1
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Zhang Y, Shaabani S, Vowinkel K, Trombetta-Lima M, Sabogal-Guáqueta AM, Chen T, Hoekstra J, Lembeck J, Schmidt M, Decher N, Dömling A, Dolga AM. Novel SK channel positive modulators prevent ferroptosis and excitotoxicity in neuronal cells. Biomed Pharmacother 2024; 171:116163. [PMID: 38242037 DOI: 10.1016/j.biopha.2024.116163] [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: 10/23/2023] [Revised: 01/07/2024] [Accepted: 01/11/2024] [Indexed: 01/21/2024] Open
Abstract
Small conductance calcium-activated potassium (SK) channel activity has been proposed to play a role in the pathology of several neurological diseases. Besides regulating plasma membrane excitability, SK channel activation provides neuroprotection against ferroptotic cell death by reducing mitochondrial Ca2+ uptake and reactive oxygen species (ROS). In this study, we employed a multifaceted approach, integrating structure-based and computational techniques, to strategically design and synthesize an innovative class of potent small-molecule SK2 channel modifiers through highly efficient multicomponent reactions (MCRs). The compounds' neuroprotective activity was compared with the well-studied SK positive modulator, CyPPA. Pharmacological SK channel activation by selected compounds confers neuroprotection against ferroptosis at low nanomolar ranges compared to CyPPA, that mediates protection at micromolar concentrations, as shown by an MTT assay, real-time cell impedance measurements and propidium iodide staining (PI). These novel compounds suppress increased mitochondrial ROS and Ca2+ level induced by ferroptosis inducer RSL3. Moreover, axonal degeneration was rescued by these novel SK channel activators in primary mouse neurons and they attenuated glutamate-induced neuronal excitability, as shown via microelectrode array. Meanwhile, functional afterhyperpolarization of the novel SK2 channel modulators was validated by electrophysiological measurements showing more current change induced by the novel modulators than the reference compound, CyPPA. These data support the notion that SK2 channel activation can represent a therapeutic target for brain diseases in which ferroptosis and excitotoxicity contribute to the pathology.
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Affiliation(s)
- Yuequ Zhang
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Shabnam Shaabani
- Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Kirsty Vowinkel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
| | - Marina Trombetta-Lima
- Department of Pharmaceutical Technologies and Biopharmacy, Research Institute of Pharmacy, University of Groningen, the Netherlands
| | | | - Tingting Chen
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Jan Hoekstra
- Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Jan Lembeck
- Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Martina Schmidt
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, 35037 Marburg, Germany
| | - Alexander Dömling
- Department of Drug Design, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands.
| | - Amalia M Dolga
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, the Netherlands.
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2
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Wolpe AG, Luse MA, Baryiames C, Schug WJ, Wolpe JB, Johnstone SR, Dunaway LS, Juśkiewicz ZJ, Loeb SA, Askew Page HR, Chen YL, Sabapathy V, Pavelec CM, Wakefield B, Cifuentes-Pagano E, Artamonov MV, Somlyo AV, Straub AC, Sharma R, Beier F, Barrett EJ, Leitinger N, Pagano PJ, Sonkusare SK, Redemann S, Columbus L, Penuela S, Isakson BE. Pannexin-3 stabilizes the transcription factor Bcl6 in a channel-independent manner to protect against vascular oxidative stress. Sci Signal 2024; 17:eadg2622. [PMID: 38289985 DOI: 10.1126/scisignal.adg2622] [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: 12/12/2022] [Accepted: 01/05/2024] [Indexed: 02/01/2024]
Abstract
Targeted degradation regulates the activity of the transcriptional repressor Bcl6 and its ability to suppress oxidative stress and inflammation. Here, we report that abundance of endothelial Bcl6 is determined by its interaction with Golgi-localized pannexin 3 (Panx3) and that Bcl6 transcriptional activity protects against vascular oxidative stress. Consistent with data from obese, hypertensive humans, mice with an endothelial cell-specific deficiency in Panx3 had spontaneous systemic hypertension without obvious changes in channel function, as assessed by Ca2+ handling, ATP amounts, or Golgi luminal pH. Panx3 bound to Bcl6, and its absence reduced Bcl6 protein abundance, suggesting that the interaction with Panx3 stabilized Bcl6 by preventing its degradation. Panx3 deficiency was associated with increased expression of the gene encoding the H2O2-producing enzyme Nox4, which is normally repressed by Bcl6, resulting in H2O2-induced oxidative damage in the vasculature. Catalase rescued impaired vasodilation in mice lacking endothelial Panx3. Administration of a newly developed peptide to inhibit the Panx3-Bcl6 interaction recapitulated the increase in Nox4 expression and in blood pressure seen in mice with endothelial Panx3 deficiency. Panx3-Bcl6-Nox4 dysregulation occurred in obesity-related hypertension, but not when hypertension was induced in the absence of obesity. Our findings provide insight into a channel-independent role of Panx3 wherein its interaction with Bcl6 determines vascular oxidative state, particularly under the adverse conditions of obesity.
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Affiliation(s)
- Abigail G Wolpe
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Melissa A Luse
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | | | - Wyatt J Schug
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Jacob B Wolpe
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Scott R Johnstone
- Fralin Biomedical Research Institute at Virginia Tech Carilion School of Medicine, Center for Vascular and Heart Research, Roanoke, VA 24016, USA
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24060, USA
| | - Luke S Dunaway
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Zuzanna J Juśkiewicz
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Skylar A Loeb
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Henry R Askew Page
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yen-Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Vikram Sabapathy
- Center for Immunity, Inflammation, and Regenerative Medicine (CIIR), University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Caitlin M Pavelec
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Brent Wakefield
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Eugenia Cifuentes-Pagano
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mykhaylo V Artamonov
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Avril V Somlyo
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Adam C Straub
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Rahul Sharma
- Center for Immunity, Inflammation, and Regenerative Medicine (CIIR), University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Frank Beier
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Eugene J Barrett
- Department of Medicine, Division of Endocrinology and Metabolism, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Norbert Leitinger
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Patrick J Pagano
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Stefanie Redemann
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Linda Columbus
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Silvia Penuela
- Department of Anatomy and Cell Biology, University of Western Ontario, London, ON N6A 5C1, Canada
- Department of Oncology (Division of Experimental Oncology), Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5W9, Canada
| | - Brant E Isakson
- Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
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3
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Silván Á, Kohlmeier KA, Herrik KF, Hougaard C. Gating small conductance calcium-activated potassium channels in the thalamic reticular nucleus. Synapse 2024; 78:e22283. [PMID: 37837643 DOI: 10.1002/syn.22283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 09/14/2023] [Accepted: 09/18/2023] [Indexed: 10/16/2023]
Abstract
Small conductance calcium-activated potassium (SK) channels are well-known regulators of neuronal excitability. In the thalamic hub, SK2 channels act as pacemakers of thalamic reticular neurons, which play a key role in the thalamocortical circuit. Several disease-linked genes are highly enriched in these neurons, including genes known to be associated with schizophrenia and attentional disorders, which could affect neuronal firing. The present study assessed the effect of pharmacological modulation of SK channels in the firing pattern and intrinsic properties of thalamic reticular neurons by performing whole cell patch clamp recordings in brain slices. Two SK positive allosteric modulators and one negative allosteric modulator were used: CyPPA, NS309, and NS8593, respectively. By acting on the burst afterhyperpolarization (AHP), negative modulation of SK channels resulted in increased action potential (AP) firing, increased burst duration, and decreased intervals between bursts. Conversely, both CyPPA and NS309 increased the afterburst AHP, prolonging the interburst interval, which additionally resulted in reduced AP firing in the case of NS309. Alterations in SK channel activity would be expected to alter functioning of thalamocortical circuits. Targeting SK channels could be promising in treating disorders involving thalamic reticular dysfunction such as psychiatric and neurodevelopmental disorders.
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Affiliation(s)
- Ágata Silván
- H Lundbeck A/S, Circuit Biology, Valby, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kristi Anne Kohlmeier
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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4
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Dupuy M, Gueguinou M, Potier-Cartereau M, Lézot F, Papin M, Chantôme A, Rédini F, Vandier C, Verrecchia F. SK Ca- and Kv1-type potassium channels and cancer: Promising therapeutic targets? Biochem Pharmacol 2023; 216:115774. [PMID: 37678626 DOI: 10.1016/j.bcp.2023.115774] [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: 06/28/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/09/2023]
Abstract
Ion channels are transmembrane structures that allow the passage of ions across cell membranes such as the plasma membrane or the membranes of various organelles like the nucleus, endoplasmic reticulum, Golgi apparatus or mitochondria. Aberrant expression of various ion channels has been demonstrated in several tumor cells, leading to the promotion of key functions in tumor development, such as cell proliferation, resistance to apoptosis, angiogenesis, invasion and metastasis. The link between ion channels and these key biological functions that promote tumor development has led to the classification of cancers as oncochannelopathies. Among all ion channels, the most varied and numerous, forming the largest family, are the potassium channels, with over 70 genes encoding them in humans. In this context, this review will provide a non-exhaustive overview of the role of plasma membrane potassium channels in cancer, describing 1) the nomenclature and structure of potassium channels, 2) the role of these channels in the control of biological functions that promotes tumor development such as proliferation, migration and cell death, and 3) the role of two particular classes of potassium channels, the SKCa- and Kv1- type potassium channels in cancer progression.
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Affiliation(s)
- Maryne Dupuy
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France.
| | | | | | - Frédéric Lézot
- Sorbonne University, INSERM UMR933, Hôpital Trousseau (AP-HP), Paris F-75012, France
| | - Marion Papin
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | | | - Françoise Rédini
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France
| | | | - Franck Verrecchia
- Nantes Université, Inserm UMR 1307, CNRS UMR 6075, Université d'Angers, CRCI2NA, F-44000 Nantes, France.
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5
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Orfali R, AlFaiz A, Rahman MA, Lau L, Nam YW, Zhang M. K Ca2 and K Ca3.1 Channels in the Airways: A New Therapeutic Target. Biomedicines 2023; 11:1780. [PMID: 37509419 PMCID: PMC10376499 DOI: 10.3390/biomedicines11071780] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 07/30/2023] Open
Abstract
K+ channels are involved in many critical functions in lung physiology. Recently, the family of Ca2+-activated K+ channels (KCa) has received more attention, and a massive amount of effort has been devoted to developing selective medications targeting these channels. Within the family of KCa channels, three small-conductance Ca2+-activated K+ (KCa2) channel subtypes, together with the intermediate-conductance KCa3.1 channel, are voltage-independent K+ channels, and they mediate Ca2+-induced membrane hyperpolarization. Many KCa2 channel members are involved in crucial roles in physiological and pathological systems throughout the body. In this article, different subtypes of KCa2 and KCa3.1 channels and their functions in respiratory diseases are discussed. Additionally, the pharmacology of the KCa2 and KCa3.1 channels and the link between these channels and respiratory ciliary regulations will be explained in more detail. In the future, specific modulators for small or intermediate Ca2+-activated K+ channels may offer a unique therapeutic opportunity to treat muco-obstructive lung diseases.
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Affiliation(s)
- Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Ali AlFaiz
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Liz Lau
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
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6
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Guo R, Cui M, Li X, Wu M, Xu F, Zhang Y, Wang C, Feng P, Wang J, Huo S, Luo Z, Xing R, Gu J, Shi X, Liu Y, Wang L. Design, synthesis and biological evaluation of pyrrolopyrimidine derivatives as novel and selective positive modulator of the small conductance Ca 2+-activated K + channels. Eur J Med Chem 2023; 254:115353. [PMID: 37068385 DOI: 10.1016/j.ejmech.2023.115353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/19/2023]
Abstract
The type 2 small conductance Ca2+-activated K+ channels (SK2) have been considered as one of the most promising therapeutic targets for spinocerebellar ataxias type 2 (SCA2) by playing a critical role in the control of normal purkinje cells (PCs) pacemaking. Herein, a novel series of pyrrolopyrimidine derivatives were designed and synthesized from the lead compound NS13001 as subtype-selective modulators of SK channels. Among them, the halogen-substituted compound 12b (EC50 = 0.34 ± 0.044 μM) was identified with a ∼5.4-fold higher potency on potentiating SK2-a channels at submicromolar concentrations as compared to NS13001 (EC50 = 1.83 ± 0.50 μM). Furthermore, compound 12b exhibited selectivity on SK2-a/SK3 subtype by displaying 93.33 ± 3.26% efficacies on SK2-a channels, and 84.54% ± 7.49% on SK3 channels. In addition, compound 12b demonstrated the potential to cross the blood-brain barrier (BBB) with suitable pharmacokinetic properties and low cytotoxicity. Molecular docking study also unveiled the binding interactions of compound 12b with SK2-CaM protein complex. Overall, the novel pyrrolopyrimidines provide an insightful guidance for future structural optimization of SK channel agonists.
