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Engström Ruud L, Font-Gironès F, Zajdel J, Kern L, Teixidor-Deulofeu J, Mannerås-Holm L, Carreras A, Becattini B, Björefeldt A, Hanse E, Fenselau H, Solinas G, Brüning JC, Wunderlich TF, Bäckhed F, Ruud J. Activation of GFRAL + neurons induces hypothermia and glucoregulatory responses associated with nausea and torpor. Cell Rep 2024; 43:113960. [PMID: 38507407 DOI: 10.1016/j.celrep.2024.113960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/11/2024] [Accepted: 02/28/2024] [Indexed: 03/22/2024] Open
Abstract
GFRAL-expressing neurons actuate aversion and nausea, are targets for obesity treatment, and may mediate metformin effects by long-term GDF15-GFRAL agonism. Whether GFRAL+ neurons acutely regulate glucose and energy homeostasis is, however, underexplored. Here, we report that cell-specific activation of GFRAL+ neurons using a variety of techniques causes a torpor-like state, including hypothermia, the release of stress hormones, a shift from glucose to lipid oxidation, and impaired insulin sensitivity, glucose tolerance, and skeletal muscle glucose uptake but augmented glucose uptake in visceral fat. Metabolomic analysis of blood and transcriptomics of muscle and fat indicate alterations in ketogenesis, insulin signaling, adipose tissue differentiation and mitogenesis, and energy fluxes. Our findings indicate that acute GFRAL+ neuron activation induces endocrine and gluco- and thermoregulatory responses associated with nausea and torpor. While chronic activation of GFRAL signaling promotes weight loss in obesity, these results show that acute activation of GFRAL+ neurons causes hypothermia and hyperglycemia.
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Affiliation(s)
- Linda Engström Ruud
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ferran Font-Gironès
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Joanna Zajdel
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lara Kern
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Júlia Teixidor-Deulofeu
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Louise Mannerås-Holm
- Department of Molecular and Clinical Medicine, The Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Alba Carreras
- Department of Molecular and Clinical Medicine, The Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Barbara Becattini
- Department of Molecular and Clinical Medicine, The Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Andreas Björefeldt
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eric Hanse
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | | | - Giovanni Solinas
- Department of Molecular and Clinical Medicine, The Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jens C Brüning
- Max Planck Institute for Metabolism Research, Cologne, Germany
| | | | - Fredrik Bäckhed
- Department of Molecular and Clinical Medicine, The Wallenberg Laboratory, Institute of Medicine, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Clinical Physiology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Johan Ruud
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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2
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Rodrigues Junior CF, Murata GM, Gerlinger-Romero F, Nachbar RT, Marzuca-Nassr GN, Gorjão R, Vitzel KF, Hirabara SM, Pithon-Curi TC, Curi R. Changes in Skeletal Muscle Protein Metabolism Signaling Induced by Glutamine Supplementation and Exercise. Nutrients 2023; 15:4711. [PMID: 38004105 PMCID: PMC10674901 DOI: 10.3390/nu15224711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
AIM To evaluate the effects of resistance exercise training (RET) and/or glutamine supplementation (GS) on signaling protein synthesis in adult rat skeletal muscles. METHODS The following groups were studied: (1) control, no exercise (C); (2) exercise, hypertrophy resistance exercise training protocol (T); (3) no exercise, supplemented with glutamine (G); and (4) exercise and supplemented with glutamine (GT). The rats performed hypertrophic training, climbing a vertical ladder with a height of 1.1 m at an 80° incline relative to the horizontal with extra weights tied to their tails. The RET was performed three days a week for five weeks. Each training session consisted of six ladder climbs. The extra weight load was progressively increased for each animal during each training session. The G groups received daily L-glutamine by gavage (one g per kilogram of body weight per day) for five weeks. The C group received the same volume of water during the same period. The rats were euthanized, and the extensor digitorum longus (EDL) muscles from both hind limbs were removed and immediately weighed. Glutamine and glutamate concentrations were measured, and histological, signaling protein contents, and mRNA expression analyses were performed. RESULTS Supplementation with free L-glutamine increased the glutamine concentration in the EDL muscle in the C group. The glutamate concentration was augmented in the EDL muscles from T rats. The EDL muscle mass did not change, but a significant rise was reported in the cross-sectional area (CSA) of the fibers in the three experimental groups. The levels of the phosphorylated proteins (pAkt/Akt, pp70S6K/p70S6K, p4E-BP1/4E-BP1, and pS6/S6 ratios) were significantly increased in EDL muscles of G rats, and the activation of p4E-BP1 was present in T rats. The fiber CSAs of the EDL muscles in T, G, and GT rats were increased compared to the C group. These changes were accompanied by a reduction in the 26 proteasome activity of EDL muscles from T rats. CONCLUSION Five weeks of GS and/or RET induced muscle hypertrophy, as indicated by the increased CSAs of the EDL muscle fibers. The increase in CSA was mediated via the upregulated phosphorylation of Akt, 4E-BP1, p70S6k, and S6 in G animals and 4E-BP1 in T animals. In the EDL muscles from T animals, a decrease in proteasome activity, favoring a further increase in the CSA of the muscle fibers, was reported.
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Affiliation(s)
- Carlos Flores Rodrigues Junior
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
| | - Gilson Masahiro Murata
- Divisions of Nephrology and Molecular Medicine, LIM-29, Department of Medicine, University of São Paulo, São Paulo 05508-220, Brazil;
| | | | - Renato Tadeu Nachbar
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
| | - Gabriel Nasri Marzuca-Nassr
- Departamento de Ciencias de la Rehabilitación, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile;
- Interuniversity Center for Healthy Aging (Code RED21993), Talca 3460000, Chile
| | - Renata Gorjão
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Kaio Fernando Vitzel
- School of Health Sciences, Massey University (University of New Zealand), Auckland 0745, New Zealand;
| | - Sandro Massao Hirabara
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Tania Cristina Pithon-Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-220, Brazil; (C.F.R.J.); (T.C.P.-C.); (R.C.)
- Interdisciplinary Post-graduate Program in Health Sciences, Universidade Cruzeiro do Sul, São Paulo 01506-000, Brazil;
- Butantan Institute, São Paulo 05585-000, Brazil
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3
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Dombrecht D, Van Daele U, Van Asbroeck B, Schieffelers DR, Guns PJ, van Breda E. Skeletal muscle wasting after burn is regulated by a decrease in anabolic signaling in the early flow phase. Burns 2023; 49:1574-1584. [PMID: 37833149 DOI: 10.1016/j.burns.2023.08.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/14/2023] [Accepted: 08/10/2023] [Indexed: 10/15/2023]
Abstract
Following burns a sustained catabolic stress response is activated, resulting in skeletal muscle wasting. A better understanding of the underlying mechanisms of postburn skeletal muscle wasting is essential for the development of preventive and/or therapeutic strategies. Six weeks old female rats underwent a sham, 10% or 40% total body surface area scald burn. Ten days post-injury, severely burned animals gained significantly less weight compared to sham treated and minor burned animals, reflected in a significantly lower ratio of muscle to total body weight for Soleus (SOL) and Extensor Digitorum Longus (EDL) in the severely burned group. Postburn, total fiber number was significantly lower in EDL, while in SOL the amount of type1 fibers significantly increased and type2 fibers significantly decreased. No signs of mitochondrial dysfunction (COX/SDH) or apoptosis (caspase-3) were found. In SOL and EDL, eEF2 and pAKT expression was significantly lower after severe burn. MURF1,2,3 and Atrogin-1 was significantly higher in SOL, whilst in EDL MURF1,2,3 was significantly lower postburn. In both muscles, FOXO3A was significantly lower postburn. This study identified postburn changes in muscle anthropomorphology and proteins involved in pathways regulating protein synthesis and breakdown, with more pronounced catabolic effects in SOL.
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Affiliation(s)
- Dorien Dombrecht
- Department of Rehabilitation Sciences & Physiotherapy, Research Group MOVANT, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
| | - Ulrike Van Daele
- Department of Rehabilitation Sciences & Physiotherapy, Research Group MOVANT, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium; Oscare, Organisation for Burns, Scar After-Care and Research, 2170 Antwerp, Belgium.
| | - Birgit Van Asbroeck
- Department of Rehabilitation Sciences & Physiotherapy, Research Group MOVANT, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
| | - David R Schieffelers
- Department of Rehabilitation Sciences & Physiotherapy, Research Group MOVANT, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
| | - Pieter-Jan Guns
- Laboratory of Physiopharmacology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium
| | - Eric van Breda
- Department of Rehabilitation Sciences & Physiotherapy, Research Group MOVANT, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
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4
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Grunow JJ, Gan T, Lewald H, Martyn JAJ, Blobner M, Schaller SJ. Insulin signaling in skeletal muscle during inflammation and/or immobilisation. Intensive Care Med Exp 2023; 11:16. [PMID: 36967414 PMCID: PMC10040391 DOI: 10.1186/s40635-023-00503-9] [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: 11/20/2022] [Accepted: 02/20/2023] [Indexed: 03/28/2023] Open
Abstract
BACKGROUND The decline in the downstream signal transduction pathway of anabolic hormone, insulin, could play a key role in the muscle atrophy and insulin resistance observed in patients with intensive care unit acquired weakness (ICUAW). This study investigated the impact of immobilisation via surgical knee and ankle fixation and inflammation via Corynebacterium parvum injection, alone and in combination, as risk factors for altering insulin transduction and, therefore, their role in ICUAW. RESULTS Muscle weight was significantly decreased due to immobilisation [estimated effect size (95% CI) - 0.10 g (- 0.12 to - 0.08); p < 0.001] or inflammation [estimated effect size (95% CI) - 0.11 g (- 0.13 to - 0.09); p < 0.001] with an additive effect of both combined (p = 0.024). pAkt was only detectable after insulin stimulation [estimated effect size (95% CI) 85.1-fold (76.2 to 94.0); p < 0.001] irrespective of the group and phosphorylation was not impaired by the different perturbations. Nevertheless, the phosphorylation of GSK3 observed in the control group after insulin stimulation was decreased in the immobilisation [estimated effect size (95% CI) - 40.2 (- 45.6 to - 34.8)] and inflammation [estimated effect size (95% CI) - 55.0 (- 60.4 to - 49.5)] groups. The expression of phosphorylated GS (pGS) was decreased after insulin stimulation in the control group and significantly increased in the immobilisation [estimated effect size (95% CI) 70.6-fold (58.8 to 82.4)] and inflammation [estimated effect size (95% CI) 96.7 (85.0 to 108.5)] groups. CONCLUSIONS Both immobilisation and inflammation significantly induce insulin resistance, i.e., impair the insulin signaling pathway downstream of Akt causing insufficient GSK phosphorylation and, therefore, its activation which caused increased glycogen synthase phosphorylation, which could contribute to muscle atrophy of immobilisation and inflammation.
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Affiliation(s)
- Julius J Grunow
- Charité - Universitätsmedizin Berlin, corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Anesthesiology and Operative Intensive Care Medicine (CVK, CCM), Charitéplatz 1, 10117, Berlin, Germany
| | - Thomas Gan
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Anesthesiology and Intensive Care, Ismaninger Straße 22, 81675, Munich, Bavaria, Germany
| | - Heidrun Lewald
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Anesthesiology and Intensive Care, Ismaninger Straße 22, 81675, Munich, Bavaria, Germany
| | - J A Jeevendra Martyn
- Department of Anaesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children®-Boston, and Harvard Medical School, 51 Blossom Street, Room 206, Boston, 02114, MA, USA
| | - Manfred Blobner
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Anesthesiology and Intensive Care, Ismaninger Straße 22, 81675, Munich, Bavaria, Germany
| | - Stefan J Schaller
- Charité - Universitätsmedizin Berlin, corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Anesthesiology and Operative Intensive Care Medicine (CVK, CCM), Charitéplatz 1, 10117, Berlin, Germany.
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Anesthesiology and Intensive Care, Ismaninger Straße 22, 81675, Munich, Bavaria, Germany.
