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Ascorbic Acid and the Premature Infant. Nutrients 2022; 14:nu14112189. [PMID: 35683989 PMCID: PMC9183051 DOI: 10.3390/nu14112189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 02/06/2023] Open
Abstract
Little information exists about the plasma target nutritional needs of the >15 million premature infants <37 weeks gestation. Investigating ascorbic acid’s (AscA) role in infant health, our study details the relationship of infant characteristics and maternal health on infant plasma AscA level (pAscA) during postnatal development. Furthermore, we determined pAscA influence during the first week of life (EpAscA) with later infant morbidities. We hypothesize that pAscA is influenced by gestational organ immaturity, as well as maternal factors, with EpAscA associated with greater morbidity risk. We conducted a prospective longitudinal observational study of pAscA, demographics and hospital course detailed in infants ≤34 weeks. Sixty-three subjects were included, with >200 urine and plasma data points analyzed. Maternal smoking, exposure to magnesium sulfate (MgSO4) and advancing gestational and postnatal age were associated with lower pAscA. Non-white infants and those ≤30 weeks that developed bronchopulmonary dysplasia or retinopathy of prematurity had lower pAscA. Prenatal smoking, MgSO4, birth gestational age and race negatively influence pAscA. These results show prenatal and postnatal developmental factors influencing initial pAscA and metabolism, potentially setting the stage for organ health and risk for disease. Assessment of dietary targets may need adjustment in this population.
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Sequeira IR. Higher doses of ascorbic acid may have the potential to promote nutrient delivery via intestinal paracellular absorption. World J Gastroenterol 2021; 27:6750-6756. [PMID: 34790005 PMCID: PMC8567472 DOI: 10.3748/wjg.v27.i40.6750] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/16/2021] [Accepted: 09/19/2021] [Indexed: 02/06/2023] Open
Abstract
The significance of plasma ascorbic acid (AA) is underscored by its enzymatic and antioxidant properties as well as involvement in many aspects of health including the synthesis of biomolecules during acute illness, trauma and chronic health conditions. Dietary intake supports maintenance of optimal levels with supplementation at higher doses more likely pursued. Transient increased intestinal paracellular permeability following high dose AA may be utilised to enhance delivery of other micronutrients across the intestinal lumen. The potential mechanism following dietary intake however needs further study but may provide an avenue to increase small intestinal nutrient co transport and absorption, including in acute and chronic illness.
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Affiliation(s)
- Ivana Roosevelt Sequeira
- Human Nutrition Unit, School of Biological Science, University of Auckland, Auckland 1024, New Zealand
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3
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Shi L, Wang Y, Ito F, Okazaki Y, Tanaka H, Mizuno M, Hori M, Richardson DR, Toyokuni S. Biphasic effects of l-ascorbate on the tumoricidal activity of non-thermal plasma against malignant mesothelioma cells. Arch Biochem Biophys 2016; 605:109-16. [DOI: 10.1016/j.abb.2016.05.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/02/2016] [Accepted: 05/20/2016] [Indexed: 12/22/2022]
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4
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SVCT2 Overexpression in Neuroblastoma Cells Induces Cellular Branching that is Associated with ERK Signaling. Mol Neurobiol 2015; 53:6668-6679. [DOI: 10.1007/s12035-015-9553-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 11/18/2015] [Indexed: 12/21/2022]
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5
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Keenan SW, Hill CA, Kandoth C, Buck LT, Warren DE. Transcriptomic Responses of the Heart and Brain to Anoxia in the Western Painted Turtle. PLoS One 2015; 10:e0131669. [PMID: 26147940 PMCID: PMC4493013 DOI: 10.1371/journal.pone.0131669] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/05/2015] [Indexed: 12/23/2022] Open
Abstract
Painted turtles are the most anoxia-tolerant tetrapods known, capable of surviving without oxygen for more than four months at 3°C and 30 hours at 20°C. To investigate the transcriptomic basis of this ability, we used RNA-seq to quantify mRNA expression in the painted turtle ventricle and telencephalon after 24 hours of anoxia at 19°C. Reads were obtained from 22,174 different genes, 13,236 of which were compared statistically between treatments for each tissue. Total tissue RNA contents decreased by 16% in telencephalon and 53% in ventricle. The telencephalon and ventricle showed ≥ 2x expression (increased expression) in 19 and 23 genes, respectively, while only four genes in ventricle showed ≤ 0.5x changes (decreased expression). When treatment effects were compared between anoxic and normoxic conditions in the two tissue types, 31 genes were increased (≥ 2x change) and 2 were decreased (≤ 0.5x change). Most of the effected genes were immediate early genes and transcription factors that regulate cellular growth and development; changes that would seem to promote transcriptional, translational, and metabolic arrest. No genes related to ion channels, synaptic transmission, cardiac contractility or excitation-contraction coupling changed. The generalized expression pattern in telencephalon and across tissues, but not in ventricle, correlated with the predicted metabolic cost of transcription, with the shortest genes and those with the fewest exons showing the largest increases in expression.
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Affiliation(s)
- Sarah W. Keenan
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Craig A. Hill
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Cyriac Kandoth
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Leslie T. Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Daniel E. Warren
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
- * E-mail:
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Sequeira IR, Kruger MC, Hurst RD, Lentle RG. Ascorbic Acid may Exacerbate Aspirin-Induced Increase in Intestinal Permeability. Basic Clin Pharmacol Toxicol 2015; 117:195-203. [PMID: 25641731 DOI: 10.1111/bcpt.12388] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/20/2015] [Indexed: 12/23/2022]
Abstract
Ascorbic acid in combination with aspirin has been used to prevent aspirin-induced oxidative GI damage. We aimed to determine whether ascorbic acid reduces or prevents aspirin-induced changes in intestinal permeability over a 6-hr period using saccharidic probes mannitol and lactulose. The effects of administration of 600 mg aspirin alone, 500 mg ascorbic acid alone and simultaneous dosage of both agents were compared in a cross-over study in 28 healthy female volunteers. These effects were also compared with that of a placebo. The ability of ascorbic acid to mitigate the effects of aspirin when administered either half an hour before or after dosage with aspirin was also assessed in 19 healthy female volunteers. The excretion of lactulose over the 6-hr period was augmented after consumption of either aspirin or ascorbic acid compared with that after consumption of placebo. Dosage with ascorbic acid alone augmented the excretion of lactulose more than did aspirin alone. Simultaneous dosage with both agents augmented the excretion of lactulose in an additive manner. The timing of dosage with ascorbic acid in relation to that with aspirin had no significant effect on the excretion of the two sugars. These findings indicate that ascorbic acid does not prevent aspirin-induced increase in gut permeability rather that both agents augment it to a similar extent. The additive effect on simultaneous dosage with both agents in augmenting the absorption of lactulose suggests that each influences paracellular permeability by different pathways.
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Affiliation(s)
- Ivana R Sequeira
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Marlena C Kruger
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Roger D Hurst
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Roger G Lentle
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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Lindblad M, Tveden-Nyborg P, Lykkesfeldt J. Regulation of vitamin C homeostasis during deficiency. Nutrients 2013; 5:2860-79. [PMID: 23892714 PMCID: PMC3775232 DOI: 10.3390/nu5082860] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/15/2013] [Accepted: 07/18/2013] [Indexed: 12/31/2022] Open
Abstract
Large cross-sectional population studies confirm that vitamin C deficiency is common in humans, affecting 5%–10% of adults in the industrialized world. Moreover, significant associations between poor vitamin C status and increased morbidity and mortality have consistently been observed. However, the absorption, distribution and elimination kinetics of vitamin C in vivo are highly complex, due to dose-dependent non-linearity, and the specific regulatory mechanisms are not fully understood. Particularly, little is known about how adaptive mechanisms during states of deficiency affect the overall regulation of vitamin C transport in the body. This review discusses mechanisms of vitamin C transport and potential means of regulation with special emphasis on capacity and functional properties, such as differences in the Km of vitamin C transporters in different target tissues, in some instances demonstrating a tissue-specific distribution.
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Affiliation(s)
- Maiken Lindblad
- Section of Experimental Animal Models, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Ridebanevej 9, Frederiksberg C 1870, Denmark.
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Chen Y, Fan JX, Zhang ZL, Wang G, Cheng X, Chuai M, Lee KKH, Yang X. The negative influence of high-glucose ambience on neurogenesis in developing quail embryos. PLoS One 2013; 8:e66646. [PMID: 23818954 PMCID: PMC3688607 DOI: 10.1371/journal.pone.0066646] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 05/08/2013] [Indexed: 12/19/2022] Open
Abstract
Gestational diabetes is defined as glucose intolerance during pregnancy and it is presented as high blood glucose levels during the onset pregnancy. This condition has an adverse impact on fetal development but the mechanism involved is still not fully understood. In this study, we investigated the effects of high glucose on the developing quail embryo, especially its impact on the development of the nervous system. We established that high glucose altered the central nervous system mophologically, such that neural tube defects (NTDs) developed. In addition, we found that high glucose impaired nerve differentiation at dorsal root ganglia and in the developing limb buds, as revealed by neurofilament (NF) immunofluorescent staining. The dorsal root ganglia are normally derived from neural crest cells (NCCs), so we examine the delamination of NCCs from dorsal side of the neural tube. We established that high glucose was detrimental to the NCCs, in vivo and in vitro. High glucose also negatively affected neural differentiation by reducing the number and length of neurites emanating from neurons in culture. We established that high glucose exposure caused an increase in reactive oxidative species (ROS) generation by primary cultured neurons. We hypothesized that excess ROS was the factor responsible for impairing neuron development and differentiation. We provided evidence for our hypothesis by showing that the addition of vitamin C (a powerful antioxidant) could rescue the damaging effects of high glucose on cultured neurons.
