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Xu B, Bahriz S, Salemme VR, Wang Y, Zhu C, Zhao M, Xiang YK. Differential Downregulation of β 1-Adrenergic Receptor Signaling in the Heart. J Am Heart Assoc 2024; 13:e033733. [PMID: 38860414 PMCID: PMC11255761 DOI: 10.1161/jaha.123.033733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 05/15/2024] [Indexed: 06/12/2024]
Abstract
BACKGROUND Chronic sympathetic stimulation drives desensitization and downregulation of β1 adrenergic receptor (β1AR) in heart failure. We aim to explore the differential downregulation subcellular pools of β1AR signaling in the heart. METHODS AND RESULTS We applied chronic infusion of isoproterenol to induced cardiomyopathy in male C57BL/6J mice. We applied confocal and proximity ligation assay to examine β1AR association with L-type calcium channel, ryanodine receptor 2, and SERCA2a ((Sarco)endoplasmic reticulum calcium ATPase 2a) and Förster resonance energy transfer-based biosensors to probe subcellular β1AR-PKA (protein kinase A) signaling in ventricular myocytes. Chronic infusion of isoproterenol led to reduced β1AR protein levels, receptor association with L-type calcium channel and ryanodine receptor 2 measured by proximity ligation (puncta/cell, 29.65 saline versus 14.17 isoproterenol, P<0.05), and receptor-induced PKA signaling at the plasma membrane (Förster resonance energy transfer, 28.9% saline versus 1.9% isoproterenol, P<0.05) and ryanodine receptor 2 complex (Förster resonance energy transfer, 30.2% saline versus 10.6% isoproterenol, P<0.05). However, the β1AR association with SERCA2a was enhanced (puncta/cell, 51.4 saline versus 87.5 isoproterenol, P<0.05), and the receptor signal was minimally affected. The isoproterenol-infused hearts displayed decreased PDE4D (phosphodiesterase 4D) and PDE3A and increased PDE2A, PDE4A, and PDE4B protein levels. We observed a reduced role of PDE4 and enhanced roles of PDE2 and PDE3 on the β1AR-PKA activity at the ryanodine receptor 2 complexes and myocyte shortening. Despite the enhanced β1AR association with SERCA2a, the endogenous norepinephrine-induced signaling was reduced at the SERCA2a complexes. Inhibiting monoamine oxidase A rescued the norepinephrine-induced PKA signaling at the SERCA2a and myocyte shortening. CONCLUSIONS This study reveals distinct mechanisms for the downregulation of subcellular β1AR signaling in the heart under chronic adrenergic stimulation.
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Affiliation(s)
- Bing Xu
- VA Northern California Health Care SystemMatherCAUSA
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
| | - Sherif Bahriz
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
- Department of Clinical Pathology, Faculty of MedicineMansoura UniversityMansouraEgypt
| | | | - Ying Wang
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
- Department of Pharmacology, School of MedicineSouthern University of Science and TechnologyShenzhenChina
| | - Chaoqun Zhu
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
| | - Meimi Zhao
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
- Department of Pharmaceutical ToxicologyChina Medical UniversityShenyangChina
| | - Yang K. Xiang
- VA Northern California Health Care SystemMatherCAUSA
- Department of PharmacologyUniversity of California at DavisDavisCAUSA
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2
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Kho C. Targeting calcium regulators as therapy for heart failure: focus on the sarcoplasmic reticulum Ca-ATPase pump. Front Cardiovasc Med 2023; 10:1185261. [PMID: 37534277 PMCID: PMC10392702 DOI: 10.3389/fcvm.2023.1185261] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/06/2023] [Indexed: 08/04/2023] Open
Abstract
Impaired myocardial Ca2+ cycling is a critical contributor to the development of heart failure (HF), causing changes in the contractile function and structure remodeling of the heart. Within cardiomyocytes, the regulation of sarcoplasmic reticulum (SR) Ca2+ storage and release is largely dependent on Ca2+ handling proteins, such as the SR Ca2+ ATPase (SERCA2a) pump. During the relaxation phase of the cardiac cycle (diastole), SERCA2a plays a critical role in transporting cytosolic Ca2+ back to the SR, which helps to restore both cytosolic Ca2+ levels to their resting state and SR Ca2+ content for the next contraction. However, decreased SERCA2a expression and/or pump activity are key features in HF. As a result, there is a growing interest in developing therapeutic approaches to target SERCA2a. This review provides an overview of the regulatory mechanisms of the SERCA2a pump and explores potential strategies for SERCA2a-targeted therapy, which are being investigated in both preclinical and clinical studies.
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Affiliation(s)
- Changwon Kho
- Division of Applied Medicine, School of Korean Medicine, Pusan National University, Yangsan, Republic of Korea
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3
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Neumann J, Hofmann B, Dhein S, Gergs U. Role of Dopamine in the Heart in Health and Disease. Int J Mol Sci 2023; 24:ijms24055042. [PMID: 36902474 PMCID: PMC10003060 DOI: 10.3390/ijms24055042] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/25/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Dopamine has effects on the mammalian heart. These effects can include an increase in the force of contraction, and an elevation of the beating rate and the constriction of coronary arteries. Depending on the species studied, positive inotropic effects were strong, very modest, or absent, or even negative inotropic effects occurred. We can discern five dopamine receptors. In addition, the signal transduction by dopamine receptors and the regulation of the expression of cardiac dopamine receptors will be of interest to us, because this might be a tempting area of drug development. Dopamine acts in a species-dependent fashion on these cardiac dopamine receptors, but also on cardiac adrenergic receptors. We will discuss the utility of drugs that are currently available as tools to understand cardiac dopamine receptors. The molecule dopamine itself is present in the mammalian heart. Therefore, cardiac dopamine might act as an autocrine or paracrine compound in the mammalian heart. Dopamine itself might cause cardiac diseases. Moreover, the cardiac function of dopamine and the expression of dopamine receptors in the heart can be altered in diseases such as sepsis. Various drugs for cardiac and non-cardiac diseases are currently in the clinic that are, at least in part, agonists or antagonists at dopamine receptors. We define the research needs in order to understand dopamine receptors in the heart better. All in all, an update on the role of dopamine receptors in the human heart appears to be clinically relevant, and is thus presented here.
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Affiliation(s)
- Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, 06097 Halle, Germany
- Correspondence: ; Tel.: +49-345-557-1686; Fax: +49-345-557-1835
| | - Britt Hofmann
- Herzchirurgie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, 06097 Halle, Germany
| | - Stefan Dhein
- Medizinische Fakultät, Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, 04107 Leipzig, Germany
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, 06097 Halle, Germany
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4
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Subramanian H, Nikolaev VO. A-Kinase Anchoring Proteins in Cardiac Myocytes and Their Roles in Regulating Calcium Cycling. Cells 2023; 12:cells12030436. [PMID: 36766777 PMCID: PMC9913689 DOI: 10.3390/cells12030436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
The rate of calcium cycling and calcium transient amplitude are critical determinants for the efficient contraction and relaxation of the heart. Calcium-handling proteins in the cardiac myocyte are altered in heart failure, and restoring the proper function of those proteins is an effective potential therapeutic strategy. The calcium-handling proteins or their regulators are phosphorylated by a cAMP-dependent kinase (PKA), and thereby their activity is regulated. A-Kinase Anchoring Proteins (AKAPs) play a seminal role in orchestrating PKA and cAMP regulators in calcium handling and contractile machinery. This cAMP/PKA orchestration is crucial for the increased force and rate of contraction and relaxation of the heart in response to fight-or-flight. Knockout models and the few available preclinical models proved that the efficient targeting of AKAPs offers potential therapies tailor-made for improving defective calcium cycling. In this review, we highlight important studies that identified AKAPs and their regulatory roles in cardiac myocyte calcium cycling in health and disease.
