1
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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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Bertolini M, Mendive-Tapia L, Ghashghaei O, Reese A, Lochenie C, Schoepf AM, Sintes M, Tokarczyk K, Nare Z, Scott AD, Knight SR, Aithal AR, Sachdeva A, Lavilla R, Vendrell M. Nonperturbative Fluorogenic Labeling of Immunophilins Enables the Wash-free Detection of Immunosuppressants. ACS CENTRAL SCIENCE 2024; 10:969-977. [PMID: 38799658 PMCID: PMC11117681 DOI: 10.1021/acscentsci.3c01590] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/26/2024] [Accepted: 02/26/2024] [Indexed: 05/29/2024]
Abstract
Immunosuppressants are clinically approved drugs to treat the potential rejection of transplanted organs and require frequent monitoring due to their narrow therapeutic window. Immunophilins are small proteins that bind immunosuppressants with high affinity, yet there are no examples of fluorogenic immunophilins and their potential application as optical biosensors for immunosuppressive drugs in clinical biosamples. In the present work, we designed novel diazonium BODIPY salts for the site-specific labeling of tyrosine residues in peptides via solid-phase synthesis as well as for late-stage functionalization of whole recombinant proteins. After the optimization of a straightforward one-step labeling procedure for immunophilins PPIA and FKBP12, we demonstrated the application of a fluorogenic analogue of FKBP12 for the selective detection of the immunosuppressant drug tacrolimus, including experiments in urine samples from patients with functioning renal transplants. This chemical methodology opens new avenues to rationally design wash-free immunophilin-based biosensors for rapid therapeutic drug monitoring.
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Affiliation(s)
- Marco Bertolini
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4UU Edinburgh, U.K.
- IRR
Chemistry Hub, Institute for Regeneration and Repair, The University of Edinburgh, EH16 4UU Edinburgh, U.K.
| | - Lorena Mendive-Tapia
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4UU Edinburgh, U.K.
- IRR
Chemistry Hub, Institute for Regeneration and Repair, The University of Edinburgh, EH16 4UU Edinburgh, U.K.
| | - Ouldouz Ghashghaei
- Laboratory
of Medicinal Chemistry, Faculty of Pharmacy and Food Sciences and
Institute of Biomedicine UB (IBUB), University
of Barcelona, Catalunya, Spain 08007
| | - Abigail Reese
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4UU Edinburgh, U.K.
- IRR
Chemistry Hub, Institute for Regeneration and Repair, The University of Edinburgh, EH16 4UU Edinburgh, U.K.
| | - Charles Lochenie
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4UU Edinburgh, U.K.
- IRR
Chemistry Hub, Institute for Regeneration and Repair, The University of Edinburgh, EH16 4UU Edinburgh, U.K.
| | - Anna M. Schoepf
- Laboratory
of Medicinal Chemistry, Faculty of Pharmacy and Food Sciences and
Institute of Biomedicine UB (IBUB), University
of Barcelona, Catalunya, Spain 08007
| | - Miquel Sintes
- Laboratory
of Medicinal Chemistry, Faculty of Pharmacy and Food Sciences and
Institute of Biomedicine UB (IBUB), University
of Barcelona, Catalunya, Spain 08007
| | - Karolina Tokarczyk
- Concept
Life Sciences Ltd, Edinburgh Bioquarter, Edinburgh EH16 4UX, U.K.
| | - Zandile Nare
- Concept
Life Sciences Ltd, Edinburgh Bioquarter, Edinburgh EH16 4UX, U.K.
| | - Andrew D. Scott
- Concept
Life Sciences Ltd, Edinburgh Bioquarter, Edinburgh EH16 4UX, U.K.
| | - Stephen R. Knight
- Renal
Transplant Unit, Queen Elizabeth Hospital, 1345 Govan Road, Glasgow G51 4TF, U.K.
| | - Advait R. Aithal
- School of
Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
| | - Amit Sachdeva
- School of
Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
| | - Rodolfo Lavilla
- Laboratory
of Medicinal Chemistry, Faculty of Pharmacy and Food Sciences and
Institute of Biomedicine UB (IBUB), University
of Barcelona, Catalunya, Spain 08007
| | - Marc Vendrell
- Centre
for Inflammation Research, The University
of Edinburgh, EH16 4UU Edinburgh, U.K.
- IRR
Chemistry Hub, Institute for Regeneration and Repair, The University of Edinburgh, EH16 4UU Edinburgh, U.K.
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3
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Šeflová J, Schwarz JA, Smith AN, Svensson B, Blackwell DJ, Phillips TA, Nikolaienko R, Bovo E, Rebbeck RT, Zima AV, Thomas DD, Van Petegem F, Knollmann BC, Johnston JN, Robia SL, Cornea RL. RyR2 Binding of an Antiarrhythmic Cyclic Depsipeptide Mapped Using Confocal Fluorescence Lifetime Detection of FRET. ACS Chem Biol 2023; 18:2290-2299. [PMID: 37769131 DOI: 10.1021/acschembio.3c00376] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Hyperactivity of cardiac sarcoplasmic reticulum (SR) ryanodine receptor (RyR2) Ca2+-release channels contributes to heart failure and arrhythmias. Reducing the RyR2 activity, particularly during cardiac relaxation (diastole), is a desirable therapeutic goal. We previously reported that the unnatural enantiomer (ent) of an insect-RyR activator, verticilide, inhibits porcine and mouse RyR2 at diastolic (nanomolar) Ca2+ and has in vivo efficacy against atrial and ventricular arrhythmia. To determine the ent-verticilide structural mode of action on RyR2 and guide its further development via medicinal chemistry structure-activity relationship studies, here, we used fluorescence lifetime (FLT)-measurements of Förster resonance energy transfer (FRET) in HEK293 cells expressing human RyR2. For these studies, we used an RyR-specific FRET molecular-toolkit and computational methods for trilateration (i.e., using distances to locate a point of interest). Multiexponential analysis of FLT-FRET measurements between four donor-labeled FKBP12.6 variants and acceptor-labeled ent-verticilide yielded distance relationships placing the acceptor probe at two candidate loci within the RyR2 cryo-EM map. One locus is within the Ry12 domain (at the corner periphery of the RyR2 tetrameric complex). The other locus is sandwiched at the interface between helical domain 1 and the SPRY3 domain. These findings document RyR2-target engagement by ent-verticilide, reveal new insight into the mechanism of action of this new class of RyR2-targeting drug candidate, and can serve as input in future computational determinations of the ent-verticilide binding site on RyR2 that will inform structure-activity studies for lead optimization.
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Affiliation(s)
- Jaroslava Šeflová
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Jacob A Schwarz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Abigail N Smith
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Taylor A Phillips
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Björn C Knollmann
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Răzvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
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4
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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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5
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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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6
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MATSUKAWA HIROYUKI, MURAYAMA TAKASHI. Development of Ryanodine Receptor (RyR) Inhibitors for Skeletal Muscle and Heart Diseases. JUNTENDO IJI ZASSHI = JUNTENDO MEDICAL JOURNAL 2023; 69:180-187. [PMID: 38855953 PMCID: PMC11153067 DOI: 10.14789/jmj.jmj22-0045-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/13/2023] [Indexed: 06/11/2024]
Abstract
Ryanodine receptors (RyR) are intracellular calcium (Ca2+) release channels on the sarcoplasmic reticulum of skeletal and cardiac muscles that play a central role in excitation-contraction coupling. Genetic mutations or posttranslational modifications of RyR causes hyperactivation of the channel, leading to various skeletal muscle and heart diseases. Currently, no specific treatments exist for most RyR-associated diseases. Recently, high-throughput screening (HTS) assays have been developed to identify potential candidates for treating RyR-related muscle diseases. These assays have successfully identified several compounds as novel RyR inhibitors, which are effective in animal models. In this review, we will focus on recent progress in HTS assays and discuss future perspectives of these promising approaches.
