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Rebbeck RT, Svensson B, Zhang J, Samsó M, Thomas DD, Bers DM, Cornea RL. Kinetics and mapping of Ca-driven calmodulin conformations on skeletal and cardiac muscle ryanodine receptors. Nat Commun 2024; 15:5120. [PMID: 38879623 PMCID: PMC11180167 DOI: 10.1038/s41467-024-48951-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 05/16/2024] [Indexed: 06/19/2024] Open
Abstract
Calmodulin transduces [Ca2+] information regulating the rhythmic Ca2+ cycling between the sarcoplasmic reticulum and cytoplasm during contraction and relaxation in cardiac and skeletal muscle. However, the structural dynamics by which calmodulin modulates the sarcoplasmic reticulum Ca2+ release channel, the ryanodine receptor, at physiologically relevant [Ca2+] is unknown. Using fluorescence lifetime FRET, we resolve different structural states of calmodulin and Ca2+-driven shifts in the conformation of calmodulin bound to ryanodine receptor. Skeletal and cardiac ryanodine receptor isoforms show different calmodulin-ryanodine receptor conformations, as well as binding and structural kinetics with 0.2-ms resolution, which reflect different functional roles of calmodulin. These FRET methods provide insight into the physiological calmodulin-ryanodine receptor structural states, revealing additional distinct structural states that complement cryo-EM models that are based on less physiological conditions. This technology will drive future studies on pathological calmodulin-ryanodine receptor interactions and dynamics with other important ryanodine receptor bound modulators.
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Affiliation(s)
- Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Jingyan Zhang
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Montserrat Samsó
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Donald M Bers
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN, USA.
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2
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Svensson B, Nitu FR, Rebbeck RT, McGurran LM, Oda T, Thomas DD, Bers DM, Cornea RL. Molecular Mechanism of a FRET Biosensor for the Cardiac Ryanodine Receptor Pathologically Leaky State. Int J Mol Sci 2023; 24:12547. [PMID: 37628726 PMCID: PMC10454150 DOI: 10.3390/ijms241612547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 07/31/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023] Open
Abstract
Ca2+ leak from cardiomyocyte sarcoplasmic reticulum (SR) via hyperactive resting cardiac ryanodine receptor channels (RyR2) is pro-arrhythmic. An exogenous peptide (DPc10) binding promotes leaky RyR2 in cardiomyocytes and reports on that endogenous state. Conversely, calmodulin (CaM) binding inhibits RyR2 leak and low CaM affinity is diagnostic of leaky RyR2. These observations have led to designing a FRET biosensor for drug discovery targeting RyR2. We used FRET to clarify the molecular mechanism driving the DPc10-CaM interdependence when binding RyR2 in SR vesicles. We used donor-FKBP12.6 (D-FKBP) to resolve RyR2 binding of acceptor-CaM (A-CaM). In low nanomolar Ca2+, DPc10 decreased both FRETmax (under saturating [A-CaM]) and the CaM/RyR2 binding affinity. In micromolar Ca2+, DPc10 decreased FRETmax without affecting CaM/RyR2 binding affinity. This correlates with the analysis of fluorescence-lifetime-detected FRET, indicating that DPc10 lowers occupancy of the RyR2 CaM-binding sites in nanomolar (not micromolar) Ca2+ and lengthens D-FKBP/A-CaM distances independent of [Ca2+]. To observe DPc10/RyR2 binding, we used acceptor-DPc10 (A-DPc10). CaM weakens A-DPc10/RyR2 binding, with this effect being larger in micromolar versus nanomolar Ca2+. Moreover, A-DPc10/RyR2 binding is cooperative in a CaM- and FKBP-dependent manner, suggesting that both endogenous modulators promote concerted structural changes between RyR2 protomers for channel regulation. Aided by the analysis of cryo-EM structures, these insights inform further development of the DPc10-CaM paradigm for therapeutic discovery targeting RyR2.
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Affiliation(s)
- Bengt Svensson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
| | - Florentin R. Nitu
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
| | - Robyn T. Rebbeck
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
| | - Lindsey M. McGurran
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
| | - Tetsuro Oda
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Razvan L. Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; (B.S.); (R.T.R.); (L.M.M.)
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3
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Walweel K, Beard N, van Helden DF, Laver DR. Dantrolene inhibition of ryanodine channels (RyR2) in artificial lipid bilayers depends on FKBP12.6. J Gen Physiol 2023; 155:e202213277. [PMID: 37279522 PMCID: PMC10244881 DOI: 10.1085/jgp.202213277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 03/18/2023] [Accepted: 05/22/2023] [Indexed: 06/08/2023] Open
Abstract
Dantrolene is a neutral hydantoin that is clinically used as a skeletal muscle relaxant to prevent overactivation of the skeletal muscle calcium release channel (RyR1) in response to volatile anesthetics. Dantrolene has aroused considerable recent interest as a lead compound for stabilizing calcium release due to overactive cardiac calcium release channels (RyR2) in heart failure. Previously, we found that dantrolene produces up to a 45% inhibition RyR2 with an IC50 of 160 nM, and that this inhibition requires the physiological association between RyR2 and CaM. In this study, we tested the hypothesis that dantrolene inhibition of RyR2 in the presence of CaM is modulated by RyR2 phosphorylation at S2808 and S2814. Phosphorylation was altered by incubations with either exogenous phosphatase (PP1) or kinases; PKA to phosphorylate S2808 or endogenous CaMKII to phosphorylate S2814. We found that PKA caused selective dissociation of FKBP12.6 from the RyR2 complex and a loss of dantrolene inhibition. Rapamycin-induced FKBP12.6 dissociation from RyR2 also resulted in the loss of dantrolene inhibition. Subsequent incubations of RyR2 with exogenous FKBP12.6 reinstated dantrolene inhibition. These findings indicate that the inhibitory action of dantrolene on RyR2 depends on RyR2 association with FKBP12.6 in addition to CaM as previously found.
