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Hou J, Wen X, Long P, Xiong S, Liu H, Cai L, Deng H, Zhang Z. The role of post-translational modifications in driving abnormal cardiovascular complications at high altitude. Front Cardiovasc Med 2022; 9:886300. [PMID: 36186970 PMCID: PMC9515308 DOI: 10.3389/fcvm.2022.886300] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
The high-altitude environment is characterized by hypobaric hypoxia, low temperatures, low humidity, and high radiation, which is a natural challenge for lowland residents entering. Previous studies have confirmed the acute and chronic effects of high altitude on the cardiovascular systems of lowlanders. Abnormal cardiovascular complications, including pulmonary edema, cardiac hypertrophy and pulmonary arterial hypertension were commonly explored. Effective evaluation of cardiovascular adaptive response in high altitude can provide a basis for early warning, prevention, diagnosis, and treatment of altitude diseases. At present, post-translational modifications (PTMs) of proteins are a key step to regulate their biological functions and dynamic interactions with other molecules. This process is regulated by countless enzymes called “writer, reader, and eraser,” and the performance is precisely controlled. Mutations and abnormal expression of these enzymes or their substrates have been implicated in the pathogenesis of cardiovascular diseases associated with high altitude. Although PTMs play an important regulatory role in key processes such as oxidative stress, apoptosis, proliferation, and hypoxia response, little attention has been paid to abnormal cardiovascular response at high altitude. Here, we reviewed the roles of PTMs in driving abnormal cardiovascular complications at high altitude.
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Affiliation(s)
- Jun Hou
- Department of Cardiology, Chengdu Third People’s Hospital, Cardiovascular Disease Research Institute of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu, China
- School of Material Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Xudong Wen
- Department of Gastroenterology and Hepatology, Chengdu First People’s Hospital, Chengdu, China
| | - Pan Long
- School of Material Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Shiqiang Xiong
- Department of Cardiology, Chengdu Third People’s Hospital, Cardiovascular Disease Research Institute of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu, China
| | - Hanxiong Liu
- Department of Cardiology, Chengdu Third People’s Hospital, Cardiovascular Disease Research Institute of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu, China
| | - Lin Cai
- Department of Cardiology, Chengdu Third People’s Hospital, Cardiovascular Disease Research Institute of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu, China
- *Correspondence: Lin Cai,
| | - Haoyu Deng
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Center for Heart and Lung Innovation, St. Paul’s Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Vascular Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Haoyu Deng,
| | - Zhen Zhang
- Department of Cardiology, Chengdu Third People’s Hospital, Cardiovascular Disease Research Institute of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu, China
- Zhen Zhang,
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Han X, Wang Y, Huang Y, Wang X, Choo J, Chen L. Fluorescent probes for biomolecule detection under environmental stress. JOURNAL OF HAZARDOUS MATERIALS 2022; 431:128527. [PMID: 35231812 DOI: 10.1016/j.jhazmat.2022.128527] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
The use of fluorescent probes in visible detection has been developed over the last several decades. Biomolecules are essential in the biological processes of organisms, and their distribution and concentration are largely influenced by environmental factors. Significant advances have occurred in the applications of fluorescent probes for the detection of the dynamic localization and quantity of biomolecules during various environmental stress-induced physiological and pathological processes. Herein, we summarize representative examples of small molecule-based fluorescent probes that provide bimolecular information when the organism is under environmental stress. The discussion includes strategies for the design of smart small-molecule fluorescent probes, in addition to their applications in biomolecule imaging under environmental stresses, such as hypoxia, ischemia-reperfusion, hyperthermia/hypothermia, organic/inorganic chemical exposure, oxidative/reductive stress, high glucose stimulation, and drug treatment-induced toxicity. We believe that comprehensive insight into the beneficial applications of fluorescent probes in biomolecule detection under environmental stress should enable the further development and effective application of fluorescent probes in the biochemical and biomedical fields.
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Affiliation(s)
- Xiaoyue Han
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; Present: Ludwig Institute for Cancer Research, Nuffield Department of Clinical Medicine, University of Oxford, UK; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Wang
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Huang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Xiaoyan Wang
- School of Pharmacy, Binzhou Medical University, Yantai 264003, China
| | - Jaebum Choo
- Department of Chemistry, Chung-Ang University, Seoul 06974, South Korea.
| | - Lingxin Chen
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; School of Pharmacy, Binzhou Medical University, Yantai 264003, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China.
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3
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Ağaşcıoğlu E, Çolak R, Çakatay U. Redox status biomarkers in the fast-twitch extensor digitorum longus resulting from the hypoxic exercise. NAGOYA JOURNAL OF MEDICAL SCIENCE 2022; 84:433-447. [PMID: 35967949 PMCID: PMC9350571 DOI: 10.18999/nagjms.84.2.433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/01/2021] [Indexed: 11/29/2022]
Abstract
The fast-twitch muscle may be affected from over-produced reactive oxygen species (ROS) during hypoxia/hypoxic exercise. The study aims to investigate redox status biomarkers in the fast-twitch extensor digitorum longus (EDL) muscle after hypoxic exercise. Male Sprague Dawley rats (eight-week-old) were randomly divided into six groups of the experimental "live high train high (LHTH), live high train low (LHTL) and live low train low (LLTL)" and their respective controls. Before the EDLs' extraction, the animals exercised for a 4-week familiarization period, then they exercised for four-weeks at different altitudes. The LHTH group had higher ratios of lipid hydroperoxides (LHPs) than the experimental groups of LHTL (p=0.004) and LLTL (p=0.002), while having no difference than its control 'LH'. Similarly, a higher percentage of advanced oxidation protein products (AOPP) was determined in the LHTH than the LHTL (p=0.041) and LLTL (p=0.048). Furthermore, oxidation of thiol fractions was the lowest in the LHTH and LH. However, redox biomarkers and thiol fractions illustrated no significant change in the LHTL and LLTL that might ensure redox homeostasis due to higher oxygen consumption. The study shows that not hypoxic exercise/exercise, but hypoxia might itself lead to a redox imbalance in the fast-twitch EDL muscle.
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Affiliation(s)
- Eda Ağaşcıoğlu
- Department of Recreation, Faculty of Sports Sciences, Lokman Hekim University, Ankara, Turkey
| | - Rıdvan Çolak
- Department of Physical Education and Sports, Ardahan University, Ardahan, Turkey
| | - Ufuk Çakatay
- Department of Medical Biochemistry, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
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Characterization of the Impacts of Living at High Altitude in Taif: Oxidative Stress Biomarker Alterations and Immunohistochemical Changes. Curr Issues Mol Biol 2022; 44:1610-1625. [PMID: 35723368 PMCID: PMC9164078 DOI: 10.3390/cimb44040110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022] Open
Abstract
At high elevations, the human body experiences a number of pathological, physiological, and biochemical changes, all of which have adverse impacts on human health and organ vitality. This study aimed to investigate the alterations in the liver and kidney biomarkers, oxidative stress markers, gene expression, and cellular histology of rats maintained at high altitudes and normal sea level. A total of twenty male Wistar rats at 2 months of age were randomly assigned to two groups. The rats in group A were maintained at normal sea level in Jeddah, whereas rats in group B were maintained in an area in Taif 2600 m above sea level. After 2 months of housing, orbital blood samples were collected for the analysis of significant biochemical indicators of oxidative stress biomarkers of the liver and kidneys. Liver and kidney tissues from both groups were taken to examine the hepatorenal changes occurring at the biochemical, histological, immunohistochemical, and genetic levels. The results revealed substantial increases in the serum levels of liver and kidney biomarkers (GPT, GOT, urea, and creatinine) and decreases in the serum levels of antioxidant biomarkers (SOD, catalase, GSH, and NO). In parallel, the levels of the malondialdehyde (MDA) tissue damage marker and inflammatory cytokines (IL-1β, TNF-α, and IFN-γ) were increased in the high-altitude group compared to the normal sea level group. In addition, there were significant alterations in the oxidative and inflammatory status of rats that lived at high altitude, with considerable upregulation in the expression of hepatic VEGF, type 1 collagen, Cox-2, TNF-α, and iNOS as well as renal EPASI, CMYC, HIF-α, and EGLN-2 genes in the high-altitude group compared with controls housed at normal sea level. In conclusion, living at high altitude induces hepatorenal damage and biochemical and molecular alterations, all of which may serve as critical factors that must be taken into account for organisms living at high altitudes.
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Zhang L, Patel S, Soulakova JN, Caldwell CC, St Pierre Schneider B. Mild hypobaric hypoxia influences splenic proliferation during the later phase of stress erythropoiesis. Exp Biol Med (Maywood) 2021; 247:509-518. [PMID: 34904451 DOI: 10.1177/15353702211060775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Tissue trauma and hemorrhagic shock are common battlefield injuries that can induce hypoxia, inflammation, and/or anemia. Inflammation and hypoxia can initiate adaptive mechanisms, such as stress erythropoiesis in the spleen, to produce red blood cells and restore the oxygen supply. In a military context, mild hypobaric hypoxia-part of the environmental milieu during aeromedical evacuation or en route care-may influence adaptive mechanisms, such as stress erythropoiesis, and host defense. In the present study, healthy (control), muscle trauma, and polytrauma (muscle trauma and hemorrhagic shock) mice were exposed to normobaric normoxia or hypobaric hypoxia for ∼17.5 h to test the hypothesis that hypobaric hypoxia exposure influences splenic erythropoiesis and splenic inflammation after polytrauma. This hypothesis was partially supported. The polytrauma + hypobaric hypoxia group exhibited more splenic neutrophils, fewer total spleen cells, and fewer splenic proliferating cells than the polytrauma+normobaric normoxia group; however, no splenic erythroid cell differences were detected between the two polytrauma groups. We also compared splenic erythropoiesis and myeloid cell numbers among control, muscle trauma, and polytrauma groups. More reticulocytes at 1.7 days (40 h) post-trauma (dpt) and neutrophils at 4 dpt were produced in the muscle trauma mice than corresponding control mice. In contrast to muscle trauma, polytrauma led to a reduced red blood cell count and elevated serum erythropoietin levels at 1.7 dpt. There were more erythroid subsets and apoptotic reticulocytes in the polytrauma mice than muscle trauma mice at 4 and 8 dpt. At 14 dpt, the red blood cell count of the polytrauma + normobaric normoxia mice was 12% lower than that of the control + normobaric normoxia mice; however, no difference was observed between polytrauma + hypobaric hypoxia and control + hypobaric hypoxia mice. Our findings suggest muscle trauma alone induces stress erythropoiesis; in a polytrauma model, hypobaric hypoxia exposure may result in the dysregulation of splenic cells, requiring a treatment plan to ensure adequate immune functioning.
