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Delgado-Ramírez M, López-Serrano AL, Rodríguez-Menchaca AA. Inhibition of Kv2.1 potassium channels by the antidepressant drug sertraline. Eur J Pharmacol 2024; 970:176487. [PMID: 38458411 DOI: 10.1016/j.ejphar.2024.176487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/07/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Sertraline is a commonly used antidepressant of the selective serotonin reuptake inhibitors (SSRIs) class. In this study, we have used the patch-clamp technique to assess the effects of sertraline on Kv2.1 channels heterologously expressed in HEK-293 cells and on the voltage-gated potassium currents (IKv) of Neuro 2a cells, which are predominantly mediated by Kv2.1 channels. Our results reveal that sertraline inhibits Kv2.1 channels in a concentration-dependent manner. The sertraline-induced inhibition was not voltage-dependent and did not require the channels to be open. The kinetics of activation and deactivation were accelerated and decelerated, respectively, by sertraline. Moreover, the inhibition by this drug was use-dependent. Notably, sertraline significantly modified the inactivation mechanism of Kv2.1 channels; the steady-state inactivation was shifted to hyperpolarized potentials, the closed-state inactivation was enhanced and accelerated, and the recovery from inactivation was slowed, suggesting that this is the main mechanism by which sertraline inhibits Kv2.1 channels. Overall, this study provides novel insights into the pharmacological actions of sertraline on Kv2.1 channels, shedding light on the intricate interaction between SSRIs and ion channel function.
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Affiliation(s)
- Mayra Delgado-Ramírez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico.
| | - Ana Laura López-Serrano
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, 78210, Mexico
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2
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Lopez-Medina AI, Campos-Staffico AM, A Chahal CA, Volkers I, Jacoby JP, Berenfeld O, Luzum JA. Genetic risk factors for drug-induced long QT syndrome: findings from a large real-world case-control study. Pharmacogenomics 2024; 25:117-131. [PMID: 38506312 DOI: 10.2217/pgs-2023-0229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024] Open
Abstract
Aim: Drug-induced long QT syndrome (diLQTS), an adverse effect of many drugs, can lead to sudden cardiac death. Candidate genetic variants in cardiac ion channels have been associated with diLQTS, but several limitations of previous studies hamper clinical utility. Materials & methods: Thus, the purpose of this study was to assess the associations of KCNE1-D85N, KCNE2-I57T and SCN5A-G615E with diLQTS in a large observational case-control study (6,083 self-reported white patients treated with 27 different high-risk QT-prolonging medications; 12.0% with diLQTS). Results: KCNE1-D85N significantly associated with diLQTS (adjusted odds ratio: 2.24 [95% CI: 1.35-3.58]; p = 0.001). Given low minor allele frequencies, the study had insufficient power to analyze KCNE2-I57T and SCN5A-G615E. Conclusion: KCNE1-D85N is a risk factor for diLQTS that should be considered in future clinical practice guidelines.
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Grants
- F32 HL162231, K08 HL146990, R01-HL156961, R21-EB032661, R21-HL153694, T32 TR004371 CSR NIH HHS
- F32 HL162231, K08 HL146990, R01-HL156961, R21-EB032661, R21-HL153694, T32 TR004371 CSR NIH HHS
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Affiliation(s)
- Ana I Lopez-Medina
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
| | | | - Choudhary Anwar A Chahal
- Center for Inherited Cardiovascular Diseases, WellSpan Health, Lancaster, PA, USA
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- Department of Cardiology, Barts Heart Centre, London, UK
| | - Isabella Volkers
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
| | - Juliet P Jacoby
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
| | - Omer Berenfeld
- Center for Arrhythmia Research, Departments of Internal Medicine - Cardiology, Biomedical Engineering, & Applied Physics, University of Michigan, Ann Arbor, MI, USA
| | - Jasmine A Luzum
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI, USA
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3
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Yang H, Wei XS, Gong J, Du XM, Feng HB, Su C, Gilmore C, Yue C, Yu SB, Li C, Sui HJ. The relationship between myodural bridge, atrophy and hyperplasia of the suboccipital musculature, and cerebrospinal fluid dynamics. Sci Rep 2023; 13:18882. [PMID: 37919345 PMCID: PMC10622500 DOI: 10.1038/s41598-023-45820-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 10/24/2023] [Indexed: 11/04/2023] Open
Abstract
The Myodural Bridge (MDB) is a physiological structure that is highly conserved in mammals and many of other tetrapods. It connects the suboccipital muscles to the cervical spinal dura mater (SDM) and transmits the tensile forces generated by the suboccipital muscles to the SDM. Consequently, the MDB has broader physiological potentials than just fixing the SDM. It has been proposed that MDB significantly contributes to the dynamics of cerebrospinal fluid (CSF) movements. Animal models of suboccipital muscle atrophy and hyperplasia were established utilizing local injection of BTX-A and ACE-031. In contrast, animal models with surgical severance of suboccipital muscles, and without any surgical operation were set as two types of negative control groups. CSF secretion and reabsorption rates were then measured for subsequent analysis. Our findings demonstrated a significant increase in CSF secretion rate in rats with the hyperplasia model, while there was a significant decrease in rats with the atrophy and severance groups. We observed an increase in CSF reabsorption rate in both the atrophy and hyperplasia groups, but no significant change was observed in the severance group. Additionally, our immunohistochemistry results revealed no significant change in the protein level of six selected choroid plexus-CSF-related proteins among all these groups. Therefore, it was indicated that alteration of MDB-transmitted tensile force resulted in changes of CSF secretion and reabsorption rates, suggesting the potential role that MDB may play during CSF circulation. This provides a unique research insight into CSF dynamics.
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Affiliation(s)
- Heng Yang
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Xiao-Song Wei
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Jin Gong
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Xue-Mei Du
- Department of Nuclear Medicine, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Hong-Bo Feng
- Department of Nuclear Medicine, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Chang Su
- The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | | | - Chen Yue
- Department of Gynecology ands Obstetrics, Affiliated Zhongshan Hospital of Dalian University, Dalian, Liaoning, China
| | - Sheng-Bo Yu
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China
| | - Chan Li
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China.
| | - Hong-Jin Sui
- Department of Anatomy, Dalian Medical University, Dalian, Liaoning, China.
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4
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Kodirov SA. Adam, amigo, brain, and K channel. Biophys Rev 2023; 15:1393-1424. [PMID: 37975011 PMCID: PMC10643815 DOI: 10.1007/s12551-023-01163-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/28/2023] [Indexed: 11/19/2023] Open
Abstract
Voltage-dependent K+ (Kv) channels are diverse, comprising the classical Shab - Kv2, Shaker - Kv1, Shal - Kv4, and Shaw - Kv3 families. The Shaker family alone consists of Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv1.5, Kv1.6, and Kv1.7. Moreover, the Shab family comprises two functional (Kv2.1 and Kv2.2) and several "silent" alpha subunits (Kv2.3, Kv5, Kv6, Kv8, and Kv9), which do not generate K current. However, e.g., Kv8.1, via heteromerization, inhibits outward currents of the same family or even that of Shaw. This property of Kv8.1 is similar to those of designated beta subunits or non-selective auxiliary elements, including ADAM or AMIGO proteins. Kv channels and, in turn, ADAM may modulate the synaptic long-term potentiation (LTP). Prevailingly, Kv1.1 and Kv1.5 are attributed to respective brain and heart pathologies, some of which may occur simultaneously. The aforementioned channel proteins are apparently involved in several brain pathologies, including schizophrenia and seizures.
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Affiliation(s)
- Sodikdjon A. Kodirov
- Department of Biological Sciences, University of Texas at Brownsville, Brownsville, TX 78520 USA
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia
- Instituto de Medicina Molecular, Universidade de Lisboa, 1649-028 Lisbon, Portugal
- Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341 Russia
- Institute for Physiology and Pathophysiology, Johannes Kepler University, Linz, Austria
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5
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Mokrov GV. Multitargeting in cardioprotection: An example of biaromatic compounds. Arch Pharm (Weinheim) 2023; 356:e2300196. [PMID: 37345968 DOI: 10.1002/ardp.202300196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/23/2023] [Accepted: 05/26/2023] [Indexed: 06/23/2023]
Abstract
A multitarget drug design approach is actively developing in modern medicinal chemistry and pharmacology, especially with regard to multifactorial diseases such as cardiovascular diseases, cancer, and neurodegenerative diseases. A detailed study of many well-known drugs developed within the single-target approach also often reveals additional mechanisms of their real pharmacological action. One of the multitarget drug design approaches can be the identification of the basic pharmacophore models corresponding to a wide range of the required target ligands. Among such models in the group of cardioprotectors is the linked biaromatic system. This review develops the concept of a "basic pharmacophore" using the biaromatic pharmacophore of cardioprotectors as an example. It presents an analysis of possible biological targets for compounds corresponding to the biaromatic pharmacophore and an analysis of the spectrum of biological targets for the five most known and most studied cardioprotective drugs corresponding to this model, and their involvement in the biological effects of these drugs.
