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Guha S, Nguyen AM, Young A, Mondell E, Farber DB. Decreased CREB phosphorylation impairs embryonic retinal neurogenesis in the Oa1-/- mouse model of Ocular albinism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.14.594013. [PMID: 38798688 PMCID: PMC11118284 DOI: 10.1101/2024.05.14.594013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Mutations in the human Ocular albinism type-1 gene OA1 are associated with abnormal retinal pigment epithelium (RPE) melanogenesis and poor binocular vision resulting from misrouting of ipsilateral retinal ganglion cell (iRGC) axons to the brain. We studied the latter using wild-type (WT) and Oa1-/- mouse eyes. At embryonic stages, the WT RPE-specific Oa1 protein signals through cAMP/Epac1-Erk2-CREB. Following CREB phosphorylation, a pCREB gradient extends from the RPE to the differentiating retinal amacrine and RGCs. In contrast to WT, the Oa1-/- RPE and ventral ciliary-margin-zone, a niche for iRGCs, express less pCREB while their retinas have a disrupted pCREB gradient, indicating Oa1's involvement in pCREB maintenance. Oa1-/- retinas also show hyperproliferation, enlarged nuclei, reduced differentiation, and fewer newborn amacrine and RGCs than WT retinas. Our results demonstrate that Oa1's absence leads to reduced binocular vision through a hyperproliferation-associated block in differentiation that impairs neurogenesis. This may affect iRGC axon's routing to the brain.
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Affiliation(s)
- Sonia Guha
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Andrew M. Nguyen
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Alejandra Young
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Ethan Mondell
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Debora B. Farber
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
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2
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Lewis MJ, Khaliulin I, Hall K, Suleiman MS. Cardioprotection of Immature Heart by Simultaneous Activation of PKA and Epac: A Role for the Mitochondrial Permeability Transition Pore. Int J Mol Sci 2022; 23:ijms23031720. [PMID: 35163640 PMCID: PMC8836102 DOI: 10.3390/ijms23031720] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/25/2022] [Accepted: 01/30/2022] [Indexed: 02/04/2023] Open
Abstract
Metabolic and ionic changes during ischaemia predispose the heart to the damaging effects of reperfusion. Such changes and the resulting injury differ between immature and adult hearts. Therefore, cardioprotective strategies for adults must be tested in immature hearts. We have recently shown that the simultaneous activation of protein kinase A (PKA) and exchange protein activated by cAMP (Epac) confers marked cardioprotection in adult hearts. The aim of this study is to investigate the efficacy of this intervention in immature hearts and determine whether the mitochondrial permeability transition pore (MPTP) is involved. Isolated perfused Langendorff hearts from both adult and immature rats were exposed to global ischaemia and reperfusion injury (I/R) following control perfusion or perfusion after an equilibration period with activators of PKA and/or Epac. Functional outcome and reperfusion injury were measured and in parallel, mitochondria were isolated following 5 min of reperfusion to determine whether cardioprotective interventions involved changes in MPTP opening behaviour. Perfusion for 5 min preceding ischaemia of injury-matched adult and immature hearts with 5 µM 8-Br (8-Br-cAMP-AM), an activator of both PKA and Epac, led to significant reduction in post-reperfusion CK release and infarct size. Perfusion with this agent also led to a reduction in MPTP opening propensity in both adult and immature hearts. These data show that immature hearts are innately more resistant to I/R injury than adults, and that this is due to a reduced tendency of MPTP opening following reperfusion. Furthermore, simultaneous stimulation of PKA and Epac causes cardioprotection, which is additive to the innate resistance.
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Affiliation(s)
- Martin John Lewis
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, UK
- Correspondence:
| | - Igor Khaliulin
- School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 91120, Israel;
| | - Katie Hall
- Bristol Medical School, University of Bristol, Bristol BS8 1TH, UK; (K.H.); (M.S.S.)
| | - M. Saadeh Suleiman
- Bristol Medical School, University of Bristol, Bristol BS8 1TH, UK; (K.H.); (M.S.S.)
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3
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Hirschhäuser C, Lissoni A, Görge PM, Lampe PD, Heger J, Schlüter KD, Leybaert L, Schulz R, Boengler K. Connexin 43 phosphorylation by casein kinase 1 is essential for the cardioprotection by ischemic preconditioning. Basic Res Cardiol 2021; 116:21. [PMID: 33751227 PMCID: PMC7985055 DOI: 10.1007/s00395-021-00861-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 03/10/2021] [Indexed: 02/07/2023]
Abstract
Myocardial connexin 43 (Cx43) forms gap junctions and hemichannels, and is also present within subsarcolemmal mitochondria. The protein is phosphorylated by several kinases including mitogen-activated protein kinase (MAPK), protein kinase C (PKC), and casein kinase 1 (CK1). A reduction in Cx43 content abrogates myocardial infarct size reduction by ischemic preconditioning (IPC). The present study characterizes the contribution of Cx43 phosphorylation towards mitochondrial function, hemichannel activity, and the cardioprotection by IPC in wild-type (WT) mice and in mice in which Cx43-phosphorylation sites targeted by above kinases are mutated to non-phosphorylatable residues (Cx43MAPKmut, Cx43PKCmut, and Cx43CK1mut mice). The amount of Cx43 in the left ventricle and in mitochondria was reduced in all mutant strains compared to WT mice and Cx43 phosphorylation was altered at residues not directly targeted by the mutations. Whereas complex 1 respiration was reduced in all strains, complex 2 respiration was decreased in Cx43CK1mut mice only. In Cx43 epitope-mutated mice, formation of reactive oxygen species and opening of the mitochondrial permeability transition pore were not affected. The hemichannel open probability was reduced in Cx43PKCmut and Cx43CK1mut but not in Cx43MAPKmut cardiomyocytes. Infarct size in isolated saline-perfused hearts after ischemia/reperfusion (45 min/120 min) was comparable between genotypes and was significantly reduced by IPC (3 × 3 min ischemia/5 min reperfusion) in WT, Cx43MAPKmut, and Cx43PKCmut, but not in Cx43CK1mut mice, an effect independent from the amount of Cx43 and the probability of hemichannel opening. Taken together, our study shows that alterations of Cx43 phosphorylation affect specific cellular functions and highlights the importance of Cx43 phosphorylation by CK1 for IPC's cardioprotection.