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Affiliation(s)
- Yao Chen
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, China
| | - Jian-xia Fan
- Department of Gynecology and Obstetrics, International Peace Maternity and Child Health Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhao-long Zhang
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, China
| | - Guang Wang
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, China
| | - Xin Cheng
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, China
| | - Manli Chuai
- Division of Cell and Developmental Biology, University of Dundee, Dundee, United Kingdom
| | - Kenneth Ka Ho Lee
- Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, Hong Kong
- * E-mail: (XY); (KKHL)
| | - Xuesong Yang
- Key Laboratory for Regenerative Medicine of the Ministry of Education, Division of Histology and Embryology, Medical College, Jinan University, Guangzhou, China
- Institute of Fetal-Preterm Labor Medicine, Jinan University, Guangzhou, China
- * E-mail: (XY); (KKHL)
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Michels AJ, Hagen TM, Frei B. Human genetic variation influences vitamin C homeostasis by altering vitamin C transport and antioxidant enzyme function. Annu Rev Nutr 2013; 33:45-70. [PMID: 23642198 DOI: 10.1146/annurev-nutr-071812-161246] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
New evidence for the regulation of vitamin C homeostasis has emerged from several studies of human genetic variation. Polymorphisms in the genes encoding sodium-dependent vitamin C transport proteins are strongly associated with plasma ascorbate levels and likely impact tissue cellular vitamin C status. Furthermore, genetic variants of proteins that suppress oxidative stress or detoxify oxidatively damaged biomolecules, i.e., haptoglobin, glutathione-S-transferases, and possibly manganese superoxide dismutase, affect ascorbate levels in the human body. There also is limited evidence for a role of glucose transport proteins. In this review, we examine the extent of the variation in these genes, their impact on vitamin C status, and their potential role in altering chronic disease risk. We conclude that future epidemiological studies should take into account genetic variation in order to successfully determine the role of vitamin C nutriture or supplementation in human vitamin C status and chronic disease risk.
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Gallie DR. L-ascorbic Acid: a multifunctional molecule supporting plant growth and development. SCIENTIFICA 2013; 2013:795964. [PMID: 24278786 PMCID: PMC3820358 DOI: 10.1155/2013/795964] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/02/2012] [Indexed: 05/19/2023]
Abstract
L-Ascorbic acid (vitamin C) is as essential to plants as it is to animals. Ascorbic acid functions as a major redox buffer and as a cofactor for enzymes involved in regulating photosynthesis, hormone biosynthesis, and regenerating other antioxidants. Ascorbic acid regulates cell division and growth and is involved in signal transduction. In contrast to the single pathway responsible for ascorbic acid biosynthesis in animals, plants use multiple pathways to synthesize ascorbic acid, perhaps reflecting the importance of this molecule to plant health. Given the importance of ascorbic acid to human nutrition, several technologies have been developed to increase the ascorbic acid content of plants through the manipulation of biosynthetic or recycling pathways. This paper provides an overview of these approaches as well as the consequences that changes in ascorbic acid content have on plant growth and function. Discussed is the capacity of plants to tolerate changes in ascorbic acid content. The many functions that ascorbic acid serves in plants, however, will require highly targeted approaches to improve their nutritional quality without compromising their health.
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Affiliation(s)
- Daniel R. Gallie
- Department of Biochemistry, University of California, Riverside, CA 92521-0129, USA
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11
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Ludke AR, Sharma AK, Akolkar G, Bajpai G, Singal PK. Downregulation of vitamin C transporter SVCT-2 in doxorubicin-induced cardiomyocyte injury. Am J Physiol Cell Physiol 2012; 303:C645-53. [DOI: 10.1152/ajpcell.00186.2012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vitamin C (Vit C) has been shown to be protective against doxorubicin (Dox)-induced cardiotoxicity. However, Vit C uptake into cardiomyocytes is poorly understood. Furthermore, whether the antioxidant enzyme reserve is enhanced by Vit C is also not known. The present study investigated an influence of Dox on Vit C transporters, expression of endogenous antioxidant reserve as well as enzymes, oxidative stress, and apoptosis in isolated cardiomyocytes. Cardiomyocytes isolated from adult Sprague-Dawley rats were exposed to control (culture medium 199 alone), Dox (10 μM), Vit C (25 μM), and Vit C + Dox for 24 h. Vit C transporter expression and localization, oxidative stress, antioxidant enzymes, and apoptosis were studied. Expression and localization of sodium-dependent vitamin C transporter-2 (SVCT-2) in the sarcolemma was reduced by Dox, but Vit C supplementation was able to blunt this change. There was a decrease in the expression of antioxidant enzymes glutathione peroxidase (GPx), catalase, and Cu/Zn superoxide dismutase (SOD) due to Dox, but only GPx expression was completely prevented and Cu/Zn SOD was partially rescued by Vit C. Dox-induced decrease in antioxidant reserve and increase in oxidative stress were partially mitigated by Vit C. Dox-induced apoptosis was ameliorated by Vit C. It is suggested that cardioprotection offered by Vit C in Dox-induced cardiomyopathy may involve an upregulation of SVCT-2 transporter followed by a reduction in oxidative stress as well as blunting of cardiomyocyte injury.
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Affiliation(s)
- Ana R. Ludke
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Anita K. Sharma
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Gauri Akolkar
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Gunjan Bajpai
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Pawan K. Singal
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
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Riganti C, Gazzano E, Polimeni M, Aldieri E, Ghigo D. The pentose phosphate pathway: an antioxidant defense and a crossroad in tumor cell fate. Free Radic Biol Med 2012; 53:421-36. [PMID: 22580150 DOI: 10.1016/j.freeradbiomed.2012.05.006] [Citation(s) in RCA: 286] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 04/14/2012] [Accepted: 05/03/2012] [Indexed: 01/10/2023]
Abstract
The pentose phosphate pathway, one of the main antioxidant cellular defense systems, has been related for a long time almost exclusively to its role as a provider of reducing power and ribose phosphate to the cell. In addition to this "traditional" correlation, in the past years multiple roles have emerged for this metabolic cascade, involving the cell cycle, apoptosis, differentiation, motility, angiogenesis, and the response to anti-tumor therapy. These findings make the pentose phosphate pathway a very interesting target in tumor cells. This review summarizes the latest discoveries relating the activity of the pentose phosphate pathway to various aspects of tumor metabolism, such as cell proliferation and death, tissue invasion, angiogenesis, and resistance to therapy, and discusses the possibility that drugs modulating the pathway could be used as potential tools in tumor therapy.
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Affiliation(s)
- Chiara Riganti
- Department of Genetics, Biology, and Biochemistry, University of Torino, Turin, Italy.
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Abstract
Vitamin C functions in enzyme activation, oxidative stress reduction, and immune function. There is considerable evidence that vitamin C protects against respiratory tract infections and reduces risk for cardiovascular disease and some cancers. Current trials are examining the efficacy of intravenous vitamin C as cancer therapy. Many experts believe that the recommended intakes for vitamin C (45 to 90 mg daily) are several orders of magnitude too low to support optimal vitamin C functionality. Also, there is a misperception that vitamin C deficiency disease (scurvy) is largely historical and rarely observed in developed nations. Physical symptoms of scurvy include swelling of the lower extremities, bleeding gums, fatigue, and hemorrhaging, as well as psychological problems, including depression, hysteria, and social introversion. The long-term safety of vitamin C supplementation seems evident as large investigations have noted reduced risk of mortality in vitamin C supplementing populations and in those with elevated plasma vitamin C concentrations.
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Gutierrez-Larrainzar M, de Castro C, del Valle P, Rúa J, García-Armesto MR, Busto F, de Arriaga D. Production, stability, and antioxidative and antimicrobial activities of two L-ascorbate analogues from phycomyces blakesleeanus: D-erythroascorbate and D-erythroascorbate glucoside. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:10631-10638. [PMID: 20815349 DOI: 10.1021/jf102202e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
D-erythroascorbate (D-EAA), a five-carbon analogue of L-ascorbate (L-AA), and D-erythroascorbate monoglucoside (D-EAAG) are accumulated in Phycomyces blakesleeanus grown on glucose (99.5 and 1084 μg/g mycelial dry weight, respectively) and also excreted into the culture medium. Both compounds showed UV spectral properties and ionization constants similar to those of L-AA. D-EAAG was much more stable to aerobic oxidation than D-EAA and L-AA at acidic pH. D-EAAG is synthesized from D-erythroascorbate by a mycelial glucosyltransferase activity that uses UDP-glucose as glucose substrate donor with K(m) = 2.5 mM and 41.3 μM for D-EAA. This glucosyltransferase activity was maximal in the stationary growth phase in parallel with maximal production of D-EAAG. The presence of D-arabinose or D-arabinono-1,4-lactone in the culture medium produces the maximal accumulation of D-EAA and D-EAAG (about 30- and 4-fold with respect to that obtained in glucose culture). Both compounds showed greater antioxidant activity than L-AA and other standard antioxidants, with a capacity similar to that of L-AA to inhibit the growth of Escherichia coli.
