1
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Using induced pluripotent stem cells to investigate human neuronal phenotypes in 1q21.1 deletion and duplication syndrome. Mol Psychiatry 2022; 27:819-830. [PMID: 34112971 PMCID: PMC9054650 DOI: 10.1038/s41380-021-01182-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/17/2021] [Accepted: 05/27/2021] [Indexed: 01/08/2023]
Abstract
Copy Number Variation (CNV) at the 1q21.1 locus is associated with a range of neurodevelopmental and psychiatric disorders in humans, including abnormalities in head size and motor deficits. Yet, the functional consequences of these CNVs (both deletion and duplication) on neuronal development remain unknown. To determine the impact of CNV at the 1q21.1 locus on neuronal development, we generated induced pluripotent stem cells from individuals harbouring 1q21.1 deletion or duplication and differentiated them into functional cortical neurons. We show that neurons with 1q21.1 deletion or duplication display reciprocal phenotype with respect to proliferation, differentiation potential, neuronal maturation, synaptic density and functional activity. Deletion of the 1q21.1 locus was also associated with an increased expression of lower cortical layer markers. This difference was conserved in the mouse model of 1q21.1 deletion, which displayed altered corticogenesis. Importantly, we show that neurons with 1q21.1 deletion and duplication are associated with differential expression of calcium channels and demonstrate that physiological deficits in neurons with 1q21.1 deletion or duplication can be pharmacologically modulated by targeting Ca2+ channel activity. These findings provide biological insight into the neuropathological mechanism underlying 1q21.1 associated brain disorder and indicate a potential target for therapeutic interventions.
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Popović N, Morales-Delgado N, Vidal Mena D, Alonso A, Pascual Martínez M, Caballero Bleda M, Popović M. Verapamil and Alzheimer's Disease: Past, Present, and Future. Front Pharmacol 2020; 11:562. [PMID: 32431612 PMCID: PMC7214748 DOI: 10.3389/fphar.2020.00562] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 04/14/2020] [Indexed: 12/18/2022] Open
Abstract
Verapamil is a phenylalkylamine class calcium channel blocker that for half a century has been used for the treatment of cardiovascular diseases. Nowadays, verapamil is also considered as a drug option for the treatment of several neurological and psychiatric disorders, such as cluster headache, bipolar disorders, epilepsy, and neurodegenerative diseases. Here, we review insights into the potential preventive and therapeutic role of verapamil on Alzheimer’s disease (AD) based on limited experimental and clinical data. Pharmacological studies have shown that verapamil has a wide therapeutic spectrum, including antihypertensive, anti-inflammatory, and antioxidative effects, regulation of the blood-brain barrier function, due to its effect on P-glycoprotein, as well as adjustment of cellular calcium homeostasis, which may result in the delay of AD onset or ameliorate the symptoms of patients. However, the majority of the AD individuals are on polypharmacotherapy, and the interactions between verapamil and other drugs need to be considered. Therefore, for an appropriate and successful AD treatment, a personalized approach is more than necessary. A well-known narrow pharmacological window of verapamil efficacy may hinder this approach. It is therefore important to note that the verapamil efficacy may be conditioned by different factors. The onset, grade, and brain distribution of AD pathological hallmarks, the time-sequential appearances of AD-related cognitive and behavioral dysfunction, the chronobiologic and gender impact on calcium homeostasis and AD pathogenesis may somehow be influencing that success. In the future, such insights will be crucial for testing the validity of verapamil treatment on animal models of AD and clinical approaches.
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Affiliation(s)
- Natalija Popović
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain
| | - Nicanor Morales-Delgado
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain.,Department of Histology and Anatomy, Faculty of Medicine, University of Miguel Hernández, Sant Joan Alacant, Spain
| | - David Vidal Mena
- Neurological Unit, University Hospital "Santa Lucia", Cartagena, Spain
| | - Antonia Alonso
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain
| | | | - María Caballero Bleda
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain
| | - Miroljub Popović
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain
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3
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Cardiomyocytes Sense Matrix Rigidity through a Combination of Muscle and Non-muscle Myosin Contractions. Dev Cell 2018; 44:326-336.e3. [PMID: 29396114 PMCID: PMC5807060 DOI: 10.1016/j.devcel.2017.12.024] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 11/09/2017] [Accepted: 12/22/2017] [Indexed: 12/31/2022]
Abstract
Mechanical properties are cues for many biological processes in health or disease. In the heart, changes to the extracellular matrix composition and cross-linking result in stiffening of the cellular microenvironment during development. Moreover, myocardial infarction and cardiomyopathies lead to fibrosis and a stiffer environment, affecting cardiomyocyte behavior. Here, we identify that single cardiomyocyte adhesions sense simultaneous (fast oscillating) cardiac and (slow) non-muscle myosin contractions. Together, these lead to oscillating tension on the mechanosensitive adaptor protein talin on substrates with a stiffness of healthy adult heart tissue, compared with no tension on embryonic heart stiffness and continuous stretching on fibrotic stiffness. Moreover, we show that activation of PKC leads to the induction of cardiomyocyte hypertrophy in a stiffness-dependent way, through activation of non-muscle myosin. Finally, PKC and non-muscle myosin are upregulated at the costameres in heart disease, indicating aberrant mechanosensing as a contributing factor to long-term remodeling and heart failure. Talin in cardiomyocytes is unstretched, cyclically stretched, or continuously stretched Talin stretching depends on stiffness, myofibrillar tension, and non-myofibrillar tension Non-myofibrillar contractility requires PKC, Src, FHOD1, and non-muscle myosin PKC and non-muscle myosin activity are enhanced in cardiac disease
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Shi L, Chang JYA, Yu F, Ko ML, Ko GYP. The Contribution of L-Type Ca v1.3 Channels to Retinal Light Responses. Front Mol Neurosci 2017; 10:394. [PMID: 29259539 PMCID: PMC5723326 DOI: 10.3389/fnmol.2017.00394] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/10/2017] [Indexed: 01/28/2023] Open
Abstract
L-type voltage-gated calcium channels (LTCCs) regulate tonic neurotransmitter release from sensory neurons including retinal photoreceptors. There are three types of LTCCs (Cav1.2, Cav1.3, and Cav1.4) expressed in the retina. While Cav1.2 is expressed in all retinal cells including the Müller glia and neurons, Cav1.3 and Cav1.4 are expressed in the retinal neurons with Cav1.4 exclusively expressed in the photoreceptor synaptic terminals. Mutations in the gene encoding Cav1.4 cause incomplete X-linked congenital stationary night blindness in humans. Even though Cav1.3 is present in the photoreceptor inner segments and the synaptic terminals in various vertebrate species, its role in vision is unclear, since genetic alterations in Cav1.3 are not associated with severe vision impairment in humans or in Cav1.3-null (Cav1.3-/-) mice. However, a failure to regulate Cav1.3 was found in a mouse model of Usher syndrome, the most common cause of combined deafness and blindness in humans, indicating that Cav1.3 may contribute to retinal function. In this report, we combined physiological and morphological data to demonstrate the role of Cav1.3 in retinal physiology and function that has been undervalued thus far. Through ex vivo and in vivo electroretinogram (ERG) recordings and immunohistochemical staining, we found that Cav1.3 plays a role in retinal light responses and synaptic plasticity. Pharmacological inhibition of Cav1.3 decreased ex vivo ERG a- and b-wave amplitudes. In Cav1.3-/- mice, their dark-adapted ERG a-, b-wave, and oscillatory potential amplitudes were significantly dampened, and implicit times were delayed compared to the wild type (WT). Furthermore, the density of ribbon synapses was reduced in the outer plexiform layer of Cav1.3-/- mice retinas. Hence, Cav1.3 plays a more prominent role in retinal physiology and function than previously reported.
