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Neshati Z, Schalij MJ, de Vries AAF. The proarrhythmic features of pathological cardiac hypertrophy in neonatal rat ventricular cardiomyocyte cultures. J Appl Physiol (1985) 2020; 128:545-553. [PMID: 31999526 DOI: 10.1152/japplphysiol.00420.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Different factors may trigger arrhythmias in diseased hearts, including fibrosis, cardiomyocyte hypertrophy, hypoxia, and inflammation. This makes it difficult to establish the relative contribution of each of them to the occurrence of arrhythmias. Accordingly, in this study, we used an in vitro model of pathological cardiac hypertrophy (PCH) to investigate its proarrhythmic features and the underlying mechanisms independent of fibrosis or other PCH-related processes. Neonatal rat ventricular cardiomyocyte (nr-vCMC) monolayers were treated with phorbol 12-myristate 13-acetate (PMA) to create an in vitro model of PCH. The electrophysiological properties of PMA-treated and control monolayers were analyzed by optical mapping at day 9 of culture. PMA treatment led to a significant increase in cell size and total protein content. It also caused a reduction in sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 level (32%) and an increase in natriuretic peptide A (42%) and α1-skeletal muscle actin (34%) levels, indicating that the hypertrophic response induced by PMA was, indeed, pathological in nature. PMA-treated monolayers showed increases in action potential duration (APD) and APD dispersion, and a decrease in conduction velocity (CV; APD30 of 306 ± 39 vs. 148 ± 18 ms, APD30 dispersion of 85 ± 19 vs. 22 ± 7 and CV of 10 ± 4 vs. 21 ± 2 cm/s in controls). Upon local 1-Hz stimulation, 53.6% of the PMA-treated cultures showed focal tachyarrhythmias based on triggered activity (n = 82), while the control group showed 4.3% tachyarrhythmias (n = 70). PMA-treated nr-vCMC cultures may, thus, represent a well-controllable in vitro model for testing new therapeutic interventions targeting specific aspects of hypertrophy-associated arrhythmias.NEW & NOTEWORTHY Phorbol 12-myristate 13-acetate (PMA) treatment of neonatal rat ventricular cardiomyocytes (nr-vCMCs) led to induction of many significant features of pathological cardiac hypertrophy (PCH), including action potential duration prolongation and dispersion, which provided enough time and depolarizing force for formation of early afterdepolarization (EAD)-induced focal tachyarrhythmias. PMA-treated nr-vCMCs represent a well-controllable in vitro model, which mostly resembles to moderate left ventricular hypertrophy (LVH) rather than severe LVH, in which generation of a reentry is the putative mechanism of its arrhythmias.
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Affiliation(s)
- Zeinab Neshati
- Zeinab Neshati, Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran.,Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
| | - Martin J Schalij
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
| | - Antoine A F de Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
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Lu XL, Tong YF, Liu Y, Xu YL, Yang H, Zhang GY, Li XH, Zhang HG. Gαq protein carboxyl terminus imitation polypeptide GCIP-27 improves cardiac function in chronic heart failure rats. PLoS One 2015; 10:e0121007. [PMID: 25822412 PMCID: PMC4379177 DOI: 10.1371/journal.pone.0121007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 02/03/2015] [Indexed: 11/24/2022] Open
Abstract
Background Gαq protein carboxyl terminus imitation polypeptide (GCIP)-27 has been shown to alleviate pathological cardiomyocyte hypertrophy induced by various factors. Pathological cardiac hypertrophy increases the morbidity and mortality of cardiovascular diseases while it compensates for poor heart function. This study was designed to investigate the effects of GCIP-27 on heart function in rats with heart failure induced by doxorubicin. Methods and Results Forty-eight rats were randomly divided into the following six groups receiving vehicle (control), doxorubicin (Dox), losartan (6 mg/kg, i.g.) and three doses of GCIP-27 (10, 30, 90 μg/kg; i.p., bid), respectively. Heart failure was induced by Dox, which was