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Dimou A, Tsimihodimos V, Bairaktari E. The Critical Role of the Branched Chain Amino Acids (BCAAs) Catabolism-Regulating Enzymes, Branched-Chain Aminotransferase (BCAT) and Branched-Chain α-Keto Acid Dehydrogenase (BCKD), in Human Pathophysiology. Int J Mol Sci 2022; 23:ijms23074022. [PMID: 35409380 PMCID: PMC8999875 DOI: 10.3390/ijms23074022] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 12/26/2022] Open
Abstract
Branched chain amino acids (BCAAs), leucine, isoleucine and valine, are essential amino acids widely studied for their crucial role in the regulation of protein synthesis mainly through the activation of the mTOR signaling pathway and their emerging recognition as players in the regulation of various physiological and metabolic processes, such as glucose homeostasis. BCAA supplementation is primarily used as a beneficial nutritional intervention in chronic liver and kidney disease as well as in muscle wasting disorders. However, downregulated/upregulated plasma BCAAs and their defective catabolism in various tissues, mainly due to altered enzymatic activity of the first two enzymes in their catabolic pathway, BCAA aminotransferase (BCAT) and branched-chain α-keto acid dehydrogenase (BCKD), have been investigated in many nutritional and disease states. The current review focused on the underlying mechanisms of altered BCAA catabolism and its contribution to the pathogenesis of a numerous pathological conditions such as diabetes, heart failure and cancer. In addition, we summarize findings that indicate that the recovery of the dysregulated BCAA catabolism may be associated with an improved outcome and the prevention of serious disease complications.
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Affiliation(s)
- Aikaterini Dimou
- Laboratory of Clinical Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece;
| | - Vasilis Tsimihodimos
- Department of Internal Medicine, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece;
| | - Eleni Bairaktari
- Laboratory of Clinical Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece;
- Correspondence: ; Tel.: +30-26510-07620
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Bagley JR, Burghardt KJ, McManus R, Howlett B, Costa PB, Coburn JW, Arevalo JA, Malek MH, Galpin AJ. Epigenetic Responses to Acute Resistance Exercise in Trained vs. Sedentary Men. J Strength Cond Res 2020; 34:1574-1580. [PMID: 32459413 DOI: 10.1519/jsc.0000000000003185] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bagley, JR, Burghardt, KJ, McManus, R, Howlett, B, Costa, PB, Coburn, JW, Arevalo, JA, Malek, MH, and Galpin, AJ. Epigenetic responses to acute resistance exercise in trained vs. sedentary men. J Strength Cond Res 34(6): 1574-1580, 2020-Acute resistance exercise (RE) alters DNA methylation, an epigenetic process that influences gene expression and regulates skeletal muscle adaptation. This aspect of cellular remodeling is poorly understood, especially in resistance-trained (RT) individuals. The study purpose was to examine DNA methylation in response to acute RE in RT and sedentary (SED) young men, specifically targeting genes responsible for metabolic, inflammatory, and hypertrophic muscle adaptations. Vastus lateralis biopsies were performed before (baseline), 30 minutes after, and 4 hours after an acute RE bout (3 × 10 repetitions at 70% 1 repetition maximum [1RM] leg press and leg extension) in 11 RT (mean ± SEM: age = 26.1 ± 1.0 years; body mass = 84.3 ± 0.2 kg; leg press 1RM = 412.6 ± 25.9 kg) and 8 SED (age = 22.9 ± 1.1 years; body mass = 75.6 ± 0.3 kg; leg press 1RM = 164.8 ± 22.5 kg) men. DNA methylation was analyzed through methylation sensitive high-resolution melting using real-time polymerase chain reaction. Separate 2 (group) × 3 (time) repeated-measures analyses of variance and analyses of covariance were performed to examine changes in DNA methylation for each target gene. Results showed that acute RE (a) hypomethylated LINE-1 (measure of global methylation) in RT but not SED, (b) hypermethylated metabolic genes (GPAM and SREBF2) in RT, while lowering SREBF2 methylation in SED, and (c) did not affect methylation of genes associated with inflammation (IL-6 and TNF-α) or hypertrophy (mTOR and AKT1). However, basal IL-6 and TNF-α were lower in SED compared with RT. These findings indicate the same RE stimulus can illicit different epigenetic responses in RT vs. SED men and provides a molecular mechanism underpinning the need for differential training stimuli based on subject training backgrounds.
