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Rayani K, Davies B, Cheung M, Comber D, Roberts JD, Tadros R, Green MS, Healey JS, Simpson CS, Sanatani S, Steinberg C, MacIntyre C, Angaran P, Duff H, Hamilton R, Arbour L, Leather R, Seifer C, Fournier A, Atallah J, Kimber S, Makanjee B, Alqarawi W, Cadrin-Tourigny J, Joza J, Gardner M, Talajic M, Bagnall RD, Krahn AD, Laksman ZWM. Identification and in-silico characterization of splice-site variants from a large cardiogenetic national registry. Eur J Hum Genet 2023; 31:512-520. [PMID: 36138163 PMCID: PMC10172209 DOI: 10.1038/s41431-022-01193-9] [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: 03/26/2022] [Revised: 08/23/2022] [Accepted: 09/08/2022] [Indexed: 11/08/2022] Open
Abstract
Splice-site variants in cardiac genes may predispose carriers to potentially lethal arrhythmias. To investigate, we screened 1315 probands and first-degree relatives enrolled in the Canadian Hearts in Rhythm Organization (HiRO) registry. 10% (134/1315) of patients in the HiRO registry carry variants within 10 base-pairs of the intron-exon boundary with 78% (104/134) otherwise genotype negative. These 134 probands were carriers of 57 unique variants. For each variant, American College of Medical Genetics and Genomics (ACMG) classification was revisited based on consensus between nine in silico tools. Due in part to the in silico algorithms, seven variants were reclassified from the original report, with the majority (6/7) downgraded. Our analyses predicted 53% (30/57) of variants to be likely/pathogenic. For the 57 variants, an average of 9 tools were able to score variants within splice sites, while 6.5 tools responded for variants outside these sites. With likely/pathogenic classification considered a positive outcome, the ACMG classification was used to calculate sensitivity/specificity of each tool. Among these, Combined Annotation Dependent Depletion (CADD) had good sensitivity (93%) and the highest response rate (131/134, 98%), dbscSNV was also sensitive (97%), and SpliceAI was the most specific (64%) tool. Splice variants remain an important consideration in gene elusive inherited arrhythmia syndromes. Screening for intronic variants, even when restricted to the ±10 positions as performed here may improve genetic testing yield. We compare 9 freely available in silico tools and provide recommendations regarding their predictive capabilities. Moreover, we highlight several novel cardiomyopathy-associated variants which merit further study.
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Affiliation(s)
- Kaveh Rayani
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Brianna Davies
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Matthew Cheung
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Drake Comber
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | - Rafik Tadros
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Martin S Green
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | | | | | | | - Christian Steinberg
- Institut Universitaire de Cardiologie et Pneumologie de Quebec, Laval University, Quebec City, QC, Canada
| | - Ciorsti MacIntyre
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Paul Angaran
- St Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Henry Duff
- Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Robert Hamilton
- Division of Cardiology, The Hospital for Sick Children (SickKids), Toronto, ON, Canada
| | - Laura Arbour
- Division of Medical Genetics, Island Health, Victoria, BC, Canada
| | | | - Colette Seifer
- Section of Cardiology, Department of Internal Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Fournier
- Division of Pediatric Cardiology, CHU Sainte-Justine, Universite de Montreal, Montreal, QC, Canada
| | - Joseph Atallah
- Division of Pediatric Cardiology, University of Alberta Stollery Children's Hospital, Edmonton, AB, Canada
| | - Shane Kimber
- Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Bhavanesh Makanjee
- Heart Health Institute, Scarborough Health Network, Scarborough, ON, Canada
| | - Wael Alqarawi
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | - Julia Cadrin-Tourigny
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Jacqueline Joza
- Division of Cardiology, McGill University Health Centre, Montreal, QC, Canada
| | - Martin Gardner
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Mario Talajic
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Richard D Bagnall
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Andrew D Krahn
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Zachary W M Laksman
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
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Rayani K, Hantz ER, Haji-Ghassemi O, Li AY, Spuches AM, Van Petegem F, Solaro RJ, Lindert S, Tibbits GF. The effect of Mg 2+ on Ca 2+ binding to cardiac troponin C in hypertrophic cardiomyopathy associated TNNC1 variants. FEBS J 2022; 289:7446-7465. [PMID: 35838319 PMCID: PMC9836626 DOI: 10.1111/febs.16578] [Citation(s) in RCA: 2] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 05/14/2022] [Accepted: 07/13/2022] [Indexed: 01/14/2023]
Abstract
Cardiac troponin C (cTnC) is the critical Ca2+ -sensing component of the troponin complex. Binding of Ca2+ to cTnC triggers a cascade of conformational changes within the myofilament that culminate in force production. Hypertrophic cardiomyopathy (HCM)-associated TNNC1 variants generally induce a greater degree and duration of Ca2+ binding, which may underly the hypertrophic phenotype. Regulation of contraction has long been thought to occur exclusively through Ca2+ binding to site II of cTnC. However, work by several groups including ours suggest that Mg2+ , which is several orders of magnitude more abundant in the cell than Ca2+ , may compete for binding to the same cTnC regulatory site. We previously used isothermal titration calorimetry (ITC) to demonstrate that physiological concentrations of Mg2+ may decrease site II Ca2+ -binding in both N-terminal and full-length cTnC. Here, we explore the binding of Ca2+ and Mg2+ to cTnC harbouring a series of TNNC1 variants thought to be causal in HCM. ITC and thermodynamic integration (TI) simulations show that A8V, L29Q and A31S elevate the affinity for both Ca2+ and Mg2+ . Further, L48Q, Q50R and C84Y that are adjacent to the EF hand binding motif of site II have a more significant effect on affinity and the thermodynamics of the binding interaction. To the best of our knowledge, this work is the first to explore the role of Mg2+ in modifying the Ca2+ affinity of cTnC mutations linked to HCM. Our results indicate a physiologically significant role for cellular Mg2+ both at baseline and when elevated on modifying the Ca2+ binding properties of cTnC and the subsequent conformational changes which precede cardiac contraction.
