1
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Kebschull JM, Casoni F, Consalez GG, Goldowitz D, Hawkes R, Ruigrok TJH, Schilling K, Wingate R, Wu J, Yeung J, Uusisaari MY. Cerebellum Lecture: the Cerebellar Nuclei-Core of the Cerebellum. CEREBELLUM (LONDON, ENGLAND) 2024; 23:620-677. [PMID: 36781689 PMCID: PMC10951048 DOI: 10.1007/s12311-022-01506-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/10/2022] [Indexed: 02/15/2023]
Abstract
The cerebellum is a key player in many brain functions and a major topic of neuroscience research. However, the cerebellar nuclei (CN), the main output structures of the cerebellum, are often overlooked. This neglect is because research on the cerebellum typically focuses on the cortex and tends to treat the CN as relatively simple output nuclei conveying an inverted signal from the cerebellar cortex to the rest of the brain. In this review, by adopting a nucleocentric perspective we aim to rectify this impression. First, we describe CN anatomy and modularity and comprehensively integrate CN architecture with its highly organized but complex afferent and efferent connectivity. This is followed by a novel classification of the specific neuronal classes the CN comprise and speculate on the implications of CN structure and physiology for our understanding of adult cerebellar function. Based on this thorough review of the adult literature we provide a comprehensive overview of CN embryonic development and, by comparing cerebellar structures in various chordate clades, propose an interpretation of CN evolution. Despite their critical importance in cerebellar function, from a clinical perspective intriguingly few, if any, neurological disorders appear to primarily affect the CN. To highlight this curious anomaly, and encourage future nucleocentric interpretations, we build on our review to provide a brief overview of the various syndromes in which the CN are currently implicated. Finally, we summarize the specific perspectives that a nucleocentric view of the cerebellum brings, move major outstanding issues in CN biology to the limelight, and provide a roadmap to the key questions that need to be answered in order to create a comprehensive integrated model of CN structure, function, development, and evolution.
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Affiliation(s)
- Justus M Kebschull
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA.
| | - Filippo Casoni
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - G Giacomo Consalez
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - Daniel Goldowitz
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Richard Hawkes
- Department of Cell Biology & Anatomy and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Tom J H Ruigrok
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Karl Schilling
- Department of Anatomy, Anatomy & Cell Biology, Rheinische Friedrich-Wilhelms-Universität, 53115, Bonn, Federal Republic of Germany
| | - Richard Wingate
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Joshua Wu
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Joanna Yeung
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Marylka Yoe Uusisaari
- Neuronal Rhythms in Movement Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-Son, Kunigami-Gun, Okinawa, 904-0495, Japan.
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2
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Meredith AL. BK Channelopathies and KCNMA1-Linked Disease Models. Annu Rev Physiol 2024; 86:277-300. [PMID: 37906945 DOI: 10.1146/annurev-physiol-030323-042845] [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: 11/02/2023]
Abstract
Novel KCNMA1 variants, encoding the BK K+ channel, are associated with a debilitating dyskinesia and epilepsy syndrome. Neurodevelopmental delay, cognitive disability, and brain and structural malformations are also diagnosed at lower incidence. More than half of affected individuals present with a rare negative episodic motor disorder, paroxysmal nonkinesigenic dyskinesia (PNKD3). The mechanistic relationship of PNKD3 to epilepsy and the broader spectrum of KCNMA1-associated symptomology is unknown. This review summarizes patient-associated KCNMA1 variants within the BK channel structure, functional classifications, genotype-phenotype associations, disease models, and treatment. Patient and transgenic animal data suggest delineation of gain-of-function (GOF) and loss-of-function KCNMA1 neurogenetic disease, validating two heterozygous alleles encoding GOF BK channels (D434G and N999S) as causing seizure and PNKD3. This discovery led to a variant-defined therapeutic approach for PNKD3, providing initial insight into the neurological basis. A comprehensive clinical definition of monogenic KCNMA1-linked disease and the neuronal mechanisms currently remain priorities for continued investigation.