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Affiliation(s)
- Christine Hirschhäuser
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Alessio Lissoni
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | | | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Jacqueline Heger
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Klaus-Dieter Schlüter
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Rainer Schulz
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany
| | - Kerstin Boengler
- Institut für Physiologie, Justus-Liebig Universität Gießen, Aulweg 129, 35392, Giessen, Germany.
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Silva I, Magalhães-Cardoso MT, Ferreirinha F, Moreira S, Costa AF, Silva D, Vieira C, Silva-Ramos M, Correia-de-Sá P. β 3 Adrenoceptor-induced cholinergic inhibition in human and rat urinary bladders involves the exchange protein directly activated by cyclic AMP 1 favoring adenosine release. Br J Pharmacol 2020; 177:1589-1608. [PMID: 31721163 DOI: 10.1111/bph.14921] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 10/11/2019] [Accepted: 10/21/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE The mechanism by which β3 receptor agonists (e.g. mirabegron) control bladder overactivity may involve adenosine release from human and rat detrusor smooth muscle. Retrograde activation of adenosine A1 receptors reduces ACh release from cholinergic bladder nerves. β3 -Adrenoceptors usually couple to adenylyl cyclase. Here we investigated, which of the cAMP targets, protein kinase A or the exchange protein directly activated by cAMP (EPAC) could be involved in this cholinergic inhibition of the bladder. EXPERIMENTAL APPROACH [3 H]ACh and adenosine release from urothelium-denuded detrusor strips of cadaveric human organ donors and rats were measured by liquid scintillation spectrometry and HPLC, respectively. In vivo cystometry was also performed in urethane-anaesthetized rats. KEY RESULTS The exchange protein directly activated by cAMP (EPAC) inhibitor, ESI-09, prevented mirabegron- and isoprenaline-induced adenosine release from human and rat detrusor strips respectively. ESI-09, but not the PKA inhibitor, H-89, attenuated inhibition of [3 H]ACh release from stimulated (10 Hz) detrusor strips caused by activating β3 -adrenoceptors, AC (forskolin) and EPAC1 (8-CTP-2Me-cAMP). Isoprenaline-induced inhibition of [3 H]ACh release was also prevented by inhibitors of PKC (chelerythrine and Go6976) and of the equilibrative nucleoside transporter 1 (ENT1; dipyridamole and NBTI), but not by PLC inhibition with U73122. Pretreatment with ESI-09, but not with H-89, prevented the reduction of the voiding frequency caused by isoprenaline and forskolin in vivo. CONCLUSION AND IMPLICATIONS Data suggest that β3 -adrenoceptor-induced inhibition of cholinergic neurotransmission in human and rat urinary bladders involves activation of an EPAC1/PKC pathway downstream cAMP production resulting in adenosine outflow via ENT1.
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Affiliation(s)
- Isabel Silva
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - M Teresa Magalhães-Cardoso
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Sílvia Moreira
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Ana Filipa Costa
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Diogo Silva
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Cátia Vieira
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Miguel Silva-Ramos
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Serviço de Urologia, Centro Hospitalar Universitário do Porto (CHUP), Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.,Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
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5
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PDE4 and Epac1 Synergistically Promote Rectal Carcinoma via the cAMP Pathway. Anal Cell Pathol (Amst) 2019; 2019:7145198. [PMID: 30809467 PMCID: PMC6364102 DOI: 10.1155/2019/7145198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 09/09/2018] [Accepted: 09/27/2018] [Indexed: 12/14/2022] Open
Abstract
Objective To assess the expression levels of exchange protein 1 directly activated by cAMP (Epac1) and phosphodiesterase 4 (PDE4) in rectal carcinoma, and their associations with clinicopathological indexes. In addition, the associations of PDE4 and Epac1 with A-kinase anchor protein 95, connexin 43, cyclin D1, and cyclin E1 were evaluated. Methods The PV-9000 two-step immunohistochemistry method was used to determine protein expression in 44 rectal carcinoma tissue samples and 16 paracarcinoma tissue specimens. Results The positive rate of PDE4 protein expression in rectal carcinoma tissues was higher than that of paracarcinoma tissues (59.09% vs. 12.5%, P < 0.05). Similar findings were obtained for Epac1 (55% vs. 6.25%, P < 0.05). No significant associations of PDE4 and Epac1 with degree of differentiation, histological type, and lymph node metastasis were found in rectal carcinoma (P > 0.05). Correlations between PDE4 and Epac1, PDE4 and Cx43, PDE4 and cyclin E1, and Epac1 and Cx43 were observed (all P < 0.05). There was no correlation between the other protein pairs examined (P > 0.05). Conclusion PDE4 and Epac1 expression levels are increased in rectal carcinoma tissues, suggesting that the two proteins may be involved in the development of this malignancy. Meanwhile, correlations between PDE4 and Epac1, PDE4 and Cx43, PDE4 and cyclin E1, and Epac1 and Cx43 suggested synergistic effects of these proteins in promoting rectal carcinoma.
