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Martin TG, Hunt DR, Langer SJ, Tan Y, Ebmeier CC, Crocini C, Chung E, Leinwand LA. A Conserved Mechanism of Cardiac Hypertrophy Regression through FoxO1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.27.577585. [PMID: 38328143 PMCID: PMC10849654 DOI: 10.1101/2024.01.27.577585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
The heart is a highly plastic organ that responds to diverse stimuli to modify form and function. The molecular mechanisms of adaptive physiological cardiac hypertrophy are well-established; however, the regulation of hypertrophy regression is poorly understood. To identify molecular features of regression, we studied Burmese pythons which experience reversible cardiac hypertrophy following large, infrequent meals. Using multi-omics screens followed by targeted analyses, we found forkhead box protein O1 (FoxO1) transcription factor signaling, and downstream autophagy activity, were downregulated during hypertrophy, but re-activated with regression. To determine whether these events were mechanistically related to regression, we established an in vitro platform of cardiomyocyte hypertrophy and regression from treatment with fed python plasma. FoxO1 inhibition prevented regression in this system, while FoxO1 activation reversed fed python plasma-induced hypertrophy in an autophagy-dependent manner. We next examined whether FoxO1 was implicated in mammalian models of reversible hypertrophy from exercise and pregnancy and found that in both cases FoxO1 was activated during regression. In these models, as in pythons, activation of FoxO1 was associated with increased expression FoxO1 target genes involved in autophagy. Taken together, our findings suggest FoxO1-dependent autophagy is a conserved mechanism for regression of physiological cardiac hypertrophy across species.
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Affiliation(s)
- Thomas G. Martin
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Dakota R. Hunt
- Department of Biochemistry, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Stephen J. Langer
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Yuxiao Tan
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Christopher C. Ebmeier
- Department of Biochemistry, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Claudia Crocini
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
| | - Eunhee Chung
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
- Department of Kinesiology, University of Texas at San Antonio, San Antonio, TX
| | - Leslie A. Leinwand
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder CO
- BioFrontiers Institute, University of Colorado Boulder, Boulder CO
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Ördög B, Teplenin A, De Coster T, Bart CI, Dekker SO, Zhang J, Ypey DL, de Vries AAF, Pijnappels DA. The Effects of Repetitive Use and Pathological Remodeling on Channelrhodopsin Function in Cardiomyocytes. Front Physiol 2021; 12:710020. [PMID: 34539432 PMCID: PMC8448166 DOI: 10.3389/fphys.2021.710020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Aim: Channelrhodopsins (ChRs) are a large family of light-gated ion channels with distinct properties, which is of great importance in the selection of a ChR variant for a given application. However, data to guide such selection for cardiac optogenetic applications are lacking. Therefore, we investigated the functioning of different ChR variants in normal and pathological hypertrophic cardiomyocytes subjected to various illumination protocols. Methods and Results: Isolated neonatal rat ventricular cardiomyocytes (NRVMs) were transduced with lentiviral vectors to express one of the following ChR variants: H134R, CatCh, ReaChR, or GtACR1. NRVMs were treated with phenylephrine (PE) to induce pathological hypertrophy (PE group) or left untreated [control (CTL) group]. In these groups, ChR currents displayed unique and significantly different properties for each ChR variant on activation by a single 1-s light pulse (1 mW/mm2: 470, 565, or 617 nm). The concomitant membrane potential (Vm) responses also showed a ChR variant-specific profile, with GtACR1 causing a slight increase in average Vm during illumination (Vplateau: −38 mV) as compared with a Vplateau > −20 mV for the other ChR variants. On repetitive activation at increasing frequencies (10-ms pulses at 1–10 Hz for 30 s), peak currents, which are important for cardiac pacing, decreased with increasing activation frequencies by 17–78% (p < 0.05), while plateau currents, which are critical for arrhythmia termination, decreased by 10–75% (p < 0.05), both in a variant-specific manner. In contrast, the corresponding Vplateau remained largely stable. Importantly, current properties and Vm responses were not statistically different between the PE and CTL groups, irrespective of the variant used (p > 0.05). Conclusion: Our data show that ChR variants function equally well in cell culture models of healthy and pathologically hypertrophic myocardium but show strong, variant-specific use-dependence. This use-dependent nature of ChR function should be taken into account during the design of cardiac optogenetic studies and the interpretation of the experimental findings thereof.
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Affiliation(s)
- Balázs Ördög
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Alexander Teplenin
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Tim De Coster
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Cindy I Bart
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Sven O Dekker
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Juan Zhang
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Dirk L Ypey
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, Leiden, Netherlands
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Curtis MW, Budyn E, Desai TA, Samarel AM, Russell B. Microdomain heterogeneity in 3D affects the mechanics of neonatal cardiac myocyte contraction. Biomech Model Mechanobiol 2013; 12:95-109. [PMID: 22407215 PMCID: PMC3407350 DOI: 10.1007/s10237-012-0384-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 02/23/2012] [Indexed: 01/26/2023]
Abstract
Cardiac muscle cells are known to adapt to their physical surroundings, optimizing intracellular organization and contractile function for a given culture environment. A previously developed in vitro model system has shown that the inclusion of discrete microscale domains (or microrods) in three dimensions (3D) can alter long-term growth responses of neonatal ventricular myocytes. The aim of this work was to understand how cellular contact with such a domain affects various mechanical changes involved in cardiac muscle cell remodeling. Myocytes were maintained in 3D gels over 5 days in the presence or absence of 100-μm-long microrods, and the effect of this local heterogeneity on cell behavior was analyzed via several imaging techniques. Microrod abutment resulted in approximately twofold increases in the maximum displacement of spontaneously beating myocytes, as based on confocal microscopy scans of the gel xy-plane or the myocyte long axis. In addition, microrods caused significant increases in the proportion of aligned myofibrils (≤20° deviation from long axis) in fixed myocytes. Microrod-related differences in axial contraction could be abrogated by long-term interruption of certain signals of the RhoA-/Rho-associated kinase (ROCK) or protein kinase C (PKC) pathway. Furthermore, microrod-induced increases in myocyte size and protein content were prevented by ROCK inhibition. In all, the data suggest that microdomain heterogeneity in 3D appears to promote the development of axially aligned contractile machinery in muscle cells, an observation that may have relevance to a number of cardiac tissue engineering interventions.
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Affiliation(s)
- Matthew W. Curtis
- Department of Physiology and Biophysics, University of Illinois at Chicago, 835 South Wolcott Avenue, Chicago, IL 60612, USA
| | - Elisa Budyn
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Tejal A. Desai
- Department of Physiology and Division of Bioengineering, University of California at San Francisco, San Francisco, CA, USA
| | - Allen M. Samarel
- The Cardiovascular Institute, Loyola University Medical Center, Maywood, IL, USA
| | - Brenda Russell
- Department of Physiology and Biophysics, University of Illinois at Chicago, 835 South Wolcott Avenue, Chicago, IL 60612, USA,
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Bai Y, Morgan EE, Giovannucci DR, Pierre SV, Philipson KD, Askari A, Liu L. Different roles of the cardiac Na+/Ca2+-exchanger in ouabain-induced inotropy, cell signaling, and hypertrophy. Am J Physiol Heart Circ Physiol 2012. [PMID: 23203972 DOI: 10.1152/ajpheart.00462.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have shown that digitalis drugs, acting as specific inhibitors of cardiac Na(+)/K(+)-ATPase, not only cause positive inotropic effects, but also activate cell signaling pathways that lead to cardiac myocyte hypertrophy. A major aim of this work was to assess the role of Na(+)/Ca(2+)-exchanger, NCX1, in the above two seemingly related drug effects. Using a mouse with ventricular-specific knockout (KO) of NCX1, ouabain-induced positive inotropy that was evident in isolated wild-type (Wt) hearts was clearly reduced in KO hearts. Ouabain also increased Ca(2+) transient amplitudes in Wt myocytes, but not in KO myocytes. Ouabain-induced activations of ERK 1/2 were noted in Wt myocytes, but not in KO myocytes; however, ouabain activated PI3K1A and Akt in both Wt and KO myocytes. Protein synthesis rate, as a measure of hypertrophy, was increased by ouabain in Wt and KO myocytes; these drug effects were prevented by a PI3K inhibitor but not by a MEK/ERK inhibitor. Hypertrophy caused by ET-1, but not that induced by ouabain, was accompanied by upregulation of BNP gene in Wt and KO myocytes. The findings indicate 1) the necessity of NCX1 for positive inotropic action of ouabain; 2) the irrelevance of NCX1 and ERK 1/2 activation to ouabain-induced hypertrophy; and 3) that hypertrophy caused by ouabain through the activation of PI3K1A/Akt pathway is likely to be beneficial to the heart.
