 32:2132-2141, 2007). Endogenously produced Epo and/or expression of the EpoR gives rise to autocrine and paracrine signaling in different organs particularly during hypoxia, toxicity, and injury conditions. Epo has been shown to regulate a variety of cell functions such as calcium flux (Korbel et al. J Comp Physiol B. 174:121-128, 2004) neurotransmitter synthesis and cell survival (Velly et al. Pharmacol Ther. 128:445-459, 2010; Vogel et al. Blood. 102:2278-2284, 2003). Furthermore Epo has neurotrophic effects (Grimm et al. Nat Med. 8:718-724, 2002; Junk et al. Proc Natl Acad Sci U S A. 99:10659-10664, 2002), can induce an angiogenic phenotype in cultured endothelial cells and is a potent angiogenic factor in vivo (Ribatti et al. Eur J Clin Invest. 33:891-896, 2003) and might enhance ventilation in hypoxic conditions (Soliz et al. J Physiol. 568:559-571, 2005; Soliz et al. J Physiol. 583, 329-336, 2007). Thus multiple functions have been identified breathing new life and exciting possibilities into what is really an old growth factor.This review will address the function of Epo in non-hematopoietic tissues with significant emphasis on the brain and heart.
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Affiliation(s)
- Omolara O Ogunshola
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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95
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Benderro GF, LaManna JC. Kidney EPO expression during chronic hypoxia in aged mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 765:9-14. [PMID: 22879008 DOI: 10.1007/978-1-4614-4989-8_2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In order to maintain normal cellular function, mammalian tissue oxygen concentrations must be tightly regulated within a narrow physiological range. The hormone erythropoietin (EPO) is essential for maintenance of tissue oxygen supply by stimulating red blood cell production and promoting their survival. In this study we compared the effects of 290 Torr atmospheric pressure on the kidney EPO protein levels in young (4-month-old) and aged (24-month-old) C57BL/6 mice. The mice were sacrificed after being anesthetized, and kidney samples were collected and processed by Western blot analysis. Relatively low basal expression of EPO during normoxia in young mice showed significant upregulation in hypoxia and stayed upregulated throughout the hypoxic period (threefold compared to normoxic control), showing a slight decline toward the third week. Whereas, a relatively higher normoxic basal EPO protein level in aged mice did not show significant increase until seventh day of hypoxia, but showed significant upregulation in prolonged hypoxia. Hence, we confirmed that there is a progressively increased accumulation of EPO during chronic hypoxia in young and aged mouse kidney, and the EPO upregulation during hypoxia showed a similarity with the pattern of increase in hematocrit, which we have reported previously.
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Affiliation(s)
- Girriso F Benderro
- Department of Anatomy, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Joseph C LaManna
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Robbins E 611, Cleveland, OH, 44106-4970, USA.
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96
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Baburamani AA, Ek CJ, Walker DW, Castillo-Melendez M. Vulnerability of the developing brain to hypoxic-ischemic damage: contribution of the cerebral vasculature to injury and repair? Front Physiol 2012; 3:424. [PMID: 23162470 PMCID: PMC3493883 DOI: 10.3389/fphys.2012.00424] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/17/2012] [Indexed: 11/13/2022] Open
Abstract
As clinicians attempt to understand the underlying reasons for the vulnerability of different regions of the developing brain to injury, it is apparent that little is known as to how hypoxia-ischemia may affect the cerebrovasculature in the developing infant. Most of the research investigating the pathogenesis of perinatal brain injury following hypoxia-ischemia has focused on excitotoxicity, oxidative stress and an inflammatory response, with the response of the developing cerebrovasculature receiving less attention. This is surprising as the presentation of devastating and permanent injury such as germinal matrix-intraventricular haemorrhage (GM-IVH) and perinatal stroke are of vascular origin, and the origin of periventricular leukomalacia (PVL) may also arise from poor perfusion of the white matter. This highlights that cerebrovasculature injury following hypoxia could primarily be responsible for the injury seen in the brain of many infants diagnosed with hypoxic-ischemic encephalopathy (HIE). Interestingly the highly dynamic nature of the cerebral blood vessels in the fetus, and the fluctuations of cerebral blood flow and metabolic demand that occur following hypoxia suggest that the response of blood vessels could explain both regional protection and vulnerability in the developing brain. However, research into how blood vessels respond following hypoxia-ischemia have mostly been conducted in adult models of ischemia or stroke, further highlighting the need to investigate how the developing cerebrovasculature responds and the possible contribution to perinatal brain injury following hypoxia. This review discusses the current concepts on the pathogenesis of perinatal brain injury, the development of the fetal cerebrovasculature and the blood brain barrier (BBB), and key mediators involved with the response of cerebral blood vessels to hypoxia.
