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Yang JM, Han IS, Chen TH, Hsieh PS, Tsai MC, Chien HC. Pharmacological activation of pyruvate dehydrogenase by dichloroacetate protects against obesity-induced muscle atrophy in vitro and in vivo. Eur J Pharmacol 2024; 979:176854. [PMID: 39059568 DOI: 10.1016/j.ejphar.2024.176854] [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: 05/26/2024] [Revised: 07/01/2024] [Accepted: 07/24/2024] [Indexed: 07/28/2024]
Abstract
Obesity-induced muscle atrophy leads to physical impairment and metabolic dysfunction, which are risky for older adults. The activity of pyruvate dehydrogenase (PDH), a critical regulator of glucose metabolism, is reduced in obesity. Additionally, PDH activator dichloroacetate (DCA) improves metabolic dysfunction. However, the effects of PDH activation on skeletal muscles in obesity remain unclear. Thus, this study aimed to evaluate the effects of PDH activation by DCA treatment on obesity-induced muscle atrophy in vitro and in vivo and elucidate the possible underlying mechanisms. Results showed that PDH activation by DCA treatment ameliorated muscle loss, decreased the cross-sectional area, and reduced grip strength in C57BL/6 mice fed a high-fat diet (HFD). Elevation of muscle atrophic factors atrogin-1 and muscle RING-finger protein-1 (MuRF-1) and autophagy factors LC3BII and p62 were abrogated by DCA treatment in palmitate-treated C2C12 myotubes and in the skeletal muscles of HFD-fed mice. Moreover, p-Akt, p-FoxO1, and p-FoxO3 protein levels were reduced and p-NF-κB p65 and p-p38 MAPK protein levels were elevated in palmitate-treated C2C12 myotubes, which were restored by DCA treatment. However, the protective effects of DCA treatment against myotube atrophy were reversed by treatment with Akt inhibitor MK2206. Taken together, our study demonstrated that PDH activation by DCA treatment can alleviate obesity-induced muscle atrophy. It may serve as a basis for developing novel strategies to prevent obesity-associated muscle loss.
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Affiliation(s)
- Jung-Mou Yang
- Department of Emergency, Cardinal Tien Hospital, New Taipei City, Taiwan
| | - I-Shan Han
- Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan
| | - Tsung-Hua Chen
- Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan
| | - Po-Shiuan Hsieh
- Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan
| | - Min-Chien Tsai
- Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan
| | - Hung-Che Chien
- Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan.
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2
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Sato R, Vatic M, Peixoto da Fonseca GW, Anker SD, von Haehling S. Biological basis and treatment of frailty and sarcopenia. Cardiovasc Res 2024:cvae073. [PMID: 38828887 DOI: 10.1093/cvr/cvae073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 11/23/2022] [Accepted: 12/20/2022] [Indexed: 06/05/2024] Open
Abstract
In an ageing society, the importance of maintaining healthy life expectancy has been emphasized. As a result of age-related decline in functional reserve, frailty is a state of increased vulnerability and susceptibility to adverse health outcomes with a serious impact on healthy life expectancy. The decline in skeletal muscle mass and function, also known as sarcopenia, is key in the development of physical frailty. Both frailty and sarcopenia are highly prevalent in patients not only with advanced age but also in patients with illnesses that exacerbate their progression like heart failure (HF), cancer, or dementia, with the prevalence of frailty and sarcopenia in HF patients reaching up to 50-75% and 19.5-47.3%, respectively, resulting in 1.5-3 times higher 1-year mortality. The biological mechanisms of frailty and sarcopenia are multifactorial, complex, and not yet fully elucidated, ranging from DNA damage, proteostasis impairment, and epigenetic changes to mitochondrial dysfunction, cellular senescence, and environmental factors, many of which are further linked to cardiac disease. Currently, there is no gold standard for the treatment of frailty and sarcopenia, however, growing evidence supports that a combination of exercise training and nutritional supplement improves skeletal muscle function and frailty, with a variety of other therapies being devised based on the underlying pathophysiology. In this review, we address the involvement of frailty and sarcopenia in cardiac disease and describe the latest insights into their biological mechanisms as well as the potential for intervention through exercise, diet, and specific therapies.
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Affiliation(s)
- Ryosuke Sato
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
| | - Mirela Vatic
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
| | - Guilherme Wesley Peixoto da Fonseca
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Stefan D Anker
- Department of Cardiology (CVK) of German Heart Center Charité; German Centre for Cardiovascular Research (DZHK) partner site Berlin, Charité Universitätsmedizin, Berlin, Germany
- Institute of Heart Diseases, Wroclaw Medical University, Wroclaw, Poland
| | - Stephan von Haehling
- Department of Cardiology and Pneumology, University of Göttingen Medical Center, Robert-Koch-Str. 40, 37075 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), partner site Göttingen, Göttingen, Germany
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3
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Neelam PB, Sharma A, Sharma V. Sarcopenia and frailty in inflammatory bowel disease: Emerging concepts and evidence. JGH Open 2024; 8:e13033. [PMID: 38283070 PMCID: PMC10821747 DOI: 10.1002/jgh3.13033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/01/2024] [Accepted: 01/05/2024] [Indexed: 01/30/2024]
Abstract
Sarcopenia is a condition marked by progressive loss of skeletal muscle mass and function while frailty is a multidimensional concept characterized by diminished physiological reserve and increased vulnerability to stressors. Both of these were previously considered as related to aging and shown to impact the quality of life and carry prognostic significance. Emerging data show that both sarcopenia and frailty carry similar relevance in chronic illness. Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and malnourishment, both of which contribute to the development of sarcopenia by increasing protein breakdown and reducing protein synthesis. The coexistence of frailty further compounds the clinical complexity of IBD patients. Published evidence suggests a bidirectional association with IBD contributing to muscle wasting, while the resultant sarcopenia and frailty could further exacerbate the disease course. Sarcopenia and frailty are independently associated with adverse outcomes, including hospitalizations, increased surgical interventions, and surgical complications. As therapeutic strategies for IBD evolve, understanding the nuanced relationship between inflammatory bowel disease, sarcopenia, and frailty is crucial for devising holistic management. Comprehensive care should encompass not only disease-modifying therapies but also interventions targeting frailty and sarcopenia, as they have been shown to have a significant impact not only on the disease course but also on the quality of life. Future research could focus on further elucidating underlying mechanisms, simple screening strategies, and developing targeted interventions to improve the overall quality of life for individuals grappling with the complex interplay of IBD, sarcopenia, and frailty.
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Affiliation(s)
- Pardhu B Neelam
- Department of GastroenterologyPostgraduate Institute of Medical Education and ResearchChandigarhIndia
| | - Alka Sharma
- Department of MedicineDr. BR Ambedkar Institute of Medical SciencesMohaliIndia
| | - Vishal Sharma
- Department of GastroenterologyPostgraduate Institute of Medical Education and ResearchChandigarhIndia
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4
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Cao R, Tian H, Zhang Y, Liu G, Xu H, Rao G, Tian Y, Fu X. Signaling pathways and intervention for therapy of type 2 diabetes mellitus. MedComm (Beijing) 2023; 4:e283. [PMID: 37303813 PMCID: PMC10248034 DOI: 10.1002/mco2.283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/18/2023] [Accepted: 04/27/2023] [Indexed: 06/13/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.
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Affiliation(s)
- Rong Cao
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Huimin Tian
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Yu Zhang
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Geng Liu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Haixia Xu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Guocheng Rao
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Yan Tian
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Xianghui Fu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
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5
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Henrot P, Dupin I, Schilfarth P, Esteves P, Blervaque L, Zysman M, Gouzi F, Hayot M, Pomiès P, Berger P. Main Pathogenic Mechanisms and Recent Advances in COPD Peripheral Skeletal Muscle Wasting. Int J Mol Sci 2023; 24:ijms24076454. [PMID: 37047427 PMCID: PMC10095391 DOI: 10.3390/ijms24076454] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/14/2023] Open
Abstract
Chronic obstructive pulmonary disease (COPD) is a worldwide prevalent respiratory disease mainly caused by tobacco smoke exposure. COPD is now considered as a systemic disease with several comorbidities. Among them, skeletal muscle dysfunction affects around 20% of COPD patients and is associated with higher morbidity and mortality. Although the histological alterations are well characterized, including myofiber atrophy, a decreased proportion of slow-twitch myofibers, and a decreased capillarization and oxidative phosphorylation capacity, the molecular basis for muscle atrophy is complex and remains partly unknown. Major difficulties lie in patient heterogeneity, accessing patients' samples, and complex multifactorial process including extrinsic mechanisms, such as tobacco smoke or disuse, and intrinsic mechanisms, such as oxidative stress, hypoxia, or systemic inflammation. Muscle wasting is also a highly dynamic process whose investigation is hampered by the differential protein regulation according to the stage of atrophy. In this review, we report and discuss recent data regarding the molecular alterations in COPD leading to impaired muscle mass, including inflammation, hypoxia and hypercapnia, mitochondrial dysfunction, diverse metabolic changes such as oxidative and nitrosative stress and genetic and epigenetic modifications, all leading to an impaired anabolic/catabolic balance in the myocyte. We recapitulate data concerning skeletal muscle dysfunction obtained in the different rodent models of COPD. Finally, we propose several pathways that should be investigated in COPD skeletal muscle dysfunction in the future.