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6
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [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: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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7
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Thapa P, Stewart R, Sepela RJ, Vivas O, Parajuli LK, Lillya M, Fletcher-Taylor S, Cohen BE, Zito K, Sack JT. EVAP: A two-photon imaging tool to study conformational changes in endogenous Kv2 channels in live tissues. J Gen Physiol 2021; 153:212666. [PMID: 34581724 PMCID: PMC8480965 DOI: 10.1085/jgp.202012858] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 09/03/2021] [Indexed: 12/29/2022] Open
Abstract
A primary goal of molecular physiology is to understand how conformational changes of proteins affect the function of cells, tissues, and organisms. Here, we describe an imaging method for measuring the conformational changes of the voltage sensors of endogenous ion channel proteins within live tissue, without genetic modification. We synthesized GxTX-594, a variant of the peptidyl tarantula toxin guangxitoxin-1E, conjugated to a fluorophore optimal for two-photon excitation imaging through light-scattering tissue. We term this tool EVAP (Endogenous Voltage-sensor Activity Probe). GxTX-594 targets the voltage sensors of Kv2 proteins, which form potassium channels and plasma membrane–endoplasmic reticulum junctions. GxTX-594 dynamically labels Kv2 proteins on cell surfaces in response to voltage stimulation. To interpret dynamic changes in fluorescence intensity, we developed a statistical thermodynamic model that relates the conformational changes of Kv2 voltage sensors to degree of labeling. We used two-photon excitation imaging of rat brain slices to image Kv2 proteins in neurons. We found puncta of GxTX-594 on hippocampal CA1 neurons that responded to voltage stimulation and retain a voltage response roughly similar to heterologously expressed Kv2.1 protein. Our findings show that EVAP imaging methods enable the identification of conformational changes of endogenous Kv2 voltage sensors in tissue.
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Affiliation(s)
- Parashar Thapa
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Robert Stewart
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Rebecka J Sepela
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Oscar Vivas
- Center for Neuroscience, University of California, Davis, Davis, CA
| | - Laxmi K Parajuli
- Center for Neuroscience, University of California, Davis, Davis, CA
| | - Mark Lillya
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA
| | - Sebastian Fletcher-Taylor
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA.,The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Bruce E Cohen
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA.,Division of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Karen Zito
- Center for Neuroscience, University of California, Davis, Davis, CA
| | - Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA.,Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA
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8
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Mi X, Ding WG, Toyoda F, Kojima A, Omatsu-Kanbe M, Matsuura H. Selective activation of adrenoceptors potentiates I Ks current in pulmonary vein cardiomyocytes through the protein kinase A and C signaling pathways. J Mol Cell Cardiol 2021; 161:86-97. [PMID: 34375616 DOI: 10.1016/j.yjmcc.2021.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/19/2021] [Accepted: 08/04/2021] [Indexed: 10/20/2022]
Abstract
Delayed rectifier K+ current (IKs) is a key contributor to repolarization of action potentials. This study investigated the mechanisms underlying the adrenoceptor-induced potentiation of IKs in pulmonary vein cardiomyocytes (PVC). PVC were isolated from guinea pig pulmonary vein. The action potentials and IKs current were recorded using perforated and conventional whole-cell patch-clamp techniques. The expression of IKs was examined using immunocytochemistry and Western blotting. KCNQ1, a IKs pore-forming protein was detected as a signal band approximately 100 kDa in size, and its immunofluorescence signal was found to be mainly localized on the cell membrane. The IKs current in PVC was markedly enhanced by both β1- and β2-adrenoceptor stimulation with a negative voltage shift in the current activation, although the potentiation was more effectively induced by β2-adrenoceptor stimulation than β1-adrenoceptor stimulation. Both β-adrenoceptor-mediated increases in IKs were attenuated by treatment with the adenylyl cyclase (AC) inhibitor or protein kinase A (PKA) inhibitor. Furthermore, the IKs current was increased by α1-adrenoceptor agonist but attenuated by the protein kinase C (PKC) inhibitor. PVC exhibited action potentials in normal Tyrode solution which was slightly reduced by HMR-1556 a selective IKs blocker. However, HMR-1556 markedly reduced the β-adrenoceptor-potentiated firing rate. The stimulatory effects of β- and α1-adrenoceptor on IKs in PVC are mediated via the PKA and PKC signal pathways. HMR-1556 effectively reduced the firing rate under β-adrenoceptor activation, suggesting that the functional role of IKs might increase during sympathetic excitation under in vivo conditions.
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Affiliation(s)
- Xinya Mi
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan.
| | - Futoshi Toyoda
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Mariko Omatsu-Kanbe
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
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9
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Zhang J, Chen X, Eaton M, Wu J, Ma Z, Lai S, Park A, Ahmad TS, Que Z, Lee JH, Xiao T, Li Y, Wang Y, Olivero-Acosta MI, Schaber JA, Jayant K, Yuan C, Huang Z, Lanman NA, Skarnes WC, Yang Y. Severe deficiency of the voltage-gated sodium channel Na V1.2 elevates neuronal excitability in adult mice. Cell Rep 2021; 36:109495. [PMID: 34348148 PMCID: PMC8382316 DOI: 10.1016/j.celrep.2021.109495] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/30/2021] [Accepted: 07/14/2021] [Indexed: 12/13/2022] Open
Abstract
Scn2a encodes the voltage-gated sodium channel NaV1.2, a main mediator of neuronal action potential firing. The current paradigm suggests that NaV1.2 gain-of-function variants enhance neuronal excitability, resulting in epilepsy, whereas NaV1.2 deficiency impairs neuronal excitability, contributing to autism. However, this paradigm does not explain why ∼20%-30% of individuals with NaV1.2 deficiency still develop seizures. Here, we report the counterintuitive finding that severe NaV1.2 deficiency results in increased neuronal excitability. Using a NaV1.2-deficient mouse model, we show enhanced intrinsic excitability of principal neurons in the prefrontal cortex and striatum, brain regions known to be involved in Scn2a-related seizures. This increased excitability is autonomous and reversible by genetic restoration of Scn2a expression in adult mice. RNA sequencing reveals downregulation of multiple potassium channels, including KV1.1. Correspondingly, KV channel openers alleviate the hyperexcitability of NaV1.2-deficient neurons. This unexpected neuronal hyperexcitability may serve as a cellular basis underlying NaV1.2 deficiency-related seizures.
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Affiliation(s)
- Jingliang Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Xiaoling Chen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Muriel Eaton
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Jiaxiang Wu
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Zhixiong Ma
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Shirong Lai
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Anthony Park
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Talha S Ahmad
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Zhefu Que
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Ji Hea Lee
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Tiange Xiao
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Yuansong Li
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Yujia Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Maria I Olivero-Acosta
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - James A Schaber
- Bioscience Imaging Facility, Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA
| | - Krishna Jayant
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Zhuo Huang
- Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Nadia A Lanman
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - William C Skarnes
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA.
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10
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Fenyves BG, Arnold A, Gharat VG, Haab C, Tishinov K, Peter F, de Quervain D, Papassotiropoulos A, Stetak A. Dual Role of an mps-2/KCNE-Dependent Pathway in Long-Term Memory and Age-Dependent Memory Decline. Curr Biol 2020; 31:527-539.e7. [PMID: 33259792 DOI: 10.1016/j.cub.2020.10.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/14/2020] [Accepted: 10/21/2020] [Indexed: 01/24/2023]
Abstract
Activity-dependent persistent changes in neuronal intrinsic excitability and synaptic strength are underlying learning and memory. Voltage-gated potassium (Kv) channels are potential regulators of memory and may be linked to age-dependent neuronal disfunction. MinK-related peptides (MiRPs) are conserved transmembrane proteins modulating Kv channels; however, their possible role in the regulation of memory and age-dependent memory decline are unknown. Here, we show that, in C. elegans, mps-2 is the sole member of the MiRP family that controls exclusively long-term associative memory (LTAM) in AVA neuron. In addition, we demonstrate that mps-2 also plays a critical role in age-dependent memory decline. In young adult worms, mps-2 is transcriptionally upregulated by CRH-1/cyclic AMP (cAMP)-response-binding protein (CREB) during LTAM, although the mps-2 baseline expression is CREB independent and instead, during aging, relies on nhr-66, which acts as an age-dependent repressor. Deletion of nhr-66 or its binding element in the mps-2 promoter prevents age-dependent transcriptional repression of mps-2 and memory decline. Finally, MPS-2 acts through the modulation of the Kv2.1/KVS-3 and Kv2.2/KVS-4 heteromeric potassium channels. Altogether, we describe a conserved MPS-2/KVS-3/KVS-4 pathway essential for LTAM and also for a programmed control of physiological age-dependent memory decline.
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Affiliation(s)
- Bank G Fenyves
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Department of Molecular Biology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| | - Andreas Arnold
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Vaibhav G Gharat
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Carmen Haab
- Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Kiril Tishinov
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Fabian Peter
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Dominique de Quervain
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland
| | - Andreas Papassotiropoulos
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Biozentrum, Life Sciences Training Facility, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland
| | - Attila Stetak
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland.
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11
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Lisewski U, Köhncke C, Schleussner L, Purfürst B, Lee SM, De Silva A, Manville RW, Abbott GW, Roepke TK. Hypochlorhydria reduces mortality in heart failure caused by Kcne2 gene deletion. FASEB J 2020; 34:10699-10719. [PMID: 32584506 DOI: 10.1096/fj.202000013rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 05/20/2020] [Accepted: 06/02/2020] [Indexed: 12/23/2022]
Abstract
Heart failure (HF) is an increasing global health crisis, affecting 40 million people and causing 50% mortality within 5 years of diagnosis. A fuller understanding of the genetic and environmental factors underlying HF, and novel therapeutic approaches to address it, are urgently warranted. Here, we discovered that cardiac-specific germline deletion in mice of potassium channel β subunit-encoding Kcne2 (Kcne2CS-/- ) causes dilated cardiomyopathy and terminal HF (median longevity, 28 weeks). Mice with global Kcne2 deletion (Kcne2Glo-/- ) exhibit multiple HF risk factors, yet, paradoxically survived over twice as long as Kcne2CS-/- mice. Global Kcne2 deletion, which inhibits gastric acid secretion, reduced the relative abundance of species within Bacteroidales, a bacterial order that positively correlates with increased lifetime risk of human cardiovascular disease. Strikingly, the proton-pump inhibitor omeprazole similarly altered the microbiome and delayed terminal HF in Kcne2CS-/- mice, increasing survival 10-fold at 44 weeks. Thus, genetic or pharmacologic induction of hypochlorhydria and decreased gut Bacteroidales species are associated with lifespan extension in a novel HF model.