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5
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Mendes S, Leal DV, Baker LA, Ferreira A, Smith AC, Viana JL. The Potential Modulatory Effects of Exercise on Skeletal Muscle Redox Status in Chronic Kidney Disease. Int J Mol Sci 2023; 24:ijms24076017. [PMID: 37046990 PMCID: PMC10094245 DOI: 10.3390/ijms24076017] [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: 02/15/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 04/14/2023] Open
Abstract
Chronic Kidney Disease (CKD) is a global health burden with high mortality and health costs. CKD patients exhibit lower cardiorespiratory and muscular fitness, strongly associated with morbidity/mortality, which is exacerbated when they reach the need for renal replacement therapies (RRT). Muscle wasting in CKD has been associated with an inflammatory/oxidative status affecting the resident cells' microenvironment, decreasing repair capacity and leading to atrophy. Exercise may help counteracting such effects; however, the molecular mechanisms remain uncertain. Thus, trying to pinpoint and understand these mechanisms is of particular interest. This review will start with a general background about myogenesis, followed by an overview of the impact of redox imbalance as a mechanism of muscle wasting in CKD, with focus on the modulatory effect of exercise on the skeletal muscle microenvironment.
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Affiliation(s)
- Sara Mendes
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University of Maia, 4475-690 Maia, Portugal
| | - Diogo V Leal
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University of Maia, 4475-690 Maia, Portugal
| | - Luke A Baker
- Leicester Kidney Lifestyle Team, Department of Health Sciences, University of Leicester, Leicester LE1 7RH, UK
| | - Aníbal Ferreira
- Nova Medical School, 1169-056 Lisbon, Portugal
- NephroCare Portugal SA, 1750-233 Lisbon, Portugal
| | - Alice C Smith
- Leicester Kidney Lifestyle Team, Department of Health Sciences, University of Leicester, Leicester LE1 7RH, UK
| | - João L Viana
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University of Maia, 4475-690 Maia, Portugal
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6
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Dombrecht D, Van Daele U, Van Asbroeck B, Schieffelers D, Guns PJ, Gebruers N, Meirte J, van Breda E. Molecular mechanisms of post-burn muscle wasting and the therapeutic potential of physical exercise. J Cachexia Sarcopenia Muscle 2023; 14:758-770. [PMID: 36760077 PMCID: PMC10067483 DOI: 10.1002/jcsm.13188] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/03/2023] [Accepted: 01/16/2023] [Indexed: 02/11/2023] Open
Abstract
After a severe burn injury, a systemic stress response activates metabolic and inflammatory derangements that, among other, leads to muscle mass loss (muscle wasting). These negative effects on skeletal muscle continue for several months or years and are aggravated by short-term and long-term disuse. The dynamic balance between muscle protein synthesis and muscle protein breakdown (proteolysis) is regulated by complex signalling pathways that leads to an overall negative protein balance in skeletal muscle after a burn injury. Research concerning these molecular mechanisms is still scarce and inconclusive, understanding of which, if any, molecular mechanisms contribute to muscle wasting is of fundamental importance in designing of therapeutic interventions for burn patients as well. This review not only summarizes our present knowledge of the molecular mechanisms that underpin muscle protein balance but also summarizes the effects of exercise on muscle wasting post-burn as promising strategy to counteract the detrimental effects on skeletal muscle. Future research focusing on the pathways causing post-burn muscle wasting and the different effects of exercise on them is needed to confirm this hypothesis and to lay the foundation of therapeutic strategies.
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Affiliation(s)
- Dorien Dombrecht
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium
| | - Ulrike Van Daele
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium.,Oscare, Organisation for Burns, Scar After-Care and Research, Antwerp, Belgium
| | - Birgit Van Asbroeck
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium
| | - David Schieffelers
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium
| | - Pieter-Jan Guns
- Laboratory of Physiopharmacology, University of Antwerp, Antwerp, Belgium
| | - Nick Gebruers
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium.,Multidisciplinary Edema Clinic, Antwerp University Hospital, Edegem, Belgium
| | - Jill Meirte
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium.,Oscare, Organisation for Burns, Scar After-Care and Research, Antwerp, Belgium
| | - Eric van Breda
- Department of Rehabilitation Sciences & Physiotherapy, Research group MOVANT, Multidisciplinary Metabolic Research Unit (M2RUN), University of Antwerp, Antwerp, Belgium
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7
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Martyn JAJ, Sparling JL, Bittner EA. Molecular mechanisms of muscular and non-muscular actions of neuromuscular blocking agents in critical illness: a narrative review. Br J Anaesth 2023; 130:39-50. [PMID: 36175185 DOI: 10.1016/j.bja.2022.08.009] [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: 04/11/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 01/05/2023] Open
Abstract
Despite frequent use of neuromuscular blocking agents in critical illness, changes in neuromuscular transmission with critical illness are not well appreciated. Recent studies have provided greater insights into the molecular mechanisms for beneficial muscular effects and non-muscular anti-inflammatory properties of neuromuscular blocking agents. This narrative review summarises the normal structure and function of the neuromuscular junction and its transformation to a 'denervation-like' state in critical illness, the underlying cause of aberrant neuromuscular blocking agent pharmacology. We also address the important favourable and adverse consequences and molecular bases for these consequences during neuromuscular blocking agent use in critical illness. This review, therefore, provides an enhanced understanding of clinical therapeutic effects and novel pathways for the salutary and aberrant effects of neuromuscular blocking agents when used during acquired pathologic states of critical illness.
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Affiliation(s)
- J A Jeevendra Martyn
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Shriners Hospitals for Children, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Jamie L Sparling
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
| | - Edward A Bittner
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Shriners Hospitals for Children, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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8
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Kübler IC, Kretzschmar J, Brankatschk M, Sandoval-Guzmán T. Local problems need global solutions - the metabolic needs of regenerating organisms. Wound Repair Regen 2022; 30:652-664. [PMID: 35596643 DOI: 10.1111/wrr.13029] [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: 01/31/2022] [Revised: 05/03/2022] [Accepted: 05/19/2022] [Indexed: 12/01/2022]
Abstract
The vast majority of species that belong to the plant or animal kingdom evolved with two main strategies to counter tissue damage - scar formation and regeneration. Whereas scar formation provides a fast and cost-effective repair to exit life-threatening conditions, complete tissue regeneration is time-consuming and requires vast resources to reinstall functionality of affected organs or structures. Local environments in wound healing are widely studied and findings have provided important biomedical applications. Less well understood are organismic physiological parameters and signaling circuits essential to maintain effective tissue repair. Here, we review accumulated evidence that positions the interplay of local and systemic changes in metabolism as essential variables modulating the injury response. We particularly emphasize the role of lipids and lipid-like molecules as significant components long overlooked. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ines C Kübler
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Germany
| | - Jenny Kretzschmar
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Marko Brankatschk
- Department of Molecular, Cell and Developmental Biology, Technische Universität Dresden, Germany
| | - Tatiana Sandoval-Guzmán
- Department of Internal Medicine III, Center for Healthy Aging, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden of Helmholtz Centre Munich, at University Clinic Carl Gustav Carus, TU Dresden Faculty of Medicine, Dresden, Germany
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9
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Cadaret CN, Posont RJ, Swanson RM, Beard JK, Gibbs RL, Barnes TL, Marks-Nelson ES, Petersen JL, Yates DT. Intermittent maternofetal oxygenation during late gestation improved birthweight, neonatal growth, body symmetry, and muscle metabolism in intrauterine growth-restricted lambs. J Anim Sci 2022; 100:6453369. [PMID: 34865027 DOI: 10.1093/jas/skab358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/30/2021] [Indexed: 02/05/2023] Open
Abstract
In humans and animals, intrauterine growth restriction (IUGR) results from fetal programming responses to poor intrauterine conditions. Chronic fetal hypoxemia elevates circulating catecholamines, which reduces skeletal muscle β2 adrenoceptor content and contributes to growth and metabolic pathologies in IUGR-born offspring. Our objective was to determine whether intermittent maternofetal oxygenation during late gestation would improve neonatal growth and glucose metabolism in IUGR-born lambs. Pregnant ewes were housed at 40 °C from the 40th to 95th day of gestational age (dGA) to produce IUGR-born lambs (n = 9). A second group of IUGR-born lambs received prenatal O2 supplementation via maternal O2 insufflation (100% humidified O2, 10 L/min) for 8 h/d from dGA 130 to parturition (IUGR+O2, n = 10). Control lambs (n = 15) were from pair-fed thermoneutral ewes. All lambs were weaned at birth, hand-reared, and fitted with hindlimb catheters at day 25. Glucose-stimulated insulin secretion (GSIS) and hindlimb hyperinsulinemic-euglycemic clamp (HEC) studies were performed at days 28 and 29, respectively. At day 30, lambs were euthanized and ex vivo HEC studies were performed on isolated muscle. Without maternofetal oxygenation, IUGR lambs were 40% lighter (P < 0.05) at birth and maintained slower (P < 0.05) growth rates throughout the neonatal period compared with controls. At 30 d of age, IUGR lambs had lighter (P < 0.05) hindlimbs and flexor digitorum superficialis (FDS) muscles. IUGR+O2 lambs exhibited improved (P < 0.05) birthweight, neonatal growth, hindlimb mass, and FDS mass compared with IUGR lambs. Hindlimb insulin-stimulated glucose utilization and oxidation rates were reduced (P < 0.05) in IUGR but not IUGR+O2 lambs. Ex vivo glucose oxidation rates were less (P < 0.05) in muscle from IUGR but not IUGR+O2 lambs. Surprisingly, β2 adrenoceptor content and insulin responsiveness were reduced (P < 0.05) in muscle from IUGR and IUGR+O2 lambs compared with controls. In addition, GSIS was reduced (P < 0.05) in IUGR lambs and only modestly improved (P < 0.05) in IUGR+O2. Insufflation of O2 also increased (P < 0.05) acidosis and hypercapnia in dams, perhaps due to the use of 100% O2 rather than a gas mixture with a lesser O2 percentage. Nevertheless, these findings show that intermittent maternofetal oxygenation during late gestation improved postnatal growth and metabolic outcomes in IUGR lambs without improving muscle β2 adrenoceptor content.
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Affiliation(s)
- Caitlin N Cadaret
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Robert J Posont
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Rebecca M Swanson
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Joslyn K Beard
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Rachel L Gibbs
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Taylor L Barnes
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | | | - Jessica L Petersen
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Dustin T Yates
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583
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10
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Knuth CM, Auger C, Jeschke MG. Burn-induced hypermetabolism and skeletal muscle dysfunction. Am J Physiol Cell Physiol 2021; 321:C58-C71. [PMID: 33909503 DOI: 10.1152/ajpcell.00106.2021] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Critical illnesses, including sepsis, cancer cachexia, and burn injury, invoke a milieu of systemic metabolic and inflammatory derangements that ultimately results in increased energy expenditure leading to fat and lean mass catabolism. Burn injuries present a unique clinical challenge given the magnitude and duration of the hypermetabolic response compared with other forms of critical illness, which drastically increase the risk of morbidity and mortality. Skeletal muscle metabolism is particularly altered as a consequence of burn-induced hypermetabolism, as it primarily provides a main source of fuel in support of wound healing. Interestingly, muscle catabolism is sustained long after the wound has healed, indicating that additional mechanisms beyond wound healing are involved. In this review, we discuss the distinctive pathophysiological response to burn injury with a focus on skeletal muscle function and metabolism. We first examine the diverse consequences on skeletal muscle dysfunction between thermal, electrical, and chemical burns. We then provide a comprehensive overview of the known mechanisms underlying skeletal muscle dysfunction that may be attributed to hypermetabolism. Finally, we review the most promising current treatment options to mitigate muscle catabolism, and by extension improve morbidity and mortality, and end with future directions that have the potential to significantly improve patient care.
