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Subramanian H, Nikolaev VO. AKAP12 Overexpression Affects Cardiac Function via PDE8. Circ Res 2024; 134:1023-1025. [PMID: 38603476 DOI: 10.1161/circresaha.124.324475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Affiliation(s)
- Hariharan Subramanian
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (H.S., V.O.N.)
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany (H.S., V.O.N.)
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Germany (H.S., V.O.N.)
- German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Germany (H.S., V.O.N.)
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2
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Interaction between A-kinase anchoring protein 5 and protein kinase A mediates CaMKII/HDAC signaling to inhibit cardiomyocyte hypertrophy after hypoxic reoxygenation. Cell Signal 2023; 103:110569. [PMID: 36565899 DOI: 10.1016/j.cellsig.2022.110569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
We reported that A-kinase anchoring protein 5 (AKAP5) played a role in cardiomyocyte apoptosis after hypoxia-reoxygenation (H/R). The role of AKAP5 in cardiomyocyte hypertrophy has not been fully elucidated. Herein we investigated whether AKAP5 regulates cardiomyocyte hypertrophy through calcium/calmodulin-dependent protein kinase II (CaMKII). After H/R, deficiency of AKAP5 in H9C2 cardiomyocytes and neonatal rat cardiac myocytes activated CaMKII and stimulated cardiomyocyte hypertrophy. AKAP5 upregulation limited this. Low expression of AKAP5 increased CaMKII interaction with histone deacetylases 4/5 (HDAC4/5) and increased nuclear export of HDAC4/5. In addition, AKAP5 interactions with protein kinase A (PKA) and phospholamban (PLN) were diminished. Moreover, the phosphorylation of PLN was decreased, and intracellular calcium increased. Interference of this process with St-Ht31 increased CaMKII signaling, decreased PLN phosphorylation and promoted post-H/R cell hypertrophy. And PKA-anchoring deficient AKAP5ΔPKA could not attenuate hypoxia-reoxygenation-induced cardiomyocyte hypertrophy, but AKAP5 could. Altogether, AKAP5 downregulation exacerbated H/R-induced hypertrophy in cardiomyocytes. This was due to, in part, to less in AKAP5-PKA interaction and the accumulation of intracellular Ca2+ with a subsequent increase in CaMKII activity.
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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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4
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Mani A. PDE4DIP in health and diseases. Cell Signal 2022; 94:110322. [PMID: 35346821 PMCID: PMC9618167 DOI: 10.1016/j.cellsig.2022.110322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 11/15/2022]
Abstract
Cyclic-AMP (cAMP), the first second messenger to be identified, is synthesized, and is universally utilized as a second messenger, and plays important roles in integrity, and function of organs, including heart. Through its coupling with other intracellular messengers, cAMP facilitates excitation-contraction coupling, increases heart rate and conduction velocity. It is degraded by a class of enzymes called cAMP-dependent phosphodiesterase (PDE), with PDE3 and PDE4 being the predominant isoforms in the heart. This highly diverse class of enzymes degrade cAMP and through anchoring proteins generates dynamic microdomains to target specific proteins and control specific cell functions in response to various stimuli. The impaired function of the anchoring protein either by inherited genetic mutations or acquired injuries results in altered intracellular targeting, and blunted responsiveness to stimulating pathways and contributes to pathological cardiac remodeling, cardiac arrhythmias and reduced cell survival. Recent genetic studies provide compelling evidence for an association between the variants in the anchoring protein PDE4DIP and atrial fibrillation, stroke, and heart failure.
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Affiliation(s)
- Arya Mani
- Cardiovascular Research Center, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA; Department of Genetics, Yale School of Medicine, New Haven, CT, USA.
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Gonano LA, Vila Petroff M. AKAP18δ Puts CaMKII in the Right Place at the Right Time: Implications for Cardiac Ca 2+ Handling. Circ Res 2022; 130:45-47. [PMID: 34995136 DOI: 10.1161/circresaha.121.320537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Luis A Gonano
- Centro de Investigaciones Cardiovasculares, CONICET-CCT La Plata, Facultad de Ciencias Médicas, UNLP, Argentina
| | - Martin Vila Petroff
- Centro de Investigaciones Cardiovasculares, CONICET-CCT La Plata, Facultad de Ciencias Médicas, UNLP, Argentina
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6
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Howlett LA, Kirton HM, Al‐Owais MM, Steele D, Lancaster MK. Action potential responses to changes in stimulation frequency and isoproterenol in rat ventricular myocytes. Physiol Rep 2022; 10:e15166. [PMID: 35076184 PMCID: PMC8787729 DOI: 10.14814/phy2.15166] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/16/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023] Open
Abstract
PURPOSE Current understanding of ventricular action potential adaptation to physiological stress is generally based on protocols using non-physiological rates and conditions isolating rate effects from escalating adrenergic stimulation. To permit refined understanding, ventricular action potentials were assessed across physiological pacing frequencies in the presence and absence of adrenergic stimuli. Isolated and combined effects were analyzed to assess their ability to replicate in-vivo responses. METHODS Steady-state action potentials from ventricular myocytes isolated from male Wistar rats (3 months; N = 8 animals) were recorded at 37°C with steady-state pacing at 1, 2, 4, 6, 8 and 10 Hz using whole-cell patch-clamp. Action potential repolarization to 25, 50, 75, 90 and 100% of full repolarization (APD25-100 ) was compared before and after 5 nM, 100 nM and 1 µM isoproterenol doses. RESULTS A Repeated measures ANOVA found APD50-90 shortened with 5 nM isoproterenol infusion by 6-25% (but comparable across doses) (p ≤ 0.03). Pacing frequencies emulating a normal rat heart rate (6 Hz) prolonged APD50 23% compared with 1 Hz pacing. Frequencies emulating exercise or stress (10 Hz) shortened APD90 (29%). CONCLUSION These results demonstrate modest action potential shortening in response to adrenergic stimulation and elevations in pacing beyond physiological resting rates. Our findings indicate changes in action potential plateau and late repolarization predominantly underlie simulated exercise responses in the rat heart. This work provides novel action potential reference data and will help model cardiac responses to physiological stimuli in the rat heart via computational techniques.
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Affiliation(s)
| | | | | | - Derek Steele
- Faculty of Biological SciencesUniversity of LeedsLeedsUK
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7
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Abou Ziki MD, Bhat N, Neogi A, Driscoll TP, Ugwu N, Liu Y, Smith E, Abboud JM, Chouairi S, Schwartz MA, Akar JG, Mani A. Epistatic interaction of PDE4DIP and DES mutations in familial atrial fibrillation with slow conduction. Hum Mutat 2021; 42:1279-1293. [PMID: 34289528 DOI: 10.1002/humu.24265] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/29/2021] [Accepted: 07/06/2021] [Indexed: 11/09/2022]
Abstract
The genetic causes of atrial fibrillation (AF) with slow conduction are unknown. Eight kindreds with familial AF and slow conduction, including a family affected by early-onset AF, heart block, and incompletely penetrant nonischemic dilated cardiomyopathy (DCM) underwent whole exome sequencing. A known pathogenic mutation in the desmin (DES) gene resulting in p.S13F substitution (NM_001927.3:c.38C>T) at a PKC phosphorylation site was identified in all four members of the kindred with early-onset AF and heart block, while only two developed DCM. Higher penetrance for AF and heart block prompted a genetic screening for DES modifier(s). A deleterious mutation in the phosphodiesterase-4D-interacting-protein (PDE4DIP) gene resulting in p.A123T substitution (NM_001002811:c.367G>A) was identified that segregated with early-onset AF, heart block, and the DES mutation. Three additional novel deleterious PDE4DIP mutations were identified in four other unrelated kindreds. Characterization of PDE4DIPA123T in vitro suggested impaired compartmentalization of PKA and PDE4D characterized by reduced colocalization with PDE4D, increased cAMP activation leading to higher PKA phosphorylation of the β2-adrenergic-receptor, and decreased PKA phosphorylation of desmin after isoproterenol stimulation. Our findings identify PDE4DIP as a novel gene for slow AF and unravel its epistatic interaction with DES mutations in development of conduction disease and arrhythmia.
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Affiliation(s)
- Maen D Abou Ziki
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Neha Bhat
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Arpita Neogi
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Tristan P Driscoll
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.,Chemical and Biomedical Engineering, Florida A&M University-Florida State University College of Engineering, Tallahassee, Florida, USA
| | - Nelson Ugwu
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Ya Liu
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Emily Smith
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Johny M Abboud
- Saint George Hospital University Medical Center, Beirut, Lebanon
| | - Salah Chouairi
- Saint George Hospital University Medical Center, Beirut, Lebanon
| | - Martin A Schwartz
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Joseph G Akar
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Arya Mani
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
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8
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Howlett LA, Lancaster MK. Reduced cardiac response to the adrenergic system is a key limiting factor for physical capacity in old age. Exp Gerontol 2021; 150:111339. [PMID: 33838216 DOI: 10.1016/j.exger.2021.111339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/02/2021] [Accepted: 04/03/2021] [Indexed: 10/21/2022]
Abstract
Ageing is associated with a progressive reduction in physical capacity reducing quality of life. One key physiological limitation of physical capacity that deteriorates in a progressive age-dependent manner is cardiac reserve. Peak cardiac output falls progressively with advancing age such that in extreme old age there is limited ability to enhance cardiac output beyond basal function as is required to support the increased metabolic needs of physical activity. This loss of dynamic range in cardiac output associates with a progressive reduction in the heart's response to adrenergic stimulation. A combination of decreases in the expression and functioning of beta1 adrenergic receptors partially underlies this change. Changes in end effector proteins also have a role to play in this decline. Alterations in the efficiency of excitation-contraction coupling contribute to the reduced chronotropic, inotropic and lusitropic responses of the aged heart. Moderate to vigorous endurance exercise training however has some potential to counter elements of these changes. Further studies are required to fully elucidate the key pivotal mechanisms involved in the age-related loss of response to adrenergic signalling to allow targeted therapeutic strategies to be developed with the aim of preserving physical capacity in advanced old age.