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Affiliation(s)
| | - Clemens Köhncke
- Experimental and Clinical Research Center, Berlin, Germany.,Department of Cardiology, Campus Virchow - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Bettina Purfürst
- Electron Microscopy Core Facility, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Soo Min Lee
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Angele De Silva
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Berlin, Germany.,Department of Cardiology and Angiology, Campus Mitte, Charité - Universitätsmedizin Berlin, Berlin, Germany
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12
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Hu Z, Liu J, Zhou L, Tian X, Abbott GW. AKT and ERK1/2 activation via remote ischemic preconditioning prevents Kcne2-dependent sudden cardiac death. Physiol Rep 2020; 7:e13957. [PMID: 30737904 PMCID: PMC6368489 DOI: 10.14814/phy2.13957] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 11/26/2018] [Indexed: 02/05/2023] Open
Abstract
Sudden cardiac death (SCD) is the leading global cause of mortality. SCD often arises from cardiac ischemia reperfusion (IR) injury, pathologic sequence variants within ion channel genes, or a combination of the two. Alternative approaches are needed to prevent or ameliorate ventricular arrhythmias linked to SCD. Here, we investigated the efficacy of remote ischemic preconditioning (RIPC) of the limb versus the liver in reducing ventricular arrhythmias in a mouse model of SCD. Mice lacking the Kcne2 gene, which encodes a potassium channel β subunit associated with acquired Long QT syndrome were exposed to IR injury via coronary ligation. This resulted in ventricular arrhythmias in all mice (15/15) and SCD in 5/15 mice during reperfusion. Strikingly, prior RIPC (limb or liver) greatly reduced the incidence and severity of all ventricular arrhythmias and completely prevented SCD. Biochemical and pharmacological analysis demonstrated that RIPC cardioprotection required ERK1/2 and/or AKT phosphorylation. A lack of alteration in GSK‐3β phosphorylation suggested against conventional reperfusion injury salvage kinase (RISK) signaling pathway protection. If replicated in human studies, limb RIPC could represent a noninvasive, nonpharmacological approach to limit dangerous ventricular arrhythmias associated with ischemia and/or channelopathy‐linked SCD.
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Affiliation(s)
- Zhaoyang Hu
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jin Liu
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Leng Zhou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xin Tian
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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13
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Oliveras A, Serrano-Novillo C, Moreno C, de la Cruz A, Valenzuela C, Soeller C, Comes N, Felipe A. The unconventional biogenesis of Kv7.1-KCNE1 complexes. SCIENCE ADVANCES 2020; 6:eaay4472. [PMID: 32270035 PMCID: PMC7112945 DOI: 10.1126/sciadv.aay4472] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 01/09/2020] [Indexed: 06/11/2023]
Abstract
The potassium channel Kv7.1 associates with the KCNE1 regulatory subunit to trigger cardiac I Ks currents. Although the Kv7.1/KCNE1 complex has received much attention, the subcellular compartment hosting the assembly is the subject of ongoing debate. Evidence suggests that the complex forms either earlier in the endoplasmic reticulum or directly at the plasma membrane. Kv7.1 and KCNE1 mutations, responsible for long QT syndromes, impair association and traffic, thereby altering I Ks currents. We found that Kv7.1 and KCNE1 do not assemble in the first stages of their biogenesis. Data support an unconventional secretory pathway for Kv7.1-KCNE1 that bypasses Golgi. This route targets channels to endoplasmic reticulum-plasma membrane junctions, where Kv7.1-KCNE1 assemble. This mechanism helps to resolve the ongoing controversy about the subcellular compartment hosting the association. Our results also provide new insights into I Ks channel localization at endoplasmic reticulum-plasma membrane junctions, highlighting an alternative anterograde trafficking mechanism for oligomeric ion channels.
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Affiliation(s)
- Anna Oliveras
- Molecular Physiology Laboratory, Departamento de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Departamento de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Cristina Moreno
- National Institute of Neurological Disorders and Stroke (NIH), Bethesda, MD, USA
| | - Alicia de la Cruz
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid, Spain
| | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid, Spain
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Christian Soeller
- Living Systems Institute and Biomedical Physics, University of Exeter, Exeter, UK
| | - Núria Comes
- Departamento De Biomedicina, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departamento de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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14
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Kang SK, Vanoye CG, Misra SN, Echevarria DM, Calhoun JD, O'Connor JB, Fabre KL, McKnight D, Demmer L, Goldenberg P, Grote LE, Thiffault I, Saunders C, Strauss KA, Torkamani A, van der Smagt J, van Gassen K, Carson RP, Diaz J, Leon E, Jacher JE, Hannibal MC, Litwin J, Friedman NR, Schreiber A, Lynch B, Poduri A, Marsh ED, Goldberg EM, Millichap JJ, George AL, Kearney JA. Spectrum of K V 2.1 Dysfunction in KCNB1-Associated Neurodevelopmental Disorders. Ann Neurol 2019; 86:899-912. [PMID: 31600826 DOI: 10.1002/ana.25607] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/16/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Pathogenic variants in KCNB1, encoding the voltage-gated potassium channel KV 2.1, are associated with developmental and epileptic encephalopathy (DEE). Previous functional studies on a limited number of KCNB1 variants indicated a range of molecular mechanisms by which variants affect channel function, including loss of voltage sensitivity, loss of ion selectivity, and reduced cell-surface expression. METHODS We evaluated a series of 17 KCNB1 variants associated with DEE or other neurodevelopmental disorders (NDDs) to rapidly ascertain channel dysfunction using high-throughput functional assays. Specifically, we investigated the biophysical properties and cell-surface expression of variant KV 2.1 channels expressed in heterologous cells using high-throughput automated electrophysiology and immunocytochemistry-flow cytometry. RESULTS Pathogenic variants exhibited diverse functional defects, including altered current density and shifts in the voltage dependence of activation and/or inactivation, as homotetramers or when coexpressed with wild-type KV 2.1. Quantification of protein expression also identified variants with reduced total KV 2.1 expression or deficient cell-surface expression. INTERPRETATION Our study establishes a platform for rapid screening of KV 2.1 functional defects caused by KCNB1 variants associated with DEE and other NDDs. This will aid in establishing KCNB1 variant pathogenicity and the mechanism of dysfunction, which will enable targeted strategies for therapeutic intervention based on molecular phenotype. ANN NEUROL 2019;86:899-912.
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Affiliation(s)
- Seok Kyu Kang
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Carlos G Vanoye
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Sunita N Misra
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Dennis M Echevarria
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jeffrey D Calhoun
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - John B O'Connor
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL
| | - Katarina L Fabre
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | | | - Laurie Demmer
- Department of Pediatrics, Atrium Health's Levine Children's Hospital, Charlotte, NC
| | - Paula Goldenberg
- Medical Genetics, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA
| | - Lauren E Grote
- Division of Clinical Genetics, Children's Mercy Hospital, Kansas City, MO.,University of Missouri-Kansas City School of Medicine, Kansas City, MO
| | - Isabelle Thiffault
- University of Missouri-Kansas City School of Medicine, Kansas City, MO.,Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO.,Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO
| | - Carol Saunders
- University of Missouri-Kansas City School of Medicine, Kansas City, MO.,Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, MO.,Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, MO
| | | | - Ali Torkamani
- Scripps Translational Science Institute and Scripps Research Institute, La Jolla, CA
| | - Jasper van der Smagt
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Koen van Gassen
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Robert P Carson
- Monroe Carell Jr Children's Hospital at Vanderbilt, Nashville, TN
| | - Jullianne Diaz
- Rare Disease Institute, Children's National Medical Center, Washington, DC
| | - Eyby Leon
- Rare Disease Institute, Children's National Medical Center, Washington, DC
| | - Joseph E Jacher
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, University of Michigan, Ann Arbor, MI
| | - Mark C Hannibal
- Division of Pediatric Genetics, Metabolism, and Genomic Medicine, University of Michigan, Ann Arbor, MI
| | - Jessica Litwin
- University of California, San Francisco Benioff Children's Hospital, San Francisco, CA
| | | | | | - Bryan Lynch
- Department of Paediatric Neurology and Clinical Neurophysiology, Children's University Hospital, Dublin, Ireland
| | - Annapurna Poduri
- Epilepsy Genetics Program, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Eric D Marsh
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Ethan M Goldberg
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA
| | - John J Millichap
- Departments of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL.,Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Alfred L George
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jennifer A Kearney
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL
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15
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Kodirov SA. Tale of tail current. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:78-97. [PMID: 31238048 DOI: 10.1016/j.pbiomolbio.2019.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023]
Abstract
The largest biomass of channel proteins is located in unicellular organisms and bacteria that have no organs. However, orchestrated bidirectional ionic currents across the cell membrane via the channels are important for the functioning of organs of organisms, and equally concern both fauna or flora. Several ion channels are activated in the course of action potentials. One of the hallmarks of voltage-dependent channels is a 'tail current' - deactivation as observed after prior and sufficient activation predominantly at more depolarized potentials e.g. for Kv while upon hyperpolarization for HCN α subunits. Tail current also reflects the timing of channel closure that is initiated upon termination of stimuli. Finally, deactivation of currents during repolarization could be a selective estimate for given channel as in case of HERG, if dedicated long and more depolarized 'tail pulse' is used. Since from a holding potential of e.g. -70 mV are often a family of outward K+ currents comprising IA and IK are simultaneously activated in native cells.
