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Maraslioglu-Sperber A, Pizzi E, Fisch JO, Kattler K, Ritter T, Friauf E. Molecular and functional profiling of cell diversity and identity in the lateral superior olive, an auditory brainstem center with ascending and descending projections. Front Cell Neurosci 2024; 18:1354520. [PMID: 38846638 PMCID: PMC11153811 DOI: 10.3389/fncel.2024.1354520] [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: 12/12/2023] [Accepted: 03/15/2024] [Indexed: 06/09/2024] Open
Abstract
The lateral superior olive (LSO), a prominent integration center in the auditory brainstem, contains a remarkably heterogeneous population of neurons. Ascending neurons, predominantly principal neurons (pLSOs), process interaural level differences for sound localization. Descending neurons (lateral olivocochlear neurons, LOCs) provide feedback into the cochlea and are thought to protect against acoustic overload. The molecular determinants of the neuronal diversity in the LSO are largely unknown. Here, we used patch-seq analysis in mice at postnatal days P10-12 to classify developing LSO neurons according to their functional and molecular profiles. Across the entire sample (n = 86 neurons), genes involved in ATP synthesis were particularly highly expressed, confirming the energy expenditure of auditory neurons. Two clusters were identified, pLSOs and LOCs. They were distinguished by 353 differentially expressed genes (DEGs), most of which were novel for the LSO. Electrophysiological analysis confirmed the transcriptomic clustering. We focused on genes affecting neuronal input-output properties and validated some of them by immunohistochemistry, electrophysiology, and pharmacology. These genes encode proteins such as osteopontin, Kv11.3, and Kvβ3 (pLSO-specific), calcitonin-gene-related peptide (LOC-specific), or Kv7.2 and Kv7.3 (no DEGs). We identified 12 "Super DEGs" and 12 genes showing "Cluster similarity." Collectively, we provide fundamental and comprehensive insights into the molecular composition of individual ascending and descending neurons in the juvenile auditory brainstem and how this may relate to their specific functions, including developmental aspects.
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Affiliation(s)
- Ayse Maraslioglu-Sperber
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Erika Pizzi
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Jonas O. Fisch
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Kathrin Kattler
- Genetics/Epigenetics Group, Department of Biological Sciences, Saarland University, Saarbrücken, Germany
| | - Tamara Ritter
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
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2
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d’Apolito M, Ceccarini C, Savino R, Adipietro I, di Bari I, Santacroce R, Curcetti M, D’Andrea G, Croce AI, Cesarano C, Polito AN, Margaglione M. A Novel KCNN2 Variant in a Family with Essential Tremor Plus: Clinical Characteristics and In Silico Analysis. Genes (Basel) 2023; 14:1380. [PMID: 37510285 PMCID: PMC10379157 DOI: 10.3390/genes14071380] [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: 05/19/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Essential tremor (ET) is one of the more common movement disorders. Current diagnosis is solely based on clinical findings. ET appears to be inherited in an autosomal dominant pattern. Several loci on specific chromosomes have been studied by linkage analysis, but the causes of essential tremor are still unknown in many patients. Genetic studies described the association of several genes with familial ET. However, they were found only in distinct families, suggesting that some can be private pathogenic variants. AIM OF THE STUDY to characterize the phenotype of an Italian family with ET and identify the genetic variant associated. METHODS Clinical and genetic examinations were performed. Genetic testing was done with whole-exome sequencing (WES) using the Illumina platform. Bidirectional capillary Sanger sequencing was used to investigate the presence of variant in all affected members of the family. In silico prediction of pathogenicity was used to study the effect of gene variants on protein structure. RESULTS The proband was a 15-year-old boy. The patient was the first of two children of a non-consanguineous couple. Family history was remarkable for tremor in the mother line. His mother suffered from bilateral upper extremity kinetic tremors (since she was 20 years old), anxiety, and depression. Other relatives referred bilateral upper extremity tremors. In the index case, WES analysis performed supposing a dominant mode of inheritance, identified a novel heterozygous missense variant in potassium calcium-activated channel subfamily N member 2 (KCNN2) (NM_021614.3: c.1145G>A, p.Gly382Asp). In the pedigree investigation, all carriers of the gene variant had ET and showed variable expressivity, the elder symptomatic relative showing cognitive impairment and hallucinations in the last decade, in addition to tremor since a young age. The amino acid residue #382 is located in a transmembrane region and in silico analysis suggested a causative role for the variant. Modelling of the mutant protein structure showed that the variant causes a clash in the protein structure. Therefore, the variant could cause a conformational change that alters the ability of the protein in the modulation of ion channels Conclusions: The KCNN2 gene variant identified could be associated with ET. The variant could modify a voltage-independent potassium channel activated by intracellular calcium.
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Affiliation(s)
- Maria d’Apolito
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Caterina Ceccarini
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Rosa Savino
- Neuropsychiatry for Child and Adolescent Unit, Department of Woman and Child, Policlinico Riuniti, 70122 Foggia, Italy; (R.S.); (A.N.P.)
| | - Iolanda Adipietro
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Ighli di Bari
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Rosa Santacroce
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Maria Curcetti
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Giovanna D’Andrea
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Anna-Irma Croce
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Carla Cesarano
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
| | - Anna Nunzia Polito
- Neuropsychiatry for Child and Adolescent Unit, Department of Woman and Child, Policlinico Riuniti, 70122 Foggia, Italy; (R.S.); (A.N.P.)
| | - Maurizio Margaglione
- Medical Genetics, Department of Clinical and Experimental Medicine, University of Foggia, 70122 Foggia, Italy; (M.d.); (C.C.); (I.A.); (I.d.B.); (R.S.); (M.C.); (G.D.); (A.-I.C.); (C.C.)
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3
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Nageeb Hasan SM, Clarke CL, McManamon Strand TP, Bambico FR. Putative pathological mechanisms of late-life depression and Alzheimer's Disease. Brain Res 2023:148423. [PMID: 37244602 DOI: 10.1016/j.brainres.2023.148423] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/18/2023] [Accepted: 05/22/2023] [Indexed: 05/29/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that is characterized by progressive impairment in cognition and memory. AD is accompanied by several neuropsychiatric symptoms, with depression being the most prominent. Although depression has long been known to be associated with AD, controversial findings from preclinical and clinical studies have obscured the precise nature of this association. However recent evidence suggests that depression could be a prodrome or harbinger of AD. Evidence indicates that the major central serotonergic nucleus-the dorsal raphe nucleus (DRN)-shows very early AD pathology: neurofibrillary tangles made of hyperphosphorylated tau protein and degenerated neurites. AD and depression share common pathophysiologies, including functional deficits of the serotonin (5-HT) system. 5-HT receptors have modulatory effects on the progression of AD pathology i.e., reduction in Aβ load, increased hyper-phosphorylation of tau, decreased oxidative stress etc. Moreover, preclinical models show a role for specific channelopathies that result in abnormal regional activational and neuroplasticity patterns. One of these concerns the pathological upregulation of the small conductance calcium-activated potassium (SK) channel in corticolimbic structure. This has also been observed in the DRN in both diseases. The SKC is a key regulator of cell excitability and long-term potentiation (LTP). SKC over-expression is positively correlated with aging and cognitive decline, and is evident in AD. Pharmacological blockade of SKCs has been reported to reverse symptoms of depression and AD. Thus, aberrant SKC functioning could be related to depression pathophysiology and diverts its late-life progression towards the development of AD. We summarize findings from preclinical and clinical studies suggesting a molecular linkage between depression and AD pathology. We also provide a rationale for considering SKCs as a novel pharmacological target for the treatment of AD-associated symptoms.
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Affiliation(s)
- S M Nageeb Hasan
- Department of Psychology, Memorial University of Newfoundland and Labrador, Newfoundland and Labrador, A1B3Xs, Canada.
| | - Courtney Leigh Clarke
- Department of Psychology, Memorial University of Newfoundland and Labrador, Newfoundland and Labrador, A1B3Xs, Canada
| | | | - Francis Rodriguez Bambico
- Department of Psychology, Memorial University of Newfoundland and Labrador, Newfoundland and Labrador, A1B3Xs, Canada; Behavioural Neurobiology Laboratory, Centre for Addiction and Mental Health, Toronto, ON, M5T1R8, Canada
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4
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Fearon C, Grippe TC, Chen R, Lang AE. Early-Onset Neurodevelopmental Movement Disorder Secondary to Novel Mutation in KCNN2. Mov Disord Clin Pract 2022; 9:S9-S12. [PMID: 36118511 PMCID: PMC9464988 DOI: 10.1002/mdc3.13535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/29/2021] [Accepted: 01/06/2022] [Indexed: 11/06/2022] Open
Affiliation(s)
- Conor Fearon
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital—UHN, Division of NeurologyUniversity of TorontoTorontoOntarioCanada
| | - Talyta Cortez Grippe
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital—UHN, Division of NeurologyUniversity of TorontoTorontoOntarioCanada
| | - Robert Chen
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital—UHN, Division of NeurologyUniversity of TorontoTorontoOntarioCanada
| | - Anthony E. Lang
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital—UHN, Division of NeurologyUniversity of TorontoTorontoOntarioCanada
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5
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KCNN2 Mutation in Pediatric Tremor Myoclonus Dystonia Syndrome with Electrophysiological Evaluation. Tremor Other Hyperkinet Mov (N Y) 2022; 12:2. [PMID: 35106185 PMCID: PMC8796689 DOI: 10.5334/tohm.668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 01/13/2022] [Indexed: 11/20/2022] Open
Abstract
Background: Here we combine clinical, electrophysiological, and genetic findings to phenotype an unusual childhood movement disorder in a patient with a rare form of KCNN2 mutation. Case Report: A 10-year-old male presented with a clinical syndrome of tremor and myoclonus. Electrophysiology demonstrated muscle activity indicative of myoclonus dystonia, an observation that was not appreciated clinically. Genetic testing revealed an abnormality in the KCNN 2 gene, not present in the parents, known to cause dystonia, as the etiology. Discussion: The value of utilizing noninvasive, electrophysiological recording in pediatric movement disorders expands the precision of diagnosis, potentially informing treatment when correlated with clinical and genetic findings.
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6
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Nashed MG, Waye S, Hasan SMN, Nguyen D, Wiseman M, Zhang J, Lau H, Dinesh OC, Raymond R, Greig IR, Bambico FR, Nobrega JN. Antidepressant activity of pharmacological and genetic deactivation of the small-conductance calcium-activated potassium channel subtype-3. Psychopharmacology (Berl) 2022; 239:253-266. [PMID: 34982171 DOI: 10.1007/s00213-021-06045-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 12/13/2021] [Indexed: 11/25/2022]
Abstract
RATIONALE The voltage-insensitive, small-conductance calcium-activated potassium (SK) channel is a key regulator of neuronal depolarization and is implicated in the pathophysiology of depressive disorders. OBJECTIVE We ascertained whether the SK channel is impaired in the chronic unpredictable stress (CUS) model and whether it can serve as a molecular target of antidepressant action. METHODS We assessed the depressive-like behavioral phenotype of CUS-exposed rats and performed post-mortem SK channel binding and activity-dependent zif268 mRNA analyses on their brains. To begin an assessment of SK channel subtypes involved, we examined the effects of genetic and pharmacological inhibition of the SK3 channel using conditional knockout mice and selective SK3 channel negative allosteric modulators (NAMs). RESULTS We found that [125I]apamin binding to SK channels is increased in the prefrontal cortex and decreased in the hippocampus, an effect that was associated with reciprocal levels of zif268 mRNA transcripts indicating abnormal regional cell activity in this model. We found that genetic and pharmacological manipulations significantly decreased immobility in the forced swim test without altering general locomotor activity, a hallmark of antidepressant-like activity. CONCLUSIONS Taken together, these findings link depression-related neural and behavioral pathophysiology with abnormal SK channel functioning and suggest that this can be reversed by the selective inhibition of SK3 channels.
