1
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Leslie E, Lopez V, Anti NAO, Alvarez R, Kafeero I, Welsh DG, Romero M, Kaushal S, Johnson CM, Bosviel R, Blaženović I, Song R, Brito A, Frano MRL, Zhang L, Newman JW, Fiehn O, Wilson SM. Gestational long-term hypoxia induces metabolomic reprogramming and phenotypic transformations in fetal sheep pulmonary arteries. Am J Physiol Lung Cell Mol Physiol 2021; 320:L770-L784. [PMID: 33624555 DOI: 10.1152/ajplung.00469.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Gestational long-term hypoxia increases the risk of myriad diseases in infants including persistent pulmonary hypertension. Similar to humans, fetal lamb lung development is susceptible to long-term intrauterine hypoxia, with structural and functional changes associated with the development of pulmonary hypertension including pulmonary arterial medial wall thickening and dysregulation of arterial reactivity, which culminates in decreased right ventricular output. To further explore the mechanisms associated with hypoxia-induced aberrations in the fetal sheep lung, we examined the premise that metabolomic changes and functional phenotypic transformations occur due to intrauterine, long-term hypoxia. To address this, we performed electron microscopy, Western immunoblotting, calcium imaging, and metabolomic analyses on pulmonary arteries isolated from near-term fetal lambs that had been exposed to low- or high-altitude (3,801 m) hypoxia for the latter 110+ days of gestation. Our results demonstrate that the sarcoplasmic reticulum was swollen with high luminal width and distances to the plasma membrane in the hypoxic group. Hypoxic animals were presented with higher endoplasmic reticulum stress and suppressed calcium storage. Metabolically, hypoxia was associated with lower levels of multiple omega-3 polyunsaturated fatty acids and derived lipid mediators (e.g., eicosapentaenoic acid, docosahexaenoic acid, α-linolenic acid, 5-hydroxyeicosapentaenoic acid (5-HEPE), 12-HEPE, 15-HEPE, prostaglandin E3, and 19(20)-epoxy docosapentaenoic acid) and higher levels of some omega-6 metabolites (P < 0.02) including 15-keto prostaglandin E2 and linoleoylglycerol. Collectively, the results reveal broad evidence for long-term hypoxia-induced metabolic reprogramming and phenotypic transformations in the pulmonary arteries of fetal sheep, conditions that likely contribute to the development of persistent pulmonary hypertension.
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Affiliation(s)
- Eric Leslie
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, New Mexico
| | - Vanessa Lopez
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Nana A O Anti
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Rafael Alvarez
- Center for Health Disparities and Molecular Mechanisms, Loma Linda University School of Medicine, Loma Linda, California
| | - Isaac Kafeero
- Center for Health Disparities and Molecular Mechanisms, Loma Linda University School of Medicine, Loma Linda, California
| | - Donald G Welsh
- Robarts Research Institute, Western University, London, Ontario, Canada
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Shawn Kaushal
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Catherine M Johnson
- Department of Food Science and Nutrition, California Polytechnic State University, San Luis Obispo, California
| | - Remy Bosviel
- NIH West Coast Metabolomics Center, Genome Center, University of California, Davis, California
| | - Ivana Blaženović
- NIH West Coast Metabolomics Center, Genome Center, University of California, Davis, California
| | - Rui Song
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - Alex Brito
- Laboratory of Pharmacokinetics and Metabolomic Analysis, Institute of Translational Medicine and Biotechnology, I.M. Sechenov First Moscow State Medical University, Moscow, Russia.,World-Class Research Center "Digital biodesign and personalized healthcare," I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Michael R La Frano
- Department of Food Science and Nutrition, California Polytechnic State University, San Luis Obispo, California.,Center for Health Research, California Polytechnic State University, San Luis Obispo, California.,Cal Poly Metabolomics Service Center, California Polytechnic State University, San Luis Obispo, California
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
| | - John W Newman
- NIH West Coast Metabolomics Center, Genome Center, University of California, Davis, California.,Department of Nutrition, University of California, Davis, California.,USDA-ARS Western Human Nutrition Research Center, Davis, California
| | - Oliver Fiehn
- NIH West Coast Metabolomics Center, Genome Center, University of California, Davis, California.,West Coast Metabolomics Center, University of California, Davis, California
| | - Sean M Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California.,Advanced Imaging and Microscopy Core, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California
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2
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Ben-Shachar D. Mitochondrial multifaceted dysfunction in schizophrenia; complex I as a possible pathological target. Schizophr Res 2017; 187:3-10. [PMID: 27802911 DOI: 10.1016/j.schres.2016.10.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 10/10/2016] [Accepted: 10/14/2016] [Indexed: 01/09/2023]
Abstract
Mitochondria are key players in various essential cellular processes beyond being the main energy supplier of the cell. Accordingly, they are involved in neuronal synaptic transmission, neuronal growth and sprouting and consequently neuronal plasticity and connectivity. In addition, mitochondria participate in the modulation of gene transcription and inflammation as well in physiological responses in health and disease. Schizophrenia is currently regarded as a neurodevelopmental disorder associated with impaired immune system, aberrant neuronal differentiation and abnormalities in various neurotransmitter systems mainly the dopaminergic, glutaminergic and GABAergic. Ample evidence has been accumulated over the last decade indicating a multifaceted dysfunction of mitochondria in schizophrenia. Indeed, mitochondrial deficit can be of relevance for the majority of the pathologies observed in this disease. In the present article, we overview specific deficits of the mitochondria in schizophrenia, with a focus on the first complex (complex I) of the mitochondrial electron transport chain (ETC). We argue that complex I, being a major factor in the regulation of mitochondrial ETC, is a possible key modulator of various functions of the mitochondria. We review biochemical, molecular, cellular and functional evidence for mitochondrial impairments and their possible convergence to impact in-vitro neuronal differentiation efficiency in schizophrenia. Mitochondrial function in schizophrenia may advance our knowledge of the disease pathophysiology and open the road for new treatment targets for the benefit of the patients.
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Affiliation(s)
- Dorit Ben-Shachar
- Laboratory of Psychobiology, Department of Psychiatry, Rambam Health Care Campus, B. Rappaport Faculty of Medicine, Rappaport Family Institute for Research in the Medical Sciences, Technion-IIT, Haifa, Israel.
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3
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Jarkovska D, Bludovska M, Mistrova E, Krizkova V, Kotyzova D, Kubikova T, Slavikova J, Erek SN, Djordjevic A, Chottova Dvorakova M. Expression of classical mediators in hearts of rats with hepatic dysfunction. Can J Physiol Pharmacol 2017; 95:1351-1359. [PMID: 28746816 DOI: 10.1139/cjpp-2017-0060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Liver cirrhosis is associated with impairment of cardiovascular function including alterations of the heart innervation, humoral and nervous dysregulation, changes in systemic circulation and electrophysiological abnormalities. Choline acetyltransferase (ChAT), enzyme forming acetylcholine, tyrosine hydroxylase (TH), and dopamine-β-hydroxylase (DBH), enzymes participating in noradrenaline synthesis, are responsible for the production of classical neurotransmitters, and atrial natriuretic peptide (ANP) is produced by cardiomyocytes. The aim of this study was to evaluate the influence of experimentally induced hepatic dysfunction on the expression of proANP, ChAT, TH, and DBH in the heart. Hepatic dysfunction was induced by application of thioacetamide (TAA) or by ligation of bile duct. Biochemical parameters of hepatic injury and levels of peroxidation in the liver and heart were measured. Liver enzymes measured in the plasma were significantly elevated. Cardiac level of peroxidation was increased in operated but not TAA group animals. In the left atrium of operated rats, the expression of TH and DBH was lower, while expression of ChAT remained unchanged. In TAA group, no significant differences in the expression of the genes compared to controls were observed. Liver injury induced by ligation leads to an imbalance in the intracardiac innervation, which might impair nervous control of the heart.
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Affiliation(s)
- Dagmar Jarkovska
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic.,b Department of Physiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Monika Bludovska
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic.,c Department of Pharmacology and Toxicology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Eliska Mistrova
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic.,b Department of Physiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Vera Krizkova
- d Department of Histology and Embryology, Faculty of Medicine in Pilsen, Charles University, Lidicka 1, Pilsen 323 00, Czech Republic
| | - Dana Kotyzova
- c Department of Pharmacology and Toxicology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Tereza Kubikova
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic.,d Department of Histology and Embryology, Faculty of Medicine in Pilsen, Charles University, Lidicka 1, Pilsen 323 00, Czech Republic
| | - Jana Slavikova
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Sumeyye Nur Erek
- b Department of Physiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Aleksandar Djordjevic
- b Department of Physiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
| | - Magdalena Chottova Dvorakova
- a Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic.,b Department of Physiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 1655/76, Pilsen 323 00, Czech Republic
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4
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Muralidharan P, Cserne Szappanos H, Ingley E, Hool L. Evidence for redox sensing by a human cardiac calcium channel. Sci Rep 2016; 6:19067. [PMID: 26750869 PMCID: PMC4707475 DOI: 10.1038/srep19067] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/26/2015] [Indexed: 02/07/2023] Open
Abstract
Ion channels are critical to life and respond rapidly to stimuli to evoke physiological responses. Calcium influx into heart muscle occurs through the ion conducting α1C subunit (Cav1.2) of the L-type Ca2+ channel. Glutathionylation of Cav1.2 results in increased calcium influx and is evident in ischemic human heart. However controversy exists as to whether direct modification of Cav1.2 is responsible for altered function. We directly assessed the function of purified human Cav1.2 in proteoliposomes. Truncation of the C terminus and mutation of cysteines in the N terminal region and cytoplasmic loop III-IV linker did not alter the effects of thiol modifying agents on open probability of the channel. However mutation of cysteines in cytoplasmic loop I-II linker altered open probability and protein folding assessed by thermal shift assay. We find that C543 confers sensitivity of Cav1.2 to oxidative stress and is sufficient to modify channel function and posttranslational folding. Our data provide direct evidence for the calcium channel as a redox sensor that facilitates rapid physiological responses.
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Affiliation(s)
- Padmapriya Muralidharan
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia
| | - Henrietta Cserne Szappanos
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia
| | - Evan Ingley
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands and Centre for Medical Research, The University of Western Australia, Crawley, WA, Australia
| | - Livia Hool
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Crawley, WA, Australia.,Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
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5
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Chandra Bhatt P, Srivastava P, Pandey P, Khan W, Panda BP. Nose to brain delivery of astaxanthin-loaded solid lipid nanoparticles: fabrication, radio labeling, optimization and biological studies. RSC Adv 2016. [DOI: 10.1039/c5ra19113k] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Astaxanthin nanoformulation was found appropriate in all measures with strong antioxidant activity against H2O2induced oxidative stress in PC12 cells. Biodistribution and brain delivery was also found to be superior to conventional dosage form.