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Affiliation(s)
| | - TAKASHI MURAYAMA
- Corresponding author: Takashi Murayama, Department of Pharmacology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan, TEL: +81-3-5802-1035 E-mail: Research of the 4th Alumni Scientific Award for Medical Student, Juntendo University School of Medicine
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7
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Murayama T, Kurebayashi N, Ishida R, Kagechika H. Drug development for the treatment of RyR1-related skeletal muscle diseases. Curr Opin Pharmacol 2023; 69:102356. [PMID: 36842386 DOI: 10.1016/j.coph.2023.102356] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 02/27/2023]
Abstract
Type 1 ryanodine receptor (RyR1) is an intracellular Ca2+ release channel on the sarcoplasmic reticulum of skeletal muscle, and it plays a central role in excitation-contraction (E-C) coupling. Mutations in RyR1 are implicated in various muscle diseases including malignant hyperthermia, central core disease, and myopathies. Currently, no specific treatment exists for most of these diseases. Recently, high-throughput screening (HTS) assays have been developed for identifying potential candidates for treating RyR-related muscle diseases. Currently, two different methods, namely a FRET-based assay and an endoplasmic reticulum Ca2+-based assay, are available. These assays identified several compounds as novel RyR1 inhibitors. In addition, the development of a reconstituted platform permitted HTS assays for E-C coupling modulators. In this review, we will focus on recent progress in HTS assays and discuss future perspectives of these promising approaches.
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Affiliation(s)
- Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan.
| | - Nagomi Kurebayashi
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo, Japan
| | - Ryosuke Ishida
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hiroyuki Kagechika
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan
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8
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Rebbeck R, Ginsburg KS, Ko CY, Fasoli A, Rusch K, Cai GF, Dong X, Thomas DD, Bers DM, Cornea RL. Synergistic FRET assays for drug discovery targeting RyR2 channels. J Mol Cell Cardiol 2022; 168:13-23. [PMID: 35405106 PMCID: PMC10088286 DOI: 10.1016/j.yjmcc.2022.04.002] [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: 08/23/2021] [Revised: 03/09/2022] [Accepted: 04/05/2022] [Indexed: 10/18/2022]
Abstract
A key therapeutic target for heart failure and arrhythmia is the deleterious leak through sarcoplasmic reticulum (SR) ryanodine receptor 2 (RyR2) calcium release channels. We have previously developed methods to detect the pathologically leaky state of RyR2 in adult cardiomyocytes by monitoring RyR2 binding to either calmodulin (CaM) or a biosensor peptide (DPc10). Here, we test whether these complementary binding measurements are effective as high-throughput screening (HTS) assays to discover small molecules that target leaky RyR2. Using FRET, we developed and validated HTS procedures under conditions that mimic a pathological state, to screen the library of 1280 pharmaceutically active compounds (LOPAC) for modulators of RyR2 in cardiac SR membrane preparations. Complementary FRET assays with acceptor-labeled CaM and DPc10 were used for Hit prioritization based on the opposing binding properties of CaM vs. DPc10. This approach narrowed the Hit list to one compound, Ro 90-7501, which altered FRET to suggest increased RyR2-CaM binding and decreased DPc10 binding. Follow-up studies revealed that Ro 90-7501 does not detrimentally affect myocyte Ca2+ transients. Moreover, Ro 90-7501 partially inhibits overall Ca2+ leak, as assessed by Ca2+ sparks in permeabilized rat cardiomyocytes. Together, these results demonstrate (1) the effectiveness of our HTS approach where two complementary assays synergize for Hit ranking and (2) a drug discovery process that combines high-throughput, high-precision in vitro structural assays with in situ myocyte assays of the pathologic RyR2 leak. These provide a drug discovery platform compatible with large-scale HTS campaigns, to identify agents that inhibit RyR2 for therapeutic development.
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Affiliation(s)
- RobynT Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, MN, USA
| | | | - Christopher Y Ko
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Anna Fasoli
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Katherine Rusch
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, MN, USA
| | - George F Cai
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, MN, USA
| | - Xiaoqiong Dong
- Department of Pharmacology, University of California, Davis, CA, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, MN, USA; Photonic Pharma LLC, Minneapolis, MN, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, MN, USA; Photonic Pharma LLC, Minneapolis, MN, USA.
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9
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Cardiac ryanodine receptor N-terminal region biosensors identify novel inhibitors via FRET-based high-throughput screening. J Biol Chem 2021; 298:101412. [PMID: 34793835 PMCID: PMC8689225 DOI: 10.1016/j.jbc.2021.101412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 11/08/2021] [Accepted: 11/11/2021] [Indexed: 12/15/2022] Open
Abstract
The N-terminal region (NTR) of ryanodine receptor (RyR) channels is critical for the regulation of Ca2+ release during excitation–contraction (EC) coupling in muscle. The NTR hosts numerous mutations linked to skeletal (RyR1) and cardiac (RyR2) myopathies, highlighting its potential as a therapeutic target. Here, we constructed two biosensors by labeling the mouse RyR2 NTR at domains A, B, and C with FRET pairs. Using fluorescence lifetime (FLT) detection of intramolecular FRET signal, we developed high-throughput screening (HTS) assays with these biosensors to identify small-molecule RyR modulators. We then screened a small validation library and identified several hits. Hits with saturable FRET dose–response profiles and previously unreported effects on RyR were further tested using [3H]ryanodine binding to isolated sarcoplasmic reticulum vesicles to determine effects on intact RyR opening in its natural membrane. We identified three novel inhibitors of both RyR1 and RyR2 and two RyR1-selective inhibitors effective at nanomolar Ca2+. Two of these hits activated RyR1 only at micromolar Ca2+, highlighting them as potential enhancers of excitation–contraction coupling. To determine whether such hits can inhibit RyR leak in muscle, we further focused on one, an FDA-approved natural antibiotic, fusidic acid (FA). In skinned skeletal myofibers and permeabilized cardiomyocytes, FA inhibited RyR leak with no detrimental effect on skeletal myofiber excitation–contraction coupling. However, in intact cardiomyocytes, FA induced arrhythmogenic Ca2+ transients, a cautionary observation for a compound with an otherwise solid safety record. These results indicate that HTS campaigns using the NTR biosensor can identify compounds with therapeutic potential.
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10
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Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
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Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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11
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Maietta V, Reyes-García J, Yadav VR, Zheng YM, Peng X, Wang YX. Cellular and Molecular Processes in Pulmonary Hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1304:21-38. [PMID: 34019261 DOI: 10.1007/978-3-030-68748-9_2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pulmonary hypertension (PH) is a progressive lung disease characterized by persistent pulmonary vasoconstriction. Another well-recognized characteristic of PH is the muscularization of peripheral pulmonary arteries. This pulmonary vasoremodeling manifests in medial hypertrophy/hyperplasia of smooth muscle cells (SMCs) with possible neointimal formation. The underlying molecular processes for these two major vascular responses remain not fully understood. On the other hand, a series of very recent studies have shown that the increased reactive oxygen species (ROS) seems to be an important player in mediating pulmonary vasoconstriction and vasoremodeling, thereby leading to PH. Mitochondria are a primary site for ROS production in pulmonary artery (PA) SMCs, which subsequently activate NADPH oxidase to induce further ROS generation, i.e., ROS-induced ROS generation. ROS control the activity of multiple ion channels to induce intracellular Ca2+ release and extracellular Ca2+ influx (ROS-induced Ca2+ release and influx) to cause PH. ROS and Ca2+ signaling may synergistically trigger an inflammatory cascade to implicate in PH. Accordingly, this paper explores the important roles of ROS, Ca2+, and inflammatory signaling in the development of PH, including their reciprocal interactions, key molecules, and possible therapeutic targets.