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Affiliation(s)
- Luke A Howlett
- Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK.
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van der Horst J, Greenwood IA, Jepps TA. Cyclic AMP-Dependent Regulation of Kv7 Voltage-Gated Potassium Channels. Front Physiol 2020; 11:727. [PMID: 32695022 PMCID: PMC7338754 DOI: 10.3389/fphys.2020.00727] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/04/2020] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated Kv7 potassium channels, encoded by KCNQ genes, have major physiological impacts cardiac myocytes, neurons, epithelial cells, and smooth muscle cells. Cyclic adenosine monophosphate (cAMP), a well-known intracellular secondary messenger, can activate numerous downstream effector proteins, generating downstream signaling pathways that regulate many functions in cells. A role for cAMP in ion channel regulation has been established, and recent findings show that cAMP signaling plays a role in Kv7 channel regulation. Although cAMP signaling is recognized to regulate Kv7 channels, the precise molecular mechanism behind the cAMP-dependent regulation of Kv7 channels is complex. This review will summarize recent research findings that support the mechanisms of cAMP-dependent regulation of Kv7 channels.
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Affiliation(s)
- Jennifer van der Horst
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Molecular and Clinical Sciences Institute, St. George's University of London, London, United Kingdom
| | - Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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10
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Russell MA. Synemin Redefined: Multiple Binding Partners Results in Multifunctionality. Front Cell Dev Biol 2020; 8:159. [PMID: 32258037 PMCID: PMC7090255 DOI: 10.3389/fcell.2020.00159] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 02/27/2020] [Indexed: 12/15/2022] Open
Abstract
Historically synemin has been studied as an intermediate filament protein. However, synemin also binds the type II regulatory (R) subunit α of protein kinase A (PKA) and protein phosphatase type 2A, thus participating in the PKA and phosphoinositide 3-kinase (PI3K)-Akt and signaling pathways. In addition, recent studies using transgenic mice indicate that a significant function of synemin is its role in signaling pathways in various tissues, including the heart. Recent clinical reports have shown that synemin mutations led to multiple cases of dilated cardiomyopathy. Additionally, a single case of the rare condition ulnar-mammary-like syndrome with left ventricular tachycardia due to a mutation in the synemin gene (SYNM) has been reported. Therefore, this review uses these recent studies to provide a new framework for detailed discussions on synemin tissue distribution, binding partners and synemin in disease. Differences between α- and β-synemin are highlighted. The studies presented here indicate that while synemin does function as an intermediate filament protein, it is unique among this large family of proteins as it is also a regulator of signaling pathways and a crosslinker. Also evident is that the dominant function(s) are isoform-, developmental-, and tissue-specific.
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Affiliation(s)
- Mary A Russell
- Department of Biological Sciences, Kent State University at Trumbull, Warren, OH, United States
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11
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Nanometric targeting of type 9 adenylyl cyclase in heart. Biochem Soc Trans 2020; 47:1749-1756. [PMID: 31769471 DOI: 10.1042/bst20190227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022]
Abstract
Adenylyl cyclases (ACs) convert ATP into the classical second messenger cyclic adenosine monophosphate (cAMP). Cardiac ACs, specifically AC5, AC6, and AC9, regulate cAMP signaling controlling functional outcomes such as heart rate, contractility and relaxation, gene regulation, stress responses, and glucose and lipid metabolism. With so many distinct functional outcomes for a single second messenger, the cell creates local domains of cAMP signaling to correctly relay signals. Targeting of ACs to A-kinase anchoring proteins (AKAPs) not only localizes ACs, but also places them within signaling nanodomains, where cAMP levels and effects can be highly regulated. Here we will discuss the recent work on the structure, regulation and physiological functions of AC9 in the heart, where it accounts for <3% of total AC activity. Despite the small contribution of AC9 to total cardiac cAMP production, AC9 binds and regulates local PKA phosphorylation of Yotiao-IKs and Hsp20, demonstrating a role for nanometric targeting of AC9.
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12
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Marin W. A-kinase anchoring protein 1 (AKAP1) and its role in some cardiovascular diseases. J Mol Cell Cardiol 2019; 138:99-109. [PMID: 31783032 DOI: 10.1016/j.yjmcc.2019.11.154] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/08/2019] [Accepted: 11/22/2019] [Indexed: 01/09/2023]
Abstract
A-kinase anchoring proteins (AKAPs) play crucial roles in regulating compartmentalized multi-protein signaling networks related to PKA-mediated phosphorylation. The mitochondrial AKAP - AKAP1 proteins are enriched in heart and play cardiac protective roles. This review aims to thoroughly summarize AKAP1 variants from their sequence features to the structure-function relationships between AKAP1 and its binding partners, as well as the molecular mechanisms of AKAP1 in cardiac hypertrophy, hypoxia-induced myocardial infarction and endothelial cells dysfunction, suggesting AKAP1 as a candidate for cardiovascular therapy.
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Affiliation(s)
- Wenwen Marin
- Institute for Translational Medicine, Medical Faculty of Qingdao University, Qingdao 266021, China.
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13
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Baltzer S, Klussmann E. Small molecules for modulating the localisation of the water channel aquaporin-2-disease relevance and perspectives for targeting local cAMP signalling. Naunyn Schmiedebergs Arch Pharmacol 2019; 392:1049-1064. [PMID: 31300862 DOI: 10.1007/s00210-019-01686-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/26/2019] [Indexed: 12/23/2022]
Abstract
The tight spatial and temporal organisation of cyclic adenosine monophosphate (cAMP) signalling plays a key role in arginine-vasopressin (AVP)-mediated water reabsorption in renal collecting duct principal cells and in a plethora of other processes such as in the control of cardiac myocyte contractility. This review critically discusses in vitro- and cell-based screening strategies for the identification of small molecules that interfere with AVP/cAMP signalling in renal principal cells; it features phenotypic screening and approaches for targeting protein-protein interactions of A-kinase anchoring proteins (AKAPs), which organise local cAMP signalling hubs. The discovery of novel chemical entities for the modulation of local cAMP will not only provide tools for elucidating molecular mechanisms underlying cAMP signalling. Novel chemical entities can also serve as starting points for the development of novel drugs for the treatment of human diseases. Examples illustrate how screening for small molecules can pave the way to novel approaches for the treatment of certain forms of diabetes insipidus, a disease caused by defects in AVP-mediated water reabsorption.
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Affiliation(s)
- Sandrine Baltzer
- Max Delbrück Center for Molecular Medicine Berlin (MDC), Helmholtz Association, Robert-Rössle-Strasse 10, 13125, Berlin, Germany
| | - Enno Klussmann
- Max Delbrück Center for Molecular Medicine Berlin (MDC), Helmholtz Association, Robert-Rössle-Strasse 10, 13125, Berlin, Germany. .,DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany. .,Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health and Vegetative Physiology, Berlin, Germany.
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14
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Dodge-Kafka K, Gildart M, Tokarski K, Kapiloff MS. mAKAPβ signalosomes - A nodal regulator of gene transcription associated with pathological cardiac remodeling. Cell Signal 2019; 63:109357. [PMID: 31299211 PMCID: PMC7197268 DOI: 10.1016/j.cellsig.2019.109357] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/01/2019] [Accepted: 07/05/2019] [Indexed: 12/14/2022]
Abstract
Striated myocytes compose about half of the cells of the heart, while contributing the majority of the heart's mass and volume. In response to increased demands for pumping power, including in diseases of pressure and volume overload, the contractile myocytes undergo non-mitotic growth, resulting in increased heart mass, i.e. cardiac hypertrophy. Myocyte hypertrophy is induced by a change in the gene expression program driven by the altered activity of transcription factors and co-repressor and co-activator chromatin-associated proteins. These gene regulatory proteins are subject to diverse post-translational modifications and serve as nuclear effectors for intracellular signal transduction pathways, including those controlled by cyclic nucleotides and calcium ion. Scaffold proteins contribute to the underlying architecture of intracellular signaling networks by targeting signaling enzymes to discrete intracellular compartments, providing specificity to the regulation of downstream effectors, including those regulating gene expression. Muscle A-kinase anchoring protein β (mAKAPβ) is a well-characterized scaffold protein that contributes to the regulation of pathological cardiac hypertrophy. In this review, we discuss the mechanisms how this prototypical scaffold protein organizes signalosomes responsible for the regulation of class IIa histone deacetylases and cardiac transcription factors such as NFAT, MEF2, and HIF-1α, as well as how this signalosome represents a novel therapeutic target for the prevention or treatment of heart failure.
