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Xue W, Liu Q, Cai L, Wang Z, Feng W. Stable overexpression of human metallothionein-IIA in a heart-derived cell line confers oxidative protection. Toxicol Lett 2009; 188:70-6. [PMID: 19433272 DOI: 10.1016/j.toxlet.2009.03.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/06/2009] [Accepted: 03/09/2009] [Indexed: 11/19/2022]
Abstract
Metallothionein (MT) is a metal binding protein and cardioprotective. In order to understand the molecular mechanisms underlying the role of MT in the heart, in the current study we established a stable MT-IIA over-expressing cardiac cell line, and evaluated its anti-oxidative property. Rat heart-derived H9c2 cell line was stably transfected with a vector in which the human MT-IIA gene was placed under the control of the constitutively active beta-actin promoter. The transfected cell line (H9c2MT7) exhibited similar growth kinetics and morphology. Western blotting analysis showed that H9c2MT7 had a remarkable increased MT protein level compared with the parent cell line H9c2. Addition of 25 microM ZnSO(4) had an undetectable effect on the induction of endogenous MT, but it likely stabilized the MT protein that is expressed only in H9c2MT7 cells. H9c2MT7 cells showed marked reduction in reactive oxygen species production when exposed to hydrogen peroxide or subjected to hypoxia/reoxygenation challenge evaluated by dihydroethidium staining. In addition, transfection of MT conferred cellular resistance to cadmium toxicity. In summary, we have established a stable human MT-IIA over-expressing cardiac cell line; and this cell line showed a markedly increased oxidative protection and would be useful for dissection of the mechanisms of MT in the cardiac protection.
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Affiliation(s)
- Wanli Xue
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA
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102
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Hibuse T, Maeda N, Nakatsuji H, Tochino Y, Fujita K, Kihara S, Funahashi T, Shimomura I. The heart requires glycerol as an energy substrate through aquaporin 7, a glycerol facilitator. Cardiovasc Res 2009; 83:34-41. [PMID: 19297367 DOI: 10.1093/cvr/cvp095] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Cardiomyocytes require fatty acids and glucose for energy production. However, other nutrients and substrates that may serve as possible candidates for a cardiac energy source have not been fully studied. Several reports showed that a moderate expression of aquaporin 7 (AQP7), a member of the aquaglyceroporin family that is permeated by glycerol and water, is observed in heart tissue. However, the functional role of cardiac AQP7 is not clear. The aim of this study was to investigate the significance of glycerol as a cardiac energy substrate and to clarify the role of cardiac AQP7. METHODS AND RESULTS Heart function and morphology were examined in AQP7-knockout (KO) mice under basal conditions and during pressure overload [isoproterenol infusion and transverse aortic constriction (TAC)]. Glycerol uptake and glycerol-dependent ATP production were measured in AQP7-knockdown cardiac cells. Cardiac glycerol consumption was analysed in ex vivo beating hearts. Cardiac morphology and function in KO mice were similar to those of wild-type (WT) mice under basal conditions, although low glycerol and ATP content were noted in hearts of KO mice. In H9c2 cardiomyotubes, knockdown of AQP7 was associated with a significant reduction of glycerol uptake. The ex vivo heart study demonstrated that cardiac glycerol consumption levels in KO mice were significantly lower than those of WT mice. Furthermore, isoproterenol challenge induced severe left ventricular hypertrophy in KO mice, and TAC resulted in a higher mortality rate in KO mice than in WT mice. CONCLUSION The results indicate that AQP7 acts as a glycerol facilitator in cardiomyocytes and that glycerol is a substrate for cardiac energy production.
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Affiliation(s)
- Toshiyuki Hibuse
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, 2-2-B5 Yamada-oka, Suita, Osaka, Japan
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103
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Down-regulation of SM22/transgelin gene expression during H9c2 cells differentiation. Mol Cell Biochem 2009; 327:145-52. [DOI: 10.1007/s11010-009-0052-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 02/04/2009] [Indexed: 10/21/2022]
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Konorev EA, Vanamala S, Kalyanaraman B. Differences in doxorubicin-induced apoptotic signaling in adult and immature cardiomyocytes. Free Radic Biol Med 2008; 45:1723-8. [PMID: 18926904 PMCID: PMC3039518 DOI: 10.1016/j.freeradbiomed.2008.09.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 09/09/2008] [Accepted: 09/10/2008] [Indexed: 11/26/2022]
Abstract
A proposed mechanism for the cardiotoxicity of doxorubicin (DOX) involves apoptosis in cardiomyocytes. In the study described here, we investigated the molecular basis for the differences in DOX-induced toxicity in adult rat cardiomyocytes (ARCM), neonatal rat cardiomyocytes (NRCM), and rat embryonic H9c2 cardiomyoblasts. Activation of caspase-9 and -3 was considerably lower in DOX-treated ARCM as compared with NRCM and H9c2 cardiomyoblasts. Addition of cytochrome c caused the activation of caspase-9 and -3 in permeabilized NRCM and H9c2 cardiomyoblasts but not in permeabilized ARCM. Expression of proapoptotic proteins, apoptotic protease activating factor-1 (Apaf1), and procaspase-9 was significantly lower, and abundance of antiapoptotic X-linked inhibitor of apoptosis protein (XIAP) was higher in ARCM, as compared with immature cardiac cells. Despite the abundance of XIAP in ARCM, its role in the inhibition of apoptosome function was dismissed, as second mitochondria-derived activator of caspases (Smac)-N7 peptide, had no effect on caspase activation in response to cytochrome c in these cells. Adenoviral expression of Apaf1 exacerbated the activation of caspase-9 and -3 in DOX-treated NRCM, but did not increase their activities in DOX-treated ARCM. This finding points to a major difference in the apoptotic signaling between immature and adult cardiomyocytes. The mitochondrial apoptotic pathway is limited in ARCM treated with DOX.
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Affiliation(s)
- Eugene A Konorev
- Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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105
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Gassanov N, Er F, Zagidullin N, Jankowski M, Gutkowska J, Hoppe UC. Retinoid acid-induced effects on atrial and pacemaker cell differentiation and expression of cardiac ion channels. Differentiation 2008; 76:971-80. [DOI: 10.1111/j.1432-0436.2008.00283.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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106
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Lee YM, Lee JO, Jung JH, Kim JH, Park SH, Park JM, Kim EK, Suh PG, Kim HS. Retinoic acid leads to cytoskeletal rearrangement through AMPK-Rac1 and stimulates glucose uptake through AMPK-p38 MAPK in skeletal muscle cells. J Biol Chem 2008; 283:33969-74. [PMID: 18927084 DOI: 10.1074/jbc.m804469200] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retinoic acid (RA) is one of the major components of vitamin A. In the present study, we found that retinoic acid activated AMP-activated protein kinase (AMPK). RA induced Rac1-GTP formation and phosphorylation of its downstream target, p21-activated kinase (PAK), whereas the inhibition of AMPK blocked RA-induced Rac1 activation. Moreover, cofilin, an actin polymerization regulator, was activated when incubated with RA. We then showed that inhibition of AMPK by compound C, a selective inhibitor of AMPK, or small interfering RNA of AMPK alpha1 blocked RA-induced cofilin phosphorylation. Additionally, we found that retinoic acid-stimulated glucose uptake in differentiated C2C12 myoblast cells and activated p38 mitogen-activated protein kinase (MAPK). Finally, the inhibition of AMPK and p38 MAPK blocked retinoic acid-induced glucose uptake. In summary, our results suggest that retinoic acid may have cytoskeletal roles in skeletal muscle cells via stimulation of the AMPK-Rac1-PAK-cofillin pathway and may also have beneficial roles in glucose metabolism via stimulation of the AMPK-p38 MAPK pathway.
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Affiliation(s)
- Yun Mi Lee
- Department of Anatomy, Korea University College of Medicine, Seoul 136-1705, Korea
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107
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Wang YJ, Chen BS, Lin MW, Lin AA, Peng H, Sung RJ, Wu SN. Time-Dependent Block of Ultrarapid-Delayed Rectifier K+ Currents by Aconitine, a Potent Cardiotoxin, in Heart-Derived H9c2 Myoblasts and in Neonatal Rat Ventricular Myocytes. Toxicol Sci 2008; 106:454-63. [DOI: 10.1093/toxsci/kfn189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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108
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Harmon EB, Harmon ML, Larsen TD, Paulson AF, Perryman MB. Myotonic dystrophy protein kinase is expressed in embryonic myocytes and is required for myotube formation. Dev Dyn 2008; 237:2353-66. [DOI: 10.1002/dvdy.21653] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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109
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The mechanisms of propofol-induced block on ion currents in differentiated H9c2 cardiac cells. Eur J Pharmacol 2008; 590:93-8. [DOI: 10.1016/j.ejphar.2008.05.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/09/2008] [Accepted: 05/22/2008] [Indexed: 11/20/2022]
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110
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Leclerc C, Webb SE, Miller AL, Moreau M. An increase in intracellular Ca2+ is involved in pronephric tubule differentiation in the amphibian Xenopus laevis. Dev Biol 2008; 321:357-67. [PMID: 18634776 DOI: 10.1016/j.ydbio.2008.06.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 05/08/2008] [Accepted: 06/20/2008] [Indexed: 10/21/2022]
Abstract
The pronephros is the first kidney to develop and is the functional embryonic kidney in lower vertebrates. It has previously been shown that pronephric tubules can be induced to form ex vivo in ectodermal tissue by treatment with activin A and retinoic acid. In this study, we investigated the role of Ca(2+) signaling in the formation of the pronephric tubules both in intact Xenopus embryos and ex vivo. In the ex vivo system, retinoic acid but not activin A stimulated the generation of Ca(2+) transients during tubule formation. Furthermore, tubule differentiation could be induced by agents that increase the concentration of intracellular Ca(2+) in activin A-treated ectoderm. In addition, tubule formation was inhibited by loading the ectodermal tissue with the Ca(2+) chelator, BAPTA-AM prior to activin A/retinoic acid treatment. In intact embryos, Ca(2+) transients were also recorded during tubule formation, and photo-activation of the caged Ca(2+) chelator, diazo-2, localized to the pronephric domain, produced embryos with a shortened and widened tubule phenotype. In addition, the location of the Ca(2+) transients observed, correlated with the expression pattern of the specific pronephric tubule gene, XSMP-30. These data indicate that Ca(2+) might be a necessary signal in the process of tubulogenesis both ex vivo and in intact embryos.
