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Hua X, Yao J, Liu X, Liu Q, Deng Y, Li S, Valdivia CR, Wang F, Pozzolini M, Shou Z, Valdivia HH, Xiao L. Comparison of the structure-function of five newly members of the calcin family. Int J Biol Macromol 2024; 260:129424. [PMID: 38219929 DOI: 10.1016/j.ijbiomac.2024.129424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/03/2024] [Accepted: 01/09/2024] [Indexed: 01/16/2024]
Abstract
Calcins are a group of scorpion toxin peptides specifically binding to ryanodine receptors (RyRs) with high affinity, and have the ability to activate and stabilize RyR in a long-lasting subconductance state. Five newly calcins synthesized compounds exhibit typical structural characteristics of a specific family through chemical synthesis and virtual analysis. As the calcins from the same species, Petersiicalcin1 and Petersiicalcin2, Jendekicalcin2 and Jendekicalcin3, have only one residue difference. Both Petersiicalcin1 and Petersiicalcin2 exhibited different affinities in stimulating [3H]ryanodine binding, but the residue mutation resulted in a 2.7 folds difference. Other calcins also exhibited a stimulatory effect on [3H]ryanodine binding to RyR1, however, their affinities were significantly lower than that of Petersiiicalcin1 and Petersiiicalcin2. The channel domain of RyR1 was found to be capable of binding with the basic residues of these calcins, which also exhibited interactions with the S6 helices on RyR1. Dynamic simulations were conducted for Petersiicalcin1 and Petersiicalcin2, which demonstrated their ability to form a highly stable conformation and resulting in an asymmetric tetramer structure of RyR1. The discovery of five newly calcins further enriches the diversity of the natural calcin family, which provides more native peptides for the structure-function analysis between calcin and RyRs.
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Affiliation(s)
- Xiaoyu Hua
- Department of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical University), Shanghai 200433, China
| | - Jinchi Yao
- Department of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical University), Shanghai 200433, China; School of Life Sciences, Liaoning Normal University, Dalian 116081, China
| | - Xinyan Liu
- Department of Traditional Chinese Medicine Surgery, the First Affiliated Hospital of the Navy Medical University, Shanghai, 200433, China
| | - Qing Liu
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi, Taigu 030801, China
| | - Yuchen Deng
- Department of Dermatology, Second Affiliated Hospital of Naval Medical University, Shanghai 200003, China
| | - Songhua Li
- Department of Cardiology, Changhai Hospital, Naval Medical University, Shanghai, China
| | - Carmen R Valdivia
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
| | - Fei Wang
- Department of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical University), Shanghai 200433, China
| | - Marina Pozzolini
- Department of Earth, Environment and Life Sciences (DISTAV), University of Genova, Via Pastore 3, 16132 Genova, Italy.
| | - Zhaoyong Shou
- Faculty of Health Service, Nacal Medical University (Second Military Medical University), Shanghai 200433, China.
| | - Héctor H Valdivia
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
| | - Liang Xiao
- Department of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical University), Shanghai 200433, China.
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2
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Chirasani VR, Elferdink M, Kral M, Carter JS, Heitmann S, Meissner G, Yamaguchi N. Structural and functional interactions between the EF hand domain and S2-S3 loop in the type-1 ryanodine receptor ion channel. J Biol Chem 2024; 300:105606. [PMID: 38159862 PMCID: PMC10832476 DOI: 10.1016/j.jbc.2023.105606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 12/04/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024] Open
Abstract
Previous cryo-electron micrographs suggested that the skeletal muscle Ca2+ release channel, ryanodine receptor (RyR)1, is regulated by intricate interactions between the EF hand Ca2+ binding domain and the cytosolic loop (S2-S3 loop). However, the precise molecular details of these interactions and functional consequences of the interactions remain elusive. Here, we used molecular dynamics simulations to explore the specific amino acid pairs involved in hydrogen bond interactions within the EF hand-S2-S3 loop interface. Our simulations unveiled two key interactions: (1) K4101 (EF hand) with D4730 (S2-S3 loop) and (2) E4075, Q4078, and D4079 (EF hand) with R4736 (S2-S3 loop). To probe the functional significance of these interactions, we constructed mutant RyR1 complementary DNAs and expressed them in HEK293 cells for [3H]ryanodine binding assays. Our results demonstrated that mutations in the EF hand, specifically K4101E and K4101M, resulted in reduced affinities for Ca2+/Mg2+-dependent inhibitions. Interestingly, the K4101E mutation increased the affinity for Ca2+-dependent activation. Conversely, mutations in the S2-S3 loop, D4730K and D4730N, did not significantly change the affinities for Ca2+/Mg2+-dependent inhibitions. Our previous finding that skeletal disease-associated RyR1 mutations, R4736Q and R4736W, impaired Ca2+-dependent inhibition, is consistent with the current results. In silico mutagenesis analysis aligned with our functional data, indicating altered hydrogen bonding patterns upon mutations. Taken together, our findings emphasize the critical role of the EF hand-S2-S3 loop interaction in Ca2+/Mg2+-dependent inhibition of RyR1 and provide insights into potential therapeutic strategies targeting this domain interaction for the treatment of skeletal myopathies.
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Affiliation(s)
- Venkat R Chirasani
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; R.L. Juliano Structural Bioinformatics Core, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Millar Elferdink
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA; College of Charleston Honors College, Charleston, South Carolina, USA
| | - MacKenzie Kral
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA; College of Charleston Honors College, Charleston, South Carolina, USA
| | - Jordan S Carter
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA
| | - Savannah Heitmann
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Naohiro Yamaguchi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA; Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina and Clemson University, Charleston, South Carolina, USA.
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3
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Yao J, Hua X, Huo W, Xiao L, Wang Y, Tang Q, Valdivia CR, Valdivia HH, Dong W, Xiao L. The Effect of Acidic Residues on the Binding between Opicalcin1 and Ryanodine Receptor from the Structure-Functional Analysis. J Nat Prod 2024; 87:104-112. [PMID: 38128916 PMCID: PMC10825818 DOI: 10.1021/acs.jnatprod.3c00821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 11/26/2023] [Accepted: 11/26/2023] [Indexed: 12/23/2023]
Abstract
Calcin is a group ligand with high affinity and specificity for the ryanodine receptors (RyRs). Little is known about the effect of its acidic residues on the spacial structure as well as the interaction with RyRs. We screened the opicalcin1 acidic mutants and investigated the effect of mutation on activity. The results indicated that all acidic mutants maintained the structural features, but their surface charge distribution underwent significant changes. Molecular docking and dynamics simulations were used to analyze the interaction between opicalcin1 mutants and RyRs, which demonstrated that all opicalcin1 mutants effectively bound to the channel domain of RyR1. This stable binding induced a pronounced asymmetry in the structure of the RyR tetramer, exhibiting a high degree of structural dissimilarity. [3H]Ryanodine binding to RyR1 was enhanced in D2A and D15A, which was similar to opicalcin1, but that effect was suppressed in E12A and E29A and reversed for the DE-4A, thereby inhibiting ryanodine binding. Opicalcin1 and DE-4A also exhibited the ability to form stable docking structures with RyR2. Acidic residues play a crucial role in the structure of calcin and its functional interaction with RyRs that is beneficial for the calcin optimization to develop more active peptide lead compounds for RyR-related diseases.
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Affiliation(s)
- Jinchi Yao
- School
of Life Sciences, Liaoning Normal University, Dalian116081, China
- Department
of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical
University), Shanghai 200433, China
| | - Xiaoyu Hua
- Department
of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical
University), Shanghai 200433, China
| | - Wenjing Huo
- The
305 Hospital of PLA, Beijing 100017, China
| | - Li Xiao
- Department
of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53188, United States
- Department
of Forensic Toxicological Analysis, West China School of Basic Medical
Sciences and Forensic Medicine, Sichuan
University, Chengdu 610017, China
| | - Yongfang Wang
- Department
of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical
University), Shanghai 200433, China
| | - Qinglong Tang
- Central
Medical District of Chinese, PLA General Hospital, Beijing 100120, China
| | - Carmen R. Valdivia
- Department
of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53188, United States
| | - Héctor H. Valdivia
- Department
of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53188, United States
| | - Weibing Dong
- School
of Life Sciences, Liaoning Normal University, Dalian116081, China
| | - Liang Xiao
- Department
of Occupational and Environmental Health, Faculty of Naval Medicine, Naval Medical University (Second Military Medical
University), Shanghai 200433, China
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Torres R, Hidalgo C. Subcellular localization and transcriptional regulation of brain ryanodine receptors. Functional implications. Cell Calcium 2023; 116:102821. [PMID: 37949035 DOI: 10.1016/j.ceca.2023.102821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/16/2023] [Accepted: 11/03/2023] [Indexed: 11/12/2023]
Abstract
Ryanodine receptors (RyR) are intracellular Ca2+ channels localized in the endoplasmic reticulum, where they act as critical mediators of Ca2+-induced Ca2+ calcium release (CICR). In the brain, mammals express in both neurons, and non-neuronal cells, a combination of the three RyR-isoforms (RyR1-3). Pharmacological approaches, which do not distinguish between isoforms, have indicated that RyR-isoforms contribute to brain function. However, isoform-specific manipulations have revealed that RyR-isoforms display different subcellular localizations and are differentially associated with neuronal function. These findings raise the need to understand RyR-isoform specific transcriptional regulation, as this knowledge will help to elucidate the causes of neuronal dysfunction for a growing list of brain disorders that show altered RyR channel expression and function.
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Affiliation(s)
- Rodrigo Torres
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Lago Panguipulli 1390, 5501842, Puerto Montt, Chile.
| | - Cecilia Hidalgo
- Department of Neurosciences. Biomedical Neuroscience Institute, Physiology and Biophysics Program, Institute of Biomedical Sciences, Center for Exercise, Metabolism and Cancer Studies, Faculty of Medicine, Universidad de Chile, Santiago, 8380000, Chile
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5
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Chen X, Chen J, Liu S, Li X. Everolimus-induced hyperpermeability of endothelial cells causes lung injury. Exp Biol Med (Maywood) 2023; 248:2440-2448. [PMID: 38158699 PMCID: PMC10903245 DOI: 10.1177/15353702231220672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/06/2023] [Indexed: 01/03/2024] Open
Abstract
The mammalian target of rapamycin (mTOR) inhibitors, everolimus (but not dactolisib), is frequently associated with lung injury in clinical therapies. However, the underlying mechanisms remain unclear. Endothelial cell barrier dysfunction plays a major role in the pathogenesis of the lung injury. This study hypothesizes that everolimus increases pulmonary endothelial permeability, which leads to lung injury. We tested the effects of everolimus on human pulmonary microvascular endothelial cell (HPMEC) permeability and a mouse model of intraperitoneal injection of everolimus was established to investigate the effect of everolimus on pulmonary vascular permeability. Our data showed that everolimus increased human pulmonary microvascular endothelial cell (HPMEC) permeability which was associated with MLC phosphorylation and F-actin stress fiber formation. Furthermore, everolimus induced an increasing concentration of intracellular calcium Ca2+ leakage in HPMECs and this was normalized with ryanodine pretreatment. In addition, ryanodine decreased everolimus-induced phosphorylation of PKCα and MLC, and barrier disruption in HPMECs. Consistent with in vitro data, everolimus treatment caused a visible lung-vascular barrier dysfunction, including an increase in protein in BALF and lung capillary-endothelial permeability, which was significantly attenuated by pretreatment with an inhibitor of PKCα, MLCK, and ryanodine. This study shows that everolimus induced pulmonary endothelial hyper-permeability, at least partly, in an MLC phosphorylation-mediated EC contraction which is influenced in a Ca2+-dependent manner and can lead to lung injury through mTOR-independent mechanisms.
