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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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2
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Kang PW, Woodbury L, Angsutararux P, Sambare N, Shi J, Marras M, Abella C, Bedi A, Zinn D, Cui J, Silva JR. Arrhythmia-associated calmodulin variants interact with KCNQ1 to confer aberrant membrane trafficking and function. PNAS NEXUS 2023; 2:pgad335. [PMID: 37965565 PMCID: PMC10642763 DOI: 10.1093/pnasnexus/pgad335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 10/04/2023] [Indexed: 11/16/2023]
Abstract
Missense variants in calmodulin (CaM) predispose patients to arrhythmias associated with high mortality rates ("calmodulinopathy"). As CaM regulates many key cardiac ion channels, an understanding of disease mechanism associated with CaM variant arrhythmias requires elucidating individual CaM variant effects on distinct channels. One key CaM regulatory target is the KCNQ1 (KV7.1) voltage-gated potassium channel that carries the IKs current. Yet, relatively little is known as to how CaM variants interact with KCNQ1 or affect its function. Here, we take a multipronged approach employing a live-cell fluorescence resonance energy transfer binding assay, fluorescence trafficking assay, and functional electrophysiology to characterize >10 arrhythmia-associated CaM variants for effect on KCNQ1 CaM binding, membrane trafficking, and channel function. We identify one variant (G114W) that exhibits severely weakened binding to KCNQ1 but find that most other CaM variants interact with similar binding affinity to KCNQ1 when compared with CaM wild-type over physiological Ca2+ ranges. We further identify several CaM variants that affect KCNQ1 and IKs membrane trafficking and/or baseline current activation kinetics, thereby delineating KCNQ1 dysfunction in calmodulinopathy. Lastly, we identify CaM variants with no effect on KCNQ1 function. This study provides extensive functional data that reveal how CaM variants contribute to creating a proarrhythmic substrate by causing abnormal KCNQ1 membrane trafficking and current conduction. We find that CaM variant regulation of KCNQ1 is not uniform with effects varying from benign to significant loss of function, suggesting how CaM variants predispose patients to arrhythmia via the dysregulation of multiple cardiac ion channels. Classification: Biological, Health, and Medical Sciences, Physiology.
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Affiliation(s)
- Po wei Kang
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Lucy Woodbury
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Paweorn Angsutararux
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Namit Sambare
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Martina Marras
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Carlota Abella
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Anish Bedi
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - DeShawn Zinn
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Washington University in St.Louis, St. Louis, MO 63130, USA
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3
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Del Rivero Morfin PJ, Chavez DS, Jayaraman S, Yang L, Kochiss AL, Colecraft HM, Liu XS, Marx SO, Rajadhyaksha AM, Ben-Johny M. A Genetically Encoded Actuator Selectively Boosts L-type Calcium Channels in Diverse Physiological Settings. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.558856. [PMID: 37790372 PMCID: PMC10542531 DOI: 10.1101/2023.09.22.558856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
L-type Ca 2+ channels (Ca V 1.2/1.3) convey influx of calcium ions (Ca 2+ ) that orchestrate a bevy of biological responses including muscle contraction and gene transcription. Deficits in Ca V 1 function play a vital role in cardiac and neurodevelopmental disorders. Yet conventional pharmacological approaches to upregulate Ca V 1 are limited, as excessive Ca 2+ influx leads to cytotoxicity. Here, we develop a genetically encoded enhancer of Ca V 1.2/1.3 channels (GeeC) to manipulate Ca 2+ entry in distinct physiological settings. Specifically, we functionalized a nanobody that targets the Ca V macromolecular complex by attaching a minimal effector domain from a Ca V enhancer-leucine rich repeat containing protein 10 (Lrrc10). In cardiomyocytes, GeeC evoked a 3-fold increase in L-type current amplitude. In neurons, GeeC augmented excitation-transcription (E-T) coupling. In all, GeeC represents a powerful strategy to boost Ca V 1.2/1.3 function in distinct physiological settings and, in so doing, lays the groundwork to illuminate new insights on neuronal and cardiac physiology and disease.
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4
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Kameyama M, Minobe E, Shao D, Xu J, Gao Q, Hao L. Regulation of Cardiac Cav1.2 Channels by Calmodulin. Int J Mol Sci 2023; 24:ijms24076409. [PMID: 37047381 PMCID: PMC10094977 DOI: 10.3390/ijms24076409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/19/2023] [Accepted: 03/23/2023] [Indexed: 03/31/2023] Open
Abstract
Cav1.2 Ca2+ channels, a type of voltage-gated L-type Ca2+ channel, are ubiquitously expressed, and the predominant Ca2+ channel type, in working cardiac myocytes. Cav1.2 channels are regulated by the direct interactions with calmodulin (CaM), a Ca2+-binding protein that causes Ca2+-dependent facilitation (CDF) and inactivation (CDI). Ca2+-free CaM (apoCaM) also contributes to the regulation of Cav1.2 channels. Furthermore, CaM indirectly affects channel activity by activating CaM-dependent enzymes, such as CaM-dependent protein kinase II and calcineurin (a CaM-dependent protein phosphatase). In this article, we review the recent progress in identifying the role of apoCaM in the channel ‘rundown’ phenomena and related repriming of channels, and CDF, as well as the role of Ca2+/CaM in CDI. In addition, the role of CaM in channel clustering is reviewed.
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Affiliation(s)
- Masaki Kameyama
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
- Correspondence:
| | - Etsuko Minobe
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Dongxue Shao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Jianjun Xu
- Department of Physiology, Graduate School of Medical & Dental Sciences, Kagoshima University, Sakura-ga-oka, Kagoshima 890-8544, Japan
| | - Qinghua Gao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang 110012, China (L.H.)
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Zuidscherwoude M, van Goor MK, Roig SR, Thijssen N, van Erp M, Fransen J, van der Wijst J, Hoenderop JG. Functional basis for calmodulation of the TRPV5 calcium channel. J Physiol 2023; 601:859-878. [PMID: 36566502 DOI: 10.1113/jp282952] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 12/06/2022] [Indexed: 12/26/2022] Open
Abstract
Within the transient receptor potential (TRP) superfamily of ion channels, TRPV5 is a highly Ca2+ -selective channel important for active reabsorption of Ca2+ in the kidney. Its channel activity is controlled by a negative feedback mechanism involving calmodulin (CaM) binding. Combining advanced microscopy techniques and biochemical assays, this study characterized the dynamic lobe-specific CaM regulation. We demonstrate for the first time that functional (full-length) TRPV5 interacts with CaM in the absence of Ca2+ , and this interaction is intensified at increasing Ca2+ concentrations sensed by the CaM C-lobe that achieves channel pore blocking. Channel inactivation occurs without requiring CaM N-lobe calcification. Moreover, we show a Ca2+ -dependent binding stoichiometry at the single channel level. In conclusion, our study proposes a new model for CaM-dependent regulation - calmodulation - of this uniquely Ca2+ -selective TRP channel TRPV5 that involves apoCaM interaction and lobe-specific actions, which may be of significant physiological relevance given its role as gatekeeper of Ca2+ transport in the kidney. KEY POINTS: The renal Ca2+ channel TRPV5 is an important player in maintenance of the body's Ca2+ homeostasis. Activity of TRPV5 is controlled by a negative feedback loop that involves calmodulin (CaM), a protein with two Ca2+ -binding lobes. We investigated the dynamics of the interaction between TRPV5 and CaM with advanced fluorescence microscopy techniques. Our data support a new model for CaM-dependent regulation of TRPV5 channel activity with CaM lobe-specific actions and demonstrates Ca2+ -dependent binding stoichiometries. This study improves our understanding of the mechanism underlying fast channel inactivation, which is physiologically relevant given the gatekeeper function of TRPV5 in Ca2+ reabsorption in the kidney.
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Affiliation(s)
- Malou Zuidscherwoude
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mark K van Goor
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sara R Roig
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Imaging Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Niky Thijssen
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Merijn van Erp
- Radboudumc Technology Centre Microscopy, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack Fransen
- Radboudumc Technology Centre Microscopy, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Kang PW, Woodbury L, Angsutararux P, Sambare N, Shi J, Marras M, Abella C, Bedi A, Zinn D, Cui J, Silva JR. Arrhythmia-associated Calmodulin Variants Interact with KCNQ1 to Confer Aberrant Membrane Trafficking and Function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.28.526031. [PMID: 36747728 PMCID: PMC9900995 DOI: 10.1101/2023.01.28.526031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Rationale Missense variants in calmodulin (CaM) predispose patients to arrhythmias associated with high mortality rates. As CaM regulates several key cardiac ion channels, a mechanistic understanding of CaM variant-associated arrhythmias requires elucidating individual CaM variant effect on distinct channels. One key CaM regulatory target is the KCNQ1 (K V 7.1) voltage-gated potassium channel that underlie the I Ks current. Yet, relatively little is known as to how CaM variants interact with KCNQ1 or affect its function. Objective To observe how arrhythmia-associated CaM variants affect binding to KCNQ1, channel membrane trafficking, and KCNQ1 function. Methods and Results We combine a live-cell FRET binding assay, fluorescence trafficking assay, and functional electrophysiology to characterize >10 arrhythmia-associated CaM variants effect on KCNQ1. We identify one variant (G114W) that exhibits severely weakened binding to KCNQ1 but find that most other CaM variants interact with similar binding affinity to KCNQ1 when compared to CaM wild-type over physiological Ca 2+ ranges. We further identify several CaM variants that affect KCNQ1 and I Ks membrane trafficking and/or baseline current activation kinetics, thereby contextualizing KCNQ1 dysfunction in calmodulinopathy. Lastly, we delineate CaM variants with no effect on KCNQ1 function. Conclusions This study provides comprehensive functional data that reveal how CaM variants contribute to creating a pro-arrhythmic substrate by causing abnormal KCNQ1 membrane trafficking and current conduction. We find that CaM variant regulation of KCNQ1 is not uniform with effects varying from benign to significant loss of function. This study provides a new approach to collecting details of CaM binding that are key for understanding how CaM variants predispose patients to arrhythmia via the dysregulation of multiple cardiac ion channels.
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Li M, Luo H, Huang Z, Qi J, Yu B. Screening and Identification of Anti-Inflammatory Compounds from Erdong Gao via Multiple-Target-Cell Extraction Coupled with HPLC-Q-TOF-MS/MS and Their Structure-Activity Relationship. MOLECULES (BASEL, SWITZERLAND) 2022; 28:molecules28010295. [PMID: 36615494 PMCID: PMC9822190 DOI: 10.3390/molecules28010295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/18/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023]
Abstract
Erdong Gao (EDG), consisting equally of roots of Asparagi Radix and Ophiopogonis Radix, is a well-known traditional Chinese formulation that has been used to treat cough and throat pain for centuries. However, the bioactive components in EDG remain to be elucidated. In this study, a rapid and effective method involving live cell bio-specific extraction and HPLC-Q-TOF-MS/MS was established to rapidly screen and identify the anti-inflammatory compounds of an EDG extract. One hundred and twenty-four components were identified in EDG extract using HPLC-Q-TOF-MS/MS analysis. After co-incubation with 16HBE, HPAEpiCs and HUVECs, which have been validated as the key target cells for pulmonary diseases, sixteen components were demonstrated to exhibit an affinity for binding to them. Furthermore, fifteen components were subsequently verified to exert anti-inflammatory effects on lipopolysaccharide (LPS)-induced 16HBE, HPAEpiCs and HUVECs via inhibiting the release of TNF-α and IL-6, indicating that nine steroidal saponins may possess potential for the treatment of lung-related diseases. Taken together, our study provides evidence that live cell biospecific extraction combined with the HPLC-Q-TOF-MS/MS technique was an efficient method for rapid screening potential bioactive components in traditional Chinese medicines and the structure activity relationship of steroidal saponins in EDG was summarized for the first time.