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Affiliation(s)
- Sodikdjon A Kodirov
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA; Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341, Russia; Institute of Experimental Medicine, I. P. Pavlov Department of Physiology, Russian Academy of Medical Sciences, Saint Petersburg, Russia; Laboratory of Emotions' Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
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16
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Zhou L, Köhncke C, Hu Z, Roepke TK, Abbott GW. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury. FASEB J 2019; 33:9762-9774. [PMID: 31162977 DOI: 10.1096/fj.201802519r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The KCNE2 single transmembrane-spanning voltage-gated potassium (Kv) channel β subunit is ubiquitously expressed and essential for normal function of a variety of cell types, often via regulation of the KCNQ1 Kv channel. A polymorphism upstream of KCNE2 is associated with reduced lung function in human populations, but the pulmonary consequences of KCNE2 gene disruption are unknown. Here, germline deletion of mouse Kcne2 reduced pulmonary expression of potassium channel α subunits Kcnq1 and Kcnb1 but did not alter expression of other Kcne genes. Kcne2 colocalized and coimmunoprecipitated with Kcnq1 in mouse lungs, suggesting the formation of pulmonary Kcnq1-Kcne2 potassium channel complexes. Kcne2 deletion reduced blood O2, increased CO2, increased pulmonary apoptosis, and increased inflammatory mediators TNF-α, IL-6, and leukocytes in bronchoalveolar lavage (BAL) fluids. Consistent with increased pulmonary vascular leakage, Kcne2 deletion increased plasma, BAL albumin, and the BAL:plasma albumin concentration ratio. Kcne2-/- mouse lungs exhibited baseline induction of the reperfusion injury salvage kinase pathway but were less able to respond via this pathway to imposed pulmonary ischemia/reperfusion injury (IRI). We conclude that KCNE2 regulates KCNQ1 in the lungs and is required for normal lung function and resistance to pulmonary IRI. Our data support a causal relationship between KCNE2 gene disruption and lung dysfunction.-Zhou, L., Köhncke, C., Hu, Z., Roepke, T. K., Abbott, G. W. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury.
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Affiliation(s)
- Leng Zhou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Clemens Köhncke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Clinic for Cardiology and Angiology, Charité-Berlin University of Medicine Campus Mitte, Berlin, Germany.,Clinic for Internal Medicine and Cardiology Klinikum Niederlausitz, Senftenberg, Germany
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California-Irvine, Irvine, California, USA
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17
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Reduced hybrid/complex N-glycosylation disrupts cardiac electrical signaling and calcium handling in a model of dilated cardiomyopathy. J Mol Cell Cardiol 2019; 132:13-23. [PMID: 31071333 DOI: 10.1016/j.yjmcc.2019.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/12/2019] [Accepted: 05/01/2019] [Indexed: 12/19/2022]
Abstract
Dilated cardiomyopathy (DCM) is the third most common cause of heart failure, with ~70% of DCM cases considered idiopathic. We showed recently, through genetic ablation of the MGAT1 gene, which encodes an essential glycosyltransferase (GlcNAcT1), that prevention of cardiomyocyte hybrid/complex N-glycosylation was sufficient to cause DCM that led to heart failure and early death. Our findings are consistent with increasing evidence suggesting a link between aberrant glycosylation and heart diseases of acquired and congenital etiologies. However, the mechanisms by which changes in glycosylation contribute to disease onset and progression remain largely unknown. Activity and gating of voltage-gated Na+ and K+ channels (Nav and Kv respectively) play pivotal roles in the initiation, shaping and conduction of cardiomyocyte action potentials (APs) and aberrant channel activity was shown to contribute to cardiac disease. We and others showed that glycosylation can impact Nav and Kv function; therefore, here, we investigated the effects of reduced cardiomyocyte hybrid/complex N-glycosylation on channel activity to investigate whether chronic aberrant channel function can contribute to DCM. Ventricular cardiomyocytes from MGAT1 deficient (MGAT1KO) mice display prolonged APs and pacing-induced aberrant early re-activation that can be attributed to, at least in part, a significant reduction in Kv expression and activity that worsens over time suggesting heart disease-related remodeling. MGAT1KO Nav demonstrate no change in expression or maximal conductance but show depolarizing shifts in voltage-dependent gating. Together, the changes in MGAT1KO Nav and Kv function likely contribute to observed anomalous electrocardiograms and Ca2+ handling. These findings provide insight into mechanisms by which altered glycosylation contributes to DCM through changes in Nav and Kv activity that impact conduction, Ca2+ handling and contraction. The MGAT1KO can also serve as a useful model to study the effects of aberrant electrical signaling on cardiac function and the remodeling events that can occur with heart disease progression.
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18
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David JP, Lisewski U, Crump SM, Jepps TA, Bocksteins E, Wilck N, Lossie J, Roepke TK, Schmitt N, Abbott GW. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular K V currents and predisposes to ventricular arrhythmia. FASEB J 2018; 33:2537-2552. [PMID: 30289750 DOI: 10.1096/fj.201800502r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
KCNE5 is an X-linked gene encoding KCNE5, an ancillary subunit to voltage-gated potassium (KV) channels. Human KCNE5 mutations are associated with atrial fibrillation (AF)- and Brugada syndrome (BrS)-induced cardiac arrhythmias that can arise from increased potassium current in cardiomyocytes. Seeking to establish underlying molecular mechanisms, we created and studied Kcne5 knockout ( Kcne5-/0) mice. Intracardiac ECG revealed that Kcne5 deletion caused ventricular premature beats, increased susceptibility to induction of polymorphic ventricular tachycardia (60 vs. 24% in Kcne5+/0 mice), and 10% shorter ventricular refractory period. Kcne5 deletion increased mean ventricular myocyte KV current density in the apex and also in the subpopulation of septal myocytes that lack fast transient outward current ( Ito,f). The current increases arose from an apex-specific increase in slow transient outward current-1 ( IKslow,1) (conducted by KV1.5) and Ito,f (conducted by KV4) and an increase in IKslow,2 (conducted by KV2.1) in both apex and septum. Kcne5 protein localized to the intercalated discs in ventricular myocytes, where KV2.1 was also detected in both Kcne5-/0 and Kcne5+/0 mice. In HL-1 cardiac cells and human embryonic kidney cells, KCNE5 and KV2.1 colocalized at the cell surface, but predominantly in intracellular vesicles, suggesting that Kcne5 deletion increases IK,slow2 by reducing KV2.1 intracellular sequestration. The human AF-associated mutation KCNE5-L65F negative shifted the voltage dependence of KV2.1-KCNE5 channels, increasing their maximum current density >2-fold, whereas BrS-associated KCNE5 mutations produced more subtle negative shifts in KV2.1 voltage dependence. The findings represent the first reported native role for Kcne5 and the first demonstrated Kcne regulation of KV2.1 in mouse heart. Increased KV current is a manifestation of KCNE5 disruption that is most likely common to both mouse and human hearts, providing a plausible mechanistic basis for human KCNE5-linked AF and BrS.-David, J.-P., Lisewski, U., Crump, S. M., Jepps, T. A., Bocksteins, E., Wilck, N., Lossie, J., Roepke, T. K., Schmitt, N., Abbott, G. W. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular KV currents and predisposes to ventricular arrhythmia.