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6
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Laudette M, Zuo H, Lezoualc'h F, Schmidt M. Epac Function and cAMP Scaffolds in the Heart and Lung. J Cardiovasc Dev Dis 2018; 5:jcdd5010009. [PMID: 29401660 PMCID: PMC5872357 DOI: 10.3390/jcdd5010009] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 01/25/2018] [Accepted: 01/29/2018] [Indexed: 12/13/2022] Open
Abstract
Evidence collected over the last ten years indicates that Epac and cAMP scaffold proteins play a critical role in integrating and transducing multiple signaling pathways at the basis of cardiac and lung physiopathology. Some of the deleterious effects of Epac, such as cardiomyocyte hypertrophy and arrhythmia, initially described in vitro, have been confirmed in genetically modified mice for Epac1 and Epac2. Similar recent findings have been collected in the lung. The following sections will describe how Epac and cAMP signalosomes in different subcellular compartments may contribute to cardiac and lung diseases.
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Affiliation(s)
- Marion Laudette
- Inserm UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III, 31432 Toulouse, France.
| | - Haoxiao Zuo
- Department of Molecular Pharmacology, University of Groningen, 9713AV Groningen, The Netherlands.
- Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of Groningen, 9713AV Groningen, The Netherlands.
| | - Frank Lezoualc'h
- Inserm UMR-1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III, 31432 Toulouse, France.
| | - Martina Schmidt
- Department of Molecular Pharmacology, University of Groningen, 9713AV Groningen, The Netherlands.
- Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of Groningen, 9713AV Groningen, The Netherlands.
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Schinner C, Vielmuth F, Rötzer V, Hiermaier M, Radeva MY, Co TK, Hartlieb E, Schmidt A, Imhof A, Messoudi A, Horn A, Schlipp A, Spindler V, Waschke J. Adrenergic Signaling Strengthens Cardiac Myocyte Cohesion. Circ Res 2017; 120:1305-1317. [PMID: 28289018 DOI: 10.1161/circresaha.116.309631] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 02/22/2017] [Accepted: 03/10/2017] [Indexed: 01/08/2023]
Abstract
RATIONALE The sympathetic nervous system is a major mediator of heart function. Intercalated discs composed of desmosomes, adherens junctions, and gap junctions provide the structural backbone for coordinated contraction of cardiac myocytes. OBJECTIVE Gap junctions dynamically remodel to adapt to sympathetic signaling. However, it is unknown whether such rapid adaption also occurs for the adhesive function provided by desmosomes and adherens junctions. METHODS AND RESULTS Atomic force microscopy revealed that β-adrenergic signaling enhances both the number of desmoglein 2-specific interactions along cell junctions and the mean desmoglein 2-mediated binding forces, whereas N-cadherin-mediated interactions were not affected. This was accompanied by increased cell cohesion in cardiac myocyte cultures and murine heart slices. Enhanced desmoglein 2-positive contacts and increased junction length as revealed by immunofluorescence and electron microscopy reflected cAMP-induced reorganization of intercellular contacts. The mechanism underlying cAMP-mediated strengthening of desmoglein 2 binding was dependent on expression of the intercalated disc plaque protein plakoglobin (Pg) and direct phosphorylation at S665 by protein kinase A: Pg deficiency as well as overexpression of the phospho-deficient Pg-mutant S665A abrogated both cAMP-mediated junctional remodeling and increase of cohesion. Moreover, Pg knockout hearts failed to functionally adapt to adrenergic stimulation. CONCLUSIONS Taken together, we provide first evidence for positive adhesiotropy as a new cardiac function of sympathetic signaling. Positive adhesiotropy is dependent on Pg phosphorylation at S665 by protein kinase A. This mechanism may be of high medical relevance because loss of junctional Pg is a hallmark of arrhythmogenic cardiomyopathy.
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Affiliation(s)
- Camilla Schinner
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Franziska Vielmuth
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Vera Rötzer
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Matthias Hiermaier
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Mariya Y Radeva
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Thu Kim Co
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Eva Hartlieb
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Andreas Schmidt
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Axel Imhof
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Ahmed Messoudi
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Anja Horn
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Angela Schlipp
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Volker Spindler
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany
| | - Jens Waschke
- From the Institute of Anatomy and Cell Biology (C.S., F.V., V.R., M.H., M.Y.R., T.K.C., E.H., A.M., A.H., A. Schlipp, V.S., J.W.) and Biomedical Center and Center for Integrated Protein Sciences Munich (A. Schmidt, A.I.), Ludwig-Maximilians-Universität, Germany.