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Affiliation(s)
- Prakash Chandra Bhatt
- Microbial and Pharmaceutical Biotechnology Laboratory
- Centre for Advance Research in Pharmaceutical Sciences
- Faculty of Pharmacy
- Jamia Hamdard
- New Delhi 110062
| | - Pranay Srivastava
- Developmental Toxicology Division
- Indian Institute of Toxicology Research Mahatma Gandhi Marg
- Lucknow
- India
| | - Preeti Pandey
- Department of Pharmaceutical Sciences
- Bhimtal Campus
- Kumaon University
- Nainital 263136
- India
| | - Washim Khan
- Biochemical Kit Division
- National Institute of Biology
- Noida
- India
| | - Bibhu Prasad Panda
- Microbial and Pharmaceutical Biotechnology Laboratory
- Centre for Advance Research in Pharmaceutical Sciences
- Faculty of Pharmacy
- Jamia Hamdard
- New Delhi 110062
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6
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Abstract
SIGNIFICANCE Oxygen plays a key role in cellular metabolism and function. Oxygen delivery to cells is crucial, and a lack of oxygen such as that which occurs during myocardial infarction can be lethal. Cells should, therefore, be able to respond to changes in oxygen tension. RECENT ADVANCES Since the first studies examining the acute cellular effect of hypoxia on activation of transmitter release from glomus or type I chemoreceptor cells, it is now known that virtually all cells are able to respond to changes in oxygen tension. CRITICAL ISSUES Despite advances made in characterizing hypoxic responses, the identity of the "oxygen sensor" remains debated. Recently, more evidence has evolved as to how cardiac myocytes sense acute changes in oxygen. This review will examine the available evidence in support of acute oxygen-sensing mechanisms providing a brief historical perspective and then more detailed insights into the heart and the role of cardiac ion channels in hypoxic responses. FUTURE DIRECTIONS A further understanding of these cellular processes should result in interventions that assist in preventing the deleterious effects of acute changes in oxygen tension such as alterations in contractile function and cardiac arrhythmia.
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Affiliation(s)
- Livia C Hool
- School of Anatomy, Physiology, and Human Biology, The University of Western Australia , Crawley, Australia
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7
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Ortega-Sáenz P, Villadiego J, Pardal R, Toledo-Aral JJ, López-Barneo J. Neurotrophic Properties, Chemosensory Responses and Neurogenic Niche of the Human Carotid Body. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 860:139-52. [PMID: 26303476 DOI: 10.1007/978-3-319-18440-1_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The carotid body (CB) is a polymodal chemoreceptor that triggers the hyperventilatory response to hypoxia necessary for the maintenance of O(2) homeostasis essential for the survival of organs such as the brain or heart. Glomus cells, the sensory elements in the CB, are also sensitive to hypercapnia, acidosis and, although less generally accepted, hypoglycemia. Current knowledge on CB function is mainly based on studies performed on lower mammals, but the information on the human CB is scant. Here we describe the structure, neurotrophic properties, and cellular responses to hypoxia and hypoglycemia of CBs dissected from human cadavers. The adult CB parenchyma contains clusters of chemosensitive glomus (type I) and sustentacular (type II) cells as well as nestin-positive progenitor cells. This organ also expresses high levels of the dopaminotrophic glial cell line-derived neurotrophic factor (GDNF). GDNF production and the number of progenitor and glomus cells were preserved in the CBs of human subjects of advanced age. As reported for other mammalian species, glomus cells responded to hypoxia by external Ca(2+)-dependent increase of cytosolic [Ca(2+)] and quantal catecholamine release. Human glomus cells are also responsive to hypoglycemia and together the two stimuli, hypoxia and hypoglycemia, can potentiate each other's effects. The chemo-sensory responses of glomus cells are also preserved at an advanced age. Interestingly, a neurogenic niche similar to that recently described in rodents is also preserved in the adult human CB. These new data on the cellular and molecular physiology of the CB pave the way for future pathophysiological studies involving this organ in humans.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Avenida Manuel Siurot s/n, 41013, Seville, Spain
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8
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Developmental study of the distribution of hypoxia-induced factor-1 alpha and microtubule-associated protein 2 in children’s brainstem: Comparison between controls and cases with signs of perinatal hypoxia. Neuroscience 2014; 271:77-98. [DOI: 10.1016/j.neuroscience.2014.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/21/2014] [Accepted: 04/08/2014] [Indexed: 11/20/2022]
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9
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Ortega-Sáenz P, Pardal R, Levitsky K, Villadiego J, Muñoz-Manchado AB, Durán R, Bonilla-Henao V, Arias-Mayenco I, Sobrino V, Ordóñez A, Oliver M, Toledo-Aral JJ, López-Barneo J. Cellular properties and chemosensory responses of the human carotid body. J Physiol 2013; 591:6157-73. [PMID: 24167224 DOI: 10.1113/jphysiol.2013.263657] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The carotid body (CB) is the major peripheral arterial chemoreceptor in mammals that mediates the acute hyperventilatory response to hypoxia. The CB grows in response to sustained hypoxia and also participates in acclimatisation to chronic hypoxaemia. Knowledge of CB physiology at the cellular level has increased considerably in recent times thanks to studies performed on lower mammals, and rodents in particular. However, the functional characteristics of human CB cells remain practically unknown. Herein, we use tissue slices or enzymatically dispersed cells to determine the characteristics of human CB cells. The adult human CB parenchyma contains clusters of chemosensitive glomus (type I) and sustentacular (type II) cells as well as nestin-positive progenitor cells. This organ also expresses high levels of the dopaminotrophic glial cell line-derived neurotrophic factor (GDNF). We found that GDNF production and the number of progenitor and glomus cells were preserved in the CBs of human subjects of advanced age. Moreover, glomus cells exhibited voltage-dependent Na(+), Ca(2+) and K(+) currents that were qualitatively similar to those reported in lower mammals. These cells responded to hypoxia with an external Ca(2+)-dependent increase of cytosolic Ca(2+) and quantal catecholamine secretion, as reported for other mammalian species. Interestingly, human glomus cells are also responsive to hypoglycaemia and together these two stimuli can potentiate each other's effects. The chemosensory responses of glomus cells are also preserved at an advanced age. These new data on the cellular and molecular physiology of the CB pave the way for future pathophysiological studies involving this organ in humans.
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Affiliation(s)
- Patricia Ortega-Sáenz
- J. López-Barneo: Instituto de Biomedicina de Sevilla (IBiS), Campus Hospital Universitario Virgen del Rocío, Avenida Manuel Siurot s/n, 41013 Seville, Spain.
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10
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α-Haemoglobin regulates sympathoadrenal cell metabolism to maintain a catecholaminergic phenotype. Biochem J 2012; 441:843-50. [PMID: 22060312 DOI: 10.1042/bj20111640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Discovery of haemoglobin A expression outside of the erythroid cell lineage suggests that oxygen transport is the main, but not the unique, function of adult haemoglobin chains in mammals. The contribution of haemoglobin A to antioxidant defences has been proposed in the territories where it is expressed. Catecholaminergic cells rely on an active oxidative metabolism to accomplish their biological function, but are exposed to strong oxidative stress due to metabolism of catecholaminergic transmitters. We show in the present study that peripheral catecholaminegic cells express the α- and not the β-haemoglobin A chains, and that α-haemoglobin expression could modulate the antioxidant capabilities of these cells. We also show that α-haemoglobin overexpression in PC12 cells leads to a selective increase of tyrosine hydroxylase synthesis and activity. This is achieved by means of a reorganization of antioxidant defences, decreasing cytoplasmic glutathione peroxidase and superoxide dismutase, and increasing mitochondrial peroxidase. Moreover, α-haemoglobin induces a decrease in lipogenesis and increase in lipid degradation, situations that help save NAD(P)H and favour supply of acetyl-CoA to the tricarboxylic acid cycle and production of reducing equivalents in the cell. All of these results point to a role for α-haemoglobin as a regulator of catecholaminergic cell metabolism required for phenotype acquisition and maintenance.
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11
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Stowe DF, Camara AKS. Mitochondrial reactive oxygen species production in excitable cells: modulators of mitochondrial and cell function. Antioxid Redox Signal 2009; 11:1373-414. [PMID: 19187004 PMCID: PMC2842133 DOI: 10.1089/ars.2008.2331] [Citation(s) in RCA: 341] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 12/14/2022]
Abstract
The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O(2)(*-)) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H(2)O(2) inside and outside the mitochondrial matrix by superoxide dismutases. H(2)O(2) is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O(2)(*-). Cell ischemia, hypoxia, or toxins can result in excess O(2)(*-) production when the redox state is altered and the ROS scavenger systems are overwhelmed. Too much H(2)O(2) can combine with Fe(2+) complexes to form reactive ferryl species (e.g., Fe(IV) = O(*)). In the presence of nitric oxide (NO(*)), O(2)(*-) forms the reactant peroxynitrite (ONOO(-)), and ONOOH-induced nitrosylation of proteins, DNA, and lipids can modify their structure and function. An initial increase in ROS can cause an even greater increase in ROS and allow excess mitochondrial Ca(2+) entry, both of which are factors that induce cell apoptosis and necrosis. Approaches to reduce excess O(2)(*-) emission include selectively boosting the antioxidant capacity, uncoupling of oxidative phosphorylation to reduce generation of O(2)(*-) by inducing proton leak, and reversibly inhibiting electron transport. Mitochondrial cation channels and exchangers function to maintain matrix homeostasis and likely play a role in modulating mitochondrial function, in part by regulating O(2)(*-) generation. Cell-signaling pathways induced physiologically by ROS include effects on thiol groups and disulfide linkages to modify posttranslationally protein structure to activate/inactivate specific kinase/phosphatase pathways. Hypoxia-inducible factors that stimulate a cascade of gene transcription may be mediated physiologically by ROS. Our knowledge of the role played by ROS and their scavenging systems in modulation of cell function and cell death has grown exponentially over the past few years, but we are still limited in how to apply this knowledge to develop its full therapeutic potential.
