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Monat J, Altieri LG, Enrique N, Sedán D, Andrinolo D, Milesi V, Martín P. Direct Inhibition of BK Channels by Cannabidiol, One of the Principal Therapeutic Cannabinoids Derived from Cannabis sativa. JOURNAL OF NATURAL PRODUCTS 2024; 87:1368-1375. [PMID: 38708937 DOI: 10.1021/acs.jnatprod.3c01274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Cannabidiol (CBD), one of the main Cannabis sativa bioactive compounds, is utilized in the treatment of major epileptic syndromes. Its efficacy can be attributed to a multimodal mechanism of action that includes, as potential targets, several types of ion channels. In the brain, CBD reduces the firing frequency in rat hippocampal neurons, partly prolonging the duration of action potentials, suggesting a potential blockade of voltage-operated K+ channels. We postulate that this effect might involve the inhibition of the large-conductance voltage- and Ca2+-operated K+ channel (BK channel), which plays a role in the neuronal action potential's repolarization. Thus, we assessed the impact of CBD on the BK channel activity, heterologously expressed in HEK293 cells. Our findings, using the patch-clamp technique, revealed that CBD inhibits BK channel currents in a concentration-dependent manner with an IC50 of 280 nM. The inhibition is through a direct interaction, reducing both the unitary conductance and voltage-dependent activation of the channel. Additionally, the cannabinoid significantly delays channel activation kinetics, indicating stabilization of the closed state. These effects could explain the changes induced by CBD in action potential shape and duration, and they may contribute to the observed anticonvulsant activity of this cannabinoid.
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Affiliation(s)
- Juliana Monat
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Lucía González Altieri
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Nicolás Enrique
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Daniela Sedán
- Centro de Investigaciones en Medioambiente (CIM), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard. 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Darío Andrinolo
- Centro de Investigaciones en Medioambiente (CIM), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard. 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Verónica Milesi
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
| | - Pedro Martín
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), Universidad Nacional de La Plata - CICPBA - CONICET, Boulevard 120 no. 1489, La Plata, CP 1900, Provincia de Buenos Aires, Argentina
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2
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Li G, Hu L, Gu X, Zhu W, Zhen X, Sun X. Targeting Large-Conductance Calcium-Activated Potassium Channels to Ameliorate Lipopolysaccharide-Induced Depressive-Like Behavior in Mice. Neurochem Res 2024; 49:1239-1253. [PMID: 38383879 DOI: 10.1007/s11064-024-04111-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/19/2024] [Accepted: 01/20/2024] [Indexed: 02/23/2024]
Abstract
Neuroinflammation plays crucial role in the development and progression of depression. Large conductance calcium- and voltage-dependent potassium (BK) channels mediate the activation of microglia. Herein, we investigated whether BK channels could serve as a target for the treatment of inflammation-associated depression. Lipopolysaccharide (LPS, 0.83 mg/kg) was injected intraperitoneally (i.p.) to induce neuroinflammation and depressive-like behavior in 6-8 week ICR mice. Adeno-associated virus (AAV) constructs (AAV9-Iba1p-BK shRNA-EGFP (BK shRNA-AAV) or AAV9-Iba1p-NC shRNA-EGFP (NC shRNA-AAV)) were unilaterally injected intracerebroventricularly to selectively knock down BK channels in microglia. The tail suspension test (TST) and forced-swim test (FST) were used to evaluate depressive-like behavior in mice 24 h after LPS challenge. The morphology of microglia, expression of BK channels, levels of cytokines, and expression and activity of indoleamine 2,3-dioxygenase (IDO) were measured by immunohistochemistry, western blot, quantitative real time PCR, and enzyme-linked immunosorbent assay (ELISA), respectively. Either paxilline (i.p.), a specific BK channel blocker, or BK shRNA-AAV effectively inhibited the activation of microglia, reduced the production of IL-1β in the hippocampus and suppressed the expression and activity of IDO in the hippocampus and prefrontal cortex, resulting in the amelioration of depressive-like behavior in mice. These data suggest for the first time that BK channels are involved in LPS-induced depressive-like behaviors. Thus, microglia BK channels may be a potential drug target for the depression treatment.
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Affiliation(s)
- Gangjing Li
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China
| | - Li Hu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China
| | - Xiangcheng Gu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China
| | - Weijun Zhu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China
| | - Xuechu Zhen
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China
| | - Xiaohui Sun
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, China.
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3
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Dai LT, Yang L, Guo JC, Ma QY, Xie QY, Jiang L, Yu ZF, Dai HF, Zhao YX. Anti-diabetic and anti-inflammatory indole diterpenes from the marine-derived fungus Penicillium sp. ZYX-Z-143. Bioorg Chem 2024; 145:107205. [PMID: 38387395 DOI: 10.1016/j.bioorg.2024.107205] [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: 12/18/2023] [Revised: 01/26/2024] [Accepted: 02/10/2024] [Indexed: 02/24/2024]
Abstract
Seven new indole-diterpenoids, penpaxilloids A-E (1-5), 7-methoxypaxilline-13-ene (6), and 10-hydroxy-paspaline (7), along with 20 known ones (8-27), were isolated from the marine-derived fungus Penicillium sp. ZYX-Z-143. Among them, compound 1 was a spiro indole-diterpenoid bearing a 2,3,3a,5-tetrahydro-1H-benzo[d]pyrrolo[2,1-b][1,3]oxazin-1-one motif. Compound 2 was characterized by a unique heptacyclic system featuring a rare 3,6,8-trioxabicyclo[3.2.1]octane unit. The structures of the new compounds were established by extensive spectroscopic analyses, NMR calculations coupled with the DP4 + analysis, and ECD calculations. The plausible biogenetic pathway of two unprecedented indole diterpenoids, penpaxilloids A and B (1 and 2), was postulated. Compound 1 acted as a noncompetitive inhibitor against protein tyrosine phosphatase 1B (PTP1B) with IC50 value of 8.60 ± 0.53 μM. Compound 17 showed significant α-glucosidase inhibitory activity with IC50 value of 19.96 ± 0.32 μM. Moreover, compounds 4, 8, and 22 potently suppressed nitric oxide production on lipopolysaccharide-stimulated RAW264.7 macrophages.
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Affiliation(s)
- Lu-Ting Dai
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China; College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Li Yang
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Jiao-Cen Guo
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Qing-Yun Ma
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Qing-Yi Xie
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Li Jiang
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhi-Fang Yu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
| | - Hao-Fu Dai
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - You-Xing Zhao
- Key Laboratory of Research and Development of Natural Product from Li Folk Medicine of Hainan Province & National Key Laboratory for Tropical Crop Breeding, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
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Van NTH, Kim WK, Nam JH. Challenges in the Therapeutic Targeting of KCa Channels: From Basic Physiology to Clinical Applications. Int J Mol Sci 2024; 25:2965. [PMID: 38474212 PMCID: PMC10932353 DOI: 10.3390/ijms25052965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 03/14/2024] Open
Abstract
Calcium-activated potassium (KCa) channels are ubiquitously expressed throughout the body and are able to regulate membrane potential and intracellular calcium concentrations, thereby playing key roles in cellular physiology and signal transmission. Consequently, it is unsurprising that KCa channels have been implicated in various diseases, making them potential targets for pharmaceutical interventions. Over the past two decades, numerous studies have been conducted to develop KCa channel-targeting drugs, including those for disorders of the central and peripheral nervous, cardiovascular, and urinary systems and for cancer. In this review, we synthesize recent findings regarding the structure and activating mechanisms of KCa channels. We also discuss the role of KCa channel modulators in therapeutic medicine. Finally, we identify the major reasons behind the delay in bringing these modulators to the pharmaceutical market and propose new strategies to promote their application.
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Affiliation(s)
- Nhung Thi Hong Van
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
- Department of Internal Medicine, Graduate School of Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
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5
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Meredith AL. BK Channelopathies and KCNMA1-Linked Disease Models. Annu Rev Physiol 2024; 86:277-300. [PMID: 37906945 DOI: 10.1146/annurev-physiol-030323-042845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Novel KCNMA1 variants, encoding the BK K+ channel, are associated with a debilitating dyskinesia and epilepsy syndrome. Neurodevelopmental delay, cognitive disability, and brain and structural malformations are also diagnosed at lower incidence. More than half of affected individuals present with a rare negative episodic motor disorder, paroxysmal nonkinesigenic dyskinesia (PNKD3). The mechanistic relationship of PNKD3 to epilepsy and the broader spectrum of KCNMA1-associated symptomology is unknown. This review summarizes patient-associated KCNMA1 variants within the BK channel structure, functional classifications, genotype-phenotype associations, disease models, and treatment. Patient and transgenic animal data suggest delineation of gain-of-function (GOF) and loss-of-function KCNMA1 neurogenetic disease, validating two heterozygous alleles encoding GOF BK channels (D434G and N999S) as causing seizure and PNKD3. This discovery led to a variant-defined therapeutic approach for PNKD3, providing initial insight into the neurological basis. A comprehensive clinical definition of monogenic KCNMA1-linked disease and the neuronal mechanisms currently remain priorities for continued investigation.
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Affiliation(s)
- Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA;
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Okhuarobo A, Kreifeldt M, Gandhi PJ, Lopez C, Martinez B, Fleck K, Bajo M, Bhattacharyya P, Dopico AM, Roberto M, Roberts AJ, Homanics GE, Contet C. Ethanol's interaction with BK channel α subunit residue K361 does not mediate behavioral responses to alcohol in mice. Mol Psychiatry 2024; 29:529-542. [PMID: 38135755 PMCID: PMC11116116 DOI: 10.1038/s41380-023-02346-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023]
Abstract
Large conductance potassium (BK) channels are among the most sensitive molecular targets of ethanol and genetic variations in the channel-forming α subunit have been nominally associated with alcohol use disorders. However, whether the action of ethanol at BK α influences the motivation to drink alcohol remains to be determined. To address this question, we first tested the effect of systemically administered BK channel modulators on voluntary alcohol consumption in C57BL/6J males. Penitrem A (blocker) exerted dose-dependent effects on moderate alcohol intake, while paxilline (blocker) and BMS-204352 (opener) were ineffective. Because pharmacological manipulations are inherently limited by non-specific effects, we then sought to investigate the behavioral relevance of ethanol's direct interaction with BK α by introducing in the mouse genome a point mutation known to render BK channels insensitive to ethanol while preserving their physiological function. The BK α K361N substitution prevented ethanol from reducing spike threshold in medial habenula neurons. However, it did not alter acute responses to ethanol in vivo, including ataxia, sedation, hypothermia, analgesia, and conditioned place preference. Furthermore, the mutation did not have reproducible effects on alcohol consumption in limited, continuous, or intermittent access home cage two-bottle choice paradigms conducted in both males and females. Notably, in contrast to previous observations made in mice missing BK channel auxiliary β subunits, the BK α K361N substitution had no significant impact on ethanol intake escalation induced by chronic intermittent alcohol vapor inhalation. It also did not affect the metabolic and locomotor consequences of chronic alcohol exposure. Altogether, these data suggest that the direct interaction of ethanol with BK α does not mediate the alcohol-related phenotypes examined here in mice.
