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Costa CF, Lismont C, Chornyi S, Koster J, Li H, Hussein MAF, Van Veldhoven PP, Waterham HR, Fransen M. The solute carrier SLC25A17 sustains peroxisomal redox homeostasis in diverse mammalian cell lines. Free Radic Biol Med 2024; 212:241-254. [PMID: 38159891 DOI: 10.1016/j.freeradbiomed.2023.12.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/01/2023] [Accepted: 12/24/2023] [Indexed: 01/03/2024]
Abstract
Despite the crucial role of peroxisomes in cellular redox maintenance, little is known about how these organelles transport redox metabolites across their membrane. In this study, we sought to assess potential associations between the cellular redox landscape and the human peroxisomal solute carrier SLC25A17, also known as PMP34. This carrier has been reported to function as a counter-exchanger of adenine-containing cofactors such as coenzyme A (CoA), dephospho-CoA, flavin adenine dinucleotide, nicotinamide adenine dinucleotide (NAD+), adenosine 3',5'-diphosphate, flavin mononucleotide, and adenosine monophosphate. We found that inactivation of SLC25A17 resulted in a shift toward a more reductive state in the glutathione redox couple (GSSG/GSH) across HEK-293 cells, HeLa cells, and SV40-transformed mouse embryonic fibroblasts, with variable impact on the NADPH levels and the NAD+/NADH redox couple. This phenotype could be rescued by the expression of Candida boidinii Pmp47, a putative SLC25A17 orthologue reported to be essential for the metabolism of medium-chain fatty acids in yeast peroxisomes. In addition, we provide evidence that the alterations in the redox state are not caused by changes in peroxisomal antioxidant enzyme expression, catalase activity, H2O2 membrane permeability, or mitochondrial fitness. Furthermore, treating control and ΔSLC25A17 cells with dehydroepiandrosterone, a commonly used glucose-6-phosphate dehydrogenase inhibitor affecting NADPH regeneration, revealed a kinetic disconnection between the peroxisomal and cytosolic glutathione pools. Additionally, these experiments underscored the impact of SLC25A17 loss on peroxisomal NADPH metabolism. The relevance of these findings is discussed in the context of the still ambiguous substrate specificity of SLC25A17 and the recent observation that the mammalian peroxisomal membrane is readily permeable to both GSH and GSSG.
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Affiliation(s)
- Cláudio F Costa
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium
| | - Celien Lismont
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium
| | - Serhii Chornyi
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Centers, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Janet Koster
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Centers, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Hongli Li
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium
| | - Mohamed A F Hussein
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium; Department of Biochemistry, Faculty of Pharmacy, Assiut University, 71515, Asyut, Egypt
| | - Paul P Van Veldhoven
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium
| | - Hans R Waterham
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam University Medical Centers, University of Amsterdam, 1105 AZ, Amsterdam, the Netherlands
| | - Marc Fransen
- Laboratory of Peroxisome Biology and Intracellular Communication, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven, 3000, Leuven, Belgium.
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Davies R, Minhas S, Jayasena CN. The role of seminal reactive oxygen species assessment in the setting of infertility and early pregnancy loss. World J Urol 2023; 41:3257-3265. [PMID: 37452867 PMCID: PMC10632302 DOI: 10.1007/s00345-023-04472-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/31/2023] [Indexed: 07/18/2023] Open
Abstract
The male contribution to a couple suffering with adverse early pregnancy outcomes is being increasingly investigated. Seminal oxidative stress is considered to cause sperm DNA damage, thus affecting the functional capacity of the sperm. Multiple lines of evidence support an association between elevated seminal reactive oxygen species (ROS) and infertility. In the setting of assisted reproduction various factors in the in vitro environment, differing from the in vivo environment, may exacerbate oxidative stress. Furthermore, seminal ROS levels have been found to be higher in the male partners of couple's affected by both spontaneous and recurrent pregnancy loss. There are several methods by which to assess ROS levels however they are costly, inconsistent and their incorporation into clinical practice is unclear. The value of ROS assessment lies in the ability to plan targeted therapies to improve pregnancy and live birth rates. As such, further robust study is required before firm conclusions can be made to inform clinical practice. We aim to review the available evidence regarding the role of seminal ROS in infertility and pregnancy loss.
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Affiliation(s)
- Rhianna Davies
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Suks Minhas
- Department of Urology, Charing Cross Hospital, Imperial College NHS Trust, London, UK
| | - Channa N Jayasena
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
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Davies R, Jayasena CN, Rai R, Minhas S. The Role of Seminal Oxidative Stress in Recurrent Pregnancy Loss. Antioxidants (Basel) 2023; 12:antiox12030723. [PMID: 36978971 PMCID: PMC10045000 DOI: 10.3390/antiox12030723] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 03/17/2023] Open
Abstract
Recurrent pregnancy loss is a distressing condition affecting 1–2% of couples. Traditionally investigations have focused on the female, however more recently researchers have started to explore the potential contribution of the male partner. Seminal reactive oxygen species have a physiological function in male reproduction but in excess are suspected to generate structural and functional damage to the sperm. Evidence is mounting to support an association between elevated seminal reaction oxygen species and recurrent pregnancy loss. Studies suggest that the rates of sperm DNA damage are higher in the male partners of women affected by recurrent pregnancy loss compared with unaffected men. However, the available pool of data is conflicting, and interpretation is limited by the recent change in nomenclature and the heterogeneity of study methodologies. Furthermore, investigation into the effects of oxidative stress on the epigenome show promise. The value of antioxidant therapy in the management of recurrent pregnancy loss currently remains unclear.