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Affiliation(s)
- David F Stowe
- Anesthesiology Research Laboratories, Department of Anesthesiology, The Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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12
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Estradiol protects PC12 cells against CoCl2-induced apoptosis. Brain Res Bull 2008; 76:579-85. [DOI: 10.1016/j.brainresbull.2008.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 03/12/2008] [Accepted: 04/11/2008] [Indexed: 11/22/2022]
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13
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Wan KF, Chan SL, Sukumaran SK, Lee MC, Yu VC. Chelerythrine induces apoptosis through a Bax/Bak-independent mitochondrial mechanism. J Biol Chem 2008; 283:8423-33. [PMID: 18230621 PMCID: PMC2417179 DOI: 10.1074/jbc.m707687200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 12/17/2007] [Indexed: 12/16/2022] Open
Abstract
Although murine embryonic fibroblasts (MEFs) with Bax or Bak deleted displayed no defect in apoptosis signaling, MEFs with Bax and Bak double knock-out (DKO) showed dramatic resistance to diverse apoptotic stimuli, suggesting that Bax and Bak are redundant but essential regulators for apoptosis signaling. Chelerythrine has recently been identified as a Bcl-xL inhibitor that is capable of triggering apoptosis via direct action on mitochondria. Here we report that in contrast to classic apoptotic stimuli, chelerythrine is fully competent in inducing apoptosis in the DKO MEFs. Wild-type and DKO MEFs are equally sensitive to chelerythrine-induced morphological and biochemical changes associated with apoptosis phenotype. Interestingly, chelerythrine-mediated release of cytochrome c is rapid and precedes Bax translocation and integration. Although the BH3 peptide of Bim is totally inactive in releasing cytochrome c from isolated mitochondria of DKO MEFs, chelerythrine maintains its potency and efficacy in inducing direct release of cytochrome c from these mitochondria. Furthermore, chelerythrine-mediated mitochondrial swelling and loss in mitochondrial membrane potential (DeltaPsi(m)) are inhibited by cyclosporine A, suggesting that mitochondrial permeability transition pore is involved in chelerythrine-induced apoptosis. Although certain apoptotic stimuli have been shown to elicit cytotoxic effect in the DKO MEFs through alternate death mechanisms, chelerythrine does not appear to engage necrotic or autophagic death mechanism to trigger cell death in the DKO MEFs. These results, thus, argue for the existence of an alternative Bax/Bak-independent apoptotic mechanism that involves cyclosporine A-sensitive mitochondrial membrane permeability.
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Affiliation(s)
- Kah Fei Wan
- Institute of Molecular and Cell Biology, ASTAR (Agency for Science, Technology, and Research), 61 Biopolis Dr. (Proteos), Singapore
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14
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The von Hippel-Lindau tumor suppressor protein and Egl-9-Type proline hydroxylases regulate the large subunit of RNA polymerase II in response to oxidative stress. Mol Cell Biol 2008; 28:2701-17. [PMID: 18285459 DOI: 10.1128/mcb.01231-07] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Human renal clear cell carcinoma (RCC) is frequently associated with loss of the von Hippel-Lindau (VHL) tumor suppressor (pVHL), which inhibits ubiquitylation and degradation of the alpha subunits of hypoxia-inducible transcription factor. pVHL also ubiquitylates the large subunit of RNA polymerase II, Rpb1, phosphorylated on serine 5 (Ser5) within the C-terminal domain (CTD). A hydroxylated proline 1465 within an LXXLAP motif located N-terminal to the CTD allows the interaction of Rpb1 with pVHL. Here we report that in RCC cells, pVHL regulates expression of Rpb1 and is necessary for low-grade oxidative-stress-induced recruitment of Rpb1 to the DNA-engaged fraction and for its P1465 hydroxylation, phosphorylation, and nondegradative ubiquitylation. Egln-9-type prolyl hydroxylases, PHD1 and PHD2, coimmunoprecipitated with Rpb1 in the chromatin fraction of VHL(+) RCC cells in response to oxidative stress, and PHD1 was necessary for P1465 hydroxylation while PHD2 had an inhibitory effect. P1465 hydroxylation was required for oxidative-stress-induced Ser5 phosphorylation of Rpb1. Importantly, overexpression of wild-type Rpb1 stimulated formation of kidney tumors by VHL(+) cells, and this effect was abolished by P1465A mutation of Rpb1. These data indicate that through this novel pathway involving P1465 hydroxylation and Ser5 phosphorylation of Rbp1, pVHL may regulate tumor growth.
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15
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Basini G, Simona B, Santini SE, Grasselli F. Reactive oxygen species and anti-oxidant defences in swine follicular fluids. Reprod Fertil Dev 2008; 20:269-74. [DOI: 10.1071/rd07147] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 11/19/2007] [Indexed: 11/23/2022] Open
Abstract
A growing body of evidence indicates that the pro-oxidant/anti-oxidant balance inside the ovarian follicle plays an important role in folliculogenesis. Therefore, the aim of the present study was to assess the redox status of follicular fluids collected from different-sized swine follicles. We quantified the most important reactive oxygen species (ROS), namely superoxide anion (O2–), hydrogen peroxide and hydroperoxides (ROOH); in addition, we examined the activity of the detoxifying enzymes superoxide dismutase, catalase (CAT) and glutathione peroxidase and the total non-enzymatic antioxidant capacity as determined by the ferric-reducing anti-oxidant power assay. Our data demonstrate that oxidative stress does not affect follicle growth because O2– levels do not change during follicle development, whereas concentrations of H2O2 and ROOH are reduced (P < 0.05). Surprisingly, all non-enzymatic and enzymatic scavengers examined in the present study, except for CAT, demonstrated reduced activity during follicle development (P < 0.05). Taken together, these results suggest that other factors could be involved in ROS detoxification during follicle development.
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16
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Ortega-Sáenz P, Pascual A, Piruat JI, López-Barneo J. Mechanisms of acute oxygen sensing by the carotid body: Lessons from genetically modified animals. Respir Physiol Neurobiol 2007; 157:140-7. [PMID: 17360248 DOI: 10.1016/j.resp.2007.02.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2006] [Revised: 02/06/2007] [Accepted: 02/09/2007] [Indexed: 01/23/2023]
Abstract
We have studied carotid body (CB) glomus cell sensitivity to changes in O(2) tension in three different genetically engineered animals models using thin CB slices and monitoring the secretory response to hypoxia by amperometry. Glomus cells from partially HIF-1alpha deficient mice exhibited a normal sensitivity to hypoxia. Animals with complete deletion of the small membrane anchoring subunit of succinate dehydrogenase (SDHD) died during embryonic life but heterozygous SDHD +/- mice showed a normal CB response to low O(2) tension. SDHD +/- mice had, however, a clear CB phenotype characterized by a decrease of K(+) current amplitude, an increase of basal catecholamine release from glomus cells, and a slight organ growth. The lack of hemeoxygenase-2 (HO-2), a ubiquitous powerful antioxidant enzyme, produces a notable CB phenotype, characterized by hypertrophy and alteration in the level of CB expression of some stress-dependent genes (including down-regulation of the maxi-K(+) channel alpha-subunit). Nevertheless, in HO-2 deficient mice the exquisite intrinsic O(2) responsiveness of CB glomus cells remains unaltered. Therefore, HO-2 is not absolutely necessary for acute CB O(2) sensing. Although the nature of the CB acute O(2) sensor(s) is yet unknown, studies similar to those summarized here serve to test the existing hypothesis and help to distinguish between those that need to be explored further and those that definitively lack experimental support.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Laboratorio de Investigaciones Biomédicas, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, Sevilla, Spain
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17
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Abstract
Calcium plays an integral role in cellular function. It is a well-recognized second messenger necessary for signaling cellular responses, but in excessive amounts can be deleterious to function, causing cell death. The main route by which calcium enters the cytoplasm is either from the extracellular compartment or internal addistores via calcium channels. There is good evidence that calcium channels can respond to pharmacological compounds that reduce or oxidize thiol groups on the channel protein. In addition, reactive oxygen species such as hydrogen peroxide and superoxide that can mediate oxidative pathology also mediate changes in channel function via alterations of thiol groups. This review looks at the structure and function of calcium channels, the evidence that changes in cellular redox state mediate changes in channel function, and the role of redox modification of channels in disease processes. Understanding how redox modification of the channel protein alters channel structure and function is providing leads for the design of therapeutic interventions that target oxidative stress responses.
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Affiliation(s)
- Livia C Hool
- Discipline of Physiology, School of Biomedical, Biomolecular, and Chemical Sciences, The University of Western Australia, Crawley, Western Australia.
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18
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Jung JY, Mo HC, Yang KH, Jeong YJ, Yoo HG, Choi NK, Oh WM, Oh HK, Kim SH, Lee JH, Kim HJ, Kim WJ. Inhibition by epigallocatechin gallate of CoCl2-induced apoptosis in rat PC12 cells. Life Sci 2007; 80:1355-63. [PMID: 17240404 DOI: 10.1016/j.lfs.2006.11.033] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 08/25/2006] [Accepted: 11/22/2006] [Indexed: 12/13/2022]
Abstract
Epigallocatechin-3-gallate (EGCG) is a major constituent of green tea polyphenols. This study was aimed to investigate the possible mechanisms of EGCG-mediated inhibition against apoptosis in rat pheochromocytoma PC12 cells by exposure to CoCl(2). Exposure to CoCl(2) caused the generation of ROS and induced cell death with appearance of apoptotic morphology and DNA fragmentation. However, EGCG rescued the loss of viability in the cells exposed to CoCl(2) and led the reduction of DNA fragmentation and sub-G(1) fraction of cell cycle. Also, EGCG attenuated the CoCl(2)-induced disruption of mitochondrial membrane potential (DeltaPsim), release of cytochrome c from the mitochondria to cytosol and abolished the CoCl(2)-stimulated activities of the caspase cascades, caspase-9 and caspase-3. In addition, EGCG ameliorated the increase in the Bax to Bcl-2 ratio, a marker of apoptosis proceeding, induced by CoCl(2) treatment. Taken together, the present results suggest that EGCG inhibit the CoCl(2)-induced apoptosis of PC12 cells through the mitochondria-mediated apoptosis pathway involved in modulating the Bcl-2 family.
