51
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Kumari N, Gaur H, Bhargava A. Cardiac voltage gated calcium channels and their regulation by β-adrenergic signaling. Life Sci 2017; 194:139-149. [PMID: 29288765 DOI: 10.1016/j.lfs.2017.12.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/17/2017] [Accepted: 12/24/2017] [Indexed: 01/08/2023]
Abstract
Voltage-gated calcium channels (VGCCs) are the predominant source of calcium influx in the heart leading to calcium-induced calcium release and ultimately excitation-contraction coupling. In the heart, VGCCs are modulated by the β-adrenergic signaling. Signaling through β-adrenergic receptors (βARs) and modulation of VGCCs by β-adrenergic signaling in the heart are critical signaling and changes to these have been significantly implicated in heart failure. However, data related to calcium channel dysfunction in heart failure is divergent and contradictory ranging from reduced function to no change in the calcium current. Many recent studies have highlighted the importance of functional and spatial microdomains in the heart and that may be the key to answer several puzzling questions. In this review, we have briefly discussed the types of VGCCs found in heart tissues, their structure, and significance in the normal and pathological condition of the heart. More importantly, we have reviewed the modulation of VGCCs by βARs in normal and pathological conditions incorporating functional and structural aspects. There are different types of βARs, each having their own significance in the functioning of the heart. Finally, we emphasize the importance of location of proteins as it relates to their function and modulation by co-signaling molecules. Its implication on the studies of heart failure is speculated.
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Affiliation(s)
- Neema Kumari
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India
| | - Himanshu Gaur
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India
| | - Anamika Bhargava
- Ion Channel Biology Lab, Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana 502285, India.
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52
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Regulation of microdomain voltage-gated L-type calcium channels in cardiac health and disease. CURRENT OPINION IN PHYSIOLOGY 2017; 2:13-18. [PMID: 29963649 DOI: 10.1016/j.cophys.2017.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cav1.2 channels in the heart mediate excitation-contraction (E-C) coupling; tune cardiac excitability; and regulate gene expression. In ventricular myocytes, CaV1.2 channels are predominantly located in t-tubules where they are in proximity to ryanodine receptors to trigger cardiac E-C coupling. A subset of ventricular CaV1.2 channels existing on the surface sarcolemma, including in caveolae, have less well-defined functions. Cardiac CaV1.2 channels are famously up-regulated by protein kinase A as a component of the 'fight-or-flight' response. The molecular details of how this kinase regulates cardiac CaV1.2 channels are controversial and under intensive study. Here, we critically review recent work addressing the putative functions of microdomain cardiac CaV1.2 channels, and their regulation by distinct kinases in health and disease.
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53
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Cserne Szappanos H, Muralidharan P, Ingley E, Petereit J, Millar AH, Hool LC. Identification of a novel cAMP dependent protein kinase A phosphorylation site on the human cardiac calcium channel. Sci Rep 2017; 7:15118. [PMID: 29123182 PMCID: PMC5680263 DOI: 10.1038/s41598-017-15087-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 10/19/2017] [Indexed: 11/09/2022] Open
Abstract
The "Fight or Flight" response is elicited by extrinsic stress and is necessary in many species for survival. The response involves activation of the β-adrenergic signalling pathway. Surprisingly the mechanisms have remained unresolved. Calcium influx through the cardiac L-type Ca2+ channel (Cav1.2) is absolutely required. Here we identify the functionally relevant site for PKA phosphorylation on the human cardiac L-type Ca2+ channel pore forming α1 subunit using a novel approach. We used a cell free system where we could assess direct effects of PKA on human purified channel protein function reconstituted in proteoliposomes. In addition to assessing open probability of channel protein we used semi-quantitative fluorescent phosphoprotein detection and MS/MS mass spectrometry analysis to demonstrate the PKA specificity of the site. Robust increases in frequency of channel openings were recorded after phosphorylation of the long and short N terminal isoforms and the channel protein with C terminus truncated at aa1504. A protein kinase A anchoring protein (AKAP) was not required. We find the novel PKA phosphorylation site at Ser1458 is in close proximity to the Repeat IV S6 region and induces a conformational change in the channel protein that is necessary and sufficient for increased calcium influx through the channel.
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Affiliation(s)
| | - Padmapriya Muralidharan
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Evan Ingley
- Harry Perkins Institute of Medical Research and Centre for Medical Research, University of Western Australia, Nedlands, Western Australia, Australia.,School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - Jakob Petereit
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - A Harvey Millar
- ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, Western Australia, Australia
| | - Livia C Hool
- School of Human Sciences, University of Western Australia, Crawley, Western Australia, Australia. .,Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia.
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54
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Raifman TK, Kumar P, Haase H, Klussmann E, Dascal N, Weiss S. Protein kinase C enhances plasma membrane expression of cardiac L-type calcium channel, Ca V1.2. Channels (Austin) 2017; 11:604-615. [PMID: 28901828 DOI: 10.1080/19336950.2017.1369636] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
L-type-voltage-dependent Ca2+ channels (L-VDCCs; CaV1.2, α1C), crucial in cardiovascular physiology and pathology, are modulated via activation of G-protein-coupled receptors and subsequently protein kinase C (PKC). Despite extensive study, key aspects of the mechanisms leading to PKC-induced Ca2+ current increase are unresolved. A notable residue, Ser1928, located in the distal C-terminus (dCT) of α1C was shown to be phosphorylated by PKC. CaV1.2 undergoes posttranslational modifications yielding full-length and proteolytically cleaved CT-truncated forms. We have previously shown that, in Xenopus oocytes, activation of PKC enhances α1C macroscopic currents. This increase depended on the isoform of α1C expressed. Only isoforms containing the cardiac, long N-terminus (L-NT), were upregulated by PKC. Ser1928 was also crucial for the full effect of PKC. Here we report that, in Xenopus oocytes, following PKC activation the amount of α1C protein expressed in the plasma membrane (PM) increases within minutes. The increase in PM content is greater with full-length α1C than in dCT-truncated α1C, and requires Ser1928. The same was observed in HL-1 cells, a mouse atrium cell line natively expressing cardiac α1C, which undergoes the proteolytic cleavage of the dCT, thus providing a native setting for exploring the effects of PKC in cardiomyocytes. Interestingly, activation of PKC preferentially increased the PM levels of full-length, L-NT α1C. Our findings suggest that part of PKC regulation of CaV1.2 in the heart involves changes in channel's cellular fate. The mechanism of this PKC regulation appears to involve the C-terminus of α1C, possibly corroborating the previously proposed role of NT-CT interactions within α1C.
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Affiliation(s)
- Tal Keren Raifman
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel.,b Department of Physiotherapy , Zfat Academic College , Zfat , Israel
| | - Prabodh Kumar
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
| | - Hannelore Haase
- c Max Delbruck Center for Molecular Medicine (MDC) , Berlin , Germany
| | - Enno Klussmann
- c Max Delbruck Center for Molecular Medicine (MDC) , Berlin , Germany
| | - Nathan Dascal
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
| | - Sharon Weiss
- a Department of Physiology and Pharmacology , Sackler School of Medicine, Tel Aviv University , Tel Aviv , Israel
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55
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Poomvanicha M, Matthes J, Domes K, Patrucco E, Angermeier E, Laugwitz KL, Schneider T, Hofmann F. Beta-adrenergic regulation of the heart expressing the Ser1700A/Thr1704A mutated Cav1.2 channel. J Mol Cell Cardiol 2017; 111:10-16. [PMID: 28778765 DOI: 10.1016/j.yjmcc.2017.07.119] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/25/2017] [Accepted: 07/28/2017] [Indexed: 01/07/2023]
Abstract
Beta-adrenergic stimulation of the heart increases ICa. PKA dependent phosphorylation of several amino acids (among them Ser 1700 and Thr 1704 in the carboxy-terminus of the Cav1.2 α1c subunit) has been implicated as decisive for the β-adrenergic up-regulation of cardiac ICa. Mutation of Ser 1700 and Thr 1704 to alanine results in the Cav1.2PKA_P2-/- mice. Cav1.2PKA_P2-/- mice display reduced cardiac L-type current. Fractional shortening and ejection fraction in the intact animal and ICa in isolated cardiomyocytes (CM) are stimulated by isoproterenol. Cardiac specific expression of the mutated Cav1.2PKA_P2-/- gene reduces Cav1.2 α1c protein concentration, ICa, and the β-adrenergic stimulation of L-type ICa in CMs. Single channels were not detected on the CM surface of the cCav1.2PKA_P2-/- hearts. This outcome supports the notion that S1700/1704 is essential for expression of the Cav1.2 channel and that isoproterenol stimulates ICa in Cav1.2PKA_P2-/- CMs.
