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Ostrakhovitch EA, Semenikhin OA. The role of redox environment in neurogenic development. Arch Biochem Biophys 2012; 534:44-54. [PMID: 22910298 DOI: 10.1016/j.abb.2012.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/19/2012] [Accepted: 08/03/2012] [Indexed: 10/28/2022]
Abstract
The dynamic changes of cellular redox elements during neurogenesis allow the control of specific programs for selective lineage progression. There are many redox couples that influence the cellular redox state. The shift from a reduced to an oxidized state and vice versa may act as a cellular switch mechanism of stem cell mode of action from proliferation to differentiation. The redox homeostasis ensures proper functioning of redox-sensitive signaling pathways through oxidation/reduction of critical cysteine residues on proteins involved in signal transduction. This review presents the current knowledge on the relation between changes in the cellular redox environment and stem cell programming in the course of commitment to a restricted neural lineage, focusing on in vivo neurogenesis and in vitro neuronal differentiation. The first two sections outline the main systems that control the intracellular redox environment and make it more oxidative or reductive. The last section provides the background on redox-sensitive signaling pathways that regulate neurogenesis.
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Affiliation(s)
- E A Ostrakhovitch
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7.
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Glutathione in cerebral microvascular endothelial biology and pathobiology: implications for brain homeostasis. Int J Cell Biol 2012; 2012:434971. [PMID: 22745639 PMCID: PMC3382959 DOI: 10.1155/2012/434971] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/01/2012] [Indexed: 02/07/2023] Open
Abstract
The integrity of the vascular endothelium of the blood-brain barrier (BBB) is central to cerebrovascular homeostasis. Given the function of the BBB as a physical and metabolic barrier that buffers the systemic environment, oxidative damage to the endothelial monolayer will have significant deleterious impact on the metabolic, immunological, and neurological functions of the brain. Glutathione (GSH) is a ubiquitous major thiol within mammalian cells that plays important roles in antioxidant defense, oxidation-reduction reactions in metabolic pathways, and redox signaling. The existence of distinct GSH pools within the subcellular organelles supports an elegant mode for independent redox regulation of metabolic processes, including those that control cell fate. GSH-dependent homeostatic control of neurovascular function is relatively unexplored. Significantly, GSH regulation of two aspects of endothelial function is paramount to barrier preservation, namely, GSH protection against oxidative endothelial cell injury and GSH control of postdamage cell proliferation in endothelial repair and/or wound healing. This paper highlights our current insights and hypotheses into the role of GSH in cerebral microvascular biology and pathobiology with special focus on endothelial GSH and vascular integrity, oxidative disruption of endothelial barrier function, GSH regulation of endothelial cell proliferation, and the pathological implications of GSH disruption in oxidative stress-associated neurovascular disorders, such as diabetes and stroke.
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Accurate measurement of reduced glutathione in gamma-glutamyltransferase-rich brain microvessel fractions. Brain Res 2011; 1369:95-102. [DOI: 10.1016/j.brainres.2010.10.100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 10/26/2010] [Accepted: 10/27/2010] [Indexed: 11/18/2022]
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Transcriptomic screening of microvascular endothelial cells implicates novel molecular regulators of vascular dysfunction after spinal cord injury. J Cereb Blood Flow Metab 2008; 28:1771-85. [PMID: 18612314 PMCID: PMC2756605 DOI: 10.1038/jcbfm.2008.76] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microvascular dysfunction is a critical pathology that underlies the evolution of secondary injury mechanisms after traumatic spinal cord injury (SCI). However, little is known of the molecular regulation of endothelial cell (EC) plasticity observed acutely after injury. One reason for this is the relative lack of methods to quickly and efficiently obtain highly enriched spinal microvascular ECs for high-throughput molecular and biochemical analyses. Adult C57Bl/6 mice received an intravenous injection of fluorescein isothiocyanate (FITC)-conjugated Lycopersicon esculentum lectin, and FITC-lectin-bound spinal microvessels were greatly enriched by fluorescence-activated cell sorter (FACS) purification. This technique allows for rapid (<1.5 h postmortem) isolation of spinal cord microvascular ECs (smvECs). The results from cell counting, reverse-transcription polymerase chain reaction (RT-PCR), and western blot analyses show a high degree of EC enrichment at mRNA and protein levels. Furthermore, a focused EC biology microarray analysis identified multiple mRNAs dramatically increased in the EC compartment 24 h after SCI, which is a time point associated with the pathologic loss of spinal vasculature. These included thrombospondin-1, CCL5/RANTES, and urokinase plasminogen activator, suggesting they may represent targets for therapeutic intervention. Furthermore, these novel methodologic approaches will likely facilitate the discovery of molecular regulators of endothelial dysfunction in a variety of central nervous system (CNS) disorders including stroke and other neurodegenerative diseases having a vascular component.