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8
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Khaliulin I, Bond M, James AF, Dyar Z, Amini R, Johnson JL, Suleiman MS. Functional and cardioprotective effects of simultaneous and individual activation of protein kinase A and Epac. Br J Pharmacol 2017; 174:438-453. [PMID: 28071786 PMCID: PMC5323515 DOI: 10.1111/bph.13709] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 12/23/2016] [Accepted: 01/05/2017] [Indexed: 01/16/2023] Open
Abstract
Background and Purpose Myocardial cAMP elevation confers cardioprotection against ischaemia/reperfusion (I/R) injury. cAMP activates two independent signalling pathways, PKA and Epac. This study investigated the cardiac effects of activating PKA and/or Epac and their involvement in cardioprotection against I/R. Experimental Approach Hearts from male rats were used either for determination of PKA and PKC activation or perfused in the Langendorff mode for either cardiomyocyte isolation or used to monitor functional activity at basal levels and after 30 min global ischaemia and 2 h reperfusion. Functional recovery and myocardial injury during reperfusion (LDH release and infarct size) were evaluated. Activation of PKA and/or Epac in perfused hearts was induced using cell permeable cAMP analogues in the presence or absence of inhibitors of PKA, Epac and PKC. H9C2 cells and cardiomyocytes were used to assess activation of Epac and effect on Ca2+ transients. Key Results Selective activation of either PKA or Epac was found to trigger a positive inotropic effect, which was considerably enhanced when both pathways were simultaneously activated. Only combined activation of PKA and Epac induced marked cardioprotection against I/R injury. This was accompanied by PKCε activation and repressed by inhibitors of PKA, Epac or PKC. Conclusion and Implications Simultaneous activation of both PKA and Epac induces an additive inotropic effect and confers optimal and marked cardioprotection against I/R injury. The latter effect is mediated by PKCε activation. This work has introduced a new therapeutic approach and targets to protect the heart against cardiac insults.
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Affiliation(s)
- Igor Khaliulin
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - Mark Bond
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - Andrew F James
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - Zara Dyar
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - Raheleh Amini
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - Jason L Johnson
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
| | - M-Saadeh Suleiman
- School of Clinical Sciences and Bristol Cardiovascular, University of Bristol, Bristol, UK
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9
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Fujita T, Umemura M, Yokoyama U, Okumura S, Ishikawa Y. The role of Epac in the heart. Cell Mol Life Sci 2017; 74:591-606. [PMID: 27549789 PMCID: PMC11107744 DOI: 10.1007/s00018-016-2336-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/21/2016] [Accepted: 08/09/2016] [Indexed: 02/08/2023]
Abstract
As one of the most important second messengers, 3',5'-cyclic adenosine monophosphate (cAMP) mediates various extracellular signals including hormones and neurotransmitters, and induces appropriate responses in diverse types of cells. Since cAMP was formerly believed to transmit signals through only two direct target molecules, protein kinase A and the cyclic nucleotide-gated channel, the sensational discovery in 1998 of another novel direct effecter of cAMP [exchange proteins directly activated by cAMP (Epac)] attracted a great deal of scientific interest in cAMP signaling. Numerous studies on Epac have since disclosed its important functions in various tissues in the body. Recently, observations of genetically manipulated mice in various pathogenic models have begun to reveal the in vivo significance of previous in vitro or cellular-level findings. Here, we focused on the function of Epac in the heart. Accumulating evidence has revealed that both Epac1 and Epac2 play important roles in the structure and function of the heart under physiological and pathological conditions. Accordingly, developing the ability to regulate cAMP-mediated signaling through Epac may lead to remarkable new therapies for the treatment of cardiac diseases.
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Affiliation(s)
- Takayuki Fujita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Masanari Umemura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoshi Okumura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
- Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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Lezoualc'h F, Fazal L, Laudette M, Conte C. Cyclic AMP Sensor EPAC Proteins and Their Role in Cardiovascular Function and Disease. Circ Res 2016; 118:881-97. [PMID: 26941424 DOI: 10.1161/circresaha.115.306529] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
cAMP is a universal second messenger that plays central roles in cardiovascular regulation influencing gene expression, cell morphology, and function. A crucial step toward a better understanding of cAMP signaling came 18 years ago with the discovery of the exchange protein directly activated by cAMP (EPAC). The 2 EPAC isoforms, EPAC1 and EPAC2, are guanine-nucleotide exchange factors for the Ras-like GTPases, Rap1 and Rap2, which they activate independently of the classical effector of cAMP, protein kinase A. With the development of EPAC pharmacological modulators, many reports in the literature have demonstrated the critical role of EPAC in the regulation of various cAMP-dependent cardiovascular functions, such as calcium handling and vascular tone. EPAC proteins are coupled to a multitude of effectors into distinct subcellular compartments because of their multidomain architecture. These novel cAMP sensors are not only at the crossroads of different physiological processes but also may represent attractive therapeutic targets for the treatment of several cardiovascular disorders, including cardiac arrhythmia and heart failure.
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Affiliation(s)
- Frank Lezoualc'h
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.).
| | - Loubina Fazal
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
| | - Marion Laudette
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
| | - Caroline Conte
- From the Department of Cardiac and Renal Remodeling of the Institute of Metabolic and Cardiovascular Diseases (I2MC), Institut National de la Santé et de la Recherche Médicale (INSERM), UMR-1048, Toulouse, France (F.L., L.F., M.L., C.C.); and Université Toulouse III-Paul Sabatier, Toulouse, France (F.L., L.F., M.L., C.C.)