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Affiliation(s)
- Vic Maietta
- Department of Molecular & Cellular Physiology, Albany Medical College, Albany, NY, USA
| | - Jorge Reyes-García
- Department of Molecular & Cellular Physiology, Albany Medical College, Albany, NY, USA.,Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Vishal R Yadav
- Department of Molecular & Cellular Physiology, Albany Medical College, Albany, NY, USA
| | - Yun-Min Zheng
- Department of Molecular & Cellular Physiology, Albany Medical College, Albany, NY, USA.
| | - Xu Peng
- Department of Medical Physiology, College of Medicine, Texas A&M University, College Station, TX, USA.
| | - Yong-Xiao Wang
- Department of Molecular & Cellular Physiology, Albany Medical College, Albany, NY, USA.
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12
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Gong D, Yan N, Ledford HA. Structural Basis for the Modulation of Ryanodine Receptors. Trends Biochem Sci 2020; 46:489-501. [PMID: 33353849 DOI: 10.1016/j.tibs.2020.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/16/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022]
Abstract
Historically, ryanodine receptors (RyRs) have presented unique challenges for high-resolution structural determination despite long-standing interest in their role in excitation-contraction coupling. Owing to their large size (nearly 2.2 MDa), high-resolution structures remained elusive until the advent of cryogenic electron microscopy (cryo-EM) techniques. In recent years, structures for both RyR1 and RyR2 have been solved at near-atomic resolution. Furthermore, recent reports have delved into their more complex structural associations with key modulators - proteins such as the dihydropyridine receptor (DHPR), FKBP12/12.6, and calmodulin (CaM), as well as ions and small molecules including Ca2+, ATP, caffeine, and PCB95. This review addresses the modulation of RyR1 and RyR2, in addition to the impact of such discoveries on intracellular Ca2+ dynamics and biophysical properties.
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Affiliation(s)
- Deshun Gong
- Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province/Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou 310024, Zhejiang, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou 310024, Zhejiang Province, China.
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Hannah A Ledford
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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13
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RyR1-targeted drug discovery pipeline integrating FRET-based high-throughput screening and human myofiber dynamic Ca 2+ assays. Sci Rep 2020; 10:1791. [PMID: 32019969 PMCID: PMC7000700 DOI: 10.1038/s41598-020-58461-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/13/2020] [Indexed: 11/18/2022] Open
Abstract
Elevated cytoplasmic [Ca2+] is characteristic in severe skeletal and cardiac myopathies, diabetes, and neurodegeneration, and partly results from increased Ca2+ leak from sarcoplasmic reticulum stores via dysregulated ryanodine receptor (RyR) channels. Consequently, RyR is recognized as a high-value target for drug discovery to treat such pathologies. Using a FRET-based high-throughput screening assay that we previously reported, we identified small-molecule compounds that modulate the skeletal muscle channel isoform (RyR1) interaction with calmodulin and FK506 binding protein 12.6. Two such compounds, chloroxine and myricetin, increase FRET and inhibit [3H]ryanodine binding to RyR1 at nanomolar Ca2+. Both compounds also decrease RyR1 Ca2+ leak in human skinned skeletal muscle fibers. Furthermore, we identified compound concentrations that reduced leak by > 50% but only slightly affected Ca2+ release in excitation-contraction coupling, which is essential for normal muscle contraction. This report demonstrates a pipeline that effectively filters small-molecule RyR1 modulators towards clinical relevance.
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14
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McCarthy MR, Savich Y, Cornea RL, Thomas DD. Resolved Structural States of Calmodulin in Regulation of Skeletal Muscle Calcium Release. Biophys J 2020; 118:1090-1100. [PMID: 32049056 DOI: 10.1016/j.bpj.2020.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 12/20/2019] [Accepted: 01/06/2020] [Indexed: 12/22/2022] Open
Abstract
Calmodulin (CaM) is proposed to modulate activity of the skeletal muscle sarcoplasmic reticulum (SR) calcium release channel (ryanodine receptor, RyR1 isoform) via a mechanism dependent on the conformation of RyR1-bound CaM. However, the correlation between CaM structure and functional regulation of RyR in physiologically relevant conditions is largely unknown. Here, we have used time-resolved fluorescence resonance energy transfer (TR-FRET) to study structural changes in CaM that may play a role in the regulation of RyR1. We covalently labeled each lobe of CaM (N and C) with fluorescent probes and used intramolecular TR-FRET to assess interlobe distances when CaM is bound to RyR1 in SR membranes, purified RyR1, or a peptide corresponding to the CaM-binding domain of RyR (RyRp). TR-FRET resolved an equilibrium between two distinct structural states (conformations) of CaM, each characterized by an interlobe distance and Gaussian distribution width (disorder). In isolated CaM, at low Ca2+, the two conformations of CaM are resolved, centered at 5 nm (closed) and 7 nm (open). At high Ca2+, the equilibrium shifts to favor the open conformation. In the presence of RyRp at high Ca2+, the closed conformation shifts to a more compact conformation and is the major component. When CaM is bound to full-length RyR1, either purified or in SR membranes, strikingly different results were obtained: 1) the two conformations are resolved and more ordered, 2) the open state is the major component, and 3) Ca2+ stabilized the closed conformation by a factor of two. We conclude that the Ca2+-dependent structural distribution of CaM bound to RyR1 is distinct from that of CaM bound to RyRp. We propose that the function of RyR1 is tuned to the Ca2+-dependent structural dynamics of bound CaM.
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Affiliation(s)
- Megan R McCarthy
- Department of Biochemistry, Molecular Biology, and Biophysics, Minneapolis, Minnesota
| | - Yahor Savich
- Department of Biochemistry, Molecular Biology, and Biophysics, Minneapolis, Minnesota; School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, Minneapolis, Minnesota
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, Minneapolis, Minnesota.
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15
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Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
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Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
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16
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Johnson CN, Pattanayek R, Potet F, Rebbeck RT, Blackwell DJ, Nikolaienko R, Sequeira V, Le Meur R, Radwański PB, Davis JP, Zima AV, Cornea RL, Damo SM, Györke S, George AL, Knollmann BC. The CaMKII inhibitor KN93-calmodulin interaction and implications for calmodulin tuning of Na V1.5 and RyR2 function. Cell Calcium 2019; 82:102063. [PMID: 31401388 DOI: 10.1016/j.ceca.2019.102063] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/15/2019] [Accepted: 07/26/2019] [Indexed: 02/06/2023]
Abstract
Here we report the structure of the widely utilized calmodulin (CaM)-dependent protein kinase II (CaMKII) inhibitor KN93 bound to the Ca2+-sensing protein CaM. KN93 is widely believed to inhibit CaMKII by binding to the kinase. The CaM-KN93 interaction is significant as it can interfere with the interaction between CaM and it's physiological targets, thereby raising the possibility of ascribing modified protein function to CaMKII phosphorylation while concealing a CaM-protein interaction. NMR spectroscopy, stopped-flow kinetic measurements, and x-ray crystallography were used to characterize the structure and biophysical properties of the CaM-KN93 interaction. We then investigated the functional properties of the cardiac Na+ channel (NaV1.5) and ryanodine receptor (RyR2). We find that KN93 disrupts a high affinity CaM-NaV1.5 interaction and alters channel function independent of CaMKII. Moreover, KN93 increases RyR2 Ca2+ release in cardiomyocytes independent of CaMKII. Therefore, when interpreting KN93 data, targets other than CaMKII need to be considered.
