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Maroto R, Graber TG, Romsdahl TB, Kudlicki A, Russell WK, Rasmussen BB. Metabolomic and Lipidomic Signature of Skeletal Muscle with Constitutively Active Mechanistic Target of Rapamycin Complex 1. J Nutr 2023; 153:3397-3405. [PMID: 37898335 PMCID: PMC10739780 DOI: 10.1016/j.tjnut.2023.10.016] [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: 07/13/2023] [Revised: 09/07/2023] [Accepted: 10/03/2023] [Indexed: 10/30/2023] Open
Abstract
BACKGROUND Regulation of mechanistic target of rapamycin complex 1 (mTORC1) plays an important role in aging and nutrition. For example, caloric restriction reduces mTORC1 signaling and extends lifespan, whereas nutrient abundance and obesity increase mTORC1 signaling and reduce lifespan. Skeletal muscle-specific knockout (KO) of DEP domain-containing 5 protein (DEPDC5) results in constitutively active mTORC1 signaling, muscle hypertrophy and an increase in mitochondrial respiratory capacity. The metabolic profile of skeletal muscle, in the setting of hyperactive mTORC1 signaling, is not well known. OBJECTIVES To determine the metabolomic and lipidomic signature in skeletal muscle from female and male wild-type (WT) and DEPDC5 KO mice. METHODS Tibialis anterior (TA) muscles from WT and transgenic (conditional skeletal muscle-specific DEPDC5 KO) were obtained from female and male adult mice. Polar metabolites and lipids were extracted using a Bligh-Dyer extraction from 5 samples per group and identified and quantified by LC-MS/MS. Resulting analyte peak areas were analyzed with t-test, analysis of variance, and Volcano plots for group comparisons (e.g., WT compared with KO) and multivariate statistical analysis for genotype and sex comparisons. RESULTS A total of 162 polar metabolites (organic acids, amino acids, and amines and acyl carnitines) and 1141 lipid metabolites were detected in TA samples by LC-MS/MS. Few polar metabolites showed significant differences in KO muscles compared with WT within the same sex group. P-aminobenzoic acid, β-alanine, and dopamine were significantly higher in KO male muscle whereas erythrose-4-phosphate and oxoglutaric acid were significantly reduced in KO females. The lipidomic profile of the KO groups revealed an increase of muscle phospholipids and reduced triacylglycerol and diacylglycerol compared with the WT groups. CONCLUSIONS Sex differences were detected in polar metabolome and lipids were dependent on genotype. The metabolomic profile of mice with hyperactive skeletal muscle mTORC1 is consistent with an upregulation of mitochondrial function and amino acid utilization for protein synthesis.
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Affiliation(s)
- Rosario Maroto
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States.
| | - Ted G Graber
- Department of Physical Therapy, East Carolina University, Greenville, NC, United States
| | - Trevor B Romsdahl
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
| | - Andrzej Kudlicki
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
| | - William K Russell
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
| | - Blake B Rasmussen
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States; Department of Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.
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Miao L, Zhang Y, Lin Y, Liu B, Ge X. Appropriate leucine supplementation promotes glucose metabolism and enhances energy homeostasis in juvenile crucian carp (Carassius auratus gibelio var. CAS III). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2021; 40:100907. [PMID: 34481144 DOI: 10.1016/j.cbd.2021.100907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 08/13/2021] [Accepted: 08/21/2021] [Indexed: 02/07/2023]
Abstract
In order to characterize the molecular mechanisms by which leucine regulates carbohydrate metabolism and energy homeostasis, juvenile crucian carps (Carassius auratus gibelio var. CAS III) fed with a high carbohydrate diet were supplemented with different levels of dietary leucine: 0% (Leu0), 0.4% (Leu4), 0.8% (Leu8), 1.2% (Leu12), 1.6% (Leu16), 2.0% (Leu20), and 5.0% (Leu50). After 8 weeks, RNA sequencing was performed on samples collected from the Leu0, Leu8, Leu12 and Leu50 groups. Differentially expressed genes were then detected and analyzed. The results showed a total of 91.6 Gb of clean bases were generated. Moreover, a total of 1131, 5254, and 1539 DEGs were detected in Leu8, Leu12, and Leu50 compared with Leu0, respectively, encompassing 161 common DEGs. STEM analysis elucidated four significant clusters of DEGs that were associated with "glycerophospholipid metabolism," "glycerolipid metabolism," "PPAR signaling pathway," and "adipocytokine signaling pathway." Moreover, the mRNA expression levels of acyl-CoA synthetase long chain family member 5 (ACSL5), choline kinase beta (CHKB), cryptochrome-1 (CRY1), lon protease homolog 2, peroxisomal isoform X2 (LONP2), lipin 1 (LPIN1), membrane bound O-acyltransferase domain containing 2 (MBOAT2), phosphoenolpyruvate carboxykinase 1 (PEPCK), and uridine-cytidine kinase 2b (UCK2b) were then further investigated in all leucine treatment groups at starvation times of 0 h, 24 h, and 48 h. The results revealed that the expression levels of UCK2b and MBOAT2 were negatively correlated with the addition of leucine, whereas CHKB, LONP2, CRY1, PEPCK, and LPIN1 were positively correlated. In conclusion, dietary leucine supplementation below 1.2% enhanced carbohydrate metabolism in juvenile crucian carp fed with a high-carbohydrate diet, whereas concentrations above 2.0% is a better choice for energy homeostasis under starvation.
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Affiliation(s)
- Linghong Miao
- Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Centre (FFRC), Chinese Academy of Fishery Sciences (CAFS), Wuxi 214081, China; Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China
| | - Yuanyuan Zhang
- Shandong Freshwater Fisheries Research Institute, Jinan 250013, China
| | - Yan Lin
- Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Centre (FFRC), Chinese Academy of Fishery Sciences (CAFS), Wuxi 214081, China
| | - Bo Liu
- Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Centre (FFRC), Chinese Academy of Fishery Sciences (CAFS), Wuxi 214081, China; Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China
| | - Xianping Ge
- Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Centre (FFRC), Chinese Academy of Fishery Sciences (CAFS), Wuxi 214081, China; Wuxi Fisheries College, Nanjing Agricultural University, Wuxi 214081, China.