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Affiliation(s)
- Xiaolin Chen
- Department of Clinical Laboratory, Pingxiang People's Hospital, Pingxiang 337000, China
- Department of Clinical Laboratory, The Sixth Clinical College of Gannan Medical University, Pingxiang 337000, China
| | - Jianhui Chen
- Department of Clinical Laboratory, Pingxiang People's Hospital, Pingxiang 337000, China
| | - Shuihong Liu
- Department of Clinical Laboratory, Pingxiang People's Hospital, Pingxiang 337000, China
| | - Xianfan Li
- Department of Clinical Laboratory, Pingxiang People's Hospital, Pingxiang 337000, China
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6
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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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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7
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Postić S, Sarikas S, Pfabe J, Pohorec V, Križančić Bombek L, Sluga N, Skelin Klemen M, Dolenšek J, Korošak D, Stožer A, Evans-Molina C, Johnson JD, Slak Rupnik M. High-resolution analysis of the cytosolic Ca 2+ events in β cell collectives in situ. Am J Physiol Endocrinol Metab 2023; 324:E42-E55. [PMID: 36449570 PMCID: PMC9829482 DOI: 10.1152/ajpendo.00165.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/15/2022] [Accepted: 11/22/2022] [Indexed: 12/02/2022]
Abstract
The release of peptide hormones is predominantly regulated by a transient increase in cytosolic Ca2+ concentration ([Ca2+]c). To trigger exocytosis, Ca2+ ions enter the cytosol from intracellular Ca2+ stores or from the extracellular space. The molecular events of late stages of exocytosis, and their dependence on [Ca2+]c, were extensively described in isolated single cells from various endocrine glands. Notably, less work has been done on endocrine cells in situ to address the heterogeneity of [Ca2+]c events contributing to a collective functional response of a gland. For this, β cell collectives in a pancreatic islet are particularly well suited as they are the smallest, experimentally manageable functional unit, where [Ca2+]c dynamics can be simultaneously assessed on both cellular and collective level. Here, we measured [Ca2+]c transients across all relevant timescales, from a subsecond to a minute time range, using high-resolution imaging with a low-affinity Ca2+ sensor. We quantified the recordings with a novel computational framework for automatic image segmentation and [Ca2+]c event identification. Our results demonstrate that under physiological conditions the duration of [Ca2+]c events is variable, and segregated into three reproducible modes, subsecond, second, and tens of seconds time range, and are a result of a progressive temporal summation of the shortest events. Using pharmacological tools we show that activation of intracellular Ca2+ receptors is both sufficient and necessary for glucose-dependent [Ca2+]c oscillations in β cell collectives, and that a subset of [Ca2+]c events could be triggered even in the absence of Ca2+ influx across the plasma membrane. In aggregate, our experimental and analytical platform was able to readily address the involvement of intracellular Ca2+ receptors in shaping the heterogeneity of [Ca2+]c responses in collectives of endocrine cells in situ.NEW & NOTEWORTHY Physiological glucose or ryanodine stimulation of β cell collectives generates a large number of [Ca2+]c events, which can be rapidly assessed with our newly developed automatic image segmentation and [Ca2+]c event identification pipeline. The event durations segregate into three reproducible modes produced by a progressive temporal summation. Using pharmacological tools, we show that activation of ryanodine intracellular Ca2+ receptors is both sufficient and necessary for glucose-dependent [Ca2+]c oscillations in β cell collectives.
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Affiliation(s)
- Sandra Postić
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Srdjan Sarikas
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Johannes Pfabe
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Nastja Sluga
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Dean Korošak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Carmella Evans-Molina
- Center for Diabetes and Metabolic Diseases and the Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
| | - James D Johnson
- Diabetes Research Group, Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marjan Slak Rupnik
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
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8
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Abstract
Flecainide, a cardiac class 1C blocker of the surface membrane sodium channel (NaV1.5), has also been reported to reduce cardiac ryanodine receptor (RyR2)-mediated sarcoplasmic reticulum (SR) Ca2+ release. It has been introduced as a clinical antiarrhythmic agent for catecholaminergic polymorphic ventricular tachycardia (CPVT), a condition most commonly associated with gain-of-function RyR2 mutations. Current debate concerns both cellular mechanisms of its antiarrhythmic action and molecular mechanisms of its RyR2 actions. At the cellular level, it targets NaV1.5, RyR2, Na+/Ca2+ exchange (NCX), and additional proteins involved in excitation-contraction (EC) coupling and potentially contribute to the CPVT phenotype. This Viewpoint primarily addresses the various direct molecular actions of flecainide on isolated RyR2 channels in artificial lipid bilayers. Such studies demonstrate different, multifarious, flecainide binding sites on RyR2, with voltage-dependent binding in the channel pore or voltage-independent binding at distant peripheral sites. In contrast to its single NaV1.5 pore binding site, flecainide may bind to at least four separate inhibitory sites on RyR2 and one activation site. None of these binding sites have been specifically located in the linear RyR2 sequence or high-resolution structure. Furthermore, it is not clear which of the inhibitory sites contribute to flecainide's reduction of spontaneous Ca2+ release in cellular studies. A confounding observation is that flecainide binding to voltage-dependent inhibition sites reduces cation fluxes in a direction opposite to physiological Ca2+ flow from SR lumen to cytosol. This may suggest that, rather than directly blocking Ca2+ efflux, flecainide can reduce Ca2+ efflux by blocking counter currents through the pore which otherwise limit SR membrane potential change during systolic Ca2+ efflux. In summary, the antiarrhythmic effects of flecainide in CPVT seem to involve multiple components of EC coupling and multiple actions on RyR2. Their clarification may identify novel specific drug targets and facilitate flecainide's clinical utilization in CPVT.
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Affiliation(s)
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - James A. Fraser
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Angela F. Dulhunty
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Acton, Australia
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9
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Guo W, Wei J, Estillore JP, Zhang L, Wang R, Sun B, Chen SRW. RyR2 disease mutations at the C-terminal domain intersubunit interface alter closed-state stability and channel activation. J Biol Chem 2021; 297:100808. [PMID: 34022226 PMCID: PMC8214192 DOI: 10.1016/j.jbc.2021.100808] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 11/19/2022] Open
Abstract
Ryanodine receptors (RyRs) are ion channels that mediate the release of Ca2+ from the sarcoplasmic reticulum/endoplasmic reticulum, mutations of which are implicated in a number of human diseases. The adjacent C-terminal domains (CTDs) of cardiac RyR (RyR2) interact with each other to form a ring-like tetrameric structure with the intersubunit interface undergoing dynamic changes during channel gating. This mobile CTD intersubunit interface harbors many disease-associated mutations. However, the mechanisms of action of these mutations and the role of CTD in channel function are not well understood. Here, we assessed the impact of CTD disease-associated mutations P4902S, P4902L, E4950K, and G4955E on Ca2+− and caffeine-mediated activation of RyR2. The G4955E mutation dramatically increased both the Ca2+-independent basal activity and Ca2+-dependent activation of [3H]ryanodine binding to RyR2. The P4902S and E4950K mutations also increased Ca2+ activation but had no effect on the basal activity of RyR2. All four disease mutations increased caffeine-mediated activation of RyR2 and reduced the threshold for activation and termination of spontaneous Ca2+ release. G4955D dramatically increased the basal activity of RyR2, whereas G4955K mutation markedly suppressed channel activity. Similarly, substitution of P4902 with a negatively charged residue (P4902D), but not a positively charged residue (P4902K), also dramatically increased the basal activity of RyR2. These data suggest that electrostatic interactions are involved in stabilizing the CTD intersubunit interface and that the G4955E disease mutation disrupts this interface, and thus the stability of the closed state. Our studies shed new insights into the mechanisms of action of RyR2 CTD disease mutations.
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Affiliation(s)
- Wenting Guo
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Jinhong Wei
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - John Paul Estillore
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Lin Zhang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Ruiwu Wang
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Bo Sun
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Medical School, Kunming University of Science and Technology, Kunming, China.
| | - S R Wayne Chen
- Libin Cardiovascular Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada.
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10
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Marques F, Thapliyal S, Javer A, Shrestha P, Brown AEX, Glauser DA. Tissue-specific isoforms of the single C. elegans Ryanodine receptor gene unc-68 control specific functions. PLoS Genet 2020; 16:e1009102. [PMID: 33104696 PMCID: PMC7644089 DOI: 10.1371/journal.pgen.1009102] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 11/05/2020] [Accepted: 09/08/2020] [Indexed: 11/18/2022] Open
Abstract
Ryanodine receptors (RyR) are essential regulators of cellular calcium homeostasis and signaling. Vertebrate genomes contain multiple RyR gene isoforms, expressed in different tissues and executing different functions. In contrast, invertebrate genomes contain a single RyR-encoding gene and it has long been proposed that different transcripts generated by alternative splicing may diversify their functions. Here, we analyze the expression and function of alternative exons in the C. elegans RyR gene unc-68. We show that specific isoform subsets are created via alternative promoters and via alternative splicing in unc-68 Divergent Region 2 (DR2), which actually corresponds to a region of high sequence variability across vertebrate isoforms. The expression of specific unc-68 alternative exons is enriched in different tissues, such as in body wall muscle, neurons and pharyngeal muscle. In order to infer the function of specific alternative promoters and alternative exons of unc-68, we selectively deleted them by CRISPR/Cas9 genome editing. We evaluated pharyngeal function, as well as locomotor function in swimming and crawling with high-content computer-assisted postural and behavioral analysis. Our data provide a comprehensive map of the pleiotropic impact of isoform-specific mutations and highlight that tissue-specific unc-68 isoforms fulfill distinct functions. As a whole, our work clarifies how the C. elegans single RyR gene unc-68 can fulfill multiple tasks through tissue-specific isoforms, and provide a solid foundation to further develop C. elegans as a model to study RyR channel functions and malfunctions. The use of alternative exons allows a vast diversification of the isoform sequences encoded by single genes. The functional study of gene product isoforms in vivo using classical genetic approaches is challenging, notably because different isoforms may work in a partially redundant manner for many of their functions. Logically, research has progressed more rapidly in discovering the function of whole genes than that of specific isoforms. Using C. elegans model, we take advantage here of the recent development of efficient genome editing techniques to create alternative exon-specific molecular lesions and infer their specific roles in vivo by using a large set of phenotypic measures. We applied this approach to elucidate the role of alternative exons in the Ryanodine receptor (RyR) gene unc-68, which encodes the largest ion channel reported so far. Our results have implications for the understanding of the functional diversity of RyR channels across phyla and send an encouraging signal for the future application of genome editing to elucidate the functions of alternative exons in C. elegans.
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Affiliation(s)
- Filipe Marques
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Saurabh Thapliyal
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Avelino Javer
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Priyanka Shrestha
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - André E. X. Brown
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
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11
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Abstract
The core myopathies are a group of congenital myopathies with variable clinical expression - ranging from early-onset skeletal-muscle weakness to later-onset disease of variable severity - that are identified by characteristic 'core-like' lesions in myofibers and the presence of hypothonia and slowly or rather non-progressive muscle weakness. The genetic causes are diverse; central core disease is most often caused by mutations in ryanodine receptor 1 (RYR1), whereas multi-minicore disease is linked to pathogenic variants of several genes, including selenoprotein N (SELENON), RYR1 and titin (TTN). Understanding the mechanisms that drive core development and muscle weakness remains challenging due to the diversity of the excitation-contraction coupling (ECC) proteins involved and the differential effects of mutations across proteins. Because of this, the use of representative models expressing a mature ECC apparatus is crucial. Animal models have facilitated the identification of disease progression mechanisms for some mutations and have provided evidence to help explain genotype-phenotype correlations. However, many unanswered questions remain about the common and divergent pathological mechanisms that drive disease progression, and these mechanisms need to be understood in order to identify therapeutic targets. Several new transgenic animals have been described recently, expanding the spectrum of core myopathy models, including mice with patient-specific mutations. Furthermore, recent developments in 3D tissue engineering are expected to enable the study of core myopathy disease progression and the effects of potential therapeutic interventions in the context of human cells. In this Review, we summarize the current landscape of core myopathy models, and assess the hurdles and opportunities of future modeling strategies.
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Affiliation(s)
- Aurora Fusto
- Department of Neuroscience, University of Padua, Padua 35128, Italy
| | - Louise A Moyle
- Donnelly Centre, University of Toronto, Toronto, ON M5S3E1, Canada
- Institute of Biomaterials and Biochemical Engineering, University of Toronto, Toronto, ON M5S3G9, Canada
| | - Penney M Gilbert
- Donnelly Centre, University of Toronto, Toronto, ON M5S3E1, Canada
- Institute of Biomaterials and Biochemical Engineering, University of Toronto, Toronto, ON M5S3G9, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S3G5, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S1A8, Canada
| | - Elena Pegoraro
- Department of Neuroscience, University of Padua, Padua 35128, Italy
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12
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Yuan GR, Wang KY, Mou X, Luo RY, Dou W, Wang JJ. Molecular cloning, mRNA expression and alternative splicing of a ryanodine receptor gene from the citrus whitefly, Dialeurodes citri (Ashmead). Pestic Biochem Physiol 2017; 142:59-66. [PMID: 29107248 DOI: 10.1016/j.pestbp.2017.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/07/2016] [Accepted: 01/04/2017] [Indexed: 06/07/2023]
Abstract
Insect ryanodine receptors are the main targets of diamide insecticides that have highly selective insecticidal activity but are less toxic to mammals. Therefore, these insecticides are ideal for pest control. Ryanodine receptors (RyRs) play a critical role in Ca2+ signaling in muscle and non-muscle cells. In this study, we cloned the complete cDNA (DcRyR) of the RyR from the citrus whitefly, Dialeurodes citri, a serious pest of citrus orchards in China. The open reading frame of RyR is 15,378bp long and encodes a protein with 5126 amino acids with a computed molecular weight of 579.523kDa. DcRyR shows a high amino acid sequence identity to RyRs from other insects (76%-95%) and low identity to those from nematodes and mammals (44%-52%). DcRyR shares many features of insect and vertebrate RyRs, including a MIR domain, two RIH domains, three SPRY domains, four copies of RyR repeat domain, RIH-associated domain at the N-terminus, two consensus calcium-binding EF-hands and six transmembrane domains at the C-terminus. The expression of DcRyR mRNA was the highest in the nymphs and lowest in eggs; DcRyR mRNA was 1.85-fold higher in the nymphs than in the eggs. Among the tissues, DcRyR mRNA expression was 4.18- and 4.02-fold higher in the adult head and thorax than in the abdomen. DcRyR had three alternative splice sites and the splice variants showed body part-specific expression and were developmentally regulated. These results may help investigate target-based resistance to diamide insecticides in D. citri.