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Affiliation(s)
- Mina G Nashed
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - Shannon Waye
- Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland & Labrador, A1B 3X9, Canada
| | - S M Nageeb Hasan
- Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland & Labrador, A1B 3X9, Canada
| | - Diana Nguyen
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - Micaela Wiseman
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - Jing Zhang
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - Harry Lau
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - O Chandani Dinesh
- Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland & Labrador, A1B 3X9, Canada
| | - Roger Raymond
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
| | - Iain R Greig
- Institute of Medical Sciences, University of Aberdeen, King's College, Aberdeen, AB25 2ZD, Scotland
| | - Francis Rodriguez Bambico
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada. .,Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland & Labrador, A1B 3X9, Canada.
| | - José N Nobrega
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health (CAMH), Toronto, ON, M5T 1R8, Canada
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7
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Ji NN, Du L, Wang Y, Wu K, Chen ZY, Hua R, Zhang YM. Small-Conductance Ca 2+-Activated K + Channels 2 in the Hypothalamic Paraventricular Nucleus Precipitates Visceral Hypersensitivity Induced by Neonatal Colorectal Distension in Rats. Front Pharmacol 2021; 11:605618. [PMID: 33584280 PMCID: PMC7873043 DOI: 10.3389/fphar.2020.605618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 12/14/2020] [Indexed: 01/30/2023] Open
Abstract
Visceral hypersensitivity is one of the pivotal pathophysiological features of visceral pain in irritable bowel syndrome (IBS). Small-conductance Ca2+-activated K+ channel (SK) is critical for a variety of functions in the central nervous system (CNS), nonetheless, whether it is involved in the pathogenesis of visceral hypersensitivity remain elusive. In this study, we examined mechanism of SK2 in hypothalamic paraventricular nucleus (PVN) in the pathogenesis of visceral hypersensitivity induced by neonatal colorectal distension (CRD). Rats undergoing neonatal CRD presented with visceral hypersensitivity as well as downregulated membrane SK2 channel and p-PKA. Intra-PVN administration of either the membrane protein transport inhibitor dynasore or the SK2 activator 1-EBIO upregulated the expression of membrane SK2 in PVN and mitigated visceral hypersensitivity. In addition, 1-EBIO administration reversed the increase in neuronal firing rates in PVN in rats undergoing neonatal CRD. On the contrary, intra-PVN administration of either the SK2 inhibitor apamin or PKA activator 8-Br-cAMP exacerbated the visceral hypersensitivity. Taken together, these findings demonstrated that visceral hypersensitivity is related to the downregulation of membrane SK2 in PVN, which may be attributed to the activation of PKA; pharmacologic activation of SK2 alleviated visceral hypersensitivity, which brings prospect of SK2 activators as a new intervention for visceral pain.
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Affiliation(s)
- Ning-Ning Ji
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Lei Du
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Anesthesiology Department of the Nanjing Children's Hospital, Nanjing, China
| | - Ying Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Ke Wu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Zi-Yang Chen
- Department of Anesthesiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Rong Hua
- Institute of Emergency Rescue Medicine, Xuzhou Medical University, Xuzhou, China
| | - Yong-Mei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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8
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Deardorff AS, Romer SH, Fyffe RE. Location, location, location: the organization and roles of potassium channels in mammalian motoneurons. J Physiol 2021; 599:1391-1420. [DOI: 10.1113/jp278675] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 01/08/2021] [Indexed: 11/08/2022] Open
Affiliation(s)
- Adam S. Deardorff
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
- Department of Neurology and Internal Medicine, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
| | - Shannon H. Romer
- Odyssey Systems Environmental Health Effects Laboratory, Navy Medical Research Unit‐Dayton Wright‐Patterson Air Force Base OH 45433 USA
| | - Robert E.W. Fyffe
- Department of Neuroscience, Cell Biology and Physiology, Wright State University Boonshoft School of Medicine Dayton OH 45435 USA
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9
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Spanoghe J, Larsen LE, Craey E, Manzella S, Van Dycke A, Boon P, Raedt R. The Signaling Pathways Involved in the Anticonvulsive Effects of the Adenosine A 1 Receptor. Int J Mol Sci 2020; 22:ijms22010320. [PMID: 33396826 PMCID: PMC7794785 DOI: 10.3390/ijms22010320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/22/2020] [Accepted: 12/27/2020] [Indexed: 12/20/2022] Open
Abstract
Adenosine acts as an endogenous anticonvulsant and seizure terminator in the brain. Many of its anticonvulsive effects are mediated through the activation of the adenosine A1 receptor, a G protein-coupled receptor with a wide array of targets. Activating A1 receptors is an effective approach to suppress seizures. This review gives an overview of the neuronal targets of the adenosine A1 receptor focusing in particular on signaling pathways resulting in neuronal inhibition. These include direct interactions of G protein subunits, the adenyl cyclase pathway and the phospholipase C pathway, which all mediate neuronal hyperpolarization and suppression of synaptic transmission. Additionally, the contribution of the guanyl cyclase and mitogen-activated protein kinase cascades to the seizure-suppressing effects of A1 receptor activation are discussed. This review ends with the cautionary note that chronic activation of the A1 receptor might have detrimental effects, which will need to be avoided when pursuing A1 receptor-based epilepsy therapies.
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Affiliation(s)
- Jeroen Spanoghe
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Lars E. Larsen
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Erine Craey
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Simona Manzella
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Annelies Van Dycke
- Department of Neurology, General Hospital Sint-Jan Bruges, 8000 Bruges, Belgium;
| | - Paul Boon
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Robrecht Raedt
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
- Correspondence:
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10
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Mochel F, Rastetter A, Ceulemans B, Platzer K, Yang S, Shinde DN, Helbig KL, Lopergolo D, Mari F, Renieri A, Benetti E, Canitano R, Waisfisz Q, Plomp AS, Huisman SA, Wilson GN, Cathey SS, Louie RJ, Gaudio DD, Waggoner D, Kacker S, Nugent KM, Roeder ER, Bruel AL, Thevenon J, Ehmke N, Horn D, Holtgrewe M, Kaiser FJ, Kamphausen SB, Abou Jamra R, Weckhuysen S, Dalle C, Depienne C. Variants in the SK2 channel gene (KCNN2) lead to dominant neurodevelopmental movement disorders. Brain 2020; 143:3564-3573. [PMID: 33242881 DOI: 10.1093/brain/awaa346] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/17/2020] [Accepted: 09/08/2020] [Indexed: 11/14/2022] Open
Abstract
KCNN2 encodes the small conductance calcium-activated potassium channel 2 (SK2). Rodent models with spontaneous Kcnn2 mutations show abnormal gait and locomotor activity, tremor and memory deficits, but human disorders related to KCNN2 variants are largely unknown. Using exome sequencing, we identified a de novo KCNN2 frameshift deletion in a patient with learning disabilities, cerebellar ataxia and white matter abnormalities on brain MRI. This discovery prompted us to collect data from nine additional patients with de novo KCNN2 variants (one nonsense, one splice site, six missense variants and one in-frame deletion) and one family with a missense variant inherited from the affected mother. We investigated the functional impact of six selected variants on SK2 channel function using the patch-clamp technique. All variants tested but one, which was reclassified to uncertain significance, led to a loss-of-function of SK2 channels. Patients with KCNN2 variants had motor and language developmental delay, intellectual disability often associated with early-onset movement disorders comprising cerebellar ataxia and/or extrapyramidal symptoms. Altogether, our findings provide evidence that heterozygous variants, likely causing a haploinsufficiency of the KCNN2 gene, lead to novel autosomal dominant neurodevelopmental movement disorders mirroring phenotypes previously described in rodents.
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Affiliation(s)
- Fanny Mochel
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013 Paris, France.,AP-HP, Hôpital Pitié-Salpêtrière, Département de Génétique and Centre de Référence Neurométabolique Adulte, F-75013, Paris, France
| | - Agnès Rastetter
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013 Paris, France
| | - Berten Ceulemans
- Division of Paediatric Neurology, Antwerp University Hospital, University of Antwerp, Edegem, Belgium
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | | | - Deepali N Shinde
- Department of Clinical Diagnostics, Ambry Genetics, Aliso Viejo, CA, USA
| | - Katherine L Helbig
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Diego Lopergolo
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Francesca Mari
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Alessandra Renieri
- Medical Genetics, University of Siena, Siena, Italy.,Genetica Medica, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Elisa Benetti
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Roberto Canitano
- Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, Siena, Italy
| | - Quinten Waisfisz
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Astrid S Plomp
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Sylvia A Huisman
- Department of Pediatrics, Amsterdam UMC, Amsterdam, The Netherlands.,Prinsenstichting, Purmerend, The Netherlands
| | - Golder N Wilson
- Department of Pediatrics, Texas Tech University Health Science Center, Lubbock, Texas, USA
| | - Sara S Cathey
- Greenwood Genetic Center, Greenwood, South Carolina, 29646, USA
| | - Raymond J Louie
- Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA
| | - Daniela Del Gaudio
- Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA
| | - Darrel Waggoner
- Department of Human Genetics, University of Chicago, Chicago, IL, 60637, USA
| | - Shawn Kacker
- Department of Pediatrics, Section of Child Neurology, University of Chicago, Chicago, IL, 60637, USA
| | - Kimberly M Nugent
- Department of Pediatrics, Baylor College of Medicine, San Antonio, TX, 78207, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Elizabeth R Roeder
- Department of Pediatrics, Baylor College of Medicine, San Antonio, TX, 78207, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Ange-Line Bruel
- UMR1231 GAD, Inserm - Université Bourgogne-Franche Comté, Dijon, France.,Centre de référence maladies rares 'déficiences intellectuelles de causes rares', Centre de Génétique, FHU-TRANSLAD, CHU Dijon Bourgogne, Dijon, France
| | - Julien Thevenon
- Service de Génétique, Génomique, et Procréation, Centre Hospitalier Universitaire Grenoble Alpes, 38700 La Tronche, France.,INSERM 1209, CNRS UMR 5309, Institute for Advanced Biosciences, Université Grenoble Alpes, 38706 Grenoble, France
| | - Nadja Ehmke
- Institute for Human Genetics and Medical Genetics, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Denise Horn
- Institute for Human Genetics and Medical Genetics, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Manuel Holtgrewe
- Core Unit Bioinformatics - CUBI, Berlin Institute of Health (BIH), Berlin, Germany
| | - Frank J Kaiser
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
| | | | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Sarah Weckhuysen
- Applied and Translational Neurogenomics Group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium.,Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium.,Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Carine Dalle
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013 Paris, France
| | - Christel Depienne
- Institut du Cerveau et de la Moelle épinière (ICM), Sorbonne Université, UMR S 1127, Inserm U1127, CNRS UMR 7225, F-75013 Paris, France.,Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany
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11
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Sun J, Liu Y, Baudry M, Bi X. SK2 channel regulation of neuronal excitability, synaptic transmission, and brain rhythmic activity in health and diseases. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2020; 1867:118834. [PMID: 32860835 PMCID: PMC7541745 DOI: 10.1016/j.bbamcr.2020.118834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 08/13/2020] [Accepted: 08/19/2020] [Indexed: 11/20/2022]
Abstract
Small conductance calcium-activated potassium channels (SKs) are solely activated by intracellular Ca2+ and their activation leads to potassium efflux, thereby repolarizing/hyperpolarizing membrane potential. Thus, these channels play a critical role in synaptic transmission, and consequently in information transmission along the neuronal circuits expressing them. SKs are widely but not homogeneously distributed in the central nervous system (CNS). Activation of SKs requires submicromolar cytoplasmic Ca2+ concentrations, which are reached following either Ca2+ release from intracellular Ca2+ stores or influx through Ca2+ permeable membrane channels. Both Ca2+ sensitivity and synaptic levels of SKs are regulated by protein kinases and phosphatases, and degradation pathways. SKs in turn control the activity of multiple Ca2+ channels. They are therefore critically involved in coordinating diverse Ca2+ signaling pathways and controlling Ca2+ signal amplitude and duration. This review highlights recent advances in our understanding of the regulation of SK2 channels and of their roles in normal brain functions, including synaptic plasticity, learning and memory, and rhythmic activities. It will also discuss how alterations in their expression and regulation might contribute to various brain disorders such as Angelman Syndrome, Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Jiandong Sun
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Yan Liu
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Michel Baudry
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Xiaoning Bi
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America.