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Affiliation(s)
- Kimberly Dodge-Kafka
- Calhoun Center for Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, University of Connecticut Health Center, Farmington, CT, USA.
| | - Moriah Gildart
- Calhoun Center for Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, University of Connecticut Health Center, Farmington, CT, USA
| | - Kristin Tokarski
- Calhoun Center for Cardiology, Cardiac Signal Transduction and Cellular Biology Laboratory, University of Connecticut Health Center, Farmington, CT, USA
| | - Michael S Kapiloff
- Departments of Ophthalmology and Medicine, Stanford Cardiovascular Institute, Stanford University, Palo Alto, CA, USA
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15
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Gildart M, Kapiloff MS, Dodge-Kafka KL. Calcineurin-AKAP interactions: therapeutic targeting of a pleiotropic enzyme with a little help from its friends. J Physiol 2018; 598:3029-3042. [PMID: 30488951 PMCID: PMC7586300 DOI: 10.1113/jp276756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 11/14/2018] [Indexed: 01/14/2023] Open
Abstract
The ubiquitous Ca2+ /calmodulin-dependent phosphatase calcineurin is a key regulator of pathological cardiac hypertrophy whose therapeutic targeting in heart disease has been elusive due to its role in other essential biological processes. Calcineurin is targeted to diverse intracellular compartments by association with scaffold proteins, including by multivalent A-kinase anchoring proteins (AKAPs) that bind protein kinase A and other important signalling enzymes determining cardiac myocyte function and phenotype. Calcineurin anchoring by AKAPs confers specificity to calcineurin function in the cardiac myocyte. Targeting of calcineurin 'signalosomes' may provide a rationale for inhibiting the phosphatase in disease.
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Affiliation(s)
- Moriah Gildart
- Calhoun Center for Cardiology, University of Connecticut Health Center, Farmington, CT, USA
| | - Michael S Kapiloff
- Departments of Ophthalmology and Cardiovascular Medicine, Byers Eye Institute and Spencer Center for Vision Research, Stanford Cardiovascular Institute, Stanford University, Palo Alto, CA, USA
| | - Kimberly L Dodge-Kafka
- Calhoun Center for Cardiology, University of Connecticut Health Center, Farmington, CT, USA
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16
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Function of Adenylyl Cyclase in Heart: the AKAP Connection. J Cardiovasc Dev Dis 2018; 5:jcdd5010002. [PMID: 29367580 PMCID: PMC5872350 DOI: 10.3390/jcdd5010002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/09/2018] [Accepted: 01/11/2018] [Indexed: 12/13/2022] Open
Abstract
Cyclic adenosine monophosphate (cAMP), synthesized by adenylyl cyclase (AC), is a universal second messenger that regulates various aspects of cardiac physiology from contraction rate to the initiation of cardioprotective stress response pathways. Local pools of cAMP are maintained by macromolecular complexes formed by A-kinase anchoring proteins (AKAPs). AKAPs facilitate control by bringing together regulators of the cAMP pathway including G-protein-coupled receptors, ACs, and downstream effectors of cAMP to finely tune signaling. This review will summarize the distinct roles of AC isoforms in cardiac function and how interactions with AKAPs facilitate AC function, highlighting newly appreciated roles for lesser abundant AC isoforms.
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17
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Wu YS, Chen CC, Chien CL, Lai HL, Jiang ST, Chen YC, Lai LP, Hsiao WF, Chen WP, Chern Y. The type VI adenylyl cyclase protects cardiomyocytes from β-adrenergic stress by a PKA/STAT3-dependent pathway. J Biomed Sci 2017; 24:68. [PMID: 28870220 PMCID: PMC5584049 DOI: 10.1186/s12929-017-0367-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 08/11/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The type VI adenylyl cyclase (AC6) is a main contributor of cAMP production in the heart. The amino acid (aa) sequence of AC6 is highly homologous to that of another major cardiac adenylyl cyclase, AC5, except for its N-terminus (AC6-N, aa 1-86). Activation of AC6, rather than AC5, produces cardioprotective effects against heart failure, while the underlying mechanism remains to be unveiled. Using an AC6-null (AC6-/-) mouse and a knockin mouse with AC6-N deletion (AC6 ΔN/ΔN), we aimed to investigate the cardioprotective mechanism of AC6 in the heart. METHODS Western blot analysis and immunofluorescence staining were performed to determine the intracellular distribution of AC6, AC6-ΔN (a truncated AC6 lacking the first 86 amino acids), and STAT3 activation. Activities of AC6 and AC6-ΔN in the heart were assessed by cAMP assay. Apoptosis of cardiomyocytes were evaluated by the TUNEL assay and a propidium iodine-based survival assay. Fibrosis was examined by collagen staining. RESULTS Immunofluorescence staining revealed that cardiac AC6 was mainly anchored on the sarcolemmal membranes, while AC6-ΔN was redistributed to the sarcoplasmic reticulum. AC6ΔN/ΔN and AC6-/- mice had more apoptotic myocytes and cardiac remodeling than WT mice in experimental models of isoproterenol (ISO)-induced myocardial injury. Adult cardiomyocytes isolated from AC6ΔN/ΔN or AC6-/- mice survived poorly after exposure to ISO, which produced no effect on WT cardiomyocytes under the condition tested. Importantly, ISO treatment induced cardiac STAT3 phosphorylation/activation in WT mice, but not in AC6ΔN/ΔN and AC6-/- mice. Pharmacological blockage of PKA-, Src-, or STAT3- pathway markedly reduced the survival of WT myocytes in the presence of ISO, but did not affect those of AC6ΔN/ΔN and AC6-/- myocytes, suggesting an important role of AC6 in mediating cardioprotective action through the activation of PKA-Src-STAT3-signaling. CONCLUSIONS Collectively, AC6-N controls the anchorage of cardiac AC6 on the sarcolemmal membrane, which enables the coupling of AC6 with the pro-survival PKA-STAT3 pathway. Our findings may facilitate the development of novel therapies for heart failure.
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Affiliation(s)
- Yu-Shuo Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chien-Chang Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Chen-Li Chien
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Si-Tse Jiang
- National Laboratory Animal Center, National Applied Research Laboratories, Tainan, Taiwan
| | - Yong-Cyuan Chen
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan
| | - Lin-Ping Lai
- Institute of Internal Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Fan Hsiao
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Pin Chen
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Yijuang Chern
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, 115, Taiwan.
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18
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Li Z, Singh S, Suryavanshi SV, Ding W, Shen X, Wijaya CS, Gao WD, McConnell BK. Force development and intracellular Ca 2+ in intact cardiac muscles from gravin mutant mice. Eur J Pharmacol 2017; 807:117-126. [PMID: 28428008 DOI: 10.1016/j.ejphar.2017.04.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 04/13/2017] [Accepted: 04/13/2017] [Indexed: 02/08/2023]
Abstract
Gravin (AKAP12) is an A-kinase-anchoring-protein that scaffolds protein kinase A (PKA), β2-adrenergic receptor (β2-AR), protein phosphatase 2B and protein kinase C. Gravin facilitates β2-AR-dependent signal transduction through PKA to modulate cardiac excitation-contraction coupling and its removal positively affects cardiac contraction. Trabeculae from the right ventricles of gravin mutant (gravin-t/t) mice were employed for force determination. Simultaneously, corresponding intracellular Ca2+ transient ([Ca2+]i) were measured. Twitch force (Tf)-interval relationship, [Ca2+]i-interval relationship, and the rate of decay of post-extrasysolic potentiation (Rf) were also obtained. Western blot analysis were performed to correlate sarcomeric protein expression with alterations in calcium cycling between the WT and gravin-t/t hearts. Gravin-t/t muscles had similar developed force compared to WT muscles despite having lower [Ca2+]i at any given external Ca2+ concentration ([Ca2+]o). The time to peak force and peak [Ca2+]i were slower and the time to 75% relaxation was significantly prolonged in gravin-t/t muscles. Both Tf-interval and [Ca2+]i-interval relations were depressed in gravin-t/t muscles. Rf, however, did not change. Furthermore, Western blot analysis revealed decreased ryanodine receptor (RyR2) phosphorylation in gravin-t/t hearts. Gravin-t/t cardiac muscle exhibits increased force development in responsiveness to Ca2+. The Ca2+ cycling across the SR appears to be unaltered in gravin-t/t muscle. Our study suggests that gravin is an important component of cardiac contraction regulation via increasing myofilament sensitivity to calcium. Further elucidation of the mechanism can provide insights to role of gravin if any in the pathophysiology of impaired contractility.
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Affiliation(s)
- Zhitao Li
- Department of Pathophysiology, Harbin Medical University, Heilongjiang, China
| | - Sonal Singh
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA
| | - Wengang Ding
- Department of Anesthesiology of 2nd Affiliated Hospital, Harbin Medical University, Heilongjiang, China
| | - Xiaoxu Shen
- Cardiology Department, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, China
| | - Cori S Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, 1800 Orleans Street, Zaye Tower 6208, Baltimore, MD 21287, USA.
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Texas Medical Center, Houston, TX, USA.
