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Schwarz JR, Freitag S, Pechmann Y, Hermans-Borgmeyer I, Wagner W, Hornig S, Kneussel M. Purkinje cell hyperexcitability and depressive-like behavior in mice lacking erg3 (ether-à-go-go-related gene) K + channel subunits. SCIENCE ADVANCES 2024; 10:eadn6836. [PMID: 39365861 PMCID: PMC11451553 DOI: 10.1126/sciadv.adn6836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 08/30/2024] [Indexed: 10/06/2024]
Abstract
Potassium channels stabilize the resting potential and neuronal excitability. Among them, erg (ether-à-go-go-related gene) K+ channels represent a subfamily of voltage-gated channels, consisting of erg1, erg2, and erg3 subunits; however, their subunit-specific neuronal functions in vivo are barely understood. To find erg3- and erg1-mediated functions, we generated global Kcnh7 (erg3) and conditional Kcnh2 (erg1) knockout mice. We found that erg3 channels stabilize the resting potential and dampen spontaneous activity in cerebellar Purkinje cells (PCs) and hippocampal CA1 neurons, whereas erg1 channels have suprathreshold functions. Lack of erg3 subunits induced hyperexcitability with increased action potential firing in PCs, but not in CA1 neurons. Notably, erg3 depletion caused depressive-like behavior with reduced locomotor activity, strongly decreased digging behavior, and shorter latencies to fall off a rotating wheel, while learning and memory remained unchanged. Our data show that erg K+ channels containing erg3 subunits mediate a neuronal subthreshold K+ current that plays important roles in the regulation of locomotor behavior in vivo.
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Affiliation(s)
- Jürgen R. Schwarz
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Sandra Freitag
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Yvonne Pechmann
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Core Facility Transgenic Animals, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Wolfgang Wagner
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Sönke Hornig
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Matthias Kneussel
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
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2
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Sultan ZW, Najac M, Raman IM. Control of action potential afterdepolarizations in the inferior olive by inactivating A-type currents through K V4 channels. J Physiol 2024. [PMID: 39303148 DOI: 10.1113/jp286818] [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: 05/03/2024] [Accepted: 08/07/2024] [Indexed: 09/22/2024] Open
Abstract
Neurons of the inferior olive (IO) fire action potentials with large, long-lasting afterdepolarizations (ADPs). Broader ADPs support more spikes in climbing fibre axons and evoke longer bursts of complex spikes in Purkinje cells, which affect the magnitude and sign of cerebellar synaptic plasticity. In the present study, we investigated the ionic mechanisms that regulate IO action potential waveforms by making whole-cell recordings in brainstem slices from C57BL6/J mice. IO spikes evoked from rest had ADPs of ∼30 ms. After 500-ms hyperpolarizations, however, evoked action potentials were brief (1-2 ms), lacking ADPs altogether. Because such preconditioning should maximally recruit depolarizing Ih and T-type currents and minimize repolarizing Ca-dependent currents known to shape the ADP, the rapid action potential downstroke suggested additional, dominant recovery of voltage-gated K currents at negative voltages. Under voltage clamp, outward currents evoked from -98 mV included large, voltage-gated, rapidly inactivating 'A-type' K currents. These currents had a steep availability curve with half-inactivation at -85 mV, suitable for recruitment by small hyperpolarizations. The fast decay time constant increased with depolarization, as is typical of KV4 channels. The KV4 channel blocker AmmTx3 almost eliminated inactivating currents and broadened action potentials evoked from strongly negative potentials by ∼8-fold. Optogenetic stimulation of inhibitory cerebellar nucleo-olivary terminals hyperpolarized IO cells sufficiently to abolish the ADP. The data support the idea that currents through KV4 channels control action potential waveforms in IO cells, shortening ADPs during synaptic inhibition or troughs of membrane potential oscillations, thereby controlling the number of climbing fibre action potentials that propagate to the cerebellum. KEY POINTS: Neurons in the mouse inferior olive (IO) express a large, inactivating, voltage-gated A-type K current carried by KV4 channels. IO action potentials evoked from rest have large, long afterdepolarizations that disappear with pre-spike hyperpolarizations of 5-15 mV. The steep voltage-sensitivity and rapid recovery of KV4 channels regulates the duration of the afterdepolarization over more than one order of magnitude. Factors such as synaptic inhibition are sufficient to recruit KV4 channels and eliminate afterdepolarization (ADP). By controlling the ADP, KV4 channels can set the number of climbing fibre action potentials relayed to the cerebellum and regulate plasticity implicated in motor learning.
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Affiliation(s)
- Ziyad W Sultan
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Marion Najac
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
| | - Indira M Raman
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA
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3
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Wei S, Shiwen W, Cao‐wenjing C, Huajun Y, Qun W. A randomized, double-blind, placebo-controlled, dose-escalating phase IIa trial to evaluate the safety, tolerability, efficacy, and pharmacokinetics of multiple oral doses of Pynegabine tablets as add-on therapy in patients with focal epilepsy. CNS Neurosci Ther 2024; 30:e70002. [PMID: 39252462 PMCID: PMC11386250 DOI: 10.1111/cns.70002] [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: 01/23/2024] [Revised: 07/29/2024] [Accepted: 08/06/2024] [Indexed: 09/11/2024] Open
Abstract
AIMS This study aims to investigate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine as an add-on therapy in the treatment of focal epilepsy. METHODOLOGY This is a protocol phase-IIa, randomized, double-blinded, placebo-controlled, multicenter study in patients with focal epilepsy from multiple centers in China who have been treated with at least 2 ASMs without effective control. The study involves an 8-week run-in period with stable use of previous medications. Patients are then randomized to receive either Pynegabine or a placebo. Sentinel administration is performed initially, and subsequent patients are randomized based on safety assessments. Three dose cohorts (15, 20, and 25 mg/d) are established. Efficacy is assessed through various measures, including seizure frequency, CGI score, PGI score, HAMA score, HAMD score, MoCA scale score, QOLIE-31 scale score, and 12 h-EEG score. Safety evaluations, PK blood samples, concomitant medications, and adverse events are also recorded. CONCLUSION Data from the study will be used to evaluate the safety, tolerability, efficacy, and pharmacokinetics of Pynegabine tablets as add-on therapy for focal epilepsy.
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Affiliation(s)
- Shan Wei
- Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- China National Clinical Research Center for Neurological DiseasesBeijingChina
- Beijing Institute for Brain DisordersBeijingChina
| | - Weng Shiwen
- Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- China National Clinical Research Center for Neurological DiseasesBeijingChina
- Beijing Institute for Brain DisordersBeijingChina
| | - Chang Cao‐wenjing
- Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- China National Clinical Research Center for Neurological DiseasesBeijingChina
| | - Yang Huajun
- China National Clinical Research Center for Neurological DiseasesBeijingChina
- Beijing Institute for Brain DisordersBeijingChina
- Sanbo Brain HospitalCapital Medical UniversityBeijingChina
| | - Wang Qun
- Department of Neurology, Beijing Tiantan HospitalCapital Medical UniversityBeijingChina
- China National Clinical Research Center for Neurological DiseasesBeijingChina
- Beijing Institute for Brain DisordersBeijingChina
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4
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Lou Y, Ma J, Hu Y, Yao X, Liu Y, Wu M, Jia G, Chen Y, Chai R, Xia M, Li W. Integration of Functional Human Auditory Neural Circuits Based on a 3D Carbon Nanotube System. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2309617. [PMID: 38889308 PMCID: PMC11348147 DOI: 10.1002/advs.202309617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 04/27/2024] [Indexed: 06/20/2024]
Abstract
The physiological interactions between the peripheral and central auditory systems are crucial for auditory information transmission and perception, while reliable models for auditory neural circuits are currently lacking. To address this issue, mouse and human neural pathways are generated by utilizing a carbon nanotube nanofiber system. The super-aligned pattern of the scaffold renders the axons of the bipolar and multipolar neurons extending in a parallel direction. In addition, the electrical conductivity of the scaffold maintains the electrophysiological activity of the primary mouse auditory neurons. The mouse and human primary neurons from peripheral and central auditory units in the system are then co-cultured and showed that the two kinds of neurons form synaptic connections. Moreover, neural progenitor cells of the cochlea and auditory cortex are derived from human embryos to generate region-specific organoids and these organoids are assembled in the nanofiber-combined 3D system. Using optogenetic stimulation, calcium imaging, and electrophysiological recording, it is revealed that functional synaptic connections are formed between peripheral neurons and central neurons, as evidenced by calcium spiking and postsynaptic currents. The auditory circuit model will enable the study of the auditory neural pathway and advance the search for treatment strategies for disorders of neuronal connectivity in sensorineural hearing loss.
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Affiliation(s)
- Yiyun Lou
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
| | - Jiaoyao Ma
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
| | - Yangnan Hu
- State Key Laboratory of Digital Medical EngineeringDepartment of Otolaryngology Head and Neck SurgeryZhongda HospitalSchool of Life Sciences and TechnologyAdvanced Institute for Life and HealthJiangsu Province High‐Tech Key Laboratory for Bio‐Medical ResearchSoutheast UniversityNanjing210096China
- Co‐Innovation Center of NeuroregenerationNantong UniversityNantong226001China
| | - Xiaoying Yao
- Obstetrics and Gynecology HospitalFudan UniversityShanghai200011China
| | - Yaoqian Liu
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
| | - Mingxuan Wu
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
| | - Gaogan Jia
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
| | - Yan Chen
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
- NHC Key Laboratory of Hearing MedicineFudan UniversityShanghai200031China
- The Institutes of Brain Science and the Collaborative Innovation Center for Brain ScienceFudan UniversityShanghai200032China
| | - Renjie Chai
- State Key Laboratory of Digital Medical EngineeringDepartment of Otolaryngology Head and Neck SurgeryZhongda HospitalSchool of Life Sciences and TechnologyAdvanced Institute for Life and HealthJiangsu Province High‐Tech Key Laboratory for Bio‐Medical ResearchSoutheast UniversityNanjing210096China
- Co‐Innovation Center of NeuroregenerationNantong UniversityNantong226001China
| | - Mingyu Xia
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
- NHC Key Laboratory of Hearing MedicineFudan UniversityShanghai200031China
- The Institutes of Brain Science and the Collaborative Innovation Center for Brain ScienceFudan UniversityShanghai200032China
| | - Wenyan Li
- ENT Institute and Otorhinolaryngology Department of Eye & ENT HospitalState Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceFudan UniversityShanghai200031China
- Institutes of Biomedical SciencesFudan UniversityShanghai200032China
- NHC Key Laboratory of Hearing MedicineFudan UniversityShanghai200031China
- The Institutes of Brain Science and the Collaborative Innovation Center for Brain ScienceFudan UniversityShanghai200032China
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5
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Li M, Sorensen M, Johnson MA, Ingram SL, Andresen MC, Habecker BA. Hypertension increases sympathetic neuron activity by enhancing intraganglionic cholinergic collateral connections. J Physiol 2024. [PMID: 39031543 DOI: 10.1113/jp286601] [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: 03/20/2024] [Accepted: 06/06/2024] [Indexed: 07/22/2024] Open
Abstract
Autonomic dysregulation, including sympathetic hyperactivity, is a common feature of hypertension (HT) and other cardiovascular diseases. The CNS plays a role in driving chronic sympathetic activation in disease, but several lines of evidence suggest that neuroplasticity in the periphery may also contribute. The potential contribution of postganglionic sympathetic neurons to sustained sympathetic hyperactivity is not well understood. We recently discovered that noradrenergic sympathetic neurons in the stellate ganglion (SG) have excitatory cholinergic collateral connections to other neurons within the ganglion. We hypothesize that remodelling of these neurons and increased cholinergic collateral transmission contributes to sustained sympathetic hyperactivity in cardiovascular diseases, including HT. To test that hypothesis, we examined the activity of sympathetic neurons in isolated SG under control conditions and after 1 week of HT induced by peripheral angiotensin II infusion, using whole-cell patch clamp recordings. Despite the absence of central inputs, we observed elevated spontaneous activity and synaptic transmission in sympathetic SG neurons from hypertensive mice that required generation of action potentials. Genetically disrupting cholinergic transmission in noradrenergic neurons decreased basal neuronal activity and prevented angiotensin II-mediated enhancement of activity. Similar changes in activity, driven by increased collateral transmission, were identified in cardiac projecting neurons and neurons projecting to brown adipose tissue. These changes were not driven by altered A-type K+ currents. This suggests that HT stimulates increased activity throughout the intraganglionic network of collateral connections, contributing to the sustained sympathetic hyperactivity characteristic in cardiovascular disease. KEY POINTS: Sympathetic neurons in ganglia isolated from angiotensin II-treated hypertensive mice are more active than neurons from control mice despite the absence of central activation. The enhanced activity is the result of a ganglionic network of cholinergic collaterals, rather than altered intrinsic excitability. Increased neuronal activity was observed in both cardiac neurons and brown adipose tissue-projecting neurons, which are not involved in cardiovascular homeostasis.