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Affiliation(s)
- Carly M Knuth
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Christopher Auger
- Department of Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Marc G Jeschke
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada.,Department of Immunology, University of Toronto, Toronto, Ontario, Canada.,Ross Tilley Burn Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
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11
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Affiliation(s)
- J A Jeevendra Martyn
- From the Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Massachusetts General Hospital, and the Research Center, Shriners Hospitals for Children - all in Boston
| | - Masao Kaneki
- From the Department of Anesthesia, Critical Care, and Pain Medicine, Harvard Medical School, Massachusetts General Hospital, and the Research Center, Shriners Hospitals for Children - all in Boston
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12
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Emery MA, Eitan S. Drug-specific differences in the ability of opioids to manage burn pain. Burns 2019; 46:503-513. [PMID: 31859093 DOI: 10.1016/j.burns.2019.03.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 03/04/2019] [Accepted: 03/30/2019] [Indexed: 12/17/2022]
Abstract
Burn injury pain is a significant public health problem. Burn injury treatment has improved tremendously in recent decades. However, an unintended consequence is that a larger number of patients now survive more severe injuries, and face intense pain that is very hard to treat. Although many efforts have been made to find alternative treatments, opioids remain the most effective medication available. Burn patients are frequently prescribed opioids in doses and durations that are significantly higher and longer than standard analgesic dosing guidelines. Despite this, many continue to experience unrelieved pain. They are also placed at a higher risk for developing dependence and opioid use disorder. Burn injury profoundly alters the functional state of the immune system. It also alters the expression levels of receptor, effector, and signaling molecules within the spinal cord's dorsal horn. These alterations could explain the reduced potency of opioids. However, recent studies demonstrate that different opioids signal preferentially via differential signaling pathways. This ligand-specific signaling by different opioids implies that burn injury may reduce the antinociceptive potency of opioids to different degrees, in a drug-specific manner. Indeed, recent findings hint at drug-specific differences in the ability of opioids to manage burn pain early after injury, as well as differences in their ability to prevent or treat the development of chronic and neuropathic pain. Here we review the current state of opioid treatment, as well as new findings that could potentially lead to opioid-based pain management strategies that may be significantly more effective than the current solutions.
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Affiliation(s)
- Michael A Emery
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), USA
| | - Shoshana Eitan
- Behavioral and Cellular Neuroscience, Department of Psychological and Brain Sciences, Texas A&M University, 4235 TAMU, College Station, TX 77843, USA; Interdisciplinary Program in Neuroscience, Texas A&M Institute for Neuroscience (TAMIN), USA.
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13
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14
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Kim JH, Park SJ, Chae U, Seong J, Lee HS, Lee SR, Lee S, Lee DS. Peroxiredoxin 2 mediates insulin sensitivity of skeletal muscles through regulation of protein tyrosine phosphatase oxidation. Int J Biochem Cell Biol 2018; 99:80-90. [PMID: 29605633 DOI: 10.1016/j.biocel.2018.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/07/2018] [Accepted: 03/27/2018] [Indexed: 01/14/2023]
Abstract
Insulin signaling is essential for regulating glucose homeostasis. Numerous studies have demonstrated that reactive oxygen species (ROS) affect insulin signaling, and low ROS levels can act as a signal to regulate cellular function. Peroxiredoxins (Prxs) are highly abundant and widely expressed antioxidant enzymes. However, it is unclear whether antioxidant enzymes, such as Prx2, mediate insulin signaling. The aim of our study was to investigate the influence of Prx2 deficiency on insulin signaling. Our western blot results showed that Prx2 deficiency enhanced insulin signaling and increased oxidation of protein tyrosine phosphatase 1B (PTP1B) and phosphatase and tensin homologue (PTEN) in mouse embryonic fibroblasts (MEFs) treated with insulin. In addition, we assessed ROS levels with a Cytosol-HyPer H2O2 sensor. As a result, increased ROS levels and Akt activation were decreased by N-acetyl-cysteine (Nac), which acted as an antioxidant in Prx2-deficient MEFs. Body weight measurements and glucose tolerance test (GTT) revealed significant body weight reduction and increase in glucose clearance in Prx2-/- mice fed a high-fat diet. Interestingly, glucose transporter type 4 (GLUT4) was significantly higher in Prx2-/- mice than in wild-type mice according to western blotting results. Western blotting also revealed that Akt phosphorylation was higher in Prx2-/- MEFs and muscle tissue than in wild-type. Together, our findings indicate that increased ROS due to Prx2 deficiency promotes insulin sensitivity and glucose clearance in skeletal muscles by increasing protein tyrosine phosphatase (PTPs) oxidation. These results provide novel insights into the fundamental mechanisms of insulin signaling induced by Prx2 deficiency and suggest that ROS-based therapeutic strategies can be used to suppress insulin resistance.
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Affiliation(s)
- Jung-Hak Kim
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Division of Endocrinology, Internal Medicine, University of California, Davis, CA, 95616, USA
| | - Sun-Ji Park
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea; Renal Division, School of Medicine, Washington University in St. Louis, MO, 63130, USA
| | - Unbin Chae
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Joongbae Seong
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Hyun-Shik Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Sang-Rae Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Chungcheongbuk-do, 34141, Republic of Korea
| | - Seunghoon Lee
- Animal Biotechnology Division, National Institute of Animal Science, Jeollabuk-do, 55365, Republic of Korea
| | - Dong-Seok Lee
- School of Life Sciences and Biotechnology, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 41566, Republic of Korea.
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15
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Screening of Key Genes in Severe Burn Injury at Different Stages via Analyzing Gene Expression Data. J Burn Care Res 2018; 37:e254-62. [PMID: 25412053 DOI: 10.1097/bcr.0000000000000179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Microarray analysis was performed to investigate the changes in gene expression profiles after severe burn injury at the early and middle stages, further discovering therapeutic targets for severe burn injury. Microarray data (GSE19743) were downloaded from Gene Expression Omnibus. First, differentially expressed genes (DEGs) at different stages were screened using limma package. Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs were then performed using DAVID. Protein-protein interaction (PPI) networks were also constructed using String database. Additionally, transcription factor binding site was detected using the Whole-Genome rVISTA. Compared with the healthy controls, 160 DEGs were identified in patients with early-stage burn injury and 261 DEGs were obtained in patients with middle-stage burn injury. Only 10 genes showed differential expression between the early and middle stages. KEGG functional analysis indicated that DEGs detected at the early stage were mainly enriched in the immune response, kinase activity, and signaling pathways and DEGs detected at the middle stage were involved in the immune response, protein and fat metabolism, and programmed cell death pathways. Three PPI networks were constructed and hub proteins with high degrees of connection were screened, such as lactotransferrin, interleukin 8, and perforin-1. Additionally, many transcription factor binding sites that may be involved in the regulation of these DEGs were also detected. A number of DEGs were identified in patients with early- and middle-stage burn injury, which helps to deepen the understanding about the molecular mechanism underlying severe burn injury.
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Prevention of Burn-Induced Inflammatory Responses and Muscle Wasting by GTS-21, a Specific Agonist for α7 Nicotinic Acetylcholine Receptors. Shock 2018; 47:61-69. [PMID: 27529131 DOI: 10.1097/shk.0000000000000729] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Muscle wasting (MW) in catabolic conditions (e.g., burn injury [BI]) is a major risk factor affecting prognosis. Activation of interleukin-1β (IL-1β)/nuclear factor-kappa B (NF-κB), interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3), and/or forkhead box O transcriptional factor (FOXO)-mediated gene transcription pathways is the pivotal trigger of inflammatory response-induced protein catabolic processes in muscle. The α7 acetylcholine receptors (α7AChRs) are upregulated in macrophages and peripheral tissues including skeletal muscle during MW conditions. Stimulation of α7AChRs mitigates inflammatory responses. Hypothesis tested is that attenuation of inflammation by α7AChR stimulation with specific α7AChR agonist, GTS-21, will reverse BI-induced body mass and MW by modulating inflammatory and proteolytic signals. METHODS Body surface area (30%) BI or sham BI mice were treated with GTS-21 or saline. Tibialis anterior (TA) muscle was harvested at 6 h, day 1 or 3 to examine inflammatory and proteolytic signals. RESULTS GTS-21 significantly ameliorated the BI-induced increased expression of inflammatory cytokines IL-6, IL-1β, C-X-C motif chemokine ligand 2 (6 h), phosphorylated STAT3, and NF-κB (day 1) in TA muscle. GTS-21 also significantly inhibited BI-induced increase of MuRF1 and FOXO1 (day 1). Consistent with the cytokine and inflammatory mediator changes, BI-induced body weight and TA muscle mass loss at day 3 were mitigated by GTS-21 treatment. The beneficial effect of GTS-21 on BI changes was absent in methyllycaconitine (α7AChR antagonist)-treated wild-type and α7AChR knockout mice. CONCLUSION GTS-21 stimulation of α7AChRs, by modulating multiple molecular signals related to inflammation and proteolysis, attenuates protein wasting, evidenced by maintenance of body weight and attenuation of distant muscle mass loss after BI. GTS-21 can be a novel, potent therapeutic option for reversal of BI-induced MW.
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17
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Dunn JLM, Kartchner LB, Gast K, Sessions M, Hunter RA, Thurlow L, Richardson A, Schoenfisch M, Cairns BA, Maile R. Mammalian target of rapamycin regulates a hyperresponsive state in pulmonary neutrophils late after burn injury. J Leukoc Biol 2018; 103:909-918. [PMID: 29393976 DOI: 10.1002/jlb.3ab0616-251rrr] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 12/28/2017] [Accepted: 01/04/2018] [Indexed: 12/11/2022] Open
Abstract
Bacterial pneumonia is a leading cause of death late after burn injury due to the severe immune dysfunction that follows this traumatic injury. The Mechanistic/Mammalian Target of Rapamycin (mTOR) pathway drives many effector functions of innate immune cells required for bacterial clearance. Studies have demonstrated alterations in multiple cellular processes in patients and animal models following burn injury in which mTOR is a central component. Goals of this study were to (1) investigate the importance of mTOR signaling in antimicrobial activity by neutrophils and (2) therapeutically target mTOR to promote normalization of the immune response. We utilized a murine model of 20% total body surface area burn and the mTOR-specific inhibitor rapamycin. Burn injury led to innate immune hyperresponsiveness in the lung including recruitment of neutrophils with greater ex vivo oxidative activity compared with neutrophils from sham-injured mice. Elevated oxidative function correlated with improved clearance of Pseudomonas aeruginosa, despite down-regulated expression of the bacterial-sensing TLR molecules. Rapamycin administration reversed the burn injury-induced lung innate immune hyperresponsiveness and inhibited enhanced bacterial clearance in burn mice compared with untreated burn mice, resulting in significantly higher mortality. Neutrophil ex vivo oxidative burst was decreased by rapamycin treatment. These data indicate that (1) neutrophil function within the lung is more important than recruitment for bacterial clearance following burn injury and (2) mTOR inhibition significantly impacts innate immune hyperresponsiveness, including neutrophil effector function, allowing normalization of the immune response late after burn injury.
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Affiliation(s)
- Julia L M Dunn
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Laurel B Kartchner
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Karli Gast
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Marci Sessions
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rebecca A Hunter
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Lance Thurlow
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Anthony Richardson
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Mark Schoenfisch
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Bruce A Cairns
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Robert Maile
- Department of Microbiology & Immunology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Surgery, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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18
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Burn-induced muscle metabolic derangements and mitochondrial dysfunction are associated with activation of HIF-1α and mTORC1: Role of protein farnesylation. Sci Rep 2017; 7:6618. [PMID: 28747716 PMCID: PMC5529411 DOI: 10.1038/s41598-017-07011-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/21/2017] [Indexed: 12/28/2022] Open
Abstract
Metabolic derangements are a clinically significant complication of major trauma (e.g., burn injury) and include various aspects of metabolism, such as insulin resistance, muscle wasting, mitochondrial dysfunction and hyperlactatemia. Nonetheless, the molecular pathogenesis and the relation between these diverse metabolic alterations are poorly understood. We have previously shown that burn increases farnesyltransferase (FTase) expression and protein farnesylation and that FTase inhibitor (FTI) prevents burn-induced hyperlactatemia, insulin resistance, and increased proteolysis in mouse skeletal muscle. In this study, we found that burn injury activated mTORC1 and hypoxia-inducible factor (HIF)-1α, which paralleled dysfunction, morphological alterations (i.e., enlargement, partial loss of cristae structure) and impairment of respiratory supercomplex assembly of the mitochondria, and ER stress. FTI reversed or ameliorated all of these alterations in burned mice. These findings indicate that these burn-induced changes, which encompass various aspects of metabolism, may be linked to one another and require protein farnesylation. Our results provide evidence of involvement of the mTORC1-HIF-1α pathway in burn-induced metabolic derangements. Our study identifies protein farnesylation as a potential hub of the signaling network affecting multiple aspects of metabolic alterations after burn injury and as a novel potential molecular target to improve the clinical outcome of severely burned patients.