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Affiliation(s)
- Kaveh Rayani
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
| | - Eric R Hantz
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Omid Haji-Ghassemi
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, Canada
| | - Alison Y Li
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
| | - Anne M Spuches
- Department of Chemistry, 300 Science and Technology, East Carolina University, Greenville, NC, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, Canada
| | - R John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, USA
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
- BC Children's Hospital Research Institute, Vancouver, Canada
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Chan P, Waxman RE, Woo S, Docherty C, Rayani K, Fischler I, Ghaffar O, Elmi S. Electroconvulsive Therapy for Neuropsychiatric Symptoms due to Major Neurocognitive Disorder: A Prospective, Observational Study. J ECT 2022; 38:81-87. [PMID: 35613007 DOI: 10.1097/yct.0000000000000814] [Citation(s) in RCA: 1] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Neuropsychiatric symptoms (NPSs) in those with major neurocognitive disorder (MNCD) include the responsive behaviors of agitation and aggression. Electroconvulsive therapy (ECT) has shown some effectiveness based on retrospective studies and one open label prospective study. We hypothesized that ECT will reduce NPSs between baseline and after treatment in those with medication-refractory behaviors. METHOD/DESIGN This Canadian prospective multicenter study included MNCD patients admitted to geriatric psychiatry units for the management of refractory NPSs. All treatment-refractory participants suffered from advanced MNCD. We conducted the Neuropsychiatric Inventory-Clinician version and the Pittsburgh Agitation Scale at baseline, and during and after the ECT course. A bitemporal or bifrontal ECT series based on dose titration to 1.5 to 2.5 times seizure threshold was administered. RESULTS Data were collected for 33 patients with a mean age of 73 and categorized with severe MNCD using the Functional Assessment Staging of Alzheimer's Disease scale (stages 6 and 7). The data showed a drop in mean Neuropsychiatric Inventory-Clinician version from 58.36 to 24.58 (P < 0.0001). Mean Neuropsychiatric Inventory agitation subscale dropped from 7.12 to 3.09 (P = 0.007). Mean Neuropsychiatric Inventory aggression subscale dropped from 6.94 to 0.97 (P < 0.0001). There was a concomitant significant decline in Pittsburgh Agitation Scale scores. No participants dropped out because of intolerance of ECT. One participant died from pneumonia, which did not appear related to ECT. CONCLUSIONS In this naturalistic study, ECT was found to be a safe and effective treatment for certain NPSs in people with MNCD. This can translate into improving quality of life.
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Affiliation(s)
| | | | | | - Claire Docherty
- From the Department of Psychiatry, Faculty of Medicine, University of British Columbia
| | - Kaveh Rayani
- Undergraduate Program, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia
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Montgomery S, Dahri K, Rayani K, Kwok J, Chan P. The Use of Anticonvulsant Adjuncts to Treat Alcohol Withdrawal Syndrome in Older Adults. Can Geriatr J 2022; 25:32-39. [PMID: 35310475 PMCID: PMC8887711 DOI: 10.5770/cgj.25.544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background
We evaluated the prescribing practices of anticonvulsant (AC) adjuncts to benzodiazepines in managing Alcohol Withdrawal Syndrome (AWS). We also examined the prescription of relapse prevention agents for Alcohol Use Disorder (AUD), and adverse events related to AWS treatment.
Methods
Records were reviewed retrospectively pertaining to medically ill adults aged 60 and above with AWS and admitted to a medicine or hospitalist unit of a Canadian centre between June 2013 and June 2018. Duration and dosing of benzodiazepine, dosing and type of AC and AUD agent, and adverse events were collected. A multivariable regression model was employed.
