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Kang H, Kim J, Park CH, Jeong B, So I. Direct modulation of TRPC ion channels by Gα proteins. Front Physiol 2024; 15:1362987. [PMID: 38384797 PMCID: PMC10880550 DOI: 10.3389/fphys.2024.1362987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 01/26/2024] [Indexed: 02/23/2024] Open
Abstract
GPCR-Gi protein pathways are involved in the regulation of vagus muscarinic pathway under physiological conditions and are closely associated with the regulation of internal visceral organs. The muscarinic receptor-operated cationic channel is important in GPCR-Gi protein signal transduction as it decreases heart rate and increases GI rhythm frequency. In the SA node of the heart, acetylcholine binds to the M2 receptor and the released Gβγ activates GIRK (I(K,ACh)) channel, inducing a negative chronotropic action. In gastric smooth muscle, there are two muscarinic acetylcholine receptor (mAChR) subtypes, M2 and M3. M2 receptor activates the muscarinic receptor-operated nonselective cationic current (mIcat, NSCC(ACh)) and induces positive chronotropic effect. Meanwhile, M3 receptor induces hydrolysis of PIP2 and releases DAG and IP3. This IP3 increases intracellular Ca2+ and then leads to contraction of GI smooth muscles. The activation of mIcat is inhibited by anti-Gi/o protein antibodies in GI smooth muscle, indicating the involvement of Gαi/o protein in the activation of mIcat. TRPC4 channel is a molecular candidate for mIcat and can be directly activated by constitutively active Gαi QL proteins. TRPC4 and TRPC5 belong to the same subfamily and both are activated by Gi/o proteins. Initial studies suggested that the binding sites for G protein exist at the rib helix or the CIRB domain of TRPC4/5 channels. However, recent cryo-EM structure showed that IYY58-60 amino acids at ARD of TRPC5 binds with Gi3 protein. Considering the expression of TRPC4/5 in the brain, the direct G protein activation on TRPC4/5 is important in terms of neurophysiology. TRPC4/5 channels are also suggested as a coincidence detector for Gi and Gq pathway as Gq pathway increases intracellular Ca2+ and the increased Ca2+ facilitates the activation of TRPC4/5 channels. More complicated situation would occur when GIRK, KCNQ2/3 (IM) and TRPC4/5 channels are co-activated by stimulation of muscarinic receptors at the acetylcholine-releasing nerve terminals. This review highlights the effects of GPCR-Gi protein pathway, including dopamine, μ-opioid, serotonin, glutamate, GABA, on various oragns, and it emphasizes the importance of considering TRPC4/5 channels as crucial players in the field of neuroscience.
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Affiliation(s)
- Hana Kang
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jinhyeong Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Christine Haewon Park
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
| | - Byeongseok Jeong
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Insuk So
- Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
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Müller S, Kartheus M, Hendinger E, Hübner DC, Schnell E, Rackow S, Bertsche A, Köhling R, Kirschstein T. Persistent Kv7.2/7.3 downregulation in the rat pilocarpine model of mesial temporal lobe epilepsy. Epilepsy Res 2024; 200:107296. [PMID: 38219422 DOI: 10.1016/j.eplepsyres.2024.107296] [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: 10/02/2023] [Revised: 12/04/2023] [Accepted: 01/05/2024] [Indexed: 01/16/2024]
Abstract
Mutations within the Kv7.2 and Kv7.3 genes are well described causes for genetic childhood epilepsies. Knowledge on these channels in acquired focal epilepsy, especially in mesial temporal lobe epilepsy (mTLE), however, is scarce. Here, we used the rat pilocarpine model of drug-resistant mTLE to elucidate both expression and function by quantitative polymerase-chain reaction, immunohistochemistry, and electrophysiology, respectively. We found transcriptional downregulation of Kv7.2 and Kv7.3 as well as reduced Kv7.2 expression in epileptic CA1. Consequences were altered synaptic transmission, hyperexcitability which consisted of epileptiform afterpotentials, and increased susceptibility to acute GABAergic disinhibition. Importantly, blocking Kv7 channels with XE991 increased hyperexcitability in control tissue, but not in chronically epileptic tissue suggesting that the Kv7 deficit had precluded XE991 effects in this tissue. Conversely, XE991 resulted in comparable reduction of the paired-pulse ratio in both experimental groups implying preserved presynaptic Kv7.2 function of Schaffer collateral terminals. Consistent with Kv7.2/7.3 downregulation, the Kv7.3 channel opener β-hydroxybutyrate failed to mitigate hyperexcitability. Our findings demonstrate that compromised Kv7 function is not only relevant in genetic epilepsy, but also in acquired focal epilepsy. Moreover, they help explain reduced anti-seizure efficacy of Kv7 channel openers in drug-resistant epilepsy.