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Affiliation(s)
- Liyuan Zhang
- School of Nursing, University of Nevada, Las Vegas, NV 89154, USA
| | - Shailey Patel
- School of Nursing, University of Nevada, Las Vegas, NV 89154, USA
| | - Julia N Soulakova
- Department of Population Health Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
| | - Charles C Caldwell
- College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
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Ilias I, Kaltsas G, Barkas K, Chrousos GP. Inherited/Genetically-Associated Pheochromocytoma/ Paraganglioma Syndromes and COVID-19. ACTA ACUST UNITED AC 2021; 57:medicina57101033. [PMID: 34684070 PMCID: PMC8538054 DOI: 10.3390/medicina57101033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/26/2021] [Accepted: 09/27/2021] [Indexed: 12/04/2022]
Abstract
In some subjects with inherited pheochromocytoma/paraganglioma (PPG) syndromes, hypoxia-inducible factor 1 alpha (HIF1α) stabilization/activation could lead to an increase in angiotensin converting enzymes (ACE). This would result in the stimulation of angiotensin (AT) II production and, hence, reduce the availability of ACE 2. The latter would provide decreased numbers of binding sites for the spike protein of SARS-CoV-2 and, therefore, result in less points of viral entry into cells. Thus, subjects with HIF1α-associated PPG syndromes may benefit from an inherent protective effect against COVID-19. Such an implication of HIF1α vis-à-vis COVID-19 could open ways of therapeutic interventions.
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Affiliation(s)
- Ioannis Ilias
- Department of Endocrinology, Diabetes and Metabolism, “Elena Venizelou” Hospital, GR-11521 Athens, Greece
- Correspondence: ; Tel.: +30-2132051389
| | - Gregory Kaltsas
- 1st Department of Propaedeutic and Internal Medicine, National and Kapodistrian University of Athens, GR-11527 Athens, Greece;
| | - Konstantinos Barkas
- Department of Neurosurgery, “Agios Panteleimon” General Hospital of Nikaia-Pireas, GR-12351 Athens, Greece;
| | - George P. Chrousos
- University Research Institute of Maternal and Child Health & Precision Medicine, National and Kapodistrian University of Athens, “Aghia Sophia” Children’s Hospital, GR-11527 Athens, Greece;
- UNESCO Chair on Adolescent Health Care, National and Kapodistrian University of Athens, “Aghia Sophia” Children’s Hospital, GR-11527 Athens, Greece
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Gheyas AA, Vallejo-Trujillo A, Kebede A, Lozano-Jaramillo M, Dessie T, Smith J, Hanotte O. Integrated Environmental and Genomic Analysis Reveals the Drivers of Local Adaptation in African Indigenous Chickens. Mol Biol Evol 2021; 38:4268-4285. [PMID: 34021753 PMCID: PMC8476150 DOI: 10.1093/molbev/msab156] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Breeding for climate resilience is currently an important goal for sustainable livestock production. Local adaptations exhibited by indigenous livestock allow investigating the genetic control of this resilience. Ecological niche modeling (ENM) provides a powerful avenue to identify the main environmental drivers of selection. Here, we applied an integrative approach combining ENM with genome-wide selection signature analyses (XPEHH and Fst) and genotype-environment association (redundancy analysis), with the aim of identifying the genomic signatures of adaptation in African village chickens. By dissecting 34 agro-climatic variables from the ecosystems of 25 Ethiopian village chicken populations, ENM identified six key drivers of environmental challenges: One temperature variable-strongly correlated with elevation, three precipitation variables as proxies for water availability, and two soil/land cover variables as proxies of food availability for foraging chickens. Genome analyses based on whole-genome sequencing (n = 245), identified a few strongly supported genomic regions under selection for environmental challenges related to altitude, temperature, water scarcity, and food availability. These regions harbor several gene clusters including regulatory genes, suggesting a predominantly oligogenic control of environmental adaptation. Few candidate genes detected in relation to heat-stress, indicates likely epigenetic regulation of thermo-tolerance for a domestic species originating from a tropical Asian wild ancestor. These results provide possible explanations for the rapid past adaptation of chickens to diverse African agro-ecologies, while also representing new landmarks for sustainable breeding improvement for climate resilience. We show that the pre-identification of key environmental drivers, followed by genomic investigation, provides a powerful new approach for elucidating adaptation in domestic animals.
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Affiliation(s)
- Almas A Gheyas
- Centre for Tropical Livestock Genetics and Health (CTLGH), The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Adriana Vallejo-Trujillo
- Cells, Organism and Molecular Genetics, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Adebabay Kebede
- LiveGene—CTLGH, International Livestock Research Institute (ILRI) Ethiopia, Addis Ababa, Ethiopia
- Amhara Regional Agricultural Research Institute, Bahir Dar, Ethiopia
| | - Maria Lozano-Jaramillo
- Wageningen University & Research Animal Breeding and Genomics, Wageningen, The Netherlands
| | - Tadelle Dessie
- LiveGene—CTLGH, International Livestock Research Institute (ILRI) Ethiopia, Addis Ababa, Ethiopia
| | - Jacqueline Smith
- Centre for Tropical Livestock Genetics and Health (CTLGH), The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Olivier Hanotte
- Cells, Organism and Molecular Genetics, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
- LiveGene—CTLGH, International Livestock Research Institute (ILRI) Ethiopia, Addis Ababa, Ethiopia
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8
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Çolak R, Ağaşcıoğlu E, Çakatay U. "Live High Train Low" Hypoxic Training Enhances Exercise Performance with Efficient Redox Homeostasis in Rats' Soleus Muscle. High Alt Med Biol 2020; 22:77-86. [PMID: 32960081 DOI: 10.1089/ham.2020.0136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Çolak, Rıdvan, Eda Ağaşcıoğlu, and Ufuk Çakatay. "Live high train low" hypoxic training enhances exercise performance with efficient redox homeostasis in rats' soleus muscle. High Alt Med Biol. 22:77-86, 2021. Background: Different types of hypoxic training have been performed to improve exercise performance. Although both "live high train high" and "live high train low" techniques are commonly performed, it is still obscure as to which one is more beneficial. Materials and Methods: Eight-week-old male Sprague-Dawley rats were randomly divided into aforementioned experimental groups. After a familiarization exercise (4-week, ∼15-30 minutes/day) at normoxia, all rats exercised (4-week, ∼35 minutes/day) at hypoxia with their pre-evaluated maximal aerobic velocity test. The soleus was extracted after the test following 2 days of resting. Results: The live high trained low group displayed better performance than the live high trained high (p = 0.031) and the live low trained low (p = 0.017) groups. Redox status biomarkers were higher in the live high trained high group except for thiols, which were illustrated with no difference among the groups. Further, contrary to total and protein thiols (r = 0.57, p = 0.037; r = 0.55, p = 0.042 respectively), other redox status biomarkers were observed to be negatively correlated to exercise performance. Conclusions: The live high trained low group could consume more oxygen during exercise, which might lead to having a better chance to ensure cellular redox homeostasis. Therefore, this group could ensure an optimum exercise performance and anabolic metabolism.
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Affiliation(s)
- Rıdvan Çolak
- Department of Physical Education and Sports, Ardahan University, Ardahan, Turkey
| | - Eda Ağaşcıoğlu
- Department of Recreation, Faculty of Sports Sciences, Lokman Hekim University, Ankara, Turkey
| | - Ufuk Çakatay
- Department of Medical Biochemistry, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
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Gassmann M, Cowburn A, Gu H, Li J, Rodriguez M, Babicheva A, Jain PP, Xiong M, Gassmann NN, Yuan JXJ, Wilkins MR, Zhao L. Hypoxia-induced pulmonary hypertension-Utilizing experiments of nature. Br J Pharmacol 2020; 178:121-131. [PMID: 32464698 DOI: 10.1111/bph.15144] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/26/2020] [Accepted: 04/30/2020] [Indexed: 12/19/2022] Open
Abstract
An increase in pulmonary artery pressure is a common observation in adult mammals exposed to global alveolar hypoxia. It is considered a maladaptive response that places an increased workload on the right ventricle. The mechanisms initiating and maintaining the elevated pressure are of considerable interest in understanding pulmonary vascular homeostasis. There is an expectation that identifying the key molecules in the integrated vascular response to hypoxia will inform potential drug targets. One strategy is to take advantage of experiments of nature, specifically, to understand the genetic basis for the inter-individual variation in the pulmonary vascular response to acute and chronic hypoxia. To date, detailed phenotyping of highlanders has focused on haematocrit and oxygen saturation rather than cardiovascular phenotypes. This review explores what we can learn from those studies with respect to the pulmonary circulation. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.