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Affiliation(s)
- Ran Guo
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Miao Cui
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Xiaojing Li
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Mengqi Wu
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Fei Xu
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Yining Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Chun Wang
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Penglei Feng
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Jianchao Wang
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Sijia Huo
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Zijun Luo
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Ruijuan Xing
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Jianmin Gu
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Xiaowei Shi
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China.
| | - Yi Liu
- Department of Toxicology, School of Public Health, Hebei Medical University, Shijiazhuang, 050017, PR China; Hebei Province Key Laboratory of Environment and Human Health, Shijiazhuang, 050017, PR China.
| | - Lei Wang
- Department of Medicinal Chemistry, School of Pharmacy, Hebei Medical University, Shijiazhuang, 050017, PR China; Hebei Province Key Laboratory of Innovative Drug Research and Evaluation, Shijiazhuang, 050017, PR China.
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7
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Nam YW, Rahman MA, Yang G, Orfali R, Cui M, Zhang M. Loss-of-function K Ca2.2 mutations abolish channel activity. Am J Physiol Cell Physiol 2023; 324:C658-C664. [PMID: 36717104 PMCID: PMC10069973 DOI: 10.1152/ajpcell.00584.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023]
Abstract
Small-conductance Ca2+-activated potassium channels subtype 2 (KCa2.2, also called SK2) are operated exclusively by a Ca2+-calmodulin gating mechanism. Heterozygous genetic mutations of KCa2.2 channels have been associated with autosomal dominant neurodevelopmental disorders including cerebellar ataxia and tremor in humans and rodents. Taking advantage of these pathogenic mutations, we performed structure-function studies of the rat KCa2.2 channel. No measurable current was detected from HEK293 cells heterologously expressing these pathogenic KCa2.2 mutants. When coexpressed with the KCa2.2_WT channel, mutations of the pore-lining amino acid residues (I360M, Y362C, G363S, and I389V) and two proline substitutions (L174P and L433P) dominant negatively suppressed and completely abolished the activity of the coexpressed KCa2.2_WT channel. Coexpression of the KCa2.2_I289N and the KCa2.2_WT channels reduced the apparent Ca2+ sensitivity compared with the KCa2.2_WT channel, which was rescued by a KCa2.2 positive modulator.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California, United States
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California, United States
| | - Grace Yang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California, United States
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California, United States
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, Massachusetts, United States
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California, United States
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8
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Nam YW, Downey M, Rahman MA, Cui M, Zhang M. Channelopathy of small- and intermediate-conductance Ca 2+-activated K + channels. Acta Pharmacol Sin 2023; 44:259-267. [PMID: 35715699 PMCID: PMC9889811 DOI: 10.1038/s41401-022-00935-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 05/31/2022] [Indexed: 02/04/2023] Open
Abstract
Small- and intermediate-conductance Ca2+-activated K+ (KCa2.x/KCa3.1 also called SK/IK) channels are gated exclusively by intracellular Ca2+. The Ca2+ binding protein calmodulin confers sub-micromolar Ca2+ sensitivity to the channel-calmodulin complex. The calmodulin C-lobe is constitutively associated with the proximal C-terminus of the channel. Interactions between calmodulin N-lobe and the channel S4-S5 linker are Ca2+-dependent, which subsequently trigger conformational changes in the channel pore and open the gate. KCNN genes encode four subtypes, including KCNN1 for KCa2.1 (SK1), KCNN2 for KCa2.2 (SK2), KCNN3 for KCa2.3 (SK3), and KCNN4 for KCa3.1 (IK). The three KCa2.x channel subtypes are expressed in the central nervous system and the heart. The KCa3.1 subtype is expressed in the erythrocytes and the lymphocytes, among other peripheral tissues. The impact of dysfunctional KCa2.x/KCa3.1 channels on human health has not been well documented. Human loss-of-function KCa2.2 mutations have been linked with neurodevelopmental disorders. Human gain-of-function mutations that increase the apparent Ca2+ sensitivity of KCa2.3 and KCa3.1 channels have been associated with Zimmermann-Laband syndrome and hereditary xerocytosis, respectively. This review article discusses the physiological significance of KCa2.x/KCa3.1 channels, the pathophysiology of the diseases linked with KCa2.x/KCa3.1 mutations, the structure-function relationship of the mutant KCa2.x/KCa3.1 channels, and potential pharmacological therapeutics for the KCa2.x/KCa3.1 channelopathy.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Myles Downey
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA, 02115, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA.
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9
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Mack ML, Huang W, Chang SL. Involvement of TRPM7 in Alcohol-Induced Damage of the Blood-Brain Barrier in the Presence of HIV Viral Proteins. Int J Mol Sci 2023; 24:1910. [PMID: 36768230 PMCID: PMC9916124 DOI: 10.3390/ijms24031910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/22/2022] [Accepted: 01/14/2023] [Indexed: 01/21/2023] Open
Abstract
Ethanol (EtOH) exerts its effects through various protein targets, including transient receptor potential melastatin 7 (TRPM7) channels, which play an essential role in cellular homeostasis. We demonstrated that TRPM7 is expressed in rat brain microvascular endothelial cells (rBMVECs), the major cellular component of the blood-brain barrier (BBB). Heavy alcohol drinking is often associated with HIV infection, however mechanisms underlying alcohol-induced BBB damage and HIV proteins, are not fully understood. We utilized the HIV-1 transgenic (HIV-1Tg) rat to mimic HIV-1 patients on combination anti-retroviral therapy (cART) and demonstrated TRPM7 expression in rBMVECs wass lower in adolescent HIV-1Tg rats compared to control animals, however control and HIV-1Tg rats expressed similar levels at 9 weeks, indicating persistent presence of HIV-1 proteins delayed TRPM7 expression. Binge exposure to EtOH (binge EtOH) decreased TRPM7 expression in control rBMVECs in a concentration-dependent manner, and abolished TRPM7 expression in HIV-1Tg rats. In human BMVECs (hBMVECs), TRPM7 expression was downregulated after treatment with EtOH, HIV-1 proteins, and in combination. Next, we constructed in vitro BBB models using BMVECs and found TRPM7 antagonists enhanced EtOH-mediated BBB integrity changes. Our study demonstrated alcohol decreased TRPM7 expression, whereby TRPM7 could be involved in the mechanisms underlying BBB alcohol-induced damage in HIV-1 patients on cART.
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Affiliation(s)
- Michelle L. Mack
- Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ 07079, USA
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA
| | - Wenfei Huang
- Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ 07079, USA
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA
| | - Sulie L. Chang
- Institute of NeuroImmune Pharmacology, Seton Hall University, South Orange, NJ 07079, USA
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA
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10
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Zahra A, Liu R, Han W, Meng H, Wang Q, Wang Y, Campbell SL, Wu J. K Ca-Related Neurological Disorders: Phenotypic Spectrum and Therapeutic Indications. Curr Neuropharmacol 2023; 21:1504-1518. [PMID: 36503451 PMCID: PMC10472807 DOI: 10.2174/1570159x21666221208091805] [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: 04/21/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 12/14/2022] Open
Abstract
Although potassium channelopathies have been linked to a wide range of neurological conditions, the underlying pathogenic mechanism is not always clear, and a systematic summary of clinical manifestation is absent. Several neurological disorders have been associated with alterations of calcium-activated potassium channels (KCa channels), such as loss- or gain-of-function mutations, post-transcriptional modification, etc. Here, we outlined the current understanding of the molecular and cellular properties of three subtypes of KCa channels, including big conductance KCa channels (BK), small conductance KCa channels (SK), and the intermediate conductance KCa channels (IK). Next, we comprehensively reviewed the loss- or gain-of-function mutations of each KCa channel and described the corresponding mutation sites in specific diseases to broaden the phenotypic-genotypic spectrum of KCa-related neurological disorders. Moreover, we reviewed the current pharmaceutical strategies targeting KCa channels in KCa-related neurological disorders to provide new directions for drug discovery in anti-seizure medication.
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Affiliation(s)
- Aqeela Zahra
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Department of Zoology, University of Sialkot, Sialkot 51310, Pakistan
| | - Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - Wenzhe Han
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Meng
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - YunFu Wang
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Susan L. Campbell
- Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Jianping Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
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11
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Spike Afterhyperpolarizations Govern Persistent Firing Dynamics in Rat Neocortical and Hippocampal Pyramidal Cells. J Neurosci 2022; 42:7690-7706. [PMID: 36414011 PMCID: PMC9581562 DOI: 10.1523/jneurosci.0570-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/10/2022] [Accepted: 08/28/2022] [Indexed: 12/14/2022] Open
Abstract
Persistent firing is commonly reported in both cortical and subcortical neurons under a variety of behavioral conditions. Yet the mechanisms responsible for persistent activity are only partially resolved with support for both intrinsic and synaptic circuit-based mechanisms. Little also is known about physiological factors that enable epochs of persistent firing to continue beyond brief pauses and then spontaneously terminate. In the present study, we used intracellular recordings in rat (both sexes) neocortical and hippocampal brain slices to assess the ionic mechanisms underlying persistent firing dynamics. Previously, we showed that blockade of ether-á-go-go-related gene (ERG) potassium channels abolished intrinsic persistent firing in the presence of low concentrations of muscarinic receptor agonists and following optogenetic activation of cholinergic axons. Here we show the slow dynamics of ERG conductance changes allows persistent firing to outlast the triggering stimulus and even to initiate discharges following ∼7 s poststimulus firing pauses. We find that persistent firing dynamics is regulated by the interaction between ERG conductance and spike afterhyperpolarizations (AHPs). Increasing the amplitude of spike AHPs using either SK channel activators or a closed-loop reactive feedback system allows persistent discharges to spontaneously terminate in both neocortical neurons and hippocampal CA1 pyramidal cells. The interplay between ERG and the potassium channels that mediate spike AHPs grades the duration of persistent firing, providing a novel, generalizable mechanism to explain self-terminating persistent firing modes observed behaving animals.SIGNIFICANCE STATEMENT Many classes of neurons generate prolonged spiking responses to transient stimuli. These discharges often outlast the stimulus by seconds to minutes in some in vitro models of persistent firing. While recent work has identified key synaptic and intrinsic components that enable persistent spiking responses, less is known about mechanisms that can terminate and regulate the dynamics of these responses. The present study identified the spike afterhyperpolarizations as a potent mechanism that regulates the duration of persistent firing. We found that amplifying spike afterpotentials converted bistable persistent firing into self-terminating discharges. Varying the spike AHP amplitude grades the duration of persistent discharges, generating in vitro responses that mimic firing modes associated with neurons associated with short-term memory function.
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12
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Nam YW, Pala R, El-Sayed NS, Larin-Henriquez D, Amirrad F, Yang G, Rahman MA, Orfali R, Downey M, Parang K, Nauli SM, Zhang M. Subtype-Selective Positive Modulation of K Ca2.3 Channels Increases Cilia Length. ACS Chem Biol 2022; 17:2344-2354. [PMID: 35947779 PMCID: PMC9396613 DOI: 10.1021/acschembio.2c00469] [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: 11/30/2022]
Abstract
![]()
Small-conductance Ca2+-activated potassium
(KCa2.x) channels are gated exclusively by intracellular
Ca2+. The activation of KCa2.3 channels induces
hyperpolarization,
which augments Ca2+ signaling in endothelial cells. Cilia
are specialized Ca2+ signaling compartments. Here, we identified
compound 4 that potentiates human KCa2.3 channels
selectively. The subtype selectivity of compound 4 for
human KCa2.3 over rat KCa2.2a channels relies
on an isoleucine residue in the HA/HB helices. Positive modulation
of KCa2.3 channels by compound 4 increased
flow-induced Ca2+ signaling and cilia length, while negative
modulation by AP14145 reduced flow-induced Ca2+ signaling
and cilia length. These findings were corroborated by the increased
cilia length due to the expression of Ca2+-hypersensitive
KCa2.3_G351D mutant channels and the reduced cilia length
resulting from the expression of Ca2+-hyposensitive KCa2.3_I438N channels. Collectively, we were able to associate
functions of KCa2.3 channels and cilia, two crucial components
in the flow-induced Ca2+ signaling of endothelial cells,
with potential implications in vasodilation and ciliopathic hypertension.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Rajasekharreddy Pala
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Naglaa Salem El-Sayed
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Denisse Larin-Henriquez
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Farideh Amirrad
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Grace Yang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Myles Downey
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Keykavous Parang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Surya M Nauli
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
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13
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Nam YW, Cui M, Salem El-Sayed N, Orfali R, Nguyen M, Yang G, Rahman MA, Lee J, Zhang M. Subtype-selective positive modulation of K Ca 2 channels depends on the HA/HB helices. Br J Pharmacol 2022; 179:460-472. [PMID: 34458981 PMCID: PMC8799485 DOI: 10.1111/bph.15676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/29/2021] [Accepted: 07/29/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND AND PURPOSE In the activated state of small-conductance Ca2+ -activated potassium (KCa 2) channels, calmodulin interacts with the HA/HB helices and the S4-S5 linker. CyPPA potentiates KCa 2.2a and KCa 2.3 channel activity but not the KCa 2.1 and KCa 3.1 subtypes. EXPERIMENTAL APPROACH Site-directed mutagenesis, patch-clamp recordings and in silico modelling were utilised to explore the structural determinants for the subtype-selective modulation of KCa 2 channels by CyPPA. KEY RESULTS Mutating residues in the HA (V420) and HB (K467) helices of KCa 2.2a channels to their equivalent residues in KCa 3.1 channels diminished the potency of CyPPA. CyPPA elicited prominent responses on mutant KCa 3.1 channels with an arginine residue in the HB helix substituted for its equivalent lysine residue in the KCa 2.2a channels (R355K). KCa 2.1 channels harbouring a three-amino-acid insertion upstream of the cognate R438 residues in the HB helix showed no response to CyPPA, whereas the deletion mutant (KCa 2.1_ΔA434/Q435/K436) became sensitive to CyPPA. In molecular dynamics simulations, CyPPA docked between calmodulin C-lobe and the HA/HB helices widens the cytoplasmic gate of KCa 2.2a channels. CONCLUSION AND IMPLICATIONS Selectivity of CyPPA among KCa 2 and KCa 3.1 channel subtypes relies on the HA/HB helices.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, Massachusetts, 02115, USA
| | - Naglaa Salem El-Sayed
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Misa Nguyen
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Grace Yang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Judy Lee
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California 92618, USA
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14
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El-Sayed NS, Nam YW, Egorova PA, Nguyen HM, Orfali R, Rahman MA, Yang G, Wulff H, Bezprozvanny I, Parang K, Zhang M. Structure-Activity Relationship Study of Subtype-Selective Positive Modulators of K Ca2 Channels. J Med Chem 2022; 65:303-322. [PMID: 34962403 PMCID: PMC8758555 DOI: 10.1021/acs.jmedchem.1c01473] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A series of modified N-cyclohexyl-2-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylpyrimidin-4-amine (CyPPA) analogues were synthesized by replacing the cyclohexane moiety with different 4-substituted cyclohexane rings, tyrosine analogues, or mono- and dihalophenyl rings and were subsequently studied for their potentiation of KCa2 channel activity. Among the N-benzene-N-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine derivatives, halogen decoration at positions 2 and 5 of benzene-substituted 4-pyrimidineamine in compound 2q conferred a ∼10-fold higher potency, while halogen substitution at positions 3 and 4 of benzene-substituted 4-pyrimidineamine in compound 2o conferred a ∼7-fold higher potency on potentiating KCa2.2a channels, compared to that of the parent template CyPPA. Both compounds retained the KCa2.2a/KCa2.3 subtype selectivity. Based on the initial evaluation, compounds 2o and 2q were selected for testing in an electrophysiological model of spinocerebellar ataxia type 2 (SCA2). Both compounds were able to normalize the abnormal firing of Purkinje cells in cerebellar slices from SCA2 mice, suggesting the potential therapeutic usefulness of these compounds for treating symptoms of ataxia.