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Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
| | - Nicole Beard
- Faculty of Science and Technology, University of Canberra, Bruce, Australia
| | - Dirk F. van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
| | - Derek R. Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
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Svensson B, Nitu FR, Rebbeck RT, McGurran LM, Oda T, Thomas DD, Bers DM, Cornea RL. Molecular Mechanism of a FRET Biosensor for the Cardiac Ryanodine Receptor Pathologically Leaky State. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.07.548138. [PMID: 37461514 PMCID: PMC10350043 DOI: 10.1101/2023.07.07.548138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Ca 2+ leak from cardiomyocyte sarcoplasmic reticulum (SR) via hyperactive resting cardiac ryanodine receptor channels (RyR2) is pro-arrhythmic. An exogenous peptide, (DPc10) detects leaky RyR2 in cardiomyocytes. Conversely, calmodulin (CaM) inhibits RyR2 leak. These observations have led to designing a FRET biosensor for drug discovery targeting RyR2. Here we used FRET to understand the molecular mechanism driving the DPc10-CaM interdependence when binding RyR2 in SR vesicles. We used donor-FKBP12.6 (D-FKBP) to resolve RyR2 binding of acceptor-CaM (A-CaM). In low nanomolar Ca 2+ , DPc10 decreased both FRET max (under saturating [A-CaM]) and the CaM/RyR2 binding affinity. In micromolar Ca 2+ , DPc10 decreased FRET max without affecting CaM/RyR2 binding affinity. This correlates with analysis of fluorescence-lifetime-detected FRET indicating that DPc10 lowers occupancy of the RyR2 CaM-binding sites in nanomolar (not micromolar) Ca 2+ and lengthens D-FKBP/A-CaM distances independent of [Ca 2+ ]. To observe DPc10/RyR2 binding, we used acceptor-DPc10 (A-DPc10). CaM weakens A-DPc10/RyR2 binding, this effect being larger in micromolar vs. nanomolar Ca 2+ . Moreover, A-DPc10/RyR2 binding is cooperative in CaM- and FKBP-dependent manner, suggesting that both endogenous modulators promote concerted structural changes between RyR2 protomers for channel regulation. Aided by analysis of cryo-EM structures, these insights inform further development of the DPc10-CaM paradigm for therapeutic discovery targeting RyR2.
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Affiliation(s)
- Bengt Svensson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
| | - Florentin R. Nitu
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
| | - Robyn T. Rebbeck
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
| | - Lindsey M. McGurran
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
| | - Tetsuro Oda
- Department of Pharmacology, University of California, Davis
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis
| | - Razvan L. Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis
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5
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Fujii S, Kobayashi S, Chang Y, Nawata J, Yoshitomi R, Tanaka S, Kohno M, Nakamura Y, Ishiguchi H, Suetomi T, Uchinoumi H, Oda T, Okuda S, Okamura T, Yamamoto T, Yano M. RyR2-targeting therapy prevents left ventricular remodeling and ventricular tachycardia in post-infarction heart failure. J Mol Cell Cardiol 2023; 178:36-50. [PMID: 36963751 DOI: 10.1016/j.yjmcc.2023.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/15/2023] [Accepted: 03/21/2023] [Indexed: 03/26/2023]
Abstract
BACKGROUND Dantrolene binds to the Leu601-Cys620 region of the N-terminal domain of cardiac ryanodine receptor (RyR2), which corresponds to the Leu590-Cys609 region of the skeletal ryanodine receptor, and suppresses diastolic Ca2+ leakage through RyR2. OBJECTIVE We investigated whether the chronic administration of dantrolene prevented left ventricular (LV) remodeling and ventricular tachycardia (VT) after myocardial infarction (MI) by the same mechanism with the mutation V3599K of RyR2, which indicated that the inhibition of diastolic Ca2+ leakage occurred by enhancing the binding affinity of calmodulin (CaM) to RyR2. METHODS AND RESULTS A left anterior descending coronary artery ligation MI model was developed in mice. Wild-type (WT) were divided into four groups: sham-operated mice (WT-Sham), sham-operated mice treated with dantrolene (WT-Sham-DAN), MI mice (WT-MI), and MI mice treated with dantrolene (WT-MI-DAN). Homozygous V3599K RyR2 knock-in (KI) mice were divided into two groups: sham-operated mice (KI-Sham) and MI mice (KI-MI). The mice were followed for 12 weeks. Survival was significantly higher in the WT-MI-DAN (73%) and KI-MI groups (70%) than the WT-MI group (40%). Echocardiography, pathological tissue, and epinephrine-induced VT studies showed that LV remodeling and VT were prevented in the WT-MI-DAN and KI-MI groups compared to the WT-MI group. An increase in diastolic Ca2+ spark frequency and a decrease in the binding affinity of CaM to the RyR2 were observed at 12 weeks after MI in the WT-MI group, although significant improvements in these values were observed in the WT-MI-DAN and KI-MI groups. CONCLUSIONS Pharmacological or genetic stabilization of RyR2 tetrameric structure improves survival after MI by suppressing LV remodeling and proarrhythmia.
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Affiliation(s)
- Shohei Fujii
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Shigeki Kobayashi
- Department of Therapeutic Science for Heart Failure in the Elderly, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan.
| | - Yaowei Chang
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Junya Nawata
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Ryosuke Yoshitomi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Shinji Tanaka
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Michiaki Kohno
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Yoshihide Nakamura
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Hironori Ishiguchi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takeshi Suetomi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Hitoshi Uchinoumi
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Tetsuro Oda
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Shinichi Okuda
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takayuki Okamura
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takeshi Yamamoto
- Department of Laboratory Medicine, Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Masafumi Yano
- Division of Cardiology, Department of Medicine and Clinical Science, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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6
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Keefe JA, Moore OM, Ho KS, Wehrens XHT. Role of Ca 2+ in healthy and pathologic cardiac function: from normal excitation-contraction coupling to mutations that cause inherited arrhythmia. Arch Toxicol 2023; 97:73-92. [PMID: 36214829 PMCID: PMC10122835 DOI: 10.1007/s00204-022-03385-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/15/2022] [Indexed: 01/19/2023]
Abstract
Calcium (Ca2+) ions are a key second messenger involved in the rhythmic excitation and contraction of cardiomyocytes throughout the heart. Proper function of Ca2+-handling proteins is required for healthy cardiac function, whereas disruption in any of these can cause cardiac arrhythmias. This comprehensive review provides a broad overview of the roles of Ca2+-handling proteins and their regulators in healthy cardiac function and the mechanisms by which mutations in these proteins contribute to inherited arrhythmias. Major Ca2+ channels and Ca2+-sensitive regulatory proteins involved in cardiac excitation-contraction coupling are discussed, with special emphasis on the function of the RyR2 macromolecular complex. Inherited arrhythmia disorders including catecholaminergic polymorphic ventricular tachycardia, long QT syndrome, Brugada syndrome, short QT syndrome, and arrhythmogenic right-ventricular cardiomyopathy are discussed with particular emphasis on subtypes caused by mutations in Ca2+-handling proteins.