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Affiliation(s)
- Guo-Rui Yuan
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China
| | - Ke-Yi Wang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China
| | - Xing Mou
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China
| | - Ruo-Yu Luo
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China
| | - Wei Dou
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China
| | - Jin-Jun Wang
- Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400716, China.
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13
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Wescott AP, Jafri MS, Lederer WJ, Williams GSB. Ryanodine receptor sensitivity governs the stability and synchrony of local calcium release during cardiac excitation-contraction coupling. J Mol Cell Cardiol 2016; 92:82-92. [PMID: 26827896 PMCID: PMC4807626 DOI: 10.1016/j.yjmcc.2016.01.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 01/13/2016] [Accepted: 01/27/2016] [Indexed: 11/27/2022]
Abstract
Calcium-induced calcium release is the principal mechanism that triggers the cell-wide [Ca(2+)]i transient that activates muscle contraction during cardiac excitation-contraction coupling (ECC). Here, we characterize this process in mouse cardiac myocytes with a novel mathematical action potential (AP) model that incorporates realistic stochastic gating of voltage-dependent L-type calcium (Ca(2+)) channels (LCCs) and sarcoplasmic reticulum (SR) Ca(2+) release channels (the ryanodine receptors, RyR2s). Depolarization of the sarcolemma during an AP stochastically activates the LCCs elevating subspace [Ca(2+)] within each of the cell's 20,000 independent calcium release units (CRUs) to trigger local RyR2 opening and initiate Ca(2+) sparks, the fundamental unit of triggered Ca(2+) release. Synchronization of Ca(2+) sparks during systole depends on the nearly uniform cellular activation of LCCs and the likelihood of local LCC openings triggering local Ca(2+) sparks (ECC fidelity). The detailed design and true SR Ca(2+) pump/leak balance displayed by our model permits investigation of ECC fidelity and Ca(2+) spark fidelity, the balance between visible (Ca(2+) spark) and invisible (Ca(2+) quark/sub-spark) SR Ca(2+) release events. Excess SR Ca(2+) leak is examined as a disease mechanism in the context of "catecholaminergic polymorphic ventricular tachycardia (CPVT)", a Ca(2+)-dependent arrhythmia. We find that that RyR2s (and therefore Ca(2+) sparks) are relatively insensitive to LCC openings across a wide range of membrane potentials; and that key differences exist between Ca(2+) sparks evoked during quiescence, diastole, and systole. The enhanced RyR2 [Ca(2+)]i sensitivity during CPVT leads to increased Ca(2+) spark fidelity resulting in asynchronous systolic Ca(2+) spark activity. It also produces increased diastolic SR Ca(2+) leak with some prolonged Ca(2+) sparks that at times become "metastable" and fail to efficiently terminate. There is a huge margin of safety for stable Ca(2+) handling within the cell and this novel mechanistic model provides insight into the molecular signaling characteristics that help maintain overall Ca(2+) stability even under the conditions of high SR Ca(2+) leak during CPVT. Finally, this model should provide tools for investigators to examine normal and pathological Ca(2+) signaling characteristics in the heart.
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Affiliation(s)
- Andrew P Wescott
- Center for Biomedical Engineering and Technology & Department of Physiology, University of Maryland, Baltimore, Baltimore, MD, United States
| | - M Saleet Jafri
- Center for Biomedical Engineering and Technology & Department of Physiology, University of Maryland, Baltimore, Baltimore, MD, United States; Molecular Neuroscience Department, George Mason University, Fairfax, VA, United States
| | - W J Lederer
- Center for Biomedical Engineering and Technology & Department of Physiology, University of Maryland, Baltimore, Baltimore, MD, United States
| | - George S B Williams
- Center for Biomedical Engineering and Technology & Department of Physiology, University of Maryland, Baltimore, Baltimore, MD, United States.
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14
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Xiao Z, Guo W, Yuen SMWK, Wang R, Zhang L, Van Petegem F, Chen SRW. The H29D Mutation Does Not Enhance Cytosolic Ca2+ Activation of the Cardiac Ryanodine Receptor. PLoS One 2015; 10:e0139058. [PMID: 26405799 PMCID: PMC4583508 DOI: 10.1371/journal.pone.0139058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/07/2015] [Indexed: 11/25/2022] Open
Abstract
The N-terminal domain of the cardiac ryanodine receptor (RyR2) harbors a large number of naturally occurring mutations that are associated with stress-induced ventricular tachyarrhythmia and sudden death. Nearly all these disease-associated N-terminal mutations are located at domain interfaces or buried within domains. Mutations at these locations would alter domain-domain interactions or the stability/folding of domains. Recently, a novel RyR2 mutation H29D associated with ventricular arrhythmia at rest was found to enhance the activation of single RyR2 channels by diastolic levels of cytosolic Ca2+. Unlike other N-terminal disease-associated mutations, the H29D mutation is located on the surface of the N-terminal domain. It is unclear how this surface-exposed H29D mutation that does not appear to interact with other parts of the RyR2 structure could alter the intrinsic properties of the channel. Here we carried out detailed functional characterization of the RyR2-H29D mutant at the molecular and cellular levels. We found that the H29D mutation has no effect on the basal level or the Ca2+ dependent activation of [3H]ryanodine binding to RyR2, the cytosolic Ca2+ activation of single RyR2 channels, or the cytosolic Ca2+- or caffeine-induced Ca2+ release in HEK293 cells. In addition, the H29D mutation does not alter the propensity for spontaneous Ca2+ release or the thresholds for Ca2+ release activation or termination. Furthermore, the H29D mutation does not have significant impact on the thermal stability of the N-terminal region (residues 1–547) of RyR2. Collectively, our data show that the H29D mutation exerts little or no effect on the function of RyR2 or on the folding stability of the N-terminal region. Thus, our results provide no evidence that the H29D mutation enhances the cytosolic Ca2+ activation of RyR2.
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Affiliation(s)
- Zhichao Xiao
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Wenting Guo
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Siobhan M. Wong King Yuen
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - Ruiwu Wang
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Lin Zhang
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada V6T 1Z3
| | - S. R. Wayne Chen
- Libin Cardiovascular Institute of Alberta, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- Libin Cardiovascular Institute of Alberta, Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Alberta, Canada T2N 4N1
- * E-mail:
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15
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Zyryanova T, Schneider R, Adams V, Sittig D, Kerner C, Gebhardt C, Ruffert H, Glasmacher S, Hepp P, Punkt K, Neuhaus J, Hamann J, Aust G. Skeletal muscle expression of the adhesion-GPCR CD97: CD97 deletion induces an abnormal structure of the sarcoplasmatic reticulum but does not impair skeletal muscle function. PLoS One 2014; 9:e100513. [PMID: 24949957 PMCID: PMC4065095 DOI: 10.1371/journal.pone.0100513] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/24/2014] [Indexed: 01/09/2023] Open
Abstract
CD97 is a widely expressed adhesion class G-protein-coupled receptor (aGPCR). Here, we investigated the presence of CD97 in normal and malignant human skeletal muscle as well as the ultrastructural and functional consequences of CD97 deficiency in mice. In normal human skeletal muscle, CD97 was expressed at the peripheral sarcolemma of all myofibers, as revealed by immunostaining of tissue sections and surface labeling of single myocytes using flow cytometry. In muscle cross-sections, an intracellular polygonal, honeycomb-like CD97-staining pattern, typical for molecules located in the T-tubule or sarcoplasmatic reticulum (SR), was additionally found. CD97 co-localized with SR Ca2+-ATPase (SERCA), a constituent of the longitudinal SR, but not with the receptors for dihydropyridine (DHPR) or ryanodine (RYR), located in the T-tubule and terminal SR, respectively. Intracellular expression of CD97 was higher in slow-twitch compared to most fast-twitch myofibers. In rhabdomyosarcomas, CD97 was strongly upregulated and in part more N-glycosylated compared to normal skeletal muscle. All tumors were strongly CD97-positive, independent of the underlying histological subtype, suggesting high sensitivity of CD97 for this tumor. Ultrastructural analysis of murine skeletal myofibers confirmed the location of CD97 in the SR. CD97 knock-out mice had a dilated SR, resulting in a partial increase in triad diameter yet not affecting the T-tubule, sarcomeric, and mitochondrial structure. Despite these obvious ultrastructural changes, intracellular Ca2+ release from single myofibers, force generation and fatigability of isolated soleus muscles, and wheel-running capacity of mice were not affected by the lack of CD97. We conclude that CD97 is located in the SR and at the peripheral sarcolemma of human and murine skeletal muscle, where its absence affects the structure of the SR without impairing skeletal muscle function.
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Affiliation(s)
- Tatiana Zyryanova
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Rick Schneider
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Volker Adams
- Heart Center Leipzig, University of Leipzig, Leipzig, Germany
| | - Doreen Sittig
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Christiane Kerner
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Claudia Gebhardt
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Henrik Ruffert
- Department of Anaesthesiology and Intensive Care Medicine, University of Leipzig, Leipzig, Germany
| | - Stefan Glasmacher
- Clinic for Trauma and Reconstructive Surgery, University of Leipzig, Leipzig, Germany
| | - Pierre Hepp
- Clinic for Trauma and Reconstructive Surgery, University of Leipzig, Leipzig, Germany
| | - Karla Punkt
- Institute of Anatomy, University of Leipzig, Leipzig, Germany
| | - Jochen Neuhaus
- Clinic of Urology, Research Laboratories, University of Leipzig, Leipzig, Germany
| | - Jörg Hamann
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Gabriela Aust
- Department of Surgery, Research Laboratories, University of Leipzig, Leipzig, Germany
- * E-mail:
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16
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Mei Y, Xu L, Kramer HF, Tomberlin GH, Townsend C, Meissner G. Stabilization of the skeletal muscle ryanodine receptor ion channel-FKBP12 complex by the 1,4-benzothiazepine derivative S107. PLoS One 2013; 8:e54208. [PMID: 23349825 PMCID: PMC3547879 DOI: 10.1371/journal.pone.0054208] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 12/10/2012] [Indexed: 12/12/2022] Open
Abstract
Activation of the skeletal muscle ryanodine receptor (RyR1) complex results in the rapid release of Ca2+ from the sarcoplasmic reticulum and muscle contraction. Dissociation of the small FK506 binding protein 12 subunit (FKBP12) increases RyR1 activity and impairs muscle function. The 1,4-benzothiazepine derivative JTV519, and the more specific derivative S107 (2,3,4,5,-tetrahydro-7-methoxy-4-methyl-1,4-benzothiazepine), are thought to improve skeletal muscle function by stabilizing the RyR1-FKBP12 complex. Here, we report a high degree of nonspecific and specific low affinity [3H]S107 binding to SR vesicles. SR vesicles enriched in RyR1 bound ∼48 [3H]S107 per RyR1 tetramer with EC50 ∼52 µM and Hillslope ∼2. The effects of S107 and FKBP12 on RyR1 were examined under conditions that altered the redox state of RyR1. S107 increased FKBP12 binding to RyR1 in SR vesicles in the presence of reduced glutathione and the NO-donor NOC12, with no effect in the presence of oxidized glutathione. Addition of 0.15 µM FKBP12 to SR vesicles prevented FKBP12 dissociation; however, in the presence of oxidized glutathione and NOC12, FKBP12 dissociation was observed in skeletal muscle homogenates that contained 0.43 µM myoplasmic FKBP12 and was attenuated by S107. In single channel measurements with FKBP12-depleted RyR1s, in the absence and presence of NOC12, S107 augmented the FKBP12-mediated decrease in channel activity. The data suggest that S107 can reverse the harmful effects of redox active species on SR Ca2+ release in skeletal muscle by binding to RyR1 low affinity sites.
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Affiliation(s)
- Yingwu Mei
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Le Xu
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Henning F. Kramer
- GlaxoSmithKline Research and Development, Research Triangle Park, North Carolina, United States of America
| | - Ginger H. Tomberlin
- GlaxoSmithKline Research and Development, Research Triangle Park, North Carolina, United States of America
| | - Claire Townsend
- GlaxoSmithKline Research and Development, Research Triangle Park, North Carolina, United States of America
| | - Gerhard Meissner
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
- * E-mail:
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17
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Kipanyula MJ, Contreras L, Zampese E, Lazzari C, Wong AKC, Pizzo P, Fasolato C, Pozzan T. Ca2+ dysregulation in neurons from transgenic mice expressing mutant presenilin 2. Aging Cell 2012; 11:885-93. [PMID: 22805202 DOI: 10.1111/j.1474-9726.2012.00858.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Mutations in amyloid precursor protein (APP), and presenilin-1 and presenilin-2 (PS1 and PS2) have causally been implicated in Familial Alzheimer's Disease (FAD), but the mechanistic link between the mutations and the early onset of neurodegeneration is still debated. Although no consensus has yet been reached, most data suggest that both FAD-linked PS mutants and endogenous PSs are involved in cellular Ca2+ homeostasis. We here investigated subcellular Ca2+ handling in primary neuronal cultures and acute brain slices from wild type and transgenic mice carrying the FAD-linked PS2-N141I mutation, either alone or in the presence of the APP Swedish mutation. Compared with wild type, both types of transgenic neurons show a similar reduction in endoplasmic reticulum (ER) Ca2+ content and decreased response to metabotropic agonists, albeit increased Ca2+ release induced by caffeine. In both transgenic neurons, we also observed a higher ER-mitochondria juxtaposition that favors increased mitochondrial Ca2+ uptake upon ER Ca2+ release. A model is described that integrates into a unifying hypothesis the contradictory effects on Ca2+ homeostasis of different PS mutations and points to the relevance of these findings in neurodegeneration and aging.