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Affiliation(s)
- Ana A Baburamani
- The Ritchie Centre, Monash Medical Centre, Monash Institute of Medical Research, Clayton Melbourne, VIC, Australia ; Sahlgrenska Academy, Gothenburg University Göteborg, Sweden
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97
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Gundemir S, Colak G, Feola J, Blouin R, Johnson GVW. Transglutaminase 2 facilitates or ameliorates HIF signaling and ischemic cell death depending on its conformation and localization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1-10. [PMID: 23085038 DOI: 10.1016/j.bbamcr.2012.10.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 10/09/2012] [Accepted: 10/10/2012] [Indexed: 12/26/2022]
Abstract
Transglutaminase 2 (TG2) is a widely expressed and multifunctional protein that modulates cell death/survival processes. We have previously shown that TG2 binds to hypoxia inducible factor 1β (HIF1β) and decreases the upregulation of HIF responsive genes; however, the relationship between these observations was not investigated. In this study, we investigated whether endogenous TG2 is sufficient to suppress HIF activity and whether the interaction between TG2 and HIF1β is required for this suppression. shRNA-mediated silencing of TG2 significantly enhanced HIF activation in response to hypoxia. In addition, nuclear localization of TG2 is required for its suppressive effect on HIF activity, with TG2 being recruited to HIF responsive promoters in hypoxic conditions. These observations suggest that TG2 directly regulates hypoxic transcriptional machinery; however, its interaction with HIF1β was not required for this regulation. We also examined whether TG2's effect on cell death/survival processes in ischemia is due to its effects on HIF signaling. Our results indicate that TG2 mediated HIF suppression can be separated from TG2's effect on cell survival in hypoxic/hypoglycemic conditions. Lastly, here we show that nuclear TG2 in the closed conformation and non-nuclear TG2 in the open conformation have opposing effects on hypoxic/hypoglycemic cell death, which could explain previous controversial results. Overall, our results further clarify the role of TG2 in mediating the cellular response to ischemia and suggest that manipulating the conformation of TG2 might be of pharmacological interest as a therapeutic strategy for the treatment of ischemia-related pathologies.