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Protection of erythropoietin against ischemic neurovascular unit injuries through the effects of connexin43. Biochem Biophys Res Commun 2015; 458:656-662. [DOI: 10.1016/j.bbrc.2015.02.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/04/2015] [Indexed: 11/19/2022]
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Del Rio CL, Clymer BD, Billman GE. Myocardial electrotonic response to submaximal exercise in dogs with healed myocardial infarctions: evidence for β-adrenoceptor mediated enhanced coupling during exercise testing. Front Physiol 2015; 6:25. [PMID: 25698976 PMCID: PMC4318283 DOI: 10.3389/fphys.2015.00025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 01/15/2015] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Autonomic neural activation during cardiac stress testing is an established risk-stratification tool in post-myocardial infarction (MI) patients. However, autonomic activation can also modulate myocardial electrotonic coupling, a known factor to contribute to the genesis of arrhythmias. The present study tested the hypothesis that exercise-induced autonomic neural activation modulates electrotonic coupling (as measured by myocardial electrical impedance, MEI) in post-MI animals shown to be susceptible or resistant to ventricular fibrillation (VF). METHODS Dogs (n = 25) with healed MI instrumented for MEI measurements were trained to run on a treadmill and classified based on their susceptibility to VF (12 susceptible, 9 resistant). MEI and ECGs were recorded during 6-stage exercise tests (18 min/test; peak: 6.4 km/h @ 16%) performed under control conditions, and following complete β-adrenoceptor (β-AR) blockade (propranolol); MEI was also measured at rest during escalating β-AR stimulation (isoproterenol) or overdrive-pacing. RESULTS Exercise progressively increased heart rate (HR) and reduced heart rate variability (HRV). In parallel, MEI decreased gradually (enhanced electrotonic coupling) with exercise; at peak exercise, MEI was reduced by 5.3 ± 0.4% (or -23 ± 1.8Ω, P < 0.001). Notably, exercise-mediated electrotonic changes were linearly predicted by the degree of autonomic activation, as indicated by changes in either HR or in HRV (P < 0.001). Indeed, β-AR blockade attenuated the MEI response to exercise while direct β-AR stimulation (at rest) triggered MEI decreases comparable to those observed during exercise; ventricular pacing had no significant effects on MEI. Finally, animals prone to VF had a significantly larger MEI response to exercise. CONCLUSIONS These data suggest that β-AR activation during exercise can acutely enhance electrotonic coupling in the myocardium, particularly in dogs susceptible to ischemia-induced VF.
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Affiliation(s)
- Carlos L Del Rio
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA ; Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA ; Safety Pharmacology, QTest Labs Columbus, OH, USA
| | - Bradley D Clymer
- Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA ; Biomedical Engineering, The Ohio State University Columbus, OH, USA
| | - George E Billman
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA ; Davis Heart and Lung Research Institute, The Ohio State University Columbus, OH, USA
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Mostafavi H, Khaksarian M, Joghataei MT, Soleimani M, Hassanzadeh G, Eftekhari S, Soleimani M, Mousavizadeh K, Estiri H, Ahmadi S, Hadjighassem MR. Selective β2 adrenergic agonist increases Cx43 and miR-451 expression via cAMP-Epac. Mol Med Rep 2014; 9:2405-10. [PMID: 24714982 DOI: 10.3892/mmr.2014.2120] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 01/15/2014] [Indexed: 11/05/2022] Open
Abstract
It has been demonstrated that connexin 43 (Cx43) and microRNAs have significant roles in glioma. Cyclic adenosine monophosphate (cAMP) is suggested to be a regulator of connexins and microRNAs. However, it remains elusive whether cAMP and exchange protein directly activated by cAMP (Epac2), have a regulatory effect on Cx43 and microRNA-451 (miR-451) in astrocytoma cells. We treated 1321N1 astrocytoma cells with a selective β2 adrenergic agonist and a selective Epac activator with and without adenyl cyclase and protein kinase A inhibition. Cx43 and miR-451 expression were measured. Next, we evaluated the effect of miR-451 overexpression on Cx43 expression. Cell proliferation was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results demonstrated that cAMP-Epac2 increased Cx43 and miR-451 expression. However, the alteration of miR-451 expression required a higher dose of drugs. Overexpression of miR-451 had no significant effect on Cx43 expression. The MTT assay showed that cAMP-Epac stimulation and miR-451 overexpression had a synergic inhibitory effect on cell proliferation. These findings may expand our understanding of the molecular biology of glioma and provide new potential therapeutic targets.
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Affiliation(s)
- Hossein Mostafavi
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
| | - Mojtaba Khaksarian
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
| | - Mohammad Taghi Joghataei
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
| | - Masoud Soleimani
- Department of Hematology, Tarbiat Modares University, Tehran 1411713116, Iran
| | - Gholamreza Hassanzadeh
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
| | - Sanaz Eftekhari
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
| | - Mansooreh Soleimani
- Division of Neuroscience, Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 141775553, Iran
| | - Kazem Mousavizadeh
- Division of Neuroscience, Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 141775553, Iran
| | - Hajar Estiri
- Stem Cell Technology Research Center, Molecular Biology and Genetic Engineering Department, Tehran 1585636473, Iran
| | - Sedighesadat Ahmadi
- Stem Cell Technology Research Center, Molecular Biology and Genetic Engineering Department, Tehran 1585636473, Iran
| | - Mahmoud Reza Hadjighassem
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran 1417755469, Iran
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Schmidt M, Dekker FJ, Maarsingh H. Exchange protein directly activated by cAMP (epac): a multidomain cAMP mediator in the regulation of diverse biological functions. Pharmacol Rev 2013; 65:670-709. [PMID: 23447132 DOI: 10.1124/pr.110.003707] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Since the discovery nearly 60 years ago, cAMP is envisioned as one of the most universal and versatile second messengers. The tremendous feature of cAMP to tightly control highly diverse physiologic processes, including calcium homeostasis, metabolism, secretion, muscle contraction, cell fate, and gene transcription, is reflected by the award of five Nobel prizes. The discovery of Epac (exchange protein directly activated by cAMP) has ignited a new surge of cAMP-related research and has depicted novel cAMP properties independent of protein kinase A and cyclic nucleotide-gated channels. The multidomain architecture of Epac determines its activity state and allows cell-type specific protein-protein and protein-lipid interactions that control fine-tuning of pivotal biologic responses through the "old" second messenger cAMP. Compartmentalization of cAMP in space and time, maintained by A-kinase anchoring proteins, phosphodiesterases, and β-arrestins, contributes to the Epac signalosome of small GTPases, phospholipases, mitogen- and lipid-activated kinases, and transcription factors. These novel cAMP sensors seem to implement certain unexpected signaling properties of cAMP and thereby to permit delicate adaptations of biologic responses. Agonists and antagonists selective for Epac are developed and will support further studies on the biologic net outcome of the activation of Epac. This will increase our current knowledge on the pathophysiology of devastating diseases, such as diabetes, cognitive impairment, renal and heart failure, (pulmonary) hypertension, asthma, and chronic obstructive pulmonary disease. Further insights into the cAMP dynamics executed by the Epac signalosome will help to optimize the pharmacological treatment of these diseases.