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Affiliation(s)
- Naglaa Salem El-Sayed
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya Ulitsa, 29, St. Petersburg, 195251, Russia
| | - Hai Minh Nguyen
- Department of Pharmacology, School of Medicine, University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Grace Yang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Ilya Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya Ulitsa, 29, St. Petersburg, 195251, Russia
- Department of Physiology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA
| | - Keykavous Parang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, 9401 Jeronimo Road, Irvine, CA 92618, USA
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15
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Wrzosek A, Gałecka S, Żochowska M, Olszewska A, Kulawiak B. Alternative Targets for Modulators of Mitochondrial Potassium Channels. Molecules 2022; 27:299. [PMID: 35011530 PMCID: PMC8746388 DOI: 10.3390/molecules27010299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial potassium channels control potassium influx into the mitochondrial matrix and thus regulate mitochondrial membrane potential, volume, respiration, and synthesis of reactive oxygen species (ROS). It has been found that pharmacological activation of mitochondrial potassium channels during ischemia/reperfusion (I/R) injury activates cytoprotective mechanisms resulting in increased cell survival. In cancer cells, the inhibition of these channels leads to increased cell death. Therefore, mitochondrial potassium channels are intriguing targets for the development of new pharmacological strategies. In most cases, however, the substances that modulate the mitochondrial potassium channels have a few alternative targets in the cell. This may result in unexpected or unwanted effects induced by these compounds. In our review, we briefly present the various classes of mitochondrial potassium (mitoK) channels and describe the chemical compounds that modulate their activity. We also describe examples of the multidirectional activity of the activators and inhibitors of mitochondrial potassium channels.
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Affiliation(s)
- Antoni Wrzosek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Shur Gałecka
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Monika Żochowska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Anna Olszewska
- Department of Histology, Medical University of Gdansk, 1a Debinki, 80-211 Gdansk, Poland;
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
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16
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Bredehöft J, Dolga AM, Honrath B, Wache S, Mazurek S, Culmsee C, Schoemaker RG, Gerstberger R, Roth J, Rummel C. SK-Channel Activation Alters Peripheral Metabolic Pathways in Mice, but Not Lipopolysaccharide-Induced Fever or Inflammation. J Inflamm Res 2022; 15:509-531. [PMID: 35115803 PMCID: PMC8800008 DOI: 10.2147/jir.s338812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/25/2021] [Indexed: 12/19/2022] Open
Abstract
Purpose Previously, we have shown that CyPPA (cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine), a pharmacological small-conductance calcium-activated potassium (SK)–channel positive modulator, antagonizes lipopolysaccharide (LPS)-induced cytokine expression in microglial cells. Here, we aimed to test its therapeutic potential for brain-controlled sickness symptoms, brain inflammatory response during LPS-induced systemic inflammation, and peripheral metabolic pathways in mice. Methods Mice were pretreated with CyPPA (15 mg/kg IP) 24 hours before and simultaneously with LPS stimulation (2.5 mg/kg IP), and the sickness response was recorded by a telemetric system for 24 hours. A second cohort of mice were euthanized 2 hours after CyPPA or solvent treatment to assess underlying CyPPA-induced mechanisms. Brain, blood, and liver samples were analyzed for inflammatory mediators or nucleotide concentrations using immunohistochemistry, real-time PCR and Western blot, or HPLC. Moreover, we investigated CyPPA-induced changes of UCP1 expression in brown adipose tissue (BAT)–explant cultures. Results CyPPA treatment did not affect LPS-induced fever, anorexia, adipsia, or expression profiles of inflammatory mediators in the hypothalamus or plasma or microglial reactivity to LPS (CD11b staining and CD68 mRNA expression). However, CyPPA alone induced a rise in core body temperature linked to heat production via altered metabolic pathways like reduced levels of adenosine, increased protein content, and increased UCP1 expression in BAT-explant cultures, but no alteration in ATP/ADP concentrations in the liver. CyPPA treatment was accompanied by altered pathways, including NFκB signaling, in the hypothalamus and cortex, while circulating cytokines remained unaltered. Conclusion Overall, while CyPPA has promise as a treatment strategy, in particular according to results from in vitro experiments, we did not reveal anti-inflammatory effects during severe LPS-induced systemic inflammation. Interestingly, we found that CyPPA alters metabolic pathways inducing short hyperthermia, most likely due to increased energy turnover in the liver and heat production in BAT.
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Affiliation(s)
- Janne Bredehöft
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Amalia M Dolga
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, Netherlands
| | - Birgit Honrath
- Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, Netherlands
- Institute of Pharmacology and Clinical Pharmacy, Philipps University of Marburg, Marburg, Germany
| | - Sybille Wache
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Sybille Mazurek
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, Philipps University of Marburg, Marburg, Germany
- Center for Mind, Brain and Behavior-CMBB, Giessen and Marburg, Germany
| | - Regien G Schoemaker
- Department of Neurobiology, GELIFES, University of Groningen, Groningen, Netherlands
| | - Rüdiger Gerstberger
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
| | - Joachim Roth
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
- Center for Mind, Brain and Behavior-CMBB, Giessen and Marburg, Germany
| | - Christoph Rummel
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Giessen, Germany
- Center for Mind, Brain and Behavior-CMBB, Giessen and Marburg, Germany
- Correspondence: Christoph Rummel Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, Frankfurter Strasse 100, GiessenD-35392, GermanyTel +49 641 99 38155Fax +49 641 99 38159 Email
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17
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Bassett JJ, Robitaille M, Peters AA, Bong AHL, Taing MW, Wood IA, Sadras F, Roberts-Thomson SJ, Monteith GR. ORAI1 regulates sustained cytosolic free calcium fluctuations during breast cancer cell apoptosis and apoptotic resistance via a STIM1 independent pathway. FASEB J 2021; 36:e22108. [PMID: 34939697 DOI: 10.1096/fj.202002031rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/24/2021] [Accepted: 12/06/2021] [Indexed: 11/11/2022]
Abstract
Excessive rapid increases in cytosolic free Ca2+ have a clear association with the induction of cancer cell death. Whereas, characterizing the Ca2+ signaling events that occur during the progression of the apoptotic cascade over a period of hours or days, has not yet been possible. Now using genetically encoded Ca2+ indicators complemented with automated epifluorescence microscopy we have shown that staurosporine-induced apoptosis in MDA-MB-231 breast cancer cells was associated with delayed development of cytosolic free Ca2+ fluctuations, which were then maintained for 24 h. These cytosolic free Ca2+ fluctuations were dependent on the Ca2+ channel ORAI1. Silencing of ORAI1, but not its canonical activators STIM1 and STIM2, promoted apoptosis in this model. The pathway for this regulation implicates a mechanism previously associated with the migration of cancer cells involving ORAI1, the chaperone protein SigmaR1, and Ca2+ -activated K+ channels.
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Affiliation(s)
- John J Bassett
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Mélanie Robitaille
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Amelia A Peters
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Alice H L Bong
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Meng-Wong Taing
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | - Ian A Wood
- School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, Australia
| | - Francisco Sadras
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
| | | | - Gregory R Monteith
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
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18
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Tiffner A, Hopl V, Schober R, Sallinger M, Grabmayr H, Höglinger C, Fahrner M, Lunz V, Maltan L, Frischauf I, Krivic D, Bhardwaj R, Schindl R, Hediger MA, Derler I. Orai1 Boosts SK3 Channel Activation. Cancers (Basel) 2021; 13:6357. [PMID: 34944977 PMCID: PMC8699475 DOI: 10.3390/cancers13246357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/13/2021] [Indexed: 12/20/2022] Open
Abstract
The interplay of SK3, a Ca2+ sensitive K+ ion channel, with Orai1, a Ca2+ ion channel, has been reported to increase cytosolic Ca2+ levels, thereby triggering proliferation of breast and colon cancer cells, although a molecular mechanism has remained elusive to date. We show in the current study, via heterologous protein expression, that Orai1 can enhance SK3 K+ currents, in addition to constitutively bound calmodulin (CaM). At low cytosolic Ca2+ levels that decrease SK3 K+ permeation, co-expressed Orai1 potentiates SK3 currents. This positive feedback mechanism of SK3 and Orai1 is enabled by their close co-localization. Remarkably, we discovered that loss of SK3 channel activity due to overexpressed CaM mutants could be restored by Orai1, likely via its interplay with the SK3-CaM binding site. Mapping for interaction sites within Orai1, we identified that the cytosolic strands and pore residues are critical for a functional communication with SK3. Moreover, STIM1 has a bimodal role in SK3-Orai1 regulation. Under physiological ionic conditions, STIM1 is able to impede SK3-Orai1 interplay by significantly decreasing their co-localization. Forced STIM1-Orai1 activity and associated Ca2+ influx promote SK3 K+ currents. The dynamic regulation of Orai1 to boost endogenous SK3 channels was also determined in the human prostate cancer cell line LNCaP.
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Affiliation(s)
- Adéla Tiffner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Valentina Hopl
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Romana Schober
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias Sallinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Herwig Grabmayr
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Carmen Höglinger
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Marc Fahrner
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Victoria Lunz
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Lena Maltan
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Irene Frischauf
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
| | - Denis Krivic
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Rajesh Bhardwaj
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Rainer Schindl
- Gottfried Schatz Research Centre, Medical University of Graz, A-8010 Graz, Austria; (D.K.); (R.S.)
| | - Matthias A. Hediger
- Department of Nephrology and Hypertension, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland; (R.B.); (M.A.H.)
- Department of Biomedical Research, University of Bern, Inselspital, Freiburgstrasse 15, CH-3010 Bern, Switzerland
| | - Isabella Derler
- JKU Life Science Center, Institute of Biophysics, Johannes Kepler University Linz, A-4020 Linz, Austria; (A.T.); (V.H.); (R.S.); (M.S.); (H.G.); (C.H.); (M.F.); (V.L.); (L.M.); (I.F.)