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Affiliation(s)
- Catherine Leclerc
- Centre de Biologie du Développement, UMR 5547 and GDR 2688, Université Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse, Cedex 04, France
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111
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Ounzain S, Dacwag CS, Samani NJ, Imbalzano AN, Chong NW. Comparative in silico analysis identifies bona fide MyoD binding sites within the Myocyte stress 1 gene promoter. BMC Mol Biol 2008; 9:50. [PMID: 18489770 PMCID: PMC2408591 DOI: 10.1186/1471-2199-9-50] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Accepted: 05/19/2008] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Myocyte stress 1 (MS1) is a striated muscle actin binding protein required for the muscle specific activity of the evolutionary ancient myocardin related transcription factor (MRTF)/serum response factor (SRF) transcriptional pathway. To date, little is known about the molecular mechanisms that govern skeletal muscle specific expression of MS1. Such mechanisms are likely to play a major role in modulating SRF activity and therefore muscle determination, differentiation and regeneration. In this study we employed a comparative in silico analysis coupled with an experimental promoter characterisation to delineate these mechanisms. RESULTS Analysis of MS1 expression in differentiating C2C12 muscle cells demonstrated a temporal differentiation dependent up-regulation in ms1 mRNA. An in silico comparative sequence analysis identified two conserved putative myogenic regulatory domains within the proximal 1.5 kbp of 5' upstream sequence. Co-transfecting C2C12 myoblasts with ms1 promoter/luciferase reporters and myogenic regulatory factor (MRF) over-expression plasmids revealed specific sensitivity of the ms1 promoter to MyoD. Subsequent mutagenesis and EMSA analysis demonstrated specific targeting of MyoD at two distinct E-Boxes (E1 and E2) within identified evolutionary conserved regions (ECRs, alpha and beta). Chromatin immunoprecipitation (ChIP) analysis indicates that co-ordinated binding of MyoD at E-Boxes located within ECRs alpha and beta correlates with the temporal induction in ms1 mRNA. CONCLUSION These findings suggest that the tissue specific and differentiation dependent up-regulation in ms1 mRNA is mediated by temporal binding of MyoD at distinct evolutionary conserved E-Boxes within the ms1 5' upstream sequence. We believe, through its activation of ms1, this is the first study to demonstrate a direct link between MyoD activity and SRF transcriptional signalling, with clear implications for the understanding of muscle determination, differentiation and regeneration.
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Affiliation(s)
- Samir Ounzain
- Cardiology Group, Department of Cardiovascular Sciences, University of Leicester, Clinical Sciences Wing, Glenfield General Hospital, Leicester, LE3 9QP, UK.
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112
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Saeedi R, Parsons HL, Wambolt RB, Paulson K, Sharma V, Dyck JRB, Brownsey RW, Allard MF. Metabolic actions of metformin in the heart can occur by AMPK-independent mechanisms. Am J Physiol Heart Circ Physiol 2008; 294:H2497-506. [PMID: 18375721 DOI: 10.1152/ajpheart.00873.2007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The metabolic actions of the antidiabetic agent metformin reportedly occur via the activation of the AMP-activated protein kinase (AMPK) in the heart and other tissues in the presence or absence of changes in cellular energy status. In this study, we tested the hypothesis that metformin has AMPK-independent effects on metabolism in heart muscle. Fatty acid oxidation and glucose utilization (glycolysis and glucose uptake) were measured in isolated working hearts from halothane-anesthetized male Sprague-Dawley rats and in cultured heart-derived H9c2 cells in the absence or in the presence of metformin (2 mM). Fatty acid oxidation and glucose utilization were significantly altered by metformin in hearts and H9c2 cells. AMPK activity was not measurably altered by metformin in either model system, and no impairment of energetic state was observed in the intact hearts. Furthermore, the inhibition of AMPK by 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl]-3-pyridin-4-yl-pyyrazolo[1,5-a] pyrimidine (Compound C), a well-recognized pharmacological inhibitor of AMPK, or the overexpression of a dominant-negative form of AMPK failed to prevent the metabolic actions of metformin in H9c2 cells. The exposure of H9c2 cells to inhibitors of p38 mitogen-activated protein kinase (p38 MAPK) or protein kinase C (PKC) partially or completely abrogated metformin-induced alterations in metabolism in these cells, respectively. Thus the metabolic actions of metformin in the heart muscle can occur independent of changes in AMPK activity and may be mediated by p38 MAPK- and PKC-dependent mechanisms.
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Affiliation(s)
- Ramesh Saeedi
- Department of Pathology and Laboratory Medicine, James Hogg iCAPTURE Centre for Cardiovascular and Pulmonary Research, University of British Columbia-Saint Paul's Hospital, Canada
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113
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Piantadosi CA, Suliman HB. Transcriptional Regulation of SDHa flavoprotein by nuclear respiratory factor-1 prevents pseudo-hypoxia in aerobic cardiac cells. J Biol Chem 2008; 283:10967-77. [PMID: 18252725 DOI: 10.1074/jbc.m709741200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Nuclear respiratory factor-1 (NRF-1) is integral to the transcriptional regulation of mitochondrial biogenesis, but its control over various respiratory genes overlaps other regulatory elements including those involved in O(2) sensing. Aerobic metabolism generally suppresses hypoxia-sensitive genes, e.g. via hypoxia-inducible factor-1 (HIF-1), but mutations in Complex II-succinate dehydrogenase (SDH), a tumor suppressor, stabilize HIF-1, producing pseudo-hypoxia. In aerobic cardiomyocytes, which rely on oxidative phosphorylation, we tested the hypothesis that NRF-1 regulates Complex II expression and opposes hypoxia-inducible factor-1. NRF-1 gene silencing blocked aerobic succinate oxidation, increasing nuclear HIF-1alpha protein prior to the loss of Complex I function. We postulated that NRF-1 suppression either specifically decreases the expression of one or more SDH subunits and increases succinate availability to regulate HIF-1 prolyl hydroxylases, or stimulates mitochondrial reactive oxygen production, which interferes with HIF-1alpha degradation. Using promoter analysis, gene silencing, and chromatin immunoprecipitation, NRF-1 was found to bind to the gene promoters of two of four nuclear-encoded Complex II subunits: SDHa and SDHd, but the enzyme activity was dynamically regulated through the catalytic SDHa flavoprotein. Complex II was inactivated by SDHa silencing, which led to aerobic HIF-1alpha stabilization, nuclear translocation, and enhanced expression of glucose transporters and heme oxygenase-1. This was unrelated to mitochondrial ROS production, reversible by high alpha-ketoglutarate concentrations, and coherent with regulation of HIF-1 by succinate reported in tumor cells. These findings disclose a novel role for NRF-1 in the transcriptional control of Complex II and prevention of pseudo-hypoxic gene expression in aerobic cardiac cells.
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Affiliation(s)
- Claude A Piantadosi
- Department of Medicine, Duke University School of Medicine and the Durham Veteran's Administration Medical Center, Durham, North Carolina 27710, USA.
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114
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Wang YJ, Lin MW, Lin AA, Wu SN. Riluzole-induced block of voltage-gated Na+ current and activation of BKCa channels in cultured differentiated human skeletal muscle cells. Life Sci 2007; 82:11-20. [PMID: 18068197 DOI: 10.1016/j.lfs.2007.10.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 10/06/2007] [Accepted: 10/06/2007] [Indexed: 11/17/2022]
Abstract
Riluzole is known to be of therapeutic use in the management of amyotrophic lateral sclerosis. In this study, we investigated the effects of riluzole on ion currents in cultured differentiated human skeletal muscle cells (dHSkMCs). Western blotting revealed the protein expression of alpha-subunits for both large-conductance Ca2+-activated K+ (BK(Ca)) channel and Na+ channel (Na(v)1.5) in these cells. Riluzole could reduce the frequency of spontaneous beating in dHSkMCs. In whole-cell configuration, riluzole suppressed voltage-gated Na+ current (I(Na)) in a concentration-dependent manner with an IC50 value of 2.3 microM. Riluzole (10 microM) also effectively increased Ca2+-activated K+ current (I(K(Ca))) which could be reversed by iberiotoxin (200 nM) and paxilline (1 microM), but not by apamin (200 nM). In inside-out patches, when applied to the inside of the cell membrane, riluzole (10 microM) increased BK(Ca)-channel activity with a decrease in mean closed time. Simulation studies also unraveled that both decreased conductance of I(Na) and increased conductance of I(K(Ca)) utilized to mimic riluzole actions in skeletal muscle cells could combine to decrease the amplitude of action potentials and increase the repolarization of action potentials. Taken together, inhibition of I(Na) and stimulation of BK(Ca)-channel activity caused by this drug are partly, if not entirely, responsible for its muscle relaxant actions in clinical setting.
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Affiliation(s)
- Ya-Jean Wang
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan
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115
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Okazaki T, Ebihara S, Asada M, Yamanda S, Saijo Y, Shiraishi Y, Ebihara T, Niu K, Mei H, Arai H, Yambe T. Macrophage colony-stimulating factor improves cardiac function after ischemic injury by inducing vascular endothelial growth factor production and survival of cardiomyocytes. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1093-103. [PMID: 17717142 PMCID: PMC1988861 DOI: 10.2353/ajpath.2007.061191] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Macrophage colony-stimulating factor (M-CSF), known as a hematopoietic growth factor, induces vascular endothelial growth factor (VEGF) production from skeletal muscles. However, the effects of M-CSF on cardiomyocytes have not been reported. Here, we show M-CSF increases VEGF production from cardiomyocytes, protects cardiomyocytes and myotubes from cell death, and improves cardiac function after ischemic injury. In mice, M-CSF increased VEGF production in hearts and in freshly isolated cardiomyocytes, which showed M-CSF receptor expression. In rat cell line H9c2 cardiomyocytes and myotubes, M-CSF induced VEGF production via the Akt signaling pathway, and M-CSF pretreatment protected these cells from H(2)O(2)-induced cell death. M-CSF activated Akt and extracellular signal-regulated kinase signaling pathways and up-regulated downstream anti-apoptotic Bcl-xL expression in these cells. Using goats as a large animal model of myocardial infarction, we found that M-CSF treatment after the onset of myocardial infarction by permanent coronary artery ligation promoted angiogenesis in ischemic hearts but did not reduce the infarct area. M-CSF pretreatment of the goat myocardial infarction model by coronary artery occlusion-reperfusion improved cardiac function, as assessed by hemodynamic parameters and echocardiography. These results suggest M-CSF might be a novel therapeutic agent for ischemic heart disease.
