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Sidorov VY, Sidorova TN, Samson PC, Reiserer RS, Britt CM, Neely MD, Ess KC, Wikswo JP. Contractile and Genetic Characterization of Cardiac Constructs Engineered from Human Induced Pluripotent Stem Cells: Modeling of Tuberous Sclerosis Complex and the Effects of Rapamycin. Bioengineering (Basel) 2024; 11:234. [PMID: 38534508 DOI: 10.3390/bioengineering11030234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/28/2024] Open
Abstract
The implementation of three-dimensional tissue engineering concurrently with stem cell technology holds great promise for in vitro research in pharmacology and toxicology and modeling cardiac diseases, particularly for rare genetic and pediatric diseases for which animal models, immortal cell lines, and biopsy samples are unavailable. It also allows for a rapid assessment of phenotype-genotype relationships and tissue response to pharmacological manipulation. Mutations in the TSC1 and TSC2 genes lead to dysfunctional mTOR signaling and cause tuberous sclerosis complex (TSC), a genetic disorder that affects multiple organ systems, principally the brain, heart, skin, and kidneys. Here we differentiated healthy (CC3) and tuberous sclerosis (TSP8-15) human induced pluripotent stem cells (hiPSCs) into cardiomyocytes to create engineered cardiac tissue constructs (ECTCs). We investigated and compared their mechano-elastic properties and gene expression and assessed the effects of rapamycin, a potent inhibitor of the mechanistic target of rapamycin (mTOR). The TSP8-15 ECTCs had increased chronotropy compared to healthy ECTCs. Rapamycin induced positive inotropic and chronotropic effects (i.e., increased contractility and beating frequency, respectively) in the CC3 ECTCs but did not cause significant changes in the TSP8-15 ECTCs. A differential gene expression analysis revealed 926 up- and 439 down-regulated genes in the TSP8-15 ECTCs compared to their healthy counterparts. The application of rapamycin initiated the differential expression of 101 and 31 genes in the CC3 and TSP8-15 ECTCs, respectively. A gene ontology analysis showed that in the CC3 ECTCs, the positive inotropic and chronotropic effects of rapamycin correlated with positively regulated biological processes, which were primarily related to the metabolism of lipids and fatty and amino acids, and with negatively regulated processes, which were predominantly associated with cell proliferation and muscle and tissue development. In conclusion, this study describes for the first time an in vitro TSC cardiac tissue model, illustrates the response of normal and TSC ECTCs to rapamycin, and provides new insights into the mechanisms of TSC.
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Affiliation(s)
- Veniamin Y Sidorov
- Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Tatiana N Sidorova
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Philip C Samson
- Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, Nashville, TN 37235, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37212, USA
| | - Ronald S Reiserer
- Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, Nashville, TN 37235, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37212, USA
| | - Clayton M Britt
- Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, Nashville, TN 37235, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37212, USA
| | - M Diana Neely
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kevin C Ess
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John P Wikswo
- Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37212, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
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2
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Waddell HMM, Mereacre V, Alvarado FJ, Munro ML. Clustering properties of the cardiac ryanodine receptor in health and heart failure. J Mol Cell Cardiol 2023; 185:38-49. [PMID: 37890552 PMCID: PMC10717225 DOI: 10.1016/j.yjmcc.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/09/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
The cardiac ryanodine receptor (RyR2) is an intracellular Ca2+ release channel vital for the function of the heart. Physiologically, RyR2 is triggered to release Ca2+ from the sarcoplasmic reticulum (SR) which enables cardiac contraction; however, spontaneous Ca2+ leak from RyR2 has been implicated in the pathophysiology of heart failure (HF). RyR2 channels have been well documented to assemble into clusters within the SR membrane, with the organisation of RyR2 clusters recently gaining interest as a mechanism by which the occurrence of pathological Ca2+ leak is regulated, including in HF. In this review, we explain the terminology relating to key nanoscale RyR2 clustering properties as both single clusters and functionally grouped Ca2+ release units, with a focus on the advancements in super-resolution imaging approaches which have enabled the detailed study of cluster organisation. Further, we discuss proposed mechanisms for modulating RyR2 channel organisation and the debate regarding the potential impact of cluster organisation on Ca2+ leak activity. Finally, recent experimental evidence investigating the nanoscale remodelling and functional alterations of RyR2 clusters in HF is discussed with consideration of the clinical implications.
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Affiliation(s)
- Helen M M Waddell
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Valeria Mereacre
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Francisco J Alvarado
- Department of Medicine and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Michelle L Munro
- Department of Physiology and HeartOtago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
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3
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Lee TI, Trang NN, Lee TW, Higa S, Kao YH, Chen YC, Chen YJ. Ketogenic Diet Regulates Cardiac Remodeling and Calcium Homeostasis in Diabetic Rat Cardiomyopathy. Int J Mol Sci 2023; 24:16142. [PMID: 38003332 PMCID: PMC10671812 DOI: 10.3390/ijms242216142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
A ketogenic diet (KD) might alleviate patients with diabetic cardiomyopathy. However, the underlying mechanism remains unclear. Myocardial function and arrhythmogenesis are closely linked to calcium (Ca2+) homeostasis. We investigated the effects of a KD on Ca2+ homeostasis and electrophysiology in diabetic cardiomyopathy. Male Wistar rats were created to have diabetes mellitus (DM) using streptozotocin (65 mg/kg, intraperitoneally), and subsequently treated for 6 weeks with either a normal diet (ND) or a KD. Our electrophysiological and Western blot analyses assessed myocardial Ca2+ homeostasis in ventricular preparations in vivo. Unlike those on the KD, DM rats treated with an ND exhibited a prolonged QTc interval and action potential duration. Compared to the control and DM rats on the KD, DM rats treated with an ND also showed lower intracellular Ca2+ transients, sarcoplasmic reticular Ca2+ content, sodium (Na+)-Ca2+ exchanger currents (reverse mode), L-type Ca2+ contents, sarcoplasmic reticulum ATPase contents, Cav1.2 contents. Furthermore, these rats exhibited elevated ratios of phosphorylated to total proteins across multiple Ca2+ handling proteins, including ryanodine receptor 2 (RyR2) at serine 2808, phospholamban (PLB)-Ser16, and calmodulin-dependent protein kinase II (CaMKII). Additionally, DM rats treated with an ND demonstrated a higher frequency and incidence of Ca2+ leak, cytosolic reactive oxygen species, Na+/hydrogen-exchanger currents, and late Na+ currents than the control and DM rats on the KD. KD treatment may attenuate the effects of DM-dysregulated Na+ and Ca2+ homeostasis, contributing to its cardioprotection in DM.