Results
83 encounters were included in the study and 28 were prescribed an AC. The amount and duration of benzodiazepine administered were not statistically different between the benzodiazepine only and the AC adjunct groups, once severe AWS complications were accounted for. Five new prescriptions of traditional AUD agents were provided on discharge. No AC-associated adverse events occurred.
Conclusions
AC adjuncts for AWS did not decrease the amount of benzodiazepine administered nor shorten the duration of treatment. Their routine use is not supported by our findings. Our study highlights a missed opportunity for AUD agents to be prescribed during hospitalization.
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Ghovanloo MR, Choudhury K, Bandaru TS, Fouda MA, Rayani K, Rusinova R, Phaterpekar T, Nelkenbrecher K, Watkins AR, Poburko D, Thewalt J, Andersen OS, Delemotte L, Goodchild SJ, Ruben PC. Cannabidiol inhibits the skeletal muscle Nav1.4 by blocking its pore and by altering membrane elasticity. J Gen Physiol 2021; 153:211970. [PMID: 33836525 PMCID: PMC8042605 DOI: 10.1085/jgp.202012701] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/13/2020] [Accepted: 03/16/2021] [Indexed: 12/12/2022] Open
Abstract
Cannabidiol (CBD) is the primary nonpsychotropic phytocannabinoid found in Cannabis sativa, which has been proposed to be therapeutic against many conditions, including muscle spasms. Among its putative targets are voltage-gated sodium channels (Navs), which have been implicated in many conditions. We investigated the effects of CBD on Nav1.4, the skeletal muscle Nav subtype. We explored direct effects, involving physical block of the Nav pore, as well as indirect effects, involving modulation of membrane elasticity that contributes to Nav inhibition. MD simulations revealed CBD's localization inside the membrane and effects on bilayer properties. Nuclear magnetic resonance (NMR) confirmed these results, showing CBD localizing below membrane headgroups. To determine the functional implications of these findings, we used a gramicidin-based fluorescence assay to show that CBD alters membrane elasticity or thickness, which could alter Nav function through bilayer-mediated regulation. Site-directed mutagenesis in the vicinity of the Nav1.4 pore revealed that removing the local anesthetic binding site with F1586A reduces the block of INa by CBD. Altering the fenestrations in the bilayer-spanning domain with Nav1.4-WWWW blocked CBD access from the membrane into the Nav1.4 pore (as judged by MD). The stabilization of inactivation, however, persisted in WWWW, which we ascribe to CBD-induced changes in membrane elasticity. To investigate the potential therapeutic value of CBD against Nav1.4 channelopathies, we used a pathogenic Nav1.4 variant, P1158S, which causes myotonia and periodic paralysis. CBD reduces excitability in both wild-type and the P1158S variant. Our in vitro and in silico results suggest that CBD may have therapeutic value against Nav1.4 hyperexcitability.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada.,Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, BC, Canada.,Science for Life Laboratory, Department of Physics, Royal Institute of Technology, Solna, Sweden
| | - Koushik Choudhury
- Science for Life Laboratory, Department of Physics, Royal Institute of Technology, Solna, Sweden
| | - Tagore S Bandaru
- Science for Life Laboratory, Department of Physics, Royal Institute of Technology, Solna, Sweden
| | - Mohamed A Fouda
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada.,Department of Pharmacology and Toxicology, Alexandria University, Alexandria, Egypt
| | - Kaveh Rayani
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Radda Rusinova
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY
| | - Tejas Phaterpekar
- Department of Molecular Biology and Biochemistry/Physics, Simon Fraser University, Burnaby, BC, Canada
| | - Karen Nelkenbrecher
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, BC, Canada
| | - Abeline R Watkins
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Damon Poburko
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Jenifer Thewalt
- Department of Molecular Biology and Biochemistry/Physics, Simon Fraser University, Burnaby, BC, Canada
| | - Olaf S Andersen
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Physics, Royal Institute of Technology, Solna, Sweden
| | - Samuel J Goodchild
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals, Burnaby, BC, Canada
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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6
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Yang YB, Chan P, Rayani K, McGirr A. Comparative Effectiveness of Repetitive Transcranial Magnetic Stimulation in Unipolar and Bipolar Depression. Can J Psychiatry 2021; 66:313-315. [PMID: 32815380 PMCID: PMC7958194 DOI: 10.1177/0706743720950938] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Yue Bo Yang
- MD Undergraduate Program, 8166University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter Chan
- Department of Psychiatry, 8166University of British Columbia, Vancouver, British Columbia, Canada.,Neurostimulation Program, 380154Vancouver General Hospital, British Columbia, Canada
| | - Kaveh Rayani
- MD Undergraduate Program, 8166University of British Columbia, Vancouver, British Columbia, Canada
| | - Alexander McGirr
- Department of Psychiatry, 2129University of Calgary, Alberta, Canada.,Hotchkiss Brain Institute, Calgary, Alberta, Canada.,Mathison Centre for Mental Health Research and Education, Calgary, Alberta, Canada