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Affiliation(s)
- Tatsuma Okazaki
- Department of Geriatrics and Gerontology, Tohoku University School of Medicine, Seiryo-machi 1-1, Aoba-ku, Sendai 980-8574, Japan
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116
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Lund KC, Peterson LL, Wallace KB. Absence of a universal mechanism of mitochondrial toxicity by nucleoside analogs. Antimicrob Agents Chemother 2007; 51:2531-9. [PMID: 17470651 PMCID: PMC1913246 DOI: 10.1128/aac.00039-07] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 03/08/2007] [Accepted: 04/24/2007] [Indexed: 11/20/2022] Open
Abstract
Nucleoside analogs are associated with various mitochondrial toxicities, and it is becoming increasingly difficult to accommodate these differences solely in the context of DNA polymerase gamma inhibition. Therefore, we examined the toxicities of zidovudine (AZT) (10 and 50 microM; 2.7 and 13.4 microg/ml), didanosine (ddI) (10 and 50 microM; 2.4 and 11.8 microg/ml), and zalcitabine (ddC) (1 and 5 microM; 0.21 and 1.1 microg/ml) in HepG2 and H9c2 cells without the presumption of mitochondrial DNA (mtDNA) depletion. Ethidium bromide (EtBr) (0.5 microg/ml; 1.3 microM) was used as a positive control. AZT treatment resulted in metabolic disruption (increased lactate and superoxide) and increased cell mortality with decreased proliferation, while mtDNA remained unchanged or increased (HepG2 cells; 50 microM AZT). ddC caused pronounced mtDNA depletion in HepG2 cells but not in H9c2 cells and increased mortality in HepG2 cells, but no significant metabolic disruption in either cell type. ddI caused a moderate depletion of mtDNA in both cell types but showed no other effects. EtBr exposure resulted in metabolic disruption, increased cell mortality with decreased cell proliferation, and mtDNA depletion in both cell types. We conclude that nucleoside analogs display unique toxicities within and between culture models, and therefore, care should be taken when generalizing about the mechanisms of nucleoside reverse transcriptase inhibitor toxicity. Additionally, mtDNA abundance does not necessarily correlate with metabolic disruption, especially in cell culture; careful discernment is recommended in this regard.
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Affiliation(s)
- Kaleb C Lund
- Department of Biochemistry and Molecular Biology, Toxicology Graduate Program, University of Minnesota Medical School Duluth, 1035 University Drive, Duluth, MN 55812, USA.
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Pedemonte N, Boido D, Moran O, Giampieri M, Mazzei M, Ravazzolo R, Galietta LJV. Structure-Activity Relationship of 1,4-Dihydropyridines as Potentiators of the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel. Mol Pharmacol 2007; 72:197-207. [PMID: 17452495 DOI: 10.1124/mol.107.034702] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations occurring in the CFTR gene, encoding for the cystic fibrosis transmembrane conductance regulator chloride channel, cause cystic fibrosis (CF). Mutations belonging to class II, such as DeltaPhe508, give rise to a protein with both a defective maturation and altered channel gating. Mutations belonging to class III, such as G551D and G1349D, cause only a gating defect. We have previously identified antihypertensive 1,4-dihydropyridines (DHPs), a class of drugs that block voltage-dependent Ca(2+) channels, as effective potentiators of CFTR gating, able to correct the defective activity of CFTR mutants (Mol Pharmacol 68:1736-1746, 2005). However, optimization of potency for CFTR versus Ca(2+) channels is required to design selective compounds for CFTR pharmacotherapy. In the present study, we have established DHP structure-activity relationship for both CFTR potentiation and Ca(2+) channel inhibition using cell-based assays for both types of channels. A panel of 333 felodipine analogs was studied to understand the effect of various substitutions and modifications in the DHP scaffold. Our results show that alkyl substitutions at the para position of the 4-phenyl ring lead to compounds with very low activity on Ca(2+) channels and strong effect as potentiators on the DeltaPhe508, G551D, and G1349D CFTR mutants.
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Affiliation(s)
- Nicoletta Pedemonte
- Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, L.go Gerolamo Gaslini 5, 16148 Genova, Italy
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118
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Brodsky GL, Bowersox JA, Fitzgerald-Miller L, Miller LA, Maclean KN. The prelamin A pre-peptide induces cardiac and skeletal myoblast differentiation. Biochem Biophys Res Commun 2007; 356:872-9. [PMID: 17389141 DOI: 10.1016/j.bbrc.2007.03.062] [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: 03/07/2007] [Accepted: 03/08/2007] [Indexed: 10/23/2022]
Abstract
Prelamin A processing is unique amongst mammalian proteins and results in the production of a farnesylated and carboxymethylated peptide. We examined the effect of pathogenic LMNA mutations on prelamin A processing, and of the covalently modified peptide on cardiac and skeletal myoblast differentiation. Here we report a mutation associated with dilated cardiomyopathy prevents prelamin A peptide production. In addition, topical application of the covalently modified C-terminal peptide to proliferating skeletal and cardiac myoblasts induced myotube and striated tissue formation, respectively. Western blot analysis revealed that skeletal and cardiac myoblasts are the first cell lines examined to contain unprocessed prelamin A, and immunostaining of peptide-treated cells revealed a previously unidentified role for prelamin A in cytoskeleton formation and intercellular organization. These results demonstrate a direct role for prelamin A in myoblast differentiation and indicate the prelamin A peptide may have therapeutic potential.
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Affiliation(s)
- Gary L Brodsky
- Division of Medical Oncology, Department of Medicine, University of Colorado at Denver and Health Sciences Center, Denver, CO 80262, USA.
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Sardão VA, Oliveira PJ, Holy J, Oliveira CR, Wallace KB. Vital imaging of H9c2 myoblasts exposed to tert-butylhydroperoxide--characterization of morphological features of cell death. BMC Cell Biol 2007; 8:11. [PMID: 17362523 PMCID: PMC1831770 DOI: 10.1186/1471-2121-8-11] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Accepted: 03/16/2007] [Indexed: 11/10/2022] Open
Abstract
Background When exposed to oxidative conditions, cells suffer not only biochemical alterations, but also morphologic changes. Oxidative stress is a condition induced by some pro-oxidant compounds, such as by tert-butylhydroperoxide (tBHP) and can also be induced in vivo by ischemia/reperfusion conditions, which is very common in cardiac tissue. The cell line H9c2 has been used as an in vitro cellular model for both skeletal and cardiac muscle. Understanding how these cells respond to oxidative agents may furnish novel insights into how cardiac and skeletal tissues respond to oxidative stress conditions. The objective of this work was to characterize, through vital imaging, morphological alterations and the appearance of apoptotic hallmarks, with a special focus on mitochondrial changes, upon exposure of H9c2 cells to tBHP. Results When exposed to tBHP, an increase in intracellular oxidative stress was detected in H9c2 cells by epifluorescence microscopy, which was accompanied by an increase in cell death that was prevented by the antioxidants Trolox and N-acetylcysteine. Several morphological alterations characteristic of apoptosis were noted, including changes in nuclear morphology, translocation of phosphatidylserine to the outer leaflet of the cell membrane, and cell blebbing. An increase in the exposure period or in tBHP concentration resulted in a clear loss of membrane integrity, which is characteristic of necrosis. Changes in mitochondrial morphology, consisting of a transition from long filaments to small and round fragments, were also detected in H9c2 cells after treatment with tBHP. Bax aggregates near mitochondrial networks were formed after short periods of incubation. Conclusion Vital imaging of alterations in cell morphology is a useful method to characterize cellular responses to oxidative stress. In the present work, we report two distinct patterns of morphological alterations in H9c2 cells exposed to tBHP, a pro-oxidant agent frequently used as model to induce oxidative stress. In particular, dynamic changes in mitochondrial networks could be visualized, which appear to be centrally involved in how these cells respond to oxidative stress. The data also indicate that the cause of H9c2 cell death following tBHP exposure is increased intracellular oxidative stress.
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Affiliation(s)
- Vilma A Sardão
- Center for Neurosciences and Cellular Biology, University of Coimbra, Coimbra, Portugal
| | - Paulo J Oliveira
- Center for Neurosciences and Cellular Biology, University of Coimbra, Coimbra, Portugal
| | - Jon Holy
- Department of Anatomy, Microbiology and Pathology, University of Minnesota-Medical School, Duluth, USA
| | - Catarina R Oliveira
- Center for Neurosciences and Cellular Biology, University of Coimbra, Coimbra, Portugal
| | - Kendall B Wallace
- Department of Biochemistry and Molecular Biology, University of Minnesota-Medical Medical School, Duluth, USA
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120
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Gassanov N, Jankowski M, Danalache B, Wang D, Grygorczyk R, Hoppe UC, Gutkowska J. Arginine vasopressin-mediated cardiac differentiation: insights into the role of its receptors and nitric oxide signaling. J Biol Chem 2007; 282:11255-65. [PMID: 17298949 DOI: 10.1074/jbc.m610769200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Despite the existence of a functional arginine vasopressin (AVP) system in the adult heart and evidence that AVP induces myogenesis, its significance in cardiomyogenesis is currently unknown. In the present study, we hypothesized a role for AVP in cardiac differentiation of D3 and lineage-specific embryonic stem (ES) cells expressing green fluorescent protein under the control of atrial natriuretic peptide (Anp) or myosin light chain-2V (Mlc-2V) promoters. Furthermore, we investigated the nitric oxide (NO) involvement in AVP-mediated pathways. AVP exposure increased the number of beating embryoid bodies, fluorescent cells, and expression of Gata-4 and other cardiac genes. V1a and V2 receptors (V1aR and V2R) differentially mediated these effects in transgenic ES cells, and exhibited a distinct developmentally regulated mRNA expression pattern. A NO synthase inhibitor, L-NAME, powerfully antagonized the AVP-induced effects on cardiogenic differentiation, implicating NO signaling in AVP-mediated pathways. Indeed, AVP elevated the mRNA and protein levels of endothelial NO synthase (eNOS) through V2R stimulation. Remarkably, increased beating activity was found in AVP-treated ES cells with down-regulated eNOS expression, indicating the significant involvement of additional pathways in cardiomyogenic effects of AVP. Finally, patch clamp recordings revealed specific AVP-induced changes of action potentials and increased L-type Ca2+ (ICa,L) current densities in differentiated ventricular phenotypes. Thus, AVP promotes cardiomyocyte differentiation of ES cells and involves Gata-4 and NO signaling. AVP-induced action potential prolongation appears likely to be linked to the increased ICa,L current in ventricular cells. In conclusion, this report provides new evidence for the essential role of the AVP system in ES cell-derived cardiomyogenesis.
