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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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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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4
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Tiwari MN, Hall BE, Terse A, Amin N, Chung MK, Kulkarni AB. ACTIVATION OF CYCLIN-DEPENDENT KINASE 5 BROADENS ACTION POTENTIALS IN HUMAN SENSORY NEURONS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543017. [PMID: 37398398 PMCID: PMC10312556 DOI: 10.1101/2023.05.31.543017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Chronic pain is one of the most devastating and unpleasant conditions, associated with many pathological conditions. Tissue or nerve injuries induce comprehensive neurobiological plasticity in nociceptive neurons, which leads to chronic pain. Recent studies suggest that cyclin-dependent kinase 5 (CDK5) in primary afferents is a key neuronal kinase that modulates nociception through phosphorylation-dependent manner under pathological conditions. However, the impact of the CDK5 on nociceptor activity especially in human sensory neurons are not known. To determine the CDK5-mediated regulation of human dorsal root ganglia (hDRG) neuronal properties, we have performed the whole-cell patch clamp recordings in neurons dissociated from hDRG. CDK5 activation induced by overexpression of p35 depolarized the resting membrane potential and reduced the rheobase currents as compared to the uninfected neurons. CDK5 activation evidently changed the shape of the action potential (AP) by increasing AP rise time, AP fall time, and AP half width. The application of a prostaglandin E2 (PG) and bradykinin (BK) cocktail in uninfected hDRG neurons induced the depolarization of RMP and the reduction of rheobase currents along with increased AP rise time. However, PG and BK applications failed to induce any further significant changes in addition to the aforementioned changes of the membrane properties and AP parameters in the p35-overexpressing group. We conclude that CDK5 activation through the overexpression of p35 in dissociated hDRG neurons broadens AP in hDRG neurons and that CDK5 may play important roles in the modulation of AP properties in human primary afferents under pathological conditions, contributing to chronic pain.
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Affiliation(s)
- Manindra Nath Tiwari
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, Maryland 21201
| | - Bradford E. Hall
- Functional Genomics Section, National Institute of Dental and Craniofacial Research
| | - Anita Terse
- Functional Genomics Section, National Institute of Dental and Craniofacial Research
| | - Niranjana Amin
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, Maryland 21201
| | - Ashok B. Kulkarni
- Functional Genomics Section, National Institute of Dental and Craniofacial Research
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Tiwari MN, Hall BE, Ton AT, Ghetti R, Terse A, Amin N, Chung MK, Kulkarni AB. Activation of cyclin-dependent kinase 5 broadens action potentials in human sensory neurons. Mol Pain 2023; 19:17448069231218353. [PMID: 37982142 PMCID: PMC10687939 DOI: 10.1177/17448069231218353] [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: 08/25/2023] [Revised: 11/06/2023] [Accepted: 11/10/2023] [Indexed: 11/21/2023] Open
Abstract
Chronic pain is one of the most devastating and unpleasant conditions, associated with many pathological states. Tissue or nerve injuries induce extensive neurobiological plasticity in nociceptive neurons, which leads to chronic pain. Recent studies suggest that cyclin-dependent kinase 5 (CDK5) in primary afferents is a key neuronal kinase that modulates nociception through phosphorylation under pathological conditions. However, the impact of the CDK5 on nociceptor activity especially in human sensory neurons is not known. To determine the CDK5-mediated regulation of human dorsal root ganglia (hDRG) neuronal properties, we have performed the whole-cell patch clamp recordings in neurons dissociated from hDRG. CDK5 activation induced by overexpression of p35 depolarized the resting membrane potential (RMP) and reduced the rheobase currents as compared to the control neurons. CDK5 activation changed the shape of the action potential (AP) by increasing AP -rise time, -fall time, and -half width. The application of a prostaglandin E2 (PG) and bradykinin (BK) cocktail in control hDRG neurons induced the depolarization of RMP and the reduction of rheobase currents along with increased AP rise time. However, PG and BK applications failed to induce any significant changes in the p35-overexpressing group. We conclude that, in dissociated hDRGs neurons, CDK5 activation through the overexpression of p35 broadens the AP and that CDK5 may play important roles in the modulation of AP properties in human primary afferents under the condition in which CDK5 is upregulated, contributing to chronic pain.