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Affiliation(s)
| | | | | | - Jin Qi
- Correspondence: (J.Q.); (B.Y.)
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8
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Morgenstern TJ, Nirwan N, Hernández-Ochoa EO, Bibollet H, Choudhury P, Laloudakis YD, Ben Johny M, Bannister RA, Schneider MF, Minor DL, Colecraft HM. Selective posttranslational inhibition of Ca Vβ 1-associated voltage-dependent calcium channels with a functionalized nanobody. Nat Commun 2022; 13:7556. [PMID: 36494348 PMCID: PMC9734117 DOI: 10.1038/s41467-022-35025-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
Ca2+ influx through high-voltage-activated calcium channels (HVACCs) controls diverse cellular functions. A critical feature enabling a singular signal, Ca2+ influx, to mediate disparate functions is diversity of HVACC pore-forming α1 and auxiliary CaVβ1-CaVβ4 subunits. Selective CaVα1 blockers have enabled deciphering their unique physiological roles. By contrast, the capacity to post-translationally inhibit HVACCs based on CaVβ isoform is non-existent. Conventional gene knockout/shRNA approaches do not adequately address this deficit owing to subunit reshuffling and partially overlapping functions of CaVβ isoforms. Here, we identify a nanobody (nb.E8) that selectively binds CaVβ1 SH3 domain and inhibits CaVβ1-associated HVACCs by reducing channel surface density, decreasing open probability, and speeding inactivation. Functionalizing nb.E8 with Nedd4L HECT domain yielded Chisel-1 which eliminated current through CaVβ1-reconstituted CaV1/CaV2 and native CaV1.1 channels in skeletal muscle, strongly suppressed depolarization-evoked Ca2+ influx and excitation-transcription coupling in hippocampal neurons, but was inert against CaVβ2-associated CaV1.2 in cardiomyocytes. The results introduce an original method for probing distinctive functions of ion channel auxiliary subunit isoforms, reveal additional dimensions of CaVβ1 signaling in neurons, and describe a genetically-encoded HVACC inhibitor with unique properties.
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Affiliation(s)
- Travis J. Morgenstern
- grid.239585.00000 0001 2285 2675Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY USA
| | - Neha Nirwan
- grid.266102.10000 0001 2297 6811Cardiovascular Research Institute, University of California, San Francisco, CA USA
| | - Erick O. Hernández-Ochoa
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Hugo Bibollet
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Papiya Choudhury
- grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
| | - Yianni D. Laloudakis
- grid.239585.00000 0001 2285 2675Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY USA
| | - Manu Ben Johny
- grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
| | - Roger A. Bannister
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA ,grid.411024.20000 0001 2175 4264Department of Pathology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Martin F. Schneider
- grid.411024.20000 0001 2175 4264Department of Biochemistry and Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Daniel L. Minor
- grid.266102.10000 0001 2297 6811Cardiovascular Research Institute, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Department of Biochemistry and Biophysics, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA USA ,grid.266102.10000 0001 2297 6811Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA USA ,grid.184769.50000 0001 2231 4551Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Henry M. Colecraft
- grid.239585.00000 0001 2285 2675Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY USA ,grid.239585.00000 0001 2285 2675Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY USA
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Bartels P, Salveson I, Coleman AM, Anderson DE, Jeng G, Estrada-Tobar ZM, Man KNM, Yu Q, Kuzmenkina E, Nieves-Cintron M, Navedo MF, Horne MC, Hell JW, Ames JB. Half-calcified calmodulin promotes basal activity and inactivation of the L-type calcium channel Ca V1.2. J Biol Chem 2022; 298:102701. [PMID: 36395884 PMCID: PMC9764201 DOI: 10.1016/j.jbc.2022.102701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
The L-type Ca2+ channel CaV1.2 controls gene expression, cardiac contraction, and neuronal activity. Calmodulin (CaM) governs CaV1.2 open probability (Po) and Ca2+-dependent inactivation (CDI) but the mechanisms remain unclear. Here, we present electrophysiological data that identify a half Ca2+-saturated CaM species (Ca2/CaM) with Ca2+ bound solely at the third and fourth EF-hands (EF3 and EF4) under resting Ca2+ concentrations (50-100 nM) that constitutively preassociates with CaV1.2 to promote Po and CDI. We also present an NMR structure of a complex between the CaV1.2 IQ motif (residues 1644-1665) and Ca2/CaM12', a calmodulin mutant in which Ca2+ binding to EF1 and EF2 is completely disabled. We found that the CaM12' N-lobe does not interact with the IQ motif. The CaM12' C-lobe bound two Ca2+ ions and formed close contacts with IQ residues I1654 and Y1657. I1654A and Y1657D mutations impaired CaM binding, CDI, and Po, as did disabling Ca2+ binding to EF3 and EF4 in the CaM34 mutant when compared to WT CaM. Accordingly, a previously unappreciated Ca2/CaM species promotes CaV1.2 Po and CDI, identifying Ca2/CaM as an important mediator of Ca signaling.
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Affiliation(s)
- Peter Bartels
- Department of Pharmacology, University of California, Davis, California, USA
| | - Ian Salveson
- Department of Chemistry, University of California, Davis, California, USA
| | - Andrea M Coleman
- Department of Pharmacology, University of California, Davis, California, USA; Department of Chemistry, University of California, Davis, California, USA
| | - David E Anderson
- Department of Chemistry, University of California, Davis, California, USA
| | - Grace Jeng
- Department of Pharmacology, University of California, Davis, California, USA
| | | | - Kwun Nok Mimi Man
- Department of Pharmacology, University of California, Davis, California, USA
| | - Qinhong Yu
- Department of Chemistry, University of California, Davis, California, USA
| | - Elza Kuzmenkina
- Center for Pharmacology, University of Cologne, Cologne, Germany
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, California, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, California, USA.
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, California, USA.
| | - James B Ames
- Department of Chemistry, University of California, Davis, California, USA.
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10
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Yadav DK, Anderson DE, Hell JW, Ames JB. Calmodulin promotes a Ca 2+ -dependent conformational change in the C-terminal regulatory domain of Ca V 1.2. FEBS Lett 2022; 596:2974-2985. [PMID: 36310389 PMCID: PMC9719739 DOI: 10.1002/1873-3468.14529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/07/2022] [Accepted: 10/10/2022] [Indexed: 11/10/2023]
Abstract
Calmodulin (CaM) binds to the membrane-proximal cytosolic C-terminal domain of CaV 1.2 (residues 1520-1669, CT(1520-1669)) and causes Ca2+ -induced conformational changes that promote Ca2+ -dependent channel inactivation (CDI). We report biophysical studies that probe the structural interaction between CT(1520-1669) and CaM. The recombinantly expressed CT(1520-1669) is insoluble, but can be solubilized in the presence of Ca2+ -saturated CaM (Ca4 /CaM), but not in the presence of Ca2+ -free CaM (apoCaM). We show that half-calcified CaM (Ca2 /CaM12 ) forms a complex with CT(1520-1669) that is less soluble than CT(1520-1669) bound to Ca4 /CaM. The NMR spectrum of CT(1520-1669) reveals spectral differences caused by the binding of Ca2 /CaM12 versus Ca4 /CaM, suggesting that the binding of Ca2+ to the CaM N-lobe may induce a conformational change in CT(1520-1669).
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Affiliation(s)
| | - David E. Anderson
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Johannes W. Hell
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - James B. Ames
- Department of Chemistry, University of California, Davis, CA 95616, USA
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11
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Zhao J, Segura E, Marsolais M, Parent L. A CACNA1C variant associated with cardiac arrhythmias provides mechanistic insights in the calmodulation of L-type Ca 2+ channels. J Biol Chem 2022; 298:102632. [PMID: 36273583 PMCID: PMC9691931 DOI: 10.1016/j.jbc.2022.102632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 10/12/2022] [Accepted: 10/15/2022] [Indexed: 11/07/2022] Open
Abstract
We recently reported the identification of a de novo single nucleotide variant in exon 9 of CACNA1C associated with prolonged repolarization interval. Recombinant expression of the glycine to arginine variant at position 419 produced a gain in the function of the L-type CaV1.2 channel with increased peak current density and activation gating but without significant decrease in the inactivation kinetics. We herein reveal that these properties are replicated by overexpressing calmodulin (CaM) with CaV1.2 WT and are reversed by exposure to the CaM antagonist W-13. Phosphomimetic (T79D or S81D), but not phosphoresistant (T79A or S81A), CaM surrogates reproduced the impact of CaM WT on the function of CaV1.2 WT. The increased channel activity of CaV1.2 WT following overexpression of CaM was found to arise in part from enhanced cell surface expression. In contrast, the properties of the variant remained unaffected by any of these treatments. CaV1.2 substituted with the α-helix breaking proline residue were more reluctant to open than CaV1.2 WT but were upregulated by phosphomimetic CaM surrogates. Our results indicate that (1) CaM and its phosphomimetic analogs promote a gain in the function of CaV1.2 and (2) the structural properties of the first intracellular linker of CaV1.2 contribute to its CaM-induced modulation. We conclude that the CACNA1C clinical variant mimics the increased activity associated with the upregulation of CaV1.2 by Ca2+-CaM, thus maintaining a majority of channels in a constitutively active mode that could ultimately promote ventricular arrhythmias.
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Affiliation(s)
- Juan Zhao
- Centre de recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Emilie Segura
- Centre de recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada,Département de Pharmacologie et Physiologie, Faculté de Médecine, Montréal, Québec, Canada
| | - Mireille Marsolais
- Centre de recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada,Département de Pharmacologie et Physiologie, Faculté de Médecine, Montréal, Québec, Canada
| | - Lucie Parent
- Centre de recherche de l’Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada,Département de Pharmacologie et Physiologie, Faculté de Médecine, Montréal, Québec, Canada,For correspondence: Lucie Parent
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12
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Salveson I, Ames JB. Chemical shift assignments of the C-terminal domain of CaBP1 bound to the IQ-motif of voltage-gated Ca 2+ channel (Ca V1.2). BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:385-390. [PMID: 36064846 PMCID: PMC9510106 DOI: 10.1007/s12104-022-10108-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
The neuronal L-type voltage-gated Ca2+ channel (CaV1.2) interacts with Ca2+ binding protein 1 (CaBP1), that promotes Ca2+-induced channel activity. The binding of CaBP1 to the IQ-motif in CaV1.2 (residues 1644-1665) blocks the binding of calmodulin and prevents Ca2+-dependent inactivation of CaV1.2. This Ca2+-induced binding of CaBP1 to CaV1.2 is important for modulating neuronal synaptic plasticity, which may serve a role in learning and memory. Here we report NMR assignments of the C-terminal domain of CaBP1 (residues 99-167, called CaBP1C) that contains two Ca2+ bound at the third and fourth EF-hands (EF3 and EF4) and is bound to the CaV1.2 IQ-motif from CaV1.2 (BMRB accession no. 51518).