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Affiliation(s)
- Ji-Yeon Jung
- Dental Science Research Institute, School of Dentistry, 2nd Stage of Brain Korea 21 for School of Dentistry, Chonnam National University, Gwang Ju 500-757, South Korea
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19
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Nguyen MVC, Pouvreau S, El Hajjaji FZ, Denavit-Saubie M, Pequignot JM. Desferrioxamine enhances hypoxic ventilatory response and induces tyrosine hydroxylase gene expression in the rat brainstem in vivo. J Neurosci Res 2007; 85:1119-25. [PMID: 17304568 DOI: 10.1002/jnr.21202] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The iron chelator desferrioxamine (DFO) induces accumulation of the hypoxia-inducible factor (HIF-1), a transcription factor that up-regulates genes involved in adaptative responses to hypoxia. This property makes DFO a potential neuroprotector against hypoxic stress. We investigated in rats the effects of DFO on the ventilatory response to mild hypoxic tests and the expression of tyrosine hydroxylase (TH), a target gene of HIF-1. Two protocols were used, the first with repeated injections of 50 mg/kg DFO every 2 days during a 2-week period. This was aimed at define the time course of the ventilatory responses to a hypoxic test. In the second protocol, rats were given a single injection of 300 mg/kg DFO. Every day over 4 days, the hypoxic ventilatory response was recorded before the animal was sacrificed, and Western blot analysis of TH in the dorsal brainstem cardiorespiratory area was performed. DFO produced a delayed increase in the hypoxic ventilatory response, which appeared in the same time window as TH up-regulation (2-3 days after the bolus injection of DFO). This delay suggests a genic effect of the drug that improves the ventilatory response to hypoxia.
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Affiliation(s)
- M V C Nguyen
- CNRS UPR 2216, Neurobiologie Génétique et Intégrative, Institut Alfred Fessard, Gif/Yvette, France.
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20
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Jung JY, Han CR, Jeong YJ, Kim HJ, Lim HS, Lee KH, Park HO, Oh WM, Kim SH, Kim WJ. Epigallocatechin gallate inhibits nitric oxide-induced apoptosis in rat PC12 cells. Neurosci Lett 2007; 411:222-7. [PMID: 17116366 DOI: 10.1016/j.neulet.2006.09.089] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2006] [Revised: 09/16/2006] [Accepted: 09/18/2006] [Indexed: 11/25/2022]
Abstract
Nitric oxide (NO) is associated with many pathophysiology of the central nervous system including brain ischemia, neurodegeneration and inflammation. Epigallocatechin gallate (EGCG) is a major compound of green tea polyphenol that has shown the protective activity against neuronal diseases. This study examined the effect of EGCG on NO-induced cell death in PC12 cells. The administration of sodium nitroprusside (SNP), a NO donor, decreased the cell viability and induced apoptosis showing characterization such as cell shrinkage and chromatin condensation as well as subG1 fraction of cell cycles. EGCG inhibited the cytotoxicity and apoptotic morphogenic changes induced by SNP. EGCG attenuated the production of reactive oxygen species (ROS) by SNP, and ameliorated the SNP-induced Bax to Bcl-2 expression ratio leading to apoptosis. In addition, EGCG prevented the release of cytochrome c from the mitochondria into the cytosol as well as the upregulation of the voltage-dependent anion channel (VDAC), a cytochrome c releasing channel, in the mitochondria of SNP-treated cells. EGCG abrogated the activation of caspase-9, caspase-8 and caspase-3 induced by SNP. These results demonstrate that EGCG has a protective effect against SNP-induced apoptosis in PC12 cells by scavenging ROS and modulating the signal molecules associated with cytochrome c, caspases, VDAC and the Bcl-2 family. These findings suggest that EGCG might be a natural neuroprotective substance.
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Affiliation(s)
- Ji Yeon Jung
- Dental Science Research Institute, School of Dentistry, 2nd Stage of Brain Korea 21 for School of Dentistry, Chonnam National University, Gwangju 500-757, South Korea
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21
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Ortega-Sáenz P, Pascual A, Gómez-Díaz R, López-Barneo J. Acute oxygen sensing in heme oxygenase-2 null mice. ACTA ACUST UNITED AC 2006; 128:405-11. [PMID: 16966473 PMCID: PMC2151578 DOI: 10.1085/jgp.200609591] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Hemeoxygenase-2 (HO-2) is an antioxidant enzyme that can modulate recombinant maxi-K(+) channels and has been proposed to be the acute O(2) sensor in the carotid body (CB). We have tested the physiological contribution of this enzyme to O(2) sensing using HO-2 null mice. HO-2 deficiency leads to a CB phenotype characterized by organ growth and alteration in the expression of stress-dependent genes, including the maxi-K(+) channel alpha-subunit. However, sensitivity to hypoxia of CB is remarkably similar in HO-2 null animals and their control littermates. Moreover, the response to hypoxia in mouse and rat CB cells was maintained after blockade of maxi-K(+) channels with iberiotoxin. Hypoxia responsiveness of the adrenal medulla (AM) (another acutely responding O(2)-sensitive organ) was also unaltered by HO-2 deficiency. Our data suggest that redox disregulation resulting from HO-2 deficiency affects maxi-K(+) channel gene expression but it does not alter the intrinsic O(2) sensitivity of CB or AM cells. Therefore, HO-2 is not a universally used acute O(2) sensor.
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Affiliation(s)
- Patricia Ortega-Sáenz
- Laboratorio de Investigaciones Biomédicas, Hospital Universitario Virgen del Rocío, Universidad de Sevilla, Sevilla 41013, Spain
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22
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Kietzmann T, Görlach A. Reactive oxygen species in the control of hypoxia-inducible factor-mediated gene expression. Semin Cell Dev Biol 2006; 16:474-86. [PMID: 15905109 DOI: 10.1016/j.semcdb.2005.03.010] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) have long been considered as cytotoxic. However, recent evidence indicates a prominent role of ROS as signaling molecules in the response to hormones, growth and coagulation factors, cytokines and other factors as well as to changes in oxygen tension. The hypoxia-inducible transcription factors (HIFs) are key players in the cellular response to changes in oxygen tension. Recently, HIFs have also been shown to respond to the above-mentioned non-hypoxic stimuli. In this article, the role of ROS in the regulation of HIF-1 under hypoxic and non-hypoxic conditions is summarized.
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Affiliation(s)
- Thomas Kietzmann
- Faculty of Chemistry, Department of Biochemistry, Erwin-Schrödinger-Strasse, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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23
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Hool LC. Reactive oxygen species in cardiac signalling: from mitochondria to plasma membrane ion channels. Clin Exp Pharmacol Physiol 2006; 33:146-51. [PMID: 16445714 DOI: 10.1111/j.1440-1681.2006.04341.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Reactive oxygen species (ROS) have been considered deleterious to cell function and there is good evidence to suggest that they play a role in the pathophysiology of a number of cardiac disease states. However, ROS are also now being recognized as important regulators of cell function by altering the redox state of proteins. 2. Possible sources of production of ROS in cardiac myocytes are the mitochondria and nicotinamide adenine dinucleotide phosphate-oxidase. The generation of ROS and anti-oxidant defence mechanisms in the heart are discussed. 3. The evidence for a role for ROS in the development of disease states, such as atherosclerosis, ischaemia, cardiac hypertrophy and hypertension, is presented. It is now recognized that cardiac ion channel function is regulated by ROS. Implications with respect to cardiac arrhythmia are discussed.
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Affiliation(s)
- Livia C Hool
- Physiology, The University of Western Australia, Crawley and The Western Australian Institute for Medical Research, Perth, Western Australia, Australia.
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24
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Yamamoto Y, König P, Henrich M, Dedio J, Kummer W. Hypoxia induces production of nitric oxide and reactive oxygen species in glomus cells of rat carotid body. Cell Tissue Res 2006; 325:3-11. [PMID: 16534602 DOI: 10.1007/s00441-006-0178-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Accepted: 01/24/2006] [Indexed: 10/24/2022]
Abstract
The carotid body is an arterial chemoreceptor organ that senses arterial pO(2) and pH. Previous studies have indicated that both reactive oxygen species (ROS) and nitric oxide (NO) are important potential mediators that may be involved in the response of the carotid body to hypoxia. However, whether their production by the chemosensitive elements of the carotid body is indeed oxygen-dependent is currently unclear. Thus, we have investigated their production under normoxic (20% O(2)) and hypoxic (1% O(2)) conditions in slice preparations of the rat carotid body by using fluorescent indicators and confocal microscopy. NO-synthesizing enzymes were identified by immunohistochemistry and histochemistry, and the subcellular localization of the NO-sensitive indicator diaminofluorescein was determined by a photoconversion technique and electron microscopy. Glomus cells of the carotid body responded to hypoxia by increases in both ROS and NO production. The hypoxia-induced increase in NO generation required (to a large extent, but not completely) extracellular calcium. Glomus cells were immunoreactive to endothelial NO synthase but not to the neuronal or inducible isoforms. Ultrastructurally, the NO-sensitive indicator was observed in mitochondrial membranes after exposure to hypoxia. The data show that glomus cells respond to exposure to hypoxia by the enhanced production of both ROS and NO. NO production by glomus cells is probably mediated by endothelial NO synthase, which is activated by calcium influx. The presence of NO indicator in mitochondria suggests the hypoxic regulation of mitochondrial function via NO in glomus cells.
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Affiliation(s)
- Yoshio Yamamoto
- Institute of Anatomy and Cell Biology, Justus Liebig University, Aulweg 123, 35385 Giessen, Germany
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25
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Zakrzewska A, Schnell PO, Striet JB, Hui A, Robbins JR, Petrovic M, Conforti L, Gozal D, Wathelet MG, Czyzyk-Krzeska MF. Hypoxia-activated metabolic pathway stimulates phosphorylation of p300 and CBP in oxygen-sensitive cells. J Neurochem 2005; 94:1288-96. [PMID: 16000154 PMCID: PMC1411962 DOI: 10.1111/j.1471-4159.2005.03293.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transcription co-activators and histone acetyltransferases, p300 and cyclic AMP responsive element-binding protein-binding protein (CBP), participate in hypoxic activation of hypoxia-inducible genes. Here, we show that exposure of PC12 and cells to 1-10% oxygen results in hyperphosphorylation of p300/CBP. This response is fast, long lasting and specific for hypoxia, but not for hypoxia-mimicking agents such as desferioxamine or Co2+ ions. It is also cell-type specific and occurs in pheochromocytoma PC12 cells and the carotid body of rats but not in hepatoblastoma cells. The p300 hyperphosphorylation specifically depends on the release of intracellular calcium from inositol 1,4,5-triphosphate (IP3)-sensitive stores. However, it is not inhibited by pharmacological inhibitors of any of the kinases traditionally known to be directly or indirectly calcium regulated. On the other hand, p300 hyperphosphorylation is inhibited by several different inhibitors of the glucose metabolic pathway from generation of NADH by glyceraldehyde 3-phosphate dehydrogenase, through the transfer of NADH through the glycerol phosphate shuttle to ubiquinone and complex III of the mitochondrial respiratory chain. Inhibition of IP3-sensitive calcium stores decreases generation of ATP, and this inhibition is significantly stronger in hypoxia than in normoxia. We propose that the NADH glycerol phosphate shuttle participates in generating a pool of ATP that serves either as a co-factor or a modulator of the kinases involved in the phosphorylation of p300/CBP during hypoxia.