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12
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Diniz AFA, Ferreira RC, de Souza ILL, da Silva BA. Ionic Channels as Potential Therapeutic Targets for Erectile Dysfunction: A Review. Front Pharmacol 2020; 11:1120. [PMID: 32848741 PMCID: PMC7396897 DOI: 10.3389/fphar.2020.01120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
Erectile dysfunction (ED) is a prevalent condition, especially in men over 40 years old, characterized by the inability to obtain and/or maintain penile erection sufficient for satisfactory sexual intercourse. Several psychological and/or organic factors are involved in the etiopathogenesis of ED. In this context, we gathered evidence of the involvement of Large-conductance, Ca2+-activated K+ channels (BKCa), Small-conductance, Ca2+-activated K+ channels (SKCa), KCNQ-encoded voltage-dependent K+ channels (KV7), Transient Receptor Potential channels (TRP), and Calcium-activated Chloride channels (CaCC) dysfunctions on ED. In addition, the use of modulating agents of these channels are involved in relaxation of the cavernous smooth muscle cell and, consequent penile erection, suggesting that these channels are promising therapeutic targets for the treatment of erectile dysfunction.
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Affiliation(s)
- Anderson Fellyp Avelino Diniz
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Rafael Carlos Ferreira
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Iara Leão Luna de Souza
- Departamento de Ciências Biológicas e da Saúde, Universidade Estadual de Roraima, Boa Vista, Brazil
| | - Bagnólia Araújo da Silva
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
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13
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Bambico FR, Li Z, Creed M, De Gregorio D, Diwan M, Li J, McNeill S, Gobbi G, Raymond R, Nobrega JN. A Key Role for Prefrontocortical Small Conductance Calcium-Activated Potassium Channels in Stress Adaptation and Rapid Antidepressant Response. Cereb Cortex 2019; 30:1559-1572. [DOI: 10.1093/cercor/bhz187] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 05/22/2019] [Accepted: 07/03/2019] [Indexed: 01/03/2023] Open
Abstract
AbstractThe muscarinic acetylcholine receptor antagonist scopolamine elicits rapid antidepressant activity, but its underlying mechanism is not fully understood. In a chronic stress model, a single low-dose administration of scopolamine reversed depressive-like reactivity. This antidepressant-like effect was mediated via a muscarinic M1 receptor–SKC pathway because it was mimicked by intra-medial prefrontal cortex (intra-mPFC) infusions of scopolamine, of the M1 antagonist pirenzepine or of the SKC antagonist apamin, but not by the selective serotonin reuptake inhibitor (SSRI) antidepressant fluoxetine. Extracellular and whole-cell recordings revealed that scopolamine and ketamine attenuate the SKC-mediated action potential hyperpolarization current and rapidly enhance mPFC neuronal excitability within the therapeutically relevant time window. The SKC agonist 1-EBIO abrogated scopolamine-induced antidepressant activity at a dose that completely suppressed burst firing activity. Scopolamine also induced a slow-onset activation of raphe serotonergic neurons, which in turn was dependent on mPFC-induced neuroplasticity or excitatory input, since mPFC transection abolished this effect. These early behavioral and mPFC activational effects of scopolamine did not appear to depend on prefrontocortical brain-derived neurotrophic factor and serotonin-1A activity, classically linked to SSRIs, and suggest a novel mechanism associated with antidepressant response onset through SKC-mediated regulation of activity-dependent plasticity.
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Affiliation(s)
- Francis Rodriguez Bambico
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
- Department of Psychology, Memorial University of Newfoundland, St. John’s, NL A1B 3X9, Canada
| | - Zhuoliang Li
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
| | - Meaghan Creed
- Département des Neurosciences Fondamentales & Service de Neurologie, University of Geneva, Geneva, CH-1211, Switzerland
| | - Danilo De Gregorio
- Department of Psychiatry, McGill University, Montreal, QC H3A 1A1, Canada
| | - Mustansir Diwan
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
| | - Jessica Li
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
| | - Sean McNeill
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
| | - Gabriella Gobbi
- Department of Psychiatry, McGill University, Montreal, QC H3A 1A1, Canada
| | - Roger Raymond
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
| | - José N Nobrega
- Behavioural Neurobiology Laboratory, Research Imaging Center, Centre for Addiction and Mental Health, Toronto, ON M5T 1R8, Canada
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14
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Gain-of-Function Mutations in KCNN3 Encoding the Small-Conductance Ca 2+-Activated K + Channel SK3 Cause Zimmermann-Laband Syndrome. Am J Hum Genet 2019; 104:1139-1157. [PMID: 31155282 DOI: 10.1016/j.ajhg.2019.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/15/2019] [Indexed: 01/16/2023] Open
Abstract
Zimmermann-Laband syndrome (ZLS) is characterized by coarse facial features with gingival enlargement, intellectual disability (ID), hypertrichosis, and hypoplasia or aplasia of nails and terminal phalanges. De novo missense mutations in KCNH1 and KCNK4, encoding K+ channels, have been identified in subjects with ZLS and ZLS-like phenotype, respectively. We report de novo missense variants in KCNN3 in three individuals with typical clinical features of ZLS. KCNN3 (SK3/KCa2.3) constitutes one of three members of the small-conductance Ca2+-activated K+ (SK) channels that are part of a multiprotein complex consisting of the pore-forming channel subunits, the constitutively bound Ca2+ sensor calmodulin, protein kinase CK2, and protein phosphatase 2A. CK2 modulates Ca2+ sensitivity of the channels by phosphorylating SK-bound calmodulin. Patch-clamp whole-cell recordings of KCNN3 channel-expressing CHO cells demonstrated that disease-associated mutations result in gain of function of the mutant channels, characterized by increased Ca2+ sensitivity leading to faster and more complete activation of KCNN3 mutant channels. Pretreatment of cells with the CK2 inhibitor 4,5,6,7-tetrabromobenzotriazole revealed basal inhibition of wild-type and mutant KCNN3 channels by CK2. Analogous experiments with the KCNN3 p.Val450Leu mutant previously identified in a family with portal hypertension indicated basal constitutive channel activity and thus a different gain-of-function mechanism compared to the ZLS-associated mutant channels. With the report on de novo KCNK4 mutations in subjects with facial dysmorphism, hypertrichosis, epilepsy, ID, and gingival overgrowth, we propose to combine the phenotypes caused by mutations in KCNH1, KCNK4, and KCNN3 in a group of neurological potassium channelopathies caused by an increase in K+ conductance.
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15
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Foster WJ, Taylor HBC, Padamsey Z, Jeans AF, Galione A, Emptage NJ. Hippocampal mGluR1-dependent long-term potentiation requires NAADP-mediated acidic store Ca 2+ signaling. Sci Signal 2018; 11:11/558/eaat9093. [PMID: 30482851 DOI: 10.1126/scisignal.aat9093] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Acidic organelles, such as endosomes and lysosomes, store Ca2+ that is released in response to intracellular increases in the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP). In neurons, NAADP and Ca2+ signaling contribute to synaptic plasticity, a process of activity-dependent long-term potentiation (LTP) [or, alternatively, long-term depression (LTD)] of synaptic strength and neuronal transmission that is critical for neuronal function and memory formation. We explored the function of and mechanisms regulating acidic Ca2+ store signaling in murine hippocampal neurons. We found that metabotropic glutamate receptor 1 (mGluR1) was coupled to NAADP signaling that elicited Ca2+ release from acidic stores. In turn, this released Ca2+-mediated mGluR1-dependent LTP by transiently inhibiting SK-type K+ channels, possibly through the activation of protein phosphatase 2A. Genetically removing two-pore channels (TPCs), which are endolysosomal-specific ion channels, switched the polarity of plasticity from LTP to LTD, indicating the importance of specific receptor store coupling and providing mechanistic insight into how mGluR1 can produce both synaptic potentiation and synaptic depression.
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Affiliation(s)
- William J Foster
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Henry B C Taylor
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Zahid Padamsey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Alexander F Jeans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
| | - Nigel J Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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16
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Kshatri AS, Gonzalez-Hernandez A, Giraldez T. Physiological Roles and Therapeutic Potential of Ca 2+ Activated Potassium Channels in the Nervous System. Front Mol Neurosci 2018; 11:258. [PMID: 30104956 PMCID: PMC6077210 DOI: 10.3389/fnmol.2018.00258] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/06/2018] [Indexed: 12/21/2022] Open
Abstract
Within the potassium ion channel family, calcium activated potassium (KCa) channels are unique in their ability to couple intracellular Ca2+ signals to membrane potential variations. KCa channels are diversely distributed throughout the central nervous system and play fundamental roles ranging from regulating neuronal excitability to controlling neurotransmitter release. The physiological versatility of KCa channels is enhanced by alternative splicing and co-assembly with auxiliary subunits, leading to fundamental differences in distribution, subunit composition and pharmacological profiles. Thus, understanding specific KCa channels’ mechanisms in neuronal function is challenging. Based on their single channel conductance, KCa channels are divided into three subtypes: small (SK, 4–14 pS), intermediate (IK, 32–39 pS) and big potassium (BK, 200–300 pS) channels. This review describes the biophysical characteristics of these KCa channels, as well as their physiological roles and pathological implications. In addition, we also discuss the current pharmacological strategies and challenges to target KCa channels for the treatment of various neurological and psychiatric disorders.