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Affiliation(s)
- James R Bagley
- Department of Kinesiology, Muscle Physiology Laboratory, San Francisco State University, San Francisco, California
| | - Kyle J Burghardt
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Ryan McManus
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Bradley Howlett
- Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Pablo B Costa
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Jared W Coburn
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Jose A Arevalo
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
| | - Moh H Malek
- Integrative Physiology of Exercise Laboratory, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Andrew J Galpin
- Department of Kinesiology, Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California; and
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Triolo M, Hood DA. Mitochondrial breakdown in skeletal muscle and the emerging role of the lysosomes. Arch Biochem Biophys 2018; 661:66-73. [PMID: 30439362 DOI: 10.1016/j.abb.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/13/2018] [Accepted: 11/05/2018] [Indexed: 11/15/2022]
Abstract
Skeletal muscle mitochondria are essential in providing the energy required for locomotion. In response to contractile activity, the production of mitochondria is upregulated to meet the energy demands placed upon muscle cells. In a coordinated fashion, exercise also promotes the breakdown of dysfunctional mitochondria via mitophagy. Mitophagy is characterized by the selection of poorly functioning organelles, engulfment in an autophagosome and transport to lysosomes for degradation. In addition to the activation of mitophagy, exercise also elevates lysosome biogenesis. This coordinated increase in mitophagy targeting and lysosomal biogenesis serves to enhance the capacity for autophagosomal degradation, thereby aiding in the maintenance of mitochondrial quality. Lysosome dysfunction, as observed in lysosomal storage disorders (LSDs), negatively impacts mitochondrial function likely through the suppression of mitophagy. Since exercise is capable of activating mitophagy and lysosome biogenesis, researchers have begun to investigate physical activity as an effective therapy for LSDs. This review summarizes the current understanding of how mitophagy and lysosomal biogenesis are regulated in exercising skeletal, with potential therapeutic implications.
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Affiliation(s)
- Matthew Triolo
- Muscle Health Research Centre, York University, Toronto, Ontario, M3J 1P3, Canada; School of Kinesiology and Health Science, York University, Toronto, Ontario, M3J 1P3, Canada.
| | - David A Hood
- Muscle Health Research Centre, York University, Toronto, Ontario, M3J 1P3, Canada; School of Kinesiology and Health Science, York University, Toronto, Ontario, M3J 1P3, Canada.
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Figueiredo VC, Markworth JF, Cameron-Smith D. Considerations on mTOR regulation at serine 2448: implications for muscle metabolism studies. Cell Mol Life Sci 2017; 74:2537-2545. [PMID: 28220207 PMCID: PMC11107628 DOI: 10.1007/s00018-017-2481-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 02/03/2023]
Abstract
The mammalian target of rapamycin (mTOR) complex exerts a pivotal role in protein anabolism and cell growth. Despite its importance, few studies adequately address the complexity of phosphorylation of the mTOR protein itself to enable conclusions to be drawn on the extent of kinase activation following this event. In particular, a large number of studies in the skeletal muscle biology field have measured Serine 2448 (Ser2448) phosphorylation as a proxy of mTOR kinase activity. However, the evidence to be described is that Ser2448 is not a measure of mTOR kinase activity nor is a target of AKT activity and instead has inhibitory effects on the kinase that is targeted by the downstream effector p70S6K in a negative feedback loop mechanism, which is evident when revisiting muscle research studies. It is proposed that this residue modification acts as a fine-tuning mechanism that has been gained during vertebrate evolution. In conclusion, it is recommended that Ser2448 is an inadequate measure and that preferential analysis of mTORC1 activation should focus on the downstream and effector proteins, including p70S6K and 4E-BP1, along mTOR protein partners that bind to mTOR protein to form the active complexes 1 and 2.
