51
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Parker BL, Shepherd NE, Trefely S, Hoffman NJ, White MY, Engholm-Keller K, Hambly BD, Larsen MR, James DE, Cordwell SJ. Structural basis for phosphorylation and lysine acetylation cross-talk in a kinase motif associated with myocardial ischemia and cardioprotection. J Biol Chem 2014; 289:25890-906. [PMID: 25008320 DOI: 10.1074/jbc.m114.556035] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Myocardial ischemia and cardioprotection by ischemic pre-conditioning induce signal networks aimed at survival or cell death if the ischemic period is prolonged. These pathways are mediated by protein post-translational modifications that are hypothesized to cross-talk with and regulate each other. Phosphopeptides and lysine-acetylated peptides were quantified in isolated rat hearts subjected to ischemia or ischemic pre-conditioning, with and without splitomicin inhibition of lysine deacetylation. We show lysine acetylation (acetyl-Lys)-dependent activation of AMP-activated protein kinase, AKT, and PKA kinases during ischemia. Phosphorylation and acetyl-Lys sites mapped onto tertiary structures were proximal in >50% of proteins investigated, yet they were mutually exclusive in 50 ischemic pre-conditioning- and/or ischemia-associated peptides containing the KXXS basophilic protein kinase consensus motif. Modifications in this motif were modeled in the C terminus of muscle-type creatine kinase. Acetyl-Lys increased proximal dephosphorylation by 10-fold. Structural analysis of modified muscle-type creatine kinase peptide variants by two-dimensional NMR revealed stabilization via a lysine-phosphate salt bridge, which was disrupted by acetyl-Lys resulting in backbone flexibility and increased phosphatase accessibility.
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Affiliation(s)
- Benjamin L Parker
- From the Discipline of Pathology, School of Medical Sciences, University of Sydney, Sydney 2006, Australia, the Diabetes and Obesity Program, Biological Mass Spectrometry Unit, Garvan Institute of Medical Research, 2010 Australia
| | | | | | - Nolan J Hoffman
- the Diabetes and Obesity Program, Biological Mass Spectrometry Unit, Garvan Institute of Medical Research, 2010 Australia
| | - Melanie Y White
- the School of Molecular Bioscience and the Charles Perkins Centre, University of Sydney, Sydney 2006, Australia, and
| | | | - Brett D Hambly
- From the Discipline of Pathology, School of Medical Sciences, University of Sydney, Sydney 2006, Australia, the Charles Perkins Centre, University of Sydney, Sydney 2006, Australia, and
| | - Martin R Larsen
- the Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - David E James
- the Diabetes and Obesity Program, Biological Mass Spectrometry Unit, Garvan Institute of Medical Research, 2010 Australia, the Charles Perkins Centre, University of Sydney, Sydney 2006, Australia, and
| | - Stuart J Cordwell
- From the Discipline of Pathology, School of Medical Sciences, University of Sydney, Sydney 2006, Australia, the School of Molecular Bioscience and the Charles Perkins Centre, University of Sydney, Sydney 2006, Australia, and
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52
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Role of soluble adenylyl cyclase in cell death and growth. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2646-55. [PMID: 25010002 DOI: 10.1016/j.bbadis.2014.06.034] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/26/2014] [Accepted: 06/27/2014] [Indexed: 12/13/2022]
Abstract
cAMP signaling is an evolutionarily conserved intracellular communication system controlling numerous cellular functions. Until recently, transmembrane adenylyl cyclase (tmAC) was considered the major source for cAMP in the cell, and the role of cAMP signaling was therefore attributed exclusively to the activity of this family of enzymes. However, increasing evidence demonstrates the role of an alternative, intracellular source of cAMP produced by type 10 soluble adenylyl cyclase (sAC). In contrast to tmAC, sAC produces cAMP in various intracellular microdomains close to specific cAMP targets, e.g., in nucleus and mitochondria. Ongoing research demonstrates involvement of sAC in diverse physiological and pathological processes. The present review is focused on the role of cAMP signaling, particularly that of sAC, in cell death and growth. Although the contributions of sAC to the regulation of these cellular functions have only recently been discovered, current data suggest that sAC plays key roles in mitochondrial bioenergetics and the mitochondrial apoptosis pathway, as well as cell proliferation and development. Furthermore, recent reports suggest the importance of sAC in several pathologies associated with apoptosis as well as in oncogenesis. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease.