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Affiliation(s)
- Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.,University Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Andrew Cowburn
- National Heart and Lung Institute (NHLI), Imperial College London, Hammersmith Hospital, London, UK
| | - Hong Gu
- Department of Pediatric Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Jia Li
- Clinical Physiology Laboratory, Institute of Pediatrics, Heart Center, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Marisela Rodriguez
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Aleksandra Babicheva
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Pritesh P Jain
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Mingmei Xiong
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Norina N Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Jason X-J Yuan
- Section of Physiology, Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Martin R Wilkins
- National Heart and Lung Institute (NHLI), Imperial College London, Hammersmith Hospital, London, UK
| | - Lan Zhao
- National Heart and Lung Institute (NHLI), Imperial College London, Hammersmith Hospital, London, UK
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10
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Impaired redox homeostasis in the heart left ventricles of aged rats experiencing fast-developing severe hypobaric hypoxia. Biogerontology 2019; 20:711-722. [DOI: 10.1007/s10522-019-09826-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 07/25/2019] [Indexed: 01/17/2023]
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Paul S, Arya A, Gangwar A, Bhargava K, Ahmad Y. Size restricted silymarin suspension evokes integrated adaptive response against acute hypoxia exposure in rat lung. Free Radic Biol Med 2016; 96:139-51. [PMID: 27105952 DOI: 10.1016/j.freeradbiomed.2016.04.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 03/22/2016] [Accepted: 04/18/2016] [Indexed: 12/14/2022]
Abstract
Despite its extraordinary antioxidant capacity, the clinical usage of silymarin has remained restricted to amelioration of hepatic pathology. Perhaps its low bioavailability and uneven bio-distribution, owing to its poor aqueous solubility, are two main causes that have dampened the clinical applicability and scope of this preparation. We took these two challenges and suggested an unexplored application of silymarin. Apart from liver, two of the most susceptible vital organs at the highest risk of oxidative stress are brain and lung, especially during reduced oxygen saturation (hypoxia) at anatomical level. Hypoxia causes excess generation of radicals primarily in the lungs as it is the first organ at the interphase of atmosphere and organism making it the most prone and vulnerable to oxidative stress and the first responder against hypobaric hypoxia. As our first objective, we improved the silymarin formulation by restricting its size to the lower threshold and then successfully tested the prophylactic and therapeutic action in rat lung challenged with simulated hypobaric hypoxia. After dose optimization, we observed that 50mg/kg BW silymarin as size restricted and homogenous aqueous suspension successfully minimized the reactive oxygen species and augmented the antioxidant defense by significant upregulation of catalase and superoxide dismutase and reduced glutathione. Moreover, the well-established hypoxia markers and proteins related to hypoxia adaptability, hif1a and VEGF were differentially regulated conferring significant reduction in the inflammation caused by hypobaric hypoxia. We therefore report,the unexplored potential benefits of silymarin for preventing high altitude associated pathophysiology further paving its road to clinical trials.
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Affiliation(s)
- Subhojit Paul
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization (DRDO), Ministry of Defence, Lucknow Road, Timarpur, Delhi 110054, India
| | - Aditya Arya
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization (DRDO), Ministry of Defence, Lucknow Road, Timarpur, Delhi 110054, India
| | - Anamika Gangwar
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization (DRDO), Ministry of Defence, Lucknow Road, Timarpur, Delhi 110054, India
| | - Kalpana Bhargava
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization (DRDO), Ministry of Defence, Lucknow Road, Timarpur, Delhi 110054, India
| | - Yasmin Ahmad
- Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization (DRDO), Ministry of Defence, Lucknow Road, Timarpur, Delhi 110054, India.
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Hill CM, Baya A, Gavlak J, Carroll A, Heathcote K, Dimitriou D, L'Esperance V, Webster R, Holloway J, Virues-Ortega J, Kirkham FJ, Bucks RS, Hogan AM. Adaptation to Life in the High Andes: Nocturnal Oxyhemoglobin Saturation in Early Development. Sleep 2016; 39:1001-8. [PMID: 26951394 DOI: 10.5665/sleep.5740] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/22/2016] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory 'burden' of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude. METHODS This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples. RESULTS Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence. CONCLUSIONS Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations.
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Affiliation(s)
- Catherine Mary Hill
- Division of Clinical Experimental Sciences, Faculty of Medicine, University of Southampton, UK.,Southampton Children's Hospital, Southampton, UK
| | - Ana Baya
- Department of Psychology, Universidad Privada de Santa Cruz de la Sierra, Santa Cruz - Bolivia
| | - Johanna Gavlak
- Southampton Children's Hospital, Southampton, UK.,Neurosciences Unit, UCL Institute of Child Health, UK
| | | | - Kate Heathcote
- Department of Otolaryngology, Poole General Hospital, UK
| | | | - Veline L'Esperance
- Department of Primary Care and Population Health, Kings College London, UK
| | - Rebecca Webster
- Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and University of Western Australia Centre for Medical Research, Perth, Australia
| | - John Holloway
- Division of Human Development and Health. Faculty of Medicine, University of Southampton, UK
| | - Javier Virues-Ortega
- School of Psychology, Faculty of Science, The University of Auckland, New Zealand
| | - Fenella Jane Kirkham
- Division of Clinical Experimental Sciences, Faculty of Medicine, University of Southampton, UK.,Southampton Children's Hospital, Southampton, UK.,Neurosciences Unit, UCL Institute of Child Health, UK
| | | | - Alexandra Marie Hogan
- Cognitive Neuroscience & Psychiatry, UCL Institute of Child Health, UK.,North Central London School of Anaesthesia, London, UK
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Xu C, Dong C, Xu C, Han T, Bao S, Gao X. Effect of iron supplementation on the expression of hypoxia-inducible factor and antioxidant status in rats exposed to high-altitude hypoxia environment. Biol Trace Elem Res 2014; 162:142-52. [PMID: 25380676 DOI: 10.1007/s12011-014-0166-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/28/2014] [Indexed: 12/18/2022]
Abstract
Iron and oxygen are essential substance for cellular activity in body tissues. Hypoxia-inducible factors (HIFs) can respond to available oxygen changes in the cellular environment and regulate the transcription of a series of target genes. The study was conducted to investigate the effects of iron supplementation on the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and antioxidant status in rats exposed to high-altitude hypoxia environment. Forty rats were divided into control (CON), hypobaric hypoxia (HH), and hypobaric hypoxia plus ferrous sulfate (FeSO4) (9.93 mg/kg body weight (BW)/day) (HFS) and hypobaric hypoxia plus iron glycinate chelate (Fe-Gly) (11.76 mg/kg BW/day) (HFG) groups. Results showed that Fe-Gly effectively alleviated weight loss and intestinal mucosa damage induced by hypobaric hypoxia, whereas FeSO4 aggravated hypobaric hypoxia-induced weight loss, liver enlargement, spleen atrophy, and intestinal damage. Iron supplementation decreased liver superoxide dismutase (T-SOD) and catalase (CAT) activity (P < 0.01) and increased iron concentration in the liver compared to HH group (P < 0.001). Moreover, Fe-Gly upregulated liver transferrin expression in messenger RNA (mRNA) level (P < 0.05) and downregulated serum erythropoietin (EPO) concentration (P < 0.01) and liver HIF-1α expression level (P < 0.05 in mRNA level; P < 0.001 in protein level) compared to HH group. The study indicated that FeSO4 supplementation at high altitudes aggravated the oxidative damage of tissues and organs that could be mediated through production of malondialdehyde (MDA) and inhibition antioxidant enzyme activities. Fe-Gly can protect hypobaric hypoxia-induced tissues injury. Moreover, iron supplementation at high altitudes affected HIF-1α-mediated regulating expression of targeting genes such as EPO and transferrin. The study highlights that iron supplementation under hypobaric hypoxia environment has possible limitation, and efficient supplementation form and dosage need careful consideration.
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Affiliation(s)
- Chunlan Xu
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 West Youyixi Road, Xi'an, Shaanxi, 710072, People's Republic of China,
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Ostergaard L, Rudiger A, Wellmann S, Gammella E, Beck-Schimmer B, Struck J, Maggiorini M, Gassmann M. Arginine-vasopressin marker copeptin is a sensitive plasma surrogate of hypoxic exposure. HYPOXIA 2014; 2:143-151. [PMID: 27774473 PMCID: PMC5045063 DOI: 10.2147/hp.s57894] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Background A reduced oxygen supply puts patients at risk of tissue hypoxia, organ damage, and even death. In response, several changes are activated that allow for at least partial adaptation, thereby increasing the chances of survival. We aimed to investigate whether the arginine vasopressin marker, copeptin, can be used as a marker of the degree of acclimatization/adaptation in rats exposed to hypoxia. Methods Sprague-Dawley rats were exposed to 10% oxygen for up to 48 hours. Arterial and right ventricular pressures were measured, and blood gas analysis was performed at set time points. Pulmonary changes were investigated by bronchoalveolar lavage, wet and dry weight measurements, and lung histology. Using a newly developed specific rat copeptin luminescence immunoassay, the regulation of vasopressin in response to hypoxia was studied, as was atrial natriuretic peptide (ANP) by detecting mid-regional proANP. Results With a decreasing oxygen supply, the rats rapidly became cyanotic and inactive. Despite continued exposure to 10% oxygen, all animals recuperated within 16 hours and ultimately survived. Their systemic blood pressure fell with acute (5 minutes) hypoxia but was partially recovered over time. In contrast, right ventricular pressures increased with acute (5 minutes) hypoxia and normalized after 16 hours. No signs of pulmonary inflammation or edema were found despite prolonged hypoxia. Whereas copeptin levels increased significantly after acute (5 minutes) hypoxia and then returned to near baseline after 16 hours, mid-regional proANP levels were even further increased after 16 hours of exposure to hypoxia. Conclusion Plasma copeptin is a sensitive marker of acute (5 minutes) exposure to severe hypoxia, and subsequent regulation can indicate recovery. Copeptin levels can therefore reflect clinical and physiological changes in response to hypoxia and indicate recovery from ongoing hypoxic exposure.