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Affiliation(s)
- Ian Salveson
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA.
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13
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Bej A, Ames JB. Chemical shift assignments of calmodulin under standard conditions at neutral pH. BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:213-218. [PMID: 35460468 PMCID: PMC9510097 DOI: 10.1007/s12104-022-10082-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/30/2022] [Indexed: 05/10/2023]
Abstract
The Ca2+ sensor protein, calmodulin (CaM) is ubiquitously expressed in all cells where it binds to hundreds of different target proteins, including dozens of enzymes, receptors, ion channels and numerous Ca2+ transporters. The only published NMR chemical shift assignments for Ca2+-bound CaM (in the absence of a target) have been determined under acidic conditions: at pH 6.5/310 K (BMRB 6541) and pH 6.3/320 K (BMRB 547). However, some CaM/target complexes are not soluble under these conditions. Also, amide chemical shifts are very sensitive to pH and temperature, which can cause large baseline errors when using the existing chemical shift assignments of free CaM to calculate chemical shift perturbations caused by target binding at neutral pH and physiological temperature. We report complete NMR chemical shift assignments of Ca2+-saturated CaM under a set of standard conditions at neutral pH and 308 K that will enable more accurate chemical shift comparison between free CaM and CaM/target complexes (BMRB 51289).
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Affiliation(s)
- Aritra Bej
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, CA, 95616, USA.
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14
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Bej A, Ames JB. NMR Structures of Calmodulin Bound to Two Separate Regulatory Sites in the Retinal Cyclic Nucleotide-Gated Channel. Biochemistry 2022; 61:1955-1965. [PMID: 36070238 PMCID: PMC9810080 DOI: 10.1021/acs.biochem.2c00378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Retinal cyclic nucleotide-gated (CNG) channels (composed of three CNGA1 and one CNGB1 subunits) exhibit a Ca2+-induced reduction in channel open probability mediated by calmodulin (CaM). Defects in the Ca2+-dependent regulation of CNG channels may be linked to autosomal recessive retinitis pigmentosa and other inherited forms of blindness. Here, we report the NMR structure and binding analysis of CaM bound to two separate sites within CNGB1 (CaM1: residues 565-589 and CaM2: residues 1120-1147). Our binding studies reveal that CaM1 binds to the Ca2+-bound CaM N-lobe with at least fivefold higher affinity than it binds to the CaM C-lobe. By contrast, the CaM2 site binds to the Ca2+-bound CaM C-lobe with higher affinity than it binds to the N-lobe. CaM1 and CaM2 both exhibited very weak binding to Ca2+-free CaM. We present separate NMR structures of Ca2+-saturated CaM bound to CaM1 and CaM2 that define key intermolecular contacts: CaM1 residue F575 interacts with the CaM N-lobe while CaM2 residues L1129, L1132, and L1136 each make close contact with the CaM C-lobe. The CNGB1 mutation F575E abolishes CaM1 binding to the CaM N-lobe while L1132E and L1136E each abolish CaM2 binding to the CaM C-lobe. Thus, a single CaM can bind to both sites in CNGB1 in which the CaM N-lobe binds to CaM1 and the CaM C-lobe binds to CaM2. We propose a Ca2+-dependent conformational switch in the CNG channel caused by CaM binding, which may serve to attenuate cGMP binding to CNG channels at high cytosolic Ca2+ levels in dark-adapted photoreceptors.
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15
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Loss of Ca V1.3 RNA editing enhances mouse hippocampal plasticity, learning, and memory. Proc Natl Acad Sci U S A 2022; 119:e2203883119. [PMID: 35914168 PMCID: PMC9371748 DOI: 10.1073/pnas.2203883119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
L-type CaV1.3 calcium channels are expressed on the dendrites and soma of neurons, and there is a paucity of information about its role in hippocampal plasticity. Here, by genetic targeting to ablate CaV1.3 RNA editing, we demonstrate that unedited CaV1.3ΔECS mice exhibited improved learning and enhanced long-term memory, supporting a functional role of RNA editing in behavior. Significantly, the editing paradox that functional recoding of CaV1.3 RNA editing sites slows Ca2+-dependent inactivation to increase Ca2+ influx but reduces channel open probability to decrease Ca2+ influx was resolved. Mechanistically, using hippocampal slice recordings, we provide evidence that unedited CaV1.3 channels permitted larger Ca2+ influx into the hippocampal pyramidal neurons to bolster neuronal excitability, synaptic transmission, late long-term potentiation, and increased dendritic arborization. Of note, RNA editing of the CaV1.3 IQ-domain was found to be evolutionarily conserved in mammals, which lends support to the importance of the functional recoding of the CaV1.3 channel in brain function.
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16
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Zhai J, Koh JH, Soong TW. RNA editing of ion channels and receptors in physiology and neurological disorders. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac010. [PMID: 38596706 PMCID: PMC11003377 DOI: 10.1093/oons/kvac010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/14/2022] [Accepted: 05/15/2022] [Indexed: 04/11/2024]
Abstract
Adenosine-to-inosine (A-to-I) RNA editing is a post-transcriptional modification that diversifies protein functions by recoding RNA or alters protein quantity by regulating mRNA level. A-to-I editing is catalyzed by adenosine deaminases that act on RNA. Millions of editing sites have been reported, but they are mostly found in non-coding sequences. However, there are also several recoding editing sites in transcripts coding for ion channels or transporters that have been shown to play important roles in physiology and changes in editing level are associated with neurological diseases. These editing sites are not only found to be evolutionary conserved across species, but they are also dynamically regulated spatially, developmentally and by environmental factors. In this review, we discuss the current knowledge of A-to-I RNA editing of ion channels and receptors in the context of their roles in physiology and pathological disease. We also discuss the regulation of editing events and site-directed RNA editing approaches for functional study that offer a therapeutic pathway for clinical applications.
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Affiliation(s)
- Jing Zhai
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
| | - Joanne Huifen Koh
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
| | - Tuck Wah Soong
- Department of Physiology, National University of Singapore, Singapore 117593, Singapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore,
Singapore 117456, Singapore
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17
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Yang Y, Yu Z, Geng J, Liu M, Liu N, Li P, Hong W, Yue S, Jiang H, Ge H, Qian F, Xiong W, Wang P, Song S, Li X, Fan Y, Liu X. Cytosolic peptides encoding Ca V1 C-termini downregulate the calcium channel activity-neuritogenesis coupling. Commun Biol 2022; 5:484. [PMID: 35589958 PMCID: PMC9120191 DOI: 10.1038/s42003-022-03438-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 05/03/2022] [Indexed: 12/31/2022] Open
Abstract
L-type Ca2+ (CaV1) channels transduce channel activities into nuclear signals critical to neuritogenesis. Also, standalone peptides encoded by CaV1 DCT (distal carboxyl-terminus) act as nuclear transcription factors reportedly promoting neuritogenesis. Here, by focusing on exemplary CaV1.3 and cortical neurons under basal conditions, we discover that cytosolic DCT peptides downregulate neurite outgrowth by the interactions with CaV1's apo-calmodulin binding motif. Distinct from nuclear DCT, various cytosolic peptides exert a gradient of inhibitory effects on Ca2+ influx via CaV1 channels and neurite extension and arborization, and also the intermediate events including CREB activation and c-Fos expression. The inhibition efficacies of DCT are quantitatively correlated with its binding affinities. Meanwhile, cytosolic inhibition tends to facilitate neuritogenesis indirectly by favoring Ca2+-sensitive nuclear retention of DCT. In summary, DCT peptides as a class of CaV1 inhibitors specifically regulate the channel activity-neuritogenesis coupling in a variant-, affinity-, and localization-dependent manner.
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Affiliation(s)
- Yaxiong Yang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China.,X-Laboratory for Ion-Channel Engineering, Beihang University, Beijing, 100083, China
| | - Zhen Yu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China.,X-Laboratory for Ion-Channel Engineering, Beihang University, Beijing, 100083, China
| | - Jinli Geng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China.,X-Laboratory for Ion-Channel Engineering, Beihang University, Beijing, 100083, China
| | - Min Liu
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Nan Liu
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, 650091, China
| | - Ping Li
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China
| | - Weili Hong
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China
| | - Shuhua Yue
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China
| | - He Jiang
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Haiyan Ge
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Feng Qian
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Wei Xiong
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Ping Wang
- Laboratory for Biomedical Engineering of Ministry of Education, Zhejiang University, Hangzhou, 310027, China
| | - Sen Song
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Xiaomei Li
- School of Medicine, Tsinghua University, Beijing, 100084, China.
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China.
| | - Xiaodong Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, Beijing, 100083, China. .,X-Laboratory for Ion-Channel Engineering, Beihang University, Beijing, 100083, China.
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18
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Barret DCA, Schertler GFX, Kaupp UB, Marino J. Structural basis of the partially open central gate in the human CNGA1/CNGB1 channel explained by additional density for calmodulin in cryo-EM map. J Struct Biol 2021; 214:107828. [PMID: 34971760 DOI: 10.1016/j.jsb.2021.107828] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/09/2021] [Accepted: 12/23/2021] [Indexed: 11/19/2022]
Abstract
The recently reported structure of the human CNGA1/CNGB1 CNG channel in the open state (Xue et al., 2021a) shows that one CNGA1 and one CNGB1 subunit do not open the central hydrophobic gate completely upon cGMP binding. This is different from what has been reported for CNGA homomeric channels (Xue et al., 2021b; Zheng et al., 2020). In seeking to understand how this difference is due to the presence of the CNGB1 subunit, we find that the deposited density map (Xue et al., 2021a) (EMDB 24465) contains an additional density not reported in the images of the original publication. This additional density fits well the structure of calmodulin (CaM), and it unambiguously connects the newly identified D-helix of CNGB1 to one of the CNGA1 helices (A1R) participating in the coiled-coil region. Interestingly, the CNGA1 subunit that engages in the interaction with this additional density is the one that, together with CNGB1, does not open completely the central gate. The sequence of the D-helix of CNGB1 contains a known CaM-binding site of exquisitely high affinity - named CaM2 (Weitz et al., 1998) -, and thus the presence of CaM in that region is not surprising. The mechanism through which CaM reduces currents across the membrane by acting on the native channel (Bauer, 1996; Hsu and Molday, 1993; Weitz et al., 1998) remains unclear. We suggest that the presence of CaM may explain the partially open central gate reported by Xue et al. (2021a). The structure of the open and closed states of the CNGA1/CNGB1 channel may be different with and without CaM present.
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Affiliation(s)
- Diane C A Barret
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Switzerland
| | - Gebhard F X Schertler
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Switzerland; Department of Biology, ETH-Zurich, Switzerland
| | - U Benjamin Kaupp
- Center for Advanced European Studies and Research (CAESAR), Bonn, Germany; Life and Medical Sciences Institute LIMES, University of Bonn, Germany
| | - Jacopo Marino
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Switzerland.