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Affiliation(s)
- Jens-Peter David
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrike Lisewski
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Shawn M Crump
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
| | - Thomas A Jepps
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elke Bocksteins
- Laboratory for Molecular Biophysics, Physiology, and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Nicola Wilck
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Janine Lossie
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Torsten K Roepke
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
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19
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Abbott GW. β Subunits Control the Effects of Human Kv4.3 Potassium Channel Phosphorylation. Front Physiol 2017; 8:646. [PMID: 28919864 PMCID: PMC5585193 DOI: 10.3389/fphys.2017.00646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/16/2017] [Indexed: 11/17/2022] Open
Abstract
The transient outward K+ current, Ito, activates early in the cardiac myocyte action potential, to begin repolarization. Human Ito is generated primarily by two Kv4.3 potassium channel α subunit splice variants (Kv4.3L and Kv4.3S) that diverge only by a C-terminal, membrane-proximal, 19-residue stretch unique to Kv4.3L. Protein kinase C (PKC) phosphorylation of threonine 504 within the Kv4.3L-specific 19-residues mediates α-adrenergic inhibition of Ito in human heart. Kv4.3 is regulated in human heart by various β subunits, including cytosolic KChIP2b and transmembrane KCNEs, yet their impact on the functional effects of human Kv4.3 phosphorylation has not been reported. Here, this gap in knowledge was addressed using human Kv4.3 splice variants, T504 mutants, and human β subunits. Subunits were co-expressed in Xenopus laevis oocytes and analyzed by two-electrode voltage-clamp, using phorbol 12-myristate 13-acetate (PMA) to stimulate PKC. Unexpectedly, KChIP2b removed the inhibitory effect of PKC on Kv4.3L (but not Kv4.3L threonine phosphorylation by PKC per-se), while co-expression with KCNE2, but not KCNE4, restored PKC-dependent inhibition of Kv4.3L-KChIP2b to quantitatively resemble previously reported effects of α-adrenergic modulation of human ventricular Ito. In addition, PKC accelerated recovery from inactivation of Kv4.3L-KChIP2b channels and, interestingly, of both Kv4.3L and Kv4.3S alone. Thus, β subunits regulate the response of human Kv4.3 to PKC phosphorylation and provide a potential mechanism for modifying the response of Ito to α-adrenergic regulation in vivo.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, IrvineIrvine, CA, United States
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20
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Hu Z, Chen M, Zhang P, Liu J, Abbott GW. Remote ischemic preconditioning differentially attenuates post-ischemic cardiac arrhythmia in streptozotocin-induced diabetic versus nondiabetic rats. Cardiovasc Diabetol 2017; 16:57. [PMID: 28446231 PMCID: PMC5406986 DOI: 10.1186/s12933-017-0537-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/19/2017] [Indexed: 02/05/2023] Open
Abstract
Background Sudden cardiac death (SCD), a leading cause of global mortality, most commonly arises from a substrate of cardiac ischemia, but requires an additional trigger. Diabetes mellitus (DM) predisposes to SCD even after adjusting for other DM-linked cardiovascular pathology such as coronary artery disease. We previously showed that remote liver ischemia preconditioning (RLIPC) is highly protective against cardiac ischemia reperfusion injury (IRI) linked ventricular arrhythmias and myocardial infarction, via induction of the cardioprotective RISK pathway, and specifically, inhibitory phosphorylation of GSK-3β (Ser 9). Methods We evaluated the impact of acute streptozotocin-induced DM on coronary artery ligation IRI-linked ventricular arrhythmogenesis and RLIPC therapy in rats. Results Post-IRI arrhythmia induction was similar in nondiabetic and DM rats, but, unexpectedly, DM rats exhibited lower incidence of SCD during reperfusion (41 vs. 100%), suggesting uncontrolled hyperglycemia does not acutely predispose to SCD. RLIPC was highly effective in both nondiabetic and DM rats at reducing incidence and duration of, and increasing latency to, all classes of ventricular tachyarrhythmias. In contrast, atrioventricular block (AVB) was highly responsive to RLIPC in nondiabetic rats (incidence reduced from 72 to 18%) but unresponsive in DM rats. RISK pathway induction was similar in nondiabetic and DM rats, thus not explaining the DM-specific resistance of AVB to therapy. Conclusions Our findings uncover important acute DM-specific differences in responsiveness to remote preconditioning for ventricular tachyarrhythmias versus AVB, which may have clinical significance given that AVB is a malignant arrhythmia twofold more common in human diabetics than nondiabetics, and correlated to plasma glucose levels >10 mmol/L.
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Affiliation(s)
- Zhaoyang Hu
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
| | - Mou Chen
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ping Zhang
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jin Liu
- Laboratory of Anesthesiology & Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Pharmacology and Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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Lee SM, Baik J, Nguyen D, Nguyen V, Liu S, Hu Z, Abbott GW. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus. FASEB J 2017; 31:2674-2685. [PMID: 28280005 DOI: 10.1096/fj.201601347] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/21/2017] [Indexed: 02/05/2023]
Abstract
Type 2 diabetes mellitus (T2DM) represents a rapidly increasing threat to global public health. T2DM arises largely from obesity, poor diet, and lack of exercise, but it also involves genetic predisposition. Here we report that the KCNE2 potassium channel transmembrane regulatory subunit is expressed in human and mouse pancreatic β cells. Kcne2 deletion in mice impaired glucose tolerance as early as 5 wk of age in pups fed a Western diet, ultimately causing diabetes. In adult mice fed normal chow, skeletal muscle expression of insulin receptor β and insulin receptor substrate 1 were down-regulated 2-fold by Kcne2 deletion, characteristic of T2DM. Kcne2 deletion also caused extensive pancreatic transcriptome changes consistent with facets of T2DM, including endoplasmic reticulum stress, inflammation, and hyperproliferation. Kcne2 deletion impaired β-cell insulin secretion in vitro up to 8-fold and diminished β-cell peak outward K+ current at positive membrane potentials, but also left-shifted its voltage dependence and slowed inactivation. Interestingly, we also observed an aging-dependent reduction in β-cell outward currents in both Kcne2+/+ and Kcne2-/- mice. Our results demonstrate that KCNE2 is required for normal β-cell electrical activity and insulin secretion, and that Kcne2 deletion causes T2DM. KCNE2 may regulate multiple K+ channels in β cells, including the T2DM-linked KCNQ1 potassium channel α subunit.-Lee, S. M., Baik, J., Nguyen, D., Nguyen, V., Liu, S., Hu, Z., Abbott, G. W. Kcne2 deletion impairs insulin secretion and causes type 2 diabetes mellitus.
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Affiliation(s)
- Soo Min Lee
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Jasmine Baik
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Dara Nguyen
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Victoria Nguyen
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Shiwei Liu
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA
| | - Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California, USA;
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Kcne2 deletion causes early-onset nonalcoholic fatty liver disease via iron deficiency anemia. Sci Rep 2016; 6:23118. [PMID: 26984260 PMCID: PMC4794722 DOI: 10.1038/srep23118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/26/2016] [Indexed: 02/05/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is an increasing health problem worldwide, with genetic, epigenetic, and environmental components. Here, we describe the first example of NAFLD caused by genetic disruption of a mammalian potassium channel subunit. Mice with germline deletion of the KCNE2 potassium channel β subunit exhibited NAFLD as early as postnatal day 7. Using mouse genetics, histology, liver damage assays and transcriptomics we discovered that iron deficiency arising from KCNE2-dependent achlorhydria is a major factor in early-onset NAFLD in Kcne2(─/─) mice, while two other KCNE2-dependent defects did not initiate NAFLD. The findings uncover a novel genetic basis for NAFLD and an unexpected potential factor in human KCNE2-associated cardiovascular pathologies, including atherosclerosis.
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Altered Kv2.1 functioning promotes increased excitability in hippocampal neurons of an Alzheimer's disease mouse model. Cell Death Dis 2016; 7:e2100. [PMID: 26890139 PMCID: PMC5399189 DOI: 10.1038/cddis.2016.18] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/28/2015] [Accepted: 01/03/2016] [Indexed: 01/02/2023]
Abstract
Altered neuronal excitability is emerging as an important feature in Alzheimer's disease (AD). Kv2.1 potassium channels are important modulators of neuronal excitability and synaptic activity. We investigated Kv2.1 currents and its relation to the intrinsic synaptic activity of hippocampal neurons from 3xTg-AD (triple transgenic mouse model of Alzheimer's disease) mice, a widely employed preclinical AD model. Synaptic activity was also investigated by analyzing spontaneous [Ca2+]i spikes. Compared with wild-type (Non-Tg (non-transgenic mouse model)) cultures, 3xTg-AD neurons showed enhanced spike frequency and decreased intensity. Compared with Non-Tg cultures, 3xTg-AD hippocampal neurons revealed reduced Kv2.1-dependent Ik current densities as well as normalized conductances. 3xTg-AD cultures also exhibited an overall decrease in the number of functional Kv2.1 channels. Immunofluorescence assay revealed an increase in Kv2.1 channel oligomerization, a condition associated with blockade of channel function. In Non-Tg neurons, pharmacological blockade of Kv2.1 channels reproduced the altered pattern found in the 3xTg-AD cultures. Moreover, compared with untreated sister cultures, pharmacological inhibition of Kv2.1 in 3xTg-AD neurons did not produce any significant modification in Ik current densities. Reactive oxygen species (ROS) promote Kv2.1 oligomerization, thereby acting as negative modulator of the channel activity. Glutamate receptor activation produced higher ROS levels in hippocampal 3xTg-AD cultures compared with Non-Tg neurons. Antioxidant treatment with N-Acetyl-Cysteine was found to rescue Kv2.1-dependent currents and decreased spontaneous hyperexcitability in 3xTg-AD neurons. Analogous results regarding spontaneous synaptic activity were observed in neuronal cultures treated with the antioxidant 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). Our study indicates that AD-related mutations may promote enhanced ROS generation, oxidative-dependent oligomerization, and loss of function of Kv2.1 channels. These processes can be part on the increased neuronal excitability of these neurons. These steps may set a deleterious vicious circle that eventually helps to promote excitotoxic damage found in the AD brain.
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Liu WJ, Deng JX, Wang G, Gao KP, Lin ZX, Liu SY, Wang YH, Liu J. Manipulation of KCNE2 expression modulates action potential duration and Ito and IK in rat and mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 2015; 309:H1288-302. [PMID: 26297229 DOI: 10.1152/ajpheart.00757.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 08/19/2015] [Indexed: 11/22/2022]
Abstract
In heterologous expression systems, KCNE2 has been demonstrated to interact with multiple α-subunits of voltage-dependent cation channels and modulate their functions. However, the physiological and pathological roles of KCNE2 in cardiomyocytes are poorly understood. The present study aimed to investigate the effects of bidirectional modulation of KCNE2 expression on action potential (AP) duration (APD) and voltage-dependent K+ channels in cardiomyocytes. Adenoviral gene delivery and RNA interference were used to either increase or decrease KCNE2 expression in cultured neonatal and adult rat or neonatal mouse ventricular myocytes. Knockdown of KCNE2 prolonged APD in both neonatal and adult myocytes, whereas overexpression of KCNE2 shortened APD in neonatal but not adult myocytes. Consistent with the alterations in APD, KCNE2 knockdown decreased transient outward K+ current ( Ito) densities in neonatal and adult myocytes, whereas KCNE2 overexpression increased Ito densities in neonatal but not adult myocytes. Furthermore, KCNE2 knockdown accelerated the rates of Ito activation and inactivation, whereas KCNE2 overexpression slowed Ito gating kinetics in neonatal but not adult myocytes. Delayed rectifier K+ current densities were remarkably affected by manipulation of KCNE2 expression in mouse but not rat cardiomyocytes. Simulation of the AP of a rat ventricular myocyte with a mathematical model showed that alterations in Ito densities and gating properties can result in similar APD alterations in KCNE2 overexpression and knockdown cells. In conclusion, endogenous KCNE2 in cardiomyocytes is important in maintaining cardiac electrical stability mainly by regulating Ito and APD. Perturbation of KCNE2 expression may predispose the heart to ventricular arrhythmia by prolonging APD.
