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Boileve A, Romito O, Hof T, Levallois A, Brard L, d'Hers S, Fouchet A, Simard C, Guinamard R, Brette F, Sallé L. EPAC1 and 2 inhibit K + currents via PLC/PKC and NOS/PKG pathways in rat ventricular cardiomyocytes. Am J Physiol Cell Physiol 2024; 327:C557-C570. [PMID: 38985989 DOI: 10.1152/ajpcell.00582.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/29/2024] [Accepted: 06/19/2024] [Indexed: 07/12/2024]
Abstract
The exchange protein directly activated by cAMP (EPAC) has been implicated in cardiac proarrhythmic signaling pathways including spontaneous diastolic Ca2+ leak from sarcoplasmic reticulum and increased action potential duration (APD) in isolated ventricular cardiomyocytes. The action potential (AP) lengthening following acute EPAC activation is mainly due to a decrease of repolarizing steady-state K+ current (IKSS) but the mechanisms involved remain unknown. This study aimed to assess the role of EPAC1 and EPAC2 in the decrease of IKSS and to investigate the underlying signaling pathways. AP and K+ currents were recorded with the whole cell configuration of the patch-clamp technique in freshly isolated rat ventricular myocytes. EPAC1 and EPAC2 were pharmacologically activated with 8-(4-chlorophenylthio)-2'-O-methyl-cAMP acetoxymethyl ester (8-CPTAM, 10 µmol/L) and inhibited with R-Ce3F4 and ESI-05, respectively. Inhibition of EPAC1 and EPAC2 significantly decreased the effect of 8-CPTAM on APD and IKSS showing that both EPAC isoforms are involved in these effects. Unexpectedly, calmodulin-dependent protein kinase II (CaMKII) inhibition by AIP or KN-93, and Ca2+ chelation by intracellular BAPTA, did not impact the response to 8-CPTAM. However, inhibition of PLC/PKC and nitric oxide synthase (NOS)/PKG pathways partially prevents the 8-CPTAM-dependent decrease of IKSS. Finally, the cumulative inhibition of PKC and PKG blocked the 8-CPTAM effect, suggesting that these two actors work along parallel pathways to regulate IKSS upon EPAC activation. On the basis of such findings, we propose that EPAC1 and EPAC2 are involved in APD lengthening by inhibiting a K+ current via both PLC/PKC and NOS/PKG pathways. This may have pathological implications since EPAC is upregulated in diseases such as cardiac hypertrophy.NEW & NOTEWORHTY Exchange protein directly activated by cAMP (EPAC) proteins modulate ventricular electrophysiology at the cellular level. Both EPAC1 and EPAC2 isoforms participate in this effect. Mechanistically, PLC/PKC and nitric oxide synthase (NO)/PKG pathways are involved in regulating K+ repolarizing current whereas the well-known downstream effector of EPAC, calmodulin-dependent protein kinase II (CaMKII), does not participate. This may have pathological implications since EPAC is upregulated in diseases such as cardiac hypertrophy. Thus, EPAC inhibition may be a new approach to prevent arrhythmias under pathological conditions.