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Affiliation(s)
- Christopher N Johnson
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA; Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
| | - Rekha Pattanayek
- Department of Life and Physical Sciences, Fisk University, Nashville, TN 37208, USA
| | - Franck Potet
- Department of Pharmacology Feinberg School of Medicine, Northwestern University, Chicago IL, 60611, USA
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel J Blackwell
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood IL, 60153, USA
| | - Vasco Sequeira
- Department of Translational Science Universitätsklinikum, Würzburg, Germany
| | - Remy Le Meur
- Department of Biochemistry, Vanderbilt University, Nashville TN 37204, USA
| | - Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jonathan P Davis
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood IL, 60153, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics University of Minnesota, Minneapolis, MN 55455, USA
| | - Steven M Damo
- Department of Life and Physical Sciences, Fisk University, Nashville, TN 37208, USA
| | - Sandor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Alfred L George
- Department of Pharmacology Feinberg School of Medicine, Northwestern University, Chicago IL, 60611, USA
| | - Björn C Knollmann
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA
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17
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Unnatural verticilide enantiomer inhibits type 2 ryanodine receptor-mediated calcium leak and is antiarrhythmic. Proc Natl Acad Sci U S A 2019; 116:4810-4815. [PMID: 30792355 DOI: 10.1073/pnas.1816685116] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ca2+ leak via ryanodine receptor type 2 (RyR2) can cause potentially fatal arrhythmias in a variety of heart diseases and has also been implicated in neurodegenerative and seizure disorders, making RyR2 an attractive therapeutic target for drug development. Here we synthesized and investigated the fungal natural product and known insect RyR antagonist (-)-verticilide and several congeners to determine their activity against mammalian RyR2. Although the cyclooligomeric depsipeptide natural product (-)-verticilide had no effect, its nonnatural enantiomer [ent-(+)-verticilide] significantly reduced RyR2-mediated spontaneous Ca2+ leak both in cardiomyocytes from wild-type mouse and from a gene-targeted mouse model of Ca2+ leak-induced arrhythmias (Casq2-/-). ent-(+)-verticilide selectively inhibited RyR2-mediated Ca2+ leak and exhibited higher potency and a distinct mechanism of action compared with the pan-RyR inhibitors dantrolene and tetracaine and the antiarrhythmic drug flecainide. ent-(+)-verticilide prevented arrhythmogenic membrane depolarizations in cardiomyocytes without significant effects on the cardiac action potential and attenuated ventricular arrhythmia in catecholamine-challenged Casq2-/- mice. These findings indicate that ent-(+)-verticilide is a potent and selective inhibitor of RyR2-mediated diastolic Ca2+ leak, making it a molecular tool to investigate the therapeutic potential of targeting RyR2 hyperactivity in heart and brain pathologies. The enantiomer-specific activity and straightforward chemical synthesis of (unnatural) ent-(+)-verticilide provides a compelling argument to prioritize ent-natural product synthesis. Despite their general absence in nature, the enantiomers of natural products may harbor unprecedented activity, thereby leading to new scaffolds for probe and therapeutic development.
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18
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Rebbeck RT, Essawy MM, Nitu FR, Grant BD, Gillispie GD, Thomas DD, Bers DM, Cornea RL. High-Throughput Screens to Discover Small-Molecule Modulators of Ryanodine Receptor Calcium Release Channels. SLAS DISCOVERY 2016; 22:176-186. [PMID: 27760856 DOI: 10.1177/1087057116674312] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Using time-resolved fluorescence resonance energy transfer (FRET), we have developed and validated the first high-throughput screening (HTS) method to discover compounds that modulate an intracellular Ca2+ channel, the ryanodine receptor (RyR), for therapeutic applications. Intracellular Ca2+ regulation is critical for striated muscle function, and RyR is a central player. At resting [Ca2+], an increased propensity of channel opening due to RyR dysregulation is associated with severe cardiac and skeletal myopathies, diabetes, and neurological disorders. This leaky state of the RyR is an attractive target for pharmacological agents to treat such pathologies. Our FRET-based HTS detects RyR binding of accessory proteins calmodulin (CaM) or FKBP12.6. Under conditions that mimic a pathological state, we carried out a screen of the 727-compound NIH Clinical Collection, which yielded six compounds that reproducibly changed FRET by >3 SD. Dose-response of FRET and [3H]ryanodine binding readouts reveal that five hits reproducibly alter RyR1 structure and activity. One compound increased FRET and inhibited RyR1, which was only significant at nM [Ca2+], and accentuated without CaM present. These properties characterize a compound that could mitigate RyR1 leak. An excellent Z' factor and the tight correlation between structural and functional readouts validate this first HTS method to identify RyR modulators.
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Affiliation(s)
- Robyn T Rebbeck
- 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Maram M Essawy
- 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Florentin R Nitu
- 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | | | | | - David D Thomas
- 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Donald M Bers
- 3 Department of Pharmacology, University of California, Davis, CA, USA
| | - Razvan L Cornea
- 1 Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
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19
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Rebbeck RT, Nitu FR, Rohde D, Most P, Bers DM, Thomas DD, Cornea RL. S100A1 Protein Does Not Compete with Calmodulin for Ryanodine Receptor Binding but Structurally Alters the Ryanodine Receptor·Calmodulin Complex. J Biol Chem 2016; 291:15896-907. [PMID: 27226555 DOI: 10.1074/jbc.m115.713107] [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] [Received: 12/29/2015] [Indexed: 11/06/2022] Open
Abstract
S100A1 has been suggested as a therapeutic agent to enhance myocyte Ca(2+) cycling in heart failure, but its molecular mode of action is poorly understood. Using FRET, we tested the hypothesis that S100A1 directly competes with calmodulin (CaM) for binding to intact, functional ryanodine receptors type I (RyR1) and II (RyR2) from skeletal and cardiac muscle, respectively. Our FRET readout provides an index of acceptor-labeled CaM binding near donor-labeled FKBP (FK506-binding protein 12.6) on the cytoplasmic domain of RyR in isolated sarcoplasmic reticulum vesicles. S100A1 (0.01-400 μm) partially inhibited FRET (i.e. CaM binding), with Ki > 10 μm, for both RyR1 and RyR2. The high [S100A1] required for partial effects on FRET indicates a lack of competition by S100A1 on CaM/RyR binding under normal physiological conditions. High-resolution analysis of time-resolved FRET detects two structural states of RyR-bound CaM, which respond to [Ca(2+)] and are isoform-specific. The distribution of these structural states was perturbed only by high micromolar [S100A1], which promoted a shift of bound CaM to a lower FRET orientation (without altering the amount of CaM bound to RyR). Thus, high micromolar S100A1 does alter the CaM/RyR interaction, without involving competition. Nevertheless, submicromolar S100A1 can alter RyR function, an effect that is influenced by both [Ca(2+)] and [CaM]. We conclude that CaM and S100A1 can concurrently bind to and functionally modulate RyR1 and RyR2, but this does not involve direct competition at the RyR CaM binding site.
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Affiliation(s)
- Robyn T Rebbeck
- From the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis Minnesota 55455
| | - Florentin R Nitu
- From the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis Minnesota 55455
| | - David Rohde
- the Center for Molecular and Translational Cardiology, Department of Internal Medicine III, University of Heidelberg, INF 410, 69120, Heidelberg, Germany, and
| | - Patrick Most
- the Center for Molecular and Translational Cardiology, Department of Internal Medicine III, University of Heidelberg, INF 410, 69120, Heidelberg, Germany, and
| | - Donald M Bers
- the Department of Pharmacology, University of California, Davis, California 95616
| | - David D Thomas
- From the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis Minnesota 55455
| | - Razvan L Cornea
- From the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis Minnesota 55455,
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20
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Yuchi Z, Yuen SMWK, Lau K, Underhill AQ, Cornea RL, Fessenden JD, Van Petegem F. Crystal structures of ryanodine receptor SPRY1 and tandem-repeat domains reveal a critical FKBP12 binding determinant. Nat Commun 2015; 6:7947. [PMID: 26245150 PMCID: PMC4530471 DOI: 10.1038/ncomms8947] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 06/30/2015] [Indexed: 12/22/2022] Open
Abstract
Ryanodine receptors (RyRs) form calcium release channels located in the membranes of the sarcoplasmic and endoplasmic reticulum. RyRs play a major role in excitation-contraction coupling and other Ca2+-dependent signalling events, and consist of several globular domains that together form a large assembly. Here we describe the crystal structures of the SPRY1 and tandem-repeat domains at 1.2–1.5 Å resolution, which reveal several structural elements not detected in recent cryo-EM reconstructions of RyRs. The cryo-EM studies disagree on the position of SPRY domains, which had been proposed based on homology modelling. Computational docking of the crystal structures, combined with FRET studies, show that the SPRY1 domain is located next to FK506-binding protein (FKBP). Molecular dynamics flexible fitting and mutagenesis experiments suggest a hydrophobic cluster within SPRY1 that is crucial for FKBP binding. A RyR1 disease mutation, N760D, appears to directly impact FKBP binding through interfering with SPRY1 folding. The ryanodine receptor (RyR) is a large multi-domain ion channel that functions to release calcium from the endoplasmic or sarcoplasmic reticulum. Here the authors present crystal structures of the SPRY1 and tandem repeat domains of RyR, allowing precise positioning of the domains and linking disease mutations to RyR function.