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Affiliation(s)
- Yan Bai
- Department of Biochemistry and Cancer Biology, College of Medicine and Life Sciences, Univ. of Toledo, 3000 Arlington Ave., MS 1010, Toledo, Ohio 43614, USA
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Contractile Activity Regulates Inducible Nitric Oxide Synthase Expression and NO(i) Production in Cardiomyocytes via a FAK-Dependent Signaling Pathway. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:473410. [PMID: 22900166 PMCID: PMC3412095 DOI: 10.1155/2012/473410] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/06/2012] [Accepted: 06/06/2012] [Indexed: 11/18/2022]
Abstract
Intracellular nitric oxide (NOi) is a physiological regulator of excitation-contraction coupling, but is also involved in the development of cardiac dysfunction during hypertrophy and heart failure. To determine whether contractile activity regulates nitric oxide synthase (NOS) expression, spontaneously contracting, neonatal rat ventricular myocytes (NRVM) were treat with L-type calcium channel blockers (nifedipine and verapamil) or myosin II ATPase inhibitors (butanedione monoxime (BDM) and blebbistatin) to produce contractile arrest. Both types of inhibitors significantly reduced iNOS but not eNOS expression, and also reduced NOi production. Inhibiting contractile activity also reduced focal adhesion kinase (FAK) and AKT phosphorylation. Contraction-induced iNOS expression required FAK and phosphatidylinositol 3-kinase (PI(3)K), as both PF573228 and LY294002 (10 μM, 24 h) eliminated contraction-induced iNOS expression. Similarly, shRNAs specific for FAK (shFAK) caused FAK knockdown, reduced AKT phosphorylation at T308 and S473, and reduced iNOS expression. In contrast, shRNA-mediated knockdown of PYK2, the other member of the FAK-family of protein tyrosine kinases, had much less of an effect. Conversely, overexpression of a constitutively active form of FAK (CD2-FAK) or AKT (Myr-AKT) reversed the inhibitory effect of BDM on iNOS expression and NOi production. Thus, contraction-induced iNOS expression and NOi production in NRVM are mediated via a FAK-PI(3)K-AKT signaling pathway.
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Abstract
Adrenoceptors and dopamine receptors are grouped together under the name 'catecholamine receptors.' Catecholamines and catecholaminergic drugs act on catecholamine receptors located on or near the cardiovascular system. The physiological effects of catecholamine receptor stimulation are only partly understood. The catecholaminergic drugs used in critical care medicine today are not selective, or are, at best, in part selective for the various catecholamine receptor subtypes. Many patients, however, depend on them. A variety of animal models has been developed to unravel catecholamine distribution and function. However, the identification of species heterogeneity makes it imperative to determine catecholamine receptor distribution and function in humans. In addition, age-related alterations in catecholamine receptor distribution and function have been identified in human adults. This might have implications for our understanding of the effect of catecholamines in pediatric patients. This article will focus on the pediatric population and will review currently available in vitro data on the distribution and the function of catecholamine receptors in the cardiovascular system of fetuses and children. Also discussed are relevant young animal models and in vivo hemodynamic effects of cardiotonic drugs acting on the catecholamine receptor in children requiring major cardiac surgery. A better understanding of these topics might provide clues for new, receptor subtype-selective, therapeutic approaches in newborns and children with cardiac disease.
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7
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Micromechanical regulation in cardiac myocytes and fibroblasts: implications for tissue remodeling. Pflugers Arch 2011; 462:105-17. [PMID: 21308471 DOI: 10.1007/s00424-011-0931-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 01/25/2011] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
Abstract
Cells of the myocardium are at home in one of the most mechanically dynamic environments in the body. At the cellular level, pulsatile stimuli of chamber filling and emptying are experienced as cyclic strains (relative deformation) and stresses (force per unit area). The intrinsic characteristics of tension-generating myocytes and fibroblasts thus have a continuous mechanical interplay with their extrinsic surroundings. This review explores the ways that the micromechanics at the scale of single cardiac myocytes and fibroblasts have been measured, modeled, and recapitulated in vitro in the context of adaptation. Both types of cardiac cells respond to externally applied strain, and many of the intracellular mechanosensing pathways have been identified with the careful manipulation of experimental variables. In addition to strain, the extent of loading in myocytes and fibroblasts is also regulated by cues from the microenvironment such as substrate surface chemistry, stiffness, and topography. Combinations of these structural cues in three dimensions are needed to mimic the micromechanical complexity derived from the extracellular matrix of the developing, healthy, or pathophysiologic heart. An understanding of cardiac cell micromechanics can therefore inform the design and composition of tissue engineering scaffolds or stem cell niches for future applications in regenerative medicine.
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8
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Curtis MW, Sharma S, Desai TA, Russell B. Hypertrophy, gene expression, and beating of neonatal cardiac myocytes are affected by microdomain heterogeneity in 3D. Biomed Microdevices 2011; 12:1073-85. [PMID: 20668947 DOI: 10.1007/s10544-010-9461-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cardiac myocytes are known to be influenced by the rigidity and topography of their physical microenvironment. It was hypothesized that 3D heterogeneity introduced by purely physical microdomains regulates cardiac myocyte size and contraction. This was tested in vitro using polymeric microstructures (G' = 1.66 GPa) suspended with random orientation in 3D by a soft Matrigel matrix (G' = 22.9 Pa). After 10 days of culture, the presence of 100 μm-long microstructures in 3D gels induced fold increases in neonatal rat ventricular myocyte size (1.61 ± 0.06, p < 0.01) and total protein/cell ratios (1.43 ± 0.08, p < 0.05) that were comparable to those induced chemically by 50 μM phenylephrine treatment. Upon attachment to microstructures, individual myocytes also had larger cross-sectional areas (1.57 ± 0.05, p < 0.01) and higher average rates of spontaneous contraction (2.01 ± 0.08, p < 0.01) than unattached myocytes. Furthermore, the inclusion of microstructures in myocyte-seeded gels caused significant increases in the expression of beta-1 adrenergic receptor (β1-AR, 1.19 ± 0.01), cardiac ankyrin repeat protein (CARP, 1.26 ± 0.02), and sarcoplasmic reticulum calcium-ATPase (SERCA2, 1.59 ± 0.12, p < 0.05), genes implicated in hypertrophy and contractile activity. Together, the results demonstrate that cardiac myocyte behavior can be controlled through local 3D microdomains alone. This approach of defining physical cues as independent features may help to advance the elemental design considerations for scaffolds in cardiac tissue engineering and therapeutic microdevices.
