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Page DA, Ruben PC. Cannabidiol potentiates hyperpolarization-activated cyclic nucleotide-gated (HCN4) channels. J Gen Physiol 2024; 156:e202313505. [PMID: 38652080 PMCID: PMC11040500 DOI: 10.1085/jgp.202313505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 03/15/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024] Open
Abstract
Cannabidiol (CBD), the main non-psychotropic phytocannabinoid produced by the Cannabis sativa plant, blocks a variety of cardiac ion channels. We aimed to identify whether CBD regulated the cardiac pacemaker channel or the hyperpolarization-activated cyclic nucleotide-gated channel (HCN4). HCN4 channels are important for the generation of the action potential in the sinoatrial node of the heart and increased heart rate in response to β-adrenergic stimulation. HCN4 channels were expressed in HEK 293T cells, and the effect of CBD application was examined using a whole-cell patch clamp. We found that CBD depolarized the V1/2 of activation in holo-HCN4 channels, with an EC50 of 1.6 µM, without changing the current density. CBD also sped activation kinetics by approximately threefold. CBD potentiation of HCN4 channels occurred via binding to the closed state of the channel. We found that CBD's mechanism of action was distinct from cAMP, as CBD also potentiated apo-HCN4 channels. The addition of an exogenous PIP2 analog did not alter the ability of CBD to potentiate HCN4 channels, suggesting that CBD also acts using a unique mechanism from the known HCN4 potentiator PIP2. Lastly, to gain insight into CBD's mechanism of action, computational modeling and targeted mutagenesis were used to predict that CBD binds to a lipid-binding pocket at the C-terminus of the voltage sensor. CBD represents the first FDA-approved drug to potentiate HCN4 channels, and our findings suggest a novel starting point for drug development targeting HCN4 channels.
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Affiliation(s)
- Dana A. Page
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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2
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Ozturk H, Basoglu H, Yorulmaz N, Aydin-Abidin S, Abidin I. Fisetin decreases the duration of ictal-like discharges in mouse hippocampal slices. J Biol Phys 2022; 48:355-368. [PMID: 35948819 PMCID: PMC9411310 DOI: 10.1007/s10867-022-09612-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/27/2022] [Indexed: 11/24/2022] Open
Abstract
There is an increasing interest in the biological and therapeutic effects of fisetin, a natural phenolic compound. Fisetin has affinity on some neuronal targets and may have the potential to modulate neuronal activity. In this study the effects of acute application of fisetin on synchronized events were evaluated electro-physiologically. Besides, interaction of fisetin with closely related channels were investigated in silico. Acute horizontal hippocampal slices were obtained from 32- to 36-day-old C57BL/6 mice. Extracellular field potentials were recorded from CA3 region of the hippocampus. Bath application of 4 aminopyridine (4AP, 100 µM) initiated ictal- and interictal-like synchronized epileptiform discharges in the brain slices. Fifty micromolar fisetin was applied to the recording chamber during the epileptiform activity. The duration and frequencies of both ictal-like and interictal-like activities were calculated from the electrophysiological records. Molecular docking was performed to reveal interaction of fisetin on GABA-A, NMDA, AMPA receptors, and HCN2 channel, which are neuronal structures directly involved in recorded activity. Although fisetin does not affect basal neuronal activity in brain slice, it reduced the duration of ictal-like discharges significantly. Molecular docking results indicated that fisetin has no effect on GABA-A, NMDA, and AMPA receptors. However, fisetin binds to the (5JON) HCN2 channel strongly with the binding energy of -7.66 kcal/mol. Reduction on the duration of 4AP-induced ictal-like discharges can be explained as HCN channels can cause an inhibitory effect via enhancing M-type K + channels which increase K outward currents.