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Affiliation(s)
- Liheng Shi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Janet Ya-An Chang
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Fei Yu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Michael L Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States.,Texas A&M Institute of Neuroscience, Texas A&M University, College Station, TX, United States
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5
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Giménez De Béjar V, Caballero Bleda M, Popović N, Popović M. Verapamil Blocks Scopolamine Enhancement Effect on Memory Consolidation in Passive Avoidance Task in Rats. Front Pharmacol 2017; 8:566. [PMID: 28878678 PMCID: PMC5572412 DOI: 10.3389/fphar.2017.00566] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/09/2017] [Indexed: 12/20/2022] Open
Abstract
Our recent data have indicated that scopolamine, a non-selective muscarinic receptor antagonist, improves memory consolidation, in a passive avoidance task, tested in rats. It has been found that verapamil, a phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, inhibits [3H] N-methyl scopolamine binding to M1 muscarinic receptors. However, there are no data about the effect of verapamil on memory consolidation in the passive avoidance task, in rats. The purpose of the present study was to examine the effects of verapamil (0.5, 1.0, 2.5, 5.0, 10, or 20 mg/kg i.p.) as well as the interaction between scopolamine and verapamil on memory consolidation in the step-through passive avoidance task, in Wistar rats. Our results showed that verapamil (1.0 and 2.5 mg/kg) administered immediately after the acquisition task significantly increased the latency of the passive avoidance response, on the 48 h retested trial, improving memory consolidation. On the other hand, verapamil in a dose of 5 mg/kg, that per se does not affect memory consolidation, significantly reversed the memory consolidation improvement induced by scopolamine (1 mg/kg, i.p., administered immediately after verapamil treatment) but did not change the passive avoidance response in rats treated by an ineffective dose of scopolamine (30 mg/kg). In conclusion, the present data suggest that (1) the post-training administration of verapamil, dose-dependently, improves the passive avoidance response; (2) verapamil, in ineffective dose, abolished the improvement of memory consolidation effect of scopolamine; and (3) exists interaction between cholinergic muscarinic receptors and calcium homeostasis-related mechanisms in the consolidation of emotional memory.
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Affiliation(s)
- Verónica Giménez De Béjar
- Department of Neurology, Hospital Quirónsalud MurciaMurcia, Spain.,Instituto Murciano de Investigación Biosanitaria Virgen de la ArrixacaMurcia, Spain
| | - María Caballero Bleda
- Instituto Murciano de Investigación Biosanitaria Virgen de la ArrixacaMurcia, Spain.,Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain
| | - Natalija Popović
- Instituto Murciano de Investigación Biosanitaria Virgen de la ArrixacaMurcia, Spain.,Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain
| | - Miroljub Popović
- Instituto Murciano de Investigación Biosanitaria Virgen de la ArrixacaMurcia, Spain.,Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain
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6
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van Lieshout JH, Dibué-Adjei M, Cornelius JF, Slotty PJ, Schneider T, Restin T, Boogaarts HD, Steiger HJ, Petridis AK, Kamp MA. An introduction to the pathophysiology of aneurysmal subarachnoid hemorrhage. Neurosurg Rev 2017; 41:917-930. [PMID: 28215029 DOI: 10.1007/s10143-017-0827-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/24/2017] [Accepted: 01/31/2017] [Indexed: 02/06/2023]
Abstract
Pathophysiological processes following subarachnoid hemorrhage (SAH) present survivors of the initial bleeding with a high risk of morbidity and mortality during the course of the disease. As angiographic vasospasm is strongly associated with delayed cerebral ischemia (DCI) and clinical outcome, clinical trials in the last few decades focused on prevention of these angiographic spasms. Despite all efforts, no new pharmacological agents have shown to improve patient outcome. As such, it has become clear that our understanding of the pathophysiology of SAH is incomplete and we need to reevaluate our concepts on the complex pathophysiological process following SAH. Angiographic vasospasm is probably important. However, a unifying theory for the pathophysiological changes following SAH has yet not been described. Some of these changes may be causally connected or present themselves as an epiphenomenon of an associated process. A causal connection between DCI and early brain injury (EBI) would mean that future therapies should address EBI more specifically. If the mechanisms following SAH display no causal pathophysiological connection but are rather evoked by the subarachnoid blood and its degradation production, multiple treatment strategies addressing the different pathophysiological mechanisms are required. The discrepancy between experimental and clinical SAH could be one reason for unsuccessful translational results.
