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Brueggemann LI, Cribbs LL, Byron KL. Heteromeric Channels Formed From Alternating Kv7.4 and Kv7.5 α-Subunits Display Biophysical, Regulatory, and Pharmacological Characteristics of Smooth Muscle M-Currents. Front Physiol 2020; 11:992. [PMID: 32903335 PMCID: PMC7434985 DOI: 10.3389/fphys.2020.00992] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 07/21/2020] [Indexed: 01/16/2023] Open
Abstract
Smooth muscle cells of the vasculature, viscera, and lungs generally express multiple α-subunits of the Kv7 voltage-gated potassium channel family, with increasing evidence that both Kv7.4 and Kv7.5 can conduct “M-currents” that are functionally important for the regulation of smooth muscle contractility. Although expression systems demonstrate that functional channels can form as homomeric tetramers of either Kv7.4 or Kv7.5 α-subunits, there is evidence that heteromeric channel complexes, containing some combination of Kv7.4 and Kv7.5 α-subunits, may represent the predominant configuration natively expressed in some arterial myocytes, such as rat mesenteric artery smooth muscle cells (MASMCs). Our previous work has suggested that Kv7.4/Kv7.5 heteromers can be distinguished from Kv7.4 or Kv7.5 homomers based on their biophysical, regulatory, and pharmacological characteristics, but it remains to be determined how Kv7.4 and Kv7.5 α-subunits combine to produce these distinct characteristics. In the present study, we constructed concatenated dimers or tetramers of Kv7.4 and Kv7.5 α-subunits and expressed them in a smooth muscle cell line to determine if a particular α-subunit configuration can exhibit the features previously reported for natively expressed Kv7 currents in MASMCs. Several unique characteristics of native smooth muscle M-currents were reproduced under conditions that constrain channel formation to a Kv7.4:Kv7.5 stoichiometry of 2:2, with alternating Kv7.4 and Kv7.5 α-subunits within a tetrameric structure. Although other subunit arrangements/combinations are not ruled out, the findings provide new insights into the oligomerization of α-subunits and the ways in which Kv7.4/Kv7.5 subunit assembly can affect smooth muscle signal transduction and pharmacological responses to Kv7 channel modulating drugs.
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Affiliation(s)
- Lyubov I Brueggemann
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Maywood, IL, United States
| | - Leanne L Cribbs
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, United States
| | - Kenneth L Byron
- Department of Molecular Pharmacology and Neuroscience, Loyola University Chicago, Maywood, IL, United States
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Lehman A, Thouta S, Mancini GMS, Naidu S, van Slegtenhorst M, McWalter K, Person R, Mwenifumbo J, Salvarinova R, Guella I, McKenzie MB, Datta A, Connolly MB, Kalkhoran SM, Poburko D, Friedman JM, Farrer MJ, Demos M, Desai S, Claydon T. Loss-of-Function and Gain-of-Function Mutations in KCNQ5 Cause Intellectual Disability or Epileptic Encephalopathy. Am J Hum Genet 2017; 101:65-74. [PMID: 28669405 PMCID: PMC5501867 DOI: 10.1016/j.ajhg.2017.05.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/24/2017] [Indexed: 01/31/2023] Open
Abstract
KCNQ5 is a highly conserved gene encoding an important channel for neuronal function; it is widely expressed in the brain and generates M-type current. Exome sequencing identified de novo heterozygous missense mutations in four probands with intellectual disability, abnormal neurological findings, and treatment-resistant epilepsy (in two of four). Comprehensive analysis of this potassium channel for the four variants expressed in frog oocytes revealed shifts in the voltage dependence of activation, including altered activation and deactivation kinetics. Specifically, both loss-of-function and gain-of-function KCNQ5 mutations, associated with increased excitability and decreased repolarization reserve, lead to pathophysiology.
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Affiliation(s)
- Anna Lehman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada.
| | - Samrat Thouta
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Sakkubai Naidu
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, MD 21211, USA
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus University Medical Center, 3000 CA Rotterdam, the Netherlands
| | | | | | - Jill Mwenifumbo
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada
| | - Ramona Salvarinova
- Division of Biochemical Diseases, Department of Pediatrics, University of British Columbia, Vancouver, BC V6H 3N1, Canada
| | - Ilaria Guella
- Centre for Applied Neurogenetics, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
| | - Marna B McKenzie
- Centre for Applied Neurogenetics, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
| | - Anita Datta
- Division of Pediatric Neurology, Department of Pediatrics, University of British Columbia, Vancouver BC, V6H 3N1, Canada
| | - Mary B Connolly
- Division of Pediatric Neurology, Department of Pediatrics, University of British Columbia, Vancouver BC, V6H 3N1, Canada
| | - Somayeh Mojard Kalkhoran
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Damon Poburko
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Jan M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada
| | - Matthew J Farrer
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada; Centre for Applied Neurogenetics, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
| | - Michelle Demos
- Division of Pediatric Neurology, Department of Pediatrics, University of British Columbia, Vancouver BC, V6H 3N1, Canada
| | - Sonal Desai
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, MD 21211, USA
| | - Thomas Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
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Li SS, Ran YJ, Zhang DD, Li SZ, Zhu D. MicroRNA-190 regulates hypoxic pulmonary vasoconstriction by targeting a voltage-gated K⁺ channel in arterial smooth muscle cells. J Cell Biochem 2014; 115:1196-205. [PMID: 24446351 DOI: 10.1002/jcb.24771] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 01/16/2014] [Indexed: 01/02/2023]
Abstract
Pulmonary arterial hypertension (PAH) is associated with sustained vasoconstriction, profound structural remodeling of vasculatures and alterations in Ca(2+) homeostasis in arterial smooth muscle cells (SMCs), while the underlying mechanisms are still elusive. By regulating the expression of proteins, microRNAs (miRNAs) are known to play an important role in cell fates including differentiation, apoptosis and proliferation, and may be involved in the development of PAH. Based on our previous study, hypoxia produced a significant increase of the miR-190 level in the pulmonary artery (PA), here, we used synthetic miR-190 to mimic the increase in hypoxic conditions and showed evidence for the effects of miR-190 on pulmonary arterial vasoconstriction and Ca(2+) influx in arterial SMCs. Synthetic miR-190 remarkably enhanced the vasoconstriction responses to phenylephrine (PE) and KCl. The voltage-gated K(+) channel subfamily member, Kcnq5, mRNA was shown to be a target for miR-190. Meanwhile, miR-190 antisense oligos can partially reverse the effects of miR-190 on PASMCs and PAs. Therefore, these results suggest that miR-190 appears to be a positive regulator of Ca(2+) influx, and plays an important role in hypoxic pulmonary vascular constriction.
