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Konnova EA, Deftu AF, Chu Sin Chung P, Kirschmann G, Decosterd I, Suter MR. Potassium channel modulation in macrophages sensitizes dorsal root ganglion neurons after nerve injury. Glia 2024; 72:677-691. [PMID: 38108588 DOI: 10.1002/glia.24496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/19/2023]
Abstract
Macrophages and satellite glial cells are found between injured and uninjured neurons in the lumbar dorsal root ganglia (DRG). We explored the mechanism of neuro-immune and neuron-glia crosstalk leading to hyperexcitability of DRG neurons. After spared nerve injury (SNI), CX3CR1+ resident macrophages became activated, proliferated, and increased inward-rectifying potassium channel Kir 2.1 currents. Conditioned medium (CM) by macrophages, obtained from DRG of SNI mice, sensitized small DRG neurons from naïve mice. However, treatment with CM from GFAP+ glial cells did not affect neuronal excitability. When subjected to this macrophage-derived CM, DRG neurons had increased spontaneous activity, current-evoked responses and voltage-gated NaV 1.7 and NaV 1.8 currents. Silencing Kir 2.1 in macrophages after SNI prevented the induction of neuronal hyperexcitability from their CM. Blocking vesicular exocytosis or soluble tumor necrosis factor in CM or interfering with the downstream intracellular p38 pathway in neurons, also prevented neuronal hyperexcitability. Blocking protein trafficking in neurons reduced the effect of CM, suggesting that the hyperexcitable state resulted from changes in NaV channel trafficking. These results suggest that DRG macrophages, primed by peripheral nerve injury, contribute to neuron-glia crosstalk, NaV channel dysregulation and neuronal hyperexcitability implicated in the development of neuropathic pain.
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Affiliation(s)
- Elena A Konnova
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Alexandru-Florian Deftu
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Paul Chu Sin Chung
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Guylène Kirschmann
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Isabelle Decosterd
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
- Department of Fundamental Neurosciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Marc R Suter
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland
- Department of Fundamental Neurosciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Guo H, Xin Y, Wang S, Zhang X, Ren Y, Qiao B, Li H, Wu J, Hao X, Xu L, Yan Y, Zhang H. Hypothalamic POMC neuron-specific knockout of MC4R affects insulin sensitivity by regulating Kir2.1. Mol Med 2024; 30:34. [PMID: 38448811 PMCID: PMC10918880 DOI: 10.1186/s10020-024-00804-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/23/2024] [Indexed: 03/08/2024] Open
Abstract
BACKGROUND Imbalance in energy regulation is a major cause of insulin resistance and diabetes. Melanocortin-4 receptor (MC4R) signaling at specific sites in the central nervous system has synergistic but non-overlapping functions. However, the mechanism by which MC4R in the arcuate nucleus (ARC) region regulates energy balance and insulin resistance remains unclear. METHODS The MC4Rflox/flox mice with proopiomelanocortin (POMC) -Cre mice were crossed to generate the POMC-MC4Rflox/+ mice. Then POMC-MC4Rflox/+ mice were further mated with MC4Rflox/flox mice to generate the POMC-MC4Rflox/flox mice in which MC4R is selectively deleted in POMC neurons. Bilateral injections of 200 nl of AAV-sh-Kir2.1 (AAV-sh-NC was used as control) were made into the ARC of the hypothalamus. Oxygen consumption, carbon dioxide production, respiratory exchange ratio and energy expenditure were measured by using the CLAMS; Total, visceral and subcutaneous fat was analyzed using micro-CT. Co-immunoprecipitation assays (Co-IP) were used to analyze the interaction between MC4R and Kir2.1 in GT1-7 cells. RESULTS POMC neuron-specific ablation of MC4R in the ARC region promoted food intake, impaired energy expenditure, leading to increased weight gain and impaired systemic glucose homeostasis. Additionally, MC4R ablation reduced the activation of POMC neuron, and is not tissue-specific for peripheral regulation, suggesting the importance of its central regulation. Mechanistically, sequencing analysis and Co-IP assay demonstrated a direct interaction of MC4R with Kir2.1. Knockdown of Kir2.1 in POMC neuron-specific ablation of MC4R restored the effect of MC4R ablation on energy expenditure and systemic glucose homeostasis, indicating by reduced body weight and ameliorated insulin resistance. CONCLUSION Hypothalamic POMC neuron-specific knockout of MC4R affects energy balance and insulin sensitivity by regulating Kir2.1. Kir2.1 represents a new target and pathway that could be targeted in obesity.
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Affiliation(s)
- Hengru Guo
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Ying Xin
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Saifei Wang
- Department of Endocrinology, Third People's Hospital, Zhengzhou, China
| | - Xiaoning Zhang
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Yanqi Ren
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Bo Qiao
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Hongjiang Li
- Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jing Wu
- Department of Pediatrics, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiao Hao
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Lijun Xu
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Yushan Yan
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China
| | - Haohao Zhang
- Department of Endocrinology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, Henan, China.
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Beverley KM, Levitan I. Cholesterol regulation of mechanosensitive ion channels. Front Cell Dev Biol 2024; 12:1352259. [PMID: 38333595 PMCID: PMC10850386 DOI: 10.3389/fcell.2024.1352259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/17/2024] [Indexed: 02/10/2024] Open
Abstract
The purpose of this review is to evaluate the role of cholesterol in regulating mechanosensitive ion channels. Ion channels discussed in this review are sensitive to two types of mechanical signals, fluid shear stress and/or membrane stretch. Cholesterol regulates the channels primarily in two ways: 1) indirectly through localizing the channels into cholesterol-rich membrane domains where they interact with accessory proteins and/or 2) direct binding of cholesterol to the channel at specified putative binding sites. Cholesterol may also regulate channel function via changes of the biophysical properties of the membrane bilayer. Changes in cholesterol affect both mechanosensitivity and basal channel function. We focus on four mechanosensitive ion channels in this review Piezo, Kir2, TRPV4, and VRAC channels. Piezo channels were shown to be regulated by auxiliary proteins that enhance channel function in high cholesterol domains. The direct binding mechanism was shown in Kir2.1 and TRPV4 where cholesterol inhibits channel function. Finally, cholesterol regulation of VRAC was attributed to changes in the physical properties of lipid bilayer. Additional studies should be performed to determine the physiological implications of these sterol effects in complex cellular environments.
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Affiliation(s)
- Katie M. Beverley
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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Benzoni P, Gazzerro E, Fiorillo C, Baratto S, Bartolucci C, Severi S, Milanesi R, Lippi M, Langione M, Murano C, Meoni C, Popolizio V, Cospito A, Baruscotti M, Bucchi A, Barbuti A. Caveolin-3 and Caveolin-1 Interaction Decreases Channel Dysfunction Due to Caveolin-3 Mutations. Int J Mol Sci 2024; 25:980. [PMID: 38256054 PMCID: PMC10816214 DOI: 10.3390/ijms25020980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/15/2023] [Accepted: 01/03/2024] [Indexed: 01/24/2024] Open
Abstract
Caveolae constitute membrane microdomains where receptors and ion channels functionally interact. Caveolin-3 (cav-3) is the key structural component of muscular caveolae. Mutations in CAV3 lead to caveolinopathies, which result in both muscular dystrophies and cardiac diseases. In cardiomyocytes, cav-1 participates with cav-3 to form caveolae; skeletal myotubes and adult skeletal fibers do not express cav-1. In the heart, the absence of cardiac alterations in the majority of cases may depend on a conserved organization of caveolae thanks to the expression of cav-1. We decided to focus on three specific cav-3 mutations (Δ62-64YTT; T78K and W101C) found in heterozygosis in patients suffering from skeletal muscle disorders. We overexpressed both the WT and mutated cav-3 together with ion channels interacting with and modulated by cav-3. Patch-clamp analysis conducted in caveolin-free cells (MEF-KO), revealed that the T78K mutant is dominant negative, causing its intracellular retention together with cav-3 WT, and inducing a significant reduction in current densities of all three ion channels tested. The other cav-3 mutations did not cause significant alterations. Mathematical modelling of the effects of cav-3 T78K would impair repolarization to levels incompatible with life. For this reason, we decided to compare the effects of this mutation in other cell lines that endogenously express cav-1 (MEF-STO and CHO cells) and to modulate cav-1 expression with an shRNA approach. In these systems, the membrane localization of cav-3 T78K was rescued in the presence of cav-1, and the current densities of hHCN4, hKv1.5 and hKir2.1 were also rescued. These results constitute the first evidence of a compensatory role of cav-1 in the heart, justifying the reduced susceptibility of this organ to caveolinopathies.
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Affiliation(s)
- Patrizia Benzoni
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Elisabetta Gazzerro
- Unit of Muscle Research, Experimental and Clinical Research Center, Cooperation between the Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association and Charité-University Berlin, 13125 Berlin, Germany
| | - Chiara Fiorillo
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, DINOGMI-University of Genova, 16147 Genova, Italy
| | - Serena Baratto
- Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Chiara Bartolucci
- Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, 47521 Cesena, Italy
| | - Stefano Severi
- Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, 47521 Cesena, Italy
| | - Raffaella Milanesi
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Melania Lippi
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Marianna Langione
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Carmen Murano
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Clarissa Meoni
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Vera Popolizio
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Alessandro Cospito
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Mirko Baruscotti
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Annalisa Bucchi
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
| | - Andrea Barbuti
- The Cell Physiology MiLab, Department of Biosciences, Università degli Studi di Milano, 20133 Milan, Italy
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Terzi F, Knabbe J, Cambridge SB. In Vivo Optical Interrogation of Neuronal Responses to Genetic, Cell Type-Specific Silencing. J Neurosci 2023; 43:8607-8620. [PMID: 37923378 PMCID: PMC10727181 DOI: 10.1523/jneurosci.2253-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/05/2023] [Accepted: 06/26/2023] [Indexed: 11/07/2023] Open
Abstract
We established a low background, Cre-dependent version of the inducible Tet-On system for fast, cell type-specific transgene expression in vivo Coexpression of a constitutive, Cre-dependent fluorescent marker selectively allowed single-cell analyses before and after inducible, Tet-dependent transgene expression. Here, we used this method for precise, acute manipulation of neuronal activity in the living brain. The goal was to study neuronal network homeostasis at cellular resolution. Single induction of the potassium channel Kir2.1 produced cell type-specific silencing within hours that lasted for at least 3 d. Longitudinal in vivo imaging of spontaneous calcium transients and neuronal morphology demonstrated that prolonged silencing did not alter spine densities or synaptic input strength. Furthermore, selective induction of Kir2.1 in parvalbumin interneurons increased the activity of surrounding neurons in a distance-dependent manner. This high-resolution, inducible interference and interval imaging of individual cells (high I5, HighFive) method thus allows visualizing temporally precise, genetic perturbations of defined cells.SIGNIFICANCE STATEMENT Gene function is studied by KO or overexpression of a specific gene followed by analyses of phenotypic changes. However, being able to predict and analyze exactly those cells in which genetic manipulation will occur is not possible. We combined two prominent transgene overexpression methods to fluorescently highlight the targeted cells appropriately before cell type-specific transgene induction. By inducing a potassium channel that decreases neuronal firing, we investigated how neuronal networks in the living mouse brain possibly compensate swift changes in cellular activities. Unlike in vitro, known compensatory homeostatic mechanisms, such as changes in synapses, were not observed in vivo Overall, we demonstrated with our method rapid genetic manipulation and analysis of neuronal activities as well as precision transgene expression.
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Affiliation(s)
- Firat Terzi
- Heidelberg University, Heidelberg, 69120, Germany
| | | | - Sidney B Cambridge
- Heidelberg University, Heidelberg, 69120, Germany
- Dr. Senckenberg Anatomy, Institute for Anatomy II, Goethe-University Frankfurt am Main, Frankfurt, 60590, Germany
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Fang X, Border JJ, Rivers PL, Zhang H, Williams JM, Fan F, Roman RJ. Amyloid beta accumulation in TgF344-AD rats is associated with reduced cerebral capillary endothelial Kir2.1 expression and neurovascular uncoupling. GeroScience 2023; 45:2909-2926. [PMID: 37326915 PMCID: PMC10643802 DOI: 10.1007/s11357-023-00841-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 05/25/2023] [Indexed: 06/17/2023] Open
Abstract
Alzheimer's disease (AD) exerts a tremendous socio-economic burden worldwide. Although reduced cerebral blood flow is an early and persistent symptom that precedes the loss of cognitive function in AD, the underlying molecular and cellular mechanisms remain unclear. The present study investigated whether capillary endothelial inward rectifier potassium 2 (Kir2.1) expression is reduced in TgF344-AD (AD) rats and contributes to neurovascular uncoupling and cognitive deficits in AD. Three- to fourteen-month-old AD rats expressing mutant human APP and PS1 and age-matched wild-type (WT) F344 rats were studied. AD rats exhibited higher amyloid beta (Aβ) expression in the brain as early as 3 months of age and amyloid plaques by 4 months of age. Functional hyperemic responses induced by whisker stimulation were impaired at 4 months of age, which were exacerbated in 6-month- and 14-month-old AD rats. The expression of Kir2.1 protein was significantly lower in the brains of 6-month-old AD versus WT rats, and Kir2.1 coverage was lower in the cerebral microvasculature of AD than in WT rats. Aβ1-42 reduced the Kir2.1 expression in cultured capillary endothelial cells. Cerebral parenchymal arterioles with attached capillaries exhibited a reduced vasodilator in response to 10 mM K+ applied to capillaries, and constricted less following administration of a Kir2.1 channel blocker, compared to WT vessels. These results indicate that capillary endothelial Kir2.1 expression is reduced and contributes to impaired functional hyperemia in AD rats at early ages, perhaps secondary to elevated Aβ expression.
