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Duncker DJ, Boontje NM, Merkus D, Versteilen A, Krysiak J, Mearini G, El-Armouche A, de Beer VJ, Lamers JMJ, Carrier L, Walker LA, Linke WA, Stienen GJM, van der Velden J. Prevention of myofilament dysfunction by beta-blocker therapy in postinfarct remodeling. Circ Heart Fail 2009; 2:233-42. [PMID: 19808345 DOI: 10.1161/circheartfailure.108.806125] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Myofilament contractility of individual cardiomyocytes is depressed in remote noninfarcted myocardium and contributes to global left ventricular pump dysfunction after myocardial infarction (MI). Here, we investigated whether beta-blocker therapy could restore myofilament contractility. METHODS AND RESULTS In pigs with a MI induced by ligation of the left circumflex coronary artery, beta-blocker therapy (bisoprolol, MI+beta) was initiated on the first day after MI. Remote left ventricular subendocardial biopsies were taken 3 weeks after sham or MI surgery. Isometric force was measured in single permeabilized cardiomyocytes. Maximal force (F(max)) was lower, whereas Ca(2+) sensitivity was higher in untreated MI compared with sham (both P<0.05). The difference in Ca(2+) sensitivity was abolished by treatment of cells with the beta-adrenergic kinase, protein kinase A. beta-blocker therapy partially reversed F(max) and Ca(2+) sensitivity to sham values and significantly reduced passive force. Despite the lower myofilament Ca(2+) sensitivity in MI+beta compared with untreated myocardium, the protein kinase A induced reduction in Ca(2+) sensitivity was largest in cardiomyocytes from myocardium treated with beta-blockers. Phosphorylation of beta-adrenergic target proteins (myosin binding protein C and troponin I) did not differ among groups, whereas myosin light chain 2 phosphorylation was reduced in MI, which coincided with increased expression of protein phosphatase 1. beta-blockade fully restored the latter alterations and significantly reduced expression of protein phosphatase 2a. CONCLUSIONS beta-blockade reversed myofilament dysfunction and enhanced myofilament responsiveness to protein kinase A in remote myocardium after MI. These effects likely contribute to the beneficial effects of beta-blockade on global left ventricular function after MI.
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Affiliation(s)
- Dirk J Duncker
- Department of Biochemistry, Cardiovascular Research School COEUR, Erasmus MC, University Medical Center Rotterdam, Thoraxcenter, Rotterdam, The Netherlands
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52
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Nicolaou P, Rodriguez P, Ren X, Zhou X, Qian J, Sadayappan S, Mitton B, Pathak A, Robbins J, Hajjar RJ, Jones K, Kranias EG. Inducible expression of active protein phosphatase-1 inhibitor-1 enhances basal cardiac function and protects against ischemia/reperfusion injury. Circ Res 2009; 104:1012-20. [PMID: 19299645 DOI: 10.1161/circresaha.108.189811] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ischemic heart disease, which remains the leading cause of morbidity and mortality in the Western world, is invariably characterized by impaired cardiac function and disturbed Ca(2+) homeostasis. Because enhanced inhibitor-1 (I-1) activity has been suggested to preserve Ca(2+) cycling, we sought to define whether increases in I-1 activity in the adult heart may ameliorate contractile dysfunction and cellular injury in the face of an ischemic insult. To this end, we generated an inducible transgenic mouse model that enabled temporally controlled expression of active I-1 (T35D). Active I-1 expression in the adult heart elicited significant enhancement of contractile function, associated with preferential phospholamban phosphorylation and enhanced sarcoplasmic reticulum Ca(2+)-transport. Further phosphoproteomic analysis revealed alterations in proteins associated with energy production and protein synthesis, possibly to support the increased metabolic demands of the hyperdynamic hearts. Importantly, on ischemia/reperfusion-induced injury, active I-1 expression augmented contractile function and recovery. Further examination revealed that the infarct region and apoptotic as well as necrotic injuries were significantly attenuated by enhanced I-1 activity. These cardioprotective effects were associated with suppression of the endoplasmic reticulum stress response. The present findings indicate that increased I-1 activity in the adult heart enhances Ca(2+) cycling and improves mechanical recovery, as well as cell survival after an ischemic insult, suggesting that active I-1 may represent a potential therapeutic strategy in myocardial infarction.
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Affiliation(s)
- Persoulla Nicolaou
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA
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Abstract
Atrial electrical and structural alterations (remodeling) have emerged as key elements in the development of the atrial fibrillation (AF) substrate. Evidence points to abnormalities in intracellular Ca (calcium) handling as crucial links in AF-initiating focal activity and in perpetuation by rapidly firing foci and reentry. This review focuses on the molecular basis of altered Ca handling in AF, with the goal of providing new insights into molecular effective antiarrhythmic therapy.
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Xu Y, Li X, Zhou M. Neuregulin-1/ErbB signaling: a druggable target for treating heart failure. Curr Opin Pharmacol 2008; 9:214-9. [PMID: 19070544 DOI: 10.1016/j.coph.2008.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 11/03/2008] [Accepted: 11/03/2008] [Indexed: 11/28/2022]
Abstract
Neuregulin-1s are widely expressed signaling molecules that are involved in cell differentiation, proliferation, growth, survival, and apoptosis. They transmit their signals by interacting with cell membrane receptors of the ErbB family, resulting in the activation of intracellular signaling cascades, which participate in various physiological and etiological processes. Besides their essential function in the development of the heart and the physiology of cardiac pumping, there is emerging evidence for the involvement of neuregulin-1/ErbB signals in human disease, including heart failure. These reasons prompt the development of new therapeutic agents based on neuregulin-1.
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Affiliation(s)
- Yabei Xu
- Zensun (Shanghai) Science and Technology Co. Ltd, 328 Bi Bo Road, Zhangjiang Hi-tech Park, Shanghai, PR China
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56
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Schwoerer AP, Neuber C, Schmechel A, Melnychenko I, Mearini G, Boknik P, Kirchhefer U, Schmitz W, Ehmke H, Eschenhagen T, El-Armouche A. Mechanical unloading of the rat heart involves marked changes in the protein kinase–phosphatase balance. J Mol Cell Cardiol 2008; 45:846-52. [DOI: 10.1016/j.yjmcc.2008.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 09/08/2008] [Accepted: 09/08/2008] [Indexed: 02/06/2023]
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57
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Davis J, Westfall MV, Townsend D, Blankinship M, Herron TJ, Guerrero-Serna G, Wang W, Devaney E, Metzger JM. Designing heart performance by gene transfer. Physiol Rev 2008; 88:1567-651. [PMID: 18923190 DOI: 10.1152/physrev.00039.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca(2+) handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.
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Affiliation(s)
- Jennifer Davis
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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58
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Chen G, Zhou X, Pathak A, Dorn GW, Kranias EG. The human G147D-protein phosphatase 1 inhibitor-1 polymorphism is not associated with altered clinical characteristics in heart failure. Cardiology 2008; 112:224-31. [PMID: 18698139 DOI: 10.1159/000151240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Accepted: 04/30/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVES A human protein phosphatase inhibitor-1 polymorphism, G147D (c.440G>A, p.147G>D), has been previously demonstrated to blunt the contractile responses of cardiomyocytes to beta-adrenergic agonists. The present study sought to examine whether the G147D inhibitor-1 polymorphism may be associated with specific clinical characteristics of heart failure carriers. METHODS Clinical information of 963 heart failure patients was analyzed according to race, inhibitor-1 genotype, treatment with beta-blockers and mortality patterns. RESULTS The G147D inhibitor-1 genetic variant was found almost exclusively in black subjects and its frequency was similar between normals and heart failure patients, indicating that it was not a primary risk factor for developing heart failure. Comparison of the major cardiac functional parameters and transplant-free survival patterns between carrier and noncarrier patients did not reveal any significant differences. Furthermore, echocardiographic evaluation showed similar outcomes of beta-blocker treatment between G147D carriers and noncarriers. CONCLUSIONS The present findings indicate that the human inhibitor-1 G147D polymorphism, found almost exclusively in blacks, may act as a modifier rather than risk factor in heart failure development.