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Affiliation(s)
- Manindra Nath Tiwari
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, United States
| | - Bradford E Hall
- Functional Genomics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States
| | | | - Re Ghetti
- AnaBios, San Diego, CA, United States
| | - Anita Terse
- Functional Genomics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States
| | - Niranjana Amin
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, United States
| | - Ashok B Kulkarni
- Functional Genomics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States
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6
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Lin Y, Zhao YJ, Zhang HL, Hao WJ, Zhu RD, Wang Y, Hu W, Zhou RP. Regulatory role of KCa3.1 in immune cell function and its emerging association with rheumatoid arthritis. Front Immunol 2022; 13:997621. [PMID: 36275686 PMCID: PMC9580404 DOI: 10.3389/fimmu.2022.997621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/16/2022] [Indexed: 11/25/2022] Open
Abstract
Rheumatoid arthritis (RA) is a common autoimmune disease characterized by chronic inflammation. Immune dysfunction is an essential mechanism in the pathogenesis of RA and directly linked to synovial inflammation and cartilage/bone destruction. Intermediate conductance Ca2+-activated K+ channel (KCa3.1) is considered a significant regulator of proliferation, differentiation, and migration of immune cells by mediating Ca2+ signal transduction. Earlier studies have demonstrated abnormal activation of KCa3.1 in the peripheral blood and articular synovium of RA patients. Moreover, knockout of KCa3.1 reduced the severity of synovial inflammation and cartilage damage to a significant extent in a mouse collagen antibody-induced arthritis (CAIA) model. Accumulating evidence implicates KCa3.1 as a potential therapeutic target for RA. Here, we provide an overview of the KCa3.1 channel and its pharmacological properties, discuss the significance of KCa3.1 in immune cells and feasibility as a drug target for modulating the immune balance, and highlight its emerging role in pathological progression of RA.
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Affiliation(s)
- Yi Lin
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Ying-Jie Zhao
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
| | - Hai-Lin Zhang
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Wen-Juan Hao
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Ren-Di Zhu
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Yan Wang
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Wei Hu
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- The Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Medical University, Hefei, China
- *Correspondence: Wei Hu, ; Ren-Peng Zhou,
| | - Ren-Peng Zhou
- Department of Clinical Pharmacology, The Second Hospital of Anhui Medical University, Hefei, China
- The Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Medical University, Hefei, China
- *Correspondence: Wei Hu, ; Ren-Peng Zhou,
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7
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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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8
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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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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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Henley JM, Nair JD, Seager R, Yucel BP, Woodhall G, Henley BS, Talandyte K, Needs HI, Wilkinson KA. Kainate and AMPA receptors in epilepsy: Cell biology, signalling pathways and possible crosstalk. Neuropharmacology 2021; 195:108569. [PMID: 33915142 DOI: 10.1016/j.neuropharm.2021.108569] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/13/2021] [Accepted: 04/09/2021] [Indexed: 02/06/2023]
Abstract
Epilepsy is caused when rhythmic neuronal network activity escapes normal control mechanisms, resulting in seizures. There is an extensive and growing body of evidence that the onset and maintenance of epilepsy involves alterations in the trafficking, synaptic surface expression and signalling of kainate and AMPA receptors (KARs and AMPARs). The KAR subunit GluK2 and AMPAR subunit GluA2 are key determinants of the properties of their respective assembled receptors. Both subunits are subject to extensive protein interactions, RNA editing and post-translational modifications. In this review we focus on the cell biology of GluK2-containing KARs and GluA2-containing AMPARs and outline how their regulation and dysregulation is implicated in, and affected by, seizure activity. Further, we discuss role of KARs in regulating AMPAR surface expression and plasticity, and the relevance of this to epilepsy. This article is part of the special issue on 'Glutamate Receptors - Kainate receptors'.