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Affiliation(s)
- Wen-juan Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Jian-xin Deng
- Department of Endocrinology, The First Affiliated Hospital of Shenzhen University, Shenzhen No. 2 People's Hospital, Shenzhen, China
| | - Gang Wang
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Kai-ping Gao
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Ze-xun Lin
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Shuai-ye Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Yong-hui Wang
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
| | - Jie Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China; and
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25
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Abbott GW. KCNE1 and KCNE3: The yin and yang of voltage-gated K(+) channel regulation. Gene 2015; 576:1-13. [PMID: 26410412 DOI: 10.1016/j.gene.2015.09.059] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 09/03/2015] [Accepted: 09/22/2015] [Indexed: 12/20/2022]
Abstract
The human KCNE gene family comprises five genes encoding single transmembrane-spanning ion channel regulatory subunits. The primary function of KCNE subunits appears to be regulation of voltage-gated potassium (Kv) channels, and the best-understood KCNE complexes are with the KCNQ1 Kv α subunit. Here, we review the often opposite effects of KCNE1 and KCNE3 on Kv channel biology, with an emphasis on regulation of KCNQ1. Slow-activating IKs channel complexes formed by KCNQ1 and KCNE1 are essential for human ventricular myocyte repolarization, while constitutively active KCNQ1-KCNE3 channels are important in the intestine. Inherited sequence variants in human KCNE1 and KCNE3 cause cardiac arrhythmias but by different mechanisms, and each is important for hearing in unique ways. Because of their contrasting effects on KCNQ1 function, KCNE1 and KCNE3 have proved invaluable tools in the mechanistic understanding of how channel gating can be manipulated, and each may also provide a window into novel insights and new therapeutic opportunities in K(+) channel pharmacology. Finally, findings from studies of Kcne1(-/-) and Kcne3(-/-) mouse lines serve to illustrate the complexity of KCNE biology and KCNE-linked disease states.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Pharmacology and Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA; 360 Medical Surge II, Dept. of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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26
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Auxiliary KCNE subunits modulate both homotetrameric Kv2.1 and heterotetrameric Kv2.1/Kv6.4 channels. Sci Rep 2015; 5:12813. [PMID: 26242757 PMCID: PMC4525287 DOI: 10.1038/srep12813] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/08/2015] [Indexed: 01/21/2023] Open
Abstract
The diversity of the voltage-gated K(+) (Kv) channel subfamily Kv2 is increased by interactions with auxiliary β-subunits and by assembly with members of the modulatory so-called silent Kv subfamilies (Kv5-Kv6 and Kv8-Kv9). However, it has not yet been investigated whether these two types of modulating subunits can associate within and modify a single channel complex simultaneously. Here, we demonstrate that the transmembrane β-subunit KCNE5 modifies the Kv2.1/Kv6.4 current extensively, whereas KCNE2 and KCNE4 only exert minor effects. Co-expression of KCNE5 with Kv2.1 and Kv6.4 did not alter the Kv2.1/Kv6.4 current density but modulated the biophysical properties significantly; KCNE5 accelerated the activation, slowed the deactivation and steepened the slope of the voltage-dependence of the Kv2.1/Kv6.4 inactivation by accelerating recovery of the closed-state inactivation. In contrast, KCNE5 reduced the current density ~2-fold without affecting the biophysical properties of Kv2.1 homotetramers. Co-localization of Kv2.1, Kv6.4 and KCNE5 was demonstrated with immunocytochemistry and formation of Kv2.1/Kv6.4/KCNE5 and Kv2.1/KCNE5 complexes was confirmed by Fluorescence Resonance Energy Transfer experiments performed in HEK293 cells. These results suggest that a triple complex consisting of Kv2.1, Kv6.4 and KCNE5 subunits can be formed. In vivo, formation of such tripartite Kv2.1/Kv6.4/KCNE5 channel complexes might contribute to tissue-specific fine-tuning of excitability.
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27
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Kitamura N, Sakamoto K, Ono T, Kimura J. THE INHIBITORY EFFECT OF PACLITAXEL ON (Kv2.1) K+ CURRENT IN H9c2 CELLS. Fukushima J Med Sci 2015; 61:47-53. [PMID: 25994081 DOI: 10.5387/fms.2014-34] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Using the whole-cell voltage clamp technique, we investigated the effect of paclitaxel, an anticancer agent which promotes microtubule formation, on K(+) current in H9c2 cells originated from rat embryonic cardiac myocytes. Paclitaxel inhibited Kv2.1 voltage-dependent K(+) current (IKur) with ultra-rapidly activating and slowly inactivating kinetics in a concentration-dependent manner. The inhibitory effect of paclitaxel on IKur was time-dependent and more marked at 200 ms after the onset than at the beginning of the depolarizing pulse. The IC50 value of paclitaxel was 1.1 µM at 200 ms. The time-dependent inhibition suggests that paclitaxel might be an open channel blocker of Kv2.1. This inhibition of Kv2.1 may be involved in the adverse effects of paclitaxel on cardiac and neuronal cells.
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Affiliation(s)
- Naoko Kitamura
- Department of Pharmacology, Fukushima Medical University, School of Medicine
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28
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Wang D, Shah KR, Um SY, Eng LS, Zhou B, Lin Y, Mitchell AA, Nicaj L, Prinz M, McDonald TV, Sampson BA, Tang Y. Cardiac channelopathy testing in 274 ethnically diverse sudden unexplained deaths. Forensic Sci Int 2014; 237:90-9. [DOI: 10.1016/j.forsciint.2014.01.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/23/2013] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
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29
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Gaber EM, Jayaprakash P, Qureshi MA, Parekh K, Oz M, Adrian TE, Howarth FC. Effects of a sucrose-enriched diet on the pattern of gene expression, contraction and Ca(2+) transport in Goto-Kakizaki type 2 diabetic rat heart. Exp Physiol 2014; 99:881-93. [PMID: 24681897 DOI: 10.1113/expphysiol.2013.077594] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus (T2DM), and cardiovascular disease is the major cause of morbidity and mortality in diabetic patients. A variety of diastolic and systolic dysfunctions have been demonstrated in type 2 diabetic heart. The consumption of sugar-sweetened beverages has been linked to rising rates of obesity, which in turn is a risk factor for development of T2DM. In this study, the effects of a sucrose-enriched diet on the pattern of gene expression, contraction and Ca(2+) transport in the Goto-Kakizaki T2DM rat heart were investigated. Genes encoding cardiac muscle proteins (Myh7, Mybpc3, Myl1, Myl3 and Mylpf), intercellular proteins (Gja4), cell membrane transport (Atp1b1), calcium channels (Cacna1c, Cacna1g and Cacnb1) and potassium channels (Kcnj11) were upregulated and genes encoding potassium channels (Kcnb1) were downregulated in GK compared with control rats. Genes encoding cardiac muscle proteins (Myh6, Mybpc3 and Tnn2), intercellular proteins (Gja1 and Gja4), intracellular Ca(2+) transport (Atp2a1 and Ryr2), cell membrane transport (Atp1a2 and Atp1b1) and potassium channel proteins (Kcnj2 and Kcnj8) were upregulated and genes encoding cardiac muscle proteins (Myh7) were downregulated in control rats fed sucrose compared with control rats. Genes encoding cardiac muscle proteins (Myh7) and potassium channel proteins (Kcnj11) were downregulated in control and GK rats fed sucrose compared with control and GK rats, respectively. The amplitude of shortening was reduced in myocytes from the control-sucrose group compared with control rats and in the GK-sucrose group compared with GK rats. The amplitude of the Ca(2+) transient was increased in myocytes from control-sucrose compared with control rats and decreased in GK-sucrose compared with GK rats. Subtle alterations in the pattern of expression of genes encoding a variety of cardiac muscle proteins are associated with changes in shortening and intracellular Ca(2+) transport in ventricular myocytes from GK T2DM and control rats fed a sucrose-enriched diet.
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Affiliation(s)
- E M Gaber
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - P Jayaprakash
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - M A Qureshi
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - K Parekh
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - M Oz
- Department of Pharmacology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - T E Adrian
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - F C Howarth
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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Abstract
Ion channels are essential for basic cellular function and for processes including sensory perception and intercellular communication in multicellular organisms. Voltage-gated potassium (Kv) channels facilitate dynamic cellular repolarization during an action potential, opening in response to membrane depolarization to facilitate K+ efflux. In both excitable and nonexcitable cells other, constitutively active, K+ channels provide a relatively constant repolarizing force to control membrane potential, ion homeostasis, and secretory processes. Of the forty known human Kv channel pore-forming α subunits that coassemble in various combinations to form the fundamental tetrameric channel pore and voltage sensor module, KCNQ1 is unique. KCNQ1 stands alone in having the capacity to form either channels that are voltage-dependent and require membrane depolarization for activation, or constitutively active channels. In mammals, KCNQ1 regulates processes including gastric acid secretion, thyroid hormone biosynthesis, salt and glucose homeostasis, and cell volume and in some species is required for rhythmic beating of the heart. In this review, the author discusses the unique functional properties, regulation, cell biology, diverse physiological roles, and involvement in human disease states of this chameleonic K+ channel.