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González A, Cabrera MDLÁ, Henríquez MJ, Contreras RA, Morales B, Moenne A. Cross talk among calcium, hydrogen peroxide, and nitric oxide and activation of gene expression involving calmodulins and calcium-dependent protein kinases in Ulva compressa exposed to copper excess. Plant Physiol 2012; 158:1451-62. [PMID: 22234999 PMCID: PMC3291273 DOI: 10.1104/pp.111.191759] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
To analyze the copper-induced cross talk among calcium, nitric oxide (NO), and hydrogen peroxide (H(2)O(2)) and the calcium-dependent activation of gene expression, the marine alga Ulva compressa was treated with the inhibitors of calcium channels, ned-19, ryanodine, and xestospongin C, of chloroplasts and mitochondrial electron transport chains, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and antimycin A, of pyruvate dehydrogenase, moniliformin, of calmodulins, N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide, and of calcium-dependent protein kinases, staurosporine, as well as with the scavengers of NO, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and of H(2)O(2), ascorbate, and exposed to a sublethal concentration of copper (10 μm) for 24 h. The level of NO increased at 2 and 12 h. The first peak was inhibited by ned-19 and 3-(2,3-dichlorophenyl)-1,1-dimethylurea and the second peak by ned-19 and antimycin A, indicating that NO synthesis is dependent on calcium release and occurs in organelles. The level of H(2)O(2) increased at 2, 3, and 12 h and was inhibited by ned-19, ryanodine, xestospongin C, and moniliformin, indicating that H(2)O(2) accumulation is dependent on calcium release and Krebs cycle activity. In addition, pyruvate dehydrogenase, 2-oxoxglutarate dehydrogenase, and isocitrate dehydrogenase activities of the Krebs cycle increased at 2, 3, 12, and/or 14 h, and these increases were inhibited in vitro by EGTA, a calcium chelating agent. Calcium release at 2, 3, and 12 h was inhibited by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and ascorbate, indicating activation by NO and H(2)O(2). In addition, the level of antioxidant protein gene transcripts decreased with N-(6-aminohexyl)-5-chloro-1-naphtalene sulfonamide and staurosporine. Thus, there is a copper-induced cross talk among calcium, H(2)O(2), and NO and a calcium-dependent activation of gene expression involving calmodulins and calcium-dependent protein kinases.
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Carter S, Pitt SJ, Colyer J, Sitsapesan R. Ca²+-dependent phosphorylation of RyR2 can uncouple channel gating from direct cytosolic Ca²+ regulation. J Membr Biol 2011; 240:21-33. [PMID: 21274522 PMCID: PMC3047053 DOI: 10.1007/s00232-011-9339-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 01/02/2011] [Indexed: 12/03/2022]
Abstract
Phosphorylation of the cardiac ryanodine receptor (RyR2) is thought to be important not only for normal cardiac excitation-contraction coupling but also in exacerbating abnormalities in Ca²+ homeostasis in heart failure. Linking phosphorylation to specific changes in the single-channel function of RyR2 has proved very difficult, yielding much controversy within the field. We therefore investigated the mechanistic changes that take place at the single-channel level after phosphorylating RyR2 and, in particular, the idea that PKA-dependent phosphorylation increases RyR2 sensitivity to cytosolic Ca²+. We show that hyperphosphorylation by exogenous PKA increases open probability (P(o)) but, crucially, RyR2 becomes uncoupled from the influence of cytosolic Ca²+; lowering [Ca²+] to subactivating levels no longer closes the channels. Phosphatase (PP1) treatment reverses these gating changes, returning the channels to a Ca²+-sensitive mode of gating. We additionally found that cytosolic incubation with Mg²+/ATP in the absence of exogenously added kinase could phosphorylate RyR2 in approximately 50% of channels, thereby indicating that an endogenous kinase incorporates into the bilayer together with RyR2. Channels activated by the endogenous kinase exhibited identical changes in gating behavior to those activated by exogenous PKA, including uncoupling from the influence of cytosolic Ca²+. We show that the endogenous kinase is both Ca²+-dependent and sensitive to inhibitors of PKC. Moreover, the Ca²+-dependent, endogenous kinase-induced changes in RyR2 gating do not appear to be related to phosphorylation of serine-2809. Further work is required to investigate the identity and physiological role of this Ca²+-dependent endogenous kinase that can uncouple RyR2 gating from direct cytosolic Ca²+ regulation.
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Affiliation(s)
- Simon Carter
- School of Physiology and Pharmacology and Centre for Nanoscience and Quantum Information, University of Bristol, Bristol, BS8 1TD UK
| | - Samantha J. Pitt
- School of Physiology and Pharmacology and Centre for Nanoscience and Quantum Information, University of Bristol, Bristol, BS8 1TD UK
| | - John Colyer
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Rebecca Sitsapesan
- School of Physiology and Pharmacology and Centre for Nanoscience and Quantum Information, University of Bristol, Bristol, BS8 1TD UK
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Abstract
Although normally absent, spontaneous pacemaker activity can develop in human atrium to promote tachyarrhythmias. HL-1 cells are immortalized atrial cardiomyocytes that contract spontaneously in culture, providing a model system of atrial cell automaticity. Using electrophysiologic recordings and selective pharmacologic blockers, we investigated the ionic basis of automaticity in atrial HL-1 cells. Both the sarcoplasmic reticulum Ca release channel inhibitor ryanodine and the sarcoplasmic reticulum Ca ATPase inhibitor thapsigargin slowed automaticity, supporting a role for intracellular Ca release in pacemaker activity. Additional experiments were performed to examine the effects of ionic currents activating in the voltage range of diastolic depolarization. Inhibition of the hyperpolarization-activated pacemaker current, If, by ivabradine significantly suppressed diastolic depolarization, with modest slowing of automaticity. Block of inward Na currents also reduced automaticity, whereas inhibition of T- and L-type Ca currents caused milder effects to slow beat rate. The major outward current in HL-1 cells is the rapidly activating delayed rectifier, IKr. Inhibition of IKr using dofetilide caused marked prolongation of action potential duration and thus spontaneous cycle length. These results demonstrate a mutual role for both intracellular Ca release and sarcolemmal ionic currents in controlling automaticity in atrial HL-1 cells. Given that similar internal and membrane-based mechanisms also play a role in sinoatrial nodal cell pacemaker activity, our findings provide evidence for generalized conservation of pacemaker mechanisms among different types of cardiomyocytes.
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Affiliation(s)
- Zhenjiang Yang
- Department of Medicine and Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-6602, USA
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21
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González A, Trebotich J, Vergara E, Medina C, Morales B, Moenne A. Copper-induced calcium release from ER involves the activation of ryanodine-sensitive and IP(3)-sensitive channels in Ulva compressa. Plant Signal Behav 2010; 5:1647-9. [PMID: 21139437 PMCID: PMC3115124 DOI: 10.4161/psb.5.12.13977] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The marine alga Ulva compressa (Chlorophyta) showed a triphasic release of intracellular calcium with maximal levels at 2, 3 and 12 h and a biphasic accumulation of intracellular hydrogen peroxide with peaks at 3 and 12 h when cultivated with copper excess. Intracellular hydrogen peroxide originated exclusively in organelles. In this work, we analyzed the intracellular origin of calcium release and the type of calcium channels activated in response to copper excess. U. compressa was treated with thapsigargin, an inhibitor of endoplasmic reticulum (ER) calcium ATPase, ryanodine, an inhibitor of ryanodine-sensitive channels, and xestospongin C, an inhibitor of inositol 1, 4, 5-triphosphate (IP(3))-sensitive channels. Thapsigargin induced the depletion of calcium stored in ER at 75 min and completely inhibited calcium release at 2, 3 and 12 h of copper exposure indicating that calcium release originated in ER. In addition, ryanodine and xestospogin C inhibited calcium release at 2 and 3 h of copper exposure whereas the peak at 12 h was only inhibited by ryanodine. Thus, copper induced the activation of ryanodine-sensitive and IP(3)-sensitive calcium channels in ER of U. compressa.
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Affiliation(s)
- Alberto González
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
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22
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Sigalas C, Mayo-Martin MB, Jane DE, Sitsapesan R. Ca2+-calmodulin increases RyR2 open probability yet reduces ryanoid association with RyR2. Biophys J 2009; 97:1907-16. [PMID: 19804721 DOI: 10.1016/j.bpj.2009.07.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 07/17/2009] [Accepted: 07/20/2009] [Indexed: 11/17/2022] Open
Abstract
We have shown that physiological levels of Ca(2+)-calmodulin (Ca(2+)CaM; 50-100 nM) activate cardiac ryanodine receptors (RyR2) incorporated into bilayers and increase the frequency of Ca(2+) sparks and waves in cardiac cells. In contrast, it is well known that Ca(2+)CaM inhibits [(3)H]ryanodine binding to cardiac sarcoplasmic reticulum. Since the [(3)H]ryanodine binding technique does not reflect the effects of Ca(2+)CaM on RyR2 open probability (Po), we have investigated, using the reversible ryanoid, ryanodol, whether Ca(2+)CaM can directly influence the binding of ryanoids to single RyR2 channels independently of Po. We demonstrate that Ca(2+)CaM reduces the rate of ryanodol association to RyR2 without affecting the rate of dissociation. We also find that ryanodol-bound channels fluctuate between at least two distinct subconductance states, M(1) and M(2), in a voltage-dependent manner. Ca(2+)CaM significantly alters the equilibrium between these two states. The results suggest that Ca(2+)CaM binding to RyR2 causes a conformation change to regions of the channel that include the ryanoid binding site, thereby leading to a decrease in ryanoid association rate and modulation of gating within the ryanoid/RyR2 bound state. Our data provide a possible explanation for why the effects of Ca(2+)CaM at the single-channel level are not mirrored by [(3)H]ryanodine binding studies.
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Affiliation(s)
- Charalambos Sigalas
- Department of Physiology and Pharmacology and Bristol Heart Institute, University of Bristol, Bristol, United Kingdom
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23
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Babai N, Morgans CW, Thoreson WB. Calcium-induced calcium release contributes to synaptic release from mouse rod photoreceptors. Neuroscience 2009; 165:1447-56. [PMID: 19932743 DOI: 10.1016/j.neuroscience.2009.11.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 11/03/2009] [Accepted: 11/12/2009] [Indexed: 11/18/2022]
Abstract
We tested whether calcium-induced calcium release (CICR) contributes to synaptic release from rods in mammalian retina. Electron micrographs and immunofluorescent double labeling for the sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA2) and synaptic ribbon protein, ribeye, showed a close association between ER and synaptic ribbons in mouse rod terminals. Stimulating CICR with 10 microM ryanodine evoked Ca(2+) increases in rod terminals from mouse retinal slices visualized using confocal microscopy with the Ca(2+)-sensitive dye, Fluo-4. Ryanodine also stimulated membrane depolarization of individual mouse rods. Inhibiting CICR with a high concentration of ryanodine (100 microM) reduced the electroretinogram (ERG) b-wave but not a-wave consistent with inhibition of synaptic transmission from rods. Ryanodine (100 microM) also inhibited light-evoked voltage responses of individual rod bipolar cells (RBCs) and presumptive horizontal cells recorded with perforated patch recording techniques. A presynaptic site of action for ryanodine's effects is further indicated by the finding that ryanodine (100 microM) did not alter currents evoked in voltage-clamped RBCs by puffing the mGluR6 antagonist, (RS)-alpha-cyclopropyl-4-phosphonophenylglycine (CPPG), onto bipolar cell dendrites in the presence of the mGluR6 agonist L-(+)-2-amino-4-phosphonobutyric acid (L-AP4). Ryanodine (100 microM) also inhibited glutamatergic outward currents in RBCs evoked by electrical stimulation of rods using electrodes placed in the outer segment layer. Together, these results indicate that, like amphibian retina, CICR contributes to synaptic release from mammalian (mouse) rods. By boosting synaptic release in darkness, CICR may improve the detection of small luminance changes by post-synaptic neurons.