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Affiliation(s)
- Natig Gassanov
- Department of Internal Medicine III, University of Cologne, 50924 Cologne, Germany
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121
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Kee HJ, Kim JR, Nam KI, Park HY, Shin S, Kim JC, Shimono Y, Takahashi M, Jeong MH, Kim N, Kim KK, Kook H. Enhancer of polycomb1, a novel homeodomain only protein-binding partner, induces skeletal muscle differentiation. J Biol Chem 2006; 282:7700-9. [PMID: 17192267 DOI: 10.1074/jbc.m611198200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Homeodomain only protein, Hop, is an unusual small protein that modulates target gene transcription without direct binding to DNA. Here we show that Hop interacts with Enhancer of Polycomb1 (Epc1), a homolog of a Drosophila polycomb group gene product that regulates transcription, to induce the skeletal muscle differentiation. Yeast two-hybrid assay with the human adult heart cDNA library revealed that Hop can associate with Epc1. The amino-terminal domain of Epc1 as well as full Epc1 physically interacted with Hop in mammalian cells and in yeast. Epc1 is highly expressed in the embryonic heart and adult skeletal muscles. Serum deprivation induced differentiation of H9c2, a myoblast cell line, into skeletal myocytes, and Epc1 was up-regulated. Differentiation of H9c2 was induced by Epc1 overexpression, although it was severely impaired in Epc1-knockdown cells. Co-transfection of Hop potentiated Epc1-induced transactivation of myogenin and myotube formation. Hop knock-out mice elicited a decrease in myosin heavy chain and myogenin expressions in skeletal muscle and showed delay in hamstring muscle healing after injury. Differentiation was impaired in skeletal myoblasts from Hop knock-out mice. These results suggest that Epc1 plays a role in the initiation of skeletal muscle differentiation, and its interaction with Hop is required for the full activity.
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Affiliation(s)
- Hae Jin Kee
- Medical Research Center for Gene Regulation, Research Institute of Medical Sciences, and Brain Korea 21 Project, Center for Biomedical Human Resources, Chonnam National University Medical School, Gwangju 501-746, South Korea
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122
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Sucharov CC, Langer S, Bristow M, Leinwand L. Shuttling of HDAC5 in H9C2 cells regulates YY1 function through CaMKIV/PKD and PP2A. Am J Physiol Cell Physiol 2006; 291:C1029-37. [PMID: 16822951 DOI: 10.1152/ajpcell.00059.2006] [Citation(s) in RCA: 38] [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
YY1 is a transcription factor that can activate or repress transcription of a variety of genes and is involved in several developmental processes. YY1 is a repressor of transcription in differentiated H9C2 cells and in neonatal cardiac myocytes but an activator of transcription in undifferentiated H9C2 cells. We now present a detailed analysis of the functional domains of YY1 when it is acting as a repressor or an activator and identify the mechanism whereby its function is regulated in the differentiation of H9C2 cells. We show that histone deacetylase 5 (HDAC5) is localized to the cytoplasm in undifferentiated H9C2 cells and that this localization is dependent on Ca(2+)/calmodulin-dependent kinase IV (CaMKIV) and/or protein kinase D (PKD). In differentiated cells, HDAC5 is nuclear and interacts with YY1. Finally, we show that HDAC5 localization in differentiated cells is dependent on phosphatase 2A (PP2A). Our results suggest that a signaling mechanism that involves CaMKIV/PKD and PP2A controls YY1 function through regulation of HDAC5 and is important in the maintenance of muscle differentiation.
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Affiliation(s)
- Carmen C Sucharov
- Division of Cardiology, School of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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123
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Leung GPH, Tse CM, Man RYK. Characterization of adenosine transport in H9c2 cardiomyoblasts. Int J Cardiol 2006; 116:186-93. [PMID: 16824629 DOI: 10.1016/j.ijcard.2006.03.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2005] [Revised: 03/20/2006] [Accepted: 03/25/2006] [Indexed: 11/20/2022]
Abstract
Adenosine plays a significant role in various physiological processes including cardioprotection. Nucleoside transporters modulate adenosine levels in the vicinity of adenosine receptors, which in turn modulate adenosine functional efficacy. In the current study, adenosine transport in the rat heart myoblast cell line H9c2 was characterized. Kinetic analysis of adenosine transport in H9c2 cells revealed a Km of 8.9+/-0.001 microM and a Vmax of 32.1+/-0.65 pmol/mg protein/min. Adenosine transport in H9c2 cells was Na+-independent. About 6% of the total adenosine uptake was sensitive to nitrobenzylmercaptopurine riboside (NBMPR); however, 94% was insensitive, suggesting that adenosine uptake by H9c2 cells was predominantly mediated by the equilibrative nucleoside transporter (ENT)-2 and only mildly by ENT-1. Results of RT-PCR demonstrated the presence of mRNA for ENT-1, ENT-2 and ENT-3. Upon culture in a cell differentiation medium containing fetal bovine serum (1%) and retinoic acid (10 nM), both the activity and mRNA expression of ENT-1 increased 3-fold, however, ENT-2 was unaffected. Pharmacological studies revealed that ENT-1 activity was stimulated by PKA and PKC-delta/epsilon, however, ENT-2 activity was unaffected. Taken together, the exceptionally high expression level of ENT-2 in H9c2 cells raises questions regarding the use of H9c2 cells as a model for physiological adenosine activity in the heart. Furthermore, this study may form the basis for further investigation into the effect of cell differentiation and protein kinases on the regulation of nucleoside transporters.
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Affiliation(s)
- George P H Leung
- Department of Pharmacology, The University of Hong Kong, Hong Kong.
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124
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Yokoyama U, Minamisawa S, Adachi-Akahane S, Akaike T, Naguro I, Funakoshi K, Iwamoto M, Nakagome M, Uemura N, Hori H, Yokota S, Ishikawa Y. Multiple transcripts of Ca2+ channel α1-subunits and a novel spliced variant of the α1C-subunit in rat ductus arteriosus. Am J Physiol Heart Circ Physiol 2006; 290:H1660-70. [PMID: 16272207 DOI: 10.1152/ajpheart.00100.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Voltage-dependent Ca2+ channels (VDCCs), which consist of multiple subtypes, regulate vascular tone in developing arterial smooth muscle, including the ductus arteriosus (DA). First, we examined the expression of VDCC subunits in the Wistar rat DA during development. Among α1-subunits, α1C and α1G were the most predominant isoforms. Maternal administration of vitamin A significantly increased α1C- and α1G-transcripts. Second, we examined the effect of VDCC subunits on proliferation of DA smooth muscle cells. We found that 1 μM nitrendipine (an L-type Ca2+ channel blocker) and kurtoxin (a T-type Ca2+ channel blocker) significantly decreased [3H]thymidine incorporation and that 3 μM efonidipine (an L- and T-type Ca2+ channel blocker) further decreased [3H]thymidine incorporation, suggesting that L- and T-type Ca2+ channels are involved in smooth muscle cell proliferation in the DA. Third, we found that a novel alternatively spliced variant of the α1C-isoform was highly expressed in the neointimal cushion of the DA, where proliferating and migrating smooth muscle cells are abundant. The basic channel properties of the spliced variant did not differ from those of the conventional α1C-subunit. We conclude that multiple VDCC subunits were identified in the DA, and, in particular, α1C- and α1G-subunits were predominant in the DA. A novel spliced variant of the α1C-subunit gene may play a distinct role in neointimal cushion formation in the DA.
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Affiliation(s)
- Utako Yokoyama
- Dept. of Pediatrics, Yokohama City University, Kanazawa-ku, Yokohama 236-0004, Japan
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125
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Bidaud I, Monteil A, Nargeot J, Lory P. Properties and role of voltage-dependent calcium channels during mouse skeletal muscle differentiation. J Muscle Res Cell Motil 2006; 27:75-81. [PMID: 16538437 DOI: 10.1007/s10974-006-9058-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 02/04/2006] [Indexed: 11/30/2022]
Abstract
Skeletal muscle differentiation depends on calcium ions, but it is yet unclear whether calcium entry through voltage-dependent calcium channels (VDCCs) contributes to the myoblast fusion process. In this study, we investigate whether calcium influx through functional T-type VDCCs precedes and affects mouse satellite cell fusion. We report here on the properties and the role of the VDCCs expressed in differentiating mouse muscular cells using both the C2C12 cell line and primary cultures of satellite cells. We present electrophysiological and biochemical evidence demonstrating that T-type and L-type VDCCs are not present in C2C12 and primary cultures of mouse satellite cells prior to the fusion stage. Although mRNA for the T-type Ca(V)3.2 subunit was detected in differentiated C2C12 cells, no T-type calcium currents could be recorded, while both T-type and L-type calcium currents were detected after the fusion process in primary cultures. In addition, chronic application of 30 microM nickel, known to inhibit T-type Ca(V)3.2 channels, did not alter the fusion of C2C12 cells and mouse satellite cells in primary culture. Overall, the data indicate that, unlike in humans, Ca(V)3.2 T-type calcium channels play no role in mouse satellite cell fusion.