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Affiliation(s)
- Guoli Chen
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575, USA
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59
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El-Armouche A, Wittköpper K, Degenhardt F, Weinberger F, Didié M, Melnychenko I, Grimm M, Peeck M, Zimmermann WH, Unsöld B, Hasenfuss G, Dobrev D, Eschenhagen T. Phosphatase inhibitor-1-deficient mice are protected from catecholamine-induced arrhythmias and myocardial hypertrophy. Cardiovasc Res 2008; 80:396-406. [PMID: 18689792 DOI: 10.1093/cvr/cvn208] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Phosphatase inhibitor-1 (I-1) is a conditional amplifier of beta-adrenergic signalling downstream of protein kinase A by inhibiting type-1 phosphatases only in its PKA-phosphorylated form. I-1 is downregulated in failing hearts and thus contributes to beta-adrenergic desensitization. It is unclear whether this should be viewed as a predominantly adverse or protective response. METHODS AND RESULTS We generated transgenic mice with cardiac-specific I-1 overexpression (I-1-TG) and evaluated cardiac function and responses to catecholamines in mice with targeted disruption of the I-1 gene (I-1-KO). Both groups were compared with their wild-type (WT) littermates. I-1-TG developed cardiac hypertrophy and mild dysfunction which was accompanied by a substantial compensatory increase in PP1 abundance and activity, confounding cause-effect relationships. I-1-KO had normal heart structure with mildly reduced sensitivity, but unchanged maximal contractile responses to beta-adrenergic stimulation, both in vitro and in vivo. Notably, I-1-KO were partially protected from lethal catecholamine-induced arrhythmias and from hypertrophy and dilation induced by a 7 day infusion with the beta-adrenergic agonist isoprenaline. Moreover, I-1-KO exhibited a partially preserved acute beta-adrenergic response after chronic isoprenaline, which was completely absent in similarly treated WT. At the molecular level, I-1-KO showed lower steady-state phosphorylation of the cardiac ryanodine receptor/Ca(2+) release channel and the sarcoplasmic reticulum (SR) Ca(2+)-ATPase-regulating protein phospholamban. These alterations may lower the propensity for diastolic Ca(2+) release and Ca(2+) uptake and thus stabilize the SR and account for the protection. CONCLUSION Taken together, loss of I-1 attenuates detrimental effects of catecholamines on the heart, suggesting I-1 downregulation in heart failure as a beneficial desensitization mechanism and I-1 inhibition as a potential novel strategy for heart failure treatment.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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60
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Brüchert N, Mavila N, Boknik P, Baba HA, Fabritz L, Gergs U, Kirchhefer U, Kirchhof P, Matus M, Schmitz W, DePaoli-Roach AA, Neumann J. Inhibitor-2 prevents protein phosphatase 1-induced cardiac hypertrophy and mortality. Am J Physiol Heart Circ Physiol 2008; 295:H1539-46. [PMID: 18689497 DOI: 10.1152/ajpheart.00515.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac-specific overexpression of the catalytic subunit of protein phosphatase type 1 (PP1) in mice results in hypertrophy, depressed contractility, propensity to heart failure, and premature death. To further address the role of PP1 in heart function, PP1 mice were crossed with mice that overexpress a functional COOH-terminally truncated form of PP1 inhibitor-2 (I-2(140)). Protein phosphatase activity was increased in PP1 mice but was normalized in double transgenic (DT) mice. The maximal rates of contraction (+dP/dt) and of relaxation (-dP/dt) were reduced in catheterized PP1 mice but normalized in DT mice. Similar contractile abnormalities were observed in isolated, perfused work-performing hearts and in whole animals by means of echocardiography. The increased absolute and relative heart weights observed in PP1 mice were normalized in DT mice. Histological analyses indicated that PP1 mice had significant cardiac fibrosis, which was absent in DT mice. Furthermore, PP1 mice exhibited an age-dependent increase in mortality, which was abrogated in DT mice. These results indicate that I-2 overexpression prevents the detrimental effects of PP1 overexpression in the heart and further underscore the fundamental role of PP1 in cardiac function. Therefore, PP1 inhibitors such as I-2 could offer new therapeutic options to ameliorate the deleterious effects of heart failure.
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Affiliation(s)
- Nicole Brüchert
- Institut für Pharmakologie und Toxikologie, Westfälische Wilhelms-Universität, Münster, Germany
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61
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Larsen KO, Lygren B, Sjaastad I, Krobert KA, Arnkvaern K, Florholmen G, Larsen AKR, Levy FO, Taskén K, Skjønsberg OH, Christensen G. Diastolic dysfunction in alveolar hypoxia: a role for interleukin-18-mediated increase in protein phosphatase 2A. Cardiovasc Res 2008; 80:47-54. [PMID: 18599478 DOI: 10.1093/cvr/cvn180] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
AIMS Chronic obstructive pulmonary disease with alveolar hypoxia is associated with diastolic dysfunction in the right and left ventricle (LV). LV diastolic dysfunction is not caused by increased afterload, and we recently showed that reduced phosphorylation of phospholamban at serine (Ser) 16 may explain the reduced relaxation of the myocardium. Here, we study the mechanisms leading to the hypoxia-induced reduction in phosphorylation of phospholamban at Ser16. METHODS AND RESULTS In C57Bl/6j mice exposed to 10% oxygen, signalling molecules were measured in cardiac tissue, sarcoplasmic reticulum (SR)-enriched membrane preparations, and serum. Cardiomyocytes isolated from neonatal mice were exposed to interleukin (IL)-18 for 24 h. The beta-adrenergic pathway in the myocardium was not altered by alveolar hypoxia, as assessed by measurements of beta-adrenergic receptor levels, adenylyl cyclase activity, and subunits of cyclic AMP-dependent protein kinase. However, alveolar hypoxia led to a significantly higher amount (124%) and activity (234%) of protein phosphatase (PP) 2A in SR-enriched membrane preparations from LV compared with control. Serum levels of an array of cytokines were assayed, and a pronounced increase in IL-18 was observed. In isolated cardiomyocytes, treatment with IL-18 increased the amount and activity of PP2A, and reduced phosphorylation of phospholamban at Ser16 to 54% of control. CONCLUSION Our results indicate that the diastolic dysfunction observed in alveolar hypoxia might be caused by increased circulating IL-18, thereby inducing an increase in PP2A and a reduction in phosphorylation of phospholamban at Ser16.
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Affiliation(s)
- Karl-Otto Larsen
- Department of Pulmonary Medicine, Ullevål University Hospital, University of Oslo, Oslo, Norway.
