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Yohko Fujimoto - One of the best experts on this subject based on the ideXlab platform.
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inhibition of prostaglandin synthesis in rabbit Kidney Medulla slices by antioxidants
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Yohko Fujimoto, H Tanioka, Eiko Toibana, Taku Yamamoto, T FujitaAbstract:The inhibitory effects of NN'-diphenyl-p-phenylenediamine (DPPD), sodium diethyldithiocarbamate (SDDC) and 2,6-di-t-butylphenol (DTBP) on the generation of Medullary prostaglandin E have been compared. DPPD (1 microM) and SDDC (1 mM) failed to inhibit arachidonic acid-induced stimulation of prostaglandin E synthesis, while DTBP (1 mM) inhibited it. This suggests that DPPD and SDDC inhibit prostaglandin formation by affecting a phospholipase pathway, and the inhibition of prostaglandin generation by DTBP occurs at the cyclooxygenase step.
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comparison of the effects of fe2 and cu2 on prostaglandin synthesis in rabbit Kidney Medulla slices
Journal of Pharmacy and Pharmacology, 2011Co-Authors: T Fujita, Noboru Ohtani, Midori Aihara, Kazuyuki Nishioka, Yohko FujimotoAbstract:The effects of Fe2+ and Cu2+ on the generation of Medullary prostaglandins E2 and F2 alpha have been compared. Fe2+ markedly promoted the lipid peroxidation of rabbit Kidney Medulla slices. The lipid peroxidation induced by Fe2+ inhibited both prostaglandin E2 and prostaglandin F2 alpha formation to a similar extent. While Cu2+ produced only a small increase in lipid peroxidation, it had a powerful inhibitory effect on prostaglandin E2 formation. Simultaneously, prostaglandin F2 alpha production was increased. In the presence of Cu2+ the net increased amount of prostaglandin F2 alpha was much smaller than the net decreased amount of prostaglandin E2 (15-20%). These results suggest that Cu2+ has the potential to modulate prostaglandins E2 and F2 alpha synthesis by affecting endoperoxide E2 isomerase or endoperoxide reductase independent of its peroxidative action.
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effect of sodium azide and sodium selenite on prostaglandin synthesis in rabbit Kidney Medulla slices
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Yohko Fujimoto, Taku Yamamoto, Nobuyuki Niwase, T FujitaAbstract:Sodium azide, a catalase inhibitor, stimulated the generation of Medullary prostaglandin E2, while the glutathione peroxidase activator sodium selenite inhibited it. These results suggest that hydroperoxides play an important role in the control of prostaglandin synthesis.
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the regulation of formation of prostaglandins and arachidonoyl coa from arachidonic acid in rabbit Kidney Medulla microsomes by linoleic acid hydroperoxide
Prostaglandins & Other Lipid Mediators, 2006Co-Authors: Satoru Sakuma, Kumiko Usa, Yohko FujimotoAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). In the present study, we investigated the effects of linoleic acid (LA) and 13-hydroperoxyoctadecadienoic acid (13-HPODE) on the PG and AA-CoA formation from high and low concentrations of AA (60 and 5 μM) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 60 or 5 μM [14C]-AA in 0.1 M Tris–HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. LA (10–50 μM) reduced only PG formation from both 60 and 5 μM AA. 13-HPODE (10–50 μM) also reduced PG formation from 60 and 5 μM AA, but the inhibitory potency was much stronger than that by LA. Furthermore, 13-HPODE had the potential to increase the AA-CoA formation with a decrease in the PG formation from 5 μM AA. These results suggest that 13-HPODE, but not LA, may shift AA away from COX pathway into ACS pathway under low substrate concentration (near physiological concentration of AA).