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Affiliation(s)
- Xing Fang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Jane J Border
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Patrice L Rivers
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Huawei Zhang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Jan Michael Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA
| | - Fan Fan
- Department of Physiology, Medical College of Georgia, Augusta University, 1462 Laney Walker Blvd, Augusta, GA, 30912, USA.
| | - Richard J Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
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Fancher IS, Levitan I. Membrane Cholesterol Interactions with Proteins in Hypercholesterolemia-Induced Endothelial Dysfunction. Curr Atheroscler Rep 2023; 25:535-541. [PMID: 37418067 PMCID: PMC10471518 DOI: 10.1007/s11883-023-01127-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2023] [Indexed: 07/08/2023]
Abstract
PURPOSE OF REVIEW The goal of this review is to highlight work identifying mechanisms driving hypercholesterolemia-mediated endothelial dysfunction. We specifically focus on cholesterol-protein interactions and address specific questions related to the impact of hypercholesterolemia on cellular cholesterol and vascular endothelial function. We describe key approaches used to determine the effects of cholesterol-protein interactions in mediating endothelial dysfunction under dyslipidemic conditions. RECENT FINDINGS The benefits of removing the cholesterol surplus on endothelial function in models of hypercholesterolemia is clear. However, specific mechanisms driving cholesterol-induced endothelial dysfunction need to be determined. In this review, we detail the latest findings describing cholesterol-mediated endothelial dysfunction, highlighting our studies indicating that cholesterol suppresses endothelial Kir2.1 channels as a major underlying mechanism. The findings detailed in this review support the targeting of cholesterol-induced suppression of proteins in restoring endothelial function in dyslipidemic conditions. The identification of similar mechanisms regarding other cholesterol-endothelial protein interactions is warranted.
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Affiliation(s)
- Ibra S. Fancher
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, DE USA
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL USA
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8
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Ozekin YH, Saal ML, Pineda RH, Moehn K, Ordonez-Erives MA, Delgado Figueroa MF, Frazier C, Korth KM, Königshoff M, Bates EA, Vladar EK. Intrauterine exposure to nicotine through maternal vaping disrupts embryonic lung and skeletal development via the Kcnj2 potassium channel. Dev Biol 2023; 501:111-123. [PMID: 37353105 PMCID: PMC10445547 DOI: 10.1016/j.ydbio.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 06/01/2023] [Accepted: 06/06/2023] [Indexed: 06/25/2023]
Abstract
Smoking cigarettes during pregnancy is associated with adverse effects on infants including low birth weight, defective lung development, and skeletal abnormalities. Pregnant women are increasingly turning to vaping [use of electronic (e)-cigarettes] as a perceived safer alternative to cigarettes. However, nicotine disrupts fetal development, suggesting that like cigarette smoking, nicotine vaping may be detrimental to the fetus. To test the impact of maternal vaping on fetal lung and skeletal development in mice, pregnant dams were exposed to e-cigarette vapor throughout gestation. At embryonic day (E)18.5, vape exposed litter sizes were reduced, and some embryos exhibited growth restriction compared to air exposed controls. Fetal lungs were collected for histology and whole transcriptome sequencing. Maternally nicotine vaped embryos exhibited histological and transcriptional changes consistent with impaired distal lung development. Embryonic lung gene expression changes mimicked transcriptional changes observed in adult mouse lungs exposed to cigarette smoke, suggesting that the developmental defects may be due to direct nicotine exposure. Fetal skeletons were analyzed for craniofacial and long bone lengths. Nicotine directly binds and inhibits the Kcnj2 potassium channel which is important for bone development. The length of the maxilla, palatal shelves, humerus, and femur were reduced in vaped embryos, which was further exacerbated by loss of one copy of the Kcnj2 gene. Nicotine vapor exposed Kcnj2KO/+ embryos also had significantly lower birth weights than unexposed animals of either genotype. Kcnj2 mutants had severely defective lungs with and without vape exposure, suggesting that potassium channels may be broadly involved in mediating the detrimental developmental effects of nicotine vaping. These data indicate that intrauterine nicotine exposure disrupts fetal lung and skeletal development likely through inhibition of Kcnj2.
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Affiliation(s)
- Yunus H Ozekin
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Maxwell L Saal
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Ricardo H Pineda
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kayla Moehn
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Madison A Ordonez-Erives
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Maria F Delgado Figueroa
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Caleb Frazier
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kamryn M Korth
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Melanie Königshoff
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Emily A Bates
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Eszter K Vladar
- Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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9
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Rong Y, Zhou X, Guo Z, Zhang Y, Qin W, Li L, Si J, Yang R, Li X, Ma K. Activation of Kir2.1 improves myocardial fibrosis by inhibiting Ca 2+ overload and the TGF-β1/Smad signaling pathway. Acta Biochim Biophys Sin (Shanghai) 2023. [PMID: 37184279 DOI: 10.3724/abbs.2023083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
The inwardly rectifying potassium channel Kir2.1 is closely associated with many cardiovascular diseases. However, the effect and mechanism of Kir2.1 in diabetic cardiomyopathy remain unclear. In vivo, we use STZ to establish the model, and ventricular structural changes, myocardial inflammatory infiltration, and myocardial fibrosis severity are detected by echocardiography, histological staining, immunohistochemistry, and western blot analysis, respectively. In vitro, a myocardial fibrosis model is established with high glucose. The Kir2.1 current amplitude, intracellular calcium concentration, fibrosis-related proteins, and TGF-β1/Smad pathway proteins are detected by whole-cell patch clamp, calcium probes, western blot analysis, and immunofluorescence, respectively. The in vivo results show that compared to diabetic cardiomyopathy, zacopride (a Kir2.1 selective agonist) significantly reduces the left ventricular systolic diameter and diastolic diameter, increases the left ventricular ejection fraction and left ventricular short-axis shortening, improves the degree of cell necrosis, and reduces the expression of myocardial interstitial fibrosis protein and collagen fibre deposition area. The in vitro results show that the current amplitude and protein expression of Kir2.1 are both decreased in the high glucose-induced myocardial fibrosis model. Additionally, zacopride significantly upregulates the expression of Kir2.1 and inhibits the expressions of the fibrosis-related proteins α-SMA, collagen I, and collagen III. Activation of Kir2.1 reduces the intracellular calcium concentration and inhibits the protein expressions of TGF-β1 and p-Smad 2/3. Activation of Kir2.1 can improve myocardial fibrosis induced by diabetic cardiomyopathy, and the possible mechanism may be related to inhibiting Ca 2+ overload and the TGF-β1/Smad signaling pathway.
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Affiliation(s)
- Yi Rong
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
| | - Xin Zhou
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
| | - Zhenli Guo
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
| | - Yingying Zhang
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
| | - Wenjuan Qin
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
| | - Li Li
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
| | - Junqiang Si
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
| | - Rui Yang
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
| | - Xinzhi Li
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Pathophysiology, Shihezi University Medical College, Shihezi 832002, China
| | - Ketao Ma
- The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University Medical College, Shihezi 832002, China
- NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence Diseases, Shihezi 832002, China
- Department of Physiology, Shihezi University Medical College, Shihezi 832002, China
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10
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Iijima A, Švecová O, Hošek J, Kula R, Bébarová M. Sildenafil affects the human Kir2.1 and Kir2.2 channels at clinically relevant concentrations: Inhibition potentiated by low Ba 2. Front Pharmacol 2023; 14:1136272. [PMID: 36817146 PMCID: PMC9932908 DOI: 10.3389/fphar.2023.1136272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Sildenafil (Viagra), the first approved and widely used oral drug for the treatment of erectile dysfunction, was occasionally associated with life-threatening ventricular arrhythmias in patients. Since inward rectifier potassium current (I K1) may considerably contribute to this arrhythmogenesis, we investigated the effect of sildenafil on the human Kir2.1 and Kir2.2, the prevailing subunits forming the ventricular I K1 channels. Experiments were performed by the whole-cell patch clamp technique at 37°C using Chinese hamster ovary cells transiently expressing the human Kir2.1 and Kir2.2 channels. Changes of both the inward and outward current components (at -110 and -50 mV, respectively) were tested to be able to consider the physiological relevance of the sildenafil effect (changes at -110 and -50 mV did not significantly differ, results at -50 mV are listed below). A significant Kir2.1 inhibition was observed at all applied sildenafil concentrations (16.1% ± 3.7%, 20.0% ± 2.6%, and 15.0% ± 3.0% at 0.1, 1, and 10 μM, respectively). The inhibitory effect of 0.1 μM sildenafil was potentiated by the presence of a low concentration of Ba2+ (0.1 μM) which induced only a slight Kir2.1 inhibition by 5.95% ± 0.75% alone (the combined effect was 35.5% ± 3.4%). The subtherapeutic and therapeutic sildenafil concentrations (0.1 and 1 μM) caused a dual effect on Kir2.2 channels whereas a significant Kir2.2 activation was observed at the supratherapeutic sildenafil concentration (10 μM: 34.1% ± 5.6%). All effects were fully reversible. This is the first study demonstrating that sildenafil at clinically relevant concentrations inhibits both the inward and outward current components of the main human ventricular I K1 subunit Kir2.1. This inhibitory effect was significantly potentiated by a low concentration of environmental contaminant Ba2+ in agreement with recently reported data on rat ventricular I K1 which additionally showed a significant repolarization delay. Considering the similar subunit composition of the human and rat ventricular I K1 channels, the observed effects might contribute to sildenafil-associated arrhythmogenesis in clinical practice.
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Affiliation(s)
- Akimasa Iijima
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Olga Švecová
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Jan Hošek
- Department of Molecular Pharmacy, Faculty of Pharmacy, Masaryk University, Brno, Czech Republic
| | - Roman Kula
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic,*Correspondence: Markéta Bébarová,
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11
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Chen S, Cui W, Chi Z, Xiao Q, Hu T, Ye Q, Zhu K, Yu W, Wang Z, Yu C, Pan X, Dai S, Yang Q, Jin J, Zhang J, Li M, Yang D, Yu Q, Wang Q, Yu X, Yang W, Zhang X, Qian J, Ding K, Wang D. Tumor-associated macrophages are shaped by intratumoral high potassium via Kir2.1. Cell Metab 2022; 34:1843-1859.e11. [PMID: 36103895 DOI: 10.1016/j.cmet.2022.08.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 06/10/2022] [Accepted: 08/17/2022] [Indexed: 01/11/2023]
Abstract
The tumor microenvironment (TME) is a unique niche governed by constant crosstalk within and across all intratumoral cellular compartments. In particular, intratumoral high potassium (K+) has shown immune-suppressive potency on T cells. However, as a pan-cancer characteristic associated with local necrosis, the impact of this ionic disturbance on innate immunity is unknown. Here, we reveal that intratumoral high K+ suppresses the anti-tumor capacity of tumor-associated macrophages (TAMs). We identify the inwardly rectifying K+ channel Kir2.1 as a central modulator of TAM functional polarization in high K+ TME, and its conditional depletion repolarizes TAMs toward an anti-tumor state, sequentially boosting local anti-tumor immunity. Kir2.1 deficiency disturbs the electrochemically dependent glutamine uptake, engendering TAM metabolic reprogramming from oxidative phosphorylation toward glycolysis. Kir2.1 blockade attenuates both murine tumor- and patient-derived xenograft growth. Collectively, our findings reveal Kir2.1 as a determinant and potential therapeutic target for regaining the anti-tumor capacity of TAMs within ionic-imbalanced TME.
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Affiliation(s)
- Sheng Chen
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Wenyu Cui
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Eye Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Zhexu Chi
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Qian Xiao
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Tianyi Hu
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Qizhen Ye
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Kaixiang Zhu
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Weiwei Yu
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Zhen Wang
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Chengxuan Yu
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Xiang Pan
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Siqi Dai
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Qi Yang
- Department of Pathology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Jiacheng Jin
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Jian Zhang
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Mobai Li
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Dehang Yang
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Qianzhou Yu
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Quanquan Wang
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Xiafei Yu
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Wei Yang
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Xue Zhang
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China
| | - Junbin Qian
- Zhejiang Provincial Key Laboratory of Precision Diagnosis and Therapy for Major Gynecological Diseases, Women's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China
| | - Kefeng Ding
- Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Cancer Center, Zhejiang University, Hangzhou 310058, P.R. China.
| | - Di Wang
- Institute of Immunology and Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, P.R. China; Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, P.R. China.