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Affiliation(s)
- Agbonlahor Okhuarobo
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Max Kreifeldt
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Pauravi J Gandhi
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Catherine Lopez
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Briana Martinez
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Kiera Fleck
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Michal Bajo
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | | | - Alex M Dopico
- University of Tennessee Health Science Center, Department of Pharmacology, Addiction Science, and Toxicology, Memphis, TN, USA
| | - Marisa Roberto
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA
| | - Amanda J Roberts
- The Scripps Research Institute, Animals Models Core Facility, La Jolla, CA, USA
| | - Gregg E Homanics
- University of Pittsburgh, Department of Anesthesiology and Perioperative Medicine, Pittsburgh, PA, USA
| | - Candice Contet
- The Scripps Research Institute, Department of Molecular Medicine, La Jolla, CA, USA.
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Liu H, Qu D, Cao Y, Li H, Wu X, Zhu Y, Tao J, Li Y, Cao C. TAT-Modified Martentoxin Displays Intravenous Antiseizure Activities. ACS Chem Neurosci 2024; 15:205-214. [PMID: 38112732 DOI: 10.1021/acschemneuro.3c00744] [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] [Indexed: 12/21/2023] Open
Abstract
Epilepsy is a chronic disease of brain dysfunction, which arises from imbalance between excitatory and inhibitory activities in neural circuits. Previously, we reported that peptide Martentoxin (MarTX), from scorpion Buthus martensii Karsch, displayed antiseizure activities by specifically inhibiting BK(α + β4) channel currents. Injection of MarTX into the hippocampal region of mice significantly alleviated convulsive seizures. However, intravenous injection of MarTX had no antiepileptic efficacy due to the blood-brain barrier (BBB). To address this, here, we designed cell-penetrating peptide TAT-modified MarTX, in which the linker containing three glycines was put between TAT and the N-terminus of MarTX (forming MTX-N-TAT) or between TAT and the C-terminus of MarTX (forming MTX-C-TAT), respectively. We prepared them in a large amount through Escherichia coli overexpression system and then probed their antiseizure activities. Our results indicated that intravenous injection of MTX-C-TAT showed significant therapeutic efficacy of antiseizure. It increased seizure latency, reduced the total seizure duration and the number of seizures at stages 3, 4, and 5, inhibited hippocampal neuronal hyperexcitability, and exhibited neuroprotective effects on hippocampal neurons. These studies implied that MTX-C-TAT displayed intravenous antiseizure activities properly through crossing BBB and would be a potential antiepileptic drug in the future.
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Affiliation(s)
- Huan Liu
- School of pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
| | - Dongxiao Qu
- Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China
| | - Yunzhu Cao
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
- Nanjing Fenglin Biotechnology Co., 2 Taixi Road, Pukou District, Nanjing 210031, China
| | - Haiting Li
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
- Center for Supramolecular Chemistry and Catalysis, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Xiaoyu Wu
- Center for Supramolecular Chemistry and Catalysis, Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Yudan Zhu
- Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China
- School of Medicine and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Jie Tao
- Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China
| | - Yiming Li
- School of pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Chunyang Cao
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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Liu X, Tao J, Zhang S, Lan W, Yao Y, Wang C, Xue H, Ji Y, Li G, Cao C. Development of charybdotoxin Q18F variant as a selective peptide blocker of neuronal BK(α + β4) channel for the treatment of epileptic seizures. Protein Sci 2022; 31:e4506. [PMID: 36369672 PMCID: PMC9703589 DOI: 10.1002/pro.4506] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 11/04/2022] [Accepted: 11/06/2022] [Indexed: 11/14/2022]
Abstract
Epilepsy is the results from the imbalance between inhibition and excitation in neural circuits, which is mainly treated by some chemical drugs with side effects. Gain-of-function of BK channels or knockout of its β4 subunit associates with spontaneous epilepsy. Currently, few reports were published about the efficacy of BK(α + β4) channel modulators in epilepsy prevention. Charybdotoxin is a non-specific inhibitor of BK and other K+ channels. Here, by nuclear magnetic resonance (NMR) and other biochemical techniques, we found that charybdotoxin might interact with the extracellular loop of human β4 subunit (i.e., hβ4-loop) of BK(α + β4) channel at a molar ratio 4:1 (hβ4-loop vs. charybdotoxin). Charybdotoxin enhanced its ability to prevent K+ current of BK(α + β4 H101Y) channel. The charybdotoxin Q18F variant selectively reduced the neuronal spiking frequency and increased interspike intervals of BK(α + β4) channel by π-π stacking interactions between its residue Phe18 and residue His101 of hβ4-loop. Moreover, intrahippocampal infusion of charybdotoxin Q18F variant significantly increased latency time of seizure, reduced seizure duration and seizure numbers on pentylenetetrazole-induced pre-sensitized rats, inhibited hippocampal hyperexcitability and c-Fos expression, and displayed neuroprotective effects on hippocampal neurons. These results implied that charybdotoxin Q18F variant could be potentially used for intractable epilepsy treatment by therapeutically targeting BK(α + β4) channel.
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Affiliation(s)
- Xinlian Liu
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of ScienceBeijingChina
| | - Jie Tao
- Department of Neurology and Central Laboratory, Putuo HospitalShanghai University of Traditional Chinese MedicineShanghaiChina
- Institute of Biomembrane and BiopharmaceuticsShanghai UniversityShanghaiChina
| | - Shuzhang Zhang
- Institute of Biomembrane and BiopharmaceuticsShanghai UniversityShanghaiChina
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghaiChina
| | - Yu Yao
- Institute of Biomembrane and BiopharmaceuticsShanghai UniversityShanghaiChina
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghaiChina
| | - Hongjuan Xue
- National Facility for Protein Science in Shanghai, Zhangjiang LabShanghai Advanced Research Institute, Chinese Academy of SciencesShanghaiChina
| | - Yonghua Ji
- Institute of Biomembrane and BiopharmaceuticsShanghai UniversityShanghaiChina
| | - Guoyi Li
- Department of Neurology and Central Laboratory, Putuo HospitalShanghai University of Traditional Chinese MedicineShanghaiChina
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghaiChina
- University of Chinese Academy of ScienceBeijingChina
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9
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Park SM, Roache CE, Iffland PH, Moldenhauer HJ, Matychak KK, Plante AE, Lieberman AG, Crino PB, Meredith A. BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models. eLife 2022; 11:e77953. [PMID: 35819138 PMCID: PMC9275823 DOI: 10.7554/elife.77953] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 06/01/2022] [Indexed: 12/14/2022] Open
Abstract
KCNMA1 forms the pore of BK K+ channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous KCNMA1 variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of KCNMA1 mutations and the basis for clinical heterogeneity in PNKD3 has not been established. Here, we evaluate the relative severity of three KCNMA1 patient variants in BK channels, neurons, and mice. In heterologous cells, BKN999S and BKD434G channels displayed gain-of-function (GOF) properties, whereas BKH444Q channels showed loss-of-function (LOF) properties. The relative degree of channel activity was BKN999S > BKD434G>WT > BKH444Q. BK currents and action potential firing were increased, and seizure thresholds decreased, in Kcnma1N999S/WT and Kcnma1D434G/WT transgenic mice but not Kcnma1H444Q/WT mice. In a novel behavioral test for paroxysmal dyskinesia, the more severely affected Kcnma1N999S/WT mice became immobile after stress. This was abrogated by acute dextroamphetamine treatment, consistent with PNKD3-affected individuals. Homozygous Kcnma1D434G/D434G mice showed similar immobility, but in contrast, homozygous Kcnma1H444Q/H444Q mice displayed hyperkinetic behavior. These data establish the relative pathogenic potential of patient alleles as N999S>D434G>H444Q and validate Kcnma1N999S/WT mice as a model for PNKD3 with increased seizure propensity.
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Affiliation(s)
- Su Mi Park
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Cooper E Roache
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Philip H Iffland
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Hans J Moldenhauer
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Katia K Matychak
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Amber E Plante
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Abby G Lieberman
- Department of Pharmacology, University of Maryland School of MedicineBaltimoreUnited States
| | - Peter B Crino
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Andrea Meredith
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
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10
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Abstract
BK channelopathy has been increasingly implicated in diverse neurological disorders, including epilepsy and movement, cognitive, and neurodevelopmental disorders. However, precision medicine to treat BK channelopathy is lacking. We characterized a mouse model carrying a gain-of-function BK channelopathy D434G from a large family of patients with absence epilepsy and paroxysmal dyskinesia. The BK-D434G mice manifest the clinical features of absence seizures and exhibit severe locomotor defects including involuntary dyskinesia-like behavior. Pharmacological inhibition of BK channels suppresses neuronal hyperactivity and mitigates absence seizure and the locomotor defects. The BK-D434G mice thus serve as a model to understand the pathogenic mechanisms of absence epilepsy and dyskinesia. Our study also suggests that BK inhibition is a promising strategy for treating BK gain-of-function channelopathy. A growing number of gain-of-function (GOF) BK channelopathies have been identified in patients with epilepsy and movement disorders. Nevertheless, the underlying pathophysiology and corresponding therapeutics remain obscure. Here, we utilized a knock-in mouse model carrying human BK-D434G channelopathy to investigate the neuronal mechanism of BK GOF in the pathogenesis of epilepsy and dyskinesia. The BK-D434G mice manifest the clinical features of absence epilepsy and exhibit severe motor deficits and dyskinesia-like behaviors. The cortical pyramidal neurons and cerebellar Purkinje cells from the BK-D434G mice show hyperexcitability, which likely contributes to the pathogenesis of absence seizures and paroxysmal dyskinesia. A BK channel blocker, paxilline, potently suppresses BK-D434G–induced hyperexcitability and effectively mitigates absence seizures and locomotor deficits in mice. Our study thus uncovered a neuronal mechanism of BK GOF in absence epilepsy and dyskinesia. Our findings also suggest that BK inhibition is a promising therapeutic strategy for mitigating BK GOF-induced neurological disorders.
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11
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Xiao N, Xu Y, Zhang X, Li H, Zhang S, Xiao A, Yu J, Yang M, Lv F, Zhang M, Hao G, Chen G, Zhou L, Kong F, Pan G. Anti-Diabetic Indole-Terpenoids From Penicillium sp. HFF16 Isolated From the Rhizosphere Soil of Cynanchum bungei Decne. Front Chem 2022; 9:792810. [PMID: 35211458 PMCID: PMC8861352 DOI: 10.3389/fchem.2021.792810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/23/2021] [Indexed: 11/13/2022] Open
Abstract
Finding novel anti-diabetic compounds with effective suppression activities against hepatic glucagon response is urgently required for the development of new drugs against diabetes. Fungi are well known for their ability to produce new bioactive secondary metabolites. As part of our ongoing research, five new indole-terpenoids (1–5), named encindolenes D-H, were isolated from the fungus Penicillium sp. HFF16 from the rhizosphere soil of Cynanchum bungei Decne. The structures of the compounds were elucidated by spectroscopic data and ECD analysis. In the anti-diabetic activity assay, compounds 1–5 could inhibit the hepatic glucose production with EC50 values of 17.6, 30.1, 21.3, 9.6, and 9.9 μM, respectively, and decrease the cAMP contents in glucagon-induced HepG2 cells.
