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Ertuglu LA, Mutchler AP, Jamison S, Laffer CL, Saleem M, Blackwell DJ, Kryshtal DO, Sahinoz M, Sheng Q, Wanjalla CN, Pakala S, Justin Y, Gutierrez OM, Kleyman TR, Knollmann BC, Ikizler TA, Kirabo A. Eicosanoid-Regulated Myeloid ENaC and Isolevuglandin Formation in Human Salt-Sensitive Hypertension. Hypertension 2024; 81:516-529. [PMID: 37675576 PMCID: PMC10918035 DOI: 10.1161/hypertensionaha.123.21285] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 03/27/2023] [Accepted: 08/15/2023] [Indexed: 09/08/2023]
Abstract
BACKGROUND The mechanisms by which salt increases blood pressure in people with salt sensitivity remain unclear. Our previous studies found that high sodium enters antigen-presenting cells (APCs) via the epithelial sodium channel and leads to the production of isolevuglandins and hypertension. In the current mechanistic clinical study, we hypothesized that epithelial sodium channel-dependent isolevuglandin-adduct formation in APCs is regulated by epoxyeicosatrienoic acids (EETs) and leads to salt-sensitive hypertension in humans. METHODS Salt sensitivity was assessed in 19 hypertensive subjects using an inpatient salt loading and depletion protocol. Isolevuglandin-adduct accumulation in APCs was analyzed using flow cytometry. Gene expression in APCs was analyzed using cellular indexing of transcriptomes and epitopes by sequencing analysis of blood mononuclear cells. Plasma and urine EETs were measured using liquid chromatography-mass spectrometry. RESULTS Baseline isolevuglandin+ APCs correlated with higher salt-sensitivity index. Isolevuglandin+ APCs significantly decreased from salt loading to depletion with an increasing salt-sensitivity index. We observed that human APCs express the epithelial sodium channel δ subunit, SGK1 (salt-sensing kinase serum/glucocorticoid kinase 1), and cytochrome P450 2S1. We found a direct correlation between baseline urinary 14,15 EET and salt-sensitivity index, whereas changes in urinary 14,15 EET negatively correlated with isolevuglandin+ monocytes from salt loading to depletion. Coincubation with 14,15 EET inhibited high-salt-induced increase in isolevuglandin+ APC. CONCLUSIONS Isolevuglandin formation in APCs responds to acute changes in salt intake in salt-sensitive but not salt-resistant people with hypertension, and this may be regulated by renal 14,15 EET. Baseline levels of isolevuglandin+ APCs or urinary 14,15 EET may provide diagnostic tools for salt sensitivity without a protocol of salt loading.
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Affiliation(s)
- Lale A. Ertuglu
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ashley Pitzer Mutchler
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - S Jamison
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
- Meharry Medical College Nashville, Nashville, TN, United States
| | - Cheryl L. Laffer
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Mohammad Saleem
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Daniel J. Blackwell
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Dmytro O. Kryshtal
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - Melis Sahinoz
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Quanhu Sheng
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Celestine N. Wanjalla
- Department of Internal Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center Nashville, TN, USA
| | - Suman Pakala
- Department of Internal Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center Nashville, TN, USA
| | - Yu Justin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Orlando M Gutierrez
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Thomas R. Kleyman
- Departments of Medicine, Cell Biology, Pharmacology, and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Björn C. Knollmann
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
| | - T. Alp Ikizler
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Annet Kirabo
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center Nashville, TN, USA
- Vanderbilt Center for Immunobiology (VCI)
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4)
- Vanderbilt Institute for Global Health (VIGH)
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2
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Murphy MB, Yang Z, Subati T, Farber-Eger E, Kim K, Blackwell DJ, Fleming MR, Stark JM, Van Amburg JC, Woodall KK, Van Beusecum JP, Agrawal V, Smart CD, Pitzer A, Atkinson JB, Fogo AB, Bastarache JA, Kirabo A, Wells QS, Madhur MS, Barnett JV, Murray KT. LNK/SH2B3 loss of function increases susceptibility to murine and human atrial fibrillation. Cardiovasc Res 2024:cvae036. [PMID: 38377486 DOI: 10.1093/cvr/cvae036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/31/2023] [Accepted: 10/07/2023] [Indexed: 02/22/2024] Open
Abstract
AIMS The lymphocyte adaptor protein (LNK) is a negative regulator of cytokine and growth factor signaling. The rs3184504 variant in SH2B3 reduces LNK function and is linked to cardiovascular, inflammatory, and hematologic disorders including stroke. In mice, deletion of Lnk causes inflammation and oxidative stress. We hypothesized that Lnk-/- mice are susceptible to atrial fibrillation (AF) and that rs3184504 is associated with AF and AF-related stroke in humans. During inflammation, reactive lipid dicarbonyls are a major component of oxidative injury, and we further hypothesized that these mediators are critical drivers of the AF substrate in Lnk-/- mice. METHODS AND RESULTS Lnk-/- or wild-type (WT) mice were treated with vehicle or 2-hydroxybenzylamine (2-HOBA), a dicarbonyl scavenger, for 3 months. Compared to WT, Lnk-/- mice displayed increased AF duration that was prevented by 2-HOBA. In the Lnk-/- atria, action potentials were prolonged with reduced transient outward K+ current, increased late Na+ current, and reduced peak Na+ current, proarrhythmic effects that were inhibited by 2-HOBA. Mitochondrial dysfunction, especially for complex I, was evident in Lnk-/- atria, while scavenging lipid dicarbonyls prevented this abnormality. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were elevated in Lnk-/- plasma and atrial tissue, respectively, both of which caused electrical and bioenergetic remodeling in vitro. Inhibition of soluble TNF-α prevented electrical remodeling and AF susceptibility, while IL-1β inhibition improved mitochondrial respiration but had no effect on AF susceptibility. In a large database of genotyped patients, rs3184504 was associated with AF, as well as AF-related stroke. CONCLUSIONS These findings identify a novel role for LNK in the pathophysiology of AF in both experimental mice and in humans. Moreover, reactive lipid dicarbonyls are critical to the inflammatory AF substrate in Lnk-/- mice and mediate the proarrhythmic effects of pro-inflammatory cytokines, primarily through electrical remodeling.