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effects of endocrine disruptors on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2005Co-Authors: Yohko Fujimoto, Kumiko Usa, Satoru SakumaAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To explore the possible actions of endocrine disruptors on the metabolic fate of free AA into these two pathways, we investigated the effects of nonylphenol (NP), bisphenol A (BPA), di- n -butyl phthalate (DBP), benzyl- n -butyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) on the formation of PG and AA-CoA from 5μM AA (close to the physiological concentration of the substrate) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 5μM [ 14 C]-AA in 0.1M Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl 2 and CoA). After incubation, PG (as total PGs) and AA-CoA were separated by selective extraction using petroleum ether and ethyl acetate. NP (1–200μM) strongly enhanced the AA-CoA formation with a coincident decrease in the PG formation. BPA, DBP, BBP and DEHP failed to show any effect on the PG and AA-CoA formation up to 200μM. Experiments utilizing 60μM AA as the substrate concentration indicated that, under a low concentration of AA, NP decreases PG formation by inhibiting the COX activity, and reduces the AA flow into the COX pathway through inhibition on the COX activity, increasing availability of the substrate for the ACS and leading to enhanced AA-CoA formation. These results firstly show that NP has the potential to disturb the balance of PG and AA-CoA formations under normal physiological conditions.
Moo H Kwon - One of the best experts on this subject based on the ideXlab platform.
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interstitial tonicity controls tonebp expression in the renal Medulla
Kidney International, 2009Co-Authors: Mee Rie Sheen, Un Sil Jeon, Juy Jung, Sooh Park, Moo H KwonAbstract:Cells in the hyperosmotic Kidney Medulla, express a transcriptional activator termed tonicity responsive enhancer binding protein (TonEBP). Genes targeted by TonEBP protect Kidney cells from the deleterious effects of hyperosmolality by inducing the expression of organic osmolytes and molecular chaperones, and other genes that mediate urine concentration such as aquaporin-2 and urea transporters. We tested here the effect of hypertonicity and hyperosmotic salt in the renal Medullary interstitium on the expression TonEBP. When massive water diuresis was induced in rats the Medullary sodium concentrations did not change, neither did TonEBP expression. In these animals the Medullary tonicity was unchanged despite the production of dilute urine. On the other hand, treatment with the loop diurectic furosemide resulted in a dose-dependent decrease in the Medullary sodium concentration causing a reduction in interstitial tonicity. Here, TonEBP expression was blunted in the outer and inner Medulla which was due, in part, to decreased mRNA abundance. As expected, the expression of TonEBP target genes in the renal Medulla also decreased in response to furosemide. Hence TonEBP expression in the renal Medulla is stimulated by interstitial hypertonicity.
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silencing of tonebp nfat5 transcriptional activator by rna interference
Journal of The American Society of Nephrology, 2003Co-Authors: Seung Kyoon Woo, Moo H Kwon, Sang Do LeeAbstract:TonEBP is a transcriptional activator that is expressed throughout development in many tissues and cell types. In the Kidney Medulla, TonEBP appears to be an important local regulator of differentiation by virtue of stimulating several genes. To study the function of TonEBP, two small interfering RNA (siRNA) duplexes were developed that reduced TonEBP expression effectively via RNA interference. The silencing lasted only 3 d after introduction of the TonEBP-siRNA's. As expected, TonEBP-driven reporter gene expression and expression of the sodium/myo-inositol cotransproter (SMIT), aldose reductase (AR) and heat shock protein 70 (HSP70) mRNA were significantly decreased in cells where TonEBP expression was silenced. These data provide direct evidence that the SMIT, AR, and HSP70 genes are targets of TonEBP, although the potential role of other proteins, such as accessory proteins, cannot be excluded. The TonEBP-siRNA is an effective tool that should prove useful in the investigation of loss-of-function relationship in cells.
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tonebp nfat5 stimulates transcription of hsp70 in response to hypertonicity
Molecular and Cellular Biology, 2002Co-Authors: Seung Kyoon Woo, Sang Do Lee, Won Kun Park, Moo H KwonAbstract:While hyperosmolality of the Kidney Medulla is essential for urinary concentration, it imposes a great deal of stress. Cells in the renal Medulla adapt to the stress of hypertonicity (hyperosmotic salt) by accumulating organic osmolytes. Tonicity-responsive enhancer (TonE) binding protein (TonEBP) (or NFAT5) stimulates transcription of transporters and a synthetic enzyme for the cellular accumulation of organic osmolytes. We found that dominant-negative TonEBP reduced expression of HSP70 as well as the transporters and enzyme. Near the major histocompatibility complex class III locus, there are three HSP70 genes named HSP70-1, HSP70-2, and HSC70t. While HSP70-1 and HSP70-2 were heat inducible, only HSP70-2 was induced by hypertonicity. In the 5' flanking region of the HSP70-2 gene, there are three sites for TonEBP binding. In cells transfected with a reporter plasmid containing this region, expression of luciferase was markedly stimulated in response to hypertonicity. Coexpression of the dominant-negative TonEBP reduced the luciferase expression. Mutating all three sites in the reporter plasmid led to a complete loss of induction by hypertonicity. Thus, TonEBP rather than heat shock factor stimulates transcription of the HSP70-2 gene in response to hypertonicity. We conclude that TonEBP is a master regulator of the renal Medulla for cellular protection against high osmolality via organic osmolytes and molecular chaperones.