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Okamura T, Kikuchi T, Fukushi K, Arano Y, Irie T. A novel noninvasive method for assessing glutathione-conjugate efflux systems in the brain. Bioorg Med Chem 2007; 15:3127-33. [PMID: 17344048 DOI: 10.1016/j.bmc.2007.02.045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 02/20/2007] [Accepted: 02/21/2007] [Indexed: 11/19/2022]
Abstract
Brain efflux systems export such conjugated metabolites as glutathione (GSH) and glucuronate conjugates, generated by the detoxification process, from the brain and serve to protect the brain from harmful metabolites. The intracerebral injection of a radiolabeled conjugate is a useful technique to assess brain efflux systems; however, this technique is not applicable to humans. Hence, we devised a novel noninvasive approach for assessing GSH-conjugate efflux systems using positron emission tomography. Here, we investigated whether or not a designed proprobe can deliver its GSH conjugate into the brain. Radiolabeled 6-chloro-7-methylpurine (7m6CP) was designed as the proprobe, and [(14)C]7m6CP was prepared by the reaction of 6-chloropurine with [(14)C]CH(3)I as a model of [(11)C]CH(3)I. The radiochemical yield and purity of [(14)C]7m6CP were 10-20% and greater than 99%, respectively. High brain uptake (0.8% ID/g) at 1 min was observed, followed by gradual radioactivity clearance from the brain for 5-60 min after the injection of [(14)C]7m6CP into rats. Analysis of metabolites confirmed that the presence of [(14)C]7m6CP was hardly observed, and 80% of the radioactivity was identical to its GSH conjugate for 15-60 min. The brain radioactivity was single-exponentially decreased during the period of 15-60 min post-injection of [(14)C]7m6CP, and the first-order efflux rate constant of the conjugate, estimated from the slope, was 0.0253 min(-1). These results showed that (1) [(14)C]7m6CP readily entered the brain, (2) it efficiently and specifically transformed to the GSH conjugate within the brain, and (3) after [(14)C]7m6CP disappearance, the clearance of radioactivity represented the only efflux of GSH conjugate. We conclude that 7m6CP can deliver the GSH conjugate into the brain and would be useful for assessing GSH-conjugate efflux systems noninvasively.
