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Sanguinetti MC, Seebohm G. Physiological Functions, Biophysical Properties, and Regulation of KCNQ1 (K V7.1) Potassium Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1349:335-353. [PMID: 35138621 DOI: 10.1007/978-981-16-4254-8_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
KCNQ1 (KV7.1) K+ channels are expressed in multiple tissues, including the heart, pancreas, colon, and inner ear. The gene encoding the KCNQ1 protein was discovered by a positional cloning effort to determine the genetic basis of long QT syndrome, an inherited ventricular arrhythmia that can cause sudden death. Mutations in KCNQ1 can also cause other types of arrhythmia (i.e., short QT syndrome, atrial fibrillation) and the gene may also have a role in diabetes and certain cancers. KCNQ1 α-subunits can partner with accessory β-subunits (KCNE1-KCNE5) to form K+-selective channels that have divergent biophysical properties. In the heart, KCNQ1 α-subunits coassemble with KCNE1 β-subunits to form channels that conduct IKs, a very slowly activating delayed rectifier K+ current. KV7.1 channels are highly regulated by PIP2, calmodulin, and phosphorylation, and rich pharmacology includes blockers and gating modulators. Recent biophysical studies and a cryo-EM structure of the KCNQ1-calmodulin complex have provided new insights into KV7.1 channel function, and how interactions between KCNQ1 and KCNE subunits alter the gating properties of heteromultimeric channels.
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Affiliation(s)
| | - Guiscard Seebohm
- Cellular Electrophysiology and Molecular Biology, Institute for Genetics of Heart Diseases, University Hospital Münster, Münster, Germany
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Fidzinski P, Korotkova T, Heidenreich M, Maier N, Schuetze S, Kobler O, Zuschratter W, Schmitz D, Ponomarenko A, Jentsch TJ. KCNQ5 K(+) channels control hippocampal synaptic inhibition and fast network oscillations. Nat Commun 2015; 6:6254. [PMID: 25649132 DOI: 10.1038/ncomms7254] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 01/09/2015] [Indexed: 11/09/2022] Open
Abstract
KCNQ2 (Kv7.2) and KCNQ3 (Kv7.3) K(+) channels dampen neuronal excitability and their functional impairment may lead to epilepsy. Less is known about KCNQ5 (Kv7.5), which also displays wide expression in the brain. Here we show an unexpected role of KCNQ5 in dampening synaptic inhibition and shaping network synchronization in the hippocampus. KCNQ5 localizes to the postsynaptic site of inhibitory synapses on pyramidal cells and in interneurons. Kcnq5(dn/dn) mice lacking functional KCNQ5 channels display increased excitability of different classes of interneurons, enhanced phasic and tonic inhibition, and decreased electrical shunting of inhibitory postsynaptic currents. In vivo, loss of KCNQ5 function leads to reduced fast (gamma and ripple) hippocampal oscillations, altered gamma-rhythmic discharge of pyramidal cells and impaired spatial representations. Our work demonstrates that KCNQ5 controls excitability and function of hippocampal networks through modulation of synaptic inhibition.
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Affiliation(s)
- Pawel Fidzinski
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Street 10, Berlin 13125, Germany [3] Klinik für Neurologie, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
| | - Tatiana Korotkova
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
| | - Matthias Heidenreich
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Street 10, Berlin 13125, Germany
| | - Nikolaus Maier
- Neurowissenschaftliches Forschungszentrum, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
| | - Sebastian Schuetze
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Street 10, Berlin 13125, Germany
| | - Oliver Kobler
- Leibniz-Institut für Neurobiologie (LIN), Brenneckestraße 6, Magdeburg 39118, Germany
| | - Werner Zuschratter
- Leibniz-Institut für Neurobiologie (LIN), Brenneckestraße 6, Magdeburg 39118, Germany
| | - Dietmar Schmitz
- 1] NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany [2] Neurowissenschaftliches Forschungszentrum, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany [3] Deutsches Zentrum für Neurodegenerative Erkrankungen in der Helmholtz-Gemeinschaft (DZNE), Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
| | - Alexey Ponomarenko
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
| | - Thomas J Jentsch
- 1] Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Street 10, Berlin 13125, Germany [2] Max-Delbrück-Centrum für Molekulare Medizin (MDC), Robert-Rössle-Street 10, Berlin 13125, Germany [3] NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, Berlin 10117, Germany