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Affiliation(s)
- Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
| | - Viacheslav O. Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck
- Correspondence: (H.S.); (V.O.N.); Tel.: +49(0)40-7410-57383 (V.O.N.)
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5
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Carlson CR, Aronsen JM, Bergan-Dahl A, Moutty MC, Lunde M, Lunde PK, Jarstadmarken H, Wanichawan P, Pereira L, Kolstad TRS, Dalhus B, Subramanian H, Hille S, Christensen G, Müller OJ, Nikolaev V, Bers DM, Sjaastad I, Shen X, Louch WE, Klussmann E, Sejersted OM. AKAP18δ Anchors and Regulates CaMKII Activity at Phospholamban-SERCA2 and RYR. Circ Res 2022; 130:27-44. [PMID: 34814703 PMCID: PMC9500498 DOI: 10.1161/circresaha.120.317976] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND The sarcoplasmic reticulum (SR) Ca2+-ATPase 2 (SERCA2) mediates Ca2+ reuptake into SR and thereby promotes cardiomyocyte relaxation, whereas the ryanodine receptor (RYR) mediates Ca2+ release from SR and triggers contraction. Ca2+/CaMKII (CaM [calmodulin]-dependent protein kinase II) regulates activities of SERCA2 through phosphorylation of PLN (phospholamban) and RYR through direct phosphorylation. However, the mechanisms for CaMKIIδ anchoring to SERCA2-PLN and RYR and its regulation by local Ca2+ signals remain elusive. The objective of this study was to investigate CaMKIIδ anchoring and regulation at SERCA2-PLN and RYR. METHODS A role for AKAP18δ (A-kinase anchoring protein 18δ) in CaMKIIδ anchoring and regulation was analyzed by bioinformatics, peptide arrays, cell-permeant peptide technology, immunoprecipitations, pull downs, transfections, immunoblotting, proximity ligation, FRET-based CaMKII activity and ELISA-based assays, whole cell and SR vesicle fluorescence imaging, high-resolution microscopy, adenovirus transduction, adenoassociated virus injection, structural modeling, surface plasmon resonance, and alpha screen technology. RESULTS Our results show that AKAP18δ anchors and directly regulates CaMKIIδ activity at SERCA2-PLN and RYR, via 2 distinct AKAP18δ regions. An N-terminal region (AKAP18δ-N) inhibited CaMKIIδ through binding of a region homologous to the natural CaMKII inhibitor peptide and the Thr17-PLN region. AKAP18δ-N also bound CaM, introducing a second level of control. Conversely, AKAP18δ-C, which shares homology to neuronal CaMKIIα activator peptide (N2B-s), activated CaMKIIδ by lowering the apparent Ca2+ threshold for kinase activation and inducing CaM trapping. While AKAP18δ-C facilitated faster Ca2+ reuptake by SERCA2 and Ca2+ release through RYR, AKAP18δ-N had opposite effects. We propose a model where the 2 unique AKAP18δ regions fine-tune Ca2+-frequency-dependent activation of CaMKIIδ at SERCA2-PLN and RYR. CONCLUSIONS AKAP18δ anchors and functionally regulates CaMKII activity at PLN-SERCA2 and RYR, indicating a crucial role of AKAP18δ in regulation of the heartbeat. To our knowledge, this is the first protein shown to enhance CaMKII activity in heart and also the first AKAP (A-kinase anchoring protein) reported to anchor a CaMKII isoform, defining AKAP18δ also as a CaM-KAP.
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Affiliation(s)
- Cathrine R. Carlson
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Jan Magnus Aronsen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo Norway,Department of Pharmacology, Oslo University Hospital, Norway
| | - Anna Bergan-Dahl
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Marie Christine Moutty
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Marianne Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Per Kristian Lunde
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Hilde Jarstadmarken
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Pimthanya Wanichawan
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
| | - Laetitia Pereira
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Terje RS Kolstad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Bjørn Dalhus
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, 0424 Oslo, Norway,Department of Medical Biochemistry, Institute for Clinical Medicine, University of Oslo, 0424 Oslo, Norway
| | - Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany,German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany
| | - Susanne Hille
- German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany,Department of Internal Medicine III, University of Kiel, Kiel, Germany
| | - Geir Christensen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Oliver J. Müller
- German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany,Department of Internal Medicine III, University of Kiel, Kiel, Germany
| | - Viacheslav Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany,German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Germany
| | - Donald M. Bers
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
| | - Enno Klussmann
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany,German Centre for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Ole M. Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway,The KG Jebsen Cardiac Research Center, University of Oslo, Oslo, Norway
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6
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Chaklader M, Rothermel BA. Calcineurin in the heart: New horizons for an old friend. Cell Signal 2021; 87:110134. [PMID: 34454008 PMCID: PMC8908812 DOI: 10.1016/j.cellsig.2021.110134] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/10/2021] [Accepted: 08/23/2021] [Indexed: 01/20/2023]
Abstract
Calcineurin, also known as PP2B or PPP3, is a member of the PPP family of protein phosphatases that also includes PP1 and PP2A. Together these three phosphatases carryout the majority of dephosphorylation events in the heart. Calcineurin is distinct in that it is activated by the binding of calcium/calmodulin (Ca2+/CaM) and therefore acts as a node for integrating Ca2+ signals with changes in phosphorylation, two fundamental intracellular signaling cascades. In the heart, calcineurin is primarily thought of in the context of pathological cardiac remodeling, acting through the Nuclear Factor of Activated T-cell (NFAT) family of transcription factors. However, calcineurin activity is also essential for normal heart development and homeostasis in the adult heart. Furthermore, it is clear that NFAT-driven changes in transcription are not the only relevant processes initiated by calcineurin in the setting of pathological remodeling. There is a growing appreciation for the diversity of calcineurin substrates that can impact cardiac function as well as the diversity of mechanisms for targeting calcineurin to specific sub-cellular domains in cardiomyocytes and other cardiac cell types. Here, we will review the basics of calcineurin structure, regulation, and function in the context of cardiac biology. Particular attention will be given to: the development of improved tools to identify and validate new calcineurin substrates; recent studies identifying new calcineurin isoforms with unique properties and targeting mechanisms; and the role of calcineurin in cardiac development and regeneration.
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Affiliation(s)
- Malay Chaklader
- Departments of Internal Medicine (Division of Cardiology) and Molecular Biology, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Beverly A Rothermel
- Departments of Internal Medicine (Division of Cardiology) and Molecular Biology, University of Texas Southwestern Medical Centre, Dallas, TX, USA.