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Affiliation(s)
- Toshimitsu Okamura
- Probe Research Section, Department of Molecular Probe, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan
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Rathinam ML, Watts LT, Stark AA, Mahimainathan L, Stewart J, Schenker S, Henderson GI. Astrocyte control of fetal cortical neuron glutathione homeostasis: up-regulation by ethanol. J Neurochem 2006; 96:1289-300. [PMID: 16464233 DOI: 10.1111/j.1471-4159.2006.03674.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ethanol increases apoptotic neuron death in the developing brain and at least part of this may be mediated by oxidative stress. In cultured fetal rat cortical neurons, Ethanol increases levels of reactive oxygen species (ROS) within minutes of exposure and reduces total cellular glutathione (GSH) shortly thereafter. This is followed by onset of apoptotic cell death. These responses to Ethanol can be blocked by elevating neuron GSH with N-acetylcysteine or by co-culturing neurons with neonatal cortical astrocytes. We describe here mechanisms by which the astrocyte-neuron gamma-glutamyl cycle is up-regulated by Ethanol, enhancing control of neuron GSH in response to the pro-oxidant, Ethanol. Up to 6 days of Ethanol exposure had no consistent effects on activities of gamma-glutamyl cysteine ligase or glutathione synthetase, and GSH content remained unchanged (p < 0.05). However, glutathione reductase was increased with 1 and 2 day Ethanol exposures, 25% and 39% for 2.5 and 4.0 mg/mL Ethanol by 1 day, and 11% and 16% for 2.5 and 4.0 mg/mL at 2 days, respectively (p < 0.05). A 24 h exposure to 4.0 mg/mL Ethanol increased GSH efflux from astrocyte up to 517% (p < 0.05). Ethanol increased both gamma-glutamyl transpeptidase expression and activity on astrocyte within 24 h of exposure (40%, p = 0.05 with 4.0 mg/mL) and this continued for at least 4 days of Ethanol treatment. Aminopeptidase N activity on neurons increased by 62% and 55% within 1 h of Ethanol for 2.5 and 4.0 mg/mL concentration, respectively (p < 0.05), remaining elevated for 24 h of treatment. Thus, there are at least three key points of the gamma-glutamyl cycle that are up-regulated by Ethanol, the net effect being to enhance neuron GSH homeostasis, thereby protecting neurons from Ethanol-mediated oxidative stress and apoptotic death.
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Affiliation(s)
- Mary Latha Rathinam
- Department of Medicine, Division of Gastroenterology and Nutrition, The University of Texas Health Science Center, San Antonio, Texas, USA
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Dasgupta A, Das S, Sarkar PK. Thyroid hormone stimulates γ-glutamyl transpeptidase in the developing rat cerebra and in astroglial cultures. J Neurosci Res 2005; 82:851-7. [PMID: 16302185 DOI: 10.1002/jnr.20657] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Hypothyroidism in the developing rat brain is associated with enhanced oxidative stress, one of the earliest manifestations of which is a decline in the level of glutathione (GSH). To investigate the role of thyroid hormone (TH) on GSH homeostasis, the effect of TH on gamma-glutamyl transpeptidase (gammaGT), the key enzyme involved in the catalysis of GSH, was studied. Hypothyroidism declined the specific activity of cerebral gammaGT at all postnatal ages examined (postnatal day 1-20) with a maximum inhibition of 42% at postnatal day 10. Intraperitoneal injection of TH to 15-day-old rat pups increased the specific activity of gammaGT by 25-30% within 4-6 hr. Treatment of primary cultures of astrocytes by TH also enhanced the specific activity of gammaGT by 30-40% within 4-6 hr. The induction of gammaGT by TH was blocked by actinomycin D or cycloheximide. gammaGT is an ectoenzyme that is normally involved in the catabolism of GSH released by astrocytes. In the presence of the gammaGT-inhibitor, acivicin, GSH released in the culture medium of astrocytes increased linearly for at least 6 hr and TH had no effect on this accumulation pattern. In the absence of acivicin, GSH content of the medium from TH-treated cells was significantly lower than that of untreated controls due to activation of gammaGT by TH and a faster processing of GSH. Because the products of gammaGT reaction are putative precursors for neuronal GSH, the activation of gammaGT by TH may be conducive to GSH synthesis in neurons and their protection from oxidative stress.