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Murine AKAP7 has a 2',5'-phosphodiesterase domain that can complement an inactive murine coronavirus ns2 gene. mBio 2014; 5:e01312-14. [PMID: 24987090 PMCID: PMC4161237 DOI: 10.1128/mbio.01312-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Viral 2′,5′-phosphodiesterases (2′,5′-PDEs) help disparate RNA viruses evade the antiviral activity of interferon (IFN) by degrading 2′,5′-oligoadenylate (2-5A) activators of RNase L. A kinase anchoring proteins (AKAPs) bind the regulatory subunits of protein kinase A (PKA) to localize and organize cyclic AMP (cAMP) signaling during diverse physiological processes. Among more than 43 AKAP isoforms, AKAP7 appears to be unique in its homology to viral 2′,5′-PDEs. Here we show that mouse AKAP7 rapidly degrades 2-5A with kinetics similar to that of murine coronavirus (mouse hepatitis virus [MHV]) strain A59 ns2 and human rotavirus strain WA VP3 proteins. To determine whether AKAP7 could substitute for a viral 2′,5′-PDE, we inserted AKAP7 cDNA into an MHV genome with an inactivated ns2 gene. The AKAP7 PDE domain or N-terminally truncated AKAP7 (both lacking a nuclear localization motif), but not full-length AKAP7 or a mutant, AKAP7H185R, PDE domain restored the infectivity of ns2 mutant MHV in bone marrow macrophages and in livers of infected mice. Interestingly, the AKAP7 PDE domain and N-terminally deleted AKAP7 were present in the cytoplasm (the site of MHV replication), whereas full-length AKAP7 was observed only in nuclei. We suggest the possibility that viral acquisition of the host AKAP7 PDE domain might have occurred during evolution, allowing diverse RNA viruses to antagonize the RNase L pathway. Early virus-host interactions determine whether an infection is established, highlighting the need to understand fundamental mechanisms regulating viral pathogenesis. Recently, our laboratories reported a novel mode of regulation of the IFN antiviral response. We showed that the coronavirus MHV accessory protein ns2 antagonizes the type I IFN response, promoting viral replication and hepatitis. ns2 confers virulence by cleaving 2′,5′-oligoadenylate (2-5A) activators of RNase L in macrophages. We also reported that the rotavirus VP3 C-terminal domain (VP3-CTD) cleaves 2-5A and that it may rescue ns2 mutant MHV. Here we report that a cellular protein, AKAP7, has an analogous 2′,5′-phosphodiesterase (2′,5′-PDE) domain that is able to restore the growth of chimeric MHV expressing inactive ns2. The proviral effect requires cytoplasmic localization of the AKAP7 PDE domain. We speculate that AKAP7 is the ancestral precursor of viral proteins, such as ns2 and VP3, that degrade 2-5A to evade the antiviral activity of RNase L.
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Abstract
3'-5'-cyclic adenosine monophosphate (cAMP) is a second messenger, which plays an important role in the heart. It is generated in response to activation of G-protein-coupled receptors (GPCRs). Initially, it was thought that protein kinase A (PKA) exclusively mediates cAMP-induced cellular responses such as an increase in cardiac contractility, relaxation, and heart rate. With the identification of the exchange factor directly activated by cAMP (EPAC) and hyperpolarizing cyclic nucleotide-gated (HCN) channels as cAMP effector proteins it became clear that a protein network is involved in cAMP signaling. The Popeye domain containing (Popdc) genes encode yet another family of cAMP-binding proteins, which are prominently expressed in the heart. Loss-of-function mutations in mice are associated with cardiac arrhythmia and impaired skeletal muscle regeneration. Interestingly, the cardiac phenotype, which is present in both, Popdc1 and Popdc2 null mutants, is characterized by a stress-induced sinus bradycardia, suggesting that Popdc proteins participate in cAMP signaling in the sinuatrial node. The identification of the two-pore channel TREK-1 and Caveolin 3 as Popdc-interacting proteins represents a first step into understanding the mechanisms of heart rate modulation triggered by Popdc proteins.