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Affiliation(s)
- Ting-I Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan; (T.-I.L.); (T.-W.L.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | | | - Ting-Wei Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan; (T.-I.L.); (T.-W.L.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Makiminato Urasoe City, Okinawa 901-2131, Japan;
| | - Yu-Hsun Kao
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei 11490, Taiwan
| | - Yi-Jen Chen
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Cardiovascular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
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Walweel K, Beard N, van Helden DF, Laver DR. Dantrolene inhibition of ryanodine channels (RyR2) in artificial lipid bilayers depends on FKBP12.6. J Gen Physiol 2023; 155:e202213277. [PMID: 37279522 PMCID: PMC10244881 DOI: 10.1085/jgp.202213277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 03/18/2023] [Accepted: 05/22/2023] [Indexed: 06/08/2023] Open
Abstract
Dantrolene is a neutral hydantoin that is clinically used as a skeletal muscle relaxant to prevent overactivation of the skeletal muscle calcium release channel (RyR1) in response to volatile anesthetics. Dantrolene has aroused considerable recent interest as a lead compound for stabilizing calcium release due to overactive cardiac calcium release channels (RyR2) in heart failure. Previously, we found that dantrolene produces up to a 45% inhibition RyR2 with an IC50 of 160 nM, and that this inhibition requires the physiological association between RyR2 and CaM. In this study, we tested the hypothesis that dantrolene inhibition of RyR2 in the presence of CaM is modulated by RyR2 phosphorylation at S2808 and S2814. Phosphorylation was altered by incubations with either exogenous phosphatase (PP1) or kinases; PKA to phosphorylate S2808 or endogenous CaMKII to phosphorylate S2814. We found that PKA caused selective dissociation of FKBP12.6 from the RyR2 complex and a loss of dantrolene inhibition. Rapamycin-induced FKBP12.6 dissociation from RyR2 also resulted in the loss of dantrolene inhibition. Subsequent incubations of RyR2 with exogenous FKBP12.6 reinstated dantrolene inhibition. These findings indicate that the inhibitory action of dantrolene on RyR2 depends on RyR2 association with FKBP12.6 in addition to CaM as previously found.
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Affiliation(s)
- Kafa Walweel
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
| | - Nicole Beard
- Faculty of Science and Technology, University of Canberra, Bruce, Australia
| | - Dirk F. van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
| | - Derek R. Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, Australia
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Richardson SJ, Thekkedam CG, Casarotto MG, Beard NA, Dulhunty AF. FKBP12 binds to the cardiac ryanodine receptor with negative cooperativity: implications for heart muscle physiology in health and disease. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220169. [PMID: 37122219 PMCID: PMC10150220 DOI: 10.1098/rstb.2022.0169] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023] Open
Abstract
Cardiac ryanodine receptors (RyR2) release the Ca2+ from intracellular stores that is essential for cardiac myocyte contraction. The ion channel opening is tightly regulated by intracellular factors, including the FK506 binding proteins, FKBP12 and FKBP12.6. The impact of these proteins on RyR2 activity and cardiac contraction is debated, with often apparently contradictory experimental results, particularly for FKBP12. The isoform that regulates RyR2 has generally been considered to be FKBP12.6, despite the fact that FKBP12 is the major isoform associated with RyR2 in some species and is bound in similar proportions to FKBP12.6 in others, including sheep and humans. Here, we show time- and concentration-dependent effects of adding FKBP12 to RyR2 channels that were partly depleted of FKBP12/12.6 during isolation. The added FKBP12 displaced most remaining endogenous FKBP12/12.6. The results suggest that FKBP12 activates RyR2 with high affinity and inhibits RyR2 with lower affinity, consistent with a model of negative cooperativity in FKBP12 binding to each of the four subunits in the RyR tetramer. The easy dissociation of some FKBP12/12.6 could dynamically alter RyR2 activity in response to changes in in vivo regulatory factors, indicating a significant role for FKBP12/12.6 in Ca2+ signalling and cardiac function in healthy and diseased hearts. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- S J Richardson
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - C G Thekkedam
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - M G Casarotto
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - N A Beard
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
| | - A F Dulhunty
- John Curtin School of Medical Research, Australian National University, Canberra, Australia, Australian Capital Territory 2601, Australia
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6
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Marcadet L, Juracic ES, Khan N, Bouredji Z, Yagita H, Ward LM, Tupling AR, Argaw A, Frenette J. RANKL Inhibition Reduces Cardiac Hypertrophy in mdx Mice and Possibly in Children with Duchenne Muscular Dystrophy. Cells 2023; 12:1538. [PMID: 37296659 PMCID: PMC10253225 DOI: 10.3390/cells12111538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 06/12/2023] Open
Abstract
Cardiomyopathy has become one of the leading causes of death in patients with Duchenne muscular dystrophy (DMD). We recently reported that the inhibition of the interaction between the receptor activator of nuclear factor κB ligand (RANKL) and receptor activator of nuclear factor κB (RANK) significantly improves muscle and bone functions in dystrophin-deficient mdx mice. RANKL and RANK are also expressed in cardiac muscle. Here, we investigate whether anti-RANKL treatment prevents cardiac hypertrophy and dysfunction in dystrophic mdx mice. Anti-RANKL treatment significantly reduced LV hypertrophy and heart mass, and maintained cardiac function in mdx mice. Anti-RANKL treatment also inhibited NFκB and PI3K, two mediators implicated in cardiac hypertrophy. Furthermore, anti-RANKL treatment increased SERCA activity and the expression of RyR, FKBP12, and SERCA2a, leading possibly to an improved Ca2+ homeostasis in dystrophic hearts. Interestingly, preliminary post hoc analyses suggest that denosumab, a human anti-RANKL, reduced left ventricular hypertrophy in two patients with DMD. Taken together, our results indicate that anti-RANKL treatment prevents the worsening of cardiac hypertrophy in mdx mice and could potentially maintain cardiac function in teenage or adult patients with DMD.