administered at a 20 mg/kg cumulative dose. After 10 weeks of treatment, we observed that GCIP-27 (30, 90 μg/kg) significantly increased ejection fraction, fraction shortening, stroke volume and sarcoplasmic reticulum Ca2+ ATPase activity of Dox-treated hearts. Additionally, GCIP-27 decreased myocardial injury, heart weight index and left ventricular weight index, fibrosis and serum cardiac troponin-I concentration in Dox-treated mice. Immunohistochemistry, western blotting and real-time PCR experiments indicated that GCIP-27 (10–90 μg/kg) could markedly upregulate the protein expression of myocardial α-myosin heavy chain (MHC), Bcl-2, protein kinase C (PKC) ε and phosphorylated extracellular signal-regulated kinase (p-ERK) 1/2 as well as the mRNA expression of α-MHC, but downregulated the expression of β-MHC, Bax and PKC βII, and the mRNA expression levels of β-MHC in Dox-treated mice. It was also found that GCIP-27 (30, 90 μg/L) decreased cell size and protein content of cardiomyocytes significantly in vitro by comparison of Dox group. Conclusions GCIP-27 could effectively ameliorate heart failure development induced by Dox. PKC–ERK1/2 signaling might represent the underlying mechanism of the beneficial effects of GCIP-27.
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Affiliation(s)
- Xiao Lan Lu
- Department of Pharmacology, College of Pharmacy, Third Military Medical University, Chongqing 400038, China
- Department of Clinical Laboratory, First Affiliated Hospital of North Sichuan Medical College, Sichuan Nanchong 637000, China
| | - Yang Fei Tong
- Department of Pharmacology, College of Pharmacy, Third Military Medical University, Chongqing 400038, China
| | - Ya Liu
- Institute of Materia Medica and Department of Pharmaceutics, College of Pharmacy, Third Military Medical University, Chongqing 40038, China
| | - Ya Li Xu
- Department of Ultrasound, Second Affiliated Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hua Yang
- Department of Pharmacology, College of Pharmacy, Third Military Medical University, Chongqing 400038, China
| | - Guo Yuan Zhang
- Department of Clinical Laboratory, First Affiliated Hospital of North Sichuan Medical College, Sichuan Nanchong 637000, China
| | - Xiao-Hui Li
- Institute of Materia Medica and Department of Pharmaceutics, College of Pharmacy, Third Military Medical University, Chongqing 40038, China
| | - Hai-Gang Zhang
- Department of Pharmacology, College of Pharmacy, Third Military Medical University, Chongqing 400038, China
- * E-mail:
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Suresh Babu S, Joladarashi D, Jeyabal P, Thandavarayan RA, Krishnamurthy P. RNA-stabilizing proteins as molecular targets in cardiovascular pathologies. Trends Cardiovasc Med 2015; 25:676-83. [PMID: 25801788 DOI: 10.1016/j.tcm.2015.02.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/31/2015] [Accepted: 02/13/2015] [Indexed: 01/08/2023]
Abstract
The stability of mRNA has emerged as a key step in the regulation of eukaryotic gene expression and function. RNA stabilizing proteins (RSPs) contain several RNA recognition motifs, and selectively bind to adenylate-uridylate-rich elements in the 3' untranslated region of several mRNAs leading to altered processing, stability, and translation. These post-transcriptional gene regulations play a critical role in cellular homeostasis; therefore act as molecular switch between 'normal cell' and 'disease state.' Many mRNA binding proteins have been discovered to date, which either stabilize (HuR/HuA, HuB, HuC, HuD) or destabilize (AUF1, tristetraprolin, KSRP) the target transcripts. Although the function of RSPs has been widely studied in cancer biology, its role in cardiovascular pathologies is only beginning to evolve. The current review provides an overall understanding of the potential role of RSPs, specifically HuR-mediated mRNA stability in myocardial infarction, hypertension and hypertrophy. Also, the effect of RSPs on various cellular processes including inflammation, fibrosis, angiogenesis, cell-death, and proliferation and its relevance to cardiovascular pathophysiological processes is presented. We also discuss the potential clinical implications of RSPs as therapeutic targets in cardiovascular diseases.