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7
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Colombe AS, Pidoux G. Cardiac cAMP-PKA Signaling Compartmentalization in Myocardial Infarction. Cells 2021; 10:cells10040922. [PMID: 33923648 PMCID: PMC8073060 DOI: 10.3390/cells10040922] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/02/2021] [Accepted: 04/13/2021] [Indexed: 02/07/2023] Open
Abstract
Under physiological conditions, cAMP signaling plays a key role in the regulation of cardiac function. Activation of this intracellular signaling pathway mirrors cardiomyocyte adaptation to various extracellular stimuli. Extracellular ligand binding to seven-transmembrane receptors (also known as GPCRs) with G proteins and adenylyl cyclases (ACs) modulate the intracellular cAMP content. Subsequently, this second messenger triggers activation of specific intracellular downstream effectors that ensure a proper cellular response. Therefore, it is essential for the cell to keep the cAMP signaling highly regulated in space and time. The temporal regulation depends on the activity of ACs and phosphodiesterases. By scaffolding key components of the cAMP signaling machinery, A-kinase anchoring proteins (AKAPs) coordinate both the spatial and temporal regulation. Myocardial infarction is one of the major causes of death in industrialized countries and is characterized by a prolonged cardiac ischemia. This leads to irreversible cardiomyocyte death and impairs cardiac function. Regardless of its causes, a chronic activation of cardiac cAMP signaling is established to compensate this loss. While this adaptation is primarily beneficial for contractile function, it turns out, in the long run, to be deleterious. This review compiles current knowledge about cardiac cAMP compartmentalization under physiological conditions and post-myocardial infarction when it appears to be profoundly impaired.
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Abstract
The field of cAMP signaling is witnessing exciting developments with the recognition that cAMP is compartmentalized and that spatial regulation of cAMP is critical for faithful signal coding. This realization has changed our understanding of cAMP signaling from a model in which cAMP connects a receptor at the plasma membrane to an intracellular effector in a linear pathway to a model in which cAMP signals propagate within a complex network of alternative branches and the specific functional outcome strictly depends on local regulation of cAMP levels and on selective activation of a limited number of branches within the network. In this review, we cover some of the early studies and summarize more recent evidence supporting the model of compartmentalized cAMP signaling, and we discuss how this knowledge is starting to provide original mechanistic insight into cell physiology and a novel framework for the identification of disease mechanisms that potentially opens new avenues for therapeutic interventions. SIGNIFICANCE STATEMENT: cAMP mediates the intracellular response to multiple hormones and neurotransmitters. Signal fidelity and accurate coordination of a plethora of different cellular functions is achieved via organization of multiprotein signalosomes and cAMP compartmentalization in subcellular nanodomains. Defining the organization and regulation of subcellular cAMP nanocompartments is necessary if we want to understand the complex functional ramifications of pharmacological treatments that target G protein-coupled receptors and for generating a blueprint that can be used to develop precision medicine interventions.
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Affiliation(s)
- Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Anna Zerio
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Miguel J Lobo
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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9
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Zhu YR, Jiang XX, Zheng Y, Xiong J, Wei D, Zhang DM. Cardiac function modulation depends on the A-kinase anchoring protein complex. J Cell Mol Med 2019; 23:7170-7179. [PMID: 31512389 PMCID: PMC6815827 DOI: 10.1111/jcmm.14659] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/27/2019] [Accepted: 08/06/2019] [Indexed: 12/26/2022] Open
Abstract
The A‐kinase anchoring proteins (AKAPs) are a group of structurally diverse proteins identified in various species and tissues. These proteins are able to anchor protein kinase and other signalling proteins to regulate cardiac function. Acting as a scaffold protein, AKAPs ensure specificity in signal transduction by enzymes close to their appropriate effectors and substrates. Over the decades, more than 70 different AKAPs have been discovered. Accumulative evidence indicates that AKAPs play crucial roles in the functional regulation of cardiac diseases, including cardiac hypertrophy, myofibre contractility dysfunction and arrhythmias. By anchoring different partner proteins (PKA, PKC, PKD and LTCCs), AKAPs take part in different regulatory pathways to function as regulators in the heart, and a damaged structure can influence the activities of these complexes. In this review, we highlight recent advances in AKAP‐associated protein complexes, focusing on local signalling events that are perturbed in cardiac diseases and their roles in interacting with ion channels and their regulatory molecules. These new findings suggest that AKAPs might have potential therapeutic value in patients with cardiac diseases, particularly malignant rhythm.
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Affiliation(s)
- Yan-Rong Zhu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Xiao-Xin Jiang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yaguo Zheng
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Jing Xiong
- Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Dongping Wei
- Department of Oncology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
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10
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Brautigan DL, Shenolikar S. Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates. Annu Rev Biochem 2019; 87:921-964. [PMID: 29925267 DOI: 10.1146/annurev-biochem-062917-012332] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity. This review focuses on the subunit and substrate interactions for PPP that depend on short linear motifs. Insights about these motifs from structures of holoenzymes open new opportunities for computational biology approaches to elucidate PPP networks. There is an expanding knowledge base of posttranslational modifications of PPP catalytic and regulatory subunits, as well as of their substrates, including phosphorylation, acetylation, and ubiquitination. Cross talk between these posttranslational modifications creates PPP-based signaling. Knowledge of PPP complexes, signaling clusters, as well as how PPPs communicate with each other in response to cellular signals should unlock the doors to PPP networks and signaling "clouds" that orchestrate and coordinate different aspects of cell physiology.
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Affiliation(s)
- David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA;
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore 169857
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11
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Ferreira M, Beullens M, Bollen M, Van Eynde A. Functions and therapeutic potential of protein phosphatase 1: Insights from mouse genetics. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2019; 1866:16-30. [PMID: 30056088 PMCID: PMC7114192 DOI: 10.1016/j.bbamcr.2018.07.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 07/16/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023]
Abstract
Protein phosphatase 1 (PP1) catalyzes more than half of all phosphoserine/threonine dephosphorylation reactions in mammalian cells. In vivo PP1 does not exist as a free catalytic subunit but is always associated with at least one regulatory PP1-interacting protein (PIP) to generate a large set of distinct holoenzymes. Each PP1 complex controls the dephosphorylation of only a small subset of PP1 substrates. We screened the literature for genetically engineered mouse models and identified models for all PP1 isoforms and 104 PIPs. PP1 itself and at least 49 PIPs were connected to human disease-associated phenotypes. Additionally, phenotypes related to 17 PIPs were clearly linked to altered PP1 function, while such information was lacking for 32 other PIPs. We propose structural reverse genetics, which combines structural characterization of proteins with mouse genetics, to identify new PP1-related therapeutic targets. The available mouse models confirm the pleiotropic action of PP1 in health and diseases.
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Affiliation(s)
- Mónica Ferreira
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Aleyde Van Eynde
- Laboratory of Biosignaling & Therapeutics, KU Leuven Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium.