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Affiliation(s)
- Laetitia Marcadet
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC G1V 4G2, Canada; (L.M.); (Z.B.); (A.A.)
| | - Emma Sara Juracic
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (E.S.J.); (A.R.T.)
| | - Nasrin Khan
- The Ottawa Pediatric Bone Health Research Group, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada; (N.K.); (L.M.W.)
| | - Zineb Bouredji
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC G1V 4G2, Canada; (L.M.); (Z.B.); (A.A.)
| | - Hideo Yagita
- Department of Immunology, School of Medicine, Juntendo University, Tokyo 113-8421, Japan;
| | - Leanne M. Ward
- The Ottawa Pediatric Bone Health Research Group, Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada; (N.K.); (L.M.W.)
- The Department of Pediatrics, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - A. Russell Tupling
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada; (E.S.J.); (A.R.T.)
| | - Anteneh Argaw
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC G1V 4G2, Canada; (L.M.); (Z.B.); (A.A.)
| | - Jérôme Frenette
- Centre Hospitalier Universitaire de Québec, Centre de Recherche du Centre Hospitalier de l’Université Laval (CHUQ-CHUL), Axe Neurosciences, Université Laval, Quebec City, QC G1V 4G2, Canada; (L.M.); (Z.B.); (A.A.)
- Department of Rehabilitation, Université Laval, Quebec City, QC G1V 0A6, Canada
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7
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Wang YX, Reyes-García J, Di Mise A, Zheng YM. Role of ryanodine receptor 2 and FK506-binding protein 12.6 dissociation in pulmonary hypertension. J Gen Physiol 2023; 155:213798. [PMID: 36625865 PMCID: PMC9836826 DOI: 10.1085/jgp.202213100] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 07/29/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Pulmonary hypertension (PH) is a devastating disease characterized by a progressive increase in pulmonary arterial pressure leading to right ventricular failure and death. A major cellular response in this disease is the contraction of smooth muscle cells (SMCs) of the pulmonary vasculature. Cell contraction is determined by the increase in intracellular Ca2+ concentration ([Ca2+]i), which is generated and regulated by various ion channels. Several studies by us and others have shown that ryanodine receptor 2 (RyR2), a Ca2+-releasing channel in the sarcoplasmic reticulum (SR), is an essential ion channel for the control of [Ca2+]i in pulmonary artery SMCs (PASMCs), thereby mediating the sustained vasoconstriction seen in PH. FK506-binding protein 12.6 (FKBP12.6) strongly associates with RyR2 to stabilize its functional activity. FKBP12.6 can be dissociated from RyR2 by a hypoxic stimulus to increase channel function and Ca2+ release, leading to pulmonary vasoconstriction and PH. More specifically, dissociation of the RyR2-FKBP12.6 complex is a consequence of increased mitochondrial ROS generation mediated by the Rieske iron-sulfur protein (RISP) at the mitochondrial complex III after hypoxia. Overall, RyR2/FKBP12.6 dissociation and the corresponding signaling pathway may be an important factor in the development of PH. Novel drugs and biologics targeting RyR2, FKBP12.6, and related molecules may become unique effective therapeutics for PH.