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Affiliation(s)
- Matthew W Curtis
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
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9
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Földes G, Mioulane M, Wright JS, Liu AQ, Novak P, Merkely B, Gorelik J, Schneider MD, Ali NN, Harding SE. Modulation of human embryonic stem cell-derived cardiomyocyte growth: a testbed for studying human cardiac hypertrophy? J Mol Cell Cardiol 2011; 50:367-76. [PMID: 21047517 PMCID: PMC3034871 DOI: 10.1016/j.yjmcc.2010.10.029] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 10/12/2010] [Accepted: 10/26/2010] [Indexed: 11/29/2022]
Abstract
Human embryonic stem cell-derived cardiomyocytes (hESC-CM) are being developed for tissue repair and as a model system for cardiac physiology and pathophysiology. However, the signaling requirements of their growth have not yet been fully characterized. We showed that hESC-CM retain their capacity for increase in size in long-term culture. Exposing hESC-CM to hypertrophic stimuli such as equiaxial cyclic stretch, angiotensin II, and phenylephrine (PE) increased cell size and volume, percentage of hESC-CM with organized sarcomeres, levels of ANF, and cytoskeletal assembly. PE effects on cell size were separable from those on cell cycle. Changes in cell size by PE were completely inhibited by p38-MAPK, calcineurin/FKBP, and mTOR blockers. p38-MAPK and calcineurin were also implicated in basal cell growth. Inhibitors of ERK, JNK, and CaMK II partially reduced PE effects; PKG or GSK3β inhibitors had no effect. The role of p38-MAPK was confirmed by an additional pharmacological inhibitor and adenoviral infection of hESC-CM with a dominant-inhibitory form of p38-MAPK. Infection of hESC-CM with constitutively active upstream MAP2K3b resulted in an increased cell size, sarcomere and cytoskeletal assembly, elongation of the cells, and induction of ANF mRNA levels. siRNA knockdown of p38-MAPK inhibited PE-induced effects on cell size. These results reveal an important role for active protein kinase signaling in hESC-CM growth and hypertrophy, with potential implications for hESC-CM as a novel in vitro test system. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".
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Key Words
- anf, atrial natriuretic factor
- bfgf, basic human fibroblast growth factor
- camk ii, ca2+/calmodulin-dependent kinase ii
- eb, embryoid body
- erk, extracellular signal-regulated kinases
- gsk3, glycogen synthase kinase 3
- hdacii, histone deacetylase
- fkbp, fk506 binding protein
- hesc, human embryonic stem cells
- hesc-cm, human embryonic stem cell-derived cardiomyocytes
- jnk, c-jun n-terminal kinases
- map2k4 and map2k3, mapk kinase 4 and 3, respectively
- mef, mouse embryonic fibroblast
- mhc, myosin heavy chains
- moi, multiplicity of infection
- mtor, mammalian target of rapamycin
- p38–mapk, p38 mitogen-activated protein kinase
- pkg, protein kinase g
- ryr2, cardiac ryanodine receptor 2
- and serca2, sarco/endoplasmic reticulum ca2±-atpase.
- embryonic stem cells
- cardiomyocytes
- human
- protein kinases
- hypertrophy
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Affiliation(s)
- Gábor Földes
- National Heart and Lung Institute, Imperial College London, London, UK.
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Zentilin L, Puligadda U, Lionetti V, Zacchigna S, Collesi C, Pattarini L, Ruozi G, Camporesi S, Sinagra G, Pepe M, Recchia FA, Giacca M. Cardiomyocyte VEGFR-1 activation by VEGF-B induces compensatory hypertrophy and preserves cardiac function after myocardial infarction. FASEB J 2009; 24:1467-78. [PMID: 20019242 DOI: 10.1096/fj.09-143180] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Mounting evidence indicates that the function of members of the vascular endothelial growth factor (VEGF) family extends beyond blood vessel formation. Here, we show that the prolonged intramyocardial expression of VEGF-A(165) and VEGF-B(167) on adeno-associated virus-mediated gene delivery determined a marked improvement in cardiac function after myocardial infarction in rats, by promoting cardiac contractility, preserving viable cardiac tissue, and preventing remodeling of the left ventricle (LV) over time. Consistent with this functional outcome, animals treated with both factors showed diminished fibrosis and increased contractile myocardium, which were more pronounced after expression of the selective VEGF receptor-1 (VEGFR-1) ligand VEGF-B, in the absence of significant induction of angiogenesis. We found that cardiomyocytes expressed VEGFR-1, VEGFR-2, and neuropilin-1 and that, in particular, VEGFR-1 was specifically up-regulated in hypoxia and on exposure to oxidative stress. VEGF-B exerted powerful antiapoptotic effect in both cultured cardiomyocytes and after myocardial infarction in vivo. Finally, VEGFR-1 activation by VEGF-B was found to elicit a peculiar gene expression profile proper of the compensatory, hypertrophic response, consisting in activation of alphaMHC and repression of betaMHC and skeletal alpha-actin, and an increase in SERCA2a, RYR, PGC1alpha, and cardiac natriuretic peptide transcripts, both in cultured cardiomyocytes and in infarcted hearts. The finding that VEGFR-1 activation by VEGF-B prevents loss of cardiac mass and promotes maintenance of cardiac contractility over time has obvious therapeutic implications.
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Affiliation(s)
- Lorena Zentilin
- Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
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Hartman TJ, Martin JL, Solaro RJ, Samarel AM, Russell B. CapZ dynamics are altered by endothelin-1 and phenylephrine via PIP2- and PKC-dependent mechanisms. Am J Physiol Cell Physiol 2009; 296:C1034-9. [PMID: 19295171 DOI: 10.1152/ajpcell.00544.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
One of the unanswered questions in muscle hypertrophy is how new contractile units are inserted into a stable existing cytoskeletal meshwork. Regulation of actin capping by CapZ may play a role in remodeling processes, therefore, CapZ dynamics are determined during rapid growth of cardiac cells in vitro. Neonatal rat ventricular myocytes were infected with adenovirus expressing green fluorescent protein-CapZ beta1 and responded normally to hypertrophic stimuli. CapZ dynamics were analyzed by fluorescence recovery after photobleaching in cultured myocytes treated with endothelin-1 (100 nM) or phenylephrine (10 muM). Recovery by 30 s was greater with endothelin treatment. Analysis 30 min postbleach showed CapZ-infected cells treated with endothelin recovered more completely than controls (77 +/- 9% vs. 50 +/- 6%, P < 0.001). Similar results were found with phenylephrine (77 +/- 5%, P < 0.05). A potential mechanism for phosphatidylinositol bisphosphate (PIP2) mediation of increased CapZ exchange in endothelin- and phenylephrine-treated cells was tested. PIP2 sequestration with neomycin (500 muM) blocked both endothelin- (43 +/- 6%, P < 0.001) and phenylephrine (36 +/- 4%, P < 0.001)-mediated recovery. The protein kinase C inhibitor chelerythrine chloride (10 muM) also blocked endothelin- (53 +/- 10%, P < 0.001) and phenylephrine (42 +/- 3%, P < 0.001)-mediated recovery. This study demonstrates for the first time that endothelin and phenylephrine alter CapZ dynamics through PIP2- and PKC-dependent pathways, which might destabilize the existing framework and permit sarcomeric remodelling to proceed.