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Affiliation(s)
- Joshua A Keefe
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Oliver M Moore
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Kevin S Ho
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA.,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX, 77030, USA. .,Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA. .,Center for Space Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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7
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Miotto MC, Weninger G, Dridi H, Yuan Q, Liu Y, Wronska A, Melville Z, Sittenfeld L, Reiken S, Marks AR. Structural analyses of human ryanodine receptor type 2 channels reveal the mechanisms for sudden cardiac death and treatment. SCIENCE ADVANCES 2022; 8:eabo1272. [PMID: 35857850 PMCID: PMC9299551 DOI: 10.1126/sciadv.abo1272] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/03/2022] [Indexed: 05/29/2023]
Abstract
Ryanodine receptor type 2 (RyR2) mutations have been linked to an inherited form of exercise-induced sudden cardiac death called catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT results from stress-induced sarcoplasmic reticular Ca2+ leak via the mutant RyR2 channels during diastole. We present atomic models of human wild-type (WT) RyR2 and the CPVT mutant RyR2-R2474S determined by cryo-electron microscopy with overall resolutions in the range of 2.6 to 3.6 Å, and reaching local resolutions of 2.25 Å, unprecedented for RyR2 channels. Under nonactivating conditions, the RyR2-R2474S channel is in a "primed" state between the closed and open states of WT RyR2, rendering it more sensitive to activation that results in stress-induced Ca2+ leak. The Rycal drug ARM210 binds to RyR2-R2474S, reverting the primed state toward the closed state. Together, these studies provide a mechanism for CPVT and for the therapeutic actions of ARM210.
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Affiliation(s)
- Marco C. Miotto
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Gunnar Weninger
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Haikel Dridi
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Qi Yuan
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Yang Liu
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Anetta Wronska
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Zephan Melville
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Leah Sittenfeld
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Steven Reiken
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
| | - Andrew R. Marks
- Department of Physiology and Cellular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Clyde and Helen Wu Center for Molecular Cardiology, Columbia University, New York, NY, USA
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8
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Tanaka S, Yamamoto T, Mikawa M, Nawata J, Fujii S, Nakamura Y, Kato T, Fukuda M, Suetomi T, Uchinoumi H, Oda T, Okuda S, Okamura T, Kobayashi S, Yano. M. Stabilization of RyR2 maintains right ventricular function, reduces the development of ventricular arrhythmias, and improves prognosis in pulmonary hypertension. Heart Rhythm 2022; 19:986-997. [DOI: 10.1016/j.hrthm.2022.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 01/18/2022] [Accepted: 02/01/2022] [Indexed: 02/01/2023]
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9
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Greene D, Barton M, Luchko T, Shiferaw Y. Computational Analysis of Binding Interactions between the Ryanodine Receptor Type 2 and Calmodulin. J Phys Chem B 2021; 125:10720-10735. [PMID: 34533024 DOI: 10.1021/acs.jpcb.1c03896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mutations in the cardiac ryanodine receptor type 2 (RyR2) have been linked to a variety of cardiac arrhythmias, such as catecholaminergic polymorphic ventricular tachycardia (CPVT). RyR2 is regulated by calmodulin (CaM), and mutations that disrupt their interaction can cause aberrant calcium release, leading to an arrhythmia. It was recently shown that increasing the RyR2-CaM binding affinity could rescue a defective CPVT-related RyR2 channel to near wild-type behavior. However, the interactions that determine the binding affinity at the RyR2-CaM binding interface are not well understood. In this study, we identify the key domains and interactions, including several new interactions, involved in the binding of CaM to RyR2. Also, our comparison between the wild-type and V3599K mutant suggests how the RyR2-CaM binding affinity can be increased via a change in the central and N-terminal lobe binding contacts for CaM. This computational approach provides new insights into the effect of a mutation at the RyR2-CaM binding interface, and it may find utility in drug design for the future treatment of cardiac arrhythmias.
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Affiliation(s)
- D'Artagnan Greene
- Department of Physics, California State University, Northridge, California 91330, United States
| | - Michael Barton
- Department of Physics, California State University, Northridge, California 91330, United States
| | - Tyler Luchko
- Department of Physics, California State University, Northridge, California 91330, United States
| | - Yohannes Shiferaw
- Department of Physics, California State University, Northridge, California 91330, United States
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10
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Ledford HA, Park S, Muir D, Woltz RL, Ren L, Nguyen PT, Sirish P, Wang W, Sihn CR, George AL, Knollmann BC, Yamoah EN, Yarov-Yarovoy V, Zhang XD, Chiamvimonvat N. Different arrhythmia-associated calmodulin mutations have distinct effects on cardiac SK channel regulation. J Gen Physiol 2021; 152:211546. [PMID: 33211795 PMCID: PMC7681919 DOI: 10.1085/jgp.202012667] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 08/25/2020] [Accepted: 10/19/2020] [Indexed: 12/21/2022] Open
Abstract
Calmodulin (CaM) plays a critical role in intracellular signaling and regulation of Ca2+-dependent proteins and ion channels. Mutations in CaM cause life-threatening cardiac arrhythmias. Among the known CaM targets, small-conductance Ca2+-activated K+ (SK) channels are unique, since they are gated solely by beat-to-beat changes in intracellular Ca2+. However, the molecular mechanisms of how CaM mutations may affect the function of SK channels remain incompletely understood. To address the structural and functional effects of these mutations, we introduced prototypical human CaM mutations in human induced pluripotent stem cell–derived cardiomyocyte-like cells (hiPSC-CMs). Using structural modeling and molecular dynamics simulation, we demonstrate that human calmodulinopathy-associated CaM mutations disrupt cardiac SK channel function via distinct mechanisms. CaMD96V and CaMD130G mutants reduce SK currents through a dominant-negative fashion. By contrast, specific mutations replacing phenylalanine with leucine result in conformational changes that affect helix packing in the C-lobe, which disengage the interactions between apo-CaM and the CaM-binding domain of SK channels. Distinct mutant CaMs may result in a significant reduction in the activation of the SK channels, leading to a decrease in the key Ca2+-dependent repolarization currents these channels mediate. The findings in this study may be generalizable to other interactions of mutant CaMs with Ca2+-dependent proteins within cardiac myocytes.