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Affiliation(s)
- Sahana Suresh Babu
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX
| | - Darukeshwara Joladarashi
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX
| | - Prince Jeyabal
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX
| | - Rajarajan A Thandavarayan
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX
| | - Prasanna Krishnamurthy
- Department of Cardiovascular Sciences, Center for Cardiovascular Regeneration, Houston Methodist Research Institute, Houston, TX.
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Koshman YE, Chu M, Kim T, Kalmanson O, Farjah M, Kumar M, Lewis W, Geenen DL, de Tombe P, Goldspink PH, Solaro RJ, Samarel AM. Cardiomyocyte-specific expression of CRNK, the C-terminal domain of PYK2, maintains ventricular function and slows ventricular remodeling in a mouse model of dilated cardiomyopathy. J Mol Cell Cardiol 2014; 72:281-91. [PMID: 24713463 DOI: 10.1016/j.yjmcc.2014.03.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 02/22/2014] [Accepted: 03/29/2014] [Indexed: 01/06/2023]
Abstract
Up-regulation and activation of PYK2, a member of the FAK family of protein tyrosine kinases, is involved in the pathogenesis of left ventricular (LV) remodeling and heart failure (HF). PYK2 activation can be prevented by CRNK, the C-terminal domain of PYK2. We previously demonstrated that adenoviral-mediated CRNK gene transfer improved survival and LV function, and slowed LV remodeling in a rat model of coronary artery ligation-induced HF. We now interrogate whether cardiomyocyte-specific, transgenic CRNK expression prevents LV remodeling and HF in a mouse model of dilated cardiomyopathy (DCM) caused by constitutively active Protein Kinase Cε (caPKCε). Transgenic (TG; FVB/N background) mice were engineered to express rat CRNK under control of the α-myosin heavy chain promoter, and crossed with FVB/N mice with cardiomyocyte-specific expression of caPKCε to create double TG mice. LV structure, function, and gene expression were evaluated in all 4 groups (nonTG FVB/N; caPKCε(+/-); CRNK(+/-); and caPKCε×CRNK (PXC) double TG mice) at 1, 3, 6, 9 and 12mo of age. CRNK expression followed a Mendelian distribution, and CRNK mice developed and survived normally through 12mo. Cardiac structure, function and selected gene expression of CRNK mice were similar to nonTG littermates. CRNK had no effect on caPKCε expression and vice versa. PYK2 was up-regulated ~6-fold in caPKCε mice, who developed a non-hypertrophic, progressive DCM with reduced systolic (Contractility Index=151±5 vs. 90±4s(-1)) and diastolic (Tau=7.5±0.5 vs. 14.7±1.3ms) function, and LV dilatation (LV Remodeling Index (LVRI)=4.2±0.1 vs. 6.0±0.3 for FVB/N vs. caPKCε mice, respectively; P<0.05 for each at 12mo). In double TG PXC mice, CRNK expression significantly prolonged survival, improved contractile function (Contractile Index=115±8s(-1); Tau=9.5±1.0ms), and reduced LV remodeling (LVRI=4.9±0.1). Cardiomyocyte-specific expression of CRNK improves contractile function and slows LV remodeling in a mouse model of DCM.
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Affiliation(s)
- Yevgeniya E Koshman
- Department of Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Miensheng Chu
- Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Taehoon Kim
- Department of Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Olivia Kalmanson
- Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Mariam Farjah
- Department of Physiology and Biophysics, University of Illinois - Chicago, Chicago, IL 60612, USA
| | - Mohit Kumar
- Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - William Lewis
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David L Geenen
- Department of Physiology and Biophysics, University of Illinois - Chicago, Chicago, IL 60612, USA
| | - Pieter de Tombe
- Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Paul H Goldspink
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - R John Solaro
- Department of Physiology and Biophysics, University of Illinois - Chicago, Chicago, IL 60612, USA
| | - Allen M Samarel
- Department of Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA; Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA.