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Affiliation(s)
- Louise Ostergaard
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich; Zürich Center for Integrative Human Physiology
| | | | - Sven Wellmann
- Zürich Center for Integrative Human Physiology; Division of Neonatology, University Hospital Zürich, Zürich; Department of Neonatology, University Children's Hospital Basel, Basel, Switzerland
| | - Elena Gammella
- Department of Human Morphology and Biomedical Science, University of Milan, Milan, Italy
| | | | - Joachim Struck
- Research Department, B⋅R⋅A⋅H⋅M⋅S Biomarkers, Thermo Fisher Scientific, Hennigsdorf, Germany
| | - Marco Maggiorini
- Zürich Center for Integrative Human Physiology; Medical Intensive Care Unit, University Hospital Zürich, Zürich, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zürich; Zürich Center for Integrative Human Physiology; Universidad Peruana Cayetano Heredia, Lima, Peru
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15
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Xu C, Sun R, Qiao X, Xu C, Shang X, Niu W, Chao Y. Effect of vitamin e supplementation on intestinal barrier function in rats exposed to high altitude hypoxia environment. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:313-20. [PMID: 25177163 PMCID: PMC4146633 DOI: 10.4196/kjpp.2014.18.4.313] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/19/2014] [Accepted: 05/19/2014] [Indexed: 01/30/2023]
Abstract
The study was conducted to investigate the role of vitamin E in the high altitude hypoxia-induced damage to the intestinal barrier in rats. Sprague-Dawley rats were divided into control (Control), high altitude hypoxia (HH), and high altitude hypoxia+vitamin E (250 mg/kg BW*d) (HV) groups. After the third day, the HH and HV groups were placed in a hypobaric chamber at a stimulated elevation of 7000 m for 5 days. The rats in the HV group were given vitamin E by gavage daily for 8 days. The other rats were given equal volume saline. The results showed that high altitude hypoxia caused the enlargement of heart, liver, lung and kidney, and intestinal villi damage. Supplementation with vitamin E significantly alleviated hypoxia-caused damage to the main organs including intestine, increased the serum superoxide dismutase (SOD) (p< 0.05), diamino oxidase (DAO) (p< 0.01) levels, and decreased the serum levels of interleukin-2 (IL-2) (p< 0.01), interleukin-4 (IL-4) (p<0.001), interferon-gamma (IFN-γ) (p<0.01) and malondialdehyde (MDA) (p<0.001), and decreased the serum erythropoietin (EPO) activity (p<0.05). Administration of vitamin E significantly increased the S-IgA (p<0.001) in ileum and significantly improved the expression levels of occludin and IκBα, and decreased the expression levels of hypoxia-inducible factor 1 alpha and 2 alpha (HIF-1α and HIF-2α), Toll-like receptors (TLR4), P-IκBα and nuclear factor-κB p65(NF-κB P65) in ileum compared to the HH group. This study suggested that vitamin E protectis from intestinal injury caused by high altitude hypoxia environment. These effects may be related to the HIF and TLR4/NF-κB signaling pathway.
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Affiliation(s)
- Chunlan Xu
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Rui Sun
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Xiangjin Qiao
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Cuicui Xu
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Xiaoya Shang
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Weining Niu
- The Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R.China
| | - Yu Chao
- Affiliated Hospital of Xi'an Medical University, Xi'an, Shaanxi 710072, P.R.China
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17
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Effect of subchronic hypobaric hypoxia on oxidative stress in rat heart. Appl Biochem Biotechnol 2013; 169:2405-19. [PMID: 23456277 DOI: 10.1007/s12010-013-0141-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 02/18/2013] [Indexed: 12/31/2022]
Abstract
We examined the effect of subchronic hypobaric hypoxia in rat heart. Adult male Sprague-Dawley rats were exposed at 25,000 ft for different time periods (2 and 5 days). Susceptibility of their hearts to oxidative stress as well as modulation in gene expression was evaluated. The results showed a crosstalk between reactive oxygen species (ROS) and nitric oxide (NO), initial response was accompanied by increase in ROS generation and development of oxidative stress as confirmed by increased lipid peroxidation, protein oxidation and accumulation of 2, 4-dinitrophenyl hydrazine and 4-hydroxy-2-nonenal adducts. At the same time, glutathione activity decreased; however, antioxidant enzymatic activities of superoxide dismutases, glutathione-S-transferase, and glutathione peroxidase rose in response to 5-days hypoxia. Interestingly, NO level increased till 5 days, however ROS decreased after 5 days; this observation suggests that ROS/NO balance plays an important role in cardioprotection. This observation is further supported by upregulation of antioxidant genes hemeoxygenase (HO-1) and metallothionein (MT). In addition, hypoxia also induces gradual upregulation of hypoxia-inducible transcription factor (HIF-1α), which in turn induces the expression of adaptive genes erythropoiesis, vascular endothelial growth factor, glucose transporter-1, nitric oxide synthase. Collectively, our data suggests a reciprocal regulation of ROS and NO and this effect is mediated by the increase in antioxidant proteins HO-1 and MT. Along with this HIF-1-mediated induction of various cardioprotective genes also plays an important role in acclimatization.
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18
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Abstract
The hematopoietic growth factor erythropoietin (Epo) circulates in plasma and controls the oxygen carrying capacity of the blood (Fisher. Exp Biol Med (Maywood) 228:1-14, 2003). Epo is produced primarily in the adult kidney and fetal liver and was originally believed to play a role restricted to stimulation of early erythroid precursor proliferation, inhibition of apoptosis, and differentiation of the erythroid lineage. Early studies showed that mice with targeted deletion of Epo or the Epo receptor (EpoR) show impaired erythropoiesis, lack mature erythrocytes, and die in utero around embryonic day 13.5 (Wu et al. Cell 83:59-67, 1995; Lin et al. Genes Dev. 10:154-164, 1996). These animals also exhibited heart defects, abnormal vascular development as well as increased apoptosis in the brain suggesting additional functions for Epo signaling in normal development of the central nervous system and heart. Now, in addition to its well-known role in erythropoiesis, a diverse array of cells have been identified that produce Epo and/or express the Epo-R including endothelial cells, smooth muscle cells, and cells of the central nervous system (Masuda et al. J Biol Chem. 269:19488-19493, 1994; Marti et al. Eur J Neurosci. 8:666-676, 1996; Bernaudin et al. J Cereb Blood Flow Metab. 19:643-651, 1999; Li et al. Neurochem Res. 32:2132-2141, 2007). Endogenously produced Epo and/or expression of the EpoR gives rise to autocrine and paracrine signaling in different organs particularly during hypoxia, toxicity, and injury conditions. Epo has been shown to regulate a variety of cell functions such as calcium flux (Korbel et al. J Comp Physiol B. 174:121-128, 2004) neurotransmitter synthesis and cell survival (Velly et al. Pharmacol Ther. 128:445-459, 2010; Vogel et al. Blood. 102:2278-2284, 2003). Furthermore Epo has neurotrophic effects (Grimm et al. Nat Med. 8:718-724, 2002; Junk et al. Proc Natl Acad Sci U S A. 99:10659-10664, 2002), can induce an angiogenic phenotype in cultured endothelial cells and is a potent angiogenic factor in vivo (Ribatti et al. Eur J Clin Invest. 33:891-896, 2003) and might enhance ventilation in hypoxic conditions (Soliz et al. J Physiol. 568:559-571, 2005; Soliz et al. J Physiol. 583, 329-336, 2007). Thus multiple functions have been identified breathing new life and exciting possibilities into what is really an old growth factor.This review will address the function of Epo in non-hematopoietic tissues with significant emphasis on the brain and heart.
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Affiliation(s)
- Omolara O Ogunshola
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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Jacobs RA, Lundby C, Robach P, Gassmann M. Red blood cell volume and the capacity for exercise at moderate to high altitude. Sports Med 2012; 42:643-63. [PMID: 22741918 DOI: 10.1007/bf03262286] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hypoxia-stimulated erythropoiesis, such as that observed when red blood cell volume (RCV) increases in response to high-altitude exposure, is well understood while the physiological importance is not. Maximal exercise tests are often performed in hypoxic conditions following some form of RCV manipulation in an attempt to elucidate oxygen transport limitations at moderate to high altitudes. Such attempts, however, have not made clear the extent to which RCV is of benefit to exercise at such elevations. Changes in RCV at sea level clearly have a direct influence on maximal exercise capacity. Nonetheless, at elevations above 3000 m, the evidence is not that clear. Certain studies demonstrate either a direct benefit or decrement to exercise capacity in response to an increase or decrease, respectively, in RCV whereas other studies report negligible effects of RCV manipulation on exercise capacity. Adding to the uncertainty regarding the importance of RCV at high altitude is the observation that Andean and Tibetan high-altitude natives exhibit similar exercise capacities at high altitude (3900 m) even though Andean natives often present with a higher percent haematocrit (Hct) when compared with both lowland natives and Tibetans. The current review summarizes past literature that has examined the effect of RCV changes on maximal exercise capacity at moderate to high altitudes, and discusses the explanation elucidating these seemingly paradoxical observations.
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Affiliation(s)
- Robert A Jacobs
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Jacobs RA, Lundby C, Robach P, Gassmann M. Red Blood Cell Volume and the Capacity for Exercise at Moderate to High Altitude. Sports Med 2012. [DOI: 10.2165/11632440-000000000-00000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Ohata Y, Ogata S, Nakanishi K, Kanazawa F, Uenoyama M, Hiroi S, Tominaga S, Kawai T. Expression of P2X4R mRNA and protein in rats with hypobaric hypoxia-induced pulmonary hypertension. Circ J 2011; 75:945-54. [PMID: 21378451 DOI: 10.1253/circj.cj-09-0575] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The experimental pulmonary hypertension that develops in hypobaric hypoxia is characterized by structural remodeling of the heart. The P2X4 receptor (P2X4R) controls vascular tone and vessel remodeling in several blood vessels, and it has emerged as a key factor in the enhancement of cardiovascular performance. METHODS AND RESULTS To study the possible effects of hypobaric hypoxia on the P2X4R-synthesis system, 150 male Wistar rats were housed in a chamber at the equivalent of the 5,500 m altitude level for 21 days. After 14 days' exposure to hypobaric hypoxia, pulmonary arterial pressure (PAP) was significantly increased. In the right ventricle (RV) of the heart, P2X4R expression was significantly increased on days 1 and 14 (mRNA) and on days 7 and 21 (protein) of hypobaric hypoxic exposure. Immunohistochemical staining for P2X4R protein became more intense in RV in the late phase of exposure. These changes in P2X4R synthesis in RV occurred alongside the increase in PAP. In addition, P2X1R and P2Y2R mRNA levels in the RV were significantly increased on days 1, 14, and 21, and day 5, respectively, of exposure. The level of P2X1R protein in the RV was significantly increased on day 21 of exposure. CONCLUSIONS Conceivably, P2 receptors, including P2X4R and P2X1R, might play roles in modulating the RV hypertrophy that occurs due to pulmonary hypertension in hypobaric hypoxia.
