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Oblasov I, Bal NV, Shvadchenko AM, Fortygina P, Idzhilova OS, Balaban PM, Nikitin ES. Ca 2+-permeable AMPA receptor-dependent silencing of neurons by KCa3.1 channels during epileptiform activity. Biochem Biophys Res Commun 2024; 733:150434. [PMID: 39068818 DOI: 10.1016/j.bbrc.2024.150434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Accepted: 07/20/2024] [Indexed: 07/30/2024]
Abstract
Ca2+-activated KCa3.1 channels are known to contribute to slow afterhyperpolarization in pyramidal neurons of several brain areas, while Ca2+-permeable AMPA receptors (CP-AMPARs) may provide a subthreshold source of Ca2+ elevation in the cytoplasm. The functionality of these two types of channels has also been shown to be altered by epileptic disorders. However, the link between KCa3.1 channels and CP-AMPARs is poorly understood, and their potential interaction in epilepsy remains unclear. Here, we address this issue by overexpressing the KCNN4 gene, which encodes the KCa3.1 channel, using patch clamp, imaging, and channel blockers in an in vitro model of epilepsy in neuronal culture. We show that KCNN4 overexpression causes strong hyperpolarization and substantial silencing of neurons during epileptiform activity events, which also prevents KCNN4-positive neurons from firing action potentials (APs) during experimentally induced status epilepticus. Intracellular blocker application experiments showed that the amplitude of hyperpolarization was strongly dependent on CP-AMPARs, but not on NMDA receptors. Taken together, our data strongly suggest that subthreshold Ca2+ elevation produced by CP-AMPARs can trigger KCa3.1 channels to hyperpolarize neurons and protect them from seizures.
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Affiliation(s)
- Ilya Oblasov
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Natalia V Bal
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Anastasya M Shvadchenko
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Polina Fortygina
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Olga S Idzhilova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Pavel M Balaban
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485
| | - Evgeny S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerova str., Moscow, Russia, 117485.
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2
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Constantin S, Quignon C, Pizano K, Shostak DM, Wray S. Vasoactive intestinal peptide excites GnRH neurons via KCa3.1, a potential player in the slow afterhyperpolarization current. Front Cell Neurosci 2024; 18:1354095. [PMID: 38633445 PMCID: PMC11021707 DOI: 10.3389/fncel.2024.1354095] [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: 12/11/2023] [Accepted: 03/05/2024] [Indexed: 04/19/2024] Open
Abstract
Vasoactive intestinal peptide (VIP) is an important component of the suprachiasmatic nucleus (SCN) which relays circadian information to neuronal populations, including GnRH neurons. Human and animal studies have shown an impact of disrupted daily rhythms (chronic shift work, temporal food restriction, clock gene disruption) on both male and female reproduction and fertility. To date, how VIP modulates GnRH neurons remains unknown. Calcium imaging and electrophysiology on primary GnRH neurons in explants and adult mouse brain slice, respectively, were used to address this question. We found VIP excites GnRH neurons via the VIP receptor, VPAC2. The downstream signaling pathway uses both Gs protein/adenylyl cyclase/protein kinase A (PKA) and phospholipase C/phosphatidylinositol 4,5-bisphosphate (PIP2) depletion. Furthermore, we identified a UCL2077-sensitive target, likely contributing to the slow afterhyperpolarization current (IAHP), as the PKA and PIP2 depletion target, and the KCa3.1 channel as a specific target. Thus, VIP/VPAC2 provides an example of Gs protein-coupled receptor-triggered excitation in GnRH neurons, modulating GnRH neurons likely via the slow IAHP. The possible identification of KCa3.1 in the GnRH neuron slow IAHP may provide a new therapeutical target for fertility treatments.
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Affiliation(s)
| | | | | | | | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, MD, United States
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3
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Van NTH, Kim WK, Nam JH. Challenges in the Therapeutic Targeting of KCa Channels: From Basic Physiology to Clinical Applications. Int J Mol Sci 2024; 25:2965. [PMID: 38474212 PMCID: PMC10932353 DOI: 10.3390/ijms25052965] [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: 12/15/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 03/14/2024] Open
Abstract
Calcium-activated potassium (KCa) channels are ubiquitously expressed throughout the body and are able to regulate membrane potential and intracellular calcium concentrations, thereby playing key roles in cellular physiology and signal transmission. Consequently, it is unsurprising that KCa channels have been implicated in various diseases, making them potential targets for pharmaceutical interventions. Over the past two decades, numerous studies have been conducted to develop KCa channel-targeting drugs, including those for disorders of the central and peripheral nervous, cardiovascular, and urinary systems and for cancer. In this review, we synthesize recent findings regarding the structure and activating mechanisms of KCa channels. We also discuss the role of KCa channel modulators in therapeutic medicine. Finally, we identify the major reasons behind the delay in bringing these modulators to the pharmaceutical market and propose new strategies to promote their application.