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Henaux L, Pereira KD, Thibodeau J, Pilon G, Gill T, Marette A, Bazinet L. Glucoregulatory and Anti-Inflammatory Activities of Peptide Fractions Separated by Electrodialysis with Ultrafiltration Membranes from Salmon Protein Hydrolysate and Identification of Four Novel Glucoregulatory Peptides. MEMBRANES 2021; 11:membranes11070528. [PMID: 34357178 PMCID: PMC8305187 DOI: 10.3390/membranes11070528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022]
Abstract
Natural bioactive peptides are suitable candidates for preventing the development of Type 2 diabetes (T2D), by reducing the various risk factors. The aim of this study was to concentrate glucoregulatory and anti-inflammatory peptides, from salmon by-products, by electrodialysis with ultrafiltration membrane (EDUF), and to identify peptides responsible for these bioactivities. Two EDUF configurations (1 and 2) were used to concentrate anionic and cationic peptides, respectively. After EDUF separation, two fractions demonstrated interesting properties: the initial fraction of the EDUF configuration 1 and the final fraction of the EDUF configuration 2 both showed biological activities to (1) increase glucose uptake in L6 muscle cells in insulin condition at 1 ng/mL (by 12% and 21%, respectively), (2) decrease hepatic glucose production in hepatic cells at 1 ng/mL in basal (17% and 16%, respectively), and insulin (25% and 34%, respectively) conditions, and (3) decrease LPS-induced inflammation in macrophages at 1 g/mL (45% and 30%, respectively). More impressive, the initial fraction of the EDUF configuration 1 (45% reduction) showed the same effect as the phenformin at 10 μM (40%), a drug used to treat T2D. Thirteen peptides were identified, chemically synthesized, and tested in-vitro for these three bioactivities. Thus, four new bioactive peptides were identified: IPVE increased glucose uptake by muscle cells, IVDI and IEGTL decreased hepatic glucose production (HGP) of insulin, whereas VAPEEHPTL decreased HGP under both basal condition and in the presence of insulin. To the best of our knowledge, this is the first time that (1) bioactive peptide fractions generated after separation by EDUF were demonstrated to be bioactive on three different criteria; all involved in the T2D, and (2) potential sequences involved in the improvement of glucose uptake and/or in the regulation of HGP were identified from a salmon protein hydrolysate.
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Affiliation(s)
- Loïc Henaux
- Department of Food Sciences and Laboratory of Food Processing and Electromembrane Processes (LTAPEM), Université Laval, Quebec City, QC G1V 0A6, Canada; (L.H.); (J.T.)
- Institute of Nutrition and Functional Foods (INAF), University Laval, Quebec City, QC G1V 0A6, Canada; (G.P.); (A.M.)
| | - Karina Danielle Pereira
- Laboratory of Biotechnology, School of Applied Sciences, University of Campinas (UNICAMP), Limeira 13484-350, SP, Brazil;
- Institute of Biosciences, State University (UNESP), Rio Claro 13506-900, SP, Brazil
| | - Jacinthe Thibodeau
- Department of Food Sciences and Laboratory of Food Processing and Electromembrane Processes (LTAPEM), Université Laval, Quebec City, QC G1V 0A6, Canada; (L.H.); (J.T.)
- Institute of Nutrition and Functional Foods (INAF), University Laval, Quebec City, QC G1V 0A6, Canada; (G.P.); (A.M.)
| | - Geneviève Pilon
- Institute of Nutrition and Functional Foods (INAF), University Laval, Quebec City, QC G1V 0A6, Canada; (G.P.); (A.M.)
- Department of Medicine, Faculty of Medicine, Quebec Heart and Lung Institute Cardiology Group, Université Laval, 2725 Chemin Ste-Foy, Quebec City, QC G1V 4G5, Canada
| | - Tom Gill
- Department of Process Engineering and Applied Science, Dalhousie University, P.O. Box 15000, Halifax, NS B3H 4R2, Canada;
| | - André Marette
- Institute of Nutrition and Functional Foods (INAF), University Laval, Quebec City, QC G1V 0A6, Canada; (G.P.); (A.M.)
- Department of Medicine, Faculty of Medicine, Quebec Heart and Lung Institute Cardiology Group, Université Laval, 2725 Chemin Ste-Foy, Quebec City, QC G1V 4G5, Canada
| | - Laurent Bazinet
- Department of Food Sciences and Laboratory of Food Processing and Electromembrane Processes (LTAPEM), Université Laval, Quebec City, QC G1V 0A6, Canada; (L.H.); (J.T.)
- Institute of Nutrition and Functional Foods (INAF), University Laval, Quebec City, QC G1V 0A6, Canada; (G.P.); (A.M.)