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19
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Ames JB. L-Type Ca 2+ Channel Regulation by Calmodulin and CaBP1. Biomolecules 2021; 11:biom11121811. [PMID: 34944455 PMCID: PMC8699282 DOI: 10.3390/biom11121811] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 01/12/2023] Open
Abstract
L-type voltage-gated Ca2+ channels (CaV1.2 and CaV1.3, called CaV) interact with the Ca2+ sensor proteins, calmodulin (CaM) and Ca2+ binding Protein 1 (CaBP1), that oppositely control Ca2+-dependent channel activity. CaM and CaBP1 can each bind to the IQ-motif within the C-terminal cytosolic domain of CaV, which promotes increased channel open probability under basal conditions. At elevated cytosolic Ca2+ levels (caused by CaV channel opening), Ca2+-bound CaM binding to CaV is essential for promoting rapid Ca2+-dependent channel inactivation (CDI). By contrast, CaV binding to CaBP1 prevents CDI and promotes Ca2+-induced channel opening (called CDF). In this review, I provide an overview of the known structures of CaM and CaBP1 and their structural interactions with the IQ-motif to help understand how CaM promotes CDI, whereas CaBP1 prevents CDI and instead promotes CDF. Previous electrophysiology studies suggest that Ca2+-free forms of CaM and CaBP1 may pre-associate with CaV under basal conditions. However, previous Ca2+ binding data suggest that CaM and CaBP1 are both calculated to bind to Ca2+ with an apparent dissociation constant of ~100 nM when CaM or CaBP1 is bound to the IQ-motif. Since the neuronal basal cytosolic Ca2+ concentration is ~100 nM, nearly half of the neuronal CaV channels are suggested to be bound to Ca2+-bound forms of either CaM or CaBP1 under basal conditions. The pre-association of CaV with calcified forms of CaM or CaBP1 are predicted here to have functional implications. The Ca2+-bound form of CaBP1 is proposed to bind to CaV under basal conditions to block CaV binding to CaM, which could explain how CaBP1 might prevent CDI.
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Affiliation(s)
- James B Ames
- Department of Chemistry, University of California, Davis, CA 95616, USA
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20
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Young BD, Varney KM, Wilder PT, Costabile BK, Pozharski E, Cook ME, Godoy-Ruiz R, Clarke OB, Mancia F, Weber DJ. Physiologically Relevant Free Ca 2+ Ion Concentrations Regulate STRA6-Calmodulin Complex Formation via the BP2 Region of STRA6. J Mol Biol 2021; 433:167272. [PMID: 34592217 PMCID: PMC8568335 DOI: 10.1016/j.jmb.2021.167272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/13/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022]
Abstract
The interaction of calmodulin (CaM) with the receptor for retinol uptake, STRA6, involves an α-helix termed BP2 that is located on the intracellular side of this homodimeric transporter (Chen et al., 2016 [1]). In the absence of Ca2+, NMR data showed that a peptide derived from BP2 bound to the C-terminal lobe (C-lobe) of Mg2+-bound CaM (MgCaM). Upon titration of Ca2+ into MgCaM-BP2, NMR chemical shift perturbations (CSPs) were observed for residues in the C-lobe, including those in the EF-hand Ca2+-binding domains, EF3 and EF4 (CaKD = 60 ± 7 nM). As higher concentrations of free Ca2+ were achieved, CSPs occurred for residues in the N-terminal lobe (N-lobe) including those in EF1 and EF2 (CaKD = 1000 ± 160 nM). Thermodynamic and kinetic Ca2+ binding studies showed that BP2 addition increased the Ca2+-binding affinity of CaM and slowed its Ca2+ dissociation rates (koff) in both the C- and N-lobe EF-hand domains, respectively. These data are consistent with BP2 binding to the C-lobe of CaM at low free Ca2+ concentrations (<100 nM) like those found at resting intracellular levels. As free Ca2+ levels approach 1000 nM, which is typical inside a cell upon an intracellular Ca2+-signaling event, BP2 is shown here to interact with both the N- and C-lobes of Ca2+-loaded CaM (CaCaM-BP2). Because this structural rearrangement observed for the CaCaM-BP2 complex occurs as intracellular free Ca2+ concentrations approach those typical of a Ca2+-signaling event (CaKD = 1000 ± 160 nM), this conformational change could be relevant to vitamin A transport by full-length CaCaM-STRA6.
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Affiliation(s)
- Brianna D Young
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Kristen M Varney
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Paul T Wilder
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Brianna K Costabile
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Edwin Pozharski
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Mary E Cook
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA
| | - Raquel Godoy-Ruiz
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - David J Weber
- The Center for Biomolecular Therapeutics (CBT), Department of Biochemistry and Molecular Biology University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD 21201, USA; The Institute of Bioscience and Biotechnology Research (IBBR), 9600 Gudelsky Dr., Rockville, MD 20850, USA.
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21
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The molecular basis of the inhibition of Ca V1 calcium-dependent inactivation by the distal carboxy tail. J Biol Chem 2021; 296:100502. [PMID: 33667546 PMCID: PMC8054141 DOI: 10.1016/j.jbc.2021.100502] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/25/2021] [Accepted: 03/01/2021] [Indexed: 12/26/2022] Open
Abstract
Ca2+/calmodulin-dependent inactivation (CDI) of CaV channels is a critical regulatory process that tunes the kinetics of Ca2+ entry for different cell types and physiologic responses. CDI is mediated by calmodulin (CaM), which is bound to the IQ domain of the CaV carboxy tail. This modulatory process is tailored by alternative splicing such that select splice variants of CaV1.3 and CaV1.4 contain a long distal carboxy tail (DCT). The DCT harbors an inhibitor of CDI (ICDI) module that competitively displaces CaM from the IQ domain, thereby diminishing CDI. While this overall mechanism is now well described, the detailed interactions required for ICDI binding to the IQ domain are yet to be elucidated. Here, we perform alanine-scanning mutagenesis of the IQ and ICDI domains and evaluate the contribution of neighboring regions to CDI inhibition. Through FRET binding analysis, we identify functionally relevant residues within the CaV1.3 IQ domain and the CaV1.4 ICDI and nearby A region, which are required for high-affinity IQ/ICDI binding. Importantly, patch-clamp recordings demonstrate that disruption of this interaction commensurately diminishes ICDI function resulting in the re-emergence of CDI in mutant channels. Furthermore, CaV1.2 channels harbor a homologous DCT; however, the ICDI region of this channel does not appear to appreciably modulate CaV1.2 CDI. Yet coexpression of CaV1.2 ICDI with select CaV1.3 splice variants significantly disrupts CDI, implicating a cross-channel modulatory scheme in cells expressing both channel subtypes. In all, these findings provide new insights into a molecular rheostat that fine-tunes Ca2+-entry and supports normal neuronal and cardiac function.
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22
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Papa A, Kushner J, Hennessey JA, Katchman AN, Zakharov SI, Chen BX, Yang L, Lu R, Leong S, Diaz J, Liu G, Roybal D, Liao X, del Rivero Morfin PJ, Colecraft HM, Pitt GS, Clarke O, Topkara V, Ben-Johny M, Marx SO. Adrenergic Ca V1.2 Activation via Rad Phosphorylation Converges at α 1C I-II Loop. Circ Res 2021; 128:76-88. [PMID: 33086983 PMCID: PMC7790865 DOI: 10.1161/circresaha.120.317839] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
RATIONALE Changing activity of cardiac CaV1.2 channels under basal conditions, during sympathetic activation, and in heart failure is a major determinant of cardiac physiology and pathophysiology. Although cardiac CaV1.2 channels are prominently upregulated via activation of PKA (protein kinase A), essential molecular details remained stubbornly enigmatic. OBJECTIVE The primary goal of this study was to determine how various factors converging at the CaV1.2 I-II loop interact to regulate channel activity under basal conditions, during β-adrenergic stimulation, and in heart failure. METHODS AND RESULTS We generated transgenic mice with expression of CaV1.2 α1C subunits with (1) mutations ablating interaction between α1C and β-subunits, (2) flexibility-inducing polyglycine substitutions in the I-II loop (GGG-α1C), or (3) introduction of the alternatively spliced 25-amino acid exon 9* mimicking a splice variant of α1C upregulated in the hypertrophied heart. Introducing 3 glycine residues that disrupt a rigid IS6-α-interaction domain helix markedly reduced basal open probability despite intact binding of CaVβ to α1C I-II loop and eliminated β-adrenergic agonist stimulation of CaV1.2 current. In contrast, introduction of the exon 9* splice variant in the α1C I-II loop, which is increased in ventricles of patients with end-stage heart failure, increased basal open probability but did not attenuate stimulatory response to β-adrenergic agonists when reconstituted heterologously with β2B and Rad or transgenically expressed in cardiomyocytes. CONCLUSIONS Ca2+ channel activity is dynamically modulated under basal conditions, during β-adrenergic stimulation, and in heart failure by mechanisms converging at the α1C I-II loop. CaVβ binding to α1C stabilizes an increased channel open probability gating mode by a mechanism that requires an intact rigid linker between the β-subunit binding site in the I-II loop and the channel pore. Release of Rad-mediated inhibition of Ca2+ channel activity by β-adrenergic agonists/PKA also requires this rigid linker and β-binding to α1C.
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Affiliation(s)
- Arianne Papa
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
- Department of Physiology and Cellular Biophysics
| | - Jared Kushner
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Jessica A. Hennessey
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Alexander N. Katchman
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Sergey I. Zakharov
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Bi-xing Chen
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Ree Lu
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Stephen Leong
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics
| | - Guoxia Liu
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | - Daniel Roybal
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
- Department of Pharmacology and Molecular Signaling, Columbia University, Vagelos College of Physicians and Surgeons
| | - Xianghai Liao
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | | | - Henry M. Colecraft
- Department of Physiology and Cellular Biophysics
- Department of Pharmacology and Molecular Signaling, Columbia University, Vagelos College of Physicians and Surgeons
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College
| | | | - Veli Topkara
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
| | | | - Steven O. Marx
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY 10032
- Department of Pharmacology and Molecular Signaling, Columbia University, Vagelos College of Physicians and Surgeons
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23
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Properties of Calmodulin Binding to Na V1.2 IQ Motif and Its Autism-Associated Mutation R1902C. Neurochem Res 2021; 46:523-534. [PMID: 33394222 DOI: 10.1007/s11064-020-03189-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/15/2020] [Accepted: 11/26/2020] [Indexed: 01/08/2023]
Abstract
Voltage-gated sodium channels (VGSCs) are fundamental to the initiation and propagation of action potentials in excitable cells. Ca2+/calmodulin (CaM) binds to VGSC type II (NaV1.2) isoleucine and glutamine (IQ) motif. An autism-associated mutation in NaV1.2 IQ motif, Arg1902Cys (R1902C), has been reported to affect the combination between CaM and the IQ motif compared to that of the wild type IQ motif. However, the detailed properties for the Ca2+-regulated binding of CaM to NaV1.2 IQ (1901Lys-1927Lys, IQwt) and mutant IQ motif (IQR1902C) remains unclear. Here, the binding ability of CaM and CaM's constituent proteins including N- and C lobe to the IQ motif of NaV1.2 and its mutant was investigated by protein pull-down experiments. We discovered that the combination between CaM and the IQ motif was U-shaped with the highest at [Ca2+] ≈ free and the lowest at 100 nM [Ca2+]. In the IQR1902C mutant, Ca2+-dependence of CaM binding was nearly lost. Consequently, the binding of CaM to IQR1902C at 100 and 500 nM [Ca2+] was increased compared to that of IQwt. Both N- and C lobe of CaM could bind with NaV1.2 IQ motif and IQR1902C mutant, with the major effect of C lobe. Furthermore, CaMKII had no impact on the binding between CaM and NaV1.2 IQ motif. This research offers novel insight to the regulation of NaV1.2 IQwt and IQR1902C motif, an autism-associated mutation, by CaM.
