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Metabolomic Analysis of the Skeletal Muscle of Mice Overexpressing PGC-1α.

Hatazawa Y, Senoo N, Tadaishi M, Ogawa Y, Ezaki O, Kamei Y, Miura S - PLoS ONE (2015)

Bottom Line: Meanwhile, BCAA levels decreased (Val, 0.7-fold; Leu, 0.8-fold; and Ile, 0.7-fold), and Glu (3.1-fold) and Asp (2.2-fold) levels increased.Moreover, our metabolomics data showing the activation of the purine nucleotide pathway, malate-aspartate shuttle, as well as creatine metabolism, which are known to be active during exercise, further suggests that PGC-1α regulates metabolism in exercise.Thus, we demonstrated the roles of PGC-1α in the skeletal muscle at the metabolite level.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Laboratory of Molecular Nutrition, Graduate School of Environmental and Life Science, Kyoto Prefectural University, Kyoto, Japan.

ABSTRACT
Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC-1α) is a coactivator of various nuclear receptors and other transcription factors whose expression increases in the skeletal muscle during exercise. We have previously made transgenic mice overexpressing PGC-1α in the skeletal muscle (PGC-1α-Tg mice). PGC-1α upregulates the expression of genes associated with red fibers, mitochondrial function, fatty acid oxidation, and branched chain amino acid (BCAA) degradation. However, global analyses of the actual metabolic products have not been investigated. In this study, we conducted metabolomic analysis of the skeletal muscle in PGC-1α-Tg mice by capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry. Principal component analysis and hierarchical cluster analysis showed clearly distinguishable changes in the metabolites between PGC-1α-Tg and wild-type control mice. Changes were observed in metabolite levels of various metabolic pathways such as the TCA cycle, pentose phosphate pathway, nucleotide synthesis, purine nucleotide cycle, and amino acid metabolism, including BCAA and β-alanine. Namely, metabolic products of the TCA cycle increased in PGC-1α-Tg mice, with increased levels of citrate (2.3-fold), succinate (2.2-fold), fumarate (2.8-fold), and malate (2.3-fold) observed. Metabolic products associated with the pentose phosphate pathway and nucleotide biosynthesis also increased in PGC-1α-Tg mice. Meanwhile, BCAA levels decreased (Val, 0.7-fold; Leu, 0.8-fold; and Ile, 0.7-fold), and Glu (3.1-fold) and Asp (2.2-fold) levels increased. Levels of β-alanine and related metabolites were markedly decreased in PGC-1α-Tg mice. Coordinated regulation of the TCA cycle and amino acid metabolism, including BCAA, suggests that PGC-1α plays important roles in energy metabolism. Moreover, our metabolomics data showing the activation of the purine nucleotide pathway, malate-aspartate shuttle, as well as creatine metabolism, which are known to be active during exercise, further suggests that PGC-1α regulates metabolism in exercise. Thus, we demonstrated the roles of PGC-1α in the skeletal muscle at the metabolite level.

No MeSH data available.


Related in: MedlinePlus

Observed metabolite changes mapped onto the pathways associated with glycine, threonine, serine, and alanine metabolism.Changes in the metabolite levels in the skeletal muscle of PGC-1α-Tg mice and WT mice are shown. Relative metabolite changes shown in the graphs were obtained by CE-TOFMS (S1 Table). Open bars, WT and filled bars, PGC-1α-Tg (N = 3). Data are expressed as the mean ± SD. Asterisks indicate statistically significant differences (***p < 0.001, **p < 0.01, *p < 0.05). Microarray data of gene expression change of enzymes and transporter in the related metabolic process are shown in the scheme.
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pone.0129084.g008: Observed metabolite changes mapped onto the pathways associated with glycine, threonine, serine, and alanine metabolism.Changes in the metabolite levels in the skeletal muscle of PGC-1α-Tg mice and WT mice are shown. Relative metabolite changes shown in the graphs were obtained by CE-TOFMS (S1 Table). Open bars, WT and filled bars, PGC-1α-Tg (N = 3). Data are expressed as the mean ± SD. Asterisks indicate statistically significant differences (***p < 0.001, **p < 0.01, *p < 0.05). Microarray data of gene expression change of enzymes and transporter in the related metabolic process are shown in the scheme.