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19
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Bonifacio A, Sanvee GM, Brecht K, Kratschmar DV, Odermatt A, Bouitbir J, Krähenbühl S. IGF-1 prevents simvastatin-induced myotoxicity in C2C12 myotubes. Arch Toxicol 2016; 91:2223-2234. [PMID: 27734117 DOI: 10.1007/s00204-016-1871-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/06/2016] [Indexed: 12/18/2022]
Abstract
Statins are generally well tolerated, but treatment with these drugs may be associated with myopathy. The mechanisms of statin-associated myopathy are not completely understood. Statins inhibit AKT phosphorylation by an unclear mechanism, whereas insulin-like growth factor (IGF-1) activates the IGF-1/AKT signaling pathway and promotes muscle growth. The aims of the study were to investigate mechanisms of impaired AKT phosphorylation by simvastatin and to assess effects of IGF-1 on simvastatin-induced myotoxicity in C2C12 myotubes. C2C12 mouse myotubes were exposed to 10 μM simvastatin and/or 10 ng/mL IGF-1 for 18 h. Simvastatin inhibited the IGF-1/AKT signaling pathway, resulting in increased breakdown of myofibrillar proteins, impaired protein synthesis and increased apoptosis. Simvastatin inhibited AKT S473 phosphorylation, indicating reduced activity of mTORC2. In addition, simvastatin impaired stimulation of AKT T308 phosphorylation by IGF-1, indicating reduced activation of the IGF-1R/PI3K pathway by IGF-1. Nevertheless, simvastatin-induced myotoxicity could be at least partially prevented by IGF-1. The protective effects of IGF-1 were mediated by activation of the IGF-1R/AKT signaling cascade. Treatment with IGF-1 also suppressed muscle atrophy markers, restored protein synthesis and inhibited apoptosis. These results were confirmed by normalization of myotube morphology and protein content of C2C12 cells exposed to simvastatin and treated with IGF-1. In conclusion, impaired activity of AKT can be explained by reduced function of mTORC2 and of the IGF-1R/PI3K pathway. IGF-1 can prevent simvastatin-associated cytotoxicity and metabolic effects on C2C12 cells. The study gives insight into mechanisms of simvastatin-associated myotoxicity and provides potential targets for therapeutic intervention.
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Affiliation(s)
- Annalisa Bonifacio
- Division of Clinical Pharmacology and Toxicology, University Hospital, 4031, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Gerda M Sanvee
- Division of Clinical Pharmacology and Toxicology, University Hospital, 4031, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Karin Brecht
- Division of Clinical Pharmacology and Toxicology, University Hospital, 4031, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Denise V Kratschmar
- Division of Molecular and Systems Toxicology, University of Basel, Basel, Switzerland.,Swiss Centre of Applied Human Toxicology, Basel, Switzerland
| | - Alex Odermatt
- Division of Molecular and Systems Toxicology, University of Basel, Basel, Switzerland.,Swiss Centre of Applied Human Toxicology, Basel, Switzerland
| | - Jamal Bouitbir
- Division of Clinical Pharmacology and Toxicology, University Hospital, 4031, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland.,Swiss Centre of Applied Human Toxicology, Basel, Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology and Toxicology, University Hospital, 4031, Basel, Switzerland. .,Department of Biomedicine, University of Basel, Basel, Switzerland. .,Swiss Centre of Applied Human Toxicology, Basel, Switzerland.
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20
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Abstract
Carbohydrate, lipid, and protein metabolism are largely controlled by the interplay of various hormones, which includes those secreted by the pancreatic islets of Langerhans. While typically representing only 1% to 2% of the total pancreatic mass, the islets have a remarkable ability to adapt to disparate situations demanding a change in hormone release, such as peripheral insulin resistance. There are many different routes to the onset of insulin resistance, including obesity, lipodystrophy, glucocorticoid excess, and the chronic usage of atypical antipsychotic drugs. All of these situations are coupled to an increase in pancreatic islet size, often with a corresponding increase in insulin production. These adaptive responses within the islets are ultimately intended to maintain glycemic control and to promote macronutrient homeostasis during times of stress. Herein, we review the consequences of specific metabolic trauma that lead to insulin resistance and the corresponding adaptive alterations within the pancreatic islets.
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Affiliation(s)
- Susan J. Burke
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808
| | - Michael D. Karlstad
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920
| | - J. Jason Collier
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920
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21
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HUANG J, ZHU X. The Molecular Mechanisms of Calpains Action on Skeletal Muscle Atrophy. Physiol Res 2016; 65:547-560. [DOI: 10.33549/physiolres.933087] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle atrophy is associated with a loss of muscle protein which may result from both increased proteolysis and decreased protein synthesis. Investigations on cell signaling pathways that regulate muscle atrophy have promoted our understanding of this complicated process. Emerging evidence implicates that calpains play key roles in dysregulation of proteolysis seen in muscle atrophy. Moreover, studies have also shown that abnormally activated calpain results muscle atrophy via its downstream effects on ubiquitin-proteasome pathway (UPP) and Akt phosphorylation. This review will discuss the role of calpains in regulation of skeletal muscle atrophy mainly focusing on its collaboration with either UPP or Akt in atrophy conditions in hope to stimulate the interest in development of novel therapeutic interventions for skeletal muscle atrophy.
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Affiliation(s)
| | - X. ZHU
- Department of Respiratory Diseases, YangPu Hospital of Tongji University, Shanghai, China
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22
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Duan H, Zhang X, Chai J, Hu Q, Liu L, Ma L, Feng Y, Yu Y. Apoptosis and death receptor signaling in diaphragm of burnt rats. J Surg Res 2016; 203:6-14. [PMID: 27338528 DOI: 10.1016/j.jss.2016.01.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 01/20/2016] [Accepted: 01/27/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Respiratory dysfunction is a frequent complication after severe burn injury. Respiratory muscle atrophy may induce respiratory dysfunction due to insufficient inspiratory motive power. Accumulated evidence suggests that apoptosis is very important in skeletal muscle atrophy in multiple pathologic conditions. Therefore, we hypothesize that myonuclear apoptosis contributes to diaphragm atrophy induced by burn injury, and death receptor signaling activation plays a role in this process. METHODS Wistar rats in the burn-injured group were subjected to a full-thickness scald injury around 40% of total body surface area. Diaphragm samples were examined for myonuclear apoptosis by transmission electron microscope, terminal deoxynucleotidyl transferase-mediated nick end labeling assay, and immunohistochemistry for caspase-3. Serum level of apoptotic ligands were assessed by ELISA. Activation of death receptor signaling was examined by Western blotting. RESULTS Burn injury resulted in significant reductions of diaphragm muscle mass and myofiber cross-section area. Apoptosis in diaphragm appeared from day 1 and peaked on day 4 after injury. The level of soluble TNF-related apoptosis-inducing ligand and the ratio of Fas ligand to soluble Fas in serum significantly increased after burn injury. In diaphragm of burnt animals, the expressions of proapoptotic proteins, such as cleaved caspase-8, cleaved caspase-3, and Bax-to-Bcl-2 ratio were upregulated, whereas expression of pAkt, an antiapoptotic protein, was downregulated. Immunohistochemistry revealed that the most of the caspase-3 was expressed in myofiber nuclei and their surrounding cytoplasm area in tissue sections. CONCLUSIONS Severe burn injury induces myonuclear apoptosis in diaphragm, which could be a contributor to diaphragm muscle atrophy. Activation of death receptor signaling may be a mechanism of apoptosis in diaphragm.
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Affiliation(s)
- Hongjie Duan
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Xulong Zhang
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Jiake Chai
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China.
| | - Quan Hu
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Lingying Liu
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Li Ma
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Yongqiang Feng
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
| | - Yonghui Yu
- Department of Burns and Plastic Surgery, Burns Institute, The First Affiliated Hospital of PLA General Hospital (Formerly 304th Hospital of PLA), Beijing, China
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23
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Akscyn RM, Franklin JL, Gavrikova TA, Messina JL. Skeletal muscle atrogene expression and insulin resistance in a rat model of polytrauma. Physiol Rep 2016; 4:4/2/e12659. [PMID: 26818585 PMCID: PMC4760393 DOI: 10.14814/phy2.12659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Polytrauma is a combination of injuries to more than one body part or organ system. Polytrauma is common in warfare, and in automobile and industrial accidents. The combination of injuries can include burn, fracture, hemorrhage, and trauma to the extremities or specific organ systems. Resistance to anabolic hormones, loss of muscle mass, and metabolic dysfunction can occur following injury. To investigate the effects of combined injuries, we have developed a highly reproducible rodent model of polytrauma. This model combines burn injury, soft tissue trauma, and penetrating injury to the gastrointestinal (GI) tract. Adult, male Sprague–Dawley rats were anesthetized with pentobarbital and subjected to a 15–20% total body surface area scald burn, or laparotomy and a single puncture of the cecum with a G30 needle, or the combination of both injuries (polytrauma). In the current studies, the inflammatory response to polytrauma was examined in skeletal muscle. Changes in skeletal muscle mRNA levels of the proinflammatory cytokines TNF‐α, IL‐1β, and IL‐6 were observed following single injuries and polytrauma. Increased expression of the E3 ubiquitin ligases Atrogin‐1/FBX032 and TRIM63/MuRF‐1 were measured following injury, as was skeletal muscle insulin resistance, as evidenced by decreased insulin‐inducible insulin receptor (IR) and AKT/PKB (Protein Kinase B) phosphorylation. Changes in the abundance of IR and insulin receptor substrate‐1 (IRS‐1) were observed at the protein and mRNA levels. Additionally, increased TRIB3 mRNA levels were observed 24 h following polytrauma, the same time when insulin resistance was observed. This may suggest a role for TRIB3 in the development of acute insulin resistance following injury.
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Affiliation(s)
- Robert M Akscyn
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama
| | - John L Franklin
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Tatyana A Gavrikova
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Joseph L Messina
- Department of Pathology, Division of Molecular and Cellular Pathology, University of Alabama at Birmingham, Birmingham, Alabama Vetrans Affairs Medical Center, Birmingham, Alabama
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24
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YU YONGHUI, CHU WANLI, CHAI JIAKE, LI XIAO, LIU LINGYING, MA LI. Critical role of miRNAs in mediating skeletal muscle atrophy (Review). Mol Med Rep 2015; 13:1470-4. [DOI: 10.3892/mmr.2015.4748] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 12/08/2015] [Indexed: 11/05/2022] Open
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Nakazawa H, Yamada M, Tanaka T, Kramer J, Yu YM, Fischman AJ, Martyn JAJ, Tompkins RG, Kaneki M. Role of protein farnesylation in burn-induced metabolic derangements and insulin resistance in mouse skeletal muscle. PLoS One 2015; 10:e0116633. [PMID: 25594415 PMCID: PMC4296934 DOI: 10.1371/journal.pone.0116633] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 12/11/2014] [Indexed: 01/04/2023] Open
Abstract
Objective Metabolic derangements, including insulin resistance and hyperlactatemia, are a major complication of major trauma (e.g., burn injury) and affect the prognosis of burn patients. Protein farnesylation, a posttranslational lipid modification of cysteine residues, has been emerging as a potential component of inflammatory response in sepsis. However, farnesylation has not yet been studied in major trauma. To study a role of farnesylation in burn-induced metabolic aberration, we examined the effects of farnesyltransferase (FTase) inhibitor, FTI-277, on burn-induced insulin resistance and metabolic alterations in mouse skeletal muscle. Methods A full thickness burn (30% total body surface area) was produced under anesthesia in male C57BL/6 mice at 8 weeks of age. After the mice were treated with FTI-277 (5 mg/kg/day, IP) or vehicle for 3 days, muscle insulin signaling, metabolic alterations and inflammatory gene expression were evaluated. Results Burn increased FTase expression and farnesylated proteins in mouse muscle compared with sham-burn at 3 days after burn. Simultaneously, insulin-stimulated phosphorylation of insulin receptor (IR), insulin receptor substrate (IRS)-1, Akt and GSK-3β was decreased. Protein expression of PTP-1B (a negative regulator of IR-IRS-1 signaling), PTEN (a negative regulator of Akt-mediated signaling), protein degradation and lactate release by muscle, and plasma lactate levels were increased by burn. Burn-induced impaired insulin signaling and metabolic dysfunction were associated with increased inflammatory gene expression. These burn-induced alterations were reversed or ameliorated by FTI-277. Conclusions Our data demonstrate that burn increased FTase expression and protein farnesylation along with insulin resistance, metabolic alterations and inflammatory response in mouse skeletal muscle, all of which were prevented by FTI-277 treatment. These results indicate that increased protein farnesylation plays a pivotal role in burn-induced metabolic dysfunction and inflammatory response. Our study identifies FTase as a novel potential molecular target to reverse or ameliorate metabolic derangements in burn patients.