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Affiliation(s)
- Zhiguang Yuchi
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - Siobhan M Wong King Yuen
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - Kelvin Lau
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - Ainsley Q Underhill
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, Minnesota 55455, USA
| | - James D Fessenden
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, Massachusetts 02115, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The Life Sciences Centre, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
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21
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Tatulian SA. Molecular-scale GPS: positioning a biosensor peptide on RyR. Biophys J 2015; 107:2003-5. [PMID: 25418085 DOI: 10.1016/j.bpj.2014.09.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/06/2014] [Accepted: 09/19/2014] [Indexed: 10/24/2022] Open
Affiliation(s)
- Suren A Tatulian
- Department of Physics, University of Central Florida, Orlando, Florida.
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22
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FRET-based trilateration of probes bound within functional ryanodine receptors. Biophys J 2015; 107:2037-48. [PMID: 25418089 DOI: 10.1016/j.bpj.2014.09.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/08/2014] [Accepted: 09/19/2014] [Indexed: 02/05/2023] Open
Abstract
To locate the biosensor peptide DPc10 bound to ryanodine receptor (RyR) Ca(2+) channels, we developed an approach that combines fluorescence resonance energy transfer (FRET), simulated-annealing, cryo-electron microscopy, and crystallographic data. DPc10 is identical to the 2460-2495 segment within the cardiac muscle RyR isoform (RyR2) central domain. DPc10 binding to RyR2 results in a pathologically elevated Ca(2+) leak by destabilizing key interactions between the RyR2 N-terminal and central domains (unzipping). To localize the DPc10 binding site within RyR2, we measured FRET between five single-cysteine variants of the FK506-binding protein (FKBP) labeled with a donor probe, and DPc10 labeled with an acceptor probe (A-DPc10). Effective donor positions were calculated from simulated-annealing constrained by both the RyR cryo-EM map and the FKBP atomic structure docked to the RyR. FRET to A-DPc10 was measured in permeabilized cardiomyocytes via confocal microscopy, converted to distances, and used to trilaterate the acceptor locus within RyR. Additional FRET measurements between donor-labeled calmodulin and A-DPc10 were used to constrain the trilaterations. Results locate the DPc10 probe within RyR domain 3, ?35 Å from the previously docked N-terminal domain crystal structure. This multiscale approach may be useful in mapping other RyR sites of mechanistic interest within FRET range of FKBP.
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Oxidation of ryanodine receptor (RyR) and calmodulin enhance Ca release and pathologically alter, RyR structure and calmodulin affinity. J Mol Cell Cardiol 2015; 85:240-8. [PMID: 26092277 DOI: 10.1016/j.yjmcc.2015.06.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 05/12/2015] [Accepted: 06/12/2015] [Indexed: 11/21/2022]
Abstract
Oxidative stress may contribute to cardiac ryanodine receptor (RyR2) dysfunction in heart failure (HF) and arrhythmias. Altered RyR2 domain-domain interaction (domain unzipping) and calmodulin (CaM) binding affinity are allosterically coupled indices of RyR2 conformation. In HF RyR2 exhibits reduced CaM binding, increased domain unzipping and greater SR Ca leak, and dantrolene can reverse these changes. However, effects of oxidative stress on RyR2 conformation and leak in myocytes are poorly understood. We used fluorescent CaM, FKBP12.6, and domain-peptide biosensor (F-DPc10) to measure, directly in cardiac myocytes, (1) RyR2 activation by hydrogen peroxide (H2O2)-induced oxidation, (2) RyR2 conformation change caused by oxidation, (3) CaM-RyR2 and FK506-binding protein (FKBP12.6)-RyR2 interaction upon oxidation, and (4) whether dantrolene affects 1-3. H2O2 was used to mimic oxidative stress. H2O2 significantly increased the frequency of Ca(2+) sparks and spontaneous Ca(2+) waves, and dantrolene almost completely blocked these effects. H2O2 pretreatment significantly reduced CaM-RyR2 binding, but had no effect on FKBP12.6-RyR2 binding. Dantrolene restored CaM-RyR2 binding but had no effect on intracellular and RyR2 oxidation levels. H2O2 also accelerated F-DPc10-RyR2 association while dantrolene slowed it. Thus, H2O2 causes conformational changes (sensed by CaM and DPc10 binding) associated with Ca leak, and dantrolene reverses these RyR2 effects. In conclusion, in cardiomyocytes, H2O2 treatment markedly reduces the CaM-RyR2 affinity, has no effect on FKBP12.6-RyR2 affinity, and causes domain unzipping. Dantrolene can correct domain unzipping, restore CaM-RyR2 affinity, and quiet pathological RyR2 channel gating. F-DPc10 and CaM are useful biosensors of a pathophysiological RyR2 state.
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Mahalingam M, Fessenden JD. Methods for labeling skeletal muscle ion channels site-specifically with fluorophores suitable for FRET-based structural analysis. Methods Enzymol 2015; 556:455-74. [PMID: 25857795 DOI: 10.1016/bs.mie.2014.11.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Skeletal muscle excitation-contraction coupling is triggered by the concerted action of two enormous Ca(2+) channel complexes, the dihydropyridine receptor and the type 1 ryanodine receptor. Recent advances in our understanding of the structure of these large Ca(2+) channels have been driven by fluorescence resonance energy transfer (FRET)-based analysis. A methodological challenge in conducting these FRET measurements is the ability to site-specifically label these huge ion channels with donor and acceptor fluorophores capable of undergoing energy transfer. In this chapter, we detail specific protocols for tagging large membrane proteins with these fluorescent probes using three orthogonal labeling methods: fluorescent protein fusions, biarsenical reagents directed to engineered tetracysteine tags, and Cy3/5 nitrilotriacetic acid conjugates that bind to poly-histidine tags.
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Affiliation(s)
- Mohana Mahalingam
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - James D Fessenden
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.
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Venturi E, Galfré E, O'Brien F, Pitt SJ, Bellamy S, Sessions RB, Sitsapesan R. FKBP12.6 activates RyR1: investigating the amino acid residues critical for channel modulation. Biophys J 2014; 106:824-33. [PMID: 24559985 PMCID: PMC3945099 DOI: 10.1016/j.bpj.2013.12.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 11/25/2013] [Accepted: 12/19/2013] [Indexed: 02/02/2023] Open
Abstract
We have previously shown that FKBP12 associates with RyR2 in cardiac muscle and that it modulates RyR2 function differently to FKBP12.6. We now investigate how these proteins affect the single-channel behavior of RyR1 derived from rabbit skeletal muscle. Our results show that FKBP12.6 activates and FKBP12 inhibits RyR1. It is likely that both proteins compete for the same binding sites on RyR1 because channels that are preactivated by FKBP12.6 cannot be subsequently inhibited by FKBP12. We produced a mutant FKBP12 molecule (FKBP12E31Q/D32N/W59F) where the residues Glu(31), Asp(32), and Trp(59) were converted to the corresponding residues in FKBP12.6. With respect to the functional regulation of RyR1 and RyR2, the FKBP12E31Q/D32N/W59F mutant lost all ability to behave like FKBP12 and instead behaved like FKBP12.6. FKBP12E31Q/D32N/W59F activated RyR1 but was not capable of activating RyR2. In conclusion, FKBP12.6 activates RyR1, whereas FKBP12 activates RyR2 and this selective activator phenotype is determined within the amino acid residues Glu(31), Asp(32), and Trp(59) in FKBP12 and Gln(31), Asn(32), and Phe(59) in FKBP12.6. The opposing but different effects of FKBP12 and FKBP12.6 on RyR1 and RyR2 channel gating provide scope for diversity of regulation in different tissues.