- Correspondence: ; Tel.: +1-418-656-2131 (ext. 407445)
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MARGOLIS LEEM, ALLEN JILLIANT, HATCH-MCCHESNEY ADRIENNE, PASIAKOS STEFANM. Coingestion of Carbohydrate and Protein on Muscle Glycogen Synthesis after Exercise: A Meta-analysis. Med Sci Sports Exerc 2021; 53:384-393. [PMID: 32826640 PMCID: PMC7803445 DOI: 10.1249/mss.0000000000002476] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION/PURPOSE Evidence suggests that carbohydrate and protein (CHO-PRO) ingestion after exercise enhances muscle glycogen repletion to a greater extent than carbohydrate (CHO) alone. However, there is no consensus at this point, and results across studies are mixed, which may be attributable to differences in energy content and carbohydrate intake relative to body mass consumed after exercise. The purpose of this study was determine the overall effects of CHO-PRO and the independent effects of energy and relative carbohydrate content of CHO-PRO supplementation on postexercise muscle glycogen synthesis compared with CHO alone. METHODS Meta-analysis was conducted on crossover studies assessing the influence of CHO-PRO compared with CHO alone on postexercise muscle glycogen synthesis. Studies were identified in a systematic review from PubMed and Cochrane Library databases. Data are presented as effect size (95% confidence interval [CI]) using Hedges' g. Subgroup analyses were conducted to evaluate effects of isocaloric and nonisocaloric energy content and dichotomized by median relative carbohydrate (high, ≥0.8 g·kg-1⋅h-1; low, <0.8 g·kg-1⋅h-1) content on glycogen synthesis. RESULTS Twenty studies were included in the analysis. CHO-PRO had no overall effect on glycogen synthesis (0.13, 95% CI = -0.04 to 0.29) compared with CHO. Subgroup analysis found that CHO-PRO had a positive effect (0.26, 95% CI = 0.04-0.49) on glycogen synthesis when the combined intervention provided more energy than CHO. Glycogen synthesis was not significant (-0.05, 95% CI = -0.23 to 0.13) in CHO-PRO compared with CON when matched for energy content. There was no statistical difference of CHO-PRO on glycogen synthesis in high (0.07, 95% CI = -0.11 to 0.22) or low (0.21, 95% CI = -0.08 to 0.50) carbohydrate content compared with CHO. CONCLUSION Glycogen synthesis rates are enhanced when CHO-PRO are coingested after exercise compared with CHO only when the added energy of protein is consumed in addition to, not in place of, carbohydrate.
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Affiliation(s)
- LEE M. MARGOLIS
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA
| | - JILLIAN T. ALLEN
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA
- Oak Ridge Institute of Science and Education, Oak Ridge, TN
| | | | - STEFAN M. PASIAKOS
- Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA
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Tulipano G. Role of Bioactive Peptide Sequences in the Potential Impact of Dairy Protein Intake on Metabolic Health. Int J Mol Sci 2020; 21:E8881. [PMID: 33238654 PMCID: PMC7700308 DOI: 10.3390/ijms21228881] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/19/2020] [Accepted: 11/19/2020] [Indexed: 02/07/2023] Open
Abstract
For years, there has been an increasing move towards elucidating the complexities of how food can interplay with the signalling networks underlying energy homeostasis and glycaemic control. Dairy foods can be regarded as the greatest source of proteins and peptides with various health benefits and are a well-recognized source of bioactive compounds. A number of dairy protein-derived peptide sequences with the ability to modulate functions related to the control of food intake, body weight gain and glucose homeostasis have been isolated and characterized. Their being active in vivo may be questionable mainly due to expected low bioavailability after ingestion, and hence their real contribution to the metabolic impact of dairy protein intake needs to be discussed. Some reports suggest that the differential effects of dairy proteins-in particular whey proteins-on mechanisms underlying energy balance and glucose-homeostasis may be attributed to their unique amino acid composition and hence the release of free amino acid mixtures enriched in essential amino acids (i.e., branched-chain-amino acids) upon digestion. Actually, the research reports reviewed in this article suggest that, among a number of dairy protein-derived peptides isolated and characterized as bioactive compounds in vitro, some peptides can be active in vivo post-oral administration through a local action in the gut, or, alternatively, a systemic action on specific molecular targets after entering the systemic circulation. Moreover, these studies highlight the importance of the enteroendocrine system in the cross talk between food proteins and the neuroendocrine network regulating energy balance.
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Affiliation(s)
- Giovanni Tulipano
- Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, 25123 Brescia, Italy
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Leucine and mTORc1 act independently to regulate 2-deoxyglucose uptake in L6 myotubes. Amino Acids 2020; 52:477-486. [PMID: 32108266 DOI: 10.1007/s00726-020-02829-0] [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: 09/05/2019] [Accepted: 02/08/2020] [Indexed: 01/15/2023]
Abstract
Chronic mTORc1 hyperactivation via obesity-induced hyperleucinaemia has been implicated in the development of insulin resistance, yet the direct impact of leucine on insulin-stimulated glucose uptake in muscle cells remains unclear. To address this, differentiated L6 myotubes were subjected to various compounds designed to either inhibit mTORc1 activity (rapamycin), blunt leucine intracellular import (BCH), or activate mTORc1 signalling (3BDO), prior to the determination of the uptake of the glucose analogue, 2-deoxyglucose (2-DG), in response to 1 mM insulin. In separate experiments, L6 myotubes were subject to various media concentrations of leucine (0-0.8 mM) for 24 h before 2-DG uptake in response to insulin was assessed. Both rapamycin and BCH blunted 2-DG uptake, irrespective of insulin administration, and this occurred in parallel with a decline in mTOR, 4E-BP1, and p70S6K phosphorylation status, but little effect on AKT phosphorylation. In contrast, reducing leucine media concentrations suppressed 2-DG uptake, both under insulin- and non-insulin-stimulated conditions, but did not alter the phosphorylation state of AKT-mTORc1 components examined. Unexpectedly, 3BDO failed to stimulate mTORc1 signalling, but, nonetheless, caused a significant increase in 2-DG uptake under non-insulin-stimulated conditions. Both leucine and mTORc1 influence glucose uptake in muscle cells independent of insulin administration, and this likely occurs via distinct but overlapping mechanisms.