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Affiliation(s)
- Yuichiro Ohata
- Department of Pathology and Laboratory Medicine, National Defense Medical College, Tokorozawa, Japan
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Astrocytes and pericytes differentially modulate blood-brain barrier characteristics during development and hypoxic insult. J Cereb Blood Flow Metab 2011; 31:693-705. [PMID: 20827262 PMCID: PMC3049523 DOI: 10.1038/jcbfm.2010.148] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Understanding regulation of blood-brain barrier (BBB) is crucial to reduce/prevent its disruption during injury. As high brain complexity makes interpretation of in vivo data challenging, BBB studies are frequently performed using simplified in vitro models. However, many models fail to address the three-dimensional (3D) cellular interactions that occur in vivo, an important feature that may explain discrepancies in translation of in vitro data to the in vivo situation. We have designed and characterized an innovative 3D model that reproduces morphological and functional characteristics of the BBB in vivo and used it to investigate cellular interactions and contribution of astrocytes and pericytes to BBB development. Our model shows that both astrocytes and pericytes significantly suppress endothelial proliferation. In contrast, differential effects on tubulogenesis were observed with astrocytes reducing the number of tubes formed but increasing diameters and length, whereas pericytes had the opposite effect. Pericytes also induce proper localization of barrier proteins, lumen polarization, and functional activity of ATP-binding cassette (ABC) transporters similar to astrocytes, but the presence of both cells is required to maintain optimal barrier characteristics during hypoxic exposure. This model is simple, dynamic, and convenient to study many aspects of BBB function and represents an exciting new tool to address open questions of BBB regulation.
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Trollmann R, Rehrauer H, Schneider C, Krischke G, Huemmler N, Keller S, Rascher W, Gassmann M. Late-gestational systemic hypoxia leads to a similar early gene response in mouse placenta and developing brain. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1489-99. [DOI: 10.1152/ajpregu.00697.2009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Late-gestational intrauterine hypoxia represents a well-known risk factor of acquired perinatal brain injury. Cell type and age-specific sensitivity of hypoxia-responsive genes to low-oxygen partial pressure is to be considered in the screening for early indicators of fetoplacental tissue hypoxia. To identify early hypoxia-induced alterations in gene expression during late-gestational hypoxia (6% O2, 6 h; gestational day 20) we compared primary mouse placenta and brain transcriptomes using high-density oligonucleotide microarrays. Upregulation of candidate marker genes for hypoxia was confirmed by quantitative RT-PCR and immunohistochemistry. Both developing brain and placenta were highly responsive to systemic hypoxia at the level of gene expression involving hypoxia-inducible transcription factor (HIF)-dependent genes and immediate early genes (IEG) (Fos, Jun, Egr1, Bhlhb2), apoptosis-promoting factors (Bnip3, Dusp1, Ier3) that were all upregulated, and genes modulating RNA binding and translation (Rbm3, Thap2, Lig4, Rbm12b) that mainly were downregulated. Functional activity of the HIF system was obvious from elevated expression of various known HIF target genes (Adm, Vegf, Hk2, Pdk1, Bnip3, Ier3, Dusp-1), indicating immediate availability among early response to acute hypoxia. In addition, genes not yet described as being hypoxia related were identified that are involved in angiogenesis/cell differentiation (Gna13, Gab2), mRNA processing, and embryonic development. RT-PCR of placenta and brain tissues confirmed upregulation of selected HIF target genes and IEG. These data indicate that the early hypoxia-induced genomic response of the placenta mirrors that of developing brain in a temporally parallel manner. Our observations implicate future diagnostic options to identify fetal and cerebral tissue hypoxia.
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Affiliation(s)
- Regina Trollmann
- Department of Pediatrics, University of Erlangen, Erlangen, Germany; and
- Institute of Veterinary Physiology and Zurich Center for Integrative Human Physiology and
| | - Hubert Rehrauer
- Functional Genomics Center Zurich, University of Zurich, Zurich, Switzerland
| | | | - Gudrun Krischke
- Department of Pediatrics, University of Erlangen, Erlangen, Germany; and
| | - Nicolas Huemmler
- Department of Pediatrics, University of Erlangen, Erlangen, Germany; and
| | - Stephan Keller
- Institute of Veterinary Physiology and Zurich Center for Integrative Human Physiology and
| | - Wolfgang Rascher
- Department of Pediatrics, University of Erlangen, Erlangen, Germany; and
| | - Max Gassmann
- Institute of Veterinary Physiology and Zurich Center for Integrative Human Physiology and
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Ikeda Y, Taveira-DaSilva AM, Pacheco-Rodriguez G, Steagall WK, El-Chemaly S, Gochuico BR, May RM, Hathaway OM, Li S, Wang JA, Darling TN, Stylianou M, Moss J. Erythropoietin-driven proliferation of cells with mutations in the tumor suppressor gene TSC2. Am J Physiol Lung Cell Mol Physiol 2010; 300:L64-72. [PMID: 21036916 DOI: 10.1152/ajplung.00095.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is characterized by cystic lung destruction, resulting from proliferation of smooth-muscle-like cells, which have mutations in the tumor suppressor genes TSC1 or TSC2. Among 277 LAM patients, severe disease was associated with hypoxia and elevated red blood cell indexes that accompanied reduced pulmonary function. Because high red cell indexes could result from hypoxemia-induced erythropoietin (EPO) production, and EPO is a smooth muscle cell mitogen, we investigated effects of EPO in human cells with genetic loss of tuberin function, and we found that EPO increased proliferation of human TSC2-/-, but not of TSC2+/-, cells. A discrete population of cells grown from explanted lungs was characterized by the presence of EPO receptor and loss of heterozygosity for TSC2, consistent with EPO involvement. In LAM cells from lung nodules, EPO was localized to the extracellular matrix, supporting evidence for activation of an EPO-driven signaling pathway. Although the high red cell mass of LAM patients could be related to advanced disease, we propose that EPO, synthesized in response to episodic hypoxia, may increase disease progression by enhancing the proliferation of LAM cells.
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Affiliation(s)
- Yoshihiko Ikeda
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1590, USA
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Antoniou X, Gassmann M, Ogunshola OO. Cdk5 interacts with Hif-1α in neurons: a new hypoxic signalling mechanism? Brain Res 2010; 1381:1-10. [PMID: 20977891 DOI: 10.1016/j.brainres.2010.10.071] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 10/15/2010] [Accepted: 10/19/2010] [Indexed: 02/07/2023]
Abstract
The cyclin dependent kinase 5 (Cdk5)/p35 complex is essential for regulation of cell survival during development and in models of neuronal excitotoxicity. Dysregulation of Cdk5, by cleavage of its neuronal specific activators p35 and p39, has been implicated in various neurodegenerative disorders such as Alzheimer's disease, however targets of the complex that regulate neuronal survival physiologically and/or during pathogenesis are largely unknown. Since hypoxia is a key feature in the pathogenesis of several neuronal disorders we investigated a role for Cdk5/p35 in the neuronal hypoxic response. Our data show that hypoxia modulates the p35/Cdk5 complex in primary cortical neurons at the transcriptional and protein level. Furthermore hypoxic induction of Cdk5 activity correlates with Hif-1α stabilisation, and direct interaction between these proteins can occur. Importantly, we demonstrate that Cdk5-mediated signaling is involved in Hif-1α stabilisation since inhibition of Cdk5 by roscovitine abrogates Hif-1α accumulation and induces cell death. Taken together our results show that the Cdk5/p35 complex may significantly contribute to modulation of Hif-1α stabilisation and impact neuronal survival during oxygen deprivation. Thus this study highlights a new hypoxia-mediated signaling pathway and implicates the cytoskeleton as a potential regulator of Hif-1α.
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Affiliation(s)
- Xanthi Antoniou
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Jiang YF, Chou CH, Lin EC, Chiu CH. Molecular characterization of hypoxia and hypoxia-inducible factor 1 alpha (HIF-1α) from Taiwan voles (Microtus kikuchii). Comp Biochem Physiol A Mol Integr Physiol 2010; 158:183-8. [PMID: 20937407 DOI: 10.1016/j.cbpa.2010.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/04/2010] [Accepted: 10/04/2010] [Indexed: 11/17/2022]
Abstract
Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that senses and adapts cells to hypoxic environmental conditions. HIF-1 is composed of an oxygen-regulated α subunit (HIF-1α) and a constitutively expressed β subunit (HIF-1β). Taiwan voles (Microtus kikuchii) are an endemic species in Taiwan, found only in mountainous areas greater than 2000m above sea level. In this study, the full-length HIF-1α cDNA was cloned and sequenced from liver tissues of Taiwan voles. We found that HIF-1α of Taiwan voles had high sequence similarity to HIF-1α of other species. Sequence alignment of HIF-1α functional domains indicated basic helix-loop-helix (bHLH), PER-ARNT-SIM (PAS) and C-terminal transactivation (TAD-C) domains were conserved among species, but sequence variations were found between the oxygen-dependent degradation domains (ODDD). To measure Taiwan vole HIF-1α responses to hypoxia, animals were challenged with cobalt chloride, and HIF-1α mRNA and protein expression in brain, lung, heart, liver, kidney, and muscle was assessed by quantitative RT-PCR and Western blot analysis. Upon induction of hypoxic stress with cobalt chloride, an increase in HIF-1α mRNA levels was detected in lung, heart, kidney, and muscle tissue. In contrast, protein expression levels showed greater variation between individual animals. These results suggest that the regulation of HIF-1α may be important to the Taiwan vole under cobalt chloride treatments. But more details regarding the evolutionary effect of environmental pressure on HIF-1α primary sequence, HIF-1α function and regulation in Taiwan voles remain to be identified.