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Affiliation(s)
- Thomas J Hartman
- Dept. of Physiology and Biophysics, University of Illinois, Chicago, IL 60612, USA
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12
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Ohba T, Watanabe H, Murakami M, Takahashi Y, Iino K, Kuromitsu S, Mori Y, Ono K, Iijima T, Ito H. Upregulation of TRPC1 in the development of cardiac hypertrophy. J Mol Cell Cardiol 2007; 42:498-507. [PMID: 17174323 DOI: 10.1016/j.yjmcc.2006.10.020] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 10/27/2006] [Accepted: 10/30/2006] [Indexed: 11/25/2022]
Abstract
The importance of Ca(2+) entry in the cardiac hypertrophic response is well documented, but the actual Ca(2+) entry channels remain unknown. Transient receptor potential (TRP) proteins are thought to form either homo- or heteromeric Ca(2+) entry channels that are involved in the proliferation and differentiation of various cells. The purpose of this study was to explore the potential involvement of TRP channels in the development of cardiac hypertrophy. The mRNA and protein expression of several TRP channel subunits were evaluated using hearts from abdominal aortic-banded (AAB) rats. Although TRPs C1, C3, C5, and C6 were constitutively expressed, only TRPC1 expression was significantly increased in the hearts of AAB rats compared to sham-operated rats. Using primary cultures of neonatal rat cardiomyocytes, we detected increases in the expression of TRPC1, brain natriuretic peptide (BNP), and atrial natriuretic factor (ANF), as well as increases in store-operated Ca(2+) entry (SOCE) and cell surface area, following endothelin-1 (ET-1) treatment. Silencing of the TRPC1 gene via small interfering RNA (siRNA) attenuated SOCE and prevented ET-1-, angiotensin-II (AT II)-, and phenylephrine (PE)-induced cardiac hypertrophy. In HEK 293T cells, overexpression of TRPC1 augmented SOCE, leading to an increase in nuclear factor of activated T cells (NFAT) promoter activity, while co-transfection with dominant-negative forms of TRPC1 suppressed it. In conclusion, TRPC1 functions in Ca(2+) influx, and its upregulation is involved in the development of cardiac hypertrophy; moreover, it plays an important role in the regulation of the signaling pathways that govern cardiac hypertrophy. These findings establish TRPC1 as a functionally important regulator of cardiac hypertrophy.
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Affiliation(s)
- Takayoshi Ohba
- Second Department of Internal Medicine, Akita University School of Medicine, Hondoh, Akita, Japan
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Dedkova EN, Wang YG, Ji X, Blatter LA, Samarel AM, Lipsius SL. Signalling mechanisms in contraction-mediated stimulation of intracellular NO production in cat ventricular myocytes. J Physiol 2007; 580:327-45. [PMID: 17234690 PMCID: PMC2075434 DOI: 10.1113/jphysiol.2006.126805] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In this study we sought to determine whether contractile activity has a role as a signalling mechanism in the activation of intracellular nitric oxide (NO(i)) production induced by electrical stimulation of cat ventricular myocytes. Field stimulation (FS) of single ventricular myocytes elicited frequency-dependent increases in NO(i) that were blocked by the calmodulin (CaM) inhibitor 10 microM W-7 and partially inhibited by the phosphatidylinositol 3'-kinase (PI-(3)K) inhibitor 10 microMm LY294002. Increasing extracellular [Ca(2+)] caused a concentration-dependent increase in FS-induced NO(i) that was partially inhibited by LY294002. The negative inotropic agents BDM (5 mm) or blebbistatin (10 microM) decreased cell shortening and NO(i) production without concomitant changes in L-type Ca(2+) current (I(Ca,L)) or [Ca(2+)](i) transients. The positive inotropic agents EMD 57033 or CGP 48506 (1 microM) increased cell shortening and NO(i) production without concomitant changes in I(Ca,L) or [Ca(2+)](i) transients. FS-induced NO(i) production was decreased in myocytes infected (100 multiplicity of viral infection (MOI); 24 h) with a replication-deficient adenovirus expressing a dominant-negative mutant of protein kinase B (Akt) compared with cells infected with a control adenovirus expressing beta-galactosidase. FS-induced NO(i) was partially inhibited by either endothelial (eNOS) or neuronal nitric oxide synthase (nNOS) inhibitors and completely blocked by simultaneous exposure to both. FS-induced [Ca(2+)](i) transients were increased by the nNOS inhibitor nNOS-I (0.24 microM), decreased by the eNOS inhibitor L-NIO (1 microM) and unchanged by exposure to both inhibitors. We conclude that in cat ventricular myocytes, FS-induced NO(i) production requires both Ca(2+)-dependent CaM signalling and Ca(2+)-independent PI-(3)K-Akt signalling activated by contractile activity. FS activates NO(i) production from both eNOS and nNOS, and each source of NO(i) exerts opposing effects on [Ca(2+)](i) transient amplitude. These findings are important for understanding the regulation of NO(i) signalling in the normal and mechanically failing heart.
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Affiliation(s)
- E N Dedkova
- Department of Physiology, Loyola University Medical Center, 2160 S. First Avenue, Maywood, IL 60153, USA
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14
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Ohba T, Watanabe H, Takahashi Y, Suzuki T, Miyoshi I, Nakayama S, Satoh E, Iino K, Sasano H, Mori Y, Kuromitsu S, Imagawa K, Saito Y, Iijima T, Ito H, Murakami M. Regulatory role of neuron-restrictive silencing factor in expression of TRPC1. Biochem Biophys Res Commun 2006; 351:764-70. [PMID: 17084381 DOI: 10.1016/j.bbrc.2006.10.107] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 10/23/2006] [Indexed: 10/23/2022]
Abstract
Neuron-restrictive silencer factor (NRSF) binds its consensus element to repress the transcription of various genes. The dominant-negative form (dnNRSF) has a hypertrophic effect on cardiogenesis through an unidentified mechanism. We examined the involvement of transient receptor potential (TRP) channel proteins, using transgenic mice overexpressing dnNRSF (dnNRSF mice). Electrophoretic mobility-shift assays revealed an interaction between NRSF and a neuron-restrictive silencer element-like sequence in intron 4 of TRPC1 genomic DNA. According to RT-PCR and Western analyses, TRPC1 was up-regulated in dnNRSF mouse heart. Transient overexpression of TRPC1 in HEK 293T cells increased the activity of the nuclear factor in activated T cells (NFAT) promoter and stimulated store-operated Ca(2+) channel (SOCC)-mediated Ca(2+) entry. Transfection of TRPC1 into primary cardiomyocytes increased NFAT activity, indicating a major role for TRPC1 in NFAT activation. Our findings strongly suggest that NRSF regulates TRP1 gene expression and causes changes in the levels of calcium entry through SOCCs.
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Affiliation(s)
- Takayoshi Ohba
- Second Department of Internal Medicine, Akita University School of Medicine, Akita, Japan
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15
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Gusterson RJ, Yuan LW, Latchman DS. Distinct serine residues in CBP and p300 are necessary for their activation by phenylephrine. Int J Biochem Cell Biol 2004; 36:893-9. [PMID: 15006641 DOI: 10.1016/j.biocel.2003.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2003] [Revised: 09/04/2003] [Accepted: 10/06/2003] [Indexed: 12/01/2022]
Abstract
The ability of CREB binding protein (CBP) and p300 co-activators to stimulate transcription has previously been shown to be enhanced by treatment of cardiac cells with the hypertrophic agent phenylephrine (PE). This effect is dependent on activation of the mitogen activated protein kinase pathway (p42/44 MAPK). Here, we demonstrate the first identification of potential phosphorylation sites targeted by PE within the proteins CBP and p300. We show that serine 2015 of CBP and serine 89 of p300 are necessary for PE to stimulate the transcriptional activity of these proteins. Furthermore, we have shown that PE is capable of mediating phosphorylation of endogenous p300 at serine 89. This phosphorylation mediated regulation of CBP and p300 suggests a potential signal transduction pathway for the induction of cardiac cell hypertrophy by PE.
