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Robertson CD, Davis P, Richardson RR, Iffland PH, Vieira DCO, Steyert M, McKeon PN, Romanowski AJ, Crutcher G, Jašarević E, Wolff SBE, Mathur BN, Crino PB, Bale TL, Dick IE, Poulopoulos A. Rapid modeling of an ultra-rare epilepsy variant in wild-type mice by in utero prime editing. bioRxiv 2023:2023.12.06.570164. [PMID: 38106154 PMCID: PMC10723435 DOI: 10.1101/2023.12.06.570164] [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] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Generating animal models for individual patients within clinically-useful timeframes holds great potential toward enabling personalized medicine approaches for genetic epilepsies. The ability to rapidly incorporate patient-specific genomic variants into model animals recapitulating elements of the patient's clinical manifestations would enable applications ranging from validation and characterization of pathogenic variants to personalized models for tailoring pharmacotherapy to individual patients. Here, we demonstrate generation of an animal model of an individual epilepsy patient with an ultra-rare variant of the NMDA receptor subunit GRIN2A, without the need for germline transmission and breeding. Using in utero prime editing in the brain of wild-type mice, our approach yielded high in vivo editing precision and induced frequent, spontaneous seizures which mirrored specific elements of the patient's clinical presentation. Leveraging the speed and versatility of this approach, we introduce PegAssist, a generalizable workflow to generate bedside-to-bench animal models of individual patients within weeks. The capability to produce individualized animal models rapidly and cost-effectively will reduce barriers to access for precision medicine, and will accelerate drug development by offering versatile in vivo platforms to identify compounds with efficacy against rare neurological conditions.
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Affiliation(s)
- Colin D Robertson
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Patrick Davis
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ryan R Richardson
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Philip H Iffland
- Department of Neurology, and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Daiana C O Vieira
- Department of Physiology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Marilyn Steyert
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Paige N McKeon
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrea J Romanowski
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Garrett Crutcher
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Eldin Jašarević
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
- Current affiliations: MS: Department of Neurological Surgery, University of California San Francisco; EJ: Department Computational and Systems Biology, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine; TB: Department of Psychiatry, University of Colorado School of Medicine
| | - Steffen B E Wolff
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Brian N Mathur
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Peter B Crino
- Department of Neurology, and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tracy L Bale
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
- Current affiliations: MS: Department of Neurological Surgery, University of California San Francisco; EJ: Department Computational and Systems Biology, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine; TB: Department of Psychiatry, University of Colorado School of Medicine
| | - Ivy E Dick
- Department of Physiology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alexandros Poulopoulos
- Department of Pharmacology and UM-MIND, University of Maryland School of Medicine, Baltimore, MD, USA
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2
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Abstract
Calcium ions (Ca2+) are the basis of a unique and potent array of cellular responses. Calmodulin (CaM) is a small but vital protein that is able to rapidly transmit information about changes in Ca2+ concentrations to its regulatory targets. CaM plays a critical role in cellular Ca2+ signaling, and interacts with a myriad of target proteins. Ca2+-dependent modulation by CaM is a major component of a diverse array of processes, ranging from gene expression in neurons to the shaping of the cardiac action potential in heart cells. Furthermore, the protein sequence of CaM is highly evolutionarily conserved, and identical CaM proteins are encoded by three independent genes (CALM1-3) in humans. Mutations within any of these three genes may lead to severe cardiac deficits including severe long QT syndrome (LQTS) and/or catecholaminergic polymorphic ventricular tachycardia (CPVT). Research into disease-associated CaM variants has identified several proteins modulated by CaM that are likely to underlie the pathogenesis of these calmodulinopathies, including the cardiac L-type Ca2+ channel (LTCC) CaV1.2, and the sarcoplasmic reticulum Ca2+ release channel, ryanodine receptor 2 (RyR2). Here, we review the research that has been done to identify calmodulinopathic CaM mutations and evaluate the mechanisms underlying their role in disease.
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Affiliation(s)
- John W. Hussey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Worawan B. Limpitikul
- Department of Medicine, Division of Cardiology, Massachusetts General Hospital, Boston, MA, USA
| | - Ivy E. Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- CONTACT Ivy E. Dick School of Medicine, University of Maryland, Baltimore, MD21210
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3
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Herold KG, Bamgboye MA, DiSilvestre D, Hussey J, Owoyemi JO, Dick IE. Elucidating the role Ca v1.2 dysfunction in the pathogenesis of timothy syndrome using iPSC-derived neurons. Biophys J 2023; 122:105a-106a. [PMID: 36782454 DOI: 10.1016/j.bpj.2022.11.755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Kevin G Herold
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Moradeke A Bamgboye
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Deborah DiSilvestre
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
| | - John Hussey
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Josiah O Owoyemi
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Ivy E Dick
- Department of Physiology, University of Maryland Baltimore, Baltimore, MD, USA
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Abstract
The CACNA1C gene encodes the pore-forming subunit of the CaV1.2 L-type Ca2+ channel, a critical component of membrane physiology in multiple tissues, including the heart, brain, and immune system. As such, mutations altering the function of these channels have the potential to impact a wide array of cellular functions. The first mutations identified within CACNA1C were shown to cause a severe, multisystem disorder known as Timothy syndrome (TS), which is characterized by neurodevelopmental deficits, long-QT syndrome, life-threatening cardiac arrhythmias, craniofacial abnormalities, and immune deficits. Since this initial description, the number and variety of disease-associated mutations identified in CACNA1C have grown tremendously, expanding the range of phenotypes observed in affected patients. CACNA1C channelopathies are now known to encompass multisystem phenotypes as described in TS, as well as more selective phenotypes where patients may exhibit predominantly cardiac or neurological symptoms. Here, we review the impact of genetic mutations on CaV1.2 function and the resultant physiological consequences.
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Affiliation(s)
- Kevin G Herold
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - John W Hussey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ivy E Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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5
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Bamgboye MA, Traficante MK, Owoyemi J, DiSilvestre D, Vieira DCO, Dick IE. Impaired Ca V1.2 inactivation reduces the efficacy of calcium channel blockers in the treatment of LQT8. J Mol Cell Cardiol 2022; 173:92-100. [PMID: 36272554 PMCID: PMC10583761 DOI: 10.1016/j.yjmcc.2022.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [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: 06/20/2022] [Revised: 10/12/2022] [Accepted: 10/16/2022] [Indexed: 11/23/2022]
Abstract
Mutations in the CaV1.2 L-type calcium channel can cause a profound form of long-QT syndrome known as long-QT type 8 (LQT8), which results in cardiac arrhythmias that are often fatal in early childhood. A growing number of such pathogenic mutations in CaV1.2 have been identified, increasing the need for targeted therapies. As many of these mutations reduce channel inactivation; resulting in excess Ca2+ entry during the action potential, calcium channel blockers (CCBs) would seem to represent a promising treatment option. Yet CCBs have been unsuccessful in the treatment of LQT8. Here, we demonstrate that this lack of efficacy likely stems from the impact of the mutations on CaV1.2 channel inactivation. As CCBs are known to preferentially bind to the inactivated state of the channel, mutation-dependent deficits in inactivation result in a decrease in use-dependent block of the mutant channel. Further, application of the CCB verapamil to induced pluripotent stem cell (iPSC) derived cardiomyocytes from an LQT8 patient demonstrates that this loss of use-dependent block translates to a lack of efficacy in correcting the LQT phenotype. As a growing number of channelopathic mutations demonstrate effects on channel inactivation, reliance on state-dependent blockers may leave a growing population of patients without a viable treatment option. This biophysical understanding of the interplay between inactivation deficits and state-dependent block may provide a new avenue to guide the development of improved therapies.