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Affiliation(s)
- Harumasa Nakazawa
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - Marina Yamada
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
| | - Tomokazu Tanaka
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America
| | - Joshua Kramer
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yong-Ming Yu
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alan J. Fischman
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
| | - J. A. Jeevendra Martyn
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
| | - Ronald G. Tompkins
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
- Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Masao Kaneki
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America
- Shriners Hospitals for Children, Boston, Massachusetts, United States of America
- * E-mail:
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Yu Y, Chai J. The function of miRNAs and their potential as therapeutic targets in burn-induced insulin resistance (review). Int J Mol Med 2014; 35:305-10. [PMID: 25484249 DOI: 10.3892/ijmm.2014.2023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 12/03/2014] [Indexed: 11/06/2022] Open
Abstract
Burns are common accidental injuries. The main clinical manifestations of severe burn injury are insulin resistance and high metabolism. Insulin resistance results in hyperglycemia, which may lead to skeletal muscle wasting and suspended wound healing. It also elevates the risk of infection and sepsis. Studies have indicated that insulin receptor (IR) and insulin receptor substrate 1 (IRS1) are essential factors involved in the regulation of blood glucose levels. Moreover, the suppression of the IR/IRS1 signaling pathway results in insulin resistance. Recent studies have also indicated that miRNAs, which are small non-coding RNAs consisting of 20-23 nucleotides, target the 3'-untranslated region (3'-UTR) of IRS1 mRNA and attenuate protein translation. miRNAs also play an important role in the development of type II diabetes (T2D) and obesity-induced insulin resistance. In the present review, we discuss the involvement of miRNAs in burn-induced insulin resistance through the targeting of the IR/IRS1 signaling pathway. We also discuss the possibility of miRNAs a novel therapeutic target in insulin resistance in burn patients.
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Affiliation(s)
- Yonghui Yu
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of PLA General Hospital, Beijing 100048, P.R. China
| | - Jiake Chai
- Department of Burn and Plastic Surgery, The First Affiliated Hospital of PLA General Hospital, Beijing 100048, P.R. China
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Avan A, Avan A, Le Large TYS, Mambrini A, Funel N, Maftouh M, Ghayour-Mobarhan M, Cantore M, Boggi U, Peters GJ, Pacetti P, Giovannetti E. AKT1 and SELP polymorphisms predict the risk of developing cachexia in pancreatic cancer patients. PLoS One 2014; 9:e108057. [PMID: 25238546 PMCID: PMC4169595 DOI: 10.1371/journal.pone.0108057] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Accepted: 08/19/2014] [Indexed: 12/15/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) patients have the highest risk of developing cachexia, which is a direct cause of reduced quality of life and shorter survival. Novel biomarkers to identify patients at risk of cachexia are needed and might have a substantial impact on clinical management. Here we investigated the prognostic value and association of SELP-rs6136, IL6-rs1800796 and AKT1-rs1130233 polymorphisms with cachexia in PDAC. Genotyping was performed in DNA from blood samples of a test and validation cohorts of 151 and 152 chemo-naive locally-advanced/metastatic PDAC patients, respectively. The association of SELP-rs6136, IL6-rs1800796 and AKT1-rs1130233 polymorphisms with cachexia as well as the correlation between cachexia and the candidate polymorphisms and overall survival were analyzed. Akt expression and phosphorylation in muscle biopsies were evaluated by specific ELISA assays. SELP-rs6136-AA and AKT1-rs1130233-AA/GA genotypes were associated with increased risk of developing cachexia in both cohorts (SELP: p = 0.011 and p = 0.045; AKT1: p = 0.004 and p = 0.019 for the first and second cohorts, respectively), while patients carrying AKT1-rs1130233-GG survived significantly longer (p = 0.002 and p = 0.004 for the first and second cohorts, respectively). In the multivariate analysis AKT1-rs1130233-AA/GA genotypes were significant predictors for shorter survival, with an increased risk of death of 1.7 (p = 0.002) and 1.6 (p = 0.004), in the first and second cohorts, respectively. This might be explained by the reduced phosphorylation of Akt1 in muscle biopsies from patients harboring AKT1-rs1130233-AA/GA (p = 0.003), favoring apoptosis induction. In conclusion, SELP and AKT1 polymorphisms may play a role in the risk of cachexia and death in PDAC patients, and should be further evaluated in larger prospective studies.
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Affiliation(s)
- Abolfazl Avan
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
| | - Amir Avan
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
- Biochemistry of Nutrition Research Center, and Department of New Sciences and Technology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Tessa Y. S. Le Large
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
| | - Andrea Mambrini
- Department of Medical Oncology, Carrara Civic Hospital, Carrara, Italy
| | | | - Mina Maftouh
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
| | - Majid Ghayour-Mobarhan
- Biochemistry of Nutrition Research Center, and Department of New Sciences and Technology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Maurizio Cantore
- Department of Medical Oncology, Carrara Civic Hospital, Carrara, Italy
| | - Ugo Boggi
- Start-Up Unit, University of Pisa, Pisa, Italy
| | - Godefridus J. Peters
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
| | - Paola Pacetti
- Department of Medical Oncology, Carrara Civic Hospital, Carrara, Italy
| | - Elisa Giovannetti
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
- Start-Up Unit, University of Pisa, Pisa, Italy
- * E-mail:
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Chondronikola M, Meyer WJ, Sidossis LS, Ojeda S, Huddleston J, Stevens P, Børsheim E, Suman OE, Finnerty CC, Herndon DN. Predictors of insulin resistance in pediatric burn injury survivors 24 to 36 months postburn. J Burn Care Res 2014; 35:409-15. [PMID: 24918945 PMCID: PMC4162820 DOI: 10.1097/bcr.0000000000000017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Burn injury is a dramatic event with acute and chronic consequences including insulin resistance. However, factors associated with insulin resistance have not been previously investigated. The purpose of this study was to identify factors associated with long-term insulin resistance in pediatric burn injury survivors. The study sample consisted of 61 pediatric burn injury survivors 24 to 36 months after the burn injury, who underwent an oral glucose tolerance test. To assess insulin resistance, the authors calculated the area under the curve for glucose and insulin. The diagnostic criteria of the American Diabetes Association were used to define individuals with impaired glucose metabolism. Additional data collected include body composition, anthropometric measurements, burn characteristics, and demographic information. The data were analyzed using multivariate linear regression analysis. Approximately 12% of the patients met the criteria for impaired glucose metabolism. After adjusting for possible confounders, burn size, age, and body fat percentage were associated with the area under the curve for glucose (P < .05 for all). Time postburn and lean mass were inversely associated with the area under the curve for glucose (P < .05 for both). Similarly, older age predicted higher insulin area under the curve. The results indicate that a significant proportion of pediatric injury survivors suffer from glucose abnormalities 24 to 36 months postburn. Burn size, time postburn, age, lean mass, and adiposity are significant predictors of insulin resistance in pediatric burn injury survivors. Clinical evaluation and screening for abnormal glucose metabolism should be emphasized in patients with large burns, older age, and survivors with high body fat.
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Affiliation(s)
- Maria Chondronikola
- Graduate School of Biomedical Sciences, Department of Preventative Medicine and Community Health, University of Texas Medical Branch, Galveston, Texas, United States
| | - Walter J. Meyer
- Shriners Hospitals for Children–Galveston, Texas, United States
- Department of Psychiatry, University of Texas Medical Branch, Galveston, Texas, United States
| | - Labros S. Sidossis
- Shriners Hospitals for Children–Galveston, Texas, United States
- Department of Internal Medicine-Geriatrics, University of Texas Medical Branch, Galveston, Texas, United States
- Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, United States
| | - Sylvia Ojeda
- Shriners Hospitals for Children–Galveston, Texas, United States
| | | | - Pamela Stevens
- Shriners Hospitals for Children–Galveston, Texas, United States
| | - Elisabet Børsheim
- Shriners Hospitals for Children–Galveston, Texas, United States
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas, United States
| | - Oscar E. Suman
- Shriners Hospitals for Children–Galveston, Texas, United States
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas, United States
| | - Celeste C. Finnerty
- Shriners Hospitals for Children–Galveston, Texas, United States
- Institute for Translational Sciences, University of Texas Medical Branch, Galveston, Texas, United States
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas, United States
| | - David N. Herndon
- Shriners Hospitals for Children–Galveston, Texas, United States
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas, United States
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Reversal of muscle atrophy by Zhimu-Huangbai herb-pair via Akt/mTOR/FoxO3 signal pathway in streptozotocin-induced diabetic mice. PLoS One 2014; 9:e100918. [PMID: 24968071 PMCID: PMC4072704 DOI: 10.1371/journal.pone.0100918] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 06/02/2014] [Indexed: 12/22/2022] Open
Abstract
Skeletal muscle atrophy is one of the serious complications of diabetes. Zhimu-Huangbai herb-pair (ZB) is widely used in Chinese traditional medicine formulas for treating Xiaoke (known as diabetes) and its complications. However, the effect of ZB on reversal of muscle atrophy and the underlying mechanisms remain unknown. In this research, we investigated the effect and possible mechanisms of ZB on skeletal muscle atrophy in diabetic mice. Animal model of diabetic muscle atrophy was developed by high fat diet (HFD) feeding plus streptozotocin (STZ) injection. After oral adminstration of ZB for 6 weeks, the effects of ZB on reversal of muscle atrophy and the underlying mechanisms were evaluated by biochemical, histological and western blot methods. The skeletal muscle weight, strength, and cross-sectional area of diabetic mice were significantly increased by ZB treatment. Biochemical results showed that ZB treatment reduced the serum glucose level, and elevated the serum insulin-like growth factor 1 (IGF-1) and insulin levels significantly compared with untreated diabetic group. The western blot results showed that ZB activated the mTOR signal pathway, shown as increased phosphorylations (p-) of Akt, mTOR, Raptor, S6K1 and reduced Foxo3 expression compared with the model group. ZB could reverse muscle atrophy in diabetic mice. This may be through activation of mTOR signaling pathway that promotes protein synthesis, and inactivation foxo3 protein that inhibits protein degradation. These findings suggested that ZB may be considered as a potential candidate drug in treatment of diabetic muscle atrophy.
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Immobilization with atrophy induces de novo expression of neuronal nicotinic α7 acetylcholine receptors in muscle contributing to neurotransmission. Anesthesiology 2014; 120:76-85. [PMID: 24126263 DOI: 10.1097/aln.0000000000000025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Mature acetylcholine receptor (AChR) isoform normally mediates muscle contraction. The hypothesis that α7AChRs up-regulate during immobilization and contribute to neurotransmission was tested pharmacologically using specific blockers to mature (waglerin-1), immature (αA-OIVA), and α7AChRs (methyllycaconitine), and nonspecific muscle AChR antagonist, α-bungarotoxin. METHODS Mice were immobilized; contralateral limbs were controls. Fourteen days later, anesthetized mice were mechanically ventilated. Nerve-stimulated tibialis muscle contractions on both sides were recorded, and blockers enumerated above sequentially administered via jugular vein. Data are mean ± standard error. RESULTS Immobilization (N = 7) induced tibialis muscle atrophy (40.6 ± 2.8 vs. 52.1 ± 2.0 mg; P < 0.01) and decrease of twitch tension (34.8 ± 1.1 vs. 42.9 ± 1.5 g; P < 0.01). Waglerin-1 (0.3 ± 0.05 μg/g) significantly (P = 0.001; N = 9) depressed twitch tension on contralateral (≥97%) versus immobilized side (approximately 45%). Additional waglerin-1 (total dose 1.06 ± 0.12 μg/g or approximately 15.0 × ED50 in normals) could not depress twitch of 80% or greater on immobilized side. Immature AChR blocker, αA-OIVA (17.0 ± 0.25 μg/g) did not change tension bilaterally. Administration of α-bungarotoxin (N = 4) or methyllycaconitine (N = 3) caused 96% or greater suppression of the remaining twitch tension on immobilized side. Methyllycaconitine, administered first (N = 3), caused equipotent inhibition by waglerin-1 on both sides. Protein expression of α7AChRs was significantly (N = 3; P < 0.01) increased on the immobilized side. CONCLUSIONS Ineffectiveness of waglerin-1 suggests that the twitch tension during immobilization is maintained by receptors other than mature AChRs. Because αA-OIVA caused no neuromuscular changes, it can be concluded that immature AChRs contribute minimally to neurotransmission. During immobilization approximately 20% of twitch tension is maintained by up-regulation of α-bungarotoxin- and methyllycaconitine-sensitive α7AChRs.