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SK Channels Modulation Accelerates Equilibrium Recovery in Unilateral Vestibular Neurectomized Rats. Pharmaceuticals (Basel) 2021; 14:ph14121226. [PMID: 34959626 PMCID: PMC8707273 DOI: 10.3390/ph14121226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 12/17/2022] Open
Abstract
We have previously reported in a feline model of acute peripheral vestibulopathy (APV) that the sudden, unilateral, and irreversible loss of vestibular inputs induces selective overexpression of small conductance calcium-activated potassium (SK) channels in the brain stem vestibular nuclei. Pharmacological blockade of these ion channels by the selective antagonist apamin significantly alleviated the evoked vestibular syndrome and accelerated vestibular compensation. In this follow-up study, we aimed at testing, using a behavioral approach, whether the antivertigo (AV) effect resulting from the antagonization of SK channels was species-dependent or whether it could be reproduced in a rodent APV model, whether other SK channel antagonists reproduced similar functional effects on the vestibular syndrome expression, and whether administration of SK agonist could also alter the vestibular syndrome. We also compared the AV effects of apamin and acetyl-DL-leucine, a reference AV compound used in human clinic. We demonstrate that the AV effect of apamin is also found in a rodent model of APV. Other SK antagonists also produce a trend of AV effect when administrated during the acute phase of the vertigo syndrome. Conversely, the vertigo syndrome is worsened upon administration of SK channel agonist. It is noteworthy that the AV effect of apamin is superior to that of acetyl-DL-leucine. Taken together, these data reinforce SK channels as a pharmacological target for modulating the manifestation of the vertigo syndrome during APV.
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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21
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Zhao J, Zhang Y, Liu X, Rao Y, Fu J, Hua L, Ou C. Activation of SK3 channel plays a pivotal role in modulation of trigeminal neuralgia. Neurol Res 2021; 43:1005-1012. [PMID: 34233598 DOI: 10.1080/01616412.2021.1948765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Objective: To investigate whether small conductance Ca2+ activatedK+ channels; Trigeminal ganglion; Trigeminal neuralgia. (SK3) exists in normal rats' trigeminal ganglions (TG) and its effect on their pain thresholds.Methods: In total, 110 healthy adult male Sprague-Dawley (SD) rats were involved in this study. Ten rats were dissected to collect their liver tissues, TG and DRG. The rest of the rats were randomly assigned to either the experimental group or the control group. The animal model of trigeminal neuralgia (TN) was established by infraorbital nerve ligation. The expression of SK3 channels in their livers, TG and dorsal root ganglions (DRG) were detected. And different doses of SK3 channel activator and inhibitor were administered to the rats in both groups 15 days after the operation; meanwhile, their pain thresholds were also measured.Results: The expression of SK3 channel was found in TG. In the experimental group, the pain threshold was significantly decreased and there was a decreased level of SK3 than that in the control group at 15 days after operation. The administration of SK3 channel agonist (CyPPA) could significantly improve the pain threshold, while, the pain threshold decreased after administration of SK3 channel antagonist (Apamin).Conclusion: The SK3 channel may play a pivotal role in the pathogenesis of trigeminal neuralgia, and it may be one of the potential targets for the treatment of trigeminal neuralgia.
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Affiliation(s)
- Jiaomei Zhao
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Yue Zhang
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Xiangbo Liu
- Department of Pain Management, The Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan Province, China
| | - Yong Rao
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Jia Fu
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Lu Hua
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
| | - Cehua Ou
- Department of Pain Management, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan Province, China
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22
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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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23
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Sanders KM, Mutafova-Yambolieva VN. Neurotransmitters responsible for purinergic motor neurotransmission and regulation of GI motility. Auton Neurosci 2021; 234:102829. [PMID: 34146957 DOI: 10.1016/j.autneu.2021.102829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 12/17/2022]
Abstract
Classical concepts of peripheral neurotransmission were insufficient to explain enteric inhibitory neurotransmission. Geoffrey Burnstock and colleagues developed the idea that ATP or a related purine satisfies the criteria for a neurotransmitter and serves as an enteric inhibitory neurotransmitter in GI muscles. Cloning of purinergic receptors and development of specific drugs and transgenic mice have shown that enteric inhibitory responses depend upon P2Y1 receptors in post-junctional cells. The post-junctional cells that transduce purinergic neurotransmitters in the GI tract are PDGFRα+ cells and not smooth muscle cells (SMCs). PDGFRα+ cells express P2Y1 receptors, are activated by enteric inhibitory nerve stimulation and generate Ca2+ oscillations, express small-conductance Ca2+-activated K+ channels (SK3), and generate outward currents when exposed to P2Y1 agonists. These properties are consistent with post-junctional purinergic responses, and similar responses and effectors are not functional in SMCs. Refinements in methodologies to measure purines in tissue superfusates, such as high-performance liquid chromatography (HPLC) coupled with etheno-derivatization of purines and fluorescence detection, revealed that multiple purines are released during stimulation of intrinsic nerves. β-NAD+ and other purines, better satisfy criteria for the purinergic neurotransmitter than ATP. HPLC has also allowed better detection of purine metabolites, and coupled with isolation of specific types of post-junctional cells, has provided new concepts about deactivation of purine neurotransmitters. In spite of steady progress, many unknowns about purinergic neurotransmission remain and require additional investigation to understand this important regulatory mechanism in GI motility.
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Affiliation(s)
- Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA.
| | - Violeta N Mutafova-Yambolieva
- Department of Physiology and Cell Biology, University of Nevada, School of Medicine, 1664 North Virginia Street, Reno, NV 89557, USA
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24
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Sevrain CM, Fontaine D, Bauduin A, Guéguinou M, Zhang BL, Chantôme A, Mahéo K, Pasqualin C, Maupoil V, Couthon H, Vandier C, Jaffrès PA. Thio-ether functionalized glycolipid amphiphilic compounds reveal a potent activator of SK3 channel with vasorelaxation effect. Org Biomol Chem 2021; 19:2753-2766. [PMID: 33687423 DOI: 10.1039/d1ob00021g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The modulation of SK3 ion channels can be efficiently and selectively achieved by using the amphiphilic compound Ohmline (a glyco-glycero-ether-lipid). We report herein a series of Ohmline analogues featuring the replacement of one ether function by a thioether function located at the same position or shifted close to its initial position. The variation of the lipid chain length and the preparation of two analogues featuring either one sulfoxide or one sulfone moiety complete this series. Patch clamp measurements indicate that the presence of the thioether function (compounds 7 and 17a) produces strong activators of SK3 channels, whereas the introduction of a sulfoxide or a sulfone function at the same place produces amphiphiles devoid of an effect on SK3 channels. Compounds 7 and 17a are the first amphiphilic compounds featuring strong activation of SK3 channels (close to 200% activation). The cytosolic calcium concentration determined from fluorescence at 3 different times for compound 7b (13 min, 1 h, 24 h) revealed that the effect is different suggesting that the compound could be metabolized over time. This compound could be used as a strong SK3 activator for a short time. The capacity of 7b to activate SK3 was then used to induce vasorelaxation via an endothelium-derived hyperpolarization (EDH) pathway. For the first time, we report that an amphiphilic compound can affect the endothelium dependent vasorelaxation.
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Affiliation(s)
- Charlotte M Sevrain
- Univ. Brest, CNRS, CEMCA UMR 6521, 6 Avenue Victor Le Gorgeu, Brest, F-29238 Brest, France.
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25
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Nam YW, Cui M, Orfali R, Viegas A, Nguyen M, Mohammed EHM, Zoghebi KA, Rahighi S, Parang K, Zhang M. Hydrophobic interactions between the HA helix and S4-S5 linker modulate apparent Ca 2+ sensitivity of SK2 channels. Acta Physiol (Oxf) 2021; 231:e13552. [PMID: 32865319 PMCID: PMC7736289 DOI: 10.1111/apha.13552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/09/2020] [Accepted: 08/20/2020] [Indexed: 12/11/2022]
Abstract
AIM Small-conductance Ca2+ -activated potassium (SK) channels are activated exclusively by increases in intracellular Ca2+ that binds to calmodulin constitutively associated with the channel. Wild-type SK2 channels are activated by Ca2+ with an EC50 value of ~0.3 μmol/L. Here, we investigate hydrophobic interactions between the HA helix and the S4-S5 linker as a major determinant of channel apparent Ca2+ sensitivity. METHODS Site-directed mutagenesis, electrophysiological recordings and molecular dynamic (MD) simulations were utilized. RESULTS Mutations that decrease hydrophobicity at the HA-S4-S5 interface lead to Ca2+ hyposensitivity of SK2 channels. Mutations that increase hydrophobicity result in hypersensitivity to Ca2+ . The Ca2+ hypersensitivity of the V407F mutant relies on the interaction of the cognate phenylalanine with the S4-S5 linker in the SK2 channel. Replacing the S4-S5 linker of the SK2 channel with the S4-S5 linker of the SK4 channel results in loss of the hypersensitivity caused by V407F. This difference between the S4-S5 linkers of SK2 and SK4 channels can be partially attributed to I295 equivalent to a valine in the SK4 channel. A N293A mutation in the S4-S5 linker also increases hydrophobicity at the HA-S4-S5 interface and elevates the channel apparent Ca2+ sensitivity. The double N293A/V407F mutations generate a highly Ca2+ sensitive channel, with an EC50 of 0.02 μmol/L. The MD simulations of this double-mutant channel revealed a larger channel cytoplasmic gate. CONCLUSION The electrophysiological data and MD simulations collectively suggest a crucial role of the interactions between the HA helix and S4-S5 linker in the apparent Ca2+ sensitivity of SK2 channels.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Adam Viegas
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Misa Nguyen
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Eman H M Mohammed
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Khalid A Zoghebi
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Simin Rahighi
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Keykavous Parang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, USA
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Tiffner A, Derler I. Molecular Choreography and Structure of Ca 2+ Release-Activated Ca 2+ (CRAC) and K Ca2+ Channels and Their Relevance in Disease with Special Focus on Cancer. MEMBRANES 2020; 10:membranes10120425. [PMID: 33333945 PMCID: PMC7765462 DOI: 10.3390/membranes10120425] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022]
Abstract
Ca2+ ions play a variety of roles in the human body as well as within a single cell. Cellular Ca2+ signal transduction processes are governed by Ca2+ sensing and Ca2+ transporting proteins. In this review, we discuss the Ca2+ and the Ca2+-sensing ion channels with particular focus on the structure-function relationship of the Ca2+ release-activated Ca2+ (CRAC) ion channel, the Ca2+-activated K+ (KCa2+) ion channels, and their modulation via other cellular components. Moreover, we highlight their roles in healthy signaling processes as well as in disease with a special focus on cancer. As KCa2+ channels are activated via elevations of intracellular Ca2+ levels, we summarize the current knowledge on the action mechanisms of the interplay of CRAC and KCa2+ ion channels and their role in cancer cell development.
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Padula AE, Rinker JA, Lopez MF, Mulligan MK, Williams RW, Becker HC, Mulholland PJ. Bioinformatics identification and pharmacological validation of Kcnn3/K Ca2 channels as a mediator of negative affective behaviors and excessive alcohol drinking in mice. Transl Psychiatry 2020; 10:414. [PMID: 33247097 PMCID: PMC7699620 DOI: 10.1038/s41398-020-01099-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/16/2020] [Accepted: 11/06/2020] [Indexed: 12/12/2022] Open
Abstract
Mood disorders are often comorbid with alcohol use disorder (AUD) and play a considerable role in the development and maintenance of alcohol dependence and relapse. Because of this high comorbidity, it is necessary to determine shared and unique genetic factors driving heavy drinking and negative affective behaviors. In order to identify novel pharmacogenetic targets, a bioinformatics analysis was used to quantify the expression of amygdala K+ channel genes that covary with anxiety-related phenotypes in the well-phenotyped and fully sequenced family of BXD strains. We used a model of stress-induced escalation of drinking in alcohol-dependent mice to measure negative affective behaviors during abstinence. A pharmacological approach was used to validate the key bioinformatics findings in alcohol-dependent, stressed mice. Amygdalar expression of Kcnn3 correlated significantly with 40 anxiety-associated phenotypes. Further examination of Kcnn3 expression revealed a strong eigentrait for anxiety-like behaviors and negative correlations with binge-like and voluntary alcohol drinking. Mice treated with chronic intermittent alcohol exposure and repeated swim stress consumed more alcohol in their home cages and showed hypophagia on the novelty-suppressed feeding test during abstinence. Pharmacologically targeting Kcnn gene products with the KCa2 (SK) channel-positive modulator 1-EBIO decreased drinking and reduced feeding latency in alcohol-dependent, stressed mice. Collectively, these validation studies provide central nervous system links into the covariance of stress, negative affective behaviors, and AUD in the BXD strains. Further, the bioinformatics discovery tool is effective in identifying promising targets (i.e., KCa2 channels) for treating alcohol dependence exacerbated by comorbid mood disorders.
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Affiliation(s)
- Audrey E Padula
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425, USA
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Jennifer A Rinker
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425, USA
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Marcelo F Lopez
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, 29425, USA
- Department of Psychiatry & Behavioral Sciences, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Megan K Mulligan
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee, 38163, USA
| | - Robert W Williams
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee, 38163, USA
| | - Howard C Becker
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, 29425, USA
- Department of Psychiatry & Behavioral Sciences, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Patrick J Mulholland
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425, USA.
- Charleston Alcohol Research Center, Medical University of South Carolina, Charleston, SC, 29425, USA.