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Affiliation(s)
- Montatip Poomvanicha
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
| | - Jan Matthes
- Institut für Pharmakologie und Toxikologie, University Cologne, Germany
| | - Katrin Domes
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
| | - Enrico Patrucco
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
| | - Elisabeth Angermeier
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
| | - Karl-Ludwig Laugwitz
- I. Medizinische Klinik und Poliklinik (Kardiologie, Angiologie & Pneumologie), Klinikum rechts der Isar-Technische Universität München, Ismaninger Straße 22, 81675 München, Germany
| | - Toni Schneider
- Institut für Neurophysiologie, University Cologne, Germany
| | - Franz Hofmann
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany.
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56
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Owolabi BO, Musale V, Ojo OO, Moffett RC, McGahon MK, Curtis TM, Conlon JM, Flatt PR, Abdel-Wahab YH. Actions of PGLa-AM1 and its [A14K] and [A20K] analogues and their therapeutic potential as anti-diabetic agents. Biochimie 2017; 138:1-12. [DOI: 10.1016/j.biochi.2017.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 04/04/2017] [Indexed: 12/19/2022]
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57
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Barbati SA, Colussi C, Bacci L, Aiello A, Re A, Stigliano E, Isidori AM, Grassi C, Pontecorvi A, Farsetti A, Gaetano C, Nanni S. Transcription Factor CREM Mediates High Glucose Response in Cardiomyocytes and in a Male Mouse Model of Prolonged Hyperglycemia. Endocrinology 2017; 158:2391-2405. [PMID: 28368536 DOI: 10.1210/en.2016-1960] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/16/2017] [Indexed: 01/31/2023]
Abstract
This study aims at investigating the epigenetic landscape of cardiomyocytes exposed to elevated glucose levels. High glucose (30 mM) for 72 hours determined some epigenetic changes in mouse HL-1 and rat differentiated H9C2 cardiomyocytes including upregulation of class I and III histone deacetylase protein levels and activity, inhibition of histone acetylase p300 activity, increase in histone H3 lysine 27 trimethylation, and reduction in H3 lysine 9 acetylation. Gene expression analysis focused on cardiotoxicity revealed that high glucose induced markers associated with tissue damage, fibrosis, and cardiac remodeling such as Nexilin (NEXN), versican, cyclic adenosine 5'-monophosphate-responsive element modulator (CREM), and adrenoceptor α2A (ADRA2). Notably, the transcription factor CREM was found to be important in the regulation of cardiotoxicity-associated genes as assessed by specific small interfering RNA and chromatin immunoprecipitation experiments. In CD1 mice, made hyperglycemic by streptozotoicin (STZ) injection, cardiac structural alterations were evident at 6 months after STZ treatment and were associated with a significant increase of H3 lysine 27 trimethylation and reduction of H3 lysine 9 acetylation. Consistently, NEXN, CREM, and ADRA2 expression was significantly induced at the RNA and protein levels. Confocal microscopy analysis of NEXN localization showed this protein irregularly distributed along the sarcomeres in the heart of hyperglycemic mice. This evidence suggested a structural alteration of cardiac Z-disk with potential consequences on contractility. In conclusion, high glucose may alter the epigenetic landscape of cardiac cells. Sildenafil, restoring guanosine 3', 5'-cyclic monophosphate levels, counteracted the increase of CREM and NEXN, providing a protective effect in the presence of hyperglycemia.
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Affiliation(s)
- Saviana A Barbati
- Institute of Human Physiology, Università Cattolica di Roma, 00168 Rome, Italy
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
| | - Claudia Colussi
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
- Institute of Cell Biology and Neurobiology, National Research Council, 00143 Rome, Italy
| | - Lorenza Bacci
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
| | - Aurora Aiello
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
- Institute of Cell Biology and Neurobiology, National Research Council, 00143 Rome, Italy
| | - Agnese Re
- Institute of Cell Biology and Neurobiology, National Research Council, 00143 Rome, Italy
| | - Egidio Stigliano
- Department of Histopathology, Università Cattolica di Roma, 00168 Rome, Italy
| | - Andrea M Isidori
- Department of Experimental Medicine, "Sapienza" University, 00161 Rome, Italy
| | - Claudio Grassi
- Institute of Human Physiology, Università Cattolica di Roma, 00168 Rome, Italy
| | - Alfredo Pontecorvi
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
| | - Antonella Farsetti
- Institute of Cell Biology and Neurobiology, National Research Council, 00143 Rome, Italy
- Medicine Clinic III, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Carlo Gaetano
- Medicine Clinic III, Division of Cardiovascular Epigenetics, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Simona Nanni
- Institute of Medical Pathology, Università Cattolica di Roma, 00168 Rome, Italy
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58
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Liu X, Shen Y, Xie J, Bao H, Cao Q, Wan R, Xu X, Zhou H, Huang L, Xu Z, Zhu W, Hu J, Cheng X, Hong K. A mutation in the CACNA1C gene leads to early repolarization syndrome with incomplete penetrance: A Chinese family study. PLoS One 2017; 12:e0177532. [PMID: 28493952 PMCID: PMC5426766 DOI: 10.1371/journal.pone.0177532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 04/28/2017] [Indexed: 01/06/2023] Open
Abstract
Background Early repolarization syndrome (ERS) may be a near-Mendelian or an oligogenic disease; however, no direct evidence has been provided to support this theory. Methods and results We described a large Chinese family with nocturnal sudden cardiac death induced by ERS in most of the young male adults. One missense mutation (p.Q1916R) was found in the major subunit of the L-type calcium channel gene CACNA1C by the direct sequencing of candidate genes. A concomitant gain-of-function variant in the sodium channel gene SCN5A (p.R1193Q) was found to rescue the phenotype of the female CACNA1C-Q1916R mutation carriers, which led to the incomplete penetrance. The functional studies, via the exogenous expression approach, revealed that the CACNA1C-Q1916R mutation led to a decreasing L-type calcium current and the protein expression defect. The decreased calcium current produced by the mutant channel was improved by isoproterenol but exacerbated by testosterone. The effects of CACNA1C-Q1916R mutation and testosterone on cellular electrophysiology were further confirmed by the human ventricular action potential simulation. Conclusions Our results demonstrated that the loss-of-function CACNA1C-Q1916R mutation contributed to ERS-related sudden cardiac death, and the phenotypic incomplete penetrance was modified by the SCN5A-R1193Q variant and sex. These findings suggest that phenotypes of ERS are modified by multiple genetic factors, which supports the theory that ERS may be an oligogenic disease.
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Affiliation(s)
- Xin Liu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yang Shen
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Jinyan Xie
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Huihui Bao
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qing Cao
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Rong Wan
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
| | - Xiaoming Xu
- Department of Forensic Medicine, Medical College of Nanchang University, Nanchang, China
| | - Hui Zhou
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Lin Huang
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Zhenyan Xu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Wengen Zhu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jinzhu Hu
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Xiaoshu Cheng
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Kui Hong
- Department of Cardiovascular medicine, the Second Affiliated Hospital of Nanchang University, Nanchang, China
- Jiangxi Province Key Laboratory of Molecular Medicine, Nanchang, China
- * E-mail:
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59
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Melville Z, Hernández-Ochoa EO, Pratt SJP, Liu Y, Pierce AD, Wilder PT, Adipietro KA, Breysse DH, Varney KM, Schneider MF, Weber DJ. The Activation of Protein Kinase A by the Calcium-Binding Protein S100A1 Is Independent of Cyclic AMP. Biochemistry 2017; 56:2328-2337. [PMID: 28409622 PMCID: PMC5415871 DOI: 10.1021/acs.biochem.7b00117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Biochemical
and structural studies demonstrate that S100A1 is involved
in a Ca2+-dependent interaction with the type 2α
and type 2β regulatory subunits of protein kinase A (PKA) (RIIα
and RIIβ) to activate holo-PKA. The interaction was specific
for S100A1 because other calcium-binding proteins (i.e., S100B and
calmodulin) had no effect. Likewise, a role for S100A1
in PKA-dependent signaling was established because the PKA-dependent
subcellular redistribution of HDAC4 was abolished in cells derived
from S100A1 knockout mice. Thus, the Ca2+-dependent interaction
between S100A1 and the type 2 regulatory subunits represents a novel
mechanism that provides a link between Ca2+ and PKA signaling,
which is important for the regulation of gene expression in skeletal
muscle via HDAC4 cytosolic–nuclear trafficking.