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Uehara Y, Azuma Y, Minai K, Yoshida H, Yoshimura M, Shimizu M. Endothelin-1 prolongs intracellular calcium transient decay in neonatal rat cardiac myocytes. Heart Vessels 2011; 27:98-105. [DOI: 10.1007/s00380-011-0133-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 03/04/2011] [Indexed: 01/08/2023]
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Puglisi JL, Yuan W, Timofeyev V, Myers RE, Chiamvimonvat N, Samarel AM, Bers DM. Phorbol ester and endothelin-1 alter functional expression of Na+/Ca2+ exchange, K+, and Ca2+ currents in cultured neonatal rat myocytes. Am J Physiol Heart Circ Physiol 2010; 300:H617-26. [PMID: 21131481 DOI: 10.1152/ajpheart.00388.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Endothelin-1 (ET-1) and activation of protein kinase C (PKC) have been implicated in alterations of myocyte function in cardiac hypertrophy and heart failure. Changes in cellular Ca2+ handling and electrophysiological properties also occur in these states and may contribute to mechanical dysfunction and arrhythmias. While ET-1 or PKC stimulation induces cellular hypertrophy in cultured neonatal rat ventricular myocytes (NRVMs), a system widely used in studies of hypertrophic signaling, there is little data about electrophysiological changes. Here we studied the effects of ET-1 (100 nM) or the PKC activator phorbol 12-myristate 13-acetate (PMA, 1 μM) on ionic currents in NRVMs. The acute effects of PMA or ET-1 (≤30 min) were small or insignificant. However, PMA or ET-1 exposure for 48-72 h increased cell capacitance by 100 or 25%, respectively, indicating cellular hypertrophy. ET-1 also slightly increased Ca2+ current density (T and L type). Na+/Ca2+ exchange current was increased by chronic pretreatment with either PMA or ET-1. In contrast, transient outward and delayed rectifier K+ currents were strongly downregulated by PMA or ET-1 pretreatment. Inward rectifier K+ current tended toward a decrease at larger negative potential, but time-independent outward K+ current was unaltered by either treatment. The enhanced inward and reduced outward currents also result in action potential prolongation after PMA or ET-1 pretreatment. We conclude that chronic PMA or ET-1 exposure in cultured NRVMs causes altered functional expression of cardiac ion currents, which mimic electrophysiological changes seen in whole animal and human hypertrophy and heart failure.
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Affiliation(s)
- José L Puglisi
- Cardiovascular Institute and Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
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Blum JL, Samarel AM, Mestril R. Phosphorylation and binding of AUF1 to the 3'-untranslated region of cardiomyocyte SERCA2a mRNA. Am J Physiol Heart Circ Physiol 2005; 289:H2543-50. [PMID: 16113063 DOI: 10.1152/ajpheart.00545.2005] [Citation(s) in RCA: 22] [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
Experimental animals and patients with cardiac hypertrophy and heart failure display abnormally slowed myocardial relaxation, which is associated with downregulation of sarco(endo)plasmic reticulum calcium ATPase 2a (SERCA2a), the cardiomyocyte sarcoplasmic reticulum Ca2+ pump. We previously showed that SERCA2a downregulation can be simulated in cultured neonatal rat ventricular myocytes (NRVM) by treatment with the hypertrophic agonist phorbol myristate acetate (PMA) or by overexpression of the novel protein kinase C (PKC) isoenzymes PKCdelta and PKCepsilon. PKC activation, in turn, decreased SERCA2a promoter activity and destabilized the SERCA2a mRNA. Here we demonstrate by using an RSV beta-galactosidase reporter system that a 609-nt fragment of the SERCA2a mRNA 3'-untranslated region (UTR), containing five adenylate-uridylate (AU)-rich regions, may be responsible for destabilizing the message following PMA treatment. UV cross-linking analysis demonstrated that several proteins found in the NRVM cell extracts bind to the 609-nt fragment. In addition, protein binding was transiently increased in response to PMA stimulation. 3'-UTR mRNA pull-down assays and Western blot analysis indicated that the AU binding protein AUF1 interacted with the SERCA2a 3'-UTR. AUF1 binding activity was predominantly found in the nuclear fraction, and PMA-induced AUF1 binding was associated with increased threonine phosphorylation of AUF1. These data suggest that the phosphorylation, binding, and location of AUF1 affect the posttranscriptional regulation of the SERCA2a message in NRVM.