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Affiliation(s)
- Na Xiao
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agriculture University, Tai’an, China
| | - Yiru Xu
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Xinru Zhang
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Haonan Li
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Shengnan Zhang
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Ang Xiao
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Jinyi Yu
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Mingtian Yang
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Fujin Lv
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Mingyu Zhang
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Gangping Hao
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
| | - Guotong Chen
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, China
| | - Liman Zhou
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, China
| | - Fandong Kong
- Key Laboratory of Chemistry and Engineering of Forest Products, State Ethnic Affairs Commission, Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi Collaborative Innovation Center for Chemistry and Engineering of Forest Products, School of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning, China
- *Correspondence: Fandong Kong, ; Guojun Pan,
| | - Guojun Pan
- College of Life Sciences, Shandong First Medical University, Shandong Academy of Medical Sciences, Tai’an, China
- *Correspondence: Fandong Kong, ; Guojun Pan,
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12
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Miller JP, Moldenhauer HJ, Keros S, Meredith AL. An emerging spectrum of variants and clinical features in KCNMA1-linked channelopathy. Channels (Austin) 2021; 15:447-464. [PMID: 34224328 PMCID: PMC8259716 DOI: 10.1080/19336950.2021.1938852] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/18/2021] [Accepted: 06/01/2021] [Indexed: 12/13/2022] Open
Abstract
KCNMA1-linked channelopathy is an emerging neurological disorder characterized by heterogeneous and overlapping combinations of movement disorder, seizure, developmental delay, and intellectual disability. KCNMA1 encodes the BK K+ channel, which contributes to both excitatory and inhibitory neuronal and muscle activity. Understanding the basis of the disorder is an important area of active investigation; however, the rare prevalence has hampered the development of large patient cohorts necessary to establish genotype-phenotype correlations. In this review, we summarize 37 KCNMA1 alleles from 69 patients currently defining the channelopathy and assess key diagnostic and clinical hallmarks. At present, 3 variants are classified as gain-of-function with respect to BK channel activity, 14 loss-of-function, 15 variants of uncertain significance, and putative benign/VUS. Symptoms associated with these variants were curated from patient-provided information and prior publications to define the spectrum of clinical phenotypes. In this newly expanded cohort, seizures showed no differential distribution between patients harboring GOF and LOF variants, while movement disorders segregated by mutation type. Paroxysmal non-kinesigenic dyskinesia was predominantly observed among patients with GOF alleles of the BK channel, although not exclusively so, while additional movement disorders were observed in patients with LOF variants. Neurodevelopmental and structural brain abnormalities were prevalent in patients with LOF mutations. In contrast to mutations, disease-associated KCNMA1 single nucleotide polymorphisms were not predominantly related to neurological phenotypes but covered a wider set of peripheral physiological functions. Together, this review provides additional evidence exploring the genetic and biochemical basis for KCNMA1-linked channelopathy and summarizes the clinical repository of patient symptoms across multiple types of KCNMA1 gene variants.
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Affiliation(s)
- Jacob P. Miller
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hans J. Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sotirios Keros
- Department of Pediatrics, Weill Cornell Medical College, New York, NY, USA
| | - Andrea L. Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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13
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Valipour M, Naderi N, Heidarli E, Shaki F, Motafeghi F, Talebpour Amiri F, Emami S, Irannejad H. Design, synthesis and biological evaluation of naphthalene-derived (arylalkyl)azoles containing heterocyclic linkers as new anticonvulsants: A comprehensive in silico, in vitro, and in vivo study. Eur J Pharm Sci 2021; 166:105974. [PMID: 34390829 DOI: 10.1016/j.ejps.2021.105974] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/10/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
In continuation of our research to find strong and safe anticonvulsant agents, a number of (arylalkyl)azoles (AAAs) containing naphthylthiazole and naphthyloxazole scaffolds were designed and synthesized. The in vivo anticonvulsant evaluations in BALB/c mice revealed that some of them had significant anticonvulsant activity in both maximal electroshock (MES) and pentylenetetrazole (PTZ) models of epilepsy. The best profile of activity was observed with compounds containing imidazole and triazole rings (C1, C6, G1, and G6). In particular, imidazolylmethyl-thiazole C1 with median effective dose (ED50)= 7.9 mg/kg in the MES test, ED50= 27.9 mg/kg in PTZ test, and without any sign of neurotoxicity (in the rotarod test, 100 mg/kg) was the most promising compound. The patch-clamp recording was performed to study the mechanism of action of the representative compound C1 on hippocampal dentate gyrus (DG) cells. The results did not confirm any modulatory effect of C1 on the voltage-gated ion channels (VGICs) or GABAA agonism, but suggested a significant reduction of excitatory postsynaptic currents (EPSCs) frequency on hippocampal DG neurons. Sub-acute toxicity studies revealed that administration of the most active compounds (C1, C6, G1, and G6) at 100 mg/kg bw/day for two weeks did not result in any mortality or significant toxicity as evaluated by assessment of biochemical markers such as lipid peroxidation, intracellular glutathione, total antioxidant capacity, histopathological changes, and mitochondrial functions. Other pharmacological aspects of compounds including mechanistic and ADME properties were investigated computationally and/or experimentally. Molecular docking on the NMDA and AMPA targets suggested that the introduction of the heterocyclic ring in the middle of AAAs significantly affects the affinity of the compounds. The obtained results totally demonstrated that the prototype compound C1 can be considered as a new lead for the development of anticonvulsant agents.
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Affiliation(s)
- Mehdi Valipour
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Nima Naderi
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neuroscience Research Center, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Elmira Heidarli
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Shaki
- Department of Toxicology and Pharmacology, Mazandaran University of Medical Sciences, Sari, Iran
| | - Farzaneh Motafeghi
- Department of Toxicology and Pharmacology, Mazandaran University of Medical Sciences, Sari, Iran
| | - Fereshteh Talebpour Amiri
- Department of Anatomy, Faculty of Medicine, Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Saeed Emami
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran; Pharmaceutical Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
| | - Hamid Irannejad
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran; Pharmaceutical Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
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14
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Copping NA, McTighe SM, Fink KD, Silverman JL. Emerging Gene and Small Molecule Therapies for the Neurodevelopmental Disorder Angelman Syndrome. Neurotherapeutics 2021; 18:1535-1547. [PMID: 34528170 PMCID: PMC8608975 DOI: 10.1007/s13311-021-01082-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2021] [Indexed: 02/07/2023] Open
Abstract
Angelman syndrome (AS) is a rare (~1:15,000) neurodevelopmental disorder characterized by severe developmental delay and intellectual disability, impaired communication skills, and a high prevalence of seizures, sleep disturbances, ataxia, motor deficits, and microcephaly. AS is caused by loss-of-function of the maternally inherited UBE3A gene. UBE3A is located on chromosome 15q11-13 and is biallelically expressed throughout the body but only maternally expressed in the brain due to an RNA antisense transcript that silences the paternal copy. There is currently no cure for AS, but advancements in small molecule drugs and gene therapies offer a promising approach for the treatment of the disorder. Here, we review AS and how loss-of-function of the maternal UBE3A contributes to the disorder. We also discuss the strengths and limitations of current animal models of AS. Furthermore, we examine potential small molecule drug and gene therapies for the treatment of AS and associated challenges faced by the therapeutic design. Finally, gene therapy offers the opportunity for precision medicine in AS and advancements in the treatment of this disorder can serve as a foundation for other single-gene neurodevelopmental disorders.
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Affiliation(s)
- Nycole A Copping
- School of Medicine, Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Research II Building 96, 4625 2nd Avenue, Suite 1001B, Davis, Sacramento, CA, 95817, USA
- Stem Cell Program and Gene Therapy Center, Department of Neurology, MIND Institute, University of California, Davis, Sacramento, CA, USA
| | | | - Kyle D Fink
- Stem Cell Program and Gene Therapy Center, Department of Neurology, MIND Institute, University of California, Davis, Sacramento, CA, USA
| | - Jill L Silverman
- School of Medicine, Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Research II Building 96, 4625 2nd Avenue, Suite 1001B, Davis, Sacramento, CA, 95817, USA.
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15
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Hunsberger MS, Mynlieff M. BK potassium currents contribute differently to action potential waveform and firing rate as rat hippocampal neurons mature in the first postnatal week. J Neurophysiol 2020; 124:703-714. [DOI: 10.1152/jn.00711.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
This work describes the early developmental trends of large-conductance calcium-activated potassium (BK) channel activity. Early developmental trends in expression of BK channels, both total expression and relative isoform expression, have been previously reported, but little work describes the effect of these changes in expression patterns on excitability. Here, we show that early changes in BK channel expression patterns lead to changes in the role of BK channels in determining the action potential waveform and neuronal excitability.
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Affiliation(s)
| | - Michelle Mynlieff
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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16
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Liu X, Tao J, Zhang S, Lan W, Wang C, Ji Y, Cao C. Selective Blockade of Neuronal BK (α + β4) Channels Preventing Epileptic Seizure. J Med Chem 2019; 63:216-230. [DOI: 10.1021/acs.jmedchem.9b01241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Xinlian Liu
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- University of Chinese Academy of Science, No. 19A, Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Jie Tao
- Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, 164 Lanxi Road, Putuo District, Shanghai 200062, China
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, 99 Shangda Road,
BaoShan District, Shanghai 200444, China
| | - Shuzhang Zhang
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, 99 Shangda Road,
BaoShan District, Shanghai 200444, China
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Yonghua Ji
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, 99 Shangda Road,
BaoShan District, Shanghai 200444, China
- Xinhua Hospital (Chongming) Affiliated to Shanghai JiaoTong University School of Medicine, Shanghai Chongming Xinhua Translational Medical Institute for Cancer Pain, 25 Nanmen Port Street, Chongming Branch, Shanghai 202150, China
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Product Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- University of Chinese Academy of Science, No. 19A, Yuquan Road, Shijingshan District, Beijing 100049, China
- Institute of Drug Discovery Technology, Ningbo University, No 818 Fenghua Road, Ningbo, Zhejiang 313211, China
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17
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Bailey CS, Moldenhauer HJ, Park SM, Keros S, Meredith AL. KCNMA1-linked channelopathy. J Gen Physiol 2019; 151:1173-1189. [PMID: 31427379 PMCID: PMC6785733 DOI: 10.1085/jgp.201912457] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 08/13/2019] [Indexed: 12/20/2022] Open
Abstract
Bailey et al. review a new neurological channelopathy associated with KCNMA1, encoding the BK voltage- and Ca2+-activated K+ channel. KCNMA1 encodes the pore-forming α subunit of the “Big K+” (BK) large conductance calcium and voltage-activated K+ channel. BK channels are widely distributed across tissues, including both excitable and nonexcitable cells. Expression levels are highest in brain and muscle, where BK channels are critical regulators of neuronal excitability and muscle contractility. A global deletion in mouse (KCNMA1−/−) is viable but exhibits pathophysiology in many organ systems. Yet despite the important roles in animal models, the consequences of dysfunctional BK channels in humans are not well characterized. Here, we summarize 16 rare KCNMA1 mutations identified in 37 patients dating back to 2005, with an array of clinically defined pathological phenotypes collectively referred to as “KCNMA1-linked channelopathy.” These mutations encompass gain-of-function (GOF) and loss-of-function (LOF) alterations in BK channel activity, as well as several variants of unknown significance (VUS). Human KCNMA1 mutations are primarily associated with neurological conditions, including seizures, movement disorders, developmental delay, and intellectual disability. Due to the recent identification of additional patients, the spectrum of symptoms associated with KCNMA1 mutations has expanded but remains primarily defined by brain and muscle dysfunction. Emerging evidence suggests the functional BK channel alterations produced by different KCNMA1 alleles may associate with semi-distinct patient symptoms, such as paroxysmal nonkinesigenic dyskinesia (PNKD) with GOF and ataxia with LOF. However, due to the de novo origins for the majority of KCNMA1 mutations identified to date and the phenotypic variability exhibited by patients, additional evidence is required to establish causality in most cases. The symptomatic picture developing from patients with KCNMA1-linked channelopathy highlights the importance of better understanding the roles BK channels play in regulating cell excitability. Establishing causality between KCNMA1-linked BK channel dysfunction and specific patient symptoms may reveal new treatment approaches with the potential to increase therapeutic efficacy over current standard regimens.