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Affiliation(s)
- N Babai
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Hirose M, Stuyvers B, Dun W, Ter Keurs H, Boyden PA. Wide long lasting perinuclear Ca2+ release events generated by an interaction between ryanodine and IP3 receptors in canine Purkinje cells. J Mol Cell Cardiol 2008; 45:176-84. [PMID: 18586264 DOI: 10.1016/j.yjmcc.2008.05.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 05/01/2008] [Accepted: 05/07/2008] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to determine whether IP(3)Rs contribute to the generation of wide long lasting perinuclear Ca(2+) release events in canine Purkinje cells. Spontaneous Ca(2+) release events (elevations of basal [Ca(2+)] equivalent to F/F(0) 3.4SD over F(0)) were imaged using Fluo-4AM and 2D confocal microscope. Only cells free of Ca(2+) waves were analyzed. Subsarcolemmal region (SSL) was defined as 5 microm from cell edges. Core was the remaining cell. The majority of events (94%, 0.0035+/-0.0007 events (ev)/microm(2)/s, N=34 cells) were detected within a single frame (typical events, TE). However, a subpopulation (6.0%, 0.00022+/-0.00005 ev/microm(2)/s, N=41 cells: wide long lasting events, WLE) lasted for several frames, showed a greater spatial extent (51.0+/-3.9 vs. TE 9.0+/-0.3 microm(2), P<0.01) and higher amplitude (F/F(0) 1.38+/-0.02 vs. TE 1.20+/-0.003, P<0.01). WLE event rate was increased by phenylephrine (10 microM, P<0.01), inhibited by 2APB and U73122 (P<0.05), and abolished by tetracaine (1 mM) and ryanodine (100 microM). While SSL WLEs were scattered randomly, Core WLEs (n=69 events) were predominantly distributed longitudinally 18.2+/-1.6 microm from the center of nuclei. Immunocytochemistry showed that IP(3)R1s were located not only at SSL region but also near both ends of nucleus overlapping with RyRs. In Purkinje cells, wide long lasting Ca(2+) release events occur in SSL and in specific perinuclear regions. They are likely due to RyRs and IP(3)R1s evoked Ca(2+) release and may play a role in Ca(2+) dependent nuclear processes.
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Affiliation(s)
- Masanori Hirose
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York NY, USA
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25
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Morton-Jones RT, Cannell MB, Housley GD. Ca2+ entry via AMPA-type glutamate receptors triggers Ca2+-induced Ca2+ release from ryanodine receptors in rat spiral ganglion neurons. Cell Calcium 2008; 43:356-66. [PMID: 17719086 DOI: 10.1016/j.ceca.2007.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 06/05/2007] [Accepted: 07/06/2007] [Indexed: 11/25/2022]
Abstract
Ryanodine receptor (RyR)-gated Ca2+ stores have recently been identified in cochlear spiral ganglion neurons (SGN) and likely contribute to Ca2+ signalling associated with auditory neurotransmission. Here, we identify an ionotropic glutamate receptor signal transduction pathway which invokes RyR-gated Ca2+ stores in SGN via Ca2+-induced Ca2+ release (CICR). Ca2+ levels were recorded in SGN in situ within rat cochlear slices (postnatal day 0-17) using the Ca2+ indicator fluo-4. RyR-gated Ca2+ stores were confirmed by caffeine-induced increases in intracellular Ca2+ which were blocked by ryanodine (100 microM) and were independent of external Ca2+. Glutamate evoked comparable increases in intracellular Ca2+, but required the presence of external Ca2+. Ca2+ influx via the glutamate receptor was found to elicit CICR via RyR-gated Ca2+ stores, as shown by the inhibition of the response by prior depletion of the Ca2+ stores with caffeine, the SERCA inhibitor thapsigargin, or ryanodine. The glutamate analogue AMPA (alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid) elicited Ca2+ responses that could be inhibited by caffeine. Glutamate- and AMPA-mediated Ca2+ responses were eliminated with the AMPA/Kainate receptor antagonist DNQX (6,7-dinitroquinoxaline-2,3-dione). These data demonstrate functional coupling between somatic AMPA-type glutamate receptors and intracellular Ca(2+) stores via RyR-dependent CICR in primary auditory neurons.
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Affiliation(s)
- Rachel T Morton-Jones
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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26
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Ranatunga KM, Chen SRW, Ruest L, Welch W, Williams AJ. Quantification of the effects of a ryanodine receptor channel mutation on interaction with a ryanoid. Mol Membr Biol 2007; 24:185-93. [PMID: 17520475 DOI: 10.1080/09687860601076522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Understanding the nature of the interaction of the plant alkaloid ryanodine with its receptor channel (RyR) is important to aid interpretation of physiological studies and provide structure-function information about RyR. We present here the first quantitative description of the relative single-channel kinetic effects of a single-point mutation in RyR2. We exploit the well-characterized ryanoid 8beta-amino-9alpha-hydroxyryanodine that displays reversible kinetics with RyR2. We explicitly show that the effect of the Q4863A mutation is to increase the apparent dissociation constant by increasing the apparent dissociation rate of the ryanoid. The voltage-dependence of the interaction displays no change. We infer that Q4863 is not involved with the voltage-drop but is able to influence ryanoid-bound structural changes. We discuss structural mechanisms by which this mutation could affect ryanoid interaction.
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Affiliation(s)
- Kishani M Ranatunga
- Cardiac Medicine, National Heart and Lung Institute, Imperial College London, London, UK
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27
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Mabrouk K, Ram N, Boisseau S, Strappazzon F, Rehaim A, Sadoul R, Darbon H, Ronjat M, De Waard M. Critical amino acid residues of maurocalcine involved in pharmacology, lipid interaction and cell penetration. Biochimica et Biophysica Acta (BBA) - Biomembranes 2007; 1768:2528-40. [PMID: 17888395 DOI: 10.1016/j.bbamem.2007.06.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 06/05/2007] [Accepted: 06/07/2007] [Indexed: 11/22/2022]
Abstract
Maurocalcine (MCa) is a 33-amino acid residue peptide that was initially identified in the Tunisian scorpion Scorpio maurus palmatus. This peptide triggers interest for three main reasons. First, it helps unravelling the mechanistic basis of Ca(2+) mobilization from the sarcoplasmic reticulum because of its sequence homology with a calcium channel domain involved in excitation-contraction coupling. Second, it shows potent pharmacological properties because of its ability to activate the ryanodine receptor. Finally, it is of technological value because of its ability to carry cell-impermeable compounds across the plasma membrane. Herein, we characterized the molecular determinants that underlie the pharmacological and cell-penetrating properties of maurocalcine. We identify several key amino acid residues of the peptide that will help the design of cell-penetrating analogues devoid of pharmacological activity and cell toxicity. Close examination of the determinants underlying cell penetration of maurocalcine reveals that basic amino acid residues are required for an interaction with negatively charged lipids of the plasma membrane. Maurocalcine analogues that penetrate better have also stronger interaction with negatively charged lipids. Conversely, less effective analogues present a diminished ability to interact with these lipids. These findings will also help the design of still more potent cell penetrating analogues of maurocalcine.
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Affiliation(s)
- Kamel Mabrouk
- Laboratoire Chimie Biologie et Radicaux Libre, Universite Aix-Marseille, Avenue Escadrille Normandie Niemen, 13397 Marseille, France
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28
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Laver DR, Hamada T, Fessenden JD, Ikemoto N. The ryanodine receptor pore blocker neomycin also inhibits channel activity via a previously undescribed high-affinity Ca(2+) binding site. J Membr Biol 2007; 220:11-20. [PMID: 17879109 DOI: 10.1007/s00232-007-9067-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Accepted: 07/21/2007] [Indexed: 10/22/2022]
Abstract
In this study, we present evidence for the mechanism of neomycin inhibition of skeletal ryanodine receptors (RyRs). In single-channel recordings, neomycin produced monophasic inhibition of RyR open probability and biphasic inhibition of [(3)H]ryanodine binding. The half-maximal inhibitory concentration (IC(50)) for channel blockade by neomycin was dependent on membrane potential and cytoplasmic [Ca(2+)], suggesting that neomycin acts both as a pore plug and as a competitive antagonist at a cytoplasmic Ca(2+) binding site that causes allosteric inhibition. This novel Ca(2+)/neomycin binding site had a neomycin affinity of 100 nM: and a Ca(2+) affinity of 35 nM,: which is 30-fold higher than that of the well-described cytoplasmic Ca(2+) activation site. Therefore, a new high-affinity class of Ca(2+) binding site(s) on the RyR exists that mediates neomycin inhibition. Neomycin plugging of the channel pore induced brief (1-2 ms) conductance substates at 30% of the fully open conductance, whereas allosteric inhibition caused complete channel closure with durations that depended on the neomycin concentration. We quantitatively account for these results using a dual inhibition model for neomycin that incorporates voltage-dependent pore plugging and Ca(2+)-dependent allosteric inhibition.
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Affiliation(s)
- Derek R Laver
- School of Biomedical Sciences, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia.
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29
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Borisova L, Shmygol A, Wray S, Burdyga T. Evidence that a Ca2+ sparks/STOCs coupling mechanism is responsible for the inhibitory effect of caffeine on electro-mechanical coupling in guinea pig ureteric smooth muscle. Cell Calcium 2007; 42:303-11. [PMID: 17298845 DOI: 10.1016/j.ceca.2006.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 12/18/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
Recent studies have highlighted the role of the sarcoplasmic reticulum (SR) in controlling excitability, Ca2+ signalling and contractility in smooth muscle. Caffeine, an agonist of ryanodine receptors (RyRs) on the SR has been previously shown to effect Ca2+ signalling but its effects on excitability and contractility are not so clear. We have studied the effects of low concentration of caffeine (1 mM) on Ca2+ signalling, action potential and contractility of guinea pig ureteric smooth muscle. Caffeine produced reversible inhibition of the action potentials, Ca2+ transients and phasic contractions evoked by electrical stimulation. It had no effect on the inward Ca2+ current or Ca2+ transient but increased the amplitude and the frequency of spontaneous transient outward currents (STOCs) in voltage clamped ureteric myocytes, suggesting Ca2+-activated K+ channels (BK) are affected by it. In isolated cells and cells in situ caffeine produced an increase in the frequency and the amplitude of Ca2+ sparks as well the number of spark discharging sites per cell. Inhibition of Ca2+ sparks by ryanodine (50 microM) or SR Ca2+-ATPase (SERCA) cyclopiazonic acid (CPA, 20 microM) or BKCa channels by iberiotoxin (200 nM) or TEA (1 mM), fully reversed the inhibitory effect of caffeine on Ca2+ transients and force evoked by electrical field stimulation (EFS). These data suggest that the inhibitory effect of caffeine on the action potential, Ca2+ transients and force in ureteric smooth muscle is caused by activation of Ca2+ sparks/STOCs coupling mechanism.
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Affiliation(s)
- L Borisova
- The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK
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30
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Paolini C, Quarta M, Nori A, Boncompagni S, Canato M, Volpe P, Allen PD, Reggiani C, Protasi F. Reorganized stores and impaired calcium handling in skeletal muscle of mice lacking calsequestrin-1. J Physiol 2007; 583:767-84. [PMID: 17627988 PMCID: PMC2277031 DOI: 10.1113/jphysiol.2007.138024] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Calsequestrin (CS), the major Ca(2+)-binding protein in the sarcoplasmic reticulum (SR), is thought to play a dual role in excitation-contraction coupling: buffering free Ca(2+) increasing SR capacity, and modulating the activity of the Ca(2+) release channels (RyRs). In this study, we generated and characterized the first murine model lacking the skeletal CS isoform (CS1). CS1-null mice are viable and fertile, even though skeletal muscles appear slightly atrophic compared to the control mice. No compensatory increase of the cardiac isoform CS2 is detectable in any type of skeletal muscle. CS1-null muscle fibres are characterized by structural and functional changes, which are much more evident in fast-twitch muscles (EDL) in which most fibres express only CS1, than in slow-twitch muscles (soleus), where CS2 is expressed in about 50% of the fibres. In isolated EDL muscle, force development is preserved, but characterized by prolonged time-to-peak and half-relaxation time, probably related to impaired calcium release from and re-uptake by the SR. Ca(2+)-imaging studies show that the amount of Ca(2+) released from the SR and the amplitude of the Ca(2+) transient are significantly reduced. The lack of CS1 also causes significant ultrastructural changes, which include: (i) striking proliferation of SR junctional domains; (ii) increased density of Ca(2+)-release channels (confirmed also by (3)H-ryanodine binding); (iii) decreased SR terminal cisternae volume; (iv) higher density of mitochondria. Taken together these results demonstrate that CS1 is essential for the normal development of the SR and its calcium release units and for the storage and release of appropriate amounts of SR Ca(2+).