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Kang PW, Westerlund AM, Shi J, White KM, Dou AK, Cui AH, Silva JR, Delemotte L, Cui J. Calmodulin acts as a state-dependent switch to control a cardiac potassium channel opening. SCIENCE ADVANCES 2020; 6:6/50/eabd6798. [PMID: 33310856 PMCID: PMC7732179 DOI: 10.1126/sciadv.abd6798] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/27/2020] [Indexed: 05/09/2023]
Abstract
Calmodulin (CaM) and phosphatidylinositol 4,5-bisphosphate (PIP2) are potent regulators of the voltage-gated potassium channel KCNQ1 (KV7.1), which conducts the cardiac I Ks current. Although cryo-electron microscopy structures revealed intricate interactions between the KCNQ1 voltage-sensing domain (VSD), CaM, and PIP2, the functional consequences of these interactions remain unknown. Here, we show that CaM-VSD interactions act as a state-dependent switch to control KCNQ1 pore opening. Combined electrophysiology and molecular dynamics network analysis suggest that VSD transition into the fully activated state allows PIP2 to compete with CaM for binding to VSD. This leads to conformational changes that alter VSD-pore coupling to stabilize open states. We identify a motif in the KCNQ1 cytosolic domain, which works downstream of CaM-VSD interactions to facilitate the conformational change. Our findings suggest a gating mechanism that integrates PIP2 and CaM in KCNQ1 voltage-dependent activation, yielding insights into how KCNQ1 gains the phenotypes critical for its physiological function.
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Affiliation(s)
- Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Annie M Westerlund
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Alex K Dou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Amy H Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Lucie Delemotte
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden.
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA.
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25
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Chakouri N, Diaz J, Yang PS, Ben-Johny M. Ca V channels reject signaling from a second CaM in eliciting Ca 2+-dependent feedback regulation. J Biol Chem 2020; 295:14948-14962. [PMID: 32820053 DOI: 10.1074/jbc.ra120.013777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 08/18/2020] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) regulation of voltage-gated calcium (CaV1-2) channels is a powerful Ca2+-feedback mechanism to adjust channel activity in response to Ca2+ influx. Despite progress in resolving mechanisms of CaM-CaV feedback, the stoichiometry of CaM interaction with CaV channels remains ambiguous. Functional studies that tethered CaM to CaV1.2 suggested that a single CaM sufficed for Ca2+ feedback, yet biochemical, FRET, and structural studies showed that multiple CaM molecules interact with distinct interfaces within channel cytosolic segments, suggesting that functional Ca2+ regulation may be more nuanced. Resolving this ambiguity is critical as CaM is enriched in subcellular domains where CaV channels reside, such as the cardiac dyad. We here localized multiple CaMs to the CaV nanodomain by tethering either WT or mutant CaM that lack Ca2+-binding capacity to the pore-forming α-subunit of CaV1.2, CaV1.3, and CaV2.1 and/or the auxiliary β2A subunit. We observed that a single CaM tethered to either the α or β2A subunit tunes Ca2+ regulation of CaV channels. However, when multiple CaMs are localized concurrently, CaV channels preferentially respond to signaling from the α-subunit-tethered CaM. Mechanistically, the introduction of a second IQ domain to the CaV1.3 carboxyl tail switched the apparent functional stoichiometry, permitting two CaMs to mediate functional regulation. In all, Ca2+ feedback of CaV channels depends exquisitely on a single CaM preassociated with the α-subunit carboxyl tail. Additional CaMs that colocalize with the channel complex are unable to trigger Ca2+-dependent feedback of channel gating but may support alternate regulatory functions.
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Affiliation(s)
- Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA
| | - Philemon S Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
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26
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Colecraft HM. Designer genetically encoded voltage-dependent calcium channel inhibitors inspired by RGK GTPases. J Physiol 2020; 598:1683-1693. [PMID: 32104913 PMCID: PMC7195252 DOI: 10.1113/jp276544] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/07/2020] [Indexed: 12/28/2022] Open
Abstract
High‐voltage‐activated calcium (CaV1/CaV2) channels translate action potentials into Ca2+ influx in excitable cells to control essential biological processes that include; muscle contraction, synaptic transmission, hormone secretion and activity‐dependent regulation of gene expression. Modulation of CaV1/CaV2 channel activity is a powerful mechanism to regulate physiology, and there are a host of intracellular signalling molecules that tune different aspects of CaV channel trafficking and gating for this purpose. Beyond normal physiological regulation, the diverse CaV channel modulatory mechanisms may potentially be co‐opted or interfered with for therapeutic benefits. CaV1/CaV2 channels are potently inhibited by a four‐member sub‐family of Ras‐like GTPases known as RGK (Rad, Rem, Rem2, Gem/Kir) proteins. Understanding the mechanisms by which RGK proteins inhibit CaV1/CaV2 channels has led to the development of novel genetically encoded CaV channel blockers with unique properties; including, chemo‐ and optogenetic control of channel activity, and blocking channels either on the basis of their subcellular localization or by targeting an auxiliary subunit. These genetically encoded CaV channel inhibitors have outstanding utility as enabling research tools and potential therapeutics.
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Affiliation(s)
- Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Department of Pharmacology and Molecular Signaling, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
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27
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Iacobucci GJ, Popescu GK. Ca 2+-Dependent Inactivation of GluN2A and GluN2B NMDA Receptors Occurs by a Common Kinetic Mechanism. Biophys J 2020; 118:798-812. [PMID: 31629478 PMCID: PMC7036730 DOI: 10.1016/j.bpj.2019.07.057] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/14/2019] [Accepted: 07/10/2019] [Indexed: 12/12/2022] Open
Abstract
N-Methyl-d-aspartate (NMDA) receptors are Ca2+-permeable channels gated by glutamate and glycine that are essential for central excitatory transmission. Ca2+-dependent inactivation (CDI) is a regulatory feedback mechanism that reduces GluN2A-type NMDA receptor responses in an activity-dependent manner. Although CDI is mediated by calmodulin binding to the constitutive GluN1 subunit, prior studies suggest that GluN2B-type receptors are insensitive to CDI. We examined the mechanism of CDI subtype dependence using electrophysiological recordings of recombinant NMDA receptors expressed in HEK-293 cells. In physiological external Ca2+, we observed robust CDI of whole-cell GluN2A currents (0.42 ± 0.05) but no CDI in GluN2B currents (0.08 ± 0.07). In contrast, when Ca2+ was supplied intracellularly, robust CDI occurred for both GluN2A and GluN2B currents (0.75 ± 0.03 and 0.67 ± 0.02, respectively). To examine how the source of Ca2+ affects CDI, we recorded one-channel Na+ currents to quantify the receptor gating mechanism while simultaneously monitoring ionomycin-induced intracellular Ca2+ elevations with fluorometry. We found that CDI of both GluN2A and GluN2B receptors reflects receptor accumulation in long-lived closed (desensitized) states, suggesting that the observed subtype-dependent differences in macroscopic CDI reflect intrinsic differences in equilibrium open probabilities (Po). We tested this hypothesis by measuring substantial macroscopic CDI, in physiologic conditions, for high Po GluN2B receptors (GluN1A652Y/GluN2B). Together, these results show that Ca2+ flux produces activity-dependent inactivation for both GluN2A and GluN2B receptors and that the extent of CDI varies with channel Po. These results are consistent with CDI as an autoinhibitory feedback mechanism against excessive Ca2+ load during high Po activation.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York.
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York
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28
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Turner M, Anderson DE, Bartels P, Nieves-Cintron M, Coleman AM, Henderson PB, Man KNM, Tseng PY, Yarov-Yarovoy V, Bers DM, Navedo MF, Horne MC, Ames JB, Hell JW. α-Actinin-1 promotes activity of the L-type Ca 2+ channel Ca v 1.2. EMBO J 2020; 39:e102622. [PMID: 31985069 DOI: 10.15252/embj.2019102622] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 01/05/2023] Open
Abstract
The L-type Ca2+ channel CaV 1.2 governs gene expression, cardiac contraction, and neuronal activity. Binding of α-actinin to the IQ motif of CaV 1.2 supports its surface localization and postsynaptic targeting in neurons. We report a bi-functional mechanism that restricts CaV 1.2 activity to its target sites. We solved separate NMR structures of the IQ motif (residues 1,646-1,664) bound to α-actinin-1 and to apo-calmodulin (apoCaM). The CaV 1.2 K1647A and Y1649A mutations, which impair α-actinin-1 but not apoCaM binding, but not the F1658A and K1662E mutations, which impair apoCaM but not α-actinin-1 binding, decreased single-channel open probability, gating charge movement, and its coupling to channel opening. Thus, α-actinin recruits CaV 1.2 to defined surface regions and simultaneously boosts its open probability so that CaV 1.2 is mostly active when appropriately localized.
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Affiliation(s)
- Matthew Turner
- Department of Chemistry, University of California, Davis, CA, USA
| | - David E Anderson
- Department of Chemistry, University of California, Davis, CA, USA
| | - Peter Bartels
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Andrea M Coleman
- Department of Chemistry, University of California, Davis, CA, USA.,Department of Pharmacology, University of California, Davis, CA, USA
| | - Peter B Henderson
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Kwun Nok Mimi Man
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Pang-Yen Tseng
- Department of Pharmacology, University of California, Davis, CA, USA
| | | | - Donald M Bers
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, CA, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, CA, USA
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29
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Liu G, Papa A, Katchman AN, Zakharov SI, Roybal D, Hennessey JA, Kushner J, Yang L, Chen BX, Kushnir A, Dangas K, Gygi SP, Pitt GS, Colecraft HM, Ben-Johny M, Kalocsay M, Marx SO. Mechanism of adrenergic Ca V1.2 stimulation revealed by proximity proteomics. Nature 2020; 577:695-700. [PMID: 31969708 PMCID: PMC7018383 DOI: 10.1038/s41586-020-1947-z] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/09/2019] [Indexed: 12/20/2022]
Abstract
Increased cardiac contractility during the fight-or-flight response is caused by β-adrenergic augmentation of CaV1.2 voltage-gated calcium channels1-4. However, this augmentation persists in transgenic murine hearts expressing mutant CaV1.2 α1C and β subunits that can no longer be phosphorylated by protein kinase A-an essential downstream mediator of β-adrenergic signalling-suggesting that non-channel factors are also required. Here we identify the mechanism by which β-adrenergic agonists stimulate voltage-gated calcium channels. We express α1C or β2B subunits conjugated to ascorbate peroxidase5 in mouse hearts, and use multiplexed quantitative proteomics6,7 to track hundreds of proteins in the proximity of CaV1.2. We observe that the calcium-channel inhibitor Rad8,9, a monomeric G protein, is enriched in the CaV1.2 microenvironment but is depleted during β-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for β subunits and relieves constitutive inhibition of CaV1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of CaV1.3 and CaV2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels.