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Rayani K, Seffernick J, Li AY, Davis JP, Spuches AM, Van Petegem F, Solaro RJ, Lindert S, Tibbits GF. Binding of calcium and magnesium to human cardiac troponin C. J Biol Chem 2021; 296:100350. [PMID: 33548225 PMCID: PMC7961095 DOI: 10.1016/j.jbc.2021.100350] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 01/03/2023] Open
Abstract
Cardiac muscle thin filaments are composed of actin, tropomyosin, and troponin that change conformation in response to Ca2+ binding, triggering muscle contraction. Human cardiac troponin C (cTnC) is the Ca2+-sensing component of the thin filament. It contains structural sites (III/IV) that bind both Ca2+ and Mg2+ and a regulatory site (II) that has been thought to bind only Ca2+. Binding of Ca2+ at this site initiates a series of conformational changes that culminate in force production. However, the mechanisms that underpin the regulation of binding at site II remain unclear. Here, we have quantified the interaction between site II and Ca2+/Mg2+ through isothermal titration calorimetry and thermodynamic integration simulations. Direct and competitive binding titrations with WT N-terminal cTnC and full-length cTnC indicate that physiologically relevant concentrations of both Ca2+/Mg2+ interacted with the same locus. Moreover, the D67A/D73A N-terminal cTnC construct in which two coordinating residues within site II were removed was found to have significantly reduced affinity for both cations. In addition, 1 mM Mg2+ caused a 1.4-fold lower affinity for Ca2+. These experiments strongly suggest that cytosolic-free Mg2+ occupies a significant population of the available site II. Interaction of Mg2+ with site II of cTnC likely has important functional consequences for the heart both at baseline as well as in diseased states that decrease or increase the availability of Mg2+, such as secondary hyperparathyroidism or ischemia, respectively.
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Affiliation(s)
- Kaveh Rayani
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Justin Seffernick
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio, USA
| | - Alison Yueh Li
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio, USA
| | - Anne Marie Spuches
- Department of Chemistry, East Carolina University, 300 Science and Technology Building, Greenville, North Carolina, USA
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - R John Solaro
- Department of Physiology and Biophysics and the Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio, USA
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada; Cardiac Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
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8
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Shi YP, Pang Z, Venkateshappa R, Gunawan M, Kemp J, Truong E, Chang C, Lin E, Shafaattalab S, Faizi S, Rayani K, Tibbits GF, Claydon VE, Claydon TW. The hERG channel activator, RPR260243, enhances protective IKr current early in the refractory period reducing arrhythmogenicity in zebrafish hearts. Am J Physiol Heart Circ Physiol 2020; 319:H251-H261. [PMID: 32559136 DOI: 10.1152/ajpheart.00038.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Human ether-à-go-go related gene (hERG) K+ channels are important in cardiac repolarization, and their dysfunction causes prolongation of the ventricular action potential, long QT syndrome, and arrhythmia. As such, approaches to augment hERG channel function, such as activator compounds, have been of significant interest due to their marked therapeutic potential. Activator compounds that hinder channel inactivation abbreviate action potential duration (APD) but carry risk of overcorrection leading to short QT syndrome. Enhanced risk by overcorrection of the APD may be tempered by activator-induced increased refractoriness; however, investigation of the cumulative effect of hERG activator compounds on the balance of these effects in whole organ systems is lacking. Here, we have investigated the antiarrhythmic capability of a hERG activator, RPR260243, which primarily augments channel function by slowing deactivation kinetics in ex vivo zebrafish whole hearts. We show that RPR260243 abbreviates the ventricular APD, reduces triangulation, and steepens the slope of the electrical restitution curve. In addition, RPR260243 increases the post-repolarization refractory period. We provide evidence that this latter effect arises from RPR260243-induced enhancement of hERG channel-protective currents flowing early in the refractory period. Finally, the cumulative effect of RPR260243 on arrhythmogenicity in whole organ zebrafish hearts is demonstrated by the restoration of normal rhythm in hearts presenting dofetilide-induced arrhythmia. These findings in a whole organ model demonstrate the antiarrhythmic benefit of hERG activator compounds that modify both APD and refractoriness. Furthermore, our results demonstrate that targeted slowing of hERG channel deactivation and enhancement of protective currents may provide an effective antiarrhythmic approach.NEW & NOTEWORTHY hERG channel dysfunction causes long QT syndrome and arrhythmia. Activator compounds have been of significant interest due to their therapeutic potential. We used the whole organ zebrafish heart model to demonstrate the antiarrhythmic benefit of the hERG activator, RPR260243. The activator abbreviated APD and increased refractoriness, the combined effect of which rescued induced ventricular arrhythmia. Our findings show that the targeted slowing of hERG channel deactivation and enhancement of protective currents caused by the RPR260243 activator may provide an effective antiarrhythmic approach.