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Affiliation(s)
- Pauline Henrot
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
- CHU de Bordeaux, Service d'Exploration Fonctionnelle Respiratoire, CIC 1401, Service de Pneumologie, F-33604 Pessac, France
| | - Isabelle Dupin
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
| | - Pierre Schilfarth
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
- CHU de Bordeaux, Service d'Exploration Fonctionnelle Respiratoire, CIC 1401, Service de Pneumologie, F-33604 Pessac, France
| | - Pauline Esteves
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
| | - Léo Blervaque
- PhyMedExp, INSERM-CNRS-Montpellier University, F-34090 Montpellier, France
| | - Maéva Zysman
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
- CHU de Bordeaux, Service d'Exploration Fonctionnelle Respiratoire, CIC 1401, Service de Pneumologie, F-33604 Pessac, France
| | - Fares Gouzi
- PhyMedExp, INSERM-CNRS-Montpellier University, CHRU Montpellier, F-34090 Montpellier, France
| | - Maurice Hayot
- PhyMedExp, INSERM-CNRS-Montpellier University, CHRU Montpellier, F-34090 Montpellier, France
| | - Pascal Pomiès
- PhyMedExp, INSERM-CNRS-Montpellier University, F-34090 Montpellier, France
| | - Patrick Berger
- Centre de Recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, F-33604 Pessac, France
- INSERM, Centre de Recherche Cardio-Thoracique de Bordeaux, U1045, CIC 1401, F-33604 Pessac, France
- CHU de Bordeaux, Service d'Exploration Fonctionnelle Respiratoire, CIC 1401, Service de Pneumologie, F-33604 Pessac, France
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6
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Hayashi K, Labios RJ, Morita T, Ashimori A, Aoki R, Mikuni M, Kimura K. Significance of the p38MAPK-CRP2 axis in myofibroblastic phenotypic transition. Cell Struct Funct 2023; 48:199-210. [PMID: 37899269 DOI: 10.1247/csf.23060] [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] [Indexed: 10/31/2023] Open
Abstract
We have recently demonstrated that a LIM domain protein, cysteine and glycine-rich protein 2 (CSRP2 [CRP2]), plays a vital role in the functional expression of myofibroblasts and cancer-associated fibroblasts. CRP2 binds directly to myocardin-related transcription factors (MRTF [MRTF-A or MRTF-B]) and serum response factor (SRF) to stabilize the MRTF/SRF/CArG-box complex, leading to the expression of smooth muscle cell (SMC) genes such as α-smooth muscle actin (α-SMA) and collagens. These are the marker genes for myofibroblasts. Here, we show that the adhesion of cultured human skin fibroblasts (HSFs) to collagen reduces the myofibroblastic features. HSF adhesion to collagen suppresses the expression of CRP2 and CSRP2-binding protein (CSRP2BP [CRP2BP]) and reduces the expression of SMC genes. Although CRP2BP is known as an epigenetic factor, we find that CRP2BP also acts as an adaptor protein to enhance the function of CRP2 mentioned above. This CRP2BP function does not depend on its histone acetyltransferase activity. We also addressed the molecular mechanism of the reduced myofibroblastic features of HSFs on collagen. HSF adhesion to collagen inhibits the p38MAPK-mediated pathway, and reducing the p38MAPK activity decreases the expression of CRP2 and SMC genes. Thus, the activation of p38MAPK is critical for the myofibroblastic features. We also show evidence that CRP2 plays a role in the myofibroblastic transition of retinal pigment epithelial cells (RPEs). Like HSFs, such phenotypic modulation of RPEs depends on the p38MAPK pathway.Key words: CRP2, p38MAPK, MRTF, myofibroblasts, retinal pigment epithelial cells.
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Affiliation(s)
- Ken'ichiro Hayashi
- Department of RNA Biology and Neuroscience, Osaka University Graduate School of Medicine
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine
| | - Reuben Jacob Labios
- Department of RNA Biology and Neuroscience, Osaka University Graduate School of Medicine
| | - Tsuyoshi Morita
- Department of Biology, Wakayama Medical University School of Medicine
| | - Atsushige Ashimori
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine
| | - Ren Aoki
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine
| | - Masanori Mikuni
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine
| | - Kazuhiro Kimura
- Department of Ophthalmology, Yamaguchi University Graduate School of Medicine
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Zhou X, Zhang C, Wu X, Hu X, Zhang Y, Wang X, Zheng L, Gao P, Du J, Zheng W, Shang H, Hu K, Jiang Z, Nie Y, Hu S, Xiao RP, Zhu X, Xiong JW. Dusp6 deficiency attenuates neutrophil-mediated cardiac damage in the acute inflammatory phase of myocardial infarction. Nat Commun 2022; 13:6672. [PMID: 36335128 PMCID: PMC9637103 DOI: 10.1038/s41467-022-33631-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 09/27/2022] [Indexed: 11/07/2022] Open
Abstract
Dual-specificity phosphatase 6 (DUSP6) serves a specific and conserved function on the dephosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). We previously identified Dusp6 as a regenerative repressor during zebrafish heart regeneration, therefore we propose to investigate the role of this repressor in mammalian cardiac repair. Utilizing a rat strain harboring Dusp6 nonsense mutation, rat neutrophil-cardiomyocyte co-culture, bone marrow transplanted rats and neutrophil-specific Dusp6 knockout mice, we find that Dusp6 deficiency improves cardiac outcomes by predominantly attenuating neutrophil-mediated myocardial damage in acute inflammatory phase after myocardial infarction. Mechanistically, Dusp6 is transcriptionally activated by p38-C/EBPβ signaling and acts as an effector for maintaining p-p38 activity by down-regulating pERK and p38-targeting phosphatases DUSP1/DUSP16. Our findings provide robust animal models and novel insights for neutrophil-mediated cardiac damage and demonstrate the potential of DUSP6 as a therapeutic target for post-MI cardiac remodeling and other relevant inflammatory diseases.
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Affiliation(s)
- Xiaohai Zhou
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Chenyang Zhang
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319PKU-Nanjing Institute of Translational Medicine, Nanjing, 211800 China
| | - Xueying Wu
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Xinli Hu
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Yan Zhang
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Xuelian Wang
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Lixia Zheng
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Peng Gao
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Jianyong Du
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Wen Zheng
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Haibao Shang
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China
| | - Keping Hu
- grid.506261.60000 0001 0706 7839Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193 China
| | - Zhengfan Jiang
- grid.11135.370000 0001 2256 9319School of Life Sciences, Peking University, Beijing, 100871 China
| | - Yu Nie
- grid.506261.60000 0001 0706 7839State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037 China
| | - Shengshou Hu
- grid.506261.60000 0001 0706 7839State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037 China
| | - Rui-Ping Xiao
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319PKU-Nanjing Institute of Translational Medicine, Nanjing, 211800 China
| | - Xiaojun Zhu
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319PKU-Nanjing Institute of Translational Medicine, Nanjing, 211800 China
| | - Jing-Wei Xiong
- grid.11135.370000 0001 2256 9319Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319PKU-Nanjing Institute of Translational Medicine, Nanjing, 211800 China
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8
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Gao S, Zhang G, Zhang Z, Zhu JZ, Li L, Zhou Y, Rodney GG, Abo-Zahrah RS, Anderson L, Garcia JM, Kwon YT, Li YP. UBR2 targets myosin heavy chain IIb and IIx for degradation: Molecular mechanism essential for cancer-induced muscle wasting. Proc Natl Acad Sci U S A 2022; 119:e2200215119. [PMID: 36252004 PMCID: PMC9618047 DOI: 10.1073/pnas.2200215119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 08/06/2022] [Indexed: 11/18/2022] Open
Abstract
Cancer cachexia is a lethal metabolic syndrome featuring muscle wasting with preferential loss of fast-twitching muscle mass through an undefined mechanism. Here, we show that cancer induces muscle wasting by selectively degrading myosin heavy chain (MHC) subtypes IIb and IIx through E3 ligase UBR2-mediated ubiquitylation. Induction of MHC loss and atrophy in C2C12 myotubes and mouse tibialis anterior (TA) by murine cancer cells required UBR2 up-regulation by cancer. Genetic gain or loss of UBR2 function inversely altered MHC level and muscle mass in TA of tumor-free mice. UBR2 selectively interacted with and ubiquitylated MHC-IIb and MHC-IIx through its substrate recognition and catalytic domain, respectively, in C2C12 myotubes. Elevation of UBR2 in muscle of tumor-bearing or free mice caused loss of MHC-IIb and MHC-IIx but not MHC-I and MHC-IIa or other myofibrillar proteins, including α-actin, troponin, tropomyosin, and tropomodulin. Muscle-specific knockout of UBR2 spared KPC tumor-bearing mice from losing MHC-IIb and MHC-IIx, fast-twitching muscle mass, cross-sectional area, and contractile force. The rectus abdominis (RA) muscle of patients with cachexia-prone cancers displayed a selective reduction of MHC-IIx in correlation with higher UBR2 levels. These data suggest that UBR2 is a regulator of MHC-IIb/IIx essential for cancer-induced muscle wasting, and that therapeutic interventions can be designed by blocking UBR2 up-regulation by cancer.
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Affiliation(s)
- Song Gao
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Zicheng Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - James Z. Zhu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Li Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Yong Zhou
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - George G. Rodney
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030
| | - Reem S. Abo-Zahrah
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030
| | - Lindsey Anderson
- Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, Seattle, WA98018
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA98108
| | - Jose M. Garcia
- Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System, Seattle, WA98018
- Department of Medicine, Division of Gerontology and Geriatric Medicine, University of Washington, Seattle, WA98108
| | - Yong Tae Kwon
- World Class University Program, Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology and College of Medicine, Seoul National University, Seoul 110-799, Korea
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030
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9
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Wu HY, Trevino JG, Fang BL, Riner AN, Vudatha V, Zhang GH, Li YP. Patient-Derived Pancreatic Cancer Cells Induce C2C12 Myotube Atrophy by Releasing Hsp70 and Hsp90. Cells 2022; 11:cells11172756. [PMID: 36078164 PMCID: PMC9455268 DOI: 10.3390/cells11172756] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 12/02/2022] Open
Abstract
Pancreatic cancer (PC) patients are highly prone to cachexia, a lethal wasting syndrome featuring muscle wasting with an undefined etiology. Recent data indicate that certain murine cancer cells induce muscle wasting by releasing Hsp70 and Hsp90 through extracellular vesicles (EVs) to activate p38β MAPK-mediated catabolic pathways primarily through Toll-like receptor 4 (TLR4). However, whether human PC induces cachexia through releasing Hsp70 and Hsp90 is undetermined. Here, we investigated whether patient-derived PC cells induce muscle cell atrophy directly through this mechanism. We compared cancer cells isolated from patient-derived xenografts (PDX) from three PC patients who had cachexia (PCC) with those of three early-stage lung cancer patients without cachexia (LCC) and two renal cancer patients who were not prone to cachexia (RCC). We observed small increases of Hsp70 and Hsp90 released by LCC and RCC in comparison to non-cancer control cells (NCC). However, PCC released markedly higher levels of Hsp70 and Hsp90 (~ 6-fold on average) than LCC and RCC. In addition, PCC released similarly increased levels of Hsp70/90-containing EVs. In contrast to RCC and LCC, PCC-conditioned media induced a potent catabolic response in C2C12 myotubes including the activation of p38 MAPK and transcription factor C/EBPβ, upregulation of E3 ligases UBR2 and MAFbx, and increase of autophagy marker LC3-II, resulting in the loss of the myosin heavy chain (MHC ~50%) and myotube diameter (~60%). Importantly, the catabolic response was attenuated by Hsp70- and Hsp90-neutralizing antibodies in a dose-dependent manner. These data suggest that human PC cells release high levels of Hsp70 and Hsp90 that induce muscle atrophy through a direct action on muscle cells.
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Affiliation(s)
- Hong-Yu Wu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX 77030, USA
| | - Jose G. Trevino
- Department of Surgery, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Bing-Liang Fang
- Department of Thoracic and Cardiovascular Surgery, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrea N. Riner
- Department of Surgery, University of Florida, Gainesville, FL 32611, USA
| | - Vignesh Vudatha
- Department of Surgery, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Guo-Hua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX 77030, USA
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth Houston), Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-(713)-500-6498; Fax: +1-(713)-500-0689
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10
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Zhang G, Anderson LJ, Gao S, Sin TK, Zhang Z, Wu H, Jafri SH, Graf SA, Wu PC, Dash A, Garcia JM, Li YP. Weight Loss in Cancer Patients Correlates With p38β MAPK Activation in Skeletal Muscle. Front Cell Dev Biol 2021; 9:784424. [PMID: 34950660 PMCID: PMC8688918 DOI: 10.3389/fcell.2021.784424] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/15/2021] [Indexed: 11/15/2022] Open
Abstract
Unintentional weight loss, a first clinical sign of muscle wasting, is a major threat to cancer survival without a defined etiology. We previously identified in mice that p38β MAPK mediates cancer-induced muscle wasting by stimulating protein catabolism. However, whether this mechanism is relevant to humans is unknown. In this study, we recruited men with cancer and weight loss (CWL) or weight stable (CWS), and non-cancer controls (NCC), who were consented to rectus abdominis (RA) biopsy and blood sampling (n = 20/group). In the RA of both CWS and CWL, levels of activated p38β MAPK and its effectors in the catabolic pathways were higher than in NCC, with progressively higher active p38β MAPK detected in CWL. Remarkably, levels of active p38β MAPK correlated with weight loss. Plasma analysis for factors that activate p38β MAPK revealed higher levels in some cytokines as well as Hsp70 and Hsp90 in CWS and/or CWL. Thus, p38β MAPK appears a biomarker of weight loss in cancer patients.
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Affiliation(s)
- Guohua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
| | - Lindsey J Anderson
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Health Care System, Seattle, WA, United States.,Department of Medicine, Division of Gerontology and Geriatric Medicine, Seattle, WA, United States
| | - Song Gao
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
| | - Thomas K Sin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
| | - Zicheng Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
| | - Hongyu Wu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
| | - Syed H Jafri
- Department of Medicine, Section of Oncology, University of Texas Health Science Center, Houston, TX, United States
| | - Solomon A Graf
- Division of Medical Oncology, University of Washington School of Medicine, Seattle, WA, United States
| | - Peter C Wu
- Department of Surgery, University of Washington School of Medicine, Seattle, WA, United States.,Department of Surgery, Veterans Affairs Puget Sound Health Care System (VAPSHCS), Seattle, WA, United States
| | - Atreya Dash
- Department of Surgery, Veterans Affairs Puget Sound Health Care System (VAPSHCS), Seattle, WA, United States.,Department of Urology, Veterans Affairs Puget Sound Health Care System (VAPSHCS), Seattle, WA, United States
| | - Jose M Garcia
- Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Health Care System, Seattle, WA, United States.,Department of Medicine, Division of Gerontology and Geriatric Medicine, Seattle, WA, United States
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, United States
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11
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X-ray Diffraction Analysis to Explore Molecular Traces of Eccentric Contraction on Rat Skeletal Muscle Parallelly Evaluated with Signal Protein Phosphorylation Levels. Int J Mol Sci 2021; 22:ijms222312644. [PMID: 34884453 PMCID: PMC8657589 DOI: 10.3390/ijms222312644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/06/2021] [Accepted: 11/15/2021] [Indexed: 11/17/2022] Open
Abstract
We performed X-ray diffraction analyses on rat plantaris muscle to determine if there are strain-specific structural changes at the molecular level after eccentric contraction (ECC). ECC was elicited in situ by supramaximal electrical stimulation through the tibial nerve. One hour after a series of ECC sessions, the structural changes that remained in the sarcomere were evaluated using X-ray diffraction. Proteins involved in cell signaling pathways in the muscle were also examined. ECC elicited by 100, 75, and 50 Hz stimulation respectively developed peak tension of 1.34, 1.12 and 0.79 times the isometric maximal tetanus tension. The series of ECC sessions phosphorylated the forkhead box O proteins (FoxO) in a tension-time integral-dependent manner, as well as phosphorylated the mitogen-activated protein kinases (MAPK) and a protein in the mammalian target of rapamycin (mTOR) pathway in a maximal tension dependent manner. Compared to isometric contractions, ECC was more efficient in phosphorylating the signaling proteins. X-ray diffraction revealed that the myofilament lattice was preserved even after intense ECC stimulation at 100 Hz. Additionally, ECC < 75 Hz preserved the molecular alignment of myoproteins along the myofilaments, while 75-Hz stimulation induced a slight but significant decrease in the intensity of meridional troponin reflection at 1/38 nm−1, and of myosin reflection at 1/14.4 nm−1. These two reflections demonstrated no appreciable decrease with triple repetitions of the standard series of ECC sessions at 50 Hz, suggesting that the intensity decrease depended on the instantaneous maximal tension development rather than the total load of contraction, and was more likely linked with the phosphorylation of MAPK and mTOR signaling proteins.
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12
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Wiedmer P, Jung T, Castro JP, Pomatto LC, Sun PY, Davies KJ, Grune T. Sarcopenia - Molecular mechanisms and open questions. Ageing Res Rev 2021; 65:101200. [PMID: 33130247 DOI: 10.1016/j.arr.2020.101200] [Citation(s) in RCA: 166] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 12/12/2022]
Abstract
Sarcopenia represents a muscle-wasting syndrome characterized by progressive and generalized degenerative loss of skeletal muscle mass, quality, and strength occurring during normal aging. Sarcopenia patients are mainly suffering from the loss in muscle strength and are faced with mobility disorders reducing their quality of life and are, therefore, at higher risk for morbidity (falls, bone fracture, metabolic diseases) and mortality. Several molecular mechanisms have been described as causes for sarcopenia that refer to very different levels of muscle physiology. These mechanisms cover e. g. function of hormones (e. g. IGF-1 and Insulin), muscle fiber composition and neuromuscular drive, myo-satellite cell potential to differentiate and proliferate, inflammatory pathways as well as intracellular mechanisms in the processes of proteostasis and mitochondrial function. In this review, we describe sarcopenia as a muscle-wasting syndrome distinct from other atrophic diseases and summarize the current view on molecular causes of sarcopenia development as well as open questions provoking further research efforts for establishing efficient lifestyle and therapeutic interventions.
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13
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Sin TK, Zhang G, Zhang Z, Zhu JZ, Zuo Y, Frost JA, Li M, Li YP. Cancer-Induced Muscle Wasting Requires p38β MAPK Activation of p300. Cancer Res 2020; 81:885-897. [PMID: 33355181 DOI: 10.1158/0008-5472.can-19-3219] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/10/2020] [Accepted: 12/16/2020] [Indexed: 11/16/2022]
Abstract
Cancer-associated cachexia, characterized by muscle wasting, is a lethal metabolic syndrome without defined etiology or established treatment. We previously found that p300 mediates cancer-induced muscle wasting by activating C/EBPβ, which then upregulates key catabolic genes. However, the signaling mechanism that activates p300 in response to cancer is unknown. Here, we show that upon cancer-induced activation of Toll-like receptor 4 in skeletal muscle, p38β MAPK phosphorylates Ser-12 on p300 to stimulate C/EBPβ acetylation, which is necessary and sufficient to cause muscle wasting. Thus, p38β MAPK is a central mediator and therapeutic target of cancer-induced muscle wasting. In addition, nilotinib, an FDA-approved kinase inhibitor that preferentially binds p38β MAPK, inhibited p300 activation 20-fold more potently than the p38α/β MAPK inhibitor, SB202190, and abrogated cancer cell-induced muscle protein loss in C2C12 myotubes without suppressing p38α MAPK-dependent myogenesis. Systemic administration of nilotinib at a low dose (0.5 mg/kg/day, i.p.) in tumor-bearing mice not only alleviated muscle wasting, but also prolonged survival. Therefore, nilotinib appears to be a promising treatment for human cancer cachexia due to its selective inhibition of p38β MAPK. SIGNIFICANCE: These findings demonstrate that prevention of p38β MAPK-mediated activation of p300 by the FDA-approved kinase inhibitor, nilotinib, ameliorates cancer cachexia, representing a potential therapeutic strategy against this syndrome.
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Affiliation(s)
- Thomas K Sin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Zicheng Zhang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - James Z Zhu
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Yan Zuo
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Jeffrey A Frost
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Min Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas.,The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston, Houston, Texas.,Department of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.,Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas.
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14
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p38 MAPK in Glucose Metabolism of Skeletal Muscle: Beneficial or Harmful? Int J Mol Sci 2020; 21:ijms21186480. [PMID: 32899870 PMCID: PMC7555282 DOI: 10.3390/ijms21186480] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscles respond to environmental and physiological changes by varying their size, fiber type, and metabolic properties. P38 mitogen-activated protein kinase (MAPK) is one of several signaling pathways that drive the metabolic adaptation of skeletal muscle to exercise. p38 MAPK also participates in the development of pathological traits resulting from excessive caloric intake and obesity that cause metabolic syndrome and type 2 diabetes (T2D). Whereas p38 MAPK increases insulin-independent glucose uptake and oxidative metabolism in muscles during exercise, it contrastingly mediates insulin resistance and glucose intolerance during metabolic syndrome development. This article provides an overview of the apparent contradicting roles of p38 MAPK in the adaptation of skeletal muscles to exercise and to pathological conditions leading to glucose intolerance and T2D. Here, we focus on the involvement of p38 MAPK in glucose metabolism of skeletal muscle, and discuss the possibility of targeting this pathway to prevent the development of T2D.
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15
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Kassouf T, Sumara G. Impact of Conventional and Atypical MAPKs on the Development of Metabolic Diseases. Biomolecules 2020; 10:biom10091256. [PMID: 32872540 PMCID: PMC7563211 DOI: 10.3390/biom10091256] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/25/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
The family of mitogen-activated protein kinases (MAPKs) consists of fourteen members and has been implicated in regulation of virtually all cellular processes. MAPKs are divided into two groups, conventional and atypical MAPKs. Conventional MAPKs are further classified into four sub-families: extracellular signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK1, 2 and 3), p38 (α, β, γ, δ), and extracellular signal-regulated kinase 5 (ERK5). Four kinases, extracellular signal-regulated kinase 3, 4, and 7 (ERK3, 4 and 7) as well as Nemo-like kinase (NLK) build a group of atypical MAPKs, which are activated by different upstream mechanisms than conventional MAPKs. Early studies identified JNK1/2 and ERK1/2 as well as p38α as a central mediators of inflammation-evoked insulin resistance. These kinases have been also implicated in the development of obesity and diabetes. Recently, other members of conventional MAPKs emerged as important mediators of liver, skeletal muscle, adipose tissue, and pancreatic β-cell metabolism. Moreover, latest studies indicate that atypical members of MAPK family play a central role in the regulation of adipose tissue function. In this review, we summarize early studies on conventional MAPKs as well as recent findings implicating previously ignored members of the MAPK family. Finally, we discuss the therapeutic potential of drugs targeting specific members of the MAPK family.
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16
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Bodine SC. Edward F. Adolph Distinguished Lecture. Skeletal muscle atrophy: Multiple pathways leading to a common outcome. J Appl Physiol (1985) 2020; 129:272-282. [PMID: 32644910 DOI: 10.1152/japplphysiol.00381.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Skeletal muscle atrophy continues to be a serious consequence of many diseases and conditions for which there is no treatment. Our understanding of the mechanisms regulating skeletal muscle mass has improved considerably over the past two decades. For many years it was known that skeletal muscle atrophy resulted from an imbalance between protein synthesis and protein breakdown, with the net balance shifting toward protein breakdown. However, the molecular and cellular mechanisms underlying the increased breakdown of myofibrils was unknown. Over the past two decades, numerous reports have identified novel genes and signaling pathways that are upregulated and activated in response to stimuli such as disuse, inflammation, metabolic stress, starvation and others that induce muscle atrophy. This review summarizes the discovery efforts performed in the identification of several pathways involved in the regulation of skeletal muscle mass: the mammalian target of rapamycin (mTORC1) and the ubiquitin proteasome pathway and the E3 ligases, MuRF1 and MAFbx. While muscle atrophy is a common outcome of many diseases, it is doubtful that a single gene or pathway initiates or mediates the breakdown of myofibrils. Interestingly, however, is the observation that upregulation of the E3 ligases, MuRF1 and MAFbx, is a common feature of many divergent atrophy conditions. The challenge for the field of muscle biology is to understand how all of the various molecules, transcription factors, and signaling pathways interact to produce muscle atrophy and to identify the critical factors for intervention.
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Affiliation(s)
- Sue C Bodine
- Department of Internal Medicine/Endocrinology and Metabolism, University of Iowa Carver College of Medicine, Iowa City, Iowa
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17
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Lautaoja JH, Pekkala S, Pasternack A, Laitinen M, Ritvos O, Hulmi JJ. Differentiation of Murine C2C12 Myoblasts Strongly Reduces the Effects of Myostatin on Intracellular Signaling. Biomolecules 2020; 10:biom10050695. [PMID: 32365803 PMCID: PMC7277184 DOI: 10.3390/biom10050695] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 12/14/2022] Open
Abstract
Alongside in vivo models, a simpler and more mechanistic approach is required to study the effects of myostatin on skeletal muscle because myostatin is an important negative regulator of muscle size. In this study, myostatin was administered to murine (C2C12) and human (CHQ) myoblasts and myotubes. Canonical and noncanonical signaling downstream to myostatin, related ligands, and their receptor were analyzed. The effects of tumorkines were analyzed after coculture of C2C12 and colon cancer-C26 cells. The effects of myostatin on canonical and noncanonical signaling were strongly reduced in C2C12 cells after differentiation. This may be explained by increased follistatin, an endogenous blocker of myostatin and altered expression of activin receptor ligands. In contrast, CHQ cells were equally responsive to myostatin, and follistatin remained unaltered. Both myostatin administration and the coculture stimulated pathways associated with inflammation, especially in C2C12 cells. In conclusion, the effects of myostatin on intracellular signaling may be cell line- or organism-specific, and C2C12 myotubes seem to be a nonoptimal in vitro model for investigating the effects of myostatin on canonical and noncanonical signaling in skeletal muscle. This may be due to altered expression of activin receptor ligands and their regulators during muscle cell differentiation.
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Affiliation(s)
- Juulia H. Lautaoja
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä, 40014 Jyväskylä, Finland; (S.P.); (J.J.H.)
- Correspondence: ; Tel.: +358-40-805-5042
| | - Satu Pekkala
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä, 40014 Jyväskylä, Finland; (S.P.); (J.J.H.)
| | - Arja Pasternack
- Department of Physiology, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (A.P.); (O.R.)
| | - Mika Laitinen
- Department of Medicine, Faculty of Medicine, University of Helsinki, 00029 Helsinki, Finland;
- Department of Medicine, Helsinki University Hospital, 00029 Helsinki, Finland
| | - Olli Ritvos
- Department of Physiology, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (A.P.); (O.R.)
| | - Juha J. Hulmi
- Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä, 40014 Jyväskylä, Finland; (S.P.); (J.J.H.)
- Department of Physiology, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (A.P.); (O.R.)
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18
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Belova SP, Mochalova EP, Kostrominova TY, Shenkman BS, Nemirovskaya TL. P38α-MAPK Signaling Inhibition Attenuates Soleus Atrophy during Early Stages of Muscle Unloading. Int J Mol Sci 2020; 21:ijms21082756. [PMID: 32326654 PMCID: PMC7215762 DOI: 10.3390/ijms21082756] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 01/24/2023] Open
Abstract
To test the hypothesis that p38α-MAPK plays a critical role in the regulation of E3 ligase expression and skeletal muscle atrophy during unloading, we used VX-745, a selective p38α inhibitor. Three groups of rats were used: non-treated control (C), 3 days of unloading/hindlimb suspension (HS), and 3 days HS with VX-745 inhibitor (HSVX; 10 mg/kg/day). Total weight of soleus muscle in HS group was reduced compared to C (72.3 ± 2.5 vs 83.0 ± 3 mg, respectively), whereas muscle weight in the HSVX group was maintained (84.2 ± 5 mg). The expression of muscle RING-finger protein-1 (MuRF1) mRNA was significantly increased in the HS group (165%), but not in the HSVX group (127%), when compared with the C group. The expression of muscle-specific E3 ubiquitin ligases muscle atrophy F-box (MAFbx) mRNA was increased in both HS and HSVX groups (294% and 271%, respectively) when compared with C group. The expression of ubiquitin mRNA was significantly higher in the HS (423%) than in the C and HSVX (200%) groups. VX-745 treatment blocked unloading-induced upregulation of calpain-1 mRNA expression (HS: 120%; HSVX: 107%). These results indicate that p38α-MAPK signaling regulates MuRF1 but not MAFbx E3 ligase expression and inhibits skeletal muscle atrophy during early stages of unloading.
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Affiliation(s)
- Svetlana P. Belova
- Institute of Biomedical Problems, RAS, Moscow 123007, Russia; (S.P.B.); (E.P.M.); (B.S.S.)
| | - Ekaterina P. Mochalova
- Institute of Biomedical Problems, RAS, Moscow 123007, Russia; (S.P.B.); (E.P.M.); (B.S.S.)
| | - Tatiana Y. Kostrominova
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine-Northwest, Gary, IN 46408, USA;
| | - Boris S. Shenkman
- Institute of Biomedical Problems, RAS, Moscow 123007, Russia; (S.P.B.); (E.P.M.); (B.S.S.)
| | - Tatiana L. Nemirovskaya
- Institute of Biomedical Problems, RAS, Moscow 123007, Russia; (S.P.B.); (E.P.M.); (B.S.S.)
- Correspondence:
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19
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Guigni BA, van der Velden J, Kinsey CM, Carson JA, Toth MJ. Effects of conditioned media from murine lung cancer cells and human tumor cells on cultured myotubes. Am J Physiol Endocrinol Metab 2020; 318:E22-E32. [PMID: 31689144 PMCID: PMC6985792 DOI: 10.1152/ajpendo.00310.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Factors secreted from tumors/tumor cells are hypothesized to cause skeletal muscle wasting in cancer patients. We examined whether cancer cells secrete factors to promote atrophy by evaluating the effects of conditioned media (CM) from murine lung cancer cells and primary cultures of human lung tumor cells on cultured myotubes. We evaluated murine Lewis lung carcinoma (LLC) and KRASG12D cells, and primary cell lines derived from tumor biopsies from patients with lung cancer (hTCM; n = 6). In all experiments, serum content was matched across treatment groups. We hypothesized that CM from murine and human tumor cells would reduce myotube myosin content, decrease mitochondrial content, and increase mitochondrial reactive oxygen species (ROS) production. Treatment of myotubes differentiated for 7 days with CM from LLC and KRASG12D cells did not alter any of these variables. Effects of murine tumor cell CM were observed when myotubes differentiated for 4 days were treated with tumor cell CM and compared with undiluted differentiation media. However, these effects were not apparent if tumor cell CM treatments were compared with control cell CM or dilution controls. Finally, CM from human lung tumor primary cell lines did not modify myosin content or mitochondrial content or ROS production compared with either undiluted differentiated media, control cell CM, or dilution controls. Our results do not support the hypothesis that factors released from cultured lung cancer/tumor cells promote myotube wasting or mitochondrial abnormalities, but we cannot dismiss the possibility that these cells could secrete such factors in vivo within the native tumor microenvironment.
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MESH Headings
- Adenocarcinoma/metabolism
- Aged
- Aged, 80 and over
- Animals
- Cachexia/etiology
- Cachexia/metabolism
- Carcinoma, Lewis Lung/metabolism
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Squamous Cell/metabolism
- Cell Line, Tumor
- Culture Media, Conditioned/pharmacology
- Female
- Humans
- Lung Neoplasms/metabolism
- Male
- Mice
- Middle Aged
- Mitochondria, Muscle/drug effects
- Mitochondria, Muscle/metabolism
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Myoblasts, Skeletal
- Myosins/metabolism
- Neoplasms/complications
- Neoplasms/metabolism
- Primary Cell Culture
- Reactive Oxygen Species/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- Blas A Guigni
- Department of Medicine, College of Medicine, University of Vermont, Burlington, Vermont
- Department of Molecular Physiology and Biophysics, College of Medicine, University of Vermont, Burlington, Vermont
| | - Jos van der Velden
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Vermont, Burlington, Vermont
| | - C Matthew Kinsey
- Department of Medicine, College of Medicine, University of Vermont, Burlington, Vermont
| | - James A Carson
- Integrative Muscle Biology Laboratory, College of Health Professions, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Michael J Toth
- Department of Medicine, College of Medicine, University of Vermont, Burlington, Vermont
- Department of Molecular Physiology and Biophysics, College of Medicine, University of Vermont, Burlington, Vermont
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20
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Odeh M, Tamir‐Livne Y, Haas T, Bengal E. P38α MAPK coordinates the activities of several metabolic pathways that together induce atrophy of denervated muscles. FEBS J 2019; 287:73-93. [DOI: 10.1111/febs.15070] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 05/30/2019] [Accepted: 09/18/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Maali Odeh
- Department of Biochemistry Rappaport Faculty of Medicine Technion‐Israel Institute of Technology Haifa Israel
| | - Yael Tamir‐Livne
- Department of Biochemistry Rappaport Faculty of Medicine Technion‐Israel Institute of Technology Haifa Israel
| | - Tali Haas
- Pre‐Clinical Research Authority Technion‐Israel Institute of Technology Haifa Israel
| | - Eyal Bengal
- Department of Biochemistry Rappaport Faculty of Medicine Technion‐Israel Institute of Technology Haifa Israel
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21
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Sin TK, Zhang G, Zhang Z, Gao S, Li M, Li YP. Cancer Takes a Toll on Skeletal Muscle by Releasing Heat Shock Proteins-An Emerging Mechanism of Cancer-Induced Cachexia. Cancers (Basel) 2019; 11:cancers11091272. [PMID: 31480237 PMCID: PMC6770863 DOI: 10.3390/cancers11091272] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/21/2019] [Accepted: 08/27/2019] [Indexed: 01/03/2023] Open
Abstract
Cancer-associated cachexia (cancer cachexia) is a major contributor to the modality and mortality of a wide variety of solid tumors. It is estimated that cachexia inflicts approximately ~60% of all cancer patients and is the immediate cause of ~30% of all cancer-related death. However, there is no established treatment of this disorder due to the poor understanding of its underlying etiology. The key manifestations of cancer cachexia are systemic inflammation and progressive loss of skeletal muscle mass and function (muscle wasting). A number of inflammatory cytokines and members of the TGFβ superfamily that promote muscle protein degradation have been implicated as mediators of muscle wasting. However, clinical trials targeting some of the identified mediators have not yielded satisfactory results. Thus, the root cause of the muscle wasting associated with cancer cachexia remains to be identified. This review focuses on recent progress of laboratory studies in the understanding of the molecular mechanisms of cancer cachexia that centers on the role of systemic activation of Toll-like receptor 4 (TLR4) by cancer-released Hsp70 and Hsp90 in the development and progression of muscle wasting, and the downstream signaling pathways that activate muscle protein degradation through the ubiquitin-proteasome and the autophagy-lysosome pathways in response to TLR4 activation. Verification of these findings in humans could lead to etiology-based therapies of cancer cachexia by targeting multiple steps in this signaling cascade.
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Affiliation(s)
- Thomas K Sin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Zicheng Zhang
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Song Gao
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
| | - Min Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA
- The Vivian L. Smith Department of Neurosurgery, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Department of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, 6431 Fannin Street, Houston, TX 77030, USA.
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22
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McCarty MF, Iloki-Assanga S, Lujany LML. Nutraceutical targeting of TLR4 signaling has potential for prevention of cancer cachexia. Med Hypotheses 2019; 132:109326. [PMID: 31421423 DOI: 10.1016/j.mehy.2019.109326] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/23/2019] [Indexed: 12/25/2022]
Abstract
The mechanisms underlying cancer cachexia - the proximate cause of at least 20% of cancer-related deaths - have until recently remained rather obscure. New research, however, clarifies that cancers evoking cachexia release microvesicles rich in heat shock proteins 70 and 90, and that these extracellular heat shock proteins induce cachexia by serving as agonists for toll-like receptor 4 (TLR4) in skeletal muscle, macrophages, and adipocytes. Hence, safe nutraceutical measures which can down-regulate TLR4 signaling can be expected to aid prevention and control of cancer cachexia. There is reason to suspect that phycocyanobilin, ferulic acid, glycine, long-chain omega-3s, green tea catechins, β-hydroxy-β-methylbutyrate, carnitine, and high-dose biotin may have some utility in this regard.
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23
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Sin TK, Zhu JZ, Zhang G, Li YP. p300 Mediates Muscle Wasting in Lewis Lung Carcinoma. Cancer Res 2019; 79:1331-1342. [PMID: 30705122 PMCID: PMC6445764 DOI: 10.1158/0008-5472.can-18-1653] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/28/2018] [Accepted: 01/28/2019] [Indexed: 12/21/2022]
Abstract
C/EBPβ is a key mediator of cancer-induced skeletal muscle wasting. However, the signaling mechanisms that activate C/EBPβ in the cancer milieu are poorly defined. Here, we report cancer-induced muscle wasting requires the transcriptional cofactor p300, which is critical for the activation of C/EBPβ. Conditioned media from diverse types of tumor cells as well as recombinant HSP70 and HSP90 provoked rapid acetylation of C/EBPβ in myotubes, particularly at its Lys39 residue. Overexpression of C/EBPβ with mutated Lys39 impaired Lewis lung carcinoma (LLC)-induced activation of the C/EBPβ-dependent catabolic response, which included upregulation of E3 ligases UBR2 and atrogin1/MAFbx, increased LC3-II, and loss of muscle proteins both in myotubes and mouse muscle. Silencing p300 in myotubes or overexpressing a dominant negative p300 mutant lacking acetyltransferase activity in mouse muscle attenuated LLC tumor-induced muscle catabolism. Administration of pharmacologic p300 inhibitor C646, but not PCAF/GCN5 inhibitor CPTH6, spared LLC tumor-bearing mice from muscle wasting. Furthermore, mice with muscle-specific p300 knockout were resistant to LLC tumor-induced muscle wasting. These data suggest that p300 is a key mediator of LLC tumor-induced muscle wasting whose acetyltransferase activity may be targeted for therapeutic benefit in this disease. SIGNIFICANCE: These findings demonstrate that tumor-induced muscle wasting in mice is abrogated by knockout, mutation of Lys39 or Asp1399, and pharmacologic inhibition of p300.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/7/1331/F1.large.jpg.
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Affiliation(s)
- Thomas K Sin
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - James Z Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas.
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas.
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24
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Hamel-Côté G, Lapointe F, Gendron D, Rola-Pleszczynski M, Stankova J. Regulation of platelet-activating factor-induced interleukin-8 expression by protein tyrosine phosphatase 1B. Cell Commun Signal 2019; 17:21. [PMID: 30832675 PMCID: PMC6399872 DOI: 10.1186/s12964-019-0334-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/22/2019] [Indexed: 12/21/2022] Open
Abstract
Background Platelet-activating factor (PAF) is a potent lipid mediator whose involvement in the onset and progression of atherosclerosis is mediated by, among others, the modulation of cytokine expression patterns. The presence of multiple potential protein-tyrosine phosphatase (PTP) 1B substrates in PAF receptor signaling pathways brought us to investigate its involvement in PAF-induced cytokine expression in monocyte-derived dendritic cells (Mo-DCs) and to study the pathways involved in this modulation. Methods We used in-vitro-matured human dendritic cells and the HEK-293 cell line in our studies. PTP1B inhibition was though siRNAs and a selective inhibitor. Cytokine expression was studied with RT-PCR, luciferase assays and ELISA. Phosphorylation status of kinases and transcription factors was studied with western blotting. Results Here, we report that PTP1B was involved in the modulation of cytokine expression in PAF-stimulated Mo-DCs. A study of the down-regulation of PAF-induced IL-8 expression, by PTP1B, showed modulation of PAF-induced transactivation of the IL-8 promoter which was dependent on the presence of the C/EBPß -binding site. Results also suggested that PTP1B decreased PAF-induced IL-8 production by a glycogen synthase kinase (GSK)-3-dependent pathway via activation of the Src family kinases (SFK). These kinases activated an unidentified pathway at early stimulation times and the PI3K/Akt signaling pathway in a later phase. This change in GSK-3 activity decreased the C/EBPß phosphorylation levels of the threonine 235, a residue whose phosphorylation is known to increase C/EBPß transactivation potential, and consequently modified IL-8 expression. Conclusion The negative regulation of GSK-3 activity by PTP1B and the consequent decrease in phosphorylation of the C/EBPß transactivation domain could be an important negative feedback loop by which cells control their cytokine production after PAF stimulation. Electronic supplementary material The online version of this article (10.1186/s12964-019-0334-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Geneviève Hamel-Côté
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H 4N5, Canada
| | - Fanny Lapointe
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H 4N5, Canada
| | - Daniel Gendron
- Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Center, 2000 College Street, Sherbrooke, QC, Canada
| | - Marek Rola-Pleszczynski
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H 4N5, Canada
| | - Jana Stankova
- Immunology Division, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H 4N5, Canada.
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25
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Liu Z, Sin KWT, Ding H, Doan HA, Gao S, Miao H, Wei Y, Wang Y, Zhang G, Li YP. p38β MAPK mediates ULK1-dependent induction of autophagy in skeletal muscle of tumor-bearing mice. Cell Stress 2018; 2:311-324. [PMID: 31225455 PMCID: PMC6551802 DOI: 10.15698/cst2018.11.163] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Muscle wasting is the key manifestation of cancer-associated cachexia, a lethal metabolic disorder seen in over 50% of cancer patients. Autophagy is activated in cachectic muscle of cancer hosts along with the ubiquitin-proteasome pathway (UPP), contributing to accelerated protein degradation and muscle wasting. However, established signaling mechanism that activates autophagy in response to fasting or denervation does not seem to mediate cancer-provoked autophagy in skeletal myocytes. Here, we show that p38β MAPK mediates autophagy activation in cachectic muscle of tumor-bearing mice via novel mechanisms. Complementary genetic and pharmacological manipulations reveal that activation of p38β MAPK, but not p38α MAPK, is necessary and sufficient for Lewis lung carcinoma (LLC)-induced autophagy activation in skeletal muscle cells. Particularly, muscle-specific knockout of p38β MAPK abrogates LLC tumor-induced activation of autophagy and UPP, sparing tumor-bearing mice from muscle wasting. Mechanistically, p38β MAPK-mediated activation of transcription factor C/EBPβ is required for LLC-induced autophagy activation, and upregulation of autophagy-related genes LC3b and Gabarapl1. Surprisingly, ULK1 activation (phosphorylation at S555) by cancer requires p38β MAPK, rather than AMPK. Activated ULK1 forms a complex with p38β MAPK in myocytes, which is markedly increased by a tumor burden. Overexpression of a constitutively active p38Tbeta; MAPK in HEK293 cells increases phosphorylation at S555 and other amino acid residues of ULK1, but not several of AMPK-mediated sites. Finally, ULK1 activation is abrogated in tumor-bearing mice with muscle-specific knockout of p38β MAPK. Thus, p38β MAPK appears a key mediator of cancer-provoked autophagy activation, and a therapeutic target of cancer-induced muscle wasting.
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Affiliation(s)
- Zhelong Liu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA.,Division of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ka Wai Thomas Sin
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Hui Ding
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA.,Department of Respiratory Medicine, Yixing Hospital affiliated to Jiangsu University, Yixing, China
| | - HoangAnh Amy Doan
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Song Gao
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Hongyu Miao
- School of Public Health, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Yahui Wei
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Yiman Wang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030, USA
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26
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Pérez-Baos S, Prieto-Potin I, Román-Blas JA, Sánchez-Pernaute O, Largo R, Herrero-Beaumont G. Mediators and Patterns of Muscle Loss in Chronic Systemic Inflammation. Front Physiol 2018; 9:409. [PMID: 29740336 PMCID: PMC5928215 DOI: 10.3389/fphys.2018.00409] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 04/04/2018] [Indexed: 12/25/2022] Open
Abstract
Besides its primary function in locomotion, skeletal muscle (SKM), which represents up to half of human's weight, also plays a fundamental homeostatic role. Through the secretion of soluble peptides, or myokines, SKM interacts with major organs involved in metabolic processes. In turn, metabolic cues from these organs are received by muscle cells, which adapt their response accordingly. This is done through an intricate intracellular signaling network characterized by the cross-talking between anabolic and catabolic pathways. A fine regulation of the network is required to protect the organism from an excessive energy expenditure. Systemic inflammation evokes a catabolic reaction in SKM known as sarcopenia. In turn this response comprises several mechanisms, which vary depending on the nature of the insult and its magnitude. In this regard, aging, chronic inflammatory systemic diseases, osteoarthritis and idiopathic inflammatory myopathies can lead to muscle loss. Interestingly, sarcopenia may persist despite remission of chronic inflammation, an issue which warrants further research. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) system stands as a major participant in muscle loss during systemic inflammation, while it is also a well-recognized orchestrator of muscle cell turnover. Herein we summarize current knowledge about models of sarcopenia, their triggers and major mediators and their effect on both protein and cell growth yields. Also, the dual action of the JAK/STAT pathway in muscle mass changes is discussed. We highlight the need to unravel the precise contribution of this system to sarcopenia in order to design targeted therapeutic strategies.
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Affiliation(s)
- Sandra Pérez-Baos
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
| | - Iván Prieto-Potin
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
| | - Jorge A Román-Blas
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
| | - Olga Sánchez-Pernaute
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
| | - Raquel Largo
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
| | - Gabriel Herrero-Beaumont
- Bone and Joint Research Unit, Service of Rheumatology, IIS-Fundación Jiménez Díaz, Autonomous University of Madrid, Madrid, Spain
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27
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Zhang G, Liu Z, Ding H, Zhou Y, Doan HA, Sin KWT, Zhu ZJ, Flores R, Wen Y, Gong X, Liu Q, Li YP. Tumor induces muscle wasting in mice through releasing extracellular Hsp70 and Hsp90. Nat Commun 2017; 8:589. [PMID: 28928431 PMCID: PMC5605540 DOI: 10.1038/s41467-017-00726-x] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 07/25/2017] [Indexed: 01/06/2023] Open
Abstract
Cachexia, characterized by muscle wasting, is a major contributor to cancer-related mortality. However, the key cachexins that mediate cancer-induced muscle wasting remain elusive. Here, we show that tumor-released extracellular Hsp70 and Hsp90 are responsible for tumor’s capacity to induce muscle wasting. We detected high-level constitutive release of Hsp70 and Hsp90 associated with extracellular vesicles (EVs) from diverse cachexia-inducing tumor cells, resulting in elevated serum levels in mice. Neutralizing extracellular Hsp70/90 or silencing Hsp70/90 expression in tumor cells abrogates tumor-induced muscle catabolism and wasting in cultured myotubes and in mice. Conversely, administration of recombinant Hsp70 and Hsp90 recapitulates the catabolic effects of tumor. In addition, tumor-released Hsp70/90-expressing EVs are necessary and sufficient for tumor-induced muscle wasting. Further, Hsp70 and Hsp90 induce muscle catabolism by activating TLR4, and are responsible for elevation of circulating cytokines. These findings identify tumor-released circulating Hsp70 and Hsp90 as key cachexins causing muscle wasting in mice. Cachexia affects many cancer patients causing weight loss and increasing mortality. Here, the authors identify extracellular Hsp70 and Hsp90, either in soluble form or secreted as part of exosomes from tumor cells, to be responsible for tumor induction of cachexia.
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Affiliation(s)
- Guohua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Zhelong Liu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA.,Division of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hui Ding
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA.,Department of Respiratory Medicine, Yixing Hospital affiliated to Jiangsu University, Yixing, 214200, China
| | - Yong Zhou
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Hoang Anh Doan
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Ka Wai Thomas Sin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Zhiren J Zhu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Rene Flores
- Academic and Research Affairs, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Yefei Wen
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Xing Gong
- The Brown Foundation Institution of Molecular Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Qingyun Liu
- The Brown Foundation Institution of Molecular Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, 77030, USA.
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28
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Toll-like receptor 4 mediates Lewis lung carcinoma-induced muscle wasting via coordinate activation of protein degradation pathways. Sci Rep 2017; 7:2273. [PMID: 28536426 PMCID: PMC5442131 DOI: 10.1038/s41598-017-02347-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/10/2017] [Indexed: 12/22/2022] Open
Abstract
Cancer-induced cachexia, characterized by muscle wasting, is a lethal metabolic syndrome with undefined etiology. Current consensus is that multiple factors contribute to cancer-induced muscle wasting, and therefore therapy requires combinational strategies. Here, we show that Toll-like receptor 4 (TLR4) mediates cancer-induced muscle wasting by directly activating muscle catabolism as well as stimulating an innate immune response in mice bearing Lewis lung carcinoma (LLC), and targeting TLR4 alone effectively abrogate muscle wasting. Utilizing specific siRNAs we observed that LLC cell-conditioned medium (LCM)-treated C2C12 myotubes underwent a rapid catabolic response in a TLR4-dependent manner, including activation of the p38 MAPK−C/EBPβ signaling pathway as well as the ubiquitin-proteasome and autophagy-lysosome pathways, resulting in myotube atrophy. Utilizing a reporter cell-line it was confirmed that LCM activated TLR4. These results suggest that LLC-released cachexins directly activate muscle catabolism via activating TLR4 on muscle cells independent of immune responses. Critically, LLC tumor-bearing TLR4−/− mice were spared from muscle wasting due to a blockade in muscle catabolic pathways. Further, tumor-induced elevation of circulating TNFα and interleukin-6 (IL-6) was abolished in TLR4−/− mice. These data suggest that TLR4 is a central mediator and therapeutic target of cancer-induced muscle wasting.
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29
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Ding H, Zhang G, Sin KWT, Liu Z, Lin RK, Li M, Li YP. Activin A induces skeletal muscle catabolism via p38β mitogen-activated protein kinase. J Cachexia Sarcopenia Muscle 2017; 8:202-212. [PMID: 27897407 PMCID: PMC5377410 DOI: 10.1002/jcsm.12145] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 07/08/2016] [Accepted: 07/25/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Activation of type IIB activin receptor (ActRIIB) in skeletal muscle leads to muscle atrophy because of increased muscle protein degradation. However, the intracellular signalling mechanism that mediates ActRIIB-activated muscle catabolism is poorly defined. METHODS We investigated the role of p38β mitogen-activated protein kinases (MAPK) in mediating ActRIIB ligand activin A-activated muscle catabolic pathways in C2C12 myotubes and in mice with perturbation of this kinase pharmacologically and genetically. RESULTS Treatment of C2C12 myotubes with activin A or myostatin rapidly activated p38 MAPK and its effector C/EBPβ within 1 h. Paradoxically, Akt was activated at the same time through a p38 MAPK-independent mechanism. These events were followed by up-regulation of ubiquitin ligases atrogin1 (MAFbx) and UBR2 (E3α-II), as well as increase in LC3-II, a marker of autophagosome formation, leading to myofibrillar protein loss and myotube atrophy. The catabolic effects of activin A were abolished by p38α/β MAPK inhibitor SB202190. Using small interfering RNA-mediated gene knockdown, we found that the catabolic activity of activin A was dependent on p38β MAPK specifically. Importantly, systemic administration of activin A to mice similarly activated the catabolic pathways in vivo, and this effect was blocked by SB202190. Further, activin A failed to activate the catabolic pathways in mice with muscle-specific knockout of p38β MAPK. Interestingly, activin A up-regulated MuRF1 in a p38 MAPK-independent manner, and MuRF1 did not appear responsible for activin A-induced myosin heavy chain loss and muscle atrophy. CONCLUSIONS ActRIIB-mediated activation of muscle catabolism is dependent on p38β MAPK-activated signalling.
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Affiliation(s)
- Hui Ding
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA.,Department of Respiratory Medicine, Yixing Hospital affiliated to Jiangsu University, Yixing, China
| | - Guohua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA
| | - Ka Wai Thomas Sin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA
| | - Zhelong Liu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA.,Division of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ren-Kuo Lin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA
| | - Min Li
- Department of Medicine and Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Yi-Ping Li
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, 77030, USA
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30
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Sun R, Zhang S, Lu X, Hu W, Lou N, Zhao Y, Zhou J, Zhang X, Yang H. Comparative molecular analysis of early and late cancer cachexia-induced muscle wasting in mouse models. Oncol Rep 2016; 36:3291-3302. [PMID: 27748895 DOI: 10.3892/or.2016.5165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/14/2016] [Indexed: 11/05/2022] Open
Abstract
Cancer-induced muscle wasting, which commonly occurs in cancer cachexia, is characterized by impaired quality of life and poor patient survival. To identify an appropriate treatment, research on the mechanism underlying muscle wasting is essential. Thus far, studies on muscle wasting using cancer cachectic models have generally focused on early cancer cachexia (ECC), before severe body weight loss occurs. In the present study, we established models of ECC and late cancer cachexia (LCC) and compared different stages of cancer cachexia using two cancer cachectic mouse models induced by colon-26 (C26) adenocarcinoma or Lewis lung carcinoma (LLC). In each model, tumor-bearing (TB) and control (CN) mice were injected with cancer cells and PBS, respectively. The TB and CN mice, which were euthanized on the 24th day or the 36th day after injection, were defined as the ECC and ECC-CN mice or the LCC and LCC-CN mice. In addition, the tissues were harvested and analyzed. We found that both the ECC and LCC mice developed cancer cachexia. The amounts of muscle loss differed between the ECC and LCC mice. Moreover, the expression of some molecules was altered in the muscles from the LCC mice but not in those from the ECC mice compared with their CN mice. In conclusion, the molecules with altered expression in the muscles from the ECC and LCC mice were not exactly the same. These findings may provide some clues for therapy which could prevent the muscle wasting in cancer cachexia from progression to the late stage.
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Affiliation(s)
- Rulin Sun
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Santao Zhang
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xing Lu
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Wenjun Hu
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Ning Lou
- Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Yan Zhao
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Jia Zhou
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xiaoping Zhang
- Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Hongmei Yang
- Department of Pathogenic Biology, School of Basic Medicine, Tonji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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Sun R, Zhang S, Hu W, Lu X, Lou N, Yang Z, Chen S, Zhang X, Yang H. Valproic acid attenuates skeletal muscle wasting by inhibiting C/EBPβ-regulated atrogin1 expression in cancer cachexia. Am J Physiol Cell Physiol 2016; 311:C101-15. [DOI: 10.1152/ajpcell.00344.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 04/13/2016] [Indexed: 12/15/2022]
Abstract
Muscle wasting is the hallmark of cancer cachexia and is associated with poor quality of life and increased mortality. Valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, has important biological effects in the treatment of muscular dystrophy. To verify whether VPA could ameliorate muscle wasting induced by cancer cachexia, we explored the role of VPA in two cancer cachectic mouse models [induced by colon-26 (C26) adenocarcinoma or Lewis lung carcinoma (LLC)] and atrophied C2C12 myotubes [induced by C26 cell conditioned medium (CCM) or LLC cell conditioned medium (LCM)]. Our data demonstrated that treatment with VPA increased the mass and cross-sectional area of skeletal muscles in tumor-bearing mice. Furthermore, treatment with VPA also increased the diameter of myotubes cultured in conditioned medium. The skeletal muscles in cachectic mice or atrophied myotubes treated with VPA exhibited reduced levels of CCAAT/enhancer binding protein beta (C/EBPβ), resulting in atrogin1 downregulation and the eventual alleviation of muscle wasting and myotube atrophy. Moreover, atrogin1 promoter activity in myotubes was stimulated by CCM via activating the C/EBPβ-responsive cis-element and subsequently inhibited by VPA. In contrast to the effect of VPA on the levels of C/EBPβ, the levels of inactivating forkhead box O3 (FoxO3a) were unaffected. In summary, VPA attenuated muscle wasting and myotube atrophy and reduced C/EBPβ binding to atrogin1 promoter locus in the myotubes. Our discoveries indicate that HDAC inhibition by VPA might be a promising new approach for the preservation of skeletal muscle in cancer cachexia.