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55
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Wang Y, Ho TG, Bertinetti D, Neddermann M, Franz E, Mo GCH, Schendowich LP, Sukhu A, Spelts RC, Zhang J, Herberg FW, Kennedy EJ. Isoform-selective disruption of AKAP-localized PKA using hydrocarbon stapled peptides. ACS Chem Biol 2014; 9:635-42. [PMID: 24422448 PMCID: PMC3985448 DOI: 10.1021/cb400900r] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
![]()
A-kinase
anchoring proteins (AKAPs) play an important role in the
spatial and temporal regulation of protein kinase A (PKA) by scaffolding
critical intracellular signaling complexes. Here we report the design
of conformationally constrained peptides that disrupt interactions
between PKA and AKAPs in an isoform-selective manner. Peptides derived
from the A Kinase Binding (AKB) domain of several AKAPs were chemically
modified to contain an all-hydrocarbon staple and target the docking/dimerization
domain of PKA-R, thereby occluding AKAP interactions. The peptides
are cell-permeable against diverse human cell lines, are highly isoform-selective
for PKA-RII, and can effectively inhibit interactions between AKAPs
and PKA-RII in intact cells. These peptides can be applied as useful
reagents in cell-based studies to selectively disrupt AKAP-localized
PKA-RII activity and block AKAP signaling complexes. In summary, the
novel hydrocarbon-stapled peptides developed in this study represent
a new class of AKAP disruptors to study compartmentalized RII-regulated
PKA signaling in cells.
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Affiliation(s)
- Yuxiao Wang
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
| | - Tienhuei G. Ho
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
| | | | | | - Eugen Franz
- Department
of Biochemistry, University of Kassel, 34132 Kassel, Germany
| | - Gary C. H. Mo
- Department
of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Lewis P. Schendowich
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
| | - Avinash Sukhu
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
| | - Raybun C. Spelts
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
| | - Jin Zhang
- Department
of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | | | - Eileen J. Kennedy
- Department
of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, Georgia 30602, United States
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56
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Weiss S, Oz S, Benmocha A, Dascal N. Regulation of cardiac L-type Ca²⁺ channel CaV1.2 via the β-adrenergic-cAMP-protein kinase A pathway: old dogmas, advances, and new uncertainties. Circ Res 2013; 113:617-31. [PMID: 23948586 DOI: 10.1161/circresaha.113.301781] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the heart, adrenergic stimulation activates the β-adrenergic receptors coupled to the heterotrimeric stimulatory Gs protein, followed by subsequent activation of adenylyl cyclase, elevation of cyclic AMP levels, and protein kinase A (PKA) activation. One of the main targets for PKA modulation is the cardiac L-type Ca²⁺ channel (CaV1.2) located in the plasma membrane and along the T-tubules, which mediates Ca²⁺ entry into cardiomyocytes. β-Adrenergic receptor activation increases the Ca²⁺ current via CaV1.2 channels and is responsible for the positive ionotropic effect of adrenergic stimulation. Despite decades of research, the molecular mechanism underlying this modulation has not been fully resolved. On the contrary, initial reports of identification of key components in this modulation were later refuted using advanced model systems, especially transgenic animals. Some of the cardinal debated issues include details of specific subunits and residues in CaV1.2 phosphorylated by PKA, the nature, extent, and role of post-translational processing of CaV1.2, and the role of auxiliary proteins (such as A kinase anchoring proteins) involved in PKA regulation. In addition, the previously proposed crucial role of PKA in modulation of unstimulated Ca²⁺ current in the absence of β-adrenergic receptor stimulation and in voltage-dependent facilitation of CaV1.2 remains uncertain. Full reconstitution of the β-adrenergic receptor signaling pathway in heterologous expression systems remains an unmet challenge. This review summarizes the past and new findings, the mechanisms proposed and later proven, rejected or disputed, and emphasizes the essential issues that remain unresolved.