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12
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Suryavanshi SV, Jadhav SM, McConnell BK. Polymorphisms/Mutations in A-Kinase Anchoring Proteins (AKAPs): Role in the Cardiovascular System. J Cardiovasc Dev Dis 2018; 5:E7. [PMID: 29370121 PMCID: PMC5872355 DOI: 10.3390/jcdd5010007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 01/23/2018] [Accepted: 01/24/2018] [Indexed: 02/06/2023] Open
Abstract
A-kinase anchoring proteins (AKAPs) belong to a family of scaffolding proteins that bind to protein kinase A (PKA) by definition and a variety of crucial proteins, including kinases, phosphatases, and phosphodiesterases. By scaffolding these proteins together, AKAPs build a "signalosome" at specific subcellular locations and compartmentalize PKA signaling. Thus, AKAPs are important for signal transduction after upstream activation of receptors ensuring accuracy and precision of intracellular PKA-dependent signaling pathways. Since their discovery in the 1980s, AKAPs have been studied extensively in the heart and have been proven essential in mediating cyclic adenosine monophosphate (cAMP)-PKA signaling. Although expression of AKAPs in the heart is very low, cardiac-specific knock-outs of several AKAPs have a noteworthy cardiac phenotype. Moreover, single nucleotide polymorphisms and genetic mutations in crucial cardiac proteins play a substantial role in the pathophysiology of cardiovascular diseases (CVDs). Despite the significant role of AKAPs in the cardiovascular system, a limited amount of research has focused on the role of genetic polymorphisms and/or mutations in AKAPs in increasing the risk of CVDs. This review attempts to overview the available literature on the polymorphisms/mutations in AKAPs and their effects on human health with a special focus on CVDs.
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Affiliation(s)
- Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Texas Medical Center, Houston, TX 77204, USA.
| | - Shweta M Jadhav
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Texas Medical Center, Houston, TX 77204, USA.
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston College of Pharmacy, Texas Medical Center, Houston, TX 77204, USA.
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Parra V, Rothermel BA. Calcineurin signaling in the heart: The importance of time and place. J Mol Cell Cardiol 2017; 103:121-136. [PMID: 28007541 PMCID: PMC5778886 DOI: 10.1016/j.yjmcc.2016.12.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/12/2016] [Accepted: 12/16/2016] [Indexed: 12/20/2022]
Abstract
The calcium-activated protein phosphatase, calcineurin, lies at the intersection of protein phosphorylation and calcium signaling cascades, where it provides an essential nodal point for coordination between these two fundamental modes of intracellular communication. In excitatory cells, such as neurons and cardiomyocytes, that experience rapid and frequent changes in cytoplasmic calcium, calcineurin protein levels are exceptionally high, suggesting that these cells require high levels of calcineurin activity. Yet, it is widely recognized that excessive activation of calcineurin in the heart contributes to pathological hypertrophic remodeling and the progression to failure. How does a calcium activated enzyme function in the calcium-rich environment of the continuously contracting heart without pathological consequences? This review will discuss the wide range of calcineurin substrates relevant to cardiovascular health and the mechanisms calcineurin uses to find and act on appropriate substrates in the appropriate location while potentially avoiding others. Fundamental differences in calcineurin signaling in neonatal verses adult cardiomyocytes will be addressed as well as the importance of maintaining heterogeneity in calcineurin activity across the myocardium. Finally, we will discuss how circadian oscillations in calcineurin activity may facilitate integration with other essential but conflicting processes, allowing a healthy heart to reap the benefits of calcineurin signaling while avoiding the detrimental consequences of sustained calcineurin activity that can culminate in heart failure.
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Affiliation(s)
- Valentina Parra
- Advanced Centre for Chronic Disease (ACCDiS), Facultad Ciencias Quimicas y Farmaceuticas, Universidad de Chile, Santiago,Chile; Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chie, Santiago, Chile
| | - Beverly A Rothermel
- Department of Internal Medicine (Cardiology Division), University of Texas Southwestern Medical Centre, Dallas, TX, USA; Department of Molecular Biology, University of Texas Southwestern Medical Centre, Dallas, TX, USA.
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Weber S, Meyer-Roxlau S, El-Armouche A. Role of protein phosphatase inhibitor-1 in cardiac beta adrenergic pathway. J Mol Cell Cardiol 2016; 101:116-126. [PMID: 27639308 DOI: 10.1016/j.yjmcc.2016.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/05/2016] [Accepted: 09/13/2016] [Indexed: 01/08/2023]
Abstract
Phosphoproteomic studies have shown that about one third of all cardiac proteins are reversibly phosphorylated, affecting virtually every cellular signaling pathway. The reversibility of this process is orchestrated by the opposing enzymatic activity of kinases and phosphatases. Conversely, imbalances in subcellular protein phosphorylation patterns are a hallmark of many cardiovascular diseases including heart failure and cardiac arrhythmias. While numerous studies have revealed excessive beta-adrenergic signaling followed by deregulated kinase expression or activity as a major driver of the latter cardiac pathologies, far less is known about the beta-adrenergic regulation of their phosphatase counterparts. In fact, most of the limited knowledge stems from the detailed analysis of the endogenous inhibitor of the protein phosphatase 1 (I-1) in cellular and animal models. I-1 acts as a nodal point between adrenergic and putatively non-adrenergic cardiac signaling pathways and is able to influence widespread cellular functions of protein phosphatase 1 which are contributing to cardiac health and disease, e.g. Ca2+ handling, sarcomere contractility and glucose metabolism. Finally, nearly all of these studies agree that I-1 is a promising drug target on the one hand but the outcome of its pharmacological regulation maybe extremely context-dependent on the other hand, thus warranting for careful interpretation of past and future experimental results. In this respect we will: 1) comprehensively review the current knowledge about structural, functional and regulatory properties of I-1 within the heart 2) highlight current working hypothesis and potential I-1 mediated disease mechanisms 3) discuss state-of-the-art knowledge and future prospects of a potential therapeutic strategy targeting I-1 by restoring the balance of cardiac protein phosphorylation.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
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Yu L, Xu J, Minobe E, Kameyama A, Yang L, Feng R, Hao L, Kameyama M. Role of protein phosphatases in the run down of guinea pig cardiac Cav1.2 Ca2+ channels. Am J Physiol Cell Physiol 2016; 310:C773-9. [DOI: 10.1152/ajpcell.00199.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 01/05/2016] [Indexed: 12/26/2022]
Abstract
This study aimed to investigate protein phosphatases involved in the run down of Cav1.2 Ca2+ channels. Single ventricular myocytes obtained from adult guinea pig hearts were used to record Ca2+ channel currents with the patch-clamp technique. Calmodulin (CaM) and ATP were used to restore channel activity in inside-out patches. Inhibitors of protein phosphatases were applied to investigate the role of phosphatases. The specific protein phosphatase type 1 (PP1) inhibitor (PP1 inhibitor-2) and protein phosphatase type 2A (PP2A) inhibitor (fostriecin) abolished the slow run down of Cav1.2 Ca2+ channels, which was evident as the time-dependent attenuation of the reversing effect of CaM/ATP on the run down. However, protein phosphatase type 2B (PP2B, calcineurin) inhibitor cyclosporine A together with cyclophilin A had no effect on the channel run down. Furthermore, PP1 inhibitor-2 mainly prolonged the open time constants of the channel, specifically, the slow open time. Fostriecin primarily shortened the slow close time constants. Our data suggest that PP1 and PP2A were involved in the slow phase of Cav1.2 Ca2+ channel run down. In addition, they exerted different effects on the open-close kinetics of the channel. All above support the view that PP1 and PP2A may dephosphorylate distinct phosphorylation sites on the Cav1.2 Ca2+ channel.