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Affiliation(s)
- Moradeke A Bamgboye
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America
| | - Maria K Traficante
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America
| | - Josiah Owoyemi
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America
| | - Deborah DiSilvestre
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America
| | - Daiana C O Vieira
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America
| | - Ivy E Dick
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, MD, United States of America.
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Bamgboye MA, Herold KG, Vieira DC, Traficante MK, Rogers PJ, Ben-Johny M, Dick IE. CaV1.2 channelopathic mutations evoke diverse pathophysiological mechanisms. J Gen Physiol 2022; 154:e202213209. [PMID: 36167061 PMCID: PMC9524202 DOI: 10.1085/jgp.202213209] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/09/2022] [Accepted: 09/13/2022] [Indexed: 01/17/2023] Open
Abstract
The first pathogenic mutation in CaV1.2 was identified in 2004 and was shown to cause a severe multisystem disorder known as Timothy syndrome (TS). The mutation was localized to the distal S6 region of the channel, a region known to play a major role in channel activation. TS patients suffer from life-threatening cardiac symptoms as well as significant neurodevelopmental deficits, including autism spectrum disorder (ASD). Since this discovery, the number and variety of mutations identified in CaV1.2 have grown tremendously, and the distal S6 regions remain a frequent locus for many of these mutations. While the majority of patients harboring these mutations exhibit cardiac symptoms that can be well explained by known pathogenic mechanisms, the same cannot be said for the ASD or neurodevelopmental phenotypes seen in some patients, indicating a gap in our understanding of the pathogenesis of CaV1.2 channelopathies. Here, we use whole-cell patch clamp, quantitative Ca2+ imaging, and single channel recordings to expand the known mechanisms underlying the pathogenesis of CaV1.2 channelopathies. Specifically, we find that mutations within the S6 region can exert independent and separable effects on activation, voltage-dependent inactivation (VDI), and Ca2+-dependent inactivation (CDI). Moreover, the mechanisms underlying the CDI effects of these mutations are varied and include altered channel opening and possible disruption of CDI transduction. Overall, these results provide a structure-function framework to conceptualize the role of S6 mutations in pathophysiology and offer insight into the biophysical defects associated with distinct clinical manifestations.
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Affiliation(s)
- Moradeke A. Bamgboye
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Kevin G. Herold
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Daiana C.O. Vieira
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Maria K. Traficante
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Philippa J. Rogers
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Manu Ben-Johny
- Department of Physiology and Biophysics, Columbia University, New York, NY
| | - Ivy E. Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
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7
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Chakouri N, Rivas S, Roybal D, Yang L, Diaz J, Hsu A, Mahling R, Chen BX, Owoyemi JO, DiSilvestre D, Sirabella D, Corneo B, Tomaselli GF, Dick IE, Marx SO, Ben-Johny M. Fibroblast growth factor homologous factors serve as a molecular rheostat in tuning arrhythmogenic cardiac late sodium current. Nat Cardiovasc Res 2022; 1:1-13. [PMID: 35662881 PMCID: PMC9161660 DOI: 10.1038/s44161-022-00060-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/04/2022] [Indexed: 05/20/2023]
Abstract
Voltage-gated sodium (Nav1.5) channels support the genesis and brisk spatial propagation of action potentials in the heart. Disruption of NaV1.5 inactivation results in a small persistent Na influx known as late Na current (I Na,L), which has emerged as a common pathogenic mechanism in both congenital and acquired cardiac arrhythmogenic syndromes. Here, using low-noise multi-channel recordings in heterologous systems, LQTS3 patient-derived iPSCs cardiomyocytes, and mouse ventricular myocytes, we demonstrate that the intracellular fibroblast growth factor homologous factors (FHF1-4) tune pathogenic I Na,L in an isoform-specific manner. This scheme suggests a complex orchestration of I Na,L in cardiomyocytes that may contribute to variable disease expressivity of NaV1.5 channelopathies. We further leverage these observations to engineer a peptide-inhibitor of I Na,L with a higher efficacy as compared to a well-established small-molecule inhibitor. Overall, these findings lend insights into molecular mechanisms underlying FHF regulation of I Na,L in pathophysiology and outline potential therapeutic avenues.
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Affiliation(s)
- Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Sharen Rivas
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Daniel Roybal
- Department of Pharmacology, Columbia University, New York, NY, USA
| | - Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University, New York, NY, USA
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Allen Hsu
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Ryan Mahling
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Bi-Xing Chen
- Division of Cardiology, Department of Medicine, Columbia University, New York, NY, USA
| | | | - Deborah DiSilvestre
- Department Physiology, University of Maryland, Baltimore, MD, USA
- Division of Cardiology, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Dario Sirabella
- Columbia Stem Cell Initiative, Stem Cell Core, Columbia University Irving Medical Center, NY, USA
| | - Barbara Corneo
- Columbia Stem Cell Initiative, Stem Cell Core, Columbia University Irving Medical Center, NY, USA
| | - Gordon F. Tomaselli
- Department of Medicine, Albert Einstein College of Medicine, New York, NY, USA
- Division of Cardiology, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Ivy E. Dick
- Department Physiology, University of Maryland, Baltimore, MD, USA
| | - Steven O. Marx
- Department of Pharmacology, Columbia University, New York, NY, USA
- Division of Cardiology, Department of Medicine, Columbia University, New York, NY, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
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8
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Vieira DC, owoyemi JO, DiSilvestre D, Bamgboye MA, Dick IE. LQT8 mutations induce action potential prolongation and arrhythmia in induced pluripotent stem cell derived cardiomyocytes. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2232] [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: 11/28/2022] Open
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9
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Herold KG, Bamgboye MA, Vieira DC, DiSilvestre D, Hussey JW, Owoyemi JO, Meredith AL, Dick IE. Evaluating the impact of Cav1.2 mutations on neuronal function. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2225] [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: 11/02/2022] Open
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10
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Brohus M, Arsov T, Wallace DA, Jensen HH, Nyegaard M, Crotti L, Adamski M, Zhang Y, Field MA, Athanasopoulos V, Baró I, Ribeiro de Oliveira-Mendes BB, Redon R, Charpentier F, Raju H, DiSilvestre D, Wei J, Wang R, Rafehi H, Kaspi A, Bahlo M, Dick IE, Chen SRW, Cook MC, Vinuesa CG, Overgaard MT, Schwartz PJ. Infanticide vs. inherited cardiac arrhythmias. Europace 2020; 23:441-450. [PMID: 33200177 PMCID: PMC7947592 DOI: 10.1093/europace/euaa272] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 01/28/2023] Open
Abstract
AIMS In 2003, an Australian woman was convicted by a jury of smothering and killing her four children over a 10-year period. Each child died suddenly and unexpectedly during a sleep period, at ages ranging from 19 days to 18 months. In 2019 we were asked to investigate if a genetic cause could explain the children's deaths as part of an inquiry into the mother's convictions. METHODS AND RESULTS Whole genomes or exomes of the mother and her four children were sequenced. Functional analysis of a novel CALM2 variant was performed by measuring Ca2+-binding affinity, interaction with calcium channels and channel function. We found two children had a novel calmodulin variant (CALM2 G114R) that was inherited maternally. Three genes (CALM1-3) encode identical calmodulin proteins. A variant in the corresponding residue of CALM3 (G114W) was recently reported in a child who died suddenly at age 4 and a sibling who suffered a cardiac arrest at age 5. We show that CALM2 G114R impairs calmodulin's ability to bind calcium and regulate two pivotal calcium channels (CaV1.2 and RyR2) involved in cardiac excitation contraction coupling. The deleterious effects of G114R are similar to those produced by G114W and N98S, which are considered arrhythmogenic and cause sudden cardiac death in children. CONCLUSION A novel functional calmodulin variant (G114R) predicted to cause idiopathic ventricular fibrillation, catecholaminergic polymorphic ventricular tachycardia, or mild long QT syndrome was present in two children. A fatal arrhythmic event may have been triggered by their intercurrent infections. Thus, calmodulinopathy emerges as a reasonable explanation for a natural cause of their deaths.