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12
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Chen K, Man Q, Miao J, Xu W, Zheng Y, Zhou X, Gao Z. Kir2.1 channel regulates macrophage polarization via Ca2+/CaMK II/ERK/NF-κB signaling pathway. J Cell Sci 2022; 135:275689. [PMID: 35694964 DOI: 10.1242/jcs.259544] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 06/06/2022] [Indexed: 11/20/2022] Open
Abstract
Macrophage polarization plays a key role in inflammatory response. Various ion channels expressed in macrophages has been documented, but very little is known about their roles in macrophage polarization. We find that knockdown or blockade of Kir2.1 channel significantly inhibits M1 polarization, but promotes M2 polarization. LPS induced M1 polarization is also remarkably suppressed in high extracellular K+ solutions (70 mM K+), and this inhibition is partially abolished by adding Ca2+ in the culture medium. Calcium imaging shows that Ca2+ influx is dependent on the hyperpolarized membrane potential generated by Kir2.1 channel. The upregulation of p-CaMK II, p-ERK1/2, and p-NF-κB proteins in RAW264.7 macrophages stimulated with LPS are significantly reversed by blocking Kir2.1 channel or culturing the cells with 70 mM K+ medium. Furthermore, in vivo study shows that mice treated with Kir2.1 channel blocker are protected from LPS-induced peritonitis. In summary, our data reveal the essential role of Kir2.1 channel in regulating macrophage polarization via Ca2+ / CaMK II / ERK1/2 / NF-κB pathway.
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Affiliation(s)
- Kuihao Chen
- Department of Cardiology, The Affiliated Hospital of Medical School of Ningbo University, 247 Renmin Rd, Ningbo, China.,Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Qiaoyan Man
- Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Jiaen Miao
- Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Wenjing Xu
- Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Yangchen Zheng
- Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Xiuli Zhou
- Department of Pharmacology, Ningbo University School of Medicine, 818 Fenghua Rd, Ningbo, China
| | - Zhe Gao
- Department of Cardiology, The Affiliated Hospital of Medical School of Ningbo University, 247 Renmin Rd, Ningbo, China.,Ningbo Institute of Medical Sciences, 42 Yangshan Rd, Ningbo, China
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13
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Chen L, Wang W, Peng X, Liu L, Zhang A, Li X, Ma K, Wang L. Alpha1-adrenoceptors activate NLRP3 inflammasome through downregulation of Kir2.1 in cardiac inflammation. Exp Physiol 2022; 107:589-600. [PMID: 35363405 DOI: 10.1113/ep090243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 03/29/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? The mechanism of cardiac inflammation induced by α 1 -AR stimulation by NLRP3 inflammasome activation is unclear. What is the main finding and its importance? In the mechanism of cardiac inflammation induced by α1 -AR overreaction, Kir2.1 exerts cardioprotective and anti-inflammatory effects by inhibiting the activation of NLRP3 Inflammasome. ABSTRACT Overstimulated sympathetic nerves in cardiovascular diseases can lead to impaired cardiomyocyte function and potential heart failure, which activates not only β-AR but also α1 -AR. A previous report indicated that NLRP3 inflammasome activation is involved in cardiac inflammation induced by the α1 -AR agonist phenylephrine, but the mechanism is still unknown. Here, we aimed to study whether Kir2.1 is involved in cardiac inflammation caused by phenylephrine. The results from in vitro experiments showed that phenylephrine upregulated the expression levels of NLRP3, Caspase-1, IL-18, and IL-1β and downregulated the expression level of Kir2.1 in H9C2 cells. The Kir2.1 agonist zacopride downregulated the expression of NLRP3, Caspase-1, IL-1β and IL-18, and the Kir2.1 inhibitor ML133 upregulated the expression of these genes. To further explore the mechanism, we found that zacopride downregulated the protein expression level of p-p65 and that ML133 upregulated it. Moreover, the NF-κB signaling pathway inhibitor curcumenol reversed the expression of NLRP3 inflammasomes caused by phenylephrine in H9C2 cells. In vivo experiments, the protein expression level of Kir2.1 in the phenylephrine group was significantly decreased, and the activation of Kir2.1 by zacopride reduced cardiac inflammation. In short, Kir2.1 is related to α1 -AR overactivation, which induces cardiac inflammation, through the NF-κB signaling pathway, and activating Kir2.1 can downregulate NLRP3 inflammation and exert cardioprotective effects by zacopride. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ling Chen
- The 3rd Department of Cardiology, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Wenbo Wang
- The 3rd Department of Cardiology, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Xiangyang Peng
- The 3rd Department of Cardiology, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Luqian Liu
- Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Department of Pathophysiology, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Aimei Zhang
- The 3rd Department of Cardiology, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Xinzhi Li
- Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Department of Pathophysiology, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Ketao Ma
- Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Department of Physiology, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
| | - Li Wang
- The 3rd Department of Cardiology, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Ministry of Education, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China.,NHC Key Laboratory of Prevention and Treatment of Central Asia High Incidence, Diseases, First Affiliated Hospital, Shihezi University School of Medicine, Shihezi, Xinjiang, 832000, China
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14
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Ahn SJ, Le Master E, Lee JC, Phillips SA, Levitan I, Fancher IS. Differential effects of obesity on visceral versus subcutaneous adipose arteries: role of shear-activated Kir2.1 and alterations to the glycocalyx. Am J Physiol Heart Circ Physiol 2022; 322:H156-H166. [PMID: 34890278 PMCID: PMC8742723 DOI: 10.1152/ajpheart.00399.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Obesity imposes well-established deficits to endothelial function. We recently showed that obesity-induced endothelial dysfunction was mediated by disruption of the glycocalyx and a loss of Kir channel flow sensitivity. However, obesity-induced endothelial dysfunction is not observed in all vascular beds: visceral adipose arteries (VAAs), but not subcutaneous adipose arteries (SAAs), exhibit endothelial dysfunction. To determine whether differences in SAA versus VAA endothelial function observed in obesity are attributed to differential impairment of Kir channels and alterations to the glycocalyx, mice were fed a normal rodent diet, or a high-fat Western diet to induce obesity. Flow-induced vasodilation (FIV) was measured ex vivo. Functional downregulation of endothelial Kir2.1 was accomplished by transducing adipose arteries from mice and obese humans with adenovirus containing a dominant-negative Kir2.1 construct. Kir function was tested in freshly isolated endothelial cells seeded in a flow chamber for electrophysiological recordings under fluid shear. Atomic force microscopy was used to assess biophysical properties of the glycocalyx. Endothelial dysfunction was observed in VAAs of obese mice and humans. Downregulating Kir2.1 blunted FIV in SAAs, but had no effect on VAAs, from obese mice and humans. Obesity abolished Kir shear sensitivity in VAA endothelial cells and significantly altered the VAA glycocalyx. In contrast, Kir shear sensitivity was observed in SAA endothelial cells from obese mice and effects on SAA glycocalyx were less pronounced. We reveal distinct differences in Kir function and alterations to the glycocalyx that we propose contribute to the dichotomy in SAA versus VAA endothelial function with obesity.NEW & NOTEWORTHY We identified a role for endothelial Kir2.1 in the differences observed in VAA versus SAA endothelial function with obesity. The endothelial glycocalyx, a regulator of Kir activation by shear, is unequally perturbed in VAAs as compared with SAAs, which we propose results in a near complete loss of VAA endothelial Kir shear sensitivity and endothelial dysfunction. We propose that these differences underly the preserved endothelial function of SAA in obese mice and humans.
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Affiliation(s)
- Sang Joon Ahn
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Elizabeth Le Master
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - James C. Lee
- 2Department of Biomedical Engineering, University of Illinois at Chicago, Chicago, Illinois
| | - Shane A. Phillips
- 3Department of Physical Therapy, College of Applied Health Sciences,
University of Illinois at Chicago, Chicago, Illinois
| | - Irena Levitan
- 1Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Ibra S. Fancher
- 4Department of Kinesiology and Applied Physiology, College of Health
Sciences, University of Delaware, Newark, Delaware
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15
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Van de Sande DV, Kopljar I, Maaike A, Teisman A, Gallacher DJ, Bart L, Snyders DJ, Leybaert L, Lu HR, Labro AJ. The resting membrane potential of hSC-CM in a syncytium is more hyperpolarised than that of isolated cells. Channels (Austin) 2021; 15:239-252. [PMID: 33465001 PMCID: PMC7817136 DOI: 10.1080/19336950.2021.1871815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/20/2020] [Accepted: 12/31/2020] [Indexed: 01/11/2023] Open
Abstract
Human-induced pluripotent stem cell (hiPSC) and stem cell (hSC) derived cardiomyocytes (CM) are gaining popularity as in vitro model for cardiology and pharmacology studies. A remaining flaw of these cells, as shown by single-cell electrophysiological characterization, is a more depolarized resting membrane potential (RMP) compared to native CM. Most reports attribute this to a lower expression of the Kir2.1 potassium channel that generates the IK1 current. However, most RMP recordings are obtained from isolated hSC/hiPSC-CMs whereas in a more native setting these cells are interconnected with neighboring cells by connexin-based gap junctions, forming a syncytium. Hereby, these cells are electrically connected and the total pool of IK1 increases. Therefore, the input resistance (Ri) of interconnected cells is lower than that of isolated cells. During patch clamp experiments pipettes need to be well attached or sealed to the cell, which is reflected in the seal resistance (Rs), because a nonspecific ionic current can leak through this pipette-cell contact or seal and balance out small currents within the cell such as IK1. By recording the action potential of isolated hSC-CMs and that of hSC-CMs cultured in small monolayers, we show that the RMP of hSC-CMs in monolayer is approximately -20 mV more hyperpolarized compared to isolated cells. Accordingly, adding carbenoxolone, a connexin channel blocker, isolates the cell that is patch clamped from its neighboring cells of the monolayer and depolarizes the RMP. The presented data show that the recorded RMP of hSC-CMs in a syncytium is more negative than that determined from isolated hSC/hiPSC-CMs, most likely because the active pool of Kir2.1 channels increased.
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Affiliation(s)
| | - Ivan Kopljar
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alaerts Maaike
- Centre of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Ard Teisman
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - David J. Gallacher
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Loeys Bart
- Centre of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Dirk J. Snyders
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Hua Rong Lu
- Global Safety Pharmacology, Non-Clinical Safety, Janssen R&D, Beerse, Belgium
| | - Alain J. Labro
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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16
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Klose E, Kuhrt H, Kohen L, Wiedemann P, Bringmann A, Hollborn M. Hypoxic and osmotic expression of Kir2.1 potassium channels in retinal pigment epithelial cells: Contribution to vascular endothelial growth factor expression. Exp Eye Res 2021; 211:108741. [PMID: 34425102 DOI: 10.1016/j.exer.2021.108741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/22/2021] [Accepted: 08/19/2021] [Indexed: 12/31/2022]
Abstract
Retinal pigment epithelial (RPE) cells express different subtypes of inwardly rectifying potassium (Kir) channels. We investigated whether human and rat RPE cells express genes of strongly rectifying Kir2 channels. We also determined the hypoxic and hyperosmotic regulation of Kir2.1 gene expression in cultured human RPE cells and the effects of siRNA-mediated knockdown of Kir2.1 on VEGFA expression, VEGF secretion, proliferation, and viability of the cells. Extracellular hyperosmolarity was induced by addition of NaCl or sucrose. Hypoxia and chemical hypoxia were produced by cell culture in 0.25% O2 and addition of CoCl2, respectively. Gene expression levels were evaluated by real-time RT-PCR. Rat RPE cells contained Kir2.1, Kir2.2, Kir2.3, and Kir2.4 gene transcripts while human RPE cells contained Kir2.1, Kir2.2, and Kir2.4 transcripts. Immunocytochemical data may suggest that Kir2.1 protein in cultured human cells is expressed in both perinuclear and plasma membranes. Kir2.1 gene expression and Kir2.1 protein level in human cells increased under hypoxic and hyperosmotic conditions. The expression of the Kir2.1 gene was mediated in part by diverse intracellular signal transduction pathways and transcription factor activities under both conditions; the hyperosmotic, but not the CoCl2-induced Kir2.1 gene expression was dependent on intracellular calcium signaling. Autocrine/paracrine activation of purinergic receptors contributed to Kir2.1 gene expression under hyperosmotic (P2Y1, P2Y2, P2X7) and CoCl2-induced conditions (P2Y2, P2X7). Exogenous VEGF, TGF-β1, and blood serum decreased Kir2.1 gene expression. Inhibition of VEGF receptor-2 increased the Kir2.1 gene expression under control conditions and in CoCl2-simulated hypoxia, and decreased it under high NaCl conditions. Knockdown of Kir2.1 by siRNA inhibited the CoCl2-induced and hyperosmotic transcription of the VEGFA gene and caused a delayed decrease of the constitutive VEGFA gene expression while VEGF protein secretion was not altered. Kir2.1 knockdown stimulated RPE cell proliferation under control and hyperosmotic conditions without affecting cell viability. The data indicate that Kir2.1 channel activity is required for the expression of the VEGFA gene and inhibits the proliferation of RPE cells. Under control and hypoxic conditions, the extracellular VEGF level may regulate the production of VEGF via its inhibitory effect on the Kir2.1 gene transcription; this feedback loop may prevent overproduction of VEGF.