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Affiliation(s)
- Guoxia Liu
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Arianne Papa
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Alexander N Katchman
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Sergey I Zakharov
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Daniel Roybal
- Department of Pharmacology, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Jessica A Hennessey
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Jared Kushner
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Bi-Xing Chen
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Alexander Kushnir
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Katerina Dangas
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, NY, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pharmacology, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Marian Kalocsay
- Department of Systems Biology, Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA.
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA.
- Department of Pharmacology, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA.
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30
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Dalal PJ, Muller WA, Sullivan DP. Endothelial Cell Calcium Signaling during Barrier Function and Inflammation. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 190:535-542. [PMID: 31866349 DOI: 10.1016/j.ajpath.2019.11.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/11/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022]
Abstract
Calcium is an essential second messenger in endothelial cells and plays a pivotal role in regulating a number of physiologic processes, including cell migration, angiogenesis, barrier function, and inflammation. An increase in intracellular Ca2+ concentration can trigger a number of diverse signaling pathways under both physiologic and pathologic conditions. In this review, we discuss how calcium signaling pathways in endothelial cells play an essential role in affecting barrier function and facilitating inflammation. Inflammatory mediators, such as thrombin and histamine, increase intracellular calcium levels. This calcium influx causes adherens junction disassembly and cytoskeletal rearrangements to facilitate endothelial cell retraction and increased permeability. During inflammation endothelial cell calcium entry and the calcium-related signaling events also help facilitate several leukocyte-endothelial cell interactions, such as leukocyte rolling, adhesion, and ultimately transendothelial migration.
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Affiliation(s)
- Prarthana J Dalal
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - William A Muller
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - David P Sullivan
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
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31
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Iacobucci GJ, Popescu GK. Spatial Coupling Tunes NMDA Receptor Responses via Ca 2+ Diffusion. J Neurosci 2019; 39:8831-8844. [PMID: 31519826 PMCID: PMC6832682 DOI: 10.1523/jneurosci.0901-19.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 08/11/2019] [Accepted: 09/03/2019] [Indexed: 12/11/2022] Open
Abstract
In the CNS, NMDA receptors generate large and highly regulated Ca2+ signals, which are critical for synaptic development and plasticity. They are highly clustered at postsynaptic sites and along dendritic arbors, but whether this spatial arrangement affects their output is unknown. Synaptic NMDA receptor currents are subject to Ca2+-dependent inactivation (CDI), a type of activity-dependent inhibition that requires intracellular Ca2+ and calmodulin (CaM). We asked whether Ca2+ influx through a single NMDA receptor influences the activity of nearby NMDA receptors, as a possible coupling mechanism. Using cell-attached unitary current recordings from GluN1-2a/GluN2A receptors expressed in human HEK293 cells and from NMDA receptors native to hippocampal neurons from male and female rats, we recorded unitary currents from multichannel patches and used a coupled Markov model to determine the extent of signal coupling (κ). In the absence of extracellular Ca2+, we observed no cooperativity (κ < 0.1), whereas in 1.8 mm external Ca2+, both recombinant and native channels showed substantial negative cooperativity (κ = 0.27). Intracellular Ca2+ chelation or overexpression of a Ca2+-insensitive CaM mutant, reduced coupling, which is consistent with CDI representing the coupling mechanism. In contrast, cooperativity increased substantially (κ = 0.68) when overexpressing the postsynaptic scaffolding protein PSD-95, which increased receptor clustering. Together, these new results demonstrate that NMDA receptor currents are negatively coupled through CDI, and the degree of coupling can be tuned by the distance between receptors. Therefore, channel clustering can influence the activity-dependent reduction in NMDA receptor currents.SIGNIFICANCE STATEMENT At central synapses, NMDA receptors are a major class of excitatory glutamate-gated channels and a source of activity-dependent Ca2+ influx. In turn, fluxed Ca2+ ions bind to calmodulin-primed receptors and reduce further entry, through an autoinhibitory mechanism known as Ca2+ -dependent inactivation (CDI). Here, we show that the diffusion of fluxed Ca2+ between active channels situated within submicroscopic distances amplified receptor inactivation. Thus, calmodulin-mediated gating modulation, an evolutionarily conserved regulatory mechanism, endows synapses with sensitivity to both the temporal sequence and spatial distribution of Ca2+ signals. Perturbations in this mechanism, which coordinates the activity of NMDA receptors within a cluster, may cause signaling alterations that contribute to neuropsychiatric conditions.
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Affiliation(s)
- Gary J Iacobucci
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
| | - Gabriela K Popescu
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, New York 14206
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32
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Johansson JK, Karema-Jokinen VI, Hakanen S, Jylhä A, Uusitalo H, Vihinen-Ranta M, Skottman H, Ihalainen TO, Nymark S. Sodium channels enable fast electrical signaling and regulate phagocytosis in the retinal pigment epithelium. BMC Biol 2019; 17:63. [PMID: 31412898 PMCID: PMC6694495 DOI: 10.1186/s12915-019-0681-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Voltage-gated sodium (Nav) channels have traditionally been considered a trademark of excitable cells. However, recent studies have shown the presence of Nav channels in several non-excitable cells, such as astrocytes and macrophages, demonstrating that the roles of these channels are more diverse than was previously thought. Despite the earlier discoveries, the presence of Nav channel-mediated currents in the cells of retinal pigment epithelium (RPE) has been dismissed as a cell culture artifact. We challenge this notion by investigating the presence and possible role of Nav channels in RPE both ex vivo and in vitro. RESULTS Our work demonstrates that several subtypes of Nav channels are found in human embryonic stem cell (hESC)-derived and mouse RPE, most prominently subtypes Nav1.4, Nav1.6, and Nav1.8. Whole cell patch clamp recordings from the hESC-derived RPE monolayers showed that the current was inhibited by TTX and QX-314 and was sensitive to the selective blockers of the main Nav subtypes. Importantly, we show that the Nav channels are involved in photoreceptor outer segment phagocytosis since blocking their activity significantly reduces the efficiency of particle internalization. Consistent with this role, our electron microscopy results and immunocytochemical analysis show that Nav1.4 and Nav1.8 accumulate on phagosomes and that pharmacological inhibition of Nav channels as well as silencing the expression of Nav1.4 with shRNA impairs the phagocytosis process. CONCLUSIONS Taken together, our study shows that Nav channels are present in RPE, giving this tissue the capacity of fast electrical signaling. The channels are critical for the physiology of RPE with an important role in photoreceptor outer segment phagocytosis.
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Affiliation(s)
- Julia K Johansson
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Viivi I Karema-Jokinen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Satu Hakanen
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Antti Jylhä
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Hannu Uusitalo
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Tays Eye Centre, Tampere University Hospital, Tampere, Finland
| | - Maija Vihinen-Ranta
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Heli Skottman
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Teemu O Ihalainen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Soile Nymark
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
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Ca 2+-dependent regulation of sodium channels Na V1.4 and Na V1.5 is controlled by the post-IQ motif. Nat Commun 2019; 10:1514. [PMID: 30944319 PMCID: PMC6447637 DOI: 10.1038/s41467-019-09570-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/12/2019] [Indexed: 01/01/2023] Open
Abstract
Skeletal muscle voltage-gated Na+ channel (NaV1.4) activity is subject to calmodulin (CaM) mediated Ca2+-dependent inactivation; no such inactivation is observed in the cardiac Na+ channel (NaV1.5). Taken together, the crystal structures of the NaV1.4 C-terminal domain relevant complexes and thermodynamic binding data presented here provide a rationale for this isoform difference. A Ca2+-dependent CaM N-lobe binding site previously identified in NaV1.5 is not present in NaV1.4 allowing the N-lobe to signal other regions of the NaV1.4 channel. Consistent with this mechanism, removing this binding site in NaV1.5 unveils robust Ca2+-dependent inactivation in the previously insensitive isoform. These findings suggest that Ca2+-dependent inactivation is effected by CaM's N-lobe binding outside the NaV C-terminal while CaM's C-lobe remains bound to the NaV C-terminal. As the N-lobe binding motif of NaV1.5 is a mutational hotspot for inherited arrhythmias, the contributions of mutation-induced changes in CDI to arrhythmia generation is an intriguing possibility.
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Salveson I, Anderson DE, Hell JW, Ames JB. Chemical shift assignments of a calmodulin intermediate with two Ca 2+ bound in complex with the IQ-motif of voltage-gated Ca 2+ channels (Ca V1.2). BIOMOLECULAR NMR ASSIGNMENTS 2019; 13:233-237. [PMID: 30788773 PMCID: PMC6440834 DOI: 10.1007/s12104-019-09883-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 02/16/2019] [Indexed: 06/09/2023]
Abstract
Calcium-dependent inactivation (CDI) of neuronal voltage-gated Ca2+ channels (CaV1.2) is important for synaptic plasticity, which is associated with learning and memory. The Ca2+-dependent binding of calmodulin (CaM) to CaV1.2 is essential for CDI. Here we report NMR assignments for a CaM mutant (D21A/D23A/D25A/E32Q/D57A/D59A/N61A/E68Q, called CaMEF12) that contains two Ca2+ bound at the third and fourth EF-hands (EF3 and EF4) and is bound to the IQ-motif (residues 1644-1665) from CaV1.2 (BMRB accession no. 27692).
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Affiliation(s)
- Ian Salveson
- Department of Chemistry, University of California, 95616, Davis, CA, USA
| | - David E Anderson
- Department of Chemistry, University of California, 95616, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, 95616, Davis, CA, USA
| | - James B Ames
- Department of Chemistry, University of California, 95616, Davis, CA, USA.
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35
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Single-Channel Resolution of the Interaction between C-Terminal Ca V1.3 Isoforms and Calmodulin. Biophys J 2019; 116:836-846. [PMID: 30773296 DOI: 10.1016/j.bpj.2019.01.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 01/05/2019] [Accepted: 01/16/2019] [Indexed: 12/21/2022] Open
Abstract
Voltage-dependent calcium (CaV) 1.3 channels are involved in the control of cellular excitability and pacemaking in neuronal, cardiac, and sensory cells. Various proteins interact with the alternatively spliced channel C-terminus regulating gating of CaV1.3 channels. Binding of a regulatory calcium-binding protein calmodulin (CaM) to the proximal C-terminus leads to the boosting of channel activity and promotes calcium-dependent inactivation (CDI). The C-terminal modulator domain (CTM) of CaV1.3 channels can interfere with the CaM binding, thereby inhibiting channel activity and CDI. Here, we compared single-channel gating behavior of two natural CaV1.3 splice isoforms: the long CaV1.342 with the full-length CTM and the short CaV1.342A with the C-terminus truncated before the CTM. We found that CaM regulation of CaV1.3 channels is dynamic on a minute timescale. We observed that at equilibrium, single CaV1.342 channels occasionally switched from low to high open probability, which perhaps reflects occasional binding of CaM despite the presence of CTM. Similarly, when the amount of the available CaM in the cell was reduced, the short CaV1.342A isoform showed patterns of the low channel activity. CDI also underwent periodic changes with corresponding kinetics in both isoforms. Our results suggest that the competition between CTM and CaM is influenced by calcium, allowing further fine-tuning of CaV1.3 channel activity for particular cellular needs.