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Affiliation(s)
| | | | - Justin B. Striet
- Departments of Genome Science
- Molecular and Cellular Physiology and
| | - Anna Hui
- Departments of Genome Science
- Molecular and Cellular Physiology and
| | - Jennifer R. Robbins
- Medicine, Division of Nephrology and Hypertension, University of Cincinnati, Ohio, USA
| | - Milan Petrovic
- Medicine, Division of Nephrology and Hypertension, University of Cincinnati, Ohio, USA
| | - Laura Conforti
- Molecular and Cellular Physiology and
- Medicine, Division of Nephrology and Hypertension, University of Cincinnati, Ohio, USA
| | - David Gozal
- Departments of Pediatrics, Pharmacology, and Toxicology, Kosair Children’s Hospital Research Institute, University of Louisville, Kentucky, USA
| | | | - Maria F. Czyzyk-Krzeska
- Departments of Genome Science
- Molecular and Cellular Physiology and
- Address correspondence and reprint requests to Maria F. Czyzyk-Krzeska, Department of Genome Science, University of Cincinnati, College of Medicine, 2180 E Galbraith Road., Cincinnati, OH 45267–0505, USA. E-mail:
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26
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Munns SE, Lui JKC, Arthur PG. Mitochondrial hydrogen peroxide production alters oxygen consumption in an oxygen-concentration-dependent manner. Free Radic Biol Med 2005; 38:1594-603. [PMID: 15917188 DOI: 10.1016/j.freeradbiomed.2005.02.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Revised: 02/02/2005] [Accepted: 02/22/2005] [Indexed: 10/25/2022]
Abstract
Metabolic responses of mammalian cells toward declining oxygen concentration are generally thought to occur when oxygen limits mitochondrial ATP production. However, at oxygen concentrations markedly above those limiting to mitochondria, several mammalian cell types display reduced rates of oxygen consumption without energy stress or compensatory increases in glycolytic ATP production. We used mammalian Jurkat T cells as a model system to identify mechanisms responsible for these changes in metabolic rate. Oxygen consumption was 31% greater at high oxygen (150-200 microM) compared to low oxygen (5-10 microM). Hydrogen peroxide was implicated in the response as catalase prevented the increase in oxygen consumption normally associated with high oxygen. Cell-derived hydrogen peroxide, predominately from the mitochondria, was elevated with high oxygen. Oxygen consumption related to intracellular calcium turnover was shown, through EDTA chelation and dantrolene antagonism of the ryanodine receptor, to account for 70% of the response. Oligomycin inhibition of oxygen consumption indicated that mitochondrial proton leak was also sensitive to changes in oxygen concentration. Our results point toward a mechanism in which changes in oxygen concentration influence the rate of hydrogen peroxide production by mitochondria, which, in turn, alters cellular ATP use associated with intracellular calcium turnover and energy wastage through mitochondrial proton leak.
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Affiliation(s)
- Shane E Munns
- School of Biomedical & Chemical Sciences, M310, University of Western Australia, Crawley, WA 6009, Australia
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27
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Basini G, Bianco F, Grasselli F. Epigallocatechin-3-gallate from green tea negatively affects swine granulosa cell function. Domest Anim Endocrinol 2005; 28:243-56. [PMID: 15760666 DOI: 10.1016/j.domaniend.2004.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 10/01/2004] [Indexed: 11/29/2022]
Abstract
The use of herbs as additives in livestock nutrition as an alternative to antibiotics is becoming a new goal in animal production. It is known that green tea exerts antimicrobial activity owing to specific flavonoid compounds named catechins, primarily represented by epigallocatechin-3-gallate (EGCG). Remarkably, despite many potential benefits of green tea and EGCG consumption, it is also important to get an insight on the possible reproductive-related consequences of feeding supplementation. To this purpose, granulosa cells were harvested from follicles > 5mm and treated with 5 and 50 microg/ml of EGCG in order to evaluate the effects on the main parameters of granulosa cell function: steroidogenesis, by measuring progesterone and estradiol-17beta production, and proliferation, one of the major feature of ovarian follicular growth. Moreover, as the genesis of new vessels has been demonstrated to be fundamental for follicle development, we evaluated the effect of EGCG on the production of the main angiogenetic factor, VEGF, by swine granulosa cells. Finally, since reactive oxygen species (ROS) might be involved in the control of female reproductive activity, we studied the effect of EGCG on superoxide anion (O2-) and hydrogen peroxide (H2O2) production by swine granulosa cells and on the activity of the scavenging enzyme superoxide dismutase (SOD). EGCG significantly (p < 0.05) inhibited proliferation, steroidogenesis, VEGF and O2- production by swine granulosa cells; on the contrary, H2O2 levels and SOD activity were stimulated (p < 0.05) by the catechin. Therefore, since our data demonstrate that EGCG has a negative effect on reproductive performances in swine, feeding supplementation should be carefully considered.
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Affiliation(s)
- Giuseppina Basini
- Dipartimento di Produzioni Animali, Biotecnologie Veterinarie, Qualità e Sicurezza degli Alimenti, Sezione di Fisiologia Veterinaria, Università di Parma, 43100 Parma, Italy.
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28
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Hool LC. Acute hypoxia differentially regulates K+ channels. Implications with respect to cardiac arrhythmia. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:369-76. [PMID: 15726346 DOI: 10.1007/s00249-005-0462-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Revised: 01/03/2005] [Accepted: 01/14/2005] [Indexed: 11/26/2022]
Abstract
The first ion channels demonstrated to be sensitive to changes in oxygen tension were K(+) channels in glomus cells of the carotid body. Since then a number of hypoxia-sensitive ion channels have been identified. However, not all K(+) channels respond to hypoxia alike. This has raised some debate about how cells detect changes in oxygen tension. Because ion channels respond rapidly to hypoxia it has been proposed that the channel is itself an oxygen sensor. However, channel function can also be modified by thiol reducing and oxidizing agents, implicating reactive oxygen species as signals in hypoxic events. Cardiac ion channels can also be modified by hypoxia and redox agents. The rapid and slow components of the delayed rectifier K(+) channel are differentially regulated by hypoxia and beta-adrenergic receptor stimulation. Mutations in the genes that encode the subunits for the channel are associated with Long QT syndrome and sudden cardiac death. The implications with respect to effects of hypoxia on the channel and triggering of cardiac arrhythmia will be discussed.
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Affiliation(s)
- Livia C Hool
- School of Biomedical and Chemical Sciences Australia and The Western Australian Institute of Medical Research, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
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29
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Zechel JL, Gamboa JL, Peterson AG, Puchowicz MA, Selman WR, Lust WD. Neuronal migration is transiently delayed by prenatal exposure to intermittent hypoxia. ACTA ACUST UNITED AC 2005; 74:287-99. [PMID: 16094620 DOI: 10.1002/bdrb.20051] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Neonatal neurodevelopment is influenced by a variety of external factors, although the mechanisms responsible are poorly understood. Prenatal hypoxia, from physiological or chemical sources, can have no discernible effect, or can result in a broad spectrum of abnormalities. METHODS To mimic some of the maternal effects of smoking, we developed a model that investigates the effects of intermittent hypoxia (IH), with or without concurrent nicotine in timed pregnant Sprague-Dawley rats. RESULTS We found no significant differences between litter sizes or birthweight of pups from any treatment group, but animals exposed to IH (with or without nicotine) showed long term diminished body weights. Animals subjected to IH consistently showed a transient delay in neuronal migration early in the postpartum period, which was amplified by concurrent nicotine administration. We observed increased c-Abl protein levels in animals from the IH treatment groups. Multiple proteins involved in the intricate control of neuronal migration were also altered in response to this treatment, primarily the downstream targets of c-Abl: Cdk5, p25, and the cytoskeletal elements neurofilament H and F-actin and catalase. Catalase activity and protein levels, already elevated in response to IH, were further amplified by simultaneous nicotine exposure. CONCLUSIONS This new model provides a novel system for investigating the effects of low grade IH in the developing brain and suggests that concurrent nicotine further aggravates many of the deleterious effects of IH.
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Affiliation(s)
- Jennifer L Zechel
- Department of Neurological Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4939, USA
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Tang MZ, Wang ZF, Shi YL. Involvement of cytochrome c release and caspase activation in toosendanin-induced PC12 cell apoptosis. Toxicology 2004; 201:31-8. [PMID: 15297017 DOI: 10.1016/j.tox.2004.03.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 03/26/2004] [Accepted: 03/26/2004] [Indexed: 01/09/2023]
Abstract
Our previous study showed that toosendanin, a triterpenoid derivative isolated from a Chinese traditional medicine, could induce apoptosis in PC12 cells. In this study we confirmed the apoptosis-inducing effect of toosendanin in PC12 cells with new evidences in morphology and biochemistry: the shrinkage of cytosol, the condensation and fragmentation of nuclei and the formation of DNA ladder. It was also demonstrated that toosendanin decreased the PC12 cell viability in a time- and concentration-dependent manner. To elucidate the pathway linked with the toosendanin-induced apoptosis, the cytochrome c in the cytosol and the cleavage of poly(ADP-ribose) polymerase (PARP) were examined. The obtained results showed that toosendanin caused the release of cytochrome c from mitochondria into the cytosol and then led to the activation of caspase, indicating that the cytochrome c release and caspase activation were involved in the toosendanin-induced apoptosis process. These results suggested the possibility that toosendanin could serve as a candidate for anti-cancer drug.