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Affiliation(s)
- Eva Klose
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Heidrun Kuhrt
- Institute of Anatomy, University of Leipzig, Germany
| | - Leon Kohen
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany; Helios Klinikum Aue, Aue, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
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He Y, Wang G, Gao H, Liu Y, Li H, Feng Y, Tang J. Prolonged duration of repolarization and decreased conduction velocity in the atrial myocardium after hypothermic ischemia-reperfusion may be related to expressions of inward rectifier potassium channel 2.1 protein and connexin 40. Perfusion 2021; 36:146-153. [PMID: 32650696 DOI: 10.1177/0267659120934612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The study aimed to determine the role of inward rectifier potassium channel 2.1 protein and connexin 40 expressions in regulating the duration of repolarization and conduction velocity of right atrial myocardium in rats following hypothermic ischemia-reperfusion. METHODS The Langendorff isolated rat cardiac perfusion models were divided into control (C) and hypothermic ischemia-reperfusion groups, with 8 models in group C and 16 models in group ischemia-reperfusion. Depending on the incidence of atrial arrhythmia after reperfusion, the models in group ischemia-reperfusion were further divided into reperfusion non-atrial arrhythmia or reperfusion atrial arrhythmia subgroup. Right atrial monophasic action potential duration at 50% and 90% of repolarization after 30 minutes of continuous perfusion in group C and group ischemia-reperfusion (T0), 105 minutes of continuous perfusion in group C or after 15 minutes of reperfusion in group ischemia-reperfusion (T1) and 120 minutes of continuous perfusion in group C or 30 minutes of reperfusion in group ischemia-reperfusion (T2) were recorded. Right atrial conduction velocity and effective refractory period were recorded at T2. Then, the expressions of inward rectifier potassium channel 2.1 protein and connexin 40 in the right atrial myocardium were detected. RESULTS Monophasic action potential duration at 50% and 90% were higher at T1 and T2 than those at T0 in subgroup reperfusion atrial arrhythmia (p < 0.05); monophasic action potential duration at 50% in subgroup reperfusion atrial arrhythmia were larger than group C and subgroup reperfusion non-atrial arrhythmia at T1 and T2 (p < 0.05); monophasic action potential duration at 90% in subgroup reperfusion atrial arrhythmia were larger than group C and subgroup reperfusion non-atrial arrhythmia at T1 and T2 (p < 0.05); effective refractory period in subgroup reperfusion atrial arrhythmia was greater than that in group C and subgroup reperfusion non-atrial arrhythmia, and the conduction velocity and the expressions of inward rectifier potassium channel 2.1 protein and connexin 40 were significantly lower than group C and subgroup reperfusion non-atrial arrhythmia (p < 0.05). CONCLUSIONS The prolonged duration of repolarization and a decrease in conduction velocity of the atrial myocardium occur in rats after hypothermic ischemia-reperfusion. These observed effects may be related to the downregulated expressions of connexin 40 and inward rectifier potassium channel 2.1.
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Affiliation(s)
- Youqin He
- School of Anesthesiology, Guizhou Medical University, Guiyang, P.R. China
| | - Guilong Wang
- Department of Anesthesiology, The People's Hospital of Zhijin County, Bijie, P.R. China
| | - Hong Gao
- The Third Affiliated Hospital of Guizhou Medical University, Duyun, P.R. China
| | - Yanqiu Liu
- Department of Anesthesiology, The Affiliated Hospital of Guizhou Medical University, Guiyang, P.R. China
| | - Huayu Li
- School of Anesthesiology, Guizhou Medical University, Guiyang, P.R. China
| | - Yurong Feng
- School of Anesthesiology, Guizhou Medical University, Guiyang, P.R. China
| | - Jian Tang
- School of Anesthesiology, Guizhou Medical University, Guiyang, P.R. China
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Mughal A, Harraz OF, Gonzales AL, Hill-Eubanks D, Nelson MT. PIP 2 Improves Cerebral Blood Flow in a Mouse Model of Alzheimer's Disease. Function (Oxf) 2021; 2:zqab010. [PMID: 33763649 PMCID: PMC7955025 DOI: 10.1093/function/zqab010] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 02/05/2023]
Abstract
Alzheimer's disease (AD) is a leading cause of dementia and a substantial healthcare burden. Despite this, few treatment options are available for controlling AD symptoms. Notably, neuronal activity-dependent increases in cortical cerebral blood flow (CBF; functional hyperemia) are attenuated in AD patients, but the associated pathological mechanisms are not fully understood at the molecular level. A fundamental mechanism underlying functional hyperemia is activation of capillary endothelial inward-rectifying K+ (Kir2.1) channels by neuronally derived potassium (K+), which evokes a retrograde capillary-to-arteriole electrical signal that dilates upstream arterioles, increasing blood delivery to downstream active regions. Here, using a mouse model of familial AD (5xFAD), we tested whether this impairment in functional hyperemia is attributable to reduced activity of capillary Kir2.1 channels. In vivo CBF measurements revealed significant reductions in whisker stimulation (WS)-induced and K+-induced hyperemic responses in 5xFAD mice compared with age-matched controls. Notably, measurements of whole-cell currents in freshly isolated 5xFAD capillary endothelial cells showed that Kir2.1 current density was profoundly reduced, suggesting a defect in Kir2.1 function. Because Kir2.1 activity absolutely depends on binding of phosphatidylinositol 4,5-bisphosphate (PIP2) to the channel, we hypothesized that capillary Kir2.1 channel impairment could be corrected by exogenously supplying PIP2. As predicted, a PIP2 analog restored Kir2.1 current density to control levels. More importantly, systemic administration of PIP2 restored K+-induced CBF increases and WS-induced functional hyperemic responses in 5xFAD mice. Collectively, these data provide evidence that PIP2-mediated restoration of capillary endothelial Kir2.1 function improves neurovascular coupling and CBF in the setting of AD.
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Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Osama F Harraz
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA
| | - Albert L Gonzales
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Department of Physiology and Cell Biology, University of Nevada, Reno, School of Medicine, Reno, NV, USA
| | - David Hill-Eubanks
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Mark T Nelson
- Department of Pharmacology, Larner College of Medicine, University of Vermont, Burlington, VT, USA,Vermont Center for Cardiovascular and Brain Health, University of Vermont, Burlington, VT, USA,Division of Cardiovascular Sciences, University of Manchester, Manchester, UK,Address correspondence to M.T.N. (e-mail: )
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19
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Wu L, Wang Q, Gu J, Zhang H, Gu Y. Modulation of Actin Filament Dynamics by Inward Rectifying of Potassium Channel Kir2.1. Int J Mol Sci 2020; 21:ijms21207479. [PMID: 33050503 PMCID: PMC7589188 DOI: 10.3390/ijms21207479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/02/2020] [Accepted: 10/06/2020] [Indexed: 01/17/2023] Open
Abstract
Apart from its ion channel properties, the Kir2.1 channel has been found in tumors and cancer cells to facilitate cancer cell motility. It is assumed that Kir2.1 might be associated with cell actin filament dynamics. With the help of structured illumination microscopy (SIM), we show that Kir2.1 overexpression promotes actin filament dynamics, cell invasion, and adhesion. Mutated Kir2.1 channels, with impaired membrane expression, present much weaker actin regulatory effects, which indicates that precise Kir2.1 membrane localization is key to its actin filament remolding effect. It is found that Kir2.1 membrane expression and anchoring are associated with PIP2 affinity, and PIP2 depletion inhibits actin filament dynamics. We also report that membrane-expressed Kir2.1 regulates redistribution and phosphorylation of FLNA (filamin A), which may be the mechanism underlying Kir2.1 and actin filament dynamics. In conclusion, Kir2.1 membrane localization regulates cell actin filaments, and not the ion channel properties. These data indicate that Kir2.1 may have additional cellular functions distinct from the regulation of excitability, which provides new insight into the study of channel proteins.
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Affiliation(s)
- Lida Wu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
- Aston Medical School, Aston University, Birmingham B4 7ET, UK
| | - Quanyi Wang
- Department of Biopharmaceutics, School of Life Science and Technology, China Pharmaceutical University, Nanjing 210009, China;
| | - Junzhong Gu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
| | - Huiyuan Zhang
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
| | - Yuchun Gu
- Molecular Pharmacology Laboratory, Institute of Molecular Medicine, Peking University, Beijing 100871, China; (L.W.); (J.G.); (H.Z.)
- Aston Medical School, Aston University, Birmingham B4 7ET, UK
- Correspondence:
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20
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Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) enable cardiotoxicity testing and personalized medicine. However, their maturity is of concern, including relatively depolarized resting membrane potential and more spontaneous activity compared with adult cardiomyocytes, implicating low or lacking inward rectifier potassium current (Ik1). Here, protein quantification confirms Kir2.1 expression in hiPSC-CM syncytia, albeit several times lower than in adult heart tissue. We find that hiPSC-CM culture density influences Kir2.1 expression at the mRNA level (potassium inwardly rectifying channel subfamily J member 2) and at the protein level and its associated electrophysiology phenotype. Namely, all-optical cardiac electrophysiology and pharmacological treatments reveal reduction of spontaneous and irregular activity and increase in action potential upstroke in denser cultures. Blocking Ik1-like currents with BaCl2 increased spontaneous frequency and blunted action potential upstrokes during pacing in a dose-dependent manner only in the highest-density cultures, in line with Ik1’s role in regulating the resting membrane potential. Our results emphasize the importance of syncytial growth of hiPSC-CMs for more physiologically relevant phenotype and the power of all-optical electrophysiology to study cardiomyocytes in their multicellular setting. NEW & NOTEWORTHY We identify cell culture density and cell-cell contact as an important factor in determining the expression of a key ion channel at the transcriptional and the protein levels, KCNJ2/Kir2.1, and its contribution to the electrophysiology of human induced pluripotent stem cell-derived cardiomyocytes. Our results indicate that studies on isolated cells, out of tissue context, may underestimate the cellular ion channel properties being characterized.
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Affiliation(s)
- Weizhen Li
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | - Julie L Han
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | - Emilia Entcheva
- Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
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21
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Fu XK, Liu YQ, Gao H, Wang GL, Li HY, Dai DJ. [Effects of hypothermia on the repolarization duration of ventricular myocytes in rats and its mechanism]. Zhongguo Ying Yong Sheng Li Xue Za Zhi 2020; 36:228-31. [PMID: 32981277 DOI: 10.12047/j.cjap.5914.2020.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Objective: To observe the effects of hypothermia on the repolarization duration and the expression of Kir2.1 protein of ventricular myocytes in isolated rat heart and explore the role of Kir2.1 protein.Methods: Eighteen healthy adult male Sprague-Dawley rats were randomly divided into three groups (n=6 per group): Control group (C group), 35℃ group (H1 group), 32℃ group (H2 group). Langendorff isolated heart models were established. After 15 min 37℃ K-H fluid banlanced perfusion, C group continued to perfuse the K-H solution at 37℃ for 30 minutes, H1 group continued to perfuse the K-H solution at 35℃ for 30 minutes, H2 group continued to perfuse the K-H solution at 32℃ for 30 minutes. At 15 min of balanced perfusion (T1), and 30 min of continuous perfusion (T2), the heart rate,and the MAP in the three layers of the left ventricular anterior wall were recorded, the action potential duration at 50% repolarization (MAPD50), the action potential duration at 90% repolarization (MAPD90) and transmural dispersion of repolarization(TDR) were calculated. At the same time, the occurrence of arrhythmia was recorded. The expression of Kir2.1 protein was measured by Western blot. The average optical density (AOD) and the distribution of Kir2.1 protein were measured by immunohistochemistry in the ventricular tissue measured by electrophysiology. Results: Compared with T0, the heart rate was decreased, MAPD50 and MAPD90 were prolonged significantly (P<0.05), and TDR was increased significantly (P<0.05) in H1 group, H2 group at T1. Compared with C group, the HR was decreased, the MAPD90 was prolonged significantly (P<0.05), TDR was increased significantly (P<0.05),the expression and the AOD of Kir2.1 protein were decreased significantly (P<0.05) in H1group, H2group at T1. Compared with H1 group, the heart rate of H2 group was decreased significantly (P<0.05), MAPD50 and MAPD90 were prolonged significantly (P<0.05), and TDR was increased significantly (P<0.05) at T1. The distribution of Kir2.1 protein in group C was normal, while the distribution of Kir2.1 in H1 group and H2 group was disordered. Conclusion: Hypothermia prolonged the ventricular duration of repolarization and increased the dispersion of repolarization. The mechanism is related to the down-regulation the expression of Kir2.1 protein and the disorder of the distribution of Kir2.1 protein.
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22
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Park SS, Ponce-Balbuena D, Kuick R, Guerrero-Serna G, Yoon J, Mellacheruvu D, Conlon KP, Basrur V, Nesvizhskii AI, Jalife J, Rual JF. Kir2.1 Interactome Mapping Uncovers PKP4 as a Modulator of the Kir2.1-Regulated Inward Rectifier Potassium Currents. Mol Cell Proteomics 2020; 19:1436-1449. [PMID: 32541000 PMCID: PMC8143648 DOI: 10.1074/mcp.ra120.002071] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Indexed: 12/27/2022] Open
Abstract
Kir2.1, a strong inward rectifier potassium channel encoded by the KCNJ2 gene, is a key regulator of the resting membrane potential of the cardiomyocyte and plays an important role in controlling ventricular excitation and action potential duration in the human heart. Mutations in KCNJ2 result in inheritable cardiac diseases in humans, e.g. the type-1 Andersen-Tawil syndrome (ATS1). Understanding the molecular mechanisms that govern the regulation of inward rectifier potassium currents by Kir2.1 in both normal and disease contexts should help uncover novel targets for therapeutic intervention in ATS1 and other Kir2.1-associated channelopathies. The information available to date on protein-protein interactions involving Kir2.1 channels remains limited. Additional efforts are necessary to provide a comprehensive map of the Kir2.1 interactome. Here we describe the generation of a comprehensive map of the Kir2.1 interactome using the proximity-labeling approach BioID. Most of the 218 high-confidence Kir2.1 channel interactions we identified are novel and encompass various molecular mechanisms of Kir2.1 function, ranging from intracellular trafficking to cross-talk with the insulin-like growth factor receptor signaling pathway, as well as lysosomal degradation. Our map also explores the variations in the interactome profiles of Kir2.1WTversus Kir2.1Δ314-315, a trafficking deficient ATS1 mutant, thus uncovering molecular mechanisms whose malfunctions may underlie ATS1 disease. Finally, using patch-clamp analysis, we validate the functional relevance of PKP4, one of our top BioID interactors, to the modulation of Kir2.1-controlled inward rectifier potassium currents. Our results validate the power of our BioID approach in identifying functionally relevant Kir2.1 interactors and underline the value of our Kir2.1 interactome as a repository for numerous novel biological hypotheses on Kir2.1 and Kir2.1-associated diseases.