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28
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Mousa MH, Elbasiouny SM. Dendritic distributions of L-type Ca 2+ and SK L channels in spinal motoneurons: a simulation study. J Neurophysiol 2020; 124:1285-1307. [PMID: 32937080 PMCID: PMC7717167 DOI: 10.1152/jn.00169.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 09/03/2020] [Accepted: 09/03/2020] [Indexed: 12/12/2022] Open
Abstract
Persistent inward currents are important to motoneuron excitability and firing behaviors and also have been implicated in excitotoxicity. In particular, L-type Ca2+ channels, usually located on motoneuron dendrites, play a primary role in amplification of synaptic inputs. However, recent experimental findings on L-type Ca2+ channel behaviors challenge some fundamental assumptions that have been used in interpreting experimental and computational modeling data. Thus, the objectives of this study were to incorporate recent experimental data into an updated, high-fidelity computational model in order to explain apparent inconsistencies and to better elucidate the spatial distributions, expression patterns, and functional roles of L-type Ca2+ and SKL channels. Specifically, the updated model incorporated asymmetric channel activation/deactivation kinetics, depolarization-dependent facilitation, randomness in channel gating, and coactivation of SKL channels. Our simulation results suggest that L-type Ca2+ and SKL channels colocalize primarily on distal dendrites of motoneurons in a punctate expression. Also, punctate expression, as opposed to a homogeneous expression, provides high synaptic current amplification, limits bistability and firing rates, and robustly regulates the Ca2+ persistent inward current, thereby reducing risk of excitotoxicity. The hysteresis and bistability observed experimentally in current-voltage and frequency-current relationships result from the L-type Ca2+ channels' distal location and intrinsic warm-up. Accordingly, our results indicate that punctate expression of L-type Ca2+ and SKL channels is a potent mechanism for regulating excitability, which would provide a strong neuroprotective effect. Our results could provide broader insights into the functional significance of warm-up and punctate expression of ion channels to regulation of cell excitability.NEW & NOTEWORTHY Recent experimental findings on L-type Ca2+ channels challenge fundamental assumptions used in interpreting experimental and computational modeling data. Here, we incorporated recent experimental data into an updated, high-fidelity computational model to explain apparent inconsistencies and better elucidate the distributions, expression patterns, and functional roles of L-type Ca2+ and SKL channels. Our results indicate that punctate expression of L-type Ca2+ and SKL channels is a potent mechanism for regulating motoneuron excitability, providing a strong neuroprotective effect.
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Affiliation(s)
- Mohamed H Mousa
- Department of Systems and Biomedical Engineering, Faculty of Engineering, Cairo University, Cairo, Egypt
- Department of Biomedical, Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University, Dayton, Ohio
| | - Sherif M Elbasiouny
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, Ohio
- Department of Biomedical, Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University, Dayton, Ohio
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Impact of I SK Voltage and Ca 2+/Mg 2+-Dependent Rectification on Cardiac Repolarization. Biophys J 2020; 119:690-704. [PMID: 32668235 DOI: 10.1016/j.bpj.2020.06.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 06/02/2020] [Accepted: 06/10/2020] [Indexed: 10/24/2022] Open
Abstract
Cardiac small conductance Ca2+-activated K+ (SK) channels are activated solely by Ca2+, but the SK current (ISK) is inwardly rectified. However, the impact of inward rectification in shaping action potentials (APs) in ventricular cardiomyocytes under β-adrenergic stimulation or in disease states remains undefined. Two processes underlie this inward rectification: an intrinsic rectification caused by an electrostatic energy barrier from positively charged amino acids at the inner pore and a voltage-dependent Ca2+/Mg2+ block. Thus, Ca2+ has a biphasic effect on ISK, activating at low [Ca2+] yet inhibiting ISK at high [Ca2+]. We examined the effect of ISK rectification on APs in rat cardiomyocytes by simultaneously recording whole-cell apamin-sensitive currents and Ca2+ transients during an AP waveform and developed a computer model of SK channels with rectification features. The typical profile of ISK during AP clamp included an initial peak (mean 1.6 pA/pF) followed by decay to the point that submembrane [Ca2+] reached ∼10 μM. During the rest of the AP stimulus, ISK either plateaued or gradually increased as the cell repolarized and submembrane [Ca2+] decreased further. We used a six-state gating model combined with intrinsic and Ca2+/Mg2+-dependent rectification to simulate ISK and investigated the relative contributions of each type of rectification to AP shape. This SK channel model replicates key features of ISK recording during AP clamp showing that intrinsic rectification limits ISK at high Vm during the early and plateau phase of APs. Furthermore, the initial rise of Ca2+ transients activates, but higher [Ca2+] blocks SK channels, yielding a transient outward-like ISK trajectory. During the decay phase of Ca2+, the Ca2+-dependent block is released, causing ISK to rise again and contribute to repolarization. Therefore, ISK is an important repolarizing current, and the rectification characteristics of an SK channel determine its impact on early, plateau, and repolarization phases of APs.
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Flavahan S, Flavahan NA. Cooling-induced dilatation of cutaneous arteries is mediated by increased myoendothelial communication. Am J Physiol Heart Circ Physiol 2020; 319:H123-H132. [PMID: 32469638 DOI: 10.1152/ajpheart.00159.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cold exposure causes cutaneous vasoconstriction via a reflex increase in sympathetic activity and a local effect to augment adrenergic constriction. Local cooling also initiates cutaneous dilatation, which may function to restrain cold-induced constriction. However, the underlying mechanisms and physiological role of cold-induced dilatation have not been defined. Experiments were performed to assess the role of endothelial-derived mediators in this response. In isolated pressurized cutaneous mouse tail arteries, cooling (28°C) did not affect the magnitude of dilatation to acetylcholine in preconstricted arteries. However, inhibition of nitric oxide (NO) [NG-nitro-l-arginine methyl ester (l-NAME)] and prostacyclin (PGI2) (indomethacin) reduced acetylcholine-induced dilatation at 37°C but not at 28°C, suggesting that cooling increased NO/PGI2-independent dilatation. This NO/PGI2-independent dilatation was reduced by inhibition of endothelial SK (UCL1684) and IK (TRAM34) Ca2+-activated K+-channels (KCa), consistent with endothelium-derived hyperpolarization (EDH). Cooling also increased dilatation to direct activation of KCa channels (SKA31, CyPPA) but did not affect dilatation to exogenous NO (DEA-NONOate). This cooling-induced increase in EDH-type dilatations was associated with divergent effects on potential downstream EDH mechanisms: cooling reduced dilatation to K+, which mimics an intercellular K+ cloud, but increased direct communication between endothelial and smooth muscle cells (myoendothelial coupling), assessed by cellular transfer of biocytin. Indeed, inhibition of gap junctions (carbenoxolone) abolished the EDH-type component of dilatation to acetylcholine during cooling but did affect NO-dominated dilatation at 37°C. Cooling also inhibited U46619 constriction that was prevented by inhibition of IK and SK KCa channels or inhibition of gap junctions. The results suggest that cooling dilates cutaneous arteries by increasing myoendothelial communication and amplifying EDH-type dilatation.NEW & NOTEWORTHY Cold causes cutaneous vasoconstriction to restrict heat loss. Although cold also initiates cutaneous dilatation, the mechanisms and role of this dilatation have not been clearly defined. This study demonstrates that cooling increases myoendothelial coupling between smooth muscle and endothelial cells in cutaneous arteries, which is associated with increased endothelium-derived hyperpolarization (EDH)-type dilatation. Dysfunction in this process may contribute to excessive cold-induced constriction and tissue injury.
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Affiliation(s)
- Sheila Flavahan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Nicholas A Flavahan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland
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31
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Kouba S, Braire J, Félix R, Chantôme A, Jaffrès PA, Lebreton J, Dubreuil D, Pipelier M, Zhang X, Trebak M, Vandier C, Mathé-Allainmat M, Potier-Cartereau M. Lipidic synthetic alkaloids as SK3 channel modulators. Synthesis and biological evaluation of 2-substituted tetrahydropyridine derivatives with potential anti-metastatic activity. Eur J Med Chem 2020; 186:111854. [PMID: 31753515 DOI: 10.1016/j.ejmech.2019.111854] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/04/2019] [Indexed: 11/18/2022]
Abstract
Small Conductance Calcium (Ca2+)-activated potassium (K+) channels (SKCa) are now proved to be involved in many cancer cell behaviors such as proliferation or migration. The SK3 channel isoform was particularly described in breast cancer where it can be associated with the Orai1 Ca2+ channel to form a complex that regulates the Ca2+ homeostasis during tumor development and acts as a potent mediator of bone metastases development in vivo. Until now, very few specific blockers of Orai1 and/or SK3 have been developed as potential anti-metastatic compounds. In this study, we illustrated the synthesis of new families of lipophilic pyridine and tetrahydropyridine derivatives designed as potential modulators of SK3 channel. The toxicity of the newly synthesized compounds and their migration effects were evaluated on the breast cancer cell line MDA-MB-435s. Two molecules (7a and 10c) demonstrated a significant decrease in the SK3 channel-dependent migration as well as the SK3/Orai1-related Ca2+ entry. Current measurements showed that these compounds are more likely SK3-selective. Taken all together these results suggest that such molecules could be considered as promising anti-metastatic drugs in breast cancer.
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Affiliation(s)
- Sana Kouba
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Julien Braire
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Romain Félix
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Aurélie Chantôme
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Paul-Alain Jaffrès
- University of Brest, CNRS, CEMCA, UMR 6521, 6 Avenue Victor Le Gorgeu, 29238, Brest, France
| | - Jacques Lebreton
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Didier Dubreuil
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Muriel Pipelier
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Xuexin Zhang
- Pennylvania State University College of Medicine, Department of Cellular and Molecular Physiology, 700 HMC Crescent Road, Hershey, PA, 17033, USA
| | - Mohamed Trebak
- Pennylvania State University College of Medicine, Department of Cellular and Molecular Physiology, 700 HMC Crescent Road, Hershey, PA, 17033, USA
| | - Christophe Vandier
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Monique Mathé-Allainmat
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France.
| | - Marie Potier-Cartereau
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France.
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32
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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33
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Diadenosine tetraphosphate activates P2Y 1 receptors that cause smooth muscle relaxation in the mouse colon. Eur J Pharmacol 2019; 855:160-166. [PMID: 31063775 DOI: 10.1016/j.ejphar.2019.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 01/01/2023]
Abstract
P2Y1 receptors play an essential role in inhibitory neuromuscular transmission in the gastrointestinal tract. The signalling pathway involves the opening of small conductance calcium activated potassium-channels (Kca2 family) that results in smooth muscle hyperpolarization and relaxation. Inorganic polyphosphates and dinucleotidic polyphosphates are putative neurotransmitters that potentially act on P2Y1 receptors. A pharmacological approach using both orthosteric (MRS2500) and allosteric (BPTU) blockers of the P2Y1 receptor and openers (CyPPA) and blockers (apamin) of Kca2 channels was used to pharmacologically characterise the effect of these neurotransmitters. Organ bath and microelectrodes were used to evaluate the effect of P1,P4-Di (adenosine-5') tetraphosphate ammonium salt (Ap4A), inorganic polyphosphates (PolyP) and CyPPA on spontaneous contractions and membrane potential of mouse colonic smooth muscle cells. PolyP neither modified contractions nor membrane potential. In contrast, Ap4A caused a concentration-dependent inhibition of spontaneous contractions reaching a maximum effect at 100 μM Ap4A response was antagonised by MRS2500 (1 μM), BPTU (3 μM) and apamin (1 μM). CyPPA (10 μM) inhibited spontaneous contractions and this response was antagonised by apamin but it was not affected by MRS2500 or BPTU. Both CyPPA and Ap4A caused smooth muscle hyperpolarization that was blocked by apamin and MRS2500 respectively. We conclude that Ap4A but not PolyP activates P2Y1 receptors causing smooth muscle hyperpolarization and relaxation. Ap4A signalling causes activation of Kca2 channels through activation of P2Y1 receptors. In contrast, CyPPA acts directly on Kca2 channels. Further studies are needed to evaluate if dinucleotidic polyphosphates are released from inhibitory motor neurons.
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34
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Simonsen U, Winther AK, Oliván-Viguera A, Comerma-Steffensen S, Köhler R, Bek T. Extracellular l-arginine Enhances Relaxations Induced by Opening of Calcium-Activated SKCa Channels in Porcine Retinal Arteriole. Int J Mol Sci 2019; 20:ijms20082032. [PMID: 31027156 PMCID: PMC6515554 DOI: 10.3390/ijms20082032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 01/27/2023] Open
Abstract
We investigated whether the substrate for nitric oxide (NO) production, extracellular l-arginine, contributes to relaxations induced by activating small (SKCa) conductance Ca2+-activated potassium channels. In endothelial cells, acetylcholine increased 3H-l-arginine uptake, while blocking the SKCa and the intermediate (IKCa) conductance Ca2+-activated potassium channels reduced l-arginine uptake. A blocker of the y+ transporter system, l-lysine also blocked 3H-l-arginine uptake. Immunostaining showed co-localization of endothelial NO synthase (eNOS), SKCa3, and the cationic amino acid transporter (CAT-1) protein of the y+ transporter system in the endothelium. An opener of SKCa channels, cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) induced large currents in endothelial cells, and concentration-dependently relaxed porcine retinal arterioles. In the presence of l-arginine, concentration-response curves for CyPPA were leftward shifted, an effect unaltered in the presence of low sodium, but blocked by l-lysine in the retinal arterioles. Our findings suggest that SKCa channel activity regulates l-arginine uptake through the y+ transporter system, and we propose that in vasculature affected by endothelial dysfunction, l-arginine administration requires the targeting of additional mechanisms such as SKCa channels to restore endothelium-dependent vasodilatation.