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Affiliation(s)
- Jasper H van Lieshout
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany.
| | - Maxine Dibué-Adjei
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Jan F Cornelius
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Philipp J Slotty
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Toni Schneider
- Institute for Neurophysiology, Medical Faculty, University of Cologne, Robert-Koch-Str. 39, 50931, Köln, Germany
| | - Tanja Restin
- Zurich Centre for Integrative Human Physiology, Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Institute of Anesthesiology, Medical Faculty, University Hospital Zurich, Rämistrasse 100, 8091, Zurich, Switzerland
| | - Hieronymus D Boogaarts
- Department of Neurosurgery, Medical Faculty, Radboud University Nijmegen, Geert Grooteplein Zuid 10, 6525 GA, Nijmegen, the Netherlands
| | - Hans-Jakob Steiger
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Athanasios K Petridis
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Marcel A Kamp
- Department of Neurosurgery, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Germany
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7
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Popović N, Giménez de Béjar V, Caballero-Bleda M, Popović M. Verapamil Parameter- and Dose-Dependently Impairs Memory Consolidation in Open Field Habituation Task in Rats. Front Pharmacol 2017; 7:539. [PMID: 28119614 PMCID: PMC5223647 DOI: 10.3389/fphar.2016.00539] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 12/26/2016] [Indexed: 11/13/2022] Open
Abstract
The purpose of the present study was to examine the effects of the phenylalkylamine class of the L-type voltage-dependent calcium channel antagonist, verapamil (1.0, 2.5, 5.0, or 10 mg/kg i.p.), administered immediately after the acquisition task, on memory consolidation of the open field habituation task, in male Wistar rats. On the 48 h retested trial, all tested parameters (ambulation in the side wall and in the central areas, number of rearing, time spent grooming and defecation rate) significantly decreased in the saline treated animals. A significant decrease of rearing was observed in all verapamil treated groups. On the retention day, the ambulation in the side wall and central areas significantly decreased in the animals treated with 1 mg/kg and 10 mg/kg of verapamil, while the time spent grooming and the defecation rate significantly decreased only in the group treated with 1 mg/kg of verapamil. According to the change ratio scores that correct the individual behavioral baseline differences during initial and final sessions, habituation deficit was found in animals treated with verapamil as follows: ambulation along the side wall area (1, 2.5, and 5 mg/kg), number of rearing (all used dose) and time spent grooming (2.5, 5, and 10 mg/kg). In conclusion, the present data suggest that the post-training administration of verapamil, parameter- and dose-dependently, impairs the habituation to a novel environment.
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Affiliation(s)
- Natalija Popović
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain; Instituto Murciano de Investigación Biosanitaria, Virgen de la ArrixacaMurcia, Spain
| | - Verónica Giménez de Béjar
- Instituto Murciano de Investigación Biosanitaria, Virgen de la ArrixacaMurcia, Spain; Department of Neurology, Santa Lucía University General HospitalCartagena, Spain
| | - María Caballero-Bleda
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain; Instituto Murciano de Investigación Biosanitaria, Virgen de la ArrixacaMurcia, Spain
| | - Miroljub Popović
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of MurciaMurcia, Spain; Instituto Murciano de Investigación Biosanitaria, Virgen de la ArrixacaMurcia, Spain
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8
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Lewis BB, Miller LE, Herbst WA, Saha MS. The role of voltage-gated calcium channels in neurotransmitter phenotype specification: Coexpression and functional analysis in Xenopus laevis. J Comp Neurol 2014; 522:2518-31. [PMID: 24477801 PMCID: PMC4043876 DOI: 10.1002/cne.23547] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/22/2014] [Accepted: 01/22/2014] [Indexed: 12/20/2022]
Abstract
Calcium activity has been implicated in many neurodevelopmental events, including the specification of neurotransmitter phenotypes. Higher levels of calcium activity lead to an increased number of inhibitory neural phenotypes, whereas lower levels of calcium activity lead to excitatory neural phenotypes. Voltage-gated calcium channels (VGCCs) allow for rapid calcium entry and are expressed during early neural stages, making them likely regulators of activity-dependent neurotransmitter phenotype specification. To test this hypothesis, multiplex fluorescent in situ hybridization was used to characterize the coexpression of eight VGCC α1 subunits with the excitatory and inhibitory neural markers xVGlut1 and xVIAAT in Xenopus laevis embryos. VGCC coexpression was higher with xVGlut1 than xVIAAT, especially in the hindbrain, spinal cord, and cranial nerves. Calcium activity was also analyzed on a single-cell level, and spike frequency was correlated with the expression of VGCC α1 subunits in cell culture. Cells expressing Cav2.1 and Cav2.2 displayed increased calcium spiking compared with cells not expressing this marker. The VGCC antagonist diltiazem and agonist (−)BayK 8644 were used to manipulate calcium activity. Diltiazem exposure increased the number of glutamatergic cells and decreased the number of γ-aminobutyric acid (GABA)ergic cells, whereas (−)BayK 8644 exposure decreased the number of glutamatergic cells without having an effect on the number of GABAergic cells. Given that the expression and functional manipulation of VGCCs are correlated with neurotransmitter phenotype in some, but not all, experiments, VGCCs likely act in combination with a variety of other signaling factors to determine neuronal phenotype specification. J. Comp. Neurol. 522:2518–2531, 2014.
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Affiliation(s)
- Brittany B Lewis
- Department of Biology, College of William and Mary, Williamsburg, Virginia, 23185
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Schneider T, Dibué M, Hescheler J. How "Pharmacoresistant" is Cav2.3, the Major Component of Voltage-Gated R-type Ca2+ Channels? Pharmaceuticals (Basel) 2013; 6:759-76. [PMID: 24276260 PMCID: PMC3816731 DOI: 10.3390/ph6060759] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/26/2013] [Accepted: 05/06/2013] [Indexed: 12/04/2022] Open
Abstract
Membrane-bound voltage-gated Ca2+ channels (VGCCs) are targets for specific signaling complexes, which regulate important processes like gene expression, neurotransmitter release and neuronal excitability. It is becoming increasingly evident that the so called “resistant” (R-type) VGCC Cav2.3 is critical in several physiologic and pathophysiologic processes in the central nervous system, vascular system and in endocrine systems. However its eponymous attribute of pharmacologic inertness initially made in depth investigation of the channel difficult. Although the identification of SNX-482 as a fairly specific inhibitor of Cav2.3 in the nanomolar range has enabled insights into the channels properties, availability of other pharmacologic modulators of Cav2.3 with different chemical, physical and biological properties are of great importance for future investigations. Therefore the literature was screened systematically for molecules that modulate Cav2.3 VGCCs.