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Affiliation(s)
- Juliana L Blum
- The Cardiovascular Institute, Loyola Univ. Medical Center, Bldg 110, Rm. 5222, 2160 South First Ave., Maywood, IL 60153, USA
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8
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Heidkamp MC, Scully BT, Vijayan K, Engman SJ, Szotek EL, Samarel AM. PYK2 regulates SERCA2 gene expression in neonatal rat ventricular myocytes. Am J Physiol Cell Physiol 2005; 289:C471-82. [PMID: 15829561 DOI: 10.1152/ajpcell.00130.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (PYK2) has been implicated in cell signaling pathways involved in left ventricular hypertrophy and heart failure, but its exact role has not been elucidated. In this study, replication-defective adenoviruses (Adv) encoding green fluorescent protein (GFP)-tagged, wild-type (WT), and mutant forms of PYK2 were used to determine whether PYK2 overexpression activates MAPKs, and downregulates SERCA2 mRNA levels in neonatal rat ventricular myocytes (NRVM). PYK2 overexpression significantly decreased SERCA2 mRNA (as determined by Northern blot analysis and real-time RT-PCR) to 54 ± 4% of Adv-GFP-infected cells 48 h after Adv infection. Adv-encoding kinase-deficient (KD) and Y402F phosphorylation-deficient mutants of PYK2 also significantly reduced SERCA2 mRNA (WT>KD>Y402F). Conversely, the PTK inhibitor PP2 (which blocks PYK2 phosphorylation by Src-family PTKs) significantly increased SERCA2 mRNA levels. PYK2 overexpression had no effect on ERK1/2, but increased JNK1/2 and p38MAPKphosphorylation from fourfold to eightfold compared with GFP overexpression. Activation of both “stress-activated” protein kinase cascades appeared necessary to reduce SERCA2 mRNA levels. Adv-mediated overexpression of constitutively active (ca)MKK6 or caMKK7, which activated only p38MAPKor JNKs, respectively, was not sufficient, whereas combined infection with both Adv reduced SERCA2 mRNA levels to 45 ± 12% of control. WTPYK2 overexpression also significantly reduced SERCA2 promoter activity, as determined by transient transfection of a 3.8-kb SERCA2 promoter-luciferase construct. Thus a PYK2-dependent signaling cascade may have a role in abnormal cardiac Ca2+handling in left ventricular hypertrophy and heart failure via downregulation of SERCA2 gene transcription.