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Affiliation(s)
- Hannah A Ledford
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA
| | - Seojin Park
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV
| | - Duncan Muir
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA
| | - Ryan L Woltz
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA
| | - Lu Ren
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA
| | - Phuong T Nguyen
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA
| | - Padmini Sirish
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA
| | - Wenying Wang
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV
| | - Choong-Ryoul Sihn
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, School of Medicine, Vanderbilt University, Nashville, TN
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA
| | - Xiao-Dong Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis, Davis, CA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA
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11
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Enhancing calmodulin binding to ryanodine receptor is crucial to limit neuronal cell loss in Alzheimer disease. Sci Rep 2021; 11:7289. [PMID: 33790404 PMCID: PMC8012710 DOI: 10.1038/s41598-021-86822-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 03/16/2021] [Indexed: 12/23/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive neuronal cell loss. Recently, dysregulation of intracellular Ca2+ homeostasis has been suggested as a common proximal cause of neural dysfunction in AD. Here, we investigated (1) the pathogenic role of destabilization of ryanodine receptor (RyR2) in endoplasmic reticulum (ER) upon development of AD phenotypes in AppNL-G-F mice, which harbor three familial AD mutations (Swedish, Beyreuther/Iberian, and Arctic), and (2) the therapeutic effect of enhanced calmodulin (CaM) binding to RyR2. In the neuronal cells from AppNL-G-F mice, CaM dissociation from RyR2 was associated with AD-related phenotypes, i.e. Aβ accumulation, TAU phosphorylation, ER stress, neuronal cell loss, and cognitive dysfunction. Surprisingly, either genetic (by V3599K substitution in RyR2) or pharmacological (by dantrolene) enhancement of CaM binding to RyR2 reversed almost completely the aforementioned AD-related phenotypes, except for Aβ accumulation. Thus, destabilization of RyR2 due to CaM dissociation is most likely an early and fundamental pathogenic mechanism involved in the development of AD. The discovery that neuronal cell loss can be fully prevented simply by stabilizing RyR2 sheds new light on the treatment of AD.
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12
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Lemos FO, Bultynck G, Parys JB. A comprehensive overview of the complex world of the endo- and sarcoplasmic reticulum Ca 2+-leak channels. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119020. [PMID: 33798602 DOI: 10.1016/j.bbamcr.2021.119020] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/09/2021] [Accepted: 03/13/2021] [Indexed: 12/11/2022]
Abstract
Inside cells, the endoplasmic reticulum (ER) forms the largest Ca2+ store. Ca2+ is actively pumped by the SERCA pumps in the ER, where intraluminal Ca2+-binding proteins enable the accumulation of large amount of Ca2+. IP3 receptors and the ryanodine receptors mediate the release of Ca2+ in a controlled way, thereby evoking complex spatio-temporal signals in the cell. The steady state Ca2+ concentration in the ER of about 500 μM results from the balance between SERCA-mediated Ca2+ uptake and the passive leakage of Ca2+. The passive Ca2+ leak from the ER is often ignored, but can play an important physiological role, depending on the cellular context. Moreover, excessive Ca2+ leakage significantly lowers the amount of Ca2+ stored in the ER compared to normal conditions, thereby limiting the possibility to evoke Ca2+ signals and/or causing ER stress, leading to pathological consequences. The so-called Ca2+-leak channels responsible for Ca2+ leakage from the ER are however still not well understood, despite over 20 different proteins have been proposed to contribute to it. This review has the aim to critically evaluate the available evidence about the various channels potentially involved and to draw conclusions about their relative importance.
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Affiliation(s)
- Fernanda O Lemos
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, B-3000 Leuven, Belgium.
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13
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Maltsev AV, Kokoz YM. Cardiomyocytes generating spontaneous Ca2+-transients as tools for precise estimation of sarcoplasmic reticulum Ca2+ transport. Arch Biochem Biophys 2020; 693:108542. [DOI: 10.1016/j.abb.2020.108542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 07/19/2020] [Accepted: 08/07/2020] [Indexed: 01/05/2023]
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14
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Tamitani M, Yamamoto T, Yamamoto N, Fujisawa K, Tanaka S, Nakamura Y, Uchinoumi H, Oda T, Okuda S, Takami T, Kobayashi S, Sakaida I, Yano M. Dantrolene prevents hepatic steatosis by reducing cytoplasmic Ca2+ level and ER stress. Biochem Biophys Rep 2020; 23:100787. [PMID: 32715106 PMCID: PMC7374254 DOI: 10.1016/j.bbrep.2020.100787] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 11/24/2022] Open
Abstract
Introduction Our previous studies demonstrated that dantrolene, a ryanodine receptor stabilizer, prevents endoplasmic reticulum (ER) stress in the heart. ER stress is a strong mediator of impaired lipid metabolism in the liver, thereby contributing to fatty liver disease. In this study, we investigated the effects of dantrolene on fatty liver disease in mice and ER stress in hepatocytes. Methods and results Eight weeks old C57BL/6 mice were fed high-fat diet (HFD) for 8 weeks with or without the oral administration of dantrolene (100 mg/kg/day). The livers of mice without dantrolene (HFD group) showed severe fatty liver, whereas the livers of the mice treated with dantrolene (HFD + DAN group) only showed slightly fatty liver. To address the preventive effects of dantrolene, primary hepatocytes were cultured with palmitate in the presence or absence of dantrolene. Dantrolene reduced lipid load and prevents palmitate-induced increase in cytoplasmic Ca2+ and ER stress. Based on these findings, we propose that dantrolene is a potential new therapeutic agent against fatty liver disease. Oral dantrolene prevents fatty liver disease in mice. Dantrolene reduced the cytoplasmic Ca2+ level in hepatocytes. Dantrolene reduced the GRP78 protein level in hepatocytes.