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31
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Crump SM, Abbott GW. Arrhythmogenic KCNE gene variants: current knowledge and future challenges. Front Genet 2014; 5:3. [PMID: 24478792 PMCID: PMC3900874 DOI: 10.3389/fgene.2014.00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/04/2014] [Indexed: 11/13/2022] Open
Abstract
There are twenty-five known inherited cardiac arrhythmia susceptibility genes, all of which encode either ion channel pore-forming subunits or proteins that regulate aspects of ion channel biology such as function, trafficking, and localization. The human KCNE gene family comprises five potassium channel regulatory subunits, sequence variants in each of which are associated with cardiac arrhythmias. KCNE gene products exhibit promiscuous partnering and in some cases ubiquitous expression, hampering efforts to unequivocally correlate each gene to specific native potassium currents. Likewise, deducing the molecular etiology of cardiac arrhythmias in individuals harboring rare KCNE gene variants, or more common KCNE polymorphisms, can be challenging. In this review we provide an update on putative arrhythmia-causing KCNE gene variants, and discuss current thinking and future challenges in the study of molecular mechanisms of KCNE-associated cardiac rhythm disturbances.
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Affiliation(s)
- Shawn M Crump
- Bioelectricity Laboratory, Department of Pharmacology, Department of Physiology and Biophysics, School of Medicine, University of California Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology, Department of Physiology and Biophysics, School of Medicine, University of California Irvine, CA, USA
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DIFRANCESCO DARIO, NAWATHE POOJAA, ROBINSON RICHARDB. Multifactorial Impact of Channel Beta-Subunit Gene Mutation on Automaticity. J Cardiovasc Electrophysiol 2013; 24:E26-7. [DOI: 10.1111/jce.12235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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33
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013. [DOI: 10.1016/j.exer.2013.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013; 116:424-432. [PMID: 24416770 PMCID: PMC3934573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this β-subunit may contribute to M-type K(+) channels in this membrane.
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Affiliation(s)
- Xiaoming Zhang
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
| | - Bret A. Hughes
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
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35
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Sachse CC, Kim YH, Agsten M, Huth T, Alzheimer C, Kovacs DM, Kim DY. BACE1 and presenilin/γ-secretase regulate proteolytic processing of KCNE1 and 2, auxiliary subunits of voltage-gated potassium channels. FASEB J 2013; 27:2458-67. [PMID: 23504710 DOI: 10.1096/fj.12-214056] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACE1 and presenilin (PS)/γ-secretase play a major role in Alzheimer's disease pathogenesis by regulating amyloid-β peptide generation. We recently showed that these secretases also regulate the processing of voltage-gated sodium channel auxiliary β-subunits and thereby modulate membrane excitability. Here, we report that KCNE1 and KCNE2, auxiliary subunits of voltage-gated potassium channels, undergo sequential cleavage mediated by either α-secretase and PS/γ-secretase or BACE1 and PS/γ-secretase in cells. Elevated α-secretase or BACE1 activities increased C-terminal fragment (CTF) levels of KCNE1 and 2 in human embryonic kidney (HEK293T) and rat neuroblastoma (B104) cells. KCNE-CTFs were then further processed by PS/γ-secretase to KCNE intracellular domains. These KCNE cleavages were specifically blocked by chemical inhibitors of the secretases in the same cell models. We also verified our results in mouse cardiomyocytes and cultured primary neurons. Endogenous KCNE1- and KCNE2-CTF levels increased by 2- to 4-fold on PS/γ-secretase inhibition or BACE1 overexpression in these cells. Furthermore, the elevated BACE1 activity increased KCNE1 processing and shifted KCNE1/KCNQ1 channel activation curve to more positive potentials in HEK cells. KCNE1/KCNQ1 channel is a cardiac potassium channel complex, and the positive shift would lead to a decrease in membrane repolarization during cardiac action potential. Together, these results clearly showed that KCNE1 and KCNE2 cleavages are regulated by BACE1 and PS/γ-secretase activities under physiological conditions. Our results also suggest a functional role of KCNE cleavage in regulating voltage-gated potassium channels.
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Affiliation(s)
- Carolyn C Sachse
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Abbott GW. KCNE genetics and pharmacogenomics in cardiac arrhythmias: much ado about nothing? Expert Rev Clin Pharmacol 2013; 6:49-60. [PMID: 23272793 PMCID: PMC4917007 DOI: 10.1586/ecp.12.76] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Voltage-gated ion channels respond to changes in membrane potential with conformational shifts that either facilitate or stem the movement of charged ions across the cell membrane. This controlled movement of ions is particularly important for the action potentials of excitable cells such as cardiac myocytes and therefore essential for timely beating of the heart. Inherited mutations in ion channel genes and in the genes encoding proteins that regulate them can cause lethal cardiac arrhythmias either by direct channel disruption or by altering interactions with therapeutic drugs, the best-understood example of both these scenarios being long QT syndrome (LQTS). Unsurprisingly, mutations in the genes encoding ion channel pore-forming α subunits underlie the large majority (~90%) of identified cases of inherited LQTS. Given that inherited LQTS is comparatively rare in itself (~0.04% of the US population), is pursuing study of the remaining known and unknown LQTS-associated genes subject to the law of diminishing returns? Here, with a particular focus on the KCNE family of single transmembrane domain K(+) channel ancillary subunits, the significance to cardiac pharmacogenetics of ion channel regulatory subunits is discussed.
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Affiliation(s)
- Geoffrey W Abbott
- Department of Pharmacology, Department of Physiology & Biophysics, University of California, Irvine, CA, USA.
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Vandenberg JI, Perry MD, Perrin MJ, Mann SA, Ke Y, Hill AP. hERG K+ Channels: Structure, Function, and Clinical Significance. Physiol Rev 2012; 92:1393-478. [DOI: 10.1152/physrev.00036.2011] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K+ channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.
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Affiliation(s)
- Jamie I. Vandenberg
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Matthew D. Perry
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Mark J. Perrin
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Stefan A. Mann
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Ying Ke
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Adam P. Hill
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
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Nakajo K, Nishino A, Okamura Y, Kubo Y. KCNQ1 subdomains involved in KCNE modulation revealed by an invertebrate KCNQ1 orthologue. ACTA ACUST UNITED AC 2012; 138:521-35. [PMID: 22042987 PMCID: PMC3206303 DOI: 10.1085/jgp.201110677] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
KCNQ1 channels are voltage-gated potassium channels that are widely expressed in various non-neuronal tissues, such as the heart, pancreas, and intestine. KCNE proteins are known as the auxiliary subunits for KCNQ1 channels. The effects and functions of the different KCNE proteins on KCNQ1 modulation are various; the KCNQ1–KCNE1 ion channel complex produces a slowly activating potassium channel that is crucial for heartbeat regulation, while the KCNE3 protein makes KCNQ1 channels constitutively active, which is important for K+ and Cl− transport in the intestine. The mechanisms by which KCNE proteins modulate KCNQ1 channels have long been studied and discussed; however, it is not well understood how different KCNE proteins exert considerably different effects on KCNQ1 channels. Here, we approached this point by taking advantage of the recently isolated Ci-KCNQ1, a KCNQ1 homologue from marine invertebrate Ciona intestinalis. We found that Ci-KCNQ1 alone could be expressed in Xenopus laevis oocytes and produced a voltage-dependent potassium current, but that Ci-KCNQ1 was not properly modulated by KCNE1 and totally unaffected by coexpression of KCNE3. By making chimeras of Ci-KCNQ1 and human KCNQ1, we determined several amino acid residues located in the pore region of human KCNQ1 involved in KCNE1 modulation. Interestingly, though, these amino acid residues of the pore region are not important for KCNE3 modulation, and we subsequently found that the S1 segment plays an important role in making KCNQ1 channels constitutively active by KCNE3. Our findings indicate that different KCNE proteins use different domains of KCNQ1 channels, and that may explain why different KCNE proteins give quite different outcomes by forming a complex with KCNQ1 channels.
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Affiliation(s)
- Koichi Nakajo
- Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan.
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Abstract
KCNE2, originally designated MinK-related peptide 1 (MiRP1), belongs to a five-strong family of potassium channel ancillary (β) subunits that, despite the diminutive size of the family and its members, has loomed large in the field of ion channel physiology. KCNE2 dictates K (+) channel gating, conductance, α subunit composition, trafficking and pharmacology, and also modifies functional properties of monovalent cation-nonselective HCN channels. The Kcne2 (-/-) mouse exhibits cardiac arrhythmia and hypertrophy, achlorhydria, gastric neoplasia, hypothyroidism, alopecia, stunted growth and choroid plexus epithelial dysfunction, illustrating the breadth and depth of the influence of KCNE2, mutations which are also associated with human cardiac arrhythmias. Here, the modus operandi and physiological roles of this potent regulator of membrane excitability and ion secretion are reviewed with particular emphasis on the ability of KCNE2 to shape the electrophysiological landscape of both excitable and non-excitable cells.
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Affiliation(s)
- Geoffrey W Abbott
- Departments of Pharmacology and Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA.
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The voltage-gated channel accessory protein KCNE2: multiple ion channel partners, multiple ways to long QT syndrome. Expert Rev Mol Med 2011; 13:e38. [DOI: 10.1017/s1462399411002092] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The single-pass transmembrane protein KCNE2 or MIRP1 was once thought to be the missing accessory protein that combined with hERG to fully recapitulate the cardiac repolarising current IKr. As a result of this role, it was an easy next step to associate mutations in KCNE2 to long QT syndrome, in which there is delayed repolarisation of the heart. Since that time however, KCNE2 has been shown to modify the behaviour of several other channels and currents, and its role in the heart and in the aetiology of long QT syndrome has become less clear. In this article, we review the known interactions of the KCNE2 protein and the resulting functional effects, and the effects of mutations in KCNE2 and their clinical role.