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Maljevic S, Lerche H. Potassium channel genes and benign familial neonatal epilepsy. PROGRESS IN BRAIN RESEARCH 2014; 213:17-53. [DOI: 10.1016/b978-0-444-63326-2.00002-8] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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K(V)7/KCNQ channels are functionally expressed in oligodendrocyte progenitor cells. PLoS One 2011; 6:e21792. [PMID: 21750731 PMCID: PMC3130044 DOI: 10.1371/journal.pone.0021792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 06/12/2011] [Indexed: 11/26/2022] Open
Abstract
Background KV7/KCNQ channels are widely expressed in neurons and they have multiple important functions, including control of excitability, spike afterpotentials, adaptation, and theta resonance. Mutations in KCNQ genes have been demonstrated to associate with human neurological pathologies. However, little is known about whether KV7/KCNQ channels are expressed in oligodendrocyte lineage cells (OLCs) and what their functions in OLCs. Methods and Findings In this study, we characterized KV7/KCNQ channels expression in rat primary cultured OLCs by RT-PCR, immunostaining and electrophysiology. KCNQ2-5 mRNAs existed in all three developmental stages of rat primary cultured OLCs. KV7/KCNQ proteins were also detected in oligodendrocyte progenitor cells (OPCs, early developmental stages of OLCs) of rat primary cultures and cortex slices. Voltage-clamp recording revealed that the IM antagonist XE991 significantly reduced KV7/KCNQ channel current (IK(Q)) in OPCs but not in differentiated oligodendrocytes. In addition, inhibition of KV7/KCNQ channels promoted OPCs motility in vitro. Conclusions These findings showed that KV7/KCNQ channels were functionally expressed in rat primary cultured OLCs and might play an important role in OPCs functioning in physiological or pathological conditions.
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Maljevic S, Wuttke TV, Seebohm G, Lerche H. KV7 channelopathies. Pflugers Arch 2010; 460:277-88. [PMID: 20401729 DOI: 10.1007/s00424-010-0831-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 01/02/2023]
Abstract
KV7 voltage-gated potassium channels, encoded by the KCNQ gene family, have caught increasing interest of the scientific community for their important physiological roles, which are emphasized by the fact that four of the five so far identified members are related to different hereditary diseases. Furthermore, these channels prove to be attractive pharmacological targets for treating diseases characterized by membrane hyperexcitability. KV7 channels are expressed in brain, heart, thyroid gland, pancreas, inner ear, muscle, stomach, and intestines. They give rise to functionally important potassium currents, reduction of which results in pathologies such as long QT syndrome, diabetes, neonatal epilepsy, neuromyotonia, or progressive deafness. Here, we summarize some key traits of KV7 channels and review how their molecular deficiencies could explain diverse disease phenotypes. We also assess the therapeutic potential of KV7 channels; in particular, how the activation of KV7 channels by the compounds retigabine and R-L3 may be useful for treatment of epilepsy or cardiac arrhythmia.
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Affiliation(s)
- Snezana Maljevic
- Department of Neurology and Epileptology, Center for Neurology, Hertie Institute for Clinical Brain Research, University Hospital Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
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Navarro-López J, Jiménez-Díaz L, Géranton SM, Ashmore JF. Electrophysiological and molecular analysis of Kv7/KCNQ potassium channels in the inferior colliculus of adult guinea pig. J Mol Neurosci 2008; 37:263-8. [PMID: 18663605 DOI: 10.1007/s12031-008-9130-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 06/24/2008] [Indexed: 11/30/2022]
Abstract
Neurons located in the inferior colliculus (IC) are on the path which processes acoustic information converging from the peripheral auditory system and to be sent through ascending pathways to superior structures. Previous in vitro recordings from early stage animals suggest that voltage-gated K channels underlie distinct neuronal discharge patterns observed in the IC. In this study, using reverse transcriptase quantitative polymerase chain reaction, we show the presence of a voltage-gated K channel family (Kv7/KCNQ) in the central nucleus of the IC (ICc) of the adult guinea pig. Whole-cell recordings from neurons in the nucleus were also made in slices from mature animals, and the action of specific openers and blockers demonstrated on the firing patterns. Our results indicate that mRNA from all members of the Kv7 family of channels are expressed in the ICc, but at different levels, and provide evidence that these channels can modulate neuronal excitability in this nucleus.