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Affiliation(s)
- Nhung Thi Hong Van
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
- Department of Internal Medicine, Graduate School of Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
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Nikitin ES, Postnikova TY, Proskurina EY, Borodinova AA, Ivanova V, Roshchin MV, Smirnova MP, Kelmanson I, Belousov VV, Balaban PM, Zaitsev AV. Overexpression of KCNN4 channels in principal neurons produces an anti-seizure effect without reducing their coding ability. Gene Ther 2024; 31:144-153. [PMID: 37968509 DOI: 10.1038/s41434-023-00427-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 10/13/2023] [Accepted: 10/24/2023] [Indexed: 11/17/2023]
Abstract
Gene therapy offers a potential alternative to the surgical treatment of epilepsy, which affects millions of people and is pharmacoresistant in ~30% of cases. Aimed at reducing the excitability of principal neurons, the engineered expression of K+ channels has been proposed as a treatment due to the outstanding ability of K+ channels to hyperpolarize neurons. However, the effects of K+ channel overexpression on cell physiology remain to be investigated. Here we report an adeno-associated virus (AAV) vector designed to reduce epileptiform activity specifically in excitatory pyramidal neurons by expressing the human Ca2+-gated K+ channel KCNN4 (KCa3.1). Electrophysiological and pharmacological experiments in acute brain slices showed that KCNN4-transduced cells exhibited a Ca2+-dependent slow afterhyperpolarization that significantly decreased the ability of KCNN4-positive neurons to generate high-frequency spike trains without affecting their lower-frequency coding ability and action potential shapes. Antiepileptic activity tests showed potent suppression of pharmacologically induced seizures in vitro at both single cell and local field potential levels with decreased spiking during ictal discharges. Taken together, our findings strongly suggest that the AAV-based expression of the KCNN4 channel in excitatory neurons is a promising therapeutic intervention as gene therapy for epilepsy.
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Affiliation(s)
- Evgeny S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, RAS, 117485, Moscow, Russia.
| | - Tatiana Y Postnikova
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, Saint Petersburg, Russia
| | - Elena Y Proskurina
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, Saint Petersburg, Russia
| | | | - Violetta Ivanova
- Institute of Higher Nervous Activity and Neurophysiology, RAS, 117485, Moscow, Russia
| | - Matvey V Roshchin
- Institute of Higher Nervous Activity and Neurophysiology, RAS, 117485, Moscow, Russia
| | - Maria P Smirnova
- Institute of Higher Nervous Activity and Neurophysiology, RAS, 117485, Moscow, Russia
| | - Ilya Kelmanson
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997, Moscow, Russia
| | - Vsevolod V Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Moscow, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997, Moscow, Russia
- Federal Center of Brain Research and Neurotechnologies, Federal Medical Biological Agency, 117997, Moscow, Russia
- Life Improvement by Future Technologies (LIFT) Center, 143025, Moscow, Russia
| | - Pavel M Balaban
- Institute of Higher Nervous Activity and Neurophysiology, RAS, 117485, Moscow, Russia
| | - Aleksey V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, 194223, Saint Petersburg, Russia.