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Affiliation(s)
- Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Correspondence to Yong-Xiao Wang:
| | - Jorge Reyes-García
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México,Ciudad de México, México
| | - Annarita Di Mise
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, NY, USA,Yun-Min Zheng:
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Alomar FA, Tian C, Bidasee SR, Venn ZL, Schroder E, Palermo NY, AlShabeeb M, Edagwa BJ, Payne JJ, Bidasee KR. HIV-Tat Exacerbates the Actions of Atazanavir, Efavirenz, and Ritonavir on Cardiac Ryanodine Receptor (RyR2). Int J Mol Sci 2022; 24:ijms24010274. [PMID: 36613717 PMCID: PMC9820108 DOI: 10.3390/ijms24010274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/05/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
The incidence of sudden cardiac death (SCD) in people living with HIV infection (PLWH), especially those with inadequate viral suppression, is high and the reasons for this remain incompletely characterized. The timely opening and closing of type 2 ryanodine receptor (RyR2) is critical for ensuring rhythmic cardiac contraction-relaxation cycles, and the disruption of these processes can elicit Ca2+ waves, ventricular arrhythmias, and SCD. Herein, we show that the HIV protein Tat (HIV-Tat: 0-52 ng/mL) and therapeutic levels of the antiretroviral drugs atazanavir (ATV: 0-25,344 ng/mL), efavirenz (EFV: 0-11,376 ng/mL), and ritonavir (RTV: 0-25,956 ng/mL) bind to and modulate the opening and closing of RyR2. Abacavir (0-14,315 ng/mL), bictegravir (0-22,469 ng/mL), Rilpivirine (0-14,360 ng/mL), and tenofovir disoproxil fumarate (0-18,321 ng/mL) did not alter [3H]ryanodine binding to RyR2. Pretreating RyR2 with low HIV-Tat (14 ng/mL) potentiated the abilities of ATV and RTV to bind to open RyR2 and enhanced their ability to bind to EFV to close RyR2. In silico molecular docking using a Schrodinger Prime protein-protein docking algorithm identified three thermodynamically favored interacting sites for HIV-Tat on RyR2. The most favored site resides between amino acids (AA) 1702-1963; the second favored site resides between AA 467-1465, and the third site resides between AA 201-1816. Collectively, these new data show that HIV-Tat, ATV, EFV, and RTV can bind to and modulate the activity of RyR2 and that HIV-Tat can exacerbate the actions of ATV, EFV, and RTV on RyR2. Whether the modulation of RyR2 by these agents increases the risk of arrhythmias and SCD remains to be explored.
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Affiliation(s)
- Fadhel A. Alomar
- Department of Pharmacology and Toxicology, College of Clinical Pharmacy, Imam Abdulrahman Bin Faisal University, Dammam 31441, Saudi Arabia
| | - Chengju Tian
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Sean R. Bidasee
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Zachary L. Venn
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Evan Schroder
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nicholas Y. Palermo
- Vice Chancellor for Research Cores, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mohammad AlShabeeb
- Population Health Research Section, King Abdullah International Medical Research Center, King Saudi bin Abdulaziz University for Health Sciences, Riyadh 11426, Saudi Arabia
| | - Benson J. Edagwa
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jason J. Payne
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Keshore R. Bidasee
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Environment and Occupational Health, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Nebraska Redox Biology Center, Lincoln, NE 68588, USA
- Correspondence: ; Tel.: +402-559-9018; Fax: +402-559-7495
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Engel MA, Wörmann YR, Kaestner H, Schüler C. An Optogenetic Arrhythmia Model—Insertion of Several Catecholaminergic Polymorphic Ventricular Tachycardia Mutations Into Caenorhabditis elegans UNC-68 Disturbs Calstabin-Mediated Stabilization of the Ryanodine Receptor Homolog. Front Physiol 2022; 13:691829. [PMID: 35399287 PMCID: PMC8990320 DOI: 10.3389/fphys.2022.691829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 02/15/2022] [Indexed: 11/14/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disturbance of the heart rhythm (arrhythmia) that is induced by stress or that occurs during exercise. Most mutations that have been linked to CPVT are found in two genes, i.e., ryanodine receptor 2 (RyR2) and calsequestrin 2 (CASQ2), two proteins fundamentally involved in the regulation of intracellular Ca2+ in cardiac myocytes. We inserted six CPVT-causing mutations via clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 into unc-68 and csq-1, the Caenorhabditis elegans homologs of RyR and CASQ, respectively. We characterized those mutations via video-microscopy, electrophysiology, and calcium imaging in our previously established optogenetic arrhythmia model. In this study, we additionally enabled high(er) throughput recordings of intact animals by combining optogenetic stimulation with a microfluidic chip system. Whereas only minor/no pump deficiency of the pharynx was observed at baseline, three mutations of UNC-68 (S2378L, P2460S, Q4623R; RyR2-S2246L, -P2328S, -Q4201R) reduced the ability of the organ to follow 4 Hz optogenetic stimulation. One mutation (Q4623R) was accompanied by a strong reduction of maximal pump rate. In addition, S2378L and Q4623R evoked an altered calcium handling during optogenetic stimulation. The 1,4-benzothiazepine S107, which is suggested to stabilize RyR2 channels by enhancing the binding of calstabin2, reversed the reduction of pumping ability in a mutation-specific fashion. However, this depends on the presence of FKB-2, a C. elegans calstabin2 homolog, indicating the involvement of calstabin2 in the disease-causing mechanisms of the respective mutations. In conclusion, we showed for three CPVT-like mutations in C. elegans RyR a reduced pumping ability upon light stimulation, i.e., an arrhythmia-like phenotype, that can be reversed in two cases by the benzothiazepine S107 and that depends on stabilization via FKB-2. The genetically amenable nematode in combination with optogenetics and high(er) throughput recordings is a promising straightforward system for the investigation of RyR mutations and the selection of mutation-specific drugs.