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Affiliation(s)
- Aravind S Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Alberto Gonzalez-Hernandez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
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17
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Chung BYT, Bailey CDC. Similar nicotinic excitability responses across the developing hippocampal formation are regulated by small-conductance calcium-activated potassium channels. J Neurophysiol 2018; 119:1707-1722. [PMID: 29384449 DOI: 10.1152/jn.00426.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hippocampal formation forms a cognitive circuit that is critical for learning and memory. Cholinergic input to nicotinic acetylcholine receptors plays an important role in the normal development of principal neurons within the hippocampal formation. However, the ability of nicotinic receptors to stimulate principal neurons across all regions of the developing hippocampal formation has not been determined. We show in this study that heteromeric nicotinic receptors mediate direct inward current and depolarization responses in principal neurons across the hippocampal formation of the young postnatal mouse. These responses were found in principal neurons of the CA1, CA3, dentate gyrus, subiculum, and entorhinal cortex layer VI, and they varied in magnitude across regions with the greatest responses occurring in the subiculum and entorhinal cortex. Despite this regional variation in the magnitude of passive responses, heteromeric nicotinic receptor stimulation increased the excitability of active principal neurons by a similar amount in all regions. Pharmacological experiments found this similar excitability response to be regulated by small-conductance calcium-activated potassium (SK) channels, which exhibited regional differences in their influence on neuron activity that offset the observed regional differences in passive nicotinic responses. These findings demonstrate that SK channels play a role to coordinate the magnitude of heteromeric nicotinic excitability responses across the hippocampal formation at a time when nicotinic signaling drives the development of this cognitive brain region. This coordinated input may contribute to the normal development, synchrony, and maturation of the hippocampal formation learning and memory network. NEW & NOTEWORTHY This study demonstrates that small-conductance calcium-activated potassium channels regulate similar-magnitude excitability responses to heteromeric nicotinic acetylcholine receptor stimulation in active principal neurons across multiple regions of the developing mouse hippocampal formation. Given the importance of nicotinic neurotransmission for the development of principal neurons within the hippocampal formation, this coordinated excitability response is positioned to influence the normal development, synchrony, and maturation of the hippocampal formation learning and memory network.
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Affiliation(s)
- Beryl Y T Chung
- Department of Biomedical Sciences, University of Guelph , Guelph, Ontario , Canada
| | - Craig D C Bailey
- Department of Biomedical Sciences, University of Guelph , Guelph, Ontario , Canada
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18
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Navidhamidi M, Ghasemi M, Mehranfard N. Epilepsy-associated alterations in hippocampal excitability. Rev Neurosci 2018; 28:307-334. [PMID: 28099137 DOI: 10.1515/revneuro-2016-0059] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/03/2016] [Indexed: 11/15/2022]
Abstract
The hippocampus exhibits a wide range of epilepsy-related abnormalities and is situated in the mesial temporal lobe, where limbic seizures begin. These abnormalities could affect membrane excitability and lead to overstimulation of neurons. Multiple overlapping processes refer to neural homeostatic responses develop in neurons that work together to restore neuronal firing rates to control levels. Nevertheless, homeostatic mechanisms are unable to restore normal neuronal excitability, and the epileptic hippocampus becomes hyperexcitable or hypoexcitable. Studies show that there is hyperexcitability even before starting recurrent spontaneous seizures, suggesting although hippocampal hyperexcitability may contribute to epileptogenesis, it alone is insufficient to produce epileptic seizures. This supports the concept that the hippocampus is not the only substrate for limbic seizure onset, and a broader hyperexcitable limbic structure may contribute to temporal lobe epilepsy (TLE) seizures. Nevertheless, seizures also occur in conditions where the hippocampus shows a hypoexcitable phenotype. Since TLE seizures most often originate in the hippocampus, it could therefore be assumed that both hippocampal hypoexcitability and hyperexcitability are undesirable states that make the epileptic hippocampal network less stable and may, under certain conditions, trigger seizures.
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19
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Robles Gómez AA, Vega AV, Gónzalez-Sandoval C, Barral J. The role of Ca 2+ -dependent K + - channels at the rat corticostriatal synapses revealed by paired pulse stimulation. Synapse 2017; 72. [PMID: 29136290 DOI: 10.1002/syn.22017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 11/09/2017] [Accepted: 11/09/2017] [Indexed: 01/23/2023]
Abstract
Potassium channels play an important role in modulating synaptic activity both at presynaptic and postsynaptic levels. We have shown before that presynaptically located KV and KIR channels modulate the strength of corticostriatal synapses in rat brain, but the role of other types of potassium channels at these synapses remains largely unknown. Here, we show that calcium-dependent potassium channels BK-type but not SK-type channels are located presynaptically in corticostriatal synapses. We stimulated cortical neurons in rat brain slices and recorded postsynaptic excitatory potentials (EPSP) in medium spiny neurons (MSN) in dorsal neostriatum. By using a paired pulse protocol, we induced synaptic facilitation before applying either BK- or SK-specific toxins. Thus, we found that blockage of BKCa with iberiotoxin (10 nM) reduces synaptic facilitation and increases the amplitude of the EPSP, while exposure to SK-blocker apamin (100 nM) has no effect. Additionally, we induced train action potentials on striatal MSN by current injection before and after the exposure to KCa toxins. We found that the action potential becomes broader when the MSN is exposed to iberiotoxin, although it has no impact on frequency. In contrast, exposure to apamin results in loss of afterhyperpolarization phase and an increase of spike frequency. Therefore, we concluded that postsynaptic SK channels are involved in afterhyperpolarization and modulation of spike frequency while the BK channels are involved on the late repolarization phase of the action potential. Altogether, our results show that calcium-dependent potassium channels modulate both input towards and output from the striatum.
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Affiliation(s)
| | - Ana V Vega
- Carrera de Médico Cirujano, UBIMED, FES Iztacala UNAM, México
| | | | - Jaime Barral
- Neurociencias, UIICSE, FES Iztacala, UNAM, México
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20
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Correa AMB, Guimarães JDS, Dos Santos E Alhadas E, Kushmerick C. Control of neuronal excitability by Group I metabotropic glutamate receptors. Biophys Rev 2017; 9:835-845. [PMID: 28836161 PMCID: PMC5662043 DOI: 10.1007/s12551-017-0301-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 07/27/2017] [Indexed: 12/12/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors couple through G proteins to regulate a large number of cell functions. Eight mGlu receptor isoforms have been cloned and classified into three Groups based on sequence, signal transduction mechanisms and pharmacology. This review will focus on Group I mGlu receptors, comprising the isoforms mGlu1 and mGlu5. Activation of these receptors initiates both G protein-dependent and -independent signal transduction pathways. The G-protein-dependent pathway involves mainly Gαq, which can activate PLCβ, leading initially to the formation of IP3 and diacylglycerol. IP3 can release Ca2+ from cellular stores resulting in activation of Ca2+-dependent ion channels. Intracellular Ca2+, together with diacylglycerol, activates PKC, which has many protein targets, including ion channels. Thus, activation of the G-protein-dependent pathway affects cellular excitability though several different effectors. In parallel, G protein-independent pathways lead to activation of non-selective cationic currents and metabotropic synaptic currents and potentials. Here, we provide a survey of the membrane transport proteins responsible for these electrical effects of Group I metabotropic glutamate receptors.
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Affiliation(s)
- Ana Maria Bernal Correa
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | | | - Christopher Kushmerick
- Graduate Program in Physiology and Pharmacology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
- Departamento de Fisiologia e Biofísica - ICB, UFMG, Av. Pres. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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21
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Roles of Na +, Ca 2+, and K + channels in the generation of repetitive firing and rhythmic bursting in adrenal chromaffin cells. Pflugers Arch 2017; 470:39-52. [PMID: 28776261 DOI: 10.1007/s00424-017-2048-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 07/23/2017] [Indexed: 12/30/2022]
Abstract
Adrenal chromaffin cells (CCs) are the main source of circulating catecholamines (CAs) that regulate the body response to stress. Release of CAs is controlled neurogenically by the activity of preganglionic sympathetic neurons through trains of action potentials (APs). APs in CCs are generated by robust depolarization following the activation of nicotinic and muscarinic receptors that are highly expressed in CCs. Bovine, rat, mouse, and human CCs also express a composite array of Na+, K+, and Ca2+ channels that regulate the resting potential, shape the APs, and set the frequency of AP trains. AP trains of increasing frequency induce enhanced release of CAs. If the primary role of CCs is simply to relay preganglionic nerve commands to CA secretion, why should they express such a diverse set of ion channels? An answer to this comes from recent observations that, like in neurons, CCs undergo complex firing patterns of APs suggesting the existence of an intrinsic CC excitability (non-neurogenically controlled). Recent work has shown that CCs undergo occasional or persistent burst firing elicited by altered physiological conditions or deletion of pore-regulating auxiliary subunits. In this review, we aim to give a rationale to the role of the many ion channel types regulating CC excitability. We will first describe their functional properties and then analyze how they contribute to pacemaking, AP shape, and burst waveforms. We will also furnish clear indications on missing ion conductances that may be involved in pacemaking and highlight the contribution of the crucial channels involved in burst firing.
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22
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Hydrogen peroxide modulates neuronal excitability and membrane properties in ventral horn neurons of the rat spinal cord. Neuroscience 2016; 331:206-20. [DOI: 10.1016/j.neuroscience.2016.06.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/27/2016] [Accepted: 06/17/2016] [Indexed: 01/29/2023]
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Meadows JP, Guzman-Karlsson MC, Phillips S, Brown JA, Strange SK, Sweatt JD, Hablitz JJ. Dynamic DNA methylation regulates neuronal intrinsic membrane excitability. Sci Signal 2016; 9:ra83. [PMID: 27555660 DOI: 10.1126/scisignal.aaf5642] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epigenetic modifications, such as DNA cytosine methylation, contribute to the mechanisms underlying learning and memory by coordinating adaptive gene expression and neuronal plasticity. Transcription-dependent plasticity regulated by DNA methylation includes synaptic plasticity and homeostatic synaptic scaling. Memory-related plasticity also includes alterations in intrinsic membrane excitability mediated by changes in the abundance or activity of ion channels in the plasma membrane, which sets the threshold for action potential generation. We found that prolonged inhibition of DNA methyltransferase (DNMT) activity increased intrinsic membrane excitability of cultured cortical pyramidal neurons. Knockdown of the cytosine demethylase TET1 or inhibition of RNA polymerase blocked the increased membrane excitability caused by DNMT inhibition, suggesting that this effect was mediated by subsequent cytosine demethylation and de novo transcription. Prolonged DNMT inhibition blunted the medium component of the after-hyperpolarization potential, an effect that would increase neuronal excitability, and was associated with reduced expression of the genes encoding small-conductance Ca(2+)-activated K(+) (SK) channels. Furthermore, the specific SK channel blocker apamin increased neuronal excitability but was ineffective after DNMT inhibition. Our results suggested that DNMT inhibition enables transcriptional changes that culminate in decreased expression of SK channel-encoding genes and decreased activity of SK channels, thus providing a mechanism for the regulation of neuronal intrinsic membrane excitability by dynamic DNA cytosine methylation. This study has implications for human neurological and psychiatric diseases associated with dysregulated intrinsic excitability.