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Affiliation(s)
- Steffen Müller
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany
| | - Mareike Kartheus
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany
| | - Elisabeth Hendinger
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany
| | | | - Emma Schnell
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany
| | - Simone Rackow
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany
| | - Astrid Bertsche
- Department Neuropaediatrics, Hospital for Children and Adolescents, University Medicine Greifswald, Germany
| | - Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany; Center of Transdisciplinary Neurosciences Rostock (CTNR), University Medicine Rostock, Germany
| | - Timo Kirschstein
- Oscar Langendorff Institute of Physiology, University Medicine Rostock, Germany; Center of Transdisciplinary Neurosciences Rostock (CTNR), University Medicine Rostock, Germany.
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Dai G. Neuronal KCNQ2/3 channels are recruited to lipid raft microdomains by palmitoylation of BACE1. J Gen Physiol 2022; 154:213033. [PMID: 35201266 PMCID: PMC8876601 DOI: 10.1085/jgp.202112888] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 02/04/2022] [Indexed: 12/14/2022] Open
Abstract
β-Secretase 1 (β-site amyloid precursor protein [APP]-cleaving enzyme 1, BACE1) plays a crucial role in the amyloidogenesis of Alzheimer’s disease (AD). BACE1 was also discovered to act like an auxiliary subunit to modulate neuronal KCNQ2/3 channels independently of its proteolytic function. BACE1 is palmitoylated at its carboxyl-terminal region, which brings BACE1 to ordered, cholesterol-rich membrane microdomains (lipid rafts). However, the physiological consequences of this specific localization of BACE1 remain elusive. Using spectral Förster resonance energy transfer (FRET), BACE1 and KCNQ2/3 channels were confirmed to form a signaling complex, a phenomenon that was relatively independent of the palmitoylation of BACE1. Nevertheless, palmitoylation of BACE1 was required for recruitment of KCNQ2/3 channels to lipid-raft domains. Two fluorescent probes, designated L10 and S15, were used to label lipid-raft and non-raft domains of the plasma membrane, respectively. Coexpressing BACE1 substantially elevated FRET between L10 and KCNQ2/3, whereas the BACE1-4C/A quadruple mutation failed to produce this effect. In contrast, BACE1 had no significant effect on FRET between S15 probes and KCNQ2/3 channels. A reduction of BACE1-dependent FRET between raft-targeting L10 probes and KCNQ2/3 channels by applying the cholesterol-extracting reagent methyl-β-cyclodextrin (MβCD), raft-disrupting general anesthetics, or pharmacological inhibitors of palmitoylation, all supported the hypothesis of the palmitoylation-dependent and raft-specific localization of KCNQ2/3 channels. Furthermore, mutating the four carboxyl-terminal cysteines (4C/A) of BACE1 abolished the BACE1-dependent increase of FRET between KCNQ2/3 and the lipid raft–specific protein caveolin 1. Taking these data collectively, we propose that the AD-related protein BACE1 underlies the localization of a neuronal potassium channel.