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Affiliation(s)
- Hilal Ozturk
- Department of Biophysics, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
- Department of Biophysics, Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Harun Basoglu
- Department of Biophysics, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey.
| | - Nuri Yorulmaz
- Department of Physics, Faculty of Science, Harran University, Sanliurfa, Turkey
| | - Selcen Aydin-Abidin
- Department of Biophysics, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ismail Abidin
- Department of Biophysics, Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
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Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
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Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
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4
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Sciamanna G, Ponterio G, Vanni V, Laricchiuta D, Martella G, Bonsi P, Meringolo M, Tassone A, Mercuri NB, Pisani A. Optogenetic Activation of Striatopallidal Neurons Reveals Altered HCN Gating in DYT1 Dystonia. Cell Rep 2021; 31:107644. [PMID: 32433955 DOI: 10.1016/j.celrep.2020.107644] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 12/10/2019] [Accepted: 04/20/2020] [Indexed: 12/30/2022] Open
Abstract
Firing activity of external globus pallidus (GPe) is crucial for motor control and is severely perturbed in dystonia, a movement disorder characterized by involuntary, repetitive muscle contractions. Here, we show that GPe projection neurons exhibit a reduction of firing frequency and an irregular pattern in a DYT1 dystonia model. Optogenetic activation of the striatopallidal pathway fails to reset pacemaking activity of GPe neurons in mutant mice. Abnormal firing is paralleled by alterations in motor learning. We find that loss of dopamine D2 receptor-dependent inhibition causes increased GABA input at striatopallidal synapses, with subsequent downregulation of hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels. Accordingly, enhancing in vivo HCN channel activity or blocking GABA release restores both the ability of striatopallidal inputs to pause ongoing GPe activity and motor coordination deficits. Our findings demonstrate an impaired striatopallidal connectivity, supporting the central role of GPe in motor control and, more importantly, identifying potential pharmacological targets for dystonia.
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Affiliation(s)
- Giuseppe Sciamanna
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giulia Ponterio
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy
| | - Valentina Vanni
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Daniela Laricchiuta
- Department of Psychology, Faculty of Medicine and Psychology, University of Rome Sapienza, Rome, Italy; Lab of Behavioural and Experimental Neurophysiology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giuseppina Martella
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Paola Bonsi
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Maria Meringolo
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy
| | - Annalisa Tassone
- Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Nicola Biagio Mercuri
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Experimental Neurology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Antonio Pisani
- Department of Systems Medicine, University of Rome "Tor Vergata," Rome, Italy; Lab of Neurophysiology and Plasticity, IRCCS Fondazione Santa Lucia, Rome, Italy.
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5
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Liang Y, Xu Z, Wu X, Pang J, Zhou P, Cao Y. Inhibition of hyperpolarization-activated cyclic nucleotide-gated channels with natural flavonoid quercetin. Biochem Biophys Res Commun 2020; 533:952-957. [PMID: 33008592 DOI: 10.1016/j.bbrc.2020.09.102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 09/22/2020] [Indexed: 11/18/2022]
Abstract
Quercetin is a natural flavonoid which has been reported to be analgesic in different animal models of pain. However, the mechanism underlying the pain-relieving effects is still unclear. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play critical roles in controlling pacemaker activity in cardiac and nervous systems, making the channel a new target for therapeutic exploration. In this study, we explored a series of flavonoids for their modulation on HCN channels. Among all tested flavonoids, quercetin was the most potent inhibitor for HCN channels with an IC50 value of 27.32 ± 1.19 μM for HCN2. Furthermore, quercetin prominently left shifted the voltage-dependent activation curves of HCN channels and decelerated deactivation process. The results presented herein firstly characterize quercetin as a novel and potent inhibitor for HCN channels, which represents a novel structure for future drug design of HCN channel inhibitors.
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Affiliation(s)
- Yemei Liang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Ziwei Xu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Xiaoyan Wu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Jianxin Pang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Pingzheng Zhou
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
| | - Ying Cao
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
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6
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Trudeau MC. Paul F. Cranefield Award to Anne E. Carlson. J Gen Physiol 2019; 151:1059-1060. [PMID: 31405898 PMCID: PMC6719400 DOI: 10.1085/jgp.201912433] [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] [Indexed: 11/20/2022] Open
Abstract
Trudeau recognizes the latest recipient of the Cranefield Award.