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Affiliation(s)
- Minghua Li
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Michelle Sorensen
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Morgan A Johnson
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Susan L Ingram
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Michael C Andresen
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Beth A Habecker
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
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Ling QH, Lou ZC, Zhang L, Jin T, Dou WT, Yang HB, Xu L. Supramolecular cage-mediated cargo transport. Chem Soc Rev 2024; 53:6042-6067. [PMID: 38770558 DOI: 10.1039/d3cs01081c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
A steady stream of material transport based on carriers and channels in living systems plays an extremely important role in normal life activities. Inspired by nature, researchers have extensively applied supramolecular cages in cargo transport because of their unique three-dimensional structures and excellent physicochemical properties. In this review, we will focus on the development of supramolecular cages as carriers and channels for cargo transport in abiotic and biological systems over the past fifteen years. In addition, we will discuss future challenges and potential applications of supramolecular cages in substance transport.
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Affiliation(s)
- Qing-Hui Ling
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
| | - Zhen-Chen Lou
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
| | - Lei Zhang
- Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433, China
| | - Tongxia Jin
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
| | - Wei-Tao Dou
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
| | - Hai-Bo Yang
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
| | - Lin Xu
- State Key Laboratory of Petroleum Molecular and Process Engineering, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Wuhu Hospital Affiliated to East China Normal University (The Second People's Hospital of Wuhu), Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200241, China.
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7
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Moribayashi T, Nakao Y, Ohtubo Y. Characteristics of A-type voltage-gated K + currents expressed on sour-sensing type III taste receptor cells in mice. Cell Tissue Res 2024; 396:353-369. [PMID: 38492001 PMCID: PMC11144136 DOI: 10.1007/s00441-024-03887-6] [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: 10/26/2023] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
Sour taste is detected by type III taste receptor cells that generate membrane depolarization with action potentials in response to HCl applied to the apical membranes. The shape of action potentials in type III cells exhibits larger afterhyperpolarization due to activation of transient A-type voltage-gated K+ currents. Although action potentials play an important role in neurotransmitter release, the electrophysiological features of A-type K+ currents in taste buds remain unclear. Here, we examined the electrophysiological properties of A-type K+ currents in mouse fungiform taste bud cells using in-situ whole-cell patch clamping. Type III cells were identified with SNAP-25 immunoreactivity and/or electrophysiological features of voltage-gated currents. Type III cells expressed A-type K+ currents which were completely inhibited by 10 mM TEA, whereas IP3R3-immunoreactive type II cells did not. The half-maximal activation and steady-state inactivation of A-type K+ currents were 17.9 ± 4.5 (n = 17) and - 11.0 ± 5.7 (n = 17) mV, respectively, which are similar to the features of Kv3.3 and Kv3.4 channels (transient and high voltage-activated K+ channels). The recovery from inactivation was well fitted with a double exponential equation; the fast and slow time constants were 6.4 ± 0.6 ms and 0.76 ± 0.26 s (n = 6), respectively. RT-PCR experiments suggest that Kv3.3 and Kv3.4 mRNAs were detected at the taste bud level, but not at single-cell levels. As the phosphorylation of Kv3.3 and Kv3.4 channels generally leads to the modulation of cell excitability, neuromodulator-mediated A-type K+ channel phosphorylation likely affects the signal transduction of taste.
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Affiliation(s)
- Takeru Moribayashi
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshiki Nakao
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan.
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8
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Stott JB, Greenwood IA. G protein βγ regulation of KCNQ-encoded voltage-dependent K channels. Front Physiol 2024; 15:1382904. [PMID: 38655029 PMCID: PMC11035767 DOI: 10.3389/fphys.2024.1382904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
The KCNQ family is comprised of five genes and the expression products form voltage-gated potassium channels (Kv7.1-7.5) that have a major impact upon cellular physiology in many cell types. Each functional Kv7 channel forms as a tetramer that often associates with proteins encoded by the KCNE gene family (KCNE1-5) and is critically reliant upon binding of phosphatidylinositol bisphosphate (PIP2) and calmodulin. Other modulators like A-kinase anchoring proteins, ubiquitin ligases and Ca-calmodulin kinase II alter Kv7 channel function and trafficking in an isoform specific manner. It has now been identified that for Kv7.4, G protein βγ subunits (Gβγ) can be added to the list of key regulators and is paramount for channel activity. This article provides an overview of this nascent field of research, highlighting themes and directions for future study.
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Affiliation(s)
| | - Iain A. Greenwood
- Vascular Biology Research Group, Institute of Molecular and Clinical Sciences, St George’s University of London, London, United Kingdom
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9
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Emmerich T, Teng Y, Ronceray N, Lopriore E, Chiesa R, Chernev A, Artemov V, Di Ventra M, Kis A, Radenovic A. Nanofluidic logic with mechano-ionic memristive switches. NATURE ELECTRONICS 2024; 7:271-278. [PMID: 38681725 PMCID: PMC11045460 DOI: 10.1038/s41928-024-01137-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 02/21/2024] [Indexed: 05/01/2024]
Abstract
Neuromorphic systems are typically based on nanoscale electronic devices, but nature relies on ions for energy-efficient information processing. Nanofluidic memristive devices could thus potentially be used to construct electrolytic computers that mimic the brain down to its basic principles of operation. Here we report a nanofluidic device that is designed for circuit-scale in-memory processing. The device, which is fabricated using a scalable process, combines single-digit nanometric confinement and large entrance asymmetry and operates on the second timescale with a conductance ratio in the range of 9 to 60. In operando optical microscopy shows that the memory capabilities are due to the reversible formation of liquid blisters that modulate the conductance of the device. We use these mechano-ionic memristive switches to assemble logic circuits composed of two interactive devices and an ohmic resistor.
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Affiliation(s)
- Theo Emmerich
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Yunfei Teng
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
- NCCR Bio-Inspired Materials, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Nathan Ronceray
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Edoardo Lopriore
- Laboratory of Nanoscale Electronics and Structures, Institute of Electrical and Microengineering & Institute of Materials Science and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Riccardo Chiesa
- Laboratory of Nanoscale Electronics and Structures, Institute of Electrical and Microengineering & Institute of Materials Science and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Andrey Chernev
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Vasily Artemov
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | | | - Andras Kis
- Laboratory of Nanoscale Electronics and Structures, Institute of Electrical and Microengineering & Institute of Materials Science and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
| | - Aleksandra Radenovic
- Laboratory of Nanoscale Biology, Institute of Bioengineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
- NCCR Bio-Inspired Materials, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
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10
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Morris PG, Taylor JD, Paton JFR, Nogaret A. Single shot detection of alterations across multiple ionic currents from assimilation of cell membrane dynamics. Sci Rep 2024; 14:6031. [PMID: 38472404 DOI: 10.1038/s41598-024-56576-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
The dysfunction of ion channels is a causative factor in a variety of neurological diseases, thereby defining the implicated channels as key drug targets. The detection of functional changes in multiple specific ionic currents currently presents a challenge, particularly when the neurological causes are either a priori unknown, or are unexpected. Traditional patch clamp electrophysiology is a powerful tool in this regard but is low throughput. Here, we introduce a single-shot method for detecting alterations amongst a range of ion channel types from subtle changes in membrane voltage in response to a short chaotically driven current clamp protocol. We used data assimilation to estimate the parameters of individual ion channels and from these we reconstructed ionic currents which exhibit significantly lower error than the parameter estimates. Such reconstructed currents thereby become sensitive predictors of functional alterations in biological ion channels. The technique correctly predicted which ionic current was altered, and by approximately how much, following pharmacological blockade of BK, SK, A-type K+ and HCN channels in hippocampal CA1 neurons. We anticipate this assay technique could aid in the detection of functional changes in specific ionic currents during drug screening, as well as in research targeting ion channel dysfunction.
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Affiliation(s)
- Paul G Morris
- Department of Physics, University of Bath, Claverton Down, Bath, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Joseph D Taylor
- Department of Physics, University of Bath, Claverton Down, Bath, UK
| | - Julian F R Paton
- Manaaki Manawa - the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Alain Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, UK.
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11
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Feng H, Clatot J, Kaneko K, Flores-Mendez M, Wengert ER, Koutcher C, Hoddeson E, Lopez E, Lee D, Arias L, Liang Q, Zhang X, Somarowthu A, Covarrubias M, Gunthorpe MJ, Large CH, Akizu N, Goldberg EM. Targeted therapy improves cellular dysfunction, ataxia, and seizure susceptibility in a model of a progressive myoclonus epilepsy. Cell Rep Med 2024; 5:101389. [PMID: 38266642 PMCID: PMC10897515 DOI: 10.1016/j.xcrm.2023.101389] [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: 02/09/2023] [Revised: 11/09/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024]
Abstract
The recurrent variant KCNC1-p.Arg320His causes progressive myoclonus epilepsy (EPM) type 7, defined by progressive myoclonus, epilepsy, and ataxia, and is without effective treatment. KCNC1 encodes the voltage-gated potassium channel subunit Kv3.1, specifically expressed in high-frequency-firing neurons. Variant subunits act via loss of function; hence, EPM7 pathogenesis may involve impaired excitability of Kv3.1-expressing neurons, while enhancing Kv3 activity could represent a viable therapeutic strategy. We generate a mouse model, Kcnc1-p.Arg320His/+, which recapitulates the core features of EPM7, including progressive ataxia and seizure susceptibility. Kv3.1-expressing cerebellar granule cells and neocortical parvalbumin-positive GABAergic interneurons exhibit abnormalities consistent with Kv3 channel dysfunction. A Kv3-specific positive modulator (AUT00206) selectively enhances the firing frequency of Kv3.1-expressing neurons and improves motor function and seizure susceptibility in Kcnc1-Arg320His/+ mice. This work identifies a cellular and circuit basis of dysfunction in EPM7 and demonstrates that Kv3 positive modulators such as AUT00206 have therapeutic potential for the treatment of EPM7.
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Affiliation(s)
- Huijie Feng
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jerome Clatot
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Keisuke Kaneko
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Anesthesiology, Nihon University, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Marco Flores-Mendez
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Eric R Wengert
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carly Koutcher
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Emily Hoddeson
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Emily Lopez
- The University of Pennsylvania School of Arts and Sciences, Philadelphia, PA, USA
| | - Demetrius Lee
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Leroy Arias
- The University of Pennsylvania School of Arts and Sciences, Philadelphia, PA, USA
| | - Qiansheng Liang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Xiaohong Zhang
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Ala Somarowthu
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Martin J Gunthorpe
- Autifony Therapeutics, Ltd., Stevenage Bioscience Catalyst, Stevenage SG1 2FX, UK
| | - Charles H Large
- Autifony Therapeutics, Ltd., Stevenage Bioscience Catalyst, Stevenage SG1 2FX, UK
| | - Naiara Akizu
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Departments of Pathology & Laboratory Medicine, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ethan M Goldberg
- Division of Neurology, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Neurology, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Neuroscience, The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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12
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Xia M, Anderson TL, Prantzalos ER, Hawkinson TR, Clarke HA, Keohane SB, Sun RC, Turner JR, Ortinski PI. Voltage-gated potassium channels control extended access cocaine seeking: a role for nucleus accumbens astrocytes. Neuropsychopharmacology 2024; 49:551-560. [PMID: 37660129 PMCID: PMC10789875 DOI: 10.1038/s41386-023-01718-w] [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: 05/22/2023] [Revised: 08/03/2023] [Accepted: 08/21/2023] [Indexed: 09/04/2023]
Abstract
Dopaminergic signaling in the nucleus accumbens shell (NAc) regulates neuronal activity relevant to reward-related learning, including cocaine-associated behaviors. Although astrocytes respond to dopamine and cocaine with structural changes, the impact of dopamine and cocaine on astrocyte functional plasticity has not been widely studied. Specifically, behavioral implications of voltage-gated channel activity in the canonically non-excitable astrocytes are not known. We characterized potassium channel function in NAc astrocytes following exposure to exogenous dopamine or cocaine self-administration training under short (2 h/day) and extended (6 h/day) access schedules. Electrophysiological, Ca2+ imaging, mRNA, and mass spectrometry tools were used for molecular characterization. Behavioral effects were examined after NAc-targeted microinjections of channel antagonists and astroglial toxins. Exogenous dopamine increased activity of currents mediated by voltage-gated (Kv7) channels in NAc astrocytes. This was associated with a ~5-fold increase in expression of Kcnq2 transcript level in homogenized NAc micropunches. Matrix-assisted laser desorption/ionization mass spectrometry revealed increased NAc dopamine levels in extended access, relative to short access, rats. Kv7 inhibition selectively increased frequency and amplitude of astrocyte intracellular Ca2+ transients in NAc of extended access rats. Inhibition of Kv7 channels in the NAc attenuated cocaine-seeking in extended access rats only, an effect that was occluded by microinjection of the astrocyte metabolic poison, fluorocitrate. These results suggest that voltage-gated K+ channel signaling in NAc astrocytes is behaviorally relevant, support Kv7-mediated regulation of astrocyte Ca2+ signals, and propose novel mechanisms of neuroglial interactions relevant to drug use.