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Affiliation(s)
- Gucan Dai
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
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Lo YC, Lin CL, Fang WY, Lőrinczi B, Szatmári I, Chang WH, Fülöp F, Wu SN. Effective Activation by Kynurenic Acid and Its Aminoalkylated Derivatives on M-Type K + Current. Int J Mol Sci 2021; 22:ijms22031300. [PMID: 33525680 PMCID: PMC7865226 DOI: 10.3390/ijms22031300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/24/2022] Open
Abstract
Kynurenic acid (KYNA, 4-oxoquinoline-2-carboxylic acid), an intermediate of the tryptophan metabolism, has been recognized to exert different neuroactive actions; however, the need of how it or its aminoalkylated amide derivative N-(2-(dimethylamino)ethyl)-3-(morpholinomethyl)-4-oxo-1,4-dihydroquinoline-2-carboxamide (KYNA-A4) exerts any effects on ion currents in excitable cells remains largely unmet. In this study, the investigations of how KYNA and other structurally similar KYNA derivatives have any adjustments on different ionic currents in pituitary GH3 cells and hippocampal mHippoE-14 neurons were performed by patch-clamp technique. KYNA or KYNA-A4 increased the amplitude of M-type K+ current (IK(M)) and concomitantly enhanced the activation time course of the current. The EC50 value required for KYNA- or KYNA-A4 -stimulated IK(M) was yielded to be 18.1 or 6.4 μM, respectively. The presence of KYNA or KYNA-A4 shifted the relationship of normalized IK(M)-conductance versus membrane potential to more depolarized potential with no change in the gating charge of the current. The voltage-dependent hysteretic area of IK(M) elicited by long-lasting triangular ramp pulse was observed in GH3 cells and that was increased during exposure to KYNA or KYNA-A4. In cell-attached current recordings, addition of KYNA raised the open probability of M-type K+ channels, along with increased mean open time of the channel. Cell exposure to KYNA or KYNA-A4 mildly inhibited delayed-rectifying K+ current; however, neither erg-mediated K+ current, hyperpolarization-activated cation current, nor voltage-gated Na+ current in GH3 cells was changed by KYNA or KYNA-A4. Under whole-cell, current-clamp recordings, exposure to KYNA or KYNA-A4 diminished the frequency of spontaneous action potentials; moreover, their reduction in firing frequency was attenuated by linopirdine, yet not by iberiotoxin or apamin. In hippocampal mHippoE-14 neurons, the addition of KYNA also increased the IK(M) amplitude effectively. Taken together, the actions presented herein would be one of the noticeable mechanisms through which they modulate functional activities of excitable cells occurring in vivo.
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Affiliation(s)
- Yi-Ching Lo
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
| | - Chih-Lung Lin
- Department of Neurosurgery, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan;
- Department of Neurosurgery, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Wei-Yu Fang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
| | - Bálint Lőrinczi
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - István Szatmári
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - Wan-Hsuan Chang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Ferenc Fülöp
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
- MTA-SZTE Stereochemistry Research Group, Hungarian Academy of Sciences, Eötvös u. 6, H-6720 Szeged, Hungary
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
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Zwierzyńska E, Krupa-Burtnik A, Pietrzak B. Beneficial effect of retigabine on memory in rats receiving ethanol. Pharmacol Rep 2021; 73:480-489. [PMID: 33385172 PMCID: PMC7994244 DOI: 10.1007/s43440-020-00205-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/14/2020] [Accepted: 11/29/2020] [Indexed: 11/25/2022]
Abstract
Background Retigabine belongs to the novel generation of antiepileptic drugs but its complex mechanism of action causes that the drug might be effective in other diseases, for instance, alcohol dependence. It is known that ethanol abuse impaired the function of brain structures associated with memory and learning such as the hippocampus. In our previous study, retigabine reduced hippocampal changes induced by ethanol in the EEG rhythms in rabbits. This study is focused on the impact of retigabine on memory processes in male rats receiving alcohol. Methods Memory was evaluated in various experimental models: Morris water maze, Contextual, and Cued Fear Conditioning tests. Retigabine was administered for 3 weeks directly to the stomach via oral gavage at a dose of 10 mg/kg. Rats received also 20% ethanol (5 g/kg/day in two doses) via oral gavage for 3 weeks and had free access to 5% ethanol in the afternoon and at night. Morris water maze was performed after 1 and 3 weeks of ethanol administration and after 1 week from the discontinuation of ethanol administration. Contextual and Cued Fear Conditioning tests were carried out after 24 h and 72 h of alcohol discontinuation. Results The drug significantly decreased ethanol-induced memory disturbances during alcohol administration as well as slightly improved learning processes after the discontinuation of ethanol administration. Conclusions This beneficial effect of retigabine-ethanol interaction on memory may be a relevant element of the drug’s impact on the development of addiction.