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MESH Headings
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels/drug effects
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/drug effects
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Line
- Male
- Mice
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/cytology
- Muscle, Skeletal/metabolism
- Nickel/pharmacology
- Regeneration/physiology
- Satellite Cells, Skeletal Muscle/cytology
- Satellite Cells, Skeletal Muscle/drug effects
- Satellite Cells, Skeletal Muscle/metabolism
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Affiliation(s)
- Isabelle Bidaud
- Institut de Génomique Fonctionnelle, CNRS UMR5203, INSERM U661, Universités de Montpellier I & II, 141, rue de la Cardonille, 34094 Montpellier cedex 05, France
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126
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Borradaile NM, Buhman KK, Listenberger LL, Magee CJ, Morimoto ETA, Ory DS, Schaffer JE. A critical role for eukaryotic elongation factor 1A-1 in lipotoxic cell death. Mol Biol Cell 2006; 17:770-8. [PMID: 16319173 PMCID: PMC1356587 DOI: 10.1091/mbc.e05-08-0742] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Revised: 11/16/2005] [Accepted: 11/18/2005] [Indexed: 02/06/2023] Open
Abstract
The deleterious consequences of fatty acid (FA) and neutral lipid accumulation in nonadipose tissues, such as the heart, contribute to the pathogenesis of type 2 diabetes. To elucidate mechanisms of FA-induced cell death, or lipotoxicity, we generated Chinese hamster ovary (CHO) cell mutants resistant to palmitate-induced death and isolated a clone with disruption of eukaryotic elongation factor (eEF) 1A-1. eEF1A-1 involvement in lipotoxicity was confirmed in H9c2 cardiomyoblasts, in which small interfering RNA-mediated knockdown also conferred palmitate resistance. In wild-type CHO and H9c2 cells, palmitate increased reactive oxygen species and induced endoplasmic reticulum (ER) stress, changes accompanied by increased eEF1A-1 expression. Disruption of eEF1A-1 expression rendered these cells resistant to hydrogen peroxide- and ER stress-induced death, indicating that eEF1A-1 plays a critical role in the cell death response to these stressors downstream of lipid overload. Disruption of eEF1A-1 also resulted in actin cytoskeleton defects under basal conditions and in response to palmitate, suggesting that eEF1A-1 mediates lipotoxic cell death, secondary to oxidative and ER stress, by regulating cytoskeletal changes critical for this process. Furthermore, our observations of oxidative stress, ER stress, and induction of eEF1A-1 expression in a mouse model of lipotoxic cardiomyopathy implicate this cellular response in the pathophysiology of metabolic disease.
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Affiliation(s)
- Nica M Borradaile
- Center for Cardiovascular Research, Division of Cardiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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127
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Montessuit C, Papageorgiou I, Campos L, Lerch R. Retinoic acids increase expression of GLUT4 in dedifferentiated and hypertrophied cardiac myocytes. Basic Res Cardiol 2005; 101:27-35. [PMID: 16273324 DOI: 10.1007/s00395-005-0567-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 09/12/2005] [Accepted: 10/04/2005] [Indexed: 01/14/2023]
Abstract
Sufficient expression of the insulin-sensitive glucose transporter GLUT4 may be crucial for the survival of cardiac myocytes in situations of stress. Expression of GLUT4 in cardiac myocytes correlates with cell differentiation and is reduced in the hypertrophied and failing myocardium. Adult rat cardiomyocytes (ARC) in primary culture undergo dedifferentiation and reduction of GLUT4 expression. Depending on the culture condition partial redifferentiation and/or hypertrophy follows. All-trans (at) and 9-cis retinoic acids (RA) are morphogenetic agents important for cell differentiation. Both atRA and 9-cisRA restored GLUT4 expression in dedifferentiated ARC, while only 9-cisRA could increase GLUT4 expression in hypertrophic ARC. The effects of RA were associated with improved differentiation of the cardiac myocytes, as assessed from the expression of atrial natriuretic factor and the morphology of the contractile apparatus. In neonatal rat cardiomyocytes, 9-cisRA, but not atRA, stimulated transcription from the glut4 promoter. In conclusion, treatment with RA can restore the down-regulated expression of GLUT4 in cardiomyocytes in association with a partial improvement of the differentiated phenotype.
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Affiliation(s)
- Christophe Montessuit
- Division of Cardiology, Department of Internal Medicine, Geneva University Hospitals, 24 Micheli-du-Crest, 1211, Geneva 14, Switzerland.
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128
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Liou JC, Ho SY, Shen MR, Liao YP, Chiu WT, Kang KH. A rapid, nongenomic pathway facilitates the synaptic transmission induced by retinoic acid at the developing synapse. J Cell Sci 2005; 118:4721-30. [PMID: 16188934 DOI: 10.1242/jcs.02603] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We have previously shown that retinoic acid (RA), a factor highly expressed in spinal cord, rapidly and specifically enhances the spontaneous acetylcholine release at developing neuromuscular synapses in Xenopus cell culture, using whole-cell patch-clamp recording. We have now further investigated the underlying mechanisms that are involved in RA-induced facilitation on the frequency of spontaneous synaptic currents (SSCs). Buffering the rise of intracellular Ca2+ with BAPTA-AM hampered the facilitation of SSC frequency induced by RA. The prompt RA-enhanced SSC frequency was not abolished when Ca2+ was eliminated from the culture medium or there was bath application of the pharmacological Ca2+ channel inhibitor Cd2+, indicating that Ca2+ influx through voltage-activated Ca2+ channels are not required. Application of membrane-permeable inhibitors of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] or ryanodine receptors effectively blocked the increase of SSC frequency elicited by RA. Treating cells with either wortmannin or LY294002, two structurally different inhibitors of phosphatidylinositol 3-kinase (PI 3-kinase) and with the phospholipase Cgamma (PLCgamma) inhibitor U73122, abolished RA-induced facilitation of synaptic transmission. Preincubation of the cultures with pharmacological inhibitors, either genistein, a broad-spectrum tyrosine kinase inhibitor, or PP2, which predominantly inhibits the Src family of nonreceptor tyrosine kinase, completely abolished RA-induced synaptic facilitation. Taken collectively, these results suggest that RA elicits Ca2+ release from Ins1,4,5P3 and/or ryanodine-sensitive intracellular Ca2+ stores of the presynaptic nerve terminal. This is done via PLCgamma/PI 3-kinase signaling cascades and Src tyrosine kinase activation, leading to an enhancement of spontaneous transmitter release.
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Affiliation(s)
- Jau-Cheng Liou
- Department of Biological Sciences, National Sun Yat-sen University, No. 70, Lein-Hai Rd., Kaohsiung City, 804, Taiwan
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129
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Selmin O, Thorne PA, Caldwell PT, Johnson PD, Runyan RB. Effects of trichloroethylene and its metabolite trichloroacetic acid on the expression of vimentin in the rat H9c2 cell line. Cell Biol Toxicol 2005; 21:83-95. [PMID: 16142583 DOI: 10.1007/s10565-005-0124-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Accepted: 05/03/2005] [Indexed: 12/21/2022]
Abstract
Trichloroethylene (TCE) and its metabolite trichloroacetic acid (TCAA) are environmental contaminants with specific toxicity for the embryonic heart. In an effort to identify the cellular pathways disrupted by TCE and TCAA during heart development, we investigated their effects on expression of vimentin, a marker of cardiac differentiation. Previous studies had shown that the level of vimentin transcript was inhibited in rat embryonic heart after maternal exposure to TCE via drinking water. In the same study, maternal exposure to TCAA produced the opposite effect, inducing an increased level of vimentin mRNA. In this study, we selected an in vitro system, the rat cardiac myoblast cell line H9c2, to further characterize the molecular mechanisms used by TCE and TCAA to disrupt normal heart development. In particular, we investigated the effects of both toxicants on vimentin, at both the RNA and protein levels, using dose-response and time course curves. Our experimental findings indicate that vimentin expression is affected by TCE and TCAA in H9c2 cells similarly as in vivo. The work is significant because it provides a suitable in vitro model for studies looking at toxicant effects on myocardiac cells, and it suggests that vimentin is a good marker of TCE exposure in the embryonic heart.
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Affiliation(s)
- O Selmin
- Department of Veterinary Sciences and Microbiology, University of Arizona, Tucson, Arizona 85721-0090, USA.
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130
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Giusti L, Gargini C, Ceccarelli F, Bacci M, Italiani P, Mazzoni MR. Modulation of Endothelin-A Receptor, Gα Subunit, and RGS2 Expression during H9c2 Cardiomyoblast Differentiation. J Recept Signal Transduct Res 2004; 24:297-317. [PMID: 15648448 DOI: 10.1081/rrs-200040331] [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: 01/08/2023]
Abstract
In cardiac myocytes, growth responses depend on activation of G protein-coupled receptors interacting with Gq/11 protein subfamily members. Endothelin receptors of the ETA subtype belong to this receptor group inducing hypertrophic responses. To understand the role of ETA receptors and signal transduction proteins in modulating cell growth, we analyzed the pharmacological profile of this receptor, its level of expression together with those of Galpha subunits and the RGS2 protein in cardiomyoblasts differentiating into the cardiac phenotype. H9c2 rat cardiomyoblasts were grown in the presence of 10% fetal bovine serum (FBS) or 1% FBS plus all-trans-retinoic acid to induce the cardiac phenotype. The pharmacological properties of ETA receptors were investigated by competition-binding experiments, whereas the protein expression profile was analyzed by immunoblot and immunocytochemistry. The pharmacological profile of ETA receptors changed during differentiation of cardiomyoblasts into cardiomyocytes, and the amount of expressed receptor appeared to increase. Immunocytochemistry also showed a marked increase of receptor expression on cell membranes of differentiated cardiomyocytes. Among the other signaling proteins examined, both Galphaq/11 and RGS2 expression decreased in cells with the cardiac phenotype. Our results demonstrate that the expression of key proteins (ETA receptor, Galphaq/11, and RGS2) involved in signal transduction of hypertrophic stimuli is modulated during cell differentiation and correlates with the cardiac phenotype.