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Affiliation(s)
- Toni Schneider
- Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, Cologne D-50931, Germany; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (T.S.); (M.D.); Tel.: +49-221-478-69446 (T.S.); Fax: +49-221-478-6965 (T.S.)
| | - Maxine Dibué
- Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, Cologne D-50931, Germany; E-Mail:
- Department for Neurosurgery, Medical Faculty, Heinrich Heine University, Moorenstraße 5, Duesseldorf D-40225, Germany & Center of Molecular Medicine, Cologne D-50931, Germany
- Authors to whom correspondence should be addressed; E-Mails: (T.S.); (M.D.); Tel.: +49-221-478-69446 (T.S.); Fax: +49-221-478-6965 (T.S.)
| | - Jürgen Hescheler
- Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, Cologne D-50931, Germany; E-Mail:
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Yamamoto S, Tanabe M, Ono H. N- and L-Type Voltage-Dependent Ca 2+ Channels Contribute to the Generation of After-Discharges in the Spinal Ventral Root After Cessation of Noxious Mechanical Stimulation. J Pharmacol Sci 2012; 119:82-90. [DOI: 10.1254/jphs.12035fp] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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12
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Earl DE, Tietz EI. Inhibition of recombinant L-type voltage-gated calcium channels by positive allosteric modulators of GABAA receptors. J Pharmacol Exp Ther 2011; 337:301-11. [PMID: 21262851 DOI: 10.1124/jpet.110.178244] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Benzodiazepines (BDZs) depress neuronal excitability via positive allosteric modulation of inhibitory GABA(A) receptors (GABA(A)R). BDZs and other positive GABA(A)R modulators, including barbiturates, ethanol, and neurosteroids, can also inhibit L-type voltage-gated calcium channels (L-VGCCs), which could contribute to reduced neuronal excitability. Because neuronal L-VGCC function is up-regulated after long-term GABA(A)R modulator exposure, an interaction with L-VGCCs may also play a role in physical dependence. The current studies assessed the effects of BDZs (diazepam, flurazepam, and desalkylflurazepam), allopregnanolone, pentobarbital, and ethanol on whole-cell Ba(2+) currents through recombinant neuronal Ca(v)1.2 and Ca(v)1.3 L-VGCCs expressed with β(3) and α(2)δ-1 in HEK293T cells. Allopregnanolone was the most potent inhibitor (IC(50), ∼10 μM), followed by BDZs (IC(50), ∼50 μM), pentobarbital (IC(50), 0.3-1 mM), and ethanol (IC(50), ∼300 mM). Ca(v)1.3 channels were less sensitive to pentobarbital inhibition than Ca(v)1.2 channels, similar to dihydropyridine (DHP) L-VGCC antagonists. All GABA(A)R modulators induced a negative shift in the steady-state inactivation curve of Ca(v)1.3 channels, but only BDZs and pentobarbital induced a negative shift in Ca(v)1.2 channel inactivation. Mutation of the high-affinity DHP binding site (T1039Y and Q1043M) in Ca(v)1.2 channels reduced pentobarbital potency. Despite the structural similarity between benzothiazepines and BDZs, mutation of an amino acid important for diltiazem potency (I1150A) did not affect diazepam potency. Although L-VGCC inhibition by BDZs occurred at concentrations that are possibly too high to be clinically relevant and is not likely to play a role in the up-regulation of L-VGCCs during long-term treatment, pentobarbital and ethanol inhibited L-VGCCs at clinically relevant concentrations.
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Affiliation(s)
- Damien E Earl
- Department of Physiology and Pharmacology, University of Toledo College of Medicine, Health Science Campus, Toledo, OH 43614, USA
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13
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Tarabova B, Lacinova L, Engel J. Effects of phenylalkylamines and benzothiazepines on Cav1.3-mediated Ca2+ currents in neonatal mouse inner hair cells. Eur J Pharmacol 2007; 573:39-48. [PMID: 17651721 DOI: 10.1016/j.ejphar.2007.06.050] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 06/12/2007] [Accepted: 06/25/2007] [Indexed: 11/23/2022]
Abstract
Calcium currents (I(Ca)) in inner hair cells (IHCs) are carried by the Ca(v)1.3 subtype of L-type calcium channels. They play an important role in synaptic transmission of sound-evoked mechanical stimuli. L-type calcium channels are targets of the organic blocker classes dihydropyridines, phenylalkylamines and benzothiazepines. Previously a low sensitivity of the Ca(v)1.3 subtype towards dihydropyridines has been demonstrated. Therefore, this study evaluates the effect of two phenylalkylamines (verapamil and gallopamil) and the benzothiazepine diltiazem on I(Ca) through Ca(v)1.3 channels in mouse IHCs. Whole-cell I(Ca) was measured using the patch-clamp technique in mouse IHCs aged postnatal day 3-7 with 5 mM calcium as a charge carrier. The phenylalkylamines verapamil and gallopamil and the benzothiazepine diltiazem inhibited I(Ca) in IHCs in a concentration-dependent manner. This block was largely reversible. Dose-response curves revealed IC(50) values of 199+/-19 microM for verapamil, 466+/-151 microM for gallopamil and 326+/-67 microM for diltiazem. The inhibition of peak I(Ca) by phenylalkylamines and benzothiazepines was voltage-independent. Verapamil (300 microM) enhanced current inactivation from -20 to +20 mV while diltiazem (300 microM) did so only at very depolarised potentials (+20 mV). In conclusion, the concentrations of phenylalkylamines and benzothiazepine necessary to inhibit 50% of I(Ca) in IHCs were one order larger compared to concentrations which inhibited I(Ca) through Ca(v)1.2 channels in native cells or expression systems. However, inhibitory concentrations were in the same range as those required for block of I(Ca) in turtle hair cells.