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Corti A, Casini AF, Pompella A. Cellular pathways for transport and efflux of ascorbate and dehydroascorbate. Arch Biochem Biophys 2010; 500:107-15. [PMID: 20494648 DOI: 10.1016/j.abb.2010.05.014] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 05/13/2010] [Accepted: 05/14/2010] [Indexed: 11/17/2022]
Abstract
The mechanisms allowing the cellular transport of ascorbic acid represent a primary aspect for the understanding of the roles played by this vitamin in pathophysiology. Considerable research effort has been spent in the field, on several animal models and different cell types. Several mechanisms have been described to date, mediating the movements of different redox forms of ascorbic acid across cell membranes. Vitamin C can enter cells both in its reduced and oxidized form, ascorbic acid (AA) and dehydroascorbate (DHA), utilizing respectively sodium-dependent transporters (SVCT) or glucose transporters (GLUT). Modulation of SVCT expression and function has been described by cytokines, steroids and post-translational protein modification. Cellular uptake of DHA is followed by its intracellular reduction to AA by several enzymatic and non-enzymatic systems. Efflux of vitamin C has been also described in a number of cell types and different pathophysiological functions were proposed for this phenomenon, in dependence of the cell model studied. Cellular efflux of AA is mediated through volume-sensitive (VSOAC) and Ca(2+)-dependent anion channels, gap-junction hemichannels, exocytosis of secretory vesicles and possibly through homo- and hetero-exchange systems at the plasma membrane level. Altogether, available data suggest that cellular efflux of ascorbic acid - besides its uptake - should be taken into account when evaluating the cellular homeostasis and functions of this important vitamin.
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Affiliation(s)
- Alessandro Corti
- Dipartimento di Patologia Sperimentale, Università di Pisa, Italy.
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Paixão TRLC, Barbosa LF, Carrì MT, Medeiros MHG, Bertotti M. Continuous monitoring of ascorbate transport through neuroblastoma cells with a ruthenium oxide hexacyanoferrate modified microelectrode. Analyst 2008; 133:1605-10. [DOI: 10.1039/b805868g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Vissers MCM, Gunningham SP, Morrison MJ, Dachs GU, Currie MJ. Modulation of hypoxia-inducible factor-1 alpha in cultured primary cells by intracellular ascorbate. Free Radic Biol Med 2007; 42:765-72. [PMID: 17320759 DOI: 10.1016/j.freeradbiomed.2006.11.023] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2006] [Revised: 10/19/2006] [Accepted: 11/25/2006] [Indexed: 11/29/2022]
Abstract
Control of the transcription factor hypoxia inducible factor (HIF)-1 is mediated by hydroxylation by proline and asparagine hydroxylases. These enzymes require ascorbate for optimal activity, but little attention has been given to the effect of ascorbate on HIF-1 activation. Furthermore, cells in culture are ascorbate deficient. We investigated the effect of intracellular ascorbate on HIF-1alpha protein levels and on HIF-1-mediated gene expression in two human primary cell lines (umbilical vein endothelial cells and skin fibroblasts) and one human cancer cell line (A431 epithelial cells). Under normal culture conditions the cells contained no ascorbate and adding ascorbate to the medium increased intracellular concentrations in a dose-dependent manner. A basal level of HIF-1alpha detected in nonsupplemented cells under normoxic conditions disappeared when 10 microM ascorbate was added to the medium. Induction of HIF-1alpha by hypoxia (1% O(2)) or by CoCl(2) was markedly inhibited by ascorbate and loading with physiological levels resulted in almost complete reversal of HIF-1alpha stabilisation. Gene expression was similarly affected, with VEGF mRNA and GLUT-1 up-regulation being inhibited by ascorbate. Hence intracellular ascorbate is a major regulator of the hypoxic response in normal cells and optimal levels of this vitamin will have a profound effect on HIF-1-regulated processes.
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Affiliation(s)
- Margret C M Vissers
- Free Radical Research Group, Pathology Department, Christchurch School of Medicine and Health Sciences, Christchurch, New Zealand.
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Karaczyn A, Ivanov S, Reynolds M, Zhitkovich A, Kasprzak KS, Salnikow K. Ascorbate depletion mediates up-regulation of hypoxia-associated proteins by cell density and nickel. J Cell Biochem 2006; 97:1025-35. [PMID: 16288478 DOI: 10.1002/jcb.20705] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Exposure of human lung cells to carcinogenic nickel compounds in the presence of oxygen up-regulated carbonic anhydrase IX (CA IX) and NDRG1/Cap43, both known as intrinsic hypoxia markers and cancer-associated genes. This suggests that factors other than a shortage of oxygen may be involved in this induction. Both proteins can also be induced in the presence of oxygen by culturing these cells to a high density without medium change. The intracellular ascorbate measurements revealed its rapid depletion in both metal- and density-exposed cells. Nickel exposure caused strong activation of HIF-1alpha and HIF-2alpha proteins, underscoring activation of HIF-1-dependent transcription. In contrast, cell density-dependent transcription was characterized by minor induction of HIF-1alpha or HIF-2alpha. Moreover, the up-regulation of NDRG1/Cap43 in HIF-1alpha deficient fibroblasts suggested the involvement of different transcription factor(s). The repletion of intracellular ascorbate reversed the induction of CA IX and NDRG1/Cap43 caused by cell density or nickel exposure. Thus, the loss of intracellular ascorbate triggered the induction of both tumor markers by two different conditions in the presence of oxygen. Ascorbate is delivered to lung cells via the SVCT2 ascorbate transporter, which was found to be sensitive to nickel or cell density. Collectively these findings establish the importance of intracellular ascorbate levels for the regulation of expression of CA IX and NDRG1/Cap43. We suggest, that, in addition to low oxygenation, insufficient supply of ascorbate or its excessive oxidation in tumors, can contribute to the induction of hypoxia-associated proteins via both HIF-dependent and independent mechanisms.
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Affiliation(s)
- Aldona Karaczyn
- Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
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Influence of different dietary vitamin C levels on vitamin E and C content and oxidative stability in various tissues and stored m. longissimus dorsi of growing pigs. Meat Sci 2006; 73:362-7. [DOI: 10.1016/j.meatsci.2005.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 12/09/2005] [Accepted: 12/18/2005] [Indexed: 02/02/2023]
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Chen H, Karne RJ, Hall G, Campia U, Panza JA, Cannon RO, Wang Y, Katz A, Levine M, Quon MJ. High-dose oral vitamin C partially replenishes vitamin C levels in patients with Type 2 diabetes and low vitamin C levels but does not improve endothelial dysfunction or insulin resistance. Am J Physiol Heart Circ Physiol 2006; 290:H137-45. [PMID: 16126809 DOI: 10.1152/ajpheart.00768.2005] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelial dysfunction is a hallmark of Type 2 diabetes related to hyperglycemia and oxidative stress. Nitric oxide-dependent vasodilator actions of insulin may augment glucose disposal. Thus endothelial dysfunction may worsen insulin resistance. Intra-arterial administration of vitamin C improves endothelial dysfunction in diabetes. In the present study, we investigated effects of high-dose oral vitamin C to alter endothelial dysfunction and insulin resistance in Type 2 diabetes. Plasma vitamin C levels in 109 diabetic subjects were lower than healthy (36 ± 2 μM) levels. Thirty-two diabetic subjects with low plasma vitamin C (<40 μM) were subsequently enrolled in a randomized, double-blind, placebo-controlled study of vitamin C (800 mg/day for 4 wk). Insulin sensitivity (determined by glucose clamp) and forearm blood flow in response to ACh, sodium nitroprusside (SNP), or insulin (determined by plethysmography) were assessed before and after 4 wk of treatment. In the placebo group ( n = 17 subjects), plasma vitamin C (22 ± 3 μM), fasting glucose (159 ± 12 mg/dl), insulin (19 ± 7 μU/ml), and SIClamp [2.06 ± 0.29 × 10−4 dl·kg−1·min−1/(μU/ml)] did not change significantly after placebo treatment. In the vitamin C group ( n = 15 subjects), basal plasma vitamin C (23 ± 2 μM) increased to 48 ± 6 μM ( P < 0.01) after treatment, but this was significantly less than that expected for healthy subjects (>80 μM). No significant changes in fasting glucose (156 ± 11 mg/dl), insulin (14 ± 2 μU/ml), SIClamp [2.71 ± 0.46 × 10−4 dl·kg−1·min−1/(μU/ml)], or forearm blood flow in response to ACh, SNP, or insulin were observed after vitamin C treatment. We conclude that high-dose oral vitamin C therapy, resulting in incomplete replenishment of vitamin C levels, is ineffective at improving endothelial dysfunction and insulin resistance in Type 2 diabetes.
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Affiliation(s)
- Hui Chen
- Diabetes Unit, National Center for Complementary and Alternative Medicine, NIH, Bldg. 10, Rm. 6C-205, 10 Center Dr. MSC 1632, Bethesda, MD 20892-1632, USA
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21
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Rubin SA, Dey S, Reidling JC. Functional analysis of two regulatory regions of the human Na+-dependent vitamin C transporter 2, SLC23A2, in human vascular smooth muscle cells. ACTA ACUST UNITED AC 2005; 1732:76-81. [PMID: 16380174 DOI: 10.1016/j.bbaexp.2005.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2005] [Revised: 11/08/2005] [Accepted: 11/09/2005] [Indexed: 11/26/2022]
Abstract
Uptake of vitamin C occurs through the Na+ -dependent vitamin C transporters (SVCT1 and 2), the products of two separate genes. In cultured human vascular smooth muscle cells (hVSMC), we found expression of only the hSVCT2 transcript and identified an additional 5'-UTR transcript variant that we termed exon 1b, in addition to the previously described exon 1a. We cloned and tested the promoter functionality of the two genomic regions of the hSVCT2 upstream of these alternative first exons in hVSMC. Both demonstrated activity, and deletion constructs demonstrated that the minimal promoter regions were within approximately 100 bp relative to their adjacent exons.
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MESH Headings
- 5' Untranslated Regions/genetics
- Base Sequence
- Caco-2 Cells
- Cells, Cultured
- Exons/genetics
- Humans
- Molecular Sequence Data
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Organic Anion Transporters, Sodium-Dependent/genetics
- Promoter Regions, Genetic/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Regulatory Sequences, Nucleic Acid/genetics
- Sodium-Coupled Vitamin C Transporters
- Symporters/genetics
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Affiliation(s)
- Stanley A Rubin
- The Greater Los Angeles Veterans Affairs Medical Center, Los Angeles, CA and the Department of Medicine, School of Medicine, University of California, 11301 Wilshire Blvd., Los Angeles, CA 99073, USA.