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Affiliation(s)
- Rhianna Davies
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London W12 0NN, UK
| | - Channa N. Jayasena
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London W12 0NN, UK
| | - Raj Rai
- Department of Obstetrics and Gynaecology, St Mary’s Hospital, Imperial College NHS Trust, London W2 1NY, UK
| | - Suks Minhas
- Department of Urology, Charing Cross Hospital, Imperial College NHS Trust, London W6 8RF, UK
- Correspondence:
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Gupte R, Dhagia V, Rocic P, Ochi R, Gupte SA. Glucose-6-phosphate dehydrogenase increases Ca 2+ currents by interacting with Ca v1.2 and reducing intrinsic inactivation of the L-type calcium channel. Am J Physiol Heart Circ Physiol 2020; 319:H144-H158. [PMID: 32442021 DOI: 10.1152/ajpheart.00727.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Pyridine nucleotides, such as NADPH and NADH, are emerging as critical players in the regulation of heart and vascular function. Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme in the pentose phosphate pathway, is the primary source and regulator of cellular NADPH. In the current study, we have identified two isoforms of G6PD (slow and fast migrating) and functionally characterized the slow migrating isoform of G6PD (G6PD545) in bovine and human arteries. We found that G6PD545 is eluted in the caveolae fraction of vascular smooth muscle (VSM) and has a higher maximum rate of reaction (Vmax: 1.65-fold) than its fast migrating isoform (G6PD515). Interestingly, caveolae G6PD forms a complex with the pore-forming α1C-subunit of the L-type Ca2+ channel, Cav1.2, as demonstrated by a proximity ligation assay in fixed VSMCs. Additionally, Förster resonance energy transfer (FRET) analysis of HEK293-17T cells cotransfected with red fluorescent protein (RFP)-tagged G6PD545 (C-G6PD545) and green fluorescent protein (GFP)-tagged Cav1.2-(Cav1.2-GFP) demonstrated strong FRET signals as compared with cells cotransfected with Cav1.2-GFP and C-G6PD515. Furthermore, L-type Ca2+ channel conductance was larger and the voltage-independent component of availability (c1) was augmented in C-G6PD545 and Cav1.2-GFP cotransfectants compared with those expressing Cav1.2-GFP alone. Surprisingly, epiandrosterone, a G6PD inhibitor, disrupted the G6PD-Cav1.2 complex, also decreasing the amplitude of L-type Ca2+ currents and window currents, thereby reducing the availability of the c1 component. Moreover, overexpression of adeno-G6PD545-GFP augmented the KCl-induced contraction in coronary arteries compared with control. To determine whether overexpression of G6PD had any clinical implication, we investigated its activity in arteries from patients and rats with metabolic syndrome and found that G6PD activity was high in this disease condition. Interestingly, epiandrosterone treatment reduced elevated mean arterial blood pressure and peripheral vascular resistance in metabolic syndrome rats, suggesting that the increased activity of G6PD augmented vascular contraction and blood pressure in the metabolic syndrome. These data suggest that the novel G6PD-Cav1.2 interaction, in the caveolae fraction, reduces intrinsic voltage-dependent inactivation of the channel and contributes to regulate VSM L-type Ca2+ channel function and Ca2+ signaling, thereby playing a significant role in modulating vascular function in physiological/pathophysiological conditions.NEW & NOTEWORTHY In this study we have identified a novel isozyme of glucose-6-phosphate dehydrogenase (G6PD), a metabolic enzyme, that interacts with and contributes to regulate smooth muscle cell l-type Ca2+ ion channel function, which plays a crucial role in vascular function in physiology and pathophysiology. Furthermore, we demonstrate that expression and activity of this novel G6PD isoform are increased in arteries of individuals with metabolic syndrome and in inhibition of G6PD activity in rats of metabolic syndrome reduced blood pressure.
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Affiliation(s)
- Rakhee Gupte
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Biochemistry, College of Medicine, University of South Alabama, Mobile, Alabama
| | - Vidhi Dhagia
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Petra Rocic
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Biochemistry, College of Medicine, University of South Alabama, Mobile, Alabama
| | - Rikuo Ochi
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Biochemistry, College of Medicine, University of South Alabama, Mobile, Alabama
| | - Sachin A Gupte
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Biochemistry, College of Medicine, University of South Alabama, Mobile, Alabama
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Belew GD, Di Nunzio G, Tavares L, Silva JG, Torres AN, Jones JG. Estimating pentose phosphate pathway activity from the analysis of hepatic glycogen 13 C-isotopomers derived from [U- 13 C]fructose and [U- 13 C]glucose. Magn Reson Med 2020; 84:2765-2771. [PMID: 32301167 DOI: 10.1002/mrm.28286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 12/26/2022]
Abstract
PURPOSE The pentose phosphate pathway (PPP) is an important component of hepatic intermediary metabolism. Jin et al developed an elegant 13 C-NMR method for measuring hepatic PPP flux by quantifying the distribution of glucose 13 C-isotopomers formed from [U-13 C]glycerol. We demonstrate that this approach can be extended to exogenous [U-13 C]fructose and [U-13 C]glucose precursors by 13 C-NMR analysis of glycogen. METHODS Twelve male C57BL/6 mice fed standard chow were provided a 55/45 mixture of fructose and glucose at 30% w/v in the drinking water for 18 wk. On the evening before sacrifice, the fructose component was enriched with 20% [U-13 C]fructose for 6 mice, while the glucose component was enriched with 20% [U-13 C]glucose for the remaining 6 mice. Mice were allowed to feed and drink naturally overnight, and then, euthanized. Livers were freeze-clamped and glycogen was extracted and derivatized for 13 C NMR spectroscopy. Flux of each sugar into the PPP relative to its incorporation into glycogen was quantified from selected 13 C glycogen isotopomer ratios. RESULTS Both [U-13 C]fructose and [U-13 C]glucose precursors yielded glycogen 13 C-isotopomer distributions that were characteristic of PPP activity. The fraction of [U-13 C]glucose utilized by the PPP relative to its conversion to glycogen via the direct pathway was 14 ± 1%, while that from [U-13 C]fructose relative to its conversion to glycogen via the indirect pathway was significantly lower (10 ± 1%, P = .00032). CONCLUSIONS Hepatic PPP fluxes from both [U-13 C]glucose and [U-13 C]fructose precursors were assessed by 13 C NMR analysis of glycogen 13 C-isotopomers. Glucose-6-phosphate generated via glucokinase and the direct pathway is preferentially utilized by the PPP.