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Affiliation(s)
- Cole S Bailey
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Hans J Moldenhauer
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Su Mi Park
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Sotirios Keros
- Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, SD
| | - Andrea L Meredith
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
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18
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Ariantari NP, Ancheeva E, Wang C, Mándi A, Knedel TO, Kurtán T, Chaidir C, Müller WEG, Kassack MU, Janiak C, Daletos G, Proksch P. Indole Diterpenoids from an Endophytic Penicillium sp. JOURNAL OF NATURAL PRODUCTS 2019; 82:1412-1423. [PMID: 31117519 DOI: 10.1021/acs.jnatprod.8b00723] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A chemical investigation of the endophyte Penicillium sp. (strain ZO-R1-1), isolated from roots of the medicinal plant Zingiber officinale, yielded nine new indole diterpenoids (1-9), together with 13 known congeners (10-22). The structures of the new compounds were elucidated by 1D and 2D NMR analysis in combination with HRESIMS data. The absolute configuration of the new natural products 1, 3, and 7 was determined using the TDDFT-ECD approach and confirmed for 1 by single-crystal X-ray determination through anomalous dispersion. The isolated compounds were tested for cytotoxicity against L5178Y, A2780, J82, and HEK-293 cell lines. Compound 1 was the most active metabolite toward L5178Y cells, with an IC50 value of 3.6 μM, and an IC50 against A2780 cells of 8.7 μM. Interestingly, 1 features a new type of indole diterpenoid scaffold with a rare 6/5/6/6/6/6/5 heterocyclic system bearing an aromatic ring C, which is suggested to be important for the cytotoxic activity of this natural product against L5278Y and A2780 cells.
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Affiliation(s)
- Ni P Ariantari
- Institute of Pharmaceutical Biology and Biotechnology , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
- Department of Pharmacy, Faculty of Mathematic and Natural Sciences , Udayana University , 80361 Bali , Indonesia
| | - Elena Ancheeva
- Institute of Pharmaceutical Biology and Biotechnology , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
| | - Chenyin Wang
- Institute of Pharmaceutical and Medicinal Chemistry , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
| | - Attila Mándi
- Department of Organic Chemistry , University of Debrecen , P.O.B. 400, 4002 Debrecen , Hungary
| | - Tim-O Knedel
- Institute of Inorganic Chemistry and Structural Chemistry , Heinrich Heine University Düsseldorf , Universitätsstraße 1 , 40225 Düsseldorf , Germany
| | - Tibor Kurtán
- Department of Organic Chemistry , University of Debrecen , P.O.B. 400, 4002 Debrecen , Hungary
| | - Chaidir Chaidir
- Center for Pharmaceutical and Medical Technology , Agency for the Assessment and Application Technology , 10340 Jakarta , Indonesia
| | - Werner E G Müller
- Institute of Physiological Chemistry , Universitätsmedizin der Johannes Gutenberg-Universität Mainz , Duesbergweg 6 , 55128 Mainz , Germany
| | - Matthias U Kassack
- Institute of Pharmaceutical and Medicinal Chemistry , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
| | - Christoph Janiak
- Institute of Inorganic Chemistry and Structural Chemistry , Heinrich Heine University Düsseldorf , Universitätsstraße 1 , 40225 Düsseldorf , Germany
| | - Georgios Daletos
- Institute of Pharmaceutical Biology and Biotechnology , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
| | - Peter Proksch
- Institute of Pharmaceutical Biology and Biotechnology , Heinrich Heine University Düsseldorf , Universitätsstrasse 1 , 40225 Düsseldorf , Germany
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19
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Kong FD, Fan P, Zhou LM, Ma QY, Xie QY, Zheng HZ, Zheng ZH, Zhang RS, Yuan JZ, Dai HF, Luo DQ, Zhao YX. Penerpenes A–D, Four Indole Terpenoids with Potent Protein Tyrosine Phosphatase Inhibitory Activity from the Marine-Derived Fungus Penicillium sp. KFD28. Org Lett 2019; 21:4864-4867. [DOI: 10.1021/acs.orglett.9b01751] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fan-Dong Kong
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
| | - Peng Fan
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002, China
| | - Li-Man Zhou
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002, China
| | - Qing-Yun Ma
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
| | - Qing-Yi Xie
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
| | - Hai-Zhou Zheng
- New Drug Research and Development Center, North China Pharmaceutical Group Corporation, Shijiazhuang 050015, China
| | - Zhi-Hui Zheng
- New Drug Research and Development Center, North China Pharmaceutical Group Corporation, Shijiazhuang 050015, China
| | - Ren-Shuai Zhang
- Qingdao Cancer Institute, the Affiliated Hospital of Qingdao University, Qingdao 266061, China
| | - Jing-Zhe Yuan
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
| | - Hao-Fu Dai
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
| | - Du-Qiang Luo
- College of Life Science, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, Hebei University, Baoding 071002, China
| | - You-Xing Zhao
- Research and Development of Natural Product from Li Folk Medicine, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China
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20
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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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21
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Large-conductance Ca 2+-activated potassium channels are potently involved in the inverse neurovascular response to spreading depolarization. Neurobiol Dis 2018; 119:41-52. [PMID: 30053571 DOI: 10.1016/j.nbd.2018.07.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/03/2018] [Accepted: 07/23/2018] [Indexed: 12/21/2022] Open
Abstract
Recurrent spreading depolarizations occur in the cerebral cortex from minutes up to weeks following acute brain injury. Clinical evidence suggests that the immediate reduction of cerebral blood flow in response to spreading depolarization importantly contributes to lesion progression as the wave propagates over vulnerable tissue zones, characterized by potassium concentration already elevated prior to the passage of spreading depolarization. Here we demonstrate with two-photon microscopy in anesthetized mice that initial vasoconstriction in response to SD triggered experimentally with 1 M KCl is coincident in space and time with the large extracellular accumulation of potassium, as shown with a potassium indicator fluorescent dye. Moreover, pharmacological manipulations in combination with the use of potassium-sensitive microelectrodes suggest that large-conductance Ca2+-activated potassium (BK) channels and L-type voltage-gated calcium channels play significant roles in the marked initial vasoconstriction under elevated baseline potassium. We propose that potassium efflux through BK channels is a central component in the devastating neurovascular effects of spreading depolarizations in tissue at risk.
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22
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Peng J, Pang N, Wang Y, Wang XL, Chen J, Xiong J, Peng P, Zhu CH, Kessi MB, He F, Yin F. Next-generation sequencing improves treatment efficacy and reduces hospitalization in children with drug-resistant epilepsy. CNS Neurosci Ther 2018; 25:14-20. [PMID: 29933521 DOI: 10.1111/cns.12869] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 03/30/2018] [Accepted: 04/03/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The purposes of this study were three-fold: (i) to determine the contribution of known genes to the causation of a broad-spectrum of pediatric drug-resistant epilepsy (DRE), (ii) to compare the diagnostic yield and cost among different next-generation sequencing (NGS) approaches, and especially (iii) to assess how NGS approaches can benefit patients by improving diagnosis and treatment efficiency. METHODS This study enrolled 273 pediatric DRE patients with no obvious acquired etiology. Seventy-four patients underwent whole-exome sequencing (WES), 141 patients had epilepsy-related gene panel testing, and another 58 patients had clinical WES gene panel testing. We obtained these patients' seizure and hospitalization frequency by periodic follow-up phone calls and outpatient visits. RESULTS Genetic diagnosis was achieved in 86 patients (31.5%) and involved 93 likely disease-causing mutations in 33 genes. In this study, the detection rates of the epilepsy-related gene panel, the clinical WES gene panel, and WES were 32.6% (46/141), 44.8% (26/58), and 17.3% (13/74), respectively. Moreover, 34 patients accepted corrective therapy according to their mutant genes, after which 52.9% (18/34) became seizure-free and 38.2% (13/34) achieved seizure reduction. In the end, patients with either positive or negative genetic results had significantly fewer hospitalization incidents (times/half year) than before (positive genetic results group 0.58 ± 1.14 vs 0.10 ± 0.26; negative genetic results group 0.72 ± 1.65 vs 0.12 ± 0.33). CONCLUSIONS These results offer further proof that NGS approaches represent powerful tools for establishing a definitive diagnosis. Moreover, this study indicated how NGS can improve treatment efficacy and reduce hospitalization in children with DRE.
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Affiliation(s)
- Jing Peng
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Nan Pang
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Ying Wang
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiao-Le Wang
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Jian Chen
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Juan Xiong
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Pan Peng
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Can-Hui Zhu
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Miriam Barakael Kessi
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Fang He
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Fei Yin
- Department of Pediatric Neurology, Xiangya Hospital, Central South University, Changsha, China
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23
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Li X, Poschmann S, Chen Q, Fazeli W, Oundjian NJ, Snoeijen-Schouwenaars FM, Fricke O, Kamsteeg EJ, Willemsen M, Wang QK. De novo BK channel variant causes epilepsy by affecting voltage gating but not Ca 2+ sensitivity. Eur J Hum Genet 2018; 26:220-229. [PMID: 29330545 PMCID: PMC5839055 DOI: 10.1038/s41431-017-0073-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 11/06/2017] [Accepted: 11/23/2017] [Indexed: 12/30/2022] Open
Abstract
Epilepsy is one of the most common neurological diseases and it causes profound morbidity and mortality. We identified the first de novo variant in KCNMA1 (c.2984 A > G (p.(N995S)))-encoding the BK channel-that causes epilepsy, but not paroxysmal dyskinesia, in two independent families. The c.2984 A > G (p.(N995S)) variant markedly increased the macroscopic potassium current by increasing both the channel open probability and channel open dwell time. The c.2984 A > G (p.(N995S)) variant did not affect the calcium sensitivity of the channel. We also identified three other variants of unknown significance (c.1554 G > T (p.(K518N)), c.1967A > C (p.(E656A)), and c.3476 A > G (p.(N1159S))) in three separate patients with divergent epileptic phenotypes. However, these variants did not affect the BK potassium current, and are therefore unlikely to be disease-causing. These results demonstrate that BK channel variants can cause epilepsy without paroxysmal dyskinesia. The underlying molecular mechanism can be increased activation of the BK channel by increased sensitivity to the voltage-dependent activation without affecting the sensitivity to the calcium-dependent activation. Our data suggest that the BK channel may represent a drug target for the treatment of epilepsy. Our data highlight the importance of functional electrophysiological studies of BK channel variants in distinguishing whether a genomic variant of unknown significance is a disease-causing variant or a benign variant.