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22
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Humphrey BD, Klasing KC. The acute phase response alters cationic amino acid transporter expression in growing chickens (Gallus gallus domesticus). Comp Biochem Physiol A Mol Integr Physiol 2005; 142:485-94. [PMID: 16321552 DOI: 10.1016/j.cbpa.2005.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2005] [Revised: 09/30/2005] [Accepted: 10/01/2005] [Indexed: 10/25/2022]
Abstract
The effect of an acute phase response (APR) on cationic amino acid transporter (CAT1-3) mRNA expression in liver, muscle, bursa and thymus was determined in broiler strain chickens. The APR was initiated by injecting Salmonella typhimurium lipopolysaccharide subcutaneously (LPS; 1 mg/kg bw). In Experiment 1, CAT1-3 mRNA expression was determined at multiple time points following LPS administration. LPS increased bursa and liver total and high affinity CAT mRNA expression (P<0.05) and transiently increased pectoralis total CAT mRNA expression (P<0.05). Total CAT mRNA expression in the thymus decreased 7.7-fold from 0 to 8 h after LPS injection (P<0.05). In Experiment 2, fasted chicks were uninjected or LPS-injected. LPS increased total and high affinity CAT mRNA 2-fold in both the bursa and liver (P<0.05) and did not change thymus total and high affinity CAT mRNA expression (P>0.05). LPS increased liver weight only (P<0.05) and did not alter the plasma lysine and arginine concentration (P>0.05). In Experiments 3 and 4, thymocyte proliferation and total protein content were dependent upon the media lysine concentration (P<0.001). The inability of the thymus to compete for lysine and arginine during the APR may limit the ability of thymocytes to develop during infections.
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Affiliation(s)
- Brooke D Humphrey
- Department of Animal Science, University of California, Davis, CA 95616, USA
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23
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Krzepiłko A, Swieciło A, Wawryn J, Zadrag R, Kozioł S, Bartosz G, Biliński T. Ascorbate restores lifespan of superoxide-dismutase deficient yeast. Free Radic Res 2005; 38:1019-24. [PMID: 15621721 DOI: 10.1080/10715760410001717327] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Yeast (Saccharomyces cerevisiae) mutants lacking CuZn-superoxide dismutase (CuZnSOD) are hypersensitive to oxygen and have significantly decreased replicative life span. Both these defects can be ameliorated by exogenous ascorbate. The effect of ascorbate on life span is complicated by auto-oxidation of its compound in the medium. If negative effects of auto-oxidation are prevented by exchange of the medium, ascorbate prolongs not only mean but also maximal replicative life span of the yeast in the atmosphere of air and of pure oxygen. These results demonstrate that life span shortening due to the lack of a vital antioxidant enzyme can be ameliorated by a low-molecular weight antioxidant.
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Affiliation(s)
- Anna Krzepiłko
- Zamość College of Agriculture, ul. Szczebrzeska 102, PL 22-400 Zamość, Poland
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24
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McFadden SL, Woo JM, Michalak N, Ding D. Dietary vitamin C supplementation reduces noise-induced hearing loss in guinea pigs. Hear Res 2005; 202:200-8. [PMID: 15811712 DOI: 10.1016/j.heares.2004.10.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 10/26/2004] [Indexed: 11/25/2022]
Abstract
Vitamin C (ascorbate) is a water-soluble, low molecular weight antioxidant that works in conjunction with glutathione and other cellular antioxidants, and is effective against a variety of reactive oxygen species, including superoxide and hydroxyl radicals that have been implicated in the etiology of noise-induced hearing loss (NIHL). Whereas most animals can manufacture their own vitamin C, humans and a few other mammals such as guinea pigs lack the terminal enzyme for vitamin C synthesis and must obtain it from dietary sources. To determine if susceptibility to NIHL could be influenced by manipulating dietary levels of vitamin C, albino guinea pigs were raised for 35 days on a diet with normal, supplemented or deficient levels of ascorbate, then exposed to 4 kHz octave band noise at 114 dB SPL for 6 h to induce permanent threshold shifts (PTS) of the scalp-recorded auditory brainstem response. Animals that received the highest levels of dietary ascorbate developed significantly less PTS for click stimuli and 4, 8, 12, and 16 kHz tones than animals on normal and deficient diets. Outer hair cell loss was minimal in all groups after noise exposure, but permanent damage to stereocilia were observed in noise-exposed ears. The results support the hypothesis that dietary factors influence individual susceptibility to hearing loss, and suggest that high levels of vitamin C may be beneficial in reducing susceptibility to NIHL.
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Affiliation(s)
- Sandra L McFadden
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, University at Buffalo, NY 14214, USA.
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25
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Abstract
Accumulating research suggests that oxidative stress is a significant contributor to the pathogenesis of diabetic nephropathy. The normal kidney generates a substantial amount of oxidative stress because of its high metabolic activity that is balanced by an extensive antioxidant system. However, in pathologic states such as hyperglycemia, nitroso-oxidant balance shifts toward a pro-oxidant state that accelerates tissue and vascular injury. This oxidative damage progresses concomitant with worsening glucose metabolism, vascular dysfunction, and kidney disease. Accordingly, strategies to reduce oxidative stress in diabetes mellitus may exert favorable effects on the progression of diabetic nephropathy.
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Affiliation(s)
- Nina Vasavada
- Department of Medicine, Division of Nephrology, University of Louisville, KY, USA
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26
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Laggner H, Schmid S, Goldenberg H. Hypericin and photodynamic treatment do not interfere with transport of vitamin C during respiratory burst. Free Radic Res 2005; 38:1073-81. [PMID: 15512795 DOI: 10.1080/10715760412331284780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Hypericin is a photosensitizing pigment found in St. John's wort (Hypericum perforatum) displaying a high toxicity towards certain tumors. The fact that some non-tumor cells, especially monocytes and granulocytes, are resistant to its photocytotoxic effects, posed the question whether this insensitivity is due to their ability to accumulate vitamin C, an antioxidant which alleviates the deleterious work of free radicals. HL-60 promyelocytic tumor cells can be differentiated to neutrophilic granulocytes by treatment with dimethylsulfoxide and were used as cell model. In the differentiated cells, treatment with phorbol esters (PMA) stimulates vitamin C (ascorbate) transport. The uptake rates were unaltered by hypericin at concentrations below 1 microM and irradiation with visible light at a light dose of 6 J/cm2. Inhibition by higher concentrations of hypericin was most probably due to a combination of photocytotoxic properties of the dye and oxygen radicals generated during respiratory burst. Superoxide production by NADPH oxidase followed by reduction of ferricytochrome c was inhibited by hypericin. The degree of inhibition was dependent on the concentration of hypericin and light intensity: IC50-values were 1.7 and 0.7 microM under light doses of 3.6 and 10.8 J/cm2, respectively. Oxidative stress, monitored with 2',7'-dichlorofluorescein (DCF) was only slightly decreased by ascorbate even at higher concentrations of hypericin. In contrast to its effect on the ferricytochrome c-reduction, irradiation had no significant influence on DCF-fluorescence. However, the viability of the cells was strongly decreased after photosensitization and no significant improvement was obtained by ascorbate. Results from this work indicate that ascorbate transport per se is not altered during photodynamic therapy and vitamin C does not interfere with hypericin-induced photodamage of cellular targets.
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Affiliation(s)
- Hildegard Laggner
- Department of Medical Chemistry, Medical University of Vienna, Währinger Strasse 10, A-1090 Vienna, Austria.
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27
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Atanasova BD, Li AC, Bjarnason I, Tzatchev KN, Simpson RJ. Duodenal ascorbate and ferric reductase in human iron deficiency. Am J Clin Nutr 2005; 81:130-3. [PMID: 15640471 DOI: 10.1093/ajcn/81.1.130] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The first step in iron absorption requires the reduction of ferric iron to ferrous iron, a change that is catalyzed by duodenal ferric reductase. Iron deficiency is associated with high iron absorption, high ferric reductase activity, and high duodenal ascorbate concentrations in experimental animals, but it is not known whether a relation between reductase and ascorbate is evident in humans. OBJECTIVE The objective of the study was to assess the relation between ferric reductase activity in human duodenal biopsy specimens and ascorbate concentrations in iron-replete and iron-deficient subjects. DESIGN Patients and control subjects were overnight-fasted adults presenting sequentially for upper gastrointestinal endoscopic investigation. Ferric reductase activity in duodenal biopsy specimens was assayed by using nitroblue tetrazolium. Ascorbate was assayed in duodenal biopsy specimens and plasma. RESULTS Iron-deficient patients had significantly higher reductase activity (n = 6-9; P < 0.05) and duodenal (n = 20; P < 0.001) and plasma (n = 6; P < 0.001) ascorbate concentrations than did control subjects. Incubation of biopsy specimens with dehydroascorbate (to boost cellular ascorbate) increased reductase activity in the tissues that initially had normal activity (n = 9; P < 0.01) but inhibited reductase activity in the tissues that already had high reductase activity (n = 13; P < 0.001). CONCLUSIONS Iron deficiency in humans is associated with increased duodenal ascorbate concentrations. This finding suggests that increased reductase activity is partly due to an increase in this substrate for duodenal cytochrome b reductase 1.