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15
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Sufu-Shimizu Y, Okuda S, Kato T, Nishimura S, Uchinoumi H, Oda T, Kobayashi S, Yamamoto T, Yano M. Stabilizing cardiac ryanodine receptor prevents the development of cardiac dysfunction and lethal arrhythmia in Ca2+/calmodulin-dependent protein kinase IIδc transgenic mice. Biochem Biophys Res Commun 2020; 524:431-438. [DOI: 10.1016/j.bbrc.2020.01.107] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 01/18/2020] [Indexed: 12/20/2022]
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16
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Kajii T, Kobayashi S, Shiba S, Fujii S, Tamitani M, Kohno M, Nakamura Y, Nanno T, Kato T, Okuda S, Uchinoumi H, Oda T, Yamamoto T, Yano M. Dantrolene prevents ventricular tachycardia by stabilizing the ryanodine receptor in pressure- overload induced failing hearts. Biochem Biophys Res Commun 2019; 521:57-63. [PMID: 31635807 DOI: 10.1016/j.bbrc.2019.10.071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 10/08/2019] [Indexed: 12/28/2022]
Abstract
Aberrant Ca2+ release from cardiac ryanodine receptors (RyR2) has been shown to be one of the most important causes of lethal arrhythmia in various types of failing hearts. We previously showed that dantrolene, a specific agent for the treatment of malignant hyperthermia, inhibits Ca2+ leakage from the RyR2 by correcting the defective inter-domain interaction between the N-terminal (1-619 amino acids) and central (2000-2500 amino acids) domains of the RyR2 and allosterically enhancing the binding affinity of calmodulin to the RyR2 in diseased hearts. In this study, we examined whether dantrolene inhibits this Ca2+ leakage, thereby preventing the pharmacologically inducible ventricular tachycardia in ventricular pressure-overloaded failing hearts. Ventricular tachycardia (VT) was easily induced after an injection of epinephrine in mice after 8 weeks of transverse aortic constriction-induced pressure-overload. Pretreatment with dantrolene almost completely inhibited the pharmacologically inducible VT. In the presence of dantrolene, the occurrence of both Ca2+ sparks and spontaneous Ca2+ transients was inhibited, which was associated with enhanced calmodulin binding affinity to the RyR2. These results suggest that dantrolene could be a new potent agent in the treatment of lethal arrhythmia in cases of acquired heart failure.
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Affiliation(s)
- Toshiro Kajii
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Shigeki Kobayashi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Sho Shiba
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Shohei Fujii
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Masaki Tamitani
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Michiaki Kohno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Yoshihide Nakamura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Takuma Nanno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Takayoshi Kato
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Shinichi Okuda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Hitoshi Uchinoumi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Tetsuro Oda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan
| | - Takeshi Yamamoto
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan.
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17
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Nakamura Y, Yamamoto T, Kobayashi S, Tamitani M, Hamada Y, Fukui G, Xu X, Nishimura S, Kato T, Uchinoumi H, Oda T, Okuda S, Yano M. Ryanodine receptor-bound calmodulin is essential to protect against catecholaminergic polymorphic ventricular tachycardia. JCI Insight 2019; 4:126112. [PMID: 31167968 DOI: 10.1172/jci.insight.126112] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 04/17/2019] [Indexed: 12/12/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is caused by a single point mutation in the cardiac type 2 ryanodine receptor (RyR2). Using a knockin (KI) mouse model (R2474S/+), we previously reported that a single point mutation within the RyR2 sensitizes the channel to agonists, primarily mediated by defective interdomain interaction within the RyR2 and subsequent dissociation of calmodulin (CaM) from the RyR2. Here, we examined whether CPVT can be genetically rescued by enhancing the binding affinity of CaM to the RyR2. We first determined whether there is a possible amino acid substitution within the CaM-binding domain in the RyR2 (3584-3603 residues) that can enhance its binding affinity to CaM and found that V3599K substitution showed the highest binding affinity of CaM to the CaM-binding domain. Hence, we generated a heterozygous KI mouse model (V3599K/+) with a single amino acid substitution in the CaM-binding domain of the RyR2 and crossbred it with the heterozygous CPVT-associated R2474S/+-KI mouse to obtain a double-heterozygous R2474S/V3599K-KI mouse model. The CPVT phenotypes - bidirectional or polymorphic ventricular tachycardia, spontaneous Ca2+ transients, and Ca2+ sparks - were all inhibited in the R2474S/V3599K mice. Thus, enhancement of the CaM-binding affinity of the RyR2 is essential to prevent CPVT-associated arrhythmogenesis.
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Affiliation(s)
- Yoshihide Nakamura
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Takeshi Yamamoto
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Shigeki Kobayashi
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Masaki Tamitani
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Yoriomi Hamada
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Go Fukui
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Xiaojuan Xu
- Department of Pathology and Pathophysiology, School of Medicine, Tongji University, Shanghai, China
| | | | - Takayoshi Kato
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Hitoshi Uchinoumi
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Tetsuro Oda
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Shinichi Okuda
- Department of Medicine and Clinical Science, Division of Cardiology, and
| | - Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, and
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18
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Walweel K, Gomez-Hurtado N, Rebbeck RT, Oo YW, Beard NA, Molenaar P, Dos Remedios C, van Helden DF, Cornea RL, Knollmann BC, Laver DR. Calmodulin inhibition of human RyR2 channels requires phosphorylation of RyR2-S2808 or RyR2-S2814. J Mol Cell Cardiol 2019; 130:96-106. [PMID: 30928430 DOI: 10.1016/j.yjmcc.2019.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/19/2019] [Accepted: 03/25/2019] [Indexed: 01/08/2023]
Abstract
Calmodulin (CaM) is a Ca-binding protein that binds to, and can directly inhibit cardiac ryanodine receptor calcium release channels (RyR2). Animal studies have shown that RyR2 hyperphosphorylation reduces CaM binding to RyR2 in failing hearts, but data are lacking on how CaM regulates human RyR2 and how this regulation is affected by RyR2 phosphorylation. Physiological concentrations of CaM (100 nM) inhibited the diastolic activity of RyR2 isolated from failing human hearts by ~50% but had no effect on RyR2 from healthy human hearts. Using FRET between donor-FKBP12.6 and acceptor-CaM bound to RyR2, we determined that CaM binds to RyR2 from healthy human heart with a Kd = 121 ± 14 nM. Ex-vivo phosphorylation/dephosphorylation experiments suggested that the divergent CaM regulation of healthy and failing human RyR2 was caused by differences in RyR2 phosphorylation by protein kinase A and Ca-CaM-dependent kinase II. Ca2+-spark measurements in murine cardiomyocytes harbouring RyR2 phosphomimetic or phosphoablated mutants at S2814 and S2808 suggest that phosphorylation of residues corresponding to either human RyR2-S2808 or S2814 is both necessary and sufficient for RyR2 regulation by CaM. Our results challenge the current concept that CaM universally functions as a canonical inhibitor of RyR2 across species. Rather, CaM's biological action on human RyR2 appears to be more nuanced, with inhibitory activity only on phosphorylated RyR2 channels, which occurs during exercise or in patients with heart failure.