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Affiliation(s)
- Sharon Weiss
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel.
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57
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Esseltine JL, Scott JD. AKAP signaling complexes: pointing towards the next generation of therapeutic targets? Trends Pharmacol Sci 2013; 34:648-55. [PMID: 24239028 DOI: 10.1016/j.tips.2013.10.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/11/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
A-kinase anchoring proteins (AKAPs) streamline signal transduction by localizing signaling enzymes with their substrates. Great strides have been made in elucidating the role of these macromolecular signaling complexes as new binding partners and novel AKAPs are continually being uncovered. The mechanics and dynamics of these multi-enzyme assemblies suggest that AKAP complexes are viable targets for therapeutic intervention. This review will highlight recent advances in AKAP research focusing on local signaling events that are perturbed in disease.
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Affiliation(s)
- Jessica L Esseltine
- Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, WA, USA
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58
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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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59
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Schäfer G, Milić J, Eldahshan A, Götz F, Zühlke K, Schillinger C, Kreuchwig A, Elkins JM, Abdul Azeez KR, Oder A, Moutty MC, Masada N, Beerbaum M, Schlegel B, Niquet S, Schmieder P, Krause G, von Kries JP, Cooper DMF, Knapp S, Rademann J, Rosenthal W, Klussmann E. Hoch funktionalisierte Terpyridine als kompetitive Inhibitoren von AKAP-PKA-Wechselwirkungen. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304686] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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60
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Schäfer G, Milić J, Eldahshan A, Götz F, Zühlke K, Schillinger C, Kreuchwig A, Elkins JM, Abdul Azeez KR, Oder A, Moutty MC, Masada N, Beerbaum M, Schlegel B, Niquet S, Schmieder P, Krause G, von Kries JP, Cooper DMF, Knapp S, Rademann J, Rosenthal W, Klussmann E. Highly functionalized terpyridines as competitive inhibitors of AKAP-PKA interactions. Angew Chem Int Ed Engl 2013; 52:12187-91. [PMID: 24115519 PMCID: PMC4138556 DOI: 10.1002/anie.201304686] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Indexed: 12/25/2022]
Affiliation(s)
- Gesa Schäfer
- Max Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Strasse 10, 13125 Berlin (Germany)
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61
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Visualizing CaMKII and CaM activity: a paradigm of compartmentalized signaling. J Mol Med (Berl) 2013; 91:907-16. [PMID: 23775230 DOI: 10.1007/s00109-013-1060-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 05/16/2013] [Accepted: 05/26/2013] [Indexed: 10/26/2022]
Abstract
Calcium (Ca(2+)) has long been recognized as a crucial intracellular messenger attaining stimuli-specific cellular outcomes via localized signaling. Ca(2+)-binding proteins, such as calmodulin (CaM), and its target proteins are key to the segregation and refinement of these Ca(2+)-dependent signaling events. This review not only summarizes the recent technological advances enabling the study of subcellular Ca(2+)-CaM and Ca(2+)-CaM-dependent protein kinase (CaMKII) signaling events but also highlights the outstanding challenges in the field.