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Affiliation(s)
- Vandré Casagrande Figueiredo
- The Liggins Institute, University of Auckland, 85 Park Road, Grafton, Private Bag 92019, Auckland, 1023, New Zealand
| | - James F Markworth
- The Liggins Institute, University of Auckland, 85 Park Road, Grafton, Private Bag 92019, Auckland, 1023, New Zealand
| | - David Cameron-Smith
- The Liggins Institute, University of Auckland, 85 Park Road, Grafton, Private Bag 92019, Auckland, 1023, New Zealand.
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Kim CH, Shin JH, Hwang SJ, Choi YH, Kim DS, Kim CM. Schisandrae fructus enhances myogenic differentiation and inhibits atrophy through protein synthesis in human myotubes. Int J Nanomedicine 2016; 11:2407-15. [PMID: 27330287 PMCID: PMC4898430 DOI: 10.2147/ijn.s101299] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Schisandrae fructus (SF) has recently been reported to increase skeletal muscle mass and inhibit atrophy in mice. We investigated the effect of SF extract on human myotube differentiation and its acting pathway. Various concentrations (0.1–10 μg/mL) of SF extract were applied on human skeletal muscle cells in vitro. Myotube area and fusion index were measured to quantify myotube differentiation. The maximum effect was observed at 0.5 μg/mL of SF extract, enhancing differentiation up to 1.4-fold in fusion index and 1.6-fold in myotube area at 8 days after induction of differentiation compared to control. Phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 and 70 kDa ribosomal protein S6 kinase, which initiate translation as downstream of mammalian target of rapamycin pathway, was upregulated in early phases of differentiation after SF treatment. SF also attenuated dexamethasone-induced atrophy. In conclusion, we show that SF augments myogenic differentiation and attenuates atrophy by increasing protein synthesis through mammalian target of rapamycin/70 kDa ribosomal protein S6 kinase and eukaryotic translation initiation factor 4E-binding protein 1 signaling pathway in human myotubes. SF can be a useful natural dietary supplement in increasing skeletal muscle mass, especially in the aged with sarcopenia and the patients with disuse atrophy.
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Affiliation(s)
- Cy Hyun Kim
- Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea; Center for Anti-Aging Industry, Pusan National University, Busan, Republic of Korea
| | - Jin-Hong Shin
- Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea; Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Sung Jun Hwang
- Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea; Center for Anti-Aging Industry, Pusan National University, Busan, Republic of Korea
| | - Yung Hyun Choi
- Department of Biochemistry, Dong-eui University College of Korean Medicine, Busan, Republic of Korea
| | - Dae-Seong Kim
- Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea; Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
| | - Cheol Min Kim
- Center for Anti-Aging Industry, Pusan National University, Busan, Republic of Korea; Department of Biomedical Informatics, Pusan National University School of Medicine, Yangsan, Republic of Korea
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Woo JH, Shin KO, Lee YH, Jang KS, Bae JY, Roh HT. Effects of treadmill exercise on skeletal muscle mTOR signaling pathway in high-fat diet-induced obese mice. J Phys Ther Sci 2016; 28:1260-5. [PMID: 27190464 PMCID: PMC4868224 DOI: 10.1589/jpts.28.1260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/08/2016] [Indexed: 11/24/2022] Open
Abstract
[Purpose] The aim of this study was to investigate the effects of regular treadmill
exercise on skeletal muscle Rictor-Akt and mTOR-Raptor-S6K1 signaling pathway in high-fat
diet-induced obese mice. [Subjects and Methods] Four- week-old C57BL/6 mice were adopted
and classified into normal diet group (ND, n = 10), normal diet and training group (NDT, n
= 10), high-fat diet group (HF, n = 10), and high-fat diet and training group (HFT, n =
10). The exercise program consisted of a treadmill exercise provided at low intensity for
1–4 weeks, and moderate intensity for 5–8 weeks. [Results] The Western blot method was
used to measure the expression of mTOR, Raptor, S6K1, Rictor, and Akt proteins in the
soleus muscle. mTOR levels were significantly higher in the HF group than in the ND and
NDT groups. Raptor/mTORC1 and S6K1 levels were significantly higher in the HF group than
in all the other groups. Akt levels were significantly lower in the HF group than in the
NDT group. The risk of obesity may be associated with the overactivation of
the mTOR-Raptor-S6K1 signaling pathway and a decrease in Akt levels. [Conclusion] This
study also indicates that performing aerobic exercise may be associated with the
downregulation of the mTOR-Raptor-S6K1 pathway.