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62
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Grote-Wessels S, Baba HA, Boknik P, El-Armouche A, Fabritz L, Gillmann HJ, Kucerova D, Matus M, Muller FU, Neumann J, Schmitz M, Stumpel F, Theilmeier G, Wohlschlaeger J, Schmitz W, Kirchhefer U. Inhibition of protein phosphatase 1 by inhibitor-2 exacerbates progression of cardiac failure in a model with pressure overload. Cardiovasc Res 2008; 79:464-71. [DOI: 10.1093/cvr/cvn113] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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63
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Ikeda Y, Hoshijima M, Chien KR. Toward biologically targeted therapy of calcium cycling defects in heart failure. Physiology (Bethesda) 2008; 23:6-16. [PMID: 18268360 DOI: 10.1152/physiol.00033.2007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A growing body of evidence indicates that heart failure progression is tightly associated with dysregulation of phosphorylation of Ca2+ regulators localized in the sub-cellular microdomain of the sarcoplasmic reticulum. Chemical or genetic correction of abnormalities in cardiac phosphorylation cascades is emerging as a potential target in the treatment of heart failure. Here, we review how specific kinases and phosphatases finely tune Ca2+ cycling and regulate excitation-contraction (E-C) coupling in cardiomyocytes.
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Affiliation(s)
- Yasuhiro Ikeda
- Department of Molecular Cardiovascular Biology, Yamaguchi University School of Medicine, Ube, Japan.
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64
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El-Armouche A, Gocht F, Jaeckel E, Wittköpper K, Peeck M, Eschenhagen T. Long-term β-adrenergic stimulation leads to downregulation of protein phosphatase inhibitor-1 in the heart. Eur J Heart Fail 2007; 9:1077-80. [DOI: 10.1016/j.ejheart.2007.09.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 08/22/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022] Open
Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf; Hamburg Germany
| | - Fabian Gocht
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf; Hamburg Germany
| | - Elmar Jaeckel
- Department of Gastroenterology, Hepatology and Endocrinology; Medical School of Hannover; Germany
| | - Katrin Wittköpper
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf; Hamburg Germany
| | - Micha Peeck
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf; Hamburg Germany
| | - Thomas Eschenhagen
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf; Hamburg Germany
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Zimmermann WH, Eschenhagen T. Embryonic stem cells for cardiac muscle engineering. Trends Cardiovasc Med 2007; 17:134-40. [PMID: 17482096 DOI: 10.1016/j.tcm.2007.02.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 02/20/2007] [Accepted: 02/22/2007] [Indexed: 11/21/2022]
Abstract
The aim of cardiac tissue engineering is twofold: (1) to provide three-dimensional cardiac tissue to restore the function of diseased hearts and (2) to develop improved test beds for target validation and substance screening. Both concepts have been successfully demonstrated by several groups using immature primary heart cells, but these cells are essentially postmitotic, precluding clinical and large-scale in vitro applications. Identification of a renewable cell source is therefore one of the key objectives in the field. Embryonic stem (ES) cells are attractive candidates because they can be propagated in large quantities, have a robust capacity to differentiate into cardiac myocytes, and can be obtained from humans. Classic isolation of ES cells from the inner cell mass is associated with destruction of the respective embryo. Thus, alternative technologies to generate stem cell lines with ES cell properties are inevitably called for. This review discusses the usefulness of ES cells in cardiac tissue engineering and alternative, embryo-sparing technologies to derive ES cells.
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Affiliation(s)
- Wolfram-Hubertus Zimmermann
- Institute of Experimental and Clinical Pharmacology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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66
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Sheehan KA, Ke Y, Solaro RJ. p21-Activated kinase-1 and its role in integrated regulation of cardiac contractility. Am J Physiol Regul Integr Comp Physiol 2007; 293:R963-73. [PMID: 17609315 DOI: 10.1152/ajpregu.00253.2007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We review here a novel concept in the regulation of cardiac contractility involving variations in the activity of the multifunctional enzyme, p21-activated kinase 1 (Pak1), a member of a family of proteins in the small G protein-signaling pathway that is activated by Cdc42 and Rac1. There is a large body of evidence from studies in noncardiac tissue that Pak1 activity is key in regulation of a number of cellular functions, including cytoskeletal dynamics, cell motility, growth, and proliferation. Although of significant potential impact, the role of Pak1 in regulation of the heart has been investigated in only a few laboratories. In this review, we discuss the structure of Pak1 and its sites of posttranslational modification and molecular interactions. We assemble an overview of the current data on Pak1 signaling in noncardiac tissues relative to similar signaling pathways in the heart, and we identify potential roles of Pak1 in cardiac regulation. Finally, we discuss the current state of Pak1 research in the heart in regard to regulation of contractility through functional myofilament and Ca(2+)-flux modification. An important aspect of this regulation is the modulation of kinase and phosphatase activity. We have focused on Pak1 regulation of protein phosphatase 2A (PP2A), which is abundant in cardiac muscle, thereby mediating dephosphorylation of sarcomeric proteins and sensitizing the myofilaments to Ca(2+). We present a model for Pak1 signaling that provides a mechanism for specifically affecting cardiac cellular processes in which regulation of protein phosphorylation states by PP2A dephosphorylation predominates.
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Affiliation(s)
- Katherine A Sheehan
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott Ave., Chicago, IL 60612-7342, USA.
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67
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El-Armouche A, Singh J, Naito H, Wittköpper K, Didié M, Laatsch A, Zimmermann WH, Eschenhagen T. Adenovirus-delivered short hairpin RNA targeting PKCalpha improves contractile function in reconstituted heart tissue. J Mol Cell Cardiol 2007; 43:371-6. [PMID: 17628588 DOI: 10.1016/j.yjmcc.2007.05.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 04/23/2007] [Accepted: 05/29/2007] [Indexed: 12/13/2022]
Abstract
PKCalpha has been shown to be a negative regulator of contractility and PKCalpha gene deletion in mice protected against heart failure. Small interfering (si)RNAs mediate gene silencing by RNA interference (RNAi) and may be used to knockdown PKCalpha in cardiomyocytes. However, transfection efficiencies of (si)RNAs by lipofection tend to be low in primary cells. To address this limitation, we developed an adenoviral vector (AV) driving short hairpin (sh)RNAs against PKCalpha (Ad-shPKCalpha) and evaluated its potential to silence PKCalpha in neonatal rat cardiac myocytes and in engineered heart tissues (EHTs), which resemble functional myocardium in vitro. A nonsense encoding AV (Ad-shNS) served as control. Quantitative PCR and Western blotting showed 90% lower PKCalpha-mRNA and 50% lower PKCalpha protein in Ad-shPKCalpha-infected cells. EHTs were infected with Ad-shPKCalpha on day 11 and subjected to isometric force measurements in organ baths 4 days later. Mean twitch tension was >50% higher in Ad-shPKCalpha compared to Ad-shNS-infected EHTs, under basal and Ca(2+)- or isoprenaline-stimulated conditions. Twitch tension negatively correlated with PKCalpha mRNA levels. In summary, AV-delivered shRNA mediated highly efficient PKCalpha knockdown in cardiac myocytes and improved contractility in EHTs. The data support a role of PKCalpha as a negative regulator of myocardial contractility and demonstrate that EHTs in conjunction with AV-delivered shRNA are a useful model for target validation.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, D-20246, Germany.