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Dutchak PA, Estill-Terpack SJ, Plec AA, Zhao X, Yang C, Chen J, Ko B, Deberardinis RJ, Yu Y, Tu BP. Loss of a Negative Regulator of mTORC1 Induces Aerobic Glycolysis and Altered Fiber Composition in Skeletal Muscle. Cell Rep 2019; 23:1907-1914. [PMID: 29768191 PMCID: PMC6038807 DOI: 10.1016/j.celrep.2018.04.058] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 12/28/2017] [Accepted: 04/13/2018] [Indexed: 01/11/2023] Open
Abstract
The conserved GATOR1 complex consisting of NPRL2-NPRL3-DEPDC5 inhibits mammalian target of rapamycin complex 1 (mTORC1) in response to amino acid insufficiency. Here, we show that loss of NPRL2 and GATOR1 function in skeletal muscle causes constitutive activation of mTORC1 signaling in the fed and fasted states. Muscle fibers of NPRL2 knockout animals are significantly larger and show altered fiber-type composition, with more fast-twitch glycolytic and fewer slow-twitch oxidative fibers. NPRL2 muscle knockout mice also have altered running behavior and enhanced glucose tolerance. Furthermore, loss of NPRL2 induces aerobic glycolysis and suppresses glucose entry into the TCA cycle. Such chronic activation of mTORC1 leads to compensatory increases in anaplerotic pathways to replenish TCA intermediates that are consumed for biosynthetic purposes. These phenotypes reveal a fundamental role for the GATOR1 complex in the homeostatic regulation of mitochondrial functions (biosynthesis versus ATP) to mediate carbohydrate utilization in muscle.
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Affiliation(s)
- Paul A Dutchak
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada; CERVO Brain Research Centre, 2601 Chemin de la Canardière, Québec, QC, Canada
| | - Sandi J Estill-Terpack
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Abigail A Plec
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaozheng Zhao
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chendong Yang
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jun Chen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bookyung Ko
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ralph J Deberardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yonghao Yu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Dhanani ZN, Mann G, Adegoke OAJ. Depletion of branched-chain aminotransferase 2 (BCAT2) enzyme impairs myoblast survival and myotube formation. Physiol Rep 2019; 7:e14299. [PMID: 31833233 PMCID: PMC6908738 DOI: 10.14814/phy2.14299] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 12/15/2022] Open
Abstract
Much is known about the positive effects of branched-chain amino acids (BCAA) in regulating muscle protein metabolism. Comparatively much less is known about the effects of these amino acids and their metabolites in regulating myotube formation. Using cultured myoblasts, we showed that although leucine is required for myotube formation, this requirement is easily met by α-ketoisocaproic acid, the ketoacid of leucine. We then demonstrated increases in the expression of the first two enzymes in the catabolism of the three BCAA, branched-chain amino transferase (BCAT2) and branched-chain α-ketoacid dehydrogenase (BCKD), with ~3× increase in BCKD protein expression (p < .05) during differentiation. Furthermore, depletion of BCAT2 abolished myoblast differentiation, as indicated by reduction in the levels of myosin heavy chain-1, troponin and myogenin. Supplementation of incubation medium with branched-chain α-ketoacids or related metabolites derivable from BCAT2 functions did not rescue the defects. However, co-depletion of BCKD kinase partially rescued the defects. Collectively, our data indicate a requirement for BCAA catabolism during myotube formation and that this requirement for BCAT2 likely goes beyond the need for this enzyme to generate the α-ketoacids of the BCAA.
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Affiliation(s)
- Zameer N. Dhanani
- School of Kinesiology and Health ScienceMuscle Health Research CentreYork UniversityTorontoONCanada
| | - Gagandeep Mann
- School of Kinesiology and Health ScienceMuscle Health Research CentreYork UniversityTorontoONCanada
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Cogan KE, Carson BP, Patel B, Amigo-Benavent M, Jakeman PM, Egan B. Regulation of GLUT4 translocation in an in vitro cell model using postprandial human serum ex vivo. Exp Physiol 2019; 104:800-807. [PMID: 30864218 DOI: 10.1113/ep087356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 03/11/2019] [Indexed: 01/07/2023]
Abstract
NEW FINDINGS What is the research question? This study used a new experimental model, in which culture medium is conditioned with human serum ex vivo, to investigate nutrient-mediated regulation of GLUT4 translocation in skeletal muscle cells in vitro. What is the main finding and importance? Human serum stimulated GLUT4 translocation, an effect differentially modulated by whether the culture medium was conditioned with serum from fasted subjects or with serum collected after feeding of intact or hydrolysed whey protein. Conditioning cell culture medium with human serum ex vivo represents a new approach to elucidate the effects of ingesting specific nutrients on skeletal muscle cell metabolism. ABSTRACT Individual amino acids, amino acid mixtures and protein hydrolysates stimulate glucose uptake in many experimental models. To replicate better in vitro the dynamic postprandial response to feeding in vivo, in the present study we investigated the effects of culture media conditioned with fasted and postprandial human serum on GLUT4 translocation in L6-GLUT4myc myotubes. Serum samples were collected from healthy male participants (n = 8) at baseline (T0), 60 (T60) and 120 min (T120) after the ingestion of 0.33 g (kg body mass)-1 of intact (WPC) or hydrolysed (WPH) whey protein and an isonitrogenous non-essential amino acid (NEAA) control. L6-GLUT4myc myotubes were starved of serum and amino acids for 1 h before incubation for 1 h in medium containing 1% postprandial human serum, after which GLUT4 translocation was determined via colorimetric assay. Medium conditioned with fasted human serum at concentrations of 5-20% increased cell surface GLUT4myc abundance. Incubation with serum collected after the ingestion of WPH increased cell surface GLUT4myc at T60 relative to T0 [mean (lower, upper 95% confidence interval)]; [1.13 (1.05, 1.22)], whereas WPC [0.98 (0.90, 1.07)] or NEAA [1.02 (0.94, 1.11)] did not. The differential increases in cell surface GLUT4myc abundance were not explained by differences in serum concentrations of total, essential and branched-chain amino acids or insulin, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). Using a new ex vivo, in vitro approach, cell culture medium conditioned with postprandial serum after the ingestion of a whey protein hydrolysate increased GLUT4 translocation in skeletal muscle cells.