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Affiliation(s)
- Zephan Melville
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Stephen J P Pratt
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Yewei Liu
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Adam D Pierce
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Paul T Wilder
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Kaylin A Adipietro
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Daniel H Breysse
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Kristen M Varney
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
| | - David J Weber
- Department of Biochemistry and Molecular Biology and ‡Center for Biomolecular Therapeutics, University of Maryland School of Medicine , 108 North Greene Street, Baltimore, Maryland 21201, United States
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60
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Monteiro LM, Vasques-Nóvoa F, Ferreira L, Pinto-do-Ó P, Nascimento DS. Restoring heart function and electrical integrity: closing the circuit. NPJ Regen Med 2017; 2:9. [PMID: 29302345 PMCID: PMC5665620 DOI: 10.1038/s41536-017-0015-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/19/2017] [Accepted: 03/06/2017] [Indexed: 12/30/2022] Open
Abstract
Cardiovascular diseases are the main cause of death in the world and are often associated with the occurrence of arrhythmias due to disruption of myocardial electrical integrity. Pathologies involving dysfunction of the specialized cardiac excitatory/conductive tissue are also common and constitute an added source of morbidity and mortality since current standard therapies withstand a great number of limitations. As electrical integrity is essential for a well-functioning heart, innovative strategies have been bioengineered to improve heart conduction and/or promote myocardial repair, based on: (1) gene and/or cell delivery; or (2) conductive biomaterials as tools for cardiac tissue engineering. Herein we aim to review the state-of-art in the area, while briefly describing the biological principles underlying the heart electrical/conduction system and how this system can be disrupted in heart disease. Suggestions regarding targets for future studies are also presented.
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Affiliation(s)
- Luís Miguel Monteiro
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
- CNC—Center for Neuroscience and Cell Biology, Universidade de Coimbra, Coimbra, Portugal
| | - Francisco Vasques-Nóvoa
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
- Departamento de Fisiologia e Cirurgia Cardiotorácica, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Lino Ferreira
- CNC—Center for Neuroscience and Cell Biology, Universidade de Coimbra, Coimbra, Portugal
| | - Perpétua Pinto-do-Ó
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
- ICBAS—Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Diana Santos Nascimento
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
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61
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Lyu L, Gao Q, Xu J, Minobe E, Zhu T, Kameyama M. A new interaction between proximal and distal C-terminus of Cav1.2 channels. J Pharmacol Sci 2017; 133:240-246. [DOI: 10.1016/j.jphs.2017.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/16/2017] [Accepted: 03/03/2017] [Indexed: 11/16/2022] Open
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62
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Oz S, Pankonien I, Belkacemi A, Flockerzi V, Klussmann E, Haase H, Dascal N. Protein kinase A regulates C-terminally truncated Ca V 1.2 in Xenopus oocytes: roles of N- and C-termini of the α 1C subunit. J Physiol 2017; 595:3181-3202. [PMID: 28194788 DOI: 10.1113/jp274015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 02/08/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS β-Adrenergic stimulation enhances Ca2+ entry via L-type CaV 1.2 channels, causing stronger contraction of cardiac muscle cells. The signalling pathway involves activation of protein kinase A (PKA), but the molecular details of PKA regulation of CaV 1.2 remain controversial despite extensive research. We show that PKA regulation of CaV 1.2 can be reconstituted in Xenopus oocytes when the distal C-terminus (dCT) of the main subunit, α1C , is truncated. The PKA upregulation of CaV 1.2 does not require key factors previously implicated in this mechanism: the clipped dCT, the A kinase-anchoring protein 15 (AKAP15), the phosphorylation sites S1700, T1704 and S1928, or the β subunit of CaV 1.2. The gating element within the initial segment of the N-terminus of the cardiac isoform of α1C is essential for the PKA effect. We propose that the regulation described here is one of two or several mechanisms that jointly mediate the PKA regulation of CaV 1.2 in the heart. ABSTRACT β-Adrenergic stimulation enhances Ca2+ currents via L-type, voltage-gated CaV 1.2 channels, strengthening cardiac contraction. The signalling via β-adrenergic receptors (β-ARs) involves elevation of cyclic AMP (cAMP) levels and activation of protein kinase A (PKA). However, how PKA affects the channel remains controversial. Recent studies in heterologous systems and genetically engineered mice stress the importance of the post-translational proteolytic truncation of the distal C-terminus (dCT) of the main (α1C ) subunit. Here, we successfully reconstituted the cAMP/PKA regulation of the dCT-truncated CaV 1.2 in Xenopus oocytes, which previously failed with the non-truncated α1C . cAMP and the purified catalytic subunit of PKA, PKA-CS, injected into intact oocytes, enhanced CaV 1.2 currents by ∼40% (rabbit α1C ) to ∼130% (mouse α1C ). PKA blockers were used to confirm specificity and the need for dissociation of the PKA holoenzyme. The regulation persisted in the absence of the clipped dCT (as a separate protein), the A kinase-anchoring protein AKAP15, and the phosphorylation sites S1700 and T1704, previously proposed as essential for the PKA effect. The CaV β2b subunit was not involved, as suggested by extensive mutagenesis. Using deletion/chimeric mutagenesis, we have identified the initial segment of the cardiac long-N-terminal isoform of α1C as a previously unrecognized essential element involved in PKA regulation. We propose that the observed regulation, that exclusively involves the α1C subunit, is one of several mechanisms underlying the overall PKA action on CaV 1.2 in the heart. We hypothesize that PKA is acting on CaV 1.2, in part, by affecting a structural 'scaffold' comprising the interacting cytosolic N- and C-termini of α1C .
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Affiliation(s)
- Shimrit Oz
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ines Pankonien
- Max Delbrück Center for Molecular Medicine (MDC), D-13092, and the German Centre for Cardiovascular Research (DZHK) partner site, Berlin, Germany
| | - Anouar Belkacemi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421, Homburg, Germany
| | - Veit Flockerzi
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421, Homburg, Germany
| | - Enno Klussmann
- Max Delbrück Center for Molecular Medicine (MDC), D-13092, and the German Centre for Cardiovascular Research (DZHK) partner site, Berlin, Germany
| | - Hannelore Haase
- Max Delbrück Center for Molecular Medicine (MDC), D-13092, and the German Centre for Cardiovascular Research (DZHK) partner site, Berlin, Germany
| | - Nathan Dascal
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 6997801, Israel
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Minobe E, Mori MX, Kameyama M. Calmodulin and ATP support activity of the Cav1.2 channel through dynamic interactions with the channel. J Physiol 2017; 595:2465-2477. [PMID: 28130847 PMCID: PMC5390892 DOI: 10.1113/jp273736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/06/2017] [Indexed: 11/08/2022] Open
Abstract
Key points Cav1.2 channels maintain activity through interactions with calmodulin (CaM). In this study, activities of the Cav1.2 channel (α1C) and of mutant‐derivatives, C‐terminal deleted (α1CΔ) and α1CΔ linked with CaM (α1CΔCaM), were compared in the inside‐out mode. α1CΔ with CaM, but not without CaM, and α1CΔCaM were active, suggesting that CaM induced channel activity through a dynamic interaction with the channel, even without the distal C‐tail. ATP induced α1C activity with CaM and enhanced activity of the mutant channels. Okadaic acid mimicked the effect of ATP on the wildtype but not mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels through their dynamic interactions. ATP effects involve mechanisms both related and unrelated to channel phosphorylation. CaM‐linked channels are useful tools for investigating Cav1.2 channels in the inside‐out mode; the fast run‐down is prevented by only ATP and the slow run‐down is nearly absent.