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Affiliation(s)
- Sung-Soo Park
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Daniela Ponce-Balbuena
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Rork Kuick
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Guadalupe Guerrero-Serna
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Justin Yoon
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Kevin P Conlon
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Venkatesha Basrur
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexey I Nesvizhskii
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, Michigan, USA
| | - José Jalife
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
- Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares, Madrid, Spain
| | - Jean-François Rual
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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23
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Nguyen HM, di Lucente J, Chen YJ, Cui Y, Ibrahim RH, Pennington MW, Jin LW, Maezawa I, Wulff H. Biophysical basis for Kv1.3 regulation of membrane potential changes induced by P2X4-mediated calcium entry in microglia. Glia 2020; 68:2377-2394. [PMID: 32525239 PMCID: PMC7540709 DOI: 10.1002/glia.23847] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/17/2020] [Accepted: 05/07/2020] [Indexed: 12/02/2022]
Abstract
Microglia‐mediated inflammation exerts adverse effects in ischemic stroke and in neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the voltage‐gated potassium channel Kv1.3 is required for microglia activation. Both genetic deletion and pharmacological inhibition of Kv1.3 are effective in reducing microglia activation and the associated inflammatory responses, as well as in improving neurological outcomes in animal models of AD and ischemic stroke. Here we sought to elucidate the molecular mechanisms underlying the therapeutic effects of Kv1.3 inhibition, which remain incompletely understood. Using a combination of whole‐cell voltage‐clamp electrophysiology and quantitative PCR (qPCR), we first characterized a stimulus‐dependent differential expression pattern for Kv1.3 and P2X4, a major ATP‐gated cationic channel, both in vitro and in vivo. We then demonstrated by whole‐cell current‐clamp experiments that Kv1.3 channels contribute not only to setting the resting membrane potential but also play an important role in counteracting excessive membrane potential changes evoked by depolarizing current injections. Similarly, the presence of Kv1.3 channels renders microglia more resistant to depolarization produced by ATP‐mediated P2X4 receptor activation. Inhibiting Kv1.3 channels with ShK‐223 completely nullified the ability of Kv1.3 to normalize membrane potential changes, resulting in excessive depolarization and reduced calcium transients through P2X4 receptors. Our report thus links Kv1.3 function to P2X4 receptor‐mediated signaling as one of the underlying mechanisms by which Kv1.3 blockade reduces microglia‐mediated inflammation. While we could confirm previously reported differences between males and females in microglial P2X4 expression, microglial Kv1.3 expression exhibited no gender differences in vitro or in vivo. Main Points The voltage‐gated K+ channel Kv1.3 regulates microglial membrane potential. Inhibition of Kv1.3 depolarizes microglia and reduces calcium entry mediated by P2X4 receptors by dissipating the electrochemical driving force for calcium.
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Affiliation(s)
- Hai M Nguyen
- Department of Pharmacology, University of California, Davis, California, USA
| | - Jacopo di Lucente
- Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California, USA
| | - Yi-Je Chen
- Department of Pharmacology, University of California, Davis, California, USA
| | - Yanjun Cui
- Department of Pharmacology, University of California, Davis, California, USA
| | - Rania H Ibrahim
- Department of Pharmacology, University of California, Davis, California, USA
| | | | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California, USA
| | - Izumi Maezawa
- Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California, USA
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California, USA
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Xuan L, Zhu Y, Liu Y, Yang H, Wang S, Li Q, Yang C, Jiao L, Zhang Y, Yang B, Sun L. Up-regulation of miR-195 contributes to cardiac hypertrophy-induced arrhythmia by targeting calcium and potassium channels. J Cell Mol Med 2020; 24:7991-8005. [PMID: 32468736 PMCID: PMC7348160 DOI: 10.1111/jcmm.15431] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 01/01/2023] Open
Abstract
Previous studies have confirmed that miR-195 expression is increased in cardiac hypertrophy, and the bioinformatics website predicted by Targetscan software shows that miR-195 can directly target CACNB1, KCNJ2 and KCND3 to regulate Cavβ1, Kir2.1 and Kv4.3 proteins expression. The purpose of this study is to confirm the role of miR-195 in arrhythmia caused by cardiac hypertrophy. The protein levels of Cavβ1, Kir2.1 and Kv4.3 in myocardium of HF mice were decreased. After miR-195 was overexpressed in neonatal mice cardiomyocytes, the expression of ANP, BNP and β-MHC was up-regulated, and miR-195 inhibitor reversed this phenomenon. Overexpression of miR-195 reduced the estimated cardiac function of EF% and FS% in wild-type (WT) mice. Transmission electron microscopy showed that the ultrastructure of cardiac tissues was damaged after miR-195 overexpression by lentivirus in mice. miR-195 overexpression increased the likelihood of arrhythmia induction and duration of arrhythmia in WT mice. Lenti-miR-195 inhibitor carried by lentivirus can reverse the decreased EF% and FS%, the increased incidence of arrhythmia and prolonged duration of arrhythmia induced by TAC in mice. After miR-195 treatment, the protein expressions of Cavβ1, Kir2.1 and Kv4.3 were decreased in mice. The results were consistent at animal and cellular levels, respectively. Luciferase assay results showed that miR-195 may directly target CACNB1, KCNJ2 and KCND3 to regulate the expression of Cavβ1, Kir2.1 and Kv4.3 proteins. MiR-195 is involved in arrhythmia caused by cardiac hypertrophy by inhibiting Cavβ1, Kir2.1 and Kv4.3.
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Affiliation(s)
- Lina Xuan
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Yanmeng Zhu
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Yunqi Liu
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Hua Yang
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Shengjie Wang
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Qingqi Li
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Chao Yang
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Lei Jiao
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Ying Zhang
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Baofeng Yang
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
| | - Lihua Sun
- Department of Pharmacology, Harbin Medical University (the State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, China
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Lv L, Zheng N, Zhang L, Li R, Li Y, Yang R, Li C, Fang R, Shabanova A, Li X, Liu Y, Liang H, Zhou Y, Shan H. Metformin ameliorates cardiac conduction delay by regulating microRNA-1 in mice. Eur J Pharmacol 2020; 881:173131. [PMID: 32450177 DOI: 10.1016/j.ejphar.2020.173131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/16/2022]
Abstract
Cardiac conduction delay may occur as a common complication of several cardiac diseases. A few therapies and drugs have a good effect on cardiac conduction delay. Metformin (Met) has a protective effect on the heart. This study's aim was to investigate whether Met could ameliorate cardiac conduction delay and its potential mechanism. Cardiac-specific microRNA-1 (miR-1) transgenic (TG) and myocardial infarction (MI) mouse models were used. Mice were administered with Met in an intragastric manner. We found that the expression of miR-1 was significantly up-regulated in H2O2 treated cardiomyocytes as well as in TG and MI mice. The protein levels of inwardly rectifying potassium channel 2.1 (Kir2.1) and Connexin43 (CX43) were down-regulated both in cardiomyocytes treated with H2O2 as well as cardiac tissues of TG and MI mice, as compared to their controls. Furthermore, the PR and QT intervals were prolonged, action potential duration (APD) was delayed, and conduction velocity (CV) was reduced, with upregulation of miR-1 in the hearts. In the meanwhile, intercalated disc injuries were found in the hearts of MI mice. Interestingly, Met can noticeably inhibit miR-1 upregulation and attenuate the changes mentioned above. Taken together, this suggested that Met could play an important role in improving cardiac conduction delay through inhibition of miR-1 expression. Our study proposes that Met is a potential candidate for the treatment of cardiac conduction delay and provides a new idea of treating arrhythmia with a drug.
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Affiliation(s)
- Lifang Lv
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; The Centre of Functional Experiment Teaching, Department of Basic Medicine, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Nan Zheng
- Department of Pharmacy, The Second Affiliated Hospital of Harbin Medical University (Institute of Clinical Pharmacy, The Heilongjiang Key Laboratory of Drug Research, Harbin Medical University), Harbin, China
| | - Lijia Zhang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Ruotong Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yingnan Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Rui Yang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Chao Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Ruonan Fang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Azaliia Shabanova
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Department of Outpatient and Emergency Pediatric, Bashkir State Medical University, Ground Floor, Teatralnaya Street, 2a, 450000, Ufa, Russia
| | - Xuelian Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yingqi Liu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Haihai Liang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China
| | - Yuhong Zhou
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China.
| | - Hongli Shan
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China; Northern Translational Medicine Research and Cooperation Center, Heilongjiang Academy of Medical Sciences, Harbin Medical University, Harbin, Heilongjiang, 150081, PR China.
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26
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Gattlen C, Deftu AF, Tonello R, Ling Y, Berta T, Ristoiu V, Suter MR. The inhibition of Kir2.1 potassium channels depolarizes spinal microglial cells, reduces their proliferation, and attenuates neuropathic pain. Glia 2020; 68:2119-2135. [PMID: 32220118 DOI: 10.1002/glia.23831] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 03/11/2020] [Accepted: 03/13/2020] [Indexed: 11/11/2022]
Abstract
Spinal microglia change their phenotype and proliferate after nerve injury, contributing to neuropathic pain. For the first time, we have characterized the electrophysiological properties of microglia and the potential role of microglial potassium channels in the spared nerve injury (SNI) model of neuropathic pain. We observed a strong increase of inward currents restricted at 2 days after injury associated with hyperpolarization of the resting membrane potential (RMP) in microglial cells compared to later time-points and naive animals. We identified pharmacologically and genetically the current as being mediated by Kir2.1 ion channels whose expression at the cell membrane is increased 2 days after SNI. The inhibition of Kir2.1 with ML133 and siRNA reversed the RMP hyperpolarization and strongly reduced the currents of microglial cells 2 days after SNI. These electrophysiological changes occurred coincidentally to the peak of microglial proliferation following nerve injury. In vitro, ML133 drastically reduced the proliferation of BV2 microglial cell line after both 2 and 4 days in culture. In vivo, the intrathecal injection of ML133 significantly attenuated the proliferation of microglia and neuropathic pain behaviors after nerve injury. In summary, our data implicate Kir2.1-mediated microglial proliferation as an important therapeutic target in neuropathic pain.
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Affiliation(s)
- Christophe Gattlen
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
| | - Alexandru-Florian Deftu
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland.,Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Raquel Tonello
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Yuejuan Ling
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA.,Pain Research Laboratory, Institute of Nautical Medicine, Jiangsu Key Laboratory of Neurodegeneration, University of Nantong, Nantong, Jiangsu, China
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Violeta Ristoiu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Marc René Suter
- Pain Center, Department of Anesthesiology, Lausanne University Hospital and University of Lausanne (CHUV), Lausanne, Switzerland.,Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland.,Department of Fundamental Neurosciences, Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
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27
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Korrell KV, Disser J, Parley K, Vadisiute A, Requena-Komuro MC, Fodder H, Pollart C, Knott G, Molnár Z, Hoerder-Suabedissen A. Differential effect on myelination through abolition of activity-dependent synaptic vesicle release or reduction of overall electrical activity of selected cortical projections in the mouse. J Anat 2019; 235:452-467. [PMID: 30901089 PMCID: PMC6704270 DOI: 10.1111/joa.12974] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2019] [Indexed: 12/16/2022] Open
Abstract
Myelination of axons by oligodendrocytes in the central nervous system is crucial for fast, saltatory conduction of action potentials. As myelination is central for brain development and plasticity, and deficits are implicated in several neural disorders such as multiple sclerosis, major depressive disorder, bipolar disorder and schizophrenia, it is important to elucidate the underlying mechanisms regulating myelination. Numerous mechanisms have been proposed by which the communication between oligodendrocytes and active axons may regulate the onset and maintenance of activity‐dependent myelination. We compared two models of ‘silencing' layer V and/or VI cortical projection neurons from early stages by either decreasing their excitability through Kir2.1 expression, an inward rectifying potassium channel, introduced through in utero electroporation at embryonic day (E)13.5, or inhibiting regulated vesicular release through Cre‐dependent knock‐out of synaptosomal associated protein 25 kDA (SNAP25). SNAP25 is a component of the soluble N‐ethylmaleimide fusion protein attachment protein receptor (SNARE) complex, which, among others, is needed for calcium‐dependent regulated vesicle release from synapses. In layer VI cortical projection neurons in the Ntsr1‐Cre;Ai14;Snap25fl/fl mouse, we found that inhibiting regulated vesicular release significantly decreased the amount of myelin basic protein (MBP, used as marker for myelination) and the amount of myelinated projections at postnatal day (P)14 without affecting the initial timing of onset of myelination in the brain (at P7/P8). Additionally, overall oligodendrocyte maturation appears to be affected. A strong trend towards reduced node of Ranvier (NoR) length was also observed in Ntsr1‐Cre;Ai14;Snap25fl/fl corpus callosum. An equally strong trend towards reduced NoR length was observed in Rbp4‐Cre;Ai14;Snap25fl/fl corpus callosum at P14, and the g‐ratio in the spinal cord dorsal column was reduced at P18. However, no measurable differences in levels of MBP were detected in the striatum when comparing Rbp4‐Cre;Ai14;Snap25fl/fl and control brains. Conversely, Kir2.1 in utero electroporation at E13.5 did not significantly affect the amount of MBP or number of myelinated callosal axons at P14 but did significantly decrease the NoR length measured in the corpus callosum. It therefore seems likely that the excitability of the neuron can potentially perform a modulating function of myelin characteristics, whereas regulated vesicular release has the potential to have a more pronounced effect on overall myelination, but in a cell‐type specific manner.