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Affiliation(s)
- Mengfan Xia
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Tanner L Anderson
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA
| | - Emily R Prantzalos
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Tara R Hawkinson
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Harrison A Clarke
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Shannon B Keohane
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
| | - Ramon C Sun
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, FL, USA
| | - Jill R Turner
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Pavel I Ortinski
- Department of Neuroscience, University of Kentucky, Lexington, KY, USA.
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13
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Michetti C, Ferrante D, Parisi B, Ciano L, Prestigio C, Casagrande S, Martinoia S, Terranova F, Millo E, Valente P, Giovedi' S, Benfenati F, Baldelli P. Low glycemic index diet restrains epileptogenesis in a gender-specific fashion. Cell Mol Life Sci 2023; 80:356. [PMID: 37947886 PMCID: PMC10638170 DOI: 10.1007/s00018-023-04988-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 11/12/2023]
Abstract
Dietary restriction, such as low glycemic index diet (LGID), have been successfully used to treat drug-resistant epilepsy. However, if such diet could also counteract antiepileptogenesis is still unclear. Here, we investigated whether the administration of LGID during the latent pre-epileptic period, prevents or delays the appearance of the overt epileptic phenotype. To this aim, we used the Synapsin II knockout (SynIIKO) mouse, a model of temporal lobe epilepsy in which seizures manifest 2-3 months after birth, offering a temporal window in which LGID may affect epileptogenesis. Pregnant SynIIKO mice were fed with either LGID or standard diet during gestation and lactation. Both diets were maintained in weaned mice up to 5 months of age. LGID delayed the seizure onset and induced a reduction of seizures severity only in female SynIIKO mice. In parallel with the epileptic phenotype, high-density multielectrode array recordings revealed a reduction of frequency, amplitude, duration, velocity of propagation and spread of interictal events by LGID in the hippocampus of SynIIKO females, but not mutant males, confirming the gender-specific effect. ELISA-based analysis revealed that LGID increased cortico-hippocampal allopregnanolone (ALLO) levels only in females, while it was unable to affect ALLO plasma concentrations in either sex. The results indicate that the gender-specific interference of LGID with the epileptogenic process can be ascribed to a gender-specific increase in cortical ALLO, a neurosteroid known to strengthen GABAergic transmission. The study highlights the possibility of developing a personalized gender-based therapy for temporal lobe epilepsy.
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Affiliation(s)
- Caterina Michetti
- Department of Experimental Medicine, University of Genova, Genoa, Italy.
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy.
| | - Daniele Ferrante
- Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Barbara Parisi
- Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Lorenzo Ciano
- Department of Experimental Medicine, University of Genova, Genoa, Italy
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy
| | - Cosimo Prestigio
- Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Silvia Casagrande
- Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Sergio Martinoia
- Department of Informatics, Bioengineering, Robotics and System Engineering, University of Genova, Genoa, Italy
| | - Fabio Terranova
- Department of Informatics, Bioengineering, Robotics and System Engineering, University of Genova, Genoa, Italy
| | - Enrico Millo
- Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Pierluigi Valente
- Department of Experimental Medicine, University of Genova, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Silvia Giovedi'
- Department of Experimental Medicine, University of Genova, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Italian Institute of Technology, Genoa, Italy
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy
| | - Pietro Baldelli
- Department of Experimental Medicine, University of Genova, Genoa, Italy.
- IRCCS, Ospedale Policlinico San Martino, Genoa, Italy.
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14
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Alam KA, Svalastoga P, Martinez A, Glennon JC, Haavik J. Potassium channels in behavioral brain disorders. Molecular mechanisms and therapeutic potential: A narrative review. Neurosci Biobehav Rev 2023; 152:105301. [PMID: 37414376 DOI: 10.1016/j.neubiorev.2023.105301] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/26/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023]
Abstract
Potassium channels (K+-channels) selectively control the passive flow of potassium ions across biological membranes and thereby also regulate membrane excitability. Genetic variants affecting many of the human K+-channels are well known causes of Mendelian disorders within cardiology, neurology, and endocrinology. K+-channels are also primary targets of many natural toxins from poisonous organisms and drugs used within cardiology and metabolism. As genetic tools are improving and larger clinical samples are being investigated, the spectrum of clinical phenotypes implicated in K+-channels dysfunction is rapidly expanding, notably within immunology, neurosciences, and metabolism. K+-channels that previously were considered to be expressed in only a few organs and to have discrete physiological functions, have recently been found in multiple tissues and with new, unexpected functions. The pleiotropic functions and patterns of expression of K+-channels may provide additional therapeutic opportunities, along with new emerging challenges from off-target effects. Here we review the functions and therapeutic potential of K+-channels, with an emphasis on the nervous system, roles in neuropsychiatric disorders and their involvement in other organ systems and diseases.
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Affiliation(s)
| | - Pernille Svalastoga
- Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway; Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway
| | | | - Jeffrey Colm Glennon
- Conway Institute for Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland.
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Norway; Division of Psychiatry, Haukeland University Hospital, Norway.
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15
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Paul A, Chumbale SS, Lakra A, Kumar V, Alhat DS, Singh S. Insights into Leishmania donovani potassium channel family and their biological functions. 3 Biotech 2023; 13:266. [PMID: 37425093 PMCID: PMC10326225 DOI: 10.1007/s13205-023-03692-y] [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: 09/27/2022] [Accepted: 06/26/2023] [Indexed: 07/11/2023] Open
Abstract
Leishmania donovani is the causative organism for visceral leishmaniasis. Although this parasite was discovered over a century ago, nothing is known about role of potassium channels in L. donovani. Potassium channels are known for their crucial roles in cellular functions in other organisms. Recently the presence of a calcium-activated potassium channel in L. donovani was reported which prompted us to look for other proteins which could be potassium channels and to investigate their possible physiological roles. Twenty sequences were identified in L. donovani genome and subjected to estimation of physio-chemical properties, motif analysis, localization prediction and transmembrane domain analysis. Structural predictions were also done. The channels were majorly α-helical and predominantly localized in cell membrane and lysosomes. The signature selectivity filter of potassium channel was present in all the sequences. In addition to the conventional potassium channel activity, they were associated with gene ontology terms for mitotic cell cycle, cell death, modulation by virus of host process, cell motility etc. The entire study indicates the presence of potassium channel families in L. donovani which may have involvement in several cellular pathways. Further investigations on these putative potassium channels are needed to elucidate their roles in Leishmania. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-023-03692-y.
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Affiliation(s)
- Anindita Paul
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
| | - Shubham Sunil Chumbale
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
| | - Anjana Lakra
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
| | - Vijay Kumar
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
| | - Dhanashri Sudam Alhat
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
| | - Sushma Singh
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, SAS Nagar, Mohali, 160062 Punjab India
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16
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Meng JH, Schuman B, Rudy B, Wang XJ. Mechanisms of Dominant Electrophysiological Features of Four Subtypes of Layer 1 Interneurons. J Neurosci 2023; 43:3202-3218. [PMID: 36931710 PMCID: PMC10168018 DOI: 10.1523/jneurosci.1876-22.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 02/01/2023] [Accepted: 02/26/2023] [Indexed: 03/19/2023] Open
Abstract
Neocortical layer 1 (L1) consists of the distal dendrites of pyramidal cells and GABAergic interneurons (INs) and receives extensive long-range "top-down" projections, but L1 INs remain poorly understood. In this work, we systematically examined the distinct dominant electrophysiological features for four unique IN subtypes in L1 that were previously identified from mice of either gender: Canopy cells show an irregular firing pattern near rheobase; neurogliaform cells are late-spiking, and their firing rate accelerates during current injections; cells with strong expression of the α7 nicotinic receptor (α7 cells), display onset (rebound) bursting; vasoactive intestinal peptide (VIP) expressing cells exhibit high input resistance, strong adaptation, and irregular firing. Computational modeling revealed that these diverse neurophysiological features could be explained by an extended exponential-integrate-and-fire neuron model with varying contributions of a slowly inactivating K+ channel, a T-type Ca2+ channel, and a spike-triggered Ca2+-dependent K+ channel. In particular, we show that irregular firing results from square-wave bursting through a fast-slow analysis. Furthermore, we demonstrate that irregular firing is frequently observed in VIP cells because of the interaction between strong adaptation and a slowly inactivating K+ channel. At last, we reveal that the VIP and α7 cell models resonant with alpha/theta band input through a dynamic gain analysis.SIGNIFICANCE STATEMENT In the neocortex, ∼25% of neurons are interneurons. Interestingly, only somas of interneurons reside within layer 1 (L1) of the neocortex, but not of excitatory pyramidal cells. L1 interneurons are diverse and believed to be important in the cortical-cortex interactions, especially top-down signaling in the cortical hierarchy. However, the electrophysiological features of L1 interneurons are poorly understood. Here, we systematically studied the electrophysiological features within each L1 interneuron subtype. Furthermore, we build computational models for each subtype and study the mechanisms behind these features. These electrophysiological features within each subtype should be incorporated to elucidate how different L1 interneuron subtypes contribute to communication between cortexes.
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Affiliation(s)
- John Hongyu Meng
- Center for Neural Science, New York University, New York, New York 10003
| | - Benjamin Schuman
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University, New York, New York 10016
| | - Bernardo Rudy
- Neuroscience Institute, Department of Neuroscience and Physiology, New York University, New York, New York 10016
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, New York University, New York, New York 10016
| | - Xiao-Jing Wang
- Center for Neural Science, New York University, New York, New York 10003
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17
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Pinto FM, Odriozola A, Candenas L, Subirán N. The Role of Sperm Membrane Potential and Ion Channels in Regulating Sperm Function. Int J Mol Sci 2023; 24:6995. [PMID: 37108159 PMCID: PMC10138380 DOI: 10.3390/ijms24086995] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 04/02/2023] [Accepted: 04/05/2023] [Indexed: 04/29/2023] Open
Abstract
During the last seventy years, studies on mammalian sperm cells have demonstrated the essential role of capacitation, hyperactivation and the acrosome reaction in the acquisition of fertilization ability. These studies revealed the important biochemical and physiological changes that sperm undergo in their travel throughout the female genital tract, including changes in membrane fluidity, the activation of soluble adenylate cyclase, increases in intracellular pH and Ca2+ and the development of motility. Sperm are highly polarized cells, with a resting membrane potential of about -40 mV, which must rapidly adapt to the ionic changes occurring through the sperm membrane. This review summarizes the current knowledge about the relationship between variations in the sperm potential membrane, including depolarization and hyperpolarization, and their correlation with changes in sperm motility and capacitation to further lead to the acrosome reaction, a calcium-dependent exocytosis process. We also review the functionality of different ion channels that are present in spermatozoa in order to understand their association with human infertility.
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Affiliation(s)
- Francisco M. Pinto
- Instituto de Investigaciones Químicas, CSIC-University of Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla, Spain;
| | - Ainize Odriozola
- Department of Physiology, Faculty of Medicine and Nursery, University of the Basque Country (UPV/EHU), 48940 Bizkaia, Spain; (A.O.); (N.S.)
- Biocruces-Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- MEPRO Medical Reproductive Solutions, 20009 San Sebastian, Spain
| | - Luz Candenas
- Instituto de Investigaciones Químicas, CSIC-University of Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla, Spain;
| | - Nerea Subirán
- Department of Physiology, Faculty of Medicine and Nursery, University of the Basque Country (UPV/EHU), 48940 Bizkaia, Spain; (A.O.); (N.S.)