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Affiliation(s)
- Soner Gundemir
- Department of Anesthesiology, University of Rochester, Rochester, NY, USA
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98
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Sen Banerjee S, Thirunavukkarasu M, Tipu Rishi M, Sanchez JA, Maulik N, Maulik G. HIF-prolyl hydroxylases and cardiovascular diseases. Toxicol Mech Methods 2012; 22:347-58. [PMID: 22424133 DOI: 10.3109/15376516.2012.673088] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prolyl hydroxylases belong to the family of iron- and 2-oxoglutamate-dependent dioxygenase enzyme. Several distinct prolyl hydroxylases have been identified. The hypoxia-inducible factor (HIF) prolyl hydroxylase termed prolyl hydroxylase domain (PHD) enzymes play an important role in oxygen regulation in the physiological network. There are three isoforms that have been identified: PHD1, PHD2 and PHD3. Deletion of PHD enzymes result in stabilization of HIFs and offers potential treatment options for many ischemic disorders such as peripheral arterial occlusive disease, myocardial infarction, and stroke. All three isoforms are oxygen sensors that regulate the stability of HIFs. The degradation of HIF-1α is regulated by hydroxylation of the 402/504 proline residue by PHDs. Under hypoxic conditions, lack of oxygen causes hydroxylation to cease HIF-1α stabilization and subsequent translocation to the nucleus where it heterodimerizes with the constitutively expressed β subunit. Binding of the HIF-heterodimer to specific DNA sequences, named hypoxia-responsive elements, triggers the transactivation of target genes. PHD regulation of HIF-1α-mediated cardioprotection has resulted in considerable interest in these molecules as potential therapeutic targets in cardiovascular and ischemic diseases. In recent years, attention has been directed towards identifying small molecule inhibitors of PHD. It is postulated that such inhibition might lead to a clinically useful strategy for protecting the myocardium against ischemia and reperfusion injury. Recently, it has been reported that the orally absorbed PHD inhibitor GSK360A can modulate HIF-1α signaling and protect the failing heart following myocardial infarction. Furthermore, PHD1 deletion has been found to have beneficial effects through an increase in tolerance to hypoxia of skeletal muscle by reprogramming basal metabolism. In the mouse liver, such deletion has resulted in protection against ischemia and reperfusion. As a result of these preliminary findings, PHDs is attracting increasing interest as potential therapeutic targets in a wide range of diseases.
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Affiliation(s)
- Sucharita Sen Banerjee
- Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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99
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Stahr A, Frahm C, Kretz A, Bondeva T, Witte O, Wolf G. Morg1+/− heterozygous mice are protected from experimentally induced focal cerebral ischemia. Brain Res 2012; 1482:22-31. [DOI: 10.1016/j.brainres.2012.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 08/25/2012] [Accepted: 09/10/2012] [Indexed: 01/13/2023]
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100
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Benderro GF, Sun X, Kuang Y, Lamanna JC. Decreased VEGF expression and microvascular density, but increased HIF-1 and 2α accumulation and EPO expression in chronic moderate hyperoxia in the mouse brain. Brain Res 2012; 1471:46-55. [PMID: 22820296 DOI: 10.1016/j.brainres.2012.06.055] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 06/09/2012] [Accepted: 06/28/2012] [Indexed: 12/01/2022]
Abstract
Normal brain function is dependent on continuous and controlled oxygen delivery. Chronic moderate hypoxia leads to angiogenesis, suggesting a modulatory role for oxygen in determining capillary density. The objective of this study was to determine physiologic and brain angiogenic adaptational changes during chronic moderate normobaric hyperoxia in mice. Four-month old C56BL/6J mice were kept in a normobaric chamber at 50% O(2) for up to 3 weeks. Normoxic littermates were kept in the same room outside the chamber. Freshly collected or fixed brain specimens were analyzed by RT-PCR, Western blot analysis and immunohistochemistry. Results show accumulation of hypoxia inducible factors 1 and 2α (HIF-1 and 2α), and increased expression of erythropoietin (EPO), cyclooxygenase-2 (COX-2) and angiopoietin-2 (Ang-2). Conversely, vascular endothelial growth factor (VEGF), and VEGF receptor-2 (KDR/Flk-1), Peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and prolylhydroxylase-2 (PHD-2) expressions were decreased. VEGF mRNA level was diminished but there was no change in HIF-1α mRNA and von Hippel Lindau E3 ubiquitin ligase (VHL) protein expression. Microvascular density was significantly diminished by the end of the 3rd week of hyperoxia. Overall, our results are: (1) increased expression of the potent neuroprotective molecule, EPO; (2) diminished expression of the potent angiogenic factor, VEGF; and (3) decreased microvascular density. We can, therefore, conclude that brain microvascular density can be controlled by HIF-independent mechanisms, and that brain capillary density is a continuously adjusted variable with tissue oxygen availability as one of the controlling modulators.
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Affiliation(s)
- Girriso F Benderro
- Department of Anatomy, Case Western Reserve University, Cleveland, OH, USA
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