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Affiliation(s)
- Jeremy M Henley
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK; Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia.
| | - Jithin D Nair
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Richard Seager
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Busra P Yucel
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Gavin Woodhall
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, UK
| | - Benjamin S Henley
- Faculty of Medical Sciences, The Medical School, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK
| | - Karolina Talandyte
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Hope I Needs
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Kevin A Wilkinson
- School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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11
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Mohan S, Tiwari MN, Stanojević M, Biala Y, Yaari Y. Muscarinic regulation of the neuronal Na + /K + -ATPase in rat hippocampus. J Physiol 2021; 599:3735-3754. [PMID: 34148230 DOI: 10.1113/jp281460] [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: 02/02/2021] [Accepted: 06/16/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Stimulation of postsynaptic muscarinic receptors was shown to excite principal hippocampal neurons by modulating several membrane ion conductances. We show here that activation of postsynaptic muscarinic receptors also causes neuronal excitation by inhibiting Na+ /K+ -ATPase activity. Muscarinic Na+ /K+ -ATPase inhibition is mediated by two separate signalling pathways that lead downstream to enhanced Na+ /K+ -ATPase phosphorylation by activating protein kinase C and protein kinase G. Muscarinic excitation through Na+ /K+ -ATPase inhibition is probably involved in cholinergic modulation of hippocampal activity and may turn out to be a widespread mechanism of neuronal excitation in the brain. ABSTRACT Stimulation of muscarinic cholinergic receptors on principal hippocampal neurons enhances intrinsic neuronal excitability by modulating several membrane ion conductances. The electrogenic Na+ /K+ -ATPase (NKA; the 'Na+ pump') is a ubiquitous regulator of intrinsic neuronal excitability, generating a hyperpolarizing current to thwart excessive neuronal firing. Using electrophysiological and pharmacological methodologies in rat hippocampal slices, we show that neuronal NKA pumping activity is also subjected to cholinergic regulation. Stimulation of postsynaptic muscarinic, but not nicotinic, cholinergic receptors activates membrane-bound phospholipase C and hydrolysis of membrane-integral phosphatidylinositol 4,5-bisphosphate into diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3 ). Along one signalling pathway, DAG activates protein kinase C (PKC). Along a second signalling pathway, IP3 causes Ca2+ release from the endoplasmic reticulum, facilitating nitric oxide (NO) production. The rise in NO levels stimulates cGMP synthesis by guanylate-cyclase, activating protein kinase G (PKG). The two pathways converge to cause partial NKA inhibition through enzyme phosphorylation by PKC and PKG, leading to a marked increase in intrinsic neuronal excitability. This novel mechanism of neuronal NKA regulation probably contributes to the cholinergic modulation of hippocampal activity in spatial navigation, learning and memory.
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Affiliation(s)
- Sandesh Mohan
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Manindra Nath Tiwari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Marija Stanojević
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Yoav Biala
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Yoel Yaari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
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12
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Borgini M, Mondal P, Liu R, Wipf P. Chemical modulation of Kv7 potassium channels. RSC Med Chem 2021; 12:483-537. [PMID: 34046626 PMCID: PMC8128042 DOI: 10.1039/d0md00328j] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/01/2020] [Indexed: 01/10/2023] Open
Abstract
The rising interest in Kv7 modulators originates from their ability to evoke fundamental electrophysiological perturbations in a tissue-specific manner. A large number of therapeutic applications are, in part, based on the clinical experience with two broad-spectrum Kv7 agonists, flupirtine and retigabine. Since precise molecular structures of human Kv7 channel subtypes in closed and open states have only very recently started to emerge, computational studies have traditionally been used to analyze binding modes and direct the development of more potent and selective Kv7 modulators with improved safety profiles. Herein, the synthetic and medicinal chemistry of small molecule modulators and the representative biological properties are summarized. Furthermore, new therapeutic applications supported by in vitro and in vivo assay data are suggested.