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Affiliation(s)
- Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Anna K Winther
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Aida Oliván-Viguera
- BESICoS group, Aragón Institute of Engineering Research, IIS-Aragón, University of Zaragoza, 50009 Zaragoza, Spain.
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
| | - Ralf Köhler
- Aragón Agency for Research and Development (ARAID) at IACS and IIS Aragón, 50009 Zaragoza, Spain.
| | - Toke Bek
- Department of Ophthalmology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark.
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35
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Hamilton S, Polina I, Terentyeva R, Bronk P, Kim TY, Roder K, Clements RT, Koren G, Choi BR, Terentyev D. PKA phosphorylation underlies functional recruitment of sarcolemmal SK2 channels in ventricular myocytes from hypertrophic hearts. J Physiol 2019; 598:2847-2873. [PMID: 30771223 PMCID: PMC7496687 DOI: 10.1113/jp277618] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 02/08/2019] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Small-conductance Ca2+ -activated K+ (SK) channels expressed in ventricular myocytes are dormant in health, yet become functional in cardiac disease. SK channels are voltage independent and their gating is controlled by intracellular [Ca2+ ] in a biphasic manner. Submicromolar [Ca2+ ] activates the channel via constitutively-bound calmodulin, whereas higher [Ca2+ ] exerts inhibitory effect during depolarization. Using a rat model of cardiac hypertrophy induced by thoracic aortic banding, we found that functional upregulation of SK2 channels in hypertrophic rat ventricular cardiomyocytes is driven by protein kinase A (PKA) phosphorylation. Using site-directed mutagenesis, we identified serine-465 as the site conferring PKA-dependent effects on SK2 channel function. PKA phosphorylation attenuates ISK rectification by reducing the Ca2+ /voltage-dependent inhibition of SK channels without changing their sensitivity to activating submicromolar [Ca2+ ]i . This mechanism underlies the functional recruitment of SK channels not only in cardiac disease, but also in normal physiology, contributing to repolarization under conditions of enhanced adrenergic drive. ABSTRACT Small-conductance Ca2+ -activated K+ (SK) channels expressed in ventricular myocytes (VMs) are dormant in health, yet become functional in cardiac disease. We aimed to test the hypothesis that post-translational modification of SK channels under conditions accompanied by enhanced adrenergic drive plays a central role in disease-related activation of the channels. We investigated this phenomenon using a rat model of hypertrophy induced by thoracic aortic banding (TAB). Western blot analysis using anti-pan-serine/threonine antibodies demonstrated enhanced phosphorylation of immunoprecipitated SK2 channels in VMs from TAB rats vs. Shams, which was reversible by incubation of the VMs with PKA inhibitor H89 (1 μmol L-1 ). Patch clamped VMs under basal conditions from TABs but not Shams exhibited outward current sensitive to the specific SK inhibitor apamin (100 nmol L-1 ), which was eliminated by inhibition of PKA (1 μmol L-1 ). Beta-adrenergic stimulation (isoproterenol, 100 nmol L-1 ) evoked ISK in VMs from Shams, resulting in shortening of action potentials in VMs and ex vivo optically mapped Sham hearts. Using adenoviral gene transfer, wild-type and mutant SK2 channels were overexpressed in adult rat VMs, revealing serine-465 as the site that elicits PKA-dependent phosphorylation effects on SK2 channel function. Concurrent confocal Ca2+ imaging experiments established that PKA phosphorylation lessens rectification of ISK via reduction Ca2+ /voltage-dependent inhibition of the channels at high [Ca2+ ] without affecting their sensitivity to activation by Ca2+ in the submicromolar range. In conclusion, upregulation of SK channels in diseased VMs is mediated by hyperadrenergic drive in cardiac hypertrophy, with functional effects on the channel conferred by PKA-dependent phosphorylation at serine-465.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Iuliia Polina
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA.,Medical University of South Carolina, Department of Medicine, Division of Nephrology, Charleston, SC, USA
| | - Radmila Terentyeva
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Peter Bronk
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA
| | - Tae Yun Kim
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA
| | - Karim Roder
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA
| | - Richard T Clements
- Department of Surgery, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA.,Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Providence, RI, USA
| | - Gideon Koren
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA
| | - Bum-Rak Choi
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Rhode Island Hospital, Cardiovascular Research Center, Providence, RI, USA.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH, USA.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
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36
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The ion channel activator CyPPA inhibits melanogenesis via the GSK3β/β-catenin pathway. Chem Biol Interact 2019; 300:1-7. [PMID: 30597128 DOI: 10.1016/j.cbi.2018.12.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 12/17/2018] [Accepted: 12/21/2018] [Indexed: 11/24/2022]
Abstract
Research into materials that inhibit melanogenesis in skin has gained interest. Screening for such compounds in B16F10 cells revealed that cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA), a positive modulator of small-conductance Ca2+-activated K+ channels, is a strong inhibitor of melanogenesis. We investigated the anti-melanogenic activity of CyPPA and the molecular mechanism by which CyPPA reduced melanin production in normal human melanocytes (NHM). CyPPA treatment resulted in a significant concentration-dependent reduction in melanin content without significant cytotoxicity; treatment likewise resulted in a significant time-dependent reduction in tyrosinase (TYR) activity. Treatment with CyPPA also decreased transcription of melanogenesis-related genes, including the gene encoding microphthalmia-associated transcription factor (MITF). In addition, visual evaluation of the MelanoDerm™ human skin model revealed significantly lower melanin content in the CyPPA-treated condition than in the untreated control. CyPPA was determined to modulate glycogen synthase kinase-3β (GSK3β) activity, thereby leading to a decrease in β-catenin/MITF expression. Thus, CyPPA acts as a melanogenesis inhibitor by modulating the GSK3β/β-catenin/MITF pathway.
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37
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Chen M, Xu DZ, Wu AZ, Guo S, Wan J, Yin D, Lin SF, Chen Z, Rubart-von der Lohe M, Everett TH, Qu Z, Weiss JN, Chen PS. Concomitant SK current activation and sodium current inhibition cause J wave syndrome. JCI Insight 2018; 3:122329. [PMID: 30429367 DOI: 10.1172/jci.insight.122329] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/17/2018] [Indexed: 12/18/2022] Open
Abstract
The mechanisms of J wave syndrome (JWS) are incompletely understood. Here, we showed that the concomitant activation of small-conductance calcium-activated potassium (SK) current (IKAS) and inhibition of sodium current by cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) recapitulate the phenotypes of JWS in Langendorff-perfused rabbit hearts. CyPPA induced significant J wave elevation and frequent spontaneous ventricular fibrillation (SVF), as well as sinus bradycardia, atrioventricular block, and intraventricular conduction delay. IKAS activation by CyPPA resulted in heterogeneous shortening of action potential (AP) duration (APD) and repolarization alternans. CyPPA inhibited cardiac sodium current (INa) and decelerated AP upstroke and intracellular calcium transient. SVFs were typically triggered by short-coupled premature ventricular contractions, initiated with phase 2 reentry and originated more frequently from the right than the left ventricles. Subsequent IKAS blockade by apamin reduced J wave elevation and eliminated SVF. β-Adrenergic stimulation was antiarrhythmic in CyPPA-induced electrical storm. Like CyPPA, hypothermia (32.0°C) also induced J wave elevation and SVF. It facilitated negative calcium-voltage coupling and phase 2 repolarization alternans with spatial and electromechanical discordance, which were ameliorated by apamin. These findings suggest that IKAS activation contributes to the development of JWS in rabbit ventricles.
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Affiliation(s)
- Mu Chen
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cardiology, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Dong-Zhu Xu
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Cardiovascular Division, Institute of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Adonis Z Wu
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Shuai Guo
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cardiology, First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Juyi Wan
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cardiothoracic Surgery, Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Dechun Yin
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cardiology, First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shien-Fong Lin
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsin-Chu, Taiwan
| | - Zhenhui Chen
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Michael Rubart-von der Lohe
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Thomas H Everett
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Zhilin Qu
- Departments of Medicine (Cardiology) and Physiology, University of California, Los Angeles, California, USA
| | - James N Weiss
- Departments of Medicine (Cardiology) and Physiology, University of California, Los Angeles, California, USA
| | - Peng-Sheng Chen
- Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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38
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Cobine CA, McKechnie M, Brookfield RJ, Hannigan KI, Keef KD. Comparison of inhibitory neuromuscular transmission in the Cynomolgus monkey IAS and rectum: special emphasis on differences in purinergic transmission. J Physiol 2018; 596:5319-5341. [PMID: 30198065 DOI: 10.1113/jp275437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/07/2018] [Indexed: 01/04/2023] Open
Abstract
KEY POINTS Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with high gene sequence identity to humans. Nitrergic NMT was present in both muscles while purinergic NMT was limited to the rectum and VIPergic NMT to the IAS. The profile for monkey IAS more closely resembles humans than rodents. In both muscles, SK3 channels were localized to PDGFRα+ cells that were closely associated with nNOS+ /VIP+ nerves. Gene expression levels of P2RY subtypes were the same in IAS and rectum while KCNN expression levels were very similar. SK3 channel activation and inhibition caused faster/greater changes in contractile activity in rectum than IAS. P2Y1 receptor activation inhibited contraction in rectum while increasing contraction in IAS. The absence of purinergic NMT in the IAS may be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells. ABSTRACT Inhibitory neuromuscular transmission (NMT) was compared in the internal anal sphincter (IAS) and rectum of the Cynomolgus monkey, an animal with a high gene sequence identity to humans. Electrical field stimulation produced nitric oxide synthase (NOS)-dependent contractile inhibition in both muscles whereas P2Y1-dependent purinergic NMT was restricted to rectum. An additional NOS-independent, α-chymotrypsin-sensitive component was identified in the IAS consistent with vasoactive intestinal peptide-ergic (VIPergic) NMT. Microelectrode recordings revealed slow NOS-dependent inhibitory junction potentials (IJPs) in both muscles and fast P2Y1-dependent IJPs in rectum. The basis for the difference in purinergic NMT was investigated. PDGFRα+ /SK3+ cells were closely aligned with nNOS+ /VIP+ neurons in both muscles. Gene expression of P2RY was the same in IAS and rectum (P2RY1>>P2RY2-14) while KCNN3 expression was 32% greater in rectum. The SK channel inhibitor apamin doubled contractile activity in rectum while having minimal effect in the IAS. Contractile inhibition elicited with the SK channel agonist CyPPA was five times faster in rectum than in the IAS. The P2Y1 receptor agonist MRS2365 inhibited contraction in rectum but increased contraction in the IAS. In conclusion, both the IAS and the rectum have nitrergic NMT whereas purinergic NMT is limited to rectum and VIPergic NMT to the IAS. The profile in monkey IAS more closely resembles that of humans than rodents. The lack of purinergic NMT in the IAS cannot be attributed to the absence of PDGFRα+ cells, P2Y1 receptors or SK3 channels. Rather, it appears to be due to poor coupling between P2Y1 receptors and SK3 channels on PDGFRα+ cells.
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Affiliation(s)
- C A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - M McKechnie
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - R J Brookfield
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K I Hannigan
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - K D Keef
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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Mandge D, Manchanda R. A biophysically detailed computational model of urinary bladder small DRG neuron soma. PLoS Comput Biol 2018; 14:e1006293. [PMID: 30020934 PMCID: PMC6066259 DOI: 10.1371/journal.pcbi.1006293] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 07/30/2018] [Accepted: 06/11/2018] [Indexed: 12/13/2022] Open
Abstract
Bladder small DRG neurons, which are putative nociceptors pivotal to urinary bladder function, express more than a dozen different ionic membrane mechanisms: ion channels, pumps and exchangers. Small-conductance Ca2+-activated K+ (SKCa) channels which were earlier thought to be gated solely by intracellular Ca2+ concentration ([Ca]i) have recently been shown to exhibit inward rectification with respect to membrane potential. The effect of SKCa inward rectification on the excitability of these neurons is unknown. Furthermore, studies on the role of KCa channels in repetitive firing and their contributions to different types of afterhyperpolarization (AHP) in these neurons are lacking. In order to study these phenomena, we first constructed and validated a biophysically detailed single compartment model of bladder small DRG neuron soma constrained by physiological data. The model includes twenty-two major known membrane mechanisms along with intracellular Ca2+ dynamics comprising Ca2+ diffusion, cytoplasmic buffering, and endoplasmic reticulum (ER) and mitochondrial mechanisms. Using modelling studies, we show that inward rectification of SKCa is an important parameter regulating neuronal repetitive firing and that its absence reduces action potential (AP) firing frequency. We also show that SKCa is more potent in reducing AP spiking than the large-conductance KCa channel (BKCa) in these neurons. Moreover, BKCa was found to contribute to the fast AHP (fAHP) and SKCa to the medium-duration (mAHP) and slow AHP (sAHP). We also report that the slow inactivating A-type K+ channel (slow KA) current in these neurons is composed of 2 components: an initial fast inactivating (time constant ∼ 25-100 ms) and a slow inactivating (time constant ∼ 200-800 ms) current. We discuss the implications of our findings, and how our detailed model can help further our understanding of the role of C-fibre afferents in the physiology of urinary bladder as well as in certain disorders.