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MESH Headings
- Algorithms
- Animals
- Animals, Newborn
- Benzazepines/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/physiology
- Calcium Signaling/drug effects
- Diltiazem/pharmacology
- Dose-Response Relationship, Drug
- Gallopamil/pharmacology
- Hair Cells, Auditory, Inner/cytology
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiology
- Membrane Potentials/drug effects
- Mice
- Mice, Inbred Strains
- Phenethylamines/pharmacology
- Verapamil/pharmacology
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Affiliation(s)
- Bohumila Tarabova
- Slovak Academy of Sciences, Institute of Molecular Physiology and Genetics, Vlárska 5, 833 34 Bratislava, Slovak Republic.
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14
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Brette F, Leroy J, Le Guennec JY, Sallé L. Ca2+ currents in cardiac myocytes: Old story, new insights. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 91:1-82. [PMID: 16503439 DOI: 10.1016/j.pbiomolbio.2005.01.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Calcium is a ubiquitous second messenger which plays key roles in numerous physiological functions. In cardiac myocytes, Ca2+ crosses the plasma membrane via specialized voltage-gated Ca2+ channels which have two main functions: (i) carrying depolarizing current by allowing positively charged Ca2+ ions to move into the cell; (ii) triggering Ca2+ release from the sarcoplasmic reticulum. Recently, it has been suggested than Ca2+ channels also participate in excitation-transcription coupling. The purpose of this review is to discuss the physiological roles of Ca2+ currents in cardiac myocytes. Next, we describe local regulation of Ca2+ channels by cyclic nucleotides. We also provide an overview of recent studies investigating the structure-function relationship of Ca2+ channels in cardiac myocytes using heterologous system expression and transgenic mice, with descriptions of the recently discovered Ca2+ channels alpha(1D) and alpha(1E). We finally discuss the potential involvement of Ca2+ currents in cardiac pathologies, such as diseases with autoimmune components, and cardiac remodeling.
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Affiliation(s)
- Fabien Brette
- School of Biomedical Sciences, University of Leeds, Worsley Building Leeds, LS2 9NQ, UK.
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15
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Dilmac N, Hilliard N, Hockerman GH. Molecular determinants of frequency dependence and Ca2+ potentiation of verapamil block in the pore region of Cav1.2. Mol Pharmacol 2004; 66:1236-47. [PMID: 15286207 DOI: 10.1124/mol.104.000893] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Verapamil block of Ca(v)1.2 is frequency-dependent and potentiated by Ca(2+). We examined the molecular determinants of these characteristics using mutations that effect Ca(2+) interactions with Ca(v)1.2. Mutant and wild-type Ca(v)1.2 channels were transiently expressed in tsA 201 cells with beta(1b) and alpha(2)delta subunits. The four conserved glutamates that compose the Ca(2+) selectivity filter in Ca(v)1.2 were mutated to Gln (E363Q, E709Q, E1118Q, E1419Q) and the adjacent conserved threonine in each domain was mutated to Ala (T361A, T707A, T1116A, T1417A). The L-type-specific residues in the domain III pore region (F1117G) and the C-terminal tail (I1627A) were also mutated and assayed for block by verapamil using whole-cell voltage-clamp recordings in 10 mM Ba(2+) or 10 mM Ca(2+). In Ba(2+), none of the pore-region mutations reduced the fraction of current blocked by 30 microM verapamil at 0.05 Hz stimulation. However, all of the pore-region mutations abolished Ca(2+) potentiation of verapamil block at 0.05 Hz. The T1116A, F1117G, E1118Q, and E1419Q mutations all significantly reduced frequency-dependent verapamil block (1-Hz stimulation) in both Ba(2+) and Ca(2+). The I1627A mutation, which disrupts Ca(2+)-dependent inactivation, increased the fraction of closed channels blocked by 30 microM verapamil in Ba(2+) but did not affect frequency-dependent block in Ba(2+) or Ca(2+). Our data suggest that the pore region of domain III may contribute to a high affinity verapamil binding site accessed during 1-Hz stimulation and that Ca(2+) binding to multiple sites may be required for potentiation of verapamil block of closed channels.
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Affiliation(s)
- Nejmi Dilmac
- Graduate Program in Biochemistry and Molecular Biology, Purdue University, West Lafayette, Indiana, USA
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16
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Lu DP, Li Y, Bathgate R, Day M, O'Neill C. Ligand-activated signal transduction in the 2-cell embryo. Biol Reprod 2003; 69:106-16. [PMID: 12606379 DOI: 10.1095/biolreprod.102.014696] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Platelet-activating factor (PAF) is an autocrine trophic/survival factor for the preimplantation embryo. PAF induced an increase in intracellular calcium concentration ([Ca2+]i) in the 2-cell embryo that had an absolute requirement for external calcium. L-type calcium channel blockers (diltiazem, verapamil, and nimodipine) significantly inhibited PAF-induced Ca2+ transients, but inhibitors of P/Q type (omega-agatoxin; omega-conotoxin MVIIC), N-type (omega-conotoxin GVIA), T-type (pimozide), and store-operated channels (SKF 96365 and econazole) did not block the transient. mRNA and protein for the alpha1-C subunit of L-type channels was expressed in the 2-cell embryo. The L-type calcium channel agonist (+/-) BAY K 8644 induced [Ca2+]i transients and, PAF and BAY K 8644 each caused mutual heterologous desensitization of each other's responses. Depolarization of the embryo (75 mM KCl) induced a [Ca2+]i transient that was inhibited by diltiazem and verapamil. Whole-cell patch-clamp measurements detected a voltage-gated channel (blocked by diltiazem, verapamil, and nifedipine) that was desensitized by prior responses of embryos to exogenous or embryo-derived PAF. Replacement of media Ca2+ with Mn2+ allowed Mn2+ influx to be observed directly; activation of a diltiazem-sensitive influx channel was an early response to PAF. The activation of a voltage-gated L-type calcium channel in the 2-cell embryo is required for normal signal transduction to an embryonic trophic factor.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Base Sequence
- Calcium Channel Agonists/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling/drug effects
- Cleavage Stage, Ovum/drug effects
- Cleavage Stage, Ovum/metabolism
- Female
- In Vitro Techniques
- Ligands
- Manganese/metabolism
- Mice
- Microscopy, Fluorescence
- Patch-Clamp Techniques
- Platelet Activating Factor/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
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Affiliation(s)
- David P Lu
- Human Reproduction Unit, Royal North Shore Hospital, University of Sydney, Sydney, New South Wales, 2065 Australia
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17
