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Yang Z, Li Y, Huang M, Li X, Fan X, Yan C, Meng Z, Liao B, Hamdani N, El-Battrawy I, Yang X, Zhou X, Akin I. Small conductance calcium-activated potassium channel contributes to stress induced endothelial dysfunctions. Microvasc Res 2024; 155:104699. [PMID: 38901735 DOI: 10.1016/j.mvr.2024.104699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 05/26/2024] [Accepted: 06/02/2024] [Indexed: 06/22/2024]
Abstract
Patients with Takotsubo syndrome displayed endothelial dysfunction, but underlying mechanisms have not been fully clarified. This study aimed to explore molecular signalling responsible for catecholamine excess induced endothelial dysfunction. Human cardiac microvascular endothelial cells were challenged by epinephrine to mimic catecholamine excess. Patch clamp, FACS, ELISA, PCR, and immunostaining were employed for the study. Epinephrine (Epi) enhanced small conductance calcium-activated potassium channel current (ISK1-3) through activating α1 adrenoceptor. Phenylephrine enhanced edothelin-1 (ET-1) and reactive oxygen species (ROS) production, and the effects involved contribution of ISK1-3. H2O2 enhanced ISK1-3 and ET-1 production. Enhancing ISK1-3 caused a hyperpolarization, which increases ROS and ET-1 production. BAPTA partially reduced phenylephrine-induced enhancement of ET-1 and ROS, suggesting that α1 receptor activation can enhance ROS/ET-1 generation in both calcium-dependent and calcium-independent ways. The study demonstrates that high concentration catecholamine can activate SK1-3 channels through α1 receptor-ROS signalling and increase ET-1 production, facilitating vasoconstriction.
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Affiliation(s)
- Zhen Yang
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany; Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, 637000 Nanchong, Sichuan, China
| | - Yingrui Li
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Mengying Huang
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Xin Li
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Xuehui Fan
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Chen Yan
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Zenghui Meng
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany
| | - Bin Liao
- Department of Cardiac Macrovascular Surgery, Affiliated Hospital of Southwest Medical University, 646000, Sichuan, China
| | - Nazha Hamdani
- Department of Molecular and Experimental Cardiology, Institut für Forschung und Lehre (IFL), Ruhr-University Bochum, Bochum, Germany
| | - Ibrahim El-Battrawy
- Department of Cardiology and Angiology, Ruhr University, Bochum, Germany; Institut für Forschung und Lehre (IFL), Department of Molecular and Experimental Cardiology, Ruhr-University Bochum, Bochum, Germany
| | - Xiaoli Yang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, 637000 Nanchong, Sichuan, China.
| | - Xiaobo Zhou
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany; European Center for AngioScience (ECAS), German Center for Cardiovascular Research (DZHK) partner site Heidelberg/Mannheim, and Centre for Cardiovascular Acute Medicine Mannheim (ZKAM), Medical Centre Mannheim, Heidelberg University, Germany; Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, 646000, Sichuan, China.
| | - Ibrahim Akin
- First Department of Medicine, Medical Faculty Mannheim, University Medical Centre Mannheim (UMM), Heidelberg University, 68167 Mannheim, Germany; European Center for AngioScience (ECAS), German Center for Cardiovascular Research (DZHK) partner site Heidelberg/Mannheim, and Centre for Cardiovascular Acute Medicine Mannheim (ZKAM), Medical Centre Mannheim, Heidelberg University, Germany
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Functional Characterization of Human Induced Pluripotent Stem Cell-Derived Endothelial Cells. Int J Mol Sci 2022; 23:ijms23158507. [PMID: 35955642 PMCID: PMC9368986 DOI: 10.3390/ijms23158507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 12/03/2022] Open
Abstract
Endothelial cells derived from human induced pluripotent stem cells (hiPSC-ECs) provide a new opportunity for mechanistic research on vascular regeneration and drug screening. However, functions of hiPSC-ECs still need to be characterized. The objective of this study was to investigate electrophysiological and functional properties of hiPSC-ECs compared with primary human cardiac microvascular endothelial cells (HCMECs), mainly focusing on ion channels and membrane receptor signaling, as well as specific cell functions. HiPSC-ECs were derived from hiPS cells that were generated from human skin fibroblasts of three independent healthy donors. Phenotypic and functional comparison to HCMECs was performed by flow cytometry, immunofluorescence staining, quantitative reverse-transcription polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), tube formation, LDL uptake, exosome release assays and, importantly, patch clamp techniques. HiPSC-ECs were successfully generated from hiPS cells and were identified by endothelial markers. The