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Affiliation(s)
- Matthew B Murphy
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Zhenjiang Yang
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Tuerdi Subati
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | | | - Kyungsoo Kim
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Daniel J Blackwell
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | | | - Joshua M Stark
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Joseph C Van Amburg
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Kaylen K Woodall
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Justin P Van Beusecum
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | | | - Charles D Smart
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Ashley Pitzer
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | | | | | | | - Annet Kirabo
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Quinn S Wells
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
- Departments of Medicine, Vanderbilt University School of Medicine, Nashville, TN
| | - Meena S Madhur
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Joey V Barnett
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
| | - Katherine T Murray
- Departments of Medicine, Pharmacology
- Departments of Medicine, Pathology, Microbiology, and Immunology
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3
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Gochman A, Do TQ, Kim K, Schwarz JA, Thorpe MP, Blackwell DJ, Ritschel PA, Smith AN, Rebbeck RT, Akers WS, Cornea RL, Laver DR, Johnston JN, Knollmann BC. ent-Verticilide B1 Inhibits Type 2 Ryanodine Receptor Channels and is Antiarrhythmic in Casq2 -/- Mice. Mol Pharmacol 2024; 105:194-201. [PMID: 38253398 PMCID: PMC10877729 DOI: 10.1124/molpharm.123.000752] [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] [Received: 07/20/2023] [Revised: 12/20/2023] [Accepted: 01/02/2024] [Indexed: 01/24/2024] Open
Abstract
Intracellular Ca2+ leak from cardiac ryanodine receptor (RyR2) is an established mechanism of sudden cardiac death (SCD), whereby dysregulated Ca2+ handling causes ventricular arrhythmias. We previously discovered the RyR2-selective inhibitor ent-(+)-verticilide (ent-1), a 24-membered cyclooligomeric depsipeptide that is the enantiomeric form of a natural product (nat-(-)-verticilide). Here, we examined its 18-membered ring-size oligomer (ent-verticilide B1; "ent-B1") in RyR2 single channel and [3H]ryanodine binding assays, and in Casq2 -/- cardiomyocytes and mice, a gene-targeted model of SCD. ent-B1 inhibited RyR2 single channels and RyR2-mediated spontaneous Ca2+ release in Casq2 -/- cardiomyocytes with sub-micromolar potency. ent-B1 was a partial RyR2 inhibitor, with maximal inhibitory efficacy of less than 50%. ent-B1 was stable in plasma, with a peak plasma concentration of 1460 ng/ml at 10 minutes and half-life of 45 minutes after intraperitoneal administration of 3 mg/kg in mice. In vivo, ent-B1 significantly reduced catecholamine-induced ventricular arrhythmias in Casq2 -/- mice in a dose-dependent manner. Hence, we have identified a novel chemical entity - ent-B1 - that preserves the mechanism of action of a hit compound and shows therapeutic efficacy. These findings strengthen RyR2 as an antiarrhythmic drug target and highlight the potential of investigating the mirror-image isomers of natural products to discover new therapeutics. SIGNIFICANCE STATEMENT: The cardiac ryanodine receptor (RyR2) is an untapped target in the stagnant field of antiarrhythmic drug development. We have confirmed RyR2 as an antiarrhythmic target in a mouse model of sudden cardiac death and shown the therapeutic efficacy of a second enantiomeric natural product.
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Affiliation(s)
- Aaron Gochman
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Tri Q Do
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Kyungsoo Kim
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Jacob A Schwarz
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Madelaine P Thorpe
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Paxton A Ritschel
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Abigail N Smith
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Robyn T Rebbeck
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Wendell S Akers
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Razvan L Cornea
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Derek R Laver
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Jeffrey N Johnston
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (A.G., T.Q.D. K.K., D.J.B., P.A.R., B.C.K.); Vanderbilt Department of Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (M.P.T., A.N.S., J.N.J.); Pharmaceutical Sciences Research Center, Lipscomb University College of Pharmacy, Nashville, Tennessee (W.S.A.); Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (J.A.S., R.L.C., R.T.R.); and School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308, Australia (D.R.L.)
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4
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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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5
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Schmeckpeper J, Kim K, George SA, Blackwell DJ, Brennan JA, Efimov IR, Knollmann BC. RyR2 inhibition with dantrolene is antiarrhythmic, prevents further pathological remodeling, and improves cardiac function in chronic ischemic heart disease. J Mol Cell Cardiol 2023; 181:67-78. [PMID: 37285929 PMCID: PMC10526741 DOI: 10.1016/j.yjmcc.2023.05.009] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 04/30/2023] [Accepted: 05/31/2023] [Indexed: 06/09/2023]
Abstract
Diastolic Ca2+ leak due to cardiac ryanodine receptor (RyR2) hyperactivity has been widely documented in chronic ischemic heart disease (CIHD) and may contribute to ventricular tachycardia (VT) risk and progressive left-ventricular (LV) remodeling. Here we test the hypothesis that targeting RyR2 hyperactivity can suppress VT inducibility and progressive heart failure in CIHD by the RyR2 inhibitor dantrolene. METHODS AND RESULTS: CIHD was induced in C57BL/6 J mice by left coronary artery ligation. Four weeks later, mice were randomized to either acute or chronic (6 weeks via implanted osmotic pump) treatment with dantrolene or vehicle. VT inducibility was assessed by programmed stimulation in vivo and in isolated hearts. Electrical substrate remodeling was assessed by optical mapping. Ca2+ sparks and spontaneous Ca2+ releases were measured in isolated cardiomyocytes. Cardiac remodeling was quantified by histology and qRT-PCR. Cardiac function and contractility were measured using echocardiography. Compared to vehicle, acute dantrolene treatment reduced VT inducibility. Optical mapping demonstrated reentrant VT prevention by dantrolene, which normalized the shortened refractory period (VERP) and prolonged action potential duration (APD), preventing APD alternans. In single CIHD cardiomyocytes, dantrolene normalized RyR2 hyperactivity and prevented spontaneous intracellular Ca2+ release. Chronic dantrolene treatment not only reduced VT inducibility but also reduced peri-infarct fibrosis and prevented further progression of LV dysfunction in CIHD mice. CONCLUSIONS: RyR2 hyperactivity plays a mechanistic role for VT risk, post-infarct remodeling, and contractile dysfunction in CIHD mice. Our data provide proof of concept for the anti-arrhythmic and anti-remodeling efficacy of dantrolene in CIHD.
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Affiliation(s)
- Jeffrey Schmeckpeper
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kyungsoo Kim
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sharon A George
- Department of Biomedical Engineering, the George Washington University, Washington DC, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jaclyn A Brennan
- Department of Biomedical Engineering, the George Washington University, Washington DC, USA
| | - Igor R Efimov
- Department of Biomedical Engineering, the George Washington University, Washington DC, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
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6
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Gochman A, Do TQ, Kim K, Schwarz JA, Thorpe MP, Blackwell DJ, Smith AN, Akers WS, Cornea RL, Laver DR, Johnston JN, Knollmann BC. ent -Verticilide B1 inhibits type 2 ryanodine receptor channels and is antiarrhythmic in Casq2-/- mice. bioRxiv 2023:2023.07.03.547578. [PMID: 37461611 PMCID: PMC10349981 DOI: 10.1101/2023.07.03.547578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Ca 2+ leak from cardiac ryanodine receptor (RyR2) is an established mechanism of sudden cardiac death (SCD), whereby dysregulated Ca 2+ handling causes ventricular arrhythmias. We previously discovered the RyR2-selective inhibitor ent- (+)-verticilide ( ent -1), a 24-membered cyclooligomeric depsipeptide that is the enantiomeric form of a natural product ( nat -(-)-verticilide). Here, we examined its 18-membered ring-size oligomer ( ent -verticilide B1; " ent -B1") in single RyR2 channel assays, [ 3 H]ryanodine binding assays, and in Casq2 -/- cardiomyocytes and mice, a gene-targeted model of SCD. ent -B1 inhibited RyR2 single-channels and [ 3 H]ryanodine binding with low micromolar potency, and RyR2-mediated spontaneous Ca 2+ release in Casq2-/- cardiomyocytes with sub-micromolar potency. ent -B1 was a partial RyR2 inhibitor, with maximal inhibitory efficacy of less than 50%. ent -B1 was stable in plasma, with a peak plasma concentration of 1460 ng/ml at 10 min and half-life of 45 min after intraperitoneal administration of 3 mg/kg in mice. Both 3 mg/kg and 30 mg/kg ent -B1 significantly reduced catecholamine-induced ventricular arrhythmia in Casq2-/- mice. Hence, we have identified a novel chemical entity - ent -B1 - that preserves the mechanism of action of a hit compound and shows therapeutic efficacy. These findings strengthen RyR2 as an antiarrhythmic drug target and highlight the potential of investigating the mirror-image isomers of natural products to discover new therapeutics. Significance statement The cardiac ryanodine receptor (RyR2) is an untapped target in the stagnant field of antiarrhythmic drug development. We have confirmed RyR2 as an antiarrhythmic target in a mouse model of sudden cardiac death and shown the therapeutic efficacy of a second enantiomeric natural product.