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Affiliation(s)
- Lifeng Yu
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Asako Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lei Yang
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Rui Feng
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
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Abstract
In the heart, Ca(2+) signals regulate a variety of biological functions ranging from contractility to gene expression, cellular hypertrophy and death. In this review, we summarize the role of local Ca(2+) homeostasis in these processes in healthy cardiac muscle cells, and highlight how mismanaged Ca(2+) handling contributes to the pathophysiology of conditions such as cardiac arrhythmia, ischemic heart disease, cardiac hypertrophy and heart failure. Aiming to provide an introduction to the field with a clinical perspective, we also indicate how current and future therapies may modulate cardiomyocytes Ca(2+) handling for the treatment of patients.
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Affiliation(s)
| | - William E Louch
- b Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo , Oslo , Norway
| | - Ivar Sjaastad
- b Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo , Oslo , Norway
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17
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Weber S, Meyer-Roxlau S, Wagner M, Dobrev D, El-Armouche A. Counteracting Protein Kinase Activity in the Heart: The Multiple Roles of Protein Phosphatases. Front Pharmacol 2015; 6:270. [PMID: 26617522 PMCID: PMC4643138 DOI: 10.3389/fphar.2015.00270] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/28/2015] [Indexed: 12/19/2022] Open
Abstract
Decades of cardiovascular research have shown that variable and flexible levels of protein phosphorylation are necessary to maintain cardiac function. A delicate balance between phosphorylated and dephosphorylated states of proteins is guaranteed by a complex interplay of protein kinases (PKs) and phosphatases. Serine/threonine phosphatases, in particular members of the protein phosphatase (PP) family govern dephosphorylation of the majority of these cardiac proteins. Recent findings have however shown that PPs do not only dephosphorylate previously phosphorylated proteins as a passive control mechanism but are capable to actively control PK activity via different direct and indirect signaling pathways. These control mechanisms can take place on (epi-)genetic, (post-)transcriptional, and (post-)translational levels. In addition PPs themselves are targets of a plethora of proteinaceous interaction partner regulating their endogenous activity, thus adding another level of complexity and feedback control toward this system. Finally, novel approaches are underway to achieve spatiotemporal pharmacologic control of PPs which in turn can be used to fine-tune misleaded PK activity in heart disease. Taken together, this review comprehensively summarizes the major aspects of PP-mediated PK regulation and discusses the subsequent consequences of deregulated PP activity for cardiovascular diseases in depth.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Michael Wagner
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, West German Heart and Vascular Center , Essen, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
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18
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Analysis of AKAP7γ Dimerization. JOURNAL OF SIGNAL TRANSDUCTION 2015; 2015:371626. [PMID: 26417456 PMCID: PMC4568377 DOI: 10.1155/2015/371626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/02/2015] [Accepted: 07/05/2015] [Indexed: 12/18/2022]
Abstract
A-kinase anchoring proteins (AKAPs) constitute a family of scaffolding proteins that contribute to spatiotemporal regulation of PKA-mediated phosphorylation events. In particular, AKAP7 is a family of alternatively spliced proteins that participates in cardiac calcium dynamics. Here, we demonstrate via pull-down from transfected cells and by direct protein-protein association that AKAP7γ self-associates. Self-association appears to be an isoform specific phenomenon, as AKAP7α did not associate with itself or with AKAP7γ. However, AKAP7γ did associate with AKAP7δ, suggesting the long isoforms of the AKAP can form heterodimers. Surface plasmon resonance found that the AKAP7γ self-association occurs via two high affinity binding sites with K D values in the low nanomolar range. Mapping of the binding sites by peptide array reveals that AKAP7γ interacts with itself through multiple regions. Photon counting histogram analysis (PCH) of AKAP7γ-EGFP expressed in HEK-293 cells confirmed that AKAP7γ-EGFP self-associates in a cellular context. Lastly, computational modeling of PKA dynamics within AKAP7γ complexes suggests that oligomerization may augment phosphorylation of scaffolded PKA substrates. In conclusion, our study reveals that AKAP7γ forms both homo- and heterodimers with the long isoforms of the AKAP and that this phenomenon could be an important step in mediating effective substrate phosphorylation in cellular microdomains.
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Nygren PJ, Scott JD. Therapeutic strategies for anchored kinases and phosphatases: exploiting short linear motifs and intrinsic disorder. Front Pharmacol 2015; 6:158. [PMID: 26283967 PMCID: PMC4516873 DOI: 10.3389/fphar.2015.00158] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/16/2015] [Indexed: 12/17/2022] Open
Abstract
Phosphorylation events that occur in response to the second messenger cAMP are controlled spatially and temporally by protein kinase A (PKA) interacting with A-kinase anchoring proteins (AKAPs). Recent advances in understanding the structural basis for this interaction have reinforced the hypothesis that AKAPs create spatially constrained signaling microdomains. This has led to the realization that the PKA/AKAP interface is a potential drug target for modulating a plethora of cell-signaling events. Pharmacological disruption of kinase–AKAP interactions has previously been explored for disease treatment and remains an interesting area of research. However, disrupting or enhancing the association of phosphatases with AKAPs is a therapeutic concept of equal promise, particularly since they oppose the actions of many anchored kinases. Accordingly, numerous AKAPs bind phosphatases such as protein phosphatase 1 (PP1), calcineurin (PP2B), and PP2A. These multimodal signaling hubs are equally able to control the addition of phosphate groups onto target substrates, as well as the removal of these phosphate groups. In this review, we describe recent advances in structural analysis of kinase and phosphatase interactions with AKAPs, and suggest future possibilities for targeting these interactions for therapeutic benefit.
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Affiliation(s)
- Patrick J Nygren
- Department of Pharmacology, University of Washington Seattle, WA, USA ; Howard Hughes Medical Institute Chevy Chase, MD, USA
| | - John D Scott
- Department of Pharmacology, University of Washington Seattle, WA, USA ; Howard Hughes Medical Institute Chevy Chase, MD, USA
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Rigatti M, Le AV, Gerber C, Moraru II, Dodge-Kafka KL. Phosphorylation state-dependent interaction between AKAP7δ/γ and phospholamban increases phospholamban phosphorylation. Cell Signal 2015; 27:1807-15. [PMID: 26027516 DOI: 10.1016/j.cellsig.2015.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 05/07/2015] [Indexed: 12/01/2022]
Abstract
Changes in heart rate and contractility in response to sympathetic stimulation occur via activation of cAMP dependent protein kinase A (PKA), leading to phosphorylation of numerous substrates that alter Ca(2+) cycling. Phosphorylation of these substrates is coordinated by A-kinase anchoring proteins (AKAPs), which recruit PKA to specific substrates [1]. Phosphorylation of the PKA substrate phospholamban (PLB) is a critical determinant of Ca(2+) re-entry into the sarcoplasmic reticulum and is coordinated by AKAP7δ/γ [2,3]. Here, we further these findings by showing that phosphorylation of PLB requires interaction with AKAP7δ/γ and that this interaction occurs only when PLB is unphosphorylated. Additionally, we find that two mutants of PLB (R9C and Δ14), which are associated with dilated cardiomyopathy in humans, prevent association with AKAP7δ/γ and display reduced phosphorylation in vitro. This finding implicates the AKAP7δ/γ-PLB interaction in the pathology of the disease phenotype. Further exploration of the AKAP7δ/γ-PLB association demonstrated a phosphorylation state-dependence of the interaction. Computational modeling revealed that this mode of interaction allows for small amounts of AKAP and PKA (100-200nM) to regulate the phosphorylation of large quantities of PLB (50μM). Our results confirm that AKAP7γ/δ binding to PLB is important for phosphorylation of PLB, and describe a novel phosphorylation state-dependent binding mechanism that explains how phosphorylation of highly abundant PKA substrates can be regulated by AKAPs present at ~100-200 fold lower concentrations.