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68
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El-Armouche A, Pohlmann L, Schlossarek S, Starbatty J, Yeh YH, Nattel S, Dobrev D, Eschenhagen T, Carrier L. Decreased phosphorylation levels of cardiac myosin-binding protein-C in human and experimental heart failure. J Mol Cell Cardiol 2007; 43:223-9. [PMID: 17560599 DOI: 10.1016/j.yjmcc.2007.05.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 05/03/2007] [Accepted: 05/07/2007] [Indexed: 01/13/2023]
Abstract
Cardiac myosin-binding protein-C (cMyBP-C) is an important regulator of cardiac contractility, and its phosphorylation by PKA is a mechanism that contributes to increased cardiac output in response to beta-adrenergic stimulation. It is presently unknown whether heart failure alters cMyBP-C phosphorylation. The present study determined the level of phosphorylated cMyBP-C in failing human hearts and in a canine model of pacing-induced heart failure. A polyclonal antibody directed against the major phosphorylation site of cMyBP-C (Ser-282) was generated and its specificity was confirmed by PKA phosphorylation with isoprenaline in cardiomyocytes and Langendorff-perfused mouse hearts. Left ventricular myocardial tissue from (i) patients with terminal heart failure (hHF; n=12) and nonfailing donor hearts (hNF; n=6) and (ii) dogs with rapid-pacing-induced end-stage heart failure (dHF; n=10) and sham-operated controls (dNF; n=10) were used for quantification of total cMyBP-C and phospho-cMyBP-C by Western blotting. Total cMyBP-C protein levels were similar in hHF and hNF as well as in dHF and dNF. In contrast, the ratio of phospho-cMyBP-C to total cMyBP-C levels were >50% reduced in hHF and >40% reduced in dHF. In summary, cMyBP-C phosphorylation levels are markedly decreased in human and experimental heart failure. Thus, the compromised contractile function of the failing heart might be in part attributable to reduced cMyBP-C phosphorylation levels.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, D-20246, Germany.
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Nguyen C, Nishi A, Kansy JW, Fernandez J, Hayashi K, Gillardon F, Hemmings HC, Nairn AC, Bibb JA. Regulation of protein phosphatase inhibitor-1 by cyclin-dependent kinase 5. J Biol Chem 2007; 282:16511-20. [PMID: 17400554 PMCID: PMC4296900 DOI: 10.1074/jbc.m701046200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Inhibitor-1, the first identified endogenous inhibitor of protein phosphatase 1 (PP-1), was previously reported to be a substrate for cyclin-dependent kinase 5 (Cdk5) at Ser67. Further investigation has revealed the presence of an additional Cdk5 site identified by mass spectrometry and confirmed by site-directed mutagenesis as Ser6. Basal levels of phospho-Ser6 inhibitor-1, as detected by a phosphorylation state-specific antibody against the site, existed in specific regions of the brain and varied with age. In the striatum, basal in vivo phosphorylation and dephosphorylation of Ser6 were mediated by Cdk5, PP-2A, and PP-1, respectively. Additionally, calcineurin contributed to dephosphorylation under conditions of high Ca2+. In biochemical assays the function of Cdk5-dependent phosphorylation of inhibitor-1 at Ser6 and Ser67 was demonstrated to be an intramolecular impairment of the ability of inhibitor-1 to be dephosphorylated at Thr35; this effect was recapitulated in two systems in vivo. Dephosphorylation of inhibitor-1 at Thr35 is equivalent to inactivation of the protein, as inhibitor-1 only serves as an inhibitor of PP-1 when phosphorylated by cAMP-dependent kinase (PKA) at Thr35. Thus, inhibitor-1 serves as a critical junction between kinase- and phosphatase-signaling pathways, linking PP-1 to not only PKA and calcineurin but also Cdk5.
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Affiliation(s)
- Chan Nguyen
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Akinori Nishi
- Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Janice W. Kansy
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Joseph Fernandez
- Protein/DNA Technology Center, Rockefeller University, New York, New York 10021
| | - Kanehiro Hayashi
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Frank Gillardon
- Central Nervous System Research, Boehringer Ingelheim Pharma KG, 88397 Biberach an der Riss, Germany
| | - Hugh C. Hemmings
- Departments of Anesthesiology and Pharmacology, Weill Medical College of Cornell University, New York, New York 10021
| | - Angus C. Nairn
- Laboratory of Cellular and Molecular Neuroscience, Rockefeller University, New York, New York 10021
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508
| | - James A. Bibb
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- To whom correspondence should be addressed: Dept. of Psychiatry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9070. Tel.: 214-648-4168; Fax: 214-648-1293;
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70
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Fischmeister R, Castro LRV, Abi-Gerges A, Rochais F, Jurevicius J, Leroy J, Vandecasteele G. Compartmentation of cyclic nucleotide signaling in the heart: the role of cyclic nucleotide phosphodiesterases. Circ Res 2006; 99:816-28. [PMID: 17038651 DOI: 10.1161/01.res.0000246118.98832.04] [Citation(s) in RCA: 302] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A current challenge in cellular signaling is to decipher the complex intracellular spatiotemporal organization that any given cell type has developed to discriminate among different external stimuli acting via a common signaling pathway. This obviously applies to cAMP and cGMP signaling in the heart, where these cyclic nucleotides determine the regulation of cardiac function by many hormones and neuromediators. Recent studies have identified cyclic nucleotide phosphodiesterases as key actors in limiting the spread of cAMP and cGMP, and in shaping and organizing intracellular signaling microdomains. With this new role, phosphodiesterases have been promoted from the rank of a housekeeping attendant to that of an executive officer.
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Affiliation(s)
- Rodolphe Fischmeister
- INSERM U769, Université Paris-Sud 11, Faculté de Pharmacie, 5, Rue J.-B. Clément, F-92296 Châtenay-Malabry Cedex, France.
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71
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Rodriguez P, Mitton B, Waggoner JR, Kranias EG. Identification of a novel phosphorylation site in protein phosphatase inhibitor-1 as a negative regulator of cardiac function. J Biol Chem 2006; 281:38599-608. [PMID: 17046826 DOI: 10.1074/jbc.m604139200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human and experimental heart failure is characterized by increases in type-1 protein phosphatase activity, which may be partially attributed to inactivation of its endogenous regulator, protein phosphatase inhibitor-1. Inhibitor-1 represents a nodal integrator of two major second messenger pathways, adenosine 3',5'-cyclic monophosphate (cAMP) and calcium, which mediate its phosphorylation at threonine 35 and serine 67, respectively. Here, using recombinant inhibitor-1 wild-type and mutated proteins, we identified a novel phosphorylation site in inhibitor-1, threonine 75. This phosphoamino acid was phosphorylated in vitro by protein kinase Calpha independently and to the same extent as serine 67, the previous protein kinase Calpha-identified site. Generation of specific antibodies for the phosphorylated and dephosphorylated threonine 75 revealed that this site is phosphorylated in rat and dog hearts. Adenoviral-mediated expression of the constitutively phosphorylated threonine 75 inhibitor-1 in isolated myocytes was associated with specific stimulation of type-1 protein phosphatase activity and marked inhibition of the sarcoplasmic calcium pump affinity for calcium, resulting in depressed contractility. Thus, phosphorylation of inhibitor-1 at threonine 75 represents a new mechanism of cardiac contractility regulation, partially through the alteration of sarcoplasmic reticulum calcium transport activity.