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tonicity responsive enhancer binding protein a rel like protein that stimulates transcription in response to hypertonicity
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Hiroshi Miyakawa, Stephen C Dahl, Joseph S Handler, Moo H KwonAbstract:Hypertonicity (most often present as high salinity) is stressful to the cells of virtually all organisms. Cells survive in a hypertonic environment by increasing the transcription of genes whose products catalyze cellular accumulation of compatible osmolytes. In mammals, the Kidney Medulla is normally hypertonic because of the urinary concentrating mechanism. Cellular accumulation of compatible osmolytes in the renal Medulla is catalyzed by the sodium/myo-inositol cotransporter (SMIT), the sodium/chloride/betaine cotransporter, and aldose reductase (synthesis of sorbitol). The importance of compatible osmolytes is underscored by the necrotic injury of the renal Medulla and subsequent renal failure that results from the inhibition of SMIT in vivo by administration of a specific inhibitor. Tonicity-responsive enhancers (TonE) play a key role in hypertonicity-induced transcriptional stimulation of SMIT, sodium/chloride/betaine cotransporter, and aldose reductase. We report the cDNA cloning of human TonE binding protein (TonEBP), a transcription factor that stimulates transcription through its binding to TonE sequences via a Rel-like DNA binding domain. Western blot and immunohistochemical analyses of cells cultured in hypertonic medium reveal that exposure to hypertonicity elicits slow activation of TonEBP, which is the result of an increase in TonEBP amount and translocation to the nucleus.
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Kidney cell survival in high tonicity
Comparative Biochemistry and Physiology Part A: Physiology, 1997Co-Authors: Jeffrey S Handler, Moo H KwonAbstract:Abstract The Kidney Medulla of mammals undergoes large changes in tonicity in parallel with the tonicity of the final urine that emerges from the Kidney at the tip of the Medulla. When the Medulla is hypertonic, its cells accumulate the compatible osmolytes myo -inositol, betaine, taurine, sorbitol and glycerophosphorylcholine. The mechanisms by which the compatible osmolytes are accumulated have been explored extensively in Kidney-derived cells in culture. Myo -inositol, betaine and taurine are accumulated by increased activity of specific sodium-coupled transporters, sorbitol by increased synthesis of aldose reductase that catalyses the synthesis of sorbitol from glucose. Glycerophosphorylcholine accumulates primarily because its degradation is reduced in cells in hypertonic medium. cDNAs for the cotransporters and for aldose reductase have been cloned and used to establish that hypertonicity increases the transcription of the genes for the cotransporters for myo -inositol, betaine and for aldose reductase. The region 5′ to the promoter of the gene for the betaine cotransporter and for aldose reductase confer osmotic responsiveness to a heterologous promoter. The 12-bp sequence responsible for the transcriptional response to hypertonicity has been identified in the 5′ region of the gene for the betaine cotransporter.
T Fujita - One of the best experts on this subject based on the ideXlab platform.
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comparison of the effects of fe2 and cu2 on prostaglandin synthesis in rabbit Kidney Medulla slices
Journal of Pharmacy and Pharmacology, 2011Co-Authors: T Fujita, Noboru Ohtani, Midori Aihara, Kazuyuki Nishioka, Yohko FujimotoAbstract:The effects of Fe2+ and Cu2+ on the generation of Medullary prostaglandins E2 and F2 alpha have been compared. Fe2+ markedly promoted the lipid peroxidation of rabbit Kidney Medulla slices. The lipid peroxidation induced by Fe2+ inhibited both prostaglandin E2 and prostaglandin F2 alpha formation to a similar extent. While Cu2+ produced only a small increase in lipid peroxidation, it had a powerful inhibitory effect on prostaglandin E2 formation. Simultaneously, prostaglandin F2 alpha production was increased. In the presence of Cu2+ the net increased amount of prostaglandin F2 alpha was much smaller than the net decreased amount of prostaglandin E2 (15-20%). These results suggest that Cu2+ has the potential to modulate prostaglandins E2 and F2 alpha synthesis by affecting endoperoxide E2 isomerase or endoperoxide reductase independent of its peroxidative action.