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Affiliation(s)
- Jarrod P Meadows
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Mikael C Guzman-Karlsson
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Scott Phillips
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jordan A Brown
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Sarah K Strange
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - J David Sweatt
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - John J Hablitz
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Regulation of excitability in tonic firing substantia gelatinosa neurons of the spinal cord by small-conductance Ca 2+ -activated K + channels. Neuropharmacology 2016; 105:15-24. [DOI: 10.1016/j.neuropharm.2016.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 11/30/2015] [Accepted: 01/03/2016] [Indexed: 01/23/2023]
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25
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Richter M, Vidovic N, Honrath B, Mahavadi P, Dodel R, Dolga AM, Culmsee C. Activation of SK2 channels preserves ER Ca²⁺ homeostasis and protects against ER stress-induced cell death. Cell Death Differ 2015; 23:814-27. [PMID: 26586570 DOI: 10.1038/cdd.2015.146] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 09/03/2015] [Accepted: 09/21/2015] [Indexed: 01/24/2023] Open
Abstract
Alteration of endoplasmic reticulum (ER) Ca(2+) homeostasis leads to excessive cytosolic Ca(2+) accumulation and delayed neuronal cell death in acute and chronic neurodegenerative disorders. While our recent studies established a protective role for SK channels against excessive intracellular Ca(2+) accumulation, their functional role in the ER has not been elucidated yet. We show here that SK2 channels are present in ER membranes of neuronal HT-22 cells, and that positive pharmacological modulation of SK2 channels with CyPPA protects against cell death induced by the ER stressors brefeldin A and tunicamycin. Calcium imaging of HT-22 neurons revealed that elevated cytosolic Ca(2+) levels and decreased ER Ca(2+) load during sustained ER stress could be largely prevented by SK2 channel activation. Interestingly, SK2 channel activation reduced the amount of the unfolded protein response transcription factor ATF4, but further enhanced the induction of CHOP. Using siRNA approaches we confirmed a detrimental role for ATF4 in ER stress, whereas CHOP regulation was dispensable for both, brefeldin A toxicity and CyPPA-mediated protection. Cell death induced by blocking Ca(2+) influx into the ER with the SERCA inhibitor thapsigargin was not prevented by CyPPA. Blocking the K(+) efflux via K(+)/H(+) exchangers with quinine inhibited CyPPA-mediated neuroprotection, suggesting an essential role of proton uptake and K(+) release in the SK channel-mediated neuroprotection. Our data demonstrate that ER SK2 channel activation preserves ER Ca(2+) uptake and retention which determines cell survival in conditions where sustained ER stress contributes to progressive neuronal death.
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Affiliation(s)
- M Richter
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany.,Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - N Vidovic
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - B Honrath
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany
| | - P Mahavadi
- Department of Internal Medicine, Justus-Liebig-University, Giessen, Germany.,Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Giessen, Germany
| | - R Dodel
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - A M Dolga
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany.,Faculty of Mathematics and Natural Sciences, Molecular Pharmacology - Groningen Research Institute of Pharmacy, Groningen, The Netherlands
| | - C Culmsee
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany
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Maurice N, Deltheil T, Melon C, Degos B, Mourre C, Amalric M, Kerkerian-Le Goff L. Bee Venom Alleviates Motor Deficits and Modulates the Transfer of Cortical Information through the Basal Ganglia in Rat Models of Parkinson's Disease. PLoS One 2015; 10:e0142838. [PMID: 26571268 PMCID: PMC4646345 DOI: 10.1371/journal.pone.0142838] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/27/2015] [Indexed: 11/19/2022] Open
Abstract
Recent evidence points to a neuroprotective action of bee venom on nigral dopamine neurons in animal models of Parkinson’s disease (PD). Here we examined whether bee venom also displays a symptomatic action by acting on the pathological functioning of the basal ganglia in rat PD models. Bee venom effects were assessed by combining motor behavior analyses and in vivo electrophysiological recordings in the substantia nigra pars reticulata (SNr, basal ganglia output structure) in pharmacological (neuroleptic treatment) and lesional (unilateral intranigral 6-hydroxydopamine injection) PD models. In the hemi-parkinsonian 6-hydroxydopamine lesion model, subchronic bee venom treatment significantly alleviates contralateral forelimb akinesia and apomorphine-induced rotations. Moreover, a single injection of bee venom reverses haloperidol-induced catalepsy, a pharmacological model reminiscent of parkinsonian akinetic deficit. This effect is mimicked by apamin, a blocker of small conductance Ca2+-activated K+ (SK) channels, and blocked by CyPPA, a positive modulator of these channels, suggesting the involvement of SK channels in the bee venom antiparkinsonian action. In vivo electrophysiological recordings in the substantia nigra pars reticulata (basal ganglia output structure) showed no significant effect of BV on the mean neuronal discharge frequency or pathological bursting activity. In contrast, analyses of the neuronal responses evoked by motor cortex stimulation show that bee venom reverses the 6-OHDA- and neuroleptic-induced biases in the influence exerted by the direct inhibitory and indirect excitatory striatonigral circuits. These data provide the first evidence for a beneficial action of bee venom on the pathological functioning of the cortico-basal ganglia circuits underlying motor PD symptoms with potential relevance to the symptomatic treatment of this disease.
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Affiliation(s)
- Nicolas Maurice
- Aix Marseille Université, CNRS, IBDM UMR 7288, Marseille, France
- * E-mail:
| | | | - Christophe Melon
- Aix Marseille Université, CNRS, IBDM UMR 7288, Marseille, France
| | - Bertrand Degos
- INSERM, CNRS, Collège de France, CIRB UMR 7241 U-1050, Paris, France
- APHP, Département des Maladies du Système Nerveux, Centre Expert Inter-Régional Ile de France de la Maladie de Parkinson, Hôpital Pitié-Salpêtrière, Paris, France
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27
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Thompson JM, Ji G, Neugebauer V. Small-conductance calcium-activated potassium (SK) channels in the amygdala mediate pain-inhibiting effects of clinically available riluzole in a rat model of arthritis pain. Mol Pain 2015; 11:51. [PMID: 26311432 PMCID: PMC4551697 DOI: 10.1186/s12990-015-0055-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/21/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Arthritis pain is an important healthcare issue with significant emotional and affective consequences. Here we focus on potentially beneficial effects of activating small-conductance calcium-activated potassium (SK) channels in the amygdala, a brain center of emotions that plays an important role in central pain modulation and processing. SK channels have been reported to regulate neuronal activity in the central amygdala (CeA, output nucleus). We tested the effects of riluzole, a clinically available drug for the treatment of amyotrophic lateral sclerosis, for the following reasons. Actions of riluzole include activation of SK channels. Evidence in the literature suggests that riluzole may have antinociceptive effects through an action in the brain but not the spinal cord. Mechanism and site of action of riluzole remain to be determined. Here we tested the hypothesis that riluzole inhibits pain behaviors by acting on SK channels in the CeA in an arthritis pain model. RESULTS Systemic (intraperitoneal) application of riluzole (8 mg/kg) inhibited audible (nocifensive response) and ultrasonic (averse affective response) vocalizations of adult rats with arthritis (5 h postinduction of a kaolin-carrageenan monoarthritis in the knee) but did not affect spinal withdrawal thresholds, which is consistent with a supraspinal action. Stereotaxic administration of riluzole into the CeA by microdialysis (1 mM, concentration in the microdialysis fiber, 15 min) also inhibited vocalizations, confirming the CeA as a site of action of riluzole. Stereotaxic administration of a selective SK channel blocker (apamin, 1 µM, concentration in the microdialysis fiber, 15 min) into the CeA had no effect by itself but inhibited the effect of systemic riluzole on vocalizations. Off-site administration of apamin into the basolateral amygdala (BLA) as a placement control or stereotaxic application of a selective blocker of large-conductance calcium-activated potassium (BK) channels (charybdotoxin, 1 µM, concentration in the microdialysis fiber, 15 min) into the CeA did not affect the inhibitory effects of systemically applied riluzole. CONCLUSIONS The results suggest that riluzole can inhibit supraspinally organized pain behaviors in an arthritis model by activating SK, but not BK, channels in the amygdala (CeA but not BLA).
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Affiliation(s)
- Jeremy M Thompson
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX, 79430-6592, USA.
| | - Guangchen Ji
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX, 79430-6592, USA.
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, 3601 4th St, Lubbock, TX, 79430-6592, USA.
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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28
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Rau AR, Ariwodola OJ, Weiner JL. Postsynaptic adenosine A2A receptors modulate intrinsic excitability of pyramidal cells in the rat basolateral amygdala. Int J Neuropsychopharmacol 2015; 18:pyv017. [PMID: 25716780 PMCID: PMC4438553 DOI: 10.1093/ijnp/pyv017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The basolateral amygdala plays a critical role in the etiology of anxiety disorders and addiction. Pyramidal neurons, the primary output cells of this region, display increased firing following exposure to stressors, and it is thought that this increase in excitability contributes to stress responsivity and the expression of anxiety-like behaviors. However, much remains unknown about the underlying mechanisms that regulate the intrinsic excitability of basolateral amygdala pyramidal neurons. METHODS Ex vivo gramicidin perforated patch recordings were conducted in current clamp mode where hyper- and depolarizing current steps were applied to basolateral amygdala pyramidal neurons to assess the effects of adenosine A(2A) receptor modulation on intrinsic excitability. RESULTS Activation of adenosine A(2A) receptors with the selective A(2A) receptor agonist CGS-21680 significantly increased the firing rate of basolateral amygdala pyramidal neurons in rat amygdala brain slices, likely via inhibition of the slow afterhyperpolarization potential. Both of these A(2A) receptor-mediated effects were blocked by preapplication of a selective A(2A) receptor antagonist (ZM-241385) or by intra-pipette infusion of a protein kinase A inhibitor, suggesting a postsynaptic locus of A(2A) receptors on basolateral amygdala pyramidal neurons. Interestingly, bath application of the A(2A) receptor antagonist alone significantly attenuated basolateral amygdala pyramidal cell firing, consistent with a role for tonic adenosine in the regulation of the intrinsic excitability of these neurons. CONCLUSIONS Collectively, these data suggest that adenosine, via activation of A(2A) receptors, may directly facilitate basolateral amygdala pyramidal cell output, providing a possible balance for the recently described inhibitory effects of adenosine A1 receptor activation on glutamatergic excitation of basolateral amygdala pyramidal cells.
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Affiliation(s)
- Andrew R Rau
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina
| | - Olusegun J Ariwodola
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina
| | - Jeff L Weiner
- Department of Physiology and Pharmacology, School of Medicine (Mr Rau, Mr Ariwodola, and Dr Weiner), Neuroscience Graduate Program, Graduate School of Arts and Sciences (Mr Rau), Wake Forest University, Winston-Salem, North Carolina.