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Affiliation(s)
- Patricia Rodriguez
- Department of Pharmacology and Cell Biophysics, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
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72
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Vandecasteele G, Rochais F, Abi-Gerges A, Fischmeister R. Functional localization of cAMP signalling in cardiac myocytes. Biochem Soc Trans 2006; 34:484-8. [PMID: 16856839 DOI: 10.1042/bst0340484] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The cAMP pathway is of cardinal importance for heart physiology and pathology. The spatial organization of the various components of the cAMP pathway is thought to allow the segregation of functional responses triggered by the different neuromediators and hormones that use this pathway. PDEs (phosphodiesterases) hydrolyse cAMP (and cGMP) and play a major role in this process by preventing cAMP diffusion to the whole cytosol and inadequate target activation. The development of olfactory cyclic nucleotide-gated channels to directly monitor cAMP beneath the plasma membrane in real time allows us to gain new insights into the molecular mechanisms responsible for cAMP homoeostasis and hormonal specificity in cardiac cells. The present review summarizes the recent results we obtained using this approach in adult rat ventricular myocytes. In particular, the role of PDEs in the maintenance of specific cAMP signals generated by beta-adrenergic receptors and other G(s)-coupled receptors will be discussed.
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Affiliation(s)
- G Vandecasteele
- INSERM U769, Faculté de Pharmacie, Université de Paris-Sud 11, Châtenay-Malabry, France.
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73
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Mueller EE, Grandy SA, Howlett SE. Protein kinase A-mediated phosphorylation contributes to enhanced contraction observed in mice that overexpress beta-adrenergic receptor kinase-1. J Pharmacol Exp Ther 2006; 319:1307-16. [PMID: 16951260 DOI: 10.1124/jpet.106.107888] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Transgenic mice with cardiac specific overexpression of beta-adrenergic receptor kinase-1 (betaARK-1) exhibit reduced contractility in the presence of adrenergic stimulation. However, whether contractility is altered in the absence of exogenous agonist is not clear. Effects of betaARK-1 overexpression on contraction were examined in mouse ventricular myocytes, studied at 37 degrees C, in the absence of adrenergic stimulation. In myocytes voltage-clamped with microelectrodes (18-26 MOmega; 2.7 M KCl) to minimize intracellular dialysis, contractions were significantly larger in betaARK-1 cells than in wild-type myocytes. In contrast, when cells were dialyzed with patch pipette solution (1-3 MOmega; 0 mM NaCl, 70 mM KCl, 70 mM potassium aspartate, 4 mM MgATP, 1 mM MgCl(2), 2.5 mM KH(2)PO(4), 0.12 mM CaCl(2), 0.5 mM EGTA, and 10 mM HEPES), the extent of cell shortening was similar in wild-type and betaARK-1 myocytes. Furthermore, when cells were dialyzed with solutions that contained phosphodiesterase-sensitive sodium-cAMP (50 microM), the extent of cell shortening was similar in wild-type and betaARK-1 myocytes. However, when patch solutions were supplemented with phosphodiesterase-resistant 8-bromo-cAMP (50 muM), contractions were larger in betaARK-1 than wild-type cells. This difference was eliminated by the protein kinase A inhibitor N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H89). Interestingly, Ca(2+) current amplitudes and inactivation rates were similar in betaARK-1 and wild-type cells in all experiments. These results suggest components of the adenylyl cyclase-protein kinase A pathway are sensitized by chronically increased betaARK-1 activity, which may augment contractile function in the absence of exogenous agonist. Thus, changes in contractile function in myocytes from failing hearts may reflect, in part, effects of chronic up-regulation of betaARK-1 on the cAMP-protein kinase A pathway.
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Affiliation(s)
- Erin E Mueller
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
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74
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El-Armouche A, Boknik P, Eschenhagen T, Carrier L, Knaut M, Ravens U, Dobrev D. Molecular Determinants of Altered Ca
2+
Handling in Human Chronic Atrial Fibrillation. Circulation 2006; 114:670-80. [PMID: 16894034 DOI: 10.1161/circulationaha.106.636845] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Background—
Abnormal Ca
2+
handling may contribute to impaired atrial contractility and arrhythmogenesis in human chronic atrial fibrillation (cAF). Here, we assessed the phosphorylation levels of key proteins involved in altered Ca
2+
handling and contractility in cAF patients.
Methods and Results—
Total and phosphorylation levels of Ca
2+
-handling and myofilament proteins were analyzed by Western blotting in right atrial appendages of 49 patients in sinus rhythm and 52 cAF patients. We found a higher total activity of type 1 (PP1) and type 2A phosphatases in cAF, which was associated with inhomogeneous changes of protein phosphorylation in the cellular compartments, ie, lower protein kinase A (PKA) phosphorylation of myosin binding protein-C (Ser-282 site) at the thick myofilaments but preserved PKA phosphorylation of troponin I at the thin myofilaments and enhanced PKA (Ser-16 site) and Ca
2+
-calmodulin protein kinase (Thr-17 site) phosphorylation of phospholamban. PP1 activity at sarcoplasmic reticulum is controlled by inhibitor-1 (I-1), which blocks PP1 in its PKA-phosphorylated form only. In cAF, the ratio of Thr-35–phosphorylated to total I-1 was 10-fold higher, which suggests that the enhanced phosphorylation of phospholamban may result from a stronger PP1 inhibition by PKA-hyperphosphorylated (activated) I-1.
Conclusions—
Altered Ca
2+
handling in cAF is associated with impaired phosphorylation of myosin binding protein-C, which may contribute to the contractile dysfunction after cardioversion. The hyperphosphorylation of phospholamban probably results from enhanced inhibition of sarcoplasmic PP1 by hyperphosphorylated I-1 and may reinforce the leakiness of ryanodine channels in cAF. Restoration of sarcoplasmic reticulum–associated PP1 function may represent a new therapeutic option for treatment of atrial fibrillation.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Center Hamburg-Eppendorf, Germany
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75
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Sahin B, Shu H, Fernandez J, El-Armouche A, Molkentin JD, Nairn AC, Bibb JA. Phosphorylation of protein phosphatase inhibitor-1 by protein kinase C. J Biol Chem 2006; 281:24322-35. [PMID: 16772299 PMCID: PMC4353479 DOI: 10.1074/jbc.m603282200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr(35). Moreover, Ser(67) of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser(67) inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser(65) in vitro. In contrast, Ser(67) phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser(65). Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser(65) and Ser(67), but not Ser(65) alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser(65) inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser(67) protects phospho-Ser(65) inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser(65)/Ser(67) inhibitor-1 in this tissue. In contrast, the activation of N-methyl-d-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser(65)/Ser(67) inhibitor-1 levels. Phosphomimetic mutation of Ser(65) and/or Ser(67) did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser(65)/Ser(67) inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser(67) and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation.