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Affiliation(s)
- Xia Li
- Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei Province, P. R. China
| | | | - Qiuyun Chen
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Department of Cardiovascular Medicine, Cleveland Clinic, OH, USA
- Department of Genetics and Genome Science, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Walid Fazeli
- University Children's Hospital Cologne, Pediatric Neurology, Cologne, Germany
| | | | | | - Oliver Fricke
- Department of Child and Adolescent Psychiatry and Neuropediatrics, Gemeinschaftskrankenhaus Herdecke, Witten/Herdecke, Germany
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, HB Nijmegen, The Netherlands
| | - Marjolein Willemsen
- Department of Human Genetics, Radboud University Medical Center, HB Nijmegen, The Netherlands.
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands.
| | - Qing Kenneth Wang
- Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei Province, P. R. China.
- Center for Cardiovascular Genetics, Department of Molecular Cardiology, Lerner Research Institute, Department of Cardiovascular Medicine, Cleveland Clinic, OH, USA.
- Department of Genetics and Genome Science, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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24
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Song T, Liang S, Liu J, Zhang T, Yin Y, Geng C, Gao S, Feng Y, Xu H, Guo D, Roberts A, Gu Y, Cang Y. CRL4 antagonizes SCFFbxo7-mediated turnover of cereblon and BK channel to regulate learning and memory. PLoS Genet 2018; 14:e1007165. [PMID: 29370161 PMCID: PMC5800687 DOI: 10.1371/journal.pgen.1007165] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 02/06/2018] [Accepted: 12/25/2017] [Indexed: 12/18/2022] Open
Abstract
Intellectual disability (ID), one of the most common human developmental disorders, can be caused by genetic mutations in Cullin 4B (Cul4B) and cereblon (CRBN). CRBN is a substrate receptor for the Cul4A/B-DDB1 ubiquitin ligase (CRL4) and can target voltage- and calcium-activated BK channel for ER retention. Here we report that ID-associated CRL4CRBN mutations abolish the interaction of the BK channel with CRL4, and redirect the BK channel to the SCFFbxo7 ubiquitin ligase for proteasomal degradation. Glioma cell lines harbouring CRBN mutations record density-dependent decrease of BK currents, which can be restored by blocking Cullin ubiquitin ligase activity. Importantly, mice with neuron-specific deletion of DDB1 or CRBN express reduced BK protein levels in the brain, and exhibit similar impairment in learning and memory, a deficit that can be partially rescued by activating the BK channel. Our results reveal a competitive targeting of the BK channel by two ubiquitin ligases to achieve exquisite control of its stability, and support changes in neuronal excitability as a common pathogenic mechanism underlying CRL4CRBN-associated ID.
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Affiliation(s)
- Tianyu Song
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shenghui Liang
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
| | - Jiye Liu
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tingyue Zhang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yifei Yin
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chenlu Geng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shaobing Gao
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yan Feng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hao Xu
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Dongqing Guo
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Amanda Roberts
- Molecular and Cellular Neurosciences Department, The Scripps Research Institute, University of California, San Diego, La Jolla, California, United States of America
| | - Yuchun Gu
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
- * E-mail: (YC); (YG)
| | - Yong Cang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail: (YC); (YG)
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25
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Whitmire LE, Ling L, Bugay V, Carver CM, Timilsina S, Chuang HH, Jaffe DB, Shapiro MS, Cavazos JE, Brenner R. Downregulation of KCNMB4 expression and changes in BK channel subtype in hippocampal granule neurons following seizure activity. PLoS One 2017; 12:e0188064. [PMID: 29145442 PMCID: PMC5690595 DOI: 10.1371/journal.pone.0188064] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 10/31/2017] [Indexed: 11/25/2022] Open
Abstract
A major challenge is to understand maladaptive changes in ion channels that sets neurons on a course towards epilepsy development. Voltage- and calcium-activated K+ (BK) channels contribute to early spike timing in neurons, and studies indicate that the BK channel plays a pathological role in increasing excitability early after a seizure. Here, we have investigated changes in BK channels and their accessory β4 subunit (KCNMB4) in dentate gyrus (DG) granule neurons of the hippocampus, key neurons that regulate excitability of the hippocampus circuit. Two days after pilocarpine-induced seizures, we found that the predominant effect is a downregulation of the β4 accessory subunit mRNA. Consistent with reduced expression, single channel recording and pharmacology indicate a switch in the subtype of channels expressed; from iberiotoxin-resistant, type II BK channels (BK α/β4) that have higher channel open probability and slow gating, to iberiotoxin-sensitive type I channels (BK α alone) with low open probability and faster gating. The switch to a majority of type I channel expression following seizure activity is correlated with a loss of BK channel function on spike threshold while maintaining the channel’s contribution to increased early spike frequency. Using heterozygous β4 knockout mice, we find reduced expression is sufficient to increase seizure sensitivity. We conclude that seizure-induced downregulation of KCNMB4 is an activity dependent mechanism that increases the excitability of DG neurons. These novel findings indicate that BK channel subtypes are not only defined by cell-specific expression, but can also be plastic depending on the recent history of neuronal excitability.
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Affiliation(s)
- Luke E. Whitmire
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Ling Ling
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Vladslav Bugay
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Chase M. Carver
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Santosh Timilsina
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Hui-Hsiu Chuang
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - David B. Jaffe
- Department of Biology, University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Mark S. Shapiro
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Jose E. Cavazos
- Neurology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Robert Brenner
- Department of Cell and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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26
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A novel BK channel-targeted peptide suppresses sound evoked activity in the mouse inferior colliculus. Sci Rep 2017; 7:42433. [PMID: 28195225 PMCID: PMC5307958 DOI: 10.1038/srep42433] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/10/2017] [Indexed: 02/06/2023] Open
Abstract
Large conductance calcium-activated (BK) channels are broadly expressed in neurons and muscle where they modulate cellular activity. Decades of research support an interest in pharmaceutical applications for modulating BK channel function. Here we report a novel BK channel-targeted peptide with functional activity in vitro and in vivo. This 9-amino acid peptide, LS3, has a unique action, suppressing channel gating rather than blocking the pore of heterologously expressed human BK channels. With an IC50 in the high picomolar range, the apparent affinity is higher than known high affinity BK channel toxins. LS3 suppresses locomotor activity via a BK channel-specific mechanism in wild-type or BK channel-humanized Caenorhabditis elegans. Topical application on the dural surface of the auditory midbrain in mouse suppresses sound evoked neural activity, similar to a well-characterized pore blocker of the BK channel. Moreover, this novel ion channel-targeted peptide rapidly crosses the BBB after systemic delivery to modulate auditory processing. Thus, a potent BK channel peptide modulator is open to neurological applications, such as preventing audiogenic seizures that originate in the auditory midbrain.
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27
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Hayashi Y, Morinaga S, Zhang J, Satoh Y, Meredith AL, Nakata T, Wu Z, Kohsaka S, Inoue K, Nakanishi H. BK channels in microglia are required for morphine-induced hyperalgesia. Nat Commun 2016; 7:11697. [PMID: 27241733 PMCID: PMC4895018 DOI: 10.1038/ncomms11697] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 04/20/2016] [Indexed: 02/01/2023] Open
Abstract
Although morphine is a gold standard medication, long-term opioid use is associated with serious side effects, such as morphine-induced hyperalgesia (MIH) and anti-nociceptive tolerance. Microglia-to-neuron signalling is critically involved in pain hypersensitivity. However, molecules that control microglial cellular state under chronic morphine treatment remain unknown. Here we show that the microglia-specific subtype of Ca2+-activated K+ (BK) channel is responsible for generation of MIH and anti-nociceptive tolerance. We find that, after chronic morphine administration, an increase in arachidonic acid levels through the μ-opioid receptors leads to the sole activation of microglial BK channels in the spinal cord. Silencing BK channel auxiliary β3 subunit significantly attenuates the generation of MIH and anti-nociceptive tolerance, and increases neurotransmission after chronic morphine administration. Therefore, microglia-specific BK channels contribute to the generation of MIH and anti-nociceptive tolerance. Long-term use of opioids can lead to a paradoxical increase in pain sensitivity. Here, Hayashi et al. link activation of potassium channels on microglia with morphine-induced hyperalgesia and anti-nociceptive tolerance in mice.
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Affiliation(s)
- Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Saori Morinaga
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Jing Zhang
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yasushi Satoh
- Department of Anesthesiology, National Defense Medical College, Tokorozawa 359-8513, Japan
| | - Andrea L Meredith
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Takahiro Nakata
- Department of Molecular and Cellular Anatomy, Faculty of Health Promotional Sciences, Tokoha University, Hamamatsu, Shizuoka 431-2102, Japan
| | - Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Shinichi Kohsaka
- Department of Neurochemistry, National Institute of Neuroscience, Kodaira, Tokyo 187-8502, Japan
| | - Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1, Otemachi, Chiyoda-ku, Tokyo 100-004, Japan
| | - Hiroshi Nakanishi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka 812-8582, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, 1-7-1, Otemachi, Chiyoda-ku, Tokyo 100-004, Japan
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28
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Griguoli M, Sgritta M, Cherubini E. Presynaptic BK channels control transmitter release: physiological relevance and potential therapeutic implications. J Physiol 2016; 594:3489-500. [PMID: 26969302 DOI: 10.1113/jp271841] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/02/2016] [Indexed: 12/14/2022] Open
Abstract
BK channels are large conductance potassium channels characterized by four pore-forming α subunits, often co-assembled with auxiliary β and γ subunits to regulate Ca(2+) sensitivity, voltage dependence and gating properties. Abundantly expressed in the CNS, they have the peculiar characteristic of being activated by both voltage and intracellular calcium rise. The increase in intracellular calcium via voltage-dependent calcium channels (Cav ) during spiking triggers conformational changes and BK channel opening. This narrows the action potential and induces a fast after-hyperpolarization that shuts calcium channels. The tight coupling between BK and Cav channels at presynaptic active zones makes them particularly suitable for regulating calcium entry and neurotransmitter release. While in most synapses, BK channels exert a negative control on transmitter release under basal conditions, in others they do so only under pathological conditions, serving as an emergency brake to protect against hyperactivity. In particular cases, by interacting with other channels (i.e. limiting the activation of the delayed rectifier and the inactivation of Na(+) channels), BK channels induce spike shortening, increase in firing rate and transmitter release. Changes in transmitter release following BK channel dysfunction have been implicated in several neurological disorders including epilepsy, schizophrenia, fragile X syndrome, mental retardation and autism. In particular, two mutations, one in the α and one in the β3 subunit, resulting in a gain of function have been associated with epilepsy. Hence, these discoveries have allowed identification of BK channels as new drug targets for therapeutic intervention.