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Affiliation(s)
- Shan-Shan Li
- Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, China; Department of Biopharmaceutical Key Laboratory of Heilongjiang Province, 157 Baojian Road, Nangang District, Harbin, Heilongjiang, 150081, PR China
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Caminos E, Vaquero CF, Martinez-Galan JR. Relationship between rat retinal degeneration and potassium channel KCNQ5 expression. Exp Eye Res 2014; 131:1-11. [PMID: 25499209 DOI: 10.1016/j.exer.2014.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/02/2014] [Accepted: 12/09/2014] [Indexed: 11/29/2022]
Abstract
KCNQ5/Kv7.5 is a low-threshold non-inactivating voltage-gated potassium channel preferentially targeted to excitatory endings in brain neurons. The M-type current is mediated by KCNQ5 channel subunits in monkey retinal pigment epithelium cells and in brain neurons. This study was undertaken to analyze KCNQ5 expression and the interaction signals of KCNQ5 with other proteins in normal rat retina and during photoreceptor degeneration. The KCNQ5 expression pattern was studied by immunocytochemistry and Western blot in normal rat retinas (Sprague-Dawley, SD) and P23H-1 rats as a retinitis pigmentosa model. The physical interactions of KCNQ5 with calmodulin (CaM), vesicular glutamate transporter 1 (VGluT1) and glial fibrillary acidic protein (GFAP) were analyzed by in situ proximity ligation assays and were supported by calcium recording. KCNQ5 expression was found in the plexiform layers, ganglion cell layer and basal membrane of the retinal pigment epithelium. The physical interactions among KCNQ5 and CaM, VGluT1 and GFAP changed with age and during retinal degeneration. The maximal level of KCNQ5/CaM interaction was found when photoreceptors had almost completely disappeared; the KCNQ5/VGluT1 interaction signal decreased and the KCNQ5/GFAP interaction increased in the inner retina, while degeneration progressed. The basal calcium levels in the astrocytes and neurons of P23H-1 were higher than in the control SD retinas. This study demonstrates that KCNQ5 is present in the rat retina where its activity may be moderated by CaM. Retinal degeneration progression in P23H-1 rats can be followed by an interaction between KCNQ5 with CaM in an in situ system. The relationship between KCNQ5 and VGluT1 or GFAP needs to be more cautiously interpreted.
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Affiliation(s)
- Elena Caminos
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
| | - Cecilia F Vaquero
- School of Medicine and Regional Center for Biomedical Research (CRIB), University of Castilla-La Mancha, Albacete, Spain.
| | - Juan R Martinez-Galan
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
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Caminos E, Garcia-Pino E, Juiz JM. Loss of auditory activity modifies the location of potassium channel KCNQ5 in auditory brainstem neurons. J Neurosci Res 2014; 93:604-14. [PMID: 25421809 PMCID: PMC4359677 DOI: 10.1002/jnr.23516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 09/19/2014] [Accepted: 10/17/2014] [Indexed: 12/19/2022]
Abstract
KCNQ5/Kv7.5, a low-threshold noninactivating voltage-gated potassium channel, is preferentially targeted to excitatory endings of auditory neurons in the adult rat brainstem. Endbulds of Held from auditory nerve axons on the bushy cells of the ventral cochlear nucleus (VCN) and calyces of Held around the principal neurons in the medial nucleus of the trapezoid body (MNTB) are rich in KCNQ5 immunoreactivity. We have previously shown that this synaptic distribution occurs at about the time of hearing onset. The current study tests whether this localization in excitatory endings depends on the peripheral activity carried by the auditory nerve. Auditory nerve activity was abolished by cochlear removal or intracochlear injection of tetrodotoxin (TTX). Presence of KCNQ5 was analyzed by immunocytochemistry, Western blotting, and quantitative reverse transcription polymerase chain reaction. After cochlear removal, KCNQ5 immunoreactivity was virtually undetectable at its usual location in endbulbs and calyces of Held in the anteroventral CN and in the MNTB, respectively, although it was found in cell bodies in the VCN. The results were comparable after intracochlear TTX injection, which drastically reduced KCNQ5 immunostaining in MNTB calyces and increased immunolabeling in VCN cell bodies. Endbulbs of Held in the VCN also showed diminished KCNQ5 labeling after intracochlear TTX injection. These results show that peripheral activity from auditory nerve afferents is necessary to maintain the subcellular distribution of KCNQ5 in synaptic endings of the auditory brainstem. This may contribute to adaptations in the excitability and neurotransmitter release properties of these presynaptic endings under altered input conditions. © 2014 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Elena Caminos
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain
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