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Affiliation(s)
- Bogachan Sahin
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Hongjun Shu
- Protein Chemistry Laboratory, Alliance for Cellular Signaling, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Joseph Fernandez
- Protein/DNA Technology Center, Rockefeller University, New York, New York 1 0021
| | - Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology, University Hospital Eppendorf, 20246 Hamburg, Germany
| | - Jeffery D. Molkentin
- Department of Pediatrics, University of Cincinnati, Children’s Hospital Medical Center, Cincinnati, Ohio 45229
| | - Angus C. Nairn
- Laboratory of Cellular and Molecular Neuroscience, Rockefeller University, New York, New York 1 0021
- Yale University School of Medicine, New Haven, Connecticut 06519
| | - James A. Bibb
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
- To whom correspondence should be addressed: Dept. of Psychiatry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9070. Tel.: 214-648-4168; Fax: 214-648-1293;
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76
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El-Armouche A, Bednorz A, Pamminger T, Ditz D, Didié M, Dobrev D, Eschenhagen T. Role of calcineurin and protein phosphatase-2A in the regulation of phosphatase inhibitor-1 in cardiac myocytes. Biochem Biophys Res Commun 2006; 346:700-6. [PMID: 16774736 DOI: 10.1016/j.bbrc.2006.05.182] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 05/22/2006] [Indexed: 10/24/2022]
Abstract
Inhibitor 1 (I-1) is a protein inhibitor of protein phosphatase 1 (PP1), the predominating Ser/Thr phosphatase in the heart. Non-phosphorylated I-1 is inactive, whereas I-1 phosphorylated by protein kinase A (PKA) at Thr35 is a potent PP1 inhibitor. The phosphatases that dephosphorylate I-1Thr35 and thus deactivate I-1 in the heart are not established. Here we overexpressed I-1 in neonatal rat cardiac myocytes with recombinant adenovirus and determined phosphorylation of I-1, and one of the major target proteins of PKA/PP1 in the heart, phospholamban (PLB), by Western blot with phospho-specific antibodies. Incubation with the calcineurin inhibitor cyclosporine A or okadaic acid, used at a concentration preferentially inhibiting phosphatase 2A (PP2A), increased significantly I-1Thr35 (approximately 2- to 6-fold) and PLB Ser16 phosphorylation (approximately 2-fold). The results indicate that calcineurin and PP2A act to maintain a low basal level of phosphorylated (active) I-1 in living cardiac myocytes. Calcineurin may constitute a cross-talk between calcium- and cAMP-dependent pathways.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology, Medical Center Hamburg-Eppendorf, Hamburg, Germany
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77
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Yamada M, Ikeda Y, Yano M, Yoshimura K, Nishino S, Aoyama H, Wang L, Aoki H, Matsuzaki M. Inhibition of protein phosphatase 1 by inhibitor-2 gene delivery ameliorates heart failure progression in genetic cardiomyopathy. FASEB J 2006; 20:1197-9. [PMID: 16627625 DOI: 10.1096/fj.05-5299fje] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The type 1 protein phosphatase (PP1) has been reported to be overactivated in the failing heart, leading to a depression in cardiac function. We investigated whether in vivo PP1 inhibition by myocardial gene transfer of inhibitor-2 (INH-2), an endogenous PP1 inhibitor, alleviates heart failure (HF) progression in the cardiomyopathic (CM) hamster, a well-established HF model. Adenoviral INH-2 gene delivery improved % fractional shortening of the left ventricle (LV) accompanied by reduced chamber size at 1 wk. In vivo myocardial INH-2 gene delivery induced an increase in cytosolic PP1 catalytic subunit alpha (PP1Calpha) without inducing the corresponding increase in cytosolic PP1 activity. On the other hand, INH-2 delivery induced a decrease in microsomal PP1Calpha, resulting in a preferential decrease in microsomal PP1 activity, thereby increasing in phospholamban phosphorylation at Ser16. INH-2 gene transfer alleviated brain natriuretic peptide expression, presumably reflecting improved cardiac function. Moreover, adeno-associated virus-mediated INH-2 gene delivery significantly extended the survival time for 3 mo. These results indicate that increased PP1 activity is an exacerbating factor during progression of genetic cardiomyopathy and modulation of PP1 activity by INH-2 provides a potential new treatment for HF without activating protein kinase A signaling in cardiomyocytes.
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Affiliation(s)
- Michio Yamada
- Department of Molecular Cardiovascular Biology, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi, Ube 755-8505, Japan
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78
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Mühlhäuser U, Zolk O, Rau T, Münzel F, Wieland T, Eschenhagen T. Atorvastatin desensitizes beta-adrenergic signaling in cardiac myocytes via reduced isoprenylation of G-protein gamma-subunits. FASEB J 2006; 20:785-7. [PMID: 16467371 DOI: 10.1096/fj.05-5067fje] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Statins exert pleiotropic, cholesterol-independent effects by reducing isoprenylation of monomeric GTPases. Here we examined whether statins also reduce isoprenylation of gamma-subunits of heterotrimeric G-proteins and thereby affect beta-adrenergic signaling and regulation of force in cardiac myocytes. Neonatal rat cardiac myocytes (NRCM) were treated with atorvastatin (0.1-10 micromol/l; 12-48 h) and examined for adenylyl cyclase regulating G-protein alpha- (Galpha), beta- (Gbeta), and gamma- (Ggamma) subunits and cAMP accumulation. Engineered heart tissue (EHT) from NRCM was used to evaluate contractile consequences. In atorvastatin-treated NRCM, a second band of Ggamma3 with a lower apparent molecular weight appeared in cytosol and particulate fractions that was absent in vehicle-treated NRCM, but also seen after GGTI-298, a geranylgeranyl transferase inhibitor. In parallel, Gbeta accumulated in the cytosol and total cellular content of Galphas was reduced. In atorvastatin-treated NRCM, the cAMP-increasing effect of isoprenaline was reduced. Likewise, the positive inotropic effect of isoprenaline was desensitized and reduced after treatment with atorvastatin. The effects of atorvastatin were abolished by mevalonate and/or geranylgeranyl pyrophosphate, but not by farnesyl pyrophosphate or squalene. Taken together, the results of this study show that atorvastatin desensitizes NRCM to beta-adrenergic stimulation by a mechanism that involves reduced isoprenylation of Ggamma and subsequent reductions in the cellular content of Galphas.
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Affiliation(s)
- Ulrike Mühlhäuser
- Institute of Experimental and Clinical Pharmacology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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79
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Feldman DS, Carnes CA, Abraham WT, Bristow MR. Mechanisms of disease: beta-adrenergic receptors--alterations in signal transduction and pharmacogenomics in heart failure. ACTA ACUST UNITED AC 2005; 2:475-83. [PMID: 16265588 DOI: 10.1038/ncpcardio0309] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 06/23/2005] [Indexed: 01/08/2023]
Abstract
Beta-adrenergic signaling is an important regulator of myocardial function. During the progression of heart failure (HF), a reproducible series of biochemical events occurs that affects beta-adrenergic receptor (beta-AR) signaling and cardiac function. Furthermore, there are pathophysiologic alterations in the expression and regulation of proteins that are regulated by beta-ARs during HF. Analyses of these complex signaling pathways have led to a better understanding of HF mechanisms and the use of beta-adrenergic antagonists, which have notably altered HF-related morbidity and mortality. Despite therapeutic advances that have affected beta-AR signaling, HF remains a leading cause of hospitalization and a principal cause of death in industrialized nations. In this review, we summarize current insights into beta-adrenergic signal-transduction pathways, the best-described beta-AR polymorphisms, and therapies that target the beta-AR pathway in HF.
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Affiliation(s)
- David S Feldman
- Davis Heart and Lung Research Institute, Division of Cardiology/Medicine, Ohio State University, Columbus, OH 43210, USA.