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Affiliation(s)
- Yi-Fan Jiang
- Department of Animal Science and Technology, College of Bio-Resources and Agriculture, National Taiwan University, Taipei 10617, Taiwan
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Bigham A, Bauchet M, Pinto D, Mao X, Akey JM, Mei R, Scherer SW, Julian CG, Wilson MJ, López Herráez D, Brutsaert T, Parra EJ, Moore LG, Shriver MD. Identifying signatures of natural selection in Tibetan and Andean populations using dense genome scan data. PLoS Genet 2010; 6:e1001116. [PMID: 20838600 PMCID: PMC2936536 DOI: 10.1371/journal.pgen.1001116] [Citation(s) in RCA: 404] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 08/09/2010] [Indexed: 11/20/2022] Open
Abstract
High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure) exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans) separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2), shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association studies necessary to confirm the role of selection-nominated candidate genes and gene regions in adaptation to altitude.
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Affiliation(s)
- Abigail Bigham
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania, United States of America.
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Trollmann R, Strasser K, Keller S, Antoniou X, Grenacher B, Ogunshola OO, Dötsch J, Rascher W, Gassmann M. Placental HIFs as markers of cerebral hypoxic distress in fetal mice. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1973-81. [DOI: 10.1152/ajpregu.00053.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Reduced oxygen supply during the pre- and perinatal period often leads to acquired neonatal brain damage. So far, there are no reliable markers available to assess the hypoxic cerebral damage and the resulting prognosis during the immediate postnatal period. Thus we aimed to determine whether the hypoxia-inducible transcription factors (HIF-1 and HIF-2) and/or their target genes in the placenta represent reliable indicators of hypoxic distress of the developing brain during systemic hypoxia at the end of gestation. To this end, pregnant mice were exposed to systemic hypoxia (inspired O2 fraction: 6%, 6 h) at gestational day 20. This hypoxic exposure significantly increased HIF-1α and HIF-2α protein levels in brain and placental tissue. Compared with normoxic controls, an increase of HIF-1α-immunoreactive neurons and HIF-2α-positive glial cells and vascular endothelial cells was observed in hypoxic cerebral cortex and hippocampus. In placenta, HIF-1α and HIF-2α were expressed in labyrinthine layer with increased staining intensity during hypoxia compared with normoxia. Significant upregulation of VEGF mRNA and protein in brain and placenta, as well as erythropoietin protein in placenta, indicated activity of the HIF system upon fetal hypoxia. Notably, hypoxia did not affect expression of the HIF target genes inducible nitric oxide synthase and GLUT-1. Taken together, at gestational day 20, systemic hypoxia led to upregulation of HIF-α in mouse brain that was temporally paralleled in placenta, implying that α-subunits of both HIF-1 and HIF-2 are indeed early markers of hypoxic distress in vivo. If our data reflect the situation in humans, analysis of the placenta will allow early identification of the hypoxic brain distress occurring near birth.
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HIF-1alpha subunit and vasoactive HIF-1-dependent genes are involved in carbon monoxide-induced cerebral hypoxic stress response. Eur J Appl Physiol 2008; 104:95-102. [PMID: 18560881 DOI: 10.1007/s00421-008-0776-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2008] [Indexed: 01/02/2023]
Abstract
Hypoxia-inducible transcription factor-1 (HIF-1) is the most important component of cellular and molecular adaptive responses to hypoxia. We aimed to analyze effects of systemic hypoxia and CO exposure on the oxygen-regulated alpha-subunit of HIF-1 and HIF-1-dependent vasoactive target genes in rat brain. Brains of adult Sprague-Dawley rats were investigated after incubation for 3 and 12 h under normoxia, hypoxia (8% O(2)) and CO 0.1% (n = 10 per group). Upon 3 h of exposure, hypoxia and CO-induced accumulation of HIF-1alpha protein in brain homogenates assessed by Western blot analysis. In contrast to hypoxia HIF-1alpha signals decreased markedly during 12 h-exposure to CO. By immunohistochemistry, intensive HIF-1alpha-positive staining was found in neurons of the cortex and hippocampus. Cerebral expression of vasoactive target genes adrenomedullin (ADM) and vascular endothelial growth factor (VEGF) showed up-regulation during both hypoxia and CO exposure indicating functional activation of HIF-1. Hypoxia increased ADM (P < 0.05) and VEGF mRNA levels within 3 h (P < 0.01) which persisted up to 12 h of exposure (ADM, P < 0.05; VEGF, P < 0.001). Similarly, CO inhalation led to early up-regulation of VEGF (3 h: P < 0.05; 12 h: P < 0.01), but a more delayed increase of ADM mRNA levels (3 h: n.s., 12 h: P < 0.01). We suggest that CO-induced oxygen deprivation is a potent stimulus to cerebral HIF-1-regulated hypoxic stress responses even though its effects are more transient than exposure to hypoxia.
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The biochemistry of drugs and doping methods used to enhance aerobic sport performance. Essays Biochem 2008; 44:63-83. [DOI: 10.1042/bse0440063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Optimum performance in aerobic sports performance requires an efficient delivery to, and consumption of, oxygen by the exercising muscle. It is probable that maximal oxygen uptake in the athlete is multifactorial, being shared between cardiac output, blood oxygen content, muscle blood flow, oxygen diffusion from the blood to the cell and mitochondrial content. Of these, raising the blood oxygen content by raising the haematocrit is the simplest acute method to increase oxygen delivery and improve sport performance. Legal means of raising haematocrit include altitude training and hypoxic tents. Illegal means include blood doping and the administration of EPO (erythropoietin). The ability to make EPO by genetic means has resulted in an increase in its availability and use, although it is probable that recent testing methods may have had some impact. Less widely used illegal methods include the use of artificial blood oxygen carriers (the so-called ‘blood substitutes’). In principle these molecules could enhance aerobic sports performance; however, they would be readily detectable in urine and blood tests. An alternative to increasing the blood oxygen content is to increase the amount of oxygen that haemoglobin can deliver. It is possible to do this by using compounds that right-shift the haemoglobin dissociation curve (e.g. RSR13). There is a compromise between improving oxygen delivery at the muscle and losing oxygen uptake at the lung and it is unclear whether these reagents would enhance the performance of elite athletes. However, given the proven success of blood doping and EPO, attempts to manipulate these pathways are likely to lead to an ongoing battle between the athlete and the drug testers.
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Kasiganesan H, Sridharan V, Wright G. Prolyl hydroxylase inhibitor treatment confers whole-animal hypoxia tolerance. Acta Physiol (Oxf) 2007; 190:163-9. [PMID: 17394573 DOI: 10.1111/j.1748-1716.2007.01676.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM Recently a family of O(2)-dependent prolyl hydroxylase domain-containing enzymes (PHD) has been identified as a cellular oxygen-sensing mechanism. Reduced prolyl hydroxylase activity initiates a signalling cascade that includes the accumulation, as well as the activation, of hypoxia-inducible factor (HIF-1alpha). In turn the transcription factor HIF-1alpha, and other targets of the PHD, elicit a myriad of incompletely understood cellular responses. In these studies we have tested: (1) whether a small-molecule prolyl hydroxylase inhibitor (PHI) can effectively activate the oxygen-sensing pathway when administered systemically to mice, and (2) whether the activation of the PHD signalling pathway at the cellular level results in whole-animal hypoxic tolerance. METHODS Mice received daily injections of the PHI, ethyl-3,4 dihydroxybenzoate (EDHB, 100-250 mg kg(-1)) or vehicle. Tissue levels of HIF-1alpha and the serum levels of the HIF-inducible gene, erythropoietin (EPO), were measured to evaluate PHD-pathway activation. To evaluate hypoxic tolerance, the endurance and survival ability of these animals was tested in sublethal (8% O(2)) and lethal hypoxia (5% O(2)) respectively. RESULTS Systemic treatment of mice with the PHD inhibitor, EDHB, leads to elevated levels of HIF-1alpha in liver and HIF-inducible EPO in serum, indicating activation of the cellular oxygen-sensing pathway. Animals treated with EDHB display significantly increased viability and enhanced exercise performance in hypoxia. CONCLUSION These results demonstrate a novel pharmacological strategy to induce hypoxic tolerance and are the first to demonstrate that the activation of the PHD oxygen-sensing pathway at the cellular level is sufficient to produce a hypoxic-tolerant phenotype at the physiological level of the whole animal.
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Affiliation(s)
- H Kasiganesan
- Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
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Sommer AM, Bogusch C, Lerchl A. Cognitive function in outbred house mice after 22 weeks of drinking oxygenated water. Physiol Behav 2007; 91:173-9. [PMID: 17400260 DOI: 10.1016/j.physbeh.2007.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2006] [Revised: 02/14/2007] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
Oxygen-enriched drinking water, which is increasingly sold worldwide, is claimed to "keep both the body and the mind healthy." However, currently there is no scientific evidence for such a statement. Therefore, we assessed the effect of 22 weeks of drinking oxygenated water on cognitive performance in healthy mice, using a spatial learning task and behavioral observations. Thirty-six female mice (age 3 to 6 months) received either hyperoxic or normal tap water (approximately 6.6 vs. 1.8 microg O(2) g(-1) day(-1), respectively) throughout the study period. Mice were weighed one to two times per month, and a blood sample was taken from the tail to determine the hematocrit. In addition, red blood cells were counted microscopically one and two months after the start of the experiment. Four weeks after the last blood sample (21 weeks after the start of the experiment), exploration behavior and locomotor activity were observed on a holeboard, and learning ability tests were performed using an elevated open maze. No significant differences were seen between groups for any of the parameters investigated. Thus, the study does not support the hypothesis that drinking oxygenated water improves cognitive function or hematological parameters in mice.