mRNA levels of KCNN2, KCNN4, KCNMA1, TRPV2, and SLC8A1 in hiPSC-ECs were significantly higher than HCMECs. AT1 receptor mRNA level in hiPSC-ECs was higher than in HCMECs. AT2 receptor mRNA level was the highest among all receptors. Adrenoceptor ADRA2 expression in hiPSC-ECs was lower than in HCMECs, while ADRA1, ADRB1, ADRB2, and G-protein GNA11 and Gai expression were similar in both cell types. The expression level of muscarinic and dopamine receptors CHRM3, DRD2, DRD3, and DRD4 in hiPSC-ECs were significantly lower than in HCMECs. The functional characteristics of endothelial cells, such as tube formation and LDL uptake assay, were not statistically different between hiPSC-ECs and HCMECs. Phenylephrine similarly increased the release of the vasoconstrictor endothelin-1 (ET-1) in hiPSC-ECs and HCMECs. Acetylcholine also similarly increased nitric oxide generation in hiPSC-ECs and HCMECs. The resting potentials (RPs), ISK1–3, ISK4 and IK1 were similar in hiPSC-ECs and HCMECs. IBK was larger and IKATP was smaller in hiPSC-ECs. In addition, we also noted a higher expression level of exosomes marker CD81 in hiPSC-ECs and a higher expression of CD9 and CD63 in HCMECs. However, the numbers of exosomes extracted from both types of cells did not differ significantly. The study demonstrates that hiPSC-ECs are similar to native endothelial cells in ion channel function and membrane receptor-coupled signaling and physiological cell functions, although some differences exist. This information may be helpful for research using hiPSC-ECs.
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Ando S, Mizutani H, Muramatsu M, Hagihara Y, Mishima H, Kondo R, Suzuki Y, Imaizumi Y, Yamamura H. Involvement of small-conductance Ca2+-activated K+ (SKCa2) channels in spontaneous Ca2+ oscillations in rat pinealocytes. Biochem Biophys Res Commun 2022; 615:157-162. [DOI: 10.1016/j.bbrc.2022.05.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/14/2022] [Indexed: 11/02/2022]
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Imaizumi Y. Reciprocal Relationship between Ca 2+ Signaling and Ca 2+-Gated Ion Channels as a Potential Target for Drug Discovery. Biol Pharm Bull 2022; 45:1-18. [PMID: 34980771 DOI: 10.1248/bpb.b21-00896] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular Ca2+ signaling functions as one of the most common second messengers of various signal transduction pathways in cells and mediates a number of physiological roles in a cell-type dependent manner. Ca2+ signaling also regulates more general and fundamental cellular activities, including cell proliferation and apoptosis. Among ion channels, Ca2+-permeable channels in the plasma membrane as well as endo- and sarcoplasmic reticulum membranes play important roles in Ca2+ signaling by directly contributing to the influx of Ca2+ from extracellular spaces or its release from storage sites, respectively. Furthermore, Ca2+-gated ion channels in the plasma membrane often crosstalk reciprocally with Ca2+ signals and are central to the regulation of cellular functions. This review focuses on the physiological and pharmacological impact of i) Ca2+-gated ion channels as an apparatus for the conversion of cellular Ca2+ signals to intercellularly propagative electrical signals and ii) the opposite feedback regulation of Ca2+ signaling by Ca2+-gated ion channel activities in excitable and non-excitable cells.
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Affiliation(s)
- Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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Role of K + and Ca 2+-Permeable Channels in Osteoblast Functions. Int J Mol Sci 2021; 22:ijms221910459. [PMID: 34638799 PMCID: PMC8509041 DOI: 10.3390/ijms221910459] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 12/20/2022] Open
Abstract
Bone-forming cells or osteoblasts play an important role in bone modeling and remodeling processes. Osteoblast differentiation or osteoblastogenesis is orchestrated by multiple intracellular signaling pathways (e.g., bone morphogenetic proteins (BMP) and Wnt signaling pathways) and is modulated by the extracellular environment (e.g., parathyroid hormone (PTH), vitamin D, transforming growth factor β (TGF-β), and integrins). The regulation of bone homeostasis depends on the proper differentiation and function of osteoblast lineage cells from osteogenic precursors to osteocytes. Intracellular Ca2+ signaling relies on the control of numerous processes in osteoblast lineage cells, including cell growth, differentiation, migration, and gene expression. In addition, hyperpolarization via the activation of K+ channels indirectly promotes Ca2+ signaling in osteoblast lineage cells. An improved understanding of the fundamental physiological and pathophysiological processes in bone homeostasis requires detailed investigations of osteoblast lineage cells. This review summarizes the current knowledge on the functional impacts of K+ channels and Ca2+-permeable channels, which critically regulate Ca2+ signaling in osteoblast lineage cells to maintain bone homeostasis.