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80
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Gupta RC, Mishra S, Yang XP, Sabbah HN. Reduced inhibitor 1 and 2 activity is associated with increased protein phosphatase type 1 activity in left ventricular myocardium of one-kidney, one-clip hypertensive rats. Mol Cell Biochem 2005; 269:49-57. [PMID: 15786716 DOI: 10.1007/s11010-005-2538-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED In failing hearts, although protein phosphatase type 1 (PP1) activity has increased, information about the regulation and status of PP1 inhibitor-1 (INH-1) and inhibitor-2 (INH-2) is limited. In this study, we examined activity and protein expression of PP1, INH-1 and INH-2 and phosphorylation of sarcoplasmic reticulum (SR) phospholamban (PLB), a substrate of PP1 and modulator of SR Ca2+-ATPase activity, in failing and non-failing hearts. These studies were performed in LV myocardium of seven rats with chronic renal hypertension produced by Goldblatt's one-kidney, one-clip procedure and seven age-matched sham-operated normal controls (CTR). Eight weeks after surgery, LV ejection fraction, LV hypertrophy, and pulmonary congestion were determined in all rats. PP1 activity (nmol 32P/min/mg non-collagen protein) was assessed in LV homogenates using 32P-labeled phosphorylase a as substrate. INH-1 and INH-2 activity was determined in the immunoprecipitate of LV homogenates and expressed as percentage inhibitory activity. Using a specific antibody, LV tissue levels of PP1C and calsequestrin (CSQ), a SR calcium binding protein, which is not altered in failing hearts, were also determined. Further, total and phosphorylated PLB, INH-1 and INH-2 protein levels were determined in the LV homogenate and phosphoprotein-enriched fraction, respectively. The band density of each protein was quantified in densitometric units and normalized to CSQ. RESULTS rats with chronic renal hypertension exhibited significantly reduced LV ejection fraction and increased LV hypertrophy and pulmonary congestion, characteristics of chronic heart failure (CHF). We found that compared to CTR, (1) both INH-1 (10.2+/-2 versus 57.5+/-1; p < 0.05) and INH-2 activity (3.8+/-0.4 versus 36.2+/-4; p < 0.05) were reduced, (2) total and phosphorylated PLB amount reduced, (3) protein level of phosphorylated INH-1 was reduced (2.32+/-0.1 versus 0.73+/-0.04; p < 0.05) whereas that of phosphorylated INH-2 increased (3.05+/-0.3 versus 1.42+/-0.1; p < 0.05), and (4) PP1 activity was increased approximately 2.6-fold in rats with CHF (1.59+/-0.05 versus 0.61+/-0.01; p < 0.05) while protein level of the catalytic subunit of PP1 (PP1C) increased 3.85-fold (0.77+/-0.05 versus 0.20+/-0.02; p < 0.05). These results suggest that reduced inhibitory INH-1 and INH-2 activity, increased PP1C protein level, and reduced PLB phosphorylation are associated with increased PP1 activity in failing hearts.
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Affiliation(s)
- Ramesh C Gupta
- Cardiovascular Medicine, Department of Medicine, Henry Ford Heart and Vascular Institute, Henry Ford Health System, Detroit, MI 48202, USA.
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81
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82
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Rajashree R, Blunt BC, Hofmann PA. Modulation of myosin phosphatase targeting subunit and protein phosphatase 1 in the heart. Am J Physiol Heart Circ Physiol 2005; 289:H1736-43. [PMID: 15908465 DOI: 10.1152/ajpheart.00318.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myosin light chain 2 (LC2) phosphorylation is of both physiological and pathological importance to myocardial function. The phosphatase that directly dephosphorylates LC2 is a type 1 protein phosphatase (PP1) that contains a catalytic subunit that complexes with a myosin-binding phosphatase targeting subunit (MYPT). The goal of the present study was to examine the role of MYPT in the regulation of PP1 in ventricular myocytes. In the first part of the study, regional distribution of MYPT expression and phosphorylation were determined in unstimulated hearts. The pattern of MYPT phosphorylation was inversely related to the LC2 phosphorylation spatial gradient as described by Epstein and colleagues (Davis JS, Hassanzadeh S, Winitsky S, Lin H, Satorius C, Vemuri R, Aletras AH, Wen H, and Epstein ND. Cell 107: 631-641, 2001). In the second part of the study, adult rat isolated ventricular myocytes were exposed to an alpha-adrenergic receptor agonist, and properties of MYPT, PP1, and LC2 were studied. We found MYPT associates with cardiac myofilaments, and this association increases upon alpha-adrenergic receptor stimulation. Activation of alpha-adrenergic receptors also led to a decrease in the PP1-myofilament association. Furthermore, alpha-adrenergic receptor stimulation results in phosphorylation of MYPT and LC2 and an increase in myocyte Ca(2+) sensitivity of tension that all depend on Rho kinase activation. These data support the hypothesis that alpha-adrenergic receptor activation works through Rho kinase to phosphorylate MYPT, and phosphorylated MYPT dissociates from PP1 so that PP1 is no longer physically associated with LC2. Hence, we propose a pathway for the dynamic modulation of LC2 phosphorylation through receptor-dependent phosphorylation of MYPT, and a spatial gradient of LC2 phosphorylation under basal conditions that occurs due to varied levels of phosphorylation of MYPT in ventricles.
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Affiliation(s)
- Ravi Rajashree
- Department of Physiology, University of Tennessee School of Medicine, 894 Union Ave., Memphis, Tennessee 38163, USA
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83
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Pathak A, del Monte F, Zhao W, Schultz JE, Lorenz JN, Bodi I, Weiser D, Hahn H, Carr AN, Syed F, Mavila N, Jha L, Qian J, Marreez Y, Chen G, McGraw DW, Heist EK, Guerrero JL, DePaoli-Roach AA, Hajjar RJ, Kranias EG. Enhancement of Cardiac Function and Suppression of Heart Failure Progression By Inhibition of Protein Phosphatase 1. Circ Res 2005; 96:756-66. [PMID: 15746443 DOI: 10.1161/01.res.0000161256.85833.fa] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abnormal calcium cycling, characteristic of experimental and human heart failure, is associated with impaired sarcoplasmic reticulum calcium uptake activity. This reflects decreases in the cAMP-pathway signaling and increases in type 1 phosphatase activity. The increased protein phosphatase 1 activity is partially due to dephosphorylation and inactivation of its inhibitor-1, promoting dephosphorylation of phospholamban and inhibition of the sarcoplasmic reticulum calcium-pump. Indeed, cardiac-specific expression of a constitutively active inhibitor-1 results in selective enhancement of phospholamban phosphorylation and augmented cardiac contractility at the cellular and intact animal levels. Furthermore, the beta-adrenergic response is enhanced in the transgenic hearts compared with wild types. On aortic constriction, the hypercontractile cardiac function is maintained, hypertrophy is attenuated and there is no decompensation in the transgenics compared with wild-type controls. Notably, acute adenoviral gene delivery of the active inhibitor-1, completely restores function and partially reverses remodeling, including normalization of the hyperactivated p38, in the setting of pre-existing heart failure. Thus, the inhibitor 1 of the type 1 phosphatase may represent an attractive new therapeutic target.