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Affiliation(s)
- Matteo Borgini
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Pravat Mondal
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Ruiting Liu
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
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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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14
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Zhang J, Zhang C, Chen X, Wang B, Ma W, Yang Y, Zheng R, Huang Z. PKA-RIIβ autophosphorylation modulates PKA activity and seizure phenotypes in mice. Commun Biol 2021; 4:263. [PMID: 33649504 PMCID: PMC7921646 DOI: 10.1038/s42003-021-01748-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 12/22/2020] [Indexed: 11/20/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is one of the most common and intractable neurological disorders in adults. Dysfunctional PKA signaling is causally linked to the TLE. However, the mechanism underlying PKA involves in epileptogenesis is still poorly understood. In the present study, we found the autophosphorylation level at serine 114 site (serine 112 site in mice) of PKA-RIIβ subunit was robustly decreased in the epileptic foci obtained from both surgical specimens of TLE patients and seizure model mice. The p-RIIβ level was negatively correlated with the activities of PKA. Notably, by using a P-site mutant that cannot be autophosphorylated and thus results in the released catalytic subunit to exert persistent phosphorylation, an increase in PKA activities through transduction with AAV-RIIβ-S112A in hippocampal DG granule cells decreased mIPSC frequency but not mEPSC, enhanced neuronal intrinsic excitability and seizure susceptibility. In contrast, a reduction of PKA activities by RIIβ knockout led to an increased mIPSC frequency, a reduction in neuronal excitability, and mice less prone to experimental seizure onset. Collectively, our data demonstrated that the autophosphorylation of RIIβ subunit plays a critical role in controlling neuronal and network excitabilities by regulating the activities of PKA, providing a potential therapeutic target for TLE.
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Affiliation(s)
- Jingliang Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, China
| | - Chenyu Zhang
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Xiaoling Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, China
| | - Bingwei Wang
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Weining Ma
- Department of Neurology, Shengjing Hospital Affiliated to China Medical University, Shenyang, China
| | - Yang Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University College of Pharmacy, West Lafayette, IN, USA
| | - Ruimao Zheng
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China.
- Neuroscience Research Institute, Peking University, Beijing, China.
- Key Laboratory for Neuroscience, Ministry of Education, Beijing, China.
- Key Laboratory for Neuroscience of National Health Commission, Beijing, China.
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, China.
- Key Laboratory for Neuroscience, Ministry of Education, Beijing, China.
- Key Laboratory for Neuroscience of National Health Commission, Beijing, China.
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15
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Gavrilovici C, Jiang Y, Kiroski I, Sterley TL, Vandal M, Bains J, Park SK, Rho JM, Teskey GC, Nguyen MD. Behavioral Deficits in Mice with Postnatal Disruption of Ndel1 in Forebrain Excitatory Neurons: Implications for Epilepsy and Neuropsychiatric Disorders. Cereb Cortex Commun 2021; 2:tgaa096. [PMID: 33615226 PMCID: PMC7876307 DOI: 10.1093/texcom/tgaa096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 12/11/2020] [Accepted: 12/28/2020] [Indexed: 12/30/2022] Open
Abstract
Dysfunction of nuclear distribution element-like 1 (Ndel1) is associated with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment and with seizures as comorbidity. The levels of Ndel1 are also altered in human and models with epilepsy, a chronic condition whose hallmark feature is the occurrence of spontaneous recurrent seizures and is typically associated with comorbid conditions including learning and memory deficits, anxiety, and depression. In this study, we analyzed the behaviors of mice postnatally deficient for Ndel1 in forebrain excitatory neurons (Ndel1 CKO) that exhibit spatial learning and memory deficits, seizures, and shortened lifespan. Ndel1 CKO mice underperformed in species-specific tasks, that is, the nest building, open field, Y maze, forced swim, and dry cylinder tasks. We surveyed the expression and/or activity of a dozen molecules related to Ndel1 functions and found changes that may contribute to the abnormal behaviors. Finally, we tested the impact of Reelin glycoprotein that shows protective effects in the hippocampus of Ndel1 CKO, on the performance of the mutant animals in the nest building task. Our study highlights the importance of Ndel1 in the manifestation of species-specific animal behaviors that may be relevant to our understanding of the clinical conditions shared between neuropsychiatric disorders and epilepsy.