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Affiliation(s)
- Ewa Zwierzyńska
- Department of Pharmacodynamics, Medical University of Lodz, Muszyńskiego 1, 90-151, Łódź, Poland.
| | - Agata Krupa-Burtnik
- Department of Pharmacodynamics, Medical University of Lodz, Muszyńskiego 1, 90-151, Łódź, Poland
| | - Bogusława Pietrzak
- Department of Pharmacodynamics, Medical University of Lodz, Muszyńskiego 1, 90-151, Łódź, Poland
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Vigil FA, Carver CM, Shapiro MS. Pharmacological Manipulation of K v 7 Channels as a New Therapeutic Tool for Multiple Brain Disorders. Front Physiol 2020; 11:688. [PMID: 32636759 PMCID: PMC7317068 DOI: 10.3389/fphys.2020.00688] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
K v 7 ("M-type," KCNQ) K+ currents, play dominant roles in controlling neuronal excitability. They act as a "brake" against hyperexcitable states in the central and peripheral nervous systems. Pharmacological augmentation of M current has been developed for controlling epileptic seizures, although current pharmacological tools are uneven in practical usefulness. Lately, however, M-current "opener" compounds have been suggested to be efficacious in preventing brain damage after multiple types of insults/diseases, such as stroke, traumatic brain injury, drug addiction and mood disorders. In this review, we will discuss what is known to date on these efforts and identify gaps in our knowledge regarding the link between M current and therapeutic potential for these disorders. We will outline the preclinical experiments that are yet to be performed to demonstrate the likelihood of success of this approach in human trials. Finally, we also address multiple pharmacological tools available to manipulate different K v 7 subunits and the relevant evidence for translational application in the clinical use for disorders of the central nervous system and multiple types of brain insults. We feel there to be great potential for manipulation of K v 7 channels as a novel therapeutic mode of intervention in the clinic, and that the paucity of existing therapies obligates us to perform further research, so that patients can soon benefit from such therapeutic approaches.
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Affiliation(s)
- Fabio A Vigil
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Chase M Carver
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Mark S Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
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Luszczki JJ, Panasiuk A, Zagaja M, Karwan S, Bojar H, Plewa Z, Florek-Łuszczki M. Polygonogram and isobolographic analysis of interactions between various novel antiepileptic drugs in the 6-Hz corneal stimulation-induced seizure model in mice. PLoS One 2020; 15:e0234070. [PMID: 32479532 PMCID: PMC7263629 DOI: 10.1371/journal.pone.0234070] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/17/2020] [Indexed: 12/11/2022] Open
Abstract
Pharmacotherapy with two antiepileptic drugs in combination is usually prescribed to epilepsy patients with refractory seizures. The choice of antiepileptic drugs in combination should be based on synergistic cooperation of the drugs with respect to suppression of seizures. The selection of synergistic interactions between antiepileptic drugs is challenging issue for physicians, especially, if 25 antiepileptic drugs are currently available and approved to treat epilepsy patients. The aim of this study was to determine all possible interactions among 5 second-generation antiepileptic drugs (gabapentin (GBP), lacosamide (LCM), levetiracetam (LEV), pregabalin (PGB) and retigabine (RTG)) in the 6-Hz corneal stimulation-induced seizure model in adult male albino Swiss mice. The anticonvulsant effects of 10 various two-drug combinations of antiepileptic drugs were evaluated with type I isobolographic analysis associated with graphical presentation of polygonogram to visualize the types of interactions. Isobolographic analysis revealed that 7 two-drug combinations of LEV+RTG, LEV+LCM, GBP+RTG, PGB+LEV, GBP+LEV, PGB+RTG, PGB+LCM were synergistic in the 6-Hz corneal stimulation-induced seizure model in mice. The additive interaction was observed for the combinations of GBP+LCM, GBP+PGB, and RTG+LCM in this seizure model in mice. The most beneficial combination, offering the highest level of synergistic suppression of seizures in mice was that of LEV+RTG, whereas the most additive combination that protected the animals from seizures was that reporting additivity for RTG+LCM. The strength of interaction for two-drug combinations can be arranged from the synergistic to the additive, as follows: LEV+RTG > LEV+LCM > GBP+RTG > PGB+LEV > GBP+LEV > PGB+RTG > PGB+LCM > GBP+LCM > GBP+PGB > RTG+LCM.
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Affiliation(s)
- Jarogniew J. Luszczki
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
- Isobolographic Analysis Laboratory, Institute of Rural Health, Lublin, Poland
- * E-mail: ,
| | - Anna Panasiuk
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
- Department of Anesthesiology and Intensive Care, Medical University of Lublin, Lublin, Poland
| | - Mirosław Zagaja
- Isobolographic Analysis Laboratory, Institute of Rural Health, Lublin, Poland
| | | | - Hubert Bojar
- Department of Toxicology and Food Safety, Institute of Rural Health, Lublin, Poland
| | - Zbigniew Plewa
- Department of General, Oncological and Minimally Invasive Surgery, 1st Military Clinical Hospital, Lublin, Poland
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