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Affiliation(s)
- Malene Brohus
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark
| | - Todor Arsov
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia,Department of Pediatrics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - David A Wallace
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia
| | - Helene Halkjær Jensen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark
| | - Mette Nyegaard
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - Lia Crotti
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy,Department of Cardiovascular, Neural and Metabolic Sciences, Istituto Auxologico Italiano, IRCCS, San Luca Hospital, Milan, Italy,Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Marcin Adamski
- Biology Teaching and Learning Centre, Research School of Biology and John Curtin School of Medical Research, The Australian National University, Canberra, Acton 2601, Australia
| | - Yafei Zhang
- NGS Team, Australian Phenomics Facility, John Curtin School of Medical Research, Australian National University, Canberra, Acton 2601, Australia
| | - Matt A Field
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia,Centre for Tropical Bioinformatics and Molecular Biology, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland 4878, Australia
| | - Vicki Athanasopoulos
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia
| | - Isabelle Baró
- Université de Nantes, CNRS, INSERM, L’institut du Thorax, F-44000 Nantes, France
| | | | - Richard Redon
- Université de Nantes, CNRS, INSERM, L’institut du Thorax, F-44000 Nantes, France
| | - Flavien Charpentier
- Université de Nantes, CNRS, INSERM, L’institut du Thorax, F-44000 Nantes, France
| | - Hariharan Raju
- Cardiology Department, Faculty of Medicine, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Deborah DiSilvestre
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jinhong Wei
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Ruiwu Wang
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Haloom Rafehi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Royal Parade, Parkville, Victoria 3052, Australia,Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Antony Kaspi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Royal Parade, Parkville, Victoria 3052, Australia,Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Royal Parade, Parkville, Victoria 3052, Australia,Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Ivy E Dick
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sui Rong Wayne Chen
- Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Matthew C Cook
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia
| | - Carola G Vinuesa
- Department of Immunology and Infectious Disease, Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, Acton 2601, Australia,Corresponding authors. +39 0255000408/9. E-mail address: (P.J.S.); Tel +45 9940 8525. E-mail address: (M.T.O.); Tel +61 432130556. E-mail address: (C.G.V.)
| | - Michael Toft Overgaard
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220 Aalborg, Denmark,Corresponding authors. +39 0255000408/9. E-mail address: (P.J.S.); Tel +45 9940 8525. E-mail address: (M.T.O.); Tel +61 432130556. E-mail address: (C.G.V.)
| | - Peter J Schwartz
- Istituto Auxologico Italiano, IRCCS, Center for Cardiac Arrhythmias of Genetic Origin, Via Pier Lombardo, 22, 20135 Milan, Italy,Corresponding authors. +39 0255000408/9. E-mail address: (P.J.S.); Tel +45 9940 8525. E-mail address: (M.T.O.); Tel +61 432130556. E-mail address: (C.G.V.)
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11
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Bamgboye MA, Owoyemi JO, Herold KG, Traficante MK, Dick IE. Towards a Deeper Understanding of the Diverse Roles of the CaV1.2 S6. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2753] [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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12
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Hussey JW, Jensen HH, Nyegaard M, Overgaard MT, Dick IE. Probing the Effects of Calmodulinopathy Mutations on Cav2.1 Channels. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.725] [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: 11/16/2022] Open
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13
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Bamgboye MA, Traficante M, Yue DT, Dick IE. Treatment of CaV1.2 Channelopathies May Be Complicated by Altered Channel Inactivation. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.633] [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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14
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Limpitikul WB, Greenstein JL, Yue DT, Dick IE, Winslow RL. A bilobal model of Ca 2+-dependent inactivation to probe the physiology of L-type Ca 2+ channels. J Gen Physiol 2018; 150:1688-1701. [PMID: 30470716 PMCID: PMC6279366 DOI: 10.1085/jgp.201812115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 08/01/2018] [Accepted: 10/26/2018] [Indexed: 12/20/2022] Open
Abstract
L-type calcium channels undergo Ca2+-dependent inactivation (CDI) in order to precisely control the entry of Ca2+ into cells such as cardiomyocytes. Limpitikul et al. develop a bilobal model of CDI and use it to understand the pathogenesis of arrhythmias associated with mutations in CaM. L-type calcium channels (LTCCs) are critical elements of normal cardiac function, playing a major role in orchestrating cardiac electrical activity and initiating downstream signaling processes. LTCCs thus use feedback mechanisms to precisely control calcium (Ca2+) entry into cells. Of these, Ca2+-dependent inactivation (CDI) is significant because it shapes cardiac action potential duration and is essential for normal cardiac rhythm. This important form of regulation is mediated by a resident Ca2+ sensor, calmodulin (CaM), which is comprised of two lobes that are each capable of responding to spatially distinct Ca2+ sources. Disruption of CaM-mediated CDI leads to severe forms of long-QT syndrome (LQTS) and life-threatening arrhythmias. Thus, a model capable of capturing the nuances of CaM-mediated CDI would facilitate increased understanding of cardiac (patho)physiology. However, one critical barrier to achieving a detailed kinetic model of CDI has been the lack of quantitative data characterizing CDI as a function of Ca2+. This data deficit stems from the experimental challenge of uncoupling the effect of channel gating on Ca2+ entry. To overcome this obstacle, we use photo-uncaging of Ca2+ to deliver a measurable Ca2+ input to CaM/LTCCs, while simultaneously recording CDI. Moreover, we use engineered CaMs with Ca2+ binding restricted to a single lobe, to isolate the kinetic response of each lobe. These high-resolution measurements enable us to build mathematical models for each lobe of CaM, which we use as building blocks for a full-scale bilobal model of CDI. Finally, we use this model to probe the pathogenesis of LQTS associated with mutations in CaM (calmodulinopathies). Each of these models accurately recapitulates the kinetics and steady-state properties of CDI in both physiological and pathological states, thus offering powerful new insights into the mechanistic alterations underlying cardiac arrhythmias.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Joseph L Greenstein
- Institute for Computational Medicine, Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD .,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Raimond L Winslow
- Institute for Computational Medicine, Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD
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Niu J, Dick IE, Yang W, Bamgboye MA, Yue DT, Tomaselli G, Inoue T, Ben-Johny M. Allosteric regulators selectively prevent Ca 2+-feedback of Ca V and Na V channels. eLife 2018; 7:35222. [PMID: 30198845 PMCID: PMC6156082 DOI: 10.7554/elife.35222] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 09/09/2018] [Indexed: 12/31/2022] Open
Abstract
Calmodulin (CaM) serves as a pervasive regulatory subunit of CaV1, CaV2, and NaV1 channels, exploiting a functionally conserved carboxy-tail element to afford dynamic Ca2+-feedback of cellular excitability in neurons and cardiomyocytes. Yet this modularity counters functional adaptability, as global changes in ambient CaM indiscriminately alter its targets. Here, we demonstrate that two structurally unrelated proteins, SH3 and cysteine-rich domain (stac) and fibroblast growth factor homologous factors (fhf) selectively diminish Ca2+/CaM-regulation of CaV1 and NaV1 families, respectively. The two proteins operate on allosteric sites within upstream portions of respective channel carboxy-tails, distinct from the CaM-binding interface. Generalizing this mechanism, insertion of a short RxxK binding motif into CaV1.3 carboxy-tail confers synthetic switching of CaM regulation by Mona SH3 domain. Overall, our findings identify a general class of auxiliary proteins that modify Ca2+/CaM signaling to individual targets allowing spatial and temporal orchestration of feedback, and outline strategies for engineering Ca2+/CaM signaling to individual targets.