Abstract Calmodulin (CaM) plays a critical role in regulation of Cav1.2 Ca2+ channels. CaM binds to the channel directly, maintaining channel activity and regulating it in a Ca2+‐dependent manner. To explore the molecular mechanisms involved, we compared the activity of the wildtype channel (α1C) and mutant derivatives, C‐terminal deleted (α1C∆) and α1C∆ linked to CaM (α1C∆CaM). These were co‐expressed with β2a and α2δ subunits in HEK293 cells. In the inside‐out mode, α1C and α1C∆ showed minimal open‐probabilities in a basic internal solution (run‐down), whereas α1C∆ with CaM and α1C∆CaM maintained detectable channel activity, confirming that CaM was necessary, but not sufficient, for channel activity. Previously, we reported that ATP was required to maintain channel activity of α1C. Unlike α1C, the mutant channels did not require ATP for activation in the early phase (3–5 min). However, α1C∆ with CaM + ATP and α1C∆CaM with ATP maintained activity, even in the late phase (after 7–9 min). These results suggested that CaM and ATP interacted dynamically with the proximal C‐terminal tail of the channel and, thereby, produced channel activity. In addition, okadaic acid, a protein phosphatase inhibitor, could substitute for the effects of ATP on α1C but not on the mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels, further indicating that ATP has dual effects. One maintains phosphorylation of the channel and the other becomes apparent when the distal carboxyl‐terminal tail is removed. Cav1.2 channels maintain activity through interactions with calmodulin (CaM). In this study, activities of the Cav1.2 channel (α1C) and of mutant‐derivatives, C‐terminal deleted (α1CΔ) and α1CΔ linked with CaM (α1CΔCaM), were compared in the inside‐out mode. α1CΔ with CaM, but not without CaM, and α1CΔCaM were active, suggesting that CaM induced channel activity through a dynamic interaction with the channel, even without the distal C‐tail. ATP induced α1C activity with CaM and enhanced activity of the mutant channels. Okadaic acid mimicked the effect of ATP on the wildtype but not mutant channels. These results supported the hypothesis that CaM and ATP maintain activity of Cav1.2 channels through their dynamic interactions. ATP effects involve mechanisms both related and unrelated to channel phosphorylation. CaM‐linked channels are useful tools for investigating Cav1.2 channels in the inside‐out mode; the fast run‐down is prevented by only ATP and the slow run‐down is nearly absent.
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Affiliation(s)
- Etsuko Minobe
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Masayuki X Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
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Hissa B, Oakes PW, Pontes B, Ramírez-San Juan G, Gardel ML. Cholesterol depletion impairs contractile machinery in neonatal rat cardiomyocytes. Sci Rep 2017; 7:43764. [PMID: 28256617 PMCID: PMC5335656 DOI: 10.1038/srep43764] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 01/27/2017] [Indexed: 02/06/2023] Open
Abstract
Cholesterol regulates numerous cellular processes. Depleting its synthesis in skeletal myofibers induces vacuolization and contraction impairment. However, little is known about how cholesterol reduction affects cardiomyocyte behavior. Here, we deplete cholesterol by incubating neonatal cardiomyocytes with methyl-beta-cyclodextrin. Traction force microscopy shows that lowering cholesterol increases the rate of cell contraction and generates defects in cell relaxation. Cholesterol depletion also increases membrane tension, Ca2+ spikes frequency and intracellular Ca2+ concentration. These changes can be correlated with modifications in caveolin-3 and L-Type Ca2+ channel distributions across the sarcolemma. Channel regulation is also compromised since cAMP-dependent PKA activity is enhanced, increasing the probability of L-Type Ca2+ channel opening events. Immunofluorescence reveals that cholesterol depletion abrogates sarcomeric organization, changing spacing and alignment of α-actinin bands due to increase in proteolytic activity of calpain. We propose a mechanism in which cholesterol depletion triggers a signaling cascade, culminating with contraction impairment and myofibril disruption in cardiomyocytes.
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Affiliation(s)
- Barbara Hissa
- James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States
| | - Patrick W. Oakes
- James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States
| | - Bruno Pontes
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Guillermina Ramírez-San Juan
- James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States
| | - Margaret L. Gardel
- James Franck Institute, Institute for Biophysical Dynamics and Physics Department, University of Chicago, Chicago, IL, United States
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Tonegawa K, Otsuka W, Kumagai S, Matsunami S, Hayamizu N, Tanaka S, Moriwaki K, Obana M, Maeda M, Asahi M, Kiyonari H, Fujio Y, Nakayama H. Caveolae-specific activation loop between CaMKII and L-type Ca 2+ channel aggravates cardiac hypertrophy in α 1-adrenergic stimulation. Am J Physiol Heart Circ Physiol 2016; 312:H501-H514. [PMID: 28039202 DOI: 10.1152/ajpheart.00601.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/01/2016] [Accepted: 11/15/2016] [Indexed: 11/22/2022]
Abstract
Activation of CaMKII induces a myriad of biological processes and plays dominant roles in cardiac hypertrophy. Caveolar microdomain contains many calcium/calmodulin-dependent kinase II (CaMKII) targets, including L-type Ca2+ channel (LTCC) complex, and serves as a signaling platform. The location of CaMKII activation is thought to be critical; however, the roles of CaMKII in caveolae are still elusive due to lack of methodology for the assessment of caveolae-specific activation. Our aim was to develop a novel tool for the specific analysis of CaMKII activation in caveolae and to determine the functional role of caveolar CaMKII in cardiac hypertrophy. To assess the caveolae-specific activation of CaMKII, we generated a fusion protein composed of phospholamban and caveolin-3 (cPLN-Cav3) and GFP fusion protein with caveolin-binding domain fused to CaMKII inhibitory peptide (CBD-GFP-AIP), which inhibits CaMKII activation specifically in caveolae. Caveolae-specific activation of CaMKII was detected using phosphospecific antibody for PLN (Thr17). Furthermore, adenoviral overexpression of LTCC β2a-subunit (β2a) in NRCMs showed its constitutive phosphorylation by CaMKII, which induces hypertrophy, and that both phosphorylation and hypertrophy are abolished by CBD-GFP-AIP expression, indicating that β2a phosphorylation occurs specifically in caveolae. Finally, β2a phosphorylation was observed after phenylephrine stimulation in β2a-overexpressing mice, and attenuation of cardiac hypertrophy after chronic phenylephrine stimulation was observed in nonphosphorylated mutant of β2a-overexpressing mice. We developed novel tools for the evaluation and inhibition of caveolae-specific activation of CaMKII. We demonstrated that phosphorylated β2a dominantly localizes to caveolae and induces cardiac hypertrophy after α1-adrenergic stimulation in mice.NEW & NOTEWORTHY While signaling in caveolae is thought to be important in cardiac hypertrophy, direct evidence is missing due to lack of tools to assess caveolae-specific signaling. This is the first study to demonstrate caveolae-specific activation of CaMKII signaling in cardiac hypertrophy induced by α1-adrenergic stimulation using an originally developed tool.