- Biocruces-Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- MEPRO Medical Reproductive Solutions, 20009 San Sebastian, Spain
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18
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Henton A, Zhao Y, Tzounopoulos T. A Role for KCNQ Channels on Cell Type-Specific Plasticity in Mouse Auditory Cortex after Peripheral Damage. J Neurosci 2023; 43:2277-2290. [PMID: 36813573 PMCID: PMC10072297 DOI: 10.1523/jneurosci.1070-22.2023] [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: 06/03/2022] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 02/24/2023] Open
Abstract
Damage to sensory organs triggers compensatory plasticity mechanisms in sensory cortices. These plasticity mechanisms result in restored cortical responses, despite reduced peripheral input, and contribute to the remarkable recovery of perceptual detection thresholds to sensory stimuli. Overall, peripheral damage is associated with a reduction of cortical GABAergic inhibition; however, less is known about changes in intrinsic properties and the underlying biophysical mechanisms. To study these mechanisms, we used a model of noise-induced peripheral damage in male and female mice. We uncovered a rapid, cell type-specific reduction in the intrinsic excitability of parvalbumin-expressing neurons (PVs) in layer (L) 2/3 of auditory cortex. No changes in the intrinsic excitability of either L2/3 somatostatin-expressing or L2/3 principal neurons (PNs) were observed. The decrease in L2/3 PV excitability was observed 1, but not 7, d after noise exposure, and was evidenced by a hyperpolarization of the resting membrane potential, depolarization of the action potential threshold, and reduction in firing frequency in response to depolarizing current. To uncover the underlying biophysical mechanisms, we recorded potassium currents. We found an increase in KCNQ potassium channel activity in L2/3 PVs of auditory cortex 1 d after noise exposure, associated with a hyperpolarizing shift in the minimal voltage activation of KCNQ channels. This increase contributes to the decreased intrinsic excitability of PVs. Our results highlight cell-type- and channel-specific mechanisms of plasticity after noise-induced hearing loss and will aid in understanding the pathologic processes involved in hearing loss and hearing loss-related disorders, such as tinnitus and hyperacusis.SIGNIFICANCE STATEMENT Noise-induced damage to the peripheral auditory system triggers central plasticity that compensates for the reduced peripheral input. The mechanisms of this plasticity are not fully understood. In the auditory cortex, this plasticity likely contributes to the recovery of sound-evoked responses and perceptual hearing thresholds. Importantly, other functional aspects of hearing do not recover, and peripheral damage may also lead to maladaptive plasticity-related disorders, such as tinnitus and hyperacusis. Here, after noise-induced peripheral damage, we highlight a rapid, transient, and cell type-specific reduction in the excitability of layer 2/3 parvalbumin-expressing neurons, which is due, at least in part, to increased KCNQ potassium channel activity. These studies may highlight novel strategies for enhancing perceptual recovery after hearing loss and mitigating hyperacusis and tinnitus.
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Affiliation(s)
- Amanda Henton
- Pittsburgh Hearing Research Center and Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Center for Neuroscience, University of Pittsburgh, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Yanjun Zhao
- Pittsburgh Hearing Research Center and Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Thanos Tzounopoulos
- Pittsburgh Hearing Research Center and Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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19
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Xin P, Xu L, Dong W, Mao L, Guo J, Bi J, Zhang S, Pei Y, Chen CP. Synthetic K + Channels Constructed by Rebuilding the Core Modules of Natural K + Channels in an Artificial System. Angew Chem Int Ed Engl 2023; 62:e202217859. [PMID: 36583482 DOI: 10.1002/anie.202217859] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 12/26/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022]
Abstract
Different types of natural K+ channels share similar core modules and cation permeability characteristics. In this study, we have developed novel artificial K+ channels by rebuilding the core modules of natural K+ channels in artificial systems. All the channels displayed high selectivity for K+ over Na+ and exhibited a selectivity sequence of K+ ≈Rb+ during the transport process, which is highly consistent with the cation permeability characteristics of natural K+ channels. More importantly, these artificial channels could be efficiently inserted into cell membranes and mediate the transmembrane transport of K+ , disrupting the cellular K+ homeostasis and eventually triggering the apoptosis of cells. These findings demonstrate that, by rebuilding the core modules of natural K+ channels in artificial systems, the structures, transport behaviors, and physiological functions of natural K+ channels can be mimicked in synthetic channels.
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Affiliation(s)
- Pengyang Xin
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Linqi Xu
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Wenpei Dong
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Linlin Mao
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Jingjing Guo
- Engineering Research Centre of Applied Technology on Machine Translation and Artificial Intelligence, Macao Polytechnic University, Macao, 999078, China
| | - Jingjing Bi
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Shouwei Zhang
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Yan Pei
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
| | - Chang-Po Chen
- Pingyuan Laboratory, NMPA (National Medical Products Administration) Key Laboratory for Research and Evaluation of Innovative Drug, Henan Key Laboratory of Organic Functional Molecule and Drug Innovation, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, 453007, China
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20
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Richter-Laskowska M, Trybek P, Delfino DV, Wawrzkiewicz-Jałowiecka A. Flavonoids as Modulators of Potassium Channels. Int J Mol Sci 2023; 24:1311. [PMID: 36674825 PMCID: PMC9861088 DOI: 10.3390/ijms24021311] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 01/12/2023] Open
Abstract
Potassium channels are widely distributed integral proteins responsible for the effective and selective transport of K+ ions through the biological membranes. According to the existing structural and mechanistic differences, they are divided into several groups. All of them are considered important molecular drug targets due to their physiological roles, including the regulation of membrane potential or cell signaling. One of the recent trends in molecular pharmacology is the evaluation of the therapeutic potential of natural compounds and their derivatives, which can exhibit high specificity and effectiveness. Among the pharmaceuticals of plant origin, which are potassium channel modulators, flavonoids appear as a powerful group of biologically active substances. It is caused by their well-documented anti-oxidative, anti-inflammatory, anti-mutagenic, anti-carcinogenic, and antidiabetic effects on human health. Here, we focus on presenting the current state of knowledge about the possibilities of modulation of particular types of potassium channels by different flavonoids. Additionally, the biological meaning of the flavonoid-mediated changes in the activity of K+ channels will be outlined. Finally, novel promising directions for further research in this area will be proposed.
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Affiliation(s)
- Monika Richter-Laskowska
- The Centre for Biomedical Engineering, Łukasiewicz Research Network—Krakow Institute of Technology, 30-418 Krakow, Poland
| | - Paulina Trybek
- Faculty of Science and Technology, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | | | - Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland
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21
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Wang ZW, Trussell LO, Vedantham K. Regulation of Neurotransmitter Release by K + Channels. ADVANCES IN NEUROBIOLOGY 2023; 33:305-331. [PMID: 37615872 DOI: 10.1007/978-3-031-34229-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
K+ channels play potent roles in the process of neurotransmitter release by influencing the action potential waveform and modulating neuronal excitability and release probability. These diverse effects of K+ channel activation are ensured by the wide variety of K+ channel genes and their differential expression in different cell types. Accordingly, a variety of K+ channels have been implicated in regulating neurotransmitter release, including the Ca2+- and voltage-gated K+ channel Slo1 (also known as BK channel), voltage-gated K+ channels of the Kv3 (Shaw-type), Kv1 (Shaker-type), and Kv7 (KCNQ) families, G-protein-gated inwardly rectifying K+ (GIRK) channels, and SLO-2 (a Ca2+-. Cl-, and voltage-gated K+ channel in C. elegans). These channels vary in their expression patterns, subcellular localization, and biophysical properties. Their roles in neurotransmitter release may also vary depending on the synapse and physiological or experimental conditions. This chapter summarizes key findings about the roles of K+ channels in regulating neurotransmitter release.
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Affiliation(s)
- Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT, USA.
| | - Laurence O Trussell
- Oregon Hearing Research Center & Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Kiranmayi Vedantham
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT, USA
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22
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McGahan K, Keener J. Modeling the kinetics of heteromeric potassium channels. Front Cell Neurosci 2022; 16:1036813. [DOI: 10.3389/fncel.2022.1036813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Abstract
Mechanistic mathematical modeling has long been used as a tool for answering questions in cellular physiology. To mathematically describe cellular processes such as cell excitability, volume regulation, neurotransmitter release, and hormone secretion requires accurate descriptions of ion channel kinetics. One class of ion channels currently lacking a physiological model framework is the class of channels built with multiple different potassium protein subunits called heteromeric voltage gated potassium channels. Here we present a novel mathematical model for heteromeric potassium channels that captures both the number and type of protein subunits present in each channel. Key model assumptions are validated by showing our model is the reduction of a Markov model and through observations about voltage clamp data. We then show our model's success in replicating kinetic properties of concatemeric channels with different numbers of Kv1.1 and Kv1.2 subunits. Finally, through comparisons with multiple expression experiments across multiple voltage gated potassium families, we use the model to make predictions about the importance and effect of genetic mutations in heteromeric channel formation.
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23
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Cereijido M, Jimenez L, Hinojosa L, Castillo A, Martínez-Rendon J, Ponce A. Ouabain-Induced Changes in the Expression of Voltage-Gated Potassium Channels in Epithelial Cells Depend on Cell-Cell Contacts. Int J Mol Sci 2022; 23:13257. [PMID: 36362049 PMCID: PMC9655981 DOI: 10.3390/ijms232113257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/21/2022] [Accepted: 10/23/2022] [Indexed: 12/25/2023] Open
Abstract
Ouabain is a cardiac glycoside, initially isolated from plants, and currently thought to be a hormone since some mammals synthesize it endogenously. It has been shown that in epithelial cells, it induces changes in properties and components related to apical-basolateral polarity and cell-cell contacts. In this work, we used a whole-cell patch clamp to test whether ouabain affects the properties of the voltage-gated potassium currents (Ik) of epithelial cells (MDCK). We found that: (1) in cells arranged as mature monolayers, ouabain induced changes in the properties of Ik; (2) it also accelerated the recovery of Ik in cells previously trypsinized and re-seeded at confluence; (3) in cell-cell contact-lacking cells, ouabain did not produce a significant change; (4) Na+/K+ ATPase might be the receptor that mediates the effect of ouabain on Ik; (5) the ouabain-induced changes in Ik required the synthesis of new nucleotides and proteins, as well as Golgi processing and exocytosis, as evidenced by treatment with drugs inhibiting those processes; and (5) the signaling cascade included the participation of cSrC, PI3K, Erk1/2, NF-κB and β-catenin. These results reveal a new role for ouabain as a modulator of the expression of voltage-gated potassium channels, which require cells to be in contact with themselves.
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Affiliation(s)
- Marcelino Cereijido
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
| | - Lidia Jimenez
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
| | - Lorena Hinojosa
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
| | - Aida Castillo
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
| | - Jacqueline Martínez-Rendon
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
- Molecular Medicine Laboratory, Unidad Academica de Medicina Humana y C.S, Campus UAZ Siglo XXI-L1, Universidad Autónoma de Zacatecas, Zacatecas 98160, Mexico
| | - Arturo Ponce
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, CDMX 07360, Mexico
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24
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Daghbouche-Rubio N, López-López JR, Pérez-García MT, Cidad P. Vascular smooth muscle ion channels in essential hypertension. Front Physiol 2022; 13:1016175. [PMID: 36213221 PMCID: PMC9540222 DOI: 10.3389/fphys.2022.1016175] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
Hypertension is a highly prevalent chronic disease and the major risk factor for cardiovascular diseases, the leading cause of death worldwide. Hypertension is characterized by an increased vascular tone determined by the contractile state of vascular smooth muscle cells that depends on intracellular calcium levels. The interplay of ion channels determine VSMCs membrane potential and thus intracellular calcium that controls the degree of contraction, vascular tone and blood pressure. Changes in ion channels expression and function have been linked to hypertension, but the mechanisms and molecular entities involved are not completely clear. Furthermore, the literature shows discrepancies regarding the contribution of different ion channels to hypertension probably due to differences both in the vascular preparation and in the model of hypertension employed. Animal models are essential to study this multifactorial disease but it is also critical to know their characteristics to interpret properly the results obtained. In this review we summarize previous studies, using the hypertensive mouse (BPH) and its normotensive control (BPN), focused on the identified changes in the expression and function of different families of ion channels. We will focus on L-type voltage-dependent Ca2+ channels (Cav1.2), canonical transient receptor potential channels and four different classes of K+ channels: voltage-activated (Kv), large conductance Ca2+-activated (BK), inward rectifiers (Kir) and ATP-sensitive (KATP) K+ channels. We will describe the role of these channels in hypertension and we will discuss the importance of integrating individual changes in a global context to understand the complex interplay of ion channels in hypertension.
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25
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Ogata G, Partida GJ, Fasoli A, Ishida AT. Calcium/calmodulin-dependent protein kinase II associates with the K + channel isoform Kv4.3 in adult rat optic nerve. Front Neuroanat 2022; 16:958986. [PMID: 36172564 PMCID: PMC9512010 DOI: 10.3389/fnana.2022.958986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/10/2022] [Indexed: 11/25/2022] Open
Abstract
Spikes are said to exhibit "memory" in that they can be altered by spikes that precede them. In retinal ganglion cell axons, for example, rapid spiking can slow the propagation of subsequent spikes. This increases inter-spike interval and, thus, low-pass filters instantaneous spike frequency. Similarly, a K+ ion channel blocker (4-aminopyridine, 4AP) increases the time-to-peak of compound action potentials recorded from optic nerve, and we recently found that reducing autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) does too. These results would be expected if CaMKII modulates spike propagation by regulating 4AP-sensitive K+ channels. As steps toward identifying a possible substrate, we test whether (i) 4AP alters optic nerve spike shape in ways consistent with reducing K+ current, (ii) 4AP alters spike propagation consistent with effects of reducing CaMKII activation, (iii) antibodies directed against 4AP-sensitive and CaMKII-regulated K+ channels bind to optic nerve axons, and (iv) optic nerve CaMKII co-immunoprecipitates with 4AP-sensitive K+ channels. We find that, in adult rat optic nerve, (i) 4AP selectively slows spike repolarization, (ii) 4AP slows spike propagation, (iii) immunogen-blockable staining is achieved with anti-Kv4.3 antibodies but not with antibodies directed against Kv1.4 or Kv4.2, and (iv) CaMKII associates with Kv4.3. Kv4.3 may thus be a substrate that underlies activity-dependent spike regulation in adult visual system pathways.