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Affiliation(s)
- Marcial Alexander Engel
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Yves René Wörmann
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Hanna Kaestner
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Christina Schüler
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
- *Correspondence: Christina Schüler,
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10
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The function and regulation of calsequestrin-2: implications in calcium-mediated arrhythmias. Biophys Rev 2022; 14:329-352. [PMID: 35340602 PMCID: PMC8921388 DOI: 10.1007/s12551-021-00914-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/14/2021] [Indexed: 01/09/2023] Open
Abstract
Cardiac arrhythmias are life-threatening events in which the heart develops an irregular rhythm. Mishandling of Ca2+ within the myocytes of the heart has been widely demonstrated to be an underlying mechanism of arrhythmogenesis. This includes altered function of the ryanodine receptor (RyR2)-the primary Ca2+ release channel located to the sarcoplasmic reticulum (SR). The spontaneous leak of SR Ca2+ via RyR2 is a well-established contributor in the development of arrhythmic contractions. This leak is associated with increased channel activity in response to changes in SR Ca2+ load. RyR2 activity can be regulated through several avenues, including interactions with numerous accessory proteins. One such protein is calsequestrin-2 (CSQ2), which is the primary Ca2+-buffering protein within the SR. The capacity of CSQ2 to buffer Ca2+ is tightly associated with the ability of the protein to polymerise in response to changing Ca2+ levels. CSQ2 can itself be regulated through phosphorylation and glycosylation modifications, which impact protein polymerisation and trafficking. Changes in CSQ2 modifications are implicated in cardiac pathologies, while mutations in CSQ2 have been identified in arrhythmic patients. Here, we review the role of CSQ2 in arrhythmogenesis including evidence for the indirect and direct regulation of RyR2 by CSQ2, and the consequences of a loss of functional CSQ2 in Ca2+ homeostasis and Ca2+-mediated arrhythmias. Supplementary Information The online version contains supplementary material available at 10.1007/s12551-021-00914-6.
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11
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Xin Y, Guan J, Li Y, Duan C. Regulation of cell quiescence-proliferation balance by Ca2+-CaMKK-Akt signaling. J Cell Sci 2021; 134:272559. [PMID: 34545403 DOI: 10.1242/jcs.253807] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 09/15/2021] [Indexed: 11/20/2022] Open
Abstract
Compared with our extensive understanding of the cell cycle, we have limited knowledge of how the cell quiescence-proliferation decision is regulated. Using a zebrafish epithelial model, we report a novel signaling mechanism governing the cell quiescence-proliferation decision. Zebrafish Ca2+-transporting epithelial cells, or ionocytes, maintain high cytoplasmic Ca2+ concentration ([Ca2+]c) due to the expression of Trpv6. Genetic deletion or pharmacological inhibition of Trpv6, or reduction of external Ca2+ concentration, lowered the [Ca2+]c and reactivated these cells. The ionocyte reactivation was attenuated by chelating intracellular Ca2+ and inhibiting calmodulin (CaM), suggesting involvement of a Ca2+ and CaM-dependent mechanism. Long-term imaging studies showed that after an initial decrease, [Ca2+]c gradually returned to the basal levels. There was a concomitant decease in endoplasmic reticulum (ER) Ca2+ levels. Lowering the ER Ca2+ store content or inhibiting ryanodine receptors impaired ionocyte reactivation. Further analyses suggest that CaM-dependent protein kinase kinase (CaMKK) is a key molecular link between Ca2+ and Akt signaling. Genetic deletion or inhibition of CaMKK abolished cell reactivation, which could be rescued by expression of a constitutively active Akt. These results suggest that the quiescence-proliferation decision in zebrafish ionocytes is regulated by Trpv6-mediated Ca2+ and CaMKK-Akt signaling.
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Affiliation(s)
- Yi Xin
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jian Guan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yingxiang Li
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Cunming Duan
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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12
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Schmidpeter PAM, Rheinberger J, Nimigean CM. Prolyl isomerization controls activation kinetics of a cyclic nucleotide-gated ion channel. Nat Commun 2020; 11:6401. [PMID: 33328472 PMCID: PMC7744796 DOI: 10.1038/s41467-020-20104-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/11/2020] [Indexed: 01/21/2023] Open
Abstract
SthK, a cyclic nucleotide-modulated ion channel from Spirochaeta thermophila, activates slowly upon cAMP increase. This is reminiscent of the slow, cAMP-induced activation reported for the hyperpolarization-activated and cyclic nucleotide-gated channel HCN2 in the family of so-called pacemaker channels. Here, we investigate slow cAMP-induced activation in purified SthK channels using stopped-flow assays, mutagenesis, enzymatic catalysis and inhibition assays revealing that the cis/trans conformation of a conserved proline in the cyclic nucleotide-binding domain determines the activation kinetics of SthK. We propose that SthK exists in two forms: trans Pro300 SthK with high ligand binding affinity and fast activation, and cis Pro300 SthK with low affinity and slow activation. Following channel activation, the cis/trans equilibrium, catalyzed by prolyl isomerases, is shifted towards trans, while steady-state channel activity is unaffected. Our results reveal prolyl isomerization as a regulatory mechanism for SthK, and potentially eukaryotic HCN channels. This mechanism could contribute to electrical rhythmicity in cells.