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Affiliation(s)
- Bisera D Atanasova
- Department of Clinical Laboratory and Clinical Immunology, Medical University, Sofia, Bulgaria
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28
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Corpe CP, Lee JH, Kwon O, Eck P, Narayanan J, Kirk KL, Levine M. 6-Bromo-6-deoxy-L-ascorbic acid: an ascorbate analog specific for Na+-dependent vitamin C transporter but not glucose transporter pathways. J Biol Chem 2004; 280:5211-20. [PMID: 15590689 DOI: 10.1074/jbc.m412925200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Vitamin C intracellular accumulation is mediated by Na(+)-dependent vitamin C transporters SVCT1 and -2 and dehydroascorbic acid transporters GLUT1 and -3. It is unclear which pathways dominate in vivo. As a new step to resolve this issue, we identified and tested 6-bromo-6-deoxy-L-ascorbic acid as a specific candidate for SVCTs. In high performance liquid chromatography and electron paramagnetic resonance analyses, the reduced compounds ascorbic acid and 6-bromo-6-deoxy-L-ascorbic acid were similar. The oxidized products 6-bromo-6-deoxy dehydroascorbic acid (BrDHA) and dehydroascorbic acid (DHA) had comparable stabilities, based on reduction recoveries. Upon expression of GLUT1 or GLUT3 in Xenopus oocytes, BrDHA was neither transported nor bound, in contrast to robust transport of DHA. The findings were not explained by differences in the oocyte reduction of DHA and BrDHA because lysed oocytes reduced both compounds equally. Further, there was no transport of the reduced compound, 6-bromo-6-deoxy-L-ascorbic acid, by GLUT1 or GLUT3. As a prerequisite for investigating 6-bromo-6-deoxy-L-ascorbic acid transported by SVCTs, SVCT2 transport activity in oocytes was enhanced 14-fold by construction and use of a vector that added a fixed poly(A) tail to the 3' end of cRNA. For SVCT1 and SVCT2 expressed in oocytes, similar K(m) and V(max) values were observed for ascorbic acid and 6-bromo-6-deoxy-L-ascorbic acid. In human fibroblasts, predicted to have SVCT-mediated ascorbate accumulation, K(m) and V(max) values were again comparable for ascorbic acid and 6-bromo-6-deoxy-L-ascorbic acid. Using activated human neutrophils, predicted to have ascorbate accumulation mediated predominantly by DHA and GLUT transporters, 6-bromo-6-deoxy-L-ascorbic acid accumulation was <1% of accumulation when compared with ascorbic acid. We conclude that 6-bromo-6-deoxy-L-ascorbic acid is the first transport substrate identified as completely specific for SVCTs, but not GLUTs, and provide a new strategy to determine the contribution of each pathway to ascorbate accumulation.
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Affiliation(s)
- Christopher P Corpe
- Molecular and Clinical Nutrition Section, Digestive Diseases Branch, NIDDK, National Institutes of Health, Bethesda, MD 20892-1372, USA
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29
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Corti A, Raggi C, Franzini M, Paolicchi A, Pompella A, Casini AF. Plasma membrane gamma-glutamyltransferase activity facilitates the uptake of vitamin C in melanoma cells. Free Radic Biol Med 2004; 37:1906-15. [PMID: 15528049 DOI: 10.1016/j.freeradbiomed.2004.08.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2004] [Revised: 08/03/2004] [Accepted: 08/26/2004] [Indexed: 11/26/2022]
Abstract
Adequate cellular transport of ascorbic acid (AA) and its oxidation product dehydroascorbate (DHA) is assured through specific carriers. It was shown that vitamin C is taken up as DHA by most cell types, including cancer cells, via the facilitative GLUT transporters. Thus, AA oxidation to DHA can be considered a mechanism favoring vitamin C uptake and intracellular accumulation. We have investigated whether such an AA-oxidizing action might be provided by plasma membrane gamma-glutamyltransferase (GGT), previously shown to function as an autocrine source of prooxidants. The process was studied using two distinct human metastatic melanoma clones. It was observed that the Me665/2/60 clone, expressing high levels of membrane GGT activity, was capable of effecting the oxidation of extracellular AA, accompanied by a marked increase of intracellular AA levels. The phenomenon was not observed with Me665/2/21 cells, possessing only traces of membrane GGT. On the other hand, AA oxidation and stimulation of cellular uptake were indeed observed after transfection of 2/21 cells with cDNA coding for GGT. The mechanism of GGT-mediated AA oxidation was investigated in acellular systems, including GGT and its substrate glutathione. The process was observed in the presence of redox-active chelated iron(II) and of transferrin or ferritin, i.e., two physiological iron sources. Thus, membrane GGT activity-often expressed at high levels in human malignancies-can oxidize extracellular AA and promote its uptake efficiently.
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Affiliation(s)
- Alessandro Corti
- Department of Experimental Pathology B.M.I.E., University of Pisa Medical School, Via Roma 55, 56126 Pisa, Italy
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30
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Eichenberger B, Pfirter HP, Wenk C, Gebert S. Influence of dietary vitamin E and C supplementation on vitamin E and C content and thiobarbituric acid reactive substances (TBARS) in different tissues of growing pigs. Arch Anim Nutr 2004; 58:195-208. [PMID: 15264669 DOI: 10.1080/00039420410001701413] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
To investigate the influence and possible interactions of dietary vitamin E and C supplementation on vitamin content of both vitamins and oxidative stability of different pork tissues 40 Large White barrows from 25 kg to 106 kg were allocated to four different cereal based diets: Basal diet (B), dl-alpha-tocopherylacetate + 200 mg/kg (E), crystalline ascorbic acid + 300 mg/kg (C) or both vitamins (EC). At slaughtering samples of liver, spleen, heart, kidney, backfat outer layer, ham and M. tongissimus dorsi were obtained. Growth performance of the pigs and carcass characteristics were not influenced by feeding treatments. Dietary vitamin E supplementation had a significant effect on the vitamin E and alpha-tocopherol concentration in all investigated tissues. Backfat outer layer, liver, spleen, kidney and heart had higher vitamin E concentrations than ham and M. longissimus dorsi. Dietary vitamin C supplementation tended towards enhanced vitamin E levels except for ham samples. Therefore, some synergistic actions without dietary vitamin E supplementation between the two vitamins could be shown. The vitamin C concentration and TBARS were increased or at least equal in all tissues due to vitamin C supplementation. Dietary alpha-tocopherol supplementation resulted in lower TBARS in backfat outer layer (malondialdehyde 0.35 mg/kg in B vs. 0.28 mg/kg in E), but increased in heart and ham. When both vitamins were supplemented (EC) TBARS were lower in M. longissimus dorsi and backfat outer layer, equal in heart and higher in liver and ham compared to a single vitamin C supplementation. Rancimat induction time of backfat outer layer was 0.3 h higher in C compared to B and 0.17 h higher in EC than in E. Correlations between levels of both vitamins were positive for kidney (r = 0.169), M. longissimus dorsi (r = 0.499) and ham (r = 0.361) and negative for heart (r = -0.350). In liver and spleen no interaction could be found. In backfat outer layer vitamin E was positively correlated with rancimat induction time (r = 0.550) and negatively with TBARS (r = -0.202), but provided no evidence that dietary vitamin E supply led to better oxidative stability.
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Affiliation(s)
- Barbara Eichenberger
- Institute of Animal Sciences, Nutrition Biology, Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
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Salnikow K, Donald SP, Bruick RK, Zhitkovich A, Phang JM, Kasprzak KS. Depletion of intracellular ascorbate by the carcinogenic metals nickel and cobalt results in the induction of hypoxic stress. J Biol Chem 2004; 279:40337-44. [PMID: 15271983 DOI: 10.1074/jbc.m403057200] [Citation(s) in RCA: 232] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exposure of cells to carcinogenic compounds of nickel(II) and cobalt(II) causes activation of the HIF-1 transcription factor and up-regulates a battery of hypoxia-inducible genes. However, the mechanism of HIF-1 activation by these metals is not known. It was shown recently that hydroxylation of prolines in the HIFalpha subunit of HIF-1 is required for its binding with the von Hippel-Lindau tumor suppressor protein and the subsequent proteasomal destruction. Here we show that responsible prolyl hydroxylases are targets for both nickel(II) and cobalt(II) because degradation of a reporter protein containing the oxygen-dependent degradation domain (Pro-402/564) of HIFalpha was abolished in a von Hippel-Lindau-dependent manner in cells exposed to nickel(II) or cobalt(II). The enzymatic activity of prolyl hydroxylases depends on iron as the activating metal, 2-oxoglutarate as a co-substrate, and ascorbic acid as a cofactor. Hydroxylase activity can be impaired by the depletion of any of these factors. We found that exposure of cells to nickel(II) or cobalt(II) did not affect the level of intracellular iron. Instead, nickel(II) or cobalt(II) exposure greatly depleted intracellular ascorbate. Co-exposure of cells to metals and ascorbate resulted in the increase of intracellular ascorbate and reversed both metal-induced stabilization of HIF-1alpha and HIF-1-dependent gene transcription. Because ascorbate is essential for maintaining iron in prolyl hydroxylases in the active iron(II) state, we suggest that the observed depletion of ascorbate by nickel(II) or cobalt(II) favors iron oxidation and thus inactivation of the enzyme.