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inhibition of prostaglandin synthesis in rabbit Kidney Medulla slices by antioxidants
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Yohko Fujimoto, H Tanioka, Eiko Toibana, Taku Yamamoto, T FujitaAbstract:The inhibitory effects of NN'-diphenyl-p-phenylenediamine (DPPD), sodium diethyldithiocarbamate (SDDC) and 2,6-di-t-butylphenol (DTBP) on the generation of Medullary prostaglandin E have been compared. DPPD (1 microM) and SDDC (1 mM) failed to inhibit arachidonic acid-induced stimulation of prostaglandin E synthesis, while DTBP (1 mM) inhibited it. This suggests that DPPD and SDDC inhibit prostaglandin formation by affecting a phospholipase pathway, and the inhibition of prostaglandin generation by DTBP occurs at the cyclooxygenase step.
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effect of sodium azide and sodium selenite on prostaglandin synthesis in rabbit Kidney Medulla slices
Journal of Pharmacy and Pharmacology, 2011Co-Authors: Yohko Fujimoto, Taku Yamamoto, Nobuyuki Niwase, T FujitaAbstract:Sodium azide, a catalase inhibitor, stimulated the generation of Medullary prostaglandin E2, while the glutathione peroxidase activator sodium selenite inhibited it. These results suggest that hydroperoxides play an important role in the control of prostaglandin synthesis.
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the effects of nitric oxide and peroxynitrite on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2003Co-Authors: Satoru Sakuma, Yohko Fujimoto, Yuhsuke Katoh, T FujitaAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To clarify factors deciding the metabolic fate of free AA into these two pathways, we investigated the effects of a nitric oxide (NO) donor 1-hydroxyl-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC7), and peroxynitrite (ONOO−) on the formation of PG and AA-CoA from high and low concentrations of AA (60 and 5 μM) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 60 or 5 μM [14C]-AA in 0.1 M Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced GSH and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs) and AA-CoA were separated by selective extraction using petroleum ether and ethyl acetate. When 60 μM AA was used as the substrate concentration, NOC7 stimulated the PG formation at 0.5 μM, and inhibited it at 50 and 100 μM, without affecting the AA-CoA formation. When 5 μM AA was used as the substrate concentration, NOC7 showed no effect on the PG and AA-CoA formation up to 10 μM or below, but enhanced the AA-CoA formation with a coincident decrease in the PG formation at 50 μM or over. Experiments utilizing a NO antidote, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, revealed that the observed effects of NOC7 using 60 and 5 μM AA are caused by NO. On the other hand, ONOO− stimulated the PG formation from 60 μM AA, with no alteration in the AA-CoA formation at a concentration of 100 μM, but when 5 μM AA was used as the substrate concentration, it was without effect on the PG and AA-CoA formation. These findings indicate that actions of NO and ONOO− on the PG and AA-CoA formation by the Kidney Medulla microsomes may change depending on the substrate concentration. The effects of NO using 5 μM AA were reversed by the addition of the superoxide generating system (xanthine–xanthine oxidase plus catalase), indicating that superoxide is a vital modulator of the action of NO. These results suggest that NO, but not ONOO−, can be a regulator of the PG and AA-CoA formation at low substrate concentrations (close to the physiological concentration of AA), and that superoxide may play an important role in the action of NO.
Satoru Sakuma - One of the best experts on this subject based on the ideXlab platform.