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Affiliation(s)
- Jin Hee Woo
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
| | - Ki Ok Shin
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
| | - Yul Hyo Lee
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
| | - Ki Soeng Jang
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
| | - Ju Yong Bae
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
| | - Hee Tae Roh
- Department of Physical Education, College of Arts and Physical Education, Dong-A University, Republic of Korea
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7
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Rivas DA, McDonald DJ, Rice NP, Haran PH, Dolnikowski GG, Fielding RA. Diminished anabolic signaling response to insulin induced by intramuscular lipid accumulation is associated with inflammation in aging but not obesity. Am J Physiol Regul Integr Comp Physiol 2016; 310:R561-9. [PMID: 26764052 DOI: 10.1152/ajpregu.00198.2015] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 01/11/2016] [Indexed: 12/24/2022]
Abstract
The loss of skeletal muscle mass is observed in many pathophysiological conditions, including aging and obesity. The loss of muscle mass and function with aging is defined as sarcopenia and is characterized by a mismatch between skeletal muscle protein synthesis and breakdown. Characteristic metabolic features of both aging and obesity are increases in intramyocellular lipid (IMCL) content in muscle. IMCL accumulation may play a mechanistic role in the development of anabolic resistance and the progression of muscle atrophy in aging and obesity. In the present study, aged and high-fat fed mice were used to determine mechanisms leading to muscle loss. We hypothesized the accumulation of bioactive lipids in skeletal muscle, such as ceramide or diacylglycerols, leads to insulin resistance with aging and obesity and the inability to activate protein synthesis, contributing to skeletal muscle loss. We report a positive association between bioactive lipid accumulation and the loss of lean mass and muscle strength. Obese and aged animals had significantly higher storage of ceramide and diacylglycerol compared with young. Furthermore, there was an attenuated insulin response in components of the mTOR anabolic signaling pathway. We also observed differential increases in the expression of inflammatory cytokines and the phosphorylation of IκBα with aging and obesity. These data challenge the accepted role of increased inflammation in obesity-induced insulin resistance in skeletal muscle. Furthermore, we have now established IκBα with a novel function in aging-associated muscle loss that may be independent of its previously understood role as an NF-κB inhibitor.
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Affiliation(s)
- Donato A Rivas
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Devin J McDonald
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Nicholas P Rice
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Prashanth H Haran
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Gregory G Dolnikowski
- Mass Spectrometry Unit; Jean Mayer U.S. Department of Agriculture, Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
| | - Roger A Fielding
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
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Margolis LM, Rivas DA. Implications of exercise training and distribution of protein intake on molecular processes regulating skeletal muscle plasticity. Calcif Tissue Int 2015; 96:211-21. [PMID: 25348078 PMCID: PMC6691734 DOI: 10.1007/s00223-014-9921-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/15/2014] [Indexed: 12/19/2022]
Abstract
To optimize its function, skeletal muscle exhibits exceptional plasticity and possesses the fundamental capacity to adapt its metabolic and contractile properties in response to various external stimuli (e.g., external loading, nutrient availability, and humoral factors). The adaptability of skeletal muscle, along with its relatively large mass and high metabolic rate, makes this tissue an important contributor to whole body health and mobility. This adaptational process includes changes in the number, size, and structural/functional properties of the myofibers. The adaptations of skeletal muscle to exercise are highly interrelated with dietary intake, particularly dietary protein, which has been shown to further potentiate exercise training-induced adaptations. Understanding the molecular adaptation of skeletal muscle to exercise and protein consumption is vital to elicit maximum benefit from exercise training to improve human performance and health. In this review, we will provide an overview of the molecular pathways regulating skeletal muscle adaptation to exercise and protein, and discuss the role of subsequent timing of nutrient intake following exercise.