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Suzuki T, Suzuki Y, Asai K, Imaizumi Y, Yamamura H. Hypoxia increases the proliferation of brain capillary endothelial cells via upregulation of TMEM16A Ca 2+-activated Cl - channels. J Pharmacol Sci 2021; 146:65-69. [PMID: 33858657 DOI: 10.1016/j.jphs.2021.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/15/2021] [Accepted: 03/04/2021] [Indexed: 02/07/2023] Open
Abstract
The blood-brain barrier (BBB) is mainly formed by brain capillary endothelial cells (BCECs) and is exposed to hypoxic environments under pathological conditions. The effects of hypoxia on the expression and activity of Ca2+-activated Cl- (ClCa) channels, TMEM16A, were examined in bovine brain endothelial t-BBEC117 cells and mouse BCECs. The expression of TMEM16A was upregulated by hypoxia. Whole-cell ClCa currents increased under hypoxia. Hypoxia also increased cell proliferation and trans-endothelial permeability, which were attenuated by ClCa channel blockers or TMEM16A siRNA. These findings are useful for elucidating the pathological role of TMEM16A ClCa channels in the BBB during cerebral ischemia.
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Affiliation(s)
- Takahisa Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori Mizuhoku, Nagoya 467-8603, Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori Mizuhoku, Nagoya 467-8603, Japan
| | - Kiyofumi Asai
- Department of Molecular Neurobiology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi Mizuhocho Mizuhoku, Nagoya 467-8601, Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori Mizuhoku, Nagoya 467-8603, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori Mizuhoku, Nagoya 467-8603, Japan.
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Nam YW, Kong D, Wang D, Orfali R, Sherpa RT, Totonchy J, Nauli SM, Zhang M. Differential modulation of SK channel subtypes by phosphorylation. Cell Calcium 2021; 94:102346. [PMID: 33422768 PMCID: PMC8415101 DOI: 10.1016/j.ceca.2020.102346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 01/01/2023]
Abstract
Small-conductance Ca2+-activated K+ (SK) channels are voltage-independent and are activated by Ca2+ binding to the calmodulin constitutively associated with the channels. Both the pore-forming subunits and the associated calmodulin are subject to phosphorylation. Here, we investigated the modulation of different SK channel subtypes by phosphorylation, using the cultured endothelial cells as a tool. We report that casein kinase 2 (CK2) negatively modulates the apparent Ca2+ sensitivity of SK1 and IK channel subtypes by more than 5-fold, whereas the apparent Ca2+ sensitivity of the SK3 and SK2 subtypes is only reduced by ∼2-fold, when heterologously expressed on the plasma membrane of cultured endothelial cells. The SK2 channel subtype exhibits limited cell surface expression in these cells, partly as a result of the phosphorylation of its C-terminus by cyclic AMP-dependent protein kinase (PKA). SK2 channels expressed on the ER and mitochondria membranes may protect against cell death. This work reveals the subtype-specific modulation of the apparent Ca2+ sensitivity and subcellular localization of SK channels by phosphorylation in cultured endothelial cells.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Dezhi Kong
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Dong Wang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Rinzhin T Sherpa
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Jennifer Totonchy
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Surya M Nauli
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA.