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Affiliation(s)
- Rosalind J Gusterson
- Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK
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16
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Li H, Cook JD, Terry M, Spitzer NC, Ferrari MB. Calcium transients regulate patterned actin assembly during myofibrillogenesis. Dev Dyn 2004; 229:231-42. [PMID: 14745949 DOI: 10.1002/dvdy.10428] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The highly ordered arrangement of sarcomeric myosin during striated muscle development requires spontaneous calcium (Ca(2+)) transients. Here, we show that blocking transients also compromises patterned assembly of actin thin filaments, titin, and capZ. Because a conserved temporal assembly pattern has been described for these proteins, selective inhibitors of either thick or thin filament formation were used to determine their relative temporal interdependencies. For example, inhibition of myosin light chain kinase (MLCK) by application of a specific inhibitory peptide or phorbol myistate acetate (PMA) disrupts myosin assembly without significantly affecting formation of actin bands. The MLCK inhibitor ML-7, however, disrupted actin as well as myosin. Surprisingly, agents that interfere with actin dynamics, such as cytochalasin D, produced only minor organizational disruptions in actin, capZ, and titin staining. However, cytochalasin D and other actin disrupting compounds significantly perturbed myosin organization. The results indicate that (1) Ca(2+) transients regulate one or more of the earliest steps in sarcomere formation, (2) mature actin filaments can assemble independently of myosin band formation, and (3) myosin thick filament assembly is extremely sensitive to disruption of either the actin or titin filament systems.
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Affiliation(s)
- Hongyan Li
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USA
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17
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Wang Q, Moncman CL, Winkelmann DA. Mutations in the motor domain modulate myosin activity and myofibril organization. J Cell Sci 2003; 116:4227-38. [PMID: 12953063 DOI: 10.1242/jcs.00709] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have investigated the functional impact on cardiac myofibril organization and myosin motor activity of point mutations associated with familial hypertrophic cardiomyopathies (FHC). Embryonic chicken cardiomyocytes were transfected with vectors encoding green fluorescent protein (GFP) fused to a striated muscle myosin heavy chain (GFP-myosin). Within 24 hours of transfection, the GFP-myosin is found co-assembled with the endogenous myosin in striated myofibrils. The wild-type GFP-myosin had no effect on the organization of the contractile cytoskeleton of the cardiomyocytes. However, expression of myosin with the R403Q FHC mutation resulted in a small but significant decrease in myofibril organization, and the R453C and G584R mutations caused a more dramatic increase in myofibril disarray. The embryonic cardiomyocytes beat spontaneously in culture and this was not affected by expression of the wild-type or mutant GFP-myosin. For the biochemical analysis of myosin motor activity, replication defective adenovirus was used to express the wild-type and mutant GFP-myosin in C2C12 myotubes. The R403Q mutation enhanced actin filament velocity but had no effect on the myosin duty ratio. The R453C and G584R mutations impaired actin filament movement and both increased the duty ratio. The effects of these mutations on myosin motor activity correlate with changes in myofibril organization of live cardiomyocytes. Thus, mutations associated with hypertrophic cardiomyopathies that alter myosin motor activity can also impair myofibril organization.
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Affiliation(s)
- Qun Wang
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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18
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Kim DJ, Park SH, Lim CS, Chun JS, Kim JK, Song WK. Cellular localization of integrin isoforms in phenylephrine-induced hypertrophic cardiac myocytes. Cell Biochem Funct 2003; 21:41-8. [PMID: 12579520 DOI: 10.1002/cbf.988] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiac hypertrophy is characterized by remodeling of the extracellular matrix (ECM). Integrins are cell-surface molecules that link the ECM to the cellular cytoskeleton where they play roles as signaling molecules and transducers of mechanical force. To clarify the possible roles of integrins in cardiac myocyte hypertrophy, we investigated the cellular localization and expression of ECM proteins and integrins in both normal cardiac myocytes and phenylephrine-induced hypertrophic myocytes. Addition of phenylephrine (PE) to cultured neonatal cardiac myocytes induced sarcomeric organization, increase in cell size, and synthesis of the hypertrophic marker, atrial natriuretic factor (ANF). In particular, fibronectin and collagen underwent dramatic localization changes during PE-induced cardiac hypertrophy. Significant changes were noted in the cellular localization of the respective collagen and fibronectin receptors, integrin alpha1 and alpha5, from diffuse to a sarcomeric banding pattern. Expression levels of integrins were also increased during hypertrophy. Treatment with okadaic acid (OA), an inhibitor of protein phosphatase 2A (PP2A), resulted in inhibition of hypertrophic response. These results suggest that dephosphorylation of integrin beta1 may be important in the induction of cardiac hypertrophy.
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Affiliation(s)
- Dae Joong Kim
- Department of Life Science, Kwangju Institute of Science and Technology, Kwangju 500-712, Korea
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19
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Kerkelä R, Ilves M, Pikkarainen S, Tokola H, Ronkainen J, Vuolteenaho O, Leppäluoto J, Ruskoaho H. Identification of PKCalpha isoform-specific effects in cardiac myocytes using antisense phosphorothioate oligonucleotides. Mol Pharmacol 2002; 62:1482-91. [PMID: 12435817 DOI: 10.1124/mol.62.6.1482] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Members of the mammalian protein kinase C (PKC) superfamily play key regulatory roles in multiple cellular processes. In the heart, PKC signaling is involved in hypertrophic agonist-induced gene expression and hypertrophic growth. To investigate the specific function of PKC signaling in regulating cardiomyocyte growth, we used antisense oligonucleotides to inhibit PKC alpha, the major isozyme present in the neonatal heart. Transfection of cultured neonatal cardiomyocytes with antisense PKCalpha oligonucleotides resulted in a marked reduction in both PKCalpha mRNA and protein levels. PKCalpha antisense treatment also reduced phenylephrine (PE)-induced PKC activity and perinuclear translocation of PKCalpha. Antisense inhibition of PKCalpha led to reduction of PE-induced increase in skeletal alpha-actin mRNA levels and atrial natriuretic peptide (ANP) secretion but had no significant effects on PE-induced beta-myosin heavy chain, ANP, or B-type natriuretic peptide (BNP) gene expression. On the other hand, antisense PKCalpha treatment attenuated endothelin-1-induced increase in ANP and BNP peptide secretion, whereas endothelin-1-induced gene expression of ANP and BNP remained unchanged. The hypertrophic agonist-induced growth of cardiomyocytes, characterized by increased [(3)H]leucine incorporation, was not affected with antisense PKCalpha treatment. Furthermore, we found that PE-induced increase in extracellular signal-regulated kinase (ERK) activity was partially inhibited by antisense PKCalpha treatment, implicating ERK as a downstream mediator for PKCalpha signaling. These results indicate that PKCalpha isozyme is involved in hypertrophic signaling in cardiomyocytes and provide novel strategies for future studies to identify other cellular targets controlled selectively by PKCalpha or other PKC isozymes.
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Affiliation(s)
- Risto Kerkelä
- Department of Pharmacology and Toxicology, Biocenter Oulu, University of Oulu, Finland
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20
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Zobel C, Kassiri Z, Nguyen TTT, Meng Y, Backx PH. Prevention of hypertrophy by overexpression of Kv4.2 in cultured neonatal cardiomyocytes. Circulation 2002; 106:2385-91. [PMID: 12403671 DOI: 10.1161/01.cir.0000033970.22130.93] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Prolonged action potentials (APs) and decreased transient outward K+ currents (I(to)) are consistent findings in hypertrophic myocardium. However, the connection of these changes with cardiac hypertrophy is unknown. The present study investigated the effects of changes in I(to) and the associated alterations in AP on myocyte hypertrophy induced by phenylephrine. METHODS AND RESULTS Chronic incubation of cultured neonatal ventricular rat myocytes (NVRMs) with phenylephrine (PE) reduced I(to) density and prolonged AP duration, leading to a 2-fold increase in the net Ca2+ influx per beat and a 1.4-fold increase in Ca2+-transient amplitude. PE treatment of chronically paced (2-Hz) NVRM also induced increases in cell size, protein/DNA ratio, atrial natriuretic factor mRNA expression, as well as beta/alpha myosin mRNA ratio. These hypertrophic changes were associated with a 2.4-fold increase in activation of nuclear factor of activated T-cells (NFAT), indicating increased activity of the Ca2+-dependent phosphatase calcineurin. Overexpression of Kv4.2 channels using adenovirus prevented the AP duration prolongation as well as the increases in Ca2+ influx and Ca2+-transient amplitude induced by PE. Kv4.2 overexpression also prohibited the PE-induced increases in cell size, protein/DNA ratio, atrial natriuretic factor expression, beta/alpha myosin mRNA ratio, and NFAT activation. CONCLUSIONS Our results demonstrate that PE-mediated hypertrophy in NRVMs seems to require I(to) reductions and AP prolongation associated with increased Ca2+ influx and Ca2+ transients as well as calcineurin activation. The clinical implications of these studies and the possible involvement of other signaling pathways are discussed.