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19
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Role of plasma membrane-associated AKAPs for the regulation of cardiac IK1 current by protein kinase A. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:493-503. [DOI: 10.1007/s00210-017-1344-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 01/12/2017] [Indexed: 12/20/2022]
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20
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Abstract
The universal second messengers cyclic nucleotides 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) play central roles in cardiovascular function and disease. They act in discrete, functionally relevant subcellular microdomains which regulate, for example, calcium cycling and excitation-contraction coupling. Such localized cAMP and cGMP signals have been difficult to measure using conventional biochemical techniques. Recent years have witnessed the advent of live cell imaging techniques which allow visualization of these functionally relevant second messengers with unprecedented spatial and temporal resolution at cellular, subcellular and tissue levels. In this review, we discuss these new imaging techniques and give examples how they are used to visualize cAMP and cGMP in physiological and pathological settings to better understand cardiovascular function and disease. Two primary techniques include the use of Förster resonance energy transfer (FRET) based cyclic nucleotide biosensors and nanoscale scanning ion conductance microscopy (SICM). These methods can provide deep mechanistic insights into compartmentalized cAMP and cGMP signaling.
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Affiliation(s)
- Filip Berisha
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of General and Interventional Cardiology, University Heart Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Viacheslav O Nikolaev
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Germany.
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21
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Lorenzen-Schmidt I, Clarke SB, Pyle WG. The neglected messengers: Control of cardiac myofilaments by protein phosphatases. J Mol Cell Cardiol 2016; 101:81-89. [PMID: 27721025 DOI: 10.1016/j.yjmcc.2016.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 01/21/2023]
Abstract
Cardiac myofilaments act as the central contractile apparatus of heart muscle cells. Covalent modification of constituent proteins through phosphorylation is a rapid and powerful mechanism to control myofilament function, and is increasingly seen as a mechanism of disease. While the relationship between protein kinases and cardiac myofilaments has been widely examined, the impact of protein dephosphorylation by protein phosphatases is poorly understood. This review outlines the mechanisms by which the mostly widely expressed protein phosphatases in cardiac myocytes regulate myofilament function, and the emerging role of myofilament-associated protein phosphatases in heart failure. The importance of regulatory subunits and subcellular compartmentalization in determining the functional impact of protein phosphatases on myofilament and myocardial function is also discussed, as are discrepancies about the roles of protein phosphatases in regulating myofilament function. The potential for targeting these molecular messengers in the treatment of heart failure is discussed as a key future direction.
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Affiliation(s)
- Ilka Lorenzen-Schmidt
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Samantha B Clarke
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - W Glen Pyle
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
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22
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Dema A, Perets E, Schulz MS, Deák VA, Klussmann E. Pharmacological targeting of AKAP-directed compartmentalized cAMP signalling. Cell Signal 2015; 27:2474-87. [PMID: 26386412 DOI: 10.1016/j.cellsig.2015.09.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/08/2015] [Accepted: 09/14/2015] [Indexed: 01/26/2023]
Abstract
The second messenger cyclic adenosine monophosphate (cAMP) can bind and activate protein kinase A (PKA). The cAMP/PKA system is ubiquitous and involved in a wide array of biological processes and therefore requires tight spatial and temporal regulation. Important components of the safeguard system are the A-kinase anchoring proteins (AKAPs), a heterogeneous family of scaffolding proteins defined by its ability to directly bind PKA. AKAPs tether PKA to specific subcellular compartments, and they bind further interaction partners to create local signalling hubs. The recent discovery of new AKAPs and advances in the field that shed light on the relevance of these hubs for human disease highlight unique opportunities for pharmacological modulation. This review exemplifies how interference with signalling, particularly cAMP signalling, at such hubs can reshape signalling responses and discusses how this could lead to novel pharmacological concepts for the treatment of disease with an unmet medical need such as cardiovascular disease and cancer.
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Affiliation(s)
- Alessandro Dema
- Max Delbrück Center for Molecular Medicine Berlin in the Helmholtz Association (MDC), Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Ekaterina Perets
- Max Delbrück Center for Molecular Medicine Berlin in the Helmholtz Association (MDC), Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Maike Svenja Schulz
- Max Delbrück Center for Molecular Medicine Berlin in the Helmholtz Association (MDC), Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Veronika Anita Deák
- Max Delbrück Center for Molecular Medicine Berlin in the Helmholtz Association (MDC), Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Enno Klussmann
- Max Delbrück Center for Molecular Medicine Berlin in the Helmholtz Association (MDC), Robert-Rössle-Straße 10, 13125 Berlin, Germany; DZHK, German Centre for Cardiovascular Research, Oudenarder Straße 16, 13347 Berlin, Germany.
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23
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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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24
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Compartmentalization role of A-kinase anchoring proteins (AKAPs) in mediating protein kinase A (PKA) signaling and cardiomyocyte hypertrophy. Int J Mol Sci 2014. [PMID: 25547489 DOI: 10.3390/ijms16010218.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure-function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.
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25
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Rababa'h A, Singh S, Suryavanshi SV, Altarabsheh SE, Deo SV, McConnell BK. Compartmentalization role of A-kinase anchoring proteins (AKAPs) in mediating protein kinase A (PKA) signaling and cardiomyocyte hypertrophy. Int J Mol Sci 2014; 16:218-29. [PMID: 25547489 PMCID: PMC4307244 DOI: 10.3390/ijms16010218] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/18/2014] [Indexed: 02/07/2023] Open
Abstract
The Beta-adrenergic receptors (β-ARs) stimulation enhances contractility through protein kinase-A (PKA) substrate phosphorylation. This PKA signaling is conferred in part by PKA binding to A-kinase anchoring proteins (AKAPs). AKAPs coordinate multi-protein signaling networks that are targeted to specific intracellular locations, resulting in the localization of enzyme activity and transmitting intracellular actions of neurotransmitters and hormones to its target substrates. In particular, mAKAP (muscle-selective AKAP) has been shown to be present on the nuclear envelope of cardiomyocytes with various proteins including: PKA-regulatory subunit (RIIα), phosphodiesterase-4D3, protein phosphatase-2A, and ryanodine receptor (RyR2). Therefore, through the coordination of spatial-temporal signaling of proteins and enzymes, mAKAP controls cyclic-adenosine monophosphate (cAMP) levels very tightly and functions as a regulator of PKA-mediated substrate phosphorylation leading to changes in calcium availability and myofilament calcium sensitivity. The goal of this review is to elucidate the critical compartmentalization role of mAKAP in mediating PKA signaling and regulating cardiomyocyte hypertrophy by acting as a scaffolding protein. Based on our literature search and studying the structure-function relationship between AKAP scaffolding protein and its binding partners, we propose possible explanations for the mechanism by which mAKAP promotes cardiac hypertrophy.
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Affiliation(s)
- Abeer Rababa'h
- Department of Clinical Pharmacy, Jordan University of Science and Technology, Irbid 22110, Jordan.
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
| | - Santosh V Suryavanshi
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
| | | | - Salil V Deo
- Department of Cardiovascular Surgery, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Bradley K McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA.
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26
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α-Synemin localizes to the M-band of the sarcomere through interaction with the M10 region of titin. FEBS Lett 2014; 588:4625-30. [PMID: 25447537 DOI: 10.1016/j.febslet.2014.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 01/26/2023]
Abstract
α-Synemin contains a unique 312 amino acid insert near the end of its C-terminal tail. Therefore we set out to determine if the insert is a site of protein-protein interaction that regulates the sub-cellular localization of this large isoform of synemin. Yeast-two hybrid analysis indicated that this region is a binding site for the M10 region of titin. This was confirmed with GST pull-down assays. Co-immunoprecipitation of endogenous proteins indicated close association of the two proteins in vivo and immunostaining of cardiomyocytes demonstrated co-localization of the proteins at the M-band of the sarcomere.
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27
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Weninger S, Van Craenenbroeck K, Cameron RT, Vandeput F, Movsesian MA, Baillie GS, Lefebvre RA. Phosphodiesterase 4 interacts with the 5-HT4(b) receptor to regulate cAMP signaling. Cell Signal 2014; 26:2573-82. [PMID: 25101859 DOI: 10.1016/j.cellsig.2014.07.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/28/2014] [Accepted: 07/28/2014] [Indexed: 12/14/2022]
Abstract
Phosphodiesterase (PDE) 3 and PDE4, which degrade cyclic adenosine monophosphate (cAMP), are important regulators of 5-hydroxytryptamine (5-HT) 4 receptor signaling in cardiac tissue. Therefore, we investigated whether they interact with the 5-HT4(b) receptor, and whether A-kinase anchoring proteins (AKAPs), scaffolding proteins that bind to the regulatory subunit of protein kinase A (PKA) and contribute to the spacial-temporal control of cAMP signaling, are involved in the regulation of 5-HT4(b) receptor signaling. By measuring PKA activity in the absence and presence of PDE3 and PDE4 inhibitiors, we found that constitutive signaling of the overexpressed HA-tagged 5-HT4(b) receptor in HEK293 cells is regulated predominantly by PDE4, with a secondary role for PDE3 that is unmasked in the presence of PDE4 inhibition. Overexpressed PDE4D3 and PDE3A1, and to a smaller extent PDE4D5 co-immunoprecipitate constitutively with the 5-HT4(b) receptor. PDE activity measurements in immunoprecipitates of the 5-HT4(b) receptor confirm the association of PDE4D3 with the receptor and provide evidence that the activity of this PDE may be increased upon receptor stimulation with 5-HT. A possible involvement of AKAPs in 5-HT4(b) receptor signaling was uncovered in experiments using the St-Ht31 inhibitor peptide, which disrupts the interaction of AKAPs with PKA. However, St-Ht31 did not influence 5-HT4(b) receptor-stimulated PKA activity, and endogenous AKAP79 and gravin were not found in immunoprecipitates of the 5-HT4(b) receptor. In conclusion, we found that both PDE3A1 and PDE4D3 are integrated into complexes that contain the 5-HT4(b) receptor and may thereby regulate 5-HT4(b) receptor-mediated signaling.