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Affiliation(s)
- Darshan Mandge
- Computational Neurophysiology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India 400076
| | - Rohit Manchanda
- Computational Neurophysiology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India 400076
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Skarsfeldt MA, Bomholtz SH, Lundegaard PR, Lopez-Izquierdo A, Tristani-Firouzi M, Bentzen BH. Atrium-specific ion channels in the zebrafish-A role of I KACh in atrial repolarization. Acta Physiol (Oxf) 2018; 223:e13049. [PMID: 29412518 DOI: 10.1111/apha.13049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/26/2018] [Accepted: 01/29/2018] [Indexed: 12/16/2022]
Abstract
AIM The zebrafish has emerged as a novel model for investigating cardiac physiology and pathology. The aim of this study was to investigate the atrium-specific ion channels responsible for shaping the atrial cardiac action potential in zebrafish. METHODS Using quantitative polymerase chain reaction, we assessed the expression level of atrium-specific potassium channels. The functional role of these channels was studied by patch clamp experiments on isolated atrial and ventricular cardiomyocytes and by optical mapping of explanted adult zebrafish hearts. Finally, surface ECGs were recorded to establish possible in vivo roles of atrial ion channels. RESULTS In isolated adult zebrafish hearts, we identified the expression of kcnk3, kcnk9, kcnn1, kcnn2, kcnn3, kcnj3 and kcnj5, the genes that encode the atrium-specific K2P , KCa 2.x and Kir 3.1/4 (KACh ) ion channels. The electrophysiological data indicate that the acetylcholine-activated inward-rectifying current, IKACh, plays a major role in the zebrafish atrium, whereas K2P 3.1/9.1 and KCa 2.x channels do not appear to be involved in regulating the action potential in the zebrafish heart. CONCLUSION We demonstrate that the acetylcholine-activated inward-rectifying current (IKACh ) current plays a major role in the zebrafish atrium and that the zebrafish could potentially be a cost-effective and reliable model for pharmacological testing of atrium-specific IKACh modulating compounds.
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Affiliation(s)
- M. A. Skarsfeldt
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - S. H. Bomholtz
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - P. R. Lundegaard
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - A. Lopez-Izquierdo
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - M. Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - B. H. Bentzen
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
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Mahrous AA, Elbasiouny SM. Modulation of SK channels regulates locomotor alternating bursting activity in the functionally-mature spinal cord. Channels (Austin) 2017; 12:9-14. [PMID: 28991505 PMCID: PMC5972800 DOI: 10.1080/19336950.2017.1389825] [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] [Indexed: 12/13/2022] Open
Abstract
The spinal cord contains specialized groups of cells called pattern generators, which are capable of orchestrating rhythmic firing activity in an isolated preparation. Different patterns of activity could be generated in vitro including right-left alternating bursting and bursting in which both sides are synchronized. The cellular and network mechanisms that enable these behaviors are not fully understood. We have recently shown that Ca2+-activated K+ channels (SK channels) control the initiation and amplitude of synchronized bursting in the spinal cord. It is unclear, however, whether SK channels play a similar role in the alternating rhythmic pattern. In the current study, we used a spinal cord preparation from functionally mature mice capable of weight bearing and walking. The present results extend our previous work and show that SK channel inhibition initiates and modulates the amplitude of alternating bursting. We also show that addition of methoxamine, an α1-adrenergic agonist, to a cocktail of serotonin, dopamine, and NMDA evokes robust and consistent alternating bursting throughout the cord.
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Affiliation(s)
- Amr A Mahrous
- a Department of Neuroscience , Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University , Dayton , Ohio , USA
| | - Sherif M Elbasiouny
- a Department of Neuroscience , Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University , Dayton , Ohio , USA.,b Department of Biomedical , Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University , Dayton , Ohio , USA
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Ca 2+ protein alpha 1D of CaV1.3 regulates intracellular calcium concentration and migration of colon cancer cells through a non-canonical activity. Sci Rep 2017; 7:14199. [PMID: 29079724 PMCID: PMC5660277 DOI: 10.1038/s41598-017-14230-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/03/2017] [Indexed: 01/05/2023] Open
Abstract
It is generally accepted that voltage-gated Ca2+ channels, CaV, regulate Ca2+ homeostasis in excitable cells following plasma membrane depolarization. Here, we show that the Ca2+ protein α1D of CaV1.3 channel is overexpressed in colorectal cancer biopsies compared to normal tissues. Gene silencing experiments targeting α1D reduced the migration and the basal cytosolic Ca2+ concentration of HCT116 colon cancer cell line and modified the cytosolic Ca2+ oscillations induced by the sodium/calcium exchanger NCX1/3 working in its reverse mode. Interestingly, NCX1/3 regulated membrane potential of HCT116 cells only when α1D was silenced, and blocking NCX1/3 increased cytosolic Ca2+ concentration and cell migration. However, membrane depolarization did not induce an increase in intracellular Ca2+. Patch-clamp experiments clearly showed that the inward Ca2+ current was absent. Finally, flow cytometry and immunofluorescence studies showed that α1D protein was localized at the plasma membrane, in cytosol and cell nuclei. Altogether, we uncover a novel signaling pathway showing that α1D is involved in the regulation of Ca2+ homeostasis and cell migration by a mechanism independent of its plasma membrane canonical function but that involved plasma membrane Na+/Ca2+ exchanger.
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Kim TY, Terentyeva R, Roder KHF, Li W, Liu M, Greener I, Hamilton S, Polina I, Murphy KR, Clements RT, Dudley SC, Koren G, Choi BR, Terentyev D. SK channel enhancers attenuate Ca2+-dependent arrhythmia in hypertrophic hearts by regulating mito-ROS-dependent oxidation and activity of RyR. Cardiovasc Res 2017; 113:343-353. [PMID: 28096168 DOI: 10.1093/cvr/cvx005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 01/12/2017] [Indexed: 01/17/2023] Open
Abstract
Aims Plasmamembrane small conductance Ca2+-activated K+ (SK) channels were implicated in ventricular arrhythmias in infarcted and failing hearts. Recently, SK channels were detected in the inner mitochondria membrane (IMM) (mSK), and their activation protected from acute ischaemia-reperfusion injury by reducing intracellular levels of reactive oxygen species (ROS). We hypothesized that mSK play an important role in regulating mitochondrial function in chronic cardiac diseases. We investigated the role of mSK channels in Ca2+-dependent ventricular arrhythmia using rat model of cardiac hypertrophy induced by banding of the ascending aorta thoracic aortic banding (TAB). Methods and results Dual Ca2+ and membrane potential optical mapping of whole hearts derived from TAB rats revealed that membrane-permeable SK enhancer NS309 (2 μM) improved aberrant Ca2+ homeostasis and abolished VT/VF induced by β-adrenergic stimulation. Using whole cell patch-clamp and confocal Ca2+ imaging of cardiomyocytes derived from TAB hearts (TCMs) we found that membrane-permeable SK enhancers NS309 and CyPPA (10 μM) attenuated frequency of spontaneous Ca2+ waves and delayed afterdepolarizations. Furthermore, mSK inhibition enhanced (UCL-1684, 1 μM); while activation reduced mitochondrial ROS production in TCMs measured with MitoSOX. Protein oxidation assays demonstrated that increased oxidation of ryanodine receptors (RyRs) in TCMs was reversed by SK enhancers. Experiments in permeabilized TCMs showed that SK enhancers restored SR Ca2+ content, suggestive of substantial improvement in RyR function. Conclusion These data suggest that enhancement of mSK channels in hypertrophic rat hearts protects from Ca2+-dependent arrhythmia and suggest that the protection is mediated via decreased mitochondrial ROS and subsequent decreased oxidation of reactive cysteines in RyR, which ultimately leads to stabilization of RyR-mediated Ca2+ release.
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Affiliation(s)
- Tae Yun Kim
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Radmila Terentyeva
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Karim H F Roder
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Weiyan Li
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Man Liu
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Ian Greener
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Shanna Hamilton
- Division of Cancer and Genetics, School of Medicine, Wales Heart Research Institute, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Iuliia Polina
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Kevin R Murphy
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Richard T Clements
- Department of Surgery, Cardiovascular Research Center, Rhode Island Hospital, The Warren, Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI 02903-4141, USA
| | - Samuel C Dudley
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Gideon Koren
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Bum-Rak Choi
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
| | - Dmitry Terentyev
- Department of Medicine, Division of Cardiology, Cardiovascular Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, 1 Hoppin Street, Providence, RI, 02903-4141, USA
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Brown BM, Shim H, Zhang M, Yarov-Yarovoy V, Wulff H. Structural Determinants for the Selectivity of the Positive KCa3.1 Gating Modulator 5-Methylnaphtho[2,1- d]oxazol-2-amine (SKA-121). Mol Pharmacol 2017; 92:469-480. [PMID: 28760780 DOI: 10.1124/mol.117.109421] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/27/2017] [Indexed: 12/20/2022] Open
Abstract
Intermediate-conductance (KCa3.1) and small-conductance (KCa2) calcium-activated K+ channels are gated by calcium binding to calmodulin (CaM) molecules associated with the calmodulin-binding domain (CaM-BD) of these channels. The existing KCa activators, such as naphtho[1,2-d]thiazol-2-ylamine (SKA-31), 6,7-dichloro-1H-indole-2,3-dione 3-oxime (NS309), and 1-ethylbenzimidazolin-2-one (EBIO), activate both channel types with similar potencies. In a previous chemistry effort, we optimized the benzothiazole pharmacophore of SKA-31 toward KCa3.1 selectivity and identified 5-methylnaphtho[2,1-d]oxazol-2-amine (SKA-121), which exhibits 40-fold selectivity for KCa3.1 over KCa2.3. To understand why introduction of a single CH3 group in five-position of the benzothiazole/oxazole system could achieve such a gain in selectivity for KCa3.1 over KCa2.3, we first localized the binding site of the benzothiazoles/oxazoles to the CaM-BD/CaM interface and then used computational modeling software to generate models of the KCa3.1 and KCa2.3 CaM-BD/CaM complexes with SKA-121. Based on a combination of mutagenesis and structural modeling, we suggest that all benzothiazole/oxazole-type KCa activators bind relatively "deep" in the CaM-BD/CaM interface and hydrogen bond with E54 on CaM. In KCa3.1, SKA-121 forms an additional hydrogen bond network with R362. In contrast, NS309 sits more "forward" and directly hydrogen bonds with R362 in KCa3.1. Mutating R362 to serine, the corresponding residue in KCa2.3 reduces the potency of SKA-121 by 7-fold, suggesting that R362 is responsible for the generally greater potency of KCa activators on KCa3.1. The increase in SKA-121's KCa3.1 selectivity compared with its parent, SKA-31, seems to be due to better overall shape complementarity and hydrophobic interactions with S372 and M368 on KCa3.1 and M72 on CaM at the KCa3.1-CaM-BD/CaM interface.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Heesung Shim
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Miao Zhang
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Vladimir Yarov-Yarovoy
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Heike Wulff
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
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Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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Onetti Y, Dantas AP, Pérez B, McNeish AJ, Vila E, Jiménez-Altayó F. Peroxynitrite formed during a transient episode of brain ischaemia increases endothelium-derived hyperpolarization-type dilations in thromboxane/prostaglandin receptor-stimulated rat cerebral arteries. Acta Physiol (Oxf) 2017; 220:150-166. [PMID: 27683007 DOI: 10.1111/apha.12809] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/05/2016] [Accepted: 09/22/2016] [Indexed: 12/19/2022]
Abstract
AIM Increased thromboxane A2 and peroxynitrite are hallmarks of cerebral ischaemia/reperfusion (I/R). Stimulation of thromboxane/prostaglandin receptors (TP) attenuates endothelium-derived hyperpolarization (EDH). We investigated whether EDH-type middle cerebral artery (MCA) relaxations following TP stimulation are altered after I/R and the influence of peroxynitrite. METHODS Vascular function was determined by wire myography after TP stimulation with the thromboxane A2 mimetic 9,11-dideoxy-9α, 11α -methano-epoxy prostaglandin F2α (U46619) in MCA of Sprague Dawley rats subjected to MCA occlusion (90 min)/reperfusion (24 h) or sham operation, and in non-operated (control) rats. Some rats were treated with saline or the peroxynitrite decomposition catalyst 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato iron (III) (20 mg kg-1 ). Protein expression was evaluated in MCA and in human microvascular endothelial cells submitted to hypoxia (overnight)/reoxygenation (24 h) (H/R) using immunofluorescence and immunoblotting. RESULTS In U46619-pre-constricted MCA, EDH-type relaxation by the proteinase-activated receptor 2 agonist serine-leucine-isoleucine-glycine-arginine-leucine-NH2 (SLIGRL) was greater in I/R than sham rats due to an increased contribution of small-conductance calcium-activated potassium channels (SKCa ), which was confirmed by the enlarged relaxation to the SKCa activator N-cyclohexyl-N-2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine. I/R and H/R induced endothelial protein tyrosine nitration and filamentous-actin disruption. In control MCA, either cytochalasin D or peroxynitrite disrupted endothelial filamentous-actin and augmented EDH-type relaxation. Furthermore, peroxynitrite decomposition during I/R prevented the increase in EDH-type responses. CONCLUSION Following TP stimulation in MCA, EDH-type relaxation to SLIGRL is greater after I/R due to endothelial filamentous-actin disruption by peroxynitrite, which prevents TP-induced block of SKCa input to EDH. These results reveal a novel mechanism whereby peroxynitrite could promote post-ischaemic brain injury.