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Affiliation(s)
- Martina Schmidt
- Department of Molecular Pharmacology, Groningen Research Institute for Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands.
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Ruiz-Hurtado G, Morel E, Domínguez-Rodríguez A, Llach A, Lezoualc'h F, Benitah JP, Gomez AM. Epac in cardiac calcium signaling. J Mol Cell Cardiol 2012; 58:162-71. [PMID: 23220153 DOI: 10.1016/j.yjmcc.2012.11.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 11/19/2012] [Accepted: 11/28/2012] [Indexed: 12/16/2022]
Abstract
Epac, exchange protein directly activated by cAMP, is emerging as a new regulator of cardiac physiopathology. Although its effects are much less known than the classical cAMP effector, PKA, several studies have investigated the cardiac role of Epac, providing evidences that Epac modulates intracellular Ca(2+). In one of the first analyses, it was shown that Epac can increase the frequency of spontaneous Ca(2+) oscillations in cultured rat cardiomyocytes. Later on, in adult cardiomyocytes, it was shown that Epac can induce sarcoplasmic reticulum (SR) Ca(2+) release in a PKA independent manner. The pathway identified involved phospholipase C (PLC) and Ca(2+)/calmodulin kinase II (CaMKII). The latter phosphorylates the ryanodine receptor (RyR), increasing the Ca(2+) spark probability. The RyR, Ca(2+) release channel located in the SR membrane, is a key element in the excitation-contraction coupling. Thus Epac participates in the excitation-contraction coupling. Moreover, by inducing RyR phosphorylation, Epac is arrhythmogenic. A detailed analysis of Ca(2+) mobilization in different microdomains showed that Epac preferently elevated Ca(2+) in the nucleoplasm ([Ca(2+)]n). This effect, besides PLC and CaMKII, required inositol 1,4,5 trisphosphate receptor (IP3R) activation. IP3R is other Ca(2+) release channel located mainly in the perinuclear area in the adult ventricular myocytes, where it has been shown to participate in the excitation-transcription coupling (the process by which Ca(2+) activates transcription). If Epac activation is maintained for some time, the histone deacetylase (HDAC) is translocated out of the nucleus de-repressing the transcription factor myocyte enhancer factor (MEF2). These evidences also pointed to Epac role in activating the excitation-transcription coupling. In fact, it has been shown that Epac induces cardiomyocyte hypertrophy. Epac activation for several hours, even before the cell hypertrophies, induces a profound modulation of the excitation-contraction coupling: increasing the [Ca(2+)]i transient amplitude and cellular contraction. Thus Epac actions are rapid but time and microdomain dependent in the cardiac myocyte. Taken together the results collected indicate that Epac may have an important role in the cardiac response to stress.
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Affiliation(s)
- Gema Ruiz-Hurtado
- Inserm, U769, Univ. Paris-Sud 11, IFR141, Labex Lermit, Châtenay-Malabry, France
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Suppression of Rap1 impairs cardiac myofibrils and conduction system in zebrafish. PLoS One 2012; 7:e50960. [PMID: 23226434 PMCID: PMC3511394 DOI: 10.1371/journal.pone.0050960] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 10/29/2012] [Indexed: 11/19/2022] Open
Abstract
Numerous studies have revealed that Rap1 (Ras-proximate-1 or Ras-related protein 1), a small GTPase protein, plays a crucial role in mediating cAMP signaling in isolated cardiac tissues and cell lines. However, the involvement of Rap1 in the cardiac development in vivo is largely unknown. By injecting anti-sense morpholino oligonucleotides to knock down Rap1a and Rap1b in zebrafish embryos, and in combination with time-lapsed imaging, in situ hybridization, immunohistochemistry and transmission electron microscope techniques, we seek to understand the role of Rap1 in cardiac development and functions. At an optimized low dose of mixed rap1a and rap1b morpholino oligonucleotides, the heart developed essentially normally until cardiac contraction occurred. Morphant hearts showed the myocardium defect phenotypes, most likely due to disrupted myofibril assembly and alignment. In vivo heart electrocardiography revealed prolonged P-R interval and QRS duration, consistent with an adherens junction defect and reduced Connexons in cardiac myocytes of morphants. We conclude that a proper level of Rap1 is crucial for heart morphogenesis and function, and suggest that Rap1 and/or their downstream factor genes are potential candidates for genetic screening for human heart diseases.