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Affiliation(s)
- Jacqueline Niu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States
| | - Ivy E Dick
- Department of Physiology, University of Maryland, Baltimore, United States
| | - Wanjun Yang
- Department of Cardiology, Johns Hopkins University, Baltimore, United States
| | | | - David T Yue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States
| | - Gordon Tomaselli
- Department of Cardiology, Johns Hopkins University, Baltimore, United States
| | - Takanari Inoue
- Department of Cell Biology, Johns Hopkins University, Baltimore, United States.,Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, Baltimore, United States
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, New York, United States
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Bamgboye MA, Traficante MK, Yue DT, Dick IE. Probing the Pathogenic Mechanisms Underlying CaV 1.2 Channelopathies. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3452] [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: 11/26/2022] Open
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17
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Limpitikul WB, Dick IE, Tester DJ, Boczek NJ, Limphong P, Yang W, Choi MH, Babich J, DiSilvestre D, Kanter RJ, Tomaselli GF, Ackerman MJ, Yue DT. A Precision Medicine Approach to the Rescue of Function on Malignant Calmodulinopathic Long-QT Syndrome. Circ Res 2016; 120:39-48. [PMID: 27765793 DOI: 10.1161/circresaha.116.309283] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [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: 06/11/2016] [Revised: 10/17/2016] [Accepted: 10/20/2016] [Indexed: 12/24/2022]
Abstract
RATIONALE Calmodulinopathies comprise a new category of potentially life-threatening genetic arrhythmia syndromes capable of producing severe long-QT syndrome (LQTS) with mutations involving CALM1, CALM2, or CALM3. The underlying basis of this form of LQTS is a disruption of Ca2+/calmodulin (CaM)-dependent inactivation of L-type Ca2+ channels. OBJECTIVE To gain insight into the mechanistic underpinnings of calmodulinopathies and devise new therapeutic strategies for the treatment of this form of LQTS. METHODS AND RESULTS We generated and characterized the functional properties of induced pluripotent stem cell-derived cardiomyocytes from a patient with D130G-CALM2-mediated LQTS, thus creating a platform with which to devise and test novel therapeutic strategies. The patient-derived induced pluripotent stem cell-derived cardiomyocytes display (1) significantly prolonged action potentials, (2) disrupted Ca2+ cycling properties, and (3) diminished Ca2+/CaM-dependent inactivation of L-type Ca2+ channels. Next, taking advantage of the fact that calmodulinopathy patients harbor a mutation in only 1 of 6 redundant CaM-encoding alleles, we devised a strategy using CRISPR interference to selectively suppress the mutant gene while sparing the wild-type counterparts. Indeed, suppression of CALM2 expression produced a functional rescue in induced pluripotent stem cell-derived cardiomyocytes with D130G-CALM2, as shown by the normalization of action potential duration and Ca2+/CaM-dependent inactivation after treatment. Moreover, CRISPR interference can be designed to achieve selective knockdown of any of the 3 CALM genes, making it a generalizable therapeutic strategy for any calmodulinopathy. CONCLUSIONS Overall, this therapeutic strategy holds great promise for calmodulinopathy patients as it represents a generalizable intervention capable of specifically altering CaM expression and potentially attenuating LQTS-triggered cardiac events, thus initiating a path toward precision medicine.
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Affiliation(s)
- Worawan B Limpitikul
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Ivy E Dick
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - David J Tester
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Nicole J Boczek
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Pattraranee Limphong
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Wanjun Yang
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Myoung Hyun Choi
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Jennifer Babich
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Deborah DiSilvestre
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Ronald J Kanter
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - Gordon F Tomaselli
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.).
| | - Michael J Ackerman
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
| | - David T Yue
- From the Calcium Signals Laboratory, Department of Biomedical Engineering (W.B.L., I.E.D., W.Y., M.H.C., J.B., D.T.Y.) and Division of Cardiology, Department of Medicine (P.L., D.D., G.F.T.), The Johns Hopkins University School of Medicine, Baltimore, MD; Department of Physiology, The University of Maryland School of Medicine, Baltimore (I.E.D.); Division of Heart Rhythm Services, Department of Cardiovascular Diseases (D.J.T., N.J.B., M.J.A.), Division of Pediatric Cardiology, Department of Pediatrics (D.J.T., N.J.B., M.J.A.), and Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics (D.J.T., N.J.B., M.J.A.), Mayo Clinic, Rochester, MN; and Division of Cardiology, Nicklaus Children's Hospital, Miami, FL (R.J.K.)
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Niu J, Ben Johny M, Dick IE, Inoue T. Following Optogenetic Dimerizers and Quantitative Prospects. Biophys J 2016; 111:1132-1140. [PMID: 27542508 DOI: 10.1016/j.bpj.2016.07.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 07/22/2016] [Accepted: 07/22/2016] [Indexed: 01/06/2023] Open
Abstract
Optogenetics describes the use of genetically encoded photosensitive proteins to direct intended biological processes with light in recombinant and native systems. While most of these light-responsive proteins were originally discovered in photosynthetic organisms, the past few decades have been punctuated by experiments that not only commandeer but also engineer and enhance these natural tools to explore a wide variety of physiological questions. In addition, the ability to tune dynamic range and kinetic rates of optogenetic actuators is a challenging question that is heavily explored with computational methods devised to facilitate optimization of these systems. Here, we explain the basic mechanisms of a few popular photodimerizing optogenetic systems, discuss applications, compare optogenetic tools against more traditional chemical methods, and propose a simple quantitative understanding of how actuators exert their influence on targeted processes.
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Affiliation(s)
- Jacqueline Niu
- Department of Biomedical Engineering, School of Medicine, The Johns Hopkins University, Baltimore, Maryland.
| | - Manu Ben Johny
- Department of Biomedical Engineering, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
| | - Ivy E Dick
- Department of Biomedical Engineering, School of Medicine, The Johns Hopkins University, Baltimore, Maryland; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Takanari Inoue
- Department of Biomedical Engineering, School of Medicine, The Johns Hopkins University, Baltimore, Maryland; Department of Cell Biology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland; The Center for Cell Dynamics, Institute for Basic Biomedical Sciences, The Johns Hopkins University, Baltimore, Maryland; Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan.
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Abstract
The regulation of L-type Ca2+ channels by protein kinase A (PKA) represents a crucial element within cardiac, skeletal muscle and neurological systems. Although much work has been done to understand this regulation in cardiac CaV1.2 Ca2+ channels, relatively little is known about the closely related CaV1.4 L-type Ca2+ channels, which feature prominently in the visual system. Here we find that CaV1.4 channels are indeed modulated by PKA phosphorylation within the inhibitor of Ca2+-dependent inactivation (ICDI) motif. Phosphorylation of this region promotes the occupancy of calmodulin on the channel, thus increasing channel open probability (PO) and Ca2+-dependent inactivation. Although this interaction seems specific to CaV1.4 channels, introduction of ICDI1.4 to CaV1.3 or CaV1.2 channels endows these channels with a form of PKA modulation, previously unobserved in heterologous systems. Thus, this mechanism may not only play an important role in the visual system but may be generalizable across the L-type channel family. Phosphorylation of L-type calcium CaV channels by protein kinase A is essential for several physiological events. Here, the authors show how this kinase regulates CaV1.4 activity, suggesting a general regulatory mechanism for all L-type calcium channels.
