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Liang X, Zhang H, Shang W, Wang M, Li J, Zhao Y, Fang C. PPP2CA Inhibition Promotes Ferroptosis Sensitivity Through AMPK/SCD1 Pathway in Colorectal Cancer. Dig Dis Sci 2024; 69:2083-2095. [PMID: 38637456 DOI: 10.1007/s10620-024-08416-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/28/2024] [Indexed: 04/20/2024]
Abstract
PURPOSE Colorectal cancer (CRC) is a very common malignancy of the digestive system. Despite a variety of treatments including surgery, chemotherapeutic and targeted drugs, the prognosis for patients with CRC is still unsatisfactory and the mortality remains high. Protein phosphorylation plays an essential role in tumorigenesis and progression and is also crucial for protein to act with proper functions. Ferroptosis is found widely involved in various diseases especially tumors as a newly identified programmed cell death. METHODS In our study, we aimed at PPP2CA as a prospective target which may play a crucial role in CRC progression. In one hand, knockdown of PPP2CA significantly enhanced the malignant phenotype in HCT116. In the other hand, knockdown of PPP2CA significantly enhanced Erastin-induced ferroptosis as well. RESULTS Specifically, knockdown of PPP2CA in HCT116 significantly increased the relative level of malondialdehyde (MDA), reactive oxygen species (ROS) and Fe2+, and decreased GSH/GSSG ratio after the treatment of certain concentration of Erastin. Besides, we found that the inhibition of PPP2CA further led to the suppression of SCD1 expression in CRC cells in a AMPK-dependent way. CONCLUSION Ultimately, we conclude that PPP2CA may regulate Erastin-induced ferroptosis through AMPK/SCD1 signaling pathway.
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Affiliation(s)
- Xiaojie Liang
- Department of General Surgery, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China
| | - Hui Zhang
- Department of General Surgery, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China
| | - Weiwei Shang
- Department of General Surgery, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China
| | - Mingming Wang
- Department of General Surgery, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China
| | - Jun Li
- Department of General Surgery, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China
| | - Yunzhao Zhao
- Department of General Surgery, The Affiliated Jinling Hospital of Nanjing Medical University, 305 East Zhongshan Road, Nanjing, 210002, China
| | - Chao Fang
- Central Laboratory, The Affiliated Jiangning Hospital of Nanjing Medical University, 169 Hushan Road, Nanjing, 211100, China.
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Kjøbsted R, Birk JB, Eskesen NO, Wojtaszewski JFP. Energy sensor AMPKγ does not exist in isolation from AMPKα or interact with PPP6C in muscle and liver from humans and mice. Mol Cell 2024; 84:1627-1628. [PMID: 38701736 DOI: 10.1016/j.molcel.2024.02.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 02/16/2024] [Accepted: 02/21/2024] [Indexed: 05/05/2024]
Affiliation(s)
- Rasmus Kjøbsted
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark.
| | - Jesper Bratz Birk
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Nicolas Oldenburg Eskesen
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jørgen Frank Pind Wojtaszewski
- August Krogh Section for Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark.
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Zhou Q, Cao X, Zhao B. Response to: Energy sensor AMPKγ does not exist in isolation from AMPKα or interact with PPP6C in muscle and liver from humans and mice. Mol Cell 2024; 84:1629-1630. [PMID: 38701737 DOI: 10.1016/j.molcel.2024.02.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 02/05/2024] [Accepted: 02/21/2024] [Indexed: 05/05/2024]
Affiliation(s)
- Qi Zhou
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Cancer Center, Zhejiang University, Hangzhou 310058, China
| | - Xiaolei Cao
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Cancer Center, Zhejiang University, Hangzhou 310058, China
| | - Bin Zhao
- MOE Key Laboratory of Biosystems Homeostasis & Protection, Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China; Cancer Center, Zhejiang University, Hangzhou 310058, China; Department of Hepatobiliary and Pancreatic Surgery, Zhejiang Provincial Key Laboratory of Pancreatic Disease, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China; Center for Life Sciences, Shaoxing Institute, Zhejiang University, Shaoxing 321000, China.
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Pang X, Zhang P, Chen X, Liu W. Ubiquitin-proteasome pathway in skeletal muscle atrophy. Front Physiol 2023; 14:1289537. [PMID: 38046952 PMCID: PMC10690626 DOI: 10.3389/fphys.2023.1289537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/06/2023] [Indexed: 12/05/2023] Open
Abstract
Skeletal muscles underpin myriad human activities, maintaining an intricate balance between protein synthesis and degradation crucial to muscle mass preservation. Historically, disruptions in this balance-where degradation overshadows synthesis-have marked the onset of muscle atrophy, a condition diminishing life quality and, in grave instances, imperiling life itself. While multiple protein degradation pathways exist-including the autophagy-lysosome, calcium-dependent calpain, and cysteine aspartate protease systems-the ubiquitin-proteasome pathway emerges as an especially cardinal avenue for intracellular protein degradation, wielding pronounced influence over the muscle atrophy trajectory. This paper ventures a panoramic view of predominant muscle atrophy types, accentuating the ubiquitin-proteasome pathway's role therein. Furthermore, by drawing from recent scholarly advancements, we draw associations between the ubiquitin-proteasome pathway and specific pathological conditions linked to muscle atrophy. Our exploration seeks to shed light on the ubiquitin-proteasome pathway's significance in skeletal muscle dynamics, aiming to pave the way for innovative therapeutic strategies against muscle atrophy and affiliated muscle disorders.
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Affiliation(s)
- XiangSheng Pang
- Department of Physical Education, College of Education, Zhejiang University, Hangzhou, Zhejiang, China
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing, China
| | - Peng Zhang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - XiaoPing Chen
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing, China
| | - WenMing Liu
- Department of Physical Education, College of Education, Zhejiang University, Hangzhou, Zhejiang, China
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Piserchio A, Long K, Browning L, Bohanon A, Isiorho E, Dalby K, Ghose R. ADP enhances the allosteric activation of eukaryotic elongation factor 2 kinase by calmodulin. Proc Natl Acad Sci U S A 2023; 120:e2300902120. [PMID: 37068230 PMCID: PMC10151598 DOI: 10.1073/pnas.2300902120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/06/2023] [Indexed: 04/19/2023] Open
Abstract
Protein translation, one of the most energy-consumptive processes in a eukaryotic cell, requires robust regulation, especially under energy-deprived conditions. A critical component of this regulation is the suppression of translational elongation through reduced ribosome association of the GTPase eukaryotic elongation factor 2 (eEF-2) resulting from its specific phosphorylation by the calmodulin (CaM)-activated α-kinase eEF-2 kinase (eEF-2K). It has been suggested that the eEF-2K response to reduced cellular energy levels is indirect and mediated by the universal energy sensor AMP-activated protein kinase (AMPK) through direct stimulatory phosphorylation and/or downregulation of the eEF-2K-inhibitory nutrient-sensing mTOR pathway. Here, we provide structural, biochemical, and cell-biological evidence of a direct energy-sensing role of eEF-2K through its stimulation by ADP. A crystal structure of the nucleotide-bound complex between CaM and the functional core of eEF-2K phosphorylated at its primary stimulatory site (T348) reveals ADP bound at a unique pocket located on the face opposite that housing the kinase active site. Within this basic pocket (BP), created at the CaM/eEF-2K interface upon complex formation, ADP is stabilized through numerous interactions with both interacting partners. Biochemical analyses using wild-type eEF-2K and specific BP mutants indicate that ADP stabilizes CaM within the active complex, increasing the sensitivity of the kinase to CaM. Induction of energy stress through glycolysis inhibition results in significantly reduced enhancement of phosphorylated eEF-2 levels in cells expressing ADP-binding compromised BP mutants compared to cells expressing wild-type eEF-2K. These results suggest a direct energy-sensing role for eEF-2K through its cooperative interaction with CaM and ADP.
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Affiliation(s)
- Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY10031
| | - Kimberly J. Long
- Division of Chemical Biology and Medicinal Chemistry, the University of Texas, Austin, TX78712
| | - Luke S. Browning
- Interdisciplinary Life Sciences Graduate Program, the University of Texas, Austin, TX78712
| | - Amanda L. Bohanon
- Interdisciplinary Life Sciences Graduate Program, the University of Texas, Austin, TX78712
| | - Eta A. Isiorho
- Macromolecular Crystallization Facility CUNY Advanced Science Research Center, New York, NY10031
| | - Kevin N. Dalby
- Division of Chemical Biology and Medicinal Chemistry, the University of Texas, Austin, TX78712
- Interdisciplinary Life Sciences Graduate Program, the University of Texas, Austin, TX78712
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY10031
- PhD Program in Biochemistry, The Graduate Center of CUNY, New York, NY10016
- PhD Program in Chemistry, The Graduate Center of CUNY, New York, NY10016
- PhD Program in Physics, The Graduate Center of CUNY, New York, NY10016
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Chen J, Wang J, Wu X, Simon N, Svensson CI, Yuan J, Hart DA, Ahmed AS, Ackermann PW. eEF2 improves dense connective tissue repair and healing outcome by regulating cellular death, autophagy, apoptosis, proliferation and migration. Cell Mol Life Sci 2023; 80:128. [PMID: 37084140 PMCID: PMC10121543 DOI: 10.1007/s00018-023-04776-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/23/2023] [Accepted: 04/09/2023] [Indexed: 04/22/2023]
Abstract
Outcomes following human dense connective tissue (DCT) repair are often variable and suboptimal, resulting in compromised function and development of chronic painful degenerative diseases. Moreover, biomarkers and mechanisms that guide good clinical outcomes after DCT injuries are mostly unknown. Here, we characterize the proteomic landscape of DCT repair following human Achilles tendon rupture and its association with long-term patient-reported outcomes. Moreover, the potential regulatory mechanisms of relevant biomarkers were assessed partly by gene silencing experiments. A mass-spectrometry based proteomic approach quantified a large number (769) of proteins, including 51 differentially expressed proteins among 20 good versus 20 poor outcome patients. A novel biomarker, elongation factor-2 (eEF2) was identified as being strongly prognostic of the 1-year clinical outcome. Further bioinformatic and experimental investigation revealed that eEF2 positively regulated autophagy, cell proliferation and migration, as well as reduced cell death and apoptosis, leading to improved DCT repair and outcomes. Findings of eEF2 as novel prognostic biomarker could pave the way for new targeted treatments to improve healing outcomes after DCT injuries.Trial registration: NCT02318472 registered 17 December 2014 and NCT01317160 registered 17 March 2011, with URL http://clinicaltrials.gov/ct2/show/NCT02318472 and http://clinicaltrials.gov/ct2/show/study/NCT01317160 .
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Affiliation(s)
- Junyu Chen
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden.
| | - Jin Wang
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, 710061, People's Republic of China
- The Key Laboratory of Tumor Molecular Diagnosis and Individualized Medicine of Zhejiang Province, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, 310014, China
| | - Xinjie Wu
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
- Peking University China-Japan Friendship School of Clinical Medicine, Beijing, 100029, China
| | - Nils Simon
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Camilla I Svensson
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Juan Yuan
- Department of Cell and Molecular Biology, Karolinska Institutet, 17176, Stockholm, Sweden
| | - David A Hart
- Department of Surgery, Faculty of Kinesiology, McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Aisha S Ahmed
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden.