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Affiliation(s)
- Angela M Sommer
- School of Engineering and Science, Jacobs University Bremen, D-28759 Bremen, Germany
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Däpp C, Gassmann M, Hoppeler H, Flück M. Hypoxia-induced gene activity in disused oxidative muscle. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 588:171-88. [PMID: 17089889 DOI: 10.1007/978-0-387-34817-9_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Hypoxia is an important modulator of the skeletal muscle's oxidative phenotype. However, little is known regarding the molecular circuitry underlying the muscular hypoxia response and the interaction of hypoxia with other stimuli of muscle oxidative capacity. We hypothesized that exposure of mice to severe hypoxia would promote the expression of genes involved in capillary morphogenesis and glucose over fatty acid metabolism in active or disused soleus muscle of mice. Specifically, we tested whether the hypoxic response depends on oxygen sensing via the alpha-subunit of hypoxia-inducible factor-1 (HIF-1 alpha). Spontaneously active wildtype and HIF-1 alpha heterozygous deficient adult female C57B1/6 mice were subjected to hypoxia (PiO2 70 mmHg). In addition, animals were subjected to hypoxia after 7 days of muscle disuse provoked by hindlimb suspension. Soleus muscles were rapidly isolated and analyzed for transcript level alterations with custom-designed AtlasTM cDNA expression arrays (BD Biosciences) and cluster analysis of differentially expressed mRNAs. Multiple mRNA elevations of factors involved in dissolution and stabilization of blood vessels, glycolysis, and mitochondrial respiration were evident after 24 hours of hypoxia in soleus muscle. In parallel transcripts of fat metabolism were reduced. A comparable hypoxia-induced expression pattern involving complex alterations of the IGF-I axis was observed in reloaded muscle after disuse. This hypoxia response in spontaneously active animals was blunted in the HIF-1 alpha heterozygous deficient mice demonstrating 35% lower HIF-1 alpha mRNA levels. Our molecular observations support the concept that severe hypoxia provides HIF-1-dependent signals for remodeling of existing blood vessels, a shift towards glycolytic metabolism and altered myogenic regulation in oxidative mouse muscle and which is amplified by enhanced muscle use. These findings further imply differential mitochondrial turnover and a negative role of HIF-1 alpha for control of fatty acid oxidation in skeletal muscle exposed to one day of severe hypoxia.
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Rodway GW, Sethi JM, Hoffman LA, Conley YP, Choi AMK, Sereika SM, Zullo TG, Ryter SW, Sanders MH. Hemodynamic and molecular response to intermittent hypoxia (IH) versus continuous hypoxia (CH) in normal humans. Transl Res 2007; 149:76-84. [PMID: 17240318 DOI: 10.1016/j.trsl.2006.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 09/08/2006] [Accepted: 09/27/2006] [Indexed: 12/21/2022]
Abstract
The hemodynamic response to hypoxia may be influenced by exposure pattern and inducible biological signals, such as nitric oxide synthase (iNOS) expression. The systemic blood pressure (BP) and heart rate (HR) response to intermittent and continuous hypoxia (IH and CH) were examined as was the relationship between these responses and iNOS expression in 10 normal subjects. BP and HR were recorded during exposure to IH or CH (total hypoxic time=60 min/dayx3 days for each exposure profile), whereas arterial oxygen saturation (SpO2) was maintained at 80-90%. Total RNA was isolated from peripheral blood lymphocytes before exposure on Day 1 and 2 hours after the last exposure on Day 3, and it was assayed for iNOS messenger RNA (mRNA) expression using quantitative polymerase chain reaction (PCR). HR, systolic BP (SBP), and diastolic BP (DBP) increased during both experimental conditions (P<0.05), with no difference by exposure pattern or evidence of facilitation over 3 days. No significant change occurred in iNOS mRNA during IH or CH when pre- and post-exposure values were compared. However, iNOS expression at the end of Day 3 was negatively correlated with the average end-exposure DBP (r=-0.79) and mean BP (MBP; r=-0.76) on Days 1-3 of the IH (P<0.05), but not CH exposure. It is concluded that both IH and CH are associated with significant but comparable hemodynamic changes. The negative correlation between BP and iNOS mRNA with IH, but not CH, may suggest differential modulation of the hemodynamic response to the 2 exposure patterns.
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Affiliation(s)
- George W Rodway
- University of Pittsburgh Division of Pulmonary Allergy and Critical Care Medicine, University of Pittsburgh School of Nursing [corrected] USA.
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Van Patot MCT, Hill AE, Dingmann C, Gaul L, Fralick K, Christians U, Honigman B, Salman MD. Risk of Impaired Coagulation in Warfarin Patients Ascending to Altitude (>2400 m). High Alt Med Biol 2006; 7:39-46. [PMID: 16544965 DOI: 10.1089/ham.2006.7.39] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Approximately 476,000 people on warfarin therapy visit a resort at altitude (>2400 m) annually in Colorado. Clinicians practicing at altitude have expressed concern that ascent to altitude adversely affects coagulation in patients taking warfarin in both high altitude residents and visitors. We sought to determine the effect of ascent to and descent from altitude on coagulation in warfarin patients, as assessed by the international normalized ratio (INR). A retrospective medical chart review was conducted on all warfarin patients treated between August 1998 and October 2003 at a cardiology clinic in which travel to and from altitude was documented in association with each INR measurement in high altitude residents. Of the 1139 INR measurements in 49 patients, 143 were associated with changes in altitude (in 32 of 49 patients). The odds of an INR measurement being below the prescribed range were 2.7 times (95% CI: 1.2-5.8) higher among warfarin patients with recent ascent to altitude, 2.1 times (95% CI: 1.4-3.2) higher among warfarin patients with atrial fibrillation, and 5.6 (95% CI: 2.3-13.7) times higher among warfarin patients with both atrial fibrillation and recent ascent to altitude. Increasing altitude is a risk factor for subtherapeutic INR in warfarin patients and this risk is doubled in atrial fibrillation patients.
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Affiliation(s)
- Martha C Tissot Van Patot
- Department of Anesthesiology, University of Colorado Denver Health Sciences Center, Denver, Colorado, USA.
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Storey KB. Genomic and Proteomic Approaches in Comparative Biochemistry and Physiology. Physiol Biochem Zool 2006; 79:324-32. [PMID: 16555191 DOI: 10.1086/499985] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2005] [Indexed: 11/03/2022]
Abstract
Emerging technologies in genomics (e.g., cDNA library screening, DNA arrays), proteomics (e.g., two-dimensional gel electrophoresis and mass-spectroscopy fingerprinting), and metabolic regulation (e.g., elucidating protein-protein binding associations or signal transduction pathways) offer powerful tools for comparative biochemistry that will greatly increase our understanding of how animals adapt to environmental stress. The power of these new technologies and their potential application for physiological and ecophysiological research are illustrated with examples of recent advances in key fields. These include hypoxia/anoxia-responsive gene expression, the actions and regulation of the hypoxia-inducible transcription factor, the central role of the AMP-dependent kinase in mediating cellular responses to changing energy status, mammalian target of rapamycin mediation of nutrient signals in the control of protein synthesis and growth, proteomics approaches to identifying the physiological substrates of protein kinases, and the interactions of biochemistry and physiology in determining a net organismal response to high hematocrit values stimulated by erythropoietin. In particular, gene- and protein-screening technologies will drive a fundamental shift in the way that environmental stress effects on metabolism are evaluated by providing a holistic overview of the responses of a huge range of cell functions to stress and allowing researchers to identify multiple new areas of metabolic response that contribute to biochemical and physiological adaptation.
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Affiliation(s)
- Kenneth B Storey
- Institute of Biochemistry, College of Natural Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
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Grimm C, Wenzel A, Acar N, Keller S, Seeliger M, Gassmann M. Hypoxic Preconditioning and Erythropoietin Protect Retinal Neurons from Degeneration. HYPOXIA AND EXERCISE 2006; 588:119-31. [PMID: 17089884 DOI: 10.1007/978-0-387-34817-9_11] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Reduced tissue oxygenation stabilizes the alpha-subunit of the transcription factor hypoxia-inducible factor-1 (HIF-1). This leads to the induction of a number of hypoxia responsive genes. One of the best known HIF-1 targets is erythropoietin that exerts neuroprotective effects on ischemia-related injury in the brain. Thus, pre-exposure to low environmental oxygen concentrations might be exploited as a preconditioning procedure to protect tissues against a variety of harmful conditions. We present recent work on neuroprotection of retinal photoreceptors induced by hypoxic preconditioning or by systemically elevated levels of Epo in mouse plasma.
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Affiliation(s)
- Christian Grimm
- Laboratory of Retinal Cell Biology, Eye Hospital Zurich and Center for Integrative Human Physiology, Zurich, Switzerland
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Abstract
The conditions of the cellular microenvironment in complex multicellular organisms fluctuate, enforcing permanent adaptation of cells at multiple regulatory levels. Covalent post-translational modifications of proteins provide the short-term response tools for cellular adjustment and growing evidence supports the possibility that protein tyrosine nitration is part of this cellular toolkit and not just a marker for oxidative damage. We have demonstrated that protein tyrosine nitration fulfils the major criteria for signalling and suggest that the normally highly regulated process may lead to disease upon excessive or inappropriate nitration.
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Lundby C, Gassmann M, Pilegaard H. Regular endurance training reduces the exercise induced HIF-1alpha and HIF-2alpha mRNA expression in human skeletal muscle in normoxic conditions. Eur J Appl Physiol 2005; 96:363-9. [PMID: 16284786 DOI: 10.1007/s00421-005-0085-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2005] [Indexed: 12/26/2022]
Abstract
Regular exercise induces a variety of adaptive responses that enhance the oxidative and metabolic capacity of human skeletal muscle. Although the physiological adjustments of regular exercise have been known for decades, the underlying mechanisms are still unclear. The hypoxia inducible factors 1 and 2 (HIFs) are clearly related heterodimeric transcription factors that consist of an oxygen-depended alpha-subunit and a constitutive beta-subunit. With hypoxic exposure, HIF-1alpha and HIF-2alpha protein are stabilized. Upon heterodimerization, HIFs induce the transcription of a variety of genes including erythropoietin (EPO), transferrin and its receptor, as well as vascular endothelial growth factor (VEGF) and its receptor. Considering that several of these genes are also induced with exercise, we tested the hypothesis that the mRNA level of HIF-1alpha and HIF-2alpha subunits increases with a single exercise bout, and that this response is blunted with training. We obtained muscle biopsies from a trained (5 days/week during 4 weeks) and untrained leg from the same human subject before, immediately after, and during the recovery from a 3 h two-legged knee extensor exercise bout, where the two legs exercised at the same absolute workload. In the untrained leg, the exercise bout induced an increase (P<0.05) in HIF-1alpha fold and HIF-2alpha fold mRNA at 6 h of recovery. In contrast, HIF-1alpha and HIF-2alpha mRNA levels were not altered at any time point in the trained leg. Obviously, HIF-1alpha and HIF-2alpha mRNA levels are transiently increased in untrained human skeletal muscle in response to an acute exercise bout, but this response is blunted after exercise training. We propose that HIFs expression is upregulated with exercise and that it may be an important transcription factor that regulates adaptive gene responses to exercise.