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Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
| | - Nieves Gomez-Hurtado
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Ye Wint Oo
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia
| | - Nicole A Beard
- Faculty of Science and Technology, University of Canberra, Bruce, ACT 2617, Australia.
| | - Peter Molenaar
- School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD 4000, Australia; Northside Clinical School of Medicine, University of Queensland, Cardio-vascular Molecular & Therapeutics Translational Research Group, The Prince Charles Hospital, Chermside, QLD 4032. Australia.
| | - Cris Dos Remedios
- Bosch Institute, Discipline of Anatomy, University of Sydney, Sydney, New South Wales 2006, Australia.
| | - Dirk F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
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19
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Nishimura S, Yamamoto T, Nakamura Y, Kohno M, Hamada Y, Sufu Y, Fukui G, Nanno T, Ishiguchi H, Kato T, Xu X, Ono M, Oda T, Okuda S, Kobayashi S, Yano M. Mutation-linked, excessively tight interaction between the calmodulin binding domain and the C-terminal domain of the cardiac ryanodine receptor as a novel cause of catecholaminergic polymorphic ventricular tachycardia. Heart Rhythm 2018; 15:905-914. [PMID: 29427818 DOI: 10.1016/j.hrthm.2018.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Indexed: 12/16/2022]
Abstract
BACKGROUND Ryanodine receptor (RyR2) is known to be a causal gene of catecholaminergic polymorphic ventricular tachycardia (CPVT), an important inherited disease. Some of the human CPVT-associated mutations have been found in a domain (4026-4172) that has EF hand motifs, the so-called calmodulin (CaM)-like domain (CaMLD). OBJECTIVE The purpose of this study was to investigate the underlying mechanism by which CPVT is induced by a mutation at CaMLD. METHODS A new N4103K/+ knock-in (KI) mice model was generated. RESULTS Sustained ventricular tachycardia was frequently observed after infusion of caffeine plus epinephrine in KI mice. Endogenous CaM bound to RyR2 decreased even at baseline in isolated KI cardiomyocytes. Ca2+ spark frequency (CaSpF) was much higher in KI cells than in wild-type cells. Addition of GSH-CaM (higher affinity CaM to RyR2) significantly decreased CaSpF. In response to isoproterenol, spontaneous Ca2+ transient (SCaT) was frequently observed in intact KI cells. Incorporation of GSH-CaM into intact KI cells using a protein delivery kit decreased SCaT significantly. An assay using a quartz crystal microbalance technique revealed that mutated CaMLD peptide showed higher binding affinity to CaM binding domain (CaMBD) peptide. CONCLUSION In the N4103K mutant, CaM binding affinity to RyR2 was significantly reduced regardless of beta-adrenergic stimulation. We found that this was caused by an abnormally tight interaction between CaMBD and mutated CaM-like domain (N4103K-CaMBD). Thus, CaMBD-CaMLD interaction may be a novel therapeutic target for treatment of lethal arrhythmia.
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Affiliation(s)
- Shigehiko Nishimura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takeshi Yamamoto
- Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, Japan.
| | - Yoshihide Nakamura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Michiaki Kohno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yoriomi Hamada
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yoko Sufu
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Go Fukui
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takuma Nanno
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Hironori Ishiguchi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takayoshi Kato
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Xiaojuan Xu
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Makoto Ono
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Tetsuro Oda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Shinichi Okuda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Shigeki Kobayashi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan
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20
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Okuda S, Sufu-Shimizu Y, Kato T, Fukuda M, Nishimura S, Oda T, Kobayashi S, Yamamoto T, Morimoto S, Yano M. CaMKII-mediated phosphorylation of RyR2 plays a crucial role in aberrant Ca 2+ release as an arrhythmogenic substrate in cardiac troponin T-related familial hypertrophic cardiomyopathy. Biochem Biophys Res Commun 2018; 496:1250-1256. [PMID: 29402414 DOI: 10.1016/j.bbrc.2018.01.181] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 01/30/2018] [Indexed: 02/05/2023]
Abstract
AIMS Cardiac Troponin T (TnT) mutation-linked familial hypertrophic cardiomyopathy (FHC) is known to cause sudden cardiac death at a young age. Here, we investigated the role of the Ca2+ release channel of the cardiac sarcoplasmic reticulum (SR), ryanodine receptor (RyR2), in the pathogenic mechanism of lethal arrhythmia in FHC-related TnT-mutated transgenic mice (TG; TnT-delta160E). METHODS AND RESULTS In TG cardiomyocytes, the Ca2+ spark frequency (SpF) was much higher than that in non-TG cardiomyocytes. These differences were more pronounced in the presence of isoproterenol (ISO; 10 nM). This increase in SpF was largely reversed by a CaMKII inhibitor (KN-93), but not by a protein kinase A inhibitor (H89). CaMKII phosphorylation at Ser2814 in RyR2 was increased significantly in TG. Spontaneous Ca2+ transients (sCaTs) after cessation of a 1-5 Hz pacing, frequently observed in ISO-treated TG cardiomyocytes, were also attenuated by KN-93, but not by H89. The RyR2 stabilizer dantrolene attenuated Ca2+ sparks and sCaTs in ISO-treated TG cardiomyocytes, indicating that the mutation-linked aberrant Ca2+ release is mediated by destabilized RyR2. CONCLUSIONS In FHC-linked TnT-mutated hearts, RyR2 is susceptible to CaMKII-mediated phosphorylation, presumably because of a mutation-linked increase in diastolic [Ca2+]i, causing aberrant Ca2+ release leading to lethal arrhythmia.