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62
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A-kinase anchoring protein Lbc coordinates a p38 activating signaling complex controlling compensatory cardiac hypertrophy. Mol Cell Biol 2013; 33:2903-17. [PMID: 23716597 DOI: 10.1128/mcb.00031-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In response to stress, the heart undergoes a remodeling process associated with cardiac hypertrophy that eventually leads to heart failure. A-kinase anchoring proteins (AKAPs) have been shown to coordinate numerous prohypertrophic signaling pathways in cultured cardiomyocytes. However, it remains to be established whether AKAP-based signaling complexes control cardiac hypertrophy and remodeling in vivo. In the current study, we show that AKAP-Lbc assembles a signaling complex composed of the kinases PKN, MLTK, MKK3, and p38α that mediates the activation of p38 in cardiomyocytes in response to stress signals. To address the role of this complex in cardiac remodeling, we generated transgenic mice displaying cardiomyocyte-specific overexpression of a molecular inhibitor of the interaction between AKAP-Lbc and the p38-activating module. Our results indicate that disruption of the AKAP-Lbc/p38 signaling complex inhibits compensatory cardiomyocyte hypertrophy in response to aortic banding-induced pressure overload and promotes early cardiac dysfunction associated with increased myocardial apoptosis, stress gene activation, and ventricular dilation. Attenuation of hypertrophy results from a reduced protein synthesis capacity, as indicated by decreased phosphorylation of 4E-binding protein 1 and ribosomal protein S6. These results indicate that AKAP-Lbc enhances p38-mediated hypertrophic signaling in the heart in response to abrupt increases in the afterload.
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63
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Abstract
Phosphorylation of mitochondrial proteins has emerged as a major regulatory mechanism for metabolic adaptation. cAMP signaling and PKA phosphorylation of mitochondrial proteins have just started to be investigated, and the presence of cAMP-generating enzymes and PKA inside mitochondria is still controversial. Here, we discuss the role of cAMP in regulating mitochondrial bioenergetics through protein phosphorylation and the evidence for soluble adenylyl cyclase as the source of cAMP inside mitochondria.
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Affiliation(s)
- Federica Valsecchi
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, USA
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64
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Biophysical techniques for detection of cAMP and cGMP in living cells. Int J Mol Sci 2013; 14:8025-46. [PMID: 23584022 PMCID: PMC3645729 DOI: 10.3390/ijms14048025] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/22/2013] [Accepted: 04/07/2013] [Indexed: 11/16/2022] Open
Abstract
Cyclic nucleotides cAMP and cGMP are ubiquitous second messengers which regulate myriads of functions in virtually all eukaryotic cells. Their intracellular effects are often mediated via discrete subcellular signaling microdomains. In this review, we will discuss state-of-the-art techniques to measure cAMP and cGMP in biological samples with a particular focus on live cell imaging approaches, which allow their detection with high temporal and spatial resolution in living cells and tissues. Finally, we will describe how these techniques can be applied to the analysis of second messenger dynamics in subcellular signaling microdomains.
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65
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Perera RK, Nikolaev VO. Compartmentation of cAMP signalling in cardiomyocytes in health and disease. Acta Physiol (Oxf) 2013; 207:650-62. [PMID: 23383621 DOI: 10.1111/apha.12077] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 11/27/2012] [Accepted: 01/30/2013] [Indexed: 12/13/2022]
Abstract
3',5'-cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger critically involved in the regulation of heart function. It has been shown to act in discrete subcellular signalling compartments formed by differentially localized receptors, phosphodiesterases and protein kinases. Cardiac diseases such as hypertrophy or heart failure are associated with structural and functional remodelling of these microdomains which leads to changes in cAMP compartmentation. In this review, we will discuss recent key findings which provided new insights into cAMP compartmentation in cardiomyocytes with a particular focus on its alterations in heart disease.