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Affiliation(s)
- Kim V Korrell
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Jolande Disser
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Kristina Parley
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Auguste Vadisiute
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | - Harriet Fodder
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Charlotte Pollart
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.,Institute of Molecular Biology and Medicine (IBMM), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Graham Knott
- EPFL SV PTECH PTBIOEM, AI 0143 (Bâtiment AI), Lausanne, Switzerland
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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28
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van der Heyden MAG, Delisle BP, Abriel H. Editorial: Ion Channel Trafficking and Cardiac Arrhythmias. Front Physiol 2018; 9:1254. [PMID: 30319434 PMCID: PMC6167604 DOI: 10.3389/fphys.2018.01254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/20/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Marcel A G van der Heyden
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, Swiss National Centre of Competence in Research TransCure, University of Bern, Bern, Switzerland
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29
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Harraz OF, Longden TA, Hill-Eubanks D, Nelson MT. PIP 2 depletion promotes TRPV4 channel activity in mouse brain capillary endothelial cells. eLife 2018; 7:38689. [PMID: 30084828 PMCID: PMC6117155 DOI: 10.7554/elife.38689] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 08/06/2018] [Indexed: 01/08/2023] Open
Abstract
We recently reported that the inward-rectifier Kir2.1 channel in brain capillary endothelial cells (cECs) plays a major role in neurovascular coupling (NVC) by mediating a neuronal activity-dependent, propagating vasodilatory (hyperpolarizing) signal. We further demonstrated that Kir2.1 activity is suppressed by depletion of plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP2). Whether cECs express depolarizing channels that intersect with Kir2.1-mediated signaling remains unknown. Here, we report that Ca2+/Na+-permeable TRPV4 (transient receptor potential vanilloid 4) channels are expressed in cECs and are tonically inhibited by PIP2. We further demonstrate that depletion of PIP2 by agonists, including putative NVC mediators, that promote PIP2 hydrolysis by signaling through Gq-protein-coupled receptors (GqPCRs) caused simultaneous disinhibition of TRPV4 channels and suppression of Kir2.1 channels. These findings collectively support the concept that GqPCR activation functions as a molecular switch to favor capillary TRPV4 activity over Kir2.1 signaling, an observation with potentially profound significance for the control of cerebral blood flow. Capillaries form branching networks that surround all cells of the body. They allow oxygen and nutrient exchange between blood and tissue, but this is not their only role. Capillaries in the brain form a tight barrier that prevents components carried in the blood from easily reaching the brain compartment. They also detect the activity of neurons and trigger on-demand increases in blood flow to active regions of the brain. This role, revealed only recently, depends upon ion channels on the surface of the capillary cells. Active neurons release potassium ions, which open a type of ion channel called Kir2.1 that allows potassium inside the cell to flow out. This process is repeated in neighboring capillary cells until it reaches an upstream vessel, where it causes the vessel to relax and increase the blood flow. Kir2.1 channels sit astride the membranes of capillary cells, where they can interact with other membrane molecules. One such molecule, called PIP2, plays several roles in relaying signals from the outside to the inside of cells. It also physically interacts with channels in the membrane, including Kir2.1 channels. If PIP2 levels are low, Kir2.1 channel activity decreases. Here, Harraz et al. discovered that capillary cells contain another type of ion channel, called TRPV4, which is also regulated by PIP2. But unlike Kir2.1, its activity increases when PIP2 levels drop. Moreover, TRPV4 channels allow sodium and calcium ions to flow into the cell, which has an effect opposite to that of potassium flowing out of the cell. Capillary cells also have receptor proteins called GqPCRs that are activated by chemical signals released by active neurons in the brain. GqPCRs break down PIP2, so their activity turns Kir2.1 channels off and TRPV4 channels on. This resets the system so that it is ready to respond to new signals from active neurons. GqPCRs work as molecular switches to control the balance between Kir2.1 and TRPV4 channels and turn brain blood flow up and down. GqPCRs and ion channels that depend on PIP2 can also be found in other types of cells. These findings could reveal clues about how signals are switched on and off in different cells. Understanding the role of PIP2 in signaling could also unveil what happens when signaling go wrong.
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Affiliation(s)
- Osama F Harraz
- Department of Pharmacology, University of Vermont, Burlington, United States
| | - Thomas A Longden
- Department of Pharmacology, University of Vermont, Burlington, United States
| | - David Hill-Eubanks
- Department of Pharmacology, University of Vermont, Burlington, United States
| | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, United States.,Institute of Cardiovascular Sciences, Manchester, United Kingdom
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30
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Di Lucente J, Nguyen HM, Wulff H, Jin LW, Maezawa I. The voltage-gated potassium channel Kv1.3 is required for microglial pro-inflammatory activation in vivo. Glia 2018; 66:1881-1895. [PMID: 30043400 DOI: 10.1002/glia.23457] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 04/26/2018] [Accepted: 05/02/2018] [Indexed: 11/09/2022]
Abstract
Microglia show a rich repertoire of activation patterns regulated by a complex ensemble of surface ion channels, receptors, and transporters. We and others have investigated whether microglia vary their K+ channel expression as a means to achieve functional diversity. However, most of the prior studies were conducted using in vitro models such as BV2 cells, primary microglia, or brain slices in culture, which may not accurately reflect microglia physiology in adult individuals. Here we employed an in vivo mouse model of selective innate immune activation by intracerebroventricular injection of lipopolysaccharides (ICV-LPS) to determine the role of the voltage-gated Kv1.3 channel in LPS-induced M1-like microglial activation. Using microglia acutely isolated from adult brains, we detected Kv1.3 and Kir2.1 currents, and found that ICV-LPS increased the current density and RNA expression of Kv1.3 but did not affect those of Kir2.1. Genetic knockout of Kv1.3 abolished LPS-induced microglial activation exemplified by Iba-1 immunoreactivity and expression of pro-inflammatory mediators such as IL-1β, TNF-α, IL-6, and iNOS. Moreover, Kv1.3 knockout mitigated the LPS-induced impairment of hippocampal long-term potentiation (hLTP), suggesting that Kv1.3 activity regulates pro-inflammatory microglial neurotoxicity. Pharmacological intervention using PAP-1, a small molecule that selectively blocks homotetrameric Kv1.3 channels, achieved anti-inflammatory and hLTP-recovery effects similar to Kv1.3 knockout. We conclude that Kv1.3 is required for microglial M1-like pro-inflammatory activation in vivo. A significant implication of our in vivo data is that Kv1.3 blockers could be therapeutic candidates for neurological diseases where microglia-mediated neurotoxicity is implicated in the pathogenesis.
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Affiliation(s)
- Jacopo Di Lucente
- From the Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California
| | - Hai M Nguyen
- Department of Pharmacology, University of California, Davis, California
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California
| | - Lee-Way Jin
- From the Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California
| | - Izumi Maezawa
- From the Department of Pathology and Laboratory Medicine and M.I.N.D. Institute, University of California Davis Medical Center, Sacramento, California
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31
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Fang W, Xia L, Sun X, Cai S, Bai S, Sun Y, Zhou P, Liu X, Zhao R, Shen B. Lipopolysaccharides increase Kir2.1 expression in lung endothelial cells. Int J Clin Exp Pathol 2018; 11:2959-2967. [PMID: 31938421 PMCID: PMC6958072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/24/2018] [Indexed: 06/10/2023]
Abstract
Kir2.1 is an inwardly rectifying K+ channel that modulates membrane potential. It is expressed widely in smooth muscle, neurons, and endothelial cells. Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe clinical syndromes, often causing the damage of epithelial and endothelial cells. Lipopolysaccharides (LPS) usually cause ALI/ARDS, directly or indirectly, and are used to reproduce the model in vivo. Here, we used differentially expressed gene analysis to find increasing Kir2.1 channel expression in human pulmonary microvascular endothelial cells cultured with LPS. Primary cultured mice pulmonary microvascular endothelial cells were verified by immunofluorescence. LPS incubation increased Kir2.1 channel expression in cultured mice pulmonary microvascular endothelial cells. A whole-cell voltage clamp was used to record the K+ current in cultured endothelial cells, showing increased whole-cell current in LPS treatment compared with controls. Additionally, the application of Ba2+, as an inhibitor of Kir2.1 channel, inhibited K+ current in both groups. We demonstrated that LPS may increase Kir2.1 channel expression in mice pulmonary microvascular endothelial cells to increase K+ flux, maintain hyperpolarization, and cause vasodilation, which may increase blood flow in pulmonary vessel bed, leading to pulmonary congestion contributing pneumonemia and ALI/ARDS.
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Affiliation(s)
- Wei Fang
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Lin Xia
- School of Basic Medical Sciences, Anhui Medical UniversityHefei, Anhui, China
| | - Xiaoxia Sun
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Shixia Cai
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Suwen Bai
- School of Basic Medical Sciences, Anhui Medical UniversityHefei, Anhui, China
| | - Yunbo Sun
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Peihong Zhou
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Xin Liu
- Department of ICU, The Affiliated Hospital of Qingdao UniversityQingdao, Shandong, China
| | - Ren Zhao
- Department of Cardiology, The First Affiliated Hospital of Anhui Medical UniversityHefei, Anhui, China
| | - Bing Shen
- School of Basic Medical Sciences, Anhui Medical UniversityHefei, Anhui, China
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32
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Kim S, Shou J, Abera S, Ziff EB. Sucrose withdrawal induces depression and anxiety-like behavior by Kir2.1 upregulation in the nucleus accumbens. Neuropharmacology 2017; 130:10-17. [PMID: 29191750 DOI: 10.1016/j.neuropharm.2017.11.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/24/2017] [Accepted: 11/25/2017] [Indexed: 02/02/2023]
Abstract
Dieting induces depression and anxiety among other emotional symptoms. Animal models indicate that repeated access to palatable foods such as sugar induces depression and anxiety-like behavior when the food is no longer available. However, the neurobiological mechanisms of how dietary restriction influences mood have not been fully understood. We used the two-bottle sucrose choice paradigm as an overeating and withdrawal model. Withdrawal after lengthy sucrose overeating elicited depression and anxiety-like behavior, which was reversed by sucrose reinstatement. In the nucleus accumbens (NAc) of sucrose withdrawal animals, dopamine levels and cAMP response element binding protein (CREB) activity were significantly reduced, while the inwardly rectifying K+ channel, Kir2.1, was significantly elevated. In addition, overexpression of Kir2.1 selectively in neurons expressing dopamine D1 receptors was sufficient to induce negative mood-linked behavior in the absence of sucrose overeating experience. As elevated K+ channels reduce neuronal excitability, a sucrose withdrawal-induced increase in Kir2.1 expression is able to decrease NAc activity, which provides a cellular basis for depression and anxiety-like behavior in animals.
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Affiliation(s)
- Seonil Kim
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States; Molecular Cellular and Integrative Neurosciences Program, Colorado State University, Fort Collins, CO 80523, United States.
| | - Jiayi Shou
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States
| | - Sinedu Abera
- Department of Biochemistry and Molecular Pharmacology, New York University Lagnone Medical Center, New York, NY 10016, United States
| | - Edward B Ziff
- Department of Biochemistry and Molecular Pharmacology, New York University Lagnone Medical Center, New York, NY 10016, United States
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33
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Utrilla RG, Nieto-Marín P, Alfayate S, Tinaquero D, Matamoros M, Pérez-Hernández M, Sacristán S, Ondo L, de Andrés R, Díez-Guerra FJ, Tamargo J, Delpón E, Caballero R. Kir2.1-Nav1.5 Channel Complexes Are Differently Regulated than Kir2.1 and Nav1.5 Channels Alone. Front Physiol 2017; 8:903. [PMID: 29184507 PMCID: PMC5694551 DOI: 10.3389/fphys.2017.00903] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Cardiac Kir2.1 and Nav1.5 channels generate the inward rectifier K+ (IK1) and the Na+ (INa) currents, respectively. There is a mutual interplay between the ventricular INa and IK1 densities, because Nav1.5 and Kir2.1 channels exhibit positive reciprocal modulation. Here we compared some of the biological properties of Nav1.5 and Kir2.1 channels when they are expressed together or separately to get further insights regarding their putative interaction. First we demonstrated by proximity ligation assays (PLAs) that in the membrane of ventricular myocytes Nav1.5 and Kir2.1 proteins are in close proximity to each other (<40 nm apart). Furthermore, intracellular dialysis with anti-Nav1.5 and anti-Kir2.1 antibodies suggested that these channels form complexes. Patch-clamp experiments in heterologous transfection systems demonstrated that the inhibition of the Ca2+/calmodulin-dependent protein kinase II (CaMKII) decreased the INa and the IK1 generated by Nav1.5 and Kir2.1 channels when they were coexpressed, but not the IK1 generated by Kir2.1 channels alone, suggesting that complexes, but not Kir2.1 channels, are a substrate of CaMKII. Furthermore, inhibition of CaMKII precluded the interaction between Nav1.5 and Kir2.1 channels. Inhibition of 14-3-3 proteins did not modify the INa and IK1 densities generated by each channel separately, whereas it decreased the INa and IK1 generated when they were coexpressed. However, inhibition of 14-3-3 proteins did not abolish the Nav1.5-Kir2.1 interaction. Inhibition of dynamin-dependent endocytosis reduced the internalization of Kir2.1 but not of Nav1.5 or Kir2.1-Nav1.5 complexes. Inhibition of cytoskeleton-dependent vesicular trafficking via the dynein/dynactin motor increased the IK1, but reduced the INa, thus suggesting that the dynein/dynactin motor is preferentially involved in the backward and forward traffic of Kir2.1 and Nav1.5, respectively. Conversely, the dynein/dynactin motor participated in the forward movement of Kir2.1-Nav1.5 complexes. Ubiquitination by Nedd4-2 ubiquitin-protein ligase promoted the Nav1.5 degradation by the proteasome, but not that of Kir2.1 channels. Importantly, the Kir2.1-Nav1.5 complexes were degraded following this route as demonstrated by the overexpression of Nedd4-2 and the inhibition of the proteasome with MG132. These results suggested that Kir2.1 and Nav1.5 channels closely interact with each other leading to the formation of a pool of complexed channels whose biology is similar to that of the Nav1.5 channels.