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Affiliation(s)
- Anand Pathak
- Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine, Cincinnati, OH 45267-0575, USA
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84
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Liu QR, Gong JP, Uhl GR. Families of Protein Phosphatase 1 Modulators Activated by Protein Kinases A and C: Focus on Brain. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2005; 79:371-404. [PMID: 16096033 DOI: 10.1016/s0079-6603(04)79008-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Qing-Rong Liu
- Molecular Neurobiology Branch, NIDA-IRP, National Institute of Health, Baltimore, Maryland 21224, USA
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85
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El-Armouche A, Jaeckel E, Boheler KR, Boknik P, Hertle B, Neumann J, Eschenhagen T. Ouabain treatment is associated with upregulation of phosphatase inhibitor-1 and Na+/Ca2+-exchanger and β-adrenergic sensitization in rat hearts. Biochem Biophys Res Commun 2004; 318:219-26. [PMID: 15110776 DOI: 10.1016/j.bbrc.2004.04.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Indexed: 11/29/2022]
Abstract
Cardiac glycosides are widely used in the treatment of congestive heart failure. While the mechanism of the positive inotropic effect after acute application of cardiac glycosides is explained by blockade of the Na+/K+-pump, little is known about consequences of a prolonged therapy. Here male Wistar rats were treated for 4 days with continuous infusions of ouabain (6.5 mg/kg/day) or 0.9% NaCl (control) via osmotic minipumps. Electrically driven (1 Hz, 35 degrees C) papillary muscles from ouabain-treated rats exhibited shorter relaxation time (-15%) and a twofold increase in the sensitivity for the positive inotropic effect of isoprenaline. The density and affinity of beta1- and beta2-adrenoceptors as well as mRNA and protein levels of stimulatory (G(s)alpha) and inhibitory (G(i)alpha-2, G(i)alpha-3) G-proteins were unaffected by ouabain. Similarly, SR-Ca2+-ATPase 2A, phospholamban, ryanodine-receptor expression as well as the oxalate-stimulated 45Ca-uptake of membrane vesicles remained unchanged. However, mRNA abundance of the protein phosphatase inhibitor-1 (I-1) and the Na+/Ca2+-exchanger (NCX) were increased by 52% and 26%, respectively. I-1 plays an amplifier role in cardiac signaling. Downregulation of I-1 in human heart failure is associated with desensitization of the beta-adrenergic signaling pathway. The present data suggest that the ouabain-induced increase in I-1 expression might be at least partly responsible for the increased isoprenaline sensitivity and increased expression of NCX for the accelerated relaxation after chronic ouabain in this model.
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Affiliation(s)
- Ali El-Armouche
- Institute of Experimental and Clinical Pharmacology, University Hospital Eppendorf, Hamburg, Germany
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86
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Braz JC, Gregory K, Pathak A, Zhao W, Sahin B, Klevitsky R, Kimball TF, Lorenz JN, Nairn AC, Liggett SB, Bodi I, Wang S, Schwartz A, Lakatta EG, DePaoli-Roach AA, Robbins J, Hewett TE, Bibb JA, Westfall MV, Kranias EG, Molkentin JD. PKC-alpha regulates cardiac contractility and propensity toward heart failure. Nat Med 2004; 10:248-54. [PMID: 14966518 DOI: 10.1038/nm1000] [Citation(s) in RCA: 448] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Accepted: 01/26/2004] [Indexed: 11/09/2022]
Abstract
The protein kinase C (PKC) family of serine/threonine kinases functions downstream of nearly all membrane-associated signal transduction pathways. Here we identify PKC-alpha as a fundamental regulator of cardiac contractility and Ca(2+) handling in myocytes. Hearts of Prkca-deficient mice are hypercontractile, whereas those of transgenic mice overexpressing Prkca are hypocontractile. Adenoviral gene transfer of dominant-negative or wild-type PKC-alpha into cardiac myocytes enhances or reduces contractility, respectively. Mechanistically, modulation of PKC-alpha activity affects dephosphorylation of the sarcoplasmic reticulum Ca(2+) ATPase-2 (SERCA-2) pump inhibitory protein phospholamban (PLB), and alters sarcoplasmic reticulum Ca(2+) loading and the Ca(2+) transient. PKC-alpha directly phosphorylates protein phosphatase inhibitor-1 (I-1), altering the activity of protein phosphatase-1 (PP-1), which may account for the effects of PKC-alpha on PLB phosphorylation. Hypercontractility caused by Prkca deletion protects against heart failure induced by pressure overload, and against dilated cardiomyopathy induced by deleting the gene encoding muscle LIM protein (Csrp3). Deletion of Prkca also rescues cardiomyopathy associated with overexpression of PP-1. Thus, PKC-alpha functions as a nodal integrator of cardiac contractility by sensing intracellular Ca(2+) and signal transduction events, which can profoundly affect propensity toward heart failure.
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Affiliation(s)
- Julian C Braz
- Department of Pediatrics, University of Cincinnati, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA
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87
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Gupta RC, Mishra S, Rastogi S, Imai M, Habib O, Sabbah HN. Cardiac SR-coupled PP1 activity and expression are increased and inhibitor 1 protein expression is decreased in failing hearts. Am J Physiol Heart Circ Physiol 2003; 285:H2373-81. [PMID: 14613911 DOI: 10.1152/ajpheart.00442.2003] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type 1 protein phosphatase (PP1) is a negative regulator of cardiac function. However, studies on the status and regulation of sarcoplasmic reticulum (SR)-associated PP1 activity in failing hearts are limited. We studied PP1 activity and protein and mRNA expression of the catalytic subunit of PP1 (PP1C) and protein levels of PP1-specific inhibitors [inhibitor 1 (Inh-1) and inhibitor 2 (Inh-2)] in the left ventricular (LV) myocardium of 6 dogs with heart failure (HF; LV ejection fraction, 23 +/- 2%) and 6 normal dogs. In failing LV tissue, PP1 activity values (expressed as pmol 32P. min-1. mg of noncollagen protein-1) in the homogenate, crude membranes, cytosol, and purified SR were increased by 52, 54, 55, and 72%, respectively. Trypsin treatment released PP1 but not type 2A protein phosphatase from the SR. In the supernatant of trypsin-treated SR, PP1 activity was approximately 24% higher in failing hearts than in normal control hearts. A similar increase in protein expression of PP1C was observed in the nontrypsinized SR. Heat-denatured phosphorylated SR inhibited PP1 activity by 30%, which suggests the presence of Inh-1 or -2 or both in the SR. With the use of a specific antibody, both Inh-1 and -2 proteins were found in the SR; the former was decreased by 56% in the failing SR, whereas the latter did not change. These results suggest that protein phosphatase activity bound to the SR is increased and is predominantly type 1. Increased SR-associated PP1 activity in failing hearts appears to be due partly to increased expression of PP1C and partly to reduced levels of Inh-1 but not Inh-2 protein. Thus inhibition of PP1 activity in the SR appears to be a potential therapeutic target for improving LV function in failing hearts, because it may lead to increased SR Ca2+ uptake, which is impaired in failing hearts.
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Affiliation(s)
- Ramesh C Gupta
- Division of Cardiovascular Medicine, Department of Medicine, Henry Ford Heart and Vascular Institute, Detroit, MI 48202, USA.
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88
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Abstract
This review addresses open questions about the role of beta-adrenergic receptors in cardiac function and failure. Cardiomyocytes express all three beta-adrenergic receptor subtypes-beta1, beta2, and, at least in some species, beta3. The beta1 subtype is the most prominent one and is mainly responsible for positive chronotropic and inotropic effects of catecholamines. The beta2 subtype also increases cardiac function, but its ability to activate nonclassical signaling pathways suggests a function distinct from the beta1 subtype. In heart failure, the sympathetic system is activated, cardiac beta-receptor number and function are decreased, and downstream mechanisms are altered. However, in spite of a wealth of data, we still do not know whether and to what extent these alterations are adaptive/protective or detrimental, or both. Clinically, beta-adrenergic antagonists represent the most important advance in heart failure therapy, but it is still debated whether they act by blocking or by resensitizing the beta-adrenergic receptor system. Newer experimental therapeutic strategies aim at the receptor desensitization machinery and at downstream signaling steps.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology, Versbacher Strasse 9, 97078 Wuerzburg, Germany.
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