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Affiliation(s)
- Kota Tonegawa
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Wataru Otsuka
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Shohei Kumagai
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Sachi Matsunami
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Nao Hayamizu
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Shota Tanaka
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Kazumasa Moriwaki
- Faculty of Medicine, Department of Pharmacology, Osaka Medical College, Takatsuki, Osaka, Japan; and
| | - Masanori Obana
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Makiko Maeda
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Michio Asahi
- Faculty of Medicine, Department of Pharmacology, Osaka Medical College, Takatsuki, Osaka, Japan; and
| | - Hiroshi Kiyonari
- Animal Resource Development Unit and Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan
| | - Yasushi Fujio
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan
| | - Hiroyuki Nakayama
- Laboratory of Clinical Science and Biomedicine, Graduate School of Pharmacological Sciences, Osaka University, Suita, Osaka, Japan;
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Loss of β-adrenergic-stimulated phosphorylation of CaV1.2 channels on Ser1700 leads to heart failure. Proc Natl Acad Sci U S A 2016; 113:E7976-E7985. [PMID: 27864509 DOI: 10.1073/pnas.1617116113] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
L-type Ca2+ currents conducted by voltage-gated calcium channel 1.2 (CaV1.2) initiate excitation-contraction coupling in the heart, and altered expression of CaV1.2 causes heart failure in mice. Here we show unexpectedly that reducing β-adrenergic regulation of CaV1.2 channels by mutation of a single PKA site, Ser1700, in the proximal C-terminal domain causes reduced contractile function, cardiac hypertrophy, and heart failure without changes in expression, localization, or function of the CaV1.2 protein in the mutant mice (SA mice). These deficits were aggravated with aging. Dual mutation of Ser1700 and a nearby casein-kinase II site (Thr1704) caused accelerated hypertrophy, heart failure, and death in mice with these mutations (STAA mice). Cardiac hypertrophy was increased by voluntary exercise and by persistent β-adrenergic stimulation. PKA expression was increased, and PKA sites Ser2808 in ryanodine receptor type-2, Ser16 in phospholamban, and Ser23/24 in troponin-I were hyperphosphorylated in SA mice, whereas phosphorylation of substrates for calcium/calmodulin-dependent protein kinase II was unchanged. The Ca2+ pool in the sarcoplasmic reticulum was increased, the activity of calcineurin was elevated, and calcineurin inhibitors improved contractility and ameliorated cardiac hypertrophy. Cardio-specific expression of the SA mutation also caused reduced contractility and hypertrophy. These results suggest engagement of compensatory mechanisms, which initially may enhance the contractility of individual myocytes but eventually contribute to an increased sensitivity to cardiovascular stress and to heart failure in vivo. Our results demonstrate that normal regulation of CaV1.2 channels by phosphorylation of Ser1700 in cardiomyocytes is required for cardiovascular homeostasis and normal physiological regulation in vivo.
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67
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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68
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Yang H, Yang L. Targeting cAMP/PKA pathway for glycemic control and type 2 diabetes therapy. J Mol Endocrinol 2016; 57:R93-R108. [PMID: 27194812 DOI: 10.1530/jme-15-0316] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/18/2016] [Indexed: 12/11/2022]
Abstract
In mammals, cyclic adenosine monophosphate (cAMP) is an intracellular second messenger that is usually elicited by binding of hormones and neurotransmitters to G protein-coupled receptors (GPCRs). cAMP exerts many of its physiological effects by activating cAMP-dependent protein kinase (PKA), which in turn phosphorylates and regulates the functions of downstream protein targets including ion channels, enzymes, and transcription factors. cAMP/PKA signaling pathway regulates glucose homeostasis at multiple levels including insulin and glucagon secretion, glucose uptake, glycogen synthesis and breakdown, gluconeogenesis, and neural control of glucose homeostasis. This review summarizes recent genetic and pharmacological studies concerning the regulation of glucose homeostasis by cAMP/PKA in pancreas, liver, skeletal muscle, adipose tissues, and brain. We also discuss the strategies for targeting cAMP/PKA pathway for research and potential therapeutic treatment of type 2 diabetes mellitus (T2D).
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Affiliation(s)
- Haihua Yang
- Division of EndocrinologyZhengzhou Children's Hospital, Zhengzhou, Henan, China
| | - Linghai Yang
- Department of PharmacologyUniversity of Washington, Seattle, Washington, USA
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69
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Sang L, Dick IE, Yue DT. Protein kinase A modulation of CaV1.4 calcium channels. Nat Commun 2016; 7:12239. [PMID: 27456671 PMCID: PMC4963476 DOI: 10.1038/ncomms12239] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 06/07/2016] [Indexed: 11/19/2022] Open
Abstract
The regulation of L-type Ca2+ channels by protein kinase A (PKA) represents a crucial element within cardiac, skeletal muscle and neurological systems. Although much work has been done to understand this regulation in cardiac CaV1.2 Ca2+ channels, relatively little is known about the closely related CaV1.4 L-type Ca2+ channels, which feature prominently in the visual system. Here we find that CaV1.4 channels are indeed modulated by PKA phosphorylation within the inhibitor of Ca2+-dependent inactivation (ICDI) motif. Phosphorylation of this region promotes the occupancy of calmodulin on the channel, thus increasing channel open probability (PO) and Ca2+-dependent inactivation. Although this interaction seems specific to CaV1.4 channels, introduction of ICDI1.4 to CaV1.3 or CaV1.2 channels endows these channels with a form of PKA modulation, previously unobserved in heterologous systems. Thus, this mechanism may not only play an important role in the visual system but may be generalizable across the L-type channel family. Phosphorylation of L-type calcium CaV channels by protein kinase A is essential for several physiological events. Here, the authors show how this kinase regulates CaV1.4 activity, suggesting a general regulatory mechanism for all L-type calcium channels.
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Affiliation(s)
- Lingjie Sang
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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70
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Protein partners of the calcium channel β subunit highlight new cellular functions. Biochem J 2016; 473:1831-44. [DOI: 10.1042/bcj20160125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/15/2016] [Indexed: 12/21/2022]
Abstract
Calcium plays a key role in cell signalling by its intervention in a wide range of physiological processes. Its entry into cells occurs mainly via voltage-gated calcium channels (VGCC), which are found not only in the plasma membrane of excitable cells but also in cells insensitive to electrical signals. VGCC are composed of different subunits, α1, β, α2δ and γ, among which the cytosolic β subunit (Cavβ) controls the trafficking of the channel to the plasma membrane, its regulation and its gating properties. For many years, these were the main functions associated with Cavβ. However, a growing number of proteins have been found to interact with Cavβ, emphasizing the multifunctional role of this versatile protein. Interestingly, some of the newly assigned functions of Cavβ are independent of its role in the regulation of VGCC, and thus further increase its functional roles. Based on the identity of Cavβ protein partners, this review emphasizes the diverse cellular functions of Cavβ and summarizes both past findings as well as recent progress in the understanding of VGCC.
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71
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Grinshpon M, Bondarenko VE. Simulation of the effects of moderate stimulation/inhibition of the β1-adrenergic signaling system and its components in mouse ventricular myocytes. Am J Physiol Cell Physiol 2016; 310:C844-56. [DOI: 10.1152/ajpcell.00002.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/02/2016] [Indexed: 01/08/2023]
Abstract
The β1-adrenergic signaling system is one of the most important protein signaling systems in cardiac cells. It regulates cardiac action potential duration, intracellular Ca2+concentration ([Ca2+]i) transients, and contraction force. In this paper, a comprehensive experimentally based mathematical model of the β1-adrenergic signaling system for mouse ventricular myocytes is explored to simulate the effects of moderate stimulations of β1-adrenergic receptors (β1-ARs) on the action potential, Ca2+and Na+dynamics, as well as the effects of inhibition of protein kinase A (PKA) and phosphodiesterase of type 4 (PDE4). Simulation results show that the action potential prolongations reach saturating values at relatively small concentrations of isoproterenol (∼0.01 μM), while the [Ca2+]itransient amplitude saturates at significantly larger concentrations (∼0.1–1.0 μM). The differences in the response of Ca2+and Na+fluxes to moderate stimulation of β1-ARs are also observed. Sensitivity analysis of the mathematical model is performed and the model limitations are discussed. The investigated model reproduces most of the experimentally observed effects of moderate stimulation of β1-ARs, PKA, and PDE4 inhibition on the L-type Ca2+current, [Ca2+]itransients, and the sarcoplasmic reticulum Ca2+load and makes testable predictions for the action potential duration and [Ca2+]itransients as functions of isoproterenol concentration.
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Affiliation(s)
- Mark Grinshpon
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia; and
| | - Vladimir E. Bondarenko
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia; and
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
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K(ATP) channel gain-of-function leads to increased myocardial L-type Ca(2+) current and contractility in Cantu syndrome. Proc Natl Acad Sci U S A 2016; 113:6773-8. [PMID: 27247394 DOI: 10.1073/pnas.1606465113] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Cantu syndrome (CS) is caused by gain-of-function (GOF) mutations in genes encoding pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) KATP channel subunits. We show that patients with CS, as well as mice with constitutive (cGOF) or tamoxifen-induced (icGOF) cardiac-specific Kir6.1 GOF subunit expression, have enlarged hearts, with increased ejection fraction and increased contractility. Whole-cell voltage-clamp recordings from cGOF or icGOF ventricular myocytes (VM) show increased basal L-type Ca(2+) current (LTCC), comparable to that seen in WT VM treated with isoproterenol. Mice with vascular-specific expression (vGOF) show left ventricular dilation as well as less-markedly increased LTCC. Increased LTCC in KATP GOF models is paralleled by changes in phosphorylation of the pore-forming α1 subunit of the cardiac voltage-gated calcium channel Cav1.2 at Ser1928, suggesting enhanced protein kinase activity as a potential link between increased KATP current and CS cardiac pathophysiology.