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Affiliation(s)
- Raquel G Utrilla
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Paloma Nieto-Marín
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Silvia Alfayate
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - David Tinaquero
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Marcos Matamoros
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Marta Pérez-Hernández
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | | | - Lorena Ondo
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Raquel de Andrés
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - F Javier Díez-Guerra
- Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Juan Tamargo
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Eva Delpón
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
| | - Ricardo Caballero
- Department of Pharmacology, School of Medicine, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense, Madrid, Spain.,CIBERCV, Madrid, Spain
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Nguyen HM, Blomster LV, Christophersen P, Wulff H. Potassium channel expression and function in microglia: Plasticity and possible species variations. Channels (Austin) 2017; 11:305-315. [PMID: 28277939 DOI: 10.1080/19336950.2017.1300738] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Potassium channels play important roles in microglia functions and thus constitute potential targets for the treatment of neurodegenerative diseases like Alzheimer, Parkinson and stroke. However, uncertainty still prevails as to which potassium channels are expressed and at what levels in different species, how the expression pattern changes upon activation with M1 or M2 polarizing stimuli compared with more complex exposure paradigms, and - most importantly - how these findings relate to the in vivo situation. In this mini-review we discuss the functional potassium channel expression pattern in cultured neonatal mouse microglia in the light of data obtained previously from animal disease models and immunohistochemical studies and compare it with a recent study of adult human microglia isolated from epilepsy patients. Overall, microglial potassium channel expression is very plastic and possibly shows species differences and therefore should be studied carefully in each disease setting and respective animal models.
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Affiliation(s)
- Hai M Nguyen
- a Department of Pharmacology , University of California , Davis, Davis , CA , USA
| | | | | | - Heike Wulff
- a Department of Pharmacology , University of California , Davis, Davis , CA , USA
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Abstract
Kir2.1 plays key roles in setting rest membrane potential and modulation of cell excitability. Mutations of Kir2.1, such as D172N or E299V, inducing gain-of-function, can cause type3 short QT syndrome (SQT3) due to the enlarged outward currents. So far, there is no clinical drug target to block the currents of Kir2.1. Here, we identified a novel blocker of Kir2.1, styrax, which is a kind of natural compound selected from traditional Chinese medicine. Our data show that styrax can abolish the inward and outward currents of Kir2.1. The IC50 of styrax for WT, D172N and E299V are 0.0113 ± 0.00075, 0.0204 ± 0.0048 and 0.0122 ± 0.0012 (in volume), respectively. The results indicate that styrax can serve as a novel blocker for Kir2.1.
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Affiliation(s)
- Shuxi Ren
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Chunli Pang
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Junwei Li
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Yayue Huang
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Suhua Zhang
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Yong Zhan
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
| | - Hailong An
- a Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology , Tianjin , China
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Nguyen HM, Grössinger EM, Horiuchi M, Davis KW, Jin LW, Maezawa I, Wulff H. Differential Kv1.3, KCa3.1, and Kir2.1 expression in "classically" and "alternatively" activated microglia. Glia 2016; 65:106-121. [PMID: 27696527 PMCID: PMC5113690 DOI: 10.1002/glia.23078] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 09/15/2016] [Indexed: 11/10/2022]
Abstract
Microglia are highly plastic cells that can assume different phenotypes in response to microenvironmental signals. Lipopolysaccharide (LPS) and interferon-γ (IFN-γ) promote differentiation into classically activated M1-like microglia, which produce high levels of pro-inflammatory cytokines and nitric oxide and are thought to contribute to neurological damage in ischemic stroke and Alzheimer's disease. IL-4 in contrast induces a phenotype associated with anti-inflammatory effects and tissue repair. We here investigated whether these microglia subsets vary in their K+ channel expression by differentiating neonatal mouse microglia into M(LPS) and M(IL-4) microglia and studying their K+ channel expression by whole-cell patch-clamp, quantitative PCR and immunohistochemistry. We identified three major types of K+ channels based on their biophysical and pharmacological fingerprints: a use-dependent, outwardly rectifying current sensitive to the KV 1.3 blockers PAP-1 and ShK-186, an inwardly rectifying Ba2+ -sensitive Kir 2.1 current, and a Ca2+ -activated, TRAM-34-sensitive KCa 3.1 current. Both KV 1.3 and KCa 3.1 blockers inhibited pro-inflammatory cytokine production and iNOS and COX2 expression demonstrating that KV 1.3 and KCa 3.1 play important roles in microglia activation. Following differentiation with LPS or a combination of LPS and IFN-γ microglia exhibited high KV 1.3 current densities (∼50 pA/pF at 40 mV) and virtually no KCa 3.1 and Kir currents, while microglia differentiated with IL-4 exhibited large Kir 2.1 currents (∼ 10 pA/pF at -120 mV). KCa 3.1 currents were generally low but moderately increased following stimulation with IFN-γ or ATP (∼10 pS/pF). This differential K+ channel expression pattern suggests that KV 1.3 and KCa 3.1 inhibitors could be used to inhibit detrimental neuroinflammatory microglia functions. GLIA 2016;65:106-121.
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Affiliation(s)
- Hai M Nguyen
- Department of Pharmacology, University of California, Davis, California
| | - Eva M Grössinger
- Department of Pharmacology, University of California, Davis, California
| | - Makoto Horiuchi
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Kyle W Davis
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California
| | - Lee-Way Jin
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Izumi Maezawa
- Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, Sacramento, California.,M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, California
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California
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Tay YL, Teah YF, Chong YM, Jamil MFA, Kollert S, Adenan MI, Wahab HA, Döring F, Wischmeyer E, Tan ML. Mitragynine and its potential blocking effects on specific cardiac potassium channels. Toxicol Appl Pharmacol 2016; 305:22-39. [PMID: 27260674 DOI: 10.1016/j.taap.2016.05.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 02/07/2023]
Abstract
Mitragyna speciosa Korth is known for its euphoric properties and is frequently used for recreational purposes. Several poisoning and fatal cases involving mitragynine have been reported but the underlying causes remain unclear. Human ether-a-go-go-related gene (hERG) encodes the cardiac IKr current which is a determinant of the duration of ventricular action potentials and QT interval. On the other hand, IK1, a Kir current mediated by Kir2.1 channel and IKACh, a receptor-activated Kir current mediated by GIRK channel are also known to be important in maintaining the cardiac function. This study investigated the effects of mitragynine on the current, mRNA and protein expression of hERG channel in hERG-transfected HEK293 cells and Xenopus oocytes. The effects on Kir2.1 and GIRK channels currents were also determined in the oocytes. The hERG tail currents following depolarization pulses were inhibited by mitragynine with an IC50 value of 1.62μM and 1.15μM in the transfected cell line and Xenopus oocytes, respectively. The S6 point mutations of Y652A and F656A attenuated the inhibitor effects of mitragynine, indicating that mitragynine interacts with these high affinity drug-binding sites in the hERG channel pore cavity which was consistent with the molecular docking simulation. Interestingly, mitragynine does not affect the hERG expression at the transcriptional level but inhibits the protein expression. Mitragynine is also found to inhibit IKACh current with an IC50 value of 3.32μM but has no significant effects on IK1. Blocking of both hERG and GIRK channels may cause additive cardiotoxicity risks.
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Pilmore E, Hamilton KL. The Role of MicroRNAs in the Regulation of K(+) Channels in Epithelial Tissue. Front Physiol 2015; 6:352. [PMID: 26648872 PMCID: PMC4664832 DOI: 10.3389/fphys.2015.00352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/09/2015] [Indexed: 12/27/2022] Open
Abstract
Our understanding of the modulation of proteins has shifted in direction with the discovery of microRNAs (miRs) over twenty years ago. MiRs are now in the “limelight” as these non-coding pieces of RNA (generally ~22 nucleotides long) result in altered translation and function of proteins. Indeed, miRs are now reported to be potential biomarkers of disease. Epithelial K+ channels play many roles in electrolyte and fluid homeostasis of the human body and have been suggested to be therapeutic targets of disease. Interestingly, the role of miRs in modulating K+ channels of epithelial tissues is only emerging now. This minireview focuses on recent novel findings into the role of miRs in the regulation of K+ channels of epithelia.
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Affiliation(s)
- Elliot Pilmore
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Kirk L Hamilton
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
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Li X, Hu H, Wang Y, Xue M, Li X, Cheng W, Xuan Y, Yin J, Yang N, Yan S. Valsartan ameliorates KIR2.1 in rats with myocardial infarction via the NF-κB-miR-16 pathway. Gene 2015; 590:201-9. [PMID: 26654716 DOI: 10.1016/j.gene.2015.11.047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 10/19/2015] [Accepted: 11/16/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND MicroRNAs have an important role in regulating arrhythmogenesis. MicroRNA-16 (miR-16) is predicted to target KCNJ2. The regulation of miR-16 is primarily due to NF-κB. Whether valsartan could downregulate miR-16 via the inhibition of NF-κB after MI and whether miR-16 targets KCNJ2 remain unclear. METHODS MI rats received valsartan or saline for 7days. The protein levels of NF-κB p65, inhibitor κBα (IκBα), and Kir2.1 were detected by Western blot analysis. The mRNA levels of Kir2.1 and miR-16 were examined by quantitative real-time PCR. Whole cell patch-clamp techniques were applied to record IK1. RESULTS MiR-16 expression was higher in the infarct border, and was accompanied by a depressed IK1/KIR2.1 level. Additionally, miR-16 overexpression suppressed KCNJ2/KIR2.1 expression. In contrast, miR-16 inhibition or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-16 target. In the MI rats, compared to saline treatment, valsartan reduced NF-κB p65 and miR-16 expression and increased IκBα and Kir2.1 expression. In vitro, angiotensin II increased miR-16 expression and valsartan inhibited it. Overexpressing miR-16 in cells treated with valsartan abrogated its beneficial effect on KCNJ2/Kir2.1. NF-κB activation directly upregulates miR-16 expression. CONCLUSIONS miR-16 controls KCNJ2 expression, and valsartan ameliorates Kir2.1 after MI partly depending on the NF-κB-miR-16 pathway.
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Affiliation(s)
- Xinran Li
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Hesheng Hu
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Ye Wang
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Mei Xue
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Xiaolu Li
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Wenjuan Cheng
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China
| | - Yongli Xuan
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Jie Yin
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Na Yang
- School of Medicine, Shandong University, Ji'nan, Shandong, China
| | - Suhua Yan
- Department of Cardiology, Qianfoshan Hospital of Shandong Province, Ji'nan, Shandong, China.
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Willis BC, Ponce-Balbuena D, Jalife J. Protein assemblies of sodium and inward rectifier potassium channels control cardiac excitability and arrhythmogenesis. Am J Physiol Heart Circ Physiol 2015; 308:H1463-73. [PMID: 25862830 DOI: 10.1152/ajpheart.00176.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/06/2015] [Indexed: 02/07/2023]
Abstract
The understanding of how cardiac ion channels function in the normal and the diseased heart has greatly increased over the last four decades thanks to the advent of patch-clamp technology and, more recently, the emergence of genetics, as well as cellular and molecular cardiology. However, our knowledge of how these membrane-embedded proteins physically interact with each other within macromolecular complexes remains incomplete. This review focuses on how the main cardiac inward sodium channel (NaV1.5) and the strong inward rectifier potassium channel (Kir2.1) function within macromolecular complexes to control cardiac excitability. It has become increasingly clear that these two important ion channel proteins physically interact with multiple other protein partners and with each other from early stages of protein trafficking and targeting through membrane anchoring, recycling, and degradation. Recent findings include compartmentalized regulation of NaV1.5 channel expression and function through a PDZ (postsynaptic density protein, Drosophila disc large tumor suppressor, and zonula occludens-1 protein) domain-binding motif, and interaction of caveolin-3 with Kir2.1 and ankyrin-G as a molecular platform for NaV1.5 signaling. At the cardiomyocyte membrane, NaV1.5 and Kir2.1 interact through at least two distinct PDZ domain-scaffolding proteins (synapse-associated protein-97 and α1-syntrophin), thus modulating reciprocally their cell-surface expression at two different microdomains. Emerging evidence also shows that inheritable mutations in plakophilin-2, ankyrin-G, dystrophin, syntrophin, synapse-associated protein-97, and caveolin-3, among others, modify functional expression and/or localization in the cardiac cell of NaV1.5, Kir2.1 or both to give rise to arrhythmogenic diseases. Unveiling the mechanistic underpinnings of macromolecular interactions should increase our understanding of inherited and acquired arrhythmogenic cardiac diseases and may lead to advances in therapy.