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Affiliation(s)
- Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA;
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3
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Pissas KP, Schilling M, Korkmaz A, Tian Y, Gründer S. Melatonin alters the excitability of mouse cerebellar granule neurons by inhibiting voltage-gated sodium, potassium, and calcium channels. J Pineal Res 2024; 76:e12919. [PMID: 37794846 DOI: 10.1111/jpi.12919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 09/01/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023]
Abstract
Besides its role in the circadian rhythm, the pineal gland hormone melatonin (MLT) also possesses antiepileptogenic, antineoplastic, and cardioprotective properties, among others. The dosages necessary to elicit beneficial effects in these diseases often far surpass physiological concentrations. Although even high doses of MLT are considered to be largely harmless to humans, the possible side effects of pharmacological concentrations are so far not well investigated. In the present study, we report that pharmacological doses of MLT (3 mM) strongly altered the electrophysiological characteristics of cultured primary mouse cerebellar granule cells (CGCs). Using whole-cell patch clamp and ratiometric Ca2+ imaging, we observed that pharmacological concentrations of MLT inhibited several types of voltage-gated Na+ , K+ , and Ca2+ channels in CGCs independently of known MLT-receptors, altering the character and pattern of elicited action potentials (APs) significantly, quickly and reversibly. Specifically, MLT reduced AP frequency, afterhyperpolarization, and rheobase, whereas AP amplitude and threshold potential remained unchanged. The altered biophysical profile of the cells could constitute a possible mechanism underlying the proposed beneficial effects of MLT in brain-related disorders, such as epilepsy. On the other hand, it suggests potential adverse effects of pharmacological MLT concentrations on neurons, which should be considered when using MLT as a pharmacological compound.
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Affiliation(s)
| | - Maria Schilling
- Medical faculty, Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Ahmet Korkmaz
- Medical faculty, Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Yuemin Tian
- Medical faculty, Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Stefan Gründer
- Medical faculty, Institute of Physiology, RWTH Aachen University, Aachen, Germany
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4
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Nandi A, Chartrand T, Van Geit W, Buchin A, Yao Z, Lee SY, Wei Y, Kalmbach B, Lee B, Lein E, Berg J, Sümbül U, Koch C, Tasic B, Anastassiou CA. Single-neuron models linking electrophysiology, morphology, and transcriptomics across cortical cell types. Cell Rep 2022; 40:111176. [PMID: 35947954 PMCID: PMC9793758 DOI: 10.1016/j.celrep.2022.111176] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 01/28/2022] [Accepted: 07/18/2022] [Indexed: 12/30/2022] Open
Abstract
Which cell types constitute brain circuits is a fundamental question, but establishing the correspondence across cellular data modalities is challenging. Bio-realistic models allow probing cause-and-effect and linking seemingly disparate modalities. Here, we introduce a computational optimization workflow to generate 9,200 single-neuron models with active conductances. These models are based on 230 in vitro electrophysiological experiments followed by morphological reconstruction from the mouse visual cortex. We show that, in contrast to current belief, the generated models are robust representations of individual experiments and cortical cell types as defined via cellular electrophysiology or transcriptomics. Next, we show that differences in specific conductances predicted from the models reflect differences in gene expression supported by single-cell transcriptomics. The differences in model conductances, in turn, explain electrophysiological differences observed between the cortical subclasses. Our computational effort reconciles single-cell modalities that define cell types and enables causal relationships to be examined.
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Affiliation(s)
- Anirban Nandi
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Thomas Chartrand
- Allen Institute for Brain Science, Seattle, WA 98109, USA,These authors contributed equally
| | - Werner Van Geit
- Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Campus Biotech, Geneva 1202, Switzerland,These authors contributed equally
| | - Anatoly Buchin
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Zizhen Yao
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Soo Yeun Lee
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Yina Wei
- Allen Institute for Brain Science, Seattle, WA 98109, USA,Zhejiang Lab, Hangzhou City, Zhejiang Province 311121, China
| | - Brian Kalmbach
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Brian Lee
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Ed Lein
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Jim Berg
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Uygar Sümbül
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Christof Koch
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Bosiljka Tasic
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Costas A. Anastassiou
- Allen Institute for Brain Science, Seattle, WA 98109, USA,Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA,Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA,Center for Neural Science and Medicine, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA,Lead contact,Correspondence:
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5
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BK Channel Regulation of Afterpotentials and Burst Firing in Cerebellar Purkinje Neurons. J Neurosci 2021; 41:2854-2869. [PMID: 33593855 DOI: 10.1523/jneurosci.0192-20.2021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 01/13/2021] [Accepted: 02/05/2021] [Indexed: 11/21/2022] Open
Abstract
BK calcium-activated potassium channels have complex kinetics because they are activated by both voltage and cytoplasmic calcium. The timing of BK activation and deactivation during action potentials determines their functional role in regulating firing patterns but is difficult to predict a priori. We used action potential clamp to characterize the kinetics of voltage-dependent calcium current and BK current during action potentials in Purkinje neurons from mice of both sexes, using acutely dissociated neurons that enabled rapid voltage clamp at 37°C. With both depolarizing voltage steps and action potential waveforms, BK current was entirely dependent on calcium entry through voltage-dependent calcium channels. With voltage steps, BK current greatly outweighed the triggering calcium current, with only a brief, small net inward calcium current before Ca-activated BK current dominated the total Ca-dependent current. During action potential waveforms, although BK current activated with only a short (∼100 μs) delay after calcium current, the two currents were largely separated, with calcium current flowing during the falling phase of the action potential and most BK current flowing over several milliseconds after repolarization. Step depolarizations activated both an iberiotoxin-sensitive BK component with rapid activation and deactivation kinetics and a slower-gating iberiotoxin-resistant component. During action potential firing, however, almost all BK current came from the faster-gating iberiotoxin-sensitive channels, even during bursts of action potentials. Inhibiting BK current had little effect on action potential width or a fast afterhyperpolarization but converted a medium afterhyperpolarization to an afterdepolarization and could convert tonic firing of single action potentials to burst firing.SIGNIFICANCE STATEMENT BK calcium-activated potassium channels are widely expressed in central neurons. Altered function of BK channels is associated with epilepsy and other neuronal disorders, including cerebellar ataxia. The functional role of BK in regulating neuronal firing patterns is highly dependent on the context of other channels and varies widely among different types of neurons. Most commonly, BK channels are activated during action potentials and help produce a fast afterhyperpolarization. We find that in Purkinje neurons BK current flows primarily after the fast afterhyperpolarization and helps to prevent a later afterdepolarization from producing rapid burst firing, enabling typical regular tonic firing.
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6
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Feria Pliego JA, Pedroarena CM. Kv1 potassium channels control action potential firing of putative GABAergic deep cerebellar nuclear neurons. Sci Rep 2020; 10:6954. [PMID: 32332769 PMCID: PMC7181752 DOI: 10.1038/s41598-020-63583-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 04/01/2020] [Indexed: 12/26/2022] Open
Abstract
Low threshold voltage activated Kv1 potassium channels play key roles in regulating action potential (AP) threshold, neural excitability, and synaptic transmission. Kv1 channels are highly expressed in the cerebellum and mutations of human Kv1 genes are associated to episodic forms of ataxia (EAT-1). Besides the well-established role of Kv1 channels in controlling the cerebellar basket-Purkinje cells synapses, Kv1 channels are expressed by the deep cerebellar nuclear neurons (DCNs) where they regulate the activity of principal DCNs carrying the cerebellar output. DCNs include as well GABAergic neurons serving important functions, such as those forming the inhibitory nucleo-olivary pathway, the nucleo-cortical DCNs providing feed-back inhibition to the cerebellar cortex, and those targeting principal DCNs, but whether their function is regulated by Kv1 channels remains unclear. Here, using cerebellar slices from mature GAD67-GFP mice to identify putative GABAergic-DCNs (GAD + DCN) we show that specific Kv1 channel blockers (dendrotoxin-alpha/I/K, DTXs) hyperpolarized the threshold of somatic action potentials, increased the spontaneous firing rate and hampered evoked high frequency repetitive responses of GAD + DCNs. Moreover, DTXs induced somatic depolarization and tonic firing in previously silent, putative nucleo-cortical DCNs. These results reveal a novel role of Kv1 channels in regulating GABAergic-DCNs activity and thereby, cerebellar function at multiple levels.
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Affiliation(s)
- Jessica Abigail Feria Pliego
- Graduate School of Cellular and Molecular Neurosciences, University of Tübingen, Tübingen, Germany.,Department for Cognitive Neurology, Hertie-Institute for Clinical Brain Research, 72076, Tübingen, Germany.,Systems Neurophysiology, Werner Reichardt Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany
| | - Christine M Pedroarena
- Department for Cognitive Neurology, Hertie-Institute for Clinical Brain Research, 72076, Tübingen, Germany. .,Systems Neurophysiology, Werner Reichardt Center for Integrative Neuroscience, University of Tübingen, 72076, Tübingen, Germany.