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Chen C, Du J, Feng W, Song Y, Lu Z, Xu M, Li Z, Zhang Y. β-Adrenergic receptors stimulate interleukin-6 production through Epac-dependent activation of PKCδ/p38 MAPK signalling in neonatal mouse cardiac fibroblasts. Br J Pharmacol 2012; 166:676-88. [PMID: 22103274 DOI: 10.1111/j.1476-5381.2011.01785.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE IL-6 plays crucial roles in cardiac hypertrophy, cardiac fibrosis and heart failure. Activation of β-adrenoceptors induced IL-6 production in neonatal mouse cardiac fibroblasts (NMCFs) through a G(s) /adenylate cyclase/cAMP/p38 MAPK pathway but independent of PKA. However, how cAMP activates p38 MAPK is still not defined. In this study, we have assessed the role of the exchange protein directly activated by cAMP (Epac) and PKCδ in p38 MAPK activation and IL-6 production by stimulated by the β-adrenoceptor agonist isoprenaline in NMCFs. EXPERIMENTAL APPROACH The IL-6 concentration in cell culture supernatants was measured by ELISA. The levels of phosphorylated and total p38 MAPK and PKCδ were determined by Western blot analysis. The translocation of PKCδ was determined by immunoblotting the soluble and particulate fractions. Expression of Epac1 or PKCδ was knocked down by the corresponding, adenovirus-mediated, small hairpin RNA (shRNA). RESULTS In NMCFs, activation of β-adrenoceptors enhanced PKCδ phosphorylation and translocation. Furthermore, knock-down of the PKCδ isoform using an adenovirus-mediated shRNA markedly down-regulated IL-6 induction by NMCFs stimulated with isoprenaline. Moreover, knock-down of Epac1 confirmed that Epac1 was upstream of PKCδ in IL-6 production. Additionally, both Epac1 and PKCδ mediated the p38 MAPK activation induced by isoprenaline. CONCLUSIONS AND IMPLICATIONS β-Adrenoceptor agonists activate a cAMP/Epac/PKCδ/p38 MAPK pathway to produce IL-6 in NMCFs. This study identifies Epac as the link between cAMP and p38 MAPK signalling pathways and demonstrates that PKCδ can function as a novel downstream effector of this β-adrenoceptor/cAMP/Epac pathway.
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Affiliation(s)
- Chao Chen
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health and Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
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Hervé JC, Derangeon M. Gap-junction-mediated cell-to-cell communication. Cell Tissue Res 2012; 352:21-31. [PMID: 22940728 DOI: 10.1007/s00441-012-1485-6] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 08/01/2012] [Indexed: 11/26/2022]
Abstract
Cells of multicellular organisms need to communicate with each other and have evolved various mechanisms for this purpose, the most direct and quickest of which is through channels that directly connect the cytoplasms of adjacent cells. Such intercellular channels span the two plasma membranes and the intercellular space and result from the docking of two hemichannels. These channels are densely packed into plasma-membrane spatial microdomains termed "gap junctions" and allow cells to exchange ions and small molecules directly. A hemichannel is a hexameric torus of junctional proteins around an aqueous pore. Vertebrates express two families of gap-junction proteins: the well-characterized connexins and the more recently discovered pannexins, the latter being related to invertebrate innexins ("invertebrate connexins"). Some gap-junctional hemichannels also appear to mediate cell-extracellular communication. Communicating junctions play crucial roles in the maintenance of homeostasis, morphogenesis, cell differentiation and growth control in metazoans. Gap-junctional channels are not passive conduits, as previously long regarded, but use "gating" mechanisms to open and close the central pore in response to biological stimuli (e.g. a change in the transjunctional voltage). Their permeability is finely tuned by complex mechanisms that have just begun to be identified. Given their ubiquity and diversity, gap junctions play crucial roles in a plethora of functions and their dysfunctions are involved in a wide range of diseases. However, the exact mechanisms involved remain poorly understood.
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Affiliation(s)
- Jean-Claude Hervé
- Institut de Physiologie et Biologie Cellulaires, FRE3511, Université de Poitiers, CNRS, 1 Rue Georges Bonnet, Poitiers, 86022, France.
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Abstract
Epacs (exchange proteins directly activated by cAMP) are guanine-nucleotide-exchange factors for the Ras-like small GTPases Rap1 and Rap2. Epacs were discovered in 1998 as new sensors for the second messenger cAMP acting in parallel to PKA (protein kinase A). As cAMP regulates many important physiological functions in brain and heart, the existence of Epacs raises many questions regarding their role in these tissues. The present review focuses on the biological roles and signalling pathways of Epacs in neurons and cardiac myocytes. We discuss the potential involvement of Epacs in the manifestation of cardiac and central diseases such as cardiac hypertrophy and memory disorders.
