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T. Washizu - One of the best experts on this subject based on the ideXlab platform.
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Activities of Enzymes in the Malate–Aspartate Shuttle in the Peripheral Leukocytes of Dogs and Cats
Veterinary Research Communications, 2001Co-Authors: T. Washizu, M. Takahashi, D. Azakami, M. Ikeda, T. AraiAbstract:The activities of the enzymes involved in the malate–aspartate Shuttle and the expression of malate dehydrogenase (MDH), a rate-limiting enzyme in the NADH Shuttle that produces ATP in glucose metabolism in leukocytes, were determined to investigate the differences in this Shuttle system in the peripheral leukocytes of dogs and cats. There were no significant differences between dogs and cats in plasma glucose, immunoreactive insulin, free fatty acid or triglyceride concentrations. The activities of cytosolic and mitochondrial MDH and of mitochondrial glutamate dehydrogenase (GLDH) in canine leukocytes were significantly higher than in feline leukocytes. High activities of MDH in canine leukocytes were confirmed by RT-PCR analysis on the total RNA extracted from leukocytes. It was concluded that there were significant differences between dogs and cats in the NADH Shuttle system.
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Activities of Enzymes Related to the Malate–Aspartate Shuttle in the Blood Cells of Thoroughbred Horses Undergoing Training Exercise
Veterinary Research Communications, 2001Co-Authors: T. Arai, M. Takahashi, K. Araki, T. WashizuAbstract:The activities of the enzymes related to the malate–aspartate Shuttle, which convert cytosolic NADH into mitochondrial NADH, were measured in red and white blood cells from thoroughbred horses undergoing continuous training (race horses) and compared with those in blood cells from riding horses. The activities of malate dehydrogenase (MDH), a rate-limiting enzyme for the Malate-Aspartate Shuttle, were significantly elevated in the white blood cells (WBC) from race horses compared with those from riding horses. There were no significant differences in the activities of the enzymes in the red blood cells between race horses and riding horses. This increase in the MDH activity in their WBC is considered to reflect the increased metabolic activity in the race horses resulting from the training.
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Activities of enzymes related to the Malate-Aspartate Shuttle in the blood cells of thoroughbred horses undergoing training exercise.
Veterinary Research Communications, 2001Co-Authors: T. Arai, M. Takahashi, K. Araki, T. WashizuAbstract:The activities of the enzymes related to the Malate-Aspartate Shuttle, which convert cytosolic NADH into mitochondrial NADH, were measured in red and white blood cells from thoroughbred horses undergoing continuous training (race horses) and compared with those in blood cells from riding horses. The activities of malate dehydrogenase (MDH), a rate-limiting enzyme for the Malate-Aspartate Shuttle, were significantly elevated in the white blood cells (WBC) from race horses compared with those from riding horses. There were no significant differences in the activities of the enzymes in the red blood cells between race horses and riding horses. This increase in the MDH activity in their WBC is considered to reflect the increased metabolic activity in the race horses resulting from the training.
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Activities of enzymes in the Malate-Aspartate Shuttle in the peripheral leukocytes of dogs and cats.
Veterinary Research Communications, 2001Co-Authors: T. Washizu, M. Takahashi, D. Azakami, M. Ikeda, Toshiro AraiAbstract:The activities of the enzymes involved in the malate–aspartate Shuttle and the expression of malate dehydrogenase (MDH), a rate-limiting enzyme in the NADH Shuttle that produces ATP in glucose metabolism in leukocytes, were determined to investigate the differences in this Shuttle system in the peripheral leukocytes of dogs and cats. There were no significant differences between dogs and cats in plasma glucose, immunoreactive insulin, free fatty acid or triglyceride concentrations. The activities of cytosolic and mitochondrial MDH and of mitochondrial glutamate dehydrogenase (GLDH) in canine leukocytes were significantly higher than in feline leukocytes. High activities of MDH in canine leukocytes were confirmed by RT-PCR analysis on the total RNA extracted from leukocytes. It was concluded that there were significant differences between dogs and cats in the NADH Shuttle system.