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Affiliation(s)
- Lingjie Sang
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Ben-Johny M, Dick IE, Sang L, Limpitikul WB, Kang PW, Niu J, Banerjee R, Yang W, Babich JS, Issa JB, Lee SR, Namkung H, Li J, Zhang M, Yang PS, Bazzazi H, Adams PJ, Joshi-Mukherjee R, Yue DN, Yue DT. Towards a Unified Theory of Calmodulin Regulation (Calmodulation) of Voltage-Gated Calcium and Sodium Channels. Curr Mol Pharmacol 2016; 8:188-205. [PMID: 25966688 DOI: 10.2174/1874467208666150507110359] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 01/29/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na and Ca(2+) channels represent two major ion channel families that enable myriad biological functions including the generation of action potentials and the coupling of electrical and chemical signaling in cells. Calmodulin regulation (calmodulation) of these ion channels comprises a vital feedback mechanism with distinct physiological implications. Though long-sought, a shared understanding of the channel families remained elusive for two decades as the functional manifestations and the structural underpinnings of this modulation often appeared to diverge. Here, we review recent advancements in the understanding of calmodulation of Ca(2+) and Na channels that suggest a remarkable similarity in their regulatory scheme. This interrelation between the two channel families now paves the way towards a unified mechanistic framework to understand vital calmodulin-dependent feedback and offers shared principles to approach related channelopathic diseases. An exciting era of synergistic study now looms.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - David T Yue
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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Limpitikul WB, Dick IE, Ben-Johny M, Yue DT. An autism-associated mutation in CaV1.3 channels has opposing effects on voltage- and Ca(2+)-dependent regulation. Sci Rep 2016; 6:27235. [PMID: 27255217 PMCID: PMC4891671 DOI: 10.1038/srep27235] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/13/2016] [Indexed: 01/07/2023] Open
Abstract
CaV1.3 channels are a major class of L-type Ca(2+) channels which contribute to the rhythmicity of the heart and brain. In the brain, these channels are vital for excitation-transcription coupling, synaptic plasticity, and neuronal firing. Moreover, disruption of CaV1.3 function has been associated with several neurological disorders. Here, we focus on the de novo missense mutation A760G which has been linked to autism spectrum disorder (ASD). To explore the role of this mutation in ASD pathogenesis, we examined the effects of A760G on CaV1.3 channel gating and regulation. Introduction of the mutation severely diminished the Ca(2+)-dependent inactivation (CDI) of CaV1.3 channels, an important feedback system required for Ca(2+) homeostasis. This reduction in CDI was observed in two major channel splice variants, though to different extents. Using an allosteric model of channel gating, we found that the underlying mechanism of CDI reduction is likely due to enhanced channel opening within the Ca(2+)-inactivated mode. Remarkably, the A760G mutation also caused an opposite increase in voltage-dependent inactivation (VDI), resulting in a multifaceted mechanism underlying ASD. When combined, these regulatory deficits appear to increase the intracellular Ca(2+) concentration, thus potentially disrupting neuronal development and synapse formation, ultimately leading to ASD.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713,720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Ivy E Dick
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713,720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Manu Ben-Johny
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713,720 Rutland Avenue, Baltimore, MD 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713,720 Rutland Avenue, Baltimore, MD 21205, USA
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Limpitikul WB, Limphong P, Dick IE, Hyun Choi M, Yang W, Babich J, Tester DJ, Ackerman MJ, Tomaselli GF, Yue DT. Functional Rescue of Calmodulinopathy IPSC-Derived Cardiomyocytes -- a Foray into Personalized Medicine. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2367] [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: 11/28/2022] Open
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Dick IE, Joshi-Mukherjee R, Yang W, Limpitikul WB, Yue DT. Toward a new Therapeutic Strategy in the Treatment of Timothy Syndrome. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2366] [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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Dick IE, Joshi-Mukherjee R, Yang W, Yue DT. Arrhythmogenesis in Timothy Syndrome is associated with defects in Ca(2+)-dependent inactivation. Nat Commun 2016; 7:10370. [PMID: 26822303 PMCID: PMC4740114 DOI: 10.1038/ncomms10370] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 12/03/2015] [Indexed: 12/18/2022] Open
Abstract
Timothy Syndrome (TS) is a multisystem disorder, prominently featuring cardiac action potential prolongation with paroxysms of life-threatening arrhythmias. The underlying defect is a single de novo missense mutation in CaV1.2 channels, either G406R or G402S. Notably, these mutations are often viewed as equivalent, as they produce comparable defects in voltage-dependent inactivation and cause similar manifestations in patients. Yet, their effects on calcium-dependent inactivation (CDI) have remained uncertain. Here, we find a significant defect in CDI in TS channels, and uncover a remarkable divergence in the underlying mechanism for G406R versus G402S variants. Moreover, expression of these TS channels in cultured adult guinea pig myocytes, combined with a quantitative ventricular myocyte model, reveals a threshold behaviour in the induction of arrhythmias due to TS channel expression, suggesting an important therapeutic principle: a small shift in the complement of mutant versus wild-type channels may confer significant clinical improvement. Timothy Syndrome (TS) is a multisystem disorder caused by two mutations leading to dysfunction of the CaV1.2 channel. Here, Dick et al. uncover a major and mechanistically divergent effect of both mutations on Ca2+/calmodulin-dependent inactivation of CaV1.2 channels, suggesting genetic variant-tailored therapy for TS treatment.
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Affiliation(s)
- Ivy E Dick
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Rosy Joshi-Mukherjee
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Wanjun Yang
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
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Bazzazi H, Sang L, Dick IE, Joshi-Mukherjee R, Yang W, Yue DT. Novel fluorescence resonance energy transfer-based reporter reveals differential calcineurin activation in neonatal and adult cardiomyocytes. J Physiol 2015; 593:3865-84. [PMID: 26096996 DOI: 10.1113/jp270510] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/16/2015] [Indexed: 12/26/2022] Open
Abstract
Novel fluorescence resonance energy transfer-based genetically encoded reporters of calcineurin are constructed by fusing the two subunits of calcineurin with P2A-based linkers retaining the expected native conformation of calcineurin. Calcineurin reporters display robust responses to calcium transients in HEK293 cells. The sensor responses are correlated with NFATc1 translocation dynamics in HEK293 cells. The sensors are uniformly distributed in neonatal myocytes and respond efficiently to single electrically evoked calcium transients and show cumulative activation at frequencies of 0.5 and 1 Hz. In adult myocytes, the calcineurin sensors appear to be localized to the cardiac z-lines, and respond to cumulative calcium transients at frequencies of 0.5 and 1 Hz. The phosphatase calcineurin is a central component of many calcium signalling pathways, relaying calcium signals from the plasma membrane to the nucleus. It has critical functions in a multitude of systems, including immune, cardiac and neuronal. Given the widespread importance of calcineurin in both normal and pathological conditions, new tools that elucidate the spatiotemporal dynamics of calcineurin activity would be invaluable. Here we develop two separate genetically encoded fluorescence resonance energy transfer (FRET)-based sensors of calcineurin activation, DuoCaN and UniCaN. Both sensors showcase a large dynamic range and rapid response kinetics, differing primarily in the linker structure between the FRET pairs. Both sensors were calibrated in HEK293 cells and their responses correlated well with NFAT translocation to the nucleus, validating the biological relevance of the sensor readout. The sensors were subsequently expressed in neonatal rat ventricular myocytes and acutely isolated adult guinea pig ventricular myocytes. Both sensors demonstrated robust responses in myocytes and revealed kinetic differences in calcineurin activation during changes in pacing rate for neonatal versus adult myocytes. Finally, mathematical modelling combined with quantitative FRET measurements provided novel insights into the kinetics and integration of calcineurin activation in response to myocyte Ca transients. In all, DuoCaN and UniCaN stand as valuable new tools for understanding the role of calcineurin in normal and pathological signalling.