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Affiliation(s)
- Getachew D Belew
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Giada Di Nunzio
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ludgero Tavares
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Joao G Silva
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Alejandra N Torres
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - John G Jones
- Center for Neurosciences and Cell Biology, University of Coimbra, Coimbra, Portugal
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Agarwal A, Rana M, Qiu E, AlBunni H, Bui AD, Henkel R. Role of oxidative stress, infection and inflammation in male infertility. Andrologia 2018; 50:e13126. [DOI: 10.1111/and.13126] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/08/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023] Open
Affiliation(s)
- Ashok Agarwal
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
| | - Mohit Rana
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
| | - Emily Qiu
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
| | - Hashem AlBunni
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
| | - Albert D. Bui
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
- Ohio University Heritage College of Osteopathic Medicine; Athens Ohio
| | - Ralf Henkel
- American Center for Reproductive Medicine; Cleveland Clinic; Cleveland Ohio
- Department of Medical Biosciences; University of the Western Cape; Bellville South Africa
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7
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Boren J, Ramos-Montoya A, Bosch KS, Vreeling H, Jonker A, Centelles JJ, Cascante M, Frederiks WM. In Situ Localization of Transketolase Activity in Epithelial Cells of Different Rat Tissues and Subcellularly in Liver Parenchymal Cells. J Histochem Cytochem 2016; 54:191-9. [PMID: 16116031 DOI: 10.1369/jhc.5a6745.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Metabolic mapping of enzyme activities (enzyme histochemistry) is an important tool to understand (patho)physiological functions of enzymes. A new enzyme histochemical method has been developed to detect transketolase activity in situ in various rat tissues and its ultrastructural localization in individual cells. In situ detection of transketolase is important because this multifunctional enzyme has been related with diseases such as cancer, diabetes, Alzheimer's disease, and Wernicke-Korsakoff's syndrome. The proposed method is based on the tetrazolium salt method applied to unfixed cryostat sections in the presence of polyvinyl alcohol. The method appeared to be specific for transketolase activity when the proper control reaction is performed and showed a linear increase of the amount of final reaction product with incubation time. Transketolase activity was studied in liver, small intestine, trachea, tongue, kidney, adrenal gland, and eye. Activity was found in liver parenchyma, epithelium of small intestine, trachea, tongue, proximal tubules of kidney and cornea, and ganglion cells in medulla of adrenal gland. To demonstrate transketolase activity ultrastructurally in liver parenchymal cells, the cupper iron method was used. It was shown that transketolase activity was present in peroxisomes and at membranes of granular endoplasmic reticulum. This ultrastructural localization is similar to that of glucose-6-phosphate dehydrogenase activity, suggesting activity of the pentose phosphate pathway at these sites. It is concluded that the method developed for in situ localization of transketolase activity for light and electron microscopy is specific and allows further investigation of the role of transketolase in (proliferation of) cancer cells and other pathophysiological processes.
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Affiliation(s)
- Joan Boren
- Department of Cell Biology and Histology, Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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8
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Sabeti P, Pourmasumi S, Rahiminia T, Akyash F, Talebi AR. Etiologies of sperm oxidative stress. Int J Reprod Biomed 2016. [DOI: 10.29252/ijrm.14.4.231] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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9
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Saeed H, Ismaeil M, Embaby A, Ataya F, Malik A, Shalaby M, El-Banna S, Ali AAM, Bassiouny K. Overexpression, purification and enzymatic characterization of a recombinant Arabian camel Camelus dromedarius glucose-6-phosphate dehydrogenase. Protein Expr Purif 2015; 142:88-94. [PMID: 26363117 DOI: 10.1016/j.pep.2015.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 08/27/2015] [Accepted: 09/03/2015] [Indexed: 11/29/2022]
Abstract
In a previous study the full-length open reading frame of the Arabian camel, Camelus dromedarius liver cytosolic glucose-6-phosphate dehydrogenase (G6PD) cDNA was determined using reverse transcription polymerase chain reaction. The C. dromedarius cDNA was found to be 1545 nucleotides (accession number JN098421) that encodes a protein of 515 amino acids residues. In the present study, C. dromedarius recombinant G6PD was heterologously overexpressed in Escherichia coli BL21 (DE3) pLysS and purified by immobilized metal affinity fast protein liquid chromatography (FPLC) in a single step. The purity and molecular weight of the enzyme were analyzed on SDS-PAGE and the purified enzyme showed a single band on the gel with a molecular weight of 63.0 KDa. The specific activity was determined to be 2000 EU/mg protein. The optimum temperature and pH were found to be 60 °C and 7.4, respectively. The isoelectric point (pI) for the purified G6PD was determined to be 6.4. The apparent Km values for the two substrates NADP+ and G6P were found to be 23.2 μM and 66.7 μM, respectively. The far-UV circular dichroism (CD) spectra of G6PD showed that it has two minima at 208 and 222 nm as well as maxima at 193 nm which is characteristic of high content of α-helix. Moreover, the far-UV CD spectra of the G6PD in the presence or absence of NADP+ were nearly identical.