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Affiliation(s)
- S Weninger
- Heymans Institute of Pharmacology, Ghent University, De Pintelaan 185, Ghent 9000, Belgium
| | - K Van Craenenbroeck
- Laboratory for Eukaryotic Gene Expression and Signal Transduction, Ghent University, Proeftuinstraat 86, Ghent 9000, Belgium
| | - R T Cameron
- Institute of Cardiovascular and Medical Science, University of Glasgow, Office 534, Wolfson-Link Building, Glasgow G12 8QQ, UK
| | - F Vandeput
- Cardiovascular Medicine Division, VA Salt Lake City Health Care System and University of Utah School of Medicine, Salt Lake City, UT 84148, USA
| | - M A Movsesian
- Cardiovascular Medicine Division, VA Salt Lake City Health Care System and University of Utah School of Medicine, Salt Lake City, UT 84148, USA
| | - G S Baillie
- Institute of Cardiovascular and Medical Science, University of Glasgow, Office 534, Wolfson-Link Building, Glasgow G12 8QQ, UK
| | - R A Lefebvre
- Heymans Institute of Pharmacology, Ghent University, De Pintelaan 185, Ghent 9000, Belgium.
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28
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Soni S, Scholten A, Vos MA, van Veen TAB. Anchored protein kinase A signalling in cardiac cellular electrophysiology. J Cell Mol Med 2014; 18:2135-46. [PMID: 25216213 PMCID: PMC4224547 DOI: 10.1111/jcmm.12365] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 06/10/2014] [Indexed: 01/13/2023] Open
Abstract
The cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) is an elementary molecule involved in both acute and chronic modulation of cardiac function. Substantial research in recent years has highlighted the importance of A-kinase anchoring proteins (AKAP) therein as they act as the backbones of major macromolecular signalling complexes of the β-adrenergic/cAMP/PKA pathway. This review discusses the role of AKAP-associated protein complexes in acute and chronic cardiac modulation by dissecting their role in altering the activity of different ion channels, which underlie cardiac action potential (AP) generation. In addition, we review the involvement of different AKAP complexes in mechanisms of cardiac remodelling and arrhythmias.
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Affiliation(s)
- Siddarth Soni
- Division of Heart & Lungs, Dept of Medical Physiology, University Medical Centre Utrecht, Utrecht, The Netherlands; Biomolecular Mass Spectrometry & Proteomics, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
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29
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PKA signaling drives mammary tumorigenesis through Src. Oncogene 2014; 34:1160-73. [PMID: 24662820 DOI: 10.1038/onc.2014.41] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 12/20/2013] [Accepted: 12/24/2013] [Indexed: 12/30/2022]
Abstract
Protein kinase A (PKA) hyperactivation causes hereditary endocrine neoplasias; however, its role in sporadic epithelial cancers is unknown. Here, we show that heightened PKA activity in the mammary epithelium generates tumors. Mammary-restricted biallelic ablation of Prkar1a, which encodes for the critical type-I PKA regulatory subunit, induced spontaneous breast tumors characterized by enhanced type-II PKA activity. Downstream of this, Src phosphorylation occurs at residues serine-17 and tyrosine-416 and mammary cell transformation is driven through a mechanism involving Src signaling. The phenotypic consequences of these alterations consisted of increased cell proliferation and, accordingly, expansion of both luminal and basal epithelial cell populations. In human breast cancer, low PRKAR1A/high SRC expression defines basal-like and HER2 breast tumors associated with poor clinical outcome. Together, the results of this study define a novel molecular mechanism altered in breast carcinogenesis and highlight the potential strategy of inhibiting SRC signaling in treating this cancer subtype in humans.
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30
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PKA catalytic subunit compartmentation regulates contractile and hypertrophic responses to β-adrenergic signaling. J Mol Cell Cardiol 2013; 66:83-93. [PMID: 24225179 DOI: 10.1016/j.yjmcc.2013.11.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 10/14/2013] [Accepted: 11/02/2013] [Indexed: 01/08/2023]
Abstract
β-Adrenergic signaling is spatiotemporally heterogeneous in the cardiac myocyte, conferring exquisite control to sympathetic stimulation. Such heterogeneity drives the formation of protein kinase A (PKA) signaling microdomains, which regulate Ca(2+) handling and contractility. Here, we test the hypothesis that the nucleus independently comprises a PKA signaling microdomain regulating myocyte hypertrophy. Spatially-targeted FRET reporters for PKA activity identified slower PKA activation and lower isoproterenol sensitivity in the nucleus (t50=10.6±0.7 min; EC50=89.0 nmol/L) than in the cytosol (t50=3.71±0.25 min; EC50=1.22 nmol/L). These differences were not explained by cAMP or AKAP-based compartmentation. A computational model of cytosolic and nuclear PKA activity was developed and predicted that differences in nuclear PKA dynamics and magnitude are regulated by slow PKA catalytic subunit diffusion, while differences in isoproterenol sensitivity are regulated by nuclear expression of protein kinase inhibitor (PKI). These were validated by FRET and immunofluorescence. The model also predicted differential phosphorylation of PKA substrates regulating cell contractility and hypertrophy. Ca(2+) and cell hypertrophy measurements validated these predictions and identified higher isoproterenol sensitivity for contractile enhancements (EC50=1.84 nmol/L) over cell hypertrophy (EC50=85.9 nmol/L). Over-expression of spatially targeted PKA catalytic subunit to the cytosol or nucleus enhanced contractile and hypertrophic responses, respectively. We conclude that restricted PKA catalytic subunit diffusion is an important PKA compartmentation mechanism and the nucleus comprises a novel PKA signaling microdomain, insulating hypertrophic from contractile β-adrenergic signaling responses.
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Ethanol Extract of Lepidium apetalum Seed Elicits Contractile Response and Attenuates Atrial Natriuretic Peptide Secretion in Beating Rabbit Atria. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:404713. [PMID: 24288558 PMCID: PMC3830812 DOI: 10.1155/2013/404713] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 09/09/2013] [Indexed: 11/24/2022]
Abstract
The seeds of Lepidium apetalum Willdenow (called “Tinglizi” in China and “Jungryukza” in Korea) have been used to discharge phlegm and improve dropsy in Oriental medicine. The present study investigated the effects of ethanol extract of the seeds of Lepidium apetalum (ELA) on atrial dynamics and atrial natriuretic peptide (ANP) secretion in beating rabbit atria. ELA increased atrial stroke volume, pulse pressure, and cAMP efflux, concomitantly attenuating ANP secretion in a dose-dependent manner. ELA-induced increases in atrial stroke volume, pulse pressure, and cAMP levels and decrease in ANP secretion were not inhibited by pretreatment with staurosporine, a nonspecific protein kinase inhibitor, or diltiazem and verapamil, the L-type Ca2+ channel blockers, respectively. Helveticoside, a well-known digitalis-like cardiac glycosidic constituent of ELA, also increased atrial dynamics, including stroke volume and pulse pressure, without changing cAMP efflux and ANP secretion, and the effects of helveticoside were not inhibited by pretreatment with staurosporine, diltiazem, and verapamil. These results suggest that the ELA-induced positive inotropic activity in beating rabbit atria might, at least partly, be due to the digitalis-like activity of helveticoside rather than an increase in cAMP efflux.
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Enhanced cardiac function in Gravin mutant mice involves alterations in the β-adrenergic receptor signaling cascade. PLoS One 2013. [PMID: 24058627 DOI: 10.1371/journal.pone.0074784.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Gravin, an A-kinase anchoring protein, targets protein kinase A (PKA), protein kinase C (PKC), calcineurin and other signaling molecules to the beta2-adrenergic receptor (β2-AR). Gravin mediates desensitization/resensitization of the receptor by facilitating its phosphorylation by PKA and PKC. The role of gravin in β-AR mediated regulation of cardiac function is unclear. The purpose of this study was to determine the effect of acute β-AR stimulation on cardiac contractility in mice lacking functional gravin. Using echocardiographic analysis, we observed that contractility parameters such as left ventricular fractional shortening and ejection fraction were increased in gravin mutant (gravin-t/t) animals lacking functional protein compared to wild-type (WT) animals both at baseline and following acute isoproterenol (ISO) administration. In isolated gravin-t/t cardiomyocytes, we observed increased cell shortening fraction and decreased intracellular Ca(2+) in response to 1 µmol/L ISO stimulation. These physiological responses occurred in the presence of decreased β2-AR phosphorylation in gravin-t/t hearts, where PKA-dependent β2-AR phosphorylation has been shown to lead to receptor desensitization. cAMP production, PKA activity and phosphorylation of phospholamban and troponin I was comparable in WT and gravin-t/t hearts both with and without ISO stimulation. However, cardiac myosin binding protein C (cMyBPC) phosphorylation site at position 273 was significantly increased in gravin-t/t versus WT hearts, in the absence of ISO. Additionally, the cardioprotective heat shock protein 20 (Hsp20) was significantly more phosphorylated in gravin-t/t versus WT hearts, in response to ISO. Our results suggest that disruption of gravin's scaffold mediated signaling is able to increase baseline cardiac function as well as to augment contractility in response to acute β-AR stimulation by decreasing β2-AR phosphorylation and thus attenuating receptor desensitization and perhaps by altering PKA localization to increase the phosphorylation of cMyBPC and the nonclassical PKA substrate Hsp20.