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Oka M, Itoh Y, Wada M, Yamamoto A, Fujita T. A comparison of Ca2+ channel blocking mode between gabapentin and verapamil: implication for protection against hypoxic injury in rat cerebrocortical slices. Br J Pharmacol 2003; 139:435-43. [PMID: 12770949 PMCID: PMC1573845 DOI: 10.1038/sj.bjp.0705246] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1 The mode of Ca(2+) channel blocking by gabapentin [1-(aminomethyl)cyclohexane acetic acid] was compared to those of other Ca(2+) channel blockers, and the potential role of Ca(2+) channel antagonists in providing protection against hypoxic injury was subsequently investigated in rat cerebrocortical slices. 2 mRNA for the alpha(2)delta subunits of Ca(2+) channels was found in rat cerebral cortex. 3 Nitric oxide (NO) synthesis estimated from cGMP formation was enhanced by KCl stimulation, which was mediated primarily by the activation of N- and P/Q-type Ca(2+) channels. Gabapentin blocked both types of Ca(2+) channels, and preferentially reversed the response to 30 mM K(+) stimulation compared with 50 mM K(+) stimulation. In contrast, verapamil preferentially inhibited the response to depolarization by the higher concentration (50 mM) of K(+). 4 Gabapentin inhibited KCl-induced elevation of intracellular Ca(2+) in primary neuronal culture. 5 Hypoxic injury was induced in cerebrocortical slices by oxygen deprivation in the absence (severe injury) or presence of 3 mM glucose (mild injury). Gabapentin preferentially inhibited mild injury, while verapamil suppressed only severe injury. omega-Conotoxin GVIA (omega-CTX) and omega-agatoxin IVA (omega-Aga) were effective in both models. 6 NO synthesis was enhanced in a manner dependent on the severity of hypoxic insults. Gabapentin reversed the NO synthesis induced by mild insults, while verapamil inhibited that elicited by severe insults. omega-CTX and omega-Aga were effective in both the cases. 7 Therefore, the data suggest that gabapentin and verapamil cause activity-dependent Ca(2+) channel blocking by different mechanisms, which are associated with their cerebroprotective actions and are dependent on the severity of hypoxic insults.
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MESH Headings
- Acetates/pharmacology
- Acetates/therapeutic use
- Amines
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channel Blockers/therapeutic use
- Calcium Channels, N-Type/biosynthesis
- Calcium Channels, N-Type/drug effects
- Calcium Channels, P-Type/biosynthesis
- Calcium Channels, P-Type/drug effects
- Calcium Channels, Q-Type/biosynthesis
- Calcium Channels, Q-Type/drug effects
- Cells, Cultured
- Cerebral Cortex/drug effects
- Cerebral Cortex/metabolism
- Cerebral Cortex/pathology
- Cyclohexanecarboxylic Acids
- Fetus
- Gabapentin
- Hypoxia, Brain/metabolism
- Hypoxia, Brain/prevention & control
- Nitric Oxide/biosynthesis
- Potassium Chloride/pharmacology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Verapamil/pharmacology
- Verapamil/therapeutic use
- gamma-Aminobutyric Acid
- omega-Agatoxin IVA/pharmacology
- omega-Conotoxin GVIA/pharmacology
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Affiliation(s)
- Michiko Oka
- Department of Biochemical Pharmacology, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Yoshinori Itoh
- Department of Hospital Pharmacy, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Miyuki Wada
- Department of Biochemical Pharmacology, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Akira Yamamoto
- Department of Biopharmaceutics, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
| | - Takuya Fujita
- Department of Biochemical Pharmacology, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
- Department of Biopharmaceutics, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan
- Author for correspondence:
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18
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Hainsworth AH, McNaughton NCL, Pereverzev A, Schneider T, Randall AD. Actions of sipatrigine, 202W92 and lamotrigine on R-type and T-type Ca2+ channel currents. Eur J Pharmacol 2003; 467:77-80. [PMID: 12706458 DOI: 10.1016/s0014-2999(03)01625-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Relatively little has been published on the pharmacology of R-type and T-type Ca(2+) channels. Here, whole-cell Ca(2+) channel currents were recorded from human embryonic kidney 293 cell-lines transfected with either alpha1E subunits (R-type currents) or alpha1G or alpha1I subunits (T-type currents). R-type currents were inhibited by sipatrigine and the related compound 202W92 (R-(-)-2,4-diamino-6-(fluromethyl)-5-(2,3,5-trichlorophenyl)pyrimidine) with IC(50) 10 and 56 microM, respectively. A therapeutic concentration of lamotrigine (10 microM) inhibited R-type currents (30%) but was without effect on alpha1I-mediated T-type currents. Lamotrigine was also a weak inhibitor of T-type currents mediated by alpha1G subunits (<10% inhibition by 100 microM).
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Affiliation(s)
- Atticus H Hainsworth
- Pharmacology Research Group, School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK
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19
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Ramakrishnan NA, Green GE, Pasha R, Drescher MJ, Swanson GS, Perin PC, Lakhani RS, Ahsan SF, Hatfield JS, Khan KM, Drescher DG. Voltage-gated Ca2+ channel Ca(V)1.3 subunit expressed in the hair cell epithelium of the sacculus of the trout Oncorhynchus mykiss: cloning and comparison across vertebrate classes. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 109:69-83. [PMID: 12531517 DOI: 10.1016/s0169-328x(02)00522-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Full-length sequence (>6.5 kb) has been determined for the Ca(V)1.3 pore-forming subunit of the voltage-gated Ca(2+) channel from the saccular hair cells of the rainbow trout (Oncorhynchus mykiss). Primary structure was obtained from overlapping PCR and cloned fragments, amplified by primers based on teleost, avian, and mammalian sources. Trout saccular Ca(V)1.3 was localized to hair cells, as evidenced by its isolation from an epithelial layer in which the hair cell is the only intact cell type. The predicted amino acid sequence of the trout hair cell Ca(V)1.3 is approximately 70% identical to the sequences of avian and mammalian Ca(V)1.3 subunits and shows L-type characteristics. The trout hair cell Ca(V)1.3 expresses a 26-aa insert in the I-II cytoplasmic loop (exon 9a) and a 10-aa insert in the IVS2-IVS3 cytoplasmic loop (exon 30a), neither of which is appreciably represented in trout brain. The exon 9a insert also occurs in hair cell organs of chick and rat, and appears as an exon in human genomic Ca(V)1.3 sequence (but not in the Ca(V)1.3 coding sequence expressed in human brain or pancreas). The exon 30a insert, although expressed in hair cells of chick as well as trout, does not appear in comparable rat or human tissues. Further, the IIIS2 region shows a splice choice (exon 22a) that is associated with the hair cell organs of trout, chick, and rat, but is not found in human genomic sequence. The elucidation of the primary structure of the voltage-gated Ca(2+) channel Ca(V)1.3 subunit from hair cells of the teleost, representing the lowest of the vertebrate classes, suggests a generality of sensory mechanism for Ca(V)1.3 across hair cell systems. In particular, the exon 9a insert of this channel appears to be the molecular feature most consistently associated with hair cells from fish to mammal, consonant with the hypothesis that the latter region may be a signature for the hair cell.