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Affiliation(s)
- Laura Giusti
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Pisa, Italy
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131
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Granata R, Trovato L, Destefanis S, Settanni F, Ghigo E. H9c2 cardiac muscle cells express all somatostatin receptor subtypes. J Endocrinol Invest 2004; 27:RC24-7. [PMID: 15648542 DOI: 10.1007/bf03346272] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The aim of the present study was to verify the hypothesis that SS receptor subtypes (SSTRs) are expressed by H9c2 cardiac muscle cells. SSTRs expression was investigated by RT-PCR and Western blot analysis at both mRNA and protein level. Our findings demonstrate that H9c2 cells express all SSTR subtypes I-5 (SSTRI-5) at the mRNA and protein level. Thus, H9c2 cells would represent a new model to study the direct biological activities of SS and its analogues at the cardiac level.
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Affiliation(s)
- R Granata
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, Turin, Italy
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132
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Ianoul A, Street M, Grant D, Pezacki J, Taylor RS, Johnston LJ. Near-field scanning fluorescence microscopy study of ion channel clusters in cardiac myocyte membranes. Biophys J 2004; 87:3525-35. [PMID: 15339803 PMCID: PMC1304818 DOI: 10.1529/biophysj.104.046383] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Near-field scanning optical microscopy (NSOM) has been used to study the nanoscale distribution of voltage-gated L-type Ca2+ ion channels, which play an important role in cardiac function. NSOM fluorescence imaging of immunostained cardiac myocytes (H9C2 cells) demonstrates that the ion channel is localized in small clusters with an average diameter of 100 nm. The clusters are randomly distributed throughout the cell membrane, with some larger fluorescent patches that high-resolution images show to consist of many small closely-spaced clusters. We have imaged unstained cells to assess the contribution of topography-induced artifacts and find that the topography-induced signal is <10% of the NSOM fluorescence intensity. We have also examined the dependence of the NSOM signal intensity on the tip-sample separation to assess the contributions from fluorophores that are significantly below the cell surface. This indicates that chromophores > approximately 200 nm below the probe will have negligible contributions to the observed signal. The ability to quantitatively measure small clusters of ion channels will facilitate future studies that examine changes in protein localization in stimulated cells and during cardiac development. Our work illustrates the potential of NSOM for studying membrane domains and protein localization/colocalization on a length scale which exceeds that available with optical microscopy.
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Affiliation(s)
- Anatoli Ianoul
- Steacie Institute for Molecular Sciences and Institute for Microstructural Sciences, National Research Council Canada, Ottawa, Ontario, Canada
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133
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Evig CB, Kelley EE, Weydert CJ, Chu Y, Buettner GR, Burns CP. Endogenous production and exogenous exposure to nitric oxide augment doxorubicin cytotoxicity for breast cancer cells but not cardiac myoblasts. Nitric Oxide 2004; 10:119-29. [PMID: 15158691 DOI: 10.1016/j.niox.2004.03.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 03/23/2004] [Indexed: 11/24/2022]
Abstract
We studied the effect of nitric oxide (*NO) on the anticancer activity of doxorubicin. When MCF-7 human breast cancer cells were exposed to an aqueous solution of *NO delivered as a bolus 30 min prior to doxorubicin, the cytotoxic effect as measured in a clonogenic assay was increased (doxorubicin alone, 40% survival, doxorubicin plus *NO, 5% survival). The *NO donor diethylamine nitric oxide, but not inactivated donor, also yielded an increase in doxorubicin cytotoxicity. The sequence was important since the simultaneous application of *NO with doxorubicin yielded only a small augmentation of effect, and the exposure of the cells to doxorubicin prior to the *NO obliterated the augmentation. Prior depletion of glutathione by incubation of the cells for 24h with D,L-buthionine-S,R-sulfoximine (BSO) further increased the cytotoxicity so that BSO plus *NO plus doxorubicin killed all of the clones. MCF-7 cells transduced with inducible nitric oxide synthase gene (iNOS) through an adenoviral vector overexpressed iNOS and produced increased amounts of nitrite, an indicator of increased *NO production. These iNOS transduced cells were more susceptible to doxorubicin than vector control or wild-type cells. Cell cycle progression of iNOS transduced cells was not different from controls. Likewise, iNOS transduction resulted in no change in cellular glutathione levels. For comparison, we examined the effect of iNOS transduction on the sensitivity of MCF-7 to edelfosine, a membrane-localizing anticancer drug without direct DNA interaction. Insertion of the iNOS had no effect on killing of the MCF-7 cells by this ether lipid class drug. We also tested the effect of iNOS transduction on doxorubicin sensitivity of H9c2 rat heart-derived myoblasts. We found no augmentation of cytotoxicity by *NO, and this observation offers potential therapeutic tumor selectivity by using *NO with doxorubicin. Therefore, we conclude that *NO produced intracellularly by iNOS overexpression or delivered as a bolus sensitizes human breast cancer cells in culture to doxorubicin, but not to a cardiac cell line or to edelfosine. This augmentation is not due to a modulation of cell cycle distribution or measurable cellular glutathione resulting from the transduction.
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Affiliation(s)
- Crystal B Evig
- Department of Medicine, The University of Iowa Carver College of Medicine and The University of Iowa Holden Comprehensive Cancer Center, Iowa City, IA 52242, USA
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134
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Cohen N, Rimessi P, Gualandi F, Ferlini A, Muntoni F. In vivo study of an aberrant dystrophin exon inclusion in X-linked dilated cardiomyopathy. Biochem Biophys Res Commun 2004; 317:1215-20. [PMID: 15094399 DOI: 10.1016/j.bbrc.2004.03.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Indexed: 11/20/2022]
Abstract
We previously identified a dystrophin intron 11 rearrangement in one family with X-linked dilated cardiomyopathy, causing incorporation of an aberrant exon in a tissue-specific manner. In this study we analyzed the role of different intron 11 genomic regions in the regulation of splicing by using mini-genes based approach, in C2C12 (skeletal muscle) myoblasts and myotubes, H9C2 cardiomyocytes, and HeLa cells. We show that inclusion of the aberrant exon is favored in H9C2 and differentiated C2C12 myotubes. These data suggest that the aberrant exon undergoes a differentiation-specific splicing. Unexpectedly, length of intron has a favorable effect in inclusion of the aberrant exon in the cardiac cells, suggesting that cardiac cells might be more prone to steric hindrance of trans-acting factors, involved in the inclusion of the aberrant exon. Furthermore, the cultured cell system used can serve as a suitable model to study human alternative splicing.
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Affiliation(s)
- Niaz Cohen
- Dubowitz Neuromuscular Unit, Department of Paediatrics, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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135
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Pagano M, Naviglio S, Spina A, Chiosi E, Castoria G, Romano M, Sorrentino A, Illiano F, Illiano G. Differentiation of H9c2 cardiomyoblasts: The role of adenylate cyclase system. J Cell Physiol 2004; 198:408-16. [PMID: 14755546 DOI: 10.1002/jcp.10420] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The adenylate cyclase (AC)/cAMP/cAMP-dependent protein kinase pathway controls many biological phenomena. The molecular mechanisms by which cAMP induces alternative commitment towards differentiation or proliferation are not still completely known. The differentiation of myoblast cell lines into myocytes/myotubes represents a well-established model of skeletal muscle differentiation. We analyzed the AC/cAMP pathway during terminal differentiation of H9c2 myoblasts. When cultured in low-serum containing medium, H9c2 myoblasts exit the cell cycle and differentiate into myocytes/myotubes. A key step of this process is the expression of myogenin, an essential transcription factor for the terminal differentiation into myocytes. During this phenomenon we observed a decrease in both cAMP levels and AC activity, which suggests a functional negative role of cAMP on the differentiation process of H9c2 cells. 8-Br-cAMP and other cAMP-elevating agents, such as forskolin, IBMX, and isoproterenol, negatively affected skeletal muscle differentiation of H9c2 myoblasts. Both AC activity down-regulation and intracellular cAMP reduction were accompanied by significant variations in the levels of membrane proteins belonging to the AC system (AC catalytic subunit, G(alphai-1), G(alphas)). The functional relationship between intracellular cAMP content and protein levels of AC system is discussed.
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Affiliation(s)
- M Pagano
- Department of Biochemistry and Biophysics "F. Cedrangolo", School of Medicine, Second University of Naples, Naples, Italy
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136
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Granata R, De Petrini M, Trovato L, Ponti R, Pons N, Ghè C, Graziani A, Ferry RJ, Muccioli G, Ghigo E. Insulin-like growth factor binding protein-3 mediates serum starvation- and doxorubicin-induced apoptosis in H9c2 cardiac cells. J Endocrinol Invest 2003; 26:1231-41. [PMID: 15055478 DOI: 10.1007/bf03349163] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Insulin-like growth factor binding protein 3 (IGFBP-3) modulates the activity of IGF-I, which exerts antiapoptotic action upon the myocardiocyte. IGFBP-3 also exerts IGF-independent actions to inhibit cell growth and induce apoptosis, mediating the effects of several antiproliferative agents. We hypothesized that IGFBP-3 mediates cardiomyocyte apoptosis. IGFBP-3 expression was studied in H9c2 rat cardiac cells cultured in serum-deprived medium in the absence or presence of 1 microM doxorubicin during a 72 h time-span. To a greater degree than serum withdrawal, doxorubicin induced IGFBP-3 up-regulation that was time-dependent. IGFBP-3 mRNA levels positively correlated with the degree of apoptosis. Exogenous IGFBP-3 decreased cell viability and induced apoptosis in serum-starved cells exposed to doxorubicin. IGFBP-3 antisense oligonucleotides markedly decreased apoptosis induced by either serum withdrawal or doxorubicin. Binding studies revealed specific high-affinity sites for IGFBP-3 in H9c2 cardiomyocytes, with binding characteristics typical of receptor-ligand interactions. These findings indicate that IGFBP-3 could play proapoptotic action at the myocardial level and suggest a novel role for this protein in cardiovascular dysfunction.