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7
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Kim K, Blackwell DJ, Yuen SL, Thorpe MP, Johnston JN, Cornea RL, Knollmann BC. The selective RyR2 inhibitor ent-verticilide suppresses atrial fibrillation susceptibility caused by Pitx2 deficiency. J Mol Cell Cardiol 2023; 180:1-9. [PMID: 37080450 PMCID: PMC10330243 DOI: 10.1016/j.yjmcc.2023.04.005] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/25/2023] [Accepted: 04/17/2023] [Indexed: 04/22/2023]
Abstract
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major cause of stroke and morbidity. The strongest genetic risk factors for AF in humans are variants on chromosome 4q25, near the paired-like homeobox transcription factor 2 gene PITX2. Although mice deficient in Pitx2 (Pitx2+/-) have increased AF susceptibility, the mechanism remains controversial. Recent evidence has implicated hyperactivation of the cardiac ryanodine receptor (RyR2) in Pitx2 deficiency, which may be associated with AF susceptibility. We investigated pacing-induced AF susceptibility and spontaneous Ca2+ release events in Pitx2 haploinsufficient (+/-) mice and isolated atrial myocytes to test the hypothesis that hyperactivity of RyR2 increases susceptibility to AF, which can be prevented by a potent and selective RyR2 channel inhibitor, ent-verticilide. Compared with littermate wild-type Pitx2+/+, the frequency of Ca2+ sparks and spontaneous Ca2+ release events increased in permeabilized and intact atrial myocytes from Pitx2+/- mice. Atrial burst pacing consistently increased the incidence and duration of AF in Pitx2+/- mice. The RyR2 inhibitor ent-verticilide significantly reduced the frequency of spontaneous Ca2+ release in intact atrial myocytes and attenuated AF susceptibility with reduced AF incidence and duration. Our data demonstrate that RyR2 hyperactivity enhances SR Ca2+ leak and AF inducibility in Pitx2+/- mice via abnormal Ca2+ handling. Therapeutic targeting of hyperactive RyR2 in AF using ent-verticilide may be a viable mechanism-based approach to treat atrial arrhythmias caused by Pitx2 deficiency.
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Affiliation(s)
- Kyungsoo Kim
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Samantha L Yuen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Madelaine P Thorpe
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Jeffrey N Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
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8
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Blackwell DJ, Smith AN, Do T, Gochman A, Schmeckpeper J, Hopkins CR, Akers WS, Johnston JN, Knollmann BC. In Vivo Pharmacokinetic and Pharmacodynamic Properties of the Antiarrhythmic Molecule ent-Verticilide. J Pharmacol Exp Ther 2023; 385:205-213. [PMID: 36894328 PMCID: PMC10201578 DOI: 10.1124/jpet.122.001455] [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] [Received: 09/22/2022] [Revised: 02/19/2023] [Accepted: 02/24/2023] [Indexed: 03/11/2023] Open
Abstract
The unnatural verticilide enantiomer (ent-verticilide) is a selective and potent inhibitor of cardiac ryanodine receptor (RyR2) calcium release channels and exhibits antiarrhythmic activity in a murine model of catecholaminergic polymorphic ventricular tachycardia (CPVT). To determine verticilide's pharmacokinetic and pharmacodynamic properties in vivo, we developed a bioassay to measure nat- and ent-verticilide in murine plasma and correlated plasma concentrations with antiarrhythmic efficacy in a mouse model of CPVT. nat-Verticilide rapidly degraded in plasma in vitro, showing >95% degradation within 5 minutes, whereas ent-verticilide showed <1% degradation over 6 hours. Plasma was collected from mice following intraperitoneal administration of ent-verticilide at two doses (3 mg/kg, 30 mg/kg). Peak C max and area under the plasma-concentration time curve (AUC) scaled proportionally to dose, and the half-life was 6.9 hours for the 3-mg/kg dose and 6.4 hours for the 30-mg/kg dose. Antiarrhythmic efficacy was examined using a catecholamine challenge protocol at time points ranging from 5 to 1440 minutes after intraperitoneal dosing. ent-Verticilide inhibited ventricular arrhythmias as early as 7 minutes after administration in a concentration-dependent manner, with an estimated potency (IC50) of 266 ng/ml (312 nM) and an estimated maximum inhibitory effect of 93.5%. Unlike the US Food and Drug Administration-approved pan-RyR blocker dantrolene, the RyR2-selective blocker ent-verticilide (30 mg/kg) did not reduce skeletal muscle strength in vivo. We conclude that ent-verticilide has favorable pharmacokinetic properties and reduces ventricular arrhythmias with an estimated potency in the nanomolar range, warranting further drug development. SIGNIFICANCE STATEMENT: ent-Verticilide has therapeutic potential to treat cardiac arrhythmias, but little is known about its pharmacological profile in vivo. The primary purpose of this study is to determine the systemic exposure and pharmacokinetics of ent-verticilide in mice and estimate its efficacy and potency in vivo. The current work suggests ent-verticilide has favorable pharmacokinetic properties and reduces ventricular arrhythmias with an estimated potency in the nanomolar range, warranting further drug development.
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Affiliation(s)
- Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Abigail N Smith
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Tri Do
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Aaron Gochman
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jeffrey Schmeckpeper
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Corey R Hopkins
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Wendell S Akers
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jeffrey N Johnston
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Bjorn C Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (D.J.B., J.S., B.C.K.); Departments of Chemistry (A.N.S., J.N.J.) and Pharmacology (A.G., W.S.A), and Vanderbilt Institute of Chemical Biology (A.N.S., J.N.J.), Vanderbilt University, Nashville, Tennessee; Pharmaceutical Sciences Research Center, Lipscomb University, Nashville, Tennessee (T.D., W.S.A); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
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9
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Muhammad A, Calandranis ME, Li B, Yang T, Blackwell DJ, Harvey ML, Smith JE, Chew AE, Capra JA, Matreyek KA, Fowler DM, Roden DM, Glazer AM. High-throughput functional mapping of variants in an arrhythmia gene, KCNE1, reveals novel biology. bioRxiv 2023:2023.04.28.538612. [PMID: 37162834 PMCID: PMC10168370 DOI: 10.1101/2023.04.28.538612] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Background KCNE1 encodes a 129-residue cardiac potassium channel (IKs) subunit. KCNE1 variants are associated with long QT syndrome and atrial fibrillation. However, most variants have insufficient evidence of clinical consequences and thus limited clinical utility. Results Here, we demonstrate the power of variant effect mapping, which couples saturation mutagenesis with high-throughput sequencing, to ascertain the function of thousands of protein coding KCNE1 variants. We comprehensively assayed KCNE1 variant cell surface expression (2,554/2,709 possible single amino acid variants) and function (2,539 variants). We identified 470 loss-of-surface expression and 588 loss-of-function variants. Out of the 588 loss-of-function variants, only 155 had low cell surface expression. The latter half of the protein is dispensable for protein trafficking but essential for channel function. 22 of the 30 KCNE1 residues (73%) highly intolerant of variation were in predicted close contact with binding partners KCNQ1 or calmodulin. Our data were highly concordant with gold standard electrophysiological data (ρ = -0.65), population and patient cohorts (32/38 concordant variants), and computational metrics (ρ = -0.55). Our data provide moderate-strength evidence for the ACMG/AMP functional criteria for benign and pathogenic variants. Conclusions Comprehensive variant effect maps of KCNE1 can both provide insight into IKs channel biology and help reclassify variants of uncertain significance.