Weihai Ying - One of the best experts on this subject based on the ideXlab platform.
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Cytosolic aspartate aminotransferase mediates the mitochondrial membrane potential and cell survival by maintaining the calcium homeostasis of BV2 microglia.
NeuroReport, 2018Co-Authors: Caixia Wang, Heyu Chen, Weihai YingAbstract:Both mitochondrial aspartate aminotransferase (mAST) and cytosolic aspartate aminotransferase (cAST) are important components in the Malate-Aspartate Shuttle - one of the two types of NADH Shuttles in cells. A major goal of our current study was to determine specifically the roles of cAST in maintaining the [Ca]i, mitochondrial membrane potential and the survival of BV2 microglia by applying molecular approach to modulate the cAST levels. Our study found that decreased cAST by cAST siRNA can lead to significant increases in the [Ca]i, mitochondrial depolarization and apoptosis of BV2 microglia. The cAST siRNA-induced mitochondrial depolarization can be significantly attenuated by an inhibitor of calpain. We further found that the cAST siRNA-induced apoptosis can be prevented by the calpain inhibitor. Collectively, our study suggests that decreased cAST induces calpain activation by increasing the [Ca]i of BV2 microglia, resulting in mitochondrial depolarization and cell death. Moreover, our data suggest that decreased cAST may produce these pathological effects by Malate-Aspartate Shuttle-independent pathways.
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malate aspartate Shuttle inhibitor aminooxyacetic acid blocks lipopolysaccharides induced activation of bv2 microglia
International journal of physiology pathophysiology and pharmacology, 2017Co-Authors: Wangsong Shang, Weihai YingAbstract:: NADH Shuttles, including Malate-Aspartate Shuttle (MAS) and glycerol-3-phosphate Shuttle, mediate the transfer of the reducing equivalents of cytosolic NADH into mitochondria. In our current study, we used BV2 microglia as a cellular model to determine the roles of NADH Shuttles in lipopolysaccharides (LPS)-induced microglial activation. We found that aminooxyacetic acid (AOAA), a widely used MAS inhibitor, significantly attenuated LPS-induced increases in the levels of nitric oxide-a hallmarker of microglial activation. Our Western Blot assays also showed that AOAA blocked the LPS-induced increases in the protein levels of iNOS, TNF-α and COX-2. Furthermore, we found that AOAA decreased LPS-induced nuclear translocation of NF-κB. Collectively, our study has suggested that AOAA may be a new agent for inhibiting microglial activation. Our study has also suggested that MAS may be a novel target for modulating microglial activation under pathological conditions.
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malate aspartate Shuttle inhibitor aminooxyacetic acid leads to decreased intracellular atp levels and altered cell cycle of c6 glioma cells by inhibiting glycolysis
Cancer Letters, 2016Co-Authors: Caixia Wang, Heyu Chen, Jie Zhang, Mingchao Zhang, Weihai YingAbstract:NADH Shuttles, including Malate-Aspartate Shuttle (MAS) and glycerol-3-phosphate Shuttle, can Shuttle the reducing equivalents of cytosolic NADH into mitochondria. It is widely accepted that the major function of NADH Shuttles is to increase mitochondrial energy production. Our study tested the hypothesis that the novel major function of NADH Shuttles in cancer cells is to maintain glycolysis by decreasing cytosolic NADH/NAD(+) ratios. We found that AOAA, a widely used MAS inhibitor, led to decreased intracellular ATP levels, altered cell cycle and increased apoptosis and necrosis of C6 glioma cells, without affecting the survival of primary astrocyte cultures. AOAA also decreased the glycolytic rate and the levels of extracellular lactate and pyruvate, without affecting the mitochondrial membrane potential of C6 cells. Moreover, the toxic effects of AOAA were completely prevented by pyruvate treatment. Collectively, our study has suggested that AOAA may be used to selectively decrease glioma cell survival, and the major function of MAS in cancer cells may be profoundly different from its major function in normal cells: The major function of MAS in cancer cells is to maintain glycolysis, instead of increasing mitochondrial energy metabolism.