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Affiliation(s)
- Mian-Zhi Tang
- Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
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31
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BelAiba RS, Djordjevic T, Bonello S, Flügel D, Hess J, Kietzmann T, Görlach A. Redox-sensitive regulation of the HIF pathway under non-hypoxic conditions in pulmonary artery smooth muscle cells. Biol Chem 2004; 385:249-57. [PMID: 15134338 DOI: 10.1515/bc.2004.019] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Pulmonary hypertension and vascular remodeling processes are associated with oxidative stress, hypoxia and enhanced levels of thrombin and vascular endothelial growth factor (VEGF). The hypoxia-inducible transcription factor HIF regulates the expression of VEGF under hypoxia. The HIF pathway is also activated by thrombin or CoCl2, likely via reactive oxygen species (ROS). In this study we investigated whether the redox-modifying enzymes superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase affect HIF levels and the expression of VEGF mRNA in pulmonary artery smooth muscle cells (PASMC). Stimulation of PASMC with thrombin or CoCl2 increased ROS production and enhanced HIF-alpha protein and VEGF mRNA levels as well as HIF-dependent reporter gene activity. These responses were inhibited by vitamin C and by overexpression of GPX and catalase, whereas the opposite effects were observed in SOD-expressing cells. These findings suggest that an 'antioxidant' state with reduced levels of H2O2 limits the activation of the HIF pathway, whereas a 'prooxidant' state allowing elevated H2O2 levels promotes it. Thus, shifting the redox balance to a more reduced environment, thereby limiting VEGF expression, may be beneficial for treating remodeling processes during pulmonary hypertension.
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Affiliation(s)
- Rachida S BelAiba
- Experimentelle Kinderkardiologie, Klinik für Kinder-Kardiologie und Angeborene Herzfehler, Deutsches Herzzentrum München an der Technischen Universität München, D-80636 München, Germany
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32
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Kotamraju S, Tampo Y, Kalivendi SV, Joseph J, Chitambar CR, Kalyanaraman B. Nitric oxide mitigates peroxide-induced iron-signaling, oxidative damage, and apoptosis in endothelial cells: role of proteasomal function? Arch Biochem Biophys 2004; 423:74-80. [PMID: 14989268 DOI: 10.1016/j.abb.2003.12.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In this mini-review, oxidant-induced transferrin receptor-mediated iron-signaling and apoptosis are described in endothelial and neuronal cells exposed to a variety of oxidative stresses. The role of nitric oxide and nitration in the regulation of iron homeostasis and oxidant-induced apoptosis is described. The interrelationship between oxidative stress, iron-signaling, and nitric oxide-dependent proteasomal function provides a rational mechanism that connects both oxidative and nitrative modifications.
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Affiliation(s)
- Srigiridhar Kotamraju
- Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, USA
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33
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Basini G, Grasselli F, Bianco F, Tirelli M, Tamanini C. Effect of reduced oxygen tension on reactive oxygen species production and activity of antioxidant enzymes in swine granulosa cells. Biofactors 2004; 20:61-9. [PMID: 15322330 DOI: 10.1002/biof.5520200201] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During follicle growth swine granulosa cells are physiologically exposed to a progressive oxygen shortage. It has already been shown that hypoxia stimulates angiogenesis through an increase of VEGF production, however, despite considerable progress in the understanding of the final events induced by cellular hypoxia, the signal transduction pathway remains elusive. Recent evidence suggest a role for Reactive Oxygen Species (ROS) as hypoxia signal transducer. Granulosa cells were isolated from pig follicles (> 5 mm) and cultured for 18 h in normoxic (19% O2), hypoxic (5% O2) or anoxic (1% O2) conditions. Following the incubation ROS (O2- and H2O2) production and the activity of scavenging enzymes (SOD, catalase and peroxidase) were determined. It was apparent from our data that ROS generation was reduced by hypoxia. On the contrary, SOD and peroxidase, but not catalase, increased their activity. Further studies are needed to verify whether ROS are involved in signalling hypoxia.
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Affiliation(s)
- Giuseppina Basini
- Dipartimento di Produzioni Animali, Biotecnologie Veterinarie, Qualità e Sicurezza degli Alimenti-Sezione di Fisiologia Veterinaria, Università di Parma, 43100 Parma, Italy.
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34
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Kummer W, Höhler B, Sell A, Hänze J, Pfeil U, Goldenberg A. Role of ROS and NO in hypoxia-induced increase in tyrosine hydroxylase-messenger RNA in PC12 cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 536:193-9. [PMID: 14635667 DOI: 10.1007/978-1-4419-9280-2_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Wolfgang Kummer
- Institute for Anatomy and Cell Biology, Justus-Liebig-University, 35385 Giessen, Germany
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35
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Hool LC. Differential regulation of the slow and rapid components of guinea-pig cardiac delayed rectifier K+ channels by hypoxia. J Physiol 2003; 554:743-54. [PMID: 14634203 PMCID: PMC1664794 DOI: 10.1113/jphysiol.2003.055442] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The aim of this study was to examine the effects of acute hypoxia on the slow (I(Ks)) and rapid (I(Kr)) components of the native delayed rectifier K+ channel in the absence and presence of the beta-adrenergic receptor agonist isoproterenol (isoprenaline; Iso) using the whole-cell configuration of the patch-clamp technique. Hypoxia reversibly inhibited basal I(Ks). The effect could be mimicked by exposing the cells to the thiol-specific reducing agent dithiothreitol (DTT) and attenuated upon exposure of cells to the membrane-impermeant thiol-specific oxidizing compound 5,5'-dithio-bis[2-nitrobenzoic acid] (DTNB). In the presence of hypoxia, the K(0.5) for activation of I(Ks) by Iso was significantly decreased from 18.3 to 1.9 nm. DTT mimicked the effect of hypoxia on the sensitivity of I(Ks) to Iso while DTNB had no effect. Hypoxia increased the sensitivity of I(Ks) to histamine and forskolin suggesting that the effect of hypoxia is not occurring at the beta-adrenergic receptor. The increase in sensitivity of I(Ks) to Iso could be attenuated with addition of PKCbeta peptide to the pipette solution. While hypoxia and DTT inhibited basal I(Ks) they were without effect on I(Kr.) In addition, Iso did not appear to alter the magnitude of I(Kr) in the absence or presence of hypoxia. These data suggest that hypoxia regulates native I(Ks) through two distinct mechanisms: direct inhibition of basal I(Ks) and an increase in sensitivity to Iso that occurs downstream from the beta-adrenergic receptor. Both mechanisms appear to involve redox modification of thiol groups. In contrast native I(Kr) does not appear to be regulated by Iso, hypoxia or redox state.
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Affiliation(s)
- Livia C Hool
- Physiology M311, School of Biomedical and Chemical Sciences, The University of Western Australia, Stirling Highway, Crawley, WA 6009, Australia.
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36
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Hui AS, Striet JB, Gudelsky G, Soukhova GK, Gozal E, Beitner-Johnson D, Guo SZ, Sachleben LR, Haycock JW, Gozal D, Czyzyk-Krzeska MF. Regulation of catecholamines by sustained and intermittent hypoxia in neuroendocrine cells and sympathetic neurons. Hypertension 2003; 42:1130-6. [PMID: 14597643 DOI: 10.1161/01.hyp.0000101691.12358.26] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic intermittent hypoxia, a characteristic feature of sleep-disordered breathing, induces hypertension through augmented sympathetic nerve activity and requires the presence of functional carotid body arterial chemoreceptors. In contrast, chronic sustained hypoxia does not alter blood pressure. We therefore analyzed the biosynthetic pathways of catecholamines in peripheral nervous system structures involved in the pathogenesis of intermittent hypoxia-induced hypertension, namely, carotid bodies, superior cervical ganglia, and adrenal glands. Rats were exposed to either intermittent hypoxia (90 seconds of room air alternating with 90 seconds of 10% O2) or to sustained hypoxia (10% O2) for 1 to 30 days. Dopamine, norepinephrine, epinephrine, dihydroxyphenylacetic acid, and 5-hydroxytyptamine contents were measured by high-performance liquid chromatography. Expression of tyrosine hydroxylase and its phosphorylated forms, dopamine beta-hydroxylase, phenylethanolamine N-methyltransferase, and GTP cyclohydrolase-1 were determined by Western blot analyses. Both sustained and intermittent hypoxia significantly increased dopamine and norepinephrine content in carotid bodies but not in sympathetic ganglia or adrenal glands. In carotid bodies, both types of hypoxia augmented total levels of tyrosine hydroxylase protein and its phosphorylation on serines 19, 31, 40, as well as levels of GTP cyclohydrolase-1. However, the effects of intermittent hypoxia on catecholaminergic pathways were significantly smaller and delayed than those induced by sustained hypoxia. Thus, attenuated induction of catecholaminergic phenotype by intermittent hypoxia in carotid body may play a role in development of hypertension associated with sleep-disordered breathing. The effects of both types of hypoxia on expression of catecholaminergic enzymes in superior cervical neurons and adrenal glands were transient and small.
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Affiliation(s)
- Anna S Hui
- Department of Genome Science, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267-0505, USA
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Jones KL, Krous HF, Nadeau J, Blackbourne B, Zielke HR, Gozal D. Vascular endothelial growth factor in the cerebrospinal fluid of infants who died of sudden infant death syndrome: evidence for antecedent hypoxia. Pediatrics 2003; 111:358-63. [PMID: 12563064 DOI: 10.1542/peds.111.2.358] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES Recurrent hypoxemia has been proposed as an important pathophysiological mechanism underlying sudden infant death syndrome (SIDS). However, conflicting results emerged when xanthines were used as markers for hypoxia. The vascular endothelial growth factor (VEGF) gene is highly sensitive to changes in tissue partial oxygen tension, and changes in genomic and protein expression occur even after changes in oxygenation within the physiologic range. METHODS For determining whether hypoxia precedes SIDS, VEGF levels were measured using an enzyme-linked immunosorbent assay in the cerebrospinal fluid (CSF) of 51 SIDS infants and in 33 additional control infants who died of an identifiable cause. In addition, 6 rats that had a chronically implanted catheter in the lateral ventricle were exposed to a short hypoxic challenge, and VEGF concentrations were measured in CSF at various time points for 24 hours. Another set of 6 rats were killed with a pentobarbital overdose, and VEGF CSF levels were obtained at different time points after death. RESULTS Mean VEGF concentrations in CSF were 308.2 +/- 299.1 pg/dL in the SIDS group and 85.1 +/- 82.9 pg/dL in those who died of known causes. Mean postmortem delay averaged 22 hours for both groups. In rat experiments, hypoxic exposures induced time-dependent increases in VEGF, peaking at 12 hours and returning to baseline at 24 hours. Postmortem duration in the animals was associated with gradual increases in VEGF that reached significance only at 36 hours. CONCLUSIONS We conclude that VEGF CSF concentrations are significantly higher in infants who die of SIDS. We postulate that hypoxia is a frequent event that precedes the sudden and unexpected death of these infants.