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36
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A Selectivity Filter Gate Controls Voltage-Gated Calcium Channel Calcium-Dependent Inactivation. Neuron 2019; 101:1134-1149.e3. [DOI: 10.1016/j.neuron.2019.01.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 11/12/2018] [Accepted: 12/31/2018] [Indexed: 11/22/2022]
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37
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Pan Y, Chai X, Gao Q, Zhou L, Zhang S, Li L, Luan S. Dynamic Interactions of Plant CNGC Subunits and Calmodulins Drive Oscillatory Ca 2+ Channel Activities. Dev Cell 2019; 48:710-725.e5. [PMID: 30713075 DOI: 10.1016/j.devcel.2018.12.025] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/03/2018] [Accepted: 12/28/2018] [Indexed: 12/20/2022]
Abstract
Calcium is a universal signal in all eukaryotes, but the mechanism for encoding calcium signatures remains largely unknown. Calcium oscillations control pollen tube growth and fertilization in flowering plants, serving as a model for dissecting the molecular machines that mediate calcium fluctuations. We report that pollen-tube-specific cyclic nucleotide-gated channels (CNGC18, CNGC8, and CNGC7) together with calmodulin 2 (CaM2) constitute a molecular switch that either opens or closes the calcium channel depending on cellular calcium levels. Under low calcium, calcium-free calmodulin 2 (Apo-CaM2) interacts with CNGC18-CNGC8 complex, leading to activation of the influx channel and consequently increasing cytosolic calcium levels. Calcium-bound CaM2 dissociates from CNGC18/8 heterotetramer, closing the channel and initiating a downturn of cellular calcium levels. We further reconstituted the calcium oscillator in HEK293 cells, supporting the model that Ca2+-CaM-dependent regulation of CNGC channel activity provides an auto-regulatory feedback mechanism for calcium oscillations during pollen tube growth.
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Affiliation(s)
- Yajun Pan
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xuyang Chai
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Qifei Gao
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Liming Zhou
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Sisi Zhang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Legong Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China.
| | - Sheng Luan
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
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38
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Pancaroglu R, Van Petegem F. Calcium Channelopathies: Structural Insights into Disorders of the Muscle Excitation–Contraction Complex. Annu Rev Genet 2018; 52:373-396. [DOI: 10.1146/annurev-genet-120417-031311] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ion channels are membrane proteins responsible for the passage of ions down their electrochemical gradients and across biological membranes. In this, they generate and shape action potentials and provide secondary messengers for various signaling pathways. They are often part of larger complexes containing auxiliary subunits and regulatory proteins. Channelopathies arise from mutations in the genes encoding ion channels or their associated proteins. Recent advances in cryo-electron microscopy have resulted in an explosion of ion channel structures in multiple states, generating a wealth of new information on channelopathies. Disease-associated mutations fall into different categories, interfering with ion permeation, protein folding, voltage sensing, ligand and protein binding, and allosteric modulation of channel gating. Prime examples of these are Ca2+-selective channels expressed in myocytes, for which multiple structures in distinct conformational states have recently been uncovered. We discuss the latest insights into these calcium channelopathies from a structural viewpoint.
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Affiliation(s)
- Raika Pancaroglu
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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39
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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] [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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40
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Engineering selectivity into RGK GTPase inhibition of voltage-dependent calcium channels. Proc Natl Acad Sci U S A 2018; 115:12051-12056. [PMID: 30397133 PMCID: PMC6255209 DOI: 10.1073/pnas.1811024115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetically encoded inhibitors for voltage-dependent Ca2+ (CaV) channels (GECCIs) are useful research tools and potential therapeutics. Rad/Rem/Rem2/Gem (RGK) proteins are Ras-like G proteins that potently inhibit high voltage-activated (HVA) Ca2+ (CaV1/CaV2 family) channels, but their nonselectivity limits their potential applications. We hypothesized that nonselectivity of RGK inhibition derives from their binding to auxiliary CaVβ-subunits. To investigate latent CaVβ-independent components of inhibition, we coexpressed each RGK individually with CaV1 (CaV1.2/CaV1.3) or CaV2 (CaV2.1/CaV2.2) channels reconstituted in HEK293 cells with either wild-type (WT) β2a or a mutant version (β2a,TM) that does not bind RGKs. All four RGKs strongly inhibited CaV1/CaV2 channels reconstituted with WT β2a By contrast, when channels were reconstituted with β2a,TM, Rem inhibited only CaV1.2, Rad selectively inhibited CaV1.2 and CaV2.2, while Gem and Rem2 were ineffective. We generated mutant RGKs (Rem[R200A/L227A] and Rad[R208A/L235A]) unable to bind WT CaVβ, as confirmed by fluorescence resonance energy transfer. Rem[R200A/L227A] selectively blocked reconstituted CaV1.2 while Rad[R208A/L235A] inhibited CaV1.2/CaV2.2 but not CaV1.3/CaV2.1. Rem[R200A/L227A] and Rad[R208A/L235A] both suppressed endogenous CaV1.2 channels in ventricular cardiomyocytes and selectively blocked 25 and 62%, respectively, of HVA currents in somatosensory neurons of the dorsal root ganglion, corresponding to their distinctive selectivity for CaV1.2 and CaV1.2/CaV2.2 channels. Thus, we have exploited latent β-binding-independent Rem and Rad inhibition of specific CaV1/CaV2 channels to develop selective GECCIs with properties unmatched by current small-molecule CaV channel blockers.
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41
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Williams B, Haeseleer F, Lee A. Splicing of an automodulatory domain in Ca v1.4 Ca 2+ channels confers distinct regulation by calmodulin. J Gen Physiol 2018; 150:1676-1687. [PMID: 30355583 PMCID: PMC6279360 DOI: 10.1085/jgp.201812140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/03/2018] [Indexed: 12/17/2022] Open
Abstract
Cav1.4 Ca2+ channels provide maintained Ca2+ entry to support sustained neurotransmitter release, but a retinal splice variant exhibits calmodulin-dependent inactivation. Williams et al. show that the N lobe of calmodulin is involved in this process as well as Ca2+-dependent enhancement of channel activation. Ca2+ influx through Cav1.4 L-type Ca2+ channels supports the sustained release of glutamate from photoreceptor synaptic terminals in darkness, a process that is critical for vision. Consistent with this role, Cav1.4 exhibits weak Ca2+-dependent inactivation (CDI)—a negative feedback regulation mediated by Ca2+-bound calmodulin (CaM). CaM binds to a conserved IQ domain in the proximal C-terminal domain of Cav channels, but in Cav1.4, a C-terminal modulatory domain (CTM) disrupts interactions with CaM. Exon 47 encodes a portion of the CTM and is deleted in a Cav1.4 splice variant (Cav1.4Δex47) that is highly expressed in the human retina. Cav1.4Δex47 exhibits CDI and enhanced voltage-dependent activation, similar to that caused by a mutation that is associated with congenital stationary night blindness type 2, in which the CTM is deleted (K1591X). The presence of CDI and very negative activation thresholds in a naturally occurring variant of Cav1.4 are perplexing considering that these properties are expected to be maladaptive for visual signaling and result in night blindness in the case of K1591X. Here we show that Cav1.4Δex47 and K1591X exhibit fundamental differences in their regulation by CaM. In Cav1.4Δex47, CDI requires both the N-terminal (N lobe) and C-terminal (C lobe) lobes of CaM to bind Ca2+, whereas CDI in K1591X is driven mainly by Ca2+ binding to the C lobe. Moreover, the CaM N lobe causes a Ca2+-dependent enhancement of activation of Cav1.4Δex47 but not K1591X. We conclude that the residual CTM in Cav1.4Δex47 enables a form of CaM N lobe regulation of activation and CDI that is absent in K1591X. Interaction with the N lobe of CaM, which is more sensitive to global elevations in cytosolic Ca2+ than the C lobe, may allow Cav1.4Δex47 to be modulated by a wider range of synaptic Ca2+ concentrations than K1591X; this may distinguish the normal physiological function of Cav1.4Δex47 from the pathological consequences of K1591X.
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Affiliation(s)
- Brittany Williams
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA
| | - Françoise Haeseleer
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA .,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, IA.,Department of Otolaryngology Head-Neck Surgery, University of Iowa, Iowa City, IA.,Department of Neurology, University of Iowa, Iowa City, IA
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42
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Mansilla A, Jordán-Álvarez S, Santana E, Jarabo P, Casas-Tintó S, Ferrús A. Molecular mechanisms that change synapse number. J Neurogenet 2018; 32:155-170. [DOI: 10.1080/01677063.2018.1506781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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43
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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] [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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44
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The Effect of Ca 2+, Lobe-Specificity, and CaMKII on CaM Binding to Na V1.1. Int J Mol Sci 2018; 19:ijms19092495. [PMID: 30142967 PMCID: PMC6165294 DOI: 10.3390/ijms19092495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 08/06/2018] [Accepted: 08/13/2018] [Indexed: 11/17/2022] Open
Abstract
Calmodulin (CaM) is well known as an activator of calcium/calmodulin-dependent protein kinase II (CaMKII). Voltage-gated sodium channels (VGSCs) are basic signaling molecules in excitable cells and are crucial molecular targets for nervous system agents. However, the way in which Ca2+/CaM/CaMKII cascade modulates NaV1.1 IQ (isoleucine and glutamine) domain of VGSCs remains obscure. In this study, the binding of CaM, its mutants at calcium binding sites (CaM12, CaM34, and CaM1234), and truncated proteins (N-lobe and C-lobe) to NaV1.1 IQ domain were detected by pull-down assay. Our data showed that the binding of Ca2+/CaM to the NaV1.1 IQ was concentration-dependent. ApoCaM (Ca2+-free form of calmodulin) bound to NaV1.1 IQ domain preferentially more than Ca2+/CaM. Additionally, the C-lobe of CaM was the predominant domain involved in apoCaM binding to NaV1.1 IQ domain. By contrast, the N-lobe of CaM was predominant in the binding of Ca2+/CaM to NaV1.1 IQ domain. Moreover, CaMKII-mediated phosphorylation increased the binding of Ca2+/CaM to NaV1.1 IQ domain due to one or several phosphorylation sites in T1909, S1918, and T1934 of NaV1.1 IQ domain. This study provides novel mechanisms for the modulation of NaV1.1 by the Ca2+/CaM/CaMKII axis. For the first time, we uncover the effect of Ca2+, lobe-specificity and CaMKII on CaM binding to NaV1.1.