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Affiliation(s)
- Marilena Griguoli
- European Brain Research Institute (EBRI) 'Fondazione Rita Levi-Montalcini', Via del Fosso di Fiorano 64, 00143, Rome, Italy
| | - Martina Sgritta
- European Brain Research Institute (EBRI) 'Fondazione Rita Levi-Montalcini', Via del Fosso di Fiorano 64, 00143, Rome, Italy
| | - Enrico Cherubini
- European Brain Research Institute (EBRI) 'Fondazione Rita Levi-Montalcini', Via del Fosso di Fiorano 64, 00143, Rome, Italy.,International School for Advanced Studies (SISSA), Trieste, Italy
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29
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Abstract
Large conductance Ca(2+)- and voltage-activated K(+) (BK) channels are widely distributed in the postnatal central nervous system (CNS). BK channels play a pleiotropic role in regulating the activity of brain and spinal cord neural circuits by providing a negative feedback mechanism for local increases in intracellular Ca(2+) concentrations. In neurons, they regulate the timing and duration of K(+) influx such that they can either increase or decrease firing depending on the cellular context, and they can suppress neurotransmitter release from presynaptic terminals. In addition, BK channels located in astrocytes and arterial myocytes modulate cerebral blood flow. Not surprisingly, both loss and gain of BK channel function have been associated with CNS disorders such as epilepsy, ataxia, mental retardation, and chronic pain. On the other hand, the neuroprotective role played by BK channels in a number of pathological situations could potentially be leveraged to correct neurological dysfunction.
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30
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Abstract
An enantioselective synthesis of the indole diterpenoid natural product paspaline is disclosed. Critical to this approach was the implementation of stereoselective desymmetrization reactions to assemble key stereocenters of the molecule. The design and execution of these tactics are described in detail, and a thorough analysis of observed outcomes is presented, ultimately providing the title compound in high stereopurity. This synthesis provides a novel template for preparing key stereocenters in this family of molecules, and the reactions developed en route to paspaline present a series of new synthetic disconnections in preparing steroidal natural products.
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Affiliation(s)
- Robert J. Sharpe
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jeffrey S. Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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31
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Morera FJ, Saravia J, Pontigo JP, Vargas-Chacoff L, Contreras GF, Pupo A, Lorenzo Y, Castillo K, Tilegenova C, Cuello LG, Gonzalez C. Voltage-dependent BK and Hv1 channels expressed in non-excitable tissues: New therapeutics opportunities as targets in human diseases. Pharmacol Res 2015; 101:56-64. [PMID: 26305431 DOI: 10.1016/j.phrs.2015.08.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/14/2015] [Accepted: 08/14/2015] [Indexed: 11/28/2022]
Abstract
Voltage-gated ion channels are the molecular determinants of cellular excitability. This group of ion channels is one of the most important pharmacological targets in excitable tissues such as nervous system, cardiac and skeletal muscle. Moreover, voltage-gated ion channels are expressed in non-excitable cells, where they mediate key cellular functions through intracellular biochemical mechanisms rather than rapid electrical signaling. This review aims at illustrating the pharmacological impact of these ion channels, highlighting in particular the structural details and physiological functions of two of them - the high conductance voltage- and Ca(2+)-gated K(+) (BK) channels and voltage-gated proton (Hv1) channels- in non-excitable cells. BK channels have been implicated in a variety of physiological processes ranging from regulation of smooth muscle tone to modulation of hormone and neurotransmitter release. Interestingly, BK channels are also involved in modulating K(+) transport in the mammalian kidney and colon epithelium with a potential role in the hyperkalemic phenotype observed in patients with familial hyperkalemic hypertension type 2, and in the pathophysiology of hypertension. In addition, BK channels are responsible for resting and stimulated Ca(2+)-activated K(+) secretion in the distal colon. Hv1 channels have been detected in many cell types, including macrophages, blood cells, lung epithelia, skeletal muscle and microglia. These channels have a central role in the phagocytic system. In macrophages, Hv1 channels participate in the generation of reactive oxygen species in the respiratory burst during the process of phagocytosis.
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Affiliation(s)
- Francisco J Morera
- Institute of Pharmacology and Morphophysiology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile.
| | - Julia Saravia
- Institute of Pharmacology and Morphophysiology, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Juan Pablo Pontigo
- Institute of Marine Sciences and Limnology, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Luis Vargas-Chacoff
- Institute of Marine Sciences and Limnology, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Gustavo F Contreras
- Interdisciplinary Center for Neuroscience of Valparaiso, Faculty of Sciences, Universidad de Valparaiso, Valparaiso, Chile
| | - Amaury Pupo
- Interdisciplinary Center for Neuroscience of Valparaiso, Faculty of Sciences, Universidad de Valparaiso, Valparaiso, Chile
| | - Yenisleidy Lorenzo
- Interdisciplinary Center for Neuroscience of Valparaiso, Faculty of Sciences, Universidad de Valparaiso, Valparaiso, Chile
| | - Karen Castillo
- Interdisciplinary Center for Neuroscience of Valparaiso, Faculty of Sciences, Universidad de Valparaiso, Valparaiso, Chile
| | - Cholpon Tilegenova
- Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubcock, TX, USA
| | - Luis G Cuello
- Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubcock, TX, USA.
| | - Carlos Gonzalez
- Interdisciplinary Center for Neuroscience of Valparaiso, Faculty of Sciences, Universidad de Valparaiso, Valparaiso, Chile.
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32
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Leo A, Citraro R, Constanti A, De Sarro G, Russo E. Are big potassium-type Ca2+-activated potassium channels a viable target for the treatment of epilepsy? Expert Opin Ther Targets 2015; 19:911-26. [DOI: 10.1517/14728222.2015.1026258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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33
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Brenner R. Knockout of the BK β2 subunit reveals the importance of accessorizing your channel. ACTA ACUST UNITED AC 2014; 144:351-6. [PMID: 25311634 PMCID: PMC4210423 DOI: 10.1085/jgp.201411291] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Robert Brenner
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78230
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Bentzen BH, Olesen SP, Rønn LCB, Grunnet M. BK channel activators and their therapeutic perspectives. Front Physiol 2014; 5:389. [PMID: 25346695 PMCID: PMC4191079 DOI: 10.3389/fphys.2014.00389] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/19/2014] [Indexed: 01/05/2023] Open
Abstract
The large conductance calcium- and voltage-activated K+ channel (KCa1.1, BK, MaxiK) is ubiquitously expressed in the body, and holds the ability to integrate changes in intracellular calcium and membrane potential. This makes the BK channel an important negative feedback system linking increases in intracellular calcium to outward hyperpolarizing potassium currents. Consequently, the channel has many important physiological roles including regulation of smooth muscle tone, neurotransmitter release and neuronal excitability. Additionally, cardioprotective roles have been revealed in recent years. After a short introduction to the structure, function and regulation of BK channels, we review the small organic molecules activating BK channels and how these tool compounds have helped delineate the roles of BK channels in health and disease.
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Affiliation(s)
- Bo H Bentzen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark ; Acesion Pharma Copenhagen, Denmark
| | - Søren-Peter Olesen
- Department of Biomedical Sciences, Faculty of Health Sciences, Danish Arrhythmia Research Centre, University of Copenhagen Copenhagen, Denmark
| | | | - Morten Grunnet
- Acesion Pharma Copenhagen, Denmark ; H. Lundbeck A/S Copenhagen, Denmark
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Wang B, Jaffe DB, Brenner R. Current understanding of iberiotoxin-resistant BK channels in the nervous system. Front Physiol 2014; 5:382. [PMID: 25346692 PMCID: PMC4190997 DOI: 10.3389/fphys.2014.00382] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 09/15/2014] [Indexed: 11/13/2022] Open
Abstract
While most large-conductance, calcium-, and voltage-activated potassium channels (BK or Maxi-K type) are blocked by the scorpion venom iberiotoxin, the so-called “type II” subtype has the property of toxin resistance. This property is uniquely mediated by channel assembly with one member of the BK accessory β subunit family, the neuron-enriched β4 subunit. This review will focus on current understanding of iberiotoxin-resistant, β4-containing BK channel properties and their function in the CNS. Studies have shown that β4 dramatically promotes BK channel opening by shifting voltage sensor activation to more negative voltage ranges, but also slows activation to timescales that theoretically preclude BK ability to shape action potentials (APs). In addition, β4 membrane trafficking is regulated through an endoplasmic retention signal and palmitoylation. More recently, the challenge has been to understand the functional role of the iberiotoxin-resistant BK subtype utilizing computational modeling of neurons and neurophysiological approaches. Utilizing iberiotoxin-resistance as a footprint for these channels, they have been identified in dentate gyrus granule neurons and in purkinje neurons of the cerebellum. In these neurons, the role of these channels is largely consistent with slow-gated channels that reduce excitability either through an interspike conductance, such as in purkinje neurons, or by replacing fast-gating BK channels that otherwise facilitate high frequency AP firing, such as in dentate gyrus neurons. They are also observed in presynaptic mossy fiber terminals of the dentate gyrus and posterior pituitary terminals. More recent studies suggest that β4 subunits may also be expressed in some neurons lacking iberiotoxin-resistant BK channels, such as in CA3 hippocampus neurons. Ongoing research using novel, specific blockers and agonists of BK/β4, and β4 knockout mice, will continue to move the field forward in understanding the function of these channels.