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Affiliation(s)
- Karl E Cogan
- Institute for Sport and Health, University College Dublin, Dublin, Ireland.,Food for Health Ireland, University College Dublin, Dublin, Ireland
| | - Brian P Carson
- Food for Health Ireland, University College Dublin, Dublin, Ireland.,Department of Physical Education & Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland.,Health Research Institute, University of Limerick, Limerick, Ireland
| | - Bijal Patel
- Food for Health Ireland, University College Dublin, Dublin, Ireland.,Department of Physical Education & Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland
| | - Miryam Amigo-Benavent
- Food for Health Ireland, University College Dublin, Dublin, Ireland.,Department of Physical Education & Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland
| | - Philip M Jakeman
- Food for Health Ireland, University College Dublin, Dublin, Ireland.,Department of Physical Education & Sport Sciences, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland.,Centre for Intervention in Infection, Inflammation and Immunity (4i), University of Limerick, Limerick, Ireland
| | - Brendan Egan
- Food for Health Ireland, University College Dublin, Dublin, Ireland.,School of Health and Human Performance, Dublin City University, Dublin, Ireland.,National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland
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Doan HV, Riyajan S, Iyara R, Chudapongse N. Antidiabetic activity, glucose uptake stimulation and α-glucosidase inhibitory effect of Chrysophyllum cainito L. stem bark extract. Altern Ther Health Med 2018; 18:267. [PMID: 30285723 PMCID: PMC6167849 DOI: 10.1186/s12906-018-2328-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/20/2018] [Indexed: 12/21/2022]
Abstract
Background Chrysophyllum cainito L., a tropical fruit tree, has been used as an alternative medicine for the treatment of diabetic patients in many countries. However, there is very limited scientific rationale for this medical use. The present study aimed to evaluate the antidiabetic activity of the extract from C. cainito stem bark and the possible mechanisms underlying this activity. Methods Phytochemistry and in vitro antioxidant capacity of the extract were studied. Hypoglycemic activity of the extract was examined in normal and alloxan-induced diabetic mice. The effect of C. cainito extract on glucose absorption and glucose uptake were conducted using mouse isolated jejunum and abdominal muscle, respectively. Finally, an in vitro effect of C. cainito extract on α-glucosidase activity was evaluated. Results C. cainito extract possessed a strong antioxidant activity comparable to the ascorbic acid and butylated hydroxytoluene. The extract at 500 mg/kg significantly reduced the area under curve of blood glucose level in oral glucose tolerance test in normal mice. In alloxan-induced diabetic model, similar to glibenclamide, a single dose of the extract significantly decreased fasting blood glucose level from 387.17 ± 29.84 mg/dl to 125.67 ± 62.09 mg/dl after 6 h of administration. From the isolated jejunum experiment, the extract at any doses used did not inhibit glucose absorption. However, the extract at 50 μg/ml significantly increased the amount of glucose uptake by abdominal muscles in the presence of insulin (P < 0.05). Lastly, it was found that the extract produced stronger inhibition of α-glucosidase activity (IC50 = 1.20 ± 0.09 μg/ml) than acarbose (IC50 = 198.17 ± 4.74 μg/ml). Conclusion Direct evidence of antidiabetic activity of C. cainito stem bark with possible modes of action, glucose uptake stimulation and α-glucosidase inhibitory effect, was reported for the first time herein. These data support the potential use of this plant for the treatment of diabetic patients.
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11
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Erukainure OL, Mopuri R, Chukwuma CI, Koorbanally NA, Islam MS. Phaseolus lunatus
(lima beans) abates Fe
2+
‐induced hepatic redox imbalance; inhibits intestinal glucose absorption and major carbohydrate catabolic enzymes; and modulates muscle glucose uptake. J Food Biochem 2018. [DOI: 10.1111/jfbc.12655] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Ochuko L. Erukainure
- Department of Biochemistry, School of Life Sciences University of KwaZulu‐Natal (Westville Campus) Durban South Africa
- Nutrition and Toxicology Division Federal Institute of Industrial Research Lagos Nigeria
| | - Ramgopal Mopuri
- Department of Biochemistry, School of Life Sciences University of KwaZulu‐Natal (Westville Campus) Durban South Africa
| | - Chika I. Chukwuma
- Department of Biochemistry, School of Life Sciences University of KwaZulu‐Natal (Westville Campus) Durban South Africa
- Faculty of Health Sciences, Department of Pharmacology University of Free State Bloemfontein South Africa
| | - Neil A. Koorbanally
- School of Chemistry and Physics University of KwaZulu‐Natal (Westville Campus) Durban South Africa
| | - Md. Shahidul Islam
- Department of Biochemistry, School of Life Sciences University of KwaZulu‐Natal (Westville Campus) Durban South Africa
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12
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Barnes T, Di Sebastiano KM, Vlavcheski F, Quadrilatero J, Tsiani EL, Mourtzakis M. Glutamate increases glucose uptake in L6 myotubes in a concentration- and time-dependent manner that is mediated by AMPK. Appl Physiol Nutr Metab 2018; 43:1307-1313. [PMID: 29847739 DOI: 10.1139/apnm-2018-0174] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Various in vivo studies have investigated the insulin response that is elicited when glutamate is elevated in circulation or in a given tissue; fewer studies have investigated the effects of glutamate on glucose uptake and handling. Glutamate ingestion in humans can attenuate rises in blood glucose following a carbohydrate load in the absence of increases in serum insulin concentrations. However, the underlying mechanisms have yet to be investigated. To elucidate the effects of glutamate on glucose handling in skeletal muscle tissue, differentiated rat L6 myocytes were treated with glutamate, and glucose uptake was assessed with the use of 2-[3H]-deoxy-d-glucose ([3H]-2-DG). Cells treated with 2 mmol/L glutamate experienced the greatest increase in [3H]-2-DG uptake relative to the control condition (177% ± 2% of control, P < 0.001) and the uptake was similar to that of metformin (184% ± 4%, P < 0.001). In line with these findings, differentiated glucose transporter 4 (GLUT4)-overexpressing myotubes treated with 2 mmol/L glutamate displayed significantly increased GLUT4 translocation when compared with the control condition (159% ± 8% of control, P < 0.001) and to an extent similar to that of insulin and metformin (181% ± 7% and 159% ± 12%, respectively). An AMP-activated protein kinase (AMPK) inhibitor (Compound C) abolished the glutamate-stimulated glucose uptake (98% ± 12% of control), and Western blotting revealed significantly elevated AMPK phosphorylation (278% ± 17% of control, P < 0.001) by glutamate. Our findings suggest that when muscle cells are exposed to increased glutamate concentrations, glucose uptake into these cells is augmented through AMPK activation, through mechanisms distinct from those of insulin and leucine.