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Affiliation(s)
- Konstantin Salnikow
- NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
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32
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Guidarelli A, Fiorani M, Cantoni O. Enhancing effects of intracellular ascorbic acid on peroxynitrite-induced U937 cell death are mediated by mitochondrial events resulting in enhanced sensitivity to peroxynitrite-dependent inhibition of complex III and formation of hydrogen peroxide. Biochem J 2004; 378:959-66. [PMID: 14627438 PMCID: PMC1223997 DOI: 10.1042/bj20031167] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 11/19/2003] [Accepted: 11/20/2003] [Indexed: 11/17/2022]
Abstract
A short-term pre-exposure to dehydroascorbic acid (DHA) promotes U937 cell death upon exposure to otherwise non-toxic levels of peroxynitrite (ONOO-). Toxicity is mediated by a saturable mechanism and cell death takes place as a consequence of mitochondrial permeability transition. The following lines of evidence are consistent with the notion that the enhancing effects of DHA were related to mitochondrial events resulting in inhibition of complex III upon exposure to otherwise inactive concentrations of ONOO-. First, DHA, as well as bona fide complex III inhibitors, similarly enhanced toxicity and subsequent formation of H2O2 induced by ONOO- via a rotenone- or catalase-sensitive mechanism. Secondly, bona fide complex III inhibitors were ineffective in DHA-pre-loaded cells. In addition, respiration-deficient cells were resistant to toxicity elicited by ONOO- and their supplementation with increasing concentrations of DHA, although resulting in the accumulation of vitamin C levels identical with those observed in respiration-proficient cells, failed to affect ONOO- toxicity. Finally, oxygen-consumption experiments demonstrated that pre-exposure to DHA promotes the ONOO--dependent inhibition of complex III. In conclusion, the above results collectively demonstrate that increasing the intracellular accumulation of vitamin C promotes mitochondrial events leading to ONOO--dependent formation of H2O2 and resulting in a rapid necrotic response.
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Affiliation(s)
- Andrea Guidarelli
- Istituto di Farmacologia e Farmacognosia, Università degli Studi di Urbino 'Carlo Bo', Via S. Chiara 27, 61029 Urbino, Italy
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33
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Atanasova B, Mudway IS, Laftah AH, Latunde-Dada GO, McKie AT, Peters TJ, Tzatchev KN, Simpson RJ. Duodenal ascorbate levels are changed in mice with altered iron metabolism. J Nutr 2004; 134:501-5. [PMID: 14988437 DOI: 10.1093/jn/134.3.501] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Ascorbate has long been thought to play an important role in intestinal iron absorption. The recent identification of a possible ascorbate-dependent duodenal ferric reductase suggests a role for intracellular ascorbate in the control of iron absorption. We set out to determine whether duodenal ascorbate concentrations are altered by treatments known to alter the rate of iron absorption and whether ascorbate levels affect duodenal reductase activity. Duodenal ascorbate was extracted and assayed by HPLC and/or a chemical assay. Ferric reductase was assayed in vitro with ferric nitrilotriacetate or nitroblue tetrazolium as substrates. Duodenal ascorbate concentrations were increased by iron deficiency, genetic hypotransferrinemia, and hypoxia. Parenteral iron overload increased iron stores but did not affect duodenal ascorbate concentrations. Hemolytic anemia induced in mice by phenylhydrazine injection also did not affect duodenal ascorbate concentrations. In vitro studies with incubated duodenum showed that decreased tissue ascorbate was associated with decreased mucosal ferric reductase activity, whereas incubation with dehydroascorbate prevented both the decrease in ascorbate concentration and reductase activity. Mouse duodenum ascorbate concentrations changed in response to treatments that altered iron absorption rates; in particular, ascorbate levels generally increased when iron absorption was increased by iron deficiency, hypoxia, or genetic hypotransferrinemia. We conclude that changes in ascorbate levels are associated with changes in ferric reductase activity. These findings are consistent with the proposal that duodenal ascorbate plays a role in intestinal iron absorption.
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Affiliation(s)
- Bisera Atanasova
- Department of Clinical Laboratory and Clinical Immunology, Medical University, Sofia, Bulgaria
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Abstract
The main theme of this chapter concerns the precise biochemical mechanisms involved in stages up to, and including, gastrointestinal absorption of vitamins and certain selected minerals. Essential data regarding sequential events, immediately following absorption of these micronutrients, are also included. There is reference to water-soluble vitamins that are, in general, either coenzymes in various metabolic reactions or carriers of certain biochemical groupings. In contrast, fat-soluble vitamins frequently function as integral components of cell membranes; they, too, receive ample attention. It is appropriate, nevertheless, to recognize that some minerals required in very small amounts are closely allied biochemically with particular vitamins; these specific associations are apportioned emphasis at relevant places in the text. Although predominant discussion centres on the physiological state, clinical reference is necessarily made to gastrointestinal disorders in which imbalance of vitamins and minerals consequently results in an additional detrimental impact on health.
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Affiliation(s)
- Tapan K Basu
- Department of Agricultural, Food and Nutritional Sciences, University of Alberta, 3-18B Agricultural Forestry Building, Edmonton, Alta, Canada T6G 2P5.
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Pepperell JR, Porterfield DM, Keefe DL, Behrman HR, Smith PJS. Control of ascorbic acid efflux in rat luteal cells: role of intracellular calcium and oxygen radicals. Am J Physiol Cell Physiol 2003; 285:C642-51. [PMID: 12724141 DOI: 10.1152/ajpcell.00587.2002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In luteal cells, prostaglandin (PG)F2a mobilizes intracellular calcium concentration ([Ca]i), generates reactive oxygen species (ROS), depletes ascorbic acid (AA) levels, inhibits steroidogenesis, and ultimately induces cell death. We investigated the hypothesis that [Ca]i mobilization stimulates ROS, which results in depletion of cellular AA in rat luteal cells. We used a self-referencing AA-selective electrode that noninvasively measures AA flux at the extended boundary layer of single cells and fluorescence microscopy with fura 2 and dichlorofluorescein diacetate (DCF-DA) to measure [Ca]i and ROS, respectively. Menadione, a generator of intracellular superoxide radical (O2-), PGF2a, and calcium ionophore were shown to increase [Ca]i and stimulate intracellular ROS. With calcium ionophore and PGF2a, but not menadione, the generation of ROS was dependent on extracellular calcium influx. In unstimulated cells there was a net efflux of AA of 121.5 +/- 20.3 fmol x cm-1 x s-1 (mean +/- SE, n = 8), but in the absence of extracellular calcium the efflux was significantly reduced (10.3 +/- 4.9 fmol x cm-1 x s-1; n = 5, P < 0.05). PGF2a and menadione stimulated AA efflux, but calcium ionophore had no significant effect. These data suggest two AA regulatory mechanisms: Under basal conditions, AA efflux is calcium dependent and may represent recycling and maintenance of an antioxidant AA gradient at the plasma membrane. Under luteolytic hormone and/or oxidative stress, AA efflux is stimulated that is independent of extracellular calcium influx or generation of ROS. Although site-specific mobilization of calcium pools and ROS cannot be ruled out, the release of AA by PGF2a-stimulated luteal cells may occur through other signaling pathways.
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Affiliation(s)
- John R Pepperell
- Department of Obstetrics and Gynecology, Women and Infants Hospital of Rhode Island, 101 Dudley St., Providence, RI 02905, USA.
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Alegria AE, Cordones E, Santiago G, Marcano Y, Sanchez S, Gordaliza M, Martín-Martín ML. Reductive activation of terpenylnaphthoquinones. Toxicology 2002; 175:167-75. [PMID: 12049845 DOI: 10.1016/s0300-483x(02)00076-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Four terpenylnaphthoquinones were found to enhance the rate of superoxide production in the presence of ascorbate as detected from the superoxide dismutase (SOD)-inhibitable initial oxygen consumption rates. Initial rates of oxygen consumption in the presence of ascorbate plus quinone increase with an increase in the half-wave reduction potentials of the quinones. These quinones also enhance the rate of Cyt(III)c reduction by xanthine/xanthine oxidase (X/XO) in both air- and nitrogen-saturated aqueous solutions at pH 7.4. Maximum rates of Cyt(III)c reduction in nitrogen and oxygen-saturated solutions (V(max)), in the presence of X/XO, increase with an increase in the half-wave reduction potentials of the quinones. SOD inhibits Cyt(III)c reduction rates in the presence of these quinones and X/XO in a manner which is also dependent on the quinone half-wave redox potential. The relative antineoplastic activity of two of these quinones follows the order in rates of oxygen consumption or Cyt(III)c reduction. This is consistent with an antineoplastic action of these quinones through the mechanism of redox cycling or possible interference or inhibition of mitochondrial respiration.
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Affiliation(s)
- Antonio E Alegria
- Department of Chemistry, University of Puerto Rico at Humacao, CUH Station, Humacao, PR 00791, USA.
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Root-Bernstein R, Busik JV, Henry DN. Are diabetic neuropathy, retinopathy and nephropathy caused by hyperglycemic exclusion of dehydroascorbate uptake by glucose transporters? J Theor Biol 2002; 216:345-59. [PMID: 12183123 DOI: 10.1006/jtbi.2002.2535] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vitamin C exists in two major forms. The charged form, ascorbic acid (AA), is taken up into cells via sodium-dependent facilitated transport. The uncharged form, dehydroascorbate (DHA), enters cells via glucose transporters (GLUT) and is then converted back to AA within these cells. Cell types such as certain endothelial and epithelial cells as well as neurons that are particularly prone to damage during diabetes tend to be those that appear to be dependent on GLUT transport of DHA rather than sodium-dependent AA uptake. We hypothesize that diabetic neuropathies, nephropathies and retinopathies develop in part by exclusion of DHA uptake by GLUT transporters when blood glucose levels rise above normal. AA plays a central role in the antioxidant defense system. Exclusion of DHA from cells by hyperglycemia would deprive the cells of the central antioxidant, worsening the hyperglycemia-induced oxidative stress level. Moreover, AA participates in many cellular oxidation-reduction reactions including hydroxylation of polypeptide lysine and proline residues and dopamine that are required for collagen production and metabolism and storage of catecholamines in neurons. Increase in the oxidative stress level and metabolic perturbations can be expected in any tissue or cell type that relies exclusively or mainly on GLUT for co-transport of glucose and DHA including neurons, epithelial cells, and vascular tissues. On the other hand, since DHA represents a significant proportion of total serum ascorbate, by increasing total plasma ascorbate concentrations during hyperglycemia, it should be possible to correct the increase in the oxidative stress level and metabolic perturbations, thereby sparing diabetic patients many of their complications.