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73
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Maturing human pluripotent stem cell-derived cardiomyocytes in human engineered cardiac tissues. Adv Drug Deliv Rev 2016; 96:110-34. [PMID: 25956564 DOI: 10.1016/j.addr.2015.04.019] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/24/2015] [Accepted: 04/25/2015] [Indexed: 12/19/2022]
Abstract
Engineering functional human cardiac tissue that mimics the native adult morphological and functional phenotype has been a long held objective. In the last 5 years, the field of cardiac tissue engineering has transitioned from cardiac tissues derived from various animal species to the production of the first generation of human engineered cardiac tissues (hECTs), due to recent advances in human stem cell biology. Despite this progress, the hECTs generated to date remain immature relative to the native adult myocardium. In this review, we focus on the maturation challenge in the context of hECTs, the present state of the art, and future perspectives in terms of regenerative medicine, drug discovery, preclinical safety testing and pathophysiological studies.
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Xu J, Yu L, Minobe E, Lu L, Lei M, Kameyama M. PKA and phosphatases attached to the Ca(V)1.2 channel regulate channel activity in cell-free patches. Am J Physiol Cell Physiol 2015; 310:C136-41. [PMID: 26561637 DOI: 10.1152/ajpcell.00157.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 11/02/2015] [Indexed: 11/22/2022]
Abstract
Calmodulin (CaM) + ATP can reprime voltage-gated L-type Ca(2+) channels (Ca(V)1.2) in inside-out patches for activation, but this effect decreases time dependently. This suggests that the Ca(V)1.2 channel activity is regulated by additional cytoplasmic factors. To test this hypothesis, we examined the role of cAMP-dependent protein kinase A (PKA) and protein phosphatases in the regulation of Ca(V)1.2 channel activity in the inside-out mode in guinea pig ventricular myocytes. Ca(V)1.2 channel activity quickly disappeared after the patch was excised from the cell and recovered to only 9% of that in the cell-attached mode on application of CaM + ATP at 10 min after the inside out. However, immediate exposure of the excised patch to the catalytic subunit of PKA + ATP or the nonspecific phosphatase inhibitor okadaic acid significantly increased the Ca(V)1.2 channel activity recovery by CaM + ATP (114 and 96%, respectively) at 10 min. Interestingly, incubation of the excised patches with cAMP + ATP also increased CaM/ATP-induced Ca(V)1.2 channel activity recovery (108%), and this effect was blocked by the nonspecific protein kinase inhibitor K252a. The channel activity in the inside-out mode was not maintained by either catalytic subunit of PKA or cAMP + ATP in the absence of CaM, but was stably maintained in the presence of CaM for more than 40 min. These results suggest that PKA and phosphatase(s) attached on or near the Ca(V)1.2 channel regulate the basal channel activity, presumably through modulation of the dynamic CaM interaction with the channel.
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Affiliation(s)
- Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Lifeng Yu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China; Department of Ethnopharmacology, School of Pharmacy, China Medical University, Shenyang, China; and
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Liting Lu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Laboratory of Environmental Biology, Northeastern University, Shenyang, China
| | - Ming Lei
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan;
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75
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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: 55] [Impact Index Per Article: 6.1] [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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76
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Odnoshivkina UG, Sytchev VI, Nurullin LF, Giniatullin AR, Zefirov AL, Petrov AM. β2-adrenoceptor agonist-evoked reactive oxygen species generation in mouse atria: implication in delayed inotropic effect. Eur J Pharmacol 2015; 765:140-53. [PMID: 26297975 DOI: 10.1016/j.ejphar.2015.08.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/05/2015] [Accepted: 08/17/2015] [Indexed: 12/20/2022]
Abstract
Fenoterol, a β2-adrenoceptor agonist, has anti-apoptotic action in cardiomyocytes and induces a specific pattern of downstream signaling. We have previously reported that exposure to fenoterol (5 μM) results in a delayed positive inotropic effect which is related to changes in both Ca2+ transient and NO. Here, the changes in reactive oxygen species (ROS) production in response to the fenoterol administration and the involvement of ROS in effect of this agonist on contractility were investigated in mouse isolated atria. Stimulation of β2-adrenoceptor increases a level of extracellular ROS, while intracellular ROS level rises only after removal of fenoterol from the bath. NADPH-oxidase inhibitor (apocynin) prevents the increase in ROS production and the Nox2 isoform is immunofluorescently colocalized with β2-adrenoceptor at the atrial myocytes. Treatments with antioxidants (N-acetyl-L-cysteine, NADPH inhibitors, exogenous catalases) significantly inhibit the fenoterol induced increase in the contraction amplitude, probably by attenuating Ca2+ transient and up-regulating NO production. ROS generated in a β2-adrenoceptor-dependent manner can potentiate the activity of some Ca2+ channels. Indeed, inhibition of ryanodine receptors, TRPV-or L-type Ca2+- channels shows a similar efficacy in reduction of positive inotropic effect of both fenoterol and H2O2. In addition, detection of mitochondrial ROS indicates that fenoterol triggers a slow increase in ROS which is prevented by rotenone, but rotenone has no impact on the inotropic effect of fenoterol. We suggest that stimulation of β2-adrenoceptor with fenoterol causes the activation of NADPH-oxidase and after the agonist removal extracellularly generated ROS penetrates into the cell, increasing the atrial contractions probably via Ca2+ channels.
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Affiliation(s)
- Ulia G Odnoshivkina
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Vaycheslav I Sytchev
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Leniz F Nurullin
- Kazan Institute of Biochemistry and Biophysics, Kazan Scientific Center of Russian Academy of Sciences, Laboratory of Biophysics of Synaptic Processes, Lobatchevsky str. 2/31, P.O. 30, Kazan 420111, Russia
| | - Arthur R Giniatullin
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Andrei L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia
| | - Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Butlerova st., 49, Kazan 420012, Russia.
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77
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Zhang XQ, Wang J, Song J, Rabinowitz J, Chen X, Houser SR, Peterson BZ, Tucker AL, Feldman AM, Cheung JY. Regulation of L-type calcium channel by phospholemman in cardiac myocytes. J Mol Cell Cardiol 2015; 84:104-11. [PMID: 25918050 PMCID: PMC4468006 DOI: 10.1016/j.yjmcc.2015.04.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 03/24/2015] [Accepted: 04/21/2015] [Indexed: 11/26/2022]
Abstract
We evaluated whether phospholemman (PLM) regulates L-type Ca(2+) current (ICa) in mouse ventricular myocytes. Expression of α1-subunit of L-type Ca(2+) channels between wild-type (WT) and PLM knockout (KO) hearts was similar. Compared to WT myocytes, peak ICa (at -10 mV) from KO myocytes was ~41% larger, the inactivation time constant (τ(inact)) of ICa was ~39% longer, but deactivation time constant (τ(deact)) was similar. In the presence of isoproterenol (1 μM), peak ICa was ~48% larger and τ(inact) was ~144% higher in KO myocytes. With Ba(2+) as the permeant ion, PLM enhanced voltage-dependent inactivation but had no effect on τ(deact). To dissect the molecular determinants by which PLM regulated ICa, we expressed PLM mutants by adenovirus-mediated gene transfer in cultured KO myocytes. After 24h in culture, KO myocytes expressing green fluorescent protein (GFP) had significantly larger peak ICa and longer τ(inact) than KO myocytes expressing WT PLM; thereby independently confirming the observations in freshly isolated myocytes. Compared to KO myocytes expressing GFP, KO myocytes expressing the cytoplasmic domain truncation mutant (TM43), the non-phosphorylatable S68A mutant, the phosphomimetic S68E mutant, and the signature PFXYD to alanine (ALL5) mutant all resulted in lower peak ICa. Expressing PLM mutants did not alter expression of α1-subunit of L-type Ca(2+) channels in cultured KO myocytes. Our results suggested that both the extracellular PFXYD motif and the transmembrane domain of PLM but not the cytoplasmic tail were necessary for regulation of peak ICa amplitude. We conclude that PLM limits Ca(2+) influx in cardiac myocytes by reducing maximal ICa and accelerating voltage-dependent inactivation.