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Affiliation(s)
- Hojjat Bazzazi
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lingjie Sang
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ivy E Dick
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rosy Joshi-Mukherjee
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wanjun Yang
- Departments of Biomedical Engineering and Neuroscience, Centre for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Dick IE, Limpitikul WB, Niu J, Banerjee R, Issa JB, Ben-Johny M, Adams PJ, Kang PW, Lee SR, Sang L, Yang W, Babich J, Zhang M, Bazazzi H, Yue NC, Tomaselli GF. A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory. Channels (Austin) 2015; 10:20-32. [PMID: 26176690 DOI: 10.1080/19336950.2015.1051272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca(2+) signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.
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Affiliation(s)
- Ivy E Dick
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Worawan B Limpitikul
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jacqueline Niu
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Rahul Banerjee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - John B Issa
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manu Ben-Johny
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Paul J Adams
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,b Kwantlen Polytechnic University ; Surrey , BC Canada
| | - Po Wei Kang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Shin Rong Lee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Lingjie Sang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Wanjun Yang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jennifer Babich
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manning Zhang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Hojjat Bazazzi
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Nancy C Yue
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Gordon F Tomaselli
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,c Division of Cardiology; Department of Medicine ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
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Adams PJ, Ben-Johny M, Dick IE, Inoue T, Yue DT. Apocalmodulin itself promotes ion channel opening and Ca(2+) regulation. Cell 2015; 159:608-22. [PMID: 25417111 DOI: 10.1016/j.cell.2014.09.047] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/25/2014] [Accepted: 09/26/2014] [Indexed: 11/16/2022]
Abstract
The Ca(2+)-free form of calmodulin (apoCaM) often appears inert, modulating target molecules only upon conversion to its Ca(2+)-bound form. This schema has appeared to govern voltage-gated Ca(2+) channels, where apoCaM has been considered a dormant Ca(2+) sensor, associated with channels but awaiting the binding of Ca(2+) ions before inhibiting channel opening to provide vital feedback inhibition. Using single-molecule measurements of channels and chemical dimerization to elevate apoCaM, we find that apoCaM binding on its own markedly upregulates opening, rivaling the strongest forms of modulation. Upon Ca(2+) binding to this CaM, inhibition may simply reverse the initial upregulation. As RNA-edited and -spliced channel variants show different affinities for apoCaM, the apoCaM-dependent control mechanisms may underlie the functional diversity of these variants and explain an elongation of neuronal action potentials by apoCaM. More broadly, voltage-gated Na channels adopt this same modulatory principle. ApoCaM thus imparts potent and pervasive ion-channel regulation. PAPERCLIP:
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Affiliation(s)
- Paul J Adams
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, Center for Cell Dynamics, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Manu Ben-Johny
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, Center for Cell Dynamics, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Ivy E Dick
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, Center for Cell Dynamics, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA
| | - Takanari Inoue
- Department of Cell Biology and Center for Cell Dynamics, The Johns Hopkins University School of Medicine, 855 N. Wolfe Street, Baltimore, MD 21205, USA; Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - David T Yue
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, Center for Cell Dynamics, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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Sang L, Dick IE, Yue DT. Live Cell Biochemistry Implicates Protein Kinase a Modulation of L-Type CaV1.4 Channels. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2010] [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: 11/30/2022] Open
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Limpitikul WB, Dick IE, Joshi-Mukherjee R, Overgaard MT, George AL, Yue DT. Calmodulin mutations associated with long QT syndrome prevent inactivation of cardiac L-type Ca(2+) currents and promote proarrhythmic behavior in ventricular myocytes. J Mol Cell Cardiol 2014; 74:115-24. [PMID: 24816216 DOI: 10.1016/j.yjmcc.2014.04.022] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [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: 04/11/2014] [Accepted: 04/28/2014] [Indexed: 01/13/2023]
Abstract
Recent work has identified missense mutations in calmodulin (CaM) that are associated with severe early-onset long-QT syndrome (LQTS), leading to the proposition that altered CaM function may contribute to the molecular etiology of this subset of LQTS. To date, however, no experimental evidence has established these mutations as directly causative of LQTS substrates, nor have the molecular targets of CaM mutants been identified. Here, therefore, we test whether expression of CaM mutants in adult guinea-pig ventricular myocytes (aGPVM) induces action-potential prolongation, and whether affiliated alterations in the Ca(2+) regulation of L-type Ca(2+) channels (LTCC) might contribute to such prolongation. In particular, we first overexpressed CaM mutants in aGPVMs, and observed both increased action potential duration (APD) and heightened Ca(2+) transients. Next, we demonstrated that all LQTS CaM mutants have the potential to strongly suppress Ca(2+)/CaM-dependent inactivation (CDI) of LTCCs, whether channels were heterologously expressed in HEK293 cells, or present in native form within myocytes. This attenuation of CDI is predicted to promote action-potential prolongation and boost Ca(2+) influx. Finally, we demonstrated how a small fraction of LQTS CaM mutants (as in heterozygous patients) would nonetheless suffice to substantially diminish CDI, and derange electrical and Ca(2+) profiles. In all, these results highlight LTCCs as a molecular locus for understanding and treating CaM-related LQTS in this group of patients.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Rosy Joshi-Mukherjee
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Michael T Overgaard
- Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Denmark
| | - Alfred L George
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205; Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205.
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Adams P, Ben Johny M, Dick IE, Yue DT. Chemical-Biological Generator of Step Increases in Calmodulin Reveals Dual Modulation of L-Type Ca2+ Channels. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.1903] [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: 11/24/2022] Open
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Joshi-Mukherjee R, Dick IE, Liu T, O'Rourke B, Yue DT, Tung L. Structural and functional plasticity in long-term cultures of adult ventricular myocytes. J Mol Cell Cardiol 2013; 65:76-87. [PMID: 24076394 DOI: 10.1016/j.yjmcc.2013.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/20/2013] [Accepted: 09/16/2013] [Indexed: 11/25/2022]
Abstract
Cultured heart cells have long been valuable for characterizing biological mechanism and disease pathogenesis. However, these preparations have limitations, relating to immaturity in key properties like excitation-contraction coupling and β-adrenergic stimulation. Progressive attenuation of the latter is intimately related to pathogenesis and therapy in heart failure. Highly valuable would be a long-term culture system that emulates the structural and functional changes that accompany disease and development, while concurrently permitting ready access to underlying molecular events. Accordingly, we here produce functional monolayers of adult guinea-pig ventricular myocytes (aGPVMs) that can be maintained in long-term culture for several weeks. At baseline, these monolayers exhibit considerable myofibrillar organization and a significant contribution of sarcoplasmic reticular (SR) Ca(2+) release to global Ca(2+) transients. In terms of electrical signaling, these monolayers support propagated electrical activity and manifest monophasic restitution of action-potential duration and conduction velocity. Intriguingly, β-adrenergic stimulation increases chronotropy but not inotropy, indicating selective maintenance of β-adrenergic signaling. It is interesting that this overall phenotypic profile is not fixed, but can be readily enhanced by chronic electrical stimulation of cultures. This simple environmental cue significantly enhances myofibrillar organization as well as β-adrenergic sensitivity. In particular, the chronotropic response increases, and an inotropic effect now emerges, mimicking a reversal of the progression seen in heart failure. Thus, these aGPVM monolayer cultures offer a valuable platform for clarifying long elusive features of β-adrenergic signaling and its plasticity.