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Affiliation(s)
- Yu Patrick Shi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - ZhaoKai Pang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Ravichandra Venkateshappa
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Marvin Gunawan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Jacob Kemp
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Elson Truong
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Cherlene Chang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Eric Lin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Sanam Shafaattalab
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Shoaib Faizi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Kaveh Rayani
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Glen F Tibbits
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
| | - Thomas W Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, British Columbia, Canada
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9
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Hull CM, Genge CE, Hobbs Y, Rayani K, Lin E, Gunawan M, Shafaattalab S, Tibbits GF, Claydon TW. Investigating the utility of adult zebrafish ex vivo whole hearts to pharmacologically screen hERG channel activator compounds. Am J Physiol Regul Integr Comp Physiol 2019; 317:R921-R931. [PMID: 31664867 DOI: 10.1152/ajpregu.00190.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is significant interest in the potential utility of small-molecule activator compounds to mitigate cardiac arrhythmia caused by loss of function of hERG1a voltage-gated potassium channels. Zebrafish (Danio rerio) have been proposed as a cost-effective, high-throughput drug-screening model to identify compounds that cause hERG1a dysfunction. However, there are no reports on the effects of hERG1a activator compounds in zebrafish and consequently on the utility of the model to screen for potential gain-of-function therapeutics. Here, we examined the effects of hERG1a blocker and types 1 and 2 activator compounds on isolated zkcnh6a (zERG3) channels in the Xenopus oocyte expression system as well as action potentials recorded from ex vivo adult zebrafish whole hearts using optical mapping. Our functional data from isolated zkcnh6a channels show that under the conditions tested, these channels are blocked by hERG1a channel blockers (dofetilide and terfenadine), and activated by type 1 (RPR260243) and type 2 (NS1643, PD-118057) hERG1a activators with higher affinity than hKCNH2a channels (except NS1643), with differences accounted for by different biophysical properties in the two channels. In ex vivo zebrafish whole hearts, two of the three hERG1a activators examined caused abbreviation of the action potential duration (APD), whereas hERG1a blockers caused APD prolongation. These data represent, to our knowledge, the first pharmacological characterization of isolated zkcnh6a channels and the first assessment of hERG enhancing therapeutics in zebrafish. Our findings lead us to suggest that the zebrafish ex vivo whole heart model serves as a valuable tool in the screening of hKCNH2a blocker and activator compounds.
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Affiliation(s)
- Christina M Hull
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christine E Genge
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Yuki Hobbs
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kaveh Rayani
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Eric Lin
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Marvin Gunawan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sanam Shafaattalab
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Glen F Tibbits
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Tom W Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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10
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Rayani K, Lin E, Craig C, Lamothe M, Shafaattalab S, Gunawan M, Li AY, Hove-Madsen L, Tibbits GF. Zebrafish as a model of mammalian cardiac function: Optically mapping the interplay of temperature and rate on voltage and calcium dynamics. Progress in Biophysics and Molecular Biology 2018; 138:69-90. [DOI: 10.1016/j.pbiomolbio.2018.07.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 12/27/2022]
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11
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Abstract
The ability of cardiomyocytes to recover from a proton load was examined in the hearts of exercise-trained and sedentary control rats in CO2/[Formula: see text]-free media. Acidosis was created by the NH4Cl prepulse technique, and intracellular pH (pHi) was determined using fluorescence microscopy on carboxy-SNARF-1 AM-loaded isolated cardiomyocytes. CO2-independent pHi buffering capacity (βi) was measured by incrementally reducing the extracellular NH4Cl concentration in steps of 50% from 20 to 1.25 mM. βi increased as pHi decreased in both exercise-trained and sedentary control groups. However, the magnitude of increase in βi as a function of pHi was found to be significantly ( P < 0.001) greater in the exercise-trained group compared with the sedentary control group. The rate of pHi recovery from an imposed proton load was found to not be different between the exercise-trained and control groups. The Na+/H+ exchanger-dependent H+ extrusion rate during the recovery from an imposed proton load, however, was found to be significantly greater in the exercise-trained group compared with the control group. By increasing βi and subsequently the Na+/H+ exchanger-dependent H+ extrusion rate, exercise training may provide cardiomyocytes with the ability to better handle an intracellular excess of H+ generated during hypoxia/ischemic insults and may serve in a cardioprotective role. These data may be predictive of two positive outcomes: 1) increased exercise tolerance by the heart and 2) a protective mechanism that limits the degree of myocardial acidosis and subsequent damage that accompanies ischemia-reperfusion stress. NEW & NOTEWORTHY The enhanced ability to deal with acidosis conferred by exercise training is likely to improve exercise tolerance and outcomes in response to myocardial ischemia-reperfusion injury.