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Affiliation(s)
- Rulin Sun
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
| | - Santao Zhang
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
| | - Wenjun Hu
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
| | - Xing Lu
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
| | - Ning Lou
- Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China; and
| | - Zhende Yang
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
| | - Shaoyong Chen
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Xiaoping Zhang
- Department of Urology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China; and
| | - Hongmei Yang
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Hubei Province, China
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Carson JA, Hardee JP, VanderVeen BN. The emerging role of skeletal muscle oxidative metabolism as a biological target and cellular regulator of cancer-induced muscle wasting. Semin Cell Dev Biol 2015; 54:53-67. [PMID: 26593326 DOI: 10.1016/j.semcdb.2015.11.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/12/2015] [Indexed: 12/17/2022]
Abstract
While skeletal muscle mass is an established primary outcome related to understanding cancer cachexia mechanisms, considerable gaps exist in our understanding of muscle biochemical and functional properties that have recognized roles in systemic health. Skeletal muscle quality is a classification beyond mass, and is aligned with muscle's metabolic capacity and substrate utilization flexibility. This supplies an additional role for the mitochondria in cancer-induced muscle wasting. While the historical assessment of mitochondria content and function during cancer-induced muscle loss was closely aligned with energy flux and wasting susceptibility, this understanding has expanded to link mitochondria dysfunction to cellular processes regulating myofiber wasting. The primary objective of this article is to highlight muscle mitochondria and oxidative metabolism as a biological target of cancer cachexia and also as a cellular regulator of cancer-induced muscle wasting. Initially, we examine the role of muscle metabolic phenotype and mitochondria content in cancer-induced wasting susceptibility. We then assess the evidence for cancer-induced regulation of skeletal muscle mitochondrial biogenesis, dynamics, mitophagy, and oxidative stress. In addition, we discuss environments associated with cancer cachexia that can impact the regulation of skeletal muscle oxidative metabolism. The article also examines the role of cytokine-mediated regulation of mitochondria function, followed by the potential role of cancer-induced hypogonadism. Lastly, a role for decreased muscle use in cancer-induced mitochondrial dysfunction is reviewed.
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Affiliation(s)
- James A Carson
- Integrative Muscle Biology Laboratory, Department of Exercise Science, University of South Carolina, 921 Assembly St., Columbia, SC, 29208, USA.
| | - Justin P Hardee
- Integrative Muscle Biology Laboratory, Department of Exercise Science, University of South Carolina, 921 Assembly St., Columbia, SC, 29208, USA
| | - Brandon N VanderVeen
- Integrative Muscle Biology Laboratory, Department of Exercise Science, University of South Carolina, 921 Assembly St., Columbia, SC, 29208, USA
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Gao S, Carson JA. Lewis lung carcinoma regulation of mechanical stretch-induced protein synthesis in cultured myotubes. Am J Physiol Cell Physiol 2015; 310:C66-79. [PMID: 26491045 DOI: 10.1152/ajpcell.00052.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 10/19/2015] [Indexed: 11/22/2022]
Abstract
Mechanical stretch can activate muscle and myotube protein synthesis through mammalian target of rapamycin complex 1 (mTORC1) signaling. While it has been established that tumor-derived cachectic factors can induce myotube wasting, the effect of this catabolic environment on myotube mechanical signaling has not been determined. We investigated whether media containing cachectic factors derived from Lewis lung carcinoma (LLC) can regulate the stretch induction of myotube protein synthesis. C2C12 myotubes preincubated in control or LLC-derived media were chronically stretched. Protein synthesis regulation by anabolic and catabolic signaling was then examined. In the control condition, stretch increased mTORC1 activity and protein synthesis. The LLC treatment decreased basal mTORC1 activity and protein synthesis and attenuated the stretch induction of protein synthesis. LLC media increased STAT3 and AMP-activated protein kinase phosphorylation in myotubes, independent of stretch. Both stretch and LLC independently increased ERK1/2, p38, and NF-κB phosphorylation. In LLC-treated myotubes, the inhibition of ERK1/2 and p38 rescued the stretch induction of protein synthesis. Interestingly, either leukemia inhibitory factor or glycoprotein 130 antibody administration caused further inhibition of mTORC1 signaling and protein synthesis in stretched myotubes. AMP-activated protein kinase inhibition increased basal mTORC1 signaling activity and protein synthesis in LLC-treated myotubes, but did not restore the stretch induction of protein synthesis. These results demonstrate that LLC-derived cachectic factors can dissociate stretch-induced signaling from protein synthesis through ERK1/2 and p38 signaling, and that glycoprotein 130 signaling is associated with the basal stretch response in myotubes.
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Affiliation(s)
- Song Gao
- Integrative Muscle Biology Laboratory, Department of Exercise Science, University of South Carolina, Columbia, South Carolina; and
| | - James A Carson
- Integrative Muscle Biology Laboratory, Department of Exercise Science, University of South Carolina, Columbia, South Carolina; and Center for Colon Cancer Research, University of South Carolina, Columbia, South Carolina
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Sankaralingam S, Abo Alrob O, Zhang L, Jaswal JS, Wagg CS, Fukushima A, Padwal RS, Johnstone DE, Sharma AM, Lopaschuk GD. Lowering body weight in obese mice with diastolic heart failure improves cardiac insulin sensitivity and function: implications for the obesity paradox. Diabetes 2015; 64:1643-57. [PMID: 25524917 DOI: 10.2337/db14-1050] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 11/27/2014] [Indexed: 11/13/2022]
Abstract
Recent studies suggest improved outcomes and survival in obese heart failure patients (i.e., the obesity paradox), although obesity and heart failure unfavorably alter cardiac function and metabolism. We investigated the effects of weight loss on cardiac function and metabolism in obese heart failure mice. Obesity and heart failure were induced by feeding mice a high-fat (HF) diet (60% kcal from fat) for 4 weeks, following which an abdominal aortic constriction (AAC) was produced. Four weeks post-AAC, mice were switched to a low-fat (LF) diet (12% kcal from fat; HF AAC LF) or maintained on an HF (HF AAC HF) for a further 10 weeks. After 18 weeks, HF AAC LF mice weighed less than HF AAC HF mice. Diastolic function was improved in HF AAC LF mice, while cardiac hypertrophy was decreased and accompanied by decreased SIRT1 expression, increased FOXO1 acetylation, and increased atrogin-1 expression compared with HF AAC HF mice. Insulin-stimulated glucose oxidation was increased in hearts from HF AAC LF mice, compared with HF AAC HF mice. Thus lowering body weight by switching to LF diet in obese mice with heart failure is associated with decreased cardiac hypertrophy and improvements in both cardiac insulin sensitivity and diastolic function, suggesting that weight loss does not negatively impact heart function in the setting of obesity.
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Affiliation(s)
- Sowndramalingam Sankaralingam
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Osama Abo Alrob
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada Faculty of Pharmacy, Yarmouk University, Irbid, Jordan
| | - Liyan Zhang
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jagdip S Jaswal
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Cory S Wagg
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Arata Fukushima
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Raj S Padwal
- Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - David E Johnstone
- Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Arya M Sharma
- Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Gary D Lopaschuk
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
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Quercetin protects against obesity-induced skeletal muscle inflammation and atrophy. Mediators Inflamm 2014; 2014:834294. [PMID: 25614714 PMCID: PMC4295595 DOI: 10.1155/2014/834294] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/22/2014] [Accepted: 11/23/2014] [Indexed: 01/06/2023] Open
Abstract
Skeletal muscle inflammation and atrophy are closely associated with metabolic impairment such as insulin resistance. Quercetin, a natural polyphenol flavonoid, is known to elicit anti-inflammatory and antioxidant activities. In this study, we investigated its effect on obesity-induced skeletal muscle inflammation and atrophy in mice. Male C57BL/6 mice were fed a regular diet, a high-fat diet (HFD), and an HFD supplemented with quercetin for nine weeks. Quercetin reduced levels of inflammatory cytokines and macrophage accumulation in the skeletal muscle of the HFD-fed obese mice. It also reduced transcript and protein levels of the specific atrophic factors, Atrogin-1 and MuRF1, in the skeletal muscle of the HFD-fed obese mice, and protected against the reduction of muscle mass and muscle fiber size. In vitro, quercetin markedly diminished transcript levels of inflammatory receptors and activation of their signaling molecules (ERK, p38 MAPK, and NF-κB) in cocultured myotubes/macrophages, and this was accompanied by reduced expression of the atrophic factors. Together, these findings suggest that quercetin reduces obesity-induced skeletal muscle atrophy by inhibiting inflammatory receptors and their signaling pathway. Quercetin may be useful for preventing obesity-induced muscle inflammation and sarcopenia.
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Abstract
Muscle RING finger 1 (MuRF1) and muscle atrophy F-box (MAFbx)/atrogin-1 were identified more than 10 years ago as two muscle-specific E3 ubiquitin ligases that are increased transcriptionally in skeletal muscle under atrophy-inducing conditions, making them excellent markers of muscle atrophy. In the past 10 years much has been published about MuRF1 and MAFbx with respect to their mRNA expression patterns under atrophy-inducing conditions, their transcriptional regulation, and their putative substrates. However, much remains to be learned about the physiological role of both genes in the regulation of mass and other cellular functions in striated muscle. Although both MuRF1 and MAFbx are enriched in skeletal, cardiac, and smooth muscle, this review will focus on the current understanding of MuRF1 and MAFbx in skeletal muscle, highlighting the critical questions that remain to be answered.
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Affiliation(s)
- Sue C Bodine
- Departments of Neurobiology, Physiology, and Behavior and Physiology and Membrane Biology, University of California Davis, Davis, California; and Northern California Veterans Affairs Health Systems, Mather, California
| | - Leslie M Baehr
- Membrane Biology, University of California Davis, Davis, California; and
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Wernbom M, Apro W, Paulsen G, Nilsen TS, Blomstrand E, Raastad T. Acute low-load resistance exercise with and without blood flow restriction increased protein signalling and number of satellite cells in human skeletal muscle. Eur J Appl Physiol 2014; 113:2953-65. [PMID: 24078212 DOI: 10.1007/s00421-013-2733-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 09/16/2013] [Indexed: 11/28/2022]
Abstract
PURPOSE To investigate hypertrophic signalling after a single bout of low-load resistance exercise with and without blood flow restriction (BFR). METHODS Seven subjects performed unilateral knee extensions at 30 % of their one repetition maximum. The subjects performed five sets to failure with BFR on one leg, and then repeated the same amount of work with the other leg without BFR. Biopsies were obtained from m. vastus lateralis before and 1, 24 and 48 h after exercise. RESULTS At 1-h post-exercise, phosphorylation of p70S6KThr389 and p38MAPKThr180/Tyr182 was elevated in the BFR leg, but not in the free-flow leg. Phospho-p70S6KThr389 was elevated three- to fourfold in both legs at 24-h post-exercise, but back to baseline at 48 h. The number of visible satellite cells (SCs) per muscle fibre was increased for all post-exercise time points and in both legs (33–53 %). The proportion of SCs with cytoplasmic extensions was elevated at 1-h post in the BFR leg and the number of SCs positive for myogenin and/or MyoD was increased at 1- and 24-h post-exercise for both legs combined. CONCLUSION Acute low-load resistance exercise with BFR resulted in early (1 h) and late (24 h) enhancement of phospho-p70S6KThr389, an early response of p38MAPK, and an increased number of SCs per muscle fibre. Enhanced phospho-p70S6KThr389 at 24-h post-exercise and increases in SC numbers were seen also in the free-flow leg. Implications of these findings for the hypertrophic effects of fatiguing low-load resistance exercise with and without BFR are discussed.