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Affiliation(s)
- Xue-Qian Zhang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA, USA
| | - JuFang Wang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA, USA
| | - Jianliang Song
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA, USA
| | - Joseph Rabinowitz
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA, USA
| | - Xiongwen Chen
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Steven R Houser
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Blaise Z Peterson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Amy L Tucker
- Cardiovascular Division, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, VA, USA
| | - Arthur M Feldman
- Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA, USA
| | - Joseph Y Cheung
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, PA, USA.
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78
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Adachi-Akahane S. [Regulation of L-type Ca(2+) channels via cross-talk of Ca(2+) signaling in cardiac myocytes]. Nihon Yakurigaku Zasshi 2014; 144:211-216. [PMID: 25381889 DOI: 10.1254/fpj.144.211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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79
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Zheng X, Zu L, Becker L, Cai ZP. Ischemic preconditioning inhibits mitochondrial permeability transition pore opening through the PTEN/PDE4 signaling pathway. Cardiology 2014; 129:163-73. [PMID: 25301476 DOI: 10.1159/000363646] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 05/14/2014] [Indexed: 01/13/2023]
Abstract
OBJECTIVES Ischemic preconditioning (IPC) induces cardioprotection against ischemia-reperfusion (IR) injury by inhibiting the mitochondrial permeability transition pore (mPTP). Here, we tested the hypothesis that IPC-induced cardioprotection is mediated by the phosphatase PTEN and PDE4 (phosphodiesterase 4). METHODS Isolated hearts from wild-type mice (WT, n = 110) and myocyte-specific PTEN-knockout mice (PKO, n = 94) were exposed to IPC or control conditions followed by IR. Subcellular fractionation was performed by sucrose gradient ultracentrifugation. RESULTS IPC limited myocardial infarct size (IS) in WT mice. The PDE4 inhibitor rolipram abolished the protective effect of IPC. However, small IS was found in PKO hearts after IR, and IPC did not decrease IS but enlarged it in PKO hearts. IPC promoted PDE4D localization to caveolin-3-enriched fractions in WT mice by increasing Akt levels at the caveolae. In PKO hearts, basal PDE4D levels were elevated at the caveolae, and IPC decreased PDE4D levels. Consistent with the subcellular PDE4D protein levels and its activity, elevation in intracellular Ca(2+) levels in the ischemic heart and opening of mPTP after IR were inhibited by IPC in WT mice, but not by IPC in PKO mice. CONCLUSIONS IPC inhibits mPTP opening by regulating the PTEN/PDE4 signaling pathway.
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Affiliation(s)
- Xiaoxu Zheng
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md., USA
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80
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Minobe E, Maeda S, Xu J, Hao L, Kameyama A, Kameyama M. A new phosphorylation site in cardiac L-type Ca2+ channels (Cav1.2) responsible for its cAMP-mediated modulation. Am J Physiol Cell Physiol 2014; 307:C999-C1009. [PMID: 25209265 DOI: 10.1152/ajpcell.00267.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cardiac L-type Ca(2+) channels are modulated by phosphorylation by protein kinase A (PKA). To explore the PKA-targeted phosphorylation site(s), five potential phosphorylation sites in the carboxyl (COOH) terminal region of the α1C-subunit of the guinea pig Cav1.2 Ca(2+) channel were mutated by replacing serine (S) or threonine (T) residues with alanine (A): S1574A (C1 site), S1626A (C2), S1699A (C3), T1908A, (C4), S1927A (C5), and their various combinations. The wild-type Ca(2+) channel activity was enhanced three- to fourfold by the adenylyl cyclase activator forskolin (Fsk, 5 μM), and that of mutants at C3, C4, C5, and combination of these sites was also significantly increased by Fsk. However, Fsk did not modulate the activity of the C1 and C2 mutants and mutants of combined sites involving the C1 site. Three peptides of the COOH-terminal tail of α1C, termed CT1 [corresponding to amino acids (aa) 1509-1789, containing sites C1-3], CT2 (aa 1778-2003, containing sites C4 and C5), and CT3 (aa 1942-2169), were constructed, and their phosphorylation by PKA was examined. CT1 and CT2, but not CT3, were phosphorylated in vitro by PKA. Three CT1 mutants at two sites of C1-C3 were also phosphorylated by PKA, but the mutant at all three sites was not. The CT2 mutant at the C4 site was phosphorylated by PKA, but the mutant at C5 sites was not. These results suggest that Ser(1574) (C1 site) may be a potential site for the channel modulation mediated by PKA.
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Affiliation(s)
- Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Sachiko Maeda
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, Sapporo, Japan; and
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Liying Hao
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan; Department of Pharmaceutical Toxicology, School of Pharmaceutical Sciences, China Medical University, Shenyang, China
| | - Asako Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Kagoshima, Japan;
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81
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Subramanyam P, Colecraft HM. Ion channel engineering: perspectives and strategies. J Mol Biol 2014; 427:190-204. [PMID: 25205552 DOI: 10.1016/j.jmb.2014.09.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/01/2014] [Indexed: 01/19/2023]
Abstract
Ion channels facilitate the passive movement of ions down an electrochemical gradient and across lipid bilayers in cells. This phenomenon is essential for life and underlies many critical homeostatic processes in cells. Ion channels are diverse and differ with respect to how they open and close (gating) and to their ionic conductance/selectivity (permeation). Fundamental understanding of ion channel structure-function mechanisms, their physiological roles, how their dysfunction leads to disease, their utility as biosensors, and development of novel molecules to modulate their activity are important and active research frontiers. In this review, we focus on ion channel engineering approaches that have been applied to investigate these aspects of ion channel function, with a major emphasis on voltage-gated ion channels.
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Affiliation(s)
- Prakash Subramanyam
- Department of Physiology and Cellular Biophysics, Columbia University, NY, 10032, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, NY, 10032, USA.
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82
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Simms BA, Souza IA, Zamponi GW. Effect of the Brugada syndrome mutation A39V on calmodulin regulation of Cav1.2 channels. Mol Brain 2014; 7:34. [PMID: 24775099 PMCID: PMC4012176 DOI: 10.1186/1756-6606-7-34] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 01/22/2023] Open
Abstract
Background The L-type calcium channel Cav1.2 is important for brain and heart function. The ubiquitous calcium sensing protein calmodulin (CaM) regulates calcium dependent gating of Cav1.2 channels by reducing calcium influx, a process known as calcium-dependent inactivation (CDI). Dissecting the calcium-dependence of CaM in this process has benefited greatly from the use of mutant CaM molecules which are unable to bind calcium to their low affinity (N-lobe) and high affinity (C-lobe) binding sites. Unlike CDI, it is unknown whether CaM can modulate the activation gating of Cav1.2 channels. Results We examined a Cav1.2 point mutant in the N-terminus region of the channel (A39V) that has been previously linked to Brugada syndrome. Using mutant CaM constructs in which the N- and/or C-lobe calcium binding sites were ablated, we were able to show that this Brugada syndrome mutation disrupts N-lobe CDI of the channel. In the course of these experiments, we discovered that all mutant CaM molecules were able to alter the kinetics of channel activation even in the absence of calcium for WT-Cav1.2, but not A39V-Cav1.2 channels. Moreover, CaM mutants differentially shifted the voltage-dependence of activation for WT and A39V-Cav1.2 channels to hyperpolarized potentials. Our data therefore suggest that structural changes in CaM that arise directly from site directed mutagenesis of calcium binding domains alter activation gating of Cav1.2 channels independently of their effects on calcium binding, and that the N-terminus of the channel contributes to this CaM dependent process. Conclusions Our data indicate that caution must be exercised when interpreting the effects of CaM mutants on ion channel gating.