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Affiliation(s)
- Hesham Saeed
- Department of Biotechnology, Institute of Graduate Studies and Research, Alexandria University, Alexandria, Egypt.
| | - Mohammad Ismaeil
- Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; Protein Research Chair, Biochemistry Department, College of Science King Saud University, Bld. 5, P.O. Box 2454, Riyadh, Saudi Arabia
| | - Amira Embaby
- Department of Biotechnology, Institute of Graduate Studies and Research, Alexandria University, Alexandria, Egypt
| | - Farid Ataya
- Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; Molecular Biology Department, Genetic Engineering Division, National Research Centre, 33 El-Bohouth St. (former El-Tahrir St.), P.O. 12622, Dokki, Giza, Egypt
| | - Ajamaluddin Malik
- Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; Protein Research Chair, Biochemistry Department, College of Science King Saud University, Bld. 5, P.O. Box 2454, Riyadh, Saudi Arabia
| | - Manal Shalaby
- Genetic Engineering and Biotechnology Research Institute (GEBRI), City for Scientific Research and Technology Applications, New Borg Alarab City, Alexandria, Egypt
| | - Sabah El-Banna
- Department of Environmental Studies, Institute of Graduate Studies and Research, Alexandria University, Alexandria, Egypt
| | - Ahmed Abdelrahim Mohamed Ali
- Food and Agricultural Science, Plant Production Department, Biotechnology Laboratory, King Saud University, P.O. Box 2454, Riyadh, Saudi Arabia
| | - Khalid Bassiouny
- Molecular Biology Department, Genetic Engineering and Biotechnology Institute, University of Sadat City, Egypt
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Topal A, Atamanalp M, Oruç E, Kırıcı M, Kocaman EM. Apoptotic effects and glucose-6-phosphate dehydrogenase responses in liver and gill tissues of rainbow trout treated with chlorpyrifos. Tissue Cell 2015; 46:490-6. [PMID: 25438950 DOI: 10.1016/j.tice.2014.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 08/18/2014] [Accepted: 09/01/2014] [Indexed: 01/08/2023]
Abstract
We investigated apoptotic effects and changes in glucose-6-phosphate dehydrogenase (G6PD) enzyme activity in liver and gill tissues of fish exposed to chlorpyrifos. Three different chlorpyrifos doses (2.25, 4.5 and 6.75 μg/L) were administrated to rainbow trout at different time intervals (24, 48, 72 and 96 h). Acute exposure to chlorpyrifos showed time dependent decrease in G6PD enzyme activity at all concentrations (p < 0.05). Immunohistochemical results showed that chlorpyrifos caused mucous cell loss in gill tissue and apoptosis via caspase-3 activation in fish. The present study suggested that chlorpyrifos inhibits G6PD enzyme and causes mucous cell loss in gill and apoptosis in gill and liver tissues.
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Affiliation(s)
- Ahmet Topal
- Department of Basic Sciences, Faculty of Fisheries, Ataturk University, TR-25240 Erzurum, Turkey.
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Ast J, Stiebler AC, Freitag J, Bölker M. Dual targeting of peroxisomal proteins. Front Physiol 2013; 4:297. [PMID: 24151469 PMCID: PMC3798809 DOI: 10.3389/fphys.2013.00297] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 09/28/2013] [Indexed: 01/08/2023] Open
Abstract
Cellular compartmentalization into organelles serves to separate biological processes within the environment of a single cell. While some metabolic reactions are specific to a single organelle, others occur in more than one cellular compartment. Specific targeting of proteins to compartments inside of eukaryotic cells is mediated by defined sequence motifs. To achieve multiple targeting to different compartments cells use a variety of strategies. Here, we focus on mechanisms leading to dual targeting of peroxisomal proteins. In many instances, isoforms of peroxisomal proteins with distinct intracellular localization are encoded by separate genes. But also single genes can give rise to differentially localized proteins. Different isoforms can be generated by use of alternative transcriptional start sites, by differential splicing or ribosomal read-through of stop codons. In all these cases different peptide variants are produced, of which only one carries a peroxisomal targeting signal. Alternatively, peroxisomal proteins contain additional signals that compete for intracellular targeting. Dual localization of proteins residing in both the cytoplasm and in peroxisomes may also result from use of inefficient targeting signals. The recent observation that some bona fide cytoplasmic enzymes were also found in peroxisomes indicates that dual targeting of proteins to both the cytoplasm and the peroxisome might be more widespread. Although current knowledge of proteins exhibiting only partial peroxisomal targeting is far from being complete, we speculate that the metabolic capacity of peroxisomes might be larger than previously assumed.
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Affiliation(s)
- Julia Ast
- Department of Biology, Philipps University Marburg Marburg, Germany
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12
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Strijbis K, van den Burg J, Visser WF, van den Berg M, Distel B. Alternative splicing directs dual localization of Candida albicans 6-phosphogluconate dehydrogenase to cytosol and peroxisomes. FEMS Yeast Res 2011; 12:61-8. [PMID: 22094058 DOI: 10.1111/j.1567-1364.2011.00761.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Accepted: 11/05/2011] [Indexed: 11/28/2022] Open
Abstract
The pentose phosphate pathway (PPP) is the main source of NADPH in the cell and therefore essential for the maintenance of the redox balance and anabolic reactions. NADPH is produced by the two dehydrogenases in the oxidative branch of the PPP: glucose-6-phosphate dehydrogenase (Zwf1) and 6-phosphogluconate dehydrogenase (Gnd1). We observed that in the commensal fungus Candida albicans these two enzymes contain putative peroxisomal targeting signals (PTSs): Zwf1 has a putative PTS1, while the annotated intron of GND1 encodes a PTS2. By subcellular fractionation and fluorescence microscopy, we show that both enzymes have a dual localization in which the majority is cytosolic, but a small fraction is peroxisome associated. Analysis of GND1 transcripts revealed that dual targeting of Gnd1 is directed by alternative splicing resulting in two Gnd1 isoforms, one without targeting signals localized to the cytosol and one with an N-terminal PTS2 targeted to peroxisomes. To our knowledge, Gnd1 is the first example of dual targeting of a protein by alternative splicing in C. albicans. In silico analysis suggests that PTS-mediated peroxisomal targeting of Zwf1 and Gnd1 is conserved across closely related Candida species. We discuss putative functions of the peroxisomal oxidative PPP in these organisms.