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Affiliation(s)
- Ayesha Muhammad
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Medical Scientist Training Program, Vanderbilt University, Nashville, TN 37232, USA
| | - Maria E. Calandranis
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Bian Li
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Daniel J. Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - M. Lorena Harvey
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jeremy E. Smith
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Ashli E. Chew
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John A. Capra
- Bakar Computational Health Sciences Institute and Department of Epidemiology and Biostatistics, University of California, San Francisco, CA 94143, USA
| | - Kenneth A. Matreyek
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Douglas M. Fowler
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Dan M. Roden
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Andrew M. Glazer
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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10
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Smith A, Thorpe MP, Blackwell DJ, Batiste SM, Hopkins CR, Schley ND, Knollmann BC, Johnston JN. Structure-Activity Relationships for the N-Me- Versus N-H-Amide Modification to Macrocyclic ent-Verticilide Antiarrhythmics. ACS Med Chem Lett 2022; 13:1755-1762. [PMID: 36385927 PMCID: PMC9661706 DOI: 10.1021/acsmedchemlett.2c00377] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/29/2022] [Indexed: 11/28/2022] Open
Abstract
The synthesis of all N-Me and N-H analogues of ent-verticilide is described, enabling a structure-activity relationship study based on cardiac ryanodine receptor (RyR2) calcium ion channel inhibition. The use of permeabilized cardiomyocytes allowed us to correlate the degree of N-methylation with activity without concern for changes in passive membrane permeability that these modifications can cause. A key hypothesis was that the minimal pharmacophore may be repeated in this cyclic oligomeric octadepsipeptide (a 24-membered macrocycle), opening the possibility that target engagement will not necessarily be lost with a single N-Me → N-H modification. The effect in the corresponding 18-membered ring oligomer (ent-verticilide B1) was also investigated. We report here that a high degree of N-methyl amide content is critical for activity in the ent-verticilide series but not entirely so for the ent-verticilide B1 series.
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Affiliation(s)
- Abigail
N. Smith
- Department
of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville 37235, Tennessee, United States
| | - Madelaine P. Thorpe
- Department
of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville 37235, Tennessee, United States
| | - Daniel J. Blackwell
- Department
of Medicine, Vanderbilt University Medical
Center, Nashville 37235, Tennessee, United States
| | - Suzanne M. Batiste
- Department
of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville 37235, Tennessee, United States
| | - Corey R. Hopkins
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha 68198, Nebraska, United States
| | - Nathan D. Schley
- Department
of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville 37235, Tennessee, United States
| | - Bjorn C. Knollmann
- Department
of Medicine, Vanderbilt University Medical
Center, Nashville 37235, Tennessee, United States
| | - Jeffrey N. Johnston
- Department
of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville 37235, Tennessee, United States
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11
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Abstract
BACKGROUND Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a potentially lethal cardiac arrhythmia syndrome triggered by catecholamines released during exercise, stress, or sudden emotion. Variants in the calsequestrin-2 gene (CASQ2), encoding the major calcium (Ca) binding protein in the sarcoplasmic reticulum (SR), are the second most common cause of CPVT. Recently, several CASQ2 gene variants, such as CASQ2-K180R, have been linked to an autosomal dominant form of Casq2-linked CPVT (CPVT2), but the underlying mechanism is not known. METHODS A K180R mouse model was generated using CRIPSR/Cas9. Heterozygous and homozygous K180R mice were studied using telemetry ECG recordings in vivo. Ventricular cardiomyocytes were isolated and studied using fluorescent Ca indicators and patch clamp. Expression levels and localization of SR Ca-handling proteins were evaluated using Western blotting and immunostaining. Intra-SR Ca kinetics were quantified using low-affinity Ca indicators. RESULTS K180R mice exhibit an autosomal dominant CPVT phenotype following exercise or catecholamine stress. Upon catecholamine stress, K180R ventricular cardiomyocytes exhibit increased spontaneous SR Ca release events, triggering delayed afterdepolarizations and spontaneous beats. K180R had no effect on levels of Casq2, Casq2 polymers, or other SR Ca-handling proteins. Intra-SR Ca measurements revealed that K180R impaired dynamic intra-SR Ca buffering, resulting in a more rapid rise of free Ca in the SR during diastole. Steady-state SR Ca buffering and total SR Ca content were not changed. Consistent with the reduced dynamic intra-SR buffering, K180R causes reduced SR Ca release refractoriness. CONCLUSIONS CASQ2-K180R causes CPVT2 via a heretofore unknown mechanism that differs from CASQ2 variants associated with autosomal recessive CPVT2. Unlike autosomal recessive CASQ2 variants, K180R impairs the dynamic buffering of Ca within the SR without affecting total SR Ca content or Casq2 protein levels. Our data provide insight into the molecular mechanism underlying autosomal dominant CPVT2.
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Affiliation(s)
- Matthew J Wleklinski
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
| | - Dmytro O Kryshtal
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
| | - Kyungsoo Kim
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
| | - Shan S Parikh
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
| | - Isabelle Marty
- University Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, Grenoble, France (I.M.)
| | - V Ramesh Iyer
- Division of Cardiology, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania (V.R.I.)
| | - Bjӧrn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (M.J.W., D.O.K., K.K., S.S.P., D.J.B., B.C.K.)
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12
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Blackwell DJ, Schmeckpeper J, Knollmann BC. Animal Models to Study Cardiac Arrhythmias. Circ Res 2022; 130:1926-1964. [PMID: 35679367 DOI: 10.1161/circresaha.122.320258] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.