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Affiliation(s)
- Bin Wang
- Department of Physiology, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - David B Jaffe
- Department of Biology and the UTSA Neurosciences Institute, University of Texas at San Antonio San Antonio, TX, USA
| | - Robert Brenner
- Department of Physiology, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
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N'Gouemo P. BKCa channel dysfunction in neurological diseases. Front Physiol 2014; 5:373. [PMID: 25324781 PMCID: PMC4179377 DOI: 10.3389/fphys.2014.00373] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/10/2014] [Indexed: 12/22/2022] Open
Abstract
The large conductance, Ca2+-activated K+ channels (BKCa, KCa1.1) are expressed in various brain neurons where they play important roles in regulating action potential duration, firing frequency and neurotransmitter release. Membrane potential depolarization and rising levels of intracellular Ca2+ gated BKCa channels, which in turn results in an outward K+ flux that re/hyperpolarizes the membrane. The sensitivity of BKCa channels to Ca2+ provides an important negative-feedback system for Ca2+ entry into brain neurons and suppresses repetitive firing. Thus, BKCa channel loss-of-function gives rise to neuronal hyperexcitability, which can lead to seizures. Evidence also indicates that BKCa channels can facilitate high-frequency firing (gain-of-function) in some brain neurons. Interestingly, both gain-of-function and loss-of-function mutations of genes encoding for various BKCa channel subunits have been associated with the development of neuronal excitability disorders, such as seizure disorders. The role of BKCa channels in the etiology of some neurological diseases raises the possibility that these channels can be used as molecular targets to prevent and suppress disease phenotypes.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics and Interdisciplinary Program in Neuroscience, Georgetown University Medical Center Washington, DC, USA
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N’Gouemo P, Morad M. Alcohol withdrawal is associated with a downregulation of large-conductance Ca²⁺-activated K⁺ channels in rat inferior colliculus neurons. Psychopharmacology (Berl) 2014; 231:2009-18. [PMID: 24241791 PMCID: PMC3988246 DOI: 10.1007/s00213-013-3346-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Large conductance calcium-activated potassium (BK(Ca) or K(Ca)1.1) channels are well-known molecular targets for the action of alcohol and therefore may play an important role in the pathogenesis of alcohol withdrawal syndrome. OBJECTIVES We evaluate the modifications of total outward K⁺ currents and protein expression of BK(Ca) channels α-subunit in inferior colliculus (IC) neurons obtained from controls and rats subjected to alcohol withdrawal associated with enhanced susceptibility to seizures. METHODS Outward K⁺ currents and BK(Ca) channel proteins were measured using the whole cell configuration of patch clamp techniques and Western blot analysis, respectively. RESULTS Total outward K⁺ current density was significantly reduced in IC neurons at 24 and 48 h during the alcohol withdrawal period when the susceptibility to seizures was maximal and absent, respectively. The iberiotoxin-sensitive (BK(Ca)) current density and conductance also were significantly reduced at 24 h following alcohol withdrawal. Consistent with functional data, the levels of protein expression of α-subunit associated with BK(Ca) channels also was significantly reduced in IC neurons at 24 and 48 h following alcohol withdrawal. CONCLUSIONS The downregulation of BK(Ca) channels outlasts the finite period of elevated susceptibility to alcohol withdrawal seizures. These findings indicate that BK(Ca) channels, per se, may not be fundamentally important for the generation of alcohol withdrawal seizures.
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Affiliation(s)
- Prosper N’Gouemo
- Department of Pediatrics, Georgetown University Medical Center
,Address correspondence to: Department of Pediatrics, Georgetown University Medical Center, 3900 Reservoir Rd, NW, Washington, DC 20057, TEL: +1-202-687-8464; FAX: +202-444-7161,
| | - Martin Morad
- Department of Pharmacology, Georgetown University Medical Center
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Ghezzi A, Krishnan HR, Atkinson NS. Susceptibility to ethanol withdrawal seizures is produced by BK channel gene expression. Addict Biol 2014; 19:332-7. [PMID: 22734584 DOI: 10.1111/j.1369-1600.2012.00465.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Alcohol withdrawal seizures are part of the symptomatology of severe alcohol dependence and are believed to originate from long-term neural adaptations that counter the central nervous system depressant effects of alcohol. Upon alcohol withdrawal, however, the increased neural excitability that was adaptive in the presence of alcohol becomes counter-adaptive and produces an imbalanced hyperactive nervous system. For some individuals, the uncovering of this imbalance by alcohol abstention can be sufficient to generate a seizure. Using the Drosophila model organism, we demonstrate a central role for the BK-type Ca(2+) -activated K(+) channel gene slo in the production of alcohol withdrawal seizures.
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Affiliation(s)
- Alfredo Ghezzi
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research; The University of Texas at Austin; Austin TX USA
| | - Harish R. Krishnan
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research; The University of Texas at Austin; Austin TX USA
| | - Nigel S. Atkinson
- Section of Neurobiology and Waggoner Center for Alcohol and Addiction Research; The University of Texas at Austin; Austin TX USA
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Wang Z, Fan Y, Xu J, Li L, Heng D, Han S, Yin J, Peng B, Liu W, He X. Transcriptome analysis of the hippocampus in novel rat model of febrile seizures. PLoS One 2014; 9:e95237. [PMID: 24736375 PMCID: PMC3988142 DOI: 10.1371/journal.pone.0095237] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 03/24/2014] [Indexed: 01/12/2023] Open
Abstract
Febrile seizures (FS) are the most common type of convulsive events in infants and young children, but the precise underlying genetic mechanism remains to be explored. To investigate the underlying pathogenic factors in FS and subsequent epilepsy, alterations in gene expression between the two new strains of rats (hyperthermia-prone [HP] vs hyperthermia-resistant [HR]), were investigated by using the Whole Rat Genome Oligo Microarray. This process identified 1,140 differentially expressed genes (DEGs; 602 upregulated and 538 downregulated), which were analyzed to determine significant Gene Ontology (GO) categories, signaling pathways and gene networks. Based on the GO analyses, the modified genes are closely related to various FS pathogenesis factors, including immune and inflammatory responses and ion transport. Certain DEGs identified have not been previously examined in relation to FS pathogenesis. Among these genes is dipeptidyl peptidase 4 (DPP4), a gene closely linked to interleukin 6 (IL-6), which played a key role in the gene network analysis. Furthermore, sitagliptin, a DPP4 inhibitor significantly decreased epileptic discharge in rats, observed via electroencephalogram, suggesting an important role for DPP4 in FS. The effectiveness of sitagliptin in reducing seizure activity may occur through a mechanism that stabilizes cellular Ca2+ homeostasis. In addition, DPP4 expression may be regulated by DNA methylation. The hippocampal gene expression profiles in novel rat models of FS provides a large database of candidate genes and pathways, which will be useful for researchers interested in disorders of neuronal excitability.
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Affiliation(s)
- Zhongcheng Wang
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Yuanteng Fan
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Jian Xu
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Liang Li
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Duanhe Heng
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Song Han
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Jun Yin
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Biwen Peng
- Hubei Provincial Key Laboratory of Developmentally Originated Disease, School of Basic Medical Sciences, Wuhan University, Wuhan, China
| | - Wanhong Liu
- Hubei Province Key Laboratory of Allergy and Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- * E-mail: (WL); (XH)
| | - Xiaohua He
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China
- * E-mail: (WL); (XH)
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40
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How is homeostatic plasticity important in epilepsy? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:123-31. [PMID: 25012372 DOI: 10.1007/978-94-017-8914-1_10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Maintaining physiological variables within narrow operating limits by homeostatic mechanisms is a fundamental property of most if not all living cells and organisms. In recent years, research from many laboratories has shown that the activity of neurons and neural circuits are also homeostatically regulated. Here, we attempt to apply concepts of homeostasis in general, and more specifically synaptic homeostatic plasticity, to the study of epilepsy. We hypothesize that homeostatic mechanisms are actively engaged in the epileptic brain. These processes attempt to re-establish normal neuronal and network activity, but are opposed by the concurrent mechanisms underlying epileptogenesis. In forms of intractable epilepsy, seizures are so frequent and intense that homeostatic mechanisms are unable to restore normal levels of neuronal activity. In such cases, we contend that homeostatic plasticity mechanisms nevertheless remain active. However, their continuing attempts to reset neuronal activity become maladaptive and results in dyshomeostasis with neurobehavioral consequences. Using the developing hippocampus as a model system, we briefly review experimental results and present a series of arguments to propose that the cognitive neurobehavioral comorbidities of childhood epilepsy result, at least in part, from unchecked homeostatic mechanisms.
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41
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Sallam AA, Houssen WE, Gissendanner CR, Orabi KY, Foudah AI, El Sayed KA. Bioguided discovery and pharmacophore modeling of the mycotoxic indole diterpene alkaloids penitrems as breast cancer proliferation, migration, and invasion inhibitors. MEDCHEMCOMM 2013; 4:10.1039/C3MD00198A. [PMID: 24273638 PMCID: PMC3835464 DOI: 10.1039/c3md00198a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Marine-derived fungi have proven to be important sources of bioactive natural organohalides. The genus Penicillium is recognized as a rich source of chemically diverse bioactive secondary metabolites. This study reports the fermentation, isolation and identification of a marine-derived Penicillium species. Bioassay-guided fractionation afforded the indole diterpene alkaloids penitrems A, B, D, E and F as well as paspaline and emnidole SB (1-7). Supplementing the fermentation broth of the growing fungus with KBr afforded the new 6-bromopenitrem B (8) and the known 6-bromopenitrem E (9). These compounds showed good antiproliferative, antimigratory and anti-invasive properties against human breast cancer cells. Penitrem B also showed a good activity profile in the NCI-60 DTP human tumor cell line screen. The nematode Caenorhabditis elegans was used to assess the BK channel inhibitory activity and toxicity of select compounds. A pharmacophore model was generated to explain the structural relationships of 1-9 with respect to their antiproliferative activity against the breast cancer MCF-7 cells. The structurally less complex biosynthetic precursors, paspaline (6) and emindole SB (7), were identified as potential hits suitable for future studies.
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Affiliation(s)
- Asmaa A. Sallam
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana 71201 USA
| | - Wael E. Houssen
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Aberdeen, AB24 3UE Scotland, UK
- Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland, UK
| | - Chris R. Gissendanner
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana 71201 USA
| | - Khaled Y. Orabi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Health Sciences Center, Kuwait University, Safat 13110, Kuwait
| | - Ahmed I. Foudah
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana 71201 USA
| | - Khalid A. El Sayed
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of Louisiana at Monroe, Monroe, Louisiana 71201 USA
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42
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D'Adamo MC, Catacuzzeno L, Di Giovanni G, Franciolini F, Pessia M. K(+) channelepsy: progress in the neurobiology of potassium channels and epilepsy. Front Cell Neurosci 2013; 7:134. [PMID: 24062639 PMCID: PMC3772396 DOI: 10.3389/fncel.2013.00134] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/06/2013] [Indexed: 12/19/2022] Open
Abstract
K(+) channels are important determinants of seizure susceptibility. These membrane proteins, encoded by more than 70 genes, make the largest group of ion channels that fine-tune the electrical activity of neuronal and non-neuronal cells in the brain. Their ubiquity and extremely high genetic and functional diversity, unmatched by any other ion channel type, place K(+) channels as primary targets of genetic variations or perturbations in K(+)-dependent homeostasis, even in the absence of a primary channel defect. It is therefore not surprising that numerous inherited or acquired K(+) channels dysfunctions have been associated with several neurologic syndromes, including epilepsy, which often generate confusion in the classification of the associated diseases. Therefore, we propose to name the K(+) channels defects underlying distinct epilepsies as "K(+) channelepsies," and introduce a new nomenclature (e.g., Kx.y-channelepsy), following the widely used K(+) channel classification, which could be also adopted to easily identify other channelopathies involving Na(+) (e.g., Nav x.y-phenotype), Ca(2+) (e.g., Cav x.y-phenotype), and Cl(-) channels. Furthermore, we discuss novel genetic defects in K(+) channels and associated proteins that underlie distinct epileptic phenotypes in humans, and analyze critically the recent progress in the neurobiology of this disease that has also been provided by investigations on valuable animal models of epilepsy. The abundant and varied lines of evidence discussed here strongly foster assessments for variations in genes encoding for K(+) channels and associated proteins in patients with idiopathic epilepsy, provide new avenues for future investigations, and highlight these proteins as critical pharmacological targets.