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Affiliation(s)
- Tyler Barnes
- a Department of Kinesiology, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
| | - Katie M Di Sebastiano
- a Department of Kinesiology, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
| | - Filip Vlavcheski
- b Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Joe Quadrilatero
- a Department of Kinesiology, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
| | | | - Marina Mourtzakis
- a Department of Kinesiology, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
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13
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Restoration of Muscle Glycogen and Functional Capacity: Role of Post-Exercise Carbohydrate and Protein Co-Ingestion. Nutrients 2018; 10:nu10020253. [PMID: 29473893 PMCID: PMC5852829 DOI: 10.3390/nu10020253] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 02/11/2018] [Accepted: 02/15/2018] [Indexed: 12/31/2022] Open
Abstract
The importance of post-exercise recovery nutrition has been well described in recent years, leading to its incorporation as an integral part of training regimes in both athletes and active individuals. Muscle glycogen depletion during an initial prolonged exercise bout is a main factor in the onset of fatigue and so the replenishment of glycogen stores may be important for recovery of functional capacity. Nevertheless, nutritional considerations for optimal short-term (3–6 h) recovery remain incompletely elucidated, particularly surrounding the precise amount of specific types of nutrients required. Current nutritional guidelines to maximise muscle glycogen availability within limited recovery are provided under the assumption that similar fatigue mechanisms (i.e., muscle glycogen depletion) are involved during a repeated exercise bout. Indeed, recent data support the notion that muscle glycogen availability is a determinant of subsequent endurance capacity following limited recovery. Thus, carbohydrate ingestion can be utilised to influence the restoration of endurance capacity following exhaustive exercise. One strategy with the potential to accelerate muscle glycogen resynthesis and/or functional capacity beyond merely ingesting adequate carbohydrate is the co-ingestion of added protein. While numerous studies have been instigated, a consensus that is related to the influence of carbohydrate-protein ingestion in maximising muscle glycogen during short-term recovery and repeated exercise capacity has not been established. When considered collectively, carbohydrate intake during limited recovery appears to primarily determine muscle glycogen resynthesis and repeated exercise capacity. Thus, when the goal is to optimise repeated exercise capacity following short-term recovery, ingesting carbohydrate at an amount of ≥1.2 g kg body mass−1·h−1 can maximise muscle glycogen repletion. The addition of protein to carbohydrate during post-exercise recovery may be beneficial under circumstances when carbohydrate ingestion is sub-optimal (≤0.8 g kg body mass−1·h−1) for effective restoration of muscle glycogen and repeated exercise capacity.
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14
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Liao YH, Chen CY, Chen CN, Wu CY, Tsai SC. An Amino Acids Mixture Attenuates Glycemic Impairment but not Affects Adiposity Development in Rats Fed with AGEs-containing Diet. Int J Med Sci 2018; 15:176-187. [PMID: 29333102 PMCID: PMC5765731 DOI: 10.7150/ijms.22008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/18/2017] [Indexed: 12/17/2022] Open
Abstract
Background: Unhealthy western dietary patterns lead to over-consumption of fat and advanced glycation end-products (AGEs), and these account for the developments of obesity, diabetes, and related metabolic disorders. Certain amino acids (AAs) have been recently demonstrated to improve glycemia and reduce adiposity. Therefore, our primary aims were to examine whether feeding an isoleucine-enriched AA mixture (4.5% AAs; Ile: 3.0%, Leu: 1.0%, Val: 0.2%, Arg: 0.3% in the drinking water) would affect adiposity development and prevent the impairments of glycemic control in rats fed with the fat/AGE-containing diet (FAD). Methods: Twenty-four male Sprague-Dawley rats were assigned into 1) control diet (CD, N = 8), 2) FAD diet (FAD, N = 8), and 3) FAD diet plus AA (FAD/AA, N = 8). After 9-weeks intervention, the glycemic control capacity (glucose level, ITT, and HbA1c levels), body composition, and spontaneous locomotor activity (SLA) were evaluated, and the fasting blood samples were collected for analyzing metabolic related hormones (insulin, leptin, adiponectin, and corticosterone). The adipose tissues were also surgically collected and weighed. Results: FAD rats showed significant increases in weight gain, body fat %, blood glucose, HbA1c, leptin, and area under the curve of glucose during insulin tolerance test (ITT-glucose-AUC) in compared with the CD rats. However, the fasting levels of blood glucose, HbA1c, leptin, and ITT-glucose-AUC did not differ between CD and FAD/AA rats. FAD/AA rats also showed a greater increase in serum testosterone. Conclusion: The amino acid mixture consisting of Ile, Leu, Val, and Arg showed clear protective benefits on preventing the FAD-induced obesity and impaired glycemic control.