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Affiliation(s)
- Kimberly L Jones
- Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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38
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Tang MZ, Wang ZF, Shi YL. Toosendanin induces outgrowth of neuronal processes and apoptosis in PC12 cells. Neurosci Res 2003; 45:225-31. [PMID: 12573469 DOI: 10.1016/s0168-0102(02)00225-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the present study, the effects of toosendanin on cell differentiation and apoptosis were investigated in PC12 cells. The results showed that after 24-48 h of culture in a medium containing toosendanin (approximately 1-10x10(-7) M), cell differentiation and outgrowth of neuronal processes were promoted. Combined treatment with toosendanin and a calcium channel blocker, nifedipine or omega-conotoxin GVIA, resulted in a significant inhibition of the toosendanin-induced effects. Pretreatment of PC12 cells with BAPTA-AM also inhibited the toosendanin-induced effects; however, these effects were not inhibited by pertussis toxin and H-7 in the medium. Toosendanin also induced cell apoptosis. Based on the DNA content determined by flow cytometric analysis, the number of apoptotic cells significantly increased when the incubation time in the toosendanin-containing medium was lasted up to 72 h. Toosendanin at a higher concentration (> or =1 x 10(-6) M) caused cell death while it had no effect on cell division at concentrations lower than 1 x 10(-7) M.
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Affiliation(s)
- Mian-Zhi Tang
- Key Laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, PR China
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39
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Tampo Y, Kotamraju S, Chitambar CR, Kalivendi SV, Keszler A, Joseph J, Kalyanaraman B. Oxidative stress-induced iron signaling is responsible for peroxide-dependent oxidation of dichlorodihydrofluorescein in endothelial cells: role of transferrin receptor-dependent iron uptake in apoptosis. Circ Res 2003; 92:56-63. [PMID: 12522121 DOI: 10.1161/01.res.0000048195.15637.ac] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Dichlorodihydrofluorescein (DCFH) is one of the most frequently used probes for detecting intracellular oxidative stress. In this study, we report that H2O2-dependent intracellular oxidation of DCFH to a green fluorescent product, 2',7'-dichlorofluorescein (DCF), required the uptake of extracellular iron transported through a transferrin receptor (TfR) in endothelial cells. H2O2-induced DCF fluorescence was inhibited by the monoclonal IgA-class anti-TfR antibody (42/6) that blocked TfR endocytosis and the iron uptake. H2O2-mediated inactivation of cytosolic aconitase was responsible for activation of iron regulatory protein-1 and increased expression of TfR, resulting in an increased iron uptake into endothelial cells. H2O2-mediated caspase-3 proteolytic activation was inhibited by anti-TfR antibody. Similar results were obtained in the presence of a lipid hydroperoxide. We conclude that hydroperoxide-induced DCFH oxidation and endothelial cell apoptosis required the uptake of extracellular iron by the TfR-dependent iron transport mechanism and that the peroxide-induced iron signaling, in general, has broader implications in oxidative vascular biology.
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Affiliation(s)
- Yoshiko Tampo
- Biophysics Research Institute and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, Wis 53226, USA
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40
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Hool LC, Arthur PG. Decreasing cellular hydrogen peroxide with catalase mimics the effects of hypoxia on the sensitivity of the L-type Ca2+ channel to beta-adrenergic receptor stimulation in cardiac myocytes. Circ Res 2002; 91:601-9. [PMID: 12364388 DOI: 10.1161/01.res.0000035528.00678.d5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In cardiac myocytes, hypoxia inhibits the basal L-type Ca2+ current (I(Ca-L)) and increases the sensitivity of I(Ca-L) to beta-adrenergic receptor stimulation. We investigated whether hydrogen peroxide (H2O2) is involved in the hypoxic response. Guinea pig ventricular myocytes were dialyzed with catalase, which specifically catalyzes the conversion of H2O2 to H2O and oxygen, and then I(Ca-L) was recorded during exposure to isoproterenol (Iso). Catalase decreased the K(0.5) for activation of I(Ca-L) by Iso from 2.7+/-0.3 nmol/L (in cells dialyzed with heat-inactivated catalase) to 0.4+/-0.1 nmol/L. The increase in sensitivity to Iso by catalase may be attenuated when cells are preexposed to H2O2. A significant increase in sensitivity of I(Ca-L) to Iso was recorded when mitochondrial function was inhibited with myxothiazol or FCCP, suggesting that the source of H2O2 was from the mitochondria. Prior exposure of cells to H2O2 attenuated the inhibition of basal I(Ca-L) during hypoxia and the increase in sensitivity of I(Ca-L) to Iso during hypoxia. Additionally, extracellularly applied catalase mimicked the effect of hypoxia on basal I(Ca-L). Measurement of the rate of production of hydrogen peroxide using 5- (and 6-)chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate acetyl ester indicated that hypoxia was associated with a significant decrease in the production of hydrogen peroxide in the cells. These data suggest that hypoxia mediates changes in channel activity through a lowering in H2O2 levels and that H2O2 is a key intermediate in modifying basal channel activity and the beta-adrenergic responsiveness of the channel during hypoxia.
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Affiliation(s)
- Livia C Hool
- Department of Physiology, The University of Western Australia, Crawley, Australia.
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41
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Henrich M, Hoffmann K, König P, Gruss M, Fischbach T, Gödecke A, Hempelmann G, Kummer W. Sensory neurons respond to hypoxia with NO production associated with mitochondria. Mol Cell Neurosci 2002; 20:307-22. [PMID: 12093162 DOI: 10.1006/mcne.2002.1111] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Oxygen is pivotal for mammalian cell function, and recent studies suggest an involvement of NO in cellular adaptation to low oxygen supply. Here, we report that endothelial NO-synthase is ubiquitously expressed in rat and mice sensory neurons, and is targeted to juxtamitochondrial compartments of the ER. There it is activated in response to hypoxia while generation of reactive oxygen species remains unaltered. Developing a technique for ultrastructural localization of an NO-sensitive indicator allowed to identify the inner mitochondrial membrane as the target of NO under hypoxia. The demonstrated hypoxic stimulation of endothelial NOS in sensory neurons shall contribute to resistance against hypoxia, since NO promotes cellular survival by interfering with mitochondrial function.
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Affiliation(s)
- Michael Henrich
- Department of Anaesthesiology and Intensive Care, Justus-Liebig-University, D-35385 Giessen, Germany
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42
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Lash GE, Postovit LM, Matthews NE, Chung EY, Canning MT, Pross H, Adams MA, Graham CH. Oxygen as a regulator of cellular phenotypes in pregnancy and cancer. Can J Physiol Pharmacol 2002; 80:103-9. [PMID: 11934252 DOI: 10.1139/y02-008] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular phenotype is determined by genetic and microenvironmental factors. There is evidence that tissue oxygenation status is one of the microenvironmental factors regulating cellular behaviour. Both normal and pathological processes such as blastocyst implantation in the uterus, placentation, and rapidly growing tumours occur under conditions characterized by relatively low oxygen levels. In this review, we address the effects of low oxygen concentrations on the phenotype of trophoblast and cancer cells. We provide evidence that oxygenation levels play an important role in the regulation of normal and pathological cellular invasiveness as it occurs during trophoblast invasion of the uterus and in tumour progression and metastasis, drug resistance in cancer, and antitumour activity of natural killer cells of the immune system.
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Affiliation(s)
- Gendie E Lash
- Department of Anatomy, Queen's University, Kingston, Canada
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Matthews NE, Adams MA, Maxwell LR, Gofton TE, Graham CH. Nitric oxide-mediated regulation of chemosensitivity in cancer cells. J Natl Cancer Inst 2001; 93:1879-85. [PMID: 11752013 DOI: 10.1093/jnci/93.24.1879] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Hypoxia in tumors is associated with malignant progression, metastatic spread, and increased resistance to radiotherapy and chemotherapy. Molecular O(2) is required for the cellular production of nitric oxide (NO) by the enzyme NO synthase (NOS), and NO may block components of the adaptive response to hypoxia. Hence, we hypothesized that hypoxia increases drug resistance in tumor cells by inhibiting endogenous NO production. METHODS Human breast carcinoma (MDA-MB-231) and mouse melanoma (B16F10) cells were pre-exposed to 20% O(2), 5% O(2), or 1% O(2), incubated with a pharmacologic inhibitor of endogenous NO production, and then treated with chemotherapeutic agents. Resistance was assessed by colony-formation assays, and western blot analysis was used to measure NOS protein levels. All P values were two-sided. RESULTS Incubation of MDA-MB-231 tumor cells in 1% O(2) maximally increased their resistance to doxorubicin and 5-fluorouracil by 8.5-fold (P =.002) and 2.3-fold (P =.002), respectively, compared with incubation in 20% O(2). B16F10 mouse melanoma cells preincubated in 1% O(2) (versus 20% O(2)) for 12 hours exhibited a twofold increase in resistance to doxorubicin (P<.001). The rapid acquisition of drug resistance after exposure to 1% O(2) could be mimicked by incubating the MDA-MB-231 cells for 12 hours with the NOS inhibitor N(G)-monomethyl-Larginine (fivefold increase; P<.001). Conversely, replacement of NO activity by use of the NO-mimetic glyceryl trinitrate (GTN) and diethylenetriamine NO adduct produced statistically significant attenuations in the development of resistance of 59% (P<.001) and 40% (P<.001), respectively, in MDA-MB-231 cells. Treatment of B16F10 cells with GTN produced a 58% reduction in resistance (P<.001). MDA-MB-231 cells expressed all three isoforms of the NOS enzyme at levels that were not altered by exposure to hypoxia. CONCLUSIONS NO mediates chemosensitivity in tumor cells, and hypoxia-induced drug resistance appears to result, in part, from downstream suppression of endogenous NO production. These results raise the possibility that administration of small doses of NO mimetics could be used as an adjuvant in chemotherapy.