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Affiliation(s)
- Philipp A. M. Schmidpeter
- grid.5386.8000000041936877XWeill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY 10065 USA
| | - Jan Rheinberger
- grid.5386.8000000041936877XWeill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY 10065 USA ,grid.4830.f0000 0004 0407 1981Present Address: University of Groningen, Groningen, Netherlands
| | - Crina M. Nimigean
- grid.5386.8000000041936877XWeill Cornell Medicine, Department of Anesthesiology, 1300 York Avenue, New York, NY 10065 USA ,grid.5386.8000000041936877XWeill Cornell Medicine, Department of Physiology and Biophysics, 1300 York Avenue, New York, NY 10065 USA
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13
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Saadeh K, Achercouk Z, Fazmin IT, Nantha Kumar N, Salvage SC, Edling CE, Huang CLH, Jeevaratnam K. Protein expression profiles in murine ventricles modeling catecholaminergic polymorphic ventricular tachycardia: effects of genotype and sex. Ann N Y Acad Sci 2020; 1478:63-74. [PMID: 32713021 DOI: 10.1111/nyas.14426] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/27/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is associated with mutations in the cardiac ryanodine receptor (RyR2). These result in stress-induced ventricular arrhythmic episodes, with clinical symptoms and prognosis reported more severe in male than female patients. Murine homozygotic RyR2-P2328S (RyR2S/S ) hearts replicate the proarrhythmic CPVT phenotype of abnormal sarcoplasmic reticular Ca2+ leak and disrupted Ca2+ homeostasis. In addition, RyR2S/S hearts show decreased myocardial action potential conduction velocities (CV), all features implicated in arrhythmic trigger and substrate. The present studies explored for independent and interacting effects of RyR2S/S genotype and sex on expression levels of molecular determinants of Ca2+ homeostasis (CASQ2, FKBP12, SERCA2a, NCX1, and CaV 1.2) and CV (NaV 1.5, Connexin (Cx)-43, phosphorylated-Cx43, and TGF-β1) in mice. Expression levels of Ca2+ homeostasis proteins were not altered, hence implicating abnormal RyR2 function alone in disrupted cytosolic Ca2+ homeostasis. Furthermore, altered NaV 1.5, phosphorylated Cx43, and TGF-β1 expression were not implicated in the development of slowed CV. By contrast, decreased Cx43 expression correlated with slowed CV, in female, but not male, RyR2S/S mice. The CV changes may reflect acute actions of the increased cytosolic Ca2+ on NaV 1.5 and Cx43 function.
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Affiliation(s)
- Khalil Saadeh
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Zakaria Achercouk
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ibrahim T Fazmin
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Nakulan Nantha Kumar
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Samantha C Salvage
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Charlotte E Edling
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
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14
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Wleklinski MJ, Kannankeril PJ, Knollmann BC. Molecular and tissue mechanisms of catecholaminergic polymorphic ventricular tachycardia. J Physiol 2020; 598:2817-2834. [PMID: 32115705 PMCID: PMC7699301 DOI: 10.1113/jp276757] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/03/2020] [Indexed: 12/21/2022] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a stress-induced cardiac channelopathy that has a high mortality in untreated patients. Our understanding has grown tremendously since CPVT was first described as a clinical syndrome in 1995. It is now established that the deadly arrhythmias are caused by unregulated 'pathological' calcium release from the sarcoplasmic reticulum (SR), the major calcium storage organelle in striated muscle. Important questions remain regarding the molecular mechanisms that are responsible for the pathological calcium release, regarding the tissue origin of the arrhythmic beats that initiate ventricular tachycardia, and regarding optimal therapeutic approaches. At present, mutations in six genes involved in SR calcium release have been identified as the genetic cause of CPVT: RYR2 (encoding ryanodine receptor calcium release channel), CASQ2 (encoding cardiac calsequestrin), TRDN (encoding triadin), CALM1, CALM2 and CALM3 (encoding identical calmodulin protein). Here, we review each CPVT subtype and how CPVT mutations alter protein function, RyR2 calcium release channel regulation, and cellular calcium handling. We then discuss research and hypotheses surrounding the tissue mechanisms underlying CPVT, such as the pathophysiological role of sinus node dysfunction in CPVT, and whether the arrhythmogenic beats originate from the conduction system or the ventricular working myocardium. Finally, we review the treatments that are available for patients with CPVT, their efficacy, and how therapy could be improved in the future.
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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, Tennessee, USA
| | - Prince J Kannankeril
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bjӧrn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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15
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Asghari P, Scriven DR, Ng M, Panwar P, Chou KC, van Petegem F, Moore ED. Cardiac ryanodine receptor distribution is dynamic and changed by auxiliary proteins and post-translational modification. eLife 2020; 9:51602. [PMID: 31916935 PMCID: PMC6994221 DOI: 10.7554/elife.51602] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/09/2020] [Indexed: 12/14/2022] Open
Abstract
The effects of the immunophilins, FKBP12 and FKBP12.6, and phosphorylation on type II ryanodine receptor (RyR2) arrangement and function were examined using correlation microscopy (line scan confocal imaging of Ca2+ sparks and dual-tilt electron tomography) and dSTORM imaging of permeabilized Wistar rat ventricular myocytes. Saturating concentrations (10 µmol/L) of either FKBP12 or 12.6 significantly reduced the frequency, spread, amplitude and Ca2+ spark mass relative to control, while the tomograms revealed both proteins shifted the tetramers into a largely side-by-side configuration. Phosphorylation of immunophilin-saturated RyR2 resulted in structural and functional changes largely comparable to phosphorylation alone. dSTORM images of myocyte surfaces demonstrated that both FKBP12 and 12.6 significantly reduced RyR2 cluster sizes, while phosphorylation, even of immunophilin-saturated RyR2, increased them. We conclude that both RyR2 cluster size and the arrangement of tetramers within clusters is dynamic and respond to changes in the cellular environment. Further, these changes affect Ca2+ spark formation.