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Affiliation(s)
- Elisa Venturi
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Elena Galfré
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Fiona O'Brien
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Samantha J Pitt
- School of Medicine, University of St. Andrews, St. Andrew, United Kingdom
| | - Stuart Bellamy
- Centre for Nanoscience and Quantum Information (NSQI), University of Bristol, Bristol, United Kingdom
| | | | - Rebecca Sitsapesan
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
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Mahalingam M, Girgenrath T, Svensson B, Thomas DD, Cornea RL, Fessenden JD. Structural mapping of divergent regions in the type 1 ryanodine receptor using fluorescence resonance energy transfer. Structure 2014; 22:1322-1332. [PMID: 25132084 DOI: 10.1016/j.str.2014.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 06/26/2014] [Accepted: 07/13/2014] [Indexed: 12/16/2022]
Abstract
Ryanodine receptors (RyRs) release Ca(2+) to initiate striated muscle contraction. Three highly divergent regions (DRs) in the RyR protein sequence (DR1, DR2, and DR3) may confer isoform-specific functional properties to the RyRs. We used cell-based fluorescence resonance energy transfer (FRET) measurements to localize these DRs to the cryoelectron microscopic (cryo-EM) map of the skeletal muscle RyR isoform (RyR1). FRET donors were targeted to RyR1 using five different FKBP12.6 variants labeled with Alexa Fluor 488. FRET was then measured to the FRET acceptors, Cy3NTA or Cy5NTA, targeted to decahistidine tags introduced within the DRs. DR2 and DR3 were localized to separate positions within the "clamp" region of the RyR1 cryo-EM map, which is presumed to interface with Cav1.1. DR1 was localized to the "handle" region, near the regulatory calmodulin-binding site on the RyR. These localizations provide insights into the roles of DRs in RyR allosteric regulation during excitation contraction coupling.
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Affiliation(s)
- Mohana Mahalingam
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Tanya Girgenrath
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - James D Fessenden
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Fessenden JD, Mahalingam M. Site-specific labeling of the type 1 ryanodine receptor using biarsenical fluorophores targeted to engineered tetracysteine motifs. PLoS One 2013; 8:e64686. [PMID: 23724080 PMCID: PMC3665623 DOI: 10.1371/journal.pone.0064686] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/16/2013] [Indexed: 12/02/2022] Open
Abstract
The type 1 ryanodine receptor (RyR1) is an intracellular Ca2+ release channel that mediates skeletal muscle excitation contraction coupling. While the overall shape of RyR1 has been elucidated using cryo electron microscopic reconstructions, fine structural details remain elusive. To better understand the structure of RyR1, we have previously used a cell-based fluorescence resonance energy transfer (FRET) method using a fused green fluorescent protein (GFP) donor and a fluorescent acceptor, Cy3NTA that binds specifically to short poly-histidine ‘tags’ engineered into RyR1. However, the need to permeabilize cells to allow Cy3NTA entry as well as the noncovalent binding of Cy3NTA to the His tag limits future applications of this technique for studying conformational changes of the RyR. To overcome these problems, we used a dodecapeptide sequence containing a tetracysteine (Tc) motif to target the biarsenical fluorophores, FlAsH and ReAsH to RyR1. These compounds freely cross intact cell membranes where they then bind covalently to the tetracysteine motif. First, we used this system to conduct FRET measurements in intact cells by fusing a yellow fluorescent protein (YFP) FRET donor to the N-terminus of RyR1 and then targeting the FRET acceptor, ReAsH to an adjacent Tc tag. Moderate energy transfer (∼33%) was observed whereas ReAsH incubation of a YFPRyR1 fusion protein lacking the Tc tag resulted in no detectable FRET. We also developed a FRET-based system that did not require RyR fluorescent protein fusions by labeling N-terminal Tc-tagged RyR1 with FlAsH, a FRET donor and then targeting the FRET acceptor Cy3NTA to an adjacent decahistidine (His10) tag. A high degree of energy transfer (∼66%) indicated proper binding of both compounds to these unique recognition sequences in RyR1. Thus, these two systems should provide unprecedented flexibility in future FRET-based structural determinations of RyR1.
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Affiliation(s)
- James D Fessenden
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America.
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Girgenrath T, Mahalingam M, Svensson B, Nitu FR, Cornea RL, Fessenden JD. N-terminal and central segments of the type 1 ryanodine receptor mediate its interaction with FK506-binding proteins. J Biol Chem 2013; 288:16073-84. [PMID: 23585572 DOI: 10.1074/jbc.m113.463299] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We used site-directed labeling of the type 1 ryanodine receptor (RyR1) and fluorescence resonance energy transfer (FRET) measurements to map RyR1 sequence elements forming the binding site of the 12-kDa binding protein for the immunosuppressant drug, FK506. This protein, FKBP12, promotes the RyR1 closed state, thereby inhibiting Ca(2+) leakage in resting muscle. Although FKBP12 function is well established, its binding determinants within the RyR1 protein sequence remain unresolved. To identify these sequence determinants using FRET, we created five single-Cys FKBP variants labeled with Alexa Fluor 488 (denoted D-FKBP) and then targeted these D-FKBPs to full-length RyR1 constructs containing decahistidine (His10) "tags" placed within N-terminal (amino acid residues 76-619) or central (residues 2157-2777) regions of RyR1. The FRET acceptor Cy3NTA bound specifically and saturably to these His tags, allowing distance analysis of FRET measured from each D-FKBP variant to Cy3NTA bound to each His tag. Results indicate that D-FKBP binds proximal to both N-terminal and central domains of RyR1, thus suggesting that the FKBP binding site is composed of determinants from both regions. These findings further imply that the RyR1 N-terminal and central domains are proximal to one another, a core premise of the domain-switch hypothesis of RyR function. We observed FRET from GFP fused at position 620 within the N-terminal domain to central domain His-tagged sites, thus further supporting this hypothesis. Taken together, these results support the conclusion that N-terminal and central domain elements are closely apposed near the FKBP binding site within the RyR1 three-dimensional structure.