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Affiliation(s)
- Lee M Margolis
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center On Aging, Tufts University, 711 Washington Street, Boston, MA, 02111, USA
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Castorena CM, Arias EB, Sharma N, Cartee GD. Effects of a brief high-fat diet and acute exercise on the mTORC1 and IKK/NF-κB pathways in rat skeletal muscle. Appl Physiol Nutr Metab 2014; 40:251-62. [PMID: 25706655 DOI: 10.1139/apnm-2014-0412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
One exercise session can improve subsequent insulin-stimulated glucose uptake by skeletal muscle in healthy and insulin-resistant individuals. Our first aim was to determine whether a brief (2 weeks) high-fat diet (HFD) that caused muscle insulin resistance would activate the mammalian target of rapamycin complex 1 (mTORC1) and/or inhibitor of κB kinase/nuclear factor κB (IKK/NF-κB) pathways, which are potentially linked to induction of insulin resistance. Our second aim was to determine whether acute exercise that improved insulin-stimulated glucose uptake by muscles would attenuate activation of these pathways. We compared HFD-fed rats with rats fed a low-fat diet (LFD). Some animals from each diet group were sedentary and others were studied 3 h postexercise, when insulin-stimulated glucose uptake was increased. The results did not provide evidence that brief HFD activated either the mTORC1 (including phosphorylation of mTOR(Ser2448), TSC2(Ser939), p70S6K(Thr412), and RPS6(Ser235/236)) or the IKK/NF-κB (including abundance of IκBα or phosphorylation of NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)) pathway in insulin-resistant muscles. Exercise did not oppose the activation of either pathway, as evidenced by no attenuation of phosphorylation of key proteins in the IKK/NF-κB pathway (NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)), unaltered IκBα abundance, and no attenuation of phosphorylation of key proteins in the mTORC1 pathway (mTOR(Ser2448), TSC2(Ser939), and RPS6(Ser235/236)). Instead, exercise induced greater phosphorylation of 2 proteins of the mTORC1 pathway (PRAS40(Thr246) and p70S6K(Thr412)) in insulin-stimulated muscles, regardless of diet. Insulin resistance induced by a brief HFD was not attributable to greater activation of the mTORC1 or the IKK/NF-κB pathway in muscle, and exercise-induced improvement in insulin sensitivity was not attributable to attenuated activation of these pathways in muscle.
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Affiliation(s)
- Carlos M Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI 48109-2214, USA
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Areta JL, Hawley JA, Ye JM, Chan MS, Coffey VG. Increasing leucine concentration stimulates mechanistic target of rapamycin signaling and cell growth in C2C12 skeletal muscle cells. Nutr Res 2014; 34:1000-7. [DOI: 10.1016/j.nutres.2014.09.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 09/23/2014] [Accepted: 09/26/2014] [Indexed: 10/24/2022]
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Hoppeler H, Baum O, Lurman G, Mueller M. Molecular mechanisms of muscle plasticity with exercise. Compr Physiol 2013; 1:1383-412. [PMID: 23733647 DOI: 10.1002/cphy.c100042] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The skeletal muscle phenotype is subject to considerable malleability depending on use. Low-intensity endurance type exercise leads to qualitative changes of muscle tissue characterized mainly by an increase in structures supporting oxygen delivery and consumption. High-load strength-type exercise leads to growth of muscle fibers dominated by an increase in contractile proteins. In low-intensity exercise, stress-induced signaling leads to transcriptional upregulation of a multitude of genes with Ca(2+) signaling and the energy status of the muscle cells sensed through AMPK being major input determinants. Several parallel signaling pathways converge on the transcriptional co-activator PGC-1α, perceived as being the coordinator of much of the transcriptional and posttranscriptional processes. High-load training is dominated by a translational upregulation controlled by mTOR mainly influenced by an insulin/growth factor-dependent signaling cascade as well as mechanical and nutritional cues. Exercise-induced muscle growth is further supported by DNA recruitment through activation and incorporation of satellite cells. Crucial nodes of strength and endurance exercise signaling networks are shared making these training modes interdependent. Robustness of exercise-related signaling is the consequence of signaling being multiple parallel with feed-back and feed-forward control over single and multiple signaling levels. We currently have a good descriptive understanding of the molecular mechanisms controlling muscle phenotypic plasticity. We lack understanding of the precise interactions among partners of signaling networks and accordingly models to predict signaling outcome of entire networks. A major current challenge is to verify and apply available knowledge gained in model systems to predict human phenotypic plasticity.