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Affiliation(s)
| | | | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr, NW, Calgary T2N 4N1, Canada.
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Fu Q, Kim S, Soto D, De Arcangelis V, DiPilato L, Liu S, Xu B, Shi Q, Zhang J, Xiang YK. A long lasting β1 adrenergic receptor stimulation of cAMP/protein kinase A (PKA) signal in cardiac myocytes. J Biol Chem 2014; 289:14771-81. [PMID: 24713698 DOI: 10.1074/jbc.m113.542589] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small-molecule, ligand-activated G protein-coupled receptors are generally thought to be rapidly desensitized within a period of minutes through receptor phosphorylation and internalization after repeated or prolonged stimulation. This transient G protein-coupled receptor activation remains at odds with many observed long-lasting cellular and physiological responses. Here, using live cell imaging of cAMP with a FRET-based biosensor and myocyte contraction assay, we show that the catecholamine-activated β1 adrenergic receptor (β1AR) continuously stimulates second messenger cAMP synthesis in primary cardiac myocytes and neurons, which lasts for more than 8 h (a decay t½ of 3.9 h) in cardiac myocytes. However, the β1AR-induced cAMP signal is counterbalanced and masked by the receptor-bound phosphodiesterase (PDE) 4D8-dependent cAMP hydrolysis. Inhibition of PDE4 activity recovers the receptor-induced cAMP signal and promotes contractile response in mouse hearts during extended periods of agonist stimulation. β1AR associates with PDE4D8 through the receptor C-terminal PDZ motif-dependent binding to synaptic-associated protein 97 (SAP97). Knockdown of SAP97 or mutation of the β1AR PDZ motif disrupts the complex and promotes sustained agonist-induced cAMP activity, PKA phosphorylation, and cardiac myocyte contraction response. Together, these findings unveil a long lasting adrenergic signal in neurons and myocytes under prolonged stimulation and an underappreciated role of PDE that is essential in classic receptor signaling desensitization and in maintaining a long lasting cAMP equilibrium for ligand-induced physiological response.
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Affiliation(s)
- Qin Fu
- From the Department of Pharmacology, University of California at Davis, Davis, California 95616, the Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China, the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Sungjin Kim
- From the Department of Pharmacology, University of California at Davis, Davis, California 95616, the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Dagoberto Soto
- the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Vania De Arcangelis
- the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Lisa DiPilato
- the Department of Pharmacology and Molecular Sciences, John Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Shubai Liu
- the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Bing Xu
- From the Department of Pharmacology, University of California at Davis, Davis, California 95616
| | - Qian Shi
- From the Department of Pharmacology, University of California at Davis, Davis, California 95616, the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
| | - Jin Zhang
- the Department of Pharmacology and Molecular Sciences, John Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Yang K Xiang
- From the Department of Pharmacology, University of California at Davis, Davis, California 95616, the Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana, Illinois 61801, and
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Hofmann F, Flockerzi V, Kahl S, Wegener JW. L-type CaV1.2 calcium channels: from in vitro findings to in vivo function. Physiol Rev 2014; 94:303-26. [PMID: 24382889 DOI: 10.1152/physrev.00016.2013] [Citation(s) in RCA: 238] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The L-type Cav1.2 calcium channel is present throughout the animal kingdom and is essential for some aspects of CNS function, cardiac and smooth muscle contractility, neuroendocrine regulation, and multiple other processes. The L-type CaV1.2 channel is built by up to four subunits; all subunits exist in various splice variants that potentially affect the biophysical and biological functions of the channel. Many of the CaV1.2 channel properties have been analyzed in heterologous expression systems including regulation of the L-type CaV1.2 channel by Ca(2+) itself and protein kinases. However, targeted mutations of the calcium channel genes confirmed only some of these in vitro findings. Substitution of the respective serines by alanine showed that β-adrenergic upregulation of the cardiac CaV1.2 channel did not depend on the phosphorylation of the in vitro specified amino acids. Moreover, well-established in vitro phosphorylation sites of the CaVβ2 subunit of the cardiac L-type CaV1.2 channel were found to be irrelevant for the in vivo regulation of the channel. However, the molecular basis of some kinetic properties, such as Ca(2+)-dependent inactivation and facilitation, has been approved by in vivo mutagenesis of the CaV1.2α1 gene. This article summarizes recent findings on the in vivo relevance of well-established in vitro results.
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85
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Bondarenko VE. A compartmentalized mathematical model of the β1-adrenergic signaling system in mouse ventricular myocytes. PLoS One 2014; 9:e89113. [PMID: 24586529 PMCID: PMC3931689 DOI: 10.1371/journal.pone.0089113] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 01/14/2014] [Indexed: 01/08/2023] Open
Abstract
The β1-adrenergic signaling system plays an important role in the functioning of cardiac cells. Experimental data shows that the activation of this system produces inotropy, lusitropy, and chronotropy in the heart, such as increased magnitude and relaxation rates of [Ca2+]i transients and contraction force, and increased heart rhythm. However, excessive stimulation of β1-adrenergic receptors leads to heart dysfunction and heart failure. In this paper, a comprehensive, experimentally based mathematical model of the β1-adrenergic signaling system for mouse ventricular myocytes is developed, which includes major subcellular functional compartments (caveolae, extracaveolae, and cytosol). The model describes biochemical reactions that occur during stimulation of β1-adrenoceptors, changes in ionic currents, and modifications of Ca2+ handling system. Simulations describe the dynamics of major signaling molecules, such as cyclic AMP and protein kinase A, in different subcellular compartments; the effects of inhibition of phosphodiesterases on cAMP production; kinetics and magnitudes of phosphorylation of ion channels, transporters, and Ca2+ handling proteins; modifications of action potential shape and duration; magnitudes and relaxation rates of [Ca2+]i transients; changes in intracellular and transmembrane Ca2+ fluxes; and [Na+]i fluxes and dynamics. The model elucidates complex interactions of ionic currents upon activation of β1-adrenoceptors at different stimulation frequencies, which ultimately lead to a relatively modest increase in action potential duration and significant increase in [Ca2+]i transients. In particular, the model includes two subpopulations of the L-type Ca2+ channels, in caveolae and extracaveolae compartments, and their effects on the action potential and [Ca2+]i transients are investigated. The presented model can be used by researchers for the interpretation of experimental data and for the developments of mathematical models for other species or for pathological conditions.
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Affiliation(s)
- Vladimir E. Bondarenko
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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86
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Phosphorylation sites required for regulation of cardiac calcium channels in the fight-or-flight response. Proc Natl Acad Sci U S A 2013; 110:19621-6. [PMID: 24218620 DOI: 10.1073/pnas.1319421110] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
L-type Ca(2+) currents conducted by CaV1.2 channels initiate excitation-contraction coupling in the heart. Their activity is increased by β-adrenergic/cAMP signaling via phosphorylation by PKA in the fight-or-flight response, but the sites of regulation are unknown. We describe the functional role of phosphorylation of Ser1700 and Thr1704-sites of phosphorylation by PKA and casein kinase II at the interface between the proximal and distal C-terminal regulatory domains. Mutation of both residues to Ala in STAA mice reduced basal L-type Ca(2+) currents, due to a small decrease in expression and a substantial decrease in functional activity. The increase in L-type Ca(2+) current caused by isoproterenol was markedly reduced at physiological levels of stimulation (3-10 nM). Maximal increases in calcium current at nearly saturating concentrations of isoproterenol (100 nM) were also significantly reduced, but the mutation effects were smaller, suggesting that alternative regulatory mechanisms are engaged at maximal levels of stimulation. The β-adrenergic increase in cell contraction was also diminished. STAA ventricular myocytes exhibited arrhythmic contractions in response to isoproterenol, and up to 20% of STAA cells failed to sustain contractions when stimulated at 1 Hz. STAA mice have reduced exercise capacity, and cardiac hypertrophy is evident at 3 mo. We conclude that phosphorylation of Ser1700 and Thr1704 is essential for regulation of basal activity of CaV1.2 channels and for up-regulation by β-adrenergic signaling at physiological levels of stimulation. Disruption of phosphorylation at those sites leads to impaired cardiac function in vivo, as indicated by reduced exercise capacity and cardiac hypertrophy.
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