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Affiliation(s)
- Asmita Dasgupta
- Division of Neurobiology, Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
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Wallin C, Abbas AK, Tranberg M, Weber SG, Wigström H, Sandberg M. Searching for mechanisms of N-methyl-D-aspartate-induced glutathione efflux in organotypic hippocampal cultures. Neurochem Res 2003; 28:281-91. [PMID: 12608701 PMCID: PMC1475825 DOI: 10.1023/a:1022381318126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
N-Methyl-D-aspartate (NMDA)-receptor stimulation evoked a selective and partly delayed elevated efflux of glutathione, phosphoethanolamine, and taurine from organotypic rat hippocampus slice cultures. The protein kinase inhibitors H9 and staurosporine had no effect on the efflux. The phospholipase A2 inhibitors quinacrine and 4-bromophenacyl bromide, as well as arachidonic acid, a product of phospholipase A2 activity, did not affect the stimulated efflux. Polymyxin B, an antimicrobal agent that inhibits protein kinase C, and quinacrine in high concentration (500 microM), blocked efflux completely. The stimulated efflux after but not during NMDA incubation was attenuated by a calmodulin antagonist (W7) and an anion transport inhibitor (DNDS). Omission of calcium increased the spontaneous efflux with no or small additional effects by NMDA. In conclusion, NMDA receptor stimulation cause an increased selective efflux of glutathione, phosphoethanolamine and taurine in organotypic cultures of rat hippocampus. The efflux may partly be regulated by calmodulin and DNDS sensitive channels.
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Affiliation(s)
- Camilla Wallin
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Abdul-Karim Abbas
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Mattias Tranberg
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Stephen G. Weber
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Holger Wigström
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
| | - Mats Sandberg
- Department of Medical Biophysics, University of Göteborg, Medicinaregatan 11, S-405 30 Göteborg, Sweden
- Address reprint requests to: Mats Sandberg, Tel: (46)-31-7733395; Fax: (46)-31-7733558; E-mail:
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Hemmings SJ, Takaya S. Sucrose feeding effects inhibition of gamma-glutamyltranspeptidase in the liver of the rat: possible mediation by thyroid hormone. Int J Biochem Cell Biol 2003; 35:51-60. [PMID: 12467647 DOI: 10.1016/s1357-2725(02)00088-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effect of sucrose on Fischer 344 rat liver gamma-glutamyltranspeptidase (gammaGT) was studied: in adults fed sucrose for 3 weeks; and rats exposed to sucrose from the 18th day of gestation to the 40th day after birth. Rats fed regular rodent chow served as controls. Sucrose caused mild lipemia; and in the liver an increase in size and fat build-up without damage. In adult sucrose-fed rats, compared to controls, plasma glucose levels were increased: 1.12-, 1.40- and 1.13-fold after 24, 48h and 3 week consumption of sucrose, respectively. Insulin levels were unaltered for the first week of sucrose consumption but increased from control levels: 16% at 1 week, and 2.0-fold at 3 weeks. The T3 levels were comparable to control levels 24h after the sucrose was started and were increased: 1.22-, 1.13- and 1.12-fold at 48h, 1 and 3 weeks, respectively. The T4 levels were comparable at all time points between sucrose-fed and control rats. Liver gammaGT activity exhibited a steady decrease from control levels: after 24, 48h, 1 and 3 weeks of sucrose feeding the decrease was 5, 8, 21 and 37%, respectively in homogenates; and 10, 17, 24 and 41%, respectively in plasma membranes. Perinatal sucrose exposure effected in 40-day-old rats, compared controls: a 1.09-fold increase in plasma glucose; no change in plasma insulin; an increase of 1.15- and 1.39-fold in plasma levels of total and free T3, respectively; a decrease of 20 and 14% in plasma levels of total and free T4, respectively. gammaGT activity was decreased in liver plasma membranes isolated from sucrose-exposed rats relative to those of control: 80% in the male; 82% in the female. Relative specific activities of gammaGT were the same in both males: 15.4 and 16.1 in control and sucrose-exposed male rats, respectively; and females: 14.1 and 15.4 in control and sucrose-exposed female rats, respectively. gammaGT was 2-fold higher in the livers of female relative to male rats in sucrose-exposed and control groups. Kidney gammaGT activities were the same in control and sucrose-exposed rats. The involvement of T3 in the sucrose-induced decrease in liver gammaGT is discussed.
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Affiliation(s)
- Susan J Hemmings
- Department of Physiology, College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5.
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