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Affiliation(s)
- Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Jeffrey Schmeckpeper
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
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13
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van Opbergen CJM, Bagwan N, Maurya SR, Kim JC, Smith AN, Blackwell DJ, Johnston JN, Knollmann BC, Cerrone M, Lundby A, Delmar M. Exercise Causes Arrhythmogenic Remodeling of Intracellular Calcium Dynamics in Plakophilin-2-Deficient Hearts. Circulation 2022; 145:1480-1496. [PMID: 35491884 PMCID: PMC9086182 DOI: 10.1161/circulationaha.121.057757] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Exercise training, and catecholaminergic stimulation, increase the incidence of arrhythmic events in patients affected with arrhythmogenic right ventricular cardiomyopathy correlated with plakophilin-2 (PKP2) mutations. Separate data show that reduced abundance of PKP2 leads to dysregulation of intracellular Ca2+ (Ca2+i) homeostasis. Here, we study the relation between excercise, catecholaminergic stimulation, Ca2+i homeostasis, and arrhythmogenesis in PKP2-deficient murine hearts. METHODS Experiments were performed in myocytes from a cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout murine line (PKP2cKO). For training, mice underwent 75 minutes of treadmill running once per day, 5 days each week for 6 weeks. We used multiple approaches including imaging, high-resolution mass spectrometry, electrocardiography, and pharmacological challenges to study the functional properties of cells/hearts in vitro and in vivo. RESULTS In myocytes from PKP2cKO animals, training increased sarcoplasmic reticulum Ca2+ load, increased the frequency and amplitude of spontaneous ryanodine receptor (ryanodine receptor 2)-mediated Ca2+ release events (sparks), and changed the time course of sarcomeric shortening. Phosphoproteomics analysis revealed that training led to hyperphosphorylation of phospholamban in residues 16 and 17, suggesting a catecholaminergic component. Isoproterenol-induced increase in Ca2+i transient amplitude showed a differential response to β-adrenergic blockade that depended on the purported ability of the blockers to reach intracellular receptors. Additional experiments showed significant reduction of isoproterenol-induced Ca2+i sparks and ventricular arrhythmias in PKP2cKO hearts exposed to an experimental blocker of ryanodine receptor 2 channels. CONCLUSIONS Exercise disproportionately affects Ca2+i homeostasis in PKP2-deficient hearts in a manner facilitated by stimulation of intracellular β-adrenergic receptors and hyperphosphorylation of phospholamban. These cellular changes create a proarrhythmogenic state that can be mitigated by ryanodine receptor 2 blockade. Our data unveil an arrhythmogenic mechanism for exercise-induced or catecholaminergic life-threatening arrhythmias in the setting of PKP2 deficit. We suggest that membrane-permeable β-blockers are potentially more efficient for patients with arrhythmogenic right ventricular cardiomyopathy, highlight the potential for ryanodine receptor 2 channel blockers as treatment for the control of heart rhythm in the population at risk, and propose that PKP2-dependent and phospholamban-dependent arrhythmogenic right ventricular cardiomyopathy-related arrhythmias have a common mechanism.
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Affiliation(s)
- Chantal JM van Opbergen
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Navratan Bagwan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Svetlana R Maurya
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joon-Chul Kim
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Abigail N Smith
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey N Johnston
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Marina Cerrone
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
| | - Alicia Lundby
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mario Delmar
- The Leon Charney Division of Cardiology, New York University Grossmann School of Medicine, New York, NY, USA
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14
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Egly CL, Blackwell DJ, Schmeckpeper J, Delisle BP, Weaver CD, Knollmann BC. A High-Throughput Screening Assay to Identify Drugs that Can Treat Long QT Syndrome Caused by Trafficking-Deficient K V11.1 (hERG) Variants. Mol Pharmacol 2022; 101:236-245. [PMID: 35125346 PMCID: PMC9638947 DOI: 10.1124/molpharm.121.000421] [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] [Received: 10/04/2021] [Accepted: 01/01/2022] [Indexed: 11/22/2022] Open
Abstract
Loss-of-function (LOF) variants in the KV11.1 potassium channel cause long QT syndrome (LQTS). Most variants disrupt intracellular channel transport (trafficking) to the cell membrane. Since some channel inhibitors improve trafficking of KV11.1 variants, a high-throughput screening (HTS) assay to detect trafficking enhancement would be valuable to the identification of drug candidates. The thallium (Tl+) flux assay technique, widely used for drug screening, was optimized using human embryonic kidney (HEK-293) cells expressing a trafficking-deficient KV11.1 variant in 384-well plates. Assay quality was assessed using Z prime (Z') scores comparing vehicle to E-4031, a drug that increases KV11.1 membrane trafficking. The optimized assay was validated by immunoblot, electrophysiology experiments, and a pilot drug screen. The combination of: 1) truncating the trafficking-deficient variant KV11.1-G601S (KV11.1-G601S-G965*X) with the addition of 2) KV11.1 channel activator (VU0405601) and 3) cesium (Cs+) to the Tl+ flux assay buffer resulted in an outstanding Z' of 0.83. To validate the optimized trafficking assay, we carried out a pilot screen that identified three drugs (ibutilide, azaperone, and azelastine) that increase KV11.1 trafficking. The new assay exhibited 100% sensitivity and specificity. Immunoblot and voltage-clamp experiments confirmed that all three drugs identified by the new assay improved membrane trafficking of two additional LQTS KV11.1 variants. We report two new ways to increase target-specific activity in trafficking assays-genetic modification and channel activation-that yielded a novel HTS assay for identifying drugs that improve membrane expression of pathogenic KV11.1 variants. SIGNIFICANCE STATEMENT: This manuscript reports the development of a high-throughput assay (thallium flux) to identify drugs that can increase function in KV11.1 variants that are trafficking-deficient. Two key aspects that improved the resolving power of the assay and could be transferable to other ion channel trafficking-related assays include genetic modification and channel activation.
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Affiliation(s)
- Christian L Egly
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Jeffrey Schmeckpeper
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Brian P Delisle
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - C David Weaver
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Björn C Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee (C.L.E., D.J.B., J.S., B.C.K.); Department of Physiology, University of Kentucky, Lexington, Kentucky (B.P.D.); and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
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15
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Blackwell DJ, Faggioni M, Wleklinski MJ, Gomez-Hurtado N, Venkataraman R, Gibbs CE, Baudenbacher FJ, Gong S, Fishman GI, Boyle PM, Pfeifer K, Knollmann BC. The Purkinje-myocardial junction is the anatomic origin of ventricular arrhythmia in CPVT. JCI Insight 2022; 7:e151893. [PMID: 34990403 PMCID: PMC8855823 DOI: 10.1172/jci.insight.151893] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [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: 06/01/2021] [Accepted: 12/21/2021] [Indexed: 11/17/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmia syndrome caused by gene mutations that render RYR2 Ca release channels hyperactive, provoking spontaneous Ca release and delayed afterdepolarizations (DADs). What remains unknown is the cellular source of ventricular arrhythmia triggered by DADs: Purkinje cells in the conduction system or ventricular cardiomyocytes in the working myocardium. To answer this question, we used a genetic approach in mice to knock out cardiac calsequestrin either in Purkinje cells or in ventricular cardiomyocytes. Total loss of calsequestrin in the heart causes a severe CPVT phenotype in mice and humans. We found that loss of calsequestrin only in ventricular myocytes produced a full-blown CPVT phenotype, whereas mice with loss of calsequestrin only in Purkinje cells were comparable to WT mice. Subendocardial chemical ablation or restoration of calsequestrin expression in subendocardial cardiomyocytes neighboring Purkinje cells was sufficient to protect against catecholamine-induced arrhythmias. In silico modeling demonstrated that DADs in ventricular myocardium can trigger full action potentials in the Purkinje fiber, but not vice versa. Hence, ectopic beats in CPVT are likely generated at the Purkinje-myocardial junction via a heretofore unrecognized tissue mechanism, whereby DADs in the ventricular myocardium trigger full action potentials in adjacent Purkinje cells.