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7
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Kaczmarek LK, Zhang Y. Kv3 Channels: Enablers of Rapid Firing, Neurotransmitter Release, and Neuronal Endurance. Physiol Rev 2017; 97:1431-1468. [PMID: 28904001 PMCID: PMC6151494 DOI: 10.1152/physrev.00002.2017] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/24/2017] [Accepted: 05/05/2017] [Indexed: 12/11/2022] Open
Abstract
The intrinsic electrical characteristics of different types of neurons are shaped by the K+ channels they express. From among the more than 70 different K+ channel genes expressed in neurons, Kv3 family voltage-dependent K+ channels are uniquely associated with the ability of certain neurons to fire action potentials and to release neurotransmitter at high rates of up to 1,000 Hz. In general, the four Kv3 channels Kv3.1-Kv3.4 share the property of activating and deactivating rapidly at potentials more positive than other channels. Each Kv3 channel gene can generate multiple protein isoforms, which contribute to the high-frequency firing of neurons such as auditory brain stem neurons, fast-spiking GABAergic interneurons, and Purkinje cells of the cerebellum, and to regulation of neurotransmitter release at the terminals of many neurons. The different Kv3 channels have unique expression patterns and biophysical properties and are regulated in different ways by protein kinases. In this review, we cover the function, localization, and modulation of Kv3 channels and describe how levels and properties of the channels are altered by changes in ongoing neuronal activity. We also cover how the protein-protein interaction of these channels with other proteins affects neuronal functions, and how mutations or abnormal regulation of Kv3 channels are associated with neurological disorders such as ataxias, epilepsies, schizophrenia, and Alzheimer's disease.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Yalan Zhang
- Departments of Pharmacology and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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8
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Yarden-Rabinowitz Y, Yarom Y. In vivo analysis of synaptic activity in cerebellar nuclei neurons unravels the efficacy of excitatory inputs. J Physiol 2017; 595:5945-5963. [PMID: 28618000 DOI: 10.1113/jp274115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 06/07/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cerebellar nuclei (CN) neurons can be classified into four groups according to their action potential (AP) waveform, corresponding to four types of neurons previously characterized. Half of the APs are generated by excitatory events, suggesting that excitatory inputs play a key role in generating CN outputs. Analysis of post-synaptic potentials reveals that the probability of excitatory inputs generating an AP is 0.1. The input from climbing fibre collaterals is characterized by a pair of synaptic potentials with a distinct interpair interval of 4.5 ms. The probability of climbing fibre collaterals initiating an AP in CN neurons is 0.15. ABSTRACT It is commonly agreed that the main function of the cerebellar system is to provide well-timed signals used for the execution of motor commands or prediction of sensory inputs. This function is manifested as a temporal sequence of spiking that should be expressed in the cerebellar nuclei (CN) projection neurons. Whether spiking activity is generated by excitation or release from inhibition is still a hotly debated issue. In an attempt to resolve this debate, we recorded intracellularly from CN neurons in anaesthetized mice and performed an analysis of synaptic activity that yielded a number of important observations. First, we demonstrate that CN neurons can be classified into four groups. Second, shape-index plots of the excitatory events suggest that they are distributed over the entire dendritic tree. Third, the rise time of excitatory events is linearly related to amplitude, suggesting that all excitatory events contribute equally to the generation of action potentials (APs). Fourth, we identified a temporal pattern of spontaneous excitatory events that represent climbing fibre inputs and confirm the results by direct stimulation and analysis on harmaline-evoked activity. Finally, we demonstrate that the probability of excitatory inputs generating an AP is 0.1 yet half of the APs are generated by excitatory events. Moreover, the probability of a presumably spontaneous climbing fibre input generating an AP is higher, reaching a mean population value of 0.15. In view of these results, the mode of synaptic integration at the level of the CN should be re-considered.