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Affiliation(s)
- Parisa Asghari
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - David Rl Scriven
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Myles Ng
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Pankaj Panwar
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Keng C Chou
- Department of Chemistry, University of British Columbia, Vancouver, Canada
| | - Filip van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Edwin Dw Moore
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
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16
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Al Kury LT. Calcium Homeostasis in Ventricular Myocytes of Diabetic Cardiomyopathy. J Diabetes Res 2020; 2020:1942086. [PMID: 33274235 PMCID: PMC7683117 DOI: 10.1155/2020/1942086] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/24/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022] Open
Abstract
Diabetes mellitus (DM) is a chronic metabolic disorder commonly characterized by high blood glucose levels, resulting from defects in insulin production or insulin resistance, or both. DM is a leading cause of mortality and morbidity worldwide, with diabetic cardiomyopathy as one of its main complications. It is well established that cardiovascular complications are common in both types of diabetes. Electrical and mechanical problems, resulting in cardiac contractile dysfunction, are considered as the major complications present in diabetic hearts. Inevitably, disturbances in the mechanism(s) of Ca2+ signaling in diabetes have implications for cardiac myocyte contraction. Over the last decade, significant progress has been made in outlining the mechanisms responsible for the diminished cardiac contractile function in diabetes using different animal models of type I diabetes mellitus (TIDM) and type II diabetes mellitus (TIIDM). The aim of this review is to evaluate our current understanding of the disturbances of Ca2+ transport and the role of main cardiac proteins involved in Ca2+ homeostasis in the diabetic rat ventricular cardiomyocytes. Exploring the molecular mechanism(s) of altered Ca2+ signaling in diabetes will provide an insight for the identification of novel therapeutic approaches to improve the heart function in diabetic patients.
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Affiliation(s)
- Lina T. Al Kury
- Department of Health Sciences, College of Natural and Health Sciences, Zayed University, Abu Dhabi 144534, UAE
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17
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Molecular basis for allosteric regulation of the type 2 ryanodine receptor channel gating by key modulators. Proc Natl Acad Sci U S A 2019; 116:25575-25582. [PMID: 31792195 PMCID: PMC6926060 DOI: 10.1073/pnas.1914451116] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
As a switch for the release of Ca2+ from the sarco(endo)plasmic reticulum of cardiomyocytes, the type 2 ryanodine receptor (RyR2) is subject to sophisticated regulation by a broad spectrum of modulators. Dysregulation of RyR2-mediated Ca2+ release is linked to life-threatening cardiac arrhythmias. The regulatory mechanism of RyR2 by key modulators, such as Ca2+, FKBP12.6, ATP, and caffeine, remains unclear. This study provides important insights into the long-range allosteric regulation of RyR2 channel gating by these modulators and serves as an important framework for mechanistic understanding of the regulation of this key player in the excitation–contraction coupling of cardiac muscles. The type 2 ryanodine receptor (RyR2) is responsible for releasing Ca2+ from the sarcoplasmic reticulum of cardiomyocytes, subsequently leading to muscle contraction. Here, we report 4 cryo-electron microscopy (cryo-EM) structures of porcine RyR2 bound to distinct modulators that, together with our published structures, provide mechanistic insight into RyR2 regulation. Ca2+ alone induces a contraction of the central domain that facilitates the dilation of the S6 bundle but is insufficient to open the pore. The small-molecule agonist PCB95 helps Ca2+ to overcome the barrier for opening. FKBP12.6 induces a relaxation of the central domain that decouples it from the S6 bundle, stabilizing RyR2 in a closed state even in the presence of Ca2+ and PCB95. Although the channel is open when PCB95 is replaced by caffeine and adenosine 5′-triphosphate (ATP), neither of the modulators alone can sufficiently counter the antagonistic effect to open the channel. Our study marks an important step toward mechanistic understanding of the sophisticated regulation of this key channel whose aberrant activity engenders life-threatening cardiac disorders.
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18
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Steele TWE, Samsó M. The FKBP12 subunit modifies the long-range allosterism of the ryanodine receptor. J Struct Biol 2019; 205:180-188. [PMID: 30641143 DOI: 10.1016/j.jsb.2018.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 02/06/2023]
Abstract
Ryanodine receptors (RyRs) are large conductance intracellular channels controlling intracellular calcium homeostasis in myocytes, neurons, and other cell types. Loss of RyR's constitutive cytoplasmic partner FKBP results in channel sensitization, dominant subconductance states, and increased cytoplasmic Ca2+. FKBP12 binds to RyR1's cytoplasmic assembly 130 Å away from the ion gate at four equivalent sites in the RyR1 tetramer. To understand how FKBP12 binding alters RyR1's channel properties, we studied the 3D structure of RyR1 alone in the closed conformation in the context of the open and closed conformations of FKBP12-bound RyR1. We analyzed the metrics of conformational changes of existing structures, the structure of the ion gate, and carried out multivariate statistical analysis of thousands of individual cryoEM RyR1 particles. We find that under closed state conditions, in the presence of FKBP12, the cytoplasmic domain of RyR1 adopts an upward conformation, whereas absence of FKBP12 results in a relaxed conformation, while the ion gate remains closed. The relaxed conformation is intermediate between the RyR1-FKBP12 complex closed (upward) and open (downward) conformations. The closed-relaxed conformation of RyR1 appears to be consistent with a lower energy barrier separating the closed and open states of RyR1-FKBP12, and suggests that FKBP12 plays an important role by restricting conformations within RyR1's conformational landscape.
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Affiliation(s)
- Tyler W E Steele
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Montserrat Samsó
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298, United States.