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29
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Vandael DHF, Marcantoni A, Carbone E. Cav1.3 Channels as Key Regulators of Neuron-Like Firings and Catecholamine Release in Chromaffin Cells. Curr Mol Pharmacol 2015; 8:149-61. [PMID: 25966692 PMCID: PMC5384372 DOI: 10.2174/1874467208666150507105443] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 01/31/2015] [Accepted: 04/20/2015] [Indexed: 12/19/2022]
Abstract
Neuronal and neuroendocrine L-type calcium channels (Cav1.2, Cav1.3) open readily at relatively low membrane potentials and allow Ca(2+) to enter the cells near resting potentials. In this way, Cav1.2 and Cav1.3 shape the action potential waveform, contribute to gene expression, synaptic plasticity, neuronal differentiation, hormone secretion and pacemaker activity. In the chromaffin cells (CCs) of the adrenal medulla, Cav1.3 is highly expressed and is shown to support most of the pacemaking current that sustains action potential (AP) firings and part of the catecholamine secretion. Cav1.3 forms Ca(2+)-nanodomains with the fast inactivating BK channels and drives the resting SK currents. These latter set the inter-spike interval duration between consecutive spikes during spontaneous firing and the rate of spike adaptation during sustained depolarizations. Cav1.3 plays also a primary role in the switch from "tonic" to "burst" firing that occurs in mouse CCs when either the availability of voltage-gated Na channels (Nav) is reduced or the β2 subunit featuring the fast inactivating BK channels is deleted. Here, we discuss the functional role of these "neuron-like" firing modes in CCs and how Cav1.3 contributes to them. The open issue is to understand how these novel firing patterns are adapted to regulate the quantity of circulating catecholamines during resting condition or in response to acute and chronic stress.
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Affiliation(s)
| | | | - Emilio Carbone
- Department of Drug Science, Corso Raffaello 30, I - 10125 Torino, Italy.
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30
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Deardorff AS, Romer SH, Sonner PM, Fyffe REW. Swimming against the tide: investigations of the C-bouton synapse. Front Neural Circuits 2014; 8:106. [PMID: 25278842 PMCID: PMC4167003 DOI: 10.3389/fncir.2014.00106] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/17/2014] [Indexed: 11/19/2022] Open
Abstract
C-boutons are important cholinergic modulatory loci for state-dependent alterations in motoneuron firing rate. m2 receptors are concentrated postsynaptic to C-boutons, and m2 receptor activation increases motoneuron excitability by reducing the action potential afterhyperpolarization. Here, using an intensive review of the current literature as well as data from our laboratory, we illustrate that C-bouton postsynaptic sites comprise a unique structural/functional domain containing appropriate cellular machinery (a “signaling ensemble”) for cholinergic regulation of outward K+ currents. Moreover, synaptic reorganization at these critical sites has been observed in a variety of pathologic states. Yet despite recent advances, there are still great challenges for understanding the role of C-bouton regulation and dysregulation in human health and disease. The development of new therapeutic interventions for devastating neurological conditions will rely on a complete understanding of the molecular mechanisms that underlie these complex synapses. Therefore, to close this review, we propose a comprehensive hypothetical mechanism for the cholinergic modification of α-MN excitability at C-bouton synapses, based on findings in several well-characterized neuronal systems.
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Affiliation(s)
- Adam S Deardorff
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Shannon H Romer
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Patrick M Sonner
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
| | - Robert E W Fyffe
- Boonshoft School of Medicine, Department of Neuroscience, Cell Biology and Physiology, Wright State University Dayton, OH, USA
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31
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SK channel blockade reverses cognitive and motor deficits induced by nigrostriatal dopamine lesions in rats. Int J Neuropsychopharmacol 2014; 17:1295-306. [PMID: 24661728 DOI: 10.1017/s1461145714000236] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parkinson's disease has traditionally been viewed as a motor disorder caused by the loss of dopamine (DA) neurons. However, emotional and cognitive syndromes can precede the onset of the motor deficits and provide an opportunity for therapeutic intervention. Potassium channels have recently emerged as potential new targets in the treatment of Parkinson's disease. The selective blockade of small conductance calcium-activated K+ channels (SK channels) by apamin is known to increase burst firing in midbrain DA neurons and therefore DA release. We thus investigated the effects of systemic administration of apamin on the motor, cognitive deficits and anxiety present after bilateral nigrostriatal 6-hydroxydopamine (6-OHDA) lesions in rats. Apamin administration (0.1 or 0.3 mg/kg i.p.) counteracted the depression, anxiety-like behaviors evaluated on sucrose consumption and in the elevated plus maze, social recognition and spatial memory deficits produced by partial 6-OHDA lesions. Apamin also reduced asymmetric motor deficits on circling behavior and postural adjustments in the unilateral extensive 6-OHDA model. The partial 6-OHDA lesions (56% striatal DA depletion) produced 20% decrease of iodinated apamin binding sites in the substantia nigra pars compacta in correlation with the loss of tyrosine hydroxylase positive cells, without modifying apamin binding in brain regions receiving DAergic innervation. Striatal extracellular levels of DA, not detectable after 6-OHDA lesions, were enhanced by apamin treatment as measured by in vivo microdialysis. These results indicate that blocking SK channels may reinstate minimal DA activity in the striatum to alleviate the non-motor symptoms induced by partial striatal DA lesions.
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32
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Gagnon A, Walsh M, Okuda T, Choe KY, Zaelzer C, Bourque CW. Modulation of spike clustering by NMDA receptors and neurotensin in rat supraoptic nucleus neurons. J Physiol 2014; 592:4177-86. [PMID: 25063824 DOI: 10.1113/jphysiol.2014.275602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Magnocellular neurosecretory cells (MNCs) in the rat supraoptic nucleus display clustered firing during hyperosmolality or dehydration. This response is beneficial because this type of activity potentiates vasopressin secretion from axon terminals in the neurohypophysis and thus promotes homoeostatic water reabsorption from the kidney. However, the mechanisms which lead to the generation of clustering activity in MNCs remain unknown. Previous work has shown that clustered firing can be induced in these neurons through the pharmacological activation of NMDA receptors (NMDARs) and that silent pauses observed during this activity are mediated by apamin-sensitive calcium activated potassium (SK) channels. However, it remains unknown if clustered firing can be induced in situ by endogenous glutamate release from axon terminals. Here we show that electrical stimulation of glutamatergic osmosensory afferents in the organum vasculosum lamina terminalis (OVLT) can promote clustering in MNCs via NMDARs and apamin-sensitive channels.We also show that the rate of spike clustering induced by NMDA varies as a bell-shaped function of voltage, and that partial inhibition of SK channels can increase cluster duration and reduce the rate of clustering. Finally,we show that MNCs express neurotensin type 2 receptors, and that activation of these receptors can simultaneously depolarize MNCs and suppress clustered firing induced by bath application of NMDA or by repetitive stimulation of glutamate afferents. These studies reveal that spike clustering can be induced in MNCs by glutamate release from afferent nerve terminals and that that this type of activity can be fine-tuned by neuromodulators such as neurotensin.
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Affiliation(s)
- Ariane Gagnon
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
| | - Michael Walsh
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
| | - Tika Okuda
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
| | - Katrina Y Choe
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
| | - Cristian Zaelzer
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
| | - Charles W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Montreal QC, Canada H3G 1A4
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Tuckwell HC, Penington NJ. Computational modeling of spike generation in serotonergic neurons of the dorsal raphe nucleus. Prog Neurobiol 2014; 118:59-101. [PMID: 24784445 DOI: 10.1016/j.pneurobio.2014.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 04/14/2014] [Accepted: 04/21/2014] [Indexed: 01/14/2023]
Abstract
Serotonergic neurons of the dorsal raphe nucleus, with their extensive innervation of limbic and higher brain regions and interactions with the endocrine system have important modulatory or regulatory effects on many cognitive, emotional and physiological processes. They have been strongly implicated in responses to stress and in the occurrence of major depressive disorder and other psychiatric disorders. In order to quantify some of these effects, detailed mathematical models of the activity of such cells are required which describe their complex neurochemistry and neurophysiology. We consider here a single-compartment model of these neurons which is capable of describing many of the known features of spike generation, particularly the slow rhythmic pacemaking activity often observed in these cells in a variety of species. Included in the model are 11 kinds of ion channels: a fast sodium current INa, a delayed rectifier potassium current IKDR, a transient potassium current IA, a slow non-inactivating potassium current IM, a low-threshold calcium current IT, two high threshold calcium currents IL and IN, small and large conductance potassium currents ISK and IBK, a hyperpolarization-activated cation current IH and a leak current ILeak. In Sections 3-8, each current type is considered in detail and parameters estimated from voltage clamp data where possible. Three kinds of model are considered for the BK current and two for the leak current. Intracellular calcium ion concentration Cai is an additional component and calcium dynamics along with buffering and pumping is discussed in Section 9. The remainder of the article contains descriptions of computed solutions which reveal both spontaneous and driven spiking with several parameter sets. Attention is focused on the properties usually associated with these neurons, particularly long duration of action potential, steep upslope on the leading edge of spikes, pacemaker-like spiking, long-lasting afterhyperpolarization and the ramp-like return to threshold after a spike. In some cases the membrane potential trajectories display doublets or have humps or notches as have been reported in some experimental studies. The computed time courses of IA and IT during the interspike interval support the generally held view of a competition between them in influencing the frequency of spiking. Spontaneous activity was facilitated by the presence of IH which has been found in these neurons by some investigators. For reasonable sets of parameters spike frequencies between about 0.6Hz and 1.2Hz are obtained, but frequencies as high as 6Hz could be obtained with special parameter choices. Topics investigated and compared with experiment include shoulders, notches, anodal break phenomena, the effects of noradrenergic input, frequency versus current curves, depolarization block, effects of cell size and the effects of IM. The inhibitory effects of activating 5-HT1A autoreceptors are also investigated. There is a considerable discussion of in vitro versus in vivo firing behavior, with focus on the roles of noradrenergic input, corticotropin-releasing factor and orexinergic inputs. Location of cells within the nucleus is probably a major factor, along with the state of the animal.