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Affiliation(s)
- Neeliyath A Ramakrishnan
- Laboratory of Bio-otology, Department of Otolaryngology, Wayne State University School of Medicine, 259 Lande Medical Research Building, 540 East Canfield Avenue, Detroit, MI 48201, USA
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20
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Oka M, Itoh Y, Fujita T. Halothane attenuates the cerebroprotective action of several Na+ and Ca2+ channel blockers via reversal of their ion channel blockade. Eur J Pharmacol 2002; 452:175-81. [PMID: 12354567 DOI: 10.1016/s0014-2999(02)02298-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
We have previously shown the involvement of Na(+) channel as well as N-type and P/Q-type Ca(2+) channels in the oxygen and glucose deprivation-induced injury in rat cerebrocortical slices. In the present study, we investigated the influence of halothane on the cerebroprotective effects of a variety of Na(+) and Ca(2+) channel blockers in rat cerebrocortical slices. The hypoxic injury was attenuated by Na(+) channel blockers including tetrodotoxin, lidocaine and dibucaine, and Ca(2+) channel blockers, such as verapamil, omega-agatoxin IVA and omega-conotoxin GVIA. Halothane abolished the protective effects of lidocaine, dibucaine and verapamil, all of which block the respective cation channels in a voltage-dependent manner, without affecting the actions of tetrodotoxin, omega-agatoxin IVA and omega-conotoxin GVIA, which reveal voltage-independent blockade. On the other hand, the nitric oxide synthesis estimated from the extracellular cyclic GMP formation was elevated during exposure to hypoxia. All channel blockers tested here attenuated hypoxia-evoked nitric oxide synthesis. Halothane blocked almost completely these actions of lidocaine and verapamil. Moreover, the Na(+) and Ca(2+) channel blockade by these compounds, as determined by veratridine- and KCl-stimulated nitric oxide synthesis, respectively, was also reversed by halothane. These findings suggest that an anesthetic agent halothane reversed the Na(+) and Ca(2+) channel blockade of several voltage-dependent ion channel blockers, leading to the attenuation of their cerebroprotective actions. Therefore, the influence of halothane anesthesia should be taken into consideration for the evaluation of neuroprotective action of Na(+) and Ca(2+) channel blockers.
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Affiliation(s)
- Michiko Oka
- Department of Biochemical Pharmacology, Kyoto Pharmaceutical University, Misasagi, Kyoto Yamashina 607-8414, Japan
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21
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Gage MJ, Rane SG, Hockerman GH, Smith TJ. The virally encoded fungal toxin KP4 specifically blocks L-type voltage-gated calcium channels. Mol Pharmacol 2002; 61:936-44. [PMID: 11901234 DOI: 10.1124/mol.61.4.936] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
KP4 is a virally encoded fungal toxin secreted by the P4 killer strain of Ustilago maydis. Previous studies demonstrated that this toxin inhibits growth of the target fungal cells by blocking calcium uptake rather than forming channels, as had been suggested previously. Unexpectedly, this toxin was also shown to inhibit voltage-gated calcium channel activity in mammalian cells. We used whole-cell patch-clamp techniques to further characterize this activity against mammalian cells. KP4 is shown to specifically block L-type calcium channels with weak voltage dependence to the block. Because KP4 activity is abrogated by calcium, KP4 probably binds competitively with calcium to the channel exterior. Finally, it is shown that chemical reagents that modify lysine residues reduce KP4 activity in both patch-clamp experiments on mammalian cells and in fungal killing assays. Because the only lysine residue is K42, this residue seems to be crucial for both mammalian and fungal channel activity. Our results defining the type of mammalian channel affected by this fungal toxin further support our contention that KP4 inhibits fungal growth by blocking transmembrane calcium flux through fungal calcium channels, and imply a high degree of structural homology between these fungal and mammalian calcium channels.
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Affiliation(s)
- Matthew J Gage
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA
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22
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Gomora JC, Daud AN, Weiergräber M, Perez-Reyes E. Block of Cloned Human T-Type Calcium Channels by Succinimide Antiepileptic Drugs. Mol Pharmacol 2001. [DOI: 10.1124/mol.60.5.1121] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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23
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Hofmann F, Lacinová L, Klugbauer N. Voltage-dependent calcium channels: from structure to function. Rev Physiol Biochem Pharmacol 1999; 139:33-87. [PMID: 10453692 DOI: 10.1007/bfb0033648] [Citation(s) in RCA: 247] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- F Hofmann
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Germany
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24
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Triggle DJ. The pharmacology of ion channels: with particular reference to voltage-gated Ca2+ channels. Eur J Pharmacol 1999; 375:311-25. [PMID: 10443585 DOI: 10.1016/s0014-2999(99)00329-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ion channels are molecular machines that serve as principal integrating and regulatory devices for the control of cellular excitability. They are also major targets for drug action. The basic aspects of ion channel structure and pharmacological control are reviewed and illustrated with specific reference to a major class of therapeutic agents and molecular tools--the clinically available Ca2+ channel antagonists.