Mentions: Some amino acid levels decreased, including Thr (0.7-fold), Met (0.8-fold), Ala (0.7-fold), Ser (0.7-fold), Pro (0.4-fold), and Gly (0.3-fold) in PGC-1α-Tg mice compared with WT mice (S1 Table). Some of these can be converted into pyruvate [9, 10] (Fig 8). Ala is metabolized into pyruvate by alanine amino transferase (ALT). Thr is converted into Gly by threonine aldolase, Gly is subsequently converted into Ser by serine hydroxymethyltransferase, and Ser is subsequently converted into pyruvate by serine dehydratase [9, 10] (Fig 8). The enzymes related to the metabolism of these amino acids increased in this study. Expression of ALT (3.6-fold), threonine aldolase (2.1-fold), serine hydroxymethyltransferase (2.3-fold), and serine dehydratase (12.6-fold) increased. Pyruvate may be converted into acetyl-CoA by pyruvate dehydrogenase (2.5-fold) (Fig 8). Consistently, although there is an increased level of pyruvate dehydrogenase kinase 4, which suppresses pyruvate dehydrogenase activity, pyruvate dehydrogenase activity is enhanced in PGC-1α-Tg mice [17]. In the previous study, we reported that glycolysis was suppressed in PGC-1α-Tg mice, and the respiration quotient was low [4], suggesting that glucose was not used as an energy source. Meanwhile, as the respiration quotient due to the use of amino acids as an energy source is lower than that of glucose, the idea that these amino acids are used for the TCA cycle, via pyruvate and acetyl-CoA, does not contradict with previous findings (suppressed glycolysis and low respiration quotient in PGC-1α-Tg mice) [4].


Metabolomic Analysis of the Skeletal Muscle of Mice Overexpressing PGC-1α.

Hatazawa Y, Senoo N, Tadaishi M, Ogawa Y, Ezaki O, Kamei Y, Miura S - PLoS ONE (2015)

Observed metabolite changes mapped onto the pathways associated with glycine, threonine, serine, and alanine metabolism.Changes in the metabolite levels in the skeletal muscle of PGC-1α-Tg mice and WT mice are shown. Relative metabolite changes shown in the graphs were obtained by CE-TOFMS (S1 Table). Open bars, WT and filled bars, PGC-1α-Tg (N = 3). Data are expressed as the mean ± SD. Asterisks indicate statistically significant differences (***p < 0.001, **p < 0.01, *p < 0.05). Microarray data of gene expression change of enzymes and transporter in the related metabolic process are shown in the scheme.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482640&req=5

pone.0129084.g008: Observed metabolite changes mapped onto the pathways associated with glycine, threonine, serine, and alanine metabolism.Changes in the metabolite levels in the skeletal muscle of PGC-1α-Tg mice and WT mice are shown. Relative metabolite changes shown in the graphs were obtained by CE-TOFMS (S1 Table). Open bars, WT and filled bars, PGC-1α-Tg (N = 3). Data are expressed as the mean ± SD. Asterisks indicate statistically significant differences (***p < 0.001, **p < 0.01, *p < 0.05). Microarray data of gene expression change of enzymes and transporter in the related metabolic process are shown in the scheme.
Mentions: Some amino acid levels decreased, including Thr (0.7-fold), Met (0.8-fold), Ala (0.7-fold), Ser (0.7-fold), Pro (0.4-fold), and Gly (0.3-fold) in PGC-1α-Tg mice compared with WT mice (S1 Table). Some of these can be converted into pyruvate [9, 10] (Fig 8). Ala is metabolized into pyruvate by alanine amino transferase (ALT). Thr is converted into Gly by threonine aldolase, Gly is subsequently converted into Ser by serine hydroxymethyltransferase, and Ser is subsequently converted into pyruvate by serine dehydratase [9, 10] (Fig 8). The enzymes related to the metabolism of these amino acids increased in this study. Expression of ALT (3.6-fold), threonine aldolase (2.1-fold), serine hydroxymethyltransferase (2.3-fold), and serine dehydratase (12.6-fold) increased. Pyruvate may be converted into acetyl-CoA by pyruvate dehydrogenase (2.5-fold) (Fig 8). Consistently, although there is an increased level of pyruvate dehydrogenase kinase 4, which suppresses pyruvate dehydrogenase activity, pyruvate dehydrogenase activity is enhanced in PGC-1α-Tg mice [17]. In the previous study, we reported that glycolysis was suppressed in PGC-1α-Tg mice, and the respiration quotient was low [4], suggesting that glucose was not used as an energy source. Meanwhile, as the respiration quotient due to the use of amino acids as an energy source is lower than that of glucose, the idea that these amino acids are used for the TCA cycle, via pyruvate and acetyl-CoA, does not contradict with previous findings (suppressed glycolysis and low respiration quotient in PGC-1α-Tg mice) [4].