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Affiliation(s)
- R Granata
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, Turin, Italy
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137
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Xu M, Welling A, Paparisto S, Hofmann F, Klugbauer N. Enhanced expression of L-type Cav1.3 calcium channels in murine embryonic hearts from Cav1.2-deficient mice. J Biol Chem 2003; 278:40837-41. [PMID: 12900400 DOI: 10.1074/jbc.m307598200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated calcium (Ca2+) channels play a key role in the control of heart contraction and are essential for normal heart development. The Cav1.2 L-type calcium channel is the predominant isoform in cardiomyocytes and is essential for excitation-contraction coupling. Although the inactivation of the Cav1.2 gene caused embryonic lethality before embryonic day E14.5, hearts were contracting before E14 depending on a dihydropyridine-sensitive calcium influx. We analyzed the consequences of the deletion of the Cav1.2 channel on the expression level of other voltage-gated calcium channels in the embryonic mouse heart and isolated cardiomyocytes. A strong compensatory up-regulation of the Cav1.3 calcium channel was observed on the mRNA as well as on the protein level. Reverse transcriptase PCR indicated that the recently identified new Cav1.3(1b) isoform was strongly up-regulated, whereas a more moderate increase was found for the Cav1.3(1a) variant. Heterologous expression of Cav1.3(1b) in HEK293 cells induced Ba2+ currents with properties similar to those found in Cav1.2 (-/-) cardiomyocytes, suggesting that this isoform constitutes a major component of the residual L-type calcium current in Cav1.2 (-/-) cardiomyocytes. In summary, our results imply that calcium channel expression is dynamically regulated during heart development and that the Cav1.3 channel may substitute for Cav1.2 during early embryogenesis.
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Affiliation(s)
- Man Xu
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Strasse 29, 80802 München, Germany
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138
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Sucharov CC, Mariner P, Long C, Bristow M, Leinwand L. Yin Yang 1 is increased in human heart failure and represses the activity of the human alpha-myosin heavy chain promoter. J Biol Chem 2003; 278:31233-9. [PMID: 12754214 DOI: 10.1074/jbc.m301917200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yin Yang 1 (YY1) is a transcription factor that can repress or activate transcription of the genes with which it interacts. In this report we show that YY1 is a negative regulator of the alpha-myosin heavy chain (alphaMyHC) gene, which, with betaMyHC are the molecular motors of the heart. AlphaMyHC mRNA and protein levels are down-regulated in hypertrophy and heart failure, and this is thought to be detrimental for cardiac contractility. We show that YY1 specifically interacts with the alphaMyHC promoter and that overexpression of YY1 in cardiac cells represses the activity of the alphaMyHC promoter. We also show that the 170-200-amino acid region of YY1, important for its interaction with histone acetyl transferases and histone deacetylases, is important for its repressive activity and that YY1 deleted in this region is an activator of the alphaMyHC promoter. Moreover, we show that YY1 levels and DNA binding activity are increased in failing human left ventricles and in a mouse model of hypertrophic cardiomyopathy, where alphaMyHC levels are decreased. These results suggest that YY1 is a negative regulator of alphaMyHC gene expression.
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Affiliation(s)
- Carmen C Sucharov
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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139
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Ceccarelli F, Scavuzzo MC, Giusti L, Bigini G, Costa B, Carnicelli V, Zucchi R, Lucacchini A, Mazzoni MR. ETA receptor-mediated Ca2+ mobilisation in H9c2 cardiac cells. Biochem Pharmacol 2003; 65:783-93. [PMID: 12628492 DOI: 10.1016/s0006-2952(02)01624-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Expression and pharmacological properties of endothelin receptors (ETRs) were investigated in H9c2 cardiomyoblasts. The mechanism of receptor-mediated modulation of intracellular Ca(2+) concentration ([Ca(2+)](i)) was examined by measuring fluorescence increase of Fluo-3-loaded cells with flow cytometry. Binding assays showed that [125I]endothelin-1 (ET-1) bound to a single class of high affinity binding sites in cardiomyoblast membranes. Endothelin-3 (ET-3) displaced bound [125I]ET-1 in a biphasic manner, in contrast to an ET(B)-selective agonist, IRL-1620, that was ineffective. The ET(B)-selective antagonist, BQ-788, inhibited [125I]ET-1 binding in a monophasic manner and with low potency. An ET(A)-selective antagonist, BQ-123, competed [125I]ET-1 binding in a monophasic manner. This antagonist was found to be 13-fold more potent than BQ-788. Immunoblotting analysis using anti-ET(A) and -ET(B) antibodies confirmed a predominant expression of the ET(A) receptor. ET-1 induced a concentration-dependent increase of Fluo-3 fluorescence in cardiomyoblasts resuspended in buffer containing 1mM CaCl(2). Treatment of cells with antagonists, PD-145065 and BQ-123, or a phospholipase C-beta inhibitor, U-73122, abolished ET-1-mediated increases in fluorescence. The close structural analogue of U-73122, U-73343, caused a minimal effect on the concentration-response curve of ET-1. ET-3 produced no major increase of Fluo-3 fluorescence. Removal of extracellular Ca(2+) resulted in a shift to the right of the ET-1 concentration-response curve. Both the L-type voltage-operated Ca(2+) channel blocker, nifedipine, and the ryanodine receptor inhibitor, dantrolene, reduced the efficacy of ET-1. Two protein kinase C inhibitors reduced both potency and efficacy of ET-1. Our results demonstrate that ET(A) receptors are expressed and functionally coupled to rise of [Ca(2+)](i) in H9c2 cardiomyoblasts. ET-1-induced [Ca(2+)](i) increase is triggered by Ca(2+) release from intracellular inositol 1,4,5-trisphosphate-gated stores; plasma membrane Ca(2+) channels and ryanodine receptors participate in sustaining the Ca(2+) response. Regulation of channel opening by protein kinase C is also involved in the process of [Ca(2+)](i) increase.
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Affiliation(s)
- Francesca Ceccarelli
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Italy
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140
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Ranki HJ, Budas GR, Crawford RM, Davies AM, Jovanović A. 17Beta-estradiol regulates expression of K(ATP) channels in heart-derived H9c2 cells. J Am Coll Cardiol 2002; 40:367-74. [PMID: 12106946 DOI: 10.1016/s0735-1097(02)01947-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The main objective of the present study was to establish whether 17beta-estradiol (E2) regulates expression of cardiac adenosine triphosphate-sensitive potassium (K(ATP)) channel. BACKGROUND Based on our previous studies that demonstrate gender-specific differences in sarcolemmal K(ATP) channels, we have hypothesized that the main estrogen, E2, may regulate expression of cardiac K(ATP) channels. METHODS Reverse transcription-polymerase chain reaction (RT-PCR) using primers specific for Kir6.2 and sulfonylurea receptor 2A (SUR2A) subunits was performed on total ribonucleic acid (RNA) from rat embryonic heart-derived H9c2 cells. Immunoprecipitation and Western blotting using anti-Kir6.2 and anti-SUR2A antibodies was done on membrane fraction of H9c2 cells. Whole cell electrophysiology and digital epifluorescent Ca(2+) imaging were performed on living H9c2 cells. All experiments were done in cells incubated 24 h with or without 100 nM E2. RESULTS The RT-PCR revealed higher levels of SUR2A, but not Kir6.2, messenger RNA (mRNA) in E2-treated, relative to untreated, cells. Increase of the level of only the SUR2A subunit could change the number of sarcolemmal K(ATP) channels only if the Kir6.2 is in excess over SUR2A. Indeed, RT-PCR analysis demonstrated considerably lower levels of SUR2A mRNA compared with Kir6.2 mRNA. Significantly higher levels of both Kir6.2 and SUR2A protein subunits were found in the membrane fraction of E2-treated cells compared with untreated ones, and the density of current evoked by pinacidil (100 microM), a K(ATP) channel opener, was significantly higher in E2-treated compared with untreated cells. To test the effect of E2 on cellular response to hypoxia-reoxygenation, we have measured on-line, intracellular concentration of Ca(2+) in H9c2 cells exposed to hypoxia-reoxygenation. Intracellular Ca(2+) loading induced by hypoxia-reoxygenation was significantly decreased by treatment with E2. This E2-mediated protection was inhibited by HMR 1098 (30 microM), but not by 5-hydroxydecanoate (50 microM). CONCLUSIONS In conclusion, this study has demonstrated that E2 increases levels of SUR2A subunit, stimulates K(ATP) channel formation and protects cardiac cells from hypoxiareoxygenation.
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Affiliation(s)
- Harri J Ranki
- Tayside Institute of Child Health, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY Scotland, UK
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141
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Peng X, Li Y. Induction of cellular glutathione-linked enzymes and catalase by the unique chemoprotective agent, 3H-1,2-dithiole-3-thione in rat cardiomyocytes affords protection against oxidative cell injury. Pharmacol Res 2002; 45:491-7. [PMID: 12162951 DOI: 10.1006/phrs.2002.0991] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Considerable evidence suggests that reactive oxygen species (ROS) are crucially involved in the pathogenesis of cardiovascular diseases, such as myocardial ischemia-reperfusion injury. Consistent with this notion, administration of exogenous antioxidative compounds has been shown to provide protection against oxidative cardiac injury. However, whether induction of endogenous cellular antioxidants by chemicals (drugs) also offers protection against oxidative cardiac injury has not been extensively investigated. In the present study, with rat cardiomyocyte H9C2 cells as an in vitro model, we have investigated the induction of cellular antioxidants by the unique chemoprotective agent, 3 H -1,2-dithiole-3-thione (D3T) and the protective effects of the D3T-induced cellular antioxidants against ROS-mediated injury in cardiac cells. Incubation of H9C2 cells with micromolar concentrations of D3T for 24 h resulted in a significant induction of a battery of cellular antioxidants, including reduced glutathione (GSH), GSH peroxidase, GSSG reductase, GSH S-transferase and catalase. To further examine the protective effects of the induced endogenous antioxidants against oxidative cell injury, H9C2 cells were pre-treated with D3T and then incubated with xanthine oxidase (XO) plus xanthine, a system that generates ROS. We observed that D3T pre-treatment of H9C2 cells led to significant protection against XO/xanthine-induced cytotoxicity as determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) reduction and morphological changes. Taken together, this study demonstrates for the first time that a number of endogenous antioxidants in cardiomyocytes can be induced by exposure to D3T, and that this chemical (drug) induction of cellular antioxidants is accompanied by markedly increased resistance to ROS-mediated cardiac cell injury.