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Suzuki T, Yasumoto M, Suzuki Y, Asai K, Imaizumi Y, Yamamura H. TMEM16A Ca 2+-Activated Cl - Channel Regulates the Proliferation and Migration of Brain Capillary Endothelial Cells. Mol Pharmacol 2020; 98:61-71. [PMID: 32358165 DOI: 10.1124/mol.119.118844] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 04/20/2020] [Indexed: 11/22/2022] Open
Abstract
The blood-brain barrier (BBB) is essential for the maintenance of homeostasis in the brain. Brain capillary endothelial cells (BCECs) comprise the BBB, and thus a delicate balance between their proliferation and death is required. Although the activity of ion channels in BCECs is involved in BBB functions, the underlying molecular mechanisms remain unclear. In the present study, the molecular components of Ca2+-activated Cl- (ClCa) channels and their physiological roles were examined using mouse BCECs (mBCECs) and a cell line derived from bovine BCECs, t-BBEC117. Expression analyses revealed that TMEM16A was strongly expressed in mBCECs and t-BBEC117 cells. In t-BBEC117 cells, whole-cell Cl- currents were sensitive to the ClCa channel blockers, 100 μM niflumic acid and 10 μM T16Ainh-A01, and were also reduced markedly by small-interfering RNA (siRNA) knockdown of TMEM16A. Importantly, block of ClCa currents with ClCa channel blockers or TMEM16A siRNA induced membrane hyperpolarization. Moreover, treatment with TMEM16A siRNA caused an increase in resting cytosolic Ca2+ concentration ([Ca2+]cyt). T16Ainh-A01 reduced cell viability in a concentration-dependent manner. Either ClCa channel blockers or TMEM16A siRNA also curtailed cell proliferation and migration. Furthermore, ClCa channel blockers attenuated the trans-endothelial permeability. In combination, these results strongly suggest that TMEM16A contributes to ClCa channel conductance and can regulate both the resting membrane potential and [Ca2+]cyt in BCECs. Our data also reveal how these BCECs may be involved in the maintenance of BBB functions, as both the proliferation and migration are altered following changes in channel activity. SIGNIFICANCE STATEMENT: In brain capillary endothelial cells (BCECs) of the blood-brain barrier (BBB), TMEM16A is responsible for Ca2+-activated Cl- channels and can regulate both the resting membrane potential and cytosolic Ca2+ concentration, contributing to the proliferation and migration of BCECs. The present study provides novel information on the molecular mechanisms underlying the physiological functions of BCECs in the BBB and a novel target for therapeutic drugs for disorders associated with dysfunctions in the BBB.
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Affiliation(s)
- Takahisa Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
| | - Miki Yasumoto
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
| | - Kiyofumi Asai
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences (T.S., M.Y., Y.S., Y.I., H.Y.) and Department of Molecular Neurobiology, Graduate School of Medical Sciences (K.A.), Nagoya City University, Nagoya, Japan
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Oxidative stress facilitates cell death by inhibiting Orai1-mediated Ca 2+ entry in brain capillary endothelial cells. Biochem Biophys Res Commun 2019; 523:153-158. [PMID: 31839216 DOI: 10.1016/j.bbrc.2019.12.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 12/06/2019] [Indexed: 12/31/2022]
Abstract
Brain capillary endothelial cells (BCECs) form the blood-brain barrier (BBB) and play an essential role in the regulation of its functions. Oxidative stress accumulates excessive reactive oxygen species (ROS) and facilitates the death of BCECs, leading to a dysfunctional BBB. However, the mechanisms underlying the death of BCECs under oxidative stress remain unclear. In the present study, the effects of oxidative stress on cell viability, ROS production, intracellular Ca2+ concentration, and protein expression were examined using a cell line derived from bovine BCECs, t-BBEC117. When t-BBEC117 cells were exposed to oxidative stress induced by hydrogen peroxide (H2O2, 10-100 μM), cell growth was inhibited in a dose-dependent manner. Oxidative stress by 30 μM H2O2 increased the production of ROS and its effects were blocked by the ROS scavenger, 10 mM N-acetyl-l-cysteine (NAC). In addition, oxidative stress reduced store-operated Ca2+ entry (SOCE) and this decrease was recovered by NAC or the Orai channel activator, 5 μM 2-aminoethyl diphenylborinate (2-APB). The siRNA knockdown of Orai1 revealed that Orai1 was mainly responsible for SOCE channels and its activity was decreased by oxidative stress. However, the protein expression of Orai1 and STIM1 was not affected by oxidative stress. Oxidative stress-induced cell death was rescued by 2-APB, NAC, or the STIM-Orai activating region. In conclusion, oxidative stress reduces Orai1-mediated SOCE and, thus, facilitates the death of BCECs.
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Saeki T, Kimura T, Hashidume K, Murayama T, Yamamura H, Ohya S, Suzuki Y, Nakayama S, Imaizumi Y. Conversion of Ca2+ oscillation into propagative electrical signals by Ