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Vanni E, Lindner K, Gavin AC, Montessuit C. Differential intracellular management of fatty acids impacts on metabolic stress-stimulated glucose uptake in cardiomyocytes. Sci Rep 2023; 13:14805. [PMID: 37684349 PMCID: PMC10491837 DOI: 10.1038/s41598-023-42072-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 09/05/2023] [Indexed: 09/10/2023] Open
Abstract
Stimulation of glucose uptake in response to ischemic metabolic stress is important for cardiomyocyte function and survival. Chronic exposure of cardiomyocytes to fatty acids (FA) impairs the stimulation of glucose uptake, whereas induction of lipid droplets (LD) is associated with preserved glucose uptake. However, the mechanisms by which LD induction prevents glucose uptake impairment remain elusive. We induced LD with either tetradecanoyl phorbol acetate (TPA) or 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). Triacylglycerol biosynthesis enzymes were inhibited in cardiomyocytes exposed to FA ± LD inducers, either upstream (glycerol-3-phosphate acyltransferases; GPAT) or downstream (diacylglycerol acyltransferases; DGAT) of the diacylglycerol step. Although both inhibitions reduced LD formation in cardiomyocytes treated with FA and LD inducers, only DGAT inhibition impaired metabolic stress-stimulated glucose uptake. DGAT inhibition in FA plus TPA-treated cardiomyocytes reduced triacylglycerol but not diacylglycerol content, thus increasing the diacylglycerol/triacylglycerol ratio. In cardiomyocytes exposed to FA alone, GPAT inhibition reduced diacylglycerol but not triacylglycerol, thus decreasing the diacylglycerol/triacylglycerol ratio, prevented PKCδ activation and improved metabolic stress-stimulated glucose uptake. Changes in AMP-activated Protein Kinase activity failed to explain variations in metabolic stress-stimulated glucose uptake. Thus, LD formation regulates metabolic stress-stimulated glucose uptake in a manner best reflected by the diacylglycerol/triacylglycerol ratio.
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Affiliation(s)
- Ettore Vanni
- Department of Pathology and Immunology, University of Geneva School of Medicine, Geneva, Switzerland
| | - Karina Lindner
- Department of Cell Physiology and Metabolism, University of Geneva School of Medicine, Geneva, Switzerland
| | - Anne-Claude Gavin
- Department of Cell Physiology and Metabolism, University of Geneva School of Medicine, Geneva, Switzerland
| | - Christophe Montessuit
- Department of Pathology and Immunology, University of Geneva School of Medicine, Geneva, Switzerland.
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Khan MS, Liu C, Meng F, Yang M, Zhou K, Hu R, Wang X, Dai K. X-rays Stimulate Granular Secretions and Activate Protein Kinase C Signaling in Human Platelets. Curr Issues Mol Biol 2023; 45:6024-6039. [PMID: 37504296 PMCID: PMC10378519 DOI: 10.3390/cimb45070380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/10/2023] [Accepted: 07/14/2023] [Indexed: 07/29/2023] Open
Abstract
X-rays can induce morphological as well as functional changes in cells. Platelets are anuclear cellular fragments originating from megakaryocytes and are the major regulators in hemostasis and thrombosis. Platelet products are irradiated to avoid medical complications associated with platelet transfusion. So far, gamma, UV, and laser radiation have been used for this purpose. However, scientists are divided about the effects of radiation on platelet quality. The present study was designed to explore the possible effects of X-rays in washed human platelets and understand the molecular mechanism behind them. In the present study, we exposed washed human platelets to 10 or 30 Gy X-rays at 0.25 Gy/min. Flow cytometry, aggregometry, and western blot were performed to investigate the effect of X-rays on platelet degranulation, integrin activation, platelet aggregation, and apoptosis. It was found that X-rays immediately induced granular secretions with no effect on GP IIb/IIIa activation. Not surprisingly, due to granule secretions in irradiated platelets, platelet aggregation was significantly reduced. In contrast to granular secretions and platelet aggregation, X-rays induced mitochondrial transmembrane potential depolarization in a time-dependent manner to induce apoptosis and activated protein kinase C (PKC) signaling. This study revealed and explained the molecular mechanism activated by X-rays in washed human platelets. Here we also introduced Gö 6983, a PKC inhibitor, as an agent that counteracts X-ray-induced changes and maintains the integrity of platelets.
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Affiliation(s)
- Muhammad Shoaib Khan
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Chunliang Liu
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Fanbi Meng
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Mengnan Yang
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Kangxi Zhou
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Renping Hu
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Xuexiang Wang
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
| | - Kesheng Dai
- Jiangsu Institute of Hematology, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, State Key Laboratory of Radiation Medicine and Protection, Medical College, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, Suzhou 215006, China
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Chia LY, Evans BA, Mukaida S, Bengtsson T, Hutchinson DS, Sato M. Adrenoceptor regulation of the mechanistic target of rapamycin in muscle and adipose tissue. Br J Pharmacol 2019; 176:2433-2448. [PMID: 30740664 PMCID: PMC6592864 DOI: 10.1111/bph.14616] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/08/2019] [Accepted: 01/21/2019] [Indexed: 12/16/2022] Open
Abstract
A vital role of adrenoceptors in metabolism and energy balance has been well documented in the heart, skeletal muscle, and adipose tissue. It has been only recently demonstrated, however, that activation of the mechanistic target of rapamycin (mTOR) makes a significant contribution to various metabolic and physiological responses to adrenoceptor agonists. mTOR exists as two distinct complexes named mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) and has been shown to play a critical role in protein synthesis, cell proliferation, hypertrophy, mitochondrial function, and glucose uptake. This review will describe the physiological significance of mTORC1 and 2 as a novel paradigm of adrenoceptor signalling in the heart, skeletal muscle, and adipose tissue. Understanding the detailed signalling cascades of adrenoceptors and how they regulate physiological responses is important for identifying new therapeutic targets and identifying novel therapeutic interventions. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.
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Affiliation(s)
- Ling Yeong Chia
- Drug Discovery Biology, Monash Institute of Pharmaceutical SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Bronwyn A. Evans
- Drug Discovery Biology, Monash Institute of Pharmaceutical SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Saori Mukaida
- Drug Discovery Biology, Monash Institute of Pharmaceutical SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Tore Bengtsson
- Department of Molecular Biosciences, The Wenner‐Gren InstituteStockholm UniversityStockholmSweden
| | - Dana S. Hutchinson
- Drug Discovery Biology, Monash Institute of Pharmaceutical SciencesMonash UniversityMelbourneVictoriaAustralia
| | - Masaaki Sato
- Drug Discovery Biology, Monash Institute of Pharmaceutical SciencesMonash UniversityMelbourneVictoriaAustralia
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4
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Chronic AICAR treatment prevents metabolic changes in cardiomyocytes exposed to free fatty acids. Pflugers Arch 2019; 471:1219-1234. [PMID: 31152240 DOI: 10.1007/s00424-019-02285-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/27/2019] [Accepted: 05/15/2019] [Indexed: 01/09/2023]
Abstract
The stimulation of glucose transport by metabolic stress is an important determinant of myocardial susceptibility to ischemia and reperfusion injury. Stimulation of glucose transport is markedly impaired in cardiomyocytes chronically exposed to excess free fatty acids (FFA), as occurs in vivo in type 2 diabetes. To determine whether chronic low-grade activation of AMP-activated kinase (AMPK) improves substrate metabolism in cardiomyocytes exposed to FFA, isolated cultured cardiomyocytes were exposed for 7 days to FFA ± the AMPK agonist 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR). Glucose transport and glycolysis were then measured during acute metabolic stress provoked by oligomycin. Chronic treatment with AICAR improved basal and oligomycin-stimulated glucose transport in FFA-exposed but not in control cardiomyocytes. Similarly, basal and oligomycin-stimulated glycolysis was reduced in FFA-exposed cardiomyocytes but restored by chronic AICAR treatment. Conversely, fatty acid oxidation was increased in FFA-exposed cardiomyocytes and reduced by chronic AICAR treatment. Chronic AICAR treatment induced in FFA-exposed cardiomyocytes the biogenesis of numerous lipid droplets. Curiously, whereas acute treatment of cardiomyocytes with AICAR increased phosphorylation of the AMPKα subunit on T172, a classical marker of AMPK activation, chronic AICAR treatment almost completely obliterated T172 phosphorylation. However, phosphorylation of the AMPK target protein raptor on S792 was reduced in FFA-exposed cardiomyocytes but restored by AICAR treatment. In conclusion, chronic AICAR treatment induces a metabolic shift in FFA-exposed cardiomyocytes, characterized by improved glucose transport and glycolysis and redirection of fatty acids towards neutral storage. Such metabolic changes in vivo could protect the hearts of patients with type 2 diabetes against ischemia-reperfusion injury.
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Smyrnias I, Goodwin N, Wachten D, Skogestad J, Aronsen JM, Robinson EL, Demydenko K, Segonds-Pichon A, Oxley D, Sadayappan S, Sipido K, Bootman MD, Roderick HL. Contractile responses to endothelin-1 are regulated by PKC phosphorylation of cardiac myosin binding protein-C in rat ventricular myocytes. J Mol Cell Cardiol 2018; 117:1-18. [DOI: 10.1016/j.yjmcc.2018.02.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/02/2018] [Accepted: 02/16/2018] [Indexed: 01/07/2023]
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6
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Sato M, Evans BA, Sandström AL, Chia LY, Mukaida S, Thai BS, Nguyen A, Lim L, Tan CYR, Baltos JA, White PJ, May LT, Hutchinson DS, Summers RJ, Bengtsson T. α 1A-Adrenoceptors activate mTOR signalling and glucose uptake in cardiomyocytes. Biochem Pharmacol 2017; 148:27-40. [PMID: 29175420 DOI: 10.1016/j.bcp.2017.11.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/22/2017] [Indexed: 12/20/2022]
Abstract
The capacity of G protein-coupled receptors to modulate mechanistic target of rapamycin (mTOR) activity is a newly emerging paradigm with the potential to link cell surface receptors with cell survival. Cardiomyocyte viability is linked to signalling pathways involving Akt and mTOR, as well as increased glucose uptake and utilization. Our aim was to determine whether the α1A-adrenoceptor (AR) couples to these protective pathways, and increased glucose uptake. We characterised α1A-AR signalling in CHO-K1 cells co-expressing the human α1A-AR and GLUT4 (CHOα1AGLUT4myc) and in neonatal rat ventricular cardiomyocytes (NRVM), and measured glucose uptake, intracellular Ca2+ mobilization, and phosphorylation of mTOR, Akt, 5' adenosine monophosphate-activated kinase (AMPK) and S6 ribosomal protein (S6rp). In both systems, noradrenaline and the α1A-AR selective agonist A61603 stimulated glucose uptake by parallel pathways involving mTOR and AMPK, whereas another α1-AR agonist oxymetazoline increased glucose uptake predominantly by mTOR. All agonists promoted phosphorylation of mTOR at Ser2448 and Ser2481, indicating activation of both mTORC1 and mTORC2, but did not increase Akt phosphorylation. In CHOα1AGLUT4myc cells, siRNA directed against rictor but not raptor suppressed α1A-AR mediated glucose uptake. We have thus identified mTORC2 as a key component in glucose uptake stimulated by α1A-AR agonists. Our findings identify a novel link between the α1A-AR, mTORC2 and glucose uptake, that have been implicated separately in cardiomyocyte survival. Our studies provide an improved framework for examining the utility of α1A-AR selective agonists as tools in the treatment of cardiac dysfunction.
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Affiliation(s)
- Masaaki Sato
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden; Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Bronwyn A Evans
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Anna L Sandström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ling Yeong Chia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Saori Mukaida
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Bui San Thai
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Anh Nguyen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Linzi Lim
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Christina Y R Tan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Jo-Anne Baltos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Paul J White
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Dana S Hutchinson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, Parkville, Victoria 3052, Australia
| | - Tore Bengtsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
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7
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Viglino C, Khoramdin B, Praplan G, Montessuit C. Pleiotropic Effects of Chronic Phorbol Ester Treatment to Improve Glucose Transport in Insulin-Resistant Cardiomyocytes. J Cell Biochem 2017; 118:4716-4727. [PMID: 28513986 DOI: 10.1002/jcb.26139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 05/16/2017] [Indexed: 11/08/2022]
Abstract
Stimulation of glucose transport is an important determinant of myocardial susceptibility to ischemia and reperfusion. Stimulation of glucose transport is markedly impaired in cardiomyocytes exposed to free fatty acids (FFA). Deactivation of the Focal Adhesion Kinase (FAK) by FFA contributes to glucose transport impairment, and could be corrected by chronic treatment with the phorbol ester TPA. However, TPA must have effects in addition to FAK reactivation to restore stimulated glucose transport. Chronic treatment with TPA improved basal and stimulated glucose transport in FFA-exposed, but not in control cardiomyocytes. Chronic FFA exposure induced the activation of PKCδ and PKCϵ. TPA markedly downregulated the expression of PKCα, PKCδ, and PKCϵ, suggesting that PKCδ or PKCϵ activation could contribute to inhibition of glucose transport by FFA. Rottlerin, a specific PKCδ inhibitor, improved glucose transport in FFA-exposed cardiomyocytes; and PKCδ was reduced in the particulate fraction of FFA + TPA-exposed cardiomyocytes. TPA also activated Protein Kinase D 1(PKD1) in FFA-exposed cardiomyocytes, as assessed by autophosphorylation of PKD1 on Y916. Pharmaceutical inhibition of PKD1 only partially prevented the improvement of glucose transport by TPA. Chronic TPA treatment also increased basal and stimulated glycolysis and favored accumulation of lipid droplets in FFA-exposed cardiomyocytes. In conclusion, basal and stimulated glucose transport in cardiomyocytes is reduced by chronic FFA exposure, but restored by concomitant treatment with a phorbol ester. The mechanism of action of phorbol esters may involve downregulation of PKCδ, activation of PKD1 and a general switch from fatty acid to glucose metabolism. J. Cell. Biochem. 9999: 4716-4727, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Christelle Viglino
- Division of Cardiology, Department of Medical Specialties, University of Geneva School of Medicine, Geneva, Switzerland
| | - Bahareh Khoramdin
- Division of Cardiology, Department of Medical Specialties, University of Geneva School of Medicine, Geneva, Switzerland
| | - Guillaume Praplan
- Division of Cardiology, Department of Medical Specialties, University of Geneva School of Medicine, Geneva, Switzerland
| | - Christophe Montessuit
- Division of Cardiology, Department of Medical Specialties, University of Geneva School of Medicine, Geneva, Switzerland.,Department of Pathology and Immunology, University of Geneva School of Medicine, Geneva, Switzerland
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8
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Van Steenbergen A, Balteau M, Ginion A, Ferté L, Battault S, Ravenstein CDMD, Balligand JL, Daskalopoulos EP, Gilon P, Despa F, Despa S, Vanoverschelde JL, Horman S, Koepsell H, Berry G, Hue L, Bertrand L, Beauloye C. Sodium-myoinositol cotransporter-1, SMIT1, mediates the production of reactive oxygen species induced by hyperglycemia in the heart. Sci Rep 2017; 7:41166. [PMID: 28128227 PMCID: PMC5269587 DOI: 10.1038/srep41166] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/16/2016] [Indexed: 01/04/2023] Open
Abstract
Hyperglycemia (HG) stimulates the production of reactive oxygen species in the heart through activation of NADPH oxidase 2 (NOX2). This production is independent of glucose metabolism but requires sodium/glucose cotransporters (SGLT). Seven SGLT isoforms (SGLT1 to 6 and sodium-myoinositol cotransporter-1, SMIT1) are known, although their expression and function in the heart remain elusive. We investigated these 7 isoforms and found that only SGLT1 and SMIT1 were expressed in mouse, rat and human hearts. In cardiomyocytes, galactose (transported through SGLT1) did not activate NOX2. Accordingly, SGLT1 deficiency did not prevent HG-induced NOX2 activation, ruling it out in the cellular response to HG. In contrast, myo-inositol (transported through SMIT1) reproduced the toxic effects of HG. SMIT1 overexpression exacerbated glucotoxicity and sensitized cardiomyocytes to HG, whereas its deletion prevented HG-induced NOX2 activation. In conclusion, our results show that heart SMIT1 senses HG and triggers NOX2 activation. This could participate in the redox signaling in hyperglycemic heart and contribute to the pathophysiology of diabetic cardiomyopathy.
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Affiliation(s)
- Anne Van Steenbergen
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Magali Balteau
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Audrey Ginion
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Laura Ferté
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Sylvain Battault
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | | | - Jean-Luc Balligand
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pole of Pharmacology and Therapeutics, Brussels, Belgium.,Cliniques Universitaires Saint-Luc, Department of Medicine, Brussels, Belgium
| | - Evangelos-Panagiotis Daskalopoulos
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Florin Despa
- University of Kentucky, Department of Pharmacology and Nutritional Sciences, Lexington, KY, USA
| | - Sanda Despa
- University of Kentucky, Department of Pharmacology and Nutritional Sciences, Lexington, KY, USA
| | - Jean-Louis Vanoverschelde
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Cliniques Universitaires Saint Luc, Division of Cardiology, Brussels, Belgium
| | - Sandrine Horman
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Hermann Koepsell
- University of Würzburg, Department of Molecular Plant Physiology and Biophysics, Julius von Sachs Institute, Würzburg, Germany
| | - Gerard Berry
- Harvard Medical School, Children's Hospital Boston, Division of Genetics and Genomics, Department of Pediatrics, Boston, MA, USA
| | - Louis Hue
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Université catholique de Louvain, de Duve Institute, Brussels, Belgium
| | - Luc Bertrand
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium
| | - Christophe Beauloye
- Université catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle de Recherche Cardiovasculaire, Brussels, Belgium.,Cliniques Universitaires Saint Luc, Division of Cardiology, Brussels, Belgium
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Xu L, Brink M. mTOR, cardiomyocytes and inflammation in cardiac hypertrophy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1894-903. [PMID: 26775585 DOI: 10.1016/j.bbamcr.2016.01.003] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/30/2015] [Accepted: 01/07/2016] [Indexed: 02/07/2023]
Abstract
Mammalian target of rapamycin (mTOR) is an evolutionary conserved kinase that senses the nutrient and energy status of cells, the availability of growth factors, stress stimuli and other cellular and environmental cues. It responds by regulating a range of cellular processes related to metabolism and growth in accordance with the available resources and intracellular needs. mTOR has distinct functions depending on its assembly in the structurally distinct multiprotein complexes mTORC1 or mTORC2. Active mTORC1 enhances processes including glycolysis, protein, lipid and nucleotide biosynthesis, and it inhibits autophagy. Reported functions for mTORC2 after growth factor stimulation are very diverse, are tissue and cell-type specific, and include insulin-stimulated glucose transport and enhanced glycogen synthesis. In accordance with its cellular functions, mTOR has been demonstrated to regulate cardiac growth in response to pressure overload and is also known to regulate cells of the immune system. The present manuscript presents recently obtained insights into mechanisms whereby mTOR may change anabolic, catabolic and stress response pathways in cardiomocytes and discusses how mTOR may affect inflammatory cells in the heart during hemodynamic stress. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
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Affiliation(s)
- Lifen Xu
- Department of Biomedicine, University of Basel and University Hospital Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland
| | - Marijke Brink
- Department of Biomedicine, University of Basel and University Hospital Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland.
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10
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Shende P, Xu L, Morandi C, Pentassuglia L, Heim P, Lebboukh S, Berthonneche C, Pedrazzini T, Kaufmann BA, Hall MN, Rüegg MA, Brink M. Cardiac mTOR complex 2 preserves ventricular function in pressure-overload hypertrophy. Cardiovasc Res 2015; 109:103-14. [DOI: 10.1093/cvr/cvv252] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 11/06/2015] [Indexed: 11/12/2022] Open
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Si H, Wyeth RP, Liu D. The flavonoid luteolin induces nitric oxide production and arterial relaxation. Eur J Nutr 2013; 53:269-75. [PMID: 23604495 DOI: 10.1007/s00394-013-0525-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 04/11/2013] [Indexed: 11/28/2022]
Abstract
PURPOSE Luteolin, a flavone present in many foods and medicinal plants, may have beneficial effects on various human chronic diseases. In the present study, we investigated the hypothesis that luteolin can directly act on vascular endothelial cells (ECs), leading to nitric oxide (NO) production and subsequent vascular relaxation. METHODS Rat aortic rings were mounted in organ bath. Luteolin was added cumulatively, and vessel relaxation of rat aortic rings precontracted with phenylephrine (PE) or potassium was recorded. Endothelial nitric oxide synthase (eNOS) phosphorylation at Ser1177 and NO production from aortic rings and primary human aortic endothelial cells (HAECs) exposed to luteolin were measured by using Western blot and fluorometric assay, respectively. RESULTS Luteolin dose-dependently (10-100 μmol/L) elicited relaxation of PE- or potassium-contracted aortic rings. The vasorelaxation effect of luteolin was attenuated by the eNOS inhibitor, N-nitro-L-arginine methyl ester, suggesting that this luteolin action is at least partially mediated by activating eNOS activity. We further found that luteolin dose-dependently (10-100 μmol/L) increased eNOS phosphorylation at Ser1177 (up to 1.9-fold) in isolated rat rings. Consistently, exposure of HAECs to luteolin also increased eNOS phosphorylation and NO production. CONCLUSIONS Luteolin may be a vascular protective agent by directly acting on vascular ECs to stimulate NO-dependent vascular dilatation.
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Affiliation(s)
- Hongwei Si
- Department of Human Nutrition, Foods and Exercise, College of Agriculture and Life Sciences, Virginia Tech, Blacksburg, VA, 24061, USA
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12
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Fonseca BD, Alain T, Finestone LK, Huang BPH, Rolfe M, Jiang T, Yao Z, Hernandez G, Bennett CF, Proud CG. Pharmacological and genetic evaluation of proposed roles of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), extracellular signal-regulated kinase (ERK), and p90(RSK) in the control of mTORC1 protein signaling by phorbol esters. J Biol Chem 2011; 286:27111-22. [PMID: 21659537 DOI: 10.1074/jbc.m111.260794] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) links the control of mRNA translation, cell growth, and metabolism to diverse stimuli. Inappropriate activation of mTORC1 can lead to cancer. Phorbol esters are naturally occurring products that act as potent tumor promoters. They activate isoforms of protein kinase C (PKCs) and stimulate the oncogenic MEK/ERK signaling cascade. They also activate mTORC1 signaling. Previous work indicated that mTORC1 activation by the phorbol ester PMA (phorbol 12-myristate 13-acetate) depends upon PKCs and may involve MEK. However, the precise mechanism(s) through which they activate mTORC1 remains unclear. Recent studies have implicated both the ERKs and the ERK-activated 90-kDa ribosomal S6 kinases (p90(RSK)) in activating mTORC1 signaling via phosphorylation of TSC2 (a regulator of mTORC1) and/or the mTORC1 component raptor. However, the relative importance of each of these kinases and phosphorylation events for the activation of mTORC1 signaling is unknown. The recent availability of MEK (PD184352) and p90(RSK) (BI-D1870) inhibitors of improved specificity allowed us to address the roles of these protein kinases in controlling mTORC1 in a variety of human and rodent cell types. In parallel, we used specific shRNAs against p90(RSK1) and p90(RSK2) to further test their roles in regulating mTORC1 signaling. Our data indicate that p90(RSKs) are dispensable for the activation of mTORC1 signaling by phorbol esters in all cell types tested. Our data also reveal striking diversity in the requirements for MEK/ERK in the control of mTORC1 between different cell types, pointing to additional signaling connections between phorbol esters and mTORC1, which do not involve MEK/ERK. This study provides important information for the design of efficient strategies to combat the hyperactivation of mTORC1 signaling by oncogenic pathways.
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Affiliation(s)
- Bruno D Fonseca
- Division of Molecular Physiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
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Leach NR, Roller RJ. Significance of host cell kinases in herpes simplex virus type 1 egress and lamin-associated protein disassembly from the nuclear lamina. Virology 2010; 406:127-37. [PMID: 20674954 DOI: 10.1016/j.virol.2010.07.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/23/2010] [Accepted: 07/01/2010] [Indexed: 12/25/2022]
Abstract
The nuclear lamina is thought to be a steric barrier to the herpesvirus capsid. Disruption of the lamina accompanied by phosphorylation of lamina proteins is a conserved feature of herpesvirus infection. In HSV-1-infected cells, protein kinase C (PKC) alpha and delta isoforms are recruited to the nuclear membrane and PKC delta has been implicated in phosphorylation of emerin and lamin B. We tested two critical hypotheses about the mechanism and significance of lamina disruption. First, we show that chemical inhibition of all PKC isoforms reduced viral growth five-fold and inhibited capsid egress from the nucleus. However, specific inhibition of either conventional PKCs or PKC delta does not inhibit viral growth. Second, we show hyperphosphorylation of emerin by viral and cellular kinases is required for its disassociation from the lamina. These data support hypothesis that phosphorylation of lamina components mediates lamina disruption during HSV nuclear egress.
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Affiliation(s)
- Natalie R Leach
- Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA 52242, USA
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Musnier A, Blanchot B, Reiter E, Crépieux P. GPCR signalling to the translation machinery. Cell Signal 2009; 22:707-16. [PMID: 19887105 DOI: 10.1016/j.cellsig.2009.10.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 10/23/2009] [Indexed: 12/26/2022]
Abstract
G protein-coupled receptors (GPCRs) are involved in most physiological processes, many of them being engaged in fully differentiated cells. These receptors couple to transducers of their own, primarily G proteins and beta-arrestins, which launch intracellular signalling cascades. Some of these signalling events regulate the translational machinery to fine-tune general cell metabolism or to alter protein expression pattern. Though extensively documented for tyrosine kinase receptors, translational regulation by GPCRs is still poorly appreciated. The objective of this review paper is to address the following questions: i) is there a "GPCR signature" impacting on the translational machinery, and ultimately on the type of mRNA translated? ii) are the regulatory networks involved similar as those utilized by tyrosine kinase receptors? In particular, we will discuss the specific features of translational control mediated by GPCRs and highlight the intrinsic properties of GPCRs these mechanisms could rely on.
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Affiliation(s)
- Astrid Musnier
- BIOS group, INRA, UMR, Unité Physiologie de la Reproduction et des Comportements, Nouzilly, France
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15
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Screen for chemical modulators of autophagy reveals novel therapeutic inhibitors of mTORC1 signaling. PLoS One 2009; 4:e7124. [PMID: 19771169 PMCID: PMC2742736 DOI: 10.1371/journal.pone.0007124] [Citation(s) in RCA: 285] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 08/17/2009] [Indexed: 02/04/2023] Open
Abstract
Background Mammalian target of rapamycin complex 1 (mTORC1) is a protein kinase that relays nutrient availability signals to control numerous cellular functions including autophagy, a process of cellular self-eating activated by nutrient depletion. Addressing the therapeutic potential of modulating mTORC1 signaling and autophagy in human disease requires active chemicals with pharmacologically desirable properties. Methodology/Principal Findings Using an automated cell-based assay, we screened a collection of >3,500 chemicals and identified three approved drugs (perhexiline, niclosamide, amiodarone) and one pharmacological reagent (rottlerin) capable of rapidly increasing autophagosome content. Biochemical assays showed that the four compounds stimulate autophagy and inhibit mTORC1 signaling in cells maintained in nutrient-rich conditions. The compounds did not inhibit mTORC2, which also contains mTOR as a catalytic subunit, suggesting that they do not inhibit mTOR catalytic activity but rather inhibit signaling to mTORC1. mTORC1 inhibition and autophagosome accumulation induced by perhexiline, niclosamide or rottlerin were rapidly reversed upon drug withdrawal whereas amiodarone inhibited mTORC1 essentially irreversibly. TSC2, a negative regulator of mTORC1, was required for inhibition of mTORC1 signaling by rottlerin but not for mTORC1 inhibition by perhexiline, niclosamide and amiodarone. Transient exposure of immortalized mouse embryo fibroblasts to these drugs was not toxic in nutrient-rich conditions but led to rapid cell death by apoptosis in starvation conditions, by a mechanism determined in large part by the tuberous sclerosis complex protein TSC2, an upstream regulator of mTORC1. By contrast, transient exposure to the mTORC1 inhibitor rapamycin caused essentially irreversible mTORC1 inhibition, sustained inhibition of cell growth and no selective cell killing in starvation. Conclusion/Significance The observation that drugs already approved for human use can reversibly inhibit mTORC1 and stimulate autophagy should greatly facilitate the preclinical and clinical testing of mTORC1 inhibition for indications such as tuberous sclerosis, diabetes, cardiovascular disease and cancer.
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Kim MS, Wang F, Puthanveetil P, Kewalramani G, Hosseini-Beheshti E, Ng N, Wang Y, Kumar U, Innis S, Proud CG, Abrahani A, Rodrigues B. Protein kinase D is a key regulator of cardiomyocyte lipoprotein lipase secretion after diabetes. Circ Res 2008; 103:252-60. [PMID: 18583709 DOI: 10.1161/circresaha.108.178681] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The diabetic heart switches to exclusively using fatty acid (FA) for energy supply and does so by multiple mechanisms including hydrolysis of lipoproteins by lipoprotein lipase (LPL) positioned at the vascular lumen. We determined the mechanism that leads to an increase in LPL after diabetes. Diazoxide (DZ), an agent that decreases insulin secretion and causes hyperglycemia, induced a substantial increase in LPL activity at the vascular lumen. This increase in LPL paralleled a robust phosphorylation of Hsp25, decreasing its association with PKCdelta, allowing this protein kinase to phosphorylate and activate protein kinase D (PKD), an important kinase that regulates fission of vesicles from the golgi membrane. Rottlerin, a PKCdelta inhibitor, prevented PKD phosphorylation and the subsequent increase in LPL. Incubating control myocytes with high glucose and palmitic acid (Glu+PA) also increased the phosphorylation of Hsp25, PKCdelta, and PKD in a pattern similar to that seen with diabetes, in addition to augmenting LPL activity. In myocytes in which PKD was silenced or a mutant form of PKCdelta was expressed, high Glu+PA were incapable of increasing LPL. Moreover, silencing of cardiomyocyte Hsp25 allowed phorbol 12-myristate 13-acetate to elicit a significant phosphorylation of PKCdelta, an appreciable association between PKCdelta and PKD, and a vigorous activation of PKD. As these cells also demonstrated an additional increase in LPL, our data imply that after diabetes, PKD control of LPL requires dissociation of Hsp25 from PKCdelta, association between PKCdelta and PKD, and vesicle fission. Results from this study could help in restricting cardiac LPL translocation, leading to strategies that overcome contractile dysfunction after diabetes.
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Affiliation(s)
- Min Suk Kim
- Faculty of Pharmaceutical Sciences, Vancouver, BC, Canada
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Zvezdina ND, Mal’chenko LA, Fateeva VI, Brodsky VY. Signaling factors of self-organization of protein synthesis rhythm in hepatocyte cultures—gangliosides and catecholamines function independently. Russ J Dev Biol 2008. [DOI: 10.1134/s106236040803003x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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18
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Moschella PC, Rao VU, McDermott PJ, Kuppuswamy D. Regulation of mTOR and S6K1 activation by the nPKC isoforms, PKCepsilon and PKCdelta, in adult cardiac muscle cells. J Mol Cell Cardiol 2007; 43:754-66. [PMID: 17976640 DOI: 10.1016/j.yjmcc.2007.09.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 09/14/2007] [Accepted: 09/25/2007] [Indexed: 11/29/2022]
Abstract
Activation of both mTOR and its downstream target, S6K1 (p70 S6 kinase) have been implicated to affect cardiac hypertrophy. Our earlier work, in a feline model of 1-48 h pressure overload, demonstrated that mTOR/S6K1 activation occurred primarily through a PKC/c-Raf pathway. To further delineate the role of specific PKC isoforms on mTOR/S6K1 activation, we utilized primary cultures of adult feline cardiomyocytes in vitro and stimulated with endothelin-1 (ET-1), phenylephrine (PE), TPA, or insulin. All agonist treatments resulted in S2248 phosphorylation of mTOR and T389 and S421/T424 phosphorylation of S6K1, however only ET-1 and TPA-stimulated mTOR/S6K1 activation was abolished with infection of a dominant negative adenoviral c-Raf (DN-Raf) construct. Expression of DN-PKC(epsilon) blocked ET-1-stimulated mTOR S2448 and S6K1 S421/T424 and T389 phosphorylation but had no effect on insulin-stimulated S6K1 phosphorylation. Expression of DN-PKC(delta) or pretreatment of cardiomyocytes with rottlerin, a PKC(delta) specific inhibitor, blocked both ET-1 and insulin stimulated mTOR S2448 and S6K1 T389 phosphorylation. However, treatment with Gö6976, a specific classical PKC (cPKC) inhibitor did not affect mTOR/S6K1 activation. These data indicate that: (i) PKC(epsilon) is required for ET-1-stimulated T421/S424 phosphorylation of S6K1, (ii) both PKC(epsilon) and PKC(delta) are required for ET-1-stimulated mTOR S2448 and S6K1 T389 phosphorylation, (iii) PKC(delta) is also required for insulin-stimulated mTOR S2448 and S6K1 T389 phosphorylation. Together, these data delineate both distinct and combinatorial roles of specific PKC isoforms on mTOR and S6K1 activation in adult cardiac myocytes following hypertrophic stimulation.
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Affiliation(s)
- Phillip C Moschella
- Cardiology Division of the Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, 114 Doughty Street, Charleston, SC 29425, USA
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Vary TC, Deiter G, Lynch CJ. Rapamycin limits formation of active eukaryotic initiation factor 4F complex following meal feeding in rat hearts. J Nutr 2007; 137:1857-62. [PMID: 17634255 DOI: 10.1093/jn/137.8.1857] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Feeding promotes protein synthesis in cardiac muscle through a stimulation of the messenger RNA translation initiation phase of protein synthesis by enhancing assembly of active eukaryotic initiation factor (eIF)4F complex. The experiments reported herein examined the potential role for a rapamycin-sensitive signaling pathway in increasing formation of active eIF4G-eIF4E complex during meal feeding. Hearts from male Sprague-Dawley rats fed a meal consisting of rat nonpurified diet were sampled prior to and 3 h following the meal in the presence or absence of treatment with rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR) complex 1. Rapamycin prevented the meal feeding-induced stimulation of myocardial protein synthesis. Inhibition of mTOR with rapamycin decreased the association of rapamycin-associated TOR protein with mTOR and prevented the feeding-induced assembly of eIF4G-eIF4E complex. In contrast, the abundance of eIF4E binding protein-1 (4E-BP1)-eIF4E complex was unaffected by either meal feeding or rapamycin. Pretreatment with rapamycin completely prevented the feeding-induced phosphorylation of eIF4G(Ser(1108)), whereas the inhibitor only partially attenuated meal feeding-induced 70-kDa ribosomal protein S6 kinase1(Thr(389)) phosphorylation and extent of 4E-BP1 in the gamma-form. Meal feeding-induced phosphorylation of protein kinase B on either Ser(473) or Thr(308) was unaffected by rapamycin. These findings suggest the extent of phosphorylation of eIF4G following meal feeding occurs by a rapamycin-sensitive mechanism in cardiac muscle. Furthermore, the rapamycin-sensitive reductions in phosphorylation of eIF4G may also lead to decreased formation of active eIF4G-eIF4E complex.
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Affiliation(s)
- Thomas C Vary
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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20
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Judé S, Martel E, Vincent F, Besson P, Couet C, Ogilvie GK, Pinault M, De Chalendar C, Bougnoux P, Richard S, Champeroux P, Crozatier B, Le Guennec JY. Dietary long-chain n-3 fatty acids modify blood and cardiac phospholipids and reduce protein kinase-C-delta and protein kinase-C-epsilon translocation. Br J Nutr 2007; 98:1143-51. [PMID: 17663802 DOI: 10.1017/s0007114507798914] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The effects of an n-3 PUFA-enriched diet on cardiac cell membrane phospholipid fraction compositions and associated protein kinase-C (PKC) translocation modification have never been studied in higher mammals. This is of importance since membrane fatty acid composition has been shown to influence PKC signalling pathways. In the present study, we have tested whether the incorporation of n-3 PUFA in cardiac membrane phospholipids correlated with changes in the fatty acid composition of diacylglycerols (DAG) and led to a differential translocation of PKC isoforms. Two groups of five dogs were fed the standard diet supplemented with palm oil or fish oil for 8 weeks. Dogs fed a fish oil-enriched diet showed a preferential incorporation of EPA and, to a lesser extent, of DHA, at the expense of arachidonic acid, in the circulating TAG, plasma phospholipids, erythrocyte phospholipids and cardiomyocyte phospholipid fractions. Analysis of 1,2-DAG fatty acid composition also indicated a preferential enrichment of EPA compared with DHA. Associated with these results, a reduction in the expression of PKC-delta and PKC-epsilon isoforms in the particulate fractions was observed whereas no effect was seen for PKC-alpha and PKC-zeta. We conclude that a fish oil-enriched diet induces a modification in fatty acid composition of cardiac membrane phospholipids, associated with a differential translocation of PKC isoforms. These results can be explained by the production of structurally different DAG that may participate in some of the protective effects of n-3 PUFA against various chronic diseases.
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Affiliation(s)
- Sébastien Judé
- CERB, Centre de Recherches Biologiques, Baugy, F-18800, France
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Alpert E, Gruzman A, Tennenbaum T, Sasson S. Selective cyclooxygenase-2 inhibitors stimulate glucose transport in L6 myotubes in a protein kinase Cδ-dependent manner. Biochem Pharmacol 2007; 73:368-77. [PMID: 17098211 DOI: 10.1016/j.bcp.2006.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 10/06/2006] [Accepted: 10/09/2006] [Indexed: 11/24/2022]
Abstract
Selective inhibitors of cyclooxygenase-2 (prostaglandin-endoperoxide synthase-2; COX-2) augment the rate of hexose uptake in myotubes by recruiting glucose transporter-4 (GLUT-4) to the plasma membrane in an insulin- and AMPKalpha-independent manner [Alpert E, Gruzman A, Lardi-Studler B, Cohen G, Reich R, Sasson S. Cyclooxygenase-2 (PTGS2) inhibitors augment the rate of hexose transport in L6 myotubes in an insulin- and AMPKalpha-independent manner. Diabetologia 2006;49:562-70]. We aimed at elucidating the molecular interactions that mediate this effect of COX-2 inhibitors in L6 myotubes. The effects of the inhibitors niflumic acid, nimesulide and rofecoxib on activities and phosphorylation state of key proteins in the insulin transduction pathway were determined. These inhibitors did not induce specific tyrosine phosphorylation in IRS-1, could not assemble a functional IRS-PI3K-PKB/Akt complex and did not activate GSK3alpha/beta, JNK1/2, ERK1/2, p38-MAPK or c-Cbl by site-specific phosphorylation(s). Yet, like insulin, they activated mTOR and induced downstream threonine phosphorylation in p70S6K and 4EBP1. However, rapamycin, which inhibits mTOR enzymatic activity, did not interfere with COX-2 inhibitor-induced stimulation of hexose uptake in myotube. Thus, mTOR activation was not required for COX-2 inhibitor-dependent augmentation of hexose transport in myotubes. Because PKCdelta has also been shown to activate mTOR, we asked whether COX-2 inhibitors activate mTOR by a prior activation of PKCdelta. Indeed, all three inhibitors induced tyrosine phosphorylation in PKCdelta and stimulated its kinase activity. Moreover, pharmacological inhibition of PKCdelta or the expression of a dominant-negative form of PKCdelta in myotubes completely abolished COX-2 inhibitor-dependent stimulation of hexose uptake. This study shows that selective COX-2 inhibitors activate a unique PKCdelta-dependent pathway to increase GLUT-4 abundance in the plasma membrane of myotubes and augment the rate of hexose transport.
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Affiliation(s)
- Evgenia Alpert
- Department of Pharmacology, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel
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22
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Gosens R, Grootte Bromhaar MM, Maarsingh H, ten Damme A, Meurs H, Zaagsma J, Nelemans SA. Bradykinin augments EGF-induced airway smooth muscle proliferation by activation of conventional protein kinase C isoenzymes. Eur J Pharmacol 2006; 535:253-62. [PMID: 16529737 DOI: 10.1016/j.ejphar.2006.01.065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 01/25/2006] [Accepted: 01/27/2006] [Indexed: 12/25/2022]
Abstract
This study aims to investigate the effects of bradykinin, alone and in combination with growth factors on proliferation of cultured bovine tracheal smooth muscle cells. Bradykinin did not induce mitogenic responses by itself, but concentration-dependently augmented growth factor-induced [3H]thymidine incorporation and cell proliferation. The bradykinin effect was mediated by bradykinin B2 receptors, and not dependent on cyclo-oxygenase. Bradykinin-induced synergism with epidermal growth factor (EGF) could be suppressed by the protein kinase C (PKC) inhibitors GF 109203X (Bisindolylmaleimide I; specific for conventional and novel PKCs) and Gö 6976 (12-(2-Cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole; specific for conventional PKCs). In addition, sole activation of PKC using Phorbol 12-myristate 13-acetate (PMA) was sufficient for a synergistic interaction with EGF. In contrast to bradykinin however, PMA was mitogenic by itself which was not at all affected by Gö 6976, but abolished by GF 109203X. Bradykinin transiently activated the p42/p44 MAP kinase pathway, whereas PMA-induced activation of p42/p44 mitogen activated protein (MAP) kinase was sustained. Neither the combination of bradykinin and EGF nor that of PMA and EGF induced synergistic activation of p42/p44 MAP kinase, however. These results show that bradykinin B2 receptor-stimulation augments growth factor-induced mitogenic responses of airway smooth muscle cells through activation of conventional PKC isozymes. In addition, the results show that PKC isozyme-specificity underlies stimulus-specific differences in mitogenic capacity for bradykinin and PMA.
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Affiliation(s)
- Reinoud Gosens
- Department of Molecular Pharmacology, University Centre for Pharmacy, University of Groningen, Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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Agnetti G, Maraldi T, Fiorentini D, Giordano E, Prata C, Hakim G, Muscari C, Guarnieri C, Caldarera CM. Activation of glucose transport during simulated ischemia in H9c2 cardiac myoblasts is mediated by protein kinase C isoforms. Life Sci 2005; 78:264-70. [PMID: 16111715 DOI: 10.1016/j.lfs.2005.04.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Accepted: 04/20/2005] [Indexed: 11/25/2022]
Abstract
Glucose transport into cells may be regulated by a variety of conditions, including ischemia. We investigated whether some enzymes frequently involved in the metabolic adaptation to ischemia are also required for glucose transport activation. Ischemia was simulated by incubating during 3 h H9c2 cardiomyoblasts in a serum- and glucose-free medium in hypoxia. Under these conditions 2-deoxy-d-[2,6-(3)H]-glucose uptake was increased (57% above control levels, p<0.0001) consistently with GLUT1 and GLUT4 translocation to sarcolemma. Tyrosine kinases inhibition via tyrphostin had no effect on glucose transport up-regulation induced by simulated ischemia. On the other hand, chelerythrine, a broad range inhibitor of protein kinase C isoforms, and rottlerin, an inhibitor of protein kinase C delta, completely prevented the stimulation of the transport rate. A lower activation of hexose uptake (19%, p<0.001) followed also treatment with Gö6976, an inhibitor of conventional protein kinases C. Finally, PD98059-mediated inhibition of the phosphorylation of ERK 1/2, a downstream mitogen-activated protein kinase (MAPK), only partially reduced the activation of glucose transport induced by simulated ischemia (31%, p<0.01), while SB203580, an inhibitor of p38 MAPK, did not exert any effect. These results indicate that stimulation of protein kinase C delta is strongly related to the up-regulation of glucose transport induced by simulated ischemia in cultured cardiomyoblasts and that conventional protein kinases C and ERK 1/2 are partially involved in the signalling pathways mediating this process.
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Affiliation(s)
- Giulio Agnetti
- Department of Biochemistry "G. Moruzzi", University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
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Pan J, Singh US, Takahashi T, Oka Y, Palm-Leis A, Herbelin BS, Baker KM. PKC mediates cyclic stretch-induced cardiac hypertrophy through Rho family GTPases and mitogen-activated protein kinases in cardiomyocytes. J Cell Physiol 2005; 202:536-53. [PMID: 15316932 DOI: 10.1002/jcp.20151] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Signaling events, including Rho GTPases and protein kinase C (PKC), are involved in cardiac hypertrophy. However, the mechanisms by which these pathways cooperate during the hypertrophic process remain unclear. Using an in vitro cyclic stretch model with neonatal rat cardiomyocytes, we demonstrated that stretch-induced activation of RhoA, Rac1/Cdc42, and phosphorylation of Rho-guanine nucleotide dissociation inhibitor (GDI) were prevented by inhibition or depletion of PKC, using chelerythrine and phorbol 12-myristate 13-acetate, indicating that phorbol ester-sensitive PKC isozymes may be upstream regulators of Rho GTPases. Using adenoviral-mediated gene transfer of wild-type (WT) and dominant-negative (DN) mutants of PKCalpha and delta, we found that stretch-induced activation of Rho GTPases and phosphorylation of Rho-GDI were mainly regulated by PKCalpha. PKCdelta was involved in regulation of the activation of Rac1. Stretch-induced increases in [(3)H]-leucine incorporation, myofibrillar reorganization and cell size, were blocked by inhibition of Rho GTPases, or overexpression of DN PKCalpha and delta, suggesting that PKCalpha and delta are both required in stretch-induced hypertrophy, through Rho GTPases-mediated signaling pathways. The mechanism, whereby PKC and Rho GTPases regulate hypertrophy, was associated with mitogen-activated protein (MAP) kinases. Stretch-stimulated phosphorylation of MEK1/ERK1/2 and MKK4/JNK was inhibited by overexpression of DN PKCalpha and delta, and that of MKK3/p38 inhibited by DN PKCdelta. The phosphorylation of ERK and JNK induced by overexpression of WT PKCalpha, and the phosphorylation of p38 induced by WT PKCdelta, were regulated by Rho GTPases. This study represents the first evidence that PKCalpha and delta are important regulators in mediating activation of Rho GTPases and MAP kinases, in the cyclic stretch-induced hypertrophic process.
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Affiliation(s)
- Jing Pan
- Division of Molecular Cardiology, Cardiovascular Research Institute, The Texas A&M University System Health Science Center, College of Medicine, Temple, Texas 76504, USA.
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Vega RB, Harrison BC, Meadows E, Roberts CR, Papst PJ, Olson EN, McKinsey TA. Protein kinases C and D mediate agonist-dependent cardiac hypertrophy through nuclear export of histone deacetylase 5. Mol Cell Biol 2004; 24:8374-85. [PMID: 15367659 PMCID: PMC516754 DOI: 10.1128/mcb.24.19.8374-8385.2004] [Citation(s) in RCA: 417] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 06/09/2004] [Accepted: 07/06/2004] [Indexed: 11/20/2022] Open
Abstract
A variety of stress signals stimulate cardiac myocytes to undergo hypertrophy. Persistent cardiac hypertrophy is associated with elevated risk for the development of heart failure. Recently, we showed that class II histone deacetylases (HDACs) suppress cardiac hypertrophy and that stress signals neutralize this repressive function by triggering phosphorylation- and CRM1-dependent nuclear export of these chromatin-modifying enzymes. However, the identities of cardiac HDAC kinases have remained unclear. Here, we demonstrate that signaling by protein kinase C (PKC) is sufficient and, in some cases, necessary to drive nuclear export of class II HDAC5 in cardiomyocytes. Inhibition of PKC prevents nucleocytoplasmic shuttling of HDAC5 in response to a subset of hypertrophic agonists. Moreover, a nonphosphorylatable HDAC5 mutant is refractory to PKC signaling and blocks cardiomyocyte hypertrophy mediated by pharmacological activators of PKC. We also demonstrate that protein kinase D (PKD), a downstream effector of PKC, directly phosphorylates HDAC5 and stimulates its nuclear export. These findings reveal a novel function for the PKC/PKD axis in coupling extracellular cues to chromatin modifications that control cellular growth, and they suggest potential utility for small-molecule inhibitors of this pathway in the treatment of pathological cardiac gene expression.
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Affiliation(s)
- Rick B Vega
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148, USA
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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