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Affiliation(s)
- Yi-Hung Liao
- Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, Taipei 11219, Taiwan
| | - Chung-Yu Chen
- Department of Exercise and Health Sciences, University of Taipei, Taipei 11153, Taiwan
| | - Chiao-Nan Chen
- Department of Physical Therapy and Assistive Technology, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei City 112, Taiwan
| | - Chia-Ying Wu
- Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, Taipei 11219, Taiwan
| | - Shiow-Chwen Tsai
- Institute of Sports Sciences, University of Taipei, Taipei 11153, Taiwan
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15
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Moghei M, Tavajohi-Fini P, Beatty B, Adegoke OAJ. Ketoisocaproic acid, a metabolite of leucine, suppresses insulin-stimulated glucose transport in skeletal muscle cells in a BCAT2-dependent manner. Am J Physiol Cell Physiol 2016; 311:C518-27. [PMID: 27488662 DOI: 10.1152/ajpcell.00062.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/26/2016] [Indexed: 01/18/2023]
Abstract
Although leucine has many positive effects on metabolism in multiple tissues, elevated levels of this amino acid and the other branched-chain amino acids (BCAAs) and their metabolites are implicated in obesity and insulin resistance. While some controversies exist about the direct effect of leucine on insulin action in skeletal muscle, little is known about the direct effect of BCAA metabolites. Here, we first showed that the inhibitory effect of leucine on insulin-stimulated glucose transport in L6 myotubes was dampened when other amino acids were present, due in part to a 140% stimulation of basal glucose transport (P < 0.05). Importantly, we also showed that α-ketoisocaproic acid (KIC), an obligatory metabolite of leucine, stimulated mTORC1 signaling but suppressed insulin-stimulated glucose transport (-34%, P < 0.05) in an mTORC1-dependent manner. The effect of KIC on insulin-stimulated glucose transport was abrogated in cells depleted of branched-chain aminotransferase 2 (BCAT2), the enzyme that catalyzes the reversible transamination of KIC to leucine. We conclude that although KIC can modulate muscle glucose metabolism, this effect is likely a result of its transamination back to leucine. Therefore, limiting the availability of leucine, rather than those of its metabolites, to skeletal muscle may be more critical in the management of insulin resistance and its sequelae.
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Affiliation(s)
- Mahshid Moghei
- School of Kinesiology and Health Science and Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Pegah Tavajohi-Fini
- School of Kinesiology and Health Science and Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Brendan Beatty
- School of Kinesiology and Health Science and Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Olasunkanmi A J Adegoke
- School of Kinesiology and Health Science and Muscle Health Research Centre, York University, Toronto, Ontario, Canada
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16
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Paradoxical effect of rapamycin on inflammatory stress-induced insulin resistance in vitro and in vivo. Sci Rep 2015; 5:14959. [PMID: 26449763 PMCID: PMC4598825 DOI: 10.1038/srep14959] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/11/2015] [Indexed: 12/16/2022] Open
Abstract
Insulin resistance is closely related to inflammatory stress and the mammalian target of rapamycin/S6 kinase (mTOR/S6K) pathway. The present study investigated whether rapamycin, a specific inhibitor of mTOR, ameliorates inflammatory stress-induced insulin resistance in vitro and in vivo. We used tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) stimulation in HepG2 hepatocytes, C2C12 myoblasts and 3T3-L1 adipocytes and casein injection in C57BL/6J mice to induce inflammatory stress. Our results showed that inflammatory stress impairs insulin signaling by reducing the expression of total IRS-1, p-IRS-1 (tyr632), and p-AKT (ser473); it also activates the mTOR/S6K signaling pathway both in vitro and in vivo. In vitro, rapamycin treatment reversed inflammatory cytokine-stimulated IRS-1 serine phosphorylation, increased insulin signaling to AKT and enhanced glucose utilization. In vivo, rapamycin treatment also ameliorated the impaired insulin signaling induced by inflammatory stress, but it induced pancreatic β-cell apoptosis, reduced pancreatic β-cell function and enhanced hepatic gluconeogenesis, thereby resulting in hyperglycemia and glucose intolerance in casein-injected mice. Our results indicate a paradoxical effect of rapamycin on insulin resistance between the in vitro and in vivo environments under inflammatory stress and provide additional insight into the clinical application of rapamycin.
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17
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The role of leucine and its metabolites in protein and energy metabolism. Amino Acids 2015; 48:41-51. [DOI: 10.1007/s00726-015-2067-1] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 07/29/2015] [Indexed: 01/30/2023]
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18
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Wang B, Ding Z, Wang W, Hwang J, Liao YH, Ivy JL. The effect of an amino acid beverage on glucose response and glycogen replenishment after strenuous exercise. Eur J Appl Physiol 2015; 115:1283-94. [PMID: 25600772 DOI: 10.1007/s00421-015-3098-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/31/2014] [Indexed: 11/26/2022]
Abstract
PURPOSE We previously reported that an amino acid mixture (AA) was able to lower the glucose response to an oral glucose challenge in both rats and humans. Increased glucose uptake and glycogen storage in muscle might be associated with the faster blood glucose clearance. We therefore tested the effect of two different doses of AA provided with a carbohydrate supplement on blood glucose homeostasis and muscle glycogen replenishment in human subjects after strenuous aerobic exercise. METHODS Ten subjects received a carbohydrate (1.2 g/kg body weight, CHO), CHO/HAA (CHO + 13 g AA), or CHO/LAA (CHO + 6.5 g AA) supplement immediately and 2 h after an intense cycling bout. Muscle biopsies were performed immediately and 4 h after exercise. RESULTS The glucose responses for CHO/HAA and CHO/LAA during recovery were significantly lower than CHO, as was the glucose area under the curve (CHO/HAA 1259.9 ± 27.7, CHO/LAA 1251.5 ± 47.7, CHO 1376.8 ± 52.9 mmol/L 4 h, p < 0.05). Glycogen storage rate was significantly lower in CHO/HAA compared with CHO, while it did not differ significantly between CHO/LAA or CHO (CHO/HAA 15.4 ± 2.0, CHO/LAA 18.1 ± 2.0, CHO 21.5 ± 1.4 µmol/g wet muscle 4 h). CHO/HAA caused a significantly higher insulin response and a greater effect on mTOR and Akt/PKB phosphorylation compared with CHO. Phosphorylation of AS160 and glycogen synthase did not differ across treatments. Likewise, there were no differences in blood lactate across treatments. CONCLUSIONS The AA lowered the glucose response to a carbohydrate supplement after strenuous exercise. However, it was not effective in facilitating subsequent muscle glycogen storage.