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Affiliation(s)
- Daniel J. Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Michela Faggioni
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Matthew J. Wleklinski
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Department of Pharmacology and
| | - Nieves Gomez-Hurtado
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Raghav Venkataraman
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Chelsea E. Gibbs
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Franz J. Baudenbacher
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Shiaoching Gong
- Laboratory of Molecular Biology, Rockefeller University, New York, New York, USA
| | - Glenn I. Fishman
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, New York, USA
| | - Patrick M. Boyle
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
- Institute for Stem Cell and Regenerative Medicine and
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington, USA
| | - Karl Pfeifer
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland, USA
| | - Bjorn C. Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Department of Pharmacology and
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16
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Smith AN, Blackwell DJ, Knollmann BC, Johnston JN. Ring Size as an Independent Variable in Cyclooligomeric Depsipeptide Antiarrhythmic Activity. ACS Med Chem Lett 2021; 12:1942-1947. [PMID: 34917258 DOI: 10.1021/acsmedchemlett.1c00508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022] Open
Abstract
Hit-to-lead studies employ a variety of strategies to optimize binding to a target of interest. When a structure for the target is available, hypothesis-driven structure-activity relationships (SAR) are a powerful strategy for refining the pharmacophore to achieve robust binding and selectivity characteristics necessary to identify a lead compound. Recrafting the three-dimensional space occupied by a small molecule, optimization of hydrogen bond contacts, and enhancing local attractive interactions are traditional approaches in medicinal chemistry. Ring size, however, is rarely able to be leveraged as an independent variable because most hits lack the symmetry required for such a study. Our discovery that the cyclic oligomeric depsipeptide ent-verticilide inhibits mammalian cardiac ryanodine receptor calcium release channels with submicromolar potency provided an opportunity to explore ring size as a variable, independent of other structural or functional group changes. We report here that ring size can be a critical independent variable, suggesting that modest conformational changes alone can dramatically affect potency.
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Affiliation(s)
- Abigail N. Smith
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Daniel J. Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Bjorn C. Knollmann
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37235, United States
| | - Jeffrey N. Johnston
- Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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17
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Kim K, Schmeckpeper J, Blackwell DJ, Knollmann BC. B-PO01-017 RYR2 HYPERACTIVITY PROMOTES SUSCEPTIBILITY TO VENTRICULAR TACHYCARDIA IN STRUCTURAL HEART DISEASE. Heart Rhythm 2021. [DOI: 10.1016/j.hrthm.2021.06.163] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Abstract
RATIONALE The class Ic antiarrhythmic drug flecainide prevents ventricular tachyarrhythmia in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), a disease caused by hyperactive RyR2 (cardiac ryanodine receptor) mediated calcium (Ca) release. Although flecainide inhibits single RyR2 channels in vitro, reports have claimed that RyR2 inhibition by flecainide is not relevant for its mechanism of antiarrhythmic action and concluded that sodium channel block alone is responsible for flecainide's efficacy in CPVT. OBJECTIVE To determine whether RyR2 block independently contributes to flecainide's efficacy for suppressing spontaneous sarcoplasmic reticulum Ca release and for preventing ventricular tachycardia in vivo. METHODS AND RESULTS We synthesized N-methylated flecainide analogues (QX-flecainide and N-methyl flecainide) and showed that N-methylation reduces flecainide's inhibitory potency on RyR2 channels incorporated into artificial lipid bilayers. N-methylation did not alter flecainide's inhibitory activity on human cardiac sodium channels expressed in HEK293T cells. Antiarrhythmic efficacy was tested utilizing a Casq2 (cardiac calsequestrin) knockout (Casq2-/-) CPVT mouse model. In membrane-permeabilized Casq2-/- cardiomyocytes-lacking intact sarcolemma and devoid of sodium channel contribution-flecainide, but not its analogues, suppressed RyR2-mediated Ca release at clinically relevant concentrations. In voltage-clamped, intact Casq2-/- cardiomyocytes pretreated with tetrodotoxin to inhibit sodium channels and isolate the effect of flecainide on RyR2, flecainide significantly reduced the frequency of spontaneous sarcoplasmic reticulum Ca release, while QX-flecainide and N-methyl flecainide did not. In vivo, flecainide effectively suppressed catecholamine-induced ventricular tachyarrhythmias in Casq2-/- mice, whereas N-methyl flecainide had no significant effect on arrhythmia burden, despite comparable sodium channel block. CONCLUSIONS Flecainide remains an effective inhibitor of RyR2-mediated arrhythmogenic Ca release even when cardiac sodium channels are blocked. In mice with CPVT, sodium channel block alone did not prevent ventricular tachycardia. Hence, RyR2 channel inhibition likely constitutes the principal mechanism of antiarrhythmic action of flecainide in CPVT.
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Affiliation(s)
- Dmytro O Kryshtal
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Christian L Egly
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
| | - Abigail N Smith
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Suzanne M Batiste
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Jeffrey N Johnston
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN (A.N.S., S.M.B., J.N.J.)
| | - Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, Australia (D.R.L.)
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN (D.O.K., D.J.B., C.L.E., B.C.K.)
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19
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Blackwell DJ, Knollmann BC. SPEG Kinase: Hitting the Brake in Atrial Fibrillation. Circulation 2020; 142:1173-1175. [PMID: 32955933 DOI: 10.1161/circulationaha.120.050226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Björn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN
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20
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Kryshtal DO, Blackwell DJ, Smith AN, Batiste SM, Johnston JN, Knollmann BC. RyR2 Inhibition by Flecainide Determines Antiarrhythmic Activity in CPVT. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3090] [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: 10/25/2022] Open
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21
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Larsen EK, Weber DK, Wang S, Gopinath T, Blackwell DJ, Dalton MP, Robia SL, Gao J, Veglia G. Intrinsically disordered HAX-1 regulates Ca 2+ cycling by interacting with lipid membranes and the phospholamban cytoplasmic region. Biochim Biophys Acta Biomembr 2020; 1862:183034. [PMID: 31400305 PMCID: PMC6899184 DOI: 10.1016/j.bbamem.2019.183034] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/09/2019] [Accepted: 07/30/2019] [Indexed: 01/14/2023]
Abstract
Hematopoietic-substrate-1 associated protein X-1 (HAX-1) is a 279 amino acid protein expressed ubiquitously. In cardiac muscle, HAX-1 was found to modulate the sarcoendoplasmic reticulum calcium ATPase (SERCA) by shifting its apparent Ca2+ affinity (pCa). It has been hypothesized that HAX-1 binds phospholamban (PLN), enhancing its inhibitory function on SERCA. HAX-1 effects are reversed by cAMP-dependent protein kinase A that phosphorylates PLN at Ser16. To date, the molecular mechanisms for HAX-1 regulation of the SERCA/PLN complex are still unknown. Using enzymatic, in cell assays, circular dichroism, and NMR spectroscopy, we found that in the absence of a binding partner HAX-1 is essentially disordered and adopts a partial secondary structure upon interaction with lipid membranes. Also, HAX-1 interacts with the cytoplasmic region of monomeric and pentameric PLN as detected by NMR and in cell FRET assays, respectively. We propose that the regulation of the SERCA/PLN complex by HAX-1 is mediated by its interactions with lipid membranes, adding another layer of control in Ca2+ homeostatic balance in the heart muscle.