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38
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Evertsson K, Fjällström AK, Norrby M, Tågerud S. p38 mitogen-activated protein kinase and mitogen-activated protein kinase-activated protein kinase 2 (MK2) signaling in atrophic and hypertrophic denervated mouse skeletal muscle. J Mol Signal 2014; 9:2. [PMID: 24629011 PMCID: PMC3995524 DOI: 10.1186/1750-2187-9-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/10/2014] [Indexed: 11/10/2022] Open
Abstract
Background p38 mitogen-activated protein kinase has been implicated in both skeletal muscle atrophy and hypertrophy. T317 phosphorylation of the p38 substrate mitogen-activated protein kinase-activated protein kinase 2 (MK2) correlates with muscle weight in atrophic and hypertrophic denervated muscle and may influence the nuclear and cytoplasmic distribution of p38 and/or MK2. The present study investigates expression and phosphorylation of p38, MK2 and related proteins in cytosolic and nuclear fractions from atrophic and hypertrophic 6-days denervated skeletal muscles compared to innervated controls. Methods Expression and phosphorylation of p38, MK2, Hsp25 (heat shock protein25rodent/27human, Hsp25/27) and Hsp70 protein expression were studied semi-quantitatively using Western blots with separated nuclear and cytosolic fractions from innervated and denervated hypertrophic hemidiaphragm and atrophic anterior tibial muscles. Unfractionated innervated and denervated atrophic pooled gastrocnemius and soleus muscles were also studied. Results No support was obtained for a differential nuclear/cytosolic localization of p38 or MK2 in denervated hypertrophic and atrophic muscle. The differential effect of denervation on T317 phosphorylation of MK2 in denervated hypertrophic and atrophic muscle was not reflected in p38 phosphorylation nor in the phosphorylation of the MK2 substrate Hsp25. Hsp25 phosphorylation increased 3-30-fold in all denervated muscles studied. The expression of Hsp70 increased 3-5-fold only in denervated hypertrophic muscles. Conclusions The study confirms a differential response of MK2 T317 phosphorylation in denervated hypertrophic and atrophic muscles and suggests that Hsp70 may be important for this. Increased Hsp25 phosphorylation in all denervated muscles studied indicates a role for factors other than MK2 in the regulation of this phosphorylation.
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Affiliation(s)
- Kim Evertsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
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Puppa MJ, Murphy EA, Fayad R, Hand GA, Carson JA. Cachectic skeletal muscle response to a novel bout of low-frequency stimulation. J Appl Physiol (1985) 2014; 116:1078-87. [PMID: 24610533 DOI: 10.1152/japplphysiol.01270.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
While exercise benefits have been well documented in patients with chronic diseases, the mechanistic understanding of cachectic muscle's response to contraction is essentially unknown. We previously demonstrated that treadmill exercise training attenuates the initiation of cancer cachexia and the development of metabolic syndrome symptoms (Puppa MJ, White JP, Velazquez KT, Baltgalvis KA, Sato S, Baynes JW, Carson JA. J Cachexia Sarcopenia Muscle 3: 117-137, 2012). However, cachectic muscle's metabolic signaling response to a novel, acute bout of low-frequency contraction has not been determined. The purpose of this study was to determine whether severe cancer cachexia disrupts the acute contraction-induced response to low-frequency muscle contraction [low-frequency stimulation (LoFS)]. Metabolic gene expression and signaling was examined 3 h after a novel 30-min bout of contraction (10 Hz) in cachectic Apc(Min/+) (Min) and C57BL/6 (BL-6) mice. Pyrrolidine dithiocarbamate, a STAT/NF-κB inhibitor and free radical scavenger, was administered systemically to a subset of mice to determine whether this altered the muscle contraction response. Although glucose transporter-4 mRNA was decreased by cachexia, LoFS increased muscle glucose transporter-4 mRNA in both BL-6 and Min mice. LoFS also induced muscle peroxisome proliferator-activated receptor-γ and peroxisome proliferator-activated receptor-α coactivator-1 mRNA. However, in Min mice, LoFS was not able to induce muscle proliferator-activated receptor-α coactivator-1 targets nuclear respiratory factor-1 and mitochondrial transcription factor A mRNA. LoFS induced phosphorylated-S6 in BL-6 mice, but this induction was blocked by cachexia. Administration of pyrrolidine dithiocarbamate for 24 h rescued LoFS-induced phosphorylated-S6 in cachectic muscle. LoFS increased muscle phosphorylated-AMP-activated protein kinase and p38 in BL-6 and Min mice. These data demonstrate that cachexia alters the muscle metabolic response to acute LoFS, and combination therapies in concert with muscle contraction may be beneficial for improving muscle mass and function during cachexia.
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Affiliation(s)
- Melissa J Puppa
- Department of Exercise Science, University of South Carolina, Columbia, South Carolina
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Puppa MJ, Gao S, Narsale AA, Carson JA. Skeletal muscle glycoprotein 130's role in Lewis lung carcinoma-induced cachexia. FASEB J 2013; 28:998-1009. [PMID: 24145720 DOI: 10.1096/fj.13-240580] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Chronic inflammation is associated with cachexia-induced skeletal muscle mass loss in cancer. Levels of IL-6 cytokine family members are increased during cancer-related cachexia and induce intracellular signaling through glycoprotein130 (gp130). Although muscle STAT3 and circulating IL-6 are implicated in cancer-induced muscle wasting, there is limited understanding of muscle gp130's role in this process. Therefore, we investigated the role of skeletal muscle gp130 (skm-gp130) in cancer-induced alterations in the regulation of muscle protein turnover. Lewis lung carcinoma (LLC) cells were injected into 8-wk-old skm-gp130-knockout (KO) mice or wild-type mice. Skeletal muscle loss was attenuated by 16% in gp130-KO mice, which coincided with attenuated LLC-induced phosphorylation of muscle STAT3, p38, and FOXO3. gp130 KO did not restore mTOR inhibition or alter AMP-activated protein kinase (AMPK) expression. The induction of atrogin expression and p38 phosphorylation in C2C12 myotubes exposed to LLC-treated medium was attenuated by gp130 inhibition, but mTOR inhibition was not restored. STAT signaling inhibition in LLC-treated myotubes did not attenuate the induction of p38 or AMPK phosphorylation. We concluded that, during LLC-induced cachexia, skm-gp130 regulates muscle mass signaling through STAT3 and p38 for the activation of FOXO3 and atrogin, but does not directly regulate the suppression of mTOR.
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Affiliation(s)
- Melissa J Puppa
- 1University of South Carolina, Department of Exercise Science, Public Health Research Center, Room 405, 921 Assembly Street, Columbia, SC 29208, USA.
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Muñoz-Cánoves P, Scheele C, Pedersen BK, Serrano AL. Interleukin-6 myokine signaling in skeletal muscle: a double-edged sword? FEBS J 2013; 280:4131-48. [PMID: 23663276 PMCID: PMC4163639 DOI: 10.1111/febs.12338] [Citation(s) in RCA: 480] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/25/2013] [Accepted: 05/07/2013] [Indexed: 12/19/2022]
Abstract
Interleukin (IL)-6 is a cytokine with pleiotropic functions in different tissues and organs. Skeletal muscle produces and releases significant levels of IL-6 after prolonged exercise and is therefore considered as a myokine. Muscle is also an important target of the cytokine. IL-6 signaling has been associated with stimulation of hypertrophic muscle growth and myogenesis through regulation of the proliferative capacity of muscle stem cells. Additional beneficial effects of IL-6 include regulation of energy metabolism, which is related to the capacity of actively contracting muscle to synthesize and release IL-6. Paradoxically, deleterious actions for IL-6 have also been proposed, such as promotion of atrophy and muscle wasting. We review the current evidence for these apparently contradictory effects, the mechanisms involved and discuss their possible biological implications.
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Affiliation(s)
- Pura Muñoz-Cánoves
- Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University (UPF), Institució Catalana de Recerca i Estudis Avançats (ICREA), CIBER on Neurodegenerative diseases (CIBERNED), Barcelona, Spain.
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Zhang G, Lin RK, Kwon YT, Li YP. Signaling mechanism of tumor cell-induced up-regulation of E3 ubiquitin ligase UBR2. FASEB J 2013; 27:2893-901. [PMID: 23568773 DOI: 10.1096/fj.12-222711] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The N-end rule pathway contributes significantly to accelerated muscle proteolysis mediated by the ubiquitin-proteasome pathway in various catabolic conditions. UBR2 (aka E3α-II) is the only known E3 ubiquitin ligase of the N-end rule pathway that is up-regulated by cachectic stimuli including proinflammatory cytokines and tumors. However, the signaling mechanism through which UBR2 is up-regulated remains undetermined. Here we identify a signaling pathway that mediates tumor cell-induced up-regulation of UBR2. UBR2 expression in C2C12 myotubes was up-regulated by conditioned medium from Lewis lung carcinoma cells or C26 colon adenocarcinoma cells, which was blocked by a pharmacological inhibitor of p38α/β mitogen-activated protein kinase (MAPK), SB202190. Similarly, SB202190 administration (i.p.) abolished UBR2 up-regulation in the tibialis anterior of LLC tumor-bearing mice. Genetic gain and loss of function assays in C2C12 myotubes indicated that tumor-induced activation of the p38β isoform is sufficient and necessary for UBR2 up-regulation. In addition, UBR2 up-regulation required p38β-mediated phosphorylation of CCAAT/enhancer binding protein (C/EBP)-β Thr-188, which was critical to C/EBPβ binding to the UBR2 promoter. Furthermore, luciferase reporter assay revealed that the C/EBPβ binding motif in the UBR2 promoter is a functional C/EBPβ-responsive cis-element that enhances the promoter activity on activation by p38β. Finally, genetic ablation of C/EBPβ blocked UBR2 up-regulation in LLC tumor-bearing mice. These results suggest that UBR2 up-regulation in cachectic muscle is mediated by the p38β-C/EBPβ signaling pathway responsible for the bulk of tumor-induced muscle proteolysis.
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Affiliation(s)
- Guohua Zhang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX 77030, USA
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