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45
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Niu J, Yang W, Yue DT, Inoue T, Ben-Johny M. Duplex signaling by CaM and Stac3 enhances Ca V1.1 function and provides insights into congenital myopathy. J Gen Physiol 2018; 150:1145-1161. [PMID: 29950399 PMCID: PMC6080896 DOI: 10.1085/jgp.201812005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/23/2018] [Accepted: 05/11/2018] [Indexed: 01/24/2023] Open
Abstract
CaV1.1 is essential for skeletal muscle excitation-contraction coupling. Its functional expression is tuned by numerous regulatory proteins, yet underlying modulatory mechanisms remain ambiguous as CaV1.1 fails to function in heterologous systems. In this study, by dissecting channel trafficking versus gating, we evaluated the requirements for functional CaV1.1 in heterologous systems. Although coexpression of the auxiliary β subunit is sufficient for surface-membrane localization, this baseline trafficking is weak, and channels elicit a diminished open probability. The regulatory proteins calmodulin and stac3 independently enhance channel trafficking and gating via their interaction with the CaV1.1 carboxy terminus. Myopathic stac3 mutations weaken channel binding and diminish trafficking. Our findings demonstrate that multiple regulatory proteins orchestrate CaV1.1 function via duplex mechanisms. Our work also furnishes insights into the pathophysiology of stac3-associated congenital myopathy and reveals novel avenues for pharmacological intervention.
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Affiliation(s)
- Jacqueline Niu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | - Wanjun Yang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
| | | | - Takanari Inoue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD
- Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, Baltimore, MD
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY
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46
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Limpitikul WB, Viswanathan MC, O'Rourke B, Yue DT, Cammarato A. Conservation of cardiac L-type Ca 2+ channels and their regulation in Drosophila: A novel genetically-pliable channelopathic model. J Mol Cell Cardiol 2018; 119:64-74. [PMID: 29684406 PMCID: PMC6154789 DOI: 10.1016/j.yjmcc.2018.04.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 04/08/2018] [Accepted: 04/11/2018] [Indexed: 01/28/2023]
Abstract
Dysregulation of L-type Ca2+ channels (LTCCs) underlies numerous cardiac pathologies. Understanding their modulation with high fidelity relies on investigating LTCCs in their native environment with intact interacting proteins. Such studies benefit from genetic manipulation of endogenous channels in cardiomyocytes, which often proves cumbersome in mammalian models. Drosophila melanogaster, however, offers a potentially efficient alternative as it possesses a relatively simple heart, is genetically pliable, and expresses well-conserved genes. Fluorescence in situ hybridization confirmed an abundance of Ca-α1D and Ca-α1T mRNA in fly myocardium, which encode subunits that specify hetero-oligomeric channels homologous to mammalian LTCCs and T-type Ca2+ channels, respectively. Cardiac-specific knockdown of Ca-α1D via interfering RNA abolished cardiac contraction, suggesting Ca-α1D (i.e. A1D) represents the primary functioning Ca2+ channel in Drosophila hearts. Moreover, we successfully isolated viable single cardiomyocytes and recorded Ca2+ currents via patch clamping, a feat never before accomplished with the fly model. The profile of Ca2+ currents recorded in individual cells when Ca2+ channels were hypomorphic, absent, or under selective LTCC blockage by nifedipine, additionally confirmed the predominance of A1D current across all activation voltages. T-type current, activated at more negative voltages, was also detected. Lastly, A1D channels displayed Ca2+-dependent inactivation, a critical negative feedback mechanism of LTCCs, and the current through them was augmented by forskolin, an activator of the protein kinase A pathway. In sum, the Drosophila heart possesses a conserved compendium of Ca2+ channels, suggesting that the fly may serve as a robust and effective platform for studying cardiac channelopathies.
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Affiliation(s)
- Worawan B Limpitikul
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States
| | - Meera C Viswanathan
- Institute of CardioScience, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States
| | - Brian O'Rourke
- Institute of CardioScience, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States
| | - Anthony Cammarato
- Institute of CardioScience, Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States; Department of Physiology, The Johns Hopkins University School of Medicine, Ross Research Building, 720 Rutland Avenue, Baltimore, MD 21205, United States.
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47
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Waldner DM, Bech-Hansen NT, Stell WK. Channeling Vision: Ca V1.4-A Critical Link in Retinal Signal Transmission. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7272630. [PMID: 29854783 PMCID: PMC5966690 DOI: 10.1155/2018/7272630] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/15/2018] [Indexed: 01/09/2023]
Abstract
Voltage-gated calcium channels (VGCC) are key to many biological functions. Entry of Ca2+ into cells is essential for initiating or modulating important processes such as secretion, cell motility, and gene transcription. In the retina and other neural tissues, one of the major roles of Ca2+-entry is to stimulate or regulate exocytosis of synaptic vesicles, without which synaptic transmission is impaired. This review will address the special properties of one L-type VGCC, CaV1.4, with particular emphasis on its role in transmission of visual signals from rod and cone photoreceptors (hereafter called "photoreceptors," to the exclusion of intrinsically photoreceptive retinal ganglion cells) to the second-order retinal neurons, and the pathological effects of mutations in the CACNA1F gene which codes for the pore-forming α1F subunit of CaV1.4.
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Affiliation(s)
- D. M. Waldner
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - N. T. Bech-Hansen
- Department of Medical Genetics and Department of Surgery, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - W. K. Stell
- Department of Cell Biology and Anatomy and Department of Surgery, Hotchkiss Brain Institute, and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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48
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Yang Y, Liu N, He Y, Liu Y, Ge L, Zou L, Song S, Xiong W, Liu X. Improved calcium sensor GCaMP-X overcomes the calcium channel perturbations induced by the calmodulin in GCaMP. Nat Commun 2018; 9:1504. [PMID: 29666364 PMCID: PMC5904127 DOI: 10.1038/s41467-018-03719-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 03/09/2018] [Indexed: 01/09/2023] Open
Abstract
GCaMP, one popular type of genetically-encoded Ca2+ indicator, has been associated with various side-effects. Here we unveil the intrinsic problem prevailing over different versions and applications, showing that GCaMP containing CaM (calmodulin) interferes with both gating and signaling of L-type calcium channels (CaV1). GCaMP acts as an impaired apoCaM and Ca2+/CaM, both critical to CaV1, which disrupts Ca2+ dynamics and gene expression. We then design and implement GCaMP-X, by incorporating an extra apoCaM-binding motif, effectively protecting CaV1-dependent excitation–transcription coupling from perturbations. GCaMP-X resolves the problems of detrimental nuclear accumulation, acute and chronic Ca2+ dysregulation, and aberrant transcription signaling and cell morphogenesis, while still demonstrating excellent Ca2+-sensing characteristics partly inherited from GCaMP. In summary, CaM/CaV1 gating and signaling mechanisms are elucidated for GCaMP side-effects, while allowing the development of GCaMP-X to appropriately monitor cytosolic, submembrane or nuclear Ca2+, which is also expected to guide the future design of CaM-based molecular tools. The popular genetically-encoded Ca2+ indicator, GCaMP, has several side-effects. Here the authors show that GCaMP containing CaM interferes with gating and signaling of L-type calcium channels, which disrupts Ca2+ dynamics and gene expression, and develop GCaMP-X to overcome these limitations.
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Affiliation(s)
- Yaxiong Yang
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China.,School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China.,Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 102402, China.,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084, China
| | - Nan Liu
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China.,School of Life Sciences, Yunan University, Kunming, 650091, China
| | - Yuanyuan He
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China
| | - Yuxia Liu
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China
| | - Lin Ge
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China
| | - Linzhi Zou
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Sen Song
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China.,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084, China
| | - Wei Xiong
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084, China.,School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xiaodong Liu
- Department of Biomedical Engineering, School of Medicine, X-Lab for Transmembrane Signaling Research, Tsinghua University, Beijing, 100084, China. .,School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083, China. .,Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 102402, China. .,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, 100084, China. .,School of Life Sciences, Tsinghua University, Beijing, 100084, China. .,Key Laboratory for Biomedical Engineering of Education Ministry, Zhejiang University, Hangzhou, 310027, China.
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49
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Abstract
Calmodulin (CaM) regulation of voltage-gated calcium (CaV) channels is a powerful Ca2+ feedback mechanism that adjusts Ca2+ influx, affording rich mechanistic insights into Ca2+ decoding. CaM possesses a dual-lobed architecture, a salient feature of the myriad Ca2+-sensing proteins, where two homologous lobes that recognize similar targets hint at redundant signaling mechanisms. Here, by tethering CaM lobes, we demonstrate that bilobal architecture is obligatory for signaling to CaV channels. With one lobe bound, CaV carboxy tail rearranges itself, resulting in a preinhibited configuration precluded from Ca2+ feedback. Reconstitution of two lobes, even as separate molecules, relieves preinhibition and restores Ca2+ feedback. CaV channels thus detect the coincident binding of two Ca2+-free lobes to promote channel opening, a molecular implementation of a logical NOR operation that processes spatiotemporal Ca2+ signals bifurcated by CaM lobes. Overall, a unified scheme of CaV channel regulation by CaM now emerges, and our findings highlight the versatility of CaM to perform exquisite Ca2+ computations.
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50
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Lee N, Jeong S, Kim KC, Kim JA, Park JY, Kang HW, Perez-Reyes E, Lee JH. Ca 2+ Regulation of Ca v3.3 T-type Ca 2+ Channel Is Mediated by Calmodulin. Mol Pharmacol 2017; 92:347-357. [PMID: 28696213 PMCID: PMC11033943 DOI: 10.1124/mol.117.108530] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/03/2017] [Indexed: 01/19/2023] Open
Abstract
Calcium-dependent inactivation of high voltage-activated Ca2+ channels plays a crucial role in limiting rises in intracellular calcium (Ca2+i). A key mediator of these effects is calmodulin, which has been found to bind the C-terminus of the pore-forming α subunit. In contrast, little is known about how Ca2+i can regulate low voltage-activated T-type Ca2+ channels. Using whole cell patch clamp, we examined the biophysical properties of Ca2+ current through the three T-type Ca2+ channel isoforms, Cav3.1, Cav3.2, or Cav3.3, comparing internal solutions containing 27 nM and l μM free Ca2+ Both activation and inactivation kinetics of Cav3.3 current in l μM Ca2+i solution were more rapid than those in 27 nM Ca2+i solution. In addition, both activation and steady-state inactivation curves of Cav3.3 were negatively shifted in the higher Ca2+i solution. In contrast, the biophysical properties of Cav3.1 and Cav3.2 isoforms were not significantly different between the two internal solutions. Overexpression of CaM1234 (a calmodulin mutant that doesn't bind Ca2+) occluded the effects of l μM Ca2+i on Cav3.3, implying that CaM is involved in the Ca2+i regulation effects on Cav3.3. Yeast two-hybrid screening and co-immunoprecipitation experiments revealed a direct interaction of CaM with the carboxyl terminus of Cav3.3. Taken together, our results suggest that Cav3.3 T-type channel is potently regulated by Ca2+i via interaction of Ca2+/CaM with the carboxyl terminus of Cav3.3.
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Affiliation(s)
- Narae Lee
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Sua Jeong
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Kang-Chang Kim
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Jin-Ah Kim
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Jin-Yong Park
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Ho-Won Kang
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Edward Perez-Reyes
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
| | - Jung-Ha Lee
- Department of Life Science and Research Institute for Basic Science, Sogang University, Mapo-gu, Seoul, Republic of Korea (N.L., S.J., K.-C.K., J.-A.K., J.-Y.P., H.-W.K., J.-H.L.) and Department of Pharmacology, University of Virginia, Charlottesville, Virginia (E.P.-R.)
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