- Department of Physiology, University of Helsinki, Helsinki, Finland.
| | - Paul W Ackermann
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
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Vilchinskaya N, Lim WF, Belova S, Roberts TC, Wood MJA, Lomonosova Y. Investigating Eukaryotic Elongation Factor 2 Kinase/Eukaryotic Translation Elongation Factor 2 Pathway Regulation and Its Role in Protein Synthesis Impairment during Disuse-Induced Skeletal Muscle Atrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2023:S0002-9440(23)00060-3. [PMID: 36871751 DOI: 10.1016/j.ajpath.2023.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 01/16/2023] [Accepted: 02/10/2023] [Indexed: 03/07/2023]
Abstract
The principal mechanism underlying the reduced rate of protein synthesis in atrophied skeletal muscle is largely unknown. Eukaryotic elongation factor 2 kinase (eEF2k) impairs the ability of eukaryotic translation elongation factor 2 (eEF2) to bind to the ribosome via T56 phosphorylation. Perturbations in the eEF2k/eEF2 pathway during various stages of disuse muscle atrophy have been investigated utilizing a rat hind limb suspension (HS) model. Two distinct components of eEF2k/eEF2 pathway misregulation were demonstrated, observing a significant (P < 0.01) increase in eEF2k mRNA expression as early as 1-day HS and in eEF2k protein level after 3-day HS. We set out to determine whether eEF2k activation is a Ca2+-dependent process with involvement of Cav1.1. The ratio of T56-phosphorylated/total eEF2 was robustly elevated after 3-day HS, which was completely reversed by BAPTA-AM and decreased by 1.7-fold (P < 0.05) by nifedipine. Transfection of C2C12 with pCMV-eEF2k and administration with small molecules were used to modulate eEF2k and eEF2 activity. More important, pharmacologic enhancement of eEF2 phosphorylation induced phosphorylated ribosomal protein S6 kinase (T389) up-regulation and restoration of global protein synthesis in the HS rats. Taken together, the eEF2k/eEF2 pathway is up-regulated during disuse muscle atrophy involving calcium-dependent activation of eEF2k partly via Cav1.1. The study provides evidence, in vitro and in vivo, of the eEF2k/eEF2 pathway impact on ribosomal protein S6 kinase activity as well as protein expression of key atrophy biomarkers, muscle atrophy F-box/atrogin-1 and muscle RING finger-1.
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Affiliation(s)
| | - Wooi Fang Lim
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | | | - Thomas C Roberts
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Matthew J A Wood
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Yulia Lomonosova
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom.
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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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Vilchinskaya N, Altaeva E, Lomonosova Y. Gaining insight into the role of FoxO1 in the progression of disuse-induced skeletal muscle atrophy. Adv Biol Regul 2022; 85:100903. [PMID: 35947892 DOI: 10.1016/j.jbior.2022.100903] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/21/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Expression of FoxO transcription factors increases during certain forms of atrophy. In a dephosphorylated state, FoxOs participate in ubiquitin-mediated proteasomal degradation through the transcriptional activation of E3-ubiquitin ligases such as MAFbx/atrogin-1 and MuRF1. There is exhaustive research demonstrating that FoxO3a is sufficient to induce MAFbx/atrogin-1 and MuRF-1 expressions. In contrast, the data are conflicting on the requirement of FoxO1 signaling in the activation of the E3-ubiquitin ligases. Moreover, no reports currently exist on the particular role of FoxO1 in the molecular mechanisms involved in the progression of physiological muscle wasting. Here, we have applied the most extensively used rodent model of microgravity/functional unloading to stimulate disuse-induced skeletal muscle atrophy such as rat hindlimb suspension (HS). We showed that inhibition of FoxO1 activity by a selective inhibitor AS1842856 completely reversed an increase in expression of MuRF-1, but not MAFbx/atrogin-1, observed upon HS. Furthermore, we demonstrated that FoxO1 induced upregulation of another E3-ubiquitin-ligase of a MuRF protein family MuRF-2 in skeletal muscle subjected to disuse. Prevention of the MuRF increase upon HS impeded upregulation of transcript expression of a negative regulator of NFATc1 pathway calsarcin-2, which was associated with a partial reversion of MyHC-IId/x and MyHC-IIb mRNA expressions. Importantly, FoxO1 inhibition induced a marked increase in p70S6k phosphorylation, an important stage in the initiation of protein translation, concomitant with the restoration of global protein synthesis in the skeletal muscle of the HS rats. Examination of eIF3f expression and the eEF2k/eEF2 pathway, other factors controlling translation initiation and elongation respectively, did not reveal any impact of FoxO1 on their activity. Lastly, we observed a decrease in transcript levels of Sesn3, but not Sesn1 and Sesn2, upon disuse, which was completely reversed by FoxO1 inhibition. These data demonstrate that FoxO1 signaling contributes to the development of disuse-induced skeletal muscle atrophy, including slow to fast MyHC isoform shift, mostly through upregulation of MuRF-1 and MuRF-2 expression. Furthermore, FoxO1 inhibition is required to recover Sesn3 mRNA expression in atrophic conditions, which likely contributes to the enhanced p70S6k activity and restoration of the protein synthesis rate.
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Affiliation(s)
- Natalia Vilchinskaya
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, 76a, Khoroshevskoe Shosse, Moscow, 123007, Russia.
| | - Erzhena Altaeva
- Myology Laboratory, Institute of Biomedical Problems, Russian Academy of Sciences, 76a, Khoroshevskoe Shosse, Moscow, 123007, Russia.
| | - Yulia Lomonosova
- Department of Paediatrics, University of Oxford, Children's Hospital, John Radcliffe, Oxford, OX3 9DU, UK; Institute of Developmental and Regenerative Medicine, Roosevelt Dr, IMS-Tetsuya Nakamura Building, Oxford, OX3 7TY, UK; MDUK Oxford Neuromuscular Centre, University of Oxford, South Parks Road, Oxford, OX1 3QX, UK.
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Jakobsgaard JE, de Paoli F, Vissing K. Protein signaling in response to ex vivo dynamic contractions is independent of training status in rat skeletal muscle. Exp Physiol 2022; 107:919-932. [PMID: 35723680 PMCID: PMC9545705 DOI: 10.1113/ep090446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 06/16/2022] [Indexed: 11/24/2022]
Abstract
New Findings What is the central question of this study? Are myofibre protein signalling responses to ex vivo dynamic contractions altered by accustomization to voluntary endurance training in rats? What is the main finding and its importance? In response to ex vivo dynamic muscle contractions, canonical myofibre protein signalling pertaining to metabolic transcriptional regulation, as well as translation initiation and elongation, was not influenced by prior accustomization to voluntary endurance training in rats. Accordingly, intrinsic myofibre protein signalling responses to standardized contractile activity may be independent of prior exercise training in rat skeletal muscle.
Abstract Skeletal muscle training status may influence myofibre regulatory protein signalling in response to contractile activity. The current study employed a purpose‐designed ex vivo dynamic contractile protocol to evaluate the effect of exercise‐accustomization on canonical myofibre protein signalling for metabolic gene expression and for translation initiation and elongation. To this end, rats completed 8 weeks of in vivo voluntary running training versus no running control intervention, whereupon an ex vivo endurance‐type dynamic contraction stimulus was conducted in isolated soleus muscle preparations from both intervention groups. Protein signalling response by phosphorylation was evaluated by immunoblotting at 0 and 3 h following ex vivo stimulation. Phosphorylation of AMP‐activated protein kinase α‐isoforms and its downstream target, acetyl‐CoA carboxylase, as well as phosphorylation of eukaryotic elongation factor 2 (eEF2) was increased immediately following the dynamic contraction protocol (at 0 h). Signalling for translation initiation and elongation was evident at 3 h after dynamic contractile activity, as evidenced by increased phosphorylation of p70 S6 kinase and eukaryotic translation initiation factor 4E‐binding protein 1, as well as a decrease in phosphorylation of eEF2 back to resting control levels. However, prior exercise training did not alter phosphorylation responses of the investigated signalling proteins. Accordingly, protein signalling responses to standardized endurance‐type contractions may be independent of training status in rat muscle during ex vivo conditions. The present findings add to our current understanding of molecular regulatory events responsible for skeletal muscle plasticity.
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Affiliation(s)
- Jesper Emil Jakobsgaard
- Exercise Biology, Department of Public Health, Faculty of Health, Aarhus University, Denmark
| | - Frank de Paoli
- Department of Biomedicine, Faculty of Health, Aarhus University, Denmark
| | - Kristian Vissing
- Exercise Biology, Department of Public Health, Faculty of Health, Aarhus University, Denmark
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Gao M, Deng C, Dang F. Synergistic antitumor effect of resveratrol and sorafenib on hepatocellular carcinoma through PKA/AMPK/eEF2K pathway. Food Nutr Res 2021; 65:3602. [PMID: 34776832 PMCID: PMC8559449 DOI: 10.29219/fnr.v65.3602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 03/31/2021] [Indexed: 11/24/2022] Open
Abstract
Although sorafenib (Sor) is the only effective drug for hepatocellular carcinoma (HCC), its therapeutic potential to date is mainly limited to the low tumor response. This study was designed to explore whether resveratrol (Res) could potentiate the anticancerous activity of Sor. We used HepG2 and Huh7 HCC cell lines and BALB/c nude mice for in vitro and in vivo studies, respectively. The cultured cell lines and tumor induction in the mice were treated with different concentrations of Res and Sor alone, and the combination of Res and Sor to observe the antitumor effects. Significant inhibitory effects were observed in the combined treatment of Res and Sor compared to Res and Sor alone treatments both in vitro and in vivo as demonstrated by significantly high number of S phase cells and apoptotic cells. Moreover, these findings were accompanied by the reduction of CDK2, CDC25A, PKA, p-AMPK, and eEF2K protein levels and the increment of cyclin A, cleavage caspase-3, caspase-8, and caspase-9 protein levels. The combinational treatment exhibited more significant anticancerous effect than the Res and Sor alone treatments in mice-bearing HepG2 xenograft. Overall, our results suggest that PKA/AMPK/eEF2K pathway is involved in the synergistic anticancerous activity of Res and Sor combination treatment in HCC cells. Thus, Res and Sor combination therapy may be promising in increasing the tumor response of Sor in the future.
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Affiliation(s)
- Meili Gao
- Department of Biological Science and Engineering, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Chun Deng
- Department of Biological Science and Engineering, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Fan Dang
- Department of Biological Science and Engineering, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
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Ballard DJ, Peng HY, Das JK, Kumar A, Wang L, Ren Y, Xiong X, Ren X, Yang JM, Song J. Insights Into the Pathologic Roles and Regulation of Eukaryotic Elongation Factor-2 Kinase. Front Mol Biosci 2021; 8:727863. [PMID: 34532346 PMCID: PMC8438118 DOI: 10.3389/fmolb.2021.727863] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 08/16/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic Elongation Factor-2 Kinase (eEF2K) acts as a negative regulator of protein synthesis, translation, and cell growth. As a structurally unique member of the alpha-kinase family, eEF2K is essential to cell survival under stressful conditions, as it contributes to both cell viability and proliferation. Known as the modulator of the global rate of protein translation, eEF2K inhibits eEF2 (eukaryotic Elongation Factor 2) and decreases translation elongation when active. eEF2K is regulated by various mechanisms, including phosphorylation through residues and autophosphorylation. Specifically, this protein kinase is downregulated through the phosphorylation of multiple sites via mTOR signaling and upregulated via the AMPK pathway. eEF2K plays important roles in numerous biological systems, including neurology, cardiology, myology, and immunology. This review provides further insights into the current roles of eEF2K and its potential to be explored as a therapeutic target for drug development.