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Affiliation(s)
- R. K. Perera
- Emmy Noether Group of the DFG, Department of Cardiology and Pneumology, European Heart Research Insitute Göttingen, Georg August University Medical Center; University of Göttingen; Göttingen; Germany
| | - V. O. Nikolaev
- Emmy Noether Group of the DFG, Department of Cardiology and Pneumology, European Heart Research Insitute Göttingen, Georg August University Medical Center; University of Göttingen; Göttingen; Germany
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66
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Stanley WC, Keehan KH. Update on innovative initiatives for the American Journal of Physiology-Heart and Circulatory Physiology. Am J Physiol Heart Circ Physiol 2013; 304:H1045-9. [PMID: 23457015 DOI: 10.1152/ajpheart.00082.2013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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67
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Chang CWJ, Lee L, Yu D, Dao K, Bossuyt J, Bers DM. Acute β-adrenergic activation triggers nuclear import of histone deacetylase 5 and delays G(q)-induced transcriptional activation. J Biol Chem 2012; 288:192-204. [PMID: 23161540 DOI: 10.1074/jbc.m112.382358] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During hemodynamic stress, catecholamines and neurohumoral stimuli may induce co-activation of G(q)-coupled receptors and β-adrenergic receptors (β-AR), leading to cardiac remodeling. Dynamic regulation of histone deacetylase 5 (HDAC5), a transcriptional repressor, is crucial during stress signaling due to its role in epigenetic control of fetal gene markers. Little is known about its regulation during acute and chronic β-AR stimulation and its cross-interaction with G(q) signaling in adult cardiac myocytes. Here, we evaluate the potential cross-talk between G(q)-driven and β-AR mediated signaling at the level of nucleocytoplasmic shuttling of HDAC5. We show the translocation of GFP-tagged wild type HDAC5 or mutants (S279A and S279D) in response to β-AR or G(q) agonists. Isoproterenol (ISO) or PKA activation results in strong nuclear accumulation of HDAC5 in contrast to nuclear export driven by Ca(2+)-calmodulin protein kinase II and protein kinase D. Moreover, nuclear accumulation of HDAC5 under acute ISO/PKA signaling is dependent on phosphorylation of Ser-279 and can block subsequent G(q)-mediated nuclear HDAC5 export. Intriguingly, the attenuation of G(q)-induced export is abolished after chronic PKA activation, yet nuclear HDAC5 remains elevated. Last, the effect of chronic β-AR signaling on HDAC5 translocation was examined in adult myocytes from a rabbit model of heart failure, where ISO-induced nuclear import is ablated, but G(q)-agonist mediated export is preserved. Acute β-AR/PKA activation protects against hypertrophic signaling by delaying G(q)-mediated transcriptional activation. This serves as a key physiological control switch before allowing genetic reprogramming via HDAC5 nuclear export during more severe stress, such as heart failure.
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Affiliation(s)
- Chia-Wei Jenny Chang
- Department of Pharmacology, University of California, Davis, California 95616-8636, USA
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68
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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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69
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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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70
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Burmeister BT, Taglieri DM, Wang L, Carnegie GK. Src homology 2 domain-containing phosphatase 2 (Shp2) is a component of the A-kinase-anchoring protein (AKAP)-Lbc complex and is inhibited by protein kinase A (PKA) under pathological hypertrophic conditions in the heart. J Biol Chem 2012; 287:40535-46. [PMID: 23045525 DOI: 10.1074/jbc.m112.385641] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AKAP-Lbc is a scaffold protein that coordinates cardiac hypertrophic signaling. RESULTS AKAP-Lbc interacts with Shp2, facilitating its regulation by PKA. CONCLUSION AKAP-Lbc integrates PKA and Shp2 signaling in the heart. Under pathological hypertrophic conditions Shp2 is phosphorylated by PKA, and phosphatase activity is inhibited. SIGNIFICANCE Inhibition of Shp2 activity through AKAP-Lbc-anchored PKA is a previously unrecognized mechanism that may promote pathological cardiac hypertrophy. Pathological cardiac hypertrophy (an increase in cardiac mass resulting from stress-induced cardiac myocyte growth) is a major factor underlying heart failure. Our results identify a novel mechanism of Shp2 inhibition that may promote cardiac hypertrophy. We demonstrate that the tyrosine phosphatase, Shp2, is a component of the A-kinase-anchoring protein (AKAP)-Lbc complex. AKAP-Lbc facilitates PKA phosphorylation of Shp2, which inhibits its protein-tyrosine phosphatase activity. Given the important cardiac roles of both AKAP-Lbc and Shp2, we investigated the AKAP-Lbc-Shp2 interaction in the heart. AKAP-Lbc-tethered PKA is implicated in cardiac hypertrophic signaling; however, mechanism of PKA action is unknown. Mutations resulting in loss of Shp2 catalytic activity are also associated with cardiac hypertrophy and congenital heart defects. Our data indicate that AKAP-Lbc integrates PKA and Shp2 signaling in the heart and that AKAP-Lbc-associated Shp2 activity is reduced in hypertrophic hearts in response to chronic β-adrenergic stimulation and PKA activation. Thus, while induction of cardiac hypertrophy is a multifaceted process, inhibition of Shp2 activity through AKAP-Lbc-anchored PKA is a previously unrecognized mechanism that may promote compensatory cardiac hypertrophy.