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19
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Jones PP, MacQuaide N, Louch WE. Dyadic Plasticity in Cardiomyocytes. Front Physiol 2018; 9:1773. [PMID: 30618792 PMCID: PMC6298195 DOI: 10.3389/fphys.2018.01773] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/23/2018] [Indexed: 11/13/2022] Open
Abstract
Contraction of cardiomyocytes is dependent on sub-cellular structures called dyads, where invaginations of the surface membrane (t-tubules) form functional junctions with the sarcoplasmic reticulum (SR). Within each dyad, Ca2+ entry through t-tubular L-type Ca2+ channels (LTCCs) elicits Ca2+ release from closely apposed Ryanodine Receptors (RyRs) in the SR membrane. The efficiency of this process is dependent on the density and macroscale arrangement of dyads, but also on the nanoscale organization of LTCCs and RyRs within them. We presently review accumulating data demonstrating the remarkable plasticity of these structures. Dyads are known to form gradually during development, with progressive assembly of both t-tubules and junctional SR terminals, and precise trafficking of LTCCs and RyRs. While dyads can exhibit compensatory remodeling when required, dyadic degradation is believed to promote impaired contractility and arrythmogenesis in cardiac disease. Recent data indicate that this plasticity of dyadic structure/function is dependent on the regulatory proteins junctophilin-2, amphiphysin-2 (BIN1), and caveolin-3, which critically arrange dyadic membranes while stabilizing the position and activity of LTCCs and RyRs. Indeed, emerging evidence indicates that clustering of both channels enables "coupled gating", implying that nanoscale localization and function are intimately linked, and may allow fine-tuning of LTCC-RyR crosstalk. We anticipate that improved understanding of dyadic plasticity will provide greater insight into the processes of cardiac compensation and decompensation, and new opportunities to target the basic mechanisms underlying heart disease.
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Affiliation(s)
- Peter P. Jones
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- HeartOtago, University of Otago, Dunedin, New Zealand
| | - Niall MacQuaide
- Institute of Cardiovascular Sciences, University of Glasgow, Glasgow, United Kingdom
- Clyde Biosciences, Glasgow, United Kingdom
| | - William E. Louch
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway
- KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
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20
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Pomplun S, Sippel C, Hähle A, Tay D, Shima K, Klages A, Ünal CM, Rieß B, Toh HT, Hansen G, Yoon HS, Bracher A, Preiser P, Rupp J, Steinert M, Hausch F. Chemogenomic Profiling of Human and Microbial FK506-Binding Proteins. J Med Chem 2018; 61:3660-3673. [PMID: 29578710 DOI: 10.1021/acs.jmedchem.8b00137] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
FK506-binding proteins (FKBPs) are evolutionarily conserved proteins that display peptidyl-prolyl isomerase activities and act as coreceptors for immunosuppressants. Microbial macrophage-infectivity-potentiator (Mip)-type FKBPs can enhance infectivity. However, developing druglike ligands for FKBPs or Mips has proven difficult, and many FKBPs and Mips still lack biologically useful ligands. To explore the scope and potential of C5-substituted [4.3.1]-aza-bicyclic sulfonamides as a broadly applicable class of FKBP inhibitors, we developed a new synthesis method for the bicyclic core scaffold and used it to prepare an FKBP- and Mip-focused library. This allowed us to perform a systematic structure-activity-relationship analysis across key human FKBPs and microbial Mips, yielding highly improved inhibitors for all the FKBPs studied. A cocrystal structure confirmed the molecular-binding mode of the core structure and explained the affinity gained as a result of the preferred substituents. The best FKBP and Mip ligands showed promising antimalarial, antileginonellal, and antichlamydial properties in cellular models of infectivity, suggesting that substituted [4.3.1]-aza-bicyclic sulfonamides could be a novel class of anti-infectives.
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Affiliation(s)
- Sebastian Pomplun
- Department of Translational Research in Psychiatry , Max Planck Institute of Psychiatry , 80804 Munich , Germany
| | - Claudia Sippel
- Department of Translational Research in Psychiatry , Max Planck Institute of Psychiatry , 80804 Munich , Germany
| | - Andreas Hähle
- Department of Translational Research in Psychiatry , Max Planck Institute of Psychiatry , 80804 Munich , Germany.,Technical University Darmstadt , Alarich-Weiss-Straße 4 , 64287 Darmstadt , Germany
| | - Donald Tay
- School of Biological Sciences , Nanyang Technological University , 639798 Singapore
| | - Kensuke Shima
- Department of Infectious Diseases and Microbiology , University of Lübeck , 23562 Lübeck , Germany
| | - Alina Klages
- Technische Universität Braunschweig , 38106 Braunschweig , Germany
| | - Can Murat Ünal
- Technische Universität Braunschweig , 38106 Braunschweig , Germany
| | - Benedikt Rieß
- Department of Translational Research in Psychiatry , Max Planck Institute of Psychiatry , 80804 Munich , Germany
| | - Hui Ting Toh
- School of Biological Sciences , Nanyang Technological University , 639798 Singapore
| | | | - Ho Sup Yoon
- School of Biological Sciences , Nanyang Technological University , 639798 Singapore
| | - Andreas Bracher
- Max Planck Institute of Biochemistry , 82152 Martinsried , Germany
| | - Peter Preiser
- School of Biological Sciences , Nanyang Technological University , 639798 Singapore
| | - Jan Rupp
- Department of Infectious Diseases and Microbiology , University of Lübeck , 23562 Lübeck , Germany
| | - Michael Steinert
- Department of Infectious Diseases and Microbiology , University of Lübeck , 23562 Lübeck , Germany.,Helmholtz Centre for Infection Research , 38124 Braunschweig , Germany
| | - Felix Hausch
- Department of Translational Research in Psychiatry , Max Planck Institute of Psychiatry , 80804 Munich , Germany.,Technical University Darmstadt , Alarich-Weiss-Straße 4 , 64287 Darmstadt , Germany
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