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Affiliation(s)
- Karin Strijbis
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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13
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Frederiks WM, Bosch KS, Hoeben KA, van Marle J, Langbein S. Renal cell carcinoma and oxidative stress: The lack of peroxisomes. Acta Histochem 2010; 112:364-71. [PMID: 19500819 DOI: 10.1016/j.acthis.2009.03.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 03/11/2009] [Accepted: 03/12/2009] [Indexed: 11/28/2022]
Abstract
Oxidative stress plays an important role in carcinogenesis because of induction of DNA damage and its effects on intracellular signal transduction pathways. Here, we investigated the relationship between the defence against oxidative stress and human renal cell carcinoma that originates from proximal tubular epithelium. Oxygen insensitivity of the histochemical assay of glucose-6-phosphate dehydrogenase (G6PD) activity is a diagnostic tool for the detection of carcinomas. Its mechanism is based on high G6PD activity, reduced superoxide dismutase activity and reduced numbers of peroxisomes in the cancer cells. Five out of the 8 renal carcinomas studied here demonstrated oxygen insensitivity. These carcinomas showed high G6PD activity, whereas the other 3 carcinomas contained lower G6PD activity and were oxygen sensitive like non-cancer cells. Oxygen insensitivity did not correlate with tumour grade, staging or presence of metastases. Electron microscopy and immunofluorescence of catalase showed large numbers of peroxisomes in epithelial cells of proximal tubules of normal human kidney, whereas these organelles were completely absent in cancer cells of all carcinomas. As a consequence of the absence of peroxisomes in cancer cells, fatty acid metabolism is disturbed in addition to the altered glucose metabolism that is generally observed in cancer cells. Therefore, therapeutic approaches should focus on metabolism in addition to other strategies targeting signal transduction and angiogenesis.
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Affiliation(s)
- Wilma M Frederiks
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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Roy L, Laboissière S, Abdou E, Thibault G, Hamel N, Taheri M, Boismenu D, Lanoix J, Kearney RE, Paiement J. Proteomic analysis of the transitional endoplasmic reticulum in hepatocellular carcinoma: an organelle perspective on cancer. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:1869-81. [PMID: 20576523 DOI: 10.1016/j.bbapap.2010.05.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 05/05/2010] [Accepted: 05/18/2010] [Indexed: 02/06/2023]
Abstract
The transitional endoplasmic reticulum (tER) is composed of both rough and smooth ER membranes and thus participates in functions attributed to both these two subcellular compartments. In this paper we have compared the protein composition of tER isolated from dissected liver tumor nodules of aflatoxin B1-treated rats with that of tER from control liver. Tandem mass spectrometry (MS), peptide counts and immunoblot validation were used to identify and determine the relative expression level of proteins. Inhibitors of apoptosis (i.e. PGRMC1, tripeptidyl peptidase II), proteins involved in ribosome biogenesis (i.e. nucleophosmin, nucleolin), proteins involved in translation (i.e. eEF-2, and subunits of eIF-3), proteins involved in ubiquitin metabolism (i.e. proteasome subunits, USP10) and proteins involved in membrane traffic (i.e. SEC13-like 1, SEC23B, dynactin 1) were found overexpressed in tumor tER. Transcription factors (i.e. Pur-beta, BTF3) and molecular targets for C-Myc and NF-kappa B were observed overexpressed in tER from tumor nodules. Down-regulated proteins included cytochrome P450 proteins and enzymes involved in fatty acid metabolism and in steroid metabolism. Unexpectedly expression of the protein folding machinery (i.e. calreticulin) and proteins of the MHC class I peptide-loading complex did not change. Proteins of unknown function were detected in association with the tER and the novel proteins showing differential expression are potential new tumor markers. In many cases differential expression of proteins in tumor tER was comparable to that of corresponding genes reported in the Oncomine human database. Thus the molecular profile of tumor tER is different and this may confer survival advantage to tumor cells in cancer.
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Affiliation(s)
- Line Roy
- McGill University and Genome Quebec Innovation Centre, Proteomics Services, Genome Quebec, Montreal, Quebec, Canada
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15
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Frederiks WM, Vizan P, Bosch KS, Vreeling-Sindelárová H, Boren J, Cascante M. Elevated activity of the oxidative and non-oxidative pentose phosphate pathway in (pre)neoplastic lesions in rat liver. Int J Exp Pathol 2008; 89:232-40. [PMID: 18422600 DOI: 10.1111/j.1365-2613.2008.00582.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
(Pre)neoplastic lesions in livers of rats induced by diethylnitrosamine are characterized by elevated activity of the first irreversible enzyme of the oxidative branch of the pentose phosphate pathway (PPP), glucose-6-phosphate dehydrogenase (G6PD), for production of NADPH. In the present study, the activity of G6PD, and the other NADPH-producing enzymes, phosphogluconate dehydrogenase (PGD), isocitrate dehydrogenase (ICD) and malate dehydrogenase (MD) was investigated in (pre)neoplastic lesions by metabolic mapping. Transketolase (TKT), the reversible rate-limiting enzyme of the non-oxidative branch of the PPP, mainly responsible for ribose production, was studied as well. Activity of G6PD in (pre)neoplastic lesions was highest, whereas activity of PGD and ICD was only 10% and of MD 5% of G6PD activity, respectively. Glucose-6-phosphate dehydrogenase activity in (pre)neoplastic lesions was increased 25 times compared with extralesional parenchyma, which was also the highest activity increase of the four NADPH-producing dehydrogenases. Transketolase activity was 0.1% of G6PD activity in lesions and was increased 2.5-fold as compared with normal parenchyma. Transketolase activity was localized by electron microscopy exclusively at membranes of granular endoplasmic reticulum in rat hepatoma cells where G6PD activity is localized as well. It is concluded that NADPH in (pre)neoplastic lesions is mainly produced by G6PD, whereas elevated TKT activity in (pre)neoplastic lesions is responsible for ribose formation with concomitant energy supply by glycolysis. The similar localization of G6PD and TKT activity suggests the channelling of substrates at this site to optimize the efficiency of NADPH and ribose synthesis.
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Affiliation(s)
- Wilma M Frederiks
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, Amsterdam, The Netherlands.