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Affiliation(s)
- Hans Hoppeler
- Institute of Anatomy, University of Bern, Bern, Switzerland.
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12
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Areta JL, Burke LM, Ross ML, Camera DM, West DWD, Broad EM, Jeacocke NA, Moore DR, Stellingwerff T, Phillips SM, Hawley JA, Coffey VG. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol 2013; 591:2319-31. [PMID: 23459753 DOI: 10.1113/jphysiol.2012.244897] [Citation(s) in RCA: 290] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distributions of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. Twenty-four healthy trained males were assigned to three groups (n = 8/group) and undertook a bout of resistance exercise followed by ingestion of 80 g of whey protein throughout 12 h recovery in one of the following protocols: 8 × 10 g every 1.5 h (PULSE); 4 × 20 g every 3 h (intermediate: INT); or 2 × 40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h post exercise. Resting and post-exercise MPS (l-[ring-(13)C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols increased MPS above rest throughout 1-12 h recovery (88-148%, P < 0.02), but INT elicited greater MPS than PULSE and BOLUS (31-48%, P < 0.02). In general signalling showed a BOLUS>INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has the potential to maximize outcomes of resistance training for attaining peak muscle mass.
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Affiliation(s)
- José L Areta
- Exercise Metabolism Group, Health Innovations Research Institute, School of Medical Sciences, RMIT University, Melbourne, Australia
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Rivas DA, Morris EP, Haran PH, Pasha EP, Morais MDS, Dolnikowski GG, Phillips EM, Fielding RA. Increased ceramide content and NFκB signaling may contribute to the attenuation of anabolic signaling after resistance exercise in aged males. J Appl Physiol (1985) 2012; 113:1727-36. [PMID: 23042913 DOI: 10.1152/japplphysiol.00412.2012] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
One of the most fundamental adaptive physiological events is the response of skeletal muscle to high-intensity resistance exercise, resulting in increased protein synthesis and ultimately larger muscle mass. However, muscle growth in response to contraction is attenuated in older humans. Impaired contractile-induced muscle growth may contribute to sarcopenia: the age-associated loss of muscle mass and function that is manifested by loss of strength, contractile capacity, and endurance. We hypothesized that the storage of ceramide would be increased in older individuals and this would be associated with increases in NFκB signaling and a decreased anabolic response to exercise. To test this hypothesis we measured ceramides at rest and anabolic and NFκB signaling after an acute bout of high-intensity resistance exercise in young and older males. Using lipidomics analysis we show there was a 156% increase in the accumulation of C16:0-ceramide (P < 0.05) and a 30% increase in C20:0-ceramide (P < 0.05) in skeletal muscle with aging, although there was no observable difference in total ceramide. C16:0-ceramide content was negatively correlated (P = 0.008) with lower leg lean mass. Aging was associated with a ~60% increase in the phosphorylation of the proinflammatory transcription factor NFκB in the total and nuclear cell fractions (P < 0.05). Furthermore, there was an attenuated activation of anabolic signaling molecules such as Akt (P < 0.05), FOXO1 (P < 0.05), and S6K1 (P < 0.05) after an acute bout of high-intensity resistance exercise in older males. We conclude that ceramide may have a significant role in the attenuation of contractile-induced skeletal muscle adaptations and atrophy that is observed with aging.
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Affiliation(s)
- Donato A Rivas
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA
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BURKE LOUISEM, HAWLEY JOHNA, ROSS MEGANL, MOORE DANIELR, PHILLIPS STUARTM, SLATER GARYR, STELLINGWERFF TRENT, TIPTON KEVIND, GARNHAM ANDREWP, COFFEY VERNONG. Preexercise Aminoacidemia and Muscle Protein Synthesis after Resistance Exercise. Med Sci Sports Exerc 2012; 44:1968-77. [DOI: 10.1249/mss.0b013e31825d28fa] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Haran PH, Rivas DA, Fielding RA. Role and potential mechanisms of anabolic resistance in sarcopenia. J Cachexia Sarcopenia Muscle 2012; 3:157-62. [PMID: 22589021 PMCID: PMC3424190 DOI: 10.1007/s13539-012-0068-4] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 04/11/2012] [Indexed: 01/06/2023] Open
Abstract
There is pressing need to understand the aging process to better cope with its associated physical and societal costs. The age-related muscle wasting known as sarcopenia is a major contributor to the problems faced by the elderly. By hindering mobility and reducing strength, it greatly diminishes independence and quality of life. In studying the factors that contribute to the development of sarcopenia, the focus is shifting to the study of disordered muscle anabolism. The abnormal response of muscle to previously well-established anabolic stimuli is known as anabolic resistance, and may be a key factor in the development and progression of sarcopenia. Factors such as age, obesity, inflammation, and lipotoxicity contribute to anabolic resistance, and have been studied either directly or indirectly in cell systems and whole animals. Understanding the physiologic and mechanistic basis of anabolic resistance could be the key to formulating new and targeted interventions that would ease the burden currently borne by the world's aged population.