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the regulation of formation of prostaglandins and arachidonoyl coa from arachidonic acid in rabbit Kidney Medulla microsomes by linoleic acid hydroperoxide
Prostaglandins & Other Lipid Mediators, 2006Co-Authors: Satoru Sakuma, Kumiko Usa, Yohko FujimotoAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). In the present study, we investigated the effects of linoleic acid (LA) and 13-hydroperoxyoctadecadienoic acid (13-HPODE) on the PG and AA-CoA formation from high and low concentrations of AA (60 and 5 μM) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 60 or 5 μM [14C]-AA in 0.1 M Tris–HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. LA (10–50 μM) reduced only PG formation from both 60 and 5 μM AA. 13-HPODE (10–50 μM) also reduced PG formation from 60 and 5 μM AA, but the inhibitory potency was much stronger than that by LA. Furthermore, 13-HPODE had the potential to increase the AA-CoA formation with a decrease in the PG formation from 5 μM AA. These results suggest that 13-HPODE, but not LA, may shift AA away from COX pathway into ACS pathway under low substrate concentration (near physiological concentration of AA).
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effects of endocrine disruptors on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2005Co-Authors: Yohko Fujimoto, Kumiko Usa, Satoru SakumaAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To explore the possible actions of endocrine disruptors on the metabolic fate of free AA into these two pathways, we investigated the effects of nonylphenol (NP), bisphenol A (BPA), di- n -butyl phthalate (DBP), benzyl- n -butyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP) on the formation of PG and AA-CoA from 5μM AA (close to the physiological concentration of the substrate) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 5μM [ 14 C]-AA in 0.1M Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl 2 and CoA). After incubation, PG (as total PGs) and AA-CoA were separated by selective extraction using petroleum ether and ethyl acetate. NP (1–200μM) strongly enhanced the AA-CoA formation with a coincident decrease in the PG formation. BPA, DBP, BBP and DEHP failed to show any effect on the PG and AA-CoA formation up to 200μM. Experiments utilizing 60μM AA as the substrate concentration indicated that, under a low concentration of AA, NP decreases PG formation by inhibiting the COX activity, and reduces the AA flow into the COX pathway through inhibition on the COX activity, increasing availability of the substrate for the ACS and leading to enhanced AA-CoA formation. These results firstly show that NP has the potential to disturb the balance of PG and AA-CoA formations under normal physiological conditions.
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the effects of nitric oxide and peroxynitrite on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2003Co-Authors: Satoru Sakuma, Yohko Fujimoto, Yuhsuke Katoh, T FujitaAbstract:Abstract Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To clarify factors deciding the metabolic fate of free AA into these two pathways, we investigated the effects of a nitric oxide (NO) donor 1-hydroxyl-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC7), and peroxynitrite (ONOO−) on the formation of PG and AA-CoA from high and low concentrations of AA (60 and 5 μM) in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 60 or 5 μM [14C]-AA in 0.1 M Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced GSH and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs) and AA-CoA were separated by selective extraction using petroleum ether and ethyl acetate. When 60 μM AA was used as the substrate concentration, NOC7 stimulated the PG formation at 0.5 μM, and inhibited it at 50 and 100 μM, without affecting the AA-CoA formation. When 5 μM AA was used as the substrate concentration, NOC7 showed no effect on the PG and AA-CoA formation up to 10 μM or below, but enhanced the AA-CoA formation with a coincident decrease in the PG formation at 50 μM or over. Experiments utilizing a NO antidote, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, revealed that the observed effects of NOC7 using 60 and 5 μM AA are caused by NO. On the other hand, ONOO− stimulated the PG formation from 60 μM AA, with no alteration in the AA-CoA formation at a concentration of 100 μM, but when 5 μM AA was used as the substrate concentration, it was without effect on the PG and AA-CoA formation. These findings indicate that actions of NO and ONOO− on the PG and AA-CoA formation by the Kidney Medulla microsomes may change depending on the substrate concentration. The effects of NO using 5 μM AA were reversed by the addition of the superoxide generating system (xanthine–xanthine oxidase plus catalase), indicating that superoxide is a vital modulator of the action of NO. These results suggest that NO, but not ONOO−, can be a regulator of the PG and AA-CoA formation at low substrate concentrations (close to the physiological concentration of AA), and that superoxide may play an important role in the action of NO.