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Affiliation(s)
- Genki Ogata
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA, United States
| | - Gloria J. Partida
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA, United States
| | - Anna Fasoli
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA, United States
| | - Andrew T. Ishida
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA, United States
- Department of Ophthalmology and Vision Science, University of California, Sacramento, Sacramento, CA, United States
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26
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Wang K, Zhao J, Guo Z. Interaction of KCNA5, CX43, and CX40 proteins in the atrial muscle of patients with atrial fibrillation. Cell Biol Int 2022; 46:1834-1840. [PMID: 35870168 DOI: 10.1002/cbin.11864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 07/06/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Keke Wang
- Henan Medical Key Laboratory of Arrhythmia Zhengzhou No. 7 People's Hospital Zhengzhou Henan China
| | - Juntao Zhao
- Department of Cardiac Surgery Zhengzhou No. 7 People's Hospital Zhengzhou Henan China
| | - Zhikun Guo
- Henan Medical Key Laboratory of Arrhythmia Zhengzhou No. 7 People's Hospital Zhengzhou Henan China
- Henan Key Laboratory of Medical Tissue Regeneration Xinxiang Medical University Xinxiang Henan China
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27
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Bi Q, Wang C, Cheng G, Chen N, Wei B, Liu X, Li L, Lu C, He J, Weng Y, Yin C, Lin Y, Wan S, Zhao L, Xu J, Wang Y, Gu Y, Shen XZ, Shi P. Microglia-derived PDGFB promotes neuronal potassium currents to suppress basal sympathetic tonicity and limit hypertension. Immunity 2022; 55:1466-1482.e9. [PMID: 35863346 DOI: 10.1016/j.immuni.2022.06.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/05/2022] [Accepted: 06/22/2022] [Indexed: 12/18/2022]
Abstract
Although many studies have addressed the regulatory circuits affecting neuronal activities, local non-synaptic mechanisms that determine neuronal excitability remain unclear. Here, we found that microglia prevented overactivation of pre-sympathetic neurons in the hypothalamic paraventricular nucleus (PVN) at steady state. Microglia constitutively released platelet-derived growth factor (PDGF) B, which signaled via PDGFRα on neuronal cells and promoted their expression of Kv4.3, a key subunit that conducts potassium currents. Ablation of microglia, conditional deletion of microglial PDGFB, or suppression of neuronal PDGFRα expression in the PVN elevated the excitability of pre-sympathetic neurons and sympathetic outflow, resulting in a profound autonomic dysfunction. Disruption of the PDGFBMG-Kv4.3Neuron pathway predisposed mice to develop hypertension, whereas central supplementation of exogenous PDGFB suppressed pressor response when mice were under hypertensive insult. Our results point to a non-immune action of resident microglia in maintaining the balance of sympathetic outflow, which is important in preventing cardiovascular diseases.
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Affiliation(s)
- Qianqian Bi
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Chao Wang
- Center of Stem Cell and Regenerative Medicine and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science & Brain-Machine Integration, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Guo Cheng
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Ningting Chen
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Bo Wei
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Xiaoli Liu
- Department of Neurology, Affiliated Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Li Li
- Department of Pharmacy, Affiliated Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310013, China
| | - Cheng Lu
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jian He
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Yuancheng Weng
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Chunyou Yin
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Yunfan Lin
- Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining, Zhejiang 314400, China
| | - Shu Wan
- Brain Center, Affiliated Zhejiang Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Li Zhao
- Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jiaxi Xu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shanxi 710061, China
| | - Yi Wang
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Yan Gu
- Center of Stem Cell and Regenerative Medicine and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science & Brain-Machine Integration, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Xiao Z Shen
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.
| | - Peng Shi
- Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.
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28
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Olah VJ, Goettemoeller AM, Rayaprolu S, Dammer EB, Seyfried NT, Rangaraju S, Dimidschstein J, Rowan MJM. Biophysical Kv3 channel alterations dampen excitability of cortical PV interneurons and contribute to network hyperexcitability in early Alzheimer's. eLife 2022; 11:75316. [PMID: 35727131 PMCID: PMC9278953 DOI: 10.7554/elife.75316] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
In Alzheimer’s disease (AD), a multitude of genetic risk factors and early biomarkers are known. Nevertheless, the causal factors responsible for initiating cognitive decline in AD remain controversial. Toxic plaques and tangles correlate with progressive neuropathology, yet disruptions in circuit activity emerge before their deposition in AD models and patients. Parvalbumin (PV) interneurons are potential candidates for dysregulating cortical excitability as they display altered action potential (AP) firing before neighboring excitatory neurons in prodromal AD. Here, we report a novel mechanism responsible for PV hypoexcitability in young adult familial AD mice. We found that biophysical modulation of Kv3 channels, but not changes in their mRNA or protein expression, were responsible for dampened excitability in young 5xFAD mice. These K+ conductances could efficiently regulate near-threshold AP firing, resulting in gamma-frequency-specific network hyperexcitability. Thus, biophysical ion channel alterations alone may reshape cortical network activity prior to changes in their expression levels. Our findings demonstrate an opportunity to design a novel class of targeted therapies to ameliorate cortical circuit hyperexcitability in early AD.
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Affiliation(s)
- Viktor J Olah
- Department of Cell Biology, Emory University, Atlanta, United States
| | | | - Sruti Rayaprolu
- Department of Neurology, Emory University, Atlanta, United States
| | - Eric B Dammer
- Department of Biochemistry, Emory University, Atlanta, United States
| | | | | | | | - Matthew J M Rowan
- Department of Cell Biology, Emory University, Atlanta, United States
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29
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Naseem MU, Carcamo-Noriega E, Beltrán-Vidal J, Borrego J, Szanto TG, Zamudio FZ, Delgado-Prudencio G, Possani LD, Panyi G. Cm28, a scorpion toxin having a unique primary structure, inhibits KV1.2 and KV1.3 with high affinity. J Gen Physiol 2022; 154:213282. [PMID: 35699659 PMCID: PMC9202693 DOI: 10.1085/jgp.202213146] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/23/2022] [Indexed: 02/03/2023] Open
Abstract
The Cm28 in the venom of Centruroides margaritatus is a short peptide consisting of 27 amino acid residues with a mol wt of 2,820 D. Cm28 has <40% similarity with other known α-KTx from scorpions and lacks the typical functional dyad (lysine-tyrosine) required to block KV channels. However, its unique sequence contains the three disulfide-bond traits of the α-KTx scorpion toxin family. We propose that Cm28 is the first example of a new subfamily of α-KTxs, registered with the systematic number α-KTx32.1. Cm28 inhibited voltage-gated K+ channels KV1.2 and KV1.3 with Kd values of 0.96 and 1.3 nM, respectively. There was no significant shift in the conductance-voltage (G-V) relationship for any of the channels in the presence of toxin. Toxin binding kinetics showed that the association and dissociation rates are consistent with a bimolecular interaction between the peptide and the channel. Based on these, we conclude that Cm28 is not a gating modifier but rather a pore blocker. In a selectivity assay, Cm28 at 150 nM concentration (>100× Kd value for KV1.3) did not inhibit KV1.5, KV11.1, KCa1.1, and KCa3.1 K+ channels; NaV1.5 and NaV1.4 Na+ channels; or the hHV1 H+ channel but blocked ∼27% of the KV1.1 current. In a biological functional assay, Cm28 strongly inhibited the expression of the activation markers interleukin-2 receptor and CD40 ligand in anti-CD3-activated human CD4+ effector memory T lymphocytes. Cm28, due to its unique structure, may serve as a template for the generation of novel peptides targeting KV1.3 in autoimmune diseases.
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Affiliation(s)
- Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Edson Carcamo-Noriega
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - José Beltrán-Vidal
- Grupo de Investigaciones Herpetológicas y Toxinológicas, Centro de Investigaciones Biomédicas, Departamento de Biología, Facultad de Ciencias Naturales, Exactas y de la Educación, Universidad del Cauca, Popayán, Colombia
| | - Jesus Borrego
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Tibor G. Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Fernando Z. Zamudio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Gustavo Delgado-Prudencio
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Lourival D. Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, Research Center for Molecular Medicine, University of Debrecen, Debrecen, Hungary,Correspondence to Gyorgy Panyi:
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30
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Richardson A, Ciampani V, Stancu M, Bondarenko K, Newton S, Steinert JR, Pilati N, Graham BP, Kopp-Scheinpflug C, Forsythe ID. Kv3.3 subunits control presynaptic action potential waveform and neurotransmitter release at a central excitatory synapse. eLife 2022; 11:75219. [PMID: 35510987 PMCID: PMC9110028 DOI: 10.7554/elife.75219] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 04/29/2022] [Indexed: 11/29/2022] Open
Abstract
Kv3 potassium currents mediate rapid repolarisation of action potentials (APs), supporting fast spikes and high repetition rates. Of the four Kv3 gene family members, Kv3.1 and Kv3.3 are highly expressed in the auditory brainstem and we exploited this to test for subunit-specific roles at the calyx of Held presynaptic terminal in the mouse. Deletion of Kv3.3 (but not Kv3.1) reduced presynaptic Kv3 channel immunolabelling, increased presynaptic AP duration and facilitated excitatory transmitter release; which in turn enhanced short-term depression during high-frequency transmission. The response to sound was delayed in the Kv3.3KO, with higher spontaneous and lower evoked firing, thereby reducing signal-to-noise ratio. Computational modelling showed that the enhanced EPSC and short-term depression in the Kv3.3KO reflected increased vesicle release probability and accelerated activity-dependent vesicle replenishment. We conclude that Kv3.3 mediates fast repolarisation for short precise APs, conserving transmission during sustained high-frequency activity at this glutamatergic excitatory synapse.
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Affiliation(s)
- Amy Richardson
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Victoria Ciampani
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Mihai Stancu
- Division of Neurobiology, Ludwig-Maximilians-Universität München, Munchen, Germany
| | - Kseniia Bondarenko
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Sherylanne Newton
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Joern R Steinert
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Nadia Pilati
- Istituto di Ricerca Pediatrica Citta'della Speranza, Padova, Italy
| | - Bruce P Graham
- Computing Science and Mathematics, University of Stirling, Stirling, United Kingdom
| | | | - Ian D Forsythe
- epartment of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
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31
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Creating a Novel Mathematical Model of the Kv10.1 Ion Channel and Controlling Channel Activity with Nanoelectromechanical Systems. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12083836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The use of nanoelectromechanical systems or nanorobots offers a new concept for sensing and controlling subcellular structures, such as ion channels. We present here a novel method for mathematical modeling of ion channels based on control system theory and system identification. We investigated the use of nanoelectromechanical devices to control the activity of ion channels, particularly the activity of the voltage-gated ion channel Kv10.1, an important channel in cancer development and progression. A mathematical model of the dynamic behavior of the selected ion channel Kv10.1 in the Laplace (s) domain was developed, which is given in the representation of a transfer function. In addition, we addressed the possibilities of controlling ion channel activity by nanoelectromechanical devices and nanorobots and finally presented a control algorithm for the Kv10.1 as a control object. A use case demonstrates the potential of a Kv10.1 controlled nanorobot for cancer treatment at a single-cell level.
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Sonekatsu M, Yamada H, Nishio N, Gu JG. Effects on low threshold mechanoreceptors in whisker hair follicles by 5-HT, Cd 2+, tetraethylammonium, 4-aminopyridine, and Ba 2. Mol Pain 2022; 18:17448069221076606. [PMID: 35189758 PMCID: PMC8873973 DOI: 10.1177/17448069221076606] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Low threshold mechanoreceptors (LTMRs) are important for environmental exploration, social interaction, and tactile discrimination. Whisker hair follicles are mechanical sensory organs in non-primate mammals that are functionally equivalent to human fingertips. Several functional types of LTMRs have been identified in rodent whisker hair follicles, including rapidly adapting (RA), slow adapting type 1 (SA1), and slowly adapting type 2 (SA2) LTMRs. Properties of these LTMRs have not been fully characterized. In the present study, we have used pressure-clamped single-fiber recording technique to record impulses of RA, SA1, and SA2 LTMRs in mouse whisker hair follicles, and tested effects of 5-HT, Cd2+, tetraethylammonium (TEA), 4-aminopyridine (4-AP), and Ba2+ on the LTMR impulses. We show that 5-HT at 2 mM suppresses SA1 impulses but has no effects on RA and SA2 impulses. Cd2+ at 100 μM suppresses both SA1 and SA2 impulses but has no effects on RA impulses. TEA at 10 mM has no effects on RA and SA1 impulses but increased SA2 impulses. However, TEA at 1 mM and 200 μM decreases SA2 impulses. 4-AP at 1 mM suppresses both SA1 and SA2 impulses but has no effects on RA impulses. Ba2+ at 5 mM increases both RA and SA1 impulses but suppresses SA2 impulses. Collectively, RA, SA1, and SA2 LTMRs show distinct pharmacological properties, suggesting that these LTMRs may use different mechanisms to tune their mechanical signaling.