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Affiliation(s)
- Rosy Joshi-Mukherjee
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Adams PJ, Dick IE, Johny MB, Yang PS, Bazazzi H, Yue DT. Novel Modulatory Action of Calmodulin Complexation with L-Type Channels. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1988] [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: 11/15/2022] Open
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Adams PJ, Dick IE, Johny MB, Bazzazi H, Yang PS, Yue DT. The Distal Carboxy Tail (DCT) of CaV1.4 Modulates More than Ca2+/CaM-Dependent Inactivation (CDI). Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.2366] [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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Dick IE, Park SA, Yue DT. Distinctive Inactivation Profiles of CaV1.2 Channels Encoding Different Timothy Syndrome Mutations in Various Alternative Splicing Backgrounds. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.842] [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: 11/26/2022] Open
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Tadross MR, Dick IE, Yue DT. Mechanism of local and global Ca2+ sensing by calmodulin in complex with a Ca2+ channel. Cell 2008; 133:1228-40. [PMID: 18585356 DOI: 10.1016/j.cell.2008.05.025] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 02/22/2008] [Accepted: 05/16/2008] [Indexed: 12/29/2022]
Abstract
Calmodulin (CaM) in complex with Ca(2+) channels constitutes a prototype for Ca(2+) sensors that are intimately colocalized with Ca(2+) sources. The C-lobe of CaM senses local, large Ca(2+) oscillations due to Ca(2+) influx from the host channel, and the N-lobe senses global, albeit diminutive Ca(2+) changes arising from distant sources. Though biologically essential, the mechanism underlying global Ca(2+) sensing has remained unknown. Here, we advance a theory of how global selectivity arises, and we experimentally validate this proposal with methodologies enabling millisecond control of Ca(2+) oscillations seen by the CaM/channel complex. We find that global selectivity arises from rapid Ca(2+) release from CaM combined with greater affinity of the channel for Ca(2+)-free versus Ca(2+)-bound CaM. The emergence of complex decoding properties from the juxtaposition of common elements, and the techniques developed herein, promise generalization to numerous molecules residing near Ca(2+) sources.
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Affiliation(s)
- Michael R Tadross
- Calcium Signals Laboratory, Departments of Biomedical Engineering and Neuroscience, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA
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Dick IE, Brochu RM, Purohit Y, Kaczorowski GJ, Martin WJ, Priest BT. Sodium channel blockade may contribute to the analgesic efficacy of antidepressants. J Pain 2006; 8:315-24. [PMID: 17175203 DOI: 10.1016/j.jpain.2006.10.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 09/11/2006] [Accepted: 10/08/2006] [Indexed: 11/16/2022]
Abstract
UNLABELLED Sodium channel blockers such as lidocaine, lamotrigine, and carbamazepine can be effective in the treatment of neuropathic pain. Though not approved for neuropathic pain indications, tricyclic antidepressants are often considered first-line treatment for conditions such as post-herpetic neuralgia and diabetic neuropathy. Several tricyclic antidepressants have been shown to block peripheral nerve sodium channels, which may contribute to their antihyperalgesic efficacy. In this study, we compared the sodium channel-blocking potency of a number of antidepressants, including tricyclic antidepressants and selective serotonin reuptake inhibitors. All compounds tested inhibited Na(V)1.7 in a state- and use-dependent manner, with affinities for the inactivated state ranging from 0.24 micromol/L for amitriptyline to 11.6 micromol/L for zimelidine. The tricyclic antidepressants were more potent blockers of Na(V)1.7. Moreover, IC(50)s for block of the inactivated state for amitriptyline, nortriptyline, imipramine, desipramine, and maprotiline were in the range of therapeutic plasma concentrations for both the treatment of depression as well as neuropathic pain. By contrast, fluoxetine, paroxetine, mianserine, and zimelidine had IC(50)s for Na(V)1.7 outside their therapeutic concentration ranges and generally were not efficacious against post-herpetic neuralgia or diabetic neuropathy. These results suggest that block of peripheral nerve sodium channels may contribute to the antihyperalgesic efficacy of certain antidepressants. PERSPECTIVE Tricyclic antidepressants are often considered first-line treatment for neuropathic pain. Some tricyclic antidepressants block sodium channels, which may contribute to their antihyperalgesic efficacy. In the current study, we compared the potency of peripheral sodium channel blockade for several tricyclic antidepressants and selective serotonin reuptake inhibitors with their therapeutic efficacy.
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Affiliation(s)
- Ivy E Dick
- Department of Ion Channels, Merck Research Laboratories, Rahway, New Jersey 07065-0900, USA
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Liu CJ, Priest BT, Bugianesi RM, Dulski PM, Felix JP, Dick IE, Brochu RM, Knaus HG, Middleton RE, Kaczorowski GJ, Slaughter RS, Garcia ML, Köhler MG. A high-capacity membrane potential FRET-based assay for NaV1.8 channels. Assay Drug Dev Technol 2006; 4:37-48. [PMID: 16506887 DOI: 10.1089/adt.2006.4.37] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Clinical treatment of neuropathic pain can be achieved with a number of different drugs, some of which interact with all members of the voltage-gated sodium channel (NaV1) family. However, block of central nervous system and cardiac NaV1 channels can cause dose-limiting side effects, preventing many patients from achieving adequate pain relief. Expression of the tetrodotoxin-resistant NaV1.8 subtype is restricted to small-diameter sensory neurons, and several lines of evidence indicate a role for NaV1.8 in pain processing. Given these features, NaV1.8 subtype-selective blockers are predicted to be efficacious in the treatment of neuropathic pain and to be associated with fewer adverse effects than currently available therapies. To facilitate the identification of NaV1.8-specific inhibitors, we stably expressed the human NaV1.8 channel together with the auxiliary human beta1 subunit (NaV beta1) in human embryonic kidney 293 cells. Heterologously expressed human NaV1.8/NaV beta1 channels display biophysical properties that are similar to those of tetrodotoxin-resistant channels present in mouse dorsal root ganglion neurons. A membrane potential, fluorescence resonance energy transfer-based functional assay on a fluorometric imaging plate reader (FLIPR-Tetra, Molecular Devices, Sunnyvale, CA) platform has been established. This highcapacity assay is sensitive to known state-dependent NaV1 modulators and can be used to identify novel and selective NaV1.8 inhibitors.
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Affiliation(s)
- Chou J Liu
- Department of Ion Channels, Merck Research Laboratories, Rahway, NJ 07065, USA
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Brochu RM, Dick IE, Tarpley JW, McGowan E, Gunner D, Herrington J, Shao PP, Ok D, Li C, Parsons WH, Stump GL, Regan CP, Lynch JJ, Lyons KA, McManus OB, Clark S, Ali Z, Kaczorowski GJ, Martin WJ, Priest BT. Block of peripheral nerve sodium channels selectively inhibits features of neuropathic pain in rats. Mol Pharmacol 2005; 69:823-32. [PMID: 16301337 DOI: 10.1124/mol.105.018127] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several sodium channel blockers are used clinically to treat neuropathic pain. However, many patients fail to achieve adequate pain relief from these highly brain-penetrant drugs because of dose-limiting central nervous system side effects. Here, we describe the functional properties of trans-N-{[2'-(aminosulfonyl)biphenyl-4-yl]methyl}-N-methyl-N'-[4-(trifluoromethoxy)benzyl]cyclopentane-1,2-dicarboxamide (CDA54), a peripherally acting sodium channel blocker. In whole-cell electrophysiological assays, CDA54 blocked the inactivated states of hNa(V)1.7 and hNa(V)1.8, two channels of the peripheral nervous system implicated in nociceptive transmission, with affinities of 0.25 and 0.18 microM, respectively. CDA54 displayed similar affinities for the tetrodotoxin-resistant Na+ current in small-diameter mouse dorsal root ganglion neurons. Peripheral nerve injury causes spontaneous electrical activity in normally silent sensory neurons. CDA54 inhibited these injury-induced spontaneous action potentials at concentrations 10-fold lower than those required to block normal A- and C-fiber conduction. Consistent with the selective inhibition of injury-induced firing, CDA54 (10 mg/kg p.o.) significantly reduced behavioral signs of neuropathic pain in two nerve injury models, whereas the same dose of CDA54 did not affect acute nociception or motor coordination. In anesthetized dogs, CDA54, at plasma concentrations of 6.7 microM, had no effect on cardiac electrophysiological parameters including conduction. Thus, the peripheral nerve sodium channel blocker CDA54 selectively inhibits sensory nerve signaling associated with neuropathic pain.