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Affiliation(s)
- Marc Rigatti
- Pat and Jim Calhoun Center for Cardiovascular Research, UCONN Health, 263 Farmington Ave, Farmington, CT 06030, USA; The Richard D. Berlin Center for Cell Analysis & Modeling, UCONN Health, 400 Farmington Ave, Farmington, CT 06030, USA
| | - Andrew V Le
- Pat and Jim Calhoun Center for Cardiovascular Research, UCONN Health, 263 Farmington Ave, Farmington, CT 06030, USA; The Richard D. Berlin Center for Cell Analysis & Modeling, UCONN Health, 400 Farmington Ave, Farmington, CT 06030, USA
| | - Claire Gerber
- Pat and Jim Calhoun Center for Cardiovascular Research, UCONN Health, 263 Farmington Ave, Farmington, CT 06030, USA; The Richard D. Berlin Center for Cell Analysis & Modeling, UCONN Health, 400 Farmington Ave, Farmington, CT 06030, USA
| | - Ion I Moraru
- Pat and Jim Calhoun Center for Cardiovascular Research, UCONN Health, 263 Farmington Ave, Farmington, CT 06030, USA; The Richard D. Berlin Center for Cell Analysis & Modeling, UCONN Health, 400 Farmington Ave, Farmington, CT 06030, USA
| | - Kimberly L Dodge-Kafka
- Pat and Jim Calhoun Center for Cardiovascular Research, UCONN Health, 263 Farmington Ave, Farmington, CT 06030, USA; The Richard D. Berlin Center for Cell Analysis & Modeling, UCONN Health, 400 Farmington Ave, Farmington, CT 06030, USA.
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Ahmad F, Shen W, Vandeput F, Szabo-Fresnais N, Krall J, Degerman E, Goetz F, Klussmann E, Movsesian M, Manganiello V. Regulation of sarcoplasmic reticulum Ca2+ ATPase 2 (SERCA2) activity by phosphodiesterase 3A (PDE3A) in human myocardium: phosphorylation-dependent interaction of PDE3A1 with SERCA2. J Biol Chem 2015; 290:6763-76. [PMID: 25593322 DOI: 10.1074/jbc.m115.638585] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclic nucleotide phosphodiesterase 3A (PDE3) regulates cAMP-mediated signaling in the heart, and PDE3 inhibitors augment contractility in patients with heart failure. Studies in mice showed that PDE3A, not PDE3B, is the subfamily responsible for these inotropic effects and that murine PDE3A1 associates with sarcoplasmic reticulum Ca(2+) ATPase 2 (SERCA2), phospholamban (PLB), and AKAP18 in a multiprotein signalosome in human sarcoplasmic reticulum (SR). Immunohistochemical staining demonstrated that PDE3A co-localizes in Z-bands of human cardiac myocytes with desmin, SERCA2, PLB, and AKAP18. In human SR fractions, cAMP increased PLB phosphorylation and SERCA2 activity; this was potentiated by PDE3 inhibition but not by PDE4 inhibition. During gel filtration chromatography of solubilized SR membranes, PDE3 activity was recovered in distinct high molecular weight (HMW) and low molecular weight (LMW) peaks. HMW peaks contained PDE3A1 and PDE3A2, whereas LMW peaks contained PDE3A1, PDE3A2, and PDE3A3. Western blotting showed that endogenous HMW PDE3A1 was the principal PKA-phosphorylated isoform. Phosphorylation of endogenous PDE3A by rPKAc increased cAMP-hydrolytic activity, correlated with shift of PDE3A from LMW to HMW peaks, and increased co-immunoprecipitation of SERCA2, cav3, PKA regulatory subunit (PKARII), PP2A, and AKAP18 with PDE3A. In experiments with recombinant proteins, phosphorylation of recombinant human PDE3A isoforms by recombinant PKA catalytic subunit increased co-immunoprecipitation with rSERCA2 and rat rAKAP18 (recombinant AKAP18). Deletion of the recombinant human PDE3A1/PDE3A2 N terminus blocked interactions with recombinant SERCA2. Serine-to-alanine substitutions identified Ser-292/Ser-293, a site unique to human PDE3A1, as the principal site regulating its interaction with SERCA2. These results indicate that phosphorylation of human PDE3A1 at a PKA site in its unique N-terminal extension promotes its incorporation into SERCA2/AKAP18 signalosomes, where it regulates a discrete cAMP pool that controls contractility by modulating phosphorylation-dependent protein-protein interactions, PLB phosphorylation, and SERCA2 activity.
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Affiliation(s)
- Faiyaz Ahmad
- From the Cardiovascular Pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892,
| | - Weixing Shen
- From the Cardiovascular Pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Fabrice Vandeput
- VA Salt Lake City Health Care System and University of Utah, Salt Lake City, Utah
| | | | - Judith Krall
- VA Salt Lake City Health Care System and University of Utah, Salt Lake City, Utah
| | - Eva Degerman
- Department of Experimental Medical Science, Division for Diabetes, Metabolism, and Endocrinology, Lund University, Lund, Sweden
| | - Frank Goetz
- Max Delbrueck Center for Molecular Medicine Berlin-Buch (MDC), 13125 Germany, and
| | - Enno Klussmann
- Max Delbrueck Center for Molecular Medicine Berlin-Buch (MDC), 13125 Germany, and DZHK, German Centre for Cardiovascular Research, 13347 Berlin, Germany
| | - Matthew Movsesian
- VA Salt Lake City Health Care System and University of Utah, Salt Lake City, Utah
| | - Vincent Manganiello
- From the Cardiovascular Pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
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Gomez-Chang E, Espinosa-Garcia MT, Olvera-Sanchez S, Flores-Herrera O, Martinez F. PKA tightly bound to human placental mitochondria participates in steroidogenesis and is not modified by cAMP. Placenta 2014; 35:748-62. [PMID: 25012296 DOI: 10.1016/j.placenta.2014.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 06/10/2014] [Accepted: 06/12/2014] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Protein phosphorylation plays an important role in the modulation of steroidogenesis and it depends on the activation of different signaling cascades. Previous data showed that PKA activity is related to steroidogenesis in mitochondria from syncytiotrophoblast of human placenta (HPM). PKA localization and contribution in progesterone synthesis and protein phosphorylation of HPM was assessed in this work. METHODS Placental mitochondria and submitochondrial fractions were used. Catalytic and regulatory PKA subunits were identified by Western blot. PKA activity was determined by the incorporation of (32)P into proteins in the presence or absence of specific inhibitors. The effect of PKA activators and inhibitors on steroidogenesis and protein phosphorylation in HPM was tested by radioimmunoassay and autoradiography. RESULTS The PKAα catalytic subunit was distributed in all the submitochondrial fractions whereas βII regulatory subunit was the main isoform observed in both the outer and inner membranes of HPM. PKA located in the inner membrane showed the highest activity. Progesterone synthesis and mitochondrial protein phosphorylation are modified by inhibitors of PKA catalytic subunit but are neither sensitive to inhibitors of the regulatory subunit nor to activators of the holoenzyme. DISCUSSION The lack of response in the presence of PKA activators and inhibitors of the regulatory subunit suggests that the activation of intramitochondrial PKA cannot be prevented or further activated. CONCLUSIONS The phosphorylating activity of PKA inside HPM could be an important component of the steroidogenesis transduction cascade, probably exerting its effects by direct phosphorylation of its substrates or by modulating other kinases and phosphatases.