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Affiliation(s)
- Mayumi Sonekatsu
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Hiroshi Yamada
- Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Naoko Nishio
- Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Jianguo G Gu
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
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Wang GH, Chuang AY, Lai YC, Chen HI, Hsueh SW, Yang YC. Pre- and post-synaptic A-type K + channels regulate glutamatergic transmission and switch of the network into epileptiform oscillations. Br J Pharmacol 2022; 179:3754-3777. [PMID: 35170022 DOI: 10.1111/bph.15818] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/28/2021] [Accepted: 02/02/2022] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Anticonvulsants targeting K+ channels have not been clinically available, although neuronal hyperexcitability in seizures could be suppressed by activation of K+ channels. Voltage-gated A-type K+ channel (A-channel) inhibitors may be prescribed for diseases of neuromuscular junction but could cause seizures. Consistently, genetic loss of function of A-channels may also cause seizures. It is unclear why inhibition of A-channels, if compared with the other types of K+ channels, is particularly prone to seizure induction. This hinders the development of relevant therapeutic interventions. EXPERIMENTAL APPROACH The epileptogenic mechanisms of A-channel inhibition and antiepileptic actions of A-channel activation were investigated in electrophysiological and behavioral seizures with pharmacological and optogenetic maneuvers. KEY RESULTS Presynaptic Kv1.4 and postsynaptic Kv4.3 A-channels act synergistically to gate glutamatergic transmission and control rhythmogenesis in the amygdala. The interconnected neurons set into the oscillatory mode by A-channel inhibition would reverberate with regular paces and the same top frequency, demonstrating a spatiotemporally well-orchestrated system with built-in oscillatory rhythms normally curbed by A-channels. Accordingly, selective over-excitation of glutamatergic neurons or inhibition of A-channels suffices to induce behavioral seizures, which are effectively ameliorated by A-channel activators such as NS-5806 or AMPA receptor antagonists such as perampanel. CONCLUSION AND IMPLICATIONS Transsynaptic voltage-dependent A-channels serve as a biophysical-biochemical transducer responsible for a novel form of synaptic plasticity. Such a network-level switch into and out of the oscillatory mode may underlie a wide-scope of telencephalic information processing, or to its extreme, epileptic seizures. A-channels thus constitute a potential target of antiepileptic therapy.
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Affiliation(s)
- Guan-Hsun Wang
- Department of Neurology, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
| | - Ai-Yu Chuang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Yi-Chen Lai
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Hsin-I Chen
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Shu-Wei Hsueh
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Ya-Chin Yang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.,Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan.,Department of Psychiatry, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
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Huffels CFM, Osborn LM, Hulshof LA, Kooijman L, Henning L, Steinhäuser C, Hol EM. Amyloid-β plaques affect astrocyte Kir4.1 protein expression but not function in the dentate gyrus of APP/PS1 mice. Glia 2022; 70:748-767. [PMID: 34981861 PMCID: PMC9306581 DOI: 10.1002/glia.24137] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 01/09/2023]
Abstract
Alzheimer pathology is accompanied by astrogliosis. Reactive astrocytes surrounding amyloid plaques may directly affect neuronal communication, and one of the mechanisms by which astrocytes impact neuronal function is by affecting K+ homeostasis. Here we studied, using hippocampal slices from 9‐month‐old Alzheimer mice (APP/PS1) and wild‐type littermates, whether astrocyte function is changed by analyzing Kir4.1 expression and function and astrocyte coupling in astrocytes surrounding amyloid‐β plaques. Immunohistochemical analysis of Kir4.1 protein in the dentate gyrus revealed localized increases in astrocytes surrounding amyloid‐β plaque deposits. We subsequently focused on changes in astrocyte function by using patch‐clamp slice electrophysiology on both plaque‐ and non‐plaque associated astrocytes to characterize general membrane properties. We found that Ba2+‐sensitive Kir4.1 conductance in astrocytes surrounding plaques was not affected by changes in Kir4.1 protein expression. Additional analysis of astrocyte gap junction coupling efficiency in the dentate gyrus revealed no apparent changes. Quantification of basic features of glutamatergic transmission to granule cells did not indicate disturbed neuronal communication in the dentate gyrus of APP/PS1 mice. Together, these results suggest that astrocytes in the dentate gyrus of APP/PS1 mice maintain their ability to buffer extracellular K+ and attempt to rectify imbalances in K+ concentration to maintain normal neuronal and synaptic function, possibly by localized increases in Kir4.1 protein expression. Our earlier transcriptomic data indicated that chronically activated astrocytes lose their neuronal support function. Here we show that, despite localized increased Kir4.1 protein expression, astrocyte Kir4.1 channel dysfunction is likely not involved in the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Christiaan F. M. Huffels
- Department of Translational Neuroscience, University Medical Center Utrecht Brain CenterUtrecht UniversityUtrechtThe Netherlands
| | - Lana M. Osborn
- Swammerdam Institute for Life Sciences, Center for NeuroscienceUniversity of AmsterdamAmsterdamThe Netherlands
| | - Lianne A. Hulshof
- Department of Translational Neuroscience, University Medical Center Utrecht Brain CenterUtrecht UniversityUtrechtThe Netherlands
| | - Lieneke Kooijman
- Swammerdam Institute for Life Sciences, Center for NeuroscienceUniversity of AmsterdamAmsterdamThe Netherlands
| | - Lukas Henning
- Institute of Cellular Neurosciences, Medical FacultyUniversity of BonnBonnGermany
| | | | - Elly M. Hol
- Department of Translational Neuroscience, University Medical Center Utrecht Brain CenterUtrecht UniversityUtrechtThe Netherlands
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Kv3 Channels Contribute to the Excitability of Subpopulations of Spinal Cord Neurons in Lamina VII. eNeuro 2022; 9:ENEURO.0510-21.2021. [PMID: 35058310 PMCID: PMC8868027 DOI: 10.1523/eneuro.0510-21.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 12/21/2021] [Indexed: 11/29/2022] Open
Abstract
Autonomic parasympathetic preganglionic neurons (PGNs) drive contraction of the bladder during micturition but remain quiescent during bladder filling. This quiescence is postulated to be because of recurrent inhibition of PGN by fast-firing adjoining interneurons. Here, we defined four distinct neuronal types within Lamina VII, where PGN are situated, by combining whole cell patch clamp recordings with k-means clustering of a range of electrophysiological parameters. Additional morphologic analysis separated these neuronal classes into parasympathetic preganglionic populations (PGN) and a fast-firing interneuronal population. Kv3 channels are voltage-gated potassium channels (Kv) that allow fast and precise firing of neurons. We found that blockade of Kv3 channels by tetraethylammonium (TEA) reduced neuronal firing frequency and isolated high-voltage-activated Kv currents in the fast-firing population but had no effect in PGN populations. Furthermore, Kv3 blockade potentiated the local and descending inhibitory inputs to PGN indicating that Kv3-expressing inhibitory neurons are synaptically connected to PGN. Taken together, our data reveal that Kv3 channels are crucial for fast and regulated neuronal output of a defined population that may be involved in intrinsic spinal bladder circuits that underpin recurrent inhibition of PGN.
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Griego E, Hernández-Frausto M, Márquez LA, Lara-Valderrabano L, López Rubalcava C, Galván EJ. Activation of D1/D5 Receptors Ameliorates Decreased Intrinsic Excitability of Hippocampal Neurons Induced by Neonatal Blockade of NMDA Receptors. Br J Pharmacol 2021; 179:1695-1715. [PMID: 34791647 DOI: 10.1111/bph.15735] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 10/01/2021] [Accepted: 10/15/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Dysregulation of dopaminergic transmission combined with transient hypofunction of N-methyl-D-aspartate receptors (NMDARs) is a key mechanism that may underlie cognitive symptoms of schizophrenia. EXPERIMENTAL APPROACH Therefore, we aimed to identify electrophysiologic alterations in animals neonatally treated with the NMDA receptor antagonist, MK-801 or with saline solution. KEY RESULTS Patch-clamp whole-cell recordings from MK-801-treated animals revealed altered passive and active electrophysiologic properties compared with CA1 pyramidal cells from saline-treated animals, including upregulation of the K+ inward-rectifier conductance and fast-inactivating and slow/non-inactivating K+ currents. Upregulation of these membrane ionic currents reduced the overall excitability and altered the firing properties of CA1 pyramidal cells. We also explored the capability of cells treated with MK-801 to express intrinsic excitability potentiation, a non-synaptic form of hippocampal plasticity associated with cognition and memory formation. CA1 pyramidal cells from animals treated with MK-801 were unable to convey intrinsic excitability potentiation and had blunted synaptic potentiation. Furthermore, MK-801-treated animals also exhibited reduced cognitive performance in the Barnes maze task. Notably, activation of D1/D5 receptors with SKF-38, 393 partially restored electrophysiologic alterations caused by neonatal treatment with MK-801. CONCLUSION AND IMPLICATIONS Our results offer a molecular and mechanistic explanation based on dysregulation of glutamatergic in addition to dopaminergic transmission that may contribute to the understanding of the cognitive deterioration associated with schizophrenia.
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Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Melissa Hernández-Frausto
- Current address: Department of Neuroscience and Physiology, NYU Neuroscience Institute, New York University Langone Medical Center, New York, NY, USA
| | - Luis A Márquez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Leonardo Lara-Valderrabano
- Current address: A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Carolina López Rubalcava
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
| | - Emilio J Galván
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México
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Li X, Zheng Y, Li S, Nair U, Sun C, Zhao C, Lu J, Zhang VW, Maljevic S, Petrou S, Lin J. Kv3.1 channelopathy: a novel loss-of-function variant and the mechanistic basis of its clinical phenotypes. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1397. [PMID: 34733949 PMCID: PMC8506712 DOI: 10.21037/atm-21-1885] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/11/2021] [Indexed: 11/26/2022]
Abstract
Background KCNC1 encodes Kv3.1, a subunit of the Kv3 voltage-gated potassium channels. It is predominantly expressed in inhibitory GABAergic interneurons and cerebellar neurons. Kv3.1 channelopathy has been linked to a variety of human diseases including epilepsy, developmental delay, and ataxia. Characterization of structural and functional disturbances of this channel, and its relationship to a heterogenous group of clinical phenotypes, is a current topic of research. We herein characterize the clinical phenotype as well as the functional and structural consequences of the novel KCNC1 p.R317S variant. We further set out to explore the mechanistic basis for the spectrum of KCNC1 related channelopathies. Methods Variant was identified via whole-exome sequencing and its functional impact was determined using two-electrode voltage clamp recordings in Xenopus laevis oocytes. Homolog modeling and in silico structural analysis were performed on the p.R317S variant and other KCNC1 related variants. Results We identified a novel loss-of-function KCNC1 variant c.949C>A (p.R317S) presenting with symptoms similar to myoclonic epilepsy and ataxia due to potassium channel (MEAK), but with distinct radiological features. Functional analysis in the Xenopus laevis oocyte’s expression system revealed that the current amplitudes were significantly decreased in the p.R317S variant compared to the wild type, indicating a dominant-negative effect. Atomic structural analysis of the KCNC1 related variants provided a possible mechanistic explanation for the heterogeneity in the clinical spectrum. Conclusions We have identified the p.R317S loss-of-function variant in the KCNC1 gene, expanded the spectrum of potassium channelopathy and provided mechanistic insights into KCNC1 related disorders.
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Affiliation(s)
- Xiaoyang Li
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China.,Department of Neurology, University of North Carolina, Chapel Hill, USA
| | - Yongsheng Zheng
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | | | - Umesh Nair
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia
| | - Chong Sun
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Chongbo Zhao
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jiahong Lu
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
| | | | - Snezana Maljevic
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Australia
| | - Jie Lin
- Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China
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38
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Naseem MU, Tajti G, Gaspar A, Szanto TG, Borrego J, Panyi G. Optimization of Pichia pastoris Expression System for High-Level Production of Margatoxin. Front Pharmacol 2021; 12:733610. [PMID: 34658872 PMCID: PMC8511391 DOI: 10.3389/fphar.2021.733610] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022] Open
Abstract
Margatoxin (MgTx) is a high-affinity blocker of voltage-gated potassium (Kv) channels. It inhibits Kv1.1–Kv1.3 ion channels in picomolar concentrations. This toxin is widely used to study physiological function of Kv ion channels in various cell types, including immune cells. Isolation of native MgTx in large quantities from scorpion venom is not affordable. Chemical synthesis and recombinant production in Escherichia coli need in vitro oxidative refolding for proper disulfide bond formation, resulting in a very low yield of peptide production. The Pichia pastoris expression system offers an economical approach to overcome all these limitations and gives a higher yield of correctly refolded recombinant peptides. In this study, improved heterologous expression of recombinant MgTx (rMgTx) in P. pastoris was obtained by using preferential codons, selecting the hyper-resistant clone against Zeocin, and optimizing the culturing conditions. About 36 ± 4 mg/L of >98% pure His-tagged rMgTx (TrMgTx) was produced, which is a threefold higher yield than has been previously reported. Proteolytic digestion of TrMgTx with factor Xa generated untagged rMgTx (UrMgTx). Both TrMgTx and UrMgTx blocked the Kv1.2 and Kv1.3 currents (patch-clamp) (Kd for Kv1.2 were 64 and 14 pM, and for Kv1.3, 86 and 50 pM, respectively) with comparable potency to the native MgTx. The analysis of the binding kinetics showed that TrMgTx had a lower association rate than UrMgTx for both Kv1.2 and Kv1.3. The dissociation rate of both the analogues was the same for Kv1.3. However, in the case of Kv1.2, TrMgTx showed a much higher dissociation rate with full recovery of the block than UrMgTx. Moreover, in a biological functional assay, both peptides significantly downregulated the expression of early activation markers IL2R and CD40L in activated CD4+ TEM lymphocytes whose activation was Kv1.3 dependent. In conclusion, the authors report that the Pichia expression system is a powerful method to produce disulfide-rich peptides, the overexpression of which could be enhanced noticeably through optimization strategies, making it more cost-effective. Since the presence of the His-tag on rMgTx only mildly altered the block equilibrium and binding kinetics, recombinant toxins could be used in ion channel research without removing the tag and could thus reduce the cost and time demand for toxin production.