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Affiliation(s)
- Vennetia R Danes
- Molecular Cardiac Physiology Group, Simon Fraser University , Burnaby, British Columbia , Canada
| | - Josephine Anthony
- Molecular Cardiac Physiology Group, Simon Fraser University , Burnaby, British Columbia , Canada
| | - Kaveh Rayani
- Molecular Cardiac Physiology Group, Simon Fraser University , Burnaby, British Columbia , Canada
| | - Kenneth W Spitzer
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Simon Fraser University , Burnaby, British Columbia , Canada.,Cardiovascular Sciences, BC Research Institute for Children's and Women's Health , Vancouver, British Columbia , Canada
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12
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Stevens CM, Rayani K, Genge CE, Singh G, Liang B, Roller JM, Li C, Li AY, Tieleman DP, van Petegem F, Tibbits GF. Characterization of Zebrafish Cardiac and Slow Skeletal Troponin C Paralogs by MD Simulation and ITC. Biophys J 2017; 111:38-49. [PMID: 27410732 DOI: 10.1016/j.bpj.2016.05.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/06/2016] [Accepted: 05/19/2016] [Indexed: 12/17/2022] Open
Abstract
Zebrafish, as a model for teleost fish, have two paralogous troponin C (TnC) genes that are expressed in the heart differentially in response to temperature acclimation. Upon Ca(2+) binding, TnC changes conformation and exposes a hydrophobic patch that interacts with troponin I and initiates cardiac muscle contraction. Teleost-specific TnC paralogs have not yet been functionally characterized. In this study we have modeled the structures of the paralogs using molecular dynamics simulations at 18°C and 28°C and calculated the different Ca(2+)-binding properties between the teleost cardiac (cTnC or TnC1a) and slow-skeletal (ssTnC or TnC1b) paralogs through potential-of-mean-force calculations. These values are compared with thermodynamic binding properties obtained through isothermal titration calorimetry (ITC). The modeled structures of each of the paralogs are similar at each temperature, with the exception of helix C, which flanks the Ca(2+) binding site; this region is also home to paralog-specific sequence substitutions that we predict have an influence on protein function. The short timescale of the potential-of-mean-force calculation precludes the inclusion of the conformational change on the ΔG of Ca(2+) interaction, whereas the ITC analysis includes the Ca(2+) binding and conformational change of the TnC molecule. ITC analysis has revealed that ssTnC has higher Ca(2+) affinity than cTnC for Ca(2+) overall, whereas each of the paralogs has increased affinity at 28°C compared to 18°C. Microsecond-timescale simulations have calculated that the cTnC paralog transitions from the closed to the open state more readily than the ssTnC paralog, an unfavorable transition that would decrease the ITC-derived Ca(2+) affinity while simultaneously increasing the Ca(2+) sensitivity of the myofilament. We propose that the preferential expression of cTnC at lower temperatures increases myofilament Ca(2+) sensitivity by this mechanism, despite the lower Ca(2+) affinity that we have measured by ITC.
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Affiliation(s)
- Charles M Stevens
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kaveh Rayani
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Christine E Genge
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Gurpreet Singh
- Biocomputing Group, University of Calgary, Calgary, Alberta, Canada
| | - Bo Liang
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Janine M Roller
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Cindy Li
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Alison Yueh Li
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - D Peter Tieleman
- Biocomputing Group, University of Calgary, Calgary, Alberta, Canada
| | - Filip van Petegem
- Department of Biochemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Glen F Tibbits
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
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13
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Stevens CM, Rayani K, Singh G, Lotfalisalmasi B, Tieleman DP, Tibbits GF. Changes in the dynamics of the cardiac troponin C molecule explain the effects of Ca 2+-sensitizing mutations. J Biol Chem 2017; 292:11915-11926. [PMID: 28533433 DOI: 10.1074/jbc.m116.770776] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/07/2017] [Indexed: 12/31/2022] Open
Abstract
Cardiac troponin C (cTnC) is the regulatory protein that initiates cardiac contraction in response to Ca2+ TnC binding Ca2+ initiates a cascade of protein-protein interactions that begins with the opening of the N-terminal domain of cTnC, followed by cTnC binding the troponin I switch peptide (TnISW). We have evaluated, through isothermal titration calorimetry and molecular-dynamics simulation, the effect of several clinically relevant mutations (A8V, L29Q, A31S, L48Q, Q50R, and C84Y) on the Ca2+ affinity, structural dynamics, and calculated interaction strengths between cTnC and each of Ca2+ and TnISW Surprisingly the Ca2+ affinity measured by isothermal titration calorimetry was only significantly affected by half of these mutations including L48Q, which had a 10-fold higher affinity than WT, and the Q50R and C84Y mutants, each of which had affinities 3-fold higher than wild type. This suggests that Ca2+ affinity of the N-terminal domain of cTnC in isolation is insufficient to explain the pathogenicity of these mutations. Molecular-dynamics simulation was used to evaluate the effects of these mutations on Ca2+ binding, structural dynamics, and TnI interaction independently. Many of the mutations had a pronounced effect on the balance between the open and closed conformations of the TnC molecule, which provides an indirect mechanism for their pathogenic properties. Our data demonstrate that the structural dynamics of the cTnC molecule are key in determining myofilament Ca2+ sensitivity. Our data further suggest that modulation of the structural dynamics is the underlying molecular mechanism for many disease mutations that are far from the regulatory Ca2+-binding site of cTnC.