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Affiliation(s)
- Brian T Burmeister
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, IL 60612, USA
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Cardiomyocytes from AKAP7 knockout mice respond normally to adrenergic stimulation. Proc Natl Acad Sci U S A 2012; 109:17099-104. [PMID: 23035250 DOI: 10.1073/pnas.1215219109] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein kinase A (PKA) is activated during sympathetic stimulation of the heart and phosphorylates key proteins involved in cardiac Ca(2+) handling, including the L-type Ca(2+) channel (Ca(V)1.2) and phospholamban (PLN). This results in acceleration and amplification of the beat-to-beat changes in cytosolic Ca(2+) in cardiomyocytes and, in turn, an increased rate and force of contraction. PKA is held in proximity to its substrates by protein scaffolds called A kinase anchoring proteins (AKAPs). It has been suggested that the short and long isoforms of AKAP7 (also called AKAP15/18) localize PKA in complexes with Ca(V)1.2 and PLN, respectively. We generated an AKAP7 KO mouse in which all isoforms were deleted and tested whether Ca(2+) current, intracellular Ca(2+) concentration, or Ca(2+) reuptake were impaired in isolated adult ventricular cardiomyocytes following stimulation with the β-adrenergic agonist isoproterenol. KO cardiomyocytes responded normally to adrenergic stimulation, as measured by whole-cell patch clamp or a fluorescent intracellular Ca(2+) indicator. Phosphorylation of Ca(V)1.2 and PLN were also unaffected by genetic deletion of AKAP7. Immunoblot and RT-PCR revealed that only the long isoforms of AKAP7 were detectable in ventricular cardiomyocytes. The results indicate that AKAP7 is not required for regulation of Ca(2+) handling in mouse cardiomyocytes.
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Tröger J, Moutty MC, Skroblin P, Klussmann E. A-kinase anchoring proteins as potential drug targets. Br J Pharmacol 2012; 166:420-33. [PMID: 22122509 DOI: 10.1111/j.1476-5381.2011.01796.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) crucially contribute to the spatial and temporal control of cellular signalling. They directly interact with a variety of protein binding partners and cellular constituents, thereby directing pools of signalling components to defined locales. In particular, AKAPs mediate compartmentalization of cAMP signalling. Alterations in AKAP expression and their interactions are associated with or cause diseases including chronic heart failure, various cancers and disorders of the immune system such as HIV. A number of cellular dysfunctions result from mutations of specific AKAPs. The link between malfunctions of single AKAP complexes and a disease makes AKAPs and their interactions interesting targets for the development of novel drugs. LINKED ARTICLES This article is part of a themed section on Novel cAMP Signalling Paradigms. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-2.