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Affiliation(s)
- Cecilia Paolini
- IIM Interuniversity Institute of Myology, Ce.S.I. Centro Science dell'Invecchiamento, University G. d' Annunzio, I-66013 Chieti, Italy
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Cohen O, Kanana H, Zoizner R, Gross C, Meiri U, Stern MD, Gerstenblith G, Horowitz M. Altered Ca2+ handling and myofilament desensitization underlie cardiomyocyte performance in normothermic and hyperthermic heat-acclimated rat hearts. J Appl Physiol (1985) 2007; 103:266-75. [PMID: 17395755 DOI: 10.1152/japplphysiol.01351.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heat acclimation (AC) improves cardiac mechanical and metabolic performance. Using cardiomyocytes and isolated hearts from 30-day and 2-day acclimated rats (AC and AC-2d, 34°C), we characterized cellular contractile mechanisms under normothermic (37°C) and hyperthermic (39–42°C) conditions. To determine contractile responses, Ca2+ transients (Ca2+ T), sarcoplasmic reticulum (SR) Ca2+ pool size (fura-2/indo-1 fluorescence), force generation [amplitude systolic motion (ASM)], L-type Ca2+ channels [dihydropyridine receptor (DHPR)], ryanodine receptors (RyRs), and total (PLBt) and phosphorylated phospholamban [serine phosphorylated (PLBs) and theonine phosphorylated (PLBtr)] proteins and transcripts were measured (Western blot, RT-PCR). Cardiac mechanical performance was measured using a Langendorff system. We demonstrated that AC and AC-2d increased Ca2+ T amplitude (148% and 147%, respectively) and twitch force (180% and 130%, respectively) and desensitized myofilaments, as indicated by a rightward shift in the ASM-Ca2+ relationships, despite no change in SR Ca2+ pool size. Hence, generation of higher Ca2+ T underlies greater force development in AC and AC-2d myocytes. In isolated hearts, ryanodine administration eliminated differences between AC and control (C) hearts, implying an important role for RyRs in that acclimation phase. Increased expression of DHPR and RyRs, and decreased PLBs/PLBt in AC hearts only, suggest that different pathways increase force generation in the AC-2d vs. AC myocytes. At basal beating rates, hyperthermia (39–41°C) enhanced pressure generation in AC hearts. C hearts failed to restitute pressure beyond 39°C. Increased beating frequency produced negative inotropic response. In C cardiomyocytes, hyperthermia elevated basal cytosolic Ca2+ and tension, Ca2+ T, and ASM. AC myocytes enhanced Ca2+ T but showed myofilament desensitization, suggesting its involvement in cardiac protection against hyperthermia. Collectively, both Ca2+ turnover and myofilament responsiveness are important adaptive acclimatory targets during normothermic and hyperthermic conditions.
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Affiliation(s)
- Omer Cohen
- Laboratory of Environmental Physiology, Faculty of Dental Medicine, Hadassah Medical Center, The Hebrew University, Jerusalem 91120, Israel
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Hunt D, Jones P, Wang R, Chen W, Bolstad J, Chen K, Shimoni Y, Chen S. K201 (JTV519) suppresses spontaneous Ca2+ release and [3H]ryanodine binding to RyR2 irrespective of FKBP12.6 association. Biochem J 2007; 404:431-8. [PMID: 17313373 PMCID: PMC1896290 DOI: 10.1042/bj20070135] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 02/16/2007] [Accepted: 02/22/2007] [Indexed: 11/17/2022]
Abstract
K201 (JTV519), a benzothiazepine derivative, has been shown to possess anti-arrhythmic and cardioprotective properties, but the mechanism of its action is both complex and controversial. It is believed to stabilize the closed state of the RyR2 (cardiac ryanodine receptor) by increasing its affinity for the FKBP12.6 (12.6 kDa FK506 binding protein) [Wehrens, Lehnart, Reiken, Deng, Vest, Cervantes, Coromilas, Landry and Marks (2004) Science 304, 292-296]. In the present study, we investigated the effect of K201 on spontaneous Ca2+ release induced by Ca2+ overload in rat ventricular myocytes and in HEK-293 cells (human embryonic kidney cells) expressing RyR2 and the role of FKBP12.6 in the action of K201. We found that K201 abolished spontaneous Ca2+ release in cardiac myocytes in a concentration-dependent manner. Treating ventricular myocytes with FK506 to dissociate FKBP12.6 from RyR2 did not affect the suppression of spontaneous Ca2+ release by K201. Similarly, K201 was able to suppress spontaneous Ca2+ release in FK506-treated HEK-293 cells co-expressing RyR2 and FKBP12.6. Furthermore, K201 suppressed spontaneous Ca2+ release in HEK-293 cells expressing RyR2 alone and in cells co-expressing RyR2 and FKBP12.6 with the same potency. In addition, K201 inhibited [3H]ryanodine binding to RyR2-wt (wild-type) and an RyR2 mutant linked to ventricular tachycardia and sudden death, N4104K, in the absence of FKBP12.6. These observations demonstrate that FKBP12.6 is not involved in the inhibitory action of K201 on spontaneous Ca2+ release. Our results also suggest that suppression of spontaneous Ca2+ release and the activity of RyR2 contributes, at least in part, to the anti-arrhythmic properties of K201.
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Key Words
- cardiac arrhythmia
- human embryonic kidney cells (hek-293 cells)
- k201 (jtv519)
- 12.6 kda fk506 binding protein (fkbp12.6)
- ryanodine receptor
- spontaneous ca2+ release
- arvd2, arrhythmogenic right ventricular dysplasia type 2
- cpvt, catecholaminergic polymorphic ventricular tachycardia
- dad, delayed afterdepolarization
- fkbp12.6, 12.6 kda fk506 binding protein
- flp, flippase
- frt, flp recombinase target
- fura 2/am, fura 2 acetoxymethyl ester
- hek-293 cells, human embryonic kidney cells
- ki, knock-in
- ko, knockout
- krh, krebs–ringer–hepes
- ryr, ryanodine receptor
- ryr2, cardiac ryr
- soicr, store-overload-induced ca2+ release
- sr, sarcoplasmic reticulum
- sv40, simian virus 40
- wt, wild-type
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Affiliation(s)
- Donald J. Hunt
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Peter P. Jones
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Ruiwu Wang
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Wenqian Chen
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Jeff Bolstad
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Keyun Chen
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Yakhin Shimoni
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - S. R. Wayne Chen
- *Department of Physiology and Biophysics, University of Calgary, Calgary, AB, Canada T2N 4N1
- †Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada T2N 4N1
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Ferrero P, Said M, Sánchez G, Vittone L, Valverde C, Donoso P, Mattiazzi A, Mundiña-Weilenmann C. Ca2+/calmodulin kinase II increases ryanodine binding and Ca2+-induced sarcoplasmic reticulum Ca2+ release kinetics during beta-adrenergic stimulation. J Mol Cell Cardiol 2007; 43:281-91. [PMID: 17643448 PMCID: PMC2045504 DOI: 10.1016/j.yjmcc.2007.05.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 05/25/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
We aimed to define the relative contribution of both PKA and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) cascades to the phosphorylation of RyR2 and the activity of the channel during beta-adrenergic receptor (betaAR) stimulation. Rat hearts were perfused with increasing concentrations of the beta-agonist isoproterenol in the absence and the presence of CaMKII inhibition. CaMKII was inhibited either by preventing the Ca(2+) influx to the cell by low [Ca](o) plus nifedipine or by the specific inhibitor KN-93. We immunodetected RyR2 phosphorylated at Ser2809 (PKA and putative CaMKII site) and at Ser2815 (CaMKII site) and measured [(3)H]-ryanodine binding and fast Ca(2+) release kinetics in sarcoplasmic reticulum (SR) vesicles. SR vesicles were isolated in conditions that preserved the phosphorylation levels achieved in the intact heart and were actively and equally loaded with Ca(2+). Our results demonstrated that Ser2809 and Ser2815 of RyR2 were dose-dependently phosphorylated under betaAR stimulation by PKA and CaMKII, respectively. The isoproterenol-induced increase in the phosphorylation of Ser2815 site was prevented by the PKA inhibitor H-89 and mimicked by forskolin. CaMKII-dependent phosphorylation of RyR2 (but not PKA-dependent phosphorylation) was responsible for the beta-induced increase in the channel activity as indicated by the enhancement of the [(3)H]-ryanodine binding and the velocity of fast SR Ca(2+) release. The present results show for the first time a dose-dependent increase in the phosphorylation of Ser2815 of RyR2 through the PKA-dependent activation of CaMKII and a predominant role of CaMKII-dependent phosphorylation of RyR2, over that of PKA-dependent phosphorylation, on SR-Ca(2+) release during betaAR stimulation.
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Affiliation(s)
- Paola Ferrero
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
| | - Matilde Said
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
| | - Gina Sánchez
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Casilla 16038, Santiago 9, Chile
| | - Leticia Vittone
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
| | - Carlos Valverde
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
| | - Paulina Donoso
- Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Casilla 16038, Santiago 9, Chile
| | - Alicia Mattiazzi
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
| | - Cecilia Mundiña-Weilenmann
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, 60 y 120, 1900 La Plata, Argentina
- * Corresponding author. Tel./fax: +54 221 483 4833. E-mail address: (C. Mundiña-Weilenmann)
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Shahbazzadeh D, Srairi-Abid N, Feng W, Ram N, Borchani L, Ronjat M, Akbari A, Pessah I, De Waard M, El Ayeb M. Hemicalcin, a new toxin from the Iranian scorpion Hemiscorpius lepturus which is active on ryanodine-sensitive Ca2+ channels. Biochem J 2007; 404:89-96. [PMID: 17291197 PMCID: PMC1868827 DOI: 10.1042/bj20061404] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present work, we purified and characterized a novel toxin named hemicalcin from the venom of the Iranian chactoid scorpion Hemiscorpius lepturus where it represents 0.6% of the total protein content. It is a 33-mer basic peptide reticulated by three disulfide bridges, and that shares between 85 and 91% sequence identity with four other toxins, all known or supposed to be active on ryanodine-sensitive calcium channels. Hemicalcin differs from these other toxins by seven amino acids at positions 9 (leucine/arginine), 12 (alanine/glutamic acid), 13 (aspartic acid/asparagine), 14 (lysine/asparagine), 18 (serine/glycine), 26 (threonine/alanine) and 28 (proline/isoleucine/alanine). In spite of these differences, hemicalcin remains active on ryanodine-sensitive Ca2+ channels, since it increases [3H]ryanodine binding on RyR1 (ryanodine receptor type 1) and triggers Ca2+ release from sarcoplasmic vesicles. Bilayer lipid membrane experiments, in which the RyR1 channel is reconstituted and its gating properties are analysed, indicate that hemicalcin promotes an increase in the opening probability at intermediate concentration and induces a long-lasting subconductance level of 38% of the original amplitude at higher concentrations. Mice intracerebroventricular inoculation of 300 ng of hemicalcin induces neurotoxic symptoms in vivo, followed by death. Overall, these data identify a new biologically active toxin that belongs to a family of peptides active on the ryanodine-sensitive channel.
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Affiliation(s)
- Delavar Shahbazzadeh
- *Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, 13 place Pasteur, Tunis, BP-74, 1002 Tunisia
- †Biotechnology Department, Institute Pasteur of Iran, P.O. Box 13164, Tehran, Iran
| | - Najet Srairi-Abid
- *Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, 13 place Pasteur, Tunis, BP-74, 1002 Tunisia
- To whom correspondence should be addressed (email )
| | - Wei Feng
- ‡Department of Veterinary Medicine-Molecular Biosciences and Center for Children's Environmental Health, University of California Davis, One Shields Avenue, Davis, CA 95616, U.S.A
| | - Narendra Ram
- §INSERM U607, Canaux Calciques, Fonctions et Pathologies, Département Réponse et Dynamique Cellulaire, Commissariat à l'Energie Atomique, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
| | - Lamia Borchani
- *Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, 13 place Pasteur, Tunis, BP-74, 1002 Tunisia
| | - Michel Ronjat
- §INSERM U607, Canaux Calciques, Fonctions et Pathologies, Département Réponse et Dynamique Cellulaire, Commissariat à l'Energie Atomique, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
| | - Abolfazl Akbari
- ∥Razi Vaccine & Serum Research Institute, 31975/148 Karaj, Iran
| | - Isaac N. Pessah
- ‡Department of Veterinary Medicine-Molecular Biosciences and Center for Children's Environmental Health, University of California Davis, One Shields Avenue, Davis, CA 95616, U.S.A
| | - Michel De Waard
- §INSERM U607, Canaux Calciques, Fonctions et Pathologies, Département Réponse et Dynamique Cellulaire, Commissariat à l'Energie Atomique, 17 rue des Martyrs, 38054 Grenoble Cedex 09, France
| | - Mohamed El Ayeb
- *Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, 13 place Pasteur, Tunis, BP-74, 1002 Tunisia
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Bull R, Finkelstein JP, Humeres A, Behrens MI, Hidalgo C. Effects of ATP, Mg2+, and redox agents on the Ca2+ dependence of RyR channels from rat brain cortex. Am J Physiol Cell Physiol 2007; 293:C162-71. [PMID: 17360812 DOI: 10.1152/ajpcell.00518.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Despite their relevance for neuronal Ca(2+)-induced Ca(2+) release (CICR), activation by Ca(2+) of ryanodine receptor (RyR) channels of brain endoplasmic reticulum at the [ATP], [Mg(2+)], and redox conditions present in neurons has not been reported. Here, we studied the effects of varying cis-(cytoplasmic) free ATP concentration ([ATP]), [Mg(2+)], and RyR redox state on the Ca(2+) dependence of endoplasmic reticulum RyR channels from rat brain cortex. At pCa 4.9 and 0.5 mM adenylylimidodiphosphate (AMP-PNP), increasing free [Mg(2+)] up to 1 mM inhibited vesicular [(3)H]ryanodine binding; incubation with thimerosal or dithiothreitol decreased or enhanced Mg(2+) inhibition, respectively. Single RyR channels incorporated into lipid bilayers displayed three different Ca(2+) dependencies, defined by low, moderate, or high maximal fractional open time (P(o)), that depend on RyR redox state, as we have previously reported. In all cases, cis-ATP addition (3 mM) decreased threshold [Ca(2+)] for activation, increased maximal P(o), and shifted channel inhibition to higher [Ca(2+)]. Conversely, at pCa 4.5 and 3 mM ATP, increasing cis-[Mg(2+)] up to 1 mM inhibited low activity channels more than moderate activity channels but barely modified high activity channels. Addition of 0.5 mM free [ATP] plus 0.8 mM free [Mg(2+)] induced a right shift in Ca(2+) dependence for all channels so that [Ca(2+)] <30 microM activated only high activity channels. These results strongly suggest that channel redox state determines RyR activation by Ca(2+) at physiological [ATP] and [Mg(2+)]. If RyR behave similarly in living neurons, cellular redox state should affect RyR-mediated CICR.