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the effects of fatty acyl coa esters on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2001Co-Authors: Satoru Sakuma, Yohko Fujimoto, Yuhsuke Katoh, Akinori Kitao, T FujitaAbstract:Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). We have previously shown that palmitoyl-CoA (PA-CoA) shifts AA away from the COX pathway into the ACS pathway in rabbit Kidney Medulla at a low concentration of AA (5 microM, close to the physiological concentration of substrate). In the present study, we investigated the effects of stearoyl (SA)-, oleoyl (OA)- and linoleoyl (LA)- CoAs on the formation of PG and AA-CoA from 5microM AA in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 5microM [(14)C]-AA in 0.1 M-Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl(2)and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. SA- and OA-CoAs increased AA-CoA formation with a reduction of PG formation, as well as PA-CoA. On the other hand, LA-CoA decreased formation of both PG and AA-CoA. These results suggest that fatty acyl CoA esters can be regulators of PG and AA-CoA formation in Kidney Medulla under physiological conditions.
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simultaneous measurement of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes the roles of zn2 and cu2 as modulators of formation of the two products
Prostaglandins Leukotrienes and Essential Fatty Acids, 1999Co-Authors: Satoru Sakuma, Yohko Fujimoto, Akinori Kitao, H Nishida, H Sakamoto, T FujitaAbstract:Under physiological conditions, small amounts of free arachidonic acid (AA) is released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) act competitively on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To date, there is no information about the factors deciding the metabolic fate of free AA into these two pathways. In this study, we tried to establish a method for the simultaneous measurement of PG and AA-CoA synthesis from exogenous AA in microsomes from rabbit Kidney Medulla. The Kidney Medulla microsomes were incubated with [14C]-AA in 0.1 M-Tris/HCI buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. When 60 microM AA was used as the substrate, indomethacin (an inhibitor of COX) and triacsin C (an inhibitor of ACS) reduced only PG and AA-CoA formation, respectively. On the other hand, when 5 microM AA was used as the substrate, indomethacin and triacsin C came to increase significantly the AA-CoA and PG formation, respectively. Thus, the experiments utilizing indomethacin and triacsin C revealed that the incubation using 60 microM AA can simultaneously detect the changes in the activities of COX and ACS caused by drugs, while the incubation using 5 microM AA can detect the changes in the product formation elicited by the resulting shunt of AA. Further, using these incubation conditions, the effects of Zn2+ and Cu2+ on the PG and AA-CoA formation were examined. Zn2+ inhibited the AA-CoA synthesis from 60 microM AA without affecting the PG synthesis. In contrast, when 5 microM AA was used as the substrate, a significant increase in the PG formation was observed in the presence of this ion, indicating that drug actions on the PG formation from AA by the Kidney Medulla microsomes may change depending on the substrate concentration. On the other hand, Cu2+ increased PG synthesis and inhibited AA-CoA synthesis from both 60 and 5 microM AA. These results suggest that the simultaneous measurements of PG and AA-CoA formation by the Kidney Medulla microsomes under high (60 microM) and low (5 microM) substrate concentrations can investigate the direct and indirect actions of drugs on the COX and ACS activities, and are useful for clarifying the haemostatic control of the metabolic fate of AA into the two enzymatic pathways. Furthermore, this study showed that Zn2+ and Cu2+ can modulate PG and AA-CoA formation by affecting COX activity, ACS activity, and/or the AA flow into the two enzymatic pathways.
T Fujita - One of the best experts on this subject based on the ideXlab platform.
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the effects of fatty acyl coa esters on the formation of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes
Prostaglandins Leukotrienes and Essential Fatty Acids, 2001Co-Authors: Satoru Sakuma, Yohko Fujimoto, Yuhsuke Katoh, Akinori Kitao, T FujitaAbstract:Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). We have previously shown that palmitoyl-CoA (PA-CoA) shifts AA away from the COX pathway into the ACS pathway in rabbit Kidney Medulla at a low concentration of AA (5 microM, close to the physiological concentration of substrate). In the present study, we investigated the effects of stearoyl (SA)-, oleoyl (OA)- and linoleoyl (LA)- CoAs on the formation of PG and AA-CoA from 5microM AA in rabbit Kidney Medulla microsomes. The Kidney Medulla microsomes were incubated with 5microM [(14)C]-AA in 0.1 M-Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl(2)and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. SA- and OA-CoAs increased AA-CoA formation with a reduction of PG formation, as well as PA-CoA. On the other hand, LA-CoA decreased formation of both PG and AA-CoA. These results suggest that fatty acyl CoA esters can be regulators of PG and AA-CoA formation in Kidney Medulla under physiological conditions.