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Affiliation(s)
- Yasmin Yarden-Rabinowitz
- Department of Neurobiology, Silberman Institute of Life Sciences and Edmond & Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, 91904, Jerusalem, Israel
| | - Yosef Yarom
- Department of Neurobiology, Silberman Institute of Life Sciences and Edmond & Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, 91904, Jerusalem, Israel
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9
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Vicente PC, Kim JY, Ha J, Song M, Lee H, Kim D, Choi J, Park K. Identification and characterization of site‐specific N‐glycosylation in the potassium channel Kv3.1b. J Cell Physiol 2017; 233:549-558. [DOI: 10.1002/jcp.25915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 03/17/2017] [Indexed: 12/11/2022]
Affiliation(s)
| | - Jin Young Kim
- Biomedical Omics GroupKorea Basic Science InstituteCheongju‐si Chungcheongbuk‐doSouth Korea
| | - Jeong‐Ju Ha
- Department of Physiology, School of MedicineKyung Hee UniversitySeoulSouth Korea
| | - Min‐Young Song
- Department of Physiology, School of MedicineKyung Hee UniversitySeoulSouth Korea
- Biomedical Omics GroupKorea Basic Science InstituteCheongju‐si Chungcheongbuk‐doSouth Korea
| | - Hyun‐Kyung Lee
- Biomedical Omics GroupKorea Basic Science InstituteCheongju‐si Chungcheongbuk‐doSouth Korea
- Graduate School of Analytical Science and TechnologyChungnam National UniversityDaejeonSouth Korea
| | - Dong‐Hyun Kim
- College of PharmacyCatholic University of KoreaBucheonGyeonggi‐DoSouth Korea
| | - Jin‐Sung Choi
- College of PharmacyCatholic University of KoreaBucheonGyeonggi‐DoSouth Korea
| | - Kang‐Sik Park
- Department of Physiology, School of MedicineKyung Hee UniversitySeoulSouth Korea
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10
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Farajnia S, Meijer JH, Michel S. Photoperiod Modulates Fast Delayed Rectifier Potassium Currents in the Mammalian Circadian Clock. ASN Neuro 2016; 8:8/5/1759091416670778. [PMID: 27697884 PMCID: PMC5051630 DOI: 10.1177/1759091416670778] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/24/2016] [Indexed: 11/15/2022] Open
Abstract
One feature of the mammalian circadian clock, situated in the suprachiasmatic nucleus (SCN), is its ability to measure day length and thereby contribute to the seasonal adaptation of physiology and behavior. The timing signal from the SCN, namely the 24 hr pattern of electrical activity, is adjusted according to the photoperiod being broader in long days and narrower in short days. Vasoactive intestinal peptide and gamma-aminobutyric acid play a crucial role in intercellular communication within the SCN and contribute to the seasonal changes in phase distribution. However, little is known about the underlying ionic mechanisms of synchronization. The present study was aimed to identify cellular mechanisms involved in seasonal encoding by the SCN. Mice were adapted to long-day (light–dark 16:8) and short-day (light–dark 8:16) photoperiods and membrane properties as well as K+ currents activity of SCN neurons were measured using patch-clamp recordings in acute slices. Remarkably, we found evidence for a photoperiodic effect on the fast delayed rectifier K+ current, that is, the circadian modulation of this ion channel’s activation reversed in long days resulting in 50% higher peak values during the night compared with the unaltered day values. Consistent with fast delayed rectifier enhancement, duration of action potentials during the night was shortened and afterhyperpolarization potentials increased in amplitude and duration. The slow delayed rectifier, transient K+ currents, and membrane excitability were not affected by photoperiod. We conclude that photoperiod can change intrinsic ion channel properties of the SCN neurons, which may influence cellular communication and contribute to photoperiodic phase adjustment.
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Affiliation(s)
- Sahar Farajnia
- Leiden University Medical Center, Leiden, The Netherlands Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | | | - Stephan Michel
- Leiden University Medical Center, Leiden, The Netherlands
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11
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Abstract
This review attempts to give a concise and up-to-date overview on the role of potassium channels in epilepsies. Their role can be defined from a genetic perspective, focusing on variants and de novo mutations identified in genetic studies or animal models with targeted, specific mutations in genes coding for a member of the large potassium channel family. In these genetic studies, a demonstrated functional link to hyperexcitability often remains elusive. However, their role can also be defined from a functional perspective, based on dynamic, aggravating, or adaptive transcriptional and posttranslational alterations. In these cases, it often remains elusive whether the alteration is causal or merely incidental. With ∼80 potassium channel types, of which ∼10% are known to be associated with epilepsies (in humans) or a seizure phenotype (in animals), if genetically mutated, a comprehensive review is a challenging endeavor. This goal may seem all the more ambitious once the data on posttranslational alterations, found both in human tissue from epilepsy patients and in chronic or acute animal models, are included. We therefore summarize the literature, and expand only on key findings, particularly regarding functional alterations found in patient brain tissue and chronic animal models.