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16
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Lavoie C, Paiement J. Topology of molecular machines of the endoplasmic reticulum: a compilation of proteomics and cytological data. Histochem Cell Biol 2008; 129:117-28. [PMID: 18172663 PMCID: PMC2228376 DOI: 10.1007/s00418-007-0370-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2007] [Indexed: 11/20/2022]
Abstract
The endoplasmic reticulum (ER) is a key organelle of the secretion pathway involved in the synthesis of both proteins and lipids destined for multiple sites within and without the cell. The ER functions to both co- and post-translationally modify newly synthesized proteins and lipids and sort them for housekeeping within the ER and for transport to their sites of function away from the ER. In addition, the ER is involved in the metabolism and degradation of specific xenobiotics and endogenous biosynthetic products. A variety of proteomics studies have been reported on different subcompartments of the ER providing an ER protein dictionary with new data being made available on many protein complexes of relevance to the biology of the ER including the ribosome, the translocon, coatomer proteins, cytoskeletal proteins, folding proteins, the antigen-processing machinery, signaling proteins and proteins involved in membrane traffic. This review examines proteomics and cytological data in support of the presence of specific molecular machines at specific sites or subcompartments of the ER.
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Affiliation(s)
- Christine Lavoie
- Département de pharmacologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC, Canada, J1H 5N4
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17
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Frederiks WM, Kümmerlin IPED, Bosch KS, Vreeling-Sindelárová H, Jonker A, Van Noorden CJF. NADPH production by the pentose phosphate pathway in the zona fasciculata of rat adrenal gland. J Histochem Cytochem 2007; 55:975-80. [PMID: 17533217 DOI: 10.1369/jhc.7a7222.2007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Biosynthesis of steroid hormones in the cortex of the adrenal gland takes place in smooth endoplasmic reticulum and mitochondria and requires NADPH. Four enzymes produce NADPH: glucose-6-phosphate dehydrogenase (G6PD), the key regulatory enzyme of the pentose phosphate pathway, phosphogluconate dehydrogenase (PGD), the third enzyme of that pathway, malate dehydrogenase (MDH), and isocitrate dehydrogenase (ICDH). However, the contribution of each enzyme to NADPH production in the cortex of adrenal gland has not been established. Therefore, activity of G6PD, PGD, MDH, and ICDH was localized and quantified in rat adrenocortical tissue using metabolic mapping, image analysis, and electron microscopy. The four enzymes have similar localization patterns in adrenal gland with highest activities in the zona fasciculata of the cortex. G6PD activity was strongest, PGD, MDH, and ICDH activity was approximately 60%, 15%, and 7% of G6PD activity, respectively. The K(m) value of G6PD for glucose-6-phosphate was two times higher than the K(m) value of PGD for phosphogluconate. As a consequence, virtual flux rates through G6PD and PGD are largely similar. It is concluded that G6PD and PGD provide the major part of NADPH in adrenocortical cells. Their activity is localized in the cytoplasm associated with free ribosomes and membranes of the smooth endoplasmic reticulum, indicating that NADPH-demanding processes related to biosynthesis of steroid hormones take place at these sites. Complete inhibition of G6PD by androsterones suggests that there is feedback regulation of steroid hormone biosynthesis via G6PD.
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Affiliation(s)
- Wilma M Frederiks
- Department of Cell Biology & Histology, Academic Medical Center, Amsterdam, The Netherlands
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18
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Frederiks WM, Vreeling-Sindelárová H, Van Noorden CJF. Loss of Peroxisomes Causes Oxygen Insensitivity of the Histochemical Assay of Glucose-6-Phosphate Dehydrogenase Activity to Detect Cancer Cells. J Histochem Cytochem 2006; 55:175-81. [PMID: 17101723 DOI: 10.1369/jhc.6a7068.2006] [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: 11/22/2022] Open
Abstract
Oxygen insensitivity of carcinoma cells and oxygen sensitivity of non-cancer cells in the histochemical assay of glucose-6-phosphate dehydrogenase (G6PD) enables detection of carcinoma cells in unfixed cell smears or cryostat sections of biopsies. The metabolic background of oxygen insensitivity is still not understood completely. In the present study, rat hepatocytes, rat hepatoma cells (FTO-2B), and human colon carcinoma cells (HT29) were used to elucidate these backgrounds. The residual activity in oxygen was 0%, 55%, and 80% in hepatocytes, hepatoma cells, and colon carcinoma cells, respectively. N-ethylmaleimide (NEM), a blocker of SH-groups, did not affect G6PD activity in both carcinoma cell types but reduced G6PD activity in hepatocytes by 40%. Ultrastructural localization of G6PD activity was exclusively in the cytoplasm of carcinoma cells, but in hepatocytes both in cytoplasm and peroxisomes. NEM abolished peroxisomal G6PD activity only. Histochemical assay of catalase activity demonstrated absence of peroxisomes in both carcinoma cell lines. It is concluded that absence of SH-sensitive G6PD activity in peroxisomes in cancer cells is responsible for the oxygen-insensitivity phenomenon.
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Affiliation(s)
- Wilma M Frederiks
- Department of Cell Biology and Histology, Academic Medical Center, Meibergdreef 15 1105 AZ, Amsterdam, The Netherlands.