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Malate-Aspartate Shuttle Inhibitor Aminooxyacetate Acid Induces Apoptosis and Impairs Energy Metabolism of Both Resting Microglia and LPS-Activated Microglia
Neurochemical Research, 2015Co-Authors: Heyu Chen, Caixia Wang, Xianting Ding, Xunbin Wei, Weihai YingAbstract:NADH Shuttles mediate the transfer of the reducing equivalents of cytosolic NADH into mitochondria. Cumulating evidence has suggested that Malate-Aspartate Shuttle (MAS), one of the two types of NADH Shuttles, plays significant roles in such biological processes as glutamate synthesis in neurons. However, there has been no information regarding the roles of NADH Shuttle in the survival and energy metabolism of microglia. In current study, using microglial BV2 cells as a cellular model, we determined the roles of MAS in the survival and energy metabolism of microglia by using aminooxyacetate acid (AOAA)—a widely used MAS inhibitor. Our study has suggested that AOAA can effectively inhibit the MAS activity of the cells. We also found that AOAA can induce both early- and late-stage apoptosis of resting microglia and lipopolysaccharides (LPS)-activated microglia. AOAA also induced mitochondrial depolarization, increases in the cytosolic Ca2+ concentrations, and decreases in the intracellular ATP levels. Moreover, our study has excluded the possibility that the major nonspecific effect of AOAA—inhibition of GABA transaminase—is involved in theses effects of AOAA. Collectively, our study has provided first information suggesting significant roles of MAS in the survival and energy metabolism in both resting microglia and LPS-activated microglia.
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Malate-Aspartate Shuttle mediates the intracellular ATP levels, antioxidation capacity and survival of differentiated PC12 cells.
International journal of physiology pathophysiology and pharmacology, 2014Co-Authors: Caixia Wang, Heyu Chen, Jie Zhang, Yunyi Hong, Xianting Ding, Weihai YingAbstract:NAD+ and NADH play pivotal roles in numerous redox reactions in cells. While increasing evidence has indicated important roles of NAD+ in cell survival and cellular functions, there has been distinct deficiency in the studies regarding the biological functions of NADH. NADH Shuttles mediate the transfer of the reducing equivalents of the cytosolic NADH into mitochondria. Cumulating evidence has suggested that Malate-Aspartate Shuttle (MAS), one of the two types of NADH Shuttles, plays significant roles in multiple biological processes such as glutamate synthesis in neurons. Because there has been no information regarding the roles of NADH Shuttle in the energy metabolism, antioxidation capacity, and survival of any type of neural cells, in this study we used differentiated PC12 cells as a cellular model to investigate the roles of MAS in the energy metabolism, antioxidation capacity and survival of cells. We found that MAS inhibition led to a significant decrease in the levels of GSH – a major antioxidation molecule in cells, suggesting an important role of MAS in maintaining the antioxidation capacity of cells. Our study has also suggested that MAS could play critical roles in maintaining the intracellular ATP levels of the cells. Moreover, MAS inhibition was shown to significantly decrease the survival of differentiated PC12 cells. Collectively, our study has provided first evidence suggesting important roles of NADH Shuttles in maintaining antioxidation capacity of cells. Our study has also suggested important roles of MAS in maintaining the intracellular ATP levels and survival of differentiated PC12 cells.
Huub Haaker - One of the best experts on this subject based on the ideXlab platform.
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glutamate oxaloacetate transaminase in pea root nodules participation in a malate aspartate Shuttle between plant and bacteroid
Plant Physiology, 1991Co-Authors: Michiel A Appels, Huub HaakerAbstract:Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate Shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this Shuttle.