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Affiliation(s)
- Shinichi Okuda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan.
| | - Yoko Sufu-Shimizu
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takayoshi Kato
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Masakazu Fukuda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Shigehiko Nishimura
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Tetsuro Oda
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Shigeki Kobayashi
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Takeshi Yamamoto
- Department of Clinical Laboratory Science, Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | - Sachio Morimoto
- Department of Health Sciences Fukuoka, International University of Health and Welfare, 131-7 Enokizu, Okawa, Fukuoka 831-8501, Japan
| | - Masafumi Yano
- Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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Walweel K, Oo YW, Laver DR. The emerging role of calmodulin regulation of RyR2 in controlling heart rhythm, the progression of heart failure and the antiarrhythmic action of dantrolene. Clin Exp Pharmacol Physiol 2017; 44:135-142. [PMID: 27626620 DOI: 10.1111/1440-1681.12669] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/27/2016] [Accepted: 09/09/2016] [Indexed: 11/28/2022]
Abstract
Cardiac output and rhythm depend on the release and the take-up of calcium from the sarcoplasmic reticulum (SR). Excessive diastolic calcium leak from the SR due to dysfunctional calcium release channels (RyR2) contributes to the formation of delayed after-depolarizations, which underlie the fatal arrhythmias that occur in heart failure and inherited syndromes. Calmodulin (CaM) is a calcium-binding protein that regulates target proteins and acts as a calcium sensor. CaM is comprised of two calcium-binding EF-hand domains and a flexible linker. CaM is an accessory protein that partially inhibits RyR2 channel activity. CaM is critical for normal cardiac function, and altered CaM binding and efficacy may contribute to defects in SR calcium release. The present paper reviews CaM binding to RyR2 and how it regulates RyR2 channel activity. It then goes on to review how mutations in the CaM amino acid sequence give rise to inherited syndromes such as Catecholaminergic Polymorphic Ventricular Tachychardia (CPVT) and long QT syndrome (LQTS). In addition, the role of reduced CaM binding to RyR2 that results from RyR2 phosphorylation or from oxidation of either RyR2 or CaM contributes to the progression of heart failure is reviewed. Finally, this manuscript reviews recent evidence that CaM binding to RyR2 is required for the inhibitory action of a pharmaceutical agent (dantrolene) on RyR2. Dantrolene is a clinically used muscle relaxant that has recently been found to exert antiarrhythmic effects against SR Ca2+ overload arrhythmias.
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Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, 2308, Australia
| | - Ye Win Oo
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, 2308, Australia
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, 2308, Australia
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Kato T, Yamamoto T, Nakamura Y, Nanno T, Fukui G, Sufu Y, Hamada Y, Maeda T, Nishimura S, Ishiguchi H, Murakami W, Fukuda M, Xu X, Hino A, Ono M, Oda T, Okuda S, Kobayashi S, Koseki N, Kyushiki H, Yano M. Correction of impaired calmodulin binding to RyR2 as a novel therapy for lethal arrhythmia in the pressure-overloaded heart failure. Heart Rhythm 2017; 14:120-127. [DOI: 10.1016/j.hrthm.2016.10.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Indexed: 11/29/2022]
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Triggered activity in atrial myocytes is influenced by Na +/Ca 2+ exchanger activity in genetically altered mice. J Mol Cell Cardiol 2016; 101:106-115. [PMID: 27838371 DOI: 10.1016/j.yjmcc.2016.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 10/26/2016] [Accepted: 11/08/2016] [Indexed: 02/05/2023]
Abstract
AIMS In atrial fibrillation, increased function of the Na+/Ca2+-exchanger (NCX) is one among several electrical remodeling mechanisms. METHODS/RESULTS Using the patch-clamp- and Ca2+ imaging-methods, we investigated atrial myocytes from NCX-homozygous-overexpressor (OE)- and heterozygous-knockout (KO)-mice and their corresponding wildtypes (WTOE; WTKO). NCX mediated Ca2+ extrusion capacity was reduced in KO and increased in OE. There was no evidence for structural or molecular remodeling. During a proarrhythmic pacing-protocol, the number of low amplitude delayed afterdepolarizations (DADs) was unaltered in OE vs. WTOE and KO vs. WTKO. However, DADs triggered full spontaneous action potentials (sAP) significantly more often in OE vs. WTOE (ratio sAP/DAD: OE:0.18±0.05; WTOE:0.02±0.02; p<0.001). Using the same protocol, a DAD triggered an sAP by tendency less often in KO vs. WTKO (p=0.06) and significantly less often under a more aggressive proarrhythmic protocol (ratio sAP/DAD: KO:0.01±0.003; WT KO: 0.12±0.05; p=0.007). The DAD amplitude was increased in OE vs. WTOE and decreased in KO vs. WTKO. There were no differences in SR-Ca2+-load, the number of spontaneous Ca2+-release-events or IKACh/IK1. CONCLUSIONS Atrial myocytes with increased NCX expression exhibited increased vulnerability towards sAPs while atriomyocytes with reduced NCX expression were protected. The underlying mechanism consists of a modification of the DAD-amplitude by the level of NCX-activity. Thus, although the number of spontaneous Ca2+-releases and therefore DADs is unaltered, the higher DAD-amplitude in OE made a transgression of the voltage-threshold of an sAP more likely. These findings indicate that the level of NCX activity could influence triggered activity in atrial myocytes independent of possible remodeling processes.
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Choy L, Yeo JM, Tse V, Chan SP, Tse G. Cardiac disease and arrhythmogenesis: Mechanistic insights from mouse models. IJC HEART & VASCULATURE 2016; 12:1-10. [PMID: 27766308 PMCID: PMC5064289 DOI: 10.1016/j.ijcha.2016.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/02/2016] [Indexed: 12/19/2022]
Abstract
The mouse is the second mammalian species, after the human, in which substantial amount of the genomic information has been analyzed. With advances in transgenic technology, mutagenesis is now much easier to carry out in mice. Consequently, an increasing number of transgenic mouse systems have been generated for the study of cardiac arrhythmias in ion channelopathies and cardiomyopathies. Mouse hearts are also amenable to physical manipulation such as coronary artery ligation and transverse aortic constriction to induce heart failure, radiofrequency ablation of the AV node to model complete AV block and even implantation of a miniature pacemaker to induce cardiac dyssynchrony. Last but not least, pharmacological models, despite being simplistic, have enabled us to understand the physiological mechanisms of arrhythmias and evaluate the anti-arrhythmic properties of experimental agents, such as gap junction modulators, that may be exert therapeutic effects in other cardiac diseases. In this article, we examine these in turn, demonstrating that primary inherited arrhythmic syndromes are now recognized to be more complex than abnormality in a particular ion channel, involving alterations in gene expression and structural remodelling. Conversely, in cardiomyopathies and heart failure, mutations in ion channels and proteins have been identified as underlying causes, and electrophysiological remodelling are recognized pathological features. Transgenic techniques causing mutagenesis in mice are extremely powerful in dissecting the relative contributions of different genes play in producing disease phenotypes. Mouse models can serve as useful systems in which to explore how protein defects contribute to arrhythmias and direct future therapy.