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Affiliation(s)
- Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
| | - Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
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12
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Rosato-Siri MD, Zambello E, Mutinelli C, Garbati N, Benedetti R, Aldegheri L, Graziani F, Virginio C, Alvaro G, Large CH. A Novel Modulator of Kv3 Potassium Channels Regulates the Firing of Parvalbumin-Positive Cortical Interneurons. J Pharmacol Exp Ther 2015; 354:251-60. [DOI: 10.1124/jpet.115.225748] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/16/2015] [Indexed: 12/19/2022] Open
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13
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Taskin B, von Schoubye NL, Sheykhzade M, Bastlund JF, Grunnet M, Jespersen T. Biophysical characterization of KV3.1 potassium channel activating compounds. Eur J Pharmacol 2015; 758:164-70. [PMID: 25845309 DOI: 10.1016/j.ejphar.2015.03.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 03/01/2015] [Accepted: 03/14/2015] [Indexed: 10/23/2022]
Abstract
The effect of two positive modulators, RE1 and EX15, on the voltage-gated K(+) channel Kv3.1 was investigated using the whole-cell patch-clamp technique on HEK293 cells expressing Kv3.1a. RE1 and EX15 increased the Kv3.1 currents in a concentration-dependent manner with an EC50 value of 4.5 and 1.3µM, respectively. However, high compound concentrations caused an inhibition of the Kv3.1 current. The compound-induced activation of Kv3.1 channels showed a profound hyperpolarized shift in activation kinetics. 30µM RE1 shifted V1/2 from 5.63±0.31mV to -9.71±1.00mV and 10µM EX15 induced a shift from 10.77±0.32mV to -15.11±1.57mV. The activation time constant (Tauact) was reduced for both RE1 and EX15, with RE1 being the fastest activator. The deactivation time constant (Taudeact) was also markedly reduced for both RE1 and EX15, with EX15 inducing the most prominent effect. Furthermore, subjected to depolarizing pulses at 30Hz, both compounds were showing a use-dependent effect resulting in a reduction of the compound-mediated effect. However, during these conditions, RE1- and EX15-modified current amplitudes still exceeded the control condition amplitudes by up to 200%. In summary, the present study introduces the first detailed biophysical characterization of two new Kv3.1 channel modifying compounds with different modulating properties.
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Affiliation(s)
- Bahar Taskin
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Nadia Lybøl von Schoubye
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | - Morten Grunnet
- Global Research, Synaptic Transmission, H. Lundbeck A/S, Valby, Denmark.
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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14
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Age-related changes in large-conductance calcium-activated potassium channels in mammalian circadian clock neurons. Neurobiol Aging 2015; 36:2176-83. [PMID: 25735218 DOI: 10.1016/j.neurobiolaging.2014.12.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 01/18/2023]
Abstract
Aging impairs the function of the suprachiasmatic nucleus (SCN, the central mammalian clock), leading to a decline in the circadian rhythm of many physiological processes, including sleep-wake rhythms. Recent studies have found evidence of age-related changes in the circadian regulation of potassium currents; these changes presumably lead to a decrease in the SCN's electrical rhythm amplitude. Current through large-conductance Ca(2+)-activated K(+) (BK) channels promote rhythmicity in both SCN neuronal activity and behavior. In many neuron types, changes in BK activity are correlated with changes in intracellular Ca(2+) concentration ([Ca(2+)]i). We performed patch-clamp recordings of SCN neurons in aged mice and observed that the circadian modulation of BK channel activity was lost because of a reduction in BK currents during the night. This reduced current diminished the afterhyperpolarization, depolarized the resting membrane potential, widened the action potential, and increased [Ca(2+)]i. These data suggest that reduced BK current increases [Ca(2+)]i by altering the action potential waveform, possibly contributing to the observed age-related phenotype.
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Archer NP, Wilkinson AV, Ranjit N, Wang J, Zhao H, Swann AC, Shete S. Genetic, psychosocial, and demographic factors associated with social disinhibition in Mexican-origin youth. Brain Behav 2014; 4:521-30. [PMID: 25161819 PMCID: PMC4128034 DOI: 10.1002/brb3.236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 04/21/2014] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION The genetic heritability for sensation-seeking tendencies ranges from 40 to 60%. Sensation-seeking behaviors typically manifest during adolescence and are associated with alcohol and cigarette experimentation in adolescents. Social disinhibition is an aspect of sensation-seeking that is closely tied to cigarette and alcohol experimentation. METHODS We examined the contribution of candidate genes to social disinhibition among 1132 Mexican origin youth in Houston, Texas, adjusting for established demographic and psychosocial risk factors. Saliva samples were obtained at baseline in 2005-06, and social disinhibition and other psychosocial data were obtained in 2008-09. Participants were genotyped for 672 functional and tagging SNPs potentially related to sensation-seeking, risk-taking, smoking, and alcohol use. RESULTS Six SNPs were significantly associated with social disinhibition scores, after controlling for false discovery and adjusting for population stratification and relevant demographic/psychosocial characteristics. Minor alleles for three of the SNPs (rs1998220 on OPRM1; rs9534511 on HTR2A; and rs4938056 on HTR3B) were associated with increased risk of social disinhibition, while minor alleles for the other three SNPs (rs1003921 on KCNC1; rs16116 downstream of NPY; and rs16870286 on LINC00518) exhibited a protective effect. Age, linguistic acculturation, thrill and adventure-seeking, and drug and alcohol-seeking were all significantly positively associated with increased risk of social disinhibition in a multivariable model (P < 0.001). CONCLUSIONS These results add to our knowledge of genetic risk factors for social disinhibition. Additional research is needed to verify whether these SNPs are associated with social disinhibition among youth of different ethnicities and nationalities, and to elucidate whether and how these SNPs functionally contribute to social disinhibition.