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Affiliation(s)
- Darby J. Ballard
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Hao-Yun Peng
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Jugal Kishore Das
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Anil Kumar
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Liqing Wang
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Yijie Ren
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xiaofang Xiong
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xingcong Ren
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jin-Ming Yang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jianxun Song
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
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13
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Okun JG, Rusu PM, Chan AY, Wu Y, Yap YW, Sharkie T, Schumacher J, Schmidt KV, Roberts-Thomson KM, Russell RD, Zota A, Hille S, Jungmann A, Maggi L, Lee Y, Blüher M, Herzig S, Keske MA, Heikenwalder M, Müller OJ, Rose AJ. Liver alanine catabolism promotes skeletal muscle atrophy and hyperglycaemia in type 2 diabetes. Nat Metab 2021; 3:394-409. [PMID: 33758419 DOI: 10.1038/s42255-021-00369-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 02/18/2021] [Indexed: 01/31/2023]
Abstract
Both obesity and sarcopenia are frequently associated in ageing, and together may promote the progression of related conditions such as diabetes and frailty. However, little is known about the pathophysiological mechanisms underpinning this association. Here we show that systemic alanine metabolism is linked to glycaemic control. We find that expression of alanine aminotransferases is increased in the liver in mice with obesity and diabetes, as well as in humans with type 2 diabetes. Hepatocyte-selective silencing of both alanine aminotransferase enzymes in mice with obesity and diabetes retards hyperglycaemia and reverses skeletal muscle atrophy through restoration of skeletal muscle protein synthesis. Mechanistically, liver alanine catabolism driven by chronic glucocorticoid and glucagon signalling promotes hyperglycaemia and skeletal muscle wasting. We further provide evidence for amino acid-induced metabolic cross-talk between the liver and skeletal muscle in ex vivo experiments. Taken together, we reveal a metabolic inter-tissue cross-talk that links skeletal muscle atrophy and hyperglycaemia in type 2 diabetes.
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Affiliation(s)
- Jürgen G Okun
- Division of Inherited Metabolic Diseases, University Children's Hospital, Heidelberg, Germany
| | - Patricia M Rusu
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Andrea Y Chan
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Yuqin Wu
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Yann W Yap
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Thomas Sharkie
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Jonas Schumacher
- Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Kathrin V Schmidt
- Division of Inherited Metabolic Diseases, University Children's Hospital, Heidelberg, Germany
| | - Katherine M Roberts-Thomson
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Ryan D Russell
- Department of Health and Human Performance, College of Health Professions, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Annika Zota
- Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine I, Heidelberg University Hospital and Chair Molecular Metabolic Control, Technical University Munich, Neuherberg, Germany
| | - Susanne Hille
- Department of Internal Medicine III, University of Kiel, Kiel, Germany
- German Center for Cardiovascular Research (DZHK), Heidelberg and Kiel sites, Germany
| | - Andreas Jungmann
- German Center for Cardiovascular Research (DZHK), Heidelberg and Kiel sites, Germany
- Department of Internal Medicine III, University Hospital Heidelberg, Heidelberg, Germany
| | - Ludovico Maggi
- Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Young Lee
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig, Leipzig, Germany
| | - Stephan Herzig
- Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich, Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine I, Heidelberg University Hospital and Chair Molecular Metabolic Control, Technical University Munich, Neuherberg, Germany
| | - Michelle A Keske
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia
| | - Mathias Heikenwalder
- Division of Chronic Inflammation and Cancer, German Cancer Research Center, Heidelberg, Germany
| | - Oliver J Müller
- Department of Internal Medicine III, University of Kiel, Kiel, Germany
- German Center for Cardiovascular Research (DZHK), Heidelberg and Kiel sites, Germany
| | - Adam J Rose
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.
- Division of Molecular Metabolic Control, German Cancer Research Center (DKFZ), Heidelberg, Germany.
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14
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Yu Q, Dai CL, Zhang Y, Chen Y, Wu Z, Iqbal K, Liu F, Gong CX. Intranasal Insulin Increases Synaptic Protein Expression and Prevents Anesthesia-Induced Cognitive Deficits Through mTOR-eEF2 Pathway. J Alzheimers Dis 2020; 70:925-936. [PMID: 31306126 DOI: 10.3233/jad-190280] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
General anesthesia increases the risk for cognitive impairment and Alzheimer's disease (AD) in vulnerable individuals such as the elderly. We previously reported that prior administration of insulin through intranasal delivery can prevent the anesthesia-induced cognitive impairment and biochemical changes in the brain. However, little is known about the underlying molecular mechanisms. Here, we report that general anesthesia resulted in downregulation of mammalian/mechanistic target of rapamycin (mTOR) and eukaryotic elongation factor 2 (eEF2) in the brain along with reduction of presynaptic proteins and brain-derived neurotrophic factor and cognitive impairment in aged mice. Prior administration of intranasal insulin prevented these anesthesia-induced changes. These results suggest the involvement of the mTOR-eEF2 signaling pathway in the anesthesia-induced brain changes and cognitive impairment and in the prevention of these changes with insulin. Correlation analyses and the use of eEF2 kinase inhibitor further support our conclusions. These studies shed light on the molecular mechanism by which anesthesia and insulin could act on synaptic proteins and cognitive function.
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Affiliation(s)
- Qian Yu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.,Department of Orthopedics, Qianfoshan Hospital, Shandong University, Jinan, China
| | - Chun-Ling Dai
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Yongli Zhang
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Yanxing Chen
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.,Department of Neurology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhe Wu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.,Department of Cell Biology and Genetics, School of Basic Medical College, Hubei University of Science and Technology, Xianning, Hubei, China
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Fei Liu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
| | - Cheng-Xin Gong
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
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15
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Shenkman BS. How Postural Muscle Senses Disuse? Early Signs and Signals. Int J Mol Sci 2020; 21:E5037. [PMID: 32708817 PMCID: PMC7404025 DOI: 10.3390/ijms21145037] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/11/2022] Open
Abstract
A mammalian soleus muscle along with other "axial" muscles ensures the stability of the body under the Earth's gravity. In rat experiments with hindlimb suspension, zero-gravity parabolic flights as well as in human dry immersion studies, a dramatic decrease in the electromyographic (EMG) activity of the soleus muscle has been repeatedly shown. Most of the motor units of the soleus muscle convert from a state of activity to a state of rest which is longer than under natural conditions. And the state of rest gradually converts to the state of disuse. This review addresses a number of metabolic events that characterize the earliest stage of the cessation of the soleus muscle contractile activity. One to three days of mechanical unloading are accompanied by energy-dependent dephosphorylation of AMPK, accumulation of the reactive oxygen species, as well as accumulation of resting myoplasmic calcium. In this transition period, a rapid rearrangement of the various signaling pathways occurs, which, primarily, results in a decrease in the rate of protein synthesis (primarily via inhibition of ribosomal biogenesis and activation of endogenous inhibitors of mRNA translation, such as GSK3β) and an increase in proteolysis (via upregulation of muscle-specific E3-ubiquitin ligases).
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Affiliation(s)
- Boris S Shenkman
- Myology Laboratory, Institute of Biomedical Problems RAS, 123007 Moscow, Russia
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16
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Nugent FJ, Flanagan EP, Wilson F, Warrington GD. Strength and Conditioning for Competitive Rowers. Strength Cond J 2020. [DOI: 10.1519/ssc.0000000000000531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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17
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Merle A, Jollet M, Britto FA, Goustard B, Bendridi N, Rieusset J, Ollendorff V, Favier FB. Endurance exercise decreases protein synthesis and ER-mitochondria contacts in mouse skeletal muscle. J Appl Physiol (1985) 2019; 127:1297-1306. [PMID: 31487224 DOI: 10.1152/japplphysiol.00196.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Exercise is important to maintain skeletal muscle mass through stimulation of protein synthesis, which is a major ATP-consuming process for cells. However, muscle cells have to face high energy demand during contraction. The present study aimed to investigate protein synthesis regulation during aerobic exercise in mouse hindlimb muscles. Male C57Bl/6J mice ran at 12 m/min for 45 min or at 12 m/min for the first 25 min followed by a progressive increase in velocity up to 20 m/min for the last 20 min. Animals were injected intraperitoneally with 40 nmol/g of body weight of puromycin and euthanized by cervical dislocation immediately after exercise cessation. Analysis of gastrocnemius, plantaris, quadriceps, soleus, and tibialis anterior muscles revealed a decrease in protein translation assessed by puromycin incorporation, without significant differences among muscles or running intensities. The reduction of protein synthesis was associated with a marked inhibition of mammalian target of rapamycin complex 1 (mTORC1)-dependent phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1, a mechanism consistent with reduced translation initiation. A slight activation of AMP-activated protein kinase consecutive to the running session was measured but did not correlate with mTORC1 inhibition. More importantly, exercise resulted in a strong upregulation of regulated in development and DNA damage 1 (REDD1) protein and gene expressions, whereas transcriptional regulation of other recognized exercise-induced genes (IL-6, kruppel-like factor 15, and regulator of calcineurin 1) did not change. Consistently with the recently discovered role of REDD1 on mitochondria-associated membranes, we observed a decrease in mitochondria-endoplasmic reticulum interaction following exercise. Collectively, these data raise questions concerning the role of mitochondria-associated endoplasmic reticulum membrane disruption in the regulation of muscle proteostasis during exercise and, more generally, in cell adaptation to metabolic stress.NEW & NOTEWORTHY How muscles regulate protein synthesis to cope with the energy demand during contraction is poorly documented. Moreover, it is unknown whether protein translation is differentially affected among mouse hindlimb muscles under different physiological exercise modalities. We showed here that 45 min of running decreases puromycin incorporation similarly in 5 different mouse muscles. This decrease was associated with a strong increase in regulated in development and DNA damage 1 protein expression and a significant disruption of the mitochondria and sarcoplasmic reticulum interaction.
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Affiliation(s)
- Audrey Merle
- DMEM, University of Montpellier, INRA, Montpellier, France
| | - Maxence Jollet
- DMEM, University of Montpellier, INRA, Montpellier, France
| | | | | | - Nadia Bendridi
- INSERM CarMeN Laboratory, Lyon 1 University, INRA U1397, Oullins, France
| | - Jennifer Rieusset
- INSERM CarMeN Laboratory, Lyon 1 University, INRA U1397, Oullins, France
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18
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Hodson N, West DWD, Philp A, Burd NA, Moore DR. Molecular regulation of human skeletal muscle protein synthesis in response to exercise and nutrients: a compass for overcoming age-related anabolic resistance. Am J Physiol Cell Physiol 2019; 317:C1061-C1078. [PMID: 31461340 DOI: 10.1152/ajpcell.00209.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle mass, a strong predictor of longevity and health in humans, is determined by the balance of two cellular processes, muscle protein synthesis (MPS) and muscle protein breakdown. MPS seems to be particularly sensitive to changes in mechanical load and/or nutritional status; therefore, much research has focused on understanding the molecular mechanisms that underpin this cellular process. Furthermore, older individuals display an attenuated MPS response to anabolic stimuli, termed anabolic resistance, which has a negative impact on muscle mass and function, as well as quality of life. Therefore, an understanding of which, if any, molecular mechanisms contribute to anabolic resistance of MPS is of vital importance in formulation of therapeutic interventions for such populations. This review summarizes the current knowledge of the mechanisms that underpin MPS, which are broadly divided into mechanistic target of rapamycin complex 1 (mTORC1)-dependent, mTORC1-independent, and ribosomal biogenesis-related, and describes the evidence that shows how they are regulated by anabolic stimuli (exercise and/or nutrition) in healthy human skeletal muscle. This review also summarizes evidence regarding which of these mechanisms may be implicated in age-related skeletal muscle anabolic resistance and provides recommendations for future avenues of research that can expand our knowledge of this area.