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Affiliation(s)
- Charles M Stevens
- Cardiovascular Sciences, British Columbia Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada; Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Kaveh Rayani
- Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Gurpreet Singh
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Bairam Lotfalisalmasi
- Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Glen F Tibbits
- Cardiovascular Sciences, British Columbia Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada; Departments of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada; Departments of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
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14
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Stevens CM, Rayani K, Singh G, Tieleman DP, Tibbits GF. Potential of Mean Force Calculations and Isothermal Titration Calorimetry Measurements of the Human Cardiac Troponin C / Calcium Interaction Reveal Affinity Changes as a Function of Familial Hypertrophic Cardiomyopathy Associated Mutations. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Rayani K, Stevens CM, Liang B, Genge CE, Tibbits GF. Thermodynamics of Calcium Binding to Zebrafish Troponin C (TnC) Visualized through Isothermal Titration Calorimetry (ITC) and Molecular Dynamics (MD). Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Li AY, Rayani K, Wilson D, Branda N, Tibbits G. A Novel Tryptophan Analog Designed for Studying Calcium Induced Conformational Change of Troponin C. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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17
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Lee L, Genge CE, Cua M, Sheng X, Rayani K, Beg MF, Sarunic MV, Tibbits GF. Functional Assessment of Cardiac Responses of Adult Zebrafish (Danio rerio) to Acute and Chronic Temperature Change Using High-Resolution Echocardiography. PLoS One 2016; 11:e0145163. [PMID: 26730947 PMCID: PMC4701665 DOI: 10.1371/journal.pone.0145163] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [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: 07/30/2015] [Accepted: 11/27/2015] [Indexed: 12/21/2022] Open
Abstract
The zebrafish (Danio rerio) is an important organism as a model for understanding vertebrate cardiovascular development. However, little is known about adult ZF cardiac function and how contractile function changes to cope with fluctuations in ambient temperature. The goals of this study were to: 1) determine if high resolution echocardiography (HRE) in the presence of reduced cardiodepressant anesthetics could be used to accurately investigate the structural and functional properties of the ZF heart and 2) if the effect of ambient temperature changes both acutely and chronically could be determined non-invasively using HRE in vivo. Heart rate (HR) appears to be the critical factor in modifying cardiac output (CO) with ambient temperature fluctuation as it increases from 78 ± 5.9 bpm at 18°C to 162 ± 9.7 bpm at 28°C regardless of acclimation state (cold acclimated CA- 18°C; warm acclimated WA- 28°C). Stroke volume (SV) is highest when the ambient temperature matches the acclimation temperature, though this difference did not constitute a significant effect (CA 1.17 ± 0.15 μL at 18°C vs 1.06 ± 0.14 μl at 28°C; WA 1.10 ± 0.13 μL at 18°C vs 1.12 ± 0.12 μl at 28°C). The isovolumetric contraction time (IVCT) was significantly shorter in CA fish at 18°C. The CA group showed improved systolic function at 18°C in comparison to the WA group with significant increases in both ejection fraction and fractional shortening and decreases in IVCT. The decreased early peak (E) velocity and early peak velocity / atrial peak velocity (E/A) ratio in the CA group are likely associated with increased reliance on atrial contraction for ventricular filling.