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33
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Rababa'h A, Craft JW, Wijaya CS, Atrooz F, Fan Q, Singh S, Guillory AN, Katsonis P, Lichtarge O, McConnell BK. Protein kinase A and phosphodiesterase-4D3 binding to coding polymorphisms of cardiac muscle anchoring protein (mAKAP). J Mol Biol 2013. [PMID: 23806656 DOI: 10.1016/j.jmb.2013.06.014.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
Protein kinase A (PKA) substrate phosphorylation is facilitated through its co-localization with its signaling partner by A-kinase anchoring proteins (AKAPs). mAKAP (muscle-selective AKAP) localizes PKA and its substrates such as phosphodiesterase-4D3 (PDE4D3), ryanodine receptor, and protein phosphatase 2A (PP2A) to the sarcoplasmic reticulum and perinuclear space. The genetic role of mAKAP, in modulating PKA/PDE4D3 molecular signaling during cardiac diseases, remains unclear. The purpose of this study was to examine the effects of naturally occurring mutations in human mAKAP on PKA and PDE4D3 signaling. We have recently identified potentially important human mAKAP coding non-synonymous polymorphisms located within or near key protein binding sites critical to β-adrenergic receptor signaling. Three mutations (P1400S, S2195F, and L717V) were cloned and transfected into a mammalian cell line for the purpose of comparing whether those substitutions disrupt mAKAP binding to PKA or PDE4D3. Immunoprecipitation study of mAKAP-P1400S, a mutation located in the mAKAP-PDE4D3 binding site, displayed a significant reduction in binding to PDE4D3, with no significant changes in PKA binding or PKA activity. Conversely, mAKAP-S2195F, a mutation located in mAKAP-PP2A binding site, showed significant increase in both binding propensity to PKA and PKA activity. Additionally, mAKAP-L717V, a mutation flanking the mAKAP-spectrin repeat domain, exhibited a significant increase in PKA binding compared to wild type, but there was no change in PKA activity. We also demonstrate specific binding of wild-type mAKAP to PDE4D3. Binding results were demonstrated using immunoprecipitation and confirmed with surface plasmon resonance (Biacore-2000); functional results were demonstrated using activity assays, Ca(2+) measurements, and Western blot. Comparative analysis of the binding responses of mutations to mAKAP could provide important information about how these mutations modulate signaling.
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Affiliation(s)
- Abeer Rababa'h
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, TX 77204, USA
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Guillory AN, Yin X, Wijaya CS, Diaz Diaz AC, Rababa’h A, Singh S, Atrooz F, Sadayappan S, McConnell BK. Enhanced cardiac function in Gravin mutant mice involves alterations in the β-adrenergic receptor signaling cascade. PLoS One 2013; 8:e74784. [PMID: 24058627 PMCID: PMC3776749 DOI: 10.1371/journal.pone.0074784] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 08/07/2013] [Indexed: 11/19/2022] Open
Abstract
Gravin, an A-kinase anchoring protein, targets protein kinase A (PKA), protein kinase C (PKC), calcineurin and other signaling molecules to the beta2-adrenergic receptor (β2-AR). Gravin mediates desensitization/resensitization of the receptor by facilitating its phosphorylation by PKA and PKC. The role of gravin in β-AR mediated regulation of cardiac function is unclear. The purpose of this study was to determine the effect of acute β-AR stimulation on cardiac contractility in mice lacking functional gravin. Using echocardiographic analysis, we observed that contractility parameters such as left ventricular fractional shortening and ejection fraction were increased in gravin mutant (gravin-t/t) animals lacking functional protein compared to wild-type (WT) animals both at baseline and following acute isoproterenol (ISO) administration. In isolated gravin-t/t cardiomyocytes, we observed increased cell shortening fraction and decreased intracellular Ca2+ in response to 1 µmol/L ISO stimulation. These physiological responses occurred in the presence of decreased β2-AR phosphorylation in gravin-t/t hearts, where PKA-dependent β2-AR phosphorylation has been shown to lead to receptor desensitization. cAMP production, PKA activity and phosphorylation of phospholamban and troponin I was comparable in WT and gravin-t/t hearts both with and without ISO stimulation. However, cardiac myosin binding protein C (cMyBPC) phosphorylation site at position 273 was significantly increased in gravin-t/t versus WT hearts, in the absence of ISO. Additionally, the cardioprotective heat shock protein 20 (Hsp20) was significantly more phosphorylated in gravin-t/t versus WT hearts, in response to ISO. Our results suggest that disruption of gravin’s scaffold mediated signaling is able to increase baseline cardiac function as well as to augment contractility in response to acute β-AR stimulation by decreasing β2-AR phosphorylation and thus attenuating receptor desensitization and perhaps by altering PKA localization to increase the phosphorylation of cMyBPC and the nonclassical PKA substrate Hsp20.
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Affiliation(s)
- Ashley N. Guillory
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Xing Yin
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Cori S. Wijaya
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Andrea C. Diaz Diaz
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Abeer Rababa’h
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Fatin Atrooz
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston Texas Medical Center, Houston, Texas, United States of America
- * E-mail:
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35
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Protein kinase A and phosphodiesterase-4D3 binding to coding polymorphisms of cardiac muscle anchoring protein (mAKAP). J Mol Biol 2013; 425:3277-88. [PMID: 23806656 DOI: 10.1016/j.jmb.2013.06.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/20/2013] [Accepted: 06/11/2013] [Indexed: 11/20/2022]
Abstract
Protein kinase A (PKA) substrate phosphorylation is facilitated through its co-localization with its signaling partner by A-kinase anchoring proteins (AKAPs). mAKAP (muscle-selective AKAP) localizes PKA and its substrates such as phosphodiesterase-4D3 (PDE4D3), ryanodine receptor, and protein phosphatase 2A (PP2A) to the sarcoplasmic reticulum and perinuclear space. The genetic role of mAKAP, in modulating PKA/PDE4D3 molecular signaling during cardiac diseases, remains unclear. The purpose of this study was to examine the effects of naturally occurring mutations in human mAKAP on PKA and PDE4D3 signaling. We have recently identified potentially important human mAKAP coding non-synonymous polymorphisms located within or near key protein binding sites critical to β-adrenergic receptor signaling. Three mutations (P1400S, S2195F, and L717V) were cloned and transfected into a mammalian cell line for the purpose of comparing whether those substitutions disrupt mAKAP binding to PKA or PDE4D3. Immunoprecipitation study of mAKAP-P1400S, a mutation located in the mAKAP-PDE4D3 binding site, displayed a significant reduction in binding to PDE4D3, with no significant changes in PKA binding or PKA activity. Conversely, mAKAP-S2195F, a mutation located in mAKAP-PP2A binding site, showed significant increase in both binding propensity to PKA and PKA activity. Additionally, mAKAP-L717V, a mutation flanking the mAKAP-spectrin repeat domain, exhibited a significant increase in PKA binding compared to wild type, but there was no change in PKA activity. We also demonstrate specific binding of wild-type mAKAP to PDE4D3. Binding results were demonstrated using immunoprecipitation and confirmed with surface plasmon resonance (Biacore-2000); functional results were demonstrated using activity assays, Ca(2+) measurements, and Western blot. Comparative analysis of the binding responses of mutations to mAKAP could provide important information about how these mutations modulate signaling.
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36
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Gorelik J, Wright PT, Lyon AR, Harding SE. Spatial control of the βAR system in heart failure: the transverse tubule and beyond. Cardiovasc Res 2013; 98:216-24. [PMID: 23345264 DOI: 10.1093/cvr/cvt005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The beta1-adrenoceptors (β(1)AR) and beta-2 (β(2)AR) adrenoceptors represent the predominant pathway for sympathetic control of myocardial function. Diverse mechanisms have evolved to translate signalling via these two molecules into differential effects on physiology. In this review, we discuss how the functions of the βAR are organized from the level of secondary messengers to the whole heart to achieve this. Using novel microscopy and bio-imaging methods researchers have uncovered subtle organization of the control of cyclic adenosine monophosphate (cAMP), the predominant positively inotropic pathway for the βAR. The β(2)AR in particular is demonstrated to give rise to highly compartmentalized, spatially confined cAMP signals. Organization of β(2)AR within the T-tubule and caveolae of cardiomyocytes concentrates this receptor with molecules which buffer and shape its cAMP signal to give fine control. This situation is undermined in various forms of heart failure. Human and animal models of heart failure demonstrate disruption of cellular micro-architecture which contributes to the change in response to cardiac βARs. Loss of cellular structure has proved key to the observed loss of confined β(2)AR signalling. Some pharmacological and genetic treatments have been successful in returning failing cells to a more structured phenotype. Within these cells it has been possible to observe the partial restoration of normal β(2)AR signalling. At the level of the organ, the expression of the two βAR subtypes varies between regions with the β(2)AR forming a greater proportion of the βAR population at the apex. This distribution may contribute to regional wall motion abnormalities in Takotsubo cardiomyopathy, a syndrome of high sympathetic activity, where the phosphorylated β(2)AR can signal via Gi protein to produce negatively inotropic effects.