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Affiliation(s)
- Carsten Zobel
- Department of Physiology, Division of Cardiology University Health Network and Heart & Stroke Richard Lewar Centre, University of Toronto, Ontario, Canada
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21
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Abstract
Chronic lengthening of immobilized, neurally intact muscle leads to the addition of sarcomeres in series. Confirmation of a similar adaptation during distraction osteogenesis is crucial for providing a rationale for a successful outcome of the intervention. When distraction osteogenesis (at < or = 1.4 mm/day) is done in skeletally immature animals, muscle adapts by creating a longer and functionally intact muscle. This is achieved through muscle growth, the proliferation of myogenic cells ultimately leading to serial addition of sarcomeres. When distraction osteogenesis is done in skeletally mature animals, however, the same distraction regimen leads to a lengthened muscle that has significant fibrosis and weakness, the latter possibly a result of partial denervation. Despite a modest but significant elevation of local insulinlike growth factor-1 in the lengthened muscles from adult animals, muscle growth is not adequate and leads to a loss of function. In adult animals, the distraction osteogenesis-induced increase in insulinlike growth factor-1 is insufficient to facilitate muscle growth during lengthening. Muscle can be targeted for future therapeutic use of insulinlike growth factor-1; however, such a therapy also may lead to increased fibrosis.
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Affiliation(s)
- Patrick G De Deyne
- Department of Physical Therapy, MSTF Room 434D, School of Medicine, University of Maryland, 10 South Pine Street, Baltimore, MD 21201, USA
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22
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23
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Connor MK, Irrcher I, Hood DA. Contractile activity-induced transcriptional activation of cytochrome C involves Sp1 and is proportional to mitochondrial ATP synthesis in C2C12 muscle cells. J Biol Chem 2001; 276:15898-904. [PMID: 11279044 DOI: 10.1074/jbc.m100272200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Contractile activity induces adaptations in the expression of genes encoding skeletal muscle mitochondrial proteins; however, the putative signals responsible for these adaptations remain unknown. We used electrical stimulation (5 Hz, 65 V) of C2C12 muscle cells in culture to define some of the mechanisms involved in contractile activity-induced changes in cytochrome c gene expression. Chronic contractile activity (4 days, 3 h/day) augmented cytochrome c mRNA by 1.6-fold above control cells. This was likely mediated by increases in transcriptional activation, because cells transfected with full-length (-726 base pairs) or minimal (-66 base pairs) cytochrome c promoter/chloramphenicol acetyltransferase reporter constructs demonstrated contractile activity-induced 1.5-1.7-fold increases in the absence of contractile activity-induced increases in mRNA stability. Transcriptional activation of the -726 promoter was abolished when muscle contraction was inhibited at various subcellular locations by pretreatment with either the Na(+) channel blocker tetrodotoxin, the intracellular Ca(2+) chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester, or the myosin ATPase inhibitor 2,3-butanedione monoxime. It was further reduced in unstimulated cells when mitochondrial ATP synthesis was impaired using the uncoupler 2,4-dinitrophenol. Because the contractile activity-induced response was evident within the minimal promoter, electromobility shift assays performed within the first intron (+75 to +104 base pairs) containing Sp1 sites revealed an elevated DNA binding in response to contractile activity. This was paralleled by increases in Sp1 protein levels. Sp1 overexpression studies also led to increases in cytochrome c transactivation and mRNA levels. These data suggest that variations in the rate of mitochondrial ATP synthesis are important in determining cytochrome c gene expression in muscle cells and that this is mediated, in part, by Sp1-induced increases in cytochrome c transcription.
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Affiliation(s)
- M K Connor
- Departments of Biology and Kinesiology and Health Science, York University, Toronto, Ontario M3J 1P3, Canada
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24
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Bayer AL, Ferguson AG, Lucchesi PA, Samarel AM. Pyk2 expression and phosphorylation in neonatal and adult cardiomyocytes. J Mol Cell Cardiol 2001; 33:1017-30. [PMID: 11343423 DOI: 10.1006/jmcc.2001.1369] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A. L. Bayer, A. G. Ferguson, P. A. Lucchesi and A. M. Samarel. PYK2 Expression and Phosphorylation in Neonatal and Adult Cardiomyocytes. Journal of Molecular and Cellular Cardiology (2001) 33, 1017-1030. Proline-rich tyrosine kinase (PYK2) is a Ca(2+)-dependent, non-receptor protein tyrosine kinase involved in growth factor signaling. Although PYK2 is expressed in a variety of tissues, it has not yet been identified in cardiac muscle. Therefore, immunocytochemical and Western blotting techniques were used to examine PYK2 expression and phosphorylation in neonatal and adult rat ventricular cardiomyocytes (NRVM and ARVM, respectively). PYK2 concentration was much greater in neonatal, than in adult ventricular tissue and cardiomyocytes. In cultured cells, PYK2 expression was highly dependent on [Ca(2+)](i)transients and contractile activity. Non-contracting, low-density NRVM in serum-free culture expressed very low levels of PYK2, while high-density, spontaneously contracting NRVM showed a approximately 12-fold increase in PYK2 expression. Conversely, high-density NRVM treated with nifedipine (10 microM, 48 h) to block spontaneous [Ca(2+)](i)transients and contractile activity resulted in a 2.6-fold decrease in PYK2 levels. Similarly, overnight culture of quiescent ARVM markedly reduced PYK2 levels. Chronic treatment (48 h) of cultured NRVM with the hypertrophic agonist endothelin-1 (ET) (10-300 n M) did not significantly increase PYK2 levels, but strongly shifted the ratio of phosphorylated to total PYK2, indicating that PYK2 phosphorylation accompanies cardiomyocyte hypertrophy. Endothelin-1 also acutely activated PYK2 in both cultured NRVM, and in freshly isolated ARVM. These results suggest that PYK2 is involved in the generation of certain aspects of cardiomyocyte hypertrophy.
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Affiliation(s)
- A L Bayer
- The Cardiovascular Institute, Loyola University Chicago Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA.