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Affiliation(s)
- Erik K Larsen
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Michael P Dalton
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Seth L Robia
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Jiali Gao
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; School of Chemical Biology and Technology, Beijing University Graduate School, Shenzhen 518055, China
| | - Gianluigi Veglia
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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22
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Johnson CN, Pattanayek R, Potet F, Rebbeck RT, Blackwell DJ, Nikolaienko R, Sequeira V, Le Meur R, Radwański PB, Davis JP, Zima AV, Cornea RL, Damo SM, Györke S, George AL, Knollmann BC. The CaMKII inhibitor KN93-calmodulin interaction and implications for calmodulin tuning of Na V1.5 and RyR2 function. Cell Calcium 2019; 82:102063. [PMID: 31401388 DOI: 10.1016/j.ceca.2019.102063] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/15/2019] [Accepted: 07/26/2019] [Indexed: 02/06/2023]
Abstract
Here we report the structure of the widely utilized calmodulin (CaM)-dependent protein kinase II (CaMKII) inhibitor KN93 bound to the Ca2+-sensing protein CaM. KN93 is widely believed to inhibit CaMKII by binding to the kinase. The CaM-KN93 interaction is significant as it can interfere with the interaction between CaM and it's physiological targets, thereby raising the possibility of ascribing modified protein function to CaMKII phosphorylation while concealing a CaM-protein interaction. NMR spectroscopy, stopped-flow kinetic measurements, and x-ray crystallography were used to characterize the structure and biophysical properties of the CaM-KN93 interaction. We then investigated the functional properties of the cardiac Na+ channel (NaV1.5) and ryanodine receptor (RyR2). We find that KN93 disrupts a high affinity CaM-NaV1.5 interaction and alters channel function independent of CaMKII. Moreover, KN93 increases RyR2 Ca2+ release in cardiomyocytes independent of CaMKII. Therefore, when interpreting KN93 data, targets other than CaMKII need to be considered.
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Affiliation(s)
- Christopher N Johnson
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA; Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
| | - Rekha Pattanayek
- Department of Life and Physical Sciences, Fisk University, Nashville, TN 37208, USA
| | - Franck Potet
- Department of Pharmacology Feinberg School of Medicine, Northwestern University, Chicago IL, 60611, USA
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel J Blackwell
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood IL, 60153, USA
| | - Vasco Sequeira
- Department of Translational Science Universitätsklinikum, Würzburg, Germany
| | - Remy Le Meur
- Department of Biochemistry, Vanderbilt University, Nashville TN 37204, USA
| | - Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jonathan P Davis
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University, Maywood IL, 60153, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics University of Minnesota, Minneapolis, MN 55455, USA
| | - Steven M Damo
- Department of Life and Physical Sciences, Fisk University, Nashville, TN 37208, USA
| | - Sandor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Alfred L George
- Department of Pharmacology Feinberg School of Medicine, Northwestern University, Chicago IL, 60611, USA
| | - Björn C Knollmann
- Center for Arrhythmia Research and Therapeutics, Vanderbilt University Medical Center, Nashville, TN 37240, USA
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23
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Chavali NV, Kryshtal DO, Parikh SS, Wang L, Glazer AM, Blackwell DJ, Kroncke BM, Shoemaker MB, Knollmann BC. Patient-independent human induced pluripotent stem cell model: A new tool for rapid determination of genetic variant pathogenicity in long QT syndrome. Heart Rhythm 2019; 16:1686-1695. [PMID: 31004778 DOI: 10.1016/j.hrthm.2019.04.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [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] [Received: 12/07/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Commercial genetic testing for long QT syndrome (LQTS) has rapidly expanded, but the inability to accurately predict whether a rare variant is pathogenic has limited its clinical benefit. Novel missense variants are routinely reported as variant of unknown significance (VUS) and cannot be used to screen family members at risk for sudden cardiac death. Better approaches to determine the pathogenicity of VUS are needed. OBJECTIVE The purpose of this study was to rapidly determine the pathogenicity of a CACNA1C variant reported by commercial genetic testing as a VUS using a patient-independent human induced pluripotent stem cell (hiPSC) model. METHODS Using CRISPR/Cas9 genome editing, CACNA1C-p.N639T was introduced into a previously established hiPSC from an unrelated healthy volunteer, thereby generating a patient-independent hiPSC model. Three independent heterozygous N639T hiPSC lines were generated and differentiated into cardiomyocytes (CM). Electrophysiological properties of N639T hiPSC-CM were compared to those of isogenic and population control hiPSC-CM by measuring the extracellular field potential (EFP) of 96-well hiPSC-CM monolayers and by patch clamp. RESULTS Significant EFP prolongation was observed only in optically stimulated but not in spontaneously beating N639T hiPSC-CM. Patch-clamp studies revealed that N639T prolonged the ventricular action potential by slowing voltage-dependent inactivation of CaV1.2 currents. Heterologous expression studies confirmed the effect of N639T on CaV1.2 inactivation. CONCLUSION The patient-independent hiPSC model enabled rapid generation of functional data to support reclassification of a CACNA1C VUS to likely pathogenic, thereby establishing a novel LQTS type 8 mutation. Furthermore, our results indicate the importance of controlling beating rates to evaluate the functional significance of LQTS VUS in high-throughput hiPSC-CM assays.
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Affiliation(s)
- Nikhil V Chavali
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Dmytro O Kryshtal
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Shan S Parikh
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Lili Wang
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Andrew M Glazer
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Brett M Kroncke
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Moore Benjamin Shoemaker
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee
| | - Bjorn C Knollmann
- Vanderbilt University School of Medicine, Nashville, Tennessee; Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine, Nashville, Tennessee.
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Parikh SS, Blackwell DJ, Gomez-Hurtado N, Frisk M, Wang L, Kim K, Dahl CP, Fiane A, Tønnessen T, Kryshtal DO, Louch WE, Knollmann BC. Thyroid and Glucocorticoid Hormones Promote Functional T-Tubule Development in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Circ Res 2017; 121:1323-1330. [PMID: 28974554 DOI: 10.1161/circresaha.117.311920] [Citation(s) in RCA: 254] [Impact Index Per Article: 36.3] [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] [Received: 08/29/2017] [Revised: 09/26/2017] [Accepted: 10/02/2017] [Indexed: 12/16/2022]
Abstract
RATIONALE Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are increasingly being used for modeling heart disease and are under development for regeneration of the injured heart. However, incomplete structural and functional maturation of hiPSC-CM, including lack of T-tubules, immature excitation-contraction coupling, and inefficient Ca-induced Ca release remain major limitations. OBJECTIVE Thyroid and glucocorticoid hormones are critical for heart maturation. We hypothesized that their addition to standard protocols would promote T-tubule development and mature excitation-contraction coupling of hiPSC-CM when cultured on extracellular matrix with physiological stiffness (Matrigel mattress). METHODS AND RESULTS hiPSC-CM were generated using a standard chemical differentiation method supplemented with T3 (triiodothyronine) and/or Dex (dexamethasone) during days 16 to 30 followed by single-cell culture for 5 days on Matrigel mattress. hiPSC-CM treated with T3+Dex, but not with either T3 or Dex alone, developed an extensive T-tubule network. Notably, Matrigel mattress was necessary for T-tubule formation. Compared with adult human ventricular cardiomyocytes, T-tubules in T3+Dex-treated hiPSC-CM were less organized and had more longitudinal elements. Confocal line scans demonstrated spatially and temporally uniform Ca release that is characteristic of excitation-contraction coupling in the heart ventricle. T3+Dex enhanced elementary Ca release measured by Ca sparks and promoted RyR2 (ryanodine receptor) structural organization. Simultaneous measurements of L-type Ca current and intracellular Ca release confirmed enhanced functional coupling between L-type Ca channels and RyR2 in T3+Dex-treated cells. CONCLUSIONS Our results suggest a permissive role of combined thyroid and glucocorticoid hormones during the cardiac differentiation process, which when coupled with further maturation on Matrigel mattress, is sufficient for T-tubule development, enhanced Ca-induced Ca release, and more ventricular-like excitation-contraction coupling. This new hormone maturation method could advance the use of hiPSC-CM for disease modeling and cell-based therapy.