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Affiliation(s)
- Natalie P Archer
- Environmental Epidemiology and Disease Registries Section, Texas Department of State Health Services Austin, Texas
| | - Anna V Wilkinson
- Austin Regional Campus, University of Texas School of Public Health Austin, Texas
| | - Nalini Ranjit
- Austin Regional Campus, University of Texas School of Public Health Austin, Texas
| | - Jian Wang
- Department of Biostatistics, University of Texas M.D. Anderson Cancer Center Houston, Texas
| | - Hua Zhao
- Department of Epidemiology, University of Texas M.D. Anderson Cancer Center Houston, Texas
| | - Alan C Swann
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine One Baylor Plaza, BCM 350, Houston, Texas
| | - Sanjay Shete
- Department of Biostatistics, University of Texas M.D. Anderson Cancer Center Houston, Texas
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Wang D, Schreurs BG. Maturation of membrane properties of neurons in the rat deep cerebellar nuclei. Dev Neurobiol 2014; 74:1268-76. [PMID: 24931427 DOI: 10.1002/dneu.22203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/25/2014] [Accepted: 06/10/2014] [Indexed: 12/20/2022]
Abstract
Patch clamp recordings of neurons in the adult rat deep cerebellar nuclei have been limited by the availability of viable brain slices. Using a new slicing technique, this study was designed to explore the maturation of membrane properties of neurons in the deep cerebellar nuclei (DCN)-an area involved in rat eyeblink conditioning. Compared to whole-cell current-clamp recordings in DCN in rat pups at postnatal day 16 (P16) to P21, recordings from weanling rats at P22-P40 revealed a number of significant changes including an increase in the amplitude of the afterhyperpolarization (AHP)-an index of membrane excitability which has been shown to be important for eyeblink conditioning-a prolonged interval between the first and second evoked action potential, and an increase in AHP amplitude for hyperpolarization-induced rebound spikes. This is the first report of developmental changes in membrane properties of DCN which may contribute to the ontogeny of eyeblink conditioning in the rat.
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Affiliation(s)
- Desheng Wang
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia, 26506; Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia, 26505
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Feng SS, Lin R, Gauck V, Jaeger D. Gain control of synaptic response function in cerebellar nuclear neurons by a calcium-activated potassium conductance. THE CEREBELLUM 2014; 12:692-706. [PMID: 23605187 DOI: 10.1007/s12311-013-0476-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Small conductance Ca(2+)-activated potassium (SK) current provides an important modulator of excitatory synaptic transmission, which undergoes plastic regulation via multiple mechanisms. We examined whether inhibitory input processing is also dependent on SK current in the cerebellar nuclei (CN) where inhibition provides the only route of information transfer from the cerebellar cortical Purkinje cells. We employed dynamic clamping in conjunction with computer simulations to address this question. We found that SK current plays a critical role in the inhibitory synaptic control of spiking output. Specifically, regulation of SK current density resulted in a gain control of spiking output, such that low SK current promoted large output signaling for large inhibitory cell input fluctuations due to Purkinje cell synchronization. In contrast, smaller nonsynchronized Purkinje cell input fluctuations were not amplified. Regulation of SK density in the CN therefore would likely lead to important consequences for the transmission of synchronized Purkinje cell activity to the motor system.