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Affiliation(s)
- Maria C Heidkamp
- The Cardiovascular Institute, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
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Watanuki S, Matsuda N, Sakuraya F, Jesmin S, Hattori Y. Protein kinase C modulation of the regulation of sarcoplasmic reticular function by protein kinase A-mediated phospholamban phosphorylation in diabetic rats. Br J Pharmacol 2003; 141:347-59. [PMID: 14691046 PMCID: PMC1574184 DOI: 10.1038/sj.bjp.0705455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The goal of this study was to elucidate the possible mechanisms by which protein kinase A (PKA)-mediated regulation of the sarcoplasmic reticulum (SR) via phospholambin protein phosphorylation is functionally impaired in streptozotocin-induced diabetic rats. 2. Phospholamban (PLB) protein and mRNA levels were 1.3-fold higher in diabetic than in control hearts, while protein expression of cardiac SR Ca(2+)-ATPase (SERCA2a) was unchanged. 3. Basal and isoprenaline-stimulated phosphorylation of PLB at Ser(16) or Thr(17) was unchanged in diabetic hearts. However, stronger immunoreactivity was observed at the basal level in diabetic hearts when antiphosphoserine antibody was used. 4. Basal (32)P incorporation into PLB was significantly higher in diabetic than in control SR vesicles, but the extent of the PKA-mediated increase in PLB phosphorylation was the same in the two groups of vesicles. 5. Stimulation of Ca(2+) uptake by PKA-catalyzed PLB phosphorylation was weaker in diabetic than in control SR vesicles. The PKA-induced increase in Ca(2+) uptake was attenuated when control SR vesicles were preincubated with protein kinase C (PKC). 6. PKC activities were increased by more than two-fold in the membranous fractions from diabetic hearts in comparison with control values, regardless of whether Ca(2+) was present. This was associated with increases in the protein content of PKCdelta, PKCeta, PKCiota, and PKClambda in diabetic membranous fractions. 7. The changes observed in diabetic rats were reversed by insulin therapy. 8. These results suggest that PKA-dependent phosphorylation may incompletely counteract the function of PLB as an inhibitor of SERCA2a activity in diabetes in which PKC expression and activity are enhanced.
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Affiliation(s)
- Satoko Watanuki
- Department of Pharmacology, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
| | - Naoyuki Matsuda
- Department of Pharmacology, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
- Department of Anesthesiology & Critical Care Medicine, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
| | - Fumika Sakuraya
- Department of Anesthesiology & Critical Care Medicine, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
| | - Subrina Jesmin
- Department of Cardiovascular Medicine, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
| | - Yuichi Hattori
- Department of Pharmacology, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan
- Author for correspondence:
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Porter MJ, Heidkamp MC, Scully BT, Patel N, Martin JL, Samarel AM. Isoenzyme-selective regulation of SERCA2 gene expression by protein kinase C in neonatal rat ventricular myocytes. Am J Physiol Cell Physiol 2003; 285:C39-47. [PMID: 12606313 DOI: 10.1152/ajpcell.00461.2002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Patients with cardiac hypertrophy and heart failure display abnormally slowed myocardial relaxation, which is associated with downregulation of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2) gene expression. We previously showed that SERCA2 downregulation can be simulated in cultured neonatal rat ventricular myocytes (NRVM) by treatment with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA). However, NRVM express three different PMA-sensitive PKC isoenzymes (PKCalpha, PKCepsilon, and PKCdelta), which may be differentially regulated and have specific functions in the cardiomyocyte. Therefore, in this study we used adenoviral vectors encoding wild-type (wt) and kinase-defective, dominant negative (dn) mutant forms of PKCalpha, PKCepsilon, and PKCdelta to analyze their individual effects in regulating SERCA2 gene expression in NRVM. Overexpression of wtPKCepsilon and wtPKCdelta, but not wtPKCalpha, was sufficient to downregulate SERCA2 mRNA levels, as assessed by Northern blotting and quantitative, real-time RT-PCR (69 +/- 7 and 61 +/- 9% of control levels for wtPKCepsilon and wtPKCdelta, respectively; P < 0.05 for each adenovirus; n = 8 experiments). Conversely, overexpression of all three dnPKCs appeared to significantly increase SERCA2 mRNA levels (dnPKCdelta > dnPKCepsilon > dnPKCalpha). dnPKCdelta overexpression produced the largest increase (2.8 +/- 1.0-fold; n = 11 experiments). However, PMA treatment was still sufficient to downregulate SERCA2 mRNA levels despite overexpression of each dominant negative mutant. These data indicate that the novel PKC isoenzymes PKCepsilon and PKCdelta selectively regulate SERCA2 gene expression in cardiomyocytes but that neither PKC alone is necessary for this effect if the other novel PKC can be activated.