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Affiliation(s)
- Richard M Brochu
- Department of Ion Channels, Merck Research Laboratories, Rahway, NJ, USA
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Herrington J, Sanchez M, Wunderler D, Yan L, Bugianesi RM, Dick IE, Clark SA, Brochu RM, Priest BT, Kohler MG, McManus OB. Biophysical and pharmacological properties of the voltage-gated potassium current of human pancreatic beta-cells. J Physiol 2005; 567:159-75. [PMID: 15932888 PMCID: PMC1474166 DOI: 10.1113/jphysiol.2005.089375] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Voltage-gated potassium (Kv) currents of human pancreatic islet cells were studied by whole-cell patch clamp recording. On average, 75% of the cells tested were identified as beta-cells by single cell, post-recording RT-PCR for insulin mRNA. In most cells, the dominant Kv current was a delayed rectifier. The delayed rectifier activated at potentials above -20 mV and had a V(1/2) for activation of -5.3 mV. Onset of inactivation was slow for a major component (tau = 3.2 s at +20 mV) observed in all cells; a smaller component (tau = 0.30 s) with an amplitude of approximately 25% was seen in some cells. Recovery from inactivation had a tau of 2.5 s at -80 mV and steady-state inactivation had a V(1/2) of -39 mV. In 12% of cells (21/182) a low-threshold, transient Kv current (A-current) was present. The A-current activated at membrane potentials above -40 mV, inactivated with a time constant of 18.5 ms at -20 mV, and had a V(1/2) for steady-state inactivation of -52 mV. TEA inhibited total Kv current with an IC50 = 0.54 mm and PAC, a disubstituted cyclohexyl Kv channel inhibitor, inhibited with an IC50 = 0.57 microm. The total Kv current was insensitive to margatoxin (100 nm), agitoxin-2 (50 nm), kaliotoxin (50 nm) and ShK (50 nm). Hanatoxin (100 nm) inhibited total Kv current by 65% at +20 mV. Taken together, these data provide evidence of at least two distinct types of Kv channels in human pancreatic beta-cells and suggest that more than one type of Kv channel may be involved in the regulation of glucose-dependent insulin secretion.
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Affiliation(s)
- James Herrington
- Department of Ion Channels, Merck Research Laboratories, PO Box 2000, RY-80N-C31, Rahway, NJ 07065, USA.
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Liang J, Brochu RM, Cohen CJ, Dick IE, Felix JP, Fisher MH, Garcia ML, Kaczorowski GJ, Lyons KA, Meinke PT, Priest BT, Schmalhofer WA, Smith MM, Tarpley JW, Williams BS, Martin WJ, Parsons WH. Discovery of potent and use-dependent sodium channel blockers for treatment of chronic pain. Bioorg Med Chem Lett 2005; 15:2943-7. [PMID: 15878274 DOI: 10.1016/j.bmcl.2005.02.093] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 02/18/2005] [Accepted: 02/22/2005] [Indexed: 11/18/2022]
Abstract
A new series of voltage-gated sodium channel blockers with potential for treatment of chronic pain is reported. Systematic structure-activity relationship studies, starting with compound 1, led to identification of potent analogs that displayed use-dependent block of sodium channels, were efficacious in pain models in vivo, and most importantly, were devoid of activity against the cardiac potassium channel hERG.
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Affiliation(s)
- Jun Liang
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065, USA.
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Felix JP, Williams BS, Priest BT, Brochu RM, Dick IE, Warren VA, Yan L, Slaughter RS, Kaczorowski GJ, Smith MM, Garcia ML. Functional assay of voltage-gated sodium channels using membrane potential-sensitive dyes. Assay Drug Dev Technol 2005; 2:260-8. [PMID: 15285907 DOI: 10.1089/1540658041410696] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The discovery of novel therapeutic agents that act on voltage-gated sodium channels requires the establishment of high-capacity screening assays that can reliably measure the activity of these proteins. Fluorescence resonance energy transfer (FRET) technology using membrane potential-sensitive dyes has been shown to provide a readout of voltage-gated sodium channel activity in stably transfected cell lines. Due to the inherent rapid inactivation of sodium channels, these assays require the presence of a channel activator to prolong channel opening. Because sodium channel activators and test compounds may share related binding sites on the protein, the assay protocol is critical for the proper identification of channel inhibitors. In this study, high throughput, functional assays for the voltage-gated sodium channels, hNa(V)1.5 and hNa(V)1.7, are described. In these assays, channels stably expressed in HEK cells are preincubated with test compound in physiological medium and then exposed to a sodium channel activator that slows channel inactivation. Sodium ion movement through open channels causes membrane depolarization that can be measured with a FRET dye membrane potential-sensing system, providing a large and reproducible signal. Unlike previous assays, the signal obtained in the agonist initiation assay is sensitive to all sodium channel modulators that were tested and can be used in high throughput mode, as well as in support of Medicinal Chemistry efforts for lead optimization.
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Affiliation(s)
- John P Felix
- Department of Ion Channels, Merck Research Laboratories, Rahway, NJ 07065, USA
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Priest BT, Garcia ML, Middleton RE, Brochu RM, Clark S, Dai G, Dick IE, Felix JP, Liu CJ, Reiseter BS, Schmalhofer WA, Shao PP, Tang YS, Chou MZ, Kohler MG, Smith MM, Warren VA, Williams BS, Cohen CJ, Martin WJ, Meinke PT, Parsons WH, Wafford KA, Kaczorowski GJ. A disubstituted succinamide is a potent sodium channel blocker with efficacy in a rat pain model. Biochemistry 2004; 43:9866-76. [PMID: 15274641 DOI: 10.1021/bi0493259] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sodium channel blockers are used clinically to treat a number of neuropathic pain conditions, but more potent and selective agents should improve on the therapeutic index of currently used drugs. In a high-throughput functional assay, a novel sodium channel (Na(V)) blocker, N-[[2'-(aminosulfonyl)biphenyl-4-yl]methyl]-N'-(2,2'-bithien-5-ylmethyl)succinamide (BPBTS), was discovered. BPBTS is 2 orders of magnitude more potent than anticonvulsant and antiarrhythmic sodium channel blockers currently used to treat neuropathic pain. Resembling block by these agents, block of Na(V)1.2, Na(V)1.5, and Na(V)1.7 by BPBTS was found to be voltage- and use-dependent. BPBTS appeared to bind preferentially to open and inactivated states and caused a dose-dependent hyperpolarizing shift in the steady-state availability curves for all sodium channel subtypes tested. The affinity of BPBTS for the resting and inactivated states of Na(V)1.2 was 1.2 and 0.14 microM, respectively. BPBTS blocked Na(V)1.7 and Na(V)1.2 with similar potency, whereas block of Na(V)1.5 was slightly more potent. The slow tetrodotoxin-resistant Na(+) current in small-diameter DRG neurons was also potently blocked by BPBTS. [(3)H]BPBTS bound with high affinity to a single class of sites present in rat brain synaptosomal membranes (K(d) = 6.1 nM), and in membranes derived from HEK cells stably expressing Na(V)1.5 (K(d) = 0.9 nM). BPBTS dose-dependently attenuated nociceptive behavior in the formalin test, a rat model of tonic pain. On the basis of these findings, BPBTS represents a structurally novel and potent sodium channel blocker that may be used as a template for the development of analgesic agents.
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Affiliation(s)
- Birgit T Priest
- Department of Ion Channels, Merck Research Laboratories, Rahway, New Jersey 07065, USA
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