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Affiliation(s)
- E Gomez-Chang
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - M T Espinosa-Garcia
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - S Olvera-Sanchez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - O Flores-Herrera
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico
| | - F Martinez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado Postal 70-159, Coyoacán 04510, Mexico City, Mexico.
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Vafiadaki E, Arvanitis DA, Sanoudou D, Kranias EG. Identification of a protein phosphatase-1/phospholamban complex that is regulated by cAMP-dependent phosphorylation. PLoS One 2013; 8:e80867. [PMID: 24244723 PMCID: PMC3828283 DOI: 10.1371/journal.pone.0080867] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/17/2013] [Indexed: 11/19/2022] Open
Abstract
In human and experimental heart failure, the activity of the type 1 phosphatase is significantly increased, associated with dephosphorylation of phospholamban, inhibition of the sarco(endo)plasmic reticulum Ca2+ transport ATPase (SERCA2a) and depressed function. In the current study, we investigated the molecular mechanisms controlling protein phosphatase-1 activity. Using recombinant proteins and complementary in vitro binding studies, we identified a multi-protein complex centered on protein phosphatase-1 that includes its muscle specific glycogen-targeting subunit GM and substrate phospholamban. GM interacts directly with phospholamban and this association is mediated by the cytosolic regions of the proteins. Our findings suggest the involvement of GM in mediating formation of the phosphatase-1/GM/phospholamban complex through the direct and independent interactions of GM with both protein phosphatase-1 and phospholamban. Importantly, the protein phosphatase-1/GM/phospholamban complex dissociates upon protein kinase A phosphorylation, indicating its significance in the β-adrenergic signalling axis. Moreover, protein phosphatase-1 activity is regulated by two binding partners, inhibitor-1 and the small heat shock protein 20, Hsp20. Indeed, human genetic variants of inhibitor-1 (G147D) or Hsp20 (P20L) result in reduced binding and inhibition of protein phosphatase-1, suggesting aberrant enzymatic regulation in human carriers. These findings provide insights into the mechanisms underlying fine-tuned regulation of protein phosphatase-1 and its impact on the SERCA2/phospholamban interactome in cardiac function.
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Affiliation(s)
- Elizabeth Vafiadaki
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Demetrios A. Arvanitis
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Despina Sanoudou
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
- Department of Pharmacology, Medical School, University of Athens, Greece
| | - Evangelia G. Kranias
- Molecular Biology Division, Biomedical Research Foundation, Academy of Athens, Athens, Greece
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
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Heijman J, Dewenter M, El-Armouche A, Dobrev D. Function and regulation of serine/threonine phosphatases in the healthy and diseased heart. J Mol Cell Cardiol 2013; 64:90-8. [PMID: 24051368 DOI: 10.1016/j.yjmcc.2013.09.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/03/2013] [Accepted: 09/08/2013] [Indexed: 12/20/2022]
Abstract
Protein phosphorylation is a major control mechanism of a wide range of physiological processes and plays an important role in cardiac pathophysiology. Serine/threonine protein phosphatases control the dephosphorylation of a variety of cardiac proteins, thereby fine-tuning cardiac electrophysiology and function. Specificity of protein phosphatases type-1 and type-2A is achieved by multiprotein complexes that target the catalytic subunits to specific subcellular domains. Here, we describe the composition, regulation and target substrates of serine/threonine phosphatases in the heart. In addition, we provide an overview of pharmacological tools and genetic models to study the role of cardiac phosphatases. Finally, we review the role of protein phosphatases in the diseased heart, particularly in ventricular arrhythmias and atrial fibrillation and discuss their role as potential therapeutic targets.
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Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, 45122 Essen, Germany
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Butler T, Paul J, Europe-Finner N, Smith R, Chan EC. Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility. Am J Physiol Cell Physiol 2013; 304:C485-504. [PMID: 23325405 DOI: 10.1152/ajpcell.00161.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.
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Affiliation(s)
- Trent Butler
- Mothers and Babies Research Centre, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia
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Cardiomyocytes from AKAP7 knockout mice respond normally to adrenergic stimulation. Proc Natl Acad Sci U S A 2012; 109:17099-104. [PMID: 23035250 DOI: 10.1073/pnas.1215219109] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein kinase A (PKA) is activated during sympathetic stimulation of the heart and phosphorylates key proteins involved in cardiac Ca(2+) handling, including the L-type Ca(2+) channel (Ca(V)1.2) and phospholamban (PLN). This results in acceleration and amplification of the beat-to-beat changes in cytosolic Ca(2+) in cardiomyocytes and, in turn, an increased rate and force of contraction. PKA is held in proximity to its substrates by protein scaffolds called A kinase anchoring proteins (AKAPs). It has been suggested that the short and long isoforms of AKAP7 (also called AKAP15/18) localize PKA in complexes with Ca(V)1.2 and PLN, respectively. We generated an AKAP7 KO mouse in which all isoforms were deleted and tested whether Ca(2+) current, intracellular Ca(2+) concentration, or Ca(2+) reuptake were impaired in isolated adult ventricular cardiomyocytes following stimulation with the β-adrenergic agonist isoproterenol. KO cardiomyocytes responded normally to adrenergic stimulation, as measured by whole-cell patch clamp or a fluorescent intracellular Ca(2+) indicator. Phosphorylation of Ca(V)1.2 and PLN were also unaffected by genetic deletion of AKAP7. Immunoblot and RT-PCR revealed that only the long isoforms of AKAP7 were detectable in ventricular cardiomyocytes. The results indicate that AKAP7 is not required for regulation of Ca(2+) handling in mouse cardiomyocytes.