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Affiliation(s)
- Cezar Gavrilovici
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - Yulan Jiang
- Departments of Clinical Neurosciences, Cell Biology and Anatomy, and Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Calgary, AB T2N 4N1, Canada
| | - Ivana Kiroski
- Departments of Clinical Neurosciences, Cell Biology and Anatomy, and Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Calgary, AB T2N 4N1, Canada
| | - Toni-Lee Sterley
- Departments of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Milene Vandal
- Departments of Clinical Neurosciences, Cell Biology and Anatomy, and Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Calgary, AB T2N 4N1, Canada
| | - Jaideep Bains
- Departments of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Sang Ki Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Jong M Rho
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - G Campbell Teskey
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, Calgary, AB T2N 4N1, Canada
| | - Minh Dang Nguyen
- Departments of Clinical Neurosciences, Cell Biology and Anatomy, and Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Calgary, AB T2N 4N1, Canada
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16
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Palomba NP, Martinello K, Cocozza G, Casciato S, Mascia A, Di Gennaro G, Morace R, Esposito V, Wulff H, Limatola C, Fucile S. ATP-evoked intracellular Ca 2+ transients shape the ionic permeability of human microglia from epileptic temporal cortex. J Neuroinflammation 2021; 18:44. [PMID: 33588880 PMCID: PMC7883449 DOI: 10.1186/s12974-021-02096-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 02/02/2021] [Indexed: 12/18/2022] Open
Abstract
Background Intracellular Ca2+ modulates several microglial activities, such as proliferation, migration, phagocytosis, and inflammatory mediator secretion. Extracellular ATP, the levels of which significantly change during epileptic seizures, activates specific receptors leading to an increase of intracellular free Ca2+ concentration ([Ca2+]i). Here, we aimed to functionally characterize human microglia obtained from cortices of subjects with temporal lobe epilepsy, focusing on the Ca2+-mediated response triggered by purinergic signaling. Methods Fura-2 based fluorescence microscopy was used to measure [Ca2+]i in primary cultures of human microglial cells obtained from surgical specimens. The perforated patch-clamp technique, which preserves the cytoplasmic milieu, was used to measure ATP-evoked Ca2+-dependent whole-cell currents. Results In human microglia extracellular ATP evoked [Ca2+]i increases depend on Ca2+ entry from the extracellular space and on Ca2+ mobilization from intracellular compartments. Extracellular ATP also induced a transient fivefold potentiation of the total transmembrane current, which was completely abolished when [Ca2+]i increases were prevented by removing external Ca2+ and using an intracellular Ca2+ chelator. TRAM-34, a selective KCa3.1 blocker, significantly reduced the ATP-induced current potentiation but did not abolish it. The removal of external Cl− in the presence of TRAM-34 further lowered the ATP-evoked effect. A direct comparison between the ATP-evoked mean current potentiation and mean Ca2+ transient amplitude revealed a linear correlation. Treatment of microglial cells with LPS for 48 h did not prevent the ATP-induced Ca2+ mobilization but completely abolished the ATP-mediated current potentiation. The absence of the Ca2+-evoked K+ current led to a less sustained ATP-evoked Ca2+ entry, as shown by the faster Ca2+ transient kinetics observed in LPS-treated microglia. Conclusions Our study confirms a functional role for KCa3.1 channels in human microglia, linking ATP-evoked Ca2+ transients to changes in membrane conductance, with an inflammation-dependent mechanism, and suggests that during brain inflammation the KCa3.1-mediated microglial response to purinergic signaling may be reduced. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02096-0.
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Affiliation(s)
| | | | | | | | | | | | | | - Vincenzo Esposito
- IRCCS Neuromed, Pozzilli, IS, Italy.,Department of Human Neurosciences, Sapienza Rome University, Rome, Italy
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, CA, USA
| | - Cristina Limatola
- IRCCS Neuromed, Pozzilli, IS, Italy.,Department of Physiology and Pharmacology "V. Erspamer", Sapienza Rome University, Rome, Italy
| | - Sergio Fucile
- IRCCS Neuromed, Pozzilli, IS, Italy.,Department of Physiology and Pharmacology "V. Erspamer", Sapienza Rome University, Rome, Italy
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Singh S, Singh TG, Rehni AK. An Insight into Molecular Mechanisms and Novel Therapeutic Approaches in Epileptogenesis. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2021; 19:750-779. [PMID: 32914725 DOI: 10.2174/1871527319666200910153827] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 11/22/2022]
Abstract
Epilepsy is the second most common neurological disease with abnormal neural activity involving the activation of various intracellular signalling transduction mechanisms. The molecular and system biology mechanisms responsible for epileptogenesis are not well defined or understood. Neuroinflammation, neurodegeneration and Epigenetic modification elicit epileptogenesis. The excessive neuronal activities in the brain are associated with neurochemical changes underlying the deleterious consequences of excitotoxicity. The prolonged repetitive excessive neuronal activities extended to brain tissue injury by the activation of microglia regulating abnormal neuroglia remodelling and monocyte infiltration in response to brain lesions inducing axonal sprouting contributing to neurodegeneration. The alteration of various downstream transduction pathways resulted in intracellular stress responses associating endoplasmic reticulum, mitochondrial and lysosomal dysfunction, activation of nucleases, proteases mediated neuronal death. The recently novel pharmacological agents modulate various receptors like mTOR, COX-2, TRK, JAK-STAT, epigenetic modulators and neurosteroids are used for attenuation of epileptogenesis. Whereas the various molecular changes like the mutation of the cell surface, nuclear receptor and ion channels focusing on repetitive episodic seizures have been explored by preclinical and clinical studies. Despite effective pharmacotherapy for epilepsy, the inadequate understanding of precise mechanisms, drug resistance and therapeutic failure are the current fundamental problems in epilepsy. Therefore, the novel pharmacological approaches evaluated for efficacy on experimental models of epilepsy need to be identified and validated. In addition, we need to understand the downstream signalling pathways of new targets for the treatment of epilepsy. This review emphasizes on the current state of novel molecular targets as therapeutic approaches and future directions for the management of epileptogenesis. Novel pharmacological approaches and clinical exploration are essential to make new frontiers in curing epilepsy.