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Affiliation(s)
- Tanya Girgenrath
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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FK506 binding proteins: Cellular regulators of intracellular Ca2+ signalling. Eur J Pharmacol 2013; 700:181-93. [DOI: 10.1016/j.ejphar.2012.12.029] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 12/04/2012] [Accepted: 12/18/2012] [Indexed: 02/04/2023]
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Oda T, Yang Y, Nitu FR, Svensson B, Lu X, Fruen BR, Cornea RL, Bers DM. In cardiomyocytes, binding of unzipping peptide activates ryanodine receptor 2 and reciprocally inhibits calmodulin binding. Circ Res 2012; 112:487-97. [PMID: 23233753 DOI: 10.1161/circresaha.111.300290] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE One hypothesis for elevated Ca(2+) leak through cardiac ryanodine receptors (ryanodine receptor 2 [RyR2]) in heart failure is interdomain unzipping that can enhance aberrant channel activation. A peptide (domain peptide corresponding to RyR2 residues 2460-2495 [DPc10]) corresponding to RyR2 central domain residues 2460-2495 recapitulates this arrhythmogenic RyR2 leakiness by unzipping N-terminal and central domains. Calmodulin (CaM) and FK506-binding protein (FKBP12.6) bind to RyR2 and stabilize the closed channel. Little is known about DPc10 binding to the RyR2 and how that may interact with binding (and effects) of CaM and FKBP12.6 to RyR2. OBJECTIVE To measure, directly in cardiac myocytes, the kinetics and binding affinity of DPc10 to RyR2 and how that affects RyR2 interaction with FKBP12.6 and CaM. METHODS AND RESULTS We used permeabilized rat ventricular myocytes and fluorescently labeled DPc10, FKBP12.6, and CaM. DPc10 access to its binding site is extremely slow in resting RyR2 but is accelerated by promoting RyR opening or unzipping (by unlabeled DPc10). RyR2-bound CaM (but not FKBP12.6) drastically slowed DPc10 binding. Conversely, DPc10 binding significantly reduced CaM (but not FKBP12.6) binding to the RyR2. Fluorescence resonance energy transfer measurements indicate that DPc10-binding and CaM-binding sites are separate and allow triangulation of the structural DPc10 binding locus on RyR2 vs FKBP12.6-binding and CaM-binding sites. CONCLUSIONS DPc10-RyR2 binding is sterically limited by the resting zipped RyR2 state. CaM binding to RyR2 stabilizes this zipped state, whereas RyR2 activation or prebound DPc10 enhances DPc10 access. DPc10-binding and CaM-binding sites are distinct but are allosterically interacting RyR2 sites. Neither DPc10 nor FKBP12.6 influences RyR2 binding of the other.
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Affiliation(s)
- Tetsuro Oda
- Department of Pharmacology, University of California, Davis, CA 95616, USA
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31
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Mapping domains and mutations on the skeletal muscle ryanodine receptor channel. Trends Mol Med 2012; 18:644-57. [DOI: 10.1016/j.molmed.2012.09.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 08/14/2012] [Accepted: 09/19/2012] [Indexed: 11/20/2022]
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Abstract
Ryanodine receptors (RyRs) are huge ion channels that are responsible for the release of Ca(2+) from the sarco/endoplasmic reticulum. RyRs form homotetramers with a mushroom-like shape, consisting of a large cytoplasmic head and transmembrane stalk. Ca(2+) is a major physiological ligand that triggers opening of RyRs, but a plethora of modulatory proteins and small molecules in the cytoplasm and sarco/endoplasmic reticulum lumen have been recognized. Over 300 mutations in RyRs are associated with severe skeletal muscle disorders or triggered cardiac arrhythmias. With the advent of high-resolution structures of individual domains, many of these can be mapped onto the three-dimensional structure.
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Affiliation(s)
- Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver V6T 1Z3, Canada.
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33
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Wen H, Kang S, Song Y, Song Y, Yang HJ, Kim MH, Park S. Characterization of the binding sites for the interactions between FKBP12 and intracellular calcium release channels. Arch Biochem Biophys 2012; 517:37-42. [DOI: 10.1016/j.abb.2011.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 11/02/2011] [Accepted: 11/02/2011] [Indexed: 11/30/2022]
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Loura LMS, Prieto M. FRET in Membrane Biophysics: An Overview. Front Physiol 2011; 2:82. [PMID: 22110442 PMCID: PMC3216123 DOI: 10.3389/fphys.2011.00082] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 10/26/2011] [Indexed: 12/31/2022] Open
Abstract
Förster resonance energy transfer (FRET), in most applications used as a “spectroscopic ruler,” allows an easy determination of the donor-acceptor intermolecular distance. However, the situation becomes complex in membranes, since around each donor there is an ensemble of acceptors at non-correlated distances. In this review, state-of-the-art methodologies for this situation are presented, usually involving time-resolved data and model fitting. This powerful approach can be used to study the occurrence of phase separation (“rafts” or other type of domains), allowing their detection as well as size evaluation. Formalisms for studying lipid–protein and protein–protein interactions according to specific topologies are also addressed. The advantages and added complexity of a specific type of FRET (energy homotransfer or energy migration) are described, as well as applications of FRET under the microscope.
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Affiliation(s)
- Luís M S Loura
- Faculdade de Farmácia, Universidade de Coimbra Coimbra, Portugal
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35
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Guo T, Fruen BR, Nitu FR, Nguyen TD, Yang Y, Cornea RL, Bers DM. FRET detection of calmodulin binding to the cardiac RyR2 calcium release channel. Biophys J 2011; 101:2170-7. [PMID: 22067155 DOI: 10.1016/j.bpj.2011.09.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 09/07/2011] [Accepted: 09/22/2011] [Indexed: 12/13/2022] Open
Abstract
Calmodulin (CaM) binding to the type 2 ryanodine receptor (RyR2) regulates Ca release from the cardiac sarcoplasmic reticulum (SR). However, the structural basis of CaM regulation of the RyR2 is poorly defined, and the presence of other potential CaM binding partners in cardiac myocytes complicates resolution of CaM's regulatory interactions with RyR2. Here, we show that a fluorescence-resonance-energy-transfer (FRET)-based approach can effectively resolve RyR2 CaM binding, both in isolated SR membrane vesicles and in permeabilized ventricular myocytes. A small FRET donor was targeted to the RyR2 cytoplasmic assembly via fluorescent labeling of the FKBP12.6 subunit. Acceptor fluorophore was attached at discrete positions within either the N- or the C-lobe of CaM. FRET between FKBP12.6 and CaM bound to SR vesicles indicated CaM binding at a single high-affinity site within 60 Å of FKBP12.6. Micromolar Ca increased the apparent affinity of CaM binding and slowed CaM dissociation, but did not significantly affect maximal FRET efficiency at saturating CaM. FRET was strongest when the acceptor was attached at either of two positions within CaM's N-lobe versus sites in CaM's C-lobe, providing CaM orientation information. In permeabilized ventricular myocytes, FKBP12.6 and CaM colocalized to Z-lines, and the efficiency of energy transfer to both the N- and C-lobes of CaM was comparable to that observed in SR vesicle experiments. Results also indicate that both the location and orientation of CaM binding on the RyR2 are very similar to the skeletal muscle RyR1 isoform. Specific binding of CaM to functional RyR2 channels in the cardiac myocyte environment can be monitored using FKBP biosensors and FRET.
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Affiliation(s)
- Tao Guo
- Department of Pharmacology, University of California, Davis, California, USA
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36
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FK506 ameliorates cell death features in Huntington's disease striatal cell models. Neurochem Int 2011; 59:600-9. [PMID: 21703318 DOI: 10.1016/j.neuint.2011.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 03/17/2011] [Accepted: 04/18/2011] [Indexed: 11/23/2022]
Abstract
Huntington's disease (HD) is a genetic neurodegenerative disorder characterized by striatal neurodegeneration, involving apoptosis. FK506, an inhibitor of calcineurin (or protein phosphatase 3, formerly known as protein phosphatase 2B), has shown neuroprotective effects in several cellular and animal models of HD. In the present study, we show the protective effects of FK506 in two striatal HD models, primary rat striatal neurons treated with 3-nitropropionic acid (3-NP) and immortalized striatal STHdh cells derived from HD knock-in mice expressing normal (STHdh(7/7)) or full-length mutant huntingtin (FL-mHtt) with 111 glutamines (STHdh(111/111)), under basal conditions and after exposure to 3-NP or staurosporine (STS). In rat striatal neurons, FK506 abolished 3-NP-induced increase in caspase-3 activation, DNA fragmentation/condensation and necrosis. Nevertheless, in STHdh(111/111) cells under basal conditions, FK506 did not prevent, in a significant manner, the release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria, or alter Bax/Bcl-2 ratio, but significantly reverted caspase-3 activation. In STHdh(111/111) cells treated with 0.3mM 3-NP or 25 nM STS, linked to high necrosis, exposure to FK506 exerted no significant effects on caspase-3 activation. However, treatment of STHdh(111/111) cells exposed to 10nM STS with FK506 effectively prevented cell death by apoptosis and moderate necrosis. The results suggest that FK506 may be neuroprotective against apoptosis and necrosis under mild cell death stimulus in the presence of FLmHtt.