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Abstract
The second messengers cAMP and cGMP exist in multiple discrete compartments and regulate a variety of biological processes in the heart. The cyclic nucleotide phosphodiesterases, by catalyzing the hydrolysis of cAMP and cGMP, play crucial roles in controlling the amplitude, duration, and compartmentalization of cyclic nucleotide signaling. Over 60 phosphodiesterase isoforms, grouped into 11 families, have been discovered to date. In the heart, both cAMP- and cGMP-hydrolyzing phosphodiesterases play important roles in physiology and pathology. At least 7 of the 11 phosphodiesterase family members appear to be expressed in the myocardium, and evidence supports phosphodiesterase involvement in regulation of many processes important for normal cardiac function including pacemaking and contractility, as well as many pathological processes including remodeling and myocyte apoptosis. Pharmacological inhibitors for a number of phosphodiesterase families have also been used clinically or preclinically to treat several types of cardiovascular disease. In addition, phosphodiesterase inhibitors are also being considered for treatment of many forms of disease outside the cardiovascular system, raising the possibility of cardiovascular side effects of such agents. This review will discuss the roles of phosphodiesterases in the heart, in terms of expression patterns, regulation, and involvement in physiological and pathological functions. Additionally, the cardiac effects of various phosphodiesterase inhibitors, both potentially beneficial and detrimental, will be discussed.
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Affiliation(s)
- W. E. Knight
- Department of Pharmacology and Physiology, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
- Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - C. Yan
- Department of Medicine, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Abstract
Directed protein phosphorylation is indisputably critical for a multitude of cellular processes. A growing body of research demonstrates A kinase anchoring proteins (AKAPs) to mediate a significant number of phosphorylation events in the heart. By acting as molecular tethers for the regulatory subunit of protein kinase A, AKAPs focus kinase activity onto specific substrate. In the time since their discovery, the AKAP model has evolved in appreciation of the broader role these scaffolds play in coordinating multiple signaling enzymes to efficiently regulate dynamic cellular processes. The focus of this review is on the emerging role of AKAPs in regulating the 3 main cardiac phosphatases: Protein Phosphatase 1 by AKAP18 and Yotiao, and Protein Phosphatases 2A and 2B by muscle specific A-kinase anchoring protein.
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Johnson KR, Nicodemus-Johnson J, Carnegie GK, Danziger RS. Molecular evolution of A-kinase anchoring protein (AKAP)-7: implications in comparative PKA compartmentalization. BMC Evol Biol 2012; 12:125. [PMID: 22834419 PMCID: PMC3508976 DOI: 10.1186/1471-2148-12-125] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 07/10/2012] [Indexed: 11/10/2022] Open
Abstract
Background A-Kinase Anchoring Proteins (AKAPs) are molecular scaffolding proteins mediating the assembly of multi-protein complexes containing cAMP-dependent protein kinase A (PKA), directing the kinase in discrete subcellular locations. Splice variants from the AKAP7 gene (AKAP15/18) are vital components of neuronal and cardiac phosphatase complexes, ion channels, cardiac Ca2+ handling and renal water transport. Results Shown in evolutionary analyses, the formation of the AKAP7-RI/RII binding domain (required for AKAP/PKA-R interaction) corresponds to vertebrate-specific gene duplication events in the PKA-RI/RII subunits. Species analyses of AKAP7 splice variants shows the ancestral AKAP7 splice variant is AKAP7α, while the ancestral long form AKAP7 splice variant is AKAP7γ. Multi-species AKAP7 gene alignments, show the recent formation of AKAP7δ occurs with the loss of native AKAP7γ in rats and basal primates. AKAP7 gene alignments and two dimensional Western analyses indicate that AKAP7γ is produced from an internal translation-start site that is present in the AKAP7δ cDNA of mice and humans but absent in rats. Immunofluorescence analysis of AKAP7 protein localization in both rat and mouse heart suggests AKAP7γ replaces AKAP7δ at the cardiac sarcoplasmic reticulum in species other than rat. DNA sequencing identified Human AKAP7δ insertion-deletions (indels) that promote the production of AKAP7γ instead of AKAP7δ. Conclusions This AKAP7 molecular evolution study shows that these vital scaffolding proteins developed in ancestral vertebrates and that independent mutations in the AKAP7 genes of rodents and early primates has resulted in the recent formation of AKAP7δ, a splice variant of likely lesser importance in humans than currently described.
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Affiliation(s)
- Keven R Johnson
- Department of Medicine, University of Illinois, Chicago, IL, USA
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Abstract
A kinase anchoring proteins (AKAPs) bind multiple signaling proteins and have subcellular targeting domains that allow them to greatly impact cellular signaling. AKAPs localize, specify, amplify, and accelerate signal transduction within the cell by bringing signaling proteins together in space and time. AKAPs also organize higher-order network motifs such as feed forward and feedback loops that may create complex network responses, including adaptation, oscillation, and ultrasensitivity. Computational models have begun to provide an insight into how AKAPs regulate signaling dynamics and cardiovascular pathophysiology. Models of mitogen-activated protein kinase and epidermal growth factor receptor scaffolds have revealed additional design principles and new methods for representing signaling scaffolds mathematically. Coupling computational modeling with quantitative experimental approaches will be increasingly necessary for dissecting the diverse information processing functions performed by AKAP signaling complexes.
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Diviani D, Dodge-Kafka KL, Li J, Kapiloff MS. A-kinase anchoring proteins: scaffolding proteins in the heart. Am J Physiol Heart Circ Physiol 2011; 301:H1742-53. [PMID: 21856912 DOI: 10.1152/ajpheart.00569.2011] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The pleiotropic cyclic nucleotide cAMP is the primary second messenger responsible for autonomic regulation of cardiac inotropy, chronotropy, and lusitropy. Under conditions of prolonged catecholaminergic stimulation, cAMP also contributes to the induction of both cardiac myocyte hypertrophy and apoptosis. The formation of localized, multiprotein complexes that contain different combinations of cAMP effectors and regulatory enzymes provides the architectural infrastructure for the specialization of the cAMP signaling network. Scaffolds that bind protein kinase A are called "A-kinase anchoring proteins" (AKAPs). In this review, we discuss recent advances in our understanding of how PKA is compartmentalized within the cardiac myocyte by AKAPs and how AKAP complexes modulate cardiac function in both health and disease.
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Affiliation(s)
- Dario Diviani
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et Médecine, Université de Lausanne, Lausanne, Switzerland.
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AKAPs: the architectural underpinnings of local cAMP signaling. J Mol Cell Cardiol 2011; 52:351-8. [PMID: 21600214 DOI: 10.1016/j.yjmcc.2011.05.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/28/2011] [Accepted: 05/03/2011] [Indexed: 12/13/2022]
Abstract
The cAMP-dependent protein kinase A (PKA) is targeted to specific compartments in the cardiac myocyte by A-kinase anchoring proteins (AKAPs), a diverse set of scaffold proteins that have been implicated in the regulation of excitation-contraction coupling and cardiac remodeling. AKAPs bind not only PKA, but also a large variety of structural and signaling molecules. In this review, we discuss the basic concepts underlying compartmentation of cAMP and PKA signaling, as well as a few of the individual AKAPs that have been shown to be functionally relevant in the heart. This article is part of a Special Issue entitled "Local Signaling in Myocytes".
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