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Affiliation(s)
- Julia Gorelik
- Department of Cardiovascular Medicine, National Heart and Lung Institute, Imperial College, 4th floor, Imperial Centre for Translational and Experimental Medicine, Hammersmith Campus, Du Cane Road, London W12 0NN, UK.
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Burgoyne JR, Eaton P. Detecting disulfide-bound complexes and the oxidative regulation of cyclic nucleotide-dependent protein kinases by H2O2. Methods Enzymol 2013; 528:111-28. [PMID: 23849862 DOI: 10.1016/b978-0-12-405881-1.00007-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hydrogen peroxide regulates intracellular signaling by oxidatively converting susceptible cysteine thiols to a modified state, which includes the formation of intermolecular disulfides. This type of oxidative modification can occur within the cAMP- and cGMP-dependent protein kinases often referred to as PKA and PKG, which have important roles in regulating cardiac contractility and systemic blood pressure. Both kinases are stimulated through conical pathways that elevate their respective cyclic nucleotides leading to direct kinase stimulation. However, PKA and PKG can also be functionally modulated independently of cyclic nucleotide stimulation through direct cysteine thiol oxidation leading to intermolecular disulfide formation. In the case of PKG, the formation of an intermolecular disulfide between two parallel dimeric subunits leads to enhanced kinase affinity for substrate. For PKA, the formation of two intermolecular disulfides between antiparallel dimeric regulatory RI subunits increases the affinity of this kinase for its binding partners, the A-kinase anchoring proteins, leading to increased PKA localization to its substrates. In this chapter, we describe the methods for detecting intermolecular disulfide-bound proteins and monitoring PKA and PKG oxidation within biological samples.
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Affiliation(s)
- Joseph R Burgoyne
- King's College London, Cardiovascular Division, The Rayne Institute, London, United Kingdom
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38
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Bortoluzzi A, Ceolotto G, Gola E, Sticca A, Bova S, Morando F, Piano S, Fasolato S, Rosi S, Gatta A, Angeli P. Positive cardiac inotropic effect of albumin infusion in rodents with cirrhosis and ascites: molecular mechanisms. Hepatology 2013; 57:266-76. [PMID: 22911662 DOI: 10.1002/hep.26021] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 08/01/2012] [Indexed: 12/14/2022]
Abstract
UNLABELLED The aim of this study was to evaluate the effect and molecular mechanism of albumin infusion on cardiac contractility in experimental cirrhosis with ascites. Cardiac contractility was recorded ex vivo in rats with cirrhosis and ascites and in control rats after the injection in the caudal vein of albumin, saline, or hydroxyethyl starch (HES). Gene and protein expression of β-receptors and pathways involved in their intracellular signaling such as Gα(i2) protein (Gα(i2)), adenylate cyclase 3 (Adcy3), protein expression of tumor necrosis factor alpha (TNF-α) and inducible nitric oxide synthase (iNOS), were evaluated in cardiac tissue in both groups. Phosphorylation and membrane-translocation of the cytosolic components of nicotinamide adenine dinucleotide phosphate (NAD(P)H)-oxidase and translocation of nuclear factor kappa B (NF-κB) were also evaluated. After saline intravenous injection, cardiac contractility was significantly reduced in rats with cirrhosis as compared to control rats (P < 0.01). This was associated with: (1) increased expression of protein Gα(i2) (P < 0.05), TNF-α (P < 0.05), iNOS (P < 0.05); (2) increased NAD(P)H-oxidase activity (P < 0.05); (3) increased nuclear translocation of NF-κB (P < 0.05); and (4) lower expression of Adcy 3 (P < 0.05) in cardiac tissue of rats with cirrhosis. After albumin injection cardiac contractility (P < 0.01), protein expression of TNF-α, iNOS, Gα(i2), and Adcy3, NAD(P)H-oxidase activity and nuclear translocation of NF-κB in cardiac tissue of rats with cirrhosis were reversed to control levels (P < 0.05). HES injection did not modify cardiac contractility and nuclear translocation of NF-κB in cardiac tissue of rats with cirrhosis. CONCLUSION Albumin exerts a positive cardiac inotropic effect in rats with cirrhosis and ascites counteracting the negative effects of oxidative stress- and TNF-α-induced activation of NF-κB-iNOS pathway and oxidative stress-induced alteration of β-receptor signaling.
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Affiliation(s)
- Alessia Bortoluzzi
- Department of Medicine DIMED, University of Padova Medical School, Italy
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Abstract
Spatial and temporal organization of signal transduction is coordinated through the segregation of signaling enzymes in selected cellular compartments. This highly evolved regulatory mechanism ensures the activation of selected enzymes only in the vicinity of their target proteins. In this context, cAMP-responsive triggering of protein kinase A is modulated by a family of scaffold proteins referred to as A-kinase anchoring proteins. A-kinase anchoring proteins form the core of multiprotein complexes and enable simultaneous but segregated cAMP signaling events to occur in defined cellular compartments. In this review we will focus on the description of A-kinase anchoring protein function in the regulation of cardiac physiopathology.
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Affiliation(s)
- Alessia Perino
- Molecular Biotechnology Center, Department of Genetics, Biology and Biochemistry, University of Torino, Torino, Italy
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40
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Shanks MO, Lund LM, Manni S, Russell M, Mauban JRH, Bond M. Chromodomain helicase binding protein 8 (Chd8) is a novel A-kinase anchoring protein expressed during rat cardiac development. PLoS One 2012; 7:e46316. [PMID: 23071553 PMCID: PMC3468582 DOI: 10.1371/journal.pone.0046316] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 08/29/2012] [Indexed: 11/19/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) bind the regulatory subunits of protein kinase A (PKA) and localize the holoenzyme to discrete signaling microdomains in multiple subcellular compartments. Despite emerging evidence for a nuclear pool of PKA that rapidly responds to activation of the PKA signaling cascade, only a few AKAPs have been identified that localize to the nucleus. Here we show a PKA-binding domain in the amino terminus of Chd8, and demonstrate subcellular colocalization of Chd8 with RII. RII overlay and immunoprecipitation assays demonstrate binding between Chd8-S and RIIα. Binding is abrogated upon dephosphorylation of RIIα. By immunofluorescence, we identified nuclear and perinuclear pools of Chd8 in HeLa cells and rat neonatal cardiomyocytes. We also show high levels of Chd8 mRNA in RNA extracted from post-natal rat hearts. These data add Chd8 to the short list of known nuclear AKAPs, and implicate a function for Chd8 in post-natal rat cardiac development.
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Affiliation(s)
- Maureen O. Shanks
- Department of Physiology, University of Maryland Baltimore, Baltimore, Maryland, United States of America
| | - Linda M. Lund
- Department of Biochemistry, University of Maryland Baltimore, Baltimore, Maryland, United States of America
| | - Sabrina Manni
- Department of Medicine, Clinical Immunology and Hematology Branches, University of Padova, Padova, Italy
- Venetian Institute of Molecular Medicine (VIMM), Padova, Italy
| | - Mary Russell
- Department of Biological Sciences, Trumbull Campus, Kent State University, Warren, Ohio, United States of America
| | - Joseph R. H. Mauban
- Department of Physiology, University of Maryland Baltimore, Baltimore, Maryland, United States of America
| | - Meredith Bond
- Department of Physiology, University of Maryland Baltimore, Baltimore, Maryland, United States of America
- College of Sciences and Health Professions, Cleveland State University, Cleveland, Ohio, United States of America
- * E-mail:
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Scott JD, Dessauer CW, Taskén K. Creating order from chaos: cellular regulation by kinase anchoring. Annu Rev Pharmacol Toxicol 2012; 53:187-210. [PMID: 23043438 DOI: 10.1146/annurev-pharmtox-011112-140204] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Second messenger responses rely on where and when the enzymes that propagate these signals become active. Spatial and temporal organization of certain signaling enzymes is controlled in part by A-kinase anchoring proteins (AKAPs). This family of regulatory proteins was originally classified on the basis of their ability to compartmentalize the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (also known as protein kinase A, or PKA). However, it is now recognized that AKAPs position G protein-coupled receptors, adenylyl cyclases, G proteins, and their effector proteins in relation to protein kinases and signal termination enzymes such as phosphodiesterases and protein phosphatases. This arrangement offers a simple and efficient means to limit the scope, duration, and directional flow of information to sites deep within the cell. This review focuses on the pros and cons of reagents that define the biological role of kinase anchoring inside cells and discusses recent advances in our understanding of anchored second messenger signaling in the cardiovascular and immune systems.
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Affiliation(s)
- John D Scott
- Howard Hughes Medical Institute and Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195, USA.