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Affiliation(s)
- Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Daniel W D West
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Philp
- Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - Nicholas A Burd
- Department of Kinesiology and Community Health, University of Illinois, Urbana, Illinois
| | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
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19
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The Effects of Wheel Running on Skeletal Muscle Function During and Following Doxorubicin Treatment. REHABILITATION ONCOLOGY 2019. [DOI: 10.1097/01.reo.0000000000000146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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The Role of AMPK in the Regulation of Skeletal Muscle Size, Hypertrophy, and Regeneration. Int J Mol Sci 2018; 19:ijms19103125. [PMID: 30314396 PMCID: PMC6212977 DOI: 10.3390/ijms19103125] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 12/22/2022] Open
Abstract
AMPK (5’-adenosine monophosphate-activated protein kinase) is heavily involved in skeletal muscle metabolic control through its regulation of many downstream targets. Because of their effects on anabolic and catabolic cellular processes, AMPK plays an important role in the control of skeletal muscle development and growth. In this review, the effects of AMPK signaling, and those of its upstream activator, liver kinase B1 (LKB1), on skeletal muscle growth and atrophy are reviewed. The effect of AMPK activity on satellite cell-mediated muscle growth and regeneration after injury is also reviewed. Together, the current data indicate that AMPK does play an important role in regulating muscle mass and regeneration, with AMPKα1 playing a prominent role in stimulating anabolism and in regulating satellite cell dynamics during regeneration, and AMPKα2 playing a potentially more important role in regulating muscle degradation during atrophy.
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21
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Lindqvist LM, Tandoc K, Topisirovic I, Furic L. Cross-talk between protein synthesis, energy metabolism and autophagy in cancer. Curr Opin Genet Dev 2017; 48:104-111. [PMID: 29179096 DOI: 10.1016/j.gde.2017.11.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/05/2017] [Accepted: 11/06/2017] [Indexed: 12/31/2022]
Abstract
Translation is a pivotal step in the regulation of gene expression as well as one of the most energy consuming processes in the cell. Dysregulation of translation caused by the aberrant function of upstream signaling pathways and/or perturbations in the expression or function of components of the translation machinery is frequent in cancer. In this review, we discuss emerging findings that highlight hitherto unappreciated aspects of signaling to the translation apparatus with the particular focus on emerging connections between protein synthesis, autophagy and energy homeostasis in cancer.
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Affiliation(s)
- Lisa M Lindqvist
- Cell Signalling and Cell Death Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3050, Australia.
| | - Kristofferson Tandoc
- Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada H3T 1E2; Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, QC H4A 3T2, Canada
| | - Ivan Topisirovic
- Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada H3T 1E2; Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, QC H4A 3T2, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC H4A 3T2, Canada; Department of Biochemistry, McGill University, Montreal, QC H4A 3T2, Canada
| | - Luc Furic
- Prostate Cancer Translational Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC 3010, Australia; Cancer Program, Biomedicine Discovery Institute and Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800, Australia.
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22
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Loumaye A, Thissen JP. Biomarkers of cancer cachexia. Clin Biochem 2017; 50:1281-1288. [PMID: 28739222 DOI: 10.1016/j.clinbiochem.2017.07.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/19/2017] [Accepted: 07/19/2017] [Indexed: 12/13/2022]
Abstract
Cachexia is a complex multifactorial syndrome, characterized by loss of skeletal muscle and fat mass, which affects the majority of advanced cancer patients and is associated with poor prognosis. Interestingly, reversing muscle loss in animal models of cancer cachexia leads to prolong survival. Therefore, detecting cachexia and maintaining muscle mass represent a major goal in the care of cancer patients. However, early diagnosis of cancer cachexia is currently limited for several reasons. Indeed, cachexia development is variable according to tumor and host characteristics. In addition, safe, accessible and non-invasive tools to detect skeletal muscle atrophy are desperately lacking in clinical practice. Finally, the precise molecular mechanisms and the key players involved in cancer cachexia remain poorly characterized. The need for an early diagnosis of cancer cachexia supports therefore the quest for a biomarker that might reflect skeletal muscle atrophy process. Current research offers different promising ways to identify such a biomarker. Initially, the quest for a biomarker of cancer cachexia has mostly focused on mediators of muscle atrophy, produced by both tumor and host, in an attempt to define new therapeutic approaches. In another hand, molecules released by the muscle into the circulation during the atrophy process have been also considered as potential biomarkers. More recently, several "omics" studies are emerging to identify new muscular or circulating markers of cancer cachexia. Some genetic markers could also contribute to identify patients more susceptible to develop cachexia. This article reviews our current knowledge regarding potential biomarkers of cancer cachexia.
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Affiliation(s)
- Audrey Loumaye
- Endocrinology, Diabetology and Nutrition Department, IREC, Université Catholique de Louvain, Cliniques Universitaires St-Luc, Brussels, Belgium.
| | - Jean-Paul Thissen
- Endocrinology, Diabetology and Nutrition Department, IREC, Université Catholique de Louvain, Cliniques Universitaires St-Luc, Brussels, Belgium
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23
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Mirzoev T, Tyganov S, Petrova I, Gnyubkin V, Laroche N, Vico L, Shenkman B. Divergent Anabolic Signalling responses of Murine Soleus and Tibialis Anterior Muscles to Chronic 2G Hypergravity. Sci Rep 2017; 7:3514. [PMID: 28615698 PMCID: PMC5471226 DOI: 10.1038/s41598-017-03758-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 04/27/2017] [Indexed: 12/02/2022] Open
Abstract
The purpose of the study was to assess the rate of protein synthesis (PS) and elucidate signalling pathways regulating PS in mouse soleus (Sol) and tibialis anterior (TA) muscles following chronic hypergravity (30-day centrifugation at 2G). The content of the key signalling proteins of the various anabolic signalling pathways was determined by Western-blotting. The rate of PS was assessed using in-vivo SUnSET technique. An exposure to 2G centrifugation did not induce any significant changes in the rate of PS as well as phosphorylation status of the key anabolic markers (AKT, p70s6k, 4E-BP1, GSK-3beta, eEF2) in Sol. On the contrary, a significant 55% increase in PS (p < 0.05) was found in TA. The cause of such a rise in PS could be associated with an increase in AKT (+72%, p < 0.05), GSK-3beta (+60%, p < 0.05) and p70s6k (+40%, p < 0.05) phosphorylation, as well as a decrease in eEF2 phosphorylation (−46%, p < 0.05) as compared to control values. Thus, the results of our study indicate that 30-day 2G centrifugation induces a distinct anabolic response in mouse Sol and TA muscles. The activation of the PS rate in TA could be linked to an up-regulation of both mTORC1-dependent and mTORC1-independent signalling pathways.
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Affiliation(s)
- Timur Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow, Russia.
| | - Sergey Tyganov
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow, Russia
| | - Irina Petrova
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow, Russia
| | - Vasily Gnyubkin
- INSERM U1059, Integrative Biology of Bone Tissue Laboratory, Lyon University, St.- Etienne, France
| | - Norbert Laroche
- INSERM U1059, Integrative Biology of Bone Tissue Laboratory, Lyon University, St.- Etienne, France
| | - Laurence Vico
- INSERM U1059, Integrative Biology of Bone Tissue Laboratory, Lyon University, St.- Etienne, France
| | - Boris Shenkman
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow, Russia
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24
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Johanns M, Pyr Dit Ruys S, Houddane A, Vertommen D, Herinckx G, Hue L, Proud CG, Rider MH. Direct and indirect activation of eukaryotic elongation factor 2 kinase by AMP-activated protein kinase. Cell Signal 2017; 36:212-221. [PMID: 28502587 DOI: 10.1016/j.cellsig.2017.05.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/27/2017] [Accepted: 05/10/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is a key regulator of protein synthesis in mammalian cells. It phosphorylates and inhibits eEF2, the translation factor necessary for peptide translocation during the elongation phase of protein synthesis. When cellular energy demand outweighs energy supply, AMP-activated protein kinase (AMPK) and eEF2K become activated, leading to eEF2 phosphorylation, which reduces the rate of protein synthesis, a process that consumes a large proportion of cellular energy under optimal conditions. AIM The goal of the present study was to elucidate the mechanisms by which AMPK activation leads to increased eEF2 phosphorylation to decrease protein synthesis. METHODS Using genetically modified mouse embryo fibroblasts (MEFs), effects of treatments with commonly used AMPK activators to increase eEF2 phosphorylation were compared with that of the novel compound 991. Bacterially expressed recombinant eEF2K was phosphorylated in vitro by recombinant activated AMPK for phosphorylation site-identification by mass spectrometry followed by site-directed mutagenesis of the identified sites to alanine residues to study effects on the kinetic properties of eEF2K. Wild-type eEF2K and a Ser491/Ser492 mutant were retrovirally re-introduced in eEF2K-deficient MEFs and effects of 991 treatment on eEF2 phosphorylation and protein synthesis rates were studied in these cells. RESULTS & CONCLUSIONS AMPK activation leads to increased eEF2 phosphorylation in MEFs mainly by direct activation of eEF2K and partly by inhibition of mammalian target of rapamycin complex 1 (mTORC1) signaling. Treatment of MEFs with AMPK activators can also lead to eEF2K activation independently of AMPK probably via a rise in intracellular Ca2+. AMPK activates eEF2K by multi-site phosphorylation and the newly identified Ser491/Ser492 is important for activation, leading to mTOR-independent inhibition of protein synthesis. Our study provides new insights into the control of eEF2K by AMPK, with implications for linking metabolic stress to decreased protein synthesis to conserve energy reserves, a pathway that is of major importance in cancer cell survival.
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Affiliation(s)
- M Johanns
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - S Pyr Dit Ruys
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - A Houddane
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - D Vertommen
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - G Herinckx
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - L Hue
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - C G Proud
- South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide, North Terrace, Adelaide, SA 5000, Australia
| | - M H Rider
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium.