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Affiliation(s)
- N E Matthews
- Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada
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44
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Nossuli TO, Frangogiannis NG, Knuefermann P, Lakshminarayanan V, Dewald O, Evans AJ, Peschon J, Mann DL, Michael LH, Entman ML. Brief murine myocardial I/R induces chemokines in a TNF-alpha-independent manner: role of oxygen radicals. Am J Physiol Heart Circ Physiol 2001; 281:H2549-58. [PMID: 11709422 DOI: 10.1152/ajpheart.2001.281.6.h2549] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Early chemokine induction in the area at risk of an ischemic-reperfused (I/R) myocardium is first seen in the venular endothelium. Reperfusion is associated with several induction mechanisms including increased extracellular tumor necrosis factor (TNF)-alpha, reactive oxygen intermediate (ROI) species formation, and adhesion of leukocytes to the venular endothelium. To test the hypothesis that chemokine induction in cardiac venules can occur by ROIs in a TNF-alpha-independent manner, and in the absence of leukocyte accumulation, we utilized wild-type (WT) and TNF-alpha double-receptor knockout mice (DKO) in a closed-chest mouse model of myocardial ischemia (15 min) and reperfusion (3 h), in which there is no infarction. We demonstrate that a single brief period of I/R induces significant upregulation of the chemokines macrophage inflammatory protein (MIP) -1 alpha, -1 beta, and -2 at both the mRNA and protein levels. This induction was independent of TNF-alpha, whereas levels of these chemokines were increased in both WT and DKO mice. Chemokine induction was seen predominantly in the endothelium of small veins and was accompanied by nuclear translocation of nuclear factor-kappa B and c-Jun (AP-1) in venular endothelium. Intravenous infusion of the oxygen radical scavenger N-2-mercaptopropionyl glycine (MPG) initiated 15 min before ischemia and maintained throughout reperfusion obviated chemokine induction, but MPG administration after reperfusion had begun had no effect. The results suggest that ROI generation in the reperfused myocardium rapidly induces C-C and C-X-C chemokines in the venular endothelium in the absence of infarction or irreversible cellular injury.
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Affiliation(s)
- T O Nossuli
- Section of Cardiovascular Sciences and Cardiology, Department of Medicine, the DeBakey Heart Center, Baylor College of Medicine, and the Methodist Hospital, Texas 77030, USA
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45
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Zou W, Yan M, Xu W, Huo H, Sun L, Zheng Z, Liu X. Cobalt chloride induces PC12 cells apoptosis through reactive oxygen species and accompanied by AP-1 activation. J Neurosci Res 2001; 64:646-53. [PMID: 11398189 DOI: 10.1002/jnr.1118] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Reactive oxygen species (ROS) are supposed to play an important role in hypoxia- and ischemia/reperfusion-mediated neuronal injury with the characteristics of apoptosis. There are many reports showing that cobalt chloride (CoCl(2)) could mimic the hypoxic responses in some aspects including production of ROS in cultured cells. The cytotoxicity of CoCl(2) and its molecular mechanisms have yet to be elucidated. We report that CoCl(2) triggered neuronal PC12 cells apoptosis in a dose- and time-dependent manner. Apoptosis was demonstrated by morphological changes and DNA fragmentation, and was dependent on macromolecular synthesis. Apoptosis was also confirmed by the decrease of the expression of Bcl-X(L). To our knowledge, this is the first documentation of the apoptotic induction of CoCl(2) on PC12 cells. Furthermore, ROS production in PC12 cells was increased during CoCl(2) treatment. Antioxidants, which could inhibit ROS production, significantly blocked CoCl(2)-induced apoptosis, suggesting that apoptosis is mediated by ROS production. We also observed a significant increase of the DNA-binding activity of AP-1 in response to CoCl(2) and this increase was blocked by antioxidants, showing that CoCl(2)-induced apoptosis is accompanied by ROS-activated AP-1. CoCl(2)-treated PC12 cells may serve as an in vitro model for studies of molecular mechanisms in ROS-linked neuronal disorders.
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Affiliation(s)
- W Zou
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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46
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Abstract
BACKGROUND -The aim of the present study was to establish whether isolated neonatal mammalian cardiomyocytes were capable of downregulating energy-using processes other than contraction while maintaining metabolic stability when oxygen availability was reduced. METHODS AND RESULTS Metabolic response of cardiomyocytes was investigated under moderate (5 to 6 micromol/L) and severe (2 to 3 micromol/L) forms of hypoxia. Cells exposed to oxygen concentrations of 5 to 6 micromol/L exhibited rates of oxygen consumption, which were decreased to 64% of normoxic rates. Rates of cellular energy usage were decreased because this reduced rate of oxygen consumption was not associated with either decreased intracellular ATP and phosphocreatine concentrations or a compensatory switch to glycolysis. When cells were exposed to oxygen concentrations of 2 to 3 micromol/L, rates of oxygen consumption decreased to 9% of normoxic rates. This decreased rate of oxygen consumption was associated with energetic stress, because a significant switch to glycolysis occurred and intracellular phosphocreatine concentrations were decreased by 40%. Rates of cellular energy usage were further decreased as indicated by stable intracellular ATP concentrations. CONCLUSIONS -Our results suggest that isolated cardiomyocytes are capable of downregulating energy-consuming processes other than contraction when oxygen supply is decreased. Regions of myocardial tissue are also capable of downregulating metabolic activity during ischemia by shutting down contractile activity (myocardial hibernation). We suggest that metabolic downregulation associated with myocardial hibernation may not be exclusively due to reduced rates of contractile activity. Other energy-using processes (eg, protein synthesis, mRNA synthesis, ion channel activity, and proton leak) may also be shut down.
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Affiliation(s)
- T M Casey
- Department of Biochemistry, The University of Western Australia, Nedlands, Australia
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47
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Kummer W, Höhler B, Goldenberg A, Lange B. Subcellular localization and function of B-type cytochromes in carotid body and other paraganglionic cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 475:371-5. [PMID: 10849676 DOI: 10.1007/0-306-46825-5_34] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- W Kummer
- Institute of Anatomy and Cell Biology, Justus-Liebig-University, Giessen, Germany
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48
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Park H, Adams MA, Lachat P, Bosman F, Pang SC, Graham CH. Hypoxia induces the expression of a 43-kDa protein (PROXY-1) in normal and malignant cells. Biochem Biophys Res Commun 2000; 276:321-8. [PMID: 11006124 DOI: 10.1006/bbrc.2000.3475] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This study was designed to determine the expression of cellular factors that may participate in phenotypic changes that occur under conditions of hypoxia. Using the RT-PCR differential display method, we isolated a cDNA fragment corresponding to a gene whose expression was induced in trophoblast and breast carcinoma cells cultured under 1 or 2% oxygen vs 4% oxygen or higher. This gene encodes a 43-kDa protein initially identified in homocysteine-treated endothelial cells and later shown to be upregulated in various human and mouse cell types (termed RTP, Drg1, Cap43, rit42, Ndr1). Herein we refer to this gene product as PROXY-1, for Protein Regulated by OXYgen-1. Elevated mRNA and protein levels were first observed in cells cultured in 1% oxygen for 8 h. Although PROXY-1 mRNA levels returned to near-control values within 2 h of reexposure to 20% oxygen, protein levels remained high 72 h after reexposure to 20% oxygen. Treatment of cells with hypoxia mimics such as cobalt or iron chelators also increased PROXY-1 expression. Moreover, presence of 30% carbon monoxide in the hypoxic atmosphere abrogated the upregulation of PROXY-1 expression. These findings suggest that hypoxia upregulates PROXY-1 levels through a heme protein-dependent pathway and that assessment of PROXY-1 expression may be of potential use in evaluating tissue hypoxia.
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Affiliation(s)
- H Park
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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49
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Ren X, Dorrington KL, Maxwell PH, Robbins PA. Effects of desferrioxamine on serum erythropoietin and ventilatory sensitivity to hypoxia in humans. J Appl Physiol (1985) 2000; 89:680-6. [PMID: 10926654 DOI: 10.1152/jappl.2000.89.2.680] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In cell culture, hypoxia stabilizes a transcriptional complex called hypoxia-inducible factor-1 (HIF-1) that increases erythropoietin (Epo) formation. One hallmark of HIF-1 responses is that they can be induced by iron chelation. The first aim of this study was to examine whether an infusion of desferrioxamine (DFO) increased serum Epo in humans. If so, this might provide a paradigm for identifying other HIF-1 responses in humans. Consequently a second aim was to determine whether an infusion of DFO would mimic prolonged hypoxia and increase the acute hypoxic ventilatory response (AHVR). Sixteen volunteers undertook two protocols: 1) continuous infusion of DFO over 8 h and 2) control. Epo and AHVR were measured at fixed times during and after the protocols. The results show that 1) compared with control, Epo increased in most subjects at 8 h [52.8 +/- 57.7 vs. 6.9 +/- 2.5 (SD) mIU/ml, for DFO = 4 g/70 kg body wt, P < 0.05] and 12 h (63.7 +/- 76.3 vs. 7.3 +/- 2.5 mIU/ml, P < 0.001) after the start of DFO administration and 2) DFO had no significant effect on AHVR. We conclude that, whereas infusions of DFO mimic hypoxia by increasing Epo, they do not mimic prolonged hypoxia by augmenting AHVR.
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Affiliation(s)
- X Ren
- University Laboratory of Physiology, University of Oxford, United Kingdom
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50
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Wang G, Hazra TK, Mitra S, Lee HM, Englander EW. Mitochondrial DNA damage and a hypoxic response are induced by CoCl(2) in rat neuronal PC12 cells. Nucleic Acids Res 2000; 28:2135-40. [PMID: 10773083 PMCID: PMC105383 DOI: 10.1093/nar/28.10.2135] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Generation of reactive oxygen species (ROS) and activation of a transcriptional program that mimics the hypoxic response have been documented in cultured cells in the presence of cobalt chloride. We found that in the presence of hypoxia-mimicking concentrations of CoCl(2), mitochondrial but not nuclear DNA damage is induced in rat neuronal, PC12 cells. To our knowledge, this is the first documentation of induction of mitochondrial DNA (mtDNA) damage under these conditions. Likewise, we provide the first evidence for elevation of MYH, the mammalian homolog of the Escherichia coli MutY DNA glycosylase, in mammalian cells. Recently, the human MYH was implicated in repair of oxidative DNA damage and shown to carry a mitochondrial localization sequence. Here, an induction of mtDNA damage and a time-dependent increase in the MYH level were detected with exposure of cells to 100 microM CoCl(2). In addition, the levels of proteins involved in cellular responses to hypoxia, ROS and nuclear DNA damage; hypoxia-inducible factor 1alpha(HIF-1alpha), p53, p21 and PCNA were also modulated temporally. Earlier studies suggested that the mtDNA is a primary target for oxidative damage. Our findings extend these observations and suggest that activation of DNA repair processes is associated with the presence of mtDNA damage.
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Affiliation(s)
- G Wang
- Department of Surgery and Shriners Hospitals for Children and Sealy Center for Molecular Science, The University of Texas Medical Branch, Galveston, TX 77555, USA
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