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Altered KCNQ3 Potassium Channel Function Caused by the W309R Pore-Helix Mutation Found in Human Epilepsy. J Membr Biol 2008; 222:55-63. [DOI: 10.1007/s00232-008-9097-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Accepted: 01/28/2008] [Indexed: 10/22/2022]
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Liang GH, Jin Z, Ulfendahl M, Järlebark L. Molecular analyses of KCNQ1-5 potassium channel mRNAs in rat and guinea pig inner ears: expression, cloning, and alternative splicing. Acta Otolaryngol 2006; 126:346-52. [PMID: 16608784 DOI: 10.1080/00016480500416777] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
CONCLUSION Expression of neuronal Kcnq gene family transcripts in the inner ear provides further evidence for cochlear M-type currents and for complex molecular heterogeneities of voltage-gated potassium channels composed of various KCNQ subunits and/or alternative splice variants. Furthermore, important roles in regulation of cellular excitability in the auditory system, and hearing disorders related to (hyper)excitability, e.g. tinnitus, are implied. BACKGROUND Voltage-gated potassium channels play key roles in hearing, as evidenced by deafness resulting from disruption of genes encoding, for example, KCNQ1 or KCNQ4 subunits. Other members of the Kcnq gene family (Kcnq2, 3, and 5) are the molecular correlates of M currents, which regulate neuronal excitability. The expression of the latter has not previously been thoroughly investigated in the inner ear. OBJECTIVE The aim of this study was to identify genetic correlates of M currents, previously identified in cochlear hair cells by electrophysiological methods. MATERIALS AND METHODS Expression of Kcnq genes was investigated by reverse transcription-polymerase chain reaction (RT-PCR) using subtype-specific primers with total RNA isolated from whole guinea pig or rat cochlea as template. PCR products were confirmed by direct DNA sequencing. RESULTS All members of the Kcnq family were expressed in guinea pig and rat cochlea. Cochlear expression of Kcnq2 exhibited two alternatively spliced forms, lacking exons 8, 15a, and 8, 12a, 15a, respectively. Novel molecular sequence data, e.g. guinea pig Kcnq cDNA sequences, were deposited in GenBank (AY684985-AY684990).
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Affiliation(s)
- Gui-Hua Liang
- Department of Clinical Neuroscience, Center for Hearing and Communication ResearchKarolinska Institutet Karolinska University Hospital, Stockholm, Sweden
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Abstract
Idiopathic epilepsies, which account for up to 40% of all epilepsies, are mainly caused by genetic factors. Most idiopathic epilepsies are due to oligogenic or multifactorial rather than monogenetic inheritance. Nevertheless, most of what is known today about the molecular genetics of idiopathic epilepsies has been found by analysing large families with rare monogenetic forms of the disease. For the first time, gene defects can be linked to certain epilepsies. Mutations in the CHRNA4 or CHRNB subunits of the neuronal nicotinic acetylcholine receptor lead to familial nocturnal frontal lobe epilepsy, while defects in the voltage-gated potassium channels KCNQ2 and KCNQ3 have recently been found to cause benign familial neonatal convulsions. The voltage-gated sodium channel subunits SCN1B, SCN1A and SCN2A as well as the GABRG2 subunit of the GABA(A) receptor are involved in the pathology of the newly described syndrome generalized epilepsy with febrile seizures plus. These rare monogenetic epilepsies can serve as models for further genetic analysis of the common forms of idiopathic epilepsies.
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Affiliation(s)
- Ortrud K Steinlein
- Institute of Human Genetics, Friedrich-Wilhelms-University of Bonn, Wilhelmstrasse 31, D 53111 Bonn, Germany.
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Steinlein OK. Genes and mutations in idiopathic epilepsy. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 106:139-45. [PMID: 11579434 DOI: 10.1002/ajmg.1571] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Partial or generalized idiopathic epilepsies, which account for up to 40% of all epilepsies, are characterized by a mostly benign course and no apparent etiology other than a genetic predisposition. So far, the genetic defects underlying three different idiopathic epilepsy syndromes have been identified: mutations in the CHRNA4- or CHRNB subunits of the neuronal nicotinic acetylcholine receptor are found in familial nocturnal frontal lobe epilepsy, while defects in the voltage-gated potassium channels KCNQ2 and KCNQ3 have recently been identified in benign familial neonatal convulsions. The syndrome of "generalized epilepsy with febrile seizures plus" can be caused by mutations affecting the voltage-gated sodium channel subunits SCN1B and SCN1A or the gamma 2-subunit of the GABA(A) receptor. The results of recent molecular studies contributed largely to our understanding of the etiology and pathophysiology of idiopathic epilepsies.