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McKnight RA, Yost CC, Zinkhan EK, Fu Q, Callaway CW, Fung CM. Intrauterine growth restriction inhibits expression of eukaryotic elongation factor 2 kinase, a regulator of protein translation. Physiol Genomics 2016; 48:616-25. [PMID: 27317589 DOI: 10.1152/physiolgenomics.00045.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/14/2016] [Indexed: 11/22/2022] Open
Abstract
Nutrient deprivation suppresses protein synthesis by blocking peptide elongation. Transcriptional upregulation and activation of eukaryotic elongation factor 2 kinase (eEF2K) blocks peptide elongation by phosphorylating eukaryotic elongation factor 2. Previous studies examining placentas from intrauterine growth restricted (IUGR) newborn infants show decreased eEF2K expression and activity despite chronic nutrient deprivation. However, the effect of IUGR on hepatic eEF2K expression in the fetus is unknown. We, therefore, examined the transcriptional regulation of hepatic eEF2K gene expression in a Sprague-Dawley rat model of IUGR. We found decreased hepatic eEF2K mRNA and protein levels in IUGR offspring at birth compared with control, consistent with previous placental observations. Furthermore, the CpG island within the eEF2K promoter demonstrated increased methylation at a critical USF 1/2 transcription factor binding site. In vitro methylation of this binding site caused near complete loss of eEF2K promoter activity, designating this promoter as methylation sensitive. The eEF2K promotor in IUGR offspring also lost the protective histone covalent modifications associated with unmethylated CGIs. In addition, the +1 nucleosome was displaced 3' and RNA polymerase loading was reduced at the IUGR eEF2K promoter. Our findings provide evidence to explain why IUGR-induced chronic nutrient deprivation does not result in the upregulation of eEF2K gene transcription.
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Affiliation(s)
- Robert A McKnight
- Division of Neonatology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Christian C Yost
- Division of Neonatology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Erin K Zinkhan
- Division of Neonatology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Qi Fu
- Division of Neonatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Christopher W Callaway
- Division of Neonatology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - Camille M Fung
- Division of Neonatology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah; and
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Philp A, Schenk S, Perez-Schindler J, Hamilton DL, Breen L, Laverone E, Jeromson S, Phillips SM, Baar K. Rapamycin does not prevent increases in myofibrillar or mitochondrial protein synthesis following endurance exercise. J Physiol 2016; 593:4275-84. [PMID: 26227152 DOI: 10.1113/jp271219] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/20/2015] [Indexed: 01/20/2023] Open
Abstract
The present study aimed to investigate the role of the mechanistic target of rapamycin complex 1 (mTORC1) in the regulation of myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis following endurance exercise. Forty-two female C57BL/6 mice performed 1 h of treadmill running (18 m min(-1) ; 5° grade), 1 h after i.p. administration of rapamycin (1.5 mg · kg(-1) ) or vehicle. To quantify skeletal muscle protein fractional synthesis rates, a flooding dose (50 mg · kg(-1) ) of l-[ring-(13) C6 ]phenylalanine was administered via i.p. injection. Blood and gastrocnemius muscle were collected in non-exercised control mice, as well as at 0.5, 3 and 6 h after completing exercise (n = 4 per time point). Skeletal muscle MyoPS and MitoPS were determined by measuring isotope incorporation in their respective protein pools. Activation of the mTORC1-signalling cascade was measured via direct kinase activity assay and immunoblotting, whereas genes related to mitochondrial biogenesis were measured via a quantitative RT-PCR. MyoPS increased rapidly in the vehicle group post-exercise and remained elevated for 6 h, whereas this response was transiently blunted (30 min post-exercise) by rapamycin. By contrast, MitoPS was unaffected by rapamycin, and was increased over the entire post-exercise recovery period in both groups (P < 0.05). Despite rapid increases in both MyoPS and MitoPS, mTORC1 activation was suppressed in both groups post-exercise for the entire 6 h recovery period. Peroxisome proliferator activated receptor-γ coactivator-1α, pyruvate dehydrogenase kinase 4 and mitochondrial transcription factor A mRNA increased post-exercise (P < 0.05) and this response was augmented by rapamycin (P < 0.05). Collectively, these data suggest that endurance exercise stimulates MyoPS and MitoPS in skeletal muscle independently of mTORC1 activation.
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Affiliation(s)
- Andrew Philp
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.,Neurobiology, Physiology and Behaviour, University of California, Davis, CA, USA
| | - Simon Schenk
- Department of Orthopaedic Surgery and Biomedical Sciences Graduate Program, University of California, San Diego, CA, USA
| | - Joaquin Perez-Schindler
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | | | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK.,Department of Kinesiology, McMaster University, Hamilton, ON, CA
| | - Erin Laverone
- Neurobiology, Physiology and Behaviour, University of California, Davis, CA, USA
| | | | | | - Keith Baar
- Neurobiology, Physiology and Behaviour, University of California, Davis, CA, USA
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Xu Z, Zhao L, Yang X, Ma S, Ge Y, Liu Y, Liu S, Shi J, Zheng D. Mmu-miR-125b overexpression suppresses NO production in activated macrophages by targeting eEF2K and CCNA2. BMC Cancer 2016; 16:252. [PMID: 27020049 PMCID: PMC4809031 DOI: 10.1186/s12885-016-2288-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 03/22/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND MicroRNAs have been shown to be important regulators of the immune response and the development of the immune system. It was reported that microRNA-125b (miR-125b) was down-regulated in macrophages challenged with endotoxin. However, little is known about the function and mechanism of action of miR-125b in macrophage activation. Macrophages use L-arginine to synthesize nitric oxide (NO) through inducible NO synthase (iNOS), and the released NO contributes to the tumoricidal activity of macrophages. METHODS Luciferase reporter assays were employed to validate regulation of a putative target of miR-125b. The effect of miR-125b on endogenous levels of this target were subsequently confirmed via Western blot. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to determine the expression level of miR-125b in macrophage. MTS assays were conducted to explore the impact of miR-125b overexpression on the cell viability of 4T1 cells. RESULTS Here, we demonstrate that mmu-miR-125b overexpression suppresses NO production in activated macrophages and that LPS-activated macrophages with overexpressed mmu-miR-125b promote 4T1 tumor cell proliferation in vitro and 4T1 tumor growth in vivo. CCNA2 and eEF2K are the direct and functional targets of mmu-miR-125b in macrophages; CCNA2 and eEF2K expression was knocked down, which mimicked the mmu-miR-125b overexpression phenotype. CONCLUSIONS These data suggest that mmu-miR-125b decreases NO production in activated macrophages at least partially by suppressing eEF2K and CCNA2 expression.
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Affiliation(s)
- Zhenbiao Xu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Lianmei Zhao
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Xin Yang
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Sisi Ma
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Yehua Ge
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Yanxin Liu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Shilian Liu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China
| | - Juan Shi
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China.
| | - Dexian Zheng
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China.
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SHI QIANQIAN, XU XIANLIN, LIU QING, LUO FENGBAO, SHI JIAN, HE XIAOZHOU. MicroRNA-877 acts as a tumor suppressor by directly targeting eEF2K in renal cell carcinoma. Oncol Lett 2016; 11:1474-1480. [PMID: 26893763 PMCID: PMC4734253 DOI: 10.3892/ol.2015.4072] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 08/06/2015] [Indexed: 12/17/2022] Open
Abstract
MicroRNAs (miRNAs) are involved in tumorigenesis. However, little is known about their role in renal cell carcinoma (RCC). In the present study, the function of the miRNA miR-877 in RCC was investigated, and its expression levels in blood and paired RCC tissues were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Bioinformatics analysis predicted eukaryotic elongation factor-2 kinase (eEF2K) to be the potential mRNA target of miR-877, which was verified by luciferase assay. The expression levels of eEF2K in RCC tissues were evaluated by western blot analysis and qPCR. The proliferation and migration abilities of RCC cells were measured by MTT and in vitro wound healing assays, respectively. The present results indicated that the expression levels of miR-877 were downregulated in blood and paired RCC tissues, whereas the expression levels of eEF2K were upregulated in RCC tissues. In addition, overexpression of miR-877 and knockdown of eEF2K significantly reduced the proliferation and migration abilities of RCC cells in vitro. Furthermore, miR-877 affected the eEF2K/eEF2 signaling pathway in these cells. In conclusion, the present study has demonstrated that miR-877 suppresses the proliferation and migration abilities of RCC cells by modulating the eEF2K/eEF2 signaling cascade. Therefore, miR-877 may be considered a potential biomarker for the diagnosis of RCC.
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Affiliation(s)
- QIANQIAN SHI
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - XIANLIN XU
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - QING LIU
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - FENGBAO LUO
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - JIAN SHI
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
| | - XIAOZHOU HE
- Department of Urology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu 213000, P.R. China
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Thomassen M, Gunnarsson TP, Christensen PM, Pavlovic D, Shattock MJ, Bangsbo J. Intensive training and reduced volume increases muscle FXYD1 expression and phosphorylation at rest and during exercise in athletes. Am J Physiol Regul Integr Comp Physiol 2016; 310:R659-69. [PMID: 26791827 DOI: 10.1152/ajpregu.00081.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 01/18/2016] [Indexed: 01/10/2023]
Abstract
The present study examined the effect of intensive training in combination with marked reduction in training volume on phospholemman (FXYD1) expression and phosphorylation at rest and during exercise. Eight well-trained cyclists replaced their regular training with speed-endurance training (10-12 × ∼30-s sprints) two or three times per week and aerobic high-intensity training (4-5 × 3-4 min at 90-95% of peak aerobic power output) 1-2 times per week for 7 wk and reduced the training volume by 70%. Muscle biopsies were obtained before and during a repeated high-intensity exercise protocol, and protein expression and phosphorylation were determined by Western blot analysis. Expression of FXYD1 (30%), actin (40%), mammalian target of rapamycin (mTOR) (12%), phospholamban (PLN) (16%), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) γ/δ (25%) was higher (P < 0.05) than before the training intervention. In addition, after the intervention, nonspecific FXYD1 phosphorylation was higher (P < 0.05) at rest and during exercise, mainly achieved by an increased FXYD1 Ser-68 phosphorylation, compared with before the intervention. CaMKII, Thr-287, and eukaryotic elongation factor 2 Thr-56 phosphorylation at rest and during exercise, overall PKCα/β, Thr-638/641, and mTOR Ser-2448 phosphorylation during repeated intense exercise as well as resting PLN Thr-17 phosphorylation were also higher (P < 0.05) compared with before the intervention period. Thus, a period of high-intensity training with reduced training volume increases expression and phosphorylation levels of FXYD1, which may affect Na(+)/K(+) pump activity and muscle K(+) homeostasis during intense exercise. Furthermore, higher expression of CaMKII and PLN, as well as increased phosphorylation of CaMKII Thr-287 may have improved intracellular Ca(2+) handling.