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Affiliation(s)
- Henry C Tuckwell
- Max Planck Institute for Mathematics in the Sciences, Inselstr. 22, 04103 Leipzig, Germany; School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Nicholas J Penington
- Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Box 29, 450 Clarkson Avenue, Brooklyn, NY 11203-2098, USA; Program in Neural and Behavioral Science and Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Box 29, 450 Clarkson Avenue, Brooklyn, NY 11203-2098, USA
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Liégeois JF, Wouters J, Seutin V, Dilly S. Bis-(1,2,3,4-tetrahydroisoquinolinium): A Chiral Scaffold for Developing High-Affinity Ligands for SK Channels. ChemMedChem 2014; 9:737-40. [DOI: 10.1002/cmdc.201400028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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35
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Mateos-Aparicio P, Murphy R, Storm JF. Complementary functions of SK and Kv7/M potassium channels in excitability control and synaptic integration in rat hippocampal dentate granule cells. J Physiol 2013; 592:669-93. [PMID: 24366266 DOI: 10.1113/jphysiol.2013.267872] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dentate granule cells (DGCs) form the most numerous neuron population of the hippocampal memory system, and its gateway for cortical input. Yet, we have only limited knowledge of the intrinsic membrane properties that shape their responses. Since SK and Kv7/M potassium channels are key mechanisms of neuronal spiking and excitability control, afterhyperpolarizations (AHPs) and synaptic integration, we studied their functions in DGCs. The specific SK channel blockers apamin or scyllatoxin increased spike frequency (excitability), reduced early spike frequency adaptation, fully blocked the medium-duration AHP (mAHP) after a single spike or spike train, and increased postsynaptic EPSP summation after spiking, but had no effect on input resistance (Rinput) or spike threshold. In contrast, blockade of Kv7/M channels by XE991 increased Rinput, lowered the spike threshold, and increased excitability, postsynaptic EPSP summation, and EPSP-spike coupling, but only slightly reduced mAHP after spike trains (and not after single spikes). The SK and Kv7/M channel openers 1-EBIO and retigabine, respectively, had effects opposite to the blockers. Computational modelling reproduced many of these effects. We conclude that SK and Kv7/M channels have complementary roles in DGCs. These mechanisms may be important for the dentate network function, as CA3 neurons can be activated or inhibition recruited depending on DGC firing rate.
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Affiliation(s)
- Pedro Mateos-Aparicio
- Department of Physiology, IMB, University of Oslo, PB 1104 Blindern, 0317 Oslo, Norway.
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36
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González C, Baez-Nieto D, Valencia I, Oyarzún I, Rojas P, Naranjo D, Latorre R. K(+) channels: function-structural overview. Compr Physiol 2013; 2:2087-149. [PMID: 23723034 DOI: 10.1002/cphy.c110047] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Potassium channels are particularly important in determining the shape and duration of the action potential, controlling the membrane potential, modulating hormone secretion, epithelial function and, in the case of those K(+) channels activated by Ca(2+), damping excitatory signals. The multiplicity of roles played by K(+) channels is only possible to their mammoth diversity that includes at present 70 K(+) channels encoding genes in mammals. Today, thanks to the use of cloning, mutagenesis, and the more recent structural studies using x-ray crystallography, we are in a unique position to understand the origins of the enormous diversity of this superfamily of ion channels, the roles they play in different cell types, and the relations that exist between structure and function. With the exception of two-pore K(+) channels that are dimers, voltage-dependent K(+) channels are tetrameric assemblies and share an extremely well conserved pore region, in which the ion-selectivity filter resides. In the present overview, we discuss in the function, localization, and the relations between function and structure of the five different subfamilies of K(+) channels: (a) inward rectifiers, Kir; (b) four transmembrane segments-2 pores, K2P; (c) voltage-gated, Kv; (d) the Slo family; and (e) Ca(2+)-activated SK family, SKCa.
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Affiliation(s)
- Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Cabo R, Zichichi R, Viña E, Guerrera MC, Vázquez G, García-Suárez O, Vega JA, Germanà A. Calcium-activated potassium channel SK1 is widely expressed in the peripheral nervous system and sensory organs of adult zebrafish. Neurosci Lett 2013; 555:62-7. [PMID: 24060674 DOI: 10.1016/j.neulet.2013.09.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 06/13/2013] [Accepted: 09/10/2013] [Indexed: 10/26/2022]
Abstract
Sensory cells contain ion channels involved in the organ-specific transduction mechanisms that convert different types of stimuli into electric energy. Here we focus on small-conductance calcium-activated potassium channel 1 (SK1) which plays an important role in all excitable cells acting as feedback regulators in after-hyperpolarization. This study was undertaken to analyze the pattern of expression of SK1 in the zebrafish peripheral nervous system and sensory organs using RT-PRC, Westernblot and immunohistochemistry. Expression of SK1 mRNA was observed at all developmental stages analyzed (from 10 to 100 days post fertilization, dpf), and the antibody used identified a protein with a molecular weight of 70kDa, at 100dpf (regarded to be adult). Cell expressing SK1 in adult animals were neurons of dorsal root and cranial nerve sensory ganglia, sympathetic neurons, sensory cells in neuromasts of the lateral line system and taste buds, crypt olfactory neurons and photoreceptors. Present results report for the first time the expression and the distribution of SK1 in the peripheral nervous system and sensory organs of adult zebrafish, and may contribute to set zebrafish as an interesting experimental model for calcium-activated potassium channels research. Moreover these findings are of potential interest because the potential role of SK as targets for the treatment of neurological diseases and sensory disorders.
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Affiliation(s)
- R Cabo
- Departamento de Morfología y Biología Celular, Grupo SINPOS, Universidad de Oviedo, Spain
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Hoffman AF, Lupica CR. Synaptic targets of Δ9-tetrahydrocannabinol in the central nervous system. Cold Spring Harb Perspect Med 2013; 3:cshperspect.a012237. [PMID: 23209160 DOI: 10.1101/cshperspect.a012237] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The availability of potent synthetic agonists for cannabinoid receptors has facilitated our understanding of cannabinoid actions on synaptic transmission in the central nervous system. Moreover, the ability of these compounds to inhibit neurotransmitter release at many central synapses is thought to underlie most of the behavioral effects of cannabinoid agonists. However, despite the widespread use and misuse of marijuana, and recognition of its potential adverse psychological effects in humans, comparatively few studies have examined the actions of its primary psychoactive constituent, Δ(9)-tetrahydrocannabinol (THC), at well-defined synaptic pathways. Here we examine the recent literature describing the effects of acute and repeated THC exposure on synaptic function in several brain regions and explore the importance of these neurobiological actions of THC in drug addiction.
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Affiliation(s)
- Alexander F Hoffman
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Electrophysiology Research Section, Baltimore, Maryland 21224, USA
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39
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EGFR tyrosine kinase regulates human small-conductance Ca2+-activated K+ (hSKCa1) channels expressed in HEK-293 cells. Biochem J 2013; 452:121-9. [PMID: 23496660 DOI: 10.1042/bj20121324] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
SKCa (small-conductance Ca(2+)-activated K(+)) channels are widely distributed in different tissues, including the brain, pancreatic islets and myocardium and play an important role in controlling electrical activity and cellular functions. However, intracellular signal modulation of SKCa channels is not fully understood. The present study was designed to investigate the potential regulation of hSKCa1 (human SKCa1) channels by PTKs (protein tyrosine kinases) in HEK (human embryonic kidney)-293 cells expressing the hSKCa1 (KCNN1) gene using approaches of whole-cell patch voltage-clamp, immunoprecipitation, Western blotting and mutagenesis. We found that the hSKCa1 current was inhibited by the broad-spectrum PTK inhibitor genistein, the selective EGFR (epidermal growth factor receptor) kinase inhibitors T25 (tyrphostin 25) and AG556 (tyrphostin AG 556), but not by the Src-family kinases inhibitor PP2. The inhibitory effect of these PTK inhibitors was significantly antagonized by the PTP (protein tyrosine phosphatase) inhibitor orthovanadate. The tyrosine phosphorylation level of hSKCa1 channels was reduced by genistein, T25 or AG556. The reduced tyrosine phosphorylation was countered by orthovanadate. Interestingly, the Y109F mutant hSKCa1 channel lost the inhibitory response to T25 or AG556, and showed a dramatic reduction in tyrosine phosphorylation levels and a reduced current density. These results demonstrate the novel information that hSKCa1 channels are inhibited by genistein, T25 and AG556 via EGFR tyrosine kinase inhibition, which is related to the phosphorylation of Tyr(109) in the N-terminus. This effect may affect electrical activity and cellular functions in brain, pancreatic islets and myocardium.
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Li S, Liu ZC, Yin SJ, Chen YT, Yu HL, Zeng J, Zhang Q, Zhu F. Human endogenous retrovirus W family envelope gene activates the small conductance Ca2+-activated K+ channel in human neuroblastoma cells through CREB. Neuroscience 2013; 247:164-74. [PMID: 23727510 DOI: 10.1016/j.neuroscience.2013.05.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 05/17/2013] [Accepted: 05/17/2013] [Indexed: 11/25/2022]
Abstract
Numerous studies have shown that human endogenous retrovirus W family (HERV-W) envelope gene (env) is related to various diseases but the underlying mechanism has remained poorly understood. Our previous study showed that there was abnormal expression of HERV-W env in sera of patients with schizophrenia. In this paper, we reported that overexpression of the HERV-W env elevated the levels of small conductance Ca(2+)-activated K(+) channel protein 3 (SK3) in human neuroblastoma cells. Using a luciferase reporter system and RNA interference method, we found that functional cAMP response element site was required for the expression of SK3 triggered by HERV-W env. In addition, it was also found that the SK3 channel was activated by HERV-W env. Further study indicated that cAMP response element-binding protein (CREB) was required for the activation of the SK3 channel. Thus, a novel signaling mechanism of how HERV-W env influences neuronal activity and contributes to mental illnesses such as schizophrenia was proposed.
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Affiliation(s)
- S Li
- Department of Medical Microbiology, School of Medicine, Wuhan University, Wuhan 430071, PR China
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41
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Tidow H, Nissen P. Structural diversity of calmodulin binding to its target sites. FEBS J 2013; 280:5551-65. [PMID: 23601118 DOI: 10.1111/febs.12296] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/11/2013] [Accepted: 04/16/2013] [Indexed: 11/28/2022]
Abstract
Calmodulin (CaM) is a ubiquitous, highly conserved, eukaryotic protein that binds to and regulates a number of diverse target proteins involved in different functions such as metabolism, muscle contraction, apoptosis, memory, inflammation and the immune response. In this minireview, we analyze the large number of CaM-complex structures deposited in the Protein Data Bank (i.e. crystal and nuclear magnetic resonance structures) to gain insight into the structural diversity of CaM-binding sites and mechanisms, such as those for CaM-activated protein kinases and phosphatases, voltage-gated Ca(2+)-channels and the plasma membrane Ca(2+)-ATPase.