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Affiliation(s)
- Michael J Porter
- The Cardiovascular Institute and Department of Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
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Misquitta CM, Mwanjewe J, Nie L, Grover AK. Sarcoplasmic reticulum Ca(2+) pump mRNA stability in cardiac and smooth muscle: role of the 3'-untranslated region. Am J Physiol Cell Physiol 2002; 283:C560-8. [PMID: 12107066 DOI: 10.1152/ajpcell.00527.2001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Stomach smooth muscle (SSM) and left ventricular muscle (LVM) express the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pump gene SERCA2. Alternative splicing yields two major isoforms, SERCA2a in LVM and slow twitch muscle and SERCA2b in SSM and most other tissues. The splices have different 3'-untranslated regions (UTR) and also encode proteins that differ slightly in their COOH-terminal domains. SERCA2 transcription rates are similar in the two tissues, yet LVM has a much higher level of SERCA2 mRNA than SSM. To understand the control of SERCA2 RNA expression, we inhibited transcription and showed that the half-life of SERCA2 mRNA is significantly longer (P < 0.05) in primary cultures of LVM cells than in SSM cells. Nuclear SERCA2 mRNA levels were also higher in LVM than in SSM. In vitro decay assays using synthetic RNA corresponding to the 3'-UTR of SERCA2a and -2b showed that nuclear extracts produced a faster decay of SERCA2 RNA than cytoplasmic extracts and that nuclear extracts produced a faster decay of SERCA2b than -2a. This was also true when the full-length native mRNA was used instead of the 3'-UTR RNA, and SERCA2b decay by cytoplasmic extracts was faster for LVM than for SSM. We propose that nuclear decay is an initial step in the control of SERCA2 RNA abundance and that this control is maintained or modulated in the cytoplasm. We discuss how these control mechanisms may be part of a control switch in cardiac development and pathophysiology.
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Misquitta CM, Iyer VR, Werstiuk ES, Grover AK. The role of 3'-untranslated region (3'-UTR) mediated mRNA stability in cardiovascular pathophysiology. Mol Cell Biochem 2001; 224:53-67. [PMID: 11693200 DOI: 10.1023/a:1011982932645] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Knowledge of transcription and translation has advanced our understanding of cardiac diseases. Here, we present the hypothesis that the stability of mRNA mediated by the 3'-untranslated region (3'-UTR) plays a role in changing gene expression in cardiovascular pathophysiology. Several proteins that bind to sequences in the 3'-UTR of mRNA of cardiovascular targets have been identified. The affected mRNAs include those encoding beta-adrenergic receptors, angiotensin II receptors, endothelial and inducible nitric oxide synthases, cyclooxygenase, endothelial growth factor, tissue necrosis factor (TNF-alpha), globin, elastin, proteins involved in cell cycle regulation, oncogenes, cytokines and lymphokines. We discuss: (a) the types of 3'-UTR sequences involved in mRNA stability, (b) AUF1, HuR and other proteins that bind to these sequences to either stabilize or destabilize the target mRNAs, and (c) the potential role of the 3'-UTR mediated mRNA stability in heart failure, myocardial infarction and hypertension. We hope that these concepts will aid in better understanding cardiovascular diseases and in developing new therapies.
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Affiliation(s)
- C M Misquitta
- Department of Biology, McMaster University, Hamilton, ON, Canada
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Abstract
ATP, besides an intracellular energy source, is an agonist when applied to a variety of different cells including cardiomyocytes. Sources of ATP in the extracellular milieu are multiple. Extracellular ATP is rapidly degraded by ectonucleotidases. Today ionotropic P2X(1--7) receptors and metabotropic P2Y(1,2,4,6,11) receptors have been cloned and their mRNA found in cardiomyocytes. On a single cardiomyocyte, micromolar ATP induces nonspecific cationic and Cl(-) currents that depolarize the cells. ATP both increases directly via a G(s) protein and decreases Ca(2+) current. ATP activates the inward-rectifying currents (ACh- and ATP-activated K(+) currents) and outward K(+) currents. P2-purinergic stimulation increases cAMP by activating adenylyl cyclase isoform V. It also involves tyrosine kinases to activate phospholipase C-gamma to produce inositol 1,4,5-trisphosphate and Cl(-)/HCO(3)(-) exchange to induce a large transient acidosis. No clear correlation is presently possible between an effect and the activation of a given P2-receptor subtype in cardiomyocytes. ATP itself is generally a positive inotropic agent. Upon rapid application to cells, ATP induces various forms of arrhythmia. At the tissue level, arrhythmia could be due to slowing of electrical spread after both Na(+) current decrease and cell-to-cell uncoupling as well as cell depolarization and Ca(2+) current increase. In as much as the information is available, this review also reports analog effects of UTP and diadenosine polyphosphates.