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25
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Strait JB, Martin JL, Bayer A, Mestril R, Eble DM, Samarel AM. Role of protein kinase C-epsilon in hypertrophy of cultured neonatal rat ventricular myocytes. Am J Physiol Heart Circ Physiol 2001; 280:H756-66. [PMID: 11158975 DOI: 10.1152/ajpheart.2001.280.2.h756] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using adenovirus (Adv)-mediated overexpression of constitutively active (ca) and dominant-negative (dn) mutants, we examined whether protein kinase C (PKC)-epsilon, the major novel PKC isoenzyme expressed in the adult heart, was necessary and/or sufficient to induce specific aspects of the hypertrophic phenotype in low-density, neonatal rat ventricular myocytes (NRVM) in serum-free culture. Adv-caPKC-epsilon did not increase cell surface area or the total protein-to-DNA ratio. However, cell shape was markedly affected, as evidenced by a 67% increase in the cell length-to-width ratio and a 17% increase in the perimeter-to-area ratio. Adv-caPKC-epsilon also increased atrial natriuretic factor (ANF) and beta-myosin heavy chain (MHC) mRNA levels 2.5 +/- 0.3- and 2.1 +/- 0.2-fold, respectively, compared with NRVM infected with an empty, parent vector (P < 0.05 for both). Conversely, Adv-dnPKC-epsilon did not block endothelin-induced increases in cell surface area, the total protein-to-DNA ratio, or upregulation of beta-MHC and ANF gene expression. However, the dominant-negative inhibitor markedly suppressed endothelin-induced extracellular signal-regulated kinase (ERK) 1/2 activation. Taken together, these results indicate that caPKC-epsilon overexpression alters cell geometry, producing cellular elongation and remodeling without a significant, overall increase in cell surface area or total protein accumulation. Furthermore, PKC-epsilon activation and downstream signaling via the ERK cascade may not be necessary for cell growth, protein accumulation, and gene expression changes induced by endothelin.
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Affiliation(s)
- J B Strait
- Department of Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois 60153, USA
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26
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Abstract
In response to increased ventricular wall tension or neurohumoral stimuli, the myocardium undergoes an adaptive hypertrophy response that temporarily augments pump function. Although initially beneficial, sustained cardiac hypertrophy can lead to decompensation and cardiomyopathy. Recent studies have focused on characterizing the molecular mechanisms that underlie cardiac hypertrophy. An increasing number of signal transduction pathways have been identified as important regulators of the hypertrophic response, including the low-molecular weight GTPases (Ras, RhoA, and Rac), mitogen-activated protein kinases, protein kinase C, and calcineurin. This review will discuss an emerging body of evidence that implicates the calcium-calmodulin-activated protein phosphatase calcineurin as a physiological regulator of the cardiac hypertrophic response. Although the sufficiency of calcineurin to promote cardiomyocyte hypertrophy in vivo and in vitro is established, its overall necessity as a hypertrophic mediator is currently an area of ongoing debate. The use of the calcineurin-inhibitory agents cyclosporine A and FK506 have suggested a necessary role for calcineurin in many, but not all, animal models of hypertrophy or cardiomyopathy. The evidence implicating a role for calcineurin signaling in the heart will be weighed against a growing body of literature suggesting necessary roles for a diverse array of intracellular signaling pathways, highlighting the multifactorial nature of the hypertrophic program.
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Affiliation(s)
- J D Molkentin
- Department of Pediatrics, University of Cincinnati, Division of Molecular Cardiovascular Biology, Children's Hospital Medical Center, Cincinnati, Ohio, USA.
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27
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Liu J, Tian J, Haas M, Shapiro JI, Askari A, Xie Z. Ouabain interaction with cardiac Na+/K+-ATPase initiates signal cascades independent of changes in intracellular Na+ and Ca2+ concentrations. J Biol Chem 2000; 275:27838-44. [PMID: 10874029 DOI: 10.1074/jbc.m002950200] [Citation(s) in RCA: 271] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that partial inhibition of the cardiac myocyte Na(+)/K(+)-ATPase activates signal pathways that regulate myocyte growth and growth-related genes and that increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) and reactive oxygen species (ROS) are two essential second messengers within these pathways. The aim of this work was to explore the relation between [Ca(2+)](i) and ROS. When myocytes were in a Ca(2+)-free medium, ouabain caused no change in [Ca(2+)](i), but it increased ROS as it did when the cells were in a Ca(2+)-containing medium. Ouabain-induced increase in ROS also occurred under conditions where there was little or no change in [Na(+)](i). Exposure of myocytes in Ca(2+)-free medium to monensin did not increase ROS. Increase in protein tyrosine phosphorylation, an early event induced by ouabain, was also independent of changes in [Ca(2+)](i) and [Na(+)](i). Ouabain-induced generation of ROS in myocytes was antagonized by genistein, a dominant negative Ras, and myxothiazol/diphenyleneiodonium, indicating a mitochondrial origin for the Ras-dependent ROS generation. These findings, along with our previous data, indicate that increases in [Ca(2+)](i) and ROS in cardiac myocytes are induced by two parallel pathways initiated at the plasma membrane: One being the ouabain-altered transient interactions of a fraction of the Na(+)/K(+)-ATPase with neighboring proteins (Src, growth factor receptors, adaptor proteins, and Ras) leading to ROS generation, and the other, inhibition of the transport function of another fraction of the Na(+)/K(+)-ATPase leading to rise in [Ca(2+)](i). Evidently, the gene regulatory effects of ouabain in cardiac myocytes require the downstream collaborations of ROS and [Ca(2+)](i).
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Affiliation(s)
- J Liu
- Departments of Pharmacology and Medicine, Medical College of Ohio, Toledo, Ohio 43614, USA
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28
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Strait JB, Samarel AM. Isoenzyme-specific protein kinase C and c-Jun N-terminal kinase activation by electrically stimulated contraction of neonatal rat ventricular myocytes. J Mol Cell Cardiol 2000; 32:1553-66. [PMID: 10900180 DOI: 10.1006/jmcc.2000.1191] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies from our laboratory and others indicate that contraction-induced mechanical loading of cultured neonatal rat ventricular myocytes produces many of the phenotypic changes associated with cardiomyocyte hypertrophy in vivo, and that these changes occur via the activation of serine-threonine protein kinases. These may include the extracellular regulated protein kinases (ERK1 and ERK2), the c-Jun N-terminal kinases (JNK1, JNK2, and JNK3), and one or more isoenzymes of protein kinase C. In this study, we assessed whether one or more of these kinases are activated by stimulated contraction, and whether activation was isoenzyme-specific. Low-density, quiescent cultures of neonatal rat ventricular myocytes were maintained in serum-free medium, or electrically stimulated to contract (3 Hz) for up to 48 h. ERK and JNK activation was assessed by Western blotting with polyclonal antibodies specific for the phosphorylated forms of both kinases. PKC activation was analysed by subcellular fractionation, detergent extraction, and Western blotting using isoenzyme-specific monoclonal antibodies. Stimulated contractile activity produced myocyte hypertrophy, as indicated by increased cell size, a 15+/-5% increase in total protein/DNA ratio, and induction of ANF and beta MHC gene transcription. Electrical pacing did not cause ERK1/2 or JNK1 activation, but increased JNK2 and JNK3 phosphorylation by;two-fold. Subcellular fractionation revealed a time-dependent increase in PKC delta, and to a much lesser extent PKC xi, in a Triton X-100-soluble membrane fraction within 5 min of the onset of stimulated contraction. PKC alpha was not activated by electrical pacing. These results indicate that contraction-induced mechanical loading acutely activates some but not all of the specific isoenzymes of JNKs and PKCs in cardiomyocytes.