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Affiliation(s)
- Bei Wang
- Department of Kinesiology and Health Education, Exercise Physiology and Metabolism Laboratory, University of Texas at Austin, Austin, TX, USA,
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19
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Liu H, Liu R, Xiong Y, Li X, Wang X, Ma Y, Guo H, Hao L, Yao P, Liu L, Wang D, Yang X. Leucine facilitates the insulin-stimulated glucose uptake and insulin signaling in skeletal muscle cells: involving mTORC1 and mTORC2. Amino Acids 2014; 46:1971-9. [PMID: 24806638 DOI: 10.1007/s00726-014-1752-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 04/16/2014] [Indexed: 10/25/2022]
Abstract
Leucine, a branched-chain amino acid, has been shown to promote glucose uptake and increase insulin sensitivity in skeletal muscle, but the exact mechanism remains unestablished. We addressed this issue in cultured skeletal muscle cells in this study. Our results showed that leucine alone did not have an effect on glucose uptake or phosphorylation of protein kinase B (AKT), but facilitated the insulin-induced glucose uptake and AKT phosphorylation. The insulin-stimulated glucose uptake and AKT phosphorylation were inhibited by the phosphatidylinositol 3-kinase inhibitor, wortmannin, but the inhibition was partially reversed by leucine. The inhibitor of mammalian target of rapamycin complex 1 (mTORC1), rapamycin, had no effect on the insulin-stimulated glucose uptake, but eliminated the facilitating effect of leucine in the insulin-stimulated glucose uptake and AKT phosphorylation. In addition, leucine facilitation of the insulin-induced AKT phosphorylation was neutralized by knocking down the core component of the mammalian target of rapamycin complex 2 (mTORC2) with specific siRNA. Together, these findings show that leucine can facilitate the insulin-induced insulin signaling and glucose uptake in skeletal muscle cells through both mTORC1 and mTORC2, implicating the potential importance of this amino acid in glucose homeostasis and providing new mechanistic insights.
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Affiliation(s)
- Hui Liu
- Hubei Key Laboratory of Food Nutrition and Safety, MOE Key Laboratory of Environment and Health, Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan, 430030, Hubei, China
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Macedo MP, Lima IS, Gaspar JM, Afonso RA, Patarrão RS, Kim YB, Ribeiro RT. Risk of postprandial insulin resistance: the liver/vagus rapport. Rev Endocr Metab Disord 2014; 15:67-77. [PMID: 24174131 PMCID: PMC4000159 DOI: 10.1007/s11154-013-9281-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ingestion of a meal is the greatest challenge faced by glucose homeostasis. The surge of nutrients has to be disposed quickly, as high concentrations in the bloodstream may have pathophysiological effects, and also properly, as misplaced reserves may induce problems in affected tissues. Thus, loss of the ability to adequately dispose of ingested nutrients can be expected to lead to glucose intolerance, and favor the development of pathologies. Achieving interplay of several organs is of upmost importance to maintain effectively postprandial glucose clearance, with the liver being responsible of orchestrating global glycemic control. This dogmatic role of the liver in postprandial insulin sensitivity is tightly associated with the vagus nerve. Herein, we uncover the behaviour of metabolic pathways determined by hepatic parasympathetic function status, in physiology and in pathophysiology. Likewise, the inquiry expands to address the impact of a modern lifestyle, especially one's feeding habits, on the hepatic parasympathetic nerve control of glucose metabolism.
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Affiliation(s)
- Maria Paula Macedo
- CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa (UNL), 1169-056, Lisboa, Portugal,
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Bernard JR, Liao YH, Ding Z, Hara D, Kleinert M, Nelson JL, Ivy JL. An amino acid mixture improves glucose tolerance and lowers insulin resistance in the obese Zucker rat. Amino Acids 2013; 45:191-203. [DOI: 10.1007/s00726-013-1488-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 03/11/2013] [Indexed: 12/27/2022]
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Bernard JR, Liao YH, Doerner PG, Ding Z, Hsieh M, Wang W, Nelson JL, Ivy JL. An amino acid mixture is essential to optimize insulin-stimulated glucose uptake and GLUT4 translocation in perfused rodent hindlimb muscle. J Appl Physiol (1985) 2012; 113:97-104. [DOI: 10.1152/japplphysiol.01484.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to investigate whether an amino acid mixture increases glucose uptake across perfused rodent hindlimb muscle in the presence and absence of a submaximal insulin concentration, and if the increase in glucose uptake is related to an increase in GLUT4 plasma membrane density. Sprague-Dawley rats were separated into one of four treatment groups: basal, amino acid mixture, submaximal insulin, or amino acid mixture with submaximal insulin. Glucose uptake was greater for both insulin-stimulated treatments compared with the non-insulin-stimulated treatment groups but amino acids only increased glucose uptake in the presence of insulin. Phosphatidylinositol 3-kinase (PI 3-kinase) activity was greater for both insulin-stimulated treatments with amino acids having no additional impact. Akt substrate of 160 kDa (AS160) phosphorylation, however, was increased by the amino acids in the presence of insulin, but not in the absence of insulin. AMPK was unaffected by insulin or amino acids. Plasma membrane GLUT4 protein concentration was greater in the rats treated with insulin compared with no insulin in the perfusate. In the presence of insulin, amino acids increased GLUT4 density in the plasma membrane but had no effect in the absence of insulin. AS160 phosphorylation and plasma membrane GLUT4 density accounted for 76% of the variability in muscle glucose uptake. Collectively, these findings suggest that the beneficial effects of an amino acid mixture on skeletal muscle glucose uptake, in the presence of a submaximal insulin concentration, are due to an increase in AS160 phosphorylation and plasma membrane-associated GLUT4, but independent of PI 3-kinase and AMPK activation.
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Affiliation(s)
- Jeffrey R. Bernard
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | - Yi-Hung Liao
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | - Phillip G. Doerner
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | - Zhenping Ding
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | - Ming Hsieh
- Taipei Sports University, Department of Sports Sciences, Taipei, Taiwan, Republic of China
| | - Wanyi Wang
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
| | | | - John L. Ivy
- Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas
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Amino acid mixture acutely improves the glucose tolerance of healthy overweight adults. Nutr Res 2012; 32:30-8. [DOI: 10.1016/j.nutres.2011.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 11/29/2011] [Accepted: 11/29/2011] [Indexed: 11/22/2022]
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