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Affiliation(s)
- Jessica Tröger
- Max Delbrück Center for Molecular Medicine Berlin-Buch (MDC), Berlin, Germany Leibniz Institute for Molecular Pharmacology (FMP), Berlin, Germany
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73
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Blant A, Czubryt MP. Promotion and inhibition of cardiac hypertrophy by A-kinase anchor proteins. Can J Physiol Pharmacol 2012; 90:1161-70. [DOI: 10.1139/y2012-032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Originally identified as mediators of cyclic adenosine monophosphate (cAMP) and protein kinase A signaling, A-kinase anchor proteins (AKAPs) are now recognized as a diverse family of molecular scaffolds capable of interacting with many other proteins. Members of the AKAP family within the heart can take on either pro- or anti-hypertrophic roles by interacting with a myriad of protein kinases and phosphatases in the process. AKAPs often form the core of large signaling complexes (or signalosomes) that allow multiple pathways to converge and functionally intertwine. Approximately 30% of AKAPs discovered to date are expressed in the heart, but the functions of many of these remain to be discovered. This review focuses on AKAPs that have been demonstrated to play roles in mediating cardiac hypertrophy.
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Affiliation(s)
- Alexandra Blant
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and University of Manitoba, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
| | - Michael P. Czubryt
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and University of Manitoba, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
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Abstract
This review discusses the potential place of soluble adenylyl cyclase (sAC) in the framework of signaling in the cardiovascular system. cAMP has been studied as a critical and pleiotropic second messenger in cardiomyocytes, endothelial cells, and smooth muscle vascular cells for many years. It is involved in the transduction of signaling by catecholamines, prostaglandins, adenosine, and glucagon, just to name a few. These hormones can act via cAMP by binding to a G protein-coupled receptor on the plasma membrane with subsequent activation of a heterotrimeric G protein and its downstream effector, transmembrane adenylyl cyclase. This has long been the canonical standard for cAMP production in a cell. However, the relatively recent discovery of a unique source of cAMP, sAC, creates the potential for a shift in this signaling paradigm. In fact, sAC has been shown to play a role in apoptosis in coronary endothelial cells and cardiomyocytes. Additionally, it links nutrient utilization with ATP production in the liver and brain, which suggests one of many potential roles for sAC in cardiac function. The possibility of producing cAMP from a source distal to the plasma membrane provides a critical new building block for reconstructing the cellular signaling infrastructure.
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Affiliation(s)
- Jonathan Chen
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10065, USA
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Abstract
Force-generating contractile cells of the myocardium must achieve and maintain their primary function as an efficient mechanical pump over the life span of the organism. Because only half of the cardiomyocytes can be replaced during the entire human life span, the maintenance strategy elicited by cardiac cells relies on uninterrupted renewal of their components, including proteins whose specialized functions constitute this complex and sophisticated contractile apparatus. Thus cardiac proteins are continuously synthesized and degraded to ensure proteome homeostasis, also termed "proteostasis." Once synthesized, proteins undergo additional folding, posttranslational modifications, and trafficking and/or become involved in protein-protein or protein-DNA interactions to exert their functions. This includes key transient interactions of cardiac proteins with molecular chaperones, which assist with quality control at multiple levels to prevent misfolding or to facilitate degradation. Importantly, cardiac proteome maintenance depends on the cellular environment and, in particular, the reduction-oxidation (REDOX) state, which is significantly different among cardiac organelles (e.g., mitochondria and endoplasmic reticulum). Taking into account the high metabolic activity for oxygen consumption and ATP production by mitochondria, it is a challenge for cardiac cells to maintain the REDOX state while preventing either excessive oxidative or reductive stress. A perturbed REDOX environment can affect protein handling and conformation (e.g., disulfide bonds), disrupt key structure-function relationships, and trigger a pathogenic cascade of protein aggregation, decreased cell survival, and increased organ dysfunction. This review covers current knowledge regarding the general domain of REDOX state and protein folding, specifically in cardiomyocytes under normal-healthy conditions and during disease states associated with morbidity and mortality in humans.
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Affiliation(s)
- Elisabeth S Christians
- Laboratory of Cardiac Disease, Redox Signaling and Cell Regeneration, Division of Cardiology, University of Utah School of Medicine, Salt Lake City, USA
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