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Affiliation(s)
- Prashanth H Haran
- Nutrition, Exercise Physiology, and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA, 02111, USA
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Poortmans JR, Carpentier A, Pereira-Lancha LO, Lancha A. Protein turnover, amino acid requirements and recommendations for athletes and active populations. Braz J Med Biol Res 2012; 45:875-90. [PMID: 22666780 PMCID: PMC3854183 DOI: 10.1590/s0100-879x2012007500096] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/25/2012] [Indexed: 12/13/2022] Open
Abstract
Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine, 15N-glycine, 2H5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg−1·day−1 compared to 0.8 g·kg−1·day−1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.
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Affiliation(s)
- J R Poortmans
- Laboratory for Biometry and Sport Nutrition, Faculty of Motor Sciences, Free University of Brussels, Brussels, Belgium
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Watt MJ, Hoy AJ. Lipid metabolism in skeletal muscle: generation of adaptive and maladaptive intracellular signals for cellular function. Am J Physiol Endocrinol Metab 2012; 302:E1315-28. [PMID: 22185843 DOI: 10.1152/ajpendo.00561.2011] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Fatty acids derived from adipose tissue lipolysis, intramyocellular triacylglycerol lipolysis, or de novo lipogenesis serve a variety of functions in skeletal muscle. The two major fates of fatty acids are mitochondrial oxidation to provide energy for the myocyte and storage within a variety of lipids, where they are stored primarily in discrete lipid droplets or serve as important structural components of membranes. In this review, we provide a brief overview of skeletal muscle fatty acid metabolism and highlight recent notable advances in the field. We then 1) discuss how lipids are stored in and mobilized from various subcellular locations to provide adaptive or maladaptive signals in the myocyte and 2) outline how lipid metabolites or metabolic byproducts derived from the actions of triacylglycerol metabolism or β-oxidation act as positive and negative regulators of insulin action. We have placed an emphasis on recent developments in the lipid biology field with respect to understanding skeletal muscle physiology and discuss unanswered questions and technical limitations for assessing lipid signaling in skeletal muscle.
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Affiliation(s)
- Matthew J Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
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Abstract
The original definition of sarcopenia refers to the age-related loss of muscle mass. The literature suggests that the prevalence of sarcopenia in 60- to 70-year-olds is in the range of 5-13%. Prevalence estimates increase to 11-50% for the population aged 80 years or older. Estimates by the World Health Organization suggest that there were 600 million people aged 60 years or older in the year 2000, and that this number will increase to 1.2 billion by the year 2025. There are, however, limited published data on serial measures of muscle mass in older subjects to establish the age-related changes in muscle mass and to relate this change with adverse health consequences. This review is focused on the definition, prevalence, symptoms, pharmacy and physical therapy of sarcopenia in older subjects with the aim of promoting the recognition and treatment of age-related sarcopenia in the clinical setting.