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Affiliation(s)
- Ricardo Bull
- Facultad de Medicina, Universidad de Chile, Casilla 70005, Santiago 7, Chile.
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Murayama T, Oba T, Hara H, Wakebe K, Ikemoto N, Ogawa Y. Postulated role of interdomain interaction between regions 1 and 2 within type 1 ryanodine receptor in the pathogenesis of porcine malignant hyperthermia. Biochem J 2007; 402:349-57. [PMID: 17107340 PMCID: PMC1798429 DOI: 10.1042/bj20061040] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have demonstrated recently that CICR (Ca2+-induced Ca2+ release) activity of RyR1 (ryanodine receptor 1) is held to a low level in mammalian skeletal muscle ('suppression' of the channel) and that this is largely caused by the interdomain interaction within RyR1 [Murayama, Oba, Kobayashi, Ikemoto and Ogawa (2005) Am. J. Physiol. Cell Physiol. 288, C1222-C1230]. To test the hypothesis that aberration of this suppression mechanism is involved in the development of channel dysfunctions in MH (malignant hyperthermia), we investigated properties of the RyR1 channels from normal and MHS (MH-susceptible) pig skeletal muscles with an Arg615-->Cys mutation using [3H]ryanodine binding, single-channel recordings and SR (sarcoplasmic reticulum) Ca2+ release. The RyR1 channels from MHS muscle (RyR1MHS) showed enhanced CICR activity compared with those from the normal muscle (RyR1N), although there was little or no difference in the sensitivity to several ligands tested (Ca2+, Mg2+ and adenine nucleotide), nor in the FKBP12 (FK506-binding protein 12) regulation. DP4, a domain peptide matching the Leu2442-Pro2477 region of RyR1 which was reported to activate the Ca2+ channel by weakening the interdomain interaction, activated the RyR1N channel in a concentration-dependent manner, and the highest activity of the affected channel reached a level comparable with that of the RyR1MHS channel with no added peptide. The addition of DP4 to the RyR1MHS channel produced virtually no further effect on the channel activity. These results suggest that stimulation of the RyR1MHS channel caused by affected inter-domain interaction between regions 1 and 2 is an underlying mechanism for dysfunction of Ca2+ homoeostasis seen in the MH phenotype.
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Affiliation(s)
- Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
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Hachisuka J, Soga-Sakakibara S, Kubota M, Narita K, Kuba K. Enhancement of Ca2+-induced Ca2+ release by cyclic ADP-ribose in frog motor nerve terminals. Neuroscience 2007; 146:123-34. [PMID: 17320303 DOI: 10.1016/j.neuroscience.2007.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 12/21/2006] [Accepted: 01/05/2007] [Indexed: 11/30/2022]
Abstract
Ca2+-induced Ca2+ release (CICR) occurs via activation of ryanodine receptors (RyRs) in frog motor nerve terminals after RyRs are primed for activation by repetitive Ca2+ entries, thereby contributing to synaptic plasticity. To clarify how the mechanism of CICR becomes activable by repetitive Ca2+ entries, we studied effects of a RyR modulator, cyclic ADP-ribose (cADPr), on CICR by Ca2+ imaging techniques. Use-dependent binding of fluorescent ryanodine and its blockade by ryanodine revealed the existence of RyRs in the terminals. Repetition of tetani applied to the nerve produced repetitive rises in intracellular Ca2+ ([Ca2+]i) in the terminals. The amplitude of each rise slowly waxed and waned during the course of the stimulation. These slow rises and decays were blocked by ryanodine, indicating the priming, activation and inactivation of CICR. Uncaging of caged-cADPr loaded in the terminals increased the amplitude of short tetanus-induced rises in [Ca2+]i and the amplitude, time to peak and half decay time of the slow waxing and waning rises in [Ca2+]i evoked by repetitive tetani. A cADPr blocker, 8-amino-cADPr, loaded in the terminals decreased the slow waxing and waning component of rises and blocked all the actions of exogenous cADPr. It is concluded that cADPr enhances the priming and activation of CICR. The four-state model for RyRs suggests that cADPr inhibits the inactivation of CICR and increases the activation efficacy of RyR.
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Affiliation(s)
- J Hachisuka
- Department of Physiology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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Wolner I, Kassack MU, Ullmann H, Karel A, Hohenegger M. Use-dependent inhibition of the skeletal muscle ryanodine receptor by the suramin analogue NF676. Br J Pharmacol 2006; 146:525-33. [PMID: 16056233 PMCID: PMC1751178 DOI: 10.1038/sj.bjp.0706359] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The skeletal muscle Ca2+ release channel, the ryanodine receptor, is activated by the trypanocidal drug suramin via the calmodulin-binding site. As calmodulin activates and inhibits the ryanodine receptor depending on whether Ca2+ is absent or present, suramin analogues were screened for inhibition of the ryanodine receptor. Up to 300 microM, the novel suramin analogue, 4,4'-(carbonyl-bis(imino-4,1-phenylene-(2,5-benzimidazolylene)carbonylimino))-bis-benzenesulfonic acid disodium salt (NF676) was not able to significantly inhibit the basal [3H]ryanodine binding. However, kinetic analysis of the high affinity [3H]ryanodine binding elucidates a time-dependent increment of inhibition by NF676, which is indicative for an open channel blocker. Moreover, the ryanodine receptor was much more sensitive towards inhibition by NF676 when preactivated with caffeine or the nonhydrolysable ATP analogue, adenylyl-imidodiphosphate. Nonetheless, the suramin activated ryanodine receptor was not susceptible towards high-affinity NF676 inhibition, indicating an allosteric hindrance between the binding sites of suramin and NF676. In the line of this finding, NF676 per se was not capable to elute the purified ryanodine receptor from a calmodulin-Sepharose, but it prevented the elution by suramin. Other than suramin, NF676 did not inhibit the Ca2+ ATPase of the sarcoplasmic reticulum. However, suramin-induced Ca2+ release from sarcoplasmic reticulum was completely abrogated by preincubation with NF676. Taken together, we conclude from these data that NF676 represents a novel lead compound as a potent use-dependent blocker of the skeletal muscle ryanodine receptor via an allosteric interaction with the suramin-binding site.
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Affiliation(s)
- Ilse Wolner
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | | | | | - Anton Karel
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
| | - Martin Hohenegger
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria
- Author for correspondence:
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Yang T, Riehl J, Esteve E, Matthaei KI, Goth S, Allen PD, Pessah IN, Lopez JR. Pharmacologic and functional characterization of malignant hyperthermia in the R163C RyR1 knock-in mouse. Anesthesiology 2006; 105:1164-75. [PMID: 17122579 DOI: 10.1097/00000542-200612000-00016] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Malignant hyperthermia is a pharmacogenetic disorder affecting humans, dogs, pigs, and horses. In the majority of human cases and all cases in animals, malignant hyperthermia has been associated with missense mutations in the skeletal ryanodine receptor (RyR1). METHODS The authors used a "knock-in" targeting vector to create mice carrying the RyR1 R163C malignant hyperthermia mutation. RESULTS Validation of this new mouse model of human malignant hyperthermia susceptibility includes (1) proof of transcription of the R163C allele and expression of ryanodine receptor protein in R163C heterozygous and R163C homozygous animals; (2) fulminant malignant hyperthermia episodes in R163C heterozygous mice after exposure to 1.25-1.75% halothane or an ambient temperature of 42 degrees C characterized by increased rectal temperature, respiratory rate, and inspiratory effort, with significant blood biochemical changes indicating metabolic acidosis, ending in death and hyperacute rigor mortis; (3) intraperitoneal pretreatment with dantrolene provided 100% protection from the halothane-triggered fulminant malignant hyperthermia episode; (4) significantly increased sensitivity (decreased effective concentration causing 50% of the maximal response) of R163C heterozygous and homozygous myotubes to caffeine, 4-chloro-m-cresol, and K-induced depolarization; (5) R163C heterozygous and homozygous myotubes have a significantly increased resting intracellular Ca concentration compared with wild type; (6) R163C heterozygous sarcoplasmic reticulum membranes have a twofold higher affinity (Kd = 35.4 nm) for [H]ryanodine binding compared with wild type (Kd = 80.1 nm) and a diminished inhibitory regulation by Mg. CONCLUSIONS Heterozygous R163C mice represent a valid model for studying the mechanisms that cause the human malignant hyperthermia syndrome.
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Affiliation(s)
- Tianzhong Yang
- Department of Anesthesia, Perioperative and Pain Medicine, Brigham & Women's Hospital, Boston, Massachusetts 02115, USA
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Abstract
Verticilide (1) is a 24-membered cyclic depsipeptide isolated from the culture broth of Verticillium sp. FKI-1033. It inhibits ryanodine binding to ryanodine receptor (RyR) and has insecticidal activity. The stereochemistry of 2-hydroxyheptanoic acid in verticilide was elucidated by chiral HPLC analysis of the degradation product 6 and synthetic (+) and (-)-6. We also describe the practical total synthesis of verticilide. [reaction: see text].
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Affiliation(s)
- Souichi Monma
- Kitasato Institute for Life Sciences and Graduate School of Infection Control Sciences, Kitasato University, Tokyo 108-8641, Japan
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Abstract
DIDS (4,4'-di-isothiocyanostilbene-2,2'-disulfonate), an anion channel blocker, triggers Ca2+ release from skeletal muscle SR (sarcoplasmic reticulum). The present study characterized the effects of DIDS on rabbit skeletal single Ca2+-release channel/RyR1 (ryanodine receptor type 1) incorporated into a planar lipid bilayer. When junctional SR vesicles were used for channel incorporation (native RyR1), DIDS increased the mean P(o) (open probability) of RyR1 without affecting unitary conductance when Cs+ was used as the charge carrier. Lifetime analysis of single RyR1 activities showed that 10 microM DIDS induced reversible long-lived open events (P(o)=0.451+/-0.038) in the presence of 10 microM Ca2+, due mainly to a new third component for both open and closed time constants. However, when purified RyR1 was examined in the same condition, 10 microM DIDS became considerably less potent (P(o)=0.206+/-0.025), although the caffeine response was similar between native and purified RyR1. Hence we postulated that a DIDS-binding protein, essential for the DIDS sensitivity of RyR1, was lost during RyR1 purification. DIDS-affinity column chromatography of solubilized junctional SR, and MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS analysis of the affinity-column-associated proteins, identified four major DIDS-binding proteins in the SR fraction. Among them, aldolase was the only protein that greatly potentiated DIDS sensitivity. The association between RyR1 and aldolase was further confirmed by co-immunoprecipitation and aldolase-affinity batch-column chromatography. Taken together, we conclude that aldolase is physically associated with RyR1 and could confer a considerable potentiation of the DIDS effect on RyR1.
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Affiliation(s)
- In-Ra Seo
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Sang Hyun Moh
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
| | - Eun Hui Lee
- †Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Gerhard Meissner
- ‡Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, U.S.A
| | - Do Han Kim
- *Department of Life Science, Gwangju Institute of Science and Technology, Gwangju, Korea
- To whom correspondence should be addressed (email )
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Abstract
To clarify whether activity of the ryanodine receptor type 2 (RyR2) is reduced in the sarcoplasmic reticulum (SR) of cardiac muscle, as is the case with the ryanodine receptor type 1 (RyR1), Ca(2+)-dependent [(3)H]ryanodine binding, a biochemical measure of Ca(2+)-induced Ca(2+) release (CICR), was determined using SR vesicle fractions isolated from rabbit and rat cardiac muscles. In the absence of an adenine nucleotide or caffeine, the rat SR showed a complicated Ca(2+) dependence, instead of the well-documented biphasic dependence of the rabbit SR. In the rat SR, [(3)H]ryanodine binding initially increased as [Ca(2+)] increased, with a plateau in the range of 10-100 microM Ca(2+), and thereafter further increased to an apparent peak around 1 mM Ca(2+), followed by a decrease. In the presence of these modulators, this complicated dependence prevailed, irrespective of the source. Addition of 0.3-1 mM Mg(2+) unexpectedly increased the binding two- to threefold and enhanced the affinity for [(3)H]ryanodine at 10-100 microM Ca(2+), resulting in the well-known biphasic dependence. In other words, the partial suppression of RyR2 is relieved by Mg(2+). Ca(2+) could be a substitute for Mg(2+). Mg(2+) also amplifies the responses of RyR2 to inhibitory and stimulatory modulators. This stimulating effect of Mg(2+) on RyR2 is entirely new, and is referred to as the third effect, in addition to the well-known dual inhibitory effects. This effect is critical to describe the role of RyR2 in excitation-contraction coupling of cardiac muscle, in view of the intracellular Mg(2+) concentration.