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Abstract
The ideal set of variables for nutritional monitoring that may correlate with patient outcomes has not been identified. This is particularly difficult in the PICU patient because many of the standard modes of nutritional monitoring, although well described and available, are fraught with difficulties. Thus, repeated anthropometric and laboratory markers must be jointly analyzed but individually interpreted according to disease and metabolic changes, in order to modify and monitor the nutritional treatment. In addition, isotope techniques are neither clinically feasible nor compatible with the multiple measurements needed to follow progression. On the other hand, indirect alternatives exist but may have pitfalls, of which the clinician must be aware. Risks exist for both overfeeding and underfeeding of PICU patients so that an accurate monitoring of energy expenditure, using targeted indirect calorimetry, is necessary to avoid either extreme. This is very important, since the monitoring of the nutritional status of the critically ill child serves as a guide to early and effective nutritional intervention.
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Kaneki M, Fukushima Y, Shinozaki S, Fukaya M, Habiro M, Shimizu N, Chang K, Yasuhara S, Martyn JAJ. iNOS inhibitor, L-NIL, reverses burn-induced glycogen synthase kinase-3β activation in skeletal muscle of rats. Metabolism 2013; 62:341-6. [PMID: 22995863 PMCID: PMC4090935 DOI: 10.1016/j.metabol.2012.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 08/16/2012] [Accepted: 08/16/2012] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Recent studies suggest that activation of glycogen synthase kinase (GSK)-3β may be involved in burn injury-induced metabolic derangements and protein breakdown in skeletal muscle. However, the mechanism for GSK-3β activation after burn injury is unknown. To investigate the role of inducible nitric oxide synthase (iNOS) in this scenario, a major mediator of inflammation, we examined the effects of a specific inhibitor for iNOS, L-NIL, on GSK-3β activity in skeletal muscle of burned rats. MATERIALS/METHODS Full-thickness third degree burn injury comprising 40% of total body surface area was produced under anesthesia in male Sprague-Dawley rats (160-190g) by immersing the back of the trunk for 15s and the abdomen for 8s in 80°C water. Burned and sham-burned rats were treated with L-NIL (60mg/kg BW, b.i.d., IP) or phosphate-buffered saline for three days. GSK-3β activity in skeletal muscle was evaluated by immune complex kinase assay, and by phosphorylation status of GSK-3β and its endogenous substrate, glycogen synthase. RESULTS GSK-3β activity was increased in a time-dependent manner in skeletal muscle after burn injury, concomitant with the induction of iNOS expression. iNOS inhibitor, L-NIL, reverted the elevated GSK-3β activity in skeletal muscle of burned rats, although L-NIL did not alter GSK-3β activity in sham-burned rats. CONCLUSIONS Our results clearly indicate that iNOS plays an important role in burn injury-induced GSK-3β activation in skeletal muscle. These findings suggest that iNOS may contribute to burn injury-induced metabolic derangements, in part, by activating GSK-3β.
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Affiliation(s)
- Masao Kaneki
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Boston, MA 02114, USA.
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Lu XM, Tompkins RG, Fischman AJ. Nitric oxide activates intradomain disulfide bond formation in the kinase loop of Akt1/PKBα after burn injury. Int J Mol Med 2013; 31:740-50. [PMID: 23314241 PMCID: PMC3597556 DOI: 10.3892/ijmm.2013.1241] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/14/2012] [Indexed: 11/23/2022] Open
Abstract
Severe burn injury is an acute inflammatory state with massive alterations in gene expression and levels of growth factors, cytokines and free radicals. During the catabolic processes, changes in insulin sensitivity and skeletal muscle wasting (unintended loss of 5–15% of lean body mass) are observed clinically. Here, we reveal a novel molecular mechanism of Akt1/protein kinase Bα (Akt1/PKBα) regulated via cross-talking between dephosphorylation of Thr308 and S-nitrosylation of Cys296 post severe burn injury, which were characterized using nano-LC interfaced with tandem quadrupole time-of-fight mass spectrometry (Q-TOF)micro tandem mass spectrometry in both in vitro and in vivo studies. For the in vitro studies, Akt1/PKBα was S-nitrosylated with S-nitrosoglutathione and derivatized by three methods. The derivatives were isolated by SDS-PAGE, trypsinized and analyzed by the tandem MS. For the in vivo studies, Akt1/PKBα in muscle lysates from burned rats was immuno-precipitated, derivatized with HPDP-Biotin and analyzed as above. The studies demonstrated that the NO free radical reacts with the free thiol of Cys296 to produce a Cys296-SNO intermediate which accelerates interaction with Cys310 to form Cys296-Cys310 in the kinase loop. MS/MS sequence analysis indicated that the dipeptide, linked via Cys296-Cys310, underwent dephosphorylation at Thr308. These effects were not observed in lysates from sham animals. As a result of this dual effect of burn injury, the loose conformation that is slightly stabilized by the Lys297-Thr308 salt bridge may be replaced by a more rigid structure which may block substrate access. Together with the findings of our previous report concerning mild IRS-1 integrity changes post burn, it is reasonable to conclude that the impaired Akt1/PKBα has a major impact on FOXO3 subcellular distribution and activities.
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Affiliation(s)
- X-M Lu
- Surgical Service, Massachusetts General Hospital, Boston, MA, USA
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Lambertucci AC, Lambertucci RH, Hirabara SM, Curi R, Moriscot AS, Alba-Loureiro TC, Guimarães-Ferreira L, Levada-Pires AC, Vasconcelos DAA, Sellitti DF, Pithon-Curi TC. Glutamine supplementation stimulates protein-synthetic and inhibits protein-degradative signaling pathways in skeletal muscle of diabetic rats. PLoS One 2012; 7:e50390. [PMID: 23239980 PMCID: PMC3519752 DOI: 10.1371/journal.pone.0050390] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 10/24/2012] [Indexed: 11/29/2022] Open
Abstract
In this study, we investigated the effect of glutamine (Gln) supplementation on the signaling pathways regulating protein synthesis and protein degradation in the skeletal muscle of rats with streptozotocin (STZ)-induced diabetes. The expression levels of key regulatory proteins in the synthetic pathways (Akt, mTOR, GSK3 and 4E-BP1) and the degradation pathways (MuRF-1 and MAFbx) were determined using real-time PCR and Western blotting in four groups of male Wistar rats; 1) control, non-supplemented with glutamine; 2) control, supplemented with glutamine; 3) diabetic, non-supplemented with glutamine; and 4) diabetic, supplemented with glutamine. Diabetes was induced by the intravenous injection of 65 mg/kg bw STZ in citrate buffer (pH 4.2); the non-diabetic controls received only citrate buffer. After 48 hours, diabetes was confirmed in the STZ-treated animals by the determination of blood glucose levels above 200 mg/dL. Starting on that day, a solution of 1 g/kg bw Gln in phosphate buffered saline (PBS) was administered daily via gavage for 15 days to groups 2 and 4. Groups 1 and 3 received only PBS for the same duration. The rats were euthanized, and the soleus muscles were removed and homogenized in extraction buffer for the subsequent measurement of protein and mRNA levels. The results demonstrated a significant decrease in the muscle Gln content in the diabetic rats, and this level increased toward the control value in the diabetic rats receiving Gln. In addition, the diabetic rats exhibited a reduced mRNA expression of regulatory proteins in the protein synthesis pathway and increased expression of those associated with protein degradation. A reduction in the skeletal muscle mass in the diabetic rats was observed and was alleviated partially with Gln supplementation. The data suggest that glutamine supplementation is potentially useful for slowing the progression of muscle atrophy in patients with diabetes.
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Affiliation(s)
- Adriana C. Lambertucci
- Institute of Physical Activity Sciences and Sports, Post-Graduate Program in Human Movement Sciences, Cruzeiro do Sul University, São Paulo, Brazil
| | - Rafael H. Lambertucci
- Institute of Physical Activity Sciences and Sports, Post-Graduate Program in Human Movement Sciences, Cruzeiro do Sul University, São Paulo, Brazil
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Sandro M. Hirabara
- Institute of Physical Activity Sciences and Sports, Post-Graduate Program in Human Movement Sciences, Cruzeiro do Sul University, São Paulo, Brazil
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Anselmo S. Moriscot
- Department of Cell Biology and Development, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Tatiana C. Alba-Loureiro
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Lucas Guimarães-Ferreira
- Center of Physical Education and Sports, Federal University of Espirito Santo, Espirito Santo, Brazil
| | - Adriana C. Levada-Pires
- Institute of Physical Activity Sciences and Sports, Post-Graduate Program in Human Movement Sciences, Cruzeiro do Sul University, São Paulo, Brazil
| | - Diogo A. A. Vasconcelos
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Donald F. Sellitti
- Department of Medicine, Uniformed Services University of Health Sciences, Bethesda, Maryland, United States of America
| | - Tania C. Pithon-Curi
- Institute of Physical Activity Sciences and Sports, Post-Graduate Program in Human Movement Sciences, Cruzeiro do Sul University, São Paulo, Brazil
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Wu X, Walters TJ, Rathbone CR. Skeletal muscle satellite cell activation following cutaneous burn in rats. Burns 2012; 39:736-44. [PMID: 23146573 DOI: 10.1016/j.burns.2012.10.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 10/10/2012] [Accepted: 10/15/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cutaneous burn distant from skeletal muscles induces atrophy; however, its effect on muscle stem cells resident in skeletal muscle (satellite cells) distal to burn is not known. METHODS Satellite cell activation was measured in predominantly fast-twitch [tibialis anterior, extensor digitorum longus (EDL), plantaris, and gastrocnemius] and slow-twitch (soleus) muscles of rats that received either 40% total body surface area full-thickness scald burn or sham burn to the trunk area by determining bromodeoxyuridine incorporation, MyoD, and Pax7 immunohistochemistry in vivo ≤48 h after burn. To determine the effects of circulating factors on satellite cell activation, satellite cell cultures were treated with serum from sham or burn rats. RESULTS In vivo activation of satellite cells was increased in fast muscles isolated from burn as compared to sham animals, whereas a significant response was not seen in slow muscles. Serum taken from animals in the burn group increased the activation of satellite cells isolated from both sham and burn animals in vitro, suggesting that circulating factors have the potential to increase satellite cell activation following burn. CONCLUSIONS Increases in satellite cell activation in muscles distal to burn are fiber-type-dependent, and circulating factors may play a role in the activation of satellite cells following burn. A better understanding of the impact of burn on satellite cell functionality will allow us to identify the cellular mechanisms of long-term muscle atrophy.
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Affiliation(s)
- Xiaowu Wu
- Extremity Trauma and Regenerative Medicine, US Army Institute of Surgical Research, Fort Sam Houston, TX 78234-6315, USA.
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Fanzani A, Conraads VM, Penna F, Martinet W. Molecular and cellular mechanisms of skeletal muscle atrophy: an update. J Cachexia Sarcopenia Muscle 2012; 3:163-79. [PMID: 22673968 PMCID: PMC3424188 DOI: 10.1007/s13539-012-0074-6] [Citation(s) in RCA: 234] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 05/13/2012] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle atrophy is defined as a decrease in muscle mass and it occurs when protein degradation exceeds protein synthesis. Potential triggers of muscle wasting are long-term immobilization, malnutrition, severe burns, aging as well as various serious and often chronic diseases, such as chronic heart failure, obstructive lung disease, renal failure, AIDS, sepsis, immune disorders, cancer, and dystrophies. Interestingly, a cooperation between several pathophysiological factors, including inappropriately adapted anabolic (e.g., growth hormone, insulin-like growth factor 1) and catabolic proteins (e.g., tumor necrosis factor alpha, myostatin), may tip the balance towards muscle-specific protein degradation through activation of the proteasomal and autophagic systems or the apoptotic pathway. Based on the current literature, we present an overview of the molecular and cellular mechanisms that contribute to muscle wasting. We also focus on the multifacetted therapeutic approach that is currently employed to prevent the development of muscle wasting and to counteract its progression. This approach includes adequate nutritional support, implementation of exercise training, and possible pharmacological compounds.