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19
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Frederiks WM, van Marle J, van Oven C, Comin-Anduix B, Cascante M. Improved localization of glucose-6-phosphate dehydrogenase activity in cells with 5-cyano-2,3-ditolyl-tetrazolium chloride as fluorescent redox dye reveals its cell cycle-dependent regulation. J Histochem Cytochem 2005; 54:47-52. [PMID: 16046670 DOI: 10.1369/jhc.5a6663.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Since the introduction of cyano-ditolyl-tetrazolium chloride (CTC), a tetrazolium salt that gives rise to a fluorescent formazan after reduction, it has been applied to quantify activity of dehydrogenases in individual cells using flow cytometry. Confocal laser scanning microscopy (CLSM) showed that the fluorescent formazan was exclusively localized at the surface of individual cells and not at intracellular sites of enzyme activity. In the present study, the technique has been optimized to localize activity of glucose-6-phosphate dehydrogenase (G6PD) intracellularly in individual cells. Activity was demonstrated in cultured fibrosarcoma cells in different stages of the cell cycle. Cells were incubated for the detection of G6PD activity using a medium containing 6% (w/v) polyvinyl alcohol, 5 mM CTC, magnesium chloride, sodium azide, the electron carrier methoxyphenazine methosulphate, NADP, and glucose-6-phosphate. Before incubation, cells were permeabilized with 0.025% glutaraldehyde. Fluorescent formazan was localized exclusively in the cytoplasm of fibrosarcoma cells. The amount of fluorescent formazan in cells increased linearly with incubation time when measured with flow cytometry and CLSM. When combining the Hoechst staining for DNA with the CTC method for the demonstration of G6PD activity, flow cytometry showed that G6PD activity of cells in S phase and G2/M phase is 27 +/- 4% and 43 +/- 4% higher, respectively, than that of cells in G1 phase. CLSM revealed that cells in all phases of mitosis as well as during apoptosis contained considerably lower G6PD activity than cells in interphase. It is concluded that posttranslational regulation of G6PD is responsible for this cell cycle-dependent activity.
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Affiliation(s)
- Wilma M Frederiks
- Department of Cell Biology and Histology, Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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20
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Veitch N, Maugeri D, Cazzulo J, Lindqvist Y, Barrett M. Transketolase from Leishmania mexicana has a dual subcellular localization. Biochem J 2005; 382:759-67. [PMID: 15149284 PMCID: PMC1133835 DOI: 10.1042/bj20040459] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 04/29/2004] [Accepted: 05/19/2004] [Indexed: 11/17/2022]
Abstract
Transketolase has been characterized in Leishmania mexicana. A gene encoding this enzyme was identified and cloned. The gene was expressed in Escherichia coli and the protein was purified and characterized. An apparent K(m) of 2.75 mM for ribose 5-phosphate was determined. X-ray crystallography was used to determine the three-dimensional structure of the enzyme to a resolution of 2.2 A (1 A identical with 0.1 nm). The C-terminus of the protein contains a type-1 peroxisome-targeting signal, suggestive of a possible glycosomal subcellular localization. Subcellular localization experiments performed with promastigote forms of the parasite revealed that the protein was predominantly cytosolic, although a significant component of the total activity was associated with the glycosomes. Transketolase is thus the first enzyme of the nonoxidative branch of the pentose phosphate pathway whose presence has been demonstrated in a peroxisome-like organelle.
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Affiliation(s)
- Nicola J. Veitch
- *Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Dante A. Maugeri
- †Instituto de Investigaciones Biotecnologicas (IIB-INTECH), Universidad Nacional de General San Martin – CONICET, 1650 San Martin, Buenos Aires, Argentina
| | - Juan Jose Cazzulo
- †Instituto de Investigaciones Biotecnologicas (IIB-INTECH), Universidad Nacional de General San Martin – CONICET, 1650 San Martin, Buenos Aires, Argentina
| | - Ylva Lindqvist
- ‡Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- To whom correspondence should be addressed (email either or )
| | - Michael P. Barrett
- *Division of Infection and Immunity, Institute of Biomedical and Life Sciences, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
- To whom correspondence should be addressed (email either or )
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21
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Schellens JPM, Vreeling-Sindelárová H, Frederiks WM. Electron microscopical enzyme histochemistry on unfixed tissues and cells. Bridging the gap between LM and EM enzyme histochemistry. Acta Histochem 2003; 105:1-19. [PMID: 12666984 DOI: 10.1078/0065-1281-00697] [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: 11/18/2022]
Abstract
In principle, enzyme histochemistry should be performed on unfixed tissues and cells to avoid inhibition of enzyme activity by chemical fixation. For EM enzyme histochemistry, unfixed tissue specimens include fresh tissue blocks, non-frozen tissue chopper sections, cryostat sections and cell preparations. Studies on localization of enzyme activity at the ultrastructural level in unfixed specimens, be it fresh or frozen, are reviewed here. Preservation of ultrastructural morphology is discussed with special attention to the effects of freezing. It is concluded that unfixed cryostat sections are the best alternative for EM histochemistry of tissues, when interposing a semipermeable membrane in between cryostat section and gelled incubation medium. It is an adequate method to preserve structural integrity of unfixed tissue on the one hand and to avoid inactivation of the enzyme by chemical fixation on the other. For EM cytochemistry on individual cells, a better preservation of ultrastructure may be obtained because freezing can be avoided, but mild pretreatment with a fixative or detergent may be necessary to permeabilize cellular membranes for demonstration of intracellular enzyme activity.
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Affiliation(s)
- Jacques P M Schellens
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, Amsterdam, The Netherlands
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22
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Ramos KL, Colquhoun A. Protective role of glucose-6-phosphate dehydrogenase activity in the metabolic response of C6 rat glioma cells to polyunsaturated fatty acid exposure. Glia 2003; 43:149-66. [PMID: 12838507 DOI: 10.1002/glia.10246] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Polyunsaturated fatty acids (PUFAs) can influence tumor growth and migration, both in vitro and in vivo. The PUFA gamma-linolenic acid (GLA) has been reported to improve the poor prognosis associated with human gliomas, although its effects at sublethal concentrations on residual cells postsurgery are poorly understood. The study investigated the effects sublethal PUFA doses (90 or 150 microM) may have on rat C6 glioma cell energy metabolism, since an adequate energy supply is essential for cell proliferation, migration, and apoptosis. Of note was the identification of mitochondrial heterogeneity in relation to the mitochondrial membrane potential (MMP), which has been suggested but unproven in previous studies. GLA and eicosapentaenoic acid (EPA) caused significant changes in cellular fatty acid composition and increased the percentage of cells with a low MMP after a 96-h exposure period. The presence of PUFAs inhibited C6 cell proliferation and migration, although apoptosis was not induced. The protein expression and activity of glucose-6-phosphate dehydrogenase was increased after 96-h incubation with 90 microM GLA and EPA and would allow redox regulation through increased NADPH production, permitting the maintenance of adequate intracellular reduced glutathione concentrations and limiting rates of lipid peroxidation and reactive oxygen species generation. Neither NADP(+)-isocitrate dehydrogenase nor NADP(+)-malate dehydrogenase activity responded to PUFAs, suggesting it is glucose-6-phosphate dehydrogenase that is the principal source of NADPH in C6 cells. These data compliment studies showing that higher concentrations of GLA induced glioma cell death and tumor regression and suggest that GLA treatment could be useful for the inhibition of residual cell proliferation and migration after surgical removal of the tumor mass.