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Affiliation(s)
- Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gabor Tajti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Gaspar
- Department of Inorganic and Analytical Chemistry, Faculty of Science and Technology, Institute of Chemistry, University of Debrecen, Debrecen, Hungary
| | - Tibor G Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jesús Borrego
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Structural basis of gating modulation of Kv4 channel complexes. Nature 2021; 599:158-164. [PMID: 34552243 PMCID: PMC8566240 DOI: 10.1038/s41586-021-03935-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 08/19/2021] [Indexed: 11/08/2022]
Abstract
Modulation of voltage-gated potassium (Kv) channels by auxiliary subunits is central to the physiological function of channels in the brain and heart1,2. Native Kv4 tetrameric channels form macromolecular ternary complexes with two auxiliary β-subunits—intracellular Kv channel-interacting proteins (KChIPs) and transmembrane dipeptidyl peptidase-related proteins (DPPs)—to evoke rapidly activating and inactivating A-type currents, which prevent the backpropagation of action potentials1–5. However, the modulatory mechanisms of Kv4 channel complexes remain largely unknown. Here we report cryo-electron microscopy structures of the Kv4.2–DPP6S–KChIP1 dodecamer complex, the Kv4.2–KChIP1 and Kv4.2–DPP6S octamer complexes, and Kv4.2 alone. The structure of the Kv4.2–KChIP1 complex reveals that the intracellular N terminus of Kv4.2 interacts with its C terminus that extends from the S6 gating helix of the neighbouring Kv4.2 subunit. KChIP1 captures both the N and the C terminus of Kv4.2. In consequence, KChIP1 would prevent N-type inactivation and stabilize the S6 conformation to modulate gating of the S6 helices within the tetramer. By contrast, unlike the reported auxiliary subunits of voltage-gated channel complexes, DPP6S interacts with the S1 and S2 helices of the Kv4.2 voltage-sensing domain, which suggests that DPP6S stabilizes the conformation of the S1–S2 helices. DPP6S may therefore accelerate the voltage-dependent movement of the S4 helices. KChIP1 and DPP6S do not directly interact with each other in the Kv4.2–KChIP1–DPP6S ternary complex. Thus, our data suggest that two distinct modes of modulation contribute in an additive manner to evoke A-type currents from the native Kv4 macromolecular complex. Cryo-electron microscopy structures of the voltage-gated potassium channel Kv4.2 alone and in complex with auxiliary subunits (DPP6S and/or KChIP1) reveal the distinct mechanisms of these two different subunits in modulating channel activity.
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Shi Y, Andhey PS, Ising C, Wang K, Snipes LL, Boyer K, Lawson S, Yamada K, Qin W, Manis M, Serrano JR, Benitez BA, Schmidt RE, Artyomov M, Ulrich JD, Holtzman DM. Overexpressing low-density lipoprotein receptor reduces tau-associated neurodegeneration in relation to apoE-linked mechanisms. Neuron 2021; 109:2413-2426.e7. [PMID: 34157306 PMCID: PMC8349883 DOI: 10.1016/j.neuron.2021.05.034] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/03/2021] [Accepted: 05/27/2021] [Indexed: 01/01/2023]
Abstract
APOE is the strongest genetic risk factor for late-onset Alzheimer's disease. ApoE exacerbates tau-associated neurodegeneration by driving microglial activation. However, how apoE regulates microglial activation and whether targeting apoE is therapeutically beneficial in tauopathy is unclear. Here, we show that overexpressing an apoE metabolic receptor, LDLR (low-density lipoprotein receptor), in P301S tauopathy mice markedly reduces brain apoE and ameliorates tau pathology and neurodegeneration. LDLR overexpression (OX) in microglia cell-autonomously downregulates microglial Apoe expression and is associated with suppressed microglial activation as in apoE-deficient microglia. ApoE deficiency and LDLR OX strongly drive microglial immunometabolism toward enhanced catabolism over anabolism, whereas LDLR-overexpressing microglia also uniquely upregulate specific ion channels and neurotransmitter receptors upon activation. ApoE-deficient and LDLR-overexpressing mice harbor enlarged pools of oligodendrocyte progenitor cells (OPCs) and show greater preservation of myelin integrity under neurodegenerative conditions. They also show less reactive astrocyte activation in the setting of tauopathy.
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Affiliation(s)
- Yang Shi
- Department of Neurology, Washington University, St. Louis, MO 63110, USA
| | | | - Christina Ising
- Department of Neurodegenerative Diseases and Geriatric Psychiatry, University Hospital of Bonn and German Center for Neurodegenerative Diseases (DZNE), Bonn 53127, Germany
| | - Kairuo Wang
- Department of Neurology, Washington University, St. Louis, MO 63110, USA
| | - Lisa L Snipes
- Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Kevin Boyer
- Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Stephanie Lawson
- Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Kaoru Yamada
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Wei Qin
- Department of Psychiatry, Washington University, St. Louis, MO 63110, USA
| | - Melissa Manis
- Department of Neurology, Washington University, St. Louis, MO 63110, USA
| | | | - Bruno A Benitez
- Department of Psychiatry, Washington University, St. Louis, MO 63110, USA
| | - Robert E Schmidt
- Department of Pathology and Immunology, Washington University, St. Louis, MO 63110, USA
| | - Maxim Artyomov
- Department of Neurodegenerative Diseases and Geriatric Psychiatry, University Hospital of Bonn and German Center for Neurodegenerative Diseases (DZNE), Bonn 53127, Germany
| | - Jason D Ulrich
- Department of Neurology, Washington University, St. Louis, MO 63110, USA.
| | - David M Holtzman
- Department of Neurology, Washington University, St. Louis, MO 63110, USA.
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Oraby M, Ahmed AS, Abdel-Lateef MA, Mostafa MA, Hassan AI. Employ FTIR spectroscopic method for determination of certain multiple sclerosis medications in plasma and pharmaceutical formulations. Microchem J 2021. [DOI: 10.1016/j.microc.2021.106329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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42
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Kalkan ÖF, Şahin Z, Öztürk H, Keser H, Aydın-Abidin S, Abidin İ. Phoenixin-14 reduces the frequency of interictal-like events in mice brain slices. Exp Brain Res 2021; 239:2841-2849. [PMID: 34283252 DOI: 10.1007/s00221-021-06179-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/13/2021] [Indexed: 01/17/2023]
Abstract
Phoenixin-14 (PNX-14) has a wide bioactivity in the central nervous system. Its role in the hypothalamus has been investigated, and it has been reported that it is involved in the regulation of excitability in hypothalamic neurons. However, its role in the regulation of excitability in entorhinal cortex and the hippocampus is unknown. In this study, we investigated whether i. PNX-14 induces any synchronous discharges or epileptiform activity and ii. PNX-14 has any effect on already initiated epileptiform discharges. We used 350 µm thick acute horizontal hippocampal-entorhinal cortex slices obtained from 30- to 35-day-old mice. Extracellular field potential recordings were evaluated in the entorhinal cortex and hippocampus CA1 region. Bath application of PNX-14 did not initiate any epileptiform activity or abnormal discharges. 4-Aminopyridine was applied to induce epileptiform activity in the slices. We found that 200 nM PNX-14 reduced the frequency of interictal-like events in both the entorhinal cortex and hippocampus CA1 region which was induced by 4-aminopyridine. Furthermore, PNX-14 led to a similar suppression in the total power of local field potentials of 1-120 Hz. The frequency or the duration of the ictal events was not affected. These results exhibited for the first time that PNX-14 has a modulatory effect on synchronized neuronal discharges which should be considered in future therapeutic approaches.
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Affiliation(s)
- Ömer Faruk Kalkan
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey.
| | - Zafer Şahin
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey
| | - Hilal Öztürk
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey
| | - Hatice Keser
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey
| | - Selcen Aydın-Abidin
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey
| | - İsmail Abidin
- Department of Physiology, Faculty of Medicine, Karadeniz Technical University, 61080, Trabzon, Turkey
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Hong J, Fu S, Gao L, Cai Y, Lazartigues E, Wang HJ. Voltage-gated potassium channel dysfunction in dorsal root ganglia contributes to the exaggerated exercise pressor reflex in rats with chronic heart failure. Am J Physiol Heart Circ Physiol 2021; 321:H461-H474. [PMID: 34270374 DOI: 10.1152/ajpheart.00256.2021] [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] [Indexed: 11/22/2022]
Abstract
An exaggerated exercise pressor reflex (EPR) causes excessive sympathoexcitation and exercise intolerance during physical activity in the chronic heart failure (CHF) state. Muscle afferent sensitization contributes to the genesis of the exaggerated EPR in CHF. However, the cellular mechanisms underlying muscle afferent sensitization in CHF remain unclear. Considering that voltage-gated potassium (Kv) channels critically regulate afferent neuronal excitability, we examined the potential role of Kv channels in mediating the sensitized EPR in male rats with CHF. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting experiments demonstrate that both mRNA and protein expressions of multiple Kv channel isoforms (Kv1.4, Kv3.4, Kv4.2, and Kv4.3) were downregulated in lumbar dorsal root ganglions (DRGs) of CHF rats compared with sham rats. Immunofluorescence data demonstrate significant decreased Kv channel staining in both NF200-positive and IB4-positive lumbar DRG neurons in CHF rats compared with sham rats. Data from patch-clamp experiments demonstrate that the total Kv current, especially IA, was dramatically decreased in medium-sized IB4-negative muscle afferent neurons (a subpopulation containing mostly Aδ neurons) from CHF rats compared with sham rats, indicating a potential functional loss of Kv channels in muscle afferent Aδ neurons. In in vivo experiments, adenoviral overexpression of Kv4.3 in lumbar DRGs for 1 wk attenuated the exaggerated EPR induced by muscle static contraction and the mechanoreflex by passive stretch without affecting the blunted cardiovascular response to hindlimb arterial injection of capsaicin in CHF rats. These data suggest that Kv channel dysfunction in DRGs plays a critical role in mediating the exaggerated EPR and muscle afferent sensitization in CHF.NEW & NOTEWORTHY The primary finding of this manuscript is that voltage-gated potassium (Kv) channel dysfunction in DRGs plays a critical role in mediating the exaggerated EPR and muscle afferent sensitization in chronic heart failure (CHF). We propose that manipulation of Kv channels in DRG neurons could be considered as a potential new approach to reduce the exaggerated sympathoexcitation and to improve exercise intolerance in CHF, which can ultimately facilitate an improved quality of life and reduce mortality.