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Affiliation(s)
- J B Strait
- The Cardiovascular Institute, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, 60153, USA
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De Windt LJ, Lim HW, Haq S, Force T, Molkentin JD. Calcineurin promotes protein kinase C and c-Jun NH2-terminal kinase activation in the heart. Cross-talk between cardiac hypertrophic signaling pathways. J Biol Chem 2000; 275:13571-9. [PMID: 10788473 DOI: 10.1074/jbc.275.18.13571] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Multiple intracellular signaling pathways have been shown to regulate the hypertrophic growth of cardiomyocytes. Both necessary and sufficient roles have been described for the mitogen activated protein kinase(1) (MAPK) signaling pathway, specific protein kinase C (PKC) isoforms, and calcineurin. Here we investigate the interdependence between calcineurin, MAPK, and PKC isoforms in regulating cardiomyocyte hypertrophy using three separate approaches. Hearts from hypertrophic calcineurin transgenic mice were characterized for PKC and MAPK activation. Transgenic hearts demonstrated activation of c-Jun NH(2)-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK1/2), but not p38 MAPK factors. Calcineurin transgenic hearts demonstrated increased activation of PKCalpha, beta(1), and theta, but not of epsilon, beta(2), or lambda. In a second approach, cultured cardiomyocytes were infected with a calcineurin adenovirus to induce hypertrophy and the effects of pharmacologic inhibitors or co-infection with a dominant negative adenovirus were examined. Calcineurin-mediated hypertrophy was prevented with PKC inhibitors, Ca(2+) chelation, and attenuated with a dominant negative SEK-1 (MKK4) adenovirus, but inhibitors of ERK or p38 activation had no effect. In a third approach, we examined the activation of MAPK factors and PKC isoforms during the progression of load-induced hypertrophy in aortic banded rats with or without cyclosporine. We determined that inhibition of calcineurin activity with cyclosporine prevented PKCalpha, theta, and JNK activation, but did not affect PKCepsilon, beta, lambda, ERK1/2, or p38 activation. Collectively, these data indicate that calcineurin hypertrophic signaling is interconnected with PKCalpha, theta, and JNK in the heart, while PKCepsilon, beta, lambda, p38, and ERK1/2 are not involved in calcineurin-mediated hypertrophy.
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Affiliation(s)
- L J De Windt
- Department of Pediatrics, University of Cincinnati, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
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Eble DM, Strait JB, Govindarajan G, Lou J, Byron KL, Samarel AM. Endothelin-induced cardiac myocyte hypertrophy: role for focal adhesion kinase. Am J Physiol Heart Circ Physiol 2000; 278:H1695-707. [PMID: 10775151 DOI: 10.1152/ajpheart.2000.278.5.h1695] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelin-1 (ET) produces neonatal rat ventricular myocyte (NRVM) hypertrophy and activates focal adhesion kinase (FAK) in other cell types. In the present study, we examined whether ET activated FAK in NRVM and whether FAK was necessary and/or sufficient for ET-induced NRVM hypertrophy. Chronic ET-1 stimulation (100 nM, 48 h) increased protein-to-DNA and myosin heavy chain (MHC)-to-DNA ratios and stimulated the assembly of newly synthesized MHC into sarcomeres. ET-1 also induced the assembly of focal adhesions and costameres, as evidenced by increased phosphotyrosine, FAK, and paxillin immunostaining. Acutely, ET treatment rapidly increased tyrosine phosphorylation of FAK and paxillin. FAK was also activated by phorbol 12-myristate 13-acetate (2 microM, 5 min). Pretreatment with chelerythrine (5 microM) or rottlerin (10 microM) completely blocked ET-induced FAK phosphorylation, indicating that protein kinase C activation was upstream of ET-induced FAK activation. In contrast, ET-induced FAK activation was not affected by blocking calcium influx via L-type voltage-gated calcium channels. Adenoviruses (Adv) containing FAK and FAK-related nonkinase (FRNK) were used to specifically define the role of FAK in ET-induced hypertrophy. ET stimulation failed to increase total protein-to-DNA or MHC-to-DNA ratios or to stimulate sarcomeric assembly in myocytes infected with Adv-FRNK. However, Adv-FAK alone did not increase total protein-to-DNA or MHC-to-DNA ratios and failed to increase the number or size of myofibrils as evidenced by double immunofluorescence labeling for MHC and FAK. Thus, although FAK is necessary for ET-induced NRVM hypertrophy, other ET-generated signals are also required to elicit the hypertrophic phenotype.
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Affiliation(s)
- D M Eble
- Cardiovascular Institute and Departments of Medicine and Physiology, Loyola University Chicago, Maywood, Illinois 60153, USA.
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Taigen T, De Windt LJ, Lim HW, Molkentin JD. Targeted inhibition of calcineurin prevents agonist-induced cardiomyocyte hypertrophy. Proc Natl Acad Sci U S A 2000; 97:1196-201. [PMID: 10655507 PMCID: PMC15566 DOI: 10.1073/pnas.97.3.1196] [Citation(s) in RCA: 235] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cardiac hypertrophy is a major predictor of future morbidity and mortality. Recent investigation has centered around identifying the molecular signaling pathways that regulate cardiac myocyte reactivity with the goal of modulating pathologic hypertrophic programs. One potential regulator of cardiomyocyte hypertrophy is the calcium-sensitive phosphatase calcineurin. We show here that calcineurin enzymatic activity, mRNA, and protein levels are increased in cultured neonatal rat cardiomyocytes by hypertrophic agonists such as angiotensin II, phenylephrine, and 1% fetal bovine serum. This induction of calcineurin activity was associated with an increase in calcineurin Abeta (CnAbeta) mRNA and protein, but not in CnAalpha or CnAgamma. Agonist-dependent increases in calcineurin enzymatic activity were specifically inhibited with an adenovirus expressing a noncompetitive peptide inhibitor of calcineurin known as cain [Lai, M. M., Burnett, P. E., Wolosker, H., Blackshaw, S. & Snyder, S. H. (1998) J. Biol. Chem. 273, 18325-18331]. Targeted inhibition of calcineurin with cain or an adenovirus expressing only the calcineurin inhibitory domain of AKAP79 attenuated cardiomyocyte hypertrophy and atrial natriuretic factor expression in response to angiotensin II, phenylephrine, and 1% fetal bovine serum. These data demonstrate that calcineurin is an important regulator of cardiomyocyte hypertrophy in response to certain agonists and suggest that cyclosporin A and FK506 function to attenuate cardiac hypertrophy by specifically inhibiting calcineurin.
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Affiliation(s)
- T Taigen
- Division of Molecular Cardiovascular Biology, Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
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Hines WA, Thorburn J, Thorburn A. Cell density and contraction regulate p38 MAP kinase-dependent responses in neonatal rat cardiac myocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H331-41. [PMID: 10409213 DOI: 10.1152/ajpheart.1999.277.1.h331] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In vitro cardiac myocyte hypertrophy is characterized by increased cell size, sarcomere organization, and induction of several genes including atrial natriuretic factor (ANF). The hypertrophic growth program has been associated with activation of various mitogen-activated protein kinase (MAP) kinase family members, one of which is a stress kinase, p38. In this study, we found that the p38-specific inhibitor SB-203580 failed to inhibit phenylephrine-induced ANF-driven gene expression in low-density myocyte cultures but did inhibit gene expression in higher density cultures. Dense myocyte cultures also had a higher metabolic activity and contraction rate than cells plated at low density. We found that mimicking this effect by rapid electrical pacing activated ANF-driven gene expression and that this expression was inhibited by inactivation of p38. However, addition of SB-203580 at time points ranging between 1 and 72 h suggests that the effect of p38 on the ANF promoter may be both direct and indirect. Electrical pacing induced a small, but consistent, increase in p38 phosphorylation (phospho-p38) at time points ranging from 30 min to 4 h, but at later times phospho-p38 levels were reduced. When myocytes were treated with phenylephrine or electrically paced in the presence of the p38 inhibitor, there was little discernible change in morphology or rates of protein synthesis from DMSO-treated cells at 48 or 72 h. These data indicate that cell density and myocyte contraction may modulate p38-dependent pathways for ANF gene expression, but these pathways may not be direct and have limited effects on hypertrophic morphology.
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Affiliation(s)
- W A Hines
- Department of Human Genetics, Program in Human Molecular Biology and Genetics, Departments of Oncological Sciences, Human Genetics, and Internal Medicine, University of Utah, Salt Lake City, Utah 84112, USA
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