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Affiliation(s)
- Arthur Boileve
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Olivier Romito
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Thomas Hof
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Aurélia Levallois
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Laura Brard
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Sarah d'Hers
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Alexandre Fouchet
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Christophe Simard
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Romain Guinamard
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
| | - Fabien Brette
- PhyMedExp, INSERM U1046, CNRS 9412, Université de Montpellier, Montpellier, France
| | - Laurent Sallé
- UR 4650 PSIR, GIP Cyceron, Caen, France
- Normandie University, Caen, France
- UNICAEN, Caen, France
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Sun F, Zhang J, Chen L, Yuan Y, Guo X, Dong L, Sun J. Epac1 Signaling Pathway Mediates the Damage and Apoptosis of Inner Ear Hair Cells after Noise Exposure in a Rat Model. Neuroscience 2021; 465:116-127. [PMID: 33838290 DOI: 10.1016/j.neuroscience.2021.03.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 03/12/2021] [Accepted: 03/26/2021] [Indexed: 01/21/2023]
Abstract
To investigate the role of the exchange protein directly activated by cAMP (Epac) signaling pathway in inner ear hair cell damage and apoptosis after noise exposure, we analyzed the expression level of Epac1 in a rat model of noise-induced hearing loss (NIHL), based on rat exposure to a 4-kHz and 106-dB sound pressure level (SPL) for 8 h. Loss of outer hair cells (OHCs), mitochondrial lesions, and hearing loss were examined after treatment with the Epac agonist, 8-CPT, or the Epac inhibitor, ESI-09. The effects of 8-CPT and ESI-09 on cell proliferation and apoptosis were examined by CCK-8 assays, holographic microscopy imaging, and Annexin-V FITC/PI staining in HEI-OC1 cells. The effects of 8-CPT and ESI-09 on Ca2+ entry were evaluated by confocal Ca2+ fluorescence measurement. We found that the expression level of Epac1 was significantly increased in the cochlear tissue after noise exposure. In NIHL rats, 8-CPT increased the loss of OHCs, mitochondrial lesions, and hearing loss compared to control rats, while ESI-09 produced the opposite effects. Oligomycin was used to induce HEI-OC1 cell damage in vitro. In HEI-OC1 cells treated with oligomycin, 8-CPT and ESI-09 increased and reduced cell apoptosis, respectively. Moreover, 8-CPT promoted Ca2+ uptake in HEI-OC1 cells, while ESI-09 inhibited this process. In conclusion, our data provide strong evidence that the Epac1 signaling pathway mediates early pathological damage in NIHL, and that Epac1 inhibition protects from NIHL, identifying Epac1 as a new potential therapeutic target for NIHL.
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Affiliation(s)
- Fanfan Sun
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of USTC, Hefei 230001, China; Department of Pharmacology, Key Laboratory of Anti-Inflammatory and Immunopharmacology of Ministry of Education, Key Laboratory of Chinese Medicine Research and Development of State Administration of Traditional Chinese Medicine, Anhui Medical University, Hefei 230032, China
| | - Junge Zhang
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of USTC, Hefei 230001, China
| | - Li Chen
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of USTC, Hefei 230001, China
| | - Yuhao Yuan
- Department of Pharmacology, Key Laboratory of Anti-Inflammatory and Immunopharmacology of Ministry of Education, Key Laboratory of Chinese Medicine Research and Development of State Administration of Traditional Chinese Medicine, Anhui Medical University, Hefei 230032, China
| | - Xiaotao Guo
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of USTC, Hefei 230001, China
| | - Liuyi Dong
- Department of Pharmacology, Key Laboratory of Anti-Inflammatory and Immunopharmacology of Ministry of Education, Key Laboratory of Chinese Medicine Research and Development of State Administration of Traditional Chinese Medicine, Anhui Medical University, Hefei 230032, China.
| | - Jiaqiang Sun
- Department of Otolaryngology-Head and Neck Surgery, The First Affiliated Hospital of USTC, Hefei 230001, China.
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Integration of Rap1 and Calcium Signaling. Int J Mol Sci 2020; 21:ijms21051616. [PMID: 32120817 PMCID: PMC7084553 DOI: 10.3390/ijms21051616] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 02/07/2023] Open
Abstract
Ca2+ is a universal intracellular signal. The modulation of cytoplasmic Ca2+ concentration regulates a plethora of cellular processes, such as: synaptic plasticity, neuronal survival, chemotaxis of immune cells, platelet aggregation, vasodilation, and cardiac excitation–contraction coupling. Rap1 GTPases are ubiquitously expressed binary switches that alternate between active and inactive states and are regulated by diverse families of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Active Rap1 couples extracellular stimulation with intracellular signaling through secondary messengers—cyclic adenosine monophosphate (cAMP), Ca2+, and diacylglycerol (DAG). Much evidence indicates that Rap1 signaling intersects with Ca2+ signaling pathways to control the important cellular functions of platelet activation or neuronal plasticity. Rap1 acts as an effector of Ca2+ signaling when activated by mechanisms involving Ca2+ and DAG-activated (CalDAG-) GEFs. Conversely, activated by other GEFs, such as cAMP-dependent GEF Epac, Rap1 controls cytoplasmic Ca2+ levels. It does so by regulating the activity of Ca2+ signaling proteins such as sarcoendoplasmic reticulum Ca2+-ATPase (SERCA). In this review, we focus on the physiological significance of the links between Rap1 and Ca2+ signaling and emphasize the molecular interactions that may offer new targets for the therapy of Alzheimer’s disease, hypertension, and atherosclerosis, among other diseases.
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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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