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MESH Headings
- Epilepsies, Partial/genetics
- Epilepsies, Partial/metabolism
- Epilepsy/genetics
- Epilepsy/metabolism
- Epilepsy, Benign Neonatal/genetics
- Epilepsy, Benign Neonatal/metabolism
- Epilepsy, Generalized/genetics
- Epilepsy, Generalized/metabolism
- Humans
- Mutation/genetics
- Point Mutation
- Potassium Channels/genetics
- Potassium Channels/metabolism
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/metabolism
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Seizures, Febrile/genetics
- Seizures, Febrile/metabolism
- Sodium Channels/genetics
- Sodium Channels/metabolism
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Affiliation(s)
- O K Steinlein
- Institute of Human Genetics, University of Bonn, Germany.
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Xiao JF, Fischer C, Steinlein OK, JianFeng X. Cloning and mutation analysis of the human potassium channel KCNQ2 gene promoter. Neuroreport 2001; 12:3733-9. [PMID: 11726784 DOI: 10.1097/00001756-200112040-00026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Benign familial neonatal convulsions (BFNC) have been previously found to be associated with mutations within the coding region of KCNQ2. We have now cloned and analyzed the promoter region of the human KCNQ2 gene. 5'-RACE identified a transcription start site (TSS) located 200 bp upstream of the ATG start codon. The TSS is located close to a repetitive region containing seven copies of a degenerate 42-mer repeat. Several different luciferase (LUC) reporter plas- mids containing fragments from the KCNQ2 5'-flanking region were constructed and expressed in NT2N and SH-SY5Y cell lines. A core promoter region was found to be located between bp 20 and bp 74 upstream of the TSS. Neither the promoter region nor the repetitive region showed any mutations in 13 index patients from unrelated BFNC families.
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Affiliation(s)
- J F Xiao
- Institute of Human Genetics, University Hospital Bonn, Wilhelmstr. 31, D-53111 Bonn, Germany
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Differential expression of kcnq2 splice variants: implications to m current function during neuronal development. J Neurosci 2001. [PMID: 11160379 DOI: 10.1523/jneurosci.21-04-01096.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The KCNQ family of K(+) channels has been implicated in several cardiac and neurological disease pathologies. KCNQ2 (Q2) is a brain-derived gene, which in association with KCNQ3 (Q3) has been shown to provide a molecular basis for the neuronal M current. We have cloned a long (Q2L) and a short (Q2S) splice variant of the human KCNQ2 gene; these variants differ in their C-terminal tail. Northern blot analysis reveals that Q2L is preferentially expressed in differentiated neurons, whereas the Q2S transcript is prominent in fetal brain, undifferentiated neuroblastoma cells, and brain tumors. Q2L, transfected into mammalian cells, produces a slowly activating, noninactivating voltage-gated K(+) current that is blocked potently by tetraethylammonium (TEA; IC(50), 0.14 mm). Q2S on the other hand produces no measurable potassium currents. Cotransfection of Q2S with either Q2L, Q3, or Q2L/Q3 heteromultimers results in attenuation of K(+) current, the suppression being most profound for Q3. Inclusion of Q2S in the heteromultimer also positively shifts the voltage dependence of current activation and alters affinity for the TEA block, suggesting that under these conditions, some Q2S subunits incorporate into functional channels on the plasma membrane. In view of the crucial role of M currents in modulating neuronal excitability, our findings provide important insight into the functional consequences of differential expression of KCNQ2 splice variants: dampened potassium conductances in the developing brain could shape firing repertoires to provide cues for proliferation rather than differentiation.
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Abstract
Humans have over 70 potassium channel genes, but only some of these have been linked to disease. In this respect, the KCNQ family of potassium channels is exceptional: mutations in four out of five KCNQ genes underlie diseases including cardiac arrhythmias, deafness and epilepsy. These disorders illustrate the different physiological functions of KCNQ channels, and provide a model for the study of the 'safety margin' that separates normal from pathological levels of channel expression. In addition, several KCNQ isoforms can associate to form heteromeric channels that underlie the M-current, an important regulator of neuronal excitability.
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Affiliation(s)
- T J Jentsch
- Zentrum für Molekulare Neurobiologie Hamburg, ZMNH, Hamburg University, Martinistrasse 85, D-20246 Hamburg, Germany.
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