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Hosoi Y, Akita T, Watanabe M, Ito T, Miyajima H, Fukuda A. Taurine depletion during fetal and postnatal development blunts firing responses of neocortical layer II/III pyramidal neurons. Front Mol Neurosci 2022; 15:806798. [PMID: 36466806 PMCID: PMC9712787 DOI: 10.3389/fnmol.2022.806798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 10/27/2022] [Indexed: 08/22/2023] Open
Abstract
Fetal and infant brains are rich in maternally derived taurine. We previously demonstrated that taurine action regulates the cation-chloride cotransporter activity and the differentiation and radial migration of pyramidal neuron progenitors in the developing neocortex of rodent fetuses. Here we examined the effects of fetal and infantile taurine depletion caused by knockout of the taurine transporter Slc6a6 on firing properties of layer II/III pyramidal neurons in the mouse somatosensory cortex at 3 weeks of postnatal age, using the whole-cell patch-clamp technique. The membrane excitability under resting conditions was similar between the neurons in knockout mice and those in wildtype littermates. However, the frequency of repetitive spike firing during moderate current injection was significantly lower, along with lower membrane voltage levels during interspike intervals in knockout neurons. When strong currents were injected, by which repetitive firing was rapidly abolished due to inactivation of voltage-gated Na+ channels in wildtype neurons, the firing in knockout neurons lasted for a much longer period than in wildtype neurons. This was due to much lower membrane voltage levels during interspike intervals in knockout neurons, promoting greater recovery of voltage-gated Na+ channels from inactivation. Thus, taurine depletion in pyramidal neurons blunted neuronal responses to external stimuli through increasing the stability of repetitive firing, presumably mediated by larger increases in membrane K+ conductance during interspike intervals.
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Affiliation(s)
- Yasushi Hosoi
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- Division of Health Science, Department of Basic Nursing, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Takashi Ito
- Department of Biosciences and Biotechnology, Fukui Prefectural University, Fukui, Japan
| | - Hiroaki Miyajima
- First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Tiwari MN, Mohan S, Biala Y, Shor O, Benninger F, Yaari Y. Corticotropin Releasing Factor Mediates K Ca3.1 Inhibition, Hyperexcitability, and Seizures in Acquired Epilepsy. J Neurosci 2022; 42:5843-5859. [PMID: 35732494 PMCID: PMC9337610 DOI: 10.1523/jneurosci.2475-21.2022] [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: 12/15/2021] [Revised: 04/11/2022] [Accepted: 04/22/2022] [Indexed: 01/29/2023] Open
Abstract
Temporal lobe epilepsy (TLE), the most common focal seizure disorder in adults, can be instigated in experimental animals by convulsant-induced status epilepticus (SE). Principal hippocampal neurons from SE-experienced epileptic male rats (post-SE neurons) display markedly augmented spike output compared with neurons from nonepileptic animals (non-SE neurons). This enhanced firing results from a cAMP-dependent protein kinase A-mediated inhibition of KCa3.1, a subclass of Ca2+-gated K+ channels generating the slow afterhyperpolarizing Ca2+-gated K+ current (IsAHP). The inhibition of KCa3.1 in post-SE neurons leads to a marked reduction in amplitude of the IsAHP that evolves during repetitive firing, as well as in amplitude of the associated Ca2+-dependent component of the slow afterhyperpolarization potential (KCa-sAHP). Here we show that KCa3.1 inhibition in post-SE neurons is induced by corticotropin releasing factor (CRF) through its Type 1 receptor (CRF1R). Acute application of CRF1R antagonists restores KCa3.1 activity in post-SE neurons, normalizing KCa-sAHP/IsAHP amplitudes and neuronal spike output, without affecting these variables in non-SE neurons. Moreover, pharmacological antagonism of CRF1Rs in vivo reduces the frequency of spontaneous recurrent seizures in post-SE chronically epileptic rats. These findings may provide a new vista for treating TLE.SIGNIFICANCE STATEMENT Epilepsy, a common neurologic disorder, often develops following a brain insult. Identifying key cellular mechanisms underlying acquired epilepsy is critical for developing effective antiepileptic therapies. In an experimental model of acquired epilepsy, principal hippocampal neurons manifest hyperexcitability because of downregulation of KCa3.1, a subtype of Ca2+-gated K+ ion channels. We show that KCa3.1 downregulation is mediated by corticotropin releasing factor (CRF) acting through its Type 1 receptor (CRF1R). Congruently, acute application of selective CRF1R antagonists restores KCa3.1 channel activity, leading to normalization of neuronal excitability. In the same model, injection of a CRF1R antagonist to epileptic animals markedly decreases the frequency of electrographic seizures. Therefore, targeting CRF1Rs may provide a new strategy in the treatment of acquired epilepsy.