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Affiliation(s)
- B Cicero Willis
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - Daniela Ponce-Balbuena
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - José Jalife
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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Shi D, Xie D, Zhang H, Zhao H, Huang J, Li C, Liu Y, Lv F, The E, Liu Y, Yuan T, Wang S, Chen J, Pan L, Yu Z, Liang D, Zhu W, Zhang Y, Li L, Peng L, Li J, Chen YH. Reduction in dynamin-2 is implicated in ischaemic cardiac arrhythmias. J Cell Mol Med 2014; 18:1992-9. [PMID: 25092467 PMCID: PMC4244014 DOI: 10.1111/jcmm.12335] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 05/14/2014] [Indexed: 11/27/2022] Open
Abstract
Ischaemic cardiac arrhythmias cause a large proportion of sudden cardiac deaths worldwide. The ischaemic arrhythmogenesis is primarily because of the dysfunction and adverse remodelling of sarcolemma ion channels. However, the potential regulators of sarcolemma ion channel turnover and function in ischaemic cardiac arrhythmias remains unknown. Our previous studies indicate that dynamin-2 (DNM2), a cardiac membrane-remodelling GTPase, modulates ion channels membrane trafficking in the cardiomyocytes. Here, we have found that DNM2 plays an important role in acute ischaemic arrhythmias. In rat ventricular tissues and primary cardiomyocytes subjected to acute ischaemic stress, the DNM2 protein and transcription levels were markedly down-regulated. This DNM2 reduction was coupled with severe ventricular arrhythmias. Moreover, we identified that the down-regulation of DNM2 within cardiomyocytes increases the action potential amplitude and prolongs the re-polarization duration by depressing the retrograde trafficking of Nav1.5 and Kir2.1 channels. These effects are likely to account for the DNM2 defect-induced arrhythmogenic potentials. These results suggest that DNM2, with its multi-ion channel targeting properties, could be a promising target for novel antiarrhythmic therapies.
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Affiliation(s)
- Dan Shi
- Key Laboratory of Basic Research in Cardiology of the Ministry of Education of China, Tongji University, Shanghai, China; Institute of Medical Genetics, Tongji University, Shanghai, China
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Shen N, Zheng J, Liu H, Xu K, Chen Q, Chen Y, Shen Y, Jiang L, Chen Y. Barium chloride impaired Kir2.1 inward rectification in its stably transfected HEK 293 cell lines. Eur J Pharmacol 2014; 730:164-70. [PMID: 24631257 DOI: 10.1016/j.ejphar.2014.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 02/16/2014] [Accepted: 02/20/2014] [Indexed: 11/16/2022]
Abstract
Kir2.1 channel is a typical inward rectified channel with little outward currents when the membrane depolarized. Barium blocks the inward Kir2.1 currents in a voltage-dependent manner. However, in this study we found that barium would impair the rectification and open Kir2.1 outward currents at a depolarized voltage, causing increment of outward current amplitudes by 43±7% (n=5, P<0.01) after 200s barium application. In the meanwhile, a higher barium concentration did block the outward currents by 17.5±4.3% (n=4, P<0.01) and temporarily twisted current upward tendency. The increment was likely barium specific since both calcium and Kir2.1 specific blocker, Chloroethylclonidine (CEC), did not enhance the current amplitudes. The rectification of Kir2.1 was not recovered by washing barium off, which suggested a non-competitive mechanism. Since the currents occurred at phase 1, 2 of cardiac action potential, it would likely shorten the action potential plateau and it would decrease QT duration in electrocardiography (ECG).
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Affiliation(s)
- Naiji Shen
- Cardiovascular Division, Zhejiang Province People׳s Hospital, 158 Shangtang Road, Hangzhou 310014, PR China
| | - Jifeng Zheng
- Cardiovascular Division, Jiaxing No. 2 Hospital, 1882 Central Circle Road South, Jiaxing 314001, PR China
| | - Hualiang Liu
- Chinese Herb Medicine Division, The Nurturing Station for the State Key Laboratory of Subtropical Silviculture, Zhejiang Agriculture and Forestry University, 88 North Circle Road, Lin'an 311300, PR China
| | - Kai Xu
- Safety Pharmacology Division, Olivepharmasolutions Ltd., 333 Changhong Road, Wukang 313200, PR China
| | - Qingmao Chen
- Safety Pharmacology Division, Olivepharmasolutions Ltd., 333 Changhong Road, Wukang 313200, PR China
| | - Yingying Chen
- Pathophysiolog department, Medical School, Zhejiang University, Hangzhou 310058, PR China
| | - Yueliang Shen
- Pathophysiolog department, Medical School, Zhejiang University, Hangzhou 310058, PR China
| | - Liqing Jiang
- Cardiovascular Division, Jiaxing No. 2 Hospital, 1882 Central Circle Road South, Jiaxing 314001, PR China
| | - Yuan Chen
- Chinese Herb Medicine Division, The Nurturing Station for the State Key Laboratory of Subtropical Silviculture, Zhejiang Agriculture and Forestry University, 88 North Circle Road, Lin'an 311300, PR China.
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Kalscheur MM, Vaidyanathan R, Orland KM, Abozeid S, Fabry N, Maginot KR, January CT, Makielski JC, Eckhardt LL. KCNJ2 mutation causes an adrenergic-dependent rectification abnormality with calcium sensitivity and ventricular arrhythmia. Heart Rhythm 2014; 11:885-94. [PMID: 24561538 DOI: 10.1016/j.hrthm.2014.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND KCNJ2 mutations are associated with a variety of inherited arrhythmia syndromes including catecholaminergic polymorphic ventricular tachycardia 3. OBJECTIVE To characterize the detailed cellular mechanisms of the clinically recognized KCNJ2 mutation R67Q. METHODS Kir2.1 current density was measured from COS-1 cells transiently transfected with wild-type human Kir-2.1 (WT-Kir2.1) and/or a heterozygous missense mutation in KCNJ2 (R67Q-Kir2.1) by using the whole-cell voltage clamp technique. Catecholamine activity was simulated with protein kinase A-stimulating cocktail exposure. Phosphorylation-deficient mutants, S425N-Kir2.1 and S425N-Kir2.1/R67Q-S425N-Kir2.1, were used in a separate set of experiments. HA- or Myc-Tag-WT-Kir2.1 and HA-Tag-R67Q-Kir2.1 were used for confocal imaging. RESULTS A 33-year-old woman presented with a catecholaminergic polymorphic ventricular tachycardia-like clinical phenotype and was found to have KCNJ2 missense mutation R67Q. Treatment with nadolol and flecainide resulted in the complete suppression of arrhythmias and symptom resolution. Under baseline conditions, R67Q-Kir2.1 expressed alone did not produce inward rectifier current while cells coexpressing WT-Kir2.1 and R67Q-Kir2.1 demonstrated the rectification index (RI) similar to that of WT-Kir2.1. After PKA stimulation, R67Q-Kir2.1/WT-Kir2.1 failed to increase peak outward current density; WT-Kir2.1 increased by 46% (n = 5), while R67Q-Kir2.1/WT-Kir2.1 decreased by 6% (n = 6) (P = .002). Rectification properties in R67Q-Kir2.1/WT-Kir2.1 demonstrated sensitivity to calcium with a decreased RI in the high-calcium pipette solution (RI 20.3% ± 4.1%) than in the low-calcium pipette solution (RI 36.5% ± 5.7%) (P < .05). Immunostaining of WT-Kir2.1 and R67Q-Kir2.1 individually and together showed a normal membrane expression pattern and colocalization by using the Pearson correlation coefficient. CONCLUSIONS R67Q-Kir2.1 is associated with an adrenergic-dependent clinical and cellular phenotype with rectification abnormality enhanced by increased calcium. These findings are a significant advancement of our knowledge and understanding of the phenotype-genotype relationship of arrhythmia syndromes related to KCNJ2 mutations.
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Kamikawa A, Ishikawa T. Functional expression of a Kir2.1-like inwardly rectifying potassium channel in mouse mammary secretory cells. Am J Physiol Cell Physiol 2013; 306:C230-40. [PMID: 24259419 DOI: 10.1152/ajpcell.00219.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
K(+) channels in mammary secretory (MS) cells are believed to play a role in transcellular electrolyte transport and thus determining ionic composition of the aqueous phase of milk. However, direct evidence for specific K(+) channel activity in native MS cells is lacking at the single-cell level. Here, we show for the first time that an inwardly rectifying K(+) (Kir) channel is functionally expressed in fully differentiated MS cells that were freshly isolated from the mammary gland of lactating mice. Using the standard whole cell patch-clamp technique, we found that mouse MS cells consistently displayed a K(+) current, whose electrophysiological properties are similar to those previously reported for Kir2.x channels, particularly Kir2.1: 1) current-voltage relationship with strong inward rectification, 2) slope conductance approximately proportional to the square root of external K(+) concentration, 3) voltage- and time-dependent and high-affinity block by external Ba(2+), and 4) voltage-dependent inhibition by external Cs(+). Accordingly, RT-PCR analysis revealed the gene expression of Kir2.1, but not Kir2.2, Kir2.3, and Kir2.4, in lactating mouse mammary gland, and immunohistochemical staining showed Kir2.1 protein expression in the secretory cells. Cell-attached patch recordings from MS cells revealed that a 31-pS K(+) channel with strong inward rectification was likely active at the resting membrane potential. Collectively, the present work demonstrates that a functional Kir2.1-like channel is expressed in lactating mouse MS cells. We propose that the channel might be involved, at least in part, in secretion and/or preservation of ionic components of milk stored into the lumen of these cells.
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Affiliation(s)
- Akihiro Kamikawa
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
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Okada M, Kano M, Matsuda H. The degradation of the inwardly rectifying potassium channel, Kir2.1, depends on the expression level: examination with fluorescent proteins. Brain Res 2013; 1528:8-19. [PMID: 23850646 DOI: 10.1016/j.brainres.2013.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 07/01/2013] [Accepted: 07/05/2013] [Indexed: 01/24/2023]
Abstract
The expression of ion channels is regulated by their synthesis as well as degradation, and some ion channels are degraded in an expression level-dependent way. Recently, new techniques of fluorescent proteins have been developed and seem to be useful to study protein degradation. To examine the regulation of the degradation of strongly inwardly rectifying potassium channel (Kir2.1) and the usefulness of the fluorescent proteins, we constructed Kir2.1 fusion proteins with SNAP tag and fluorescent timer (FT). The SNAP tag, which covalently binds to a specific membrane-permeable fluorescent dye, enables a pulse-chase experiment with fluorescence. When the SNAP-Kir2.1 proteins were expressed in 293T cells by low and high expression plasmids, the half-life of the fusion protein expressed by a high-expression plasmid was shorter (18.2±1.9 h) than that expressed by a low-expression plasmid (35.1+2.3h). The addition of Ba(2+), a selective blocker of Kir2.1, slowed the degradation, suggesting a current-dependency of degradation. Consistently, patch-clamp recording showed that cultivation in the presence of Ba(2+) increased the whole cell conductance of SNAP-Kir2.1. Since the fluorescence of FT changes gradually changes from green to red, the green/red ratio should allow us to monitor the changes in the degradation rate of FT-Kir2.1. Using this method, we confirmed the slower degradation by Ba(2+). The results suggest a homeostatic regulation of the degradation of Kir2.1 in the 293T cells, and the usefulness of fluorescence-based methods for examining the degradation of ion channels.
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Rosenhouse-Dantsker A, Noskov S, Logothetis DE, Levitan I. Cholesterol sensitivity of KIR2.1 depends on functional inter-links between the N and C termini. Channels (Austin) 2013; 7:303-12. [PMID: 23807091 DOI: 10.4161/chan.25437] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In recent years, cholesterol has been emerging as a major regulator of ion channel function. We have previously shown that cholesterol suppresses Kir2 channels, a subfamily of constitutively active strongly rectifying K (+) channels. Furthermore, our earlier studies have shown that cholesterol sensitivity of Kir2 channels depends on a group of residues that form a belt-like structure around the cytosolic pore of the channel in proximity to the transmembrane domain. In this study, we focus on the contributions of different structural domains of Kir2 channels in the regulation of their cholesterol sensitivity. Focusing on the mildest mutation in the sensitivity belt, L222I, we show that the sensitivity of the channel to cholesterol can be restored by crosstalk between three distinct cytosolic regions: the C-terminal CD loop, the EF and GA loops of the C-terminus, and the βA sheet of the N-terminus. Thus, in addition to the importance of residues that affect the cytosolic G-loop gate in the sensitivity of Kir2 channels to cholesterol, our data suggest an important role to the interactions at the interface between the channel's N- and C- termini that couple the intracellular domains of its four subunits during gating.
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