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Glutamate Oxaloacetate Transaminase in Pea Root Nodules : Participation in a Malate/Aspartate Shuttle between Plant and Bacteroid.
Plant Physiology, 1991Co-Authors: Michiel A Appels, Huub HaakerAbstract:Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate Shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this Shuttle.
T. Arai - One of the best experts on this subject based on the ideXlab platform.
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Activities of Enzymes in the Malate–Aspartate Shuttle in the Peripheral Leukocytes of Dogs and Cats
Veterinary Research Communications, 2001Co-Authors: T. Washizu, M. Takahashi, D. Azakami, M. Ikeda, T. AraiAbstract:The activities of the enzymes involved in the malate–aspartate Shuttle and the expression of malate dehydrogenase (MDH), a rate-limiting enzyme in the NADH Shuttle that produces ATP in glucose metabolism in leukocytes, were determined to investigate the differences in this Shuttle system in the peripheral leukocytes of dogs and cats. There were no significant differences between dogs and cats in plasma glucose, immunoreactive insulin, free fatty acid or triglyceride concentrations. The activities of cytosolic and mitochondrial MDH and of mitochondrial glutamate dehydrogenase (GLDH) in canine leukocytes were significantly higher than in feline leukocytes. High activities of MDH in canine leukocytes were confirmed by RT-PCR analysis on the total RNA extracted from leukocytes. It was concluded that there were significant differences between dogs and cats in the NADH Shuttle system.
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Activities of Enzymes Related to the Malate–Aspartate Shuttle in the Blood Cells of Thoroughbred Horses Undergoing Training Exercise
Veterinary Research Communications, 2001Co-Authors: T. Arai, M. Takahashi, K. Araki, T. WashizuAbstract:The activities of the enzymes related to the malate–aspartate Shuttle, which convert cytosolic NADH into mitochondrial NADH, were measured in red and white blood cells from thoroughbred horses undergoing continuous training (race horses) and compared with those in blood cells from riding horses. The activities of malate dehydrogenase (MDH), a rate-limiting enzyme for the Malate-Aspartate Shuttle, were significantly elevated in the white blood cells (WBC) from race horses compared with those from riding horses. There were no significant differences in the activities of the enzymes in the red blood cells between race horses and riding horses. This increase in the MDH activity in their WBC is considered to reflect the increased metabolic activity in the race horses resulting from the training.
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Activities of enzymes related to the Malate-Aspartate Shuttle in the blood cells of thoroughbred horses undergoing training exercise.
Veterinary Research Communications, 2001Co-Authors: T. Arai, M. Takahashi, K. Araki, T. WashizuAbstract:The activities of the enzymes related to the Malate-Aspartate Shuttle, which convert cytosolic NADH into mitochondrial NADH, were measured in red and white blood cells from thoroughbred horses undergoing continuous training (race horses) and compared with those in blood cells from riding horses. The activities of malate dehydrogenase (MDH), a rate-limiting enzyme for the Malate-Aspartate Shuttle, were significantly elevated in the white blood cells (WBC) from race horses compared with those from riding horses. There were no significant differences in the activities of the enzymes in the red blood cells between race horses and riding horses. This increase in the MDH activity in their WBC is considered to reflect the increased metabolic activity in the race horses resulting from the training.
Michiel A Appels - One of the best experts on this subject based on the ideXlab platform.
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glutamate oxaloacetate transaminase in pea root nodules participation in a malate aspartate Shuttle between plant and bacteroid
Plant Physiology, 1991Co-Authors: Michiel A Appels, Huub HaakerAbstract:Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate Shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this Shuttle.
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Glutamate Oxaloacetate Transaminase in Pea Root Nodules : Participation in a Malate/Aspartate Shuttle between Plant and Bacteroid.
Plant Physiology, 1991Co-Authors: Michiel A Appels, Huub HaakerAbstract:Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate Shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this Shuttle.