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Diviani D, Maric D, Pérez López I, Cavin S, Del Vescovo CD. A-kinase anchoring proteins: molecular regulators of the cardiac stress response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:901-8. [PMID: 22889610 DOI: 10.1016/j.bbamcr.2012.07.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 07/26/2012] [Accepted: 07/29/2012] [Indexed: 12/29/2022]
Abstract
In response to stress or injury the heart undergoes a pathological remodeling process, associated with hypertrophy, cardiomyocyte death and fibrosis, that ultimately causes cardiac dysfunction and heart failure. It has become increasingly clear that signaling events associated with these pathological cardiac remodeling events are regulated by scaffolding and anchoring proteins, which allow coordination of pathological signals in space and time. A-kinase anchoring proteins (AKAPs) constitute a family of functionally related proteins that organize multiprotein signaling complexes that tether the cAMP-dependent protein kinase (PKA) as well as other signaling enzymes to ensure integration and processing of multiple signaling pathways. This review will discuss the role of AKAPs in the cardiac response to stress. Particular emphasis will be given to the adaptative process associated with cardiac hypoxia as well as the remodeling events linked to cardiac hypertrophy and heart failure. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Dario Diviani
- Département de Pharmacologie et de Toxicologie, Faculté de Biologie et Médecine, Lausanne, Switzerland.
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Abstract
3'-5'-Cyclic adenosine monophosphate (cAMP), generated by adenylyl cyclase (AC), serves as a second messenger in signaling pathways regulating many aspects of cardiac physiology, including contraction rate and action potential duration, and in the pathophysiology of hypertrophy and heart failure. A kinase-anchoring proteins localize the effect of cAMP in space and time by organizing receptors, AC, protein kinase A, and other components of the cAMP cascade into multiprotein complexes. In this review, we discuss how the interaction of A kinase-anchoring proteins with distinct AC isoforms affects cardiovascular physiology.
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Local termination of 3'-5'-cyclic adenosine monophosphate signals: the role of A kinase anchoring protein-tethered phosphodiesterases. J Cardiovasc Pharmacol 2012; 58:345-53. [PMID: 21654331 DOI: 10.1097/fjc.0b013e3182214f2b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A kinase anchoring proteins (AKAPs) belong to a family of functionally related proteins capable of binding protein kinase A (PKA) and tether it to relevant targets. In this way, AKAPs organize macromolecular complexes to segregate PKA activity and retain signal specificity. In the heart, AKAP-PKA interaction is central to the regulation of cardiac contractility. Phosphodiesterases belong to a large superfamily of enzymes that degrade 3'-5'-cyclic adenosine monophosphate (cAMP). They possess diverse catalytic properties and multiple regulatory mechanisms and control the duration and amplitude of the cAMP signal, including its propagation in space. AKAPs, together with PKA, can also assemble phosphodiesterases thereby providing a means to locally control cAMP dynamics at the level of single macromolecular complexes. This allows for the fine tuning of the cAMP response to the specific demands of the cell.
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45
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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: 16] [Impact Index Per Article: 1.3] [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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Kuster DWD, Bawazeer AC, Zaremba R, Goebel M, Boontje NM, van der Velden J. Cardiac myosin binding protein C phosphorylation in cardiac disease. J Muscle Res Cell Motil 2011; 33:43-52. [PMID: 22127559 PMCID: PMC3351594 DOI: 10.1007/s10974-011-9280-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 11/23/2011] [Indexed: 12/14/2022]
Abstract
Perturbations in sarcomeric function may in part underlie systolic and diastolic dysfunction of the failing heart. Sarcomeric dysfunction has been ascribed to changes in phosphorylation status of sarcomeric proteins caused by an altered balance between intracellular kinases and phosphatases during the development of cardiac disease. In the present review we discuss changes in phosphorylation of the thick filament protein myosin binding protein C (cMyBP-C) reported in failing myocardium, with emphasis on phosphorylation changes observed in familial hypertrophic cardiomyopathy caused by mutations in MYBPC3. Moreover, we will discuss assays which allow to distinguish between functional consequences of mutant sarcomeric proteins and (mal)adaptive changes in sarcomeric protein phosphorylation.
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MESH Headings
- Animals
- Calcium/metabolism
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Cardiomyopathy, Hypertrophic, Familial/pathology
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Heart Failure, Systolic/metabolism
- Heart Failure, Systolic/pathology
- Humans
- Mice
- Mice, Transgenic
- Mutation
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phosphoric Monoester Hydrolases/metabolism
- Phosphorylation
- Sarcomeres/metabolism
- Sarcomeres/pathology
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Affiliation(s)
- Diederik W D Kuster
- Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands.
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Stangherlin A, Zaccolo M. Phosphodiesterases and subcellular compartmentalized cAMP signaling in the cardiovascular system. Am J Physiol Heart Circ Physiol 2011; 302:H379-90. [PMID: 22037184 DOI: 10.1152/ajpheart.00766.2011] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Phosphodiesterases are key enzymes in the cAMP signaling cascade. They convert cAMP in its inactive form 5'-AMP and critically regulate the intensity and the duration of cAMP-mediated signals. Multiple isoforms exist that possess different intracellular distributions, different affinities for cAMP, and different catalytic and regulatory properties. This complex repertoire of enzymes provides a multiplicity of ways to modulate cAMP levels, to integrate more signaling pathways, and to respond to the specific needs of the cell within distinct subcellular domains. In this review we summarize key findings on phosphodiesterase compartmentalization in the cardiovascular system.
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Affiliation(s)
- Alessandra Stangherlin
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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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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Liu J, Sirenko S, Juhaszova M, Ziman B, Shetty V, Rain S, Shukla S, Spurgeon HA, Vinogradova TM, Maltsev VA, Lakatta EG. A full range of mouse sinoatrial node AP firing rates requires protein kinase A-dependent calcium signaling. J Mol Cell Cardiol 2011; 51:730-9. [PMID: 21840316 DOI: 10.1016/j.yjmcc.2011.07.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 06/24/2011] [Accepted: 07/26/2011] [Indexed: 11/24/2022]
Abstract
Recent perspectives on sinoatrial nodal cell (SANC)(*) function indicate that spontaneous sarcoplasmic reticulum (SR) Ca(2+) cycling, i.e. an intracellular "Ca(2+) clock," driven by cAMP-mediated, PKA-dependent phosphorylation, interacts with an ensemble of surface membrane electrogenic molecules ("surface membrane clock") to drive SANC normal automaticity. The role of AC-cAMP-PKA-Ca(2+) signaling cascade in mouse, the species most often utilized for genetic manipulations, however, has not been systematically tested. Here we show that Ca(2+) cycling proteins (e.g. RyR2, NCX1, and SERCA2) are abundantly expressed in mouse SAN and that spontaneous, rhythmic SR generated local Ca(2+) releases (LCRs) occur in skinned mouse SANC, clamped at constant physiologic [Ca(2+)]. Mouse SANC also exhibits a high basal level of phospholamban (PLB) phosphorylation at the PKA-dependent site, Serine16. Inhibition of intrinsic PKA activity or inhibition of PDE in SANC, respectively: reduces or increases PLB phosphorylation, and markedly prolongs or reduces the LCR period; and markedly reduces or accelerates SAN spontaneous firing rate. Additionally, the increase in AP firing rate by PKA-dependent phosphorylation by β-adrenergic receptor (β-AR) stimulation requires normal intracellular Ca(2+) cycling, because the β-AR chronotropic effect is markedly blunted when SR Ca(2+) cycling is disrupted. Thus, AC-cAMP-PKA-Ca(2+) signaling cascade is a major mechanism of normal automaticity in mouse SANC.
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Affiliation(s)
- Jie Liu
- Laboratory of Cardiovascular Science, Intramural Research Program, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore MD 21224, USA
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Aye TT, Soni S, van Veen TAB, van der Heyden MAG, Cappadona S, Varro A, de Weger RA, de Jonge N, Vos MA, Heck AJR, Scholten A. Reorganized PKA-AKAP associations in the failing human heart. J Mol Cell Cardiol 2011; 52:511-8. [PMID: 21712045 DOI: 10.1016/j.yjmcc.2011.06.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/20/2011] [Accepted: 06/02/2011] [Indexed: 10/18/2022]
Abstract
Here we reveal that the characterization of large-scale re-arrangements of signaling scaffolds induced by heart failure can serve as a novel concept to identify more specific therapeutic targets. In the mammalian heart, the cAMP pathway, with the cAMP-dependent protein kinase (PKA) in a central role, acts directly downstream of adrenergic receptors to mediate cardiac contractility and rhythm. Heart failure, characterized by severe alterations in adrenergic stimulation is, amongst other interventions, often treated with β-blockers. Contrasting results, however, have shown both beneficial and detrimental effects of decreased cAMP levels in failing hearts. We hypothesize that the origin of this behavior lies in the complex spatiotemporal organization of the regulatory subunit of PKA (PKA-R), which associates tightly with various A-kinase anchoring proteins (AKAPs) to specifically localize PKA's activity. Using chemical proteomics directly applied to human patient and control heart tissue we demonstrate that the association profile of PKA-R with several AKAPs is severely altered in the failing heart, for instance effecting the interaction between PKA and the novel AKAP SPHKAP was 6-fold upregulated upon failing heart conditions. Also a significant increase in captured cGMP-dependent protein kinase (PKG) and phosphodiesterase 2 (PDE2) was observed. The observed altered profiles can already explain many aspects of the aberrant cAMP-response in the failing human heart, validating that this dataset may provide a resource for several novel, more specific, treatment options. This article is part of a Special Issue entitled "Local Signaling in Myocytes".
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Affiliation(s)
- Thin-Thin Aye
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
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