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Affiliation(s)
- Martin Thomassen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Thomas P Gunnarsson
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Peter M Christensen
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
| | - Davor Pavlovic
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Michael J Shattock
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; and
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Burd NA, Gorissen SH, van Vliet S, Snijders T, van Loon LJ. Differences in postprandial protein handling after beef compared with milk ingestion during postexercise recovery: a randomized controlled trial. Am J Clin Nutr 2015; 102:828-36. [PMID: 26354539 DOI: 10.3945/ajcn.114.103184] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 07/30/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Protein consumed after resistance exercise increases postexercise muscle protein synthesis rates. To date, dairy protein has been studied extensively, with little known about the capacity of other protein-dense foods to augment postexercise muscle protein synthesis rates. OBJECTIVE We aimed to compare protein digestion and absorption kinetics, postprandial amino acid availability, anabolic signaling, and the subsequent myofibrillar protein synthetic response after the ingestion of milk compared with beef during recovery from resistance-type exercise. DESIGN In crossover trials, 12 healthy young men performed a single bout of resistance exercise. Immediately after cessation of exercise, participants ingested 30 g protein by consuming isonitrogenous amounts of intrinsically l-[1-(13)C]phenylalanine-labeled beef or milk. Blood and muscle biopsy samples were collected at rest and after exercise during primed continuous infusions of l-[ring-(2)H5]phenylalanine and l-[ring-3,5-(2)H2]tyrosine to assess protein digestion and absorption kinetics, plasma amino acid availability, anabolic signaling, and subsequent myofibrillar protein synthesis rates in vivo in young men. RESULTS Beef protein-derived phenylalanine appeared more rapidly in circulation compared with milk ingestion (P < 0.001). The availability of phenylalanine during the 5-h postexercise period tended to be higher after beef (64% ± 3%) ingestion than after milk ingestion (57% ± 3%; P = 0.08). Both beef and milk ingestion were followed by an increase in the phosphorylation of mammalian target of rapamycin complex 1 and 70-kDa S6 protein kinase 1 during postexercise recovery. Milk ingestion increased myofibrillar protein synthesis rates to a greater extent than did beef ingestion during the 0- to 2-h postexercise phase (P = 0.013). However, the increase in myofibrillar protein synthesis rates did not differ between milk and beef ingestion during the entire 0- to 5-h postexercise phase (P = 0.114). CONCLUSIONS Both milk and beef ingestion augment the postexercise myofibrillar protein synthetic response in young men, with a stronger stimulation of myofibrillar protein synthesis during the early postprandial stage after milk ingestion. This trial was registered at www.clinicaltrials.gov as NCT01578590.
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Affiliation(s)
- Nicholas A Burd
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Stefan H Gorissen
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Stephan van Vliet
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Tim Snijders
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Luc Jc van Loon
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
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Shenkman BS, Belova SP, Lomonosova YN, Kostrominova TY, Nemirovskaya TL. Calpain-dependent regulation of the skeletal muscle atrophy following unloading. Arch Biochem Biophys 2015; 584:36-41. [DOI: 10.1016/j.abb.2015.07.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 07/02/2015] [Accepted: 07/15/2015] [Indexed: 12/28/2022]
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Kim W, Conery AL, Rajamuthiah R, Fuchs BB, Ausubel FM, Mylonakis E. Identification of an Antimicrobial Agent Effective against Methicillin-Resistant Staphylococcus aureus Persisters Using a Fluorescence-Based Screening Strategy. PLoS One 2015; 10:e0127640. [PMID: 26039584 PMCID: PMC4454602 DOI: 10.1371/journal.pone.0127640] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/17/2015] [Indexed: 12/21/2022] Open
Abstract
Persisters are a subpopulation of normal bacterial cells that show tolerance to conventional antibiotics. Persister cells are responsible for recalcitrant chronic infections and new antibiotics effective against persisters would be a major development in the treatment of these infections. Using the reporter dye SYTOX Green that only stains cells with permeabilized membranes, we developed a fluorescence-based screening assay in a 384-well format for identifying compounds that can kill methicillin-resistant Staphylococcus aureus (MRSA) persisters. The assay proved robust and suitable for high throughput screening (Z`-factor: >0.7). In screening a library of hits from a previous screen, which identified compounds that had the ability to block killing of the nematode Caenorhabditis by MRSA, we discovered that the low molecular weight compound NH125, a bacterial histidine kinase inhibitor, kills MRSA persisters by causing cell membrane permeabilization, and that 5 μg/mL of the compound can kill all cells to the limit of detection in a 108 CFU/mL culture of MRSA persisters within 3h. Furthermore, NH125 disrupts 50% of established MRSA biofilms at 20 μg/mL and completely eradicates biofilms at 160 μg/mL. Our results suggest that the SYTOX Green screening assay is suitable for large-scale projects to identify small molecules effective against MRSA persisters and should be easily adaptable to a broad range of pathogens that form persisters. Since NH125 has strong bactericidal properties against MRSA persisters and high selectivity to bacteria, we believe NH125 is a good anti-MRSA candidate drug that should be further evaluated.
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Affiliation(s)
- Wooseong Kim
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Annie L. Conery
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rajmohan Rajamuthiah
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Beth Burgwyn Fuchs
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Frederick M. Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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eEF-2 Phosphorylation Down-Regulates P-Glycoprotein Over-Expression in Rat Brain Microvessel Endothelial Cells. PLoS One 2015; 10:e0125389. [PMID: 25962137 PMCID: PMC4427111 DOI: 10.1371/journal.pone.0125389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 03/24/2015] [Indexed: 01/07/2023] Open
Abstract
Objective We investigated whether glutamate, NMDA receptors, and eukaryote elongation factor-2 kinase (eEF-2K)/eEF-2 regulate P-glycoprotein expression, and the effects of the eEF-2K inhibitor NH125 on the expression of P-glycoprotein in rat brain microvessel endothelial cells (RBMECs). Methods Cortex was obtained from newborn Wistar rat brains. After surface vessels and meninges were removed, the pellet containing microvessels was resuspended and incubated at 37°C in culture medium. Cell viability was assessed by the MTT assay. RBMECs were identified by immunohistochemistry with anti-vWF. P-glycoprotein, phospho-eEF-2, and eEF-2 expression were determined by western blot analysis. Mdr1a gene expression was analyzed by RT-PCR. Results Mdr1a mRNA, P-glycoprotein and phospho-eEF-2 expression increased in L-glutamate stimulated RBMECs. P-glycoprotein and phospho-eEF-2 expression were down-regulated after NH125 treatment in L-glutamate stimulated RBMECs. Conclusions eEF-2K/eEF-2 should have played an important role in the regulation of P-glycoprotein expression in RBMECs. eEF-2K inhibitor NH125 could serve as an efficacious anti-multidrug resistant agent.
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Apró W, Moberg M, Hamilton DL, Ekblom B, van Hall G, Holmberg HC, Blomstrand E. Resistance exercise-induced S6K1 kinase activity is not inhibited in human skeletal muscle despite prior activation of AMPK by high-intensity interval cycling. Am J Physiol Endocrinol Metab 2015; 308:E470-81. [PMID: 25605643 DOI: 10.1152/ajpendo.00486.2014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Combining endurance and strength training in the same session has been reported to reduce the anabolic response to the latter form of exercise. The underlying mechanism, based primarily on results from rodent muscle, is proposed to involve AMPK-dependent inhibition of mTORC1 signaling. This hypothesis was tested in eight trained male subjects who in randomized order performed either resistance exercise only (R) or interval cycling followed by resistance exercise (ER). Biopsies taken from the vastus lateralis before and after endurance exercise and repeatedly after resistance exercise were assessed for glycogen content, kinase activity, protein phosphorylation, and gene expression. Mixed muscle fractional synthetic rate was measured at rest and during 3 h of recovery using the stable isotope technique. In ER, AMPK activity was elevated immediately after both endurance and resistance exercise (∼90%, P < 0.05) but was unchanged in R. Thr(389) phosphorylation of S6K1 was increased severalfold immediately after exercise (P < 0.05) in both trials and increased further throughout recovery. After 90 and 180 min recovery, S6K1 activity was elevated (∼55 and ∼110%, respectively, P < 0.05) and eukaryotic elongation factor 2 phosphorylation was reduced (∼55%, P < 0.05) with no difference between trials. In contrast, markers for protein catabolism were differently influenced by the two modes of exercise; ER induced a significant increase in gene and protein expression of MuRF1 (P < 0.05), which was not observed following R exercise only. In conclusion, cycling-induced elevation in AMPK activity does not inhibit mTOR complex 1 signaling after subsequent resistance exercise but may instead interfere with the hypertrophic response by influencing key components in protein breakdown.
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Affiliation(s)
- William Apró
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden; Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden;
| | - Marcus Moberg
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - D Lee Hamilton
- Health and Exercise Sciences Research Group, University of Stirling, Stirling, United Kingdom
| | - Björn Ekblom
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Gerrit van Hall
- Department of Biomedical Sciences, Rigshospitalet, University of Copenhagen, Denmark
| | - Hans-Christer Holmberg
- Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden; and
| | - Eva Blomstrand
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Wright CR, Brown EL, Ward AC, Russell AP. G-CSF treatment can attenuate dexamethasone-induced reduction in C2C12 myotube protein synthesis. Cytokine 2015; 73:1-7. [PMID: 25689616 DOI: 10.1016/j.cyto.2015.01.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 01/27/2023]
Abstract
Granulocyte-colony stimulating factor (G-CSF) has been demonstrated to enhance skeletal muscle recovery following injury and increases muscle function in the context of neuromuscular disease in rodent models. However, understanding of the underlying mechanisms used by G-CSF to mediate these functions remains poor. G-CSF acts on responsive cells through binding to a specific membrane spanning receptor, G-CSFR. Recently identified, the G-CSFR is expressed in myoblasts, myotubes and mature skeletal muscle tissue. Therefore, elucidating the actions of G-CSF in skeletal muscle represents an important prerequisite to consider G-CSF as a therapeutic agent to treat skeletal muscle. Here we show for the first time that treatment with moderate doses (4 and 40ng/ml) of G-CSF attenuates the effects of dexamethasone in reducing protein synthesis in C2C12 myotubes. However, a higher dose (100ng/ml) of G-CSF exacerbates the dexamethasone-induced reduction in protein synthesis. In contrast, G-CSF had no effect on basal or dexamethasone-induced protein degradation, nor did G-CSF influence the phosphorylation of Akt, STAT3, Erk1/2, Src, Lyn and Erk5 in C2C12 myotubes. In conclusion, physiologically relevant doses of G-CSF may attenuate reduced skeletal muscle protein synthesis during catabolic conditions, thereby improving recovery.
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Affiliation(s)
- Craig R Wright
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Victoria, Australia
| | - Erin L Brown
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Victoria, Australia
| | - Alister C Ward
- Molecular and Medical Research SRC, School of Medicine, Deakin University, Waurn Ponds, 3216 Victoria, Australia
| | - Aaron P Russell
- Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Victoria, Australia.
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Atherton PJ, Phillips BE, Wilkinson DJ. Exercise and Regulation of Protein Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:75-98. [DOI: 10.1016/bs.pmbts.2015.06.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Interference between concurrent resistance and endurance exercise: molecular bases and the role of individual training variables. Sports Med 2014; 44:743-62. [PMID: 24728927 DOI: 10.1007/s40279-014-0162-1] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Concurrent training is defined as simultaneously incorporating both resistance and endurance exercise within a periodized training regime. Despite the potential additive benefits of combining these divergent exercise modes with regards to disease prevention and athletic performance, current evidence suggests that this approach may attenuate gains in muscle mass, strength, and power compared with undertaking resistance training alone. This has been variously described as the interference effect or concurrent training effect. In recent years, understanding of the molecular mechanisms mediating training adaptation in skeletal muscle has emerged and provided potential mechanistic insight into the concurrent training effect. Although it appears that various molecular signaling responses induced in skeletal muscle by endurance exercise can inhibit pathways regulating protein synthesis and stimulate protein breakdown, human studies to date have not observed such molecular 'interference' following acute concurrent exercise that might explain compromised muscle hypertrophy following concurrent training. However, given the multitude of potential concurrent training variables and the limitations of existing evidence, the potential roles of individual training variables in acute and chronic interference are not fully elucidated. The present review explores current evidence for the molecular basis of the specificity of training adaptation and the concurrent interference phenomenon. Additionally, insights provided by molecular and performance-based concurrent training studies regarding the role of individual training variables (i.e., within-session exercise order, between-mode recovery, endurance training volume, intensity, and modality) in the concurrent interference effect are discussed, along with the limitations of our current understanding of this complex paradigm.