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Affiliation(s)
- Matthew C. Trudeau
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD
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7
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Jegla T, Busey G, Assmann SM. Evolution and Structural Characteristics of Plant Voltage-Gated K + Channels. THE PLANT CELL 2018; 30:2898-2909. [PMID: 30389753 PMCID: PMC6354262 DOI: 10.1105/tpc.18.00523] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 10/09/2018] [Accepted: 10/30/2018] [Indexed: 05/18/2023]
Abstract
Plant voltage-gated K+ channels have been referred to as "plant Shakers" in reference to animal Shaker channels, the first K+ channels identified. Recent advances in our knowledge of K+ channel evolution and structure have significantly deepened the divide between these plant and animal K+ channels, suggesting that it is time to completely retire the "plant Shaker" designation. Evolutionary genomics reveals that plant voltage-gated K+ channels and metazoan Shakers derive from distinct prokaryotic ancestors. The plant channels belong to a lineage that includes cyclic nucleotide-gated channels and metazoan ether-à-go-go and hyperpolarization-activated, cyclic nucleotide-gated channels. We refer to this lineage as the CNBD channel superfamily, because all these channels share a cytoplasmic gating domain homologous to cyclic nucleotide binding domains. The first structures of CNBD superfamily channels reveal marked differences in coupling between the voltage sensor and ion-conducting pore relative to metazoan Shaker channels. Viewing plant voltage-gated K+ channel function through the lens of CNBD superfamily structures should lead to insights into how these channels are regulated.
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Affiliation(s)
- Timothy Jegla
- Department of Biology and Huck Institute for the Life Sciences, Penn State University, 230 Life Sciences Building, University Park, Pennsylvania 16802
| | - Gregory Busey
- Department of Biology, Penn State University, 225 Life Sciences Building, University Park, Pennsylvania 16802
| | - Sarah M Assmann
- Department of Biology, Penn State University, 354 North Frear, University Park, Pennsylvania 16802
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Sartiani L, Mannaioni G, Masi A, Novella Romanelli M, Cerbai E. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels. Pharmacol Rev 2017; 69:354-395. [PMID: 28878030 DOI: 10.1124/pr.117.014035] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.
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Affiliation(s)
- Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Alessio Masi
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
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9
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Zhang X, Li H, Zhang H, Liu Y, Huo L, Jia Z, Xue Y, Sun X, Zhang W. Inhibition of transmembrane member 16A calcium-activated chloride channels by natural flavonoids contributes to flavonoid anticancer effects. Br J Pharmacol 2017; 174:2334-2345. [PMID: 28452066 DOI: 10.1111/bph.13841] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 04/19/2017] [Accepted: 04/20/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Natural flavonoids are ubiquitous in dietary plants and vegetables and have been proposed to have antiviral, antioxidant, cardiovascular protective and anticancer effects. Transmembrane member 16A (TMEM16A)-encoded Ca2+ -activated Cl- channels play a variety of physiological roles in many organs and tissues. Overexpression of TMEM16A is also believed to be associated with cancer progression. Therefore, inhibition of TMEM16A current may be a potential target for cancer therapy. In this study, we screened a broad spectrum of flavonoids for their inhibitory activities on TMEM16A currents. EXPERIMENTAL APPROACH A whole-cell patch technique was used to record the currents. The BrdU assay and transwell technique were used to investigate cell proliferation and migration. KEY RESULTS At a concentration of 100 μM, 10 of 20 compounds caused significant (>50%) inhibition of TMEM16A currents. The four most potent compounds - luteolin, galangin, quercetin and fisetin - had IC50 values ranging from 4.5 to 15 μM). To examine the physiological relevance of these findings, we also studied the effects of these flavonoids on endogenous TMEM16A currents in addition to cell proliferation and migration in LA795 cancer cells. Among the flavonoids tested, we detected a highly significant correlation between TMEM16A current inhibition and cell proliferation or reduction of migration. CONCLUSIONS AND IMPLICATIONS This study demonstrates that flavonoids inhibit TMEM16A currents and suggests that flavonoids could have anticancer effects via this mechanism.
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Affiliation(s)
- Xuan Zhang
- Department of Pharmacology, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, China.,Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Honglin Li
- Department of Respiratory, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Huiran Zhang
- Department of Respiratory, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yani Liu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Lifang Huo
- Department of Pharmacology, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, China
| | - Zhanfeng Jia
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Yucong Xue
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Xiaorun Sun
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Wei Zhang
- Department of Pharmacology, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, China
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Novella Romanelli M, Sartiani L, Masi A, Mannaioni G, Manetti D, Mugelli A, Cerbai E. HCN Channels Modulators: The Need for Selectivity. Curr Top Med Chem 2016; 16:1764-91. [PMID: 26975509 PMCID: PMC5374843 DOI: 10.2174/1568026616999160315130832] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.