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simultaneous measurement of prostaglandin and arachidonoyl coa formed from arachidonic acid in rabbit Kidney Medulla microsomes the roles of zn2 and cu2 as modulators of formation of the two products
Prostaglandins Leukotrienes and Essential Fatty Acids, 1999Co-Authors: Satoru Sakuma, Yohko Fujimoto, Akinori Kitao, H Nishida, H Sakamoto, T FujitaAbstract:Under physiological conditions, small amounts of free arachidonic acid (AA) is released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) act competitively on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). To date, there is no information about the factors deciding the metabolic fate of free AA into these two pathways. In this study, we tried to establish a method for the simultaneous measurement of PG and AA-CoA synthesis from exogenous AA in microsomes from rabbit Kidney Medulla. The Kidney Medulla microsomes were incubated with [14C]-AA in 0.1 M-Tris/HCI buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. When 60 microM AA was used as the substrate, indomethacin (an inhibitor of COX) and triacsin C (an inhibitor of ACS) reduced only PG and AA-CoA formation, respectively. On the other hand, when 5 microM AA was used as the substrate, indomethacin and triacsin C came to increase significantly the AA-CoA and PG formation, respectively. Thus, the experiments utilizing indomethacin and triacsin C revealed that the incubation using 60 microM AA can simultaneously detect the changes in the activities of COX and ACS caused by drugs, while the incubation using 5 microM AA can detect the changes in the product formation elicited by the resulting shunt of AA. Further, using these incubation conditions, the effects of Zn2+ and Cu2+ on the PG and AA-CoA formation were examined. Zn2+ inhibited the AA-CoA synthesis from 60 microM AA without affecting the PG synthesis. In contrast, when 5 microM AA was used as the substrate, a significant increase in the PG formation was observed in the presence of this ion, indicating that drug actions on the PG formation from AA by the Kidney Medulla microsomes may change depending on the substrate concentration. On the other hand, Cu2+ increased PG synthesis and inhibited AA-CoA synthesis from both 60 and 5 microM AA. These results suggest that the simultaneous measurements of PG and AA-CoA formation by the Kidney Medulla microsomes under high (60 microM) and low (5 microM) substrate concentrations can investigate the direct and indirect actions of drugs on the COX and ACS activities, and are useful for clarifying the haemostatic control of the metabolic fate of AA into the two enzymatic pathways. Furthermore, this study showed that Zn2+ and Cu2+ can modulate PG and AA-CoA formation by affecting COX activity, ACS activity, and/or the AA flow into the two enzymatic pathways.
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existence of an enzymatic pathway furnishing arachidonic acid for prostaglandin synthesis from arachidonoyl coa in rabbit Kidney Medulla
Biochemical and Biophysical Research Communications, 1994Co-Authors: Satoru Sakuma, Yukari Fujimoto, Kentaro Doi, S Nagamatsu, H Nishida, T FujitaAbstract:We examined whether arachidonoyl CoA (AA-CoA) can be a possible supplier of arachidonic acid (AA) for prostaglandin (PG) synthesis in rabbit Kidney Medulla. AA-CoA was preincubated with or without the 105,000 g supernatant (cytosol) fraction from the Kidney Medulla for 5 min at 37 degrees C followed by the incubation with the microsomal fraction (0.5 mg protein) (a rich source of PG synthesizing enzymes) in the presence of reduced glutathione and hydroquinone for 5 min at 37 degrees C, and the formed PGE2, F2 alpha and D2 were measured by high-pressure liquid chromatography using 9-anthryldiazomethane for derivatization. The addition of AA-CoA (20 nmol) alone changed the total PG formation (the sum of PGE2, F2 alpha and D2) from 0.14 to 1.55 ng. When the cytosolic fraction (10-100 microliters) was added together with 20 nmol-AA-CoA in the preincubation mixture, total PG formation was further increased 2- to 3-fold compared to AA-CoA alone. Experiments utilizing AA, instead of AA-CoA and boiled cytosolic fraction revealed that the stimulatory action of the cytosolic fraction on the AA-CoA-induced PG synthesis may not be due to the effect on cyclooxygenase activity and due to long-chain acyl CoA hydrolase. These results show that long-chain acyl CoA hydrolase which hydrolyzes AA-CoA to AA is present in the cytosol of rabbit Kidney Medulla and suggest that this enzyme activity is a potential mediator of supply of AA for PG synthesis in this region.