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Affiliation(s)
- Manindra Nath Tiwari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, Israel 9112102
| | - Sandesh Mohan
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, Israel 9112102
| | - Yoav Biala
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, Israel 9112102
| | - Oded Shor
- Felsenstein Medical Research Center, Beilinson Hospital, Petach Tikva, Israel 4941492
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel 6997801
| | - Felix Benninger
- Felsenstein Medical Research Center, Beilinson Hospital, Petach Tikva, Israel 4941492
- Department of Neurology, Rabin Medical Center, Petach Tikva, Israel 49141492
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel 6997801
| | - Yoel Yaari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, Israel 9112102
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Ierusalimsky VN, Balaban PM, Nikitin ES. Nav1.6 but not KCa3.1 channels contribute to heterogeneity in coding abilities and dynamics of action potentials in the L5 neocortical pyramidal neurons. Biochem Biophys Res Commun 2022; 615:102-108. [DOI: 10.1016/j.bbrc.2022.05.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/14/2022] [Indexed: 12/16/2022]
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Nikitin ES, Balaban PM, Zaitsev AV. Prospects for Gene Therapy of Epilepsy Using Calcium-Acivated Potassium Channel Vectors. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022040111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Sokolov RA, Mukhina IV. Spontaneous Ca 2+ events are linked to the development of neuronal firing during maturation in mice primary hippocampal culture cells. Arch Biochem Biophys 2022; 727:109330. [PMID: 35750097 DOI: 10.1016/j.abb.2022.109330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/21/2022] [Accepted: 06/19/2022] [Indexed: 11/30/2022]
Abstract
Calcium is one of the most vital intracellular secondary messengers that tightly regulates a variety of cell physiology processes, especially in the brain. Using a fluorescent Ca2+-sensitive Oregon Green probe, we revealed three different amplitude distributions of spontaneous Ca2+ events (SCEs) in neurons between 15 and 26 days in vitro (DIV) culture maturation. We detected a series of amplitude events: micro amplitude SCE (microSCE) 25% increase from the baseline, intermediate amplitude SCE (interSCE) as 25-75%, and macro amplitude SCE (macroSCE) - over 75%. The SCEs were fully dependent on extracellular Ca2+ and neuronal network activity and vanished in the Ca2+-free solution, 10 mM Mg2+-block, or in the presence of voltage-gated Na+-channel blocker, tetrodotoxin. Combined patch-clamp and Ca2+-imaging techniques revealed that microSCE match single action potential (AP), interSCE - burst of 3-12 APs, and macroSCE - 'superburst' of 10+ APs. MicroSCEs were blocked by a common α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainic acid (KA) receptor antagonist, CNQX. The γ-aminobutyric acid (GABA) A-type receptor (GABAAR) picrotoxin blockade and L-type voltage-dependent Ca2+-channel inhibitor diltiazem significantly reduced microSCE frequency. InterSCEs were inhibited by CNQX, but picrotoxin treatment significantly increased its amplitude. The N-methyl-d-aspartate (NMDA) receptor antagonist, D-APV, voltage-gated K+-channel blocker, tetraethylammonium, noticeably suppressed interSCE amplitude. We also demonstrate that macroSCEs were AMPA/KA receptor-independent.
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Affiliation(s)
- Rostislav A Sokolov
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia; In Vivo Research Center, Sirius University of Science and Technology, Olympic Avenue, 1, Sochi, Russia.
| | - Irina V Mukhina
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia; Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia.
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Sahu G, Turner RW. The Molecular Basis for the Calcium-Dependent Slow Afterhyperpolarization in CA1 Hippocampal Pyramidal Neurons. Front Physiol 2022; 12:759707. [PMID: 35002757 PMCID: PMC8730529 DOI: 10.3389/fphys.2021.759707] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 12/02/2022] Open
Abstract
Neuronal signal transmission depends on the frequency, pattern, and timing of spike output, each of which are shaped by spike afterhyperpolarizations (AHPs). There are classically three post-spike AHPs of increasing duration categorized as fast, medium and slow AHPs that hyperpolarize a cell over a range of 10 ms to 30 s. Intensive early work on CA1 hippocampal pyramidal cells revealed that all three AHPs incorporate activation of calcium-gated potassium channels. The ionic basis for a fAHP was rapidly attributed to the actions of big conductance (BK) and the mAHP to small conductance (SK) or Kv7 potassium channels. In stark contrast, the ionic basis for a prominent slow AHP of up to 30 s duration remained an enigma for over 30 years. Recent advances in pharmacological, molecular, and imaging tools have uncovered the expression of a calcium-gated intermediate conductance potassium channel (IK, KCa3.1) in central neurons that proves to contribute to the slow AHP in CA1 hippocampal pyramidal cells. Together the data show that the sAHP arises in part from a core tripartite complex between Cav1.3 (L-type) calcium channels, ryanodine receptors, and IK channels at endoplasmic reticulum-plasma membrane junctions. Work on the sAHP in CA1 pyramidal neurons has again quickened pace, with identified contributions by both IK channels and the Na-K pump providing answers to several mysteries in the pharmacological properties of the sAHP.