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Affiliation(s)
- Shan S Parikh
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Daniel J Blackwell
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Nieves Gomez-Hurtado
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Michael Frisk
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Lili Wang
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Kyungsoo Kim
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Christen P Dahl
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Arnt Fiane
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Theis Tønnessen
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Dmytro O Kryshtal
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - William E Louch
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.)
| | - Bjorn C Knollmann
- From the Vanderbilt Center for Arrhythmia Research and Therapeutics, Department of Medicine (S.S.P., D.J.B., N.G.-H., L.W., K.K., D.O.K., B.C.K.), Department of Pharmacology (S.S.P., B.C.K.), Vanderbilt University Medical School, Nashville, TN; Institute for Experimental Medical Research, Oslo University Hospital, Norway (M.F., T.T., W.E.L.); University of Oslo, Norway (M.F., T.T., W.E.L.); Department of Cardiology (C.P.D.), and Department of Cardiothoracic Surgery (A.F.), Oslo University Hospital Rikshospitalet, Norway; and Oslo University Hospital Ullevål, Norway (T.T.).
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Blackwell DJ, Zak TJ, Robia SL. Cardiac Calcium ATPase Dimerization Measured by Cross-Linking and Fluorescence Energy Transfer. Biophys J 2017; 111:1192-1202. [PMID: 27653478 DOI: 10.1016/j.bpj.2016.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 07/13/2016] [Accepted: 08/01/2016] [Indexed: 12/21/2022] Open
Abstract
The cardiac sarco/endoplasmic reticulum calcium ATPase (SERCA) establishes the intracellular calcium gradient across the sarcoplasmic reticulum membrane. It has been proposed that SERCA forms homooligomers that increase the catalytic rate of calcium transport. We investigated SERCA dimerization in rabbit left ventricular myocytes using a photoactivatable cross-linker. Western blotting of cross-linked SERCA revealed higher-molecular-weight species consistent with SERCA oligomerization. Fluorescence resonance energy transfer measurements in cells transiently transfected with fluorescently labeled SERCA2a revealed that SERCA readily forms homodimers. These dimers formed in the absence or presence of the SERCA regulatory partner, phospholamban (PLB) and were unaltered by PLB phosphorylation or changes in calcium or ATP. Fluorescence lifetime data are compatible with a model in which PLB interacts with a SERCA homodimer in a stoichiometry of 1:2. Together, these results suggest that SERCA forms constitutive homodimers in live cells and that dimer formation is not modulated by SERCA conformational poise, PLB binding, or PLB phosphorylation.
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Affiliation(s)
- Daniel J Blackwell
- Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois
| | - Taylor J Zak
- Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois
| | - Seth L Robia
- Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois.
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Hou Z, Hu Z, Blackwell DJ, Miller TD, Thomas DD, Robia SL. 2-Color calcium pump reveals closure of the cytoplasmic headpiece with calcium binding. PLoS One 2012; 7:e40369. [PMID: 22808146 PMCID: PMC3394785 DOI: 10.1371/journal.pone.0040369] [Citation(s) in RCA: 34] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/07/2012] [Indexed: 11/19/2022] Open
Abstract
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) undergoes conformational changes while transporting calcium, but the details of the domain motions are still unclear. The objective of the present study was to measure distances between the cytoplasmic domains of SERCA2a in order to reveal the magnitude and direction of conformational changes. Using fluorescence microscopy of live cells, we measured intramolecular fluorescence resonance energy transfer (FRET) from a donor fluorescent protein fused to the SERCA N-terminus to an acceptor fluorescent protein fused to either the N-, P-, or transmembrane domain. The "2-color" SERCA constructs were catalytically active as indicated by ATPase activity in vitro and Ca uptake in live cells. All constructs exhibited dynamic FRET changes in response to the pump ligands calcium and thapsigargin (Tg). These FRET changes were quantified as an index of SERCA conformational changes. Intramolecular FRET decreased with Tg for the two N-domain fusion sites (at residue 509 or 576), while the P- (residue 661) and TM-domain (C-terminus) fusions showed increased FRET with Tg. The magnitude of the Tg-dependent conformational change was not decreased by coexpression of phospholamban (PLB), nor did PLB slow the kinetics of Tg binding. FRET in ionophore-permeabilized cells was lower in EGTA than in saturating calcium for all constructs, indicating a decrease in domain separation distance with the structural transition from E2 (Ca-free) to E1 (Ca-bound). The data suggest closure of the cytoplasmic headpiece with Ca-binding. The present results provide insight into the structural dynamics of the Ca-ATPase. In addition, the 2-color SERCA constructs developed for this study may be useful for evaluating candidate small molecule regulators of Ca uptake activity.
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Affiliation(s)
- Zhanjia Hou
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Zhihong Hu
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Daniel J. Blackwell
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States of America
| | - Tyler D. Miller
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Seth L. Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States of America
- * E-mail:
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Hou Z, Hu Z, Blackwell DJ, Miller TD, Thomas DD, Robia SL. Quantification of Calcium Pump Structure Changes in Live Celss. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3848] [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: 10/14/2022] Open
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28
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Bidwell P, Blackwell DJ, Hou Z, Zima AV, Robia SL. Phospholamban binds with differential affinity to calcium pump conformers. J Biol Chem 2011; 286:35044-50. [PMID: 21832088 PMCID: PMC3186385 DOI: 10.1074/jbc.m111.266759] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [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: 05/31/2011] [Revised: 08/03/2011] [Indexed: 12/16/2022] Open
Abstract
To investigate the mechanism of regulation of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) by phospholamban (PLB), we expressed Cerulean-SERCA and yellow fluorescent protein (YFP)-PLB in adult rabbit ventricular myocytes using adenovirus vectors. SERCA and PLB were localized in the sarcoplasmic reticulum and were mobile over multiple sarcomeres on a timescale of tens of seconds. We also observed robust fluorescence resonance energy transfer (FRET) from Cerulean-SERCA to YFP-PLB. Electrical pacing of cardiac myocytes elicited cytoplasmic Ca(2+) elevations, but these increases in Ca(2+) produced only modest changes in SERCA-PLB FRET. The data suggest that the regulatory complex is not disrupted by elevations of cytosolic calcium during cardiac contraction (systole). This conclusion was also supported by parallel experiments in heterologous cells, which showed that FRET was reduced but not abolished by calcium. Thapsigargin also elicited a small decrease in PLB-SERCA binding affinity. We propose that PLB is not displaced from SERCA by high calcium during systole, and relief of functional inhibition does not require dissociation of the regulatory complex. The observed modest reduction in the affinity of the PLB-SERCA complex with Ca(2+) or thapsigargin suggests that the binding interface is altered by SERCA conformational changes. The results are consistent with multiple modes of PLB binding or alternative binding sites.
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Affiliation(s)
- Philip Bidwell
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153
| | - Daniel J. Blackwell
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153
| | - Zhanjia Hou
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153
| | - Aleksey V. Zima
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153
| | - Seth L. Robia
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153
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Blackwell DJ, Bidwell P, Robia SL. Fret Measurements in Electrically Paced Adult Cardiac Myocytes Suggest the Phospholamban-SERCA2a Regulatory Complex is not Dissociated by Beat-To-Beat Elevations of Cytosolic Calcium. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2077] [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: 11/29/2022] Open
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Bidwell P, Blackwell DJ, Hou Z, Robia SL. FRET from SERCA to Phospholamban is Decreased by Thapsigargin and Anti-PLB Antibody, but not by Calcium. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.637] [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: 10/21/2022] Open
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