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Abstract
The signaling networks that mediate activation, proliferation, or programmed cell death of T lymphocytes are dependent on complex redox and metabolic pathways. T lymphocytes are primarily activated through the T-cell receptor and co-stimulatory molecules. Although activation results in lymphokine production, proliferation, and clonal expansion, it also increases susceptibility to apoptosis upon crosslinking of cell-surface death receptors or exposure to toxic metabolites. Activation signals are transmitted by receptor-associated protein tyrosine kinases and phosphatases through calcium mobilization to a secondary cascade of kinases, which in turn activate transcription factors initiating cell proliferation and cytokine production. Initiation and activity of cell death-mediating proteases are redox-sensitive and dependent on energy provided by ATP. Mitochondria play crucial roles in providing ATP for T-cell activation through the electron transport chain and oxidative phosphorylation. The mitochondrial transmembrane potential (DeltaPsi(m)) plays a decisive role not only by driving ATP synthesis, but also by controlling reactive oxygen species production and release of cell death-inducing factors. DeltaPsi(m) and reactive oxygen species levels are regulated by the supply of reducing equivalents, glutathione and thioredoxin, as well as NADPH generated in the pentose phosphate pathway. This article identifies redox and metabolic checkpoints controlling activation and survival of T lymphocytes.
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Affiliation(s)
- Andras Perl
- Departments of Medicine, Microbiology and Immunology, and Pathology, State University of New York Upstate Medical University, College of Medicine, 750 East Adams Street, Syracuse, NY 13210, USA.
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Puskas F, Gergely P, Niland B, Banki K, Perl A. Differential regulation of hydrogen peroxide and Fas-dependent apoptosis pathways by dehydroascorbate, the oxidized form of vitamin C. Antioxid Redox Signal 2002; 4:357-69. [PMID: 12215204 DOI: 10.1089/15230860260196164] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Dehydroascorbate (DHA), the oxidized form of vitamin C (ascorbate), enhanced antioxidant defenses of human T cells preferentially importing DHA over ascorbate. In itself, DHA did not affect cytosolic or mitochondrial reactive oxygen intermediate levels as monitored by flow cytometry using oxidation-sensitive fluorescent probes. DHA at 200-1,000 microM stimulated activity of pentose phosphate pathway enzymes glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and transaldolase, elevated intracellular glutathione levels, and inhibited H(2)O(2)-induced changes in mitochondrial transmembrane potential and cell death. With respect to the CD4 antigen, DHA selectively enhanced cell-surface expression of the Fas receptor and increased susceptibility of Jurkat and H9 human T cells to Fas-mediated cell death. The data identify DHA as a selective regulator of H(2)O(2)- and Fas-dependent apoptosis pathways.
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Affiliation(s)
- Ferenc Puskas
- Department of Medicine, State University of New York Upstate Medical University, College of Medicine, 750 East Adams Street, Syracuse, NY 13210, USA
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Sotiriou S, Gispert S, Cheng J, Wang Y, Chen A, Hoogstraten-Miller S, Miller GF, Kwon O, Levine M, Guttentag SH, Nussbaum RL. Ascorbic-acid transporter Slc23a1 is essential for vitamin C transport into the brain and for perinatal survival. Nat Med 2002; 8:514-7. [PMID: 11984597 DOI: 10.1038/0502-514] [Citation(s) in RCA: 257] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The only proven requirement for ascorbic acid (vitamin C) is in preventing scurvy, presumably because it is a cofactor for hydroxylases required for post-translational modifications that stabilize collagen. We have created mice deficient in the mouse ortholog (solute carrier family 23 member 1 or Slc23a1) of a rat ascorbic-acid transporter, Svct2 (ref. 4). Cultured embryonic fibroblasts from homozygous Slc23a1(-/-) mice had less than 5% of normal ascorbic-acid uptake. Ascorbic-acid levels were undetectable or markedly reduced in the blood and tissues of Slc23a1(-/-) mice. Prenatal supplementation of pregnant females did not elevate blood ascorbic acid in Slc23a1(-/-) fetuses, suggesting Slc23a1 is important in placental ascorbic-acid transport. Slc23a1(-/-) mice died within a few minutes of birth with respiratory failure and intraparenchymal brain hemorrhage. Lungs showed no postnatal expansion but had normal surfactant protein B levels. Brain hemorrhage was unlikely to be simply a form of scurvy since Slc23a1(-/-) mice showed no hemorrhage in any other tissues and their skin had normal skin 4-hydroxyproline levels despite low ascorbic-acid content. We conclude that Slc23a1 is required for transport of ascorbic acid into many tissues and across the placenta. Deficiency of the transporter is lethal in newborn mice, thereby revealing a previously unrecognized requirement for ascorbic acid in the perinatal period.
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Affiliation(s)
- Sotiria Sotiriou
- Genetic Diseases Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
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Patel M, McIntosh L, Bliss T, Ho D, Sapolsky R. Interactions among ascorbate, dehydroascorbate and glucose transport in cultured hippocampal neurons and glia. Brain Res 2001; 916:127-35. [PMID: 11597599 DOI: 10.1016/s0006-8993(01)02877-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
There is an increasing recognition of the damaging role played by oxygen radicals in mediating necrotic neuronal injury. As such, it becomes important to understand the transport mechanisms that help maintain appropriate levels of small molecule antioxidants such as ascorbate in the brain. It has long been known that the transport of dehydroascorbate (DHA) into a variety of cell types is accomplished through the Glut-1 glucose transporter. In this paper, we characterize interactions among the transports of ascorbate, DHA and glucose in hippocampal cultures. We find: (a) sodium-dependent transport of ascorbate in mixed neuronal/glial, pure glial, and neuron-enriched hippocampal cultures; in contrast, we observed no such transport of DHA; (b) such ascorbate transport appeared to be independent of the glucose transporter, in that glucose did not compete for such transport, and overexpression of the Glut-1 glucose transporter did not alter ascorbate uptake; (c) in contrast, ascorbate, at concentrations ranging from 1 to 20 mM inhibited 2-dexogyglucose transport in mixed, glial and enriched neuronal hippocampal cultures; (d) potentially, ascorbate, by acting as an electron donor, could impair the function of molecules involve in the transport or metabolism of glucose. We observed mild inhibition of glucose transport by one unrelated electron donor (glutathione). Moreover, transport was also inhibited by an ascorbate analog which is not an electron donor. Thus, we conclude that ascorbate transport in hippocampal neurons and glia occurs independent of the glucose transporter but that, nevertheless, ascorbate, at concentrations generally thought to be supraphysiological, has the potential for disrupting glucose transport.
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Affiliation(s)
- M Patel
- Department of Biological Sciences, Gilbert Laboratory, MC 4020, Stanford University, Stanford, CA 94305, USA
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42
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Van Duijn MM, Buijs JT, Van der Zee J, Van den Broek PJ. The ascorbate: ascorbate free radical oxidoreductase from the erythrocyte membrane is not cytochrome b561. PROTOPLASMA 2001; 217:94-100. [PMID: 11732344 DOI: 10.1007/bf01289418] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Erythrocytes contain a plasma membrane redox system that can reduce extracellular ascorbate radicals by using intracellular ascorbate as an electron donor. In this study, the hypothesis was tested that cytochrome b561 was a component of this system. Spectroscopic analysis of erythrocyte membrane preparations revealed the presence of cytochrome b5 and hemoglobin but also of a cytochrome with properties similar to cytochrome b561, reducible by ascorbate and insensitive to CO. The presence of cytochrome b561 was studied further by reverse transcriptase-PCR analysis of erythrocyte progenitor cells, reticulocytes. However, no cytochrome b561 mRNA could be found. These results were corroborated by Western blot analysis with an anti-cytochrome b561 serum. No cytochrome b561 protein could be detected in extracts of erythrocyte membranes. It is therefore concluded that erythrocytes do not contain cytochrome b561 in their membranes. The possible involvement of other b-cytochromes in ascorbate-ascorbate free radical oxidoreductase activity is discussed.
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Affiliation(s)
- M M Van Duijn
- Sylvius Laboratory, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
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43
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Abstract
Vitamin C is essential for many enzymatic reactions and also acts as a free radical scavenger. Specific non-overlapping transport proteins mediate the transport of the oxidized form of vitamin C, dehydroascorbic acid, and the reduced form, L-ascorbic acid, across biological membranes. Dehydroascorbic acid uptake is via the facilitated-diffusion glucose transporters, GLUT 1, 3 and 4, but under physiological conditions these transporters are unlikely to play a major role in the uptake of vitamin C due to the high concentrations of glucose that will effectively block influx. L-ascorbic acid enters cells via Na+-dependent systems, and two isoforms of these transporters (SVCT1 and SVCT2) have recently been cloned from humans and rats. Transport by both isoforms is stereospecific, with a pH optimum of approximately 7.5 and a Na+:ascorbic acid stoichiometry of 2:1. SVCT2 may exhibit a higher affinity for ascorbic acid than SVCT1 but with a lower maximum velocity. SVCT1 and SVCT2 are predicted to have 12 transmembrane domains, but they share no structural homology with other Na+ co-transporters. Potential sites for phosphorylation by protein kinase C exist on the cytoplasmic surface of both proteins, with an additional protein kinase A site in SVCT1. The two isoforms also differ in their tissue distribution: SVCT1 is present in epithelial tissues, whereas SVCT2 is present in most tissues with the exception of lung and skeletal muscle.