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Affiliation(s)
- Akihito Chugun
- Department of Pharmacology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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Masuno MN, Pessah IN, Olmstead MM, Molinski TF. Simplified cyclic analogues of bastadin-5. Structure-activity relationships for modulation of the RyR1/FKBP12 Ca2+ channel complex. J Med Chem 2006; 49:4497-511. [PMID: 16854055 PMCID: PMC3987770 DOI: 10.1021/jm050708u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bastadin-5, a brominated macro-dilactam from the marine sponge Ianthella basta, enhances release of Ca2+ from stores within the sarcoplasmic reticulum (SR) of muscle and nonmuscle cells by modulating RyR1/FKBP12 complex. Analogues of bastadin-5 present desirable targets for SAR studies to shed light on the gating mechanism and locus of bastadin-5 binding on these heteromeric channels that mediate essential steps in early coupling of membrane excitation to Ca2+ signaling cascades. Simple, ring-constrained analogues of bastadin-5 were synthesized from substituted benzaldehydes in a convergent manner, featuring an efficient S(N)Ar macroetherification, and evaluated in an assay that measures [3H]-ryanodine that is known to correlate with the functional open state of the Ca2+ channel. The simplified 14-membered ring, atropisomeric analogue (+/-)-7, like bastadin-5, enhanced ryanodine binding to the RyR1/FKBP12 complex (EC50 11 microM), however, unexpectedly, the corresponding achiral 18-membered ring analogue 14 potently inhibited binding (IC50 6 microM) under the same conditions. Structure-activity relationships of both families of cyclic analogues showed activity in a ryanodine binding assay that varied with substitutions of the Br atom on the trisubstituted aryl ring by various functional groups. The most active analogues were those that conserved the dibromocatechol ether moiety that corresponds to the 'western edge' of the bastadin-5 structure. These data suggest that cyclic analogues of bastadin-5 interact with the channel complex in a complex manner that can either enhance or inhibit channel activity.
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Abstract
AIM To elucidate the molecular nature of sulfhydryl modification by hydrogen peroxide on type 1 ryanodine receptor (RyR1). METHODS Rabbit skeletal muscle sarcoplasmic reticulum was treated with hydrogen peroxide, then RyR1 complex was isolated. The proteins in the complex were analysed by electrophoresis, Western blot and electron microscopy. RESULTS (1) Hydrogen peroxide induces inter-subunit cross-linking within the tetrameric RyR1 molecule; (2) in parallel to inter-subunit cross-linking, the RyR1 molecule changes morphology; (3) the chemical and morphological changes are reversible: upon reduction by reducing agents, the RyR1 molecule regains its original state. CONCLUSION These findings suggest that the molecular mechanism of RyR1 channel activity in sarcoplasmic reticulum regulated by hydrogen peroxide is through inter-subunit cross-linking within the tetrameric RyR1 molecule, which in turn induces structural changes of RyR1.
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Affiliation(s)
- Hong-mei Han
- Department of Biophysics, Peking University Health Science Centre, Peking University, Beijing 100083, China
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Dincer UD, Araiza A, Knudson JD, Shao CH, Bidasee KR, Tune JD. Dysfunction of cardiac ryanodine receptors in the metabolic syndrome. J Mol Cell Cardiol 2006; 41:108-14. [PMID: 16793060 DOI: 10.1016/j.yjmcc.2006.04.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 04/20/2006] [Accepted: 04/25/2006] [Indexed: 11/28/2022]
Abstract
This study examined the hypothesis that the prediabetic metabolic syndrome alters expression, phosphorylation state and binding affinity of cardiac RyR2. Real-time PCR and Western blot analysis were used to assess mRNA and protein expression in the left ventricle, right ventricle and right atrium from control (n=5) and chronically high-fat-fed (n=5) dogs with the metabolic syndrome. Functional integrity of RyR2 was assessed by RyR2-Ser2809 phosphorylation and the receptor's ability to bind [3H]ryanodine. We found that RyR2 phosphorylation at Ser2809 was significantly elevated in right and left ventricle from high-fat-fed dogs compared to normal control dogs. This hyperphosphorylation was associated with a decrease in RyR2 binding affinity in right and left ventricle (high-fat diet=80.2 and 90.5 fmol/mg protein vs. control=243.6 and 200.9 fmol/mg protein, respectively) and a decrease in cardiac index in exercising dogs. RyR2 phosphorylation at Ser2809 and RyR2 binding affinity were not altered in the right atria of high-fat-fed dogs. In addition, no significant differences in cardiac RyR2 mRNA or protein expression were noted between groups. These data suggest that alterations in RyR2 could be an important mechanism of early cardiac dysfunction in obesity and insulin resistance.
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Affiliation(s)
- U Deniz Dincer
- Department of Physiology, Louisiana State University Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112, USA.
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Meurs KM, Lacombe VA, Dryburgh K, Fox PR, Reiser PR, Kittleson MD. Differential expression of the cardiac ryanodine receptor in normal and arrhythmogenic right ventricular cardiomyopathy canine hearts. Hum Genet 2006; 120:111-8. [PMID: 16733711 DOI: 10.1007/s00439-006-0193-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 04/18/2006] [Indexed: 11/24/2022]
Abstract
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a form of cardiomyopathy characterized by ventricular tachyarrhythmias and a fibrofatty infiltrate that is believed to preferentially affect the right ventricle. Mutations in the cardiac ryanodine receptor (RyR2) gene have been identified in some human families with a unique form of ARVC, ARVC2. Although the RyR2 has significant importance in excitation-contraction coupling across the ventricles, mutations in the gene encoding for it appear to have the greatest impact on the right ventricle in ARVC2. Using a canine model (boxer), the RyR2 protein and message RNA in the right ventricle, left ventricle and interventricular septum from normal dogs and dogs with ARVC were investigated by immunoblotting and real time PCR. The cardiac RyR2 message and protein expression were differentially expressed across the cardiac walls in the normal heart, with the lowest concentration expressed in the right ventricle (P < 0.05). The message and protein expression of the RyR2 were reduced in all chambers in the canine model of ARVC. We propose that the increased susceptibility of the right ventricle to ARVC may be associated with the lower baseline protein concentration of RyR2 in the normal right ventricle compared to the left ventricle and interventricular septum and that all three areas are equally affected in this canine model of ARVC. Using this naturally occurring model of canine ARVC, we may have provided new insights into the pathogenesis of this cardiomyopathy.
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Affiliation(s)
- Kathryn M Meurs
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
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47
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Higure Y, Shimazaki Y, Nohmi M. Can 4-chloro-m-cresol be substituted for caffeine as an activator of calcium oscillation in bullfrog sympathetic ganglion cells? Cell Calcium 2006; 39:467-70. [PMID: 16530265 DOI: 10.1016/j.ceca.2006.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 01/12/2006] [Accepted: 01/30/2006] [Indexed: 11/19/2022]
Abstract
4-Chloro-m-cresol (cresol) and caffeine have been shown to be potent activators of the Ca(2+) release mediated by the ryanodine-sensitive Ca(2+) release channel and therefore increase the cytosolic free calcium concentration in skeletal muscles. To distinguish the effects of cresol and caffeine in neurones, the responses of the intracellular ([Ca(2+)](i)) and intraluminal free calcium concentrations to cresol were investigated using bullfrog sympathetic ganglion cells and then compared with those to caffeine. Cresol generated a gradual rise (slow response) with and without a fast transient rise (fast response) in [Ca(2+)](i). A low extracellular Ca(2+) concentration abolished the slow response but not the fast response, thus indicating that the slow response was caused by a Ca(2+) influx across the cell membrane. The fast response was inhibited by ryanodine, thus confirming that the source may therefore be the Ca(2+) release through the ryanodine-sensitive calcium store. Unlike caffeine, the long-term application of cresol did not cause any calcium oscillation; neither did it cause a decrease in the basal calcium levels.
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Affiliation(s)
- Yoko Higure
- Division of Instrumental Analysis, Analytical Research Center for Experimental Sciences, Saga University, Nabeshima, Saga 849-8501, Japan
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Kim HS, Chang YH, Kim DH, Park SR, Han SH, Lee JB. Calcium uptake and release through sarcoplasmic reticulum in the inferior oblique muscles of patients with inferior oblique overaction. Yonsei Med J 2006; 47:207-13. [PMID: 16642550 PMCID: PMC2687630 DOI: 10.3349/ymj.2006.47.2.207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
We characterized and compared the characteristics of Ca2+ movements through the sarcoplasmic reticulum of inferior oblique muscles in the various conditions including primary inferior oblique overaction (IOOA), secondary IOOA, and controls, so as to further understand the pathogenesis of primary IOOA. Of 15 specimens obtained through inferior oblique myectomy, six were from primary IOOA, 6 from secondary IOOA, and the remaining 3 were controls from enucleated eyes. Ryanodine binding assays were performed, and Ca2+ uptake rates, calsequestrins and SERCA levels were determined. Ryanodine bindings and sarcoplasmic reticulum Ca2+ uptake rates were significantly decreased in primary IOOA (p < 0.05). Western blot analysis conducted to quantify calsequestrins and SERCA, found no significant difference between primary IOOA, secondary IOOA, and the controls. Increased intracellular Ca2+ concentration due to reduced sarcoplasmic reticulum Ca2+ uptake may play a role in primary IOOA.
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Affiliation(s)
- Hee Seon Kim
- Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Yoon-Hee Chang
- Department of Ophthalmology, Ajou University School of Medicine, Suwon, Korea
| | - Do Han Kim
- Department of Life Science, Kwangju Institute of Science & Technology, Kwangju, Korea
| | - So Ra Park
- Department of Physiology, Inha University College of Medicine, Incheon, Korea
| | - Sueng-Han Han
- Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
| | - Jong Bok Lee
- Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea
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Fernandez-Velasco M, Gomez AM, Richard S. Unzipping RyR2 in adult cardiomyocytes: getting closer to mechanisms of inherited ventricular arrhythmias? Cardiovasc Res 2006; 70:407-9. [PMID: 16690043 DOI: 10.1016/j.cardiores.2006.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 04/06/2006] [Indexed: 11/27/2022] Open
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50
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Pessah IN, Hansen LG, Albertson TE, Garner CE, Ta TA, Do Z, Kim KH, Wong PW. Structure-activity relationship for noncoplanar polychlorinated biphenyl congeners toward the ryanodine receptor-Ca2+ channel complex type 1 (RyR1). Chem Res Toxicol 2006; 19:92-101. [PMID: 16411661 DOI: 10.1021/tx050196m] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ryanodine receptor isoforms are expressed in both excitable and nonexcitable tissues where they form microsomal Ca2+ release channels broadly involved in shaping cellular signaling. In this report, we provide a detailed structure-activity relationship (SAR) for polychlorinated biphenyl (PCB) congeners and metabolites necessary for enhancing ryanodine receptor type 1 (RyR1) activity using [3H]ryanodine ([3H]Ry) binding analysis. The 2,3,6-Cl PCB configuration is most important for optimal recognition by the RyR1 complex and/or critical for sensitizing its activation. Para substitution(s) diminishes the activity with para-chloro having a higher potency than the corresponding para-hydroxy derivative. The addition of a more bulky para-methyl-sulfonyl group eliminates the activity toward RyR1, supporting the importance of the para positions in binding RyR1. The requirement for an intact major T cell immunophilin FKBP12-RyR1 complex was observed with each of 12 active PCB congeners indicating a common mechanism requiring an immunophilin-regulated Ca2+ release channel. An excellent correlation between the relative potencies for doubling [3H]Ry binding and the corresponding initial rates of PCB-induced Ca2+ efflux indicates that [3H]Ry binding analysis provides a measure of dysregulation of microsomal Ca2+ transport. The SAR for activating RyR1 is consistent with those previously reported in several in vivo and in vitro studies, suggesting that a common mechanism may contribute to the toxicity of noncoplanar PCBs. A practical application of the receptor-based screen developed here with RyR1 is that it provides a quantitative SAR that may be useful in predicting biological activity and risk of mixtures containing noncoplanar PCB congeners that have low or a lack of aryl hydrocarbon receptor activity.
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Affiliation(s)
- Isaac N Pessah
- Department of VM:Molecular Biosciences and Center for Children's Environmental Health, University of California, Davis, California 95616, USA.
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