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Hayasaka M, Tsunekawa H, Yoshinaga M, Murakami T. Endurance exercise induces REDD1 expression and transiently decreases mTORC1 signaling in rat skeletal muscle. Physiol Rep 2014; 2:2/12/e12254. [PMID: 25539833 PMCID: PMC4332227 DOI: 10.14814/phy2.12254] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Working muscle conserves adenosine triphosphate (ATP) for muscle contraction by attenuating protein synthesis through several different pathways. Regulated in development and DNA damage response 1 (REDD1) is one candidate protein that can itself attenuate muscle protein synthesis during muscle contraction. In this study, we investigated whether endurance exercise induces REDD1 expression in association with decreased mammalian target of rapamycin (mTOR) complex I (mTORC1) signaling and global protein synthesis in rat skeletal muscle. After overnight fasting, rats ran on a treadmill at a speed of 28 m/min for 60 min, and were killed before and immediately, 1, 3, 6, 12, and 24 h after exercise. REDD1 mRNA and corresponding protein levels increased rapidly immediately after exercise, and gradually decreased back to the basal level over a period of 6 h in the gastrocnemius muscle. Phosphorylation of mTOR Ser2448 and S6K1 Thr389 increased with the exercise, but diminished in 1–3 h into the recovery period after cessation of exercise. The rate of protein synthesis, as determined by the surface sensing of translation (SUnSET) method, was not altered by exercise in fasted muscle. These results suggest that REDD1 attenuates exercise‐induced mTORC1 signaling. This may be one mechanism responsible for blunting muscle protein synthesis during exercise and in the early postexercise recovery period. We show that REDD1 expression is rapidly induced by an acute bout of endurance exercise in association with a decrease in mTORC1 signaling in rat muscle. The rate of mixed‐muscle protein synthesis was, however, not altered by exercise in fasted state. These results suggest that REDD1‐induced suppression of mTORC1 signaling may be one mechanism to blunt muscle protein synthesis during exercise and postexercise early recovery period.
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Affiliation(s)
- Miki Hayasaka
- Department of Nutrition, Shigakkan University, Yokone-Machi, Ohbu, Japan
| | - Haruka Tsunekawa
- Department of Nutrition, Shigakkan University, Yokone-Machi, Ohbu, Japan
| | - Mariko Yoshinaga
- Department of Nutrition, Shigakkan University, Yokone-Machi, Ohbu, Japan
| | - Taro Murakami
- Department of Nutrition, Shigakkan University, Yokone-Machi, Ohbu, Japan
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Abstract
With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB). While resistance exercise and postprandial hyperaminoacidemia both stimulate MPS, it is through the synergistic effects of these two stimuli that a net gain in muscle proteins occurs and muscle fiber hypertrophy takes place. Current evidence favors the post-exercise period as a time when rapid hyperaminoacidemia promotes a marked rise in the rate of MPS. Dietary proteins with a full complement of essential amino acids and high leucine contents that are rapidly digested are more likely to be efficacious in this regard. Various other compounds have been added to complete proteins, including carbohydrate, arginine and glutamine, in an attempt to augment the effectiveness of the protein in stimulating MPS (or suppressing MPB), but none has proved particularly effective. Evidence points to a higher protein intake in combination with resistance exercise as being efficacious in allowing preservation, and on occasion increases, in skeletal muscle mass with dietary energy restriction aimed at the promotion of weight loss. The goal of this review is to examine practices of protein ingestion in combination with resistance exercise that have some evidence for efficacy and to highlight future areas for investigation.
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Jensen TE, Angin Y, Sylow L, Richter EA. Is contraction-stimulated glucose transport feedforward regulated by Ca2+? Exp Physiol 2014; 99:1562-8. [DOI: 10.1113/expphysiol.2014.081679] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Thomas E. Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports; University of Copenhagen; Denmark
| | - Yeliz Angin
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports; University of Copenhagen; Denmark
| | - Lykke Sylow
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports; University of Copenhagen; Denmark
| | - Erik A. Richter
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports; University of Copenhagen; Denmark
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Steiner JL, Lang CH. Alcohol impairs skeletal muscle protein synthesis and mTOR signaling in a time-dependent manner following electrically stimulated muscle contraction. J Appl Physiol (1985) 2014; 117:1170-9. [PMID: 25257868 DOI: 10.1152/japplphysiol.00180.2014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Alcohol (EtOH) decreases protein synthesis and mammalian target of rapamycin (mTOR)-mediated signaling and blunts the anabolic response to growth factors in skeletal muscle. The purpose of the current investigation was to determine whether acute EtOH intoxication antagonizes the contraction-induced increase in protein synthesis and mTOR signaling in skeletal muscle. Fasted male mice were injected intraperitoneally with 3 g/kg EtOH or saline (control), and the right hindlimb was electrically stimulated (10 sets of 6 contractions). The gastrocnemius muscle complex was collected 30 min, 4 h, or 12 h after stimulation. EtOH decreased in vivo basal protein synthesis (PS) in the nonstimulated muscle compared with time-matched Controls at 30 min, 4 h, and 12 h. In Control, but not EtOH, PS was decreased 15% after 30 min. In contrast, PS was increased in Control 4 h poststimulation but remained unchanged in EtOH. Last, stimulation increased PS 10% in Control and EtOH at 12 h, even though the absolute rate remained reduced by EtOH. The stimulation-induced increase in the phosphorylation of S6K1 Thr(421)/Ser(424) (20-52%), S6K1 Thr(389) (45-57%), and its substrate rpS6 Ser(240/244) (37-72%) was blunted by EtOH at 30 min, 4 h, and 12 h. Phosphorylation of 4E-BP1 Ser(65) was also attenuated by EtOH (61%) at 4 h. Conversely, phosphorylation of extracellular signal-regulated kinase Thr(202)/Tyr(204) was increased by stimulation in Control and EtOH mice at 30 min but only in Control at 4 h. Our data indicate that acute EtOH intoxication suppresses muscle protein synthesis for at least 12 h and greatly impairs contraction-induced changes in synthesis and mTOR signaling.
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Affiliation(s)
- Jennifer L Steiner
- Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, Pennsylvania
| | - Charles H Lang
- Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, Pennsylvania
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A small-molecule benzimidazole derivative that potently activates AMPK to increase glucose transport in skeletal muscle: comparison with effects of contraction and other AMPK activators. Biochem J 2014; 460:363-75. [PMID: 24665903 DOI: 10.1042/bj20131673] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
AMPK (AMP-activated protein kinase) is an attractive therapeutic drug target for treating metabolic disorders. We studied the effects of an AMPK activator developed by Merck (ex229 from patent application WO2010036613), comparing chemical activation with contraction in intact incubated skeletal muscles. We also compared effects of ex229 with those of the Abbott A769662 compound and AICAR (5-amino-4-imidazolecarboxamide riboside). In rat epitrochlearis muscle, ex229 dose-dependently increased AMPK activity of α1-, α2-, β1- and β2-containing complexes with significant increases in AMPK activity seen at a concentration of 50 μM. At a concentration of 100 μM, AMPK activation was similar to that observed after contraction and importantly led to an ~2-fold increase in glucose uptake. In AMPK α1-/α2-catalytic subunit double-knockout myotubes incubated with ex229, the increases in glucose uptake and ACC (acetyl-CoA carboxylase) phosphorylation seen in control cells were completely abolished, suggesting that the effects of the compound were AMPK-dependent. When muscle glycogen levels were reduced by ~50% after starvation, ex229-induced AMPK activation and glucose uptake were amplified in a wortmannin-independent manner. In L6 myotubes incubated with ex229, fatty acid oxidation was increased. Furthermore, in mouse EDL (extensor digitorum longus) and soleus muscles, ex229 increased both AMPK activity and glucose uptake at least 2-fold. In summary, ex229 efficiently activated skeletal muscle AMPK and elicited metabolic effects in muscle appropriate for treating Type 2 diabetes by stimulating glucose uptake and increasing fatty acid oxidation.
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43
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Contraction-stimulated glucose transport in muscle is controlled by AMPK and mechanical stress but not sarcoplasmatic reticulum Ca(2+) release. Mol Metab 2014; 3:742-53. [PMID: 25353002 PMCID: PMC4209358 DOI: 10.1016/j.molmet.2014.07.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/11/2014] [Accepted: 07/16/2014] [Indexed: 12/25/2022] Open
Abstract
Understanding how muscle contraction orchestrates insulin-independent muscle glucose transport may enable development of hyperglycemia-treating drugs. The prevailing concept implicates Ca2+ as a key feed forward regulator of glucose transport with secondary fine-tuning by metabolic feedback signals through proteins such as AMPK. Here, we demonstrate in incubated mouse muscle that Ca2+ release is neither sufficient nor strictly necessary to increase glucose transport. Rather, the glucose transport response is associated with metabolic feedback signals through AMPK, and mechanical stress-activated signals. Furthermore, artificial stimulation of AMPK combined with passive stretch of muscle is additive and sufficient to elicit the full contraction glucose transport response. These results suggest that ATP-turnover and mechanical stress feedback are sufficient to fully increase glucose transport during muscle contraction, and call for a major reconsideration of the established Ca2+ centric paradigm.
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Dahmani R, Just PA, Delay A, Canal F, Finzi L, Prip-Buus C, Lambert M, Sujobert P, Buchet-Poyau K, Miller E, Cavard C, Marmier S, Terris B, Billaud M, Perret C. A novel LKB1 isoform enhances AMPK metabolic activity and displays oncogenic properties. Oncogene 2014; 34:2337-46. [PMID: 24998845 DOI: 10.1038/onc.2014.182] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 04/28/2014] [Accepted: 05/16/2014] [Indexed: 12/13/2022]
Abstract
The LKB1 tumor suppressor gene encodes a master kinase that coordinates the regulation of energetic metabolism and cell polarity. We now report the identification of a novel isoform of LKB1 (named ΔN-LKB1) that is generated through alternative transcription and internal initiation of translation of the LKB1 mRNA. The ΔN-LKB1 protein lacks the N-terminal region and a portion of the kinase domain. Although ΔN-LKB1 is catalytically inactive, it potentiates the stimulating effect of LKB1 on the AMP-activated protein kinase (AMPK) metabolic sensor through a direct interaction with the regulatory autoinhibitory domain of AMPK. In contrast, ΔN-LKB1 negatively interferes with the LKB1 polarizing activity. Finally, combining in vitro and in vivo approaches, we showed that ΔN-LKB1 has an intrinsic oncogenic property. ΔN-LKB1 is expressed solely in the lung cancer cell line, NCI-H460. Silencing of ΔN-LKB1 decreased the survival of NCI-H460 cells and inhibited their tumorigenicity when engrafted in nude mice. In conclusion, we have identified a novel LKB1 isoform that enhances the LKB1-controlled AMPK metabolic activity but inhibits LKB1-induced polarizing activity. Both the LKB1 tumor suppressor gene and the oncogene ΔN-LKB1 are expressed from the same locus and this may account for some of the paradoxical effects of LKB1 during tumorigenesis.