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Key Words
- Potassium channels: [Kv1, Kv2, Kv3, Kv4, Kv8, Kv11(HERG), KCa1.1, Kvβ1, Kvβ2, KChIP LGI1, Kir1-Kir7 (GIRK, KATP)]
- autism–epilepsy
- channelopathies
- temporal lobe epilepsy
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Affiliation(s)
- Maria Cristina D'Adamo
- Faculty of Medicine, Section of Human Physiology, Department of Internal Medicine, University of Perugia Perugia, Italy ; Istituto Euro Mediterraneo di Scienza e Tecnologia, IEMEST Palermo, Italy
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43
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Ghotbedin Z, Janahmadi M, Mirnajafi-Zadeh J, Behzadi G, Semnanian S. Electrical Low Frequency Stimulation of the Kindling Site Preserves the Electrophysiological Properties of the Rat Hippocampal CA1 Pyramidal Neurons From the Destructive Effects of Amygdala Kindling: The Basis for a Possible Promising Epilepsy Therapy. Brain Stimul 2013; 6:515-23. [DOI: 10.1016/j.brs.2012.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 09/29/2012] [Accepted: 11/07/2012] [Indexed: 11/28/2022] Open
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The role of potassium BK channels in anticonvulsant effect of cannabidiol in pentylenetetrazole and maximal electroshock models of seizure in mice. Epilepsy Behav 2013; 28:1-7. [PMID: 23644464 DOI: 10.1016/j.yebeh.2013.03.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/02/2013] [Accepted: 03/08/2013] [Indexed: 11/22/2022]
Abstract
Cannabidiol is a nonpsychoactive member of phytocannabinoids that produces various pharmacological effects that are not mediated through putative CB1/CB2 cannabinoid receptors and their related effectors. In this study, we examined the effect of the i.c.v. administration of potassium BK channel blocker paxilline alone and in combination with cannabidiol in protection against pentylenetetrazol (PTZ)- and maximal electroshock (MES)-induced seizure in mice. In the PTZ-induced seizure model, i.c.v. administration of cannabidiol caused a significant increase in seizure threshold compared with the control group. Moreover, while i.c.v. administration of various doses of paxilline did not produce significant change in the PTZ-induced seizure threshold in mice, coadministration of cannabidiol and paxilline attenuated the antiseizure effect of cannabidiol in PTZ-induced tonic seizures. In the MES model of seizure, both cannabidiol and paxilline per se produced significant increase in percent protection against electroshock-induced seizure. However, coadministration of cannabidiol and paxilline did not produce significant interaction in their antiseizure effect in the MES test. The results of the present study showed a protective effect of cannabidiol in both PTZ and MES models of seizure. These results suggested a BK channel-mediated antiseizure action of cannabidiol in PTZ model of seizure. However, such an interaction might not exist in MES-induced convulsion.
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45
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Genetic activation of BK currents in vivo generates bidirectional effects on neuronal excitability. Proc Natl Acad Sci U S A 2012; 109:18997-9002. [PMID: 23112153 DOI: 10.1073/pnas.1205573109] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Large-conductance calcium-activated potassium channels (BK) are potent negative regulators of excitability in neurons and muscle, and increasing BK current is a novel therapeutic strategy for neuro- and cardioprotection, disorders of smooth muscle hyperactivity, and several psychiatric diseases. However, in some neurons, enhanced BK current is linked with seizures and paradoxical increases in excitability, potentially complicating the clinical use of agonists. The mechanisms that switch BK influence from inhibitory to excitatory are not well defined. Here we investigate this dichotomy using a gain-of-function subunit (BK(R207Q)) to enhance BK currents. Heterologous expression of BK(R207Q) generated currents that activated at physiologically relevant voltages in lower intracellular Ca(2+), activated faster, and deactivated slower than wild-type currents. We then used BK(R207Q) expression to broadly augment endogenous BK currents in vivo, generating a transgenic mouse from a circadian clock-controlled Period1 gene fragment (Tg-BK(R207Q)). The specific impact on excitability was assessed in neurons of the suprachiasmatic nucleus (SCN) in the hypothalamus, a cell type where BK currents regulate spontaneous firing under distinct day and night conditions that are defined by different complements of ionic currents. In the SCN, Tg-BK(R207Q) expression converted the endogenous BK current to fast-activating, while maintaining similar current-voltage properties between day and night. Alteration of BK currents in Tg-BK(R207Q) SCN neurons increased firing at night but decreased firing during the day, demonstrating that BK currents generate bidirectional effects on neuronal firing under distinct conditions.
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46
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Ye H, Buttigieg J, Wan Y, Wang J, Figley S, Fehlings MG. Expression and functional role of BK channels in chronically injured spinal cord white matter. Neurobiol Dis 2012; 47:225-36. [DOI: 10.1016/j.nbd.2012.04.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 03/22/2012] [Accepted: 04/08/2012] [Indexed: 11/30/2022] Open
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47
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Shruti S, Urban-Ciecko J, Fitzpatrick JA, Brenner R, Bruchez MP, Barth AL. The brain-specific Beta4 subunit downregulates BK channel cell surface expression. PLoS One 2012; 7:e33429. [PMID: 22438928 PMCID: PMC3306404 DOI: 10.1371/journal.pone.0033429] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/12/2012] [Indexed: 01/12/2023] Open
Abstract
The large-conductance K+ channel (BK channel) can control neural excitability, and enhanced channel currents facilitate high firing rates in cortical neurons. The brain-specific auxiliary subunit β4 alters channel Ca++- and voltage-sensitivity, and β4 knock-out animals exhibit spontaneous seizures. Here we investigate β4's effect on BK channel trafficking to the plasma membrane. Using a novel genetic tag to track the cellular location of the pore-forming BKα subunit in living cells, we find that β4 expression profoundly reduces surface localization of BK channels via a C-terminal ER retention sequence. In hippocampal CA3 neurons from C57BL/6 mice with endogenously high β4 expression, whole-cell BK channel currents display none of the characteristic properties of BKα+β4 channels observed in heterologous cells. Finally, β4 knock-out animals exhibit a 2.5-fold increase in whole-cell BK channel current, indicating that β4 also regulates current magnitude in vivo. Thus, we propose that a major function of the brain-specific β4 subunit in CA3 neurons is control of surface trafficking.
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Affiliation(s)
- Sonal Shruti
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Joanna Urban-Ciecko
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - James A. Fitzpatrick
- Molecular and Biosensor Imaging Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Robert Brenner
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Marcel P. Bruchez
- Molecular and Biosensor Imaging Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (ALB); (MPB)
| | - Alison L. Barth
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (ALB); (MPB)
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Rank C, Klejnstrup ML, Petersen LM, Kildgaard S, Frisvad JC, Held Gotfredsen C, Ostenfeld Larsen T. Comparative Chemistry of Aspergillus oryzae (RIB40) and A. flavus (NRRL 3357). Metabolites 2012; 2:39-56. [PMID: 24957367 PMCID: PMC3901201 DOI: 10.3390/metabo2010039] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 12/14/2011] [Accepted: 12/22/2011] [Indexed: 12/29/2022] Open
Abstract
Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus.
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Affiliation(s)
- Christian Rank
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Marie Louise Klejnstrup
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Lene Maj Petersen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Sara Kildgaard
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Jens Christian Frisvad
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
| | - Charlotte Held Gotfredsen
- Department of Chemistry, Technical University of Denmark, Kemitorvet B201, DK-2800 Kgs. Lyngby, Denmark.
| | - Thomas Ostenfeld Larsen
- Department of Systems Biology, Center for Microbial Biotechnology, Technical University of Denmark, Søltofts Plads B221, DK-2800 Kgs. Lyngby, Denmark.
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Abstract
INTRODUCTION Epilepsies are disorders of neuronal excitability characterized by spontaneous and recurrent seizures. Ion channels are critical for regulating neuronal excitability and, therefore, can contribute significantly to epilepsy pathophysiology. In particular, large conductance, Ca2+-activated K+ (BKCa) channels play an important role in seizure etiology. These channels are activated by both membrane depolarization and increased intracellular Ca2+. This unique coupling of Ca2+ signaling to membrane depolarization is important in controlling neuronal hyperexcitability, as outward K+ current through BKCa channels hyperpolarizes neurons. AREAS COVERED BKCa channel structure-function and the role of these channels in epilepsy pathophysiology. EXPERT OPINION Loss-of-function BKCa channel mutations contribute to neuronal hyperexcitability that can lead to temporal lobe epilepsy, tonic-clonic seizures and alcohol withdrawal seizures. Similarly, BKCa channel blockade can trigger seizures and status epilepticus. Paradoxically, some mutations in BKCa channel subunit can give rise to channel gain-of-function that leads to development of idiopathic epilepsy (primarily absence epilepsy). Seizures themselves also enhance BKCa channel currents associated with neuronal hyperexcitability, and blocking BKCa channels suppresses generalized tonic-clonic seizures. Thus, both loss-of-function and gain-of-function BKCa channels might serve as molecular targets for drugs to suppress certain seizure phenotypes including temporal lobe seizures and absence seizures, respectively.
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Affiliation(s)
- Prosper N'Gouemo
- Georgetown University Medical Center, Interdisciplinary Program in Neuroscience and Department of Pediatrics, Washington, DC 20057, USA.
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Cortical up state activity is enhanced after seizures: a quantitative analysis. J Clin Neurophysiol 2011; 27:425-32. [PMID: 21127407 DOI: 10.1097/wnp.0b013e3181fdf8bd] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In the neocortex, neurons participate in epochs of elevated activity, or Up states, during periods of quiescent wakefulness, slow-wave sleep, and general anesthesia. The regulation of firing during and between Up states is of great interest because it can reflect the underlying connectivity and excitability of neurons within the network. Automated analysis of the onset and characteristics of Up state firing across different experiments and conditions requires a robust and accurate method for Up state detection. Using measurements of membrane potential mean and variance calculated from whole-cell recordings of neurons from control and postseizure tissue, the authors have developed such a method. This quantitative and automated method is independent of cell- or condition-dependent variability in underlying noise or tonic firing activity. Using this approach, the authors show that Up state frequency and firing rates are significantly increased in layer 2/3 neocortical neurons 24 hours after chemoconvulsant-induced seizure. Down states in postseizure tissue show greater membrane-potential variance characterized by increased synaptic activity. Previously, the authors have found that postseizure increase in excitability is linked to a gain-of-function in BK channels, and blocking BK channels in vitro and in vivo can decrease excitability and eliminate seizures. Thus, the authors also assessed the effect of BK-channel antagonists on Up state properties in control and postseizure neurons. These data establish a robust and broadly applicable algorithm for Up state detection and analysis, provide a quantitative description of how prior seizures increase spontaneous firing activity in cortical networks, and show how BK-channel antagonists reduce this abnormal activity.
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