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Affiliation(s)
- Shareen Singh
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | | | - Ashish Kumar Rehni
- Cerebral Vascular Disease Research Laboratories, Department of Neurology and Neuroscience Program, University of Miami School of Medicine, Miami, Florida 33101, United States
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18
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Severin D, Gallagher M, Kirkwood A. Afterhyperpolarization amplitude in CA1 pyramidal cells of aged Long-Evans rats characterized for individual differences. Neurobiol Aging 2020; 96:43-48. [PMID: 32932137 DOI: 10.1016/j.neurobiolaging.2020.07.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 07/06/2020] [Accepted: 07/25/2020] [Indexed: 11/18/2022]
Abstract
Altered neural excitability is considered a prominent contributing factor to cognitive decline during aging. A clear example is the excess neural activity observed in several temporal lobe structures of cognitively impaired older individuals in rodents and humans. At a cellular level, aging-related changes in mechanisms regulating intrinsic excitability have been well examined in pyramidal cells of the CA1 hippocampal subfield. Studies in the inbred Fisher 344 rat strain document an age-related increase in the slow afterhyperpolarization (AHP) that normally occurs after a burst of action potentials, and serves to reduce subsequent firing. We evaluated the status of the AHP in the outbred Long-Evans rat, a well-established model for studying individual differences in neurocognitive aging. In contrast to the findings reported in the Fisher 344 rats, in the Long-Evan rats we detected a selective reduction in AHP in cognitively impaired aged individuals. We discuss plausible scenarios to account for these differences and also discuss possible implications of these differences.
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Affiliation(s)
- Daniel Severin
- Department of Neurosciences, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Michela Gallagher
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Alfredo Kirkwood
- Department of Neurosciences, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, USA.
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Tao Z, Chun-Yan H, Hua P, Bin-Bin Y, Xiaoping T. Phyllathin From Phyllanthus Amarus Ameliorates Epileptic Convulsion and Kindling Associated Post-Ictal Depression in Mice via Inhibition of NF-κB/TLR-4 Pathway. Dose Response 2020; 18:1559325820946914. [PMID: 32821254 PMCID: PMC7412921 DOI: 10.1177/1559325820946914] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/14/2020] [Accepted: 07/04/2020] [Indexed: 12/13/2022] Open
Abstract
Background Epilepsy is a chronic, complex, unprovoked, and recurrent disorder of the nervous system that affected several people worldwide. Phyllanthus amarus (PA) has been documented to have neuroprotective potential. Aim To evaluate the potential of standardized extract of PA and its possible mechanism of action against the Pentylenetetrazol (PTZ)-induced convulsion and kindling associated post-ictal depression in experimental mice. Materials and Methods Phyllathin was isolated from methanolic extract of PA and well-characterized using HPTLC, ESI-MS/MS, and LC/MS. Phyllathin containing a standardized extract of PA (50, 100, and 200 mg/kg) was administered in convulsed and kindled mice, followed by an assessment of various parameters. Results The spectral analysis confirmed the molecular formula and weight of phyllanthin as C24H34O6 and 418.2342 Da. PA (100 and 200 mg/kg) significantly ameliorated PTZ-induced (p < 0.05) duration, onset of tonic-clonic convulsion, and mortality in mice. It also significantly attenuated (p < 0.05) PTZ-induced kindling in mice. Alteration in brain GABA, dopamine, and glutamate, Na+K+ATPase, Ca+2-ATPase activities, and oxido-nitrosative stress in kindled mice was significantly restored (p < 0.05) by PA treatment. It also significantly (p < 0.05) down-regulated brain mRNA expressions of NF-κB, TNF-α, IL-1β, COX-2, and TLR-4. Histological aberrations induced by PTZ in the brain of a kindled rat was significantly (p < 0.05) ameliorated by PA. Conclusion Phyllanthin containing a standardized extract of PA exerts its antiepileptic potential via balancing excitatory (glutamate) and inhibitory (GABA) brain monoamines, voltage-gated ion channels (Na+K+/Ca+2-ATPase) and inhibition of NF-κB/TLR-4 pathway to ameliorate neuroinflammation (TNF-α, IL-1β, and COX-2) in experimental mice.