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Affiliation(s)
- Karina Lawrence Ramos
- Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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23
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Biagiotti E, Malatesta M, Capellacci S, Fattoretti P, Gazzanelli G, Ninfali P. Quantification of G6PD in small and large intestine of rat during aging. Acta Histochem 2003; 104:225-34. [PMID: 12389736 DOI: 10.1078/0065-1281-00667] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Numerous studies have demonstrated a decrease in glucose-6-phosphate dehydrogenase (G6PD) activity during aging in many cell types, including red blood cells, fibroblasts and lens cells. Moreover, the intracellular activity of G6PD has been shown to be regulated by binding to cell organelles. To investigate whether binding of G6PD to cell organelles is related with the decrease in its activity during aging, distribution patterns of G6PD activity and protein were assessed in small (SI) and large (LI) intestine of 3-month-old and 28-month-old rats. Enzyme activity, as measured spectrophotometrically, did not show any significant change with aging in SI or LI. Enzyme histochemistry, performed by subtracting activity staining of 6-phosphogluconate dehydrogenase (6PGD) from that of G6PD, showed a lower net G6PD activity in SI and LI epithelium of old rats in comparison with young rats. G6PD activity did not change significantly with aging in the muscularis externa of SI and LI. Immunoelectron microscopic analysis of G6PD protein allowed us to measure the density of G6PD molecules in cellular compartments, and the fraction of enzyme bound to cell organelles. In SI and LI epithelia, density of G6PD molecules was higher in old rats than in young rats; however, the fraction of enzyme bound to cell organelles also increased with aging. These data suggest that G6PD activity in epithelium of SI and LI decreases with aging due to the accumulation of significant amounts of enzyme bound to cell organelles, a condition which makes it less active than the soluble enzyme.
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Affiliation(s)
- Enrica Biagiotti
- Institute of Biochemistry G. Fornaini, University of Urbino, Italy
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24
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Frederiks WM, Bosch KS, De Jong JSSG, Van Noorden CJF. Post-translational regulation of glucose-6-phosphate dehydrogenase activity in (pre)neoplastic lesions in rat liver. J Histochem Cytochem 2003; 51:105-12. [PMID: 12502759 DOI: 10.1177/002215540305100112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) is the key regulatory enzyme of the pentose phosphate pathway and produces NADPH and riboses. In this study, the kinetic properties of G6PD activity were determined in situ in chemically induced hepatocellular carcinomas, and extralesional and control parenchyma in rat livers and were directly compared with those of the second NADPH-producing enzyme of the pentose phosphate pathway, phosphogluconate dehydrogenase (PGD). Distribution patterns of G6PD activity, protein, and mRNA levels were also compared to establish the regulation mechanisms of G6PD activity. In (pre)neoplastic lesions, the V(max) of G6PD was 150-fold higher and the K(m) for G6P was 10-fold higher than in control liver parenchyma, whereas in extralesional parenchyma, the V(max) was similar to that in normal parenchyma but the K(m) was fivefold lower. This means that virtual fluxes at physiological substrate concentrations are 20-fold higher in lesions and twofold higher in extralesional parenchyma than in normal parenchyma. The V(max) of PGD was fivefold higher in lesions than in normal and extralesional liver parenchyma, whereas the K(m) was not affected. Amounts of G6PD protein and mRNA were similar in lesions and in extralesional liver parenchyma. These results demonstrate that G6PD is strongly activated post-translationally in (pre)neoplastic lesions to produce NADPH.
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Affiliation(s)
- Wilma M Frederiks
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, Amsterdam, The Netherlands.
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25
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Frederiks WM, Vreeling-Sindelárová H. Ultrastructural localization of xanthine oxidoreductase activity in isolated rat liver cells. Acta Histochem 2002; 104:29-37. [PMID: 11993848 DOI: 10.1078/0065-1281-00629] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Xanthine oxidoreductase (XOR) can exist in a dehydrogenase form (XD) and an oxidase form (XO). The D-form uses NAD as cofactor and the O-form uses oxygen as second substrate and produces oxygen radicals. Both enzymes have a high affinity for hypoxanthine and xanthine as substrate and produce uric acid, a potent antioxidant. In the present study, XOR activity was demonstrated with the ferricyanide method in permeabilized isolated rat liver cells at the electron microscopical level. Moreover, ultrastructural localization of XO activity in these cells was studied with the cerium salt method. Activity of both XOR and XO was found in matrix and core of peroxisomes of rat liver parenchymal cells. Only XOR activity was present as well in the cytoplasm of rat liver parenchymal cells. In Kupffer cells and sinusoidal endothelial cells, XOR activity was demonstrated in vesicles and occasionally on granular endoplasmic reticulum. XO activity was not found in Kupffer cells and sinusoidal endothelial cells. The presence of uric acid oxidase activity in matrix and core of peroxisomes as was found previously suggests further breakdown of purines to allantoin in peroxisomes. It is suggested that the major function of XOR activity in the cytoplasm of rat liver parenchymal cells and in sinusoidal cells is not the production of oxygen radicals, but rather the production of uric acid which can act as a potent antioxidant.
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Affiliation(s)
- Wilma M Frederiks
- Academic Medical Center, University of Amsterdam, Department of Cell Biology and Histology, The Netherlands.
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