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Hill J, Lee SK, Samasilp P, Smith C. Pituitary adenylate cyclase-activating peptide enhances electrical coupling in the mouse adrenal medulla. Am J Physiol Cell Physiol 2012; 303:C257-66. [PMID: 22592408 DOI: 10.1152/ajpcell.00119.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neuroendocrine adrenal medullary chromaffin cells receive synaptic excitation through the sympathetic splanchnic nerve to elicit catecholamine release into the circulation. Under basal sympathetic tone, splanchnic-released acetylcholine evokes chromaffin cells to fire action potentials, leading to synchronous phasic catecholamine release. Under elevated splanchnic firing, experienced under the sympathoadrenal stress response, chromaffin cells undergo desensitization to cholinergic excitation. Yet, stress evokes a persistent and elevated adrenal catecholamine release. This sustained stress-evoked release has been shown to depend on splanchnic release of a peptide transmitter, pituitary adenylate cyclase-activating peptide (PACAP). PACAP stimulates catecholamine release through a PKC-dependent pathway that is mechanistically independent of cholinergic excitation. Moreover, it has also been reported that shorter term phospho-regulation of existing gap junction channels acts to increase junctional conductance. In this study, we test if PACAP-mediated excitation upregulates cell-cell electrical coupling to enhance chromaffin cell excitability. We utilize electrophysiological recordings conducted in adrenal tissue slices to measure the effects of PACAP stimulation on cell coupling. We report that PACAP excitation increases electrical coupling and the spread of electrical excitation between adrenal chromaffin cells. Thus PACAP acts not only as a secretagogue but also evokes an electrical remodeling of the medulla, presumably to adapt to the organism's needs during acute sympathetic stress.
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Affiliation(s)
- Jacqueline Hill
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA
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Rap-linked cAMP signaling Epac proteins: Compartmentation, functioning and disease implications. Cell Signal 2011; 23:1257-66. [DOI: 10.1016/j.cellsig.2011.03.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/04/2011] [Accepted: 03/04/2011] [Indexed: 12/14/2022]
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Duquesnes N, Lezoualc'h F, Crozatier B. PKC-delta and PKC-epsilon: foes of the same family or strangers? J Mol Cell Cardiol 2011; 51:665-73. [PMID: 21810427 DOI: 10.1016/j.yjmcc.2011.07.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/24/2011] [Accepted: 07/15/2011] [Indexed: 11/30/2022]
Abstract
Protein kinase C (PKC) is a family of 10 serine/threonine kinases divided into 3 subfamilies, classical, novel and atypical classes. Two PKC isozymes of the novel group, PKCε and PKCδ, have different and sometimes opposite effects. PKCε stimulates cell growth and differentiation while PKCδ is apoptotic. In the heart, they are among the most expressed PKC isozymes and they are opposed in the preconditioning process with a positive role of PKCε and an inhibiting role of PKCδ. The goal of this review is to analyze the structural differences of these 2 enzymes that may explain their different behaviors and properties.
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Alesutan I, Sopjani M, Munoz C, Fraser S, Kemp BE, Föller M, Lang F. Inhibition of Connexin 26 by the AMP-Activated Protein Kinase. J Membr Biol 2011; 240:151-8. [DOI: 10.1007/s00232-011-9353-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 02/22/2011] [Indexed: 01/19/2023]
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Dzhura I, Chepurny OG, Kelley GG, Leech CA, Roe MW, Dzhura E, Afshari P, Malik S, Rindler MJ, Xu X, Lu Y, Smrcka AV, Holz GG. Epac2-dependent mobilization of intracellular Ca²+ by glucagon-like peptide-1 receptor agonist exendin-4 is disrupted in β-cells of phospholipase C-ε knockout mice. J Physiol 2010; 588:4871-89. [PMID: 21041529 DOI: 10.1113/jphysiol.2010.198424] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Calcium can be mobilized in pancreatic β-cells via a mechanism of Ca(2+)-induced Ca(2+) release (CICR), and cAMP-elevating agents such as exendin-4 facilitate CICR in β-cells by activating both protein kinase A and Epac2. Here we provide the first report that a novel phosphoinositide-specific phospholipase C- (PLC-) is expressed in the islets of Langerhans, and that the knockout (KO) of PLC- gene expression in mice disrupts the action of exendin-4 to facilitate CICR in the β-cells of these mice. Thus, in the present study, in which wild-type (WT) C57BL/6 mouse β-cells were loaded with the photolabile Ca(2+) chelator NP-EGTA, the UV flash photolysis-catalysed uncaging of Ca(2+) generated CICR in only 9% of the β-cells tested, whereas CICR was generated in 82% of the β-cells pretreated with exendin-4. This action of exendin-4 to facilitate CICR was reproduced by cAMP analogues that activate protein kinase A (6-Bnz-cAMP-AM) or Epac2 (8-pCPT-2'-O-Me-cAMP-AM) selectively. However, in β-cells of PLC- KO mice, and also Epac2 KO mice, these test substances exhibited differential efficacies in the CICR assay such that exendin-4 was partly effective, 6-Bnz-cAMP-AM was fully effective, and 8-pCPT-2'-O-Me-cAMP-AM was without significant effect. Importantly, transduction of PLC- KO β-cells with recombinant PLC- rescued the action of 8-pCPT-2'-O-Me-cAMP-AM to facilitate CICR, whereas a K2150E PLC- with a mutated Ras association (RA) domain, or a H1640L PLC- that is catalytically dead, were both ineffective. Since 8-pCPT-2'-O-Me-cAMP-AM failed to facilitate CICR in WT β-cells transduced with a GTPase activating protein (RapGAP) that downregulates Rap activity, the available evidence indicates that a signal transduction 'module' comprised of Epac2, Rap and PLC- exists in β-cells, and that the activities of Epac2 and PLC- are key determinants of CICR in this cell type.
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Affiliation(s)
- Igor Dzhura
- Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY, USA
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