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Affiliation(s)
- Xingxiang Peng
- Department of Pharmaceutical Sciences, St John's University College of Pharmacy and Allied Health Professions, 8000 Utopia Parkway, Jamaica, NY 11439, USA
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142
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Kageyama K, Ihara Y, Goto S, Urata Y, Toda G, Yano K, Kondo T. Overexpression of calreticulin modulates protein kinase B/Akt signaling to promote apoptosis during cardiac differentiation of cardiomyoblast H9c2 cells. J Biol Chem 2002; 277:19255-64. [PMID: 11907032 DOI: 10.1074/jbc.m112377200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is a Ca(2+)-binding molecular chaperone of the lumen of the endoplasmic reticulum. Calreticulin has been shown to be essential for cardiac and neural development in mice, but the mechanism by which it functions in cell differentiation is not fully understood. To examine the role of calreticulin in cardiac differentiation, the calreticulin gene was introduced into rat cardiomyoblast H9c2 cells, and the effect of calreticulin overexpression on cardiac differentiation was examined. Upon culture in a differentiation medium containing fetal calf serum (1%) and retinoic acid (10 nm), cells transfected with the calreticulin gene were highly susceptible to apoptosis compared with controls. In the gene-transfected cells, protein kinase B/Akt signaling was significantly suppressed during differentiation. Furthermore, protein phosphatase 2A, a Ser/Thr protein phosphatase, was significantly up-regulated, implying suppression of Akt signaling due to dephosphorylation of Akt by the up-regulated protein phosphatase 2A via regulation of Ca(2+) homeostasis. Thus, overexpression of calreticulin promotes differentiation-dependent apoptosis in H9c2 cells by suppressing the Akt signaling pathway. These findings indicate a novel mechanism by which cytoplasmic Akt signaling is modulated to cause apoptosis by a resident protein of the endoplasmic reticulum, calreticulin.
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Affiliation(s)
- Kan Kageyama
- Department of Biochemistry and Molecular Biology in Disease, Atomic Bomb Disease Institute, Nagasaki 852-8523, Japan
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143
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Wang HJ, Zhu YC, Yao T. Effects of all-trans retinoic acid on angiotensin II-induced myocyte hypertrophy. J Appl Physiol (1985) 2002; 92:2162-8. [PMID: 11960970 DOI: 10.1152/japplphysiol.01192.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used cultured neonatal rat cardiac myocytes to test the hypothesis that all-trans retinoic acid (atRA) may act to modulate ANG II actions in inducing myocyte hypertrophy. Our observations were as follows. 1) atRA (10(-7) to approximately 10(-5) M ) inhibited ANG II-induced hyperplasia of fibroblasts in a dose-dependent manner. 2) Treatment of atRA attenuated the ANG II-induced increase in total cell protein content. 3) Treated with ANG II (10(-7) M) for 5 days, the cultured neonatal rat cardiac myocytes demonstrated an apparent accumulation of sarcomeric fiber proteins and Golgi's complex, as well as reorganization of the sarcomeric unit within individual myocytes. atRA (10(-6) M) treatment reduced the accumulation of contractile proteins and Golgi's complex without affecting the ANG II-induced reorganization of the sarcomeric unit. 4) atRA attenuated the ANG II-induced increase in intracellular Ca2+. Our results show that atRA inhibits some effects of ANG II on neonatal rat cardiac myocytes and suggest that atRA may be a therapeutic candidate for the prevention and therapy of cardiac hypertrophy and remodeling.
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Affiliation(s)
- Hao-Jie Wang
- Kidney and Hypertension Research Center, Department of Physiology, Medical Center of Fudan University, Shanghai 200032, People's Republic of China
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144
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L'Ecuyer T, Horenstein MS, Thomas R, Vander Heide R. Anthracycline-induced cardiac injury using a cardiac cell line: potential for gene therapy studies. Mol Genet Metab 2001; 74:370-9. [PMID: 11708868 DOI: 10.1006/mgme.2001.3243] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anthracyclines are effective antitumor agents whose chief limitation has been cardiotoxicity directly related to free radical production. Therefore, strategies designed to selectively overexpress antioxidant proteins in the heart could protect against drug-induced toxicity and allow higher doses of chemotherapy. However, to date an adequate cardiac model system that is susceptible to anthracycline injury and can express foreign genes in a controlled fashion has been lacking. Developing a cardiac model system would permit examination of the relationship between the expression level of a potentially protective foreign gene and the degree of protection from injury. In this study we have examined the potential of the H9C2 rat cardiac myocyte cell line in this regard. H9C2 cells differentiate in a reproducible fashion, as shown by progressive increases in muscle tropomyosin-expressing cells, the organization of this thin filament protein, and the percentage of muscle cells contained within myotubes. Exposure of this cell line to the anthracycline doxorubicin produces cell injury as indicated by release of the intracellular enzyme lactate dehydrogenase into the culture medium. This injury is preceded by generation of reactive oxygen species, indicated by fluorescence after loading with carboxy-dichlorodihydrofluorescein diacetate. Stable transfection of H9C2 cells with a plasmid producing a tetracycline transactivator protein allows foreign genes to be expressed at a level tightly controlled by the concentration of tetracycline in the culture medium. Since H9C2 cells differentiate, can be injured by anthracycline exposure, and can express foreign genes at controllable levels, this is a suitable system in which to design genetic approaches to prevent this important clinical problem.
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Affiliation(s)
- T L'Ecuyer
- Department of Pediatrics, Wayne State University College of Medicine, Detroit, MI, USA.
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145
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van den Eijnde SM, van den Hoff MJ, Reutelingsperger CP, van Heerde WL, Henfling ME, Vermeij-Keers C, Schutte B, Borgers M, Ramaekers FC. Transient expression of phosphatidylserine at cell-cell contact areas is required for myotube formation. J Cell Sci 2001; 114:3631-42. [PMID: 11707515 DOI: 10.1242/jcs.114.20.3631] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell surface exposure of phosphatidylserine (PS) is shown to be part of normal physiology of skeletal muscle development and to mediate myotube formation. A transient exposure of PS was observed on mouse embryonic myotubes at E13, at a stage of development when primary myotubes are formed. The study of this process in cell cultures of differentiating C2C12 and H9C2 myoblasts also reveals a transient expression of PS at the cell surface. This exposure of PS locates mainly at cell-cell contact areas and takes place at a stage when the structural organization of the sarcomeric protein titin is initiated, prior to actual fusion of individual myoblast into multinucleated myotubes. Myotube formation in vitro can be inhibited by the PS binding protein annexin V, in contrast to its mutant M1234, which lacks the ability to bind to PS. Although apoptotic myoblasts also expose PS, differentiating muscle cells show neither loss of mitochondrial membrane potential nor detectable levels of active caspase-3 protein. Moreover, myotube formation and exposure of PS cannot be blocked by the caspase inhibitor zVAD(OMe)-fmk. Our findings indicate that different mechanisms regulate PS exposure during apoptosis and muscle cell differentiation, and that surface exposed PS plays a crucial role in the process of myotube formation.
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Affiliation(s)
- S M van den Eijnde
- Department of Molecular Cell Biology, Cardiovascular Research Institute Maastricht, University of Maastricht, PO Box 616, 6200 MD Maastricht, The Netherlands.
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146
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Abstract
Building a vertebrate heart is a complex task and involves several tissues, including the myocardium, endocardium, neural crest, and epicardium. Interactions between these tissues result in the changes in function and morphology (and also in the extracellular matrix, which serves as a substrate for morphological change) that are requisite for development of the heart. Some of the signaling pathways that mediate these changes have now been identified and several investigators are now filling in the missing pieces in these pathways in hopes of ultimately understanding the molecular mechanisms that govern healthy heart development. In addition, transcription factors that regulate various aspects of heart development have been identified. Transcription factors of the GATA and Nkx2 families are of particular importance for early specification of the heart field and for regulating expression of genes that encode proteins of the contractile apparatus. This chapter highlights some of the most significant discoveries made in the rapidly expanding field of heart development.
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Affiliation(s)
- M J Farrell
- Developmental Biology Program, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta 30912, USA
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147
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Brostrom MA, Reilly BA, Wilson FJ, Brostrom CO. Vasopressin-induced hypertrophy in H9c2 heart-derived myocytes. Int J Biochem Cell Biol 2000; 32:993-1006. [PMID: 11084379 DOI: 10.1016/s1357-2725(00)00037-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein synthesis in H9c2 heart-derived myocytes responds biphasically to arginine vasopressin (1 microM). An initial 50% inhibition attributable to Ca(2+) mobilization from the sarcoplasmic/endoplasmic reticulum is followed by a recovery that subsequently converts to a 1.5-fold stimulation. This study was undertaken to ascertain whether vasopressin programs H9c2 cells to undergo hypertrophy or to proliferate and whether early translational inhibition is required for programming. Translational suppression was observed only at vasopressin concentrations (>1 nM) causing extensive (>50%) depletion of Ca(2+) stores and was diminished at supraphysiologic extracellular Ca(2+) concentrations. Stimulation of protein synthesis, by contrast, was unaffected by changes in extracellular Ca(2+), depended on gene transcription, was suppressed by a protein kinase C pseudosubstrate sequence (peptide 19-27), and was observed at pM vasopressin concentrations. Activation of MAP kinases, phosphoinositide 3-kinase, calcineurin, S6 kinase, or eIF4 could not be implicated in the stimulation, which persisted for 24 h. Vasopressin-treated H9c2 cells underwent hypertrophy by standard criteria. Cellular protein accumulation occurred at pM hormone concentrations, was blocked by peptide 19-27, was observed regardless of retinoic acid pretreatment to prevent myogenic transdifferentiation, and preceded full repletion of Ca(2+) stores. It is proposed that H9c2 cells, which possess all basic features of V1-vasopressin receptor signaling, provide a convenient model for investigating vasopressin-induced myocyte hypertrophy. Early translational suppression is not needed for vasopressin-induced H9c2 myocyte hypertrophy whereas activation of protein kinase C appears essential.
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Affiliation(s)
- M A Brostrom
- Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
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