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Affiliation(s)
- Steven Si Feng
- Department of Biology, Emory University, 1510 Clifton Rd., Atlanta, GA, 30322, USA
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Nakamura K, Shimizu T, Tanaka K, Taniuchi K, Yokotani K. Involvement of presynaptic voltage-dependent Kv3 channel in endothelin-1-induced inhibition of noradrenaline release from rat gastric sympathetic nerves. Eur J Pharmacol 2012; 694:98-103. [PMID: 22964465 DOI: 10.1016/j.ejphar.2012.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/20/2012] [Accepted: 08/20/2012] [Indexed: 11/26/2022]
Abstract
We previously reported that two types of K(+) channels, the BK type Ca(2+)-activated K(+) channel coupled with phospholipase C (PLC) and the voltage-dependent K(+) channel (Kv channel), are, respectively, involved in the prostanoid TP receptor- and muscarinic M(2) receptor-mediated inhibition of noradrenaline (NA) release from rat gastric sympathetic nerves. In the present study, therefore, we examined whether these K(+) channels are involved in endothelin-1-induced inhibition of NA release, using an isolated, vascularly perfused rat stomach. The gastric sympathetic postganglionic nerves around the left gastric artery were electrically stimulated twice at 2.5 Hz for 1 min, and endothelin-1 was added during the second stimulation. Endothelin-1 (1, 2 and 10 nM) dose-dependently inhibited gastric NA release. Endothelin-1 (2 nM)-induced inhibition of NA release was neither attenuated by PLC inhibitors [U-73122 (3 μM) and ET-18-OCH(3) (3 μM)] nor by Ca(2+)-activated K(+) channel blockers [charybdotoxin (0.1 μM) (a blocker of BK type K(+) channel) and apamin (0.3 μM) (a blocker of SK type K(+) channel)]. The endothelin-1-induced inhibitory response was also not attenuated by α-dendrotoxin (0.1 μM) (a selective inhibitor of Kv1 channel), but abolished by 4-aminopyridine (20 μM) (a selectively inhibitory dose for Kv3 channel). These results suggest the involvement of a voltage-dependent Kv3 channel in the endothelin-1-induced inhibition of NA release from the gastric sympathetic nerves in rats.
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Affiliation(s)
- Kumiko Nakamura
- Department of Pharmacology, School of Medicine, Kochi University, Nankoku, Kochi 783-8505, Japan.
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Genetic activation of BK currents in vivo generates bidirectional effects on neuronal excitability. Proc Natl Acad Sci U S A 2012; 109:18997-9002. [PMID: 23112153 DOI: 10.1073/pnas.1205573109] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Large-conductance calcium-activated potassium channels (BK) are potent negative regulators of excitability in neurons and muscle, and increasing BK current is a novel therapeutic strategy for neuro- and cardioprotection, disorders of smooth muscle hyperactivity, and several psychiatric diseases. However, in some neurons, enhanced BK current is linked with seizures and paradoxical increases in excitability, potentially complicating the clinical use of agonists. The mechanisms that switch BK influence from inhibitory to excitatory are not well defined. Here we investigate this dichotomy using a gain-of-function subunit (BK(R207Q)) to enhance BK currents. Heterologous expression of BK(R207Q) generated currents that activated at physiologically relevant voltages in lower intracellular Ca(2+), activated faster, and deactivated slower than wild-type currents. We then used BK(R207Q) expression to broadly augment endogenous BK currents in vivo, generating a transgenic mouse from a circadian clock-controlled Period1 gene fragment (Tg-BK(R207Q)). The specific impact on excitability was assessed in neurons of the suprachiasmatic nucleus (SCN) in the hypothalamus, a cell type where BK currents regulate spontaneous firing under distinct day and night conditions that are defined by different complements of ionic currents. In the SCN, Tg-BK(R207Q) expression converted the endogenous BK current to fast-activating, while maintaining similar current-voltage properties between day and night. Alteration of BK currents in Tg-BK(R207Q) SCN neurons increased firing at night but decreased firing during the day, demonstrating that BK currents generate bidirectional effects on neuronal firing under distinct conditions.
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Witter L, De Zeeuw CI, Ruigrok TJH, Hoebeek FE. The cerebellar nuclei take center stage. CEREBELLUM (LONDON, ENGLAND) 2011; 10:633-6. [PMID: 21279491 PMCID: PMC3215877 DOI: 10.1007/s12311-010-0245-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Laurens Witter
- Netherlands Institute for Neuroscience, Royal Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - Chris I. De Zeeuw
- Netherlands Institute for Neuroscience, Royal Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
- Department of Neuroscience, Ee 1202, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Tom J. H. Ruigrok
- Department of Neuroscience, Ee 1202, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Ee 1202, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
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