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Affiliation(s)
- Ling Lee
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- Child and Family Research Institute, Department of Cardiovascular Science, 950 West 28th Ave, Vancouver, BC V5Z 4H4, Canada
| | - Christine E. Genge
- Child and Family Research Institute, Department of Cardiovascular Science, 950 West 28th Ave, Vancouver, BC V5Z 4H4, Canada
| | - Michelle Cua
- School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Xiaoye Sheng
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- Child and Family Research Institute, Department of Cardiovascular Science, 950 West 28th Ave, Vancouver, BC V5Z 4H4, Canada
| | - Kaveh Rayani
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Mirza F. Beg
- School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Marinko V. Sarunic
- School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Glen F. Tibbits
- Molecular Cardiac Physiology Group, Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
- Child and Family Research Institute, Department of Cardiovascular Science, 950 West 28th Ave, Vancouver, BC V5Z 4H4, Canada
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18
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Genge CE, Lin E, Lee L, Sheng X, Rayani K, Gunawan M, Stevens CM, Li AY, Talab SS, Claydon TW, Hove-Madsen L, Tibbits GF. The Zebrafish Heart as a Model of Mammalian Cardiac Function. Rev Physiol Biochem Pharmacol 2016; 171:99-136. [PMID: 27538987 DOI: 10.1007/112_2016_5] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Zebrafish (Danio rerio) are widely used as vertebrate model in developmental genetics and functional genomics as well as in cardiac structure-function studies. The zebrafish heart has been increasingly used as a model of human cardiac function, in part, due to the similarities in heart rate and action potential duration and morphology with respect to humans. The teleostian zebrafish is in many ways a compelling model of human cardiac function due to the clarity afforded by its ease of genetic manipulation, the wealth of developmental biological information, and inherent suitability to a variety of experimental techniques. However, in addition to the numerous advantages of the zebrafish system are also caveats related to gene duplication (resulting in paralogs not present in human or other mammals) and fundamental differences in how zebrafish hearts function. In this review, we discuss the use of zebrafish as a cardiac function model through the use of techniques such as echocardiography, optical mapping, electrocardiography, molecular investigations of excitation-contraction coupling, and their physiological implications relative to that of the human heart. While some of these techniques (e.g., echocardiography) are particularly challenging in the zebrafish because of diminutive size of the heart (~1.5 mm in diameter) critical information can be derived from these approaches and are discussed in detail in this article.
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Affiliation(s)
- Christine E Genge
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Eric Lin
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Ling Lee
- BC Children's Hospital Research Institute, Vancouver, BC, Canada, V5Z 4H4
| | - XiaoYe Sheng
- BC Children's Hospital Research Institute, Vancouver, BC, Canada, V5Z 4H4
| | - Kaveh Rayani
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Marvin Gunawan
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Charles M Stevens
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6.,BC Children's Hospital Research Institute, Vancouver, BC, Canada, V5Z 4H4
| | - Alison Yueh Li
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Sanam Shafaat Talab
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Thomas W Claydon
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6
| | - Leif Hove-Madsen
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6.,Cardiovascular Research Centre CSIC-ICCC, Hospital de Sant Pau, Barcelona, Spain
| | - Glen F Tibbits
- Molecular Cardiac Physiology Group, Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada, V5A 1S6. .,BC Children's Hospital Research Institute, Vancouver, BC, Canada, V5Z 4H4.
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19
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Li AY, Stevens CM, Liang B, Rayani K, Little S, Davis J, Tibbits GF. Familial hypertrophic cardiomyopathy related cardiac troponin C L29Q mutation alters length-dependent activation and functional effects of phosphomimetic troponin I*. PLoS One 2013; 8:e79363. [PMID: 24260207 PMCID: PMC3832503 DOI: 10.1371/journal.pone.0079363] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [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: 07/31/2013] [Accepted: 09/27/2013] [Indexed: 11/18/2022] Open
Abstract
The Ca(2+) binding properties of the FHC-associated cardiac troponin C (cTnC) mutation L29Q were examined in isolated cTnC, troponin complexes, reconstituted thin filament preparations, and skinned cardiomyocytes. While higher Ca(2+) binding affinity was apparent for the L29Q mutant in isolated cTnC, this phenomenon was not observed in the cTn complex. At the level of the thin filament in the presence of phosphomimetic TnI, L29Q cTnC further reduced the Ca(2+) affinity by 27% in the steady-state measurement and increased the Ca(2+) dissociation rate by 20% in the kinetic studies. Molecular dynamics simulations suggest that L29Q destabilizes the conformation of cNTnC in the presence of phosphomimetic cTnI and potentially modulates the Ca(2+) sensitivity due to the changes of the opening/closing equilibrium of cNTnC. In the skinned cardiomyocyte preparation, L29Q cTnC increased Ca(2+) sensitivity in a highly sarcomere length (SL)-dependent manner. The well-established reduction of Ca(2+) sensitivity by phosphomimetic cTnI was diminished by 68% in the presence of the mutation and it also depressed the SL-dependent increase in myofilament Ca(2+) sensitivity. This might result from its modified interaction with cTnI which altered the feedback effects of cross-bridges on the L29Q cTnC-cTnI-Tm complex. This study demonstrates that the L29Q mutation alters the contractility and the functional effects of the phosphomimetic cTnI in both thin filament and single skinned cardiomyocytes and importantly that this effect is highly sarcomere length dependent.
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Affiliation(s)
- Alison Y. Li
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Charles M. Stevens
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Bo Liang
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kaveh Rayani
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sean Little
- Physiology and Cell Biology, The Ohio State University, Columbia, Ohio, United States of America
| | - Jonathan Davis
- Physiology and Cell Biology, The Ohio State University, Columbia, Ohio, United States of America
| | - Glen F. Tibbits
- Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
- Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
- Cardiovascular Sciences, Child and Family Research Institute, Vancouver, British Columbia, Canada
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