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Affiliation(s)
- Maria Novella Romanelli
- University of Florence, Department of Neurosciences, Psychology, Drug Research and Child's Health, Section of Pharmaceutical and Nutraceutical Sciences, via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
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11
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DeBerg HA, Brzovic PS, Flynn GE, Zagotta WN, Stoll S. Structure and Energetics of Allosteric Regulation of HCN2 Ion Channels by Cyclic Nucleotides. J Biol Chem 2015; 291:371-81. [PMID: 26559974 PMCID: PMC4697172 DOI: 10.1074/jbc.m115.696450] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Indexed: 12/20/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels play an important role in regulating electrical activity in the heart and brain. They are gated by the binding of cyclic nucleotides to a conserved, intracellular cyclic nucleotide-binding domain (CNBD), which is connected to the channel pore by a C-linker region. Binding of cyclic nucleotides increases the rate and extent of channel activation and shifts it to less hyperpolarized voltages. We probed the allosteric mechanism of different cyclic nucleotides on the CNBD and on channel gating. Electrophysiology experiments showed that cAMP, cGMP, and cCMP were effective agonists of the channel and produced similar increases in the extent of channel activation. In contrast, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) on the isolated CNBD indicated that the induced conformational changes and the degrees of stabilization of the active conformation differed for the three cyclic nucleotides. We explain these results with a model where different allosteric mechanisms in the CNBD all converge to have the same effect on the C-linker and render all three cyclic nucleotides similarly potent activators of the channel.
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Affiliation(s)
- Hannah A DeBerg
- From the Departments of Chemistry, Physiology and Biophysics, and
| | - Peter S Brzovic
- Biochemistry, University of Washington, Seattle, Washington 98195
| | | | | | - Stefan Stoll
- From the Departments of Chemistry, Physiology and Biophysics, and
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12
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Sucher NJ, Carles MC. A pharmacological basis of herbal medicines for epilepsy. Epilepsy Behav 2015; 52:308-18. [PMID: 26074183 DOI: 10.1016/j.yebeh.2015.05.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 05/06/2015] [Indexed: 01/25/2023]
Abstract
Epilepsy is the most common chronic neurological disease, affecting about 1% of the world's population during their lifetime. Most people with epilepsy can attain a seizure-free life upon treatment with antiepileptic drugs (AEDs). Unfortunately, seizures in up to 30% do not respond to treatment. It is estimated that 90% of people with epilepsy live in developing countries, and most of them receive no drug treatment for the disease. This treatment gap has motivated investigations into the effects of plants that have been used by traditional healers all over the world to treat seizures. Extracts of hundreds of plants have been shown to exhibit anticonvulsant activity in phenotypic screens performed in experimental animals. Some of those extracts appear to exhibit anticonvulsant efficacy similar to that of synthetic AEDs. Dozens of plant-derived chemical compounds have similarly been shown to act as anticonvulsants in various in vivo and in vitro assays. To a significant degree, anticonvulsant effects of plant extracts can be attributed to widely distributed flavonoids, (furano)coumarins, phenylpropanoids, and terpenoids. Flavonoids and coumarins have been shown to interact with the benzodiazepine site of the GABAA receptor and various voltage-gated ion channels, which are targets of synthetic AEDs. Modulation of the activity of ligand-gated and voltage-gated ion channels provides an explanatory basis of the anticonvulsant effects of plant secondary metabolites. Many complex extracts and single plant-derived compounds exhibit antiinflammatory, neuroprotective, and cognition-enhancing activities that may be beneficial in the treatment of epilepsy. Thus, botanicals provide a base for target-oriented antiepileptic drug discovery and development. In the future, preclinical work should focus on the characterization of the effects of plant extracts and plant-derived compounds on well-defined targets rather than on phenotypic screening using in vivo animal models of acute seizures. At the same time, available data provide ample justification for clinical studies with selected standardized botanical extracts and plant-derived compounds. This article is part of a Special Issue entitled "Botanicals for Epilepsy".
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Affiliation(s)
- Nikolaus J Sucher
- Science Department, Roxbury Community College, MA, USA; FLAS, Northern Essex Community College, MA, USA; Biology Department, Salem State University, MA, USA.
| | - Maria C Carles
- Science Department, Roxbury Community College, MA, USA; FLAS, Northern Essex Community College, MA, USA; Biology Department, Salem State University, MA, USA
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