Bottom Line: Meanwhile, BCAA levels decreased (Val, 0.7-fold; Leu, 0.8-fold; and Ile, 0.7-fold), and Glu (3.1-fold) and Asp (2.2-fold) levels increased.Moreover, our metabolomics data showing the activation of the purine nucleotide pathway, malate-aspartate shuttle, as well as creatine metabolism, which are known to be active during exercise, further suggests that PGC-1α regulates metabolism in exercise.Thus, we demonstrated the roles of PGC-1α in the skeletal muscle at the metabolite level.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan; Laboratory of Molecular Nutrition, Graduate School of Environmental and Life Science, Kyoto Prefectural University, Kyoto, Japan.

ABSTRACT
Peroxisome proliferator-activated receptor (PPAR) γ coactivator 1α (PGC-1α) is a coactivator of various nuclear receptors and other transcription factors whose expression increases in the skeletal muscle during exercise. We have previously made transgenic mice overexpressing PGC-1α in the skeletal muscle (PGC-1α-Tg mice). PGC-1α upregulates the expression of genes associated with red fibers, mitochondrial function, fatty acid oxidation, and branched chain amino acid (BCAA) degradation. However, global analyses of the actual metabolic products have not been investigated. In this study, we conducted metabolomic analysis of the skeletal muscle in PGC-1α-Tg mice by capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry. Principal component analysis and hierarchical cluster analysis showed clearly distinguishable changes in the metabolites between PGC-1α-Tg and wild-type control mice. Changes were observed in metabolite levels of various metabolic pathways such as the TCA cycle, pentose phosphate pathway, nucleotide synthesis, purine nucleotide cycle, and amino acid metabolism, including BCAA and β-alanine. Namely, metabolic products of the TCA cycle increased in PGC-1α-Tg mice, with increased levels of citrate (2.3-fold), succinate (2.2-fold), fumarate (2.8-fold), and malate (2.3-fold) observed. Metabolic products associated with the pentose phosphate pathway and nucleotide biosynthesis also increased in PGC-1α-Tg mice. Meanwhile, BCAA levels decreased (Val, 0.7-fold; Leu, 0.8-fold; and Ile, 0.7-fold), and Glu (3.1-fold) and Asp (2.2-fold) levels increased. Levels of β-alanine and related metabolites were markedly decreased in PGC-1α-Tg mice. Coordinated regulation of the TCA cycle and amino acid metabolism, including BCAA, suggests that PGC-1α plays important roles in energy metabolism. Moreover, our metabolomics data showing the activation of the purine nucleotide pathway, malate-aspartate shuttle, as well as creatine metabolism, which are known to be active during exercise, further suggests that PGC-1α regulates metabolism in exercise. Thus, we demonstrated the roles of PGC-1α in the skeletal muscle at the metabolite level.

No MeSH data available.


Related in: MedlinePlus