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25
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Dobrev D, Milde AS, Andreas K, Ravens U. The effects of verapamil and diltiazem on N-, P- and Q-type calcium channels mediating dopamine release in rat striatum. Br J Pharmacol 1999; 127:576-82. [PMID: 10385261 PMCID: PMC1566043 DOI: 10.1038/sj.bjp.0702574] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The putative inhibitory effects of verapamil and diltiazem on neuronal non-L-type Ca2+ channels were studied by investigating their effects on either K+- or veratridine-evoked [3H]-dopamine ([3H]-DA) release in rat striatal slices. Involvement of N-, P- and Q-type channels was identified by sensitivity of [3H]-DA release to omega-conotoxin GVIA (omega-CTx-GVIA), omega-agatoxin IVA (omega-Aga-IVA) and omega-conotoxin MVIIC (omega-CTx-MVIIC), respectively. 2. KCl (50 mM)-evoked [3H]-DA release was abolished in the absence of Ca2+, and was insensitive to dihydropyridines (up to 30 microM). It was significantly blocked by omega-CTx-GVIA (1 microM), omega-Aga-IVA (30 nM) and was confirmed to be abolished by omega-CTx-MVIIC (3 microM), indicating involvement of N-, P- and Q-type channel subtypes. 3. Verapamil and diltiazem inhibited K+-evoked [3H]-DA release in a concentration-dependent manner. The inhibitory effects of verapamil or diltiazem (each 30 microM) were fully additive to the effect of omega-CTx-GVIA (1 microM), whereas co-application with omega-Aga-IVA (30 nM) produced similar effects to those of omega-Aga-IVA alone. 4. As shown previously, veratridine-evoked [3H]-DA release in Ca2+ containing medium exclusively involves Q-type Ca2+ channels. Here, diltiazem (30 microM) did not inhibit veratridine-evoked [3H]-DA release, whereas verapamil (30 microM) partially inhibited it, indicating possible involvement of Q-type channels in verapamil-induced inhibition. However, verapamil (30 microM) inhibited this release even in the absence of extracellular Ca2+, suggesting that Na+ rather than Q-type Ca2+ channels are involved. 5. Taken together, our results suggest that verapamil can block P- and at higher concentrations possibly N- and Q-type Ca2+ channels linked to [3H]-DA release, whereas diltiazem appears to block P-type Ca2+ channels only.
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Affiliation(s)
- D Dobrev
- Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Technology, Dresden, Germany.
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26
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Motoike HK, Bodi I, Nakayama H, Schwartz A, Varadi G. A region in IVS5 of the human cardiac L-type calcium channel is required for the use-dependent block by phenylalkylamines and benzothiazepines. J Biol Chem 1999; 274:9409-20. [PMID: 10092621 DOI: 10.1074/jbc.274.14.9409] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in motif IVS5 and IVS6 of the human cardiac calcium channel were made using homologous residues from the rat brain sodium channel 2a. [3H]PN200-110 and allosteric binding assays revealed that the dihydropyridine and benzothiazepine receptor sites maintained normal coupling in the chimeric mutant channels. Whole cell voltage clamp recording from Xenopus oocytes showed a dramatically slowed inactivation and a complete loss of use-dependent block for mutations in the cytoplasmic connecting link to IVS5 (HHT-5371) and in IVS5 transmembrane segment (HHT-5411) with both diltiazem and verapamil. However, the use-dependent block by isradipine was retained by these two mutants. For mutants HHT-5411 and HHT-5371, the residual current appeared associated with a loss of voltage dependence in the rate of inactivation indicating a destabilization of the inactivated state. Furthermore, both HHT-5371 and -5411 recovered from inactivation significantly faster after drug block than that of the wild type channel. Our data demonstrate that accelerated recovery of HHT-5371 and HHT-5411 decreased accumulation of these channels in inactivation during pulse trains and suggest a close link between inactivation gating of the channel and use-dependent block by phenylalkylamines and benzothiazepines and provide evidence of a role for the transmembrane and cytoplasmic regions of IVS5 in the use-dependent block by diltiazem and verapamil.
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Affiliation(s)
- H K Motoike
- Institute of Molecular Pharmacology and Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0828, USA
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27
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Berjukow S, Gapp F, Aczél S, Sinnegger MJ, Mitterdorfer J, Glossmann H, Hering S. Sequence differences between alpha1C and alpha1S Ca2+ channel subunits reveal structural determinants of a guarded and modulated benzothiazepine receptor. J Biol Chem 1999; 274:6154-60. [PMID: 10037699 DOI: 10.1074/jbc.274.10.6154] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular basis of the Ca2+ channel block by (+)-cis-diltiazem was studied in class A/L-type chimeras and mutant alpha1C-a Ca2+ channels. Chimeras consisted of either rabbit heart (alpha1C-a) or carp skeletal muscle (alpha1S) sequence in transmembrane segments IIIS6, IVS6, and adjacent S5-S6 linkers. Only chimeras containing sequences from alpha1C-a were efficiently blocked by (+)-cis-diltiazem, whereas the phenylalkylamine (-)-gallopamil efficiently blocked both constructs. Carp skeletal muscle and rabbit heart Ca2+ channel alpha1 subunits differ with respect to two nonconserved amino acids in segments IVS6. Transfer of a single leucine (Leu1383, located at the extracellular mouth of the pore) from IVS6 alpha1C-a to IVS6 of alpha1S significantly increased the (+)-cis-diltiazem sensitivity of the corresponding mutant L1383I. An analysis of the role of the two heterologous amino acids in a L-type alpha1 subunit revealed that corresponding amino acids in position 1487 (outer channel mouth) determine recovery of resting Ca2+ channels from block by (+)-cis-diltiazem. The second heterologous amino acid in position 1504 of segment IVS6 (inner channel mouth) was identified as crucial inactivation determinant of L-type Ca2+ channels. This residue simultaneously modulates drug binding during membrane depolarization. Our study provides the first evidence for a guarded and modulated benzothiazepine receptor on L-type channels.
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Affiliation(s)
- S Berjukow
- Institut für Biochemische Pharmakologie, Peter Mayr Strasse 1, A-6020 Innsbruck, Austria
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Hering S, Berjukow S, Aczél S, Timin EN. Ca2+ channel block and inactivation: common molecular determinants. Trends Pharmacol Sci 1998; 19:439-43. [PMID: 9850606 DOI: 10.1016/s0165-6147(98)01258-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- S Hering
- Institut für Biochemische Pharmakologie, Universität Innsbruck, Austria
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