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Capes EM, Loaiza R, Valdivia HH. Ryanodine receptors. Skelet Muscle 2011; 1:18. [PMID: 21798098 PMCID: PMC3156641 DOI: 10.1186/2044-5040-1-18] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 05/04/2011] [Indexed: 12/31/2022] Open
Abstract
Excitation-contraction coupling involves the faithful conversion of electrical stimuli to mechanical shortening in striated muscle cells, enabled by the ubiquitous second messenger, calcium. Crucial to this process are ryanodine receptors (RyRs), the sentinels of massive intracellular calcium stores contained within the sarcoplasmic reticulum. In response to sarcolemmal depolarization, RyRs release calcium into the cytosol, facilitating mobilization of the myofilaments and enabling cell contraction. In order for the cells to relax, calcium must be rapidly resequestered or extruded from the cytosol. The sustainability of this cycle is crucially dependent upon precise regulation of RyRs by numerous cytosolic metabolites and by proteins within the lumen of the sarcoplasmic reticulum and those directly associated with the receptors in a macromolecular complex. In addition to providing the majority of the calcium necessary for contraction of cardiac and skeletal muscle, RyRs act as molecular switchboards that integrate a multitude of cytosolic signals such as dynamic and steady calcium fluctuations, β-adrenergic stimulation (phosphorylation), nitrosylation and metabolic states, and transduce these signals to the channel pore to release appropriate amounts of calcium. Indeed, dysregulation of calcium release via RyRs is associated with life-threatening diseases in both skeletal and cardiac muscle. In this paper, we briefly review some of the most outstanding structural and functional attributes of RyRs and their mechanism of regulation. Further, we address pathogenic RyR dysfunction implicated in cardiovascular disease and skeletal myopathies.
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Affiliation(s)
- E Michelle Capes
- Department of Cellular and Regenerative Biology, University of Wisconsin Medical School, Madison, WI 53711, USA.
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Wang R, Zhong X, Meng X, Koop A, Tian X, Jones PP, Fruen BR, Wagenknecht T, Liu Z, Chen SRW. Localization of the dantrolene-binding sequence near the FK506-binding protein-binding site in the three-dimensional structure of the ryanodine receptor. J Biol Chem 2011; 286:12202-12. [PMID: 21262961 DOI: 10.1074/jbc.m110.194316] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dantrolene is believed to stabilize interdomain interactions between the NH2-terminal and central regions of ryanodine receptors by binding to the NH2-terminal residues 590-609 in skeletal ryanodine receptor (RyR1) and residues 601-620 in cardiac ryanodine receptor (RyR2). To gain further insight into the structural basis of dantrolene action, we have attempted to localize the dantrolene-binding sequence in RyR1/RyR2 by using GFP as a structural marker and three-dimensional cryo-EM. We inserted GFP into RyR2 after residues Arg-626 and Tyr-846 to generate GFP-RyR2 fusion proteins, RyR2Arg-626-GFP and RyR2Tyr-846-GFP. Insertion of GFP after residue Arg-626 abolished the binding of a bulky GST- or cyan fluorescent protein-tagged FKBP12.6 but not the binding of a smaller, nontagged FKBP12.6, suggesting that residue Arg-626 and the dantrolene-binding sequence are located near the FKBP12.6-binding site. Using cryo-EM, we have mapped the three-dimensional location of Tyr-846-GFP to domain 9, which is also adjacent to the FKBP12.6-binding site. To further map the three-dimensional location of the dantrolene-binding sequence, we generated 10 FRET pairs based on four known three-dimensional locations (FKBP12.6, Ser-437-GFP, Tyr-846-GFP, and Ser-2367-GFP). Based on the FRET efficiencies of these FRET pairs and the corresponding distance relationships, we mapped the three-dimensional location of Arg-626-GFP or -cyan fluorescent protein, hence the dantrolene-binding sequence, to domain 9 near the FKBP12.6-binding site but distant to the central region around residue Ser-2367. An allosteric mechanism by which dantrolene stabilizes interdomain interactions between the NH2-terminal and central regions is proposed.
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Affiliation(s)
- Ruiwu Wang
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Lanner JT, Georgiou DK, Joshi AD, Hamilton SL. Ryanodine receptors: structure, expression, molecular details, and function in calcium release. Cold Spring Harb Perspect Biol 2010; 2:a003996. [PMID: 20961976 DOI: 10.1101/cshperspect.a003996] [Citation(s) in RCA: 546] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ryanodine receptors (RyRs) are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of Ca(2+) from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle. RyRs are the largest known ion channels (> 2MDa) and exist as three mammalian isoforms (RyR 1-3), all of which are homotetrameric proteins that interact with and are regulated by phosphorylation, redox modifications, and a variety of small proteins and ions. Most RyR channel modulators interact with the large cytoplasmic domain whereas the carboxy-terminal portion of the protein forms the ion-conducting pore. Mutations in RyR2 are associated with human disorders such as catecholaminergic polymorphic ventricular tachycardia whereas mutations in RyR1 underlie diseases such as central core disease and malignant hyperthermia. This chapter examines the current concepts of the structure, function and regulation of RyRs and assesses the current state of understanding of their roles in associated disorders.
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Affiliation(s)
- Johanna T Lanner
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, Houston, Texas 77030,USA
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Eltit JM, Feng W, Lopez JR, Padilla IT, Pessah IN, Molinski TF, Fruen BR, Allen PD, Perez CF. Ablation of skeletal muscle triadin impairs FKBP12/RyR1 channel interactions essential for maintaining resting cytoplasmic Ca2+. J Biol Chem 2010; 285:38453-62. [PMID: 20926377 DOI: 10.1074/jbc.m110.164525] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we have shown that lack of expression of triadins in skeletal muscle cells results in significant increase of myoplasmic resting free Ca(2+) ([Ca(2+)](rest)), suggesting a role for triadins in modulating global intracellular Ca(2+) homeostasis. To understand this mechanism, we study here how triadin alters [Ca(2+)](rest), Ca(2+) release, and Ca(2+) entry pathways using a combination of Ca(2+) microelectrodes, channels reconstituted in bilayer lipid membranes (BLM), Ca(2+), and Mn(2+) imaging analyses of myotubes and RyR1 channels obtained from triadin-null mice. Unlike WT cells, triadin-null myotubes had chronically elevated [Ca(2+)](rest) that was sensitive to inhibition with ryanodine, suggesting that triadin-null cells have increased basal RyR1 activity. Consistently, BLM studies indicate that, unlike WT-RyR1, triadin-null channels more frequently display atypical gating behavior with multiple and stable subconductance states. Accordingly, pulldown analysis and fluorescent FKBP12 binding studies in triadin-null muscles revealed a significant impairment of the FKBP12/RyR1 interaction. Mn(2+) quench rates under resting conditions indicate that triadin-null cells also have higher Ca(2+) entry rates and lower sarcoplasmic reticulum Ca(2+) load than WT cells. Overexpression of FKBP12.6 reverted the null phenotype, reducing resting Ca(2+) entry, recovering sarcoplasmic reticulum Ca(2+) content levels, and restoring near normal [Ca(2+)](rest). Exogenous FKBP12.6 also reduced the RyR1 channel P(o) but did not rescue subconductance behavior. In contrast, FKBP12 neither reduced P(o) nor recovered multiple subconductance gating. These data suggest that elevated [Ca(2+)](rest) in triadin-null myotubes is primarily driven by dysregulated RyR1 channel activity that results in part from impaired FKBP12/RyR1 functional interactions and a secondary increased Ca(2+) entry at rest.
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Affiliation(s)
- Jose M Eltit
- Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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