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Kanda VA, Lewis A, Xu X, Abbott GW. KCNE1 and KCNE2 provide a checkpoint governing voltage-gated potassium channel α-subunit composition. Biophys J 2011; 101:1364-75. [PMID: 21943417 DOI: 10.1016/j.bpj.2011.08.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 07/25/2011] [Accepted: 08/05/2011] [Indexed: 11/28/2022] Open
Abstract
Voltage-gated potassium (Kv) currents generated by N-type α-subunit homotetramers inactivate rapidly because an N-terminal ball domain blocks the channel pore after activation. Hence, the inactivation rate of heterotetrameric channels comprising both N-type and non-N-type (delayed rectifier) α-subunits depends upon the number of N-type α-subunits in the complex. As Kv channel inactivation and inactivation recovery rates regulate cellular excitability, the composition and expression of these heterotetrameric complexes are expected to be tightly regulated. In a companion article, we showed that the single transmembrane segment ancillary (β) subunits KCNE1 and KCNE2 suppress currents generated by homomeric Kv1.4, Kv3.3, and Kv3.4 channels, by trapping them early in the secretory pathway. Here, we show that this trapping is prevented by coassembly of the N-type α-subunits with intra-subfamily delayed rectifier α-subunits. Extra-subfamily delayed rectifier α-subunits, regardless of their capacity to interact with KCNE1 and KCNE2, cannot rescue Kv1.4 or Kv3.4 surface expression unless engineered to interact with them using N-terminal A and B domain swapping. The KCNE1/2-enforced checkpoint ensures N-type α-subunits only reach the cell surface as part of intra-subfamily mixed-α complexes, thereby governing channel composition, inactivation rate, and-by extension-cellular excitability.
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Affiliation(s)
- Vikram A Kanda
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, USA
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Ma LJ, Ohmert I, Vardanyan V. Allosteric features of KCNQ1 gating revealed by alanine scanning mutagenesis. Biophys J 2011; 100:885-94. [PMID: 21320432 DOI: 10.1016/j.bpj.2010.12.3726] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 11/29/2010] [Accepted: 12/15/2010] [Indexed: 01/10/2023] Open
Abstract
Controlled opening and closing of an ion-selective pathway in response to changes of membrane potential is a fundamental feature of voltage-gated ion channels. In recent decades, various details of this process have been revealed with unprecedented precision based on studies of prototypic potassium channels. Though current scientific efforts are focused more on a thorough description of voltage-sensor movement, much less is known about the similarities and differences of the gating mechanisms among potassium channels. Here, we describe the peculiarities of the KCNQ1 gating process in parallel comparison to Shaker. We applied alanine scanning mutagenesis to the S4-S5 linker and pore region and followed the regularities of gating perturbations in KCNQ1. We found a fractional constitutive conductance for wild-type KCNQ1. This component increased significantly in mutants with considerably leftward-shifted steady-state activation curves. In contrast to Shaker, no correlation between V(1/2) and Z parameters was observed for the voltage-dependent fraction of KCNQ1. Our experimental findings are explained by a simple allosteric gating scheme with voltage-driven and voltage-independent transitions. Allosteric features are discussed in the context of extreme gating adaptability of KCNQ1 upon interaction with KCNE β-subunits.
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Affiliation(s)
- Li-Juan Ma
- Institut für Neurale Signalverarbeitung, Zentrum für Molekulare Neurobiologie, Universität Hamburg, Hamburg, Germany
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Chen L, Lai C, Lai J, Tian C. Expression, purification, detergent screening and solution NMR backbone assignment of the human potassium channel accessory subunit MiRP1. Protein Expr Purif 2010; 76:205-10. [PMID: 21087668 DOI: 10.1016/j.pep.2010.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 10/31/2010] [Accepted: 11/03/2010] [Indexed: 10/18/2022]
Abstract
MiRP1 (MinK related protein 1) is a membrane protein in the KCNE family. It can associate with and modulate various voltage gated potassium channels. Mutations in human MiRP1 have been found to cause many congenital and acquired long QT syndromes, which are potentially life-threatening cardiac arrhythmias. Here, human MiRP1 was over-expressed in Escherichia coli, purified and eluted into different detergents. Two dimensional (1)H-(15)N correlated solution nuclear magnetic resonance (NMR) spectra of the human MiRP1 in four different detergent micelles indicated that high resolution solution NMR spectrum can be obtained for human MiRP1 in detergent lyso-myristoylphosphatidylglycerol (LMPG). Circular dichroism (CD) spectroscopy of human MiRP1 indicated a high content of alpha-helical secondary structure in LMPG. Backbone assignments of most MiRP1 residues were achieved through a series of triple resonance NMR experiments. Secondary structure analysis based on backbone chemical shifts showed several stretches of alpha-helices along the primary sequence of MiRP1 in LMPG.
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Affiliation(s)
- Liu Chen
- Hefei National Laboratory for Physical Science at Microscale and School of Life Science, University of Science and Technology of China, Hefei, Anhui, PR China
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Wu J, Shimizu W, Ding WG, Ohno S, Toyoda F, Itoh H, Zang WJ, Miyamoto Y, Kamakura S, Matsuura H, Nademanee K, Brugada J, Brugada P, Brugada R, Vatta M, Towbin JA, Antzelevitch C, Horie M. KCNE2 modulation of Kv4.3 current and its potential role in fatal rhythm disorders. Heart Rhythm 2009; 7:199-205. [PMID: 20042375 DOI: 10.1016/j.hrthm.2009.10.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Accepted: 10/07/2009] [Indexed: 11/29/2022]
Abstract
BACKGROUND The transient outward current I(to) is of critical importance in regulating myocardial electrical properties during the very early phase of the action potential. The auxiliary beta subunit KCNE2 recently was shown to modulate I(to). OBJECTIVE The purpose of this study was to examine the contributions of KCNE2 and its two published variants (M54T, I57T) to I(to). METHODS The functional interaction between Kv4.3 (alpha subunit of human I(to)) and wild-type (WT), M54T, and I57T KCNE2, expressed in a heterologous cell line, was studied using patch-clamp techniques. RESULTS Compared to expression of Kv4.3 alone, co-expression of WT KCNE2 significantly reduced peak current density, slowed the rate of inactivation, and caused a positive shift of voltage dependence of steady-state inactivation curve. These modifications rendered Kv4.3 channels more similar to native cardiac I(to). Both M54T and I57T variants significantly increased I(to) current density and slowed the inactivation rate compared with WT KCNE2. Moreover, both variants accelerated the recovery from inactivation. CONCLUSION The study results suggest that KCNE2 plays a critical role in the normal function of the native I(to) channel complex in human heart and that M54T and I57T variants lead to a gain of function of I(to), which may contribute to generating potential arrhythmogeneity and pathogenesis for inherited fatal rhythm disorders.
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Affiliation(s)
- Jie Wu
- Pharmacology Department, Medical School of Xi'an Jiaotong University. Xi'an, Shaanxi, China
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Clancy SM, Chen B, Bertaso F, Mamet J, Jegla T. KCNE1 and KCNE3 beta-subunits regulate membrane surface expression of Kv12.2 K(+) channels in vitro and form a tripartite complex in vivo. PLoS One 2009; 4:e6330. [PMID: 19623261 PMCID: PMC2710002 DOI: 10.1371/journal.pone.0006330] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 06/17/2009] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated potassium channels that activate near the neuronal resting membrane potential are important regulators of excitation in the nervous system, but their functional diversity is still not well understood. For instance, Kv12.2 (ELK2, KCNH3) channels are highly expressed in the cerebral cortex and hippocampus, and although they are most likely to contribute to resting potassium conductance, surprisingly little is known about their function or regulation. Here we demonstrate that the auxiliary MinK (KCNE1) and MiRP2 (KCNE3) proteins are important regulators of Kv12.2 channel function. Reduction of endogenous KCNE1 or KCNE3 expression by siRNA silencing, significantly increased macroscopic Kv12.2 currents in Xenopus oocytes by around 4-fold. Interestingly, an almost 9-fold increase in Kv12.2 currents was observed with the dual injection of KCNE1 and KCNE3 siRNA, suggesting an additive effect. Consistent with these findings, over-expression of KCNE1 and/or KCNE3 suppressed Kv12.2 currents. Membrane surface biotinylation assays showed that surface expression of Kv12.2 was significantly increased by KCNE1 and KCNE3 siRNA, whereas total protein expression of Kv12.2 was not affected. KCNE1 and KCNE3 siRNA shifted the voltages for half-maximal activation to more hyperpolarized voltages, indicating that KCNE1 and KCNE3 may also inhibit activation gating of Kv12.2. Native co-immunoprecipitation assays from mouse brain membranes imply that KCNE1 and KCNE3 interact with Kv12.2 simultaneously in vivo, suggesting the existence of novel KCNE1-KCNE3-Kv12.2 channel tripartite complexes. Together these data indicate that KCNE1 and KCNE3 interact directly with Kv12.2 channels to regulate channel membrane trafficking.
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Affiliation(s)
- Sinead M. Clancy
- Department of Cell Biology, Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
| | - Bihan Chen
- Department of Cell Biology, Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
| | - Federica Bertaso
- Department of Cell Biology, Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
| | - Julien Mamet
- Department of Cell Biology, Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
| | - Timothy Jegla
- Department of Cell Biology, Institute for Childhood and Neglected Diseases, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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