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Affiliation(s)
- Juan Hong
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Shubin Fu
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska.,College of Animal Science and Technology, Southwest University, Chongqing, People's Republic of China
| | - Lie Gao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Yanhui Cai
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Eric Lazartigues
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Han-Jun Wang
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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45
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Déri S, Borbás J, Hartai T, Hategan L, Csányi B, Visnyovszki Á, Madácsy T, Maléth J, Hegedűs Z, Nagy I, Arora R, Labro AJ, Környei L, Varró A, Sepp R, Ördög B. Impaired cytoplasmic domain interactions cause co-assembly defect and loss of function in the p.Glu293Lys KNCJ2 variant isolated from an Andersen-Tawil syndrome patient. Cardiovasc Res 2021; 117:1923-1934. [PMID: 32810216 DOI: 10.1093/cvr/cvaa249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/16/2020] [Accepted: 08/12/2020] [Indexed: 02/07/2023] Open
Abstract
AIMS Subunit interactions at the cytoplasmic domain interface (CD-I) have recently been shown to control gating in inward rectifier potassium channels. Here we report the novel KCNJ2 variant p.Glu293Lys that has been found in a patient with Andersen-Tawil syndrome type 1 (ATS1), causing amino acid substitution at the CD-I of the inward rectifier potassium channel subunit Kir2.1. Neither has the role of Glu293 in gating control been investigated nor has a pathogenic variant been described at this position. This study aimed to assess the involvement of Glu293 in CD-I subunit interactions and to establish the pathogenic role of the p.Glu293Lys variant in ATS1. METHODS AND RESULTS The p.Glu293Lys variant produced no current in homomeric form and showed dominant-negative effect over wild-type (WT) subunits. Immunocytochemical labelling showed the p.Glu293Lys subunits to distribute in the subsarcolemmal space. Salt bridge prediction indicated the presence of an intersubunit salt bridge network at the CD-I of Kir2.1, with the involvement of Glu293. Subunit interactions were studied by the NanoLuc® Binary Technology (NanoBiT) split reporter assay. Reporter constructs carrying NanoBiT tags on the intracellular termini produced no bioluminescent signal above background with the p.Glu293Lys variant in homomeric configuration and significantly reduced signals in cells co-expressing WT and p.Glu293Lys subunits simultaneously. Extracellularly presented reporter tags, however, generated comparable bioluminescent signals with heteromeric WT and p.Glu293Lys subunits and with homomeric WT channels. CONCLUSIONS Loss of function and dominant-negative effect confirm the causative role of p.Glu293Lys in ATS1. Co-assembly of Kir2.1 subunits is impaired in homomeric channels consisting of p.Glu293Lys subunits and is partially rescued in heteromeric complexes of WT and p.Glu293Lys Kir2.1 variants. These data point to an important role of Glu293 in mediating subunit assembly, as well as in gating of Kir2.1 channels.
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Affiliation(s)
- Szilvia Déri
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Dóm tér 12, PO Box 427, Szeged 6720, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 12, 6720 Szeged, Hungary
| | - János Borbás
- 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Semmelweis u. 8, 6725 Szeged, Hungary
| | - Teodóra Hartai
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Dóm tér 12, PO Box 427, Szeged 6720, Hungary
| | - Lidia Hategan
- 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Semmelweis u. 8, 6725 Szeged, Hungary
| | - Beáta Csányi
- 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Semmelweis u. 8, 6725 Szeged, Hungary
| | - Ádám Visnyovszki
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Dóm tér 12, PO Box 427, Szeged 6720, Hungary
| | - Tamara Madácsy
- 1st Department of Internal Medicine, University of Szeged, Korányi fasor 8-10, 6720 Szeged, Hungary, Hungary
| | - József Maléth
- 1st Department of Internal Medicine, University of Szeged, Korányi fasor 8-10, 6720 Szeged, Hungary, Hungary
| | - Zoltán Hegedűs
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary
- Department of Biochemistry and Medical Chemistry, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
| | - István Nagy
- Institute of Biochemistry, Biological Research Centre the Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary
- Seqomics Biotechnology Ltd, Vállalkozók útja 7, 6782 Mórahalom, Hungary
| | - Rohit Arora
- Department of Veterinary Sciences, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
| | - Alain J Labro
- Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
- Department of Basic Medical Sciences, University of Ghent, C. Heymanslaan 10, 9000 Ghent, Belgium
| | - László Környei
- Gottsegen György National Institute of Cardiology, Haller u. 9, 1096 Budapest, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Dóm tér 12, PO Box 427, Szeged 6720, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 12, 6720 Szeged, Hungary
- MTA-SZTE Research Group for Cardiovascular Pharmacology, Hungarian Academy of Sciences, Dóm tér 12, 6720 Szeged, Hungary
| | - Róbert Sepp
- 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Semmelweis u. 8, 6725 Szeged, Hungary
| | - Balázs Ördög
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Dóm tér 12, PO Box 427, Szeged 6720, Hungary
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Gonzalez Sabater V, Rigby M, Burrone J. Voltage-Gated Potassium Channels Ensure Action Potential Shape Fidelity in Distal Axons. J Neurosci 2021; 41:5372-5385. [PMID: 34001627 PMCID: PMC8221596 DOI: 10.1523/jneurosci.2765-20.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/29/2021] [Accepted: 04/01/2021] [Indexed: 11/21/2022] Open
Abstract
The initiation and propagation of the action potential (AP) along an axon allows neurons to convey information rapidly and across distant sites. Although AP properties have typically been characterized at the soma and proximal axon, knowledge of the propagation of APs toward distal axonal domains of mammalian CNS neurons remains limited. We used genetically encoded voltage indicators (GEVIs) to image APs with submillisecond temporal resolution simultaneously at different locations along the long axons of dissociated hippocampal neurons from rat embryos of either sex. We found that APs became sharper and showed remarkable fidelity as they traveled toward distal axons, even during a high-frequency train. Blocking voltage-gated potassium channels (Kv) with 4-AP resulted in an increase in AP width in all compartments, which was stronger at distal locations and exacerbated during AP trains. We conclude that the higher levels of Kv channel activity in distal axons serve to sustain AP fidelity, conveying a reliable digital signal to presynaptic boutons.SIGNIFICANCE STATEMENT The AP represents the electrical signal carried along axons toward distant presynaptic boutons where it culminates in the release of neurotransmitters. The nonlinearities involved in this process are such that small changes in AP shape can result in large changes in neurotransmitter release. Since axons are remarkably long structures, any distortions that APs suffer along the way have the potential to translate into a significant modulation of synaptic transmission, particularly in distal domains. To avoid these issues, distal axons have ensured that signals are kept remarkably constant and insensitive to modulation during a train, despite the long distances traveled. Here, we uncover the mechanisms that allow distal axonal domains to provide a reliable and faithful digital signal to presynaptic terminals.
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Affiliation(s)
- Victoria Gonzalez Sabater
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
| | - Mark Rigby
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
| | - Juan Burrone
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom
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Bazard P, Frisina RD, Acosta AA, Dasgupta S, Bauer MA, Zhu X, Ding B. Roles of Key Ion Channels and Transport Proteins in Age-Related Hearing Loss. Int J Mol Sci 2021; 22:6158. [PMID: 34200434 PMCID: PMC8201059 DOI: 10.3390/ijms22116158] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/30/2021] [Accepted: 05/31/2021] [Indexed: 12/25/2022] Open
Abstract
The auditory system is a fascinating sensory organ that overall, converts sound signals to electrical signals of the nervous system. Initially, sound energy is converted to mechanical energy via amplification processes in the middle ear, followed by transduction of mechanical movements of the oval window into electrochemical signals in the cochlear hair cells, and finally, neural signals travel to the central auditory system, via the auditory division of the 8th cranial nerve. The majority of people above 60 years have some form of age-related hearing loss, also known as presbycusis. However, the biological mechanisms of presbycusis are complex and not yet fully delineated. In the present article, we highlight ion channels and transport proteins, which are integral for the proper functioning of the auditory system, facilitating the diffusion of various ions across auditory structures for signal transduction and processing. Like most other physiological systems, hearing abilities decline with age, hence, it is imperative to fully understand inner ear aging changes, so ion channel functions should be further investigated in the aging cochlea. In this review article, we discuss key various ion channels in the auditory system and how their functions change with age. Understanding the roles of ion channels in auditory processing could enhance the development of potential biotherapies for age-related hearing loss.
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Affiliation(s)
- Parveen Bazard
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Robert D. Frisina
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
- Department Communication Sciences and Disorders, College of Behavioral & Communication Sciences, Tampa, FL 33620, USA
| | - Alejandro A. Acosta
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Sneha Dasgupta
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Mark A. Bauer
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Xiaoxia Zhu
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
| | - Bo Ding
- Department of Medical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620, USA; (P.B.); (A.A.A.); (S.D.); (M.A.B.); (X.Z.); (B.D.)
- Global Center for Hearing and Speech Research, University of South Florida, Tampa, FL 33612, USA
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Scheiblich H, Steinert JR. Nitrergic modulation of neuronal excitability in the mouse hippocampus is mediated via regulation of Kv2 and voltage-gated sodium channels. Hippocampus 2021; 31:1020-1038. [PMID: 34047430 DOI: 10.1002/hipo.23366] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/10/2021] [Accepted: 05/19/2021] [Indexed: 12/21/2022]
Abstract
Regulation of neuronal activity is a necessity for communication and information transmission. Many regulatory processes which have been studied provide a complex picture of how neurons can respond to permanently changing functional requirements. One such activity-dependent mechanism involves signaling mediated by nitric oxide (NO). Within the brain, NO is generated in response to neuronal NO synthase (nNOS) activation but NO-dependent pathways regulating neuronal excitability in the hippocampus remain to be fully elucidated. This study was set out to systematically assess the effects of NO on ion channel activities and intrinsic excitabilities of pyramidal neurons within the CA1 region of the mouse hippocampus. We characterized whole-cell potassium and sodium currents, both involved in action potential (AP) shaping and propagation and determined NO-mediated changes in excitabilities and AP waveforms. Our data describe a novel signaling by which NO, in a cGMP-independent manner, suppresses voltage-gated Kv2 potassium and voltage-gated sodium channel activities, thereby widening AP waveforms and reducing depolarization-induced AP firing rates. Our data show that glutathione, which possesses denitrosylating activity, is sufficient to prevent the observed nitrergic effects on potassium and sodium channels, whereas inhibition of cGMP signaling is also sufficient to abolish NO modulation of sodium currents. We propose that NO suppresses both ion channel activities via redox signaling and that an additional cGMP-mediated component is required to exert effects on sodium currents. Both mechanisms result in a dampened excitability and firing ability providing new data on nitrergic activities in the context of activity-dependent regulation of neuronal function following nNOS activation.
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Affiliation(s)
- Hannah Scheiblich
- Department of Neurodegenerative Disease and Geriatric Psychiatry/Neurology, University of Bonn Medical Center, Bonn, Germany
| | - Joern R Steinert
- Faculty of Medicine and Health Sciences, University of Nottingham, School of Life Sciences, Queen's Medical Centre, Nottingham, UK
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Bragg-Gonzalo L, De León Reyes NS, Nieto M. Genetic and activity dependent-mechanisms wiring the cortex: Two sides of the same coin. Semin Cell Dev Biol 2021; 118:24-34. [PMID: 34030948 DOI: 10.1016/j.semcdb.2021.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/27/2021] [Accepted: 05/08/2021] [Indexed: 01/17/2023]
Abstract
The cerebral cortex is responsible for the higher-order functions of the brain such as planning, cognition, or social behaviour. It provides us with the capacity to interact with and transform our world. The substrates of cortical functions are complex neural circuits that arise during development from the dynamic remodelling and progressive specialization of immature undefined networks. Here, we review the genetic and activity-dependent mechanisms of cortical wiring focussing on the importance of their interaction. Cortical circuits emerge from an initial set of neuronal types that engage in sequential forms of embryonic and postnatal activity. Such activities further complement the cells' genetic programs, increasing neuronal diversity and modifying the electrical properties while promoting selective connectivity. After a temporal window of enhanced plasticity, the main features of mature circuits are established. Failures in these processes can lead to neurodevelopmental disorders whose treatment remains elusive. However, a deeper dissection of cortical wiring will pave the way for innovative therapies.
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Affiliation(s)
- L Bragg-Gonzalo
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, (CNB-CSIC) Campus de Cantoblanco, Darwin 3, 28049 Madrid, Spain
| | - N S De León Reyes
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, (CNB-CSIC) Campus de Cantoblanco, Darwin 3, 28049 Madrid, Spain; Instituto de Neurociencias de Alicante, CSIC-UMH, 03550 San Juan de Alicante, Spain
| | - M Nieto
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, (CNB-CSIC) Campus de Cantoblanco, Darwin 3, 28049 Madrid, Spain.
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Fluorescence Fluctuation Spectroscopy enables quantification of potassium channel subunit dynamics and stoichiometry. Sci Rep 2021; 11:10719. [PMID: 34021177 PMCID: PMC8140153 DOI: 10.1038/s41598-021-90002-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/15/2021] [Indexed: 11/08/2022] Open
Abstract
Voltage-gated potassium (Kv) channels are a family of membrane proteins that facilitate K+ ion diffusion across the plasma membrane, regulating both resting and action potentials. Kv channels comprise four pore-forming α subunits, each with a voltage sensing domain, and they are regulated by interaction with β subunits such as those belonging to the KCNE family. Here we conducted a comprehensive biophysical characterization of stoichiometry and protein diffusion across the plasma membrane of the epithelial KCNQ1-KCNE2 complex, combining total internal reflection fluorescence (TIRF) microscopy and a series of complementary Fluorescence Fluctuation Spectroscopy (FFS) techniques. Using this approach, we found that KCNQ1-KCNE2 has a predominant 4:4 stoichiometry, while non-bound KCNE2 subunits are mostly present as dimers in the plasma membrane. At the same time, we identified unique spatio-temporal diffusion modalities and nano-environment organization for each channel subunit. These findings improve our understanding of KCNQ1-KCNE2 channel function and suggest strategies for elucidating the subunit stoichiometry and forces directing localization and diffusion of ion channel complexes in general.
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