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Affiliation(s)
- Giriraj Sahu
- National Institute of Pharmaceutical Education and Research Ahmedabad, Ahmedabad, India
| | - Ray W Turner
- Department Cell Biology & Anatomy, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
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KCa3.1 in diabetic kidney disease. Curr Opin Nephrol Hypertens 2022; 31:129-134. [PMID: 34710887 DOI: 10.1097/mnh.0000000000000751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Diabetic kidney disease (DKD) is a significant health concern. Innovative strategies to prevent or limit the progression of DKD are urgently needed due to the limitation of existing treatments. KCa3.1, a potassium channel, is involved in a range of biological processes from cell survival to cell death. This review summarizes the current knowledge on the pathophysiological functions of the KCa3.1 channel, specifically its involvement in maintaining mitochondrial function. More specifically, the therapeutic potential of targeting KCa3.1 in DKD is systematically discussed in the review. RECENT FINDINGS Mitochondrial dysfunction contributes to the development and progression of DKD. Accumulating evidence indicates that KCa3.1 dysregulation plays a crucial role in mitochondrial dysfunction, in addition to driving cellular activation, proliferation and inflammation. Recent studies demonstrate that KCa3.1 deficiency improves diabetes-induced mitochondrial dysfunction in DKD, which is attributed to modulation of mitochondrial quality control through mitigating the altered mitochondrial dynamics and restoring abnormal BNIP3-mediated mitophagy. SUMMARY Based on its role in fibrosis, inflammation and mitochondrial dysfunction, pharmacological inhibition of KCa3.1 may offer a promising alternative for the treatment of DKD. Due to its safety profile in humans, the repurposing of senicapoc has the potential to expedite an urgently needed new drug in DKD.
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Laker D, Tolle F, Stegen M, Heerdegen M, Köhling R, Kirschstein T, Wolfart J. K v7 and K ir6 Channels Shape the Slow AHP in Mouse Dentate Gyrus Granule Cells and Control Burst-like Firing Behavior. Neuroscience 2021; 467:56-72. [PMID: 34048798 DOI: 10.1016/j.neuroscience.2021.05.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 11/29/2022]
Abstract
The slow afterhyperpolarizing potential (sAHP) can silence a neuron for hundreds of milliseconds. Thereby, the sAHP determines the discharge behavior of many types of neurons. In dentate granule cells (DGCs), serving as a filter into the hippocampal network, mostly tonic or adapting discharge properties have been described. As under standard whole-cell recording conditions the sAHP is inhibited, we reevaluated the intrinsic functional phenotype of DGCs and the conductances underlying the sAHP, using gramicidine-perforated patch-clamp technique. We found that in 97/113 (86%) of the DGCs, a burst of action potentials (APs) to excitation ended by a large sAHP, despite continued depolarization. This result suggests that burst-like firing is the default functional phenotype of DGCs and that sAHPs are important for it. Indeed, burst-like firing DGCs showed a significantly higher sAHP-current (IsAHP) amplitude compared to spike-frequency adapting cells (16/113 = 14%). The IsAHP was mediated by Kv7 and Kir6 channels by pharmacological inhibition using XE991 and tolbutamide, although heterogeneously among DGCs. The percent inhibition of IsAHP by these compounds also correlated with the AP number and AP burst length. Application of 100 µM nickel after XE991 and tolbutamide detected a third conductance contributing to burst-like firing and the sAHP, most likely mediated by T-type calcium channels. Lastly, medial perforant path-dentate gyrus long-term potentiation was amplified by XE991 and tolbutamide. In conclusion, the sAHP shapes intrinsic burst-like firing which, under physiological circumstances, could be controlled via cholinergic afferents and ATP metabolism.
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Affiliation(s)
- Debora Laker
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany
| | - Frederik Tolle
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany
| | - Michael Stegen
- Department of Neurosurgery, University of Freiburg, Germany
| | - Marco Heerdegen
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany
| | - Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany
| | - Timo Kirschstein
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany.
| | - Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Rostock, Germany
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13
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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