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Affiliation(s)
- Lois Choy
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, SW7 2AZ, UK
| | - Vivian Tse
- Department of Physiology, McGill University, Canada
| | - Shing Po Chan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Gary Tse
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
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CaMKII-dependent phosphorylation of RyR2 promotes targetable pathological RyR2 conformational shift. J Mol Cell Cardiol 2016; 98:62-72. [PMID: 27318036 DOI: 10.1016/j.yjmcc.2016.06.007] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/27/2016] [Accepted: 06/14/2016] [Indexed: 01/27/2023]
Abstract
Diastolic calcium (Ca) leak via cardiac ryanodine receptors (RyR2) can cause arrhythmias and heart failure (HF). Ca/calmodulin (CaM)-dependent kinase II (CaMKII) is upregulated and more active in HF, promoting RyR2-mediated Ca leak by RyR2-Ser2814 phosphorylation. Here, we tested a mechanistic hypothesis that RyR2 phosphorylation by CaMKII increases Ca leak by promoting a pathological RyR2 conformation with reduced CaM affinity. Acute CaMKII activation in wild-type RyR2, and phosphomimetic RyR2-S2814D (vs. non-phosphorylatable RyR2-S2814A) knock-in mouse myocytes increased SR Ca leak, reduced CaM-RyR2 affinity, and caused a pathological shift in RyR2 conformation (detected via increased access of the RyR2 structural peptide DPc10). This same trio of effects was seen in myocytes from rabbits with pressure/volume-overload induced HF. Excess CaM quieted leak and restored control conformation, consistent with negative allosteric coupling between CaM affinity and DPc10 accessible conformation. Dantrolene (DAN) also restored CaM affinity, reduced DPc10 access, and suppressed RyR2-mediated Ca leak and ventricular tachycardia in RyR2-S2814D mice. We propose that a common pathological RyR2 conformational state (low CaM affinity, high DPc10 access, and elevated leak) may be caused by CaMKII-dependent phosphorylation, oxidation, and HF. Moreover, DAN (or excess CaM) can shift this pathological gating state back to the normal physiological conformation, a potentially important therapeutic approach.
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Effect of α-Allocryptopine on Delayed Afterdepolarizations and Triggered Activities in Mice Cardiomyocytes Treated with Isoproterenol. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:634172. [PMID: 26557861 PMCID: PMC4629026 DOI: 10.1155/2015/634172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 08/07/2015] [Accepted: 08/13/2015] [Indexed: 12/16/2022]
Abstract
Objective. To investigate the effect of α-allocryptopine (ALL) on delayed afterdepolarization (DAD) incidence and triggered activity (TA) in mice administered isoproterenol (ISO). Methods. Mouse ventricular myocytes were isolated. And the cellular electrophysiological properties of ventricular myocytes were investigated. Results. We found that the incidences of DADs and TA in mouse myocytes were increased by ISO treatment. In sharp contrast, triggered arrhythmia events were rarely observed in myocytes with 10 μM ALL treatment. Transient inward current (I ti) was reduced significantly with ALL treatment, which contributed to DAD-related triggered arrhythmia. Compared to Iso-treated group, the L-type calcium current (I Ca,L) densities were decreased after exposure to ALL, along with slower activation, quicker inactivation, and longer time constant of recovery from inactivation kinetics. Conclusion. There is less triggered arrhythmia events in ventricular myocytes treated with ALL. This effect may be associated with the inhibition of I ti and I Ca,L.
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Huang TQ, Zou MX, Pasek DA, Meissner G. mTOR signaling in mice with dysfunctional cardiac ryanodine receptor ion channel. ACTA ACUST UNITED AC 2015; 8:43-51. [PMID: 26312014 PMCID: PMC4547478 DOI: 10.2147/jrlcr.s78410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Simultaneous substitution of three amino acid residues in the calmodulin binding domain (W3587A/L3591D/F3603A, ADA) of the cardiac ryanodine receptor ion channel (RyR2) impairs calmodulin inhibition of RyR2 and causes cardiac hypertrophy and early death of Ryr2ADA/ADA mice. To determine the physiological significance of growth promoting signaling molecules, the protein and phosphorylation levels of Ser/Thr kinase mTOR and upstream and downstream signaling molecules were determined in hearts of wild-type and Ryr2ADA/ADA mice. Phosphorylation of mTOR at Ser-2448, and mTOR downstream targets p70S6 kinase at Thr-389, S6 ribosomal protein at Ser-240/244, and 4E-BP1 at Ser-65 were increased. However, there was no increased phosphorylation of mTOR upstream kinases PDK1 at Ser-241, AKT at Thr-308, AMPK at Thr-172, and ERK1/2 at Thr-202/Tyr204. To confirm a role for mTOR signaling in the development of cardiac hypertrophy, rapamycin, an inhibitor of mTOR, was injected into wild-type and mutant mice. Rapamycin decreased mouse heart-to-body weight ratio, improved cardiac performance, and decreased phosphorylation of mTOR and downstream targets p70S6K and S6 in 10-day-old Ryr2ADA/ADA mice but did not extend longevity. Taken together, the results link a dysfunctional RyR2 to an altered activity of signaling molecules that regulate cardiac growth and function.
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Affiliation(s)
- Tai-Qin Huang
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Min-Xu Zou
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Daniel A Pasek
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
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The Ever Changing Moods of Calmodulin: How Structural Plasticity Entails Transductional Adaptability. J Mol Biol 2014; 426:2717-35. [DOI: 10.1016/j.jmb.2014.05.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/14/2014] [Accepted: 05/16/2014] [Indexed: 11/20/2022]
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