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Affiliation(s)
- Alessandro Fanzani
- Department of Biomedical Sciences and Biotechnologies and Interuniversitary Institute of Myology (IIM), University of Brescia, viale Europa 11, 25123, Brescia, Italy,
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Novel mitochondria-targeted antioxidant peptide ameliorates burn-induced apoptosis and endoplasmic reticulum stress in the skeletal muscle of mice. Shock 2012; 36:580-5. [PMID: 21937949 DOI: 10.1097/shk.0b013e3182366872] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This study tested the hypothesis that a novel mitochondria-targeted SS-31 peptide attenuates the burn injury-induced apoptosis and endoplasmic reticulum stress and improves insulin sensitivity in the skeletal muscle. Following 30% total body surface area burn or sham burn, mice were injected daily with SS-31 peptide (5 mg/kg body weight), and the rectus abdominis muscles collected on postburn days 1, 3, and 7. The tissues were subjected to various biochemical and immunohistochemical analyses. Treatment with SS-31 peptide prevented burn-induced increases in the caspase 3 activity (P < 0.05) and apoptosis (P < 0.01) on postburn day 7. The SS-31 peptide treatment also prevented the increase in the expression levels of phosphatase and tensin homolog on postburn days 3 and 7. Burn injury-induced increases in the levels of two endoplasmic reticulum stress markers, binding immunoglobulin protein and protein disulfide isomerase, were significantly decreased by the SS-31 peptide treatments on postburn day 7 and on day 3 for binding immunoglobulin protein as well (P < 0.05). The effects of SS-31 appear to be, in part, due to its ability to reduce oxidative stress in burned mice, evidenced by reduced expression of oxidized proteins that were clearly evident on postburn day 7. Our results demonstrate a possible therapeutic potential of SS-31 peptide to ameliorate the adverse effects of burn injury in skeletal muscle.
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Brooks NC, Song J, Boehning D, Kraft R, Finnerty CC, Herndon DN, Jeschke MG. Propranolol improves impaired hepatic phosphatidylinositol 3-kinase/akt signaling after burn injury. Mol Med 2012; 18:707-11. [PMID: 22396018 DOI: 10.2119/molmed.2011.00277] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 02/28/2012] [Indexed: 12/11/2022] Open
Abstract
Severe burn injury is associated with induction of the hepatic endoplasmic reticulum (ER) stress response. ER stress leads to activation of c-Jun N-terminal kinase (JNK), suppression of insulin receptor signaling via phosphorylation of insulin receptor substrate 1 and subsequent insulin resistance. Marked and sustained increases in catecholamines are prominent after a burn. Here, we show that administration of propranolol, a nonselective β1/2 adrenergic receptor antagonist, attenuates ER stress and JNK activation. Attenuation of ER stress by propranolol results in increased insulin sensitivity, as determined by activation of hepatic phosphatidylinositol 3-kinase and Akt. We conclude that catecholamine release is responsible for the ER stress response and impaired insulin receptor signaling after burn injury.
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Affiliation(s)
- Natasha C Brooks
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
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Kraft R, Herndon DN, Kulp GA, Mecott GA, Trentzsch H, Jeschke MG. Retinol binding protein: marker for insulin resistance and inflammation postburn? JPEN J Parenter Enteral Nutr 2012; 35:695-703. [PMID: 22042048 DOI: 10.1177/0148607111413901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Burn injury leads to vast changes in both metabolic and inflammatory responses and is associated with increased morbidity and mortality. Insulin resistance (IR) and hyperglycemia are major components of the hypermetabolic response found in burn-injured patients and subsequently contribute to adverse outcomes. Studies have shown that increased systemic retinol binding protein (RBP) levels are associated with IR and hyperinflammation in diabetic and obese patients. The aim of this study was to determine RBP profiles and to test the hypothesis that elevated RBP levels are associated with both IR and the inflammatory response in burned patients. METHODS RBP was measured in 372 patients during the acute stay postburn. Patients' demographics, glucose levels, and insulin administration were recorded. Cytokines, hormones, plasma proteins, and organ markers were measured. The average of all measurements of RBP (2.1 mg/dL) was used to divide patients into high and low groups. Statistical analysis was performed by Student t test. Statistical significance was accepted at P < .05. RESULTS Fifty-one patients (high group) had elevated RBP levels during acute hospitalization and demonstrated a significant higher incidence of multiorgan failure, sepsis, and mortality (P < .05). Moreover, in the high group, a significant increase of IR, inflammatory cytokines, and catabolic and organ-specific markers were detected (P < .05). CONCLUSIONS Increased RBP levels postburn correlate with increased IR, inflammatory and catabolic responses, incidence of multiorgan failure, and mortality. RBP may be a novel biomarker to monitor these detrimental responses postburn.
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Affiliation(s)
- Robert Kraft
- Shriners Hospitals for Children, and Department of Surgery, University of Texas Medical Branch Galveston, Texas, USA
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Sugita M, Sugita H, Kim M, Mao J, Yasuda Y, Habiro M, Shinozaki S, Yasuhara S, Shimizu N, Martyn JJ, Kaneki M. Inducible nitric oxide synthase deficiency ameliorates skeletal muscle insulin resistance but does not alter unexpected lower blood glucose levels after burn injury in C57BL/6 mice. Metabolism 2012; 61:127-36. [PMID: 21816442 PMCID: PMC3304504 DOI: 10.1016/j.metabol.2011.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 05/30/2011] [Accepted: 06/02/2011] [Indexed: 01/04/2023]
Abstract
Burn injury is associated with inflammatory responses and metabolic alterations including insulin resistance. Impaired insulin receptor substrate-1 (IRS-1)-mediated insulin signal transduction is a major component of insulin resistance in skeletal muscle following burn injury. To further investigate molecular mechanisms that underlie burn injury-induced insulin resistance, we study a role of inducible nitric oxide synthase (iNOS), a major mediator of inflammation, on burn-induced muscle insulin resistance in iNOS-deficient mice. Full-thickness third-degree burn injury comprising 12% of total body surface area was produced in wild-type and iNOS-deficient C57BL/6 mice. Insulin-stimulated activation (phosphorylation) of IR, IRS-1, and Akt was assessed by immunoblotting and immunoprecipitation. Insulin-stimulated glucose uptake by skeletal muscle was evaluated ex vivo. Burn injury caused induction of iNOS in skeletal muscle of wild-type mice. The increase of iNOS expression paralleled the increase of insulin resistance, as evidenced by decreased tyrosine phosphorylation of IR and IRS-1, IRS-1 expression, insulin-stimulated activation of phosphatidylinositol 3-kinase and Akt/PKB, and insulin-stimulated glucose uptake in mouse skeletal muscle. The absence of iNOS in genetically engineered mice significantly lessened burn injury-induced insulin resistance in skeletal muscle. In wild-type mice, insulin tolerance test revealed whole-body insulin resistance in burned mice compared with sham-burned controls. This effect was reversed by iNOS deficiency. Unexpectedly, however, blood glucose levels were depressed in both wild-type and iNOS-deficient mice after burn injury. Gene disruption of iNOS ameliorated the effect of burn on IRS-1-mediated insulin signaling in skeletal muscle of mice. These findings indicate that iNOS plays a significant role in burn injury-induced skeletal muscle insulin resistance.
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Affiliation(s)
- Michiko Sugita
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Hiroki Sugita
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Minhye Kim
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Ji Mao
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Yoshikazu Yasuda
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Mayu Habiro
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Shohei Shinozaki
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Shingo Yasuhara
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Nobuyuki Shimizu
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - J.A. Jeevendra Martyn
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
| | - Masao Kaneki
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Shriners Hospitals for Children, Boston, MA 02114, USA
- Corresponding author. Masao Kaneki; Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, 149 Thirteenth Street, Charlestown, MA 02129, USA, Phone: +1(617) 726-8122; Fax: +1(617) 726-8134;
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Lu XM, Tompkins RG, Fischman AJ. SILAM for quantitative proteomics of liver Akt1/PKBα after burn injury. Int J Mol Med 2011; 29:461-71. [PMID: 22179310 PMCID: PMC3981641 DOI: 10.3892/ijmm.2011.861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 11/17/2011] [Indexed: 12/27/2022] Open
Abstract
Akt1/protein kinase Bα (Akt1/PKBα) is a downstream mediator of the insulin signaling system. In this study we explored mechanism(s) for its role in burn injury. Akt1/PKBα in liver extracts from mice with burn injury fed with (2H7)-L-Leu was immunoprecipitated and isolated with SDS-PAGE. Two tryptic peptides, one in the kinase loop and a control peptide just outside of the loop were sequenced via nano-LC interfaced with quadruple time-of-flight tandem mass spectrometry (Q-TOF tandem MS). Their relative isotopologue abundances were determined by stable isotope labeling by amino acids in mammalians (SILAM). Relative quantifications based on paired heavy/light peptides were obtained in 3 steps. The first step included homogenization of mixtures of equal amounts of tissue from burned and sham-treated animals (i.e., isotope dilution) and acquisition of uncorrected data based on parent monoisotopic MS ion ratios. The second step included determination of isotopic enrichment of the kinase from burned mice on Day 7 and the third step enrichment correction of partially labeled heavy and light monoisotopic MS ion ratios for relative quantification of bioactivity (loop peptide) and expression level (control peptide). Protein synthesis and enrichment after injury were found to be dependent on tissue and turnover of individual proteins. Three heavy and light monoisotopic ion ratios for albumin peptides from burned mice indicated ~55% enrichment and ~16.7-fold downregulation. In contract, serum amyloid P had ~66% enrichment and was significantly upregulated. Akt1/PKBα had ~56% enrichment and kinase level in response to the burn injury was upregulated compared with the control peptide. However, kinase bioactivity, represented by the Cys296 peptide, was significantly reduced. Overall, we demonstrated that i) quantitative proteomics can be performed without completely labeled mice; ii) measurement of enrichment of acyl-tRNAs is unnecessary and iii) Cys296 plays an important role in kinase activity after burn injury.
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Affiliation(s)
- X-M Lu
- Massachusetts General Hospital, Boston, MA, USA
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Insulin-Mediated Inhibition of p38 Mitogen-Activated Protein Kinase Protects Cardiomyocytes in Severe Burns. J Burn Care Res 2011; 32:591-9. [DOI: 10.1097/bcr.0b013e31822dc3f2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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de Betue CT, van Waardenburg DA, Deutz NE, van Eijk HM, van Goudoever JB, Luiking YC, Zimmermann LJ, Joosten KF. Increased protein-energy intake promotes anabolism in critically ill infants with viral bronchiolitis: a double-blind randomised controlled trial. Arch Dis Child 2011; 96:817-22. [PMID: 21673183 PMCID: PMC3155119 DOI: 10.1136/adc.2010.185637] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The preservation of nutritional status and growth is an important aim in critically ill infants, but difficult to achieve due to the metabolic stress response and inadequate nutritional intake, leading to negative protein balance. This study investigated whether increasing protein and energy intakes can promote anabolism. The primary outcome was whole body protein balance, and the secondary outcome was first pass splanchnic phenylalanine extraction (SPE(Phe)). DESIGN This was a double-blind randomised controlled trial. Infants (n=18) admitted to the paediatric intensive care unit with respiratory failure due to viral bronchiolitis were randomised to continuous enteral feeding with protein and energy enriched formula (PE-formula) (n=8; 3.1 ± 0.3 g protein/kg/24 h, 119 ± 25 kcal/kg/24 h) or standard formula (S-formula) (n=10; 1.7 ± 0.2 g protein/kg/24 h, 84 ± 15 kcal/kg/24 h; equivalent to recommended intakes for healthy infants <6 months). A combined intravenous-enteral phenylalanine stable isotope protocol was used on day 5 after admission to determine whole body protein metabolism and SPE(Phe). RESULTS Protein balance was significantly higher with PE-formula than with S-formula (PE-formula: 0.73 ± 0.5 vs S-formula: 0.02 ± 0.6 g/kg/24 h) resulting from significantly increased protein synthesis (PE-formula: 9.6 ± 4.4, S-formula: 5.2 ± 2.3 g/kg/24 h), despite significantly increased protein breakdown (PE-formula: 8.9 ± 4.3, S-formula: 5.2 ± 2.6 g/kg/24 h). SPE(Phe) was not statistically different between the two groups (PE-formula: 39.8 ± 18.3%, S-formula: 52.4 ± 13.6%). CONCLUSIONS Increasing protein and energy intakes promotes protein anabolism in critically ill infants in the first days after admission. Since this is an important target of nutritional support, increased protein and energy intakes should be preferred above standard intakes in these infants. Dutch Trial Register number: NTR 515.