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Affiliation(s)
- Y. Onetti
- Departament de Farmacologia, de Terapèutica i de Toxicologia; Institut de Neurociències; Facultat de Medicina; Universitat Autònoma de Barcelona; Bellaterra Spain
| | - A. P. Dantas
- Institut Clínic Cardiovascular; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Barcelona Spain
| | - B. Pérez
- Departament de Farmacologia, de Terapèutica i de Toxicologia; Institut de Neurociències; Facultat de Medicina; Universitat Autònoma de Barcelona; Bellaterra Spain
| | - A. J. McNeish
- Reading School of Pharmacy; University of Reading; Reading Berkshire UK
| | - E. Vila
- Departament de Farmacologia, de Terapèutica i de Toxicologia; Institut de Neurociències; Facultat de Medicina; Universitat Autònoma de Barcelona; Bellaterra Spain
| | - F. Jiménez-Altayó
- Departament de Farmacologia, de Terapèutica i de Toxicologia; Institut de Neurociències; Facultat de Medicina; Universitat Autònoma de Barcelona; Bellaterra Spain
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Mahrous AA, Elbasiouny SM. SK channel inhibition mediates the initiation and amplitude modulation of synchronized burst firing in the spinal cord. J Neurophysiol 2017; 118:161-175. [PMID: 28356481 DOI: 10.1152/jn.00929.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/06/2017] [Accepted: 03/25/2017] [Indexed: 11/22/2022] Open
Abstract
Burst firing in motoneurons represents the basis for generating meaningful movements. Neuromodulators and inhibitory receptor blocker cocktails have been used for years to induce burst firing in vitro; however, the ionic mechanisms in the motoneuron membrane that contribute to burst initiation and amplitude modulation are not fully understood. Small conductance Ca2+-activated potassium (SK) channels regulate excitatory inputs and firing output of motoneurons and interneurons and therefore, are a candidate for mediating bursting behavior. The present study examines the role of SK channels in the generation of synchronized bursting using an in vitro spinal cord preparation from adult mice. Our results show that SK channel inhibition is required for both initiation and amplitude modulation of burst firing. Specifically, administration of the synaptic inhibition blockers strychnine and picrotoxin amplified the spinal circuit excitatory drive but not enough to evoke bursting. However, when SK channels were inhibited using various approaches, the excitatory drive was further amplified, and synchronized bursting was always evoked. Furthermore, graded SK channel inhibition modulated the amplitude of the burst in a dose-dependent manner, which was reversed using SK channel activators. Importantly, modulation of neuronal excitability using multiple approaches failed to mimic the effects of SK modulators, suggesting a specific role for SK channel inhibition in generating bursting. Both NMDA (N-methyl-d-aspartate) and AMPA (α-amino-3-hydroxy-5-methylisoxazole-4-propionate) receptors were found to drive the synchronized bursts. The blocking of gap junctions did not disturb the burst synchrony. These results demonstrate a novel mechanistic role for SK channels in initiating and modulating burst firing of spinal motoneurons.NEW & NOTEWORTHY This study demonstrates that cholinergic inhibition or direct blockade of small conductance Ca2+-activated potassium (SK) channels facilitates burst firing in spinal motoneurons. The data provide a novel mechanistic explanation for synchronized bursting initiation and amplitude modulation through SK channel inhibition. Evidence also shows that synchronized bursting is driven by NMDA (N-methyl-d-aspartate) and AMPA (α-amino-3-hydroxy-5-methylisoxazole-4-propionate) receptors and that gap junctions do not mediate motoneuron synchronization in this behavior.
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Affiliation(s)
- Amr A Mahrous
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, Ohio; and
| | - Sherif M Elbasiouny
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine and College of Science and Mathematics, Wright State University, Dayton, Ohio; and .,Department of Biomedical, Industrial, and Human Factors Engineering, College of Engineering and Computer Science, Wright State University, Dayton, Ohio
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48
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Honrath B, Matschke L, Meyer T, Magerhans L, Perocchi F, Ganjam GK, Zischka H, Krasel C, Gerding A, Bakker BM, Bünemann M, Strack S, Decher N, Culmsee C, Dolga AM. SK2 channels regulate mitochondrial respiration and mitochondrial Ca 2+ uptake. Cell Death Differ 2017; 24:761-773. [PMID: 28282037 DOI: 10.1038/cdd.2017.2] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/29/2016] [Accepted: 12/14/2016] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial calcium ([Ca2+]m) overload and changes in mitochondrial metabolism are key players in neuronal death. Small conductance calcium-activated potassium (SK) channels provide protection in different paradigms of neuronal cell death. Recently, SK channels were identified at the inner mitochondrial membrane, however, their particular role in the observed neuroprotection remains unclear. Here, we show a potential neuroprotective mechanism that involves attenuation of [Ca2+]m uptake upon SK channel activation as detected by time lapse mitochondrial Ca2+ measurements with the Ca2+-binding mitochondria-targeted aequorin and FRET-based [Ca2+]m probes. High-resolution respirometry revealed a reduction in mitochondrial respiration and complex I activity upon pharmacological activation and overexpression of mitochondrial SK2 channels resulting in reduced mitochondrial ROS formation. Overexpression of mitochondria-targeted SK2 channels enhanced mitochondrial resilience against neuronal death, and this effect was inhibited by overexpression of a mitochondria-targeted dominant-negative SK2 channel. These findings suggest that SK channels provide neuroprotection by reducing [Ca2+]m uptake and mitochondrial respiration in conditions, where sustained mitochondrial damage determines progressive neuronal death.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany.,Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Behavioural and Cognitive Neurosciences (BCN), Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
| | - Lina Matschke
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Tammo Meyer
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Behavioural and Cognitive Neurosciences (BCN), Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
| | - Lena Magerhans
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Fabiana Perocchi
- Gene Center/Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, Germany.,Institute for Obesity and Diabetes, Helmholtz Zentrum München, Neuherberg, Germany
| | - Goutham K Ganjam
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Hans Zischka
- Institute of Molecular Toxicology and Pharmacology, Helmholtz Center Munich, German Research Center for Environmental Health GmbH, Neuherberg, Germany
| | - Cornelius Krasel
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Albert Gerding
- Center for Liver, Digestive and Metabolic Diseases, Department of Pediatrics & Systems Biology Center for Energy Metabolism and Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Barbara M Bakker
- Center for Liver, Digestive and Metabolic Diseases, Department of Pediatrics & Systems Biology Center for Energy Metabolism and Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Moritz Bünemann
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Stefan Strack
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Marburg, Germany
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, Marburg, Germany.,Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Behavioural and Cognitive Neurosciences (BCN), Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
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49
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Jara-Avaca M, Kempf H, Rückert M, Robles-Diaz D, Franke A, de la Roche J, Fischer M, Malan D, Sasse P, Solodenko W, Dräger G, Kirschning A, Martin U, Zweigerdt R. EBIO Does Not Induce Cardiomyogenesis in Human Pluripotent Stem Cells but Modulates Cardiac Subtype Enrichment by Lineage-Selective Survival. Stem Cell Reports 2017; 8:305-317. [PMID: 28089668 PMCID: PMC5311470 DOI: 10.1016/j.stemcr.2016.12.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/13/2016] [Accepted: 12/14/2016] [Indexed: 12/21/2022] Open
Abstract
Subtype-specific human cardiomyocytes (CMs) are valuable for basic and applied research. Induction of cardiomyogenesis and enrichment of nodal-like CMs was described for mouse pluripotent stem cells (mPSCs) in response to 1-ethyl-2-benzimidazolinone (EBIO), a chemical modulator of small-/intermediate-conductance Ca2+-activated potassium channels (SKs 1-4). Investigating EBIO in human pluripotent stem cells (PSCs), we have applied three independent differentiation protocols of low to high cardiomyogenic efficiency. Equivalent to mPSCs, timed EBIO supplementation during hPSC differentiation resulted in dose-dependent enrichment of up to 80% CMs, including an increase in nodal- and atrial-like phenotypes. However, our study revealed extensive EBIO-triggered cell loss favoring cardiac progenitor preservation and, subsequently, CMs with shortened action potentials. Proliferative cells were generally more sensitive to EBIO, presumably via an SK-independent mechanism. Together, EBIO did not promote cardiogenic differentiation of PSCs, opposing previous findings, but triggered lineage-selective survival at a cardiac progenitor stage, which we propose as a pharmacological strategy to modulate CM subtype composition.
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Affiliation(s)
- Monica Jara-Avaca
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Henning Kempf
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Michael Rückert
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Diana Robles-Diaz
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Annika Franke
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Jeanne de la Roche
- Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg Straße, 30625 Hannover, Germany
| | - Martin Fischer
- Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg Straße, 30625 Hannover, Germany
| | - Daniela Malan
- Institute of Physiology I, Life & Brain Center, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany
| | - Philipp Sasse
- Institute of Physiology I, Life & Brain Center, University of Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany
| | - Wladimir Solodenko
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 38, 30167 Hannover, Germany
| | - Gerald Dräger
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 38, 30167 Hannover, Germany
| | - Andreas Kirschning
- Center of Biomolecular Drug Research (BMWZ), Institute of Organic Chemistry, Leibniz University Hannover, Schneiderberg 38, 30167 Hannover, Germany
| | - Ulrich Martin
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany
| | - Robert Zweigerdt
- Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, REBIRTH-Cluster of Excellence, Hannover Medical School, Carl-Neuberg Straße 1, 30625 Hannover, Germany.
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50
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Seki T, Goto K, Kiyohara K, Kansui Y, Murakami N, Haga Y, Ohtsubo T, Matsumura K, Kitazono T. Downregulation of Endothelial Transient Receptor Potential Vanilloid Type 4 Channel and Small-Conductance of Ca2+-Activated K+ Channels Underpins Impaired Endothelium-Dependent Hyperpolarization in Hypertension. Hypertension 2016; 69:143-153. [PMID: 27872234 DOI: 10.1161/hypertensionaha.116.07110] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 09/01/2016] [Accepted: 10/31/2016] [Indexed: 01/24/2023]
Abstract
Endothelium-dependent hyperpolarization (EDH)-mediated responses are impaired in hypertension, but the underlying mechanisms have not yet been determined. The activation of small- and intermediate-conductance of Ca2+-activated K+ channels (SKCa and IKCa) underpins EDH-mediated responses. It was recently reported that Ca2+ influx through endothelial transient receptor potential vanilloid type 4 channel (TRPV4) is a prerequisite for the activation of SKCa/IKCa in endothelial cells in specific beds. Here, we attempted to determine whether the impairment of EDH in hypertension is attributable to the dysfunction of TRPV4 and S/IKCa, using isolated superior mesenteric arteries of 20-week-old stroke-prone spontaneously hypertensive rats (SHRSP) and age-matched Wistar-Kyoto (WKY) rats. In the WKY arteries, EDH-mediated responses were reduced by a combination of SKCa/IKCa blockers (apamin plus TRAM-34; 1-[(2-chlorophenyl)diphenylmethl]-1H-pyrazole) and by the blockade of TRPV4 with the selective antagonist RN-1734 or HC-067047. In the SHRSP arteries, EDH-mediated hyperpolarization and relaxation were significantly impaired when compared with WKY. GSK1016790A, a selective TRPV4 activator, evoked robust hyperpolarization and relaxation in WKY arteries. In contrast, in SHRSP arteries, the GSK1016790A-evoked hyperpolarization was small and relaxation was absent. Hyperpolarization and relaxation to cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine, a selective SKCa activator, were marginally decreased in SHRSP arteries compared with WKY arteries. The expression of endothelial TRPV4 and SKCa protein was significantly decreased in the SHRSP mesenteric arteries compared with those of WKY, whereas function and expression of IKCa were preserved in SHRSP arteries. These findings suggest that EDH-mediated responses are impaired in superior mesenteric arteries of SHRSP because of a reduction in both TRPV4 and SKCa input to EDH.
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Affiliation(s)
- Takunori Seki
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kenichi Goto
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Kanako Kiyohara
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yasuo Kansui
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Noboru Murakami
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshie Haga
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toshio Ohtsubo
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kiyoshi Matsumura
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Takanari Kitazono
- From the Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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