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Affiliation(s)
- R Dahmani
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - P-A Just
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - A Delay
- Institut Albert Bonniot, CRI Inserm/UJF U823, Rond Point de la Chantourne, La Tronche, France
| | - F Canal
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - L Finzi
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - C Prip-Buus
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France
| | - M Lambert
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France
| | - P Sujobert
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France
| | - K Buchet-Poyau
- Institut Albert Bonniot, CRI Inserm/UJF U823, Rond Point de la Chantourne, La Tronche, France
| | - E Miller
- Section of Cardiology, Boston University School of Medicine, Boston, MA, USA
| | - C Cavard
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - S Marmier
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
| | - B Terris
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France [5] Pathology Unit, Hôpital Cochin, Paris, France
| | - M Billaud
- Institut Albert Bonniot, CRI Inserm/UJF U823, Rond Point de la Chantourne, La Tronche, France
| | - C Perret
- 1] Inserm, U1016, Institut Cochin, Paris, France [2] Cnrs, UMR8104, Paris, France [3] Université Paris Descartes, Paris, France [4] Equipe labellisée LNCC, Paris, France
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45
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Jessen N, Sundelin EI, Møller AB. AMP kinase in exercise adaptation of skeletal muscle. Drug Discov Today 2014; 19:999-1002. [DOI: 10.1016/j.drudis.2014.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/07/2014] [Indexed: 11/25/2022]
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Ogasawara R, Sato K, Matsutani K, Nakazato K, Fujita S. The order of concurrent endurance and resistance exercise modifies mTOR signaling and protein synthesis in rat skeletal muscle. Am J Physiol Endocrinol Metab 2014; 306:E1155-62. [PMID: 24691029 DOI: 10.1152/ajpendo.00647.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Concurrent training, a combination of endurance (EE) and resistance exercise (RE) performed in succession, may compromise the muscle hypertrophic adaptations induced by RE alone. However, little is known about the molecular signaling interactions underlying the changes in skeletal muscle adaptation during concurrent training. Here, we used an animal model to investigate whether EE before or after RE affects the molecular signaling associated with muscle protein synthesis, specifically the interaction between RE-induced mammalian target of rapamycin complex 1 (mTORC1) signaling and EE-induced AMP-activated protein kinase (AMPK) signaling. Male Sprague-Dawley rats were divided into five groups: an EE group (treadmill, 25 m/min, 60 min), an RE group (maximum isometric contraction via percutaneous electrical stimulation for 3 × 10 s, 5 sets), an EE before RE group, an EE after RE group, and a nonexercise control group. Phosphorylation of p70S6K, a marker of mTORC1 activity, was significantly increased 3 h after RE in both the EE before RE and EE after RE groups, but the increase was smaller in latter. Furthermore, protein synthesis was greatly increased 6 h after RE in the EE before RE group. Increases in the phosphorylation of AMPK and Raptor were observed only in the EE after RE group. Akt and mTOR phosphorylation were increased in both groups, with no between-group differences. Our results suggest that the last bout of exercise dictates the molecular responses and that mTORC1 signaling induced by any prior bout of RE may be downregulated by a subsequent bout of EE.
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Affiliation(s)
- Riki Ogasawara
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan; The Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan;
| | - Koji Sato
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan; Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, Shiga, Japan; and
| | - Kenji Matsutani
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Koichi Nakazato
- Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan
| | - Satoshi Fujita
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
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Van Thienen R, D'Hulst G, Deldicque L, Hespel P. Biochemical artifacts in experiments involving repeated biopsies in the same muscle. Physiol Rep 2014; 2:e00286. [PMID: 24819751 PMCID: PMC4098731 DOI: 10.14814/phy2.286] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Needle biopsies are being extensively used in clinical trials addressing muscular adaptation to exercise and diet. Still, the potential artifacts due to biopsy sampling are often overlooked. Healthy volunteers (n = 9) underwent two biopsies through a single skin incision in a pretest. Two days later (posttest) another biopsy was taken 3 cm proximally and 3 cm distally to the pretest incision. Muscle oxygenation status (tissue oxygenation index [TOI]) was measured by near‐infrared spectroscopy. Biopsy samples were analyzed for 40 key markers (mRNA and protein contents) of myocellular O2 sensing, inflammation, cell proliferation, mitochondrial biogenesis, protein synthesis and breakdown, oxidative stress, and energy metabolism. In the pretest, all measurements were identical between proximal and distal biopsies. However, compared with the pretest, TOI in the posttest was reduced in the proximal (−10%, P < 0.05), but not in the distal area. Conversely, most inflammatory markers were upregulated at the distal (100–500%, P < 0.05), but not at the proximal site. Overall, 29 of the 40 markers measured, equally distributed over all pathways studied, were either up‐ or downregulated by 50–500% (P < 0.05). In addition, 19 markers yielded conflicting results between the proximal and distal measurements (P < 0.05). This study clearly documents that prior muscle biopsies can cause major disturbances in myocellular signaling pathways in needle biopsies specimens sampled 48 h later. In addition, different biopsy sites within identical experimental conditions yielded conflicting results. This study clearly demonstrates that skeletal muscle biopsying per se, at least by causing local tissue inflammation and/or topical deoxygenation, can substantially alter biochemical events happening in needle biopsy specimens sampled at a later day in the same muscle belly. It is crucial to take into account these potential artifacts whenever investigating the cellular mechanisms implicated in adaptation to exercise, recovery, or hypoxia.
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Affiliation(s)
- Ruud Van Thienen
- Exercise Physiology Research Group - Department of Kinesiology, KU Leuven, Tervuursevest 101, Leuven, B-3001, Belgium
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48
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Kenney JW, Moore CE, Wang X, Proud CG. Eukaryotic elongation factor 2 kinase, an unusual enzyme with multiple roles. Adv Biol Regul 2014; 55:15-27. [PMID: 24853390 DOI: 10.1016/j.jbior.2014.04.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/15/2014] [Indexed: 12/27/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a member of the small group of atypical 'α-kinases'. It phosphorylates and inhibits eukaryotic elongation factor 2, to slow down the elongation stage of protein synthesis, which normally consumes a great deal of energy and amino acids. The activity of eEF2K is normally dependent on calcium ions and calmodulin. eEF2K is also regulated by a plethora of other inputs, including inhibition by signalling downstream of anabolic signalling pathways such as the mammalian target of rapamycin complex 1. Recent data show that eEF2K helps to protect cancer cells against nutrient starvation and is also cytoprotective in other settings, including hypoxia. Growing evidence points to roles for eEF2K in neurological processes such as learning and memory and perhaps in depression.
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Affiliation(s)
- Justin W Kenney
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Claire E Moore
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Xuemin Wang
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Christopher G Proud
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK.
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Sumi K, Higashi S, Natsume M, Kawahata K, Nakazato K. Temporal changes in ERK phosphorylation are harmonious with 4E-BP1, but not p70S6K, during clenbuterol-induced hypertrophy in the rat gastrocnemius. Appl Physiol Nutr Metab 2014; 39:902-10. [PMID: 24941107 DOI: 10.1139/apnm-2013-0431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Extracellular signal-regulated kinase (ERK) is required for clenbuterol (CB)-dependent fast-type myofibril enlargement; however, its contribution to translation control is unclear. ERK mediates translational regulation through mammalian target of rapamycin complex 1 (mTORC1) activation and (or) mTORC1-independent pathways. In this study, we aimed to investigate the role of ERK in translational control during CB-induced muscular hypertrophy by measuring time-dependent changes in the phosphorylation statuses of ERK, p70 ribosomal S6 kinase (p70S6K; an indicator of mTORC1 activity), 4E-binding protein 1 (4E-BP1), eukaryotic elongation factor 2 (eEF2), and other related signaling molecules in rat gastrocnemius muscles. Five-day administration of CB induced phenotypes associated with muscular hypertrophy (significant increases in wet weight and isometric ankle flexion torque in the gastrocnemius muscle), but was not accompanied by elevated ERK or p70S6K phosphorylation. One-day administration of CB caused significant increases in the phosphorylation of ERK, p70S6K, and 4E-BP1. In contrast, 3-day administration of CB caused significant increases in the phosphorylation of ERK and 4E-BP1, but not p70S6K. In addition, positive correlations were observed between ERK and 4E-BP1 on days 1 and 3, whereas a correlation between ERK and p70S6K was only observed on day 1. eEF2 phosphorylation was unchanged on both days 1 and 3. These findings suggest that ERK accelerates the initiation of translation, but does not support the involvement of ERK in translational elongation. Furthermore, ERK may play a major role in promoting translational initiation by mediating the phosphorylation of 4E-BP1, and may contribute to the initial activation of mTORC1 during CB administration.
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Affiliation(s)
- Koichiro Sumi
- a Food Science Research Laboratories, R&D Division, Meiji Co., Ltd. 540 Naruda, Odawara, 540 Naruda, Odawara, Kanagawa 250-0862, Japan
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de Oliveira GP, Maximino JR, Maschietto M, Zanoteli E, Puga RD, Lima L, Carraro DM, Chadi G. Early gene expression changes in skeletal muscle from SOD1(G93A) amyotrophic lateral sclerosis animal model. Cell Mol Neurobiol 2014; 34:451-62. [PMID: 24442855 DOI: 10.1007/s10571-014-0029-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/07/2014] [Indexed: 02/07/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by loss of motor neurons. Familial ALS is strongly associated to dominant mutations in the gene for Cu/Zn superoxide dismutase (SOD1). Recent evidences point to skeletal muscle as a primary target in the ALS mouse model. Wnt/PI3 K signaling pathways and epithelial-mesenchymal transition (EMT) have important roles in maintenance and repair of skeletal muscle. Wnt/PI3 K pathways and EMT gene expression profile were investigated in gastrocnemius muscle from SOD1(G93A) mouse model and age-paired wild-type control in the presymptomatic ages of 40 and 80 days aiming the early neuromuscular abnormalities that precede motor neuron death in ALS. A customized cDNA microarray platform containing 326 genes of Wnt/PI3 K and EMT was used and results revealed eight up-regulated (Loxl2, Pik4ca, Fzd9, Cul1, Ctnnd1, Snf1lk, Prkx, Dner) and nine down-regulated (Pik3c2a, Ripk4, Id2, C1qdc1, Eif2ak2, Rac3, Cds1, Inppl1, Tbl1x) genes at 40 days, and also one up-regulated (Pik3ca) and five down-regulated (Cd44, Eef2 k, Fzd2, Crebbp, Piki3r1) genes at 80 days. Also, protein-protein interaction networks grown from the differentially expressed genes of 40 and 80 days old mice have identified Grb2 and Src genes in both presymptomatic ages, thus playing a potential central role in the disease mechanisms. mRNA and protein levels for Grb2 and Src were found to be increased in 80 days old ALS mice. Gene expression changes in the skeletal muscle of transgenic ALS mice at presymptomatic periods of disease gave further evidence of early neuromuscular abnormalities that precede motor neuron death. The results were discussed in terms of initial triggering for neuronal degeneration and muscle adaptation to keep function before the onset of symptoms.
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Affiliation(s)
- Gabriela P de Oliveira
- Neuroregeneration Center, Department of Neurology, University of São Paulo School of Medicine, Av. Dr. Arnaldo, 455, 2nd Floor, Room 2119, São Paulo, 01246-903, Brazil
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