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Affiliation(s)
- Carlijn T de Betue
- Department of Paediatrics, Maastricht University Medical Center, Maastricht, The Netherlands,Currently working: Department of Paediatric Surgery, ErasmusMC-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Dick A van Waardenburg
- Department of Paediatrics, Maastricht University Medical Center, Maastricht, The Netherlands,Department of Paediatric Surgery, Erasmus MC– Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Nicolaas E Deutz
- Department of Surgery, Maastricht University Medical Center, Maastricht, the Netherlands,Currently working: Center for Translational Research in Aging and Longevity, Donald W Reynolds Insitute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Hans M van Eijk
- Department of Surgery, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Johannes B van Goudoever
- Department of Paedatrics, VU University Medical Center, Amsterdam, the Netherlands,Department of Paediatrics, Emma Children's Hospital-AMC, Amsterdam, the Netherlands,Department of Paediatrics, ErasmusMC-Sophia Children's Hospital, Rotterdam, the Netherlands
| | - Yvette C Luiking
- Currently working: Department of Paediatric Surgery, ErasmusMC-Sophia Children's Hospital, Rotterdam, The Netherlands,Department of Surgery, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Luc J Zimmermann
- Department of Paediatric Surgery, Erasmus MC– Sophia Children's Hospital, Rotterdam, The Netherlands
| | - Koen F Joosten
- Department of Paediatrics, ErasmusMC-Sophia Children's Hospital, Rotterdam, the Netherlands
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Blockade of the Renin-Angiotensin system improves insulin receptor signaling and insulin-stimulated skeletal muscle glucose transport in burn injury. Shock 2011; 35:80-5. [PMID: 20823693 DOI: 10.1097/shk.0b013e3181e762da] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Burn injury is associated with a decline in glucose utilization and insulin sensitivity due to alterations in postreceptor insulin signaling pathways. We have reported that blockade of the renin-angiotensin system with losartan, an angiotensin II type 1 (AT1) receptor blocker, improves whole body insulin sensitivity and glucose metabolism after burn injury. This study examines whether losartan improves insulin signaling pathways and insulin-stimulated glucose transport in skeletal muscle in burn-injured rats. Rats were injured by a 30% full-skin-thickness scalding burn and treated with losartan or placebo for 3 days after burn. Insulin signaling pathways were investigated in rectus abdominus muscle taken before and 90 s after intraportal insulin injection (10 U·kg). Insulin-stimulated insulin receptor substrate 1-associated phosphatidylinositol 3-kinase and plasma membrane-associated GLUT4 transporter were substantially increased with losartan treatment in burn-injured animals (59% above sham). Serine phosphorylated AKT/PKB was decreased with burn injury, and this decrease was attenuated with losartan treatment. In a separate group of rats, the effect of insulin on 2-deoxyglucose transport was significantly impaired in burned as compared with sham soleus muscles, in vitro; however, treatment of burned rats with losartan completely abolished the reduction of insulin-stimulated 2-deoxyglucose transport. These findings demonstrate a cross talk between the AT1 and insulin receptor that negatively modulates insulin receptor signaling and suggest a potential role of renin-angiotensin system blockade as a therapeutic strategy for enhancing insulin sensitivity in skeletal muscle and improving whole-body glucose homeostasis in burn injury.
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Rüegg MA, Glass DJ. Molecular mechanisms and treatment options for muscle wasting diseases. Annu Rev Pharmacol Toxicol 2011; 51:373-95. [PMID: 20936944 DOI: 10.1146/annurev-pharmtox-010510-100537] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Loss of muscle mass can be the consequence of pathological changes, as observed in muscular dystrophies; or it can be secondary to cachexia-inducing diseases that cause muscle atrophy, such as cancer, heart disease, or chronic obstructive pulmonary disease; or it can be a consequence of aging or simple disuse. Although muscular dystrophies are rare, muscle loss affects millions of people worldwide. We discuss the molecular mechanisms involved in muscular dystrophy and in muscle atrophy and present current strategies aimed at ameliorating these diseases. Finally, we discuss whether lessons learned from studying muscular dystrophies will also be helpful for halting muscle loss secondary to nondystrophic diseases and whether strategies to halt muscle atrophy have potential for the treatment of muscular dystrophies.
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Jespersen JG, Nedergaard A, Reitelseder S, Mikkelsen UR, Dideriksen KJ, Agergaard J, Kreiner F, Pott FC, Schjerling P, Kjaer M. Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients. PLoS One 2011; 6:e18090. [PMID: 21483870 PMCID: PMC3069050 DOI: 10.1371/journal.pone.0018090] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 02/20/2011] [Indexed: 12/25/2022] Open
Abstract
Background Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR), glycogen synthase kinase 3β (GSK3β) and forkhead box O (FoxO) pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU) patients compared with healthy controls. Methodology/Principal Findings ICU patients were systemically inflamed, moderately hyperglycemic, received insulin therapy, and showed a tendency to lower plasma branched chain amino acids compared with controls. Using Western blotting we measured Akt, GSK3β, mTOR, ribosomal protein S6 kinase (S6k), eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1), and muscle ring finger protein 1 (MuRF1); and by RT-PCR we determined mRNA expression of, among others, insulin-like growth factor 1 (IGF-1), FoxO 1, 3 and 4, atrogin1, MuRF1, interleukin-6 (IL-6), tumor necrosis factor α (TNF-α) and myostatin. Unexpectedly, in critically ill ICU patients Akt-mTOR-S6k signaling was substantially higher compared with controls. FoxO1 mRNA was higher in patients, whereas FoxO3, atrogin1 and myostatin mRNAs and MuRF1 protein were lower compared with controls. A moderate correlation (r2 = 0.36, p<0.05) between insulin infusion dose and phosphorylated Akt was demonstrated. Conclusions/Significance We present for the first time muscle protein turnover signaling in critically ill ICU patients, and we show signaling pathway activity towards a stimulation of muscle protein synthesis and a somewhat inhibited proteolysis.
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Affiliation(s)
- Jakob G Jespersen
- Department of Orthopedic Surgery M, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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mTOR partly mediates insulin resistance by phosphorylation of insulin receptor substrate-1 on serine307 residues after burn. Burns 2011; 37:86-93. [DOI: 10.1016/j.burns.2010.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/09/2010] [Accepted: 04/05/2010] [Indexed: 11/20/2022]
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PI3 kinase regulation of skeletal muscle hypertrophy and atrophy. Curr Top Microbiol Immunol 2011; 346:267-78. [PMID: 20593312 DOI: 10.1007/82_2010_78] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Activation of the PI3 kinase pathway can induce skeletal muscle hypertrophy, defined as an increase in skeletal muscle mass. In mammals, skeletal muscle hypertrophy occurs as a result of an increase in the size, as opposed to the number, of pre-existing skeletal muscle fibers. This pathway's effects on skeletal muscle have been implicated most prominently downstream of Insulin-like growth factor 1 signaling. IGF-1's pro-hypertrophy activity comes predominantly through its ability to activate the Phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Akt is a serine-threonine protein kinase that can induce protein synthesis and block the transcriptional upregulation of key mediators of skeletal muscle atrophy, the E3 ubiquitin ligases MuRF1 and MAFbx (also called Atrogin-1), by phosphorylating and thereby inhibiting the nuclear translocation of the FOXO (also called "forkhead") family of transcription factors. Once phosphorylated by Akt, the FOXOs are excluded from the nucleus, and upregulation of MuRF1 and MAFbx is blocked. MuRF1 and MAFbx mediate atrophy by ubiquitinating particular protein substrates, causing them to undergo degradation by the proteasome. MuRF1's substrates include several components of the sarcomeric thick filament, including Myosin Heavy Chain (MyHC). Thus, by blocking MuRF1 activation, IGF-1 helps prevent the breakdown of the thick filament under atrophy conditions.IGF1/PI3K/Akt signaling also can dominantly inhibit the effects of a secreted protein called "myostatin," which is a member of the TGFβ family of proteins. Deletion or inhibition of myostatin causes an increase in skeletal muscle size, because myostatin acts both to inhibit myoblast differentiation and to block the Akt pathway. Thus by blocking myostatin, PI3K/Akt activation stimulates differentiation and protein synthesis by this distinct mechanism. Myostatin induces the phosphorylation and activation of the transcription factors of Smad2 and Smad3, downstream of the ActRII (Activin Receptor type II)/Alk (Activin Receptor-like kinase) receptor complex. Other TGFβ-like molecules can also block differentiation, including TGF-b1, GDF-11, activinA, BMP-2 and BMP-7. As mentioned, myostatin also downregulates the Akt/mTOR/p70S6 protein synthesis pathway, which mediates both differentiation in myoblasts and hypertrophy in myotubes. Blockade of the Akt/mTOR pathway, using siRNA to RAPTOR, a component of "TORC1" (TOR signaling Complex 1), increases myostatin-induced phosphorylation of Smad2; this establishes a "feed-forward mechanism," because myostatin can downregulates TORC1, and this downregulation in turn amplifies myostatin signaling. Blockade of RAPTOR also facilitates myostatin's inhibition of muscle differentiation. When added to post-differentiated myotubes, myostatin causes a decrease in their diameter - however, this does not happen through the normal "atrophy pathway." Rather than causing upregulation of the E3 ubiquitin ligases MuRF1 and MAFbx, previously shown to mediate skeletal muscle atrophy, myostatin decreases expression of these atrophy markers in differentiated myotubes, as well as other genes normally upregulated during differentiation, such as MyoD and myogenin. These findings show that myostatin signaling acts by blocking genes induced during differentiation, even in a myotube, as opposed to activating the distinct "atrophy program."
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Glucose metabolism in burn patients: The role of insulin and other endocrine hormones. Burns 2010; 36:599-605. [DOI: 10.1016/j.burns.2009.11.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 07/24/2009] [Accepted: 11/11/2009] [Indexed: 01/08/2023]
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Abstract
PURPOSE OF REVIEW To discuss the mechanisms of muscle loss during cachexia. RECENT FINDINGS Cachexia can be defined as a wasting of lean body mass that cannot be reversed nutrionally, indicating a dysregulation in the pathways maintaining body composition. In skeletal muscle, during cachexia, there is an upregulation of protein degradation. A search for transcriptional markers of muscle atrophy led to the discovery of the E3 ubiquitin ligases MuRF1 and MAFbx (also called Atrogin-1). These genes are upregulated in multiple models of atrophy and cachexia. They target particular protein substrates for degradation via the ubiquitin/proteasome pathway. The insulin-like growth factor-1 can block the transcriptional upregulation of MuRF1 and MAFbx via the phosphatidylinositol-3 kinase/Akt/Foxo pathway. MuRF1's substrates include several components of the sarcomeric thick filament, including myosin heavy chain. Thus, by blocking MuRF1, insulin-like growth factor-1 prevents the breakdown of the thick filament, particularly myosin heavy chain, which is asymmetrically lost in settings of cortisol-linked skeletal muscle atrophy. Insulin-like growth factor-1/phosphatidylinositol-3 kinase/Akt signaling also dominantly inhibits the effects of myostatin, which is a member of the transforming growth factor-[beta] family of proteins. Deletion or inhibition of myostatin causes a significant increase in skeletal muscle size. Recently, myostatin has been shown to act both by inhibiting gene activation associated with differentiation, even when applied to postdifferentiated myotubes, and by blocking the phosphatidylinositol-3 kinase/Akt pathway. SUMMARY These findings will help to define strategies to treat cachexia.
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Affiliation(s)
- David J Glass
- Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA.
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