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Affiliation(s)
- Zhang Tao
- Department of Neurosurgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Hu Chun-Yan
- Department of Urology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Peng Hua
- Department of Neurosurgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Yang Bin-Bin
- Department of Neurosurgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Tang Xiaoping
- Department of Neurosurgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
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Abstract
Protein Kinase A-Mediated Suppression of the Slow After Hyperpolarizing KCa3.1 Current in Temporal Lobe Epilepsy Tiwari MN, Mohan S, Biala Y, Yaari Y. J Neurosci . 2019;39(50):9914-9926. doi: https://doi.org/10.1523/JNEUROSCI.1603-19 . Brain insults, such as trauma, stroke, anoxia, and status epilepticus (SE), cause multiple changes in synaptic function and intrinsic properties of surviving neurons that may lead to the development of epilepsy. Experimentally, a single SE episode, induced by the convulsant pilocarpine, initiates the development of an epileptic condition resembling human temporal lobe epilepsy (TLE). Principal hippocampal neurons from such epileptic animals display enhanced spike output in response to excitatory stimuli compared with neurons from nonepileptic animals. This enhanced firing is negatively related to the size of the slow afterhyperpolarization (sAHP), which is reduced in the epileptic neurons. The sAHP is an intrinsic neuronal negative feedback mechanism consisting normally of 2 partially overlapping components produced by disparate mechanisms. One component is generated by activation of Ca2+-gated K+ (KCa) channels, likely KCa3.1, consequent to spike Ca2+ influx (the KCa-sAHP component). The second component is generated by enhancement of the electrogenic Na+/K+ ATPase (NKA) by spike Na+ influx (NKA-sAHP component). Here we show that the KCa-sAHP component is markedly reduced in male rat epileptic neurons, whereas the NKA-sAHP component is not altered. The KCa-sAHP reduction is due to the downregulation of KCa3.1 channels, mediated by cAMP-dependent protein kinase A (PKA). This sustained effect can be acutely reversed by applying PKA inhibitors, leading also to normalization of the spike output of epileptic neurons. We propose that the novel “acquired channelopathy” described here, namely, PKA-mediated downregulation of KCa3.1 activity, provides an innovative target for developing new treatments for TLE, hopefully overcoming the pharmacoresistance to traditional drugs. Significance Statement: Epilepsy, a common neurological disorder, often develops following a brain insult. Identifying key molecular and cellular mechanisms underlying acquired epilepsy is critical for developing effective antiepileptic therapies. In an experimental model of acquired epilepsy, we show that principal hippocampal neurons become intrinsically hyperexcitable. This alteration is due predominantly to the downregulation of a ubiquitous class of potassium ion channels, KCa3.1, whose main function is to dampen neuronal excitability. KCa3.1 downregulation is mediated by the cAMP-dependent PKA signaling pathway. Most importantly, it can be acutely reversed by PKA inhibitors, leading to recovery of KCa3.1 function and normalization of neuronal excitability. The discovery of this novel epileptogenic mechanism hopefully will facilitate the development of more efficient pharmacotherapy for acquired epilepsy.
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