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Haddad JJ, Harb HL. Cytokines and the regulation of hypoxia-inducible factor (HIF)-1alpha. Int Immunopharmacol 2005; 5:461-83. [PMID: 15683844 DOI: 10.1016/j.intimp.2004.11.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 09/27/2004] [Accepted: 11/11/2004] [Indexed: 01/25/2023]
Abstract
Hypoxia-inducible factor (HIF)--an oxygen sensor? The HIF-oxygen sensing association type of dogma is, unequivocally, well anchored. But this is only one face of, at least, a double-sided coin. Current concepts charge HIF of taking sides with a yet not well-founded identity--an immunologic sensor and/or regulator. Or, is it really a sensor, put it more correctly, a key player in sensing mechanisms? The evolving association between HIF and immunity emanates from an established linkage that bonds oxidative stress and inflammation--notably the 'biologic response modifiers', or cytokines. HIF is a redox(y)-sensitive transcription factor, and so are cytokines. Recently, cytokines emerged as major regulators of HIF, under physiologic conditions extending the realm of hypoxia. Alternatively, can HIF, like the so infamous inflammatory transcription factor NF-(kappa)B, prove itself as a key player in the regulation of cytokines and, subsequently, the inflammatory process. The targeting of HIF would be, at least theoretically, of therapeutic value, but does it make sense given its intricate role in hypoxia signaling? It is the theme of HIF being an immunologic sensor that will be explored therein--with special emphasis on the regulatory role of cytokines.
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Affiliation(s)
- John J Haddad
- Department of Biology and Biomedical Sciences [corrected] Faculty of Arts and Sciences, Lebanese International University [corrected] Beirut, Lebanon.
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Morin P, Storey KB. Cloning and expression of hypoxia-inducible factor 1α from the hibernating ground squirrel, Spermophilus tridecemlineatus. ACTA ACUST UNITED AC 2005; 1729:32-40. [PMID: 15811624 DOI: 10.1016/j.bbaexp.2005.02.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 02/27/2005] [Accepted: 02/28/2005] [Indexed: 10/25/2022]
Abstract
Mammalian hibernation is associated with apnoic breathing patterns and a hypoxia-hypothermia connection has been suggested as part of the mechanism by which body temperature is reduced as animals enter torpor. Hence, we hypothesized that changes in the expression of the hypoxia inducible factor (HIF-1) may potentially be involved in regulating hibernation-responsive gene targets. The expression of the alpha subunit of HIF-1 was quantified at both gene and protein levels in four organs of the thirteen-lined ground squirrel, Spermophilus tridecemlineatus. Reverse transcription-PCR showed no change in hif-1alpha transcript levels in the liver, lung, skeletal muscle or brown adipose tissue of euthermic versus hibernating animals but HIF-1alpha protein levels were elevated by 60-70% in the two organs responsive for thermogenesis (brown adipose and skeletal muscle). Furthermore, assessment of DNA binding by HIF-1 in nuclear extracts from brown adipose revealed 6-fold higher levels in hibernator tissue than in euthermic controls suggesting increased expression of HIF-1 responsive genes during hibernation. The complete nucleotide sequence of hif-1alpha from ground squirrels, the first hif-1alpha sequence amplified from a hibernating mammal, was obtained using PCR amplification and 3' and 5' RACE. Amino acid sequence analysis revealed 90-95% identity with the HIF-1alpha protein from other mammals. Several unique amino acid sequence substitutions were identified that may affect protein conformation and could possibly function to counteract low temperature effects on HIF-1alpha conformation at near 0 degrees C body temperatures during torpor.
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Affiliation(s)
- Pier Morin
- Institute of Biochemistry and Department of Chemistry, College of Natural Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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Buehler PW, Alayash AI. Oxygen sensing in the circulation: "cross talk" between red blood cells and the vasculature. Antioxid Redox Signal 2004; 6:1000-10. [PMID: 15548897 DOI: 10.1089/ars.2004.6.1000] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Oxygen (O(2)) sensing in blood and regulation of microvascular tone appear to involve hemoglobin (Hb) conformational changes resulting from O(2) desaturation. This observation has prompted the thought that Hb functions as both an O(2) sensor and regulator of microvasular blood flow to meet local tissue oxygen demand. The mechanism(s) by which this is accomplished has recently been the subject of increasing debate. Three primary hypotheses are described within the literature and include release of adenosine 5'-triphosphate by red blood cells (RBCs), release of S-nitrosylated molecules from RBCs originally bound to beta93 cysteine residues of oxyHb, and nitrite conversion and storage of nitric oxide by Hb at the site of ferric (Fe(3+)) and ferrous (Fe(2+)) Hb. Within extravascular cells, the global regulator of oxygen homeostasis is hypoxia-inducible factor-1 (HIF- 1). This transcriptional factor is tightly regulated by O(2) and cellular redox-sensitive mechanisms. HIF-1 activation is responsible for the up-regulation of proteins, which increase O(2) supply. We believe that there are important and yet unexplored mechanisms by which RBCs can directly or indirectly communicate via redox intermediates with extravascular sites as part of the global O(2) sensing mechanism.
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Affiliation(s)
- Paul W Buehler
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Bethesda, MD 20892, USA
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Haddad JJ, Harb HL. L-gamma-Glutamyl-L-cysteinyl-glycine (glutathione; GSH) and GSH-related enzymes in the regulation of pro- and anti-inflammatory cytokines: a signaling transcriptional scenario for redox(y) immunologic sensor(s)? Mol Immunol 2004; 42:987-1014. [PMID: 15829290 DOI: 10.1016/j.molimm.2004.09.029] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 09/29/2004] [Indexed: 12/17/2022]
Abstract
Of the antioxidant/prooxidant mechanisms mediating the regulation of inflammatory mediators, particularly cytokines, oxidative stress-related pathways remain a cornerstone. It is conspicuous that there is a strong association between free radical accumulation (ROS/RNS; oxidative stress) and the evolution of inflammation and inflammatory-related responses. The scenario that upholds a consensus on the aforementioned is still evolving to unravel, from an immunologic perspective, the molecular mechanisms associated with ROS/RNS-dependent inflammation. Cytokines are keynote players when it comes to defining an intimate relationship among reduction-oxidation (redox) signals, oxidative stress and inflammation. How close we are to identifying the molecular basis of this intricate association should be weighed against the involvement of specific signaling molecules and, potentially, transcription factors. L-gamma-Glutamyl-L-cysteinyl-glycine, or glutathione (GSH), an antioxidant thiol, has shaped, and still is refining, the face of oxidative signaling in terms of regulating the milieu of inflammatory mediators, ostensibly via the modulation (expression/repression) of oxygen- and redox-responsive transcription factors, hence termed redox(y)-sensitive cofactors. When it comes to the arena of oxygen sensing, oxidative stress and inflammation, nuclear factor-kappaB (NF-kappaB) and hypoxia-inducible factor-1alpha (HIF-1alpha) are key players that determine antioxidant/prooxidant responses with oxidative challenge. It is the theme therein to underlie current understanding of the molecular association hanging between oxidative stress and the evolution of inflammation, walked through an elaborate discussion on the role of transcription factors and cofactors. Would that classify glutathione and other redox signaling cofactors as potential anti-inflammatory molecules emphatically remains of particular interest, especially in the light of identifying upstream and downstream molecular pathways for conceiving therapeutic, alleviating strategy for oxidant-mediated, inflammatory-related disease conditions.
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Affiliation(s)
- John J Haddad
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut, Beirut, Lebanon.
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Waskow C, Terszowski G, Costa C, Gassmann M, Rodewald HR. Rescue of lethal c-KitW/W mice by erythropoietin. Blood 2004; 104:1688-95. [PMID: 15178584 DOI: 10.1182/blood-2004-04-1247] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Homozygous natural white-spotted (W) mutations in the gene encoding the receptor tyrosine kinase c-Kit are associated with hypoplastic bone marrow, severe macrocytic anemia, and lethality during early postnatal life. c-Kit(W/W) mice can be rescued by wild-type hematopoietic stem cells (HSCs), but it is not known whether the lethality of c-Kit(W/W) mice is the result of HSC failure or defects specific for erythropoiesis. Here we show that transgenic expression of erythropoietin (EPO) can overcome the lethality caused by the c-Kit(W/W) mutation. In W mutant mice rescued by EPO, termed WEPO, erythrocyte colony-forming units (CFU-Es) are rescued to normal frequencies. Hence, Epo receptor signals can partially bypass the strict requirement for c-Kit signaling in erythropoiesis in the absence of c-Kit in vivo. Using a series of W and rescue mouse strains, we define here the erythropoietic threshold permitting survival in vivo. The lethality of c-Kit(W/W) mice has precluded analysis of this crucial receptor-ligand pair in adult stem/progenitor cells. Our strategy to generate viable c-Kit(W/W) mice will be useful to analyze the role of this important receptor tyrosine kinase in adult life in vivo.
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Affiliation(s)
- Claudia Waskow
- Department for Immunology, University of Ulm, D-89081 Ulm, Germany.
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Rodway GW, Hoffman LA. Reply. Heart Lung 2004. [DOI: 10.1016/j.hrtlng.2004.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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