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Affiliation(s)
- Henning Tidow
- Centre for Membrane Pumps in Cells and Disease - PUMPkin, Aarhus University, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Denmark
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Ferreira R, Schlichter LC. Selective activation of KCa3.1 and CRAC channels by P2Y2 receptors promotes Ca(2+) signaling, store refilling and migration of rat microglial cells. PLoS One 2013; 8:e62345. [PMID: 23620825 PMCID: PMC3631179 DOI: 10.1371/journal.pone.0062345] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 03/20/2013] [Indexed: 12/26/2022] Open
Abstract
Microglial activation involves Ca(2+) signaling, and numerous receptors can evoke elevation of intracellular Ca(2+). ATP released from damaged brain cells can activate ionotropic and metabotropic purinergic receptors, and act as a chemoattractant for microglia. Metabotropic P2Y receptors evoke a Ca(2+) rise through release from intracellular Ca(2+) stores and store-operated Ca(2+) entry, and some have been implicated in microglial migration. This Ca(2+) rise is expected to activate small-conductance Ca(2+)-dependent K(+) (SK) channels, if present. We previously found that SK3 (KCa2.3) and KCa3.1 (SK4/IK1) are expressed in rat microglia and contribute to LPS-mediated activation and neurotoxicity. However, neither current has been studied by elevating Ca(2+) during whole-cell recordings. We hypothesized that, rather than responding only to Ca(2+), each channel type might be coupled to different receptor-mediated pathways. Here, our objective was to determine whether the channels are differentially activated by P2Y receptors, and, if so, whether they play differing roles. We used primary rat microglia and a rat microglial cell line (MLS-9) in which riluzole robustly activates both SK3 and KCa3.1 currents. Using electrophysiological, Ca(2+) imaging and pharmacological approaches, we show selective functional coupling of KCa3.1 to UTP-mediated P2Y2 receptor activation. KCa3.1 current is activated by Ca(2+) entry through Ca(2+)-release-activated Ca(2+) (CRAC/Orai1) channels, and both CRAC/Orai1 and KCa3.1 channels facilitate refilling of Ca(2+) stores. The Ca(2+) dependence of KCa3.1 channel activation was skewed to abnormally high concentrations, and we present evidence for a close physical association of the two channel types. Finally, migration of primary rat microglia was stimulated by UTP and inhibited by blocking either KCa3.1 or CRAC/Orai1 channels. This is the first report of selective coupling of one type of SK channel to purinergic stimulation of microglia, transactivation of KCa3.1 channels by CRAC/Orai1, and coordinated roles for both channels in store refilling, Ca(2+) signaling and microglial migration.
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Affiliation(s)
- Roger Ferreira
- Genes and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lyanne C. Schlichter
- Genes and Development Division, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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Shemarova IV, Nesterov VP. Evolution of mechanisms of Ca2+-signalization. Role of Ca2+ in regulation of specialized cell functions. J EVOL BIOCHEM PHYS+ 2013. [DOI: 10.1134/s0022093013010027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Deardorff AS, Romer SH, Deng Z, Bullinger KL, Nardelli P, Cope TC, Fyffe REW. Expression of postsynaptic Ca2+-activated K+ (SK) channels at C-bouton synapses in mammalian lumbar -motoneurons. J Physiol 2013; 591:875-97. [PMID: 23129791 PMCID: PMC3591704 DOI: 10.1113/jphysiol.2012.240879] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 10/31/2012] [Indexed: 01/27/2023] Open
Abstract
Small-conductance calcium-activated potassium (SK) channels mediate medium after-hyperpolarization (AHP) conductances in neurons throughout the central nervous system. However, the expression profile and subcellular localization of different SK channel isoforms in lumbar spinal α-motoneurons (α-MNs) is unknown. Using immunohistochemical labelling of rat, mouse and cat spinal cord, we reveal a differential and overlapping expression of SK2 and SK3 isoforms across specific types of α-MNs. In rodents, SK2 is expressed in all α-MNs, whereas SK3 is expressed preferentially in small-diameter α-MNs; in cats, SK3 is expressed in all α-MNs. Function-specific expression of SK3 was explored using post hoc immunostaining of electrophysiologically characterized rat α-MNs in vivo. These studies revealed strong relationships between SK3 expression and medium AHP properties. Motoneurons with SK3-immunoreactivity exhibit significantly longer AHP half-decay times (24.67 vs. 11.02 ms) and greater AHP amplitudes (3.27 vs. 1.56 mV) than MNs lacking SK3-immunoreactivity. We conclude that the differential expression of SK isoforms in rat and mouse spinal cord may contribute to the range of medium AHP durations across specific MN functional types and may be a molecular factor distinguishing between slow- and fast-type α-MNs in rodents. Furthermore, our results show that SK2- and SK3-immunoreactivity is enriched in distinct postsynaptic domains that contain Kv2.1 channel clusters associated with cholinergic C-boutons on the soma and proximal dendrites of α-MNs. We suggest that this remarkably specific subcellular membrane localization of SK channels is likely to represent the basis for a cholinergic mechanism for effective regulation of channel function and cell excitability.
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Affiliation(s)
- Adam S Deardorff
- Department of Neuroscience, Cell Biology & Physiology, Wright State University, Boonshoft School of Medicine, Dayton, OH 45435, USA
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45
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The interactions of apamin and tetraethylammonium are differentially affected by single mutations in the pore mouth of small conductance calcium-activated potassium (SK) channels. Biochem Pharmacol 2013; 85:560-9. [DOI: 10.1016/j.bcp.2012.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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Ca(V)1.3-driven SK channel activation regulates pacemaking and spike frequency adaptation in mouse chromaffin cells. J Neurosci 2013; 32:16345-59. [PMID: 23152617 DOI: 10.1523/jneurosci.3715-12.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mouse chromaffin cells (MCCs) fire spontaneous action potentials (APs) at rest. Ca(v)1.3 L-type calcium channels sustain the pacemaker current, and their loss results in depolarized resting potentials (V(rest)), spike broadening, and remarkable switches into depolarization block after BayK 8644 application. A functional coupling between Ca(v)1.3 and BK channels has been reported but cannot fully account for the aforementioned observations. Here, using Ca(v)1.3(-/-) mice, we investigated the role of Ca(v)1.3 on SK channel activation and how this functional coupling affects the firing patterns induced by sustained current injections. MCCs express SK1-3 channels whose tonic currents are responsible for the slow irregular firing observed at rest. Percentage of frequency increase induced by apamin was found inversely correlated to basal firing frequency. Upon stimulation, MCCs build-up Ca(v)1.3-dependent SK currents during the interspike intervals that lead to a notable degree of spike frequency adaptation (SFA). The major contribution of Ca(v)1.3 to the subthreshold Ca(2+) charge during an AP-train rather than a specific molecular coupling to SK channels accounts for the reduced SFA of Ca(v)1.3(-/-) MCCs. Low adaptation ratios due to reduced SK activation associated with Ca(v)1.3 deficiency prevent the efficient recovery of Na(V) channels from inactivation. This promotes a rapid decline of AP amplitudes and facilitates early onset of depolarization block following prolonged stimulation. Thus, besides serving as pacemaker, Ca(v)1.3 slows down MCC firing by activating SK channels that maintain Na(V) channel availability high enough to preserve stable AP waveforms, even upon high-frequency stimulation of chromaffin cells during stress responses.
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47
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Ireland MF, Funk GD, Bellingham MC. Muscarinic acetylcholine receptors enhance neonatal mouse hypoglossal motoneuron excitability in vitro. J Appl Physiol (1985) 2012; 113:1024-39. [DOI: 10.1152/japplphysiol.00699.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In brain stem slices from neonatal ( postnatal days 0–4) CD-1 mice, muscarinic ACh receptors (MAChRs) increased rhythmic inspiratory-related and tonic hypoglossal nerve discharge and depolarized single hypoglossal motoneurons (HMs) via an inward current without changing input resistance. These responses were blocked by the MAChR antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; 100 nM). MAChRs shifted voltage-dependent activation of the hyperpolarization-activated cation current to more positive levels. MAChRs increased the HM repetitive firing rate and decreased rheobase, with both effects being blocked by 4-DAMP. Muscarinic agonists reduced the afterhyperpolarization of single action potentials (APs), suggesting that small-conductance Ca2+-dependent K+ current inhibition increased the HM firing rate. Muscarinic agonists also reduced the AP amplitude and slowed its time course, suggesting that MAChRs inhibited voltage-gated Na+ channels. To compare muscarinic excitation of single HMs to muscarinic excitatory effects on motor output in thicker brain stem slices requiring higher extracellular K+ for rhythmic activity, we tested the effects of muscarinic agonists on single HM excitability in high-K+ artificial cerebrospinal fluid (aCSF). In high-K+ aCSF, muscarinic agonists still depolarized HMs and altered AP size and shape, as in standard aCSF, but did not increase the steady-state firing rate, decrease afterhyperpolarization, or alter threshold potential. These results indicate that the basic cellular response of HMs to muscarinic receptors is excitatory, via a number of distinct mechanisms, and that this excitatory response will be largely preserved in rhythmically active brain stem slices.
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Affiliation(s)
- Matthew F. Ireland
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
| | - Gregory D. Funk
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Mark C. Bellingham
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia; and
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Zhang M, Abrams C, Wang L, Gizzi A, He L, Lin R, Chen Y, Loll PJ, Pascal JM, Zhang JF. Structural basis for calmodulin as a dynamic calcium sensor. Structure 2012; 20:911-23. [PMID: 22579256 DOI: 10.1016/j.str.2012.03.019] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 02/20/2012] [Accepted: 03/08/2012] [Indexed: 12/14/2022]
Abstract
Calmodulin is a prototypical and versatile Ca(2+) sensor with EF hands as its high-affinity Ca(2+) binding domains. Calmodulin is present in all eukaryotic cells, mediating Ca(2+)-dependent signaling. Upon binding Ca(2+), calmodulin changes its conformation to form complexes with a diverse array of target proteins. Despite a wealth of knowledge on calmodulin, little is known on how target proteins regulate calmodulin's ability to bind Ca(2+). Here, we take advantage of two splice variants of SK2 channels, which are activated by Ca(2+)-bound calmodulin but show different sensitivity to Ca(2+) for their activation. Protein crystal structures and other experiments show that, depending on which SK2 splice variant it binds to, calmodulin adopts drastically different conformations with different affinities for Ca(2+) at its C-lobe. Such target protein-induced conformational changes make calmodulin a dynamic Ca(2+) sensor capable of responding to different Ca(2+) concentrations in cellular Ca(2+) signaling.
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Affiliation(s)
- Miao Zhang
- Department of Molecular Physiology and Biophysics, Jefferson Medical College, Philadelphia, PA 19107, USA
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49
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Balut CM, Hamilton KL, Devor DC. Trafficking of intermediate (KCa3.1) and small (KCa2.x) conductance, Ca(2+)-activated K(+) channels: a novel target for medicinal chemistry efforts? ChemMedChem 2012; 7:1741-55. [PMID: 22887933 DOI: 10.1002/cmdc.201200226] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 07/09/2012] [Indexed: 12/22/2022]
Abstract
Ca(2+)-activated K(+) (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro-domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein-protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.
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Affiliation(s)
- Corina M Balut
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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50
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Kuiper EFE, Nelemans A, Luiten P, Nijholt I, Dolga A, Eisel U. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration. Front Pharmacol 2012; 3:107. [PMID: 22701424 PMCID: PMC3372087 DOI: 10.3389/fphar.2012.00107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/19/2012] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium (KCa) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of KCa channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of KCa channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) and the intermediate-conductance (KCa3.1) channel. These channels are activated by submicromolar intracellular Ca2+ concentrations and are voltage independent. Of all KCa channels only the KCa2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of KCa channel activation revealed new roles for KCa2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, KCa2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of KCa2 and KCa3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer’s disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and KCa channel activation.
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Affiliation(s)
- Els F E Kuiper
- Molecular Neurobiology, University of Groningen Groningen, Netherlands
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