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Affiliation(s)
- W J Liang
- Research School of Biosciences, University of Kent, Canterbury, UK
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44
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VanDuijn MM, Tijssen K, VanSteveninck J, Van Den Broek PJ, Van Der Zee J. Erythrocytes reduce extracellular ascorbate free radicals using intracellular ascorbate as an electron donor. J Biol Chem 2000; 275:27720-5. [PMID: 10871632 DOI: 10.1074/jbc.m910281199] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ascorbate is readily oxidized in aqueous solution by ascorbate oxidase. Ascorbate radicals are formed, which disproportionate to ascorbate and dehydroascorbic acid. Addition of erythrocytes with increasing intracellular ascorbate concentrations decreased the oxidation of ascorbate in a concentration-dependent manner. Concurrently, it was found, utilizing electron spin resonance spectroscopy, that extracellular ascorbate radical levels were decreased. Control experiments showed that these results could not be explained by leakage of ascorbate from the cells, inactivation of ascorbate oxidase, or oxygen depletion. Thus, this means that intracellular ascorbate is directly responsible for the decreased oxidation of extracellular ascorbate. Exposure of ascorbate-loaded erythrocytes to higher levels of extracellular ascorbate radicals resulted in the detection of intracellular ascorbate radicals. Moreover, efflux of dehydroascorbic acid was observed under these conditions. These data confirm the view that intracellular ascorbate donates electrons to extracellular ascorbate free radical via a plasma membrane redox system. Such a redox system enables the cells to effectively counteract oxidative processes and thereby prevent depletion of extracellular ascorbate.
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Affiliation(s)
- M M VanDuijn
- Department of Molecular Cell Biology, Sylvius Laboratory, Leiden University Medical Center, P. O. Box 9503, 2300 RA Leiden, The Netherlands
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45
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Csala M, Mile V, Benedetti A, Mandl J, Bánhegyi G. Ascorbate oxidation is a prerequisite for its transport into rat liver microsomal vesicles. Biochem J 2000; 349:413-5. [PMID: 10880339 PMCID: PMC1221163 DOI: 10.1042/0264-6021:3490413] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Oxidation and uptake of ascorbate show similar time courses in rat liver microsomal vesicles: a rapid burst phase is followed by a slower process. Inhibitors of ascorbate oxidation (proadifen, econazole or quercetin) also effectively decreased the uptake of ascorbate. The results show that dehydroascorbate is the transport form of ascorbate at the membrane of the endoplasmic reticulum.
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Affiliation(s)
- M Csala
- Department of Medical Chemistry, Semmelweis University, P.O.B. 260, H-1444 Budapest, Hungary
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46
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Puskas F, Gergely P, Banki K, Perl A. Stimulation of the pentose phosphate pathway and glutathione levels by dehydroascorbate, the oxidized form of vitamin C. FASEB J 2000. [DOI: 10.1096/fasebj.14.10.1352] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ferenc Puskas
- Departments of MedicineState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
| | - Peter Gergely
- Departments of MedicineState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
| | - Katalin Banki
- Departments of MedicineState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
- PathologyState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
| | - Andras Perl
- Departments of MedicineState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
- Microbiology and ImmunologyState University of New York Health Science CenterCollege of Medicine, Syracuse New York 13210 USA
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Horemans N, Foyer CH, Asard H. Transport and action of ascorbate at the plant plasma membrane. TRENDS IN PLANT SCIENCE 2000; 5:263-7. [PMID: 10838618 DOI: 10.1016/s1360-1385(00)01649-6] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The plasmalemma is both a bridge and a barrier between the cytoplasm and the outside world. It is a dynamic interface that perceives and transmits information concerning changes in the environment to the nucleus to modify gene expression. In plants, ascorbate is an essential part of this dialogue. The concentration and ratio of reduced to oxidized ascorbate in the apoplast, for example, possibly modulates cell division and growth. The leaf apoplast contains millimolar amounts of ascorbate that protect the plasmalemma against oxidative damage. The apoplastic ascorbate-dehydroascorbate redox couple is linked to the cytoplasmic ascorbate-dehydroascorbate redox couple by specific transporters for either or both metabolites. Although evidence about the mechanisms driving ascorbate or dehydroascorbate transport remains inconclusive, these carrier proteins potentially regulate the level and redox status of ascorbate in the apoplast. The redox coupling between compartments facilitated by these transport systems allows coordinated control of key physiological responses to environmental cues.
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Affiliation(s)
- N Horemans
- Dept of Biology, University of Antwerp (RUCA), Antwerp, Belgium.
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48
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Goldenberg H, Landertshamer H, Laggner H. Functions of vitamin C as a mediator of transmembrane electron transport in blood cells and related cell culture models. Antioxid Redox Signal 2000; 2:189-96. [PMID: 11229525 DOI: 10.1089/ars.2000.2.2-189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Vitamin C (ascorbic acid) is an important physiological antioxidant. Within cells, it is practically always present in the reduced form. Several enzymatic and nonenzymatic mechanisms have been reported to maintain this status. In the extracellular environment, oxidation of ascorbate leads to loss of vitamin because the oxidized form, dehydroascorbic acid, is unstable under physiological conditions. The intermediate ascorbate free radical, although rather long-lived for a free radical, quickly disproportionates into the two other forms, also leading to loss of vitamin. Protection from loss can only be achieved by cellular regeneration mechanisms, i.e., by uptake of dehydroascorbic acid and either storage or recycling, and by plasma-membrane mediated reduction of extracellular free radical or dehydroascorbic acid. Moreover, intracellular ascorbate can also serve as an electron donor for transmembrane reduction of external electron acceptors. However, the physiological significance of this function is as yet unknown. The results presented in the literature are sometimes conflicting as to the relative contributions of these different possibilities, which seem to differ in different cell types. In this short review, the various pathways of regeneration of ascorbate and their relative contributions to the avoidance of vitamin loss in plasma or cell culture medium are discussed.
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Affiliation(s)
- H Goldenberg
- Department of Medical Chemistry, University of Vienna, Austria.
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49
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Malo C, Wilson JX. Glucose modulates vitamin C transport in adult human small intestinal brush border membrane vesicles. J Nutr 2000; 130:63-9. [PMID: 10613768 DOI: 10.1093/jn/130.1.63] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The uptake of L-ascorbate (vitamin C) and its oxidized form, dehydro-L-ascorbic acid (DHAA), was evaluated in brush border membrane vesicles isolated from adult human duodenum, jejunum and ileum. Ascorbate was taken up along the entire length of the small intestine with a threefold higher initial uptake rate in distal than proximal segments. Ascorbate uptake was Na(+)-dependent, potential-sensitive and saturable (K(m), 200 micromol/L), whereas DHAA transport involved facilitated diffusion (K(m), 800 micromol/L). Pharmacologic experiments were conducted to characterize further these transport mechanisms. DHAA uptake was not mediated by the fructose carrier GLUT5, the uridine transporter or the 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-sensitive anion exchanger of the apical membrane. DIDS and sulfinpyrazone, an inhibitor of the urate/lactate exchanger, both significantly reduced the initial rate of ascorbate uptake. Acidic pH inhibited ascorbate uptake, and this effect was not due to a transmembrane proton gradient. Increasing concentrations of glucose in the transport media also significantly inhibited ascorbate uptake, but no effect of glucose was seen when glucose internalization was blocked by phlorizin. Preloading the vesicles with glucose inhibited ascorbate uptake similarly, indicating that glucose interferes with the ascorbate transporter from the internal side of the membrane. The results of this study suggest that DHAA crosses the apical membrane by facilitated diffusion, whereas ascorbate transport is a Na(+)-dependent, electrogenic process modulated by glucose.
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Affiliation(s)
- C Malo
- Membrane Transport Research Group, Department of Physiology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
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50
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Rumsey SC, Welch RW, Garraffo HM, Ge P, Lu SF, Crossman AT, Kirk KL, Levine M. Specificity of ascorbate analogs for ascorbate transport. Synthesis and detection of [(125)I]6-deoxy-6-iodo-L-ascorbic acid and characterization of its ascorbate-specific transport properties. J Biol Chem 1999; 274:23215-22. [PMID: 10438494 DOI: 10.1074/jbc.274.33.23215] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cellular ascorbic acid accumulation occurs in vitro by two distinct mechanisms: transport of ascorbate itself or transport and subsequent intracellular reduction of its oxidized product, dehydroascorbic acid. It is unclear which mechanism predominates in vivo. An easily detectable compound resembling ascorbate but not dehydroascorbic acid could be a powerful tool to distinguish the two transport activities. To identify compounds, 21 ascorbate analogs were tested for inhibition of ascorbate or dehydroascorbic acid transport in human fibroblasts. The most effective analogs, competitive inhibitors of ascorbate transport with K(i) values of 3 microM, were 6-deoxy-6-bromo-, 6-deoxy-6-chloro-, and 6-deoxy-6-iodo-L-ascorbate. No analog inhibited dehydroascorbic acid transport. Using substitution chemistry, [(125)I]6-deoxy-6-iodo-L-ascorbate (1.4 x 10(4) mCi/mmol) was synthesized. HPLC detection methods were developed for radiolabeled and nonradiolabeled compounds, and transport kinetics of both compounds were characterized. Transport was sodium-dependent, inhibited by excess ascorbate, and similar to that of ascorbate. Transport of oxidized ascorbate and oxidized 6-deoxy-6-iodo-L-ascorbate was investigated using Xenopus laevis oocytes expressing glucose transporter isoform GLUT1 or GLUT3. Oxidation of ascorbate or its analog in media increased uptake of ascorbate in oocytes by 6-13-fold compared with control but not that of 6-deoxy-6-iodo-L-ascorbate. Therefore, 6-deoxy-6-iodo-L-ascorbate, although an effective inhibitor of ascorbate transport, either in its reduced or oxidized form was not a substrate for dehydroascorbic acid transport. Thus, radiolabeled and nonradiolabeled 6-deoxy-6-iodo-L-ascorbate provide a new means for discriminating dehydroascorbic acid and ascorbate transport in ascorbate recycling.
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Affiliation(s)
- S C Rumsey
- Molecular and Clinical Nutrition Section, Digestive Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-1372, USA
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