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Affiliation(s)
- Cuiying Wang
- Medical Health Center of Beijing Friendship Hospital of Capital Medical University, Beijing, China
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Rivas DA, Morris EP, Fielding RA. Lipogenic regulators are elevated with age and chronic overload in rat skeletal muscle. Acta Physiol (Oxf) 2011; 202:691-701. [PMID: 21439027 DOI: 10.1111/j.1748-1716.2011.02289.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM Both muscle mass and strength decline with ageing, but the loss of strength far surpasses what is projected based on the decline in mass. Interestingly, the accumulation of fat mass has been shown to be a strong predictor of functional loss and disability. Furthermore, there is a known attenuated hypertrophic response to skeletal muscle overload with ageing. The purpose of this study was to determine the effect of 28 days of overload on the storage of intramuscular triglycerides (IMTG) and metabolic regulators of lipid synthesis in young and old skeletal muscle. METHODS The phosphorylation and expression of essential lipogenic regulators were determined in the plantaris of young (YNG; 6-month-old) and aged (OLD; 30-month-old) rats subjected to bilateral synergist ablation (SA) of two-thirds of the gastrocnemius muscle or sham surgery. RESULTS We demonstrate that age-induced increases in IMTG are associated with enhancements in the expression of lipogenic regulators in muscle. We also show that the phosphorylation and concentration of the 5'AMP-activated protein kinase (AMPK) isoforms are altered in OLD. We observed increases in the expression of lipogenic regulators and AMPK signalling after SA in YNG, despite no increase in IMTG. Markers of oxidative capacity were increased in YNG after SA. These overload-induced effects were blunted in OLD. CONCLUSION These data suggest that lipid metabolism may be altered in ageing skeletal muscle and is unaffected by mechanical overload via SA. By determining the role of increased lipid storage on skeletal muscle mass during ageing, possible gene targets for the treatment of sarcopenia may be identified.
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Affiliation(s)
- D A Rivas
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA
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Pillard F, Laoudj-Chenivesse D, Carnac G, Mercier J, Rami J, Rivière D, Rolland Y. Physical activity and sarcopenia. Clin Geriatr Med 2011; 27:449-70. [PMID: 21824557 DOI: 10.1016/j.cger.2011.03.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Physical activity can be a valuable countermeasure to sarcopenia in its treatment and prevention. In considering physical training strategies for sarcopenic subjects, it is critical to consider personal and environmental obstacles to access opportunities for physical activity for any patient with chronic disease. This article presents an overview of current knowledge of the effects of physical training on muscle function and the physical activity recommended for sarcopenic patients. So that this countermeasure strategy can be applied in practice, the authors propose a standardized protocol for prescribing physical activity in chronic diseases such as sarcopenia.
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Affiliation(s)
- Fabien Pillard
- Respiratory Exploration Department and Sports Medicine Department, Larrey University Hospital, Toulouse CEDEX, France.
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Free acid gel form of β-hydroxy-β-methylbutyrate (HMB) improves HMB clearance from plasma in human subjects compared with the calcium HMB salt. Br J Nutr 2010; 105:367-72. [DOI: 10.1017/s0007114510003582] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The leucine metabolite, β-hydroxy-β-methylbutyrate (HMB), is a nutritional supplement that increases lean muscle and strength with exercise and in disease states. HMB is presently available as the Ca salt (CaHMB). The present study was designed to examine whether HMB in free acid gel form will improve HMB availability to tissues. Two studies were conducted and in each study four males and four females were given three treatments in a randomised, cross-over design. Treatments were CaHMB (gelatin capsule, 1 g), equivalent HMB free acid gel swallowed (FASW) and free acid gel held sublingual for 15 s then swallowed (FASL). Plasma HMB was measured for 3 h following treatment in study 1 and 24 h with urine collection in study 2. In both the studies, the times to peak plasma HMB were 128 (sem 11), 38 (sem 4) and 38 (sem 1) min (P < 0·0001) for CaHMB, FASW and FASL, respectively. The peak concentrations were 131 (sem 6), 249 (sem 14) and 239 (sem 14) μmol/l (P < 0·0001) for CaHMB, FASW and FASL, respectively. The areas under the curve were almost double for FASW and FASL (P < 0·0001). Daily urinary HMB excretion was not significantly increased resulting in more HMB retained (P < 0·003) with FASW and FASL. Half-lives were 3·17 (sem 0·22), 2·50 (sem 0·13) and 2·51 (sem 0·14) h for CaHMB, FASW and FASL, respectively (P < 0·004). Free acid gel resulted in quicker and greater plasma concentrations (+185 %) and improved clearance (+25 %) of HMB from plasma. In conclusion, HMB free acid gel could improve HMB availability and efficacy to tissues in health and disease.
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