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Affiliation(s)
- G Vassort
- Institut National de la Santé et de la Recherche Médicale U. 390, Centre Hospitalier Universitaire Arnaud de Villeneuve, Montpellier, France.
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Strait JB, Martin JL, Bayer A, Mestril R, Eble DM, Samarel AM. Role of protein kinase C-epsilon in hypertrophy of cultured neonatal rat ventricular myocytes. Am J Physiol Heart Circ Physiol 2001; 280:H756-66. [PMID: 11158975 DOI: 10.1152/ajpheart.2001.280.2.h756] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using adenovirus (Adv)-mediated overexpression of constitutively active (ca) and dominant-negative (dn) mutants, we examined whether protein kinase C (PKC)-epsilon, the major novel PKC isoenzyme expressed in the adult heart, was necessary and/or sufficient to induce specific aspects of the hypertrophic phenotype in low-density, neonatal rat ventricular myocytes (NRVM) in serum-free culture. Adv-caPKC-epsilon did not increase cell surface area or the total protein-to-DNA ratio. However, cell shape was markedly affected, as evidenced by a 67% increase in the cell length-to-width ratio and a 17% increase in the perimeter-to-area ratio. Adv-caPKC-epsilon also increased atrial natriuretic factor (ANF) and beta-myosin heavy chain (MHC) mRNA levels 2.5 +/- 0.3- and 2.1 +/- 0.2-fold, respectively, compared with NRVM infected with an empty, parent vector (P < 0.05 for both). Conversely, Adv-dnPKC-epsilon did not block endothelin-induced increases in cell surface area, the total protein-to-DNA ratio, or upregulation of beta-MHC and ANF gene expression. However, the dominant-negative inhibitor markedly suppressed endothelin-induced extracellular signal-regulated kinase (ERK) 1/2 activation. Taken together, these results indicate that caPKC-epsilon overexpression alters cell geometry, producing cellular elongation and remodeling without a significant, overall increase in cell surface area or total protein accumulation. Furthermore, PKC-epsilon activation and downstream signaling via the ERK cascade may not be necessary for cell growth, protein accumulation, and gene expression changes induced by endothelin.
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Affiliation(s)
- J B Strait
- Department of Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois 60153, USA
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Bowman JC, Steinberg SF, Jiang T, Geenen DL, Fishman GI, Buttrick PM. Expression of protein kinase C beta in the heart causes hypertrophy in adult mice and sudden death in neonates. J Clin Invest 1997; 100:2189-95. [PMID: 9410895 PMCID: PMC508413 DOI: 10.1172/jci119755] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Protein kinase C (PKC) activation in the heart has been linked to a hypertrophic phenotype and to processes that influence contractile function. To establish whether PKC activation is sufficient to induce an abnormal phenotype, PKCbeta was conditionally expressed in cardiomyocytes of transgenic mice. Transgene expression in adults caused mild and progressive ventricular hypertrophy associated with impaired diastolic relaxation, whereas expression in newborns caused sudden death associated with marked abnormalities in the regulation of intracellular calcium. Thus, the PKC signaling pathway in cardiocytes has different effects depending on the timing of expression and, in the adult, is sufficient to induce pathologic hypertrophy.
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Affiliation(s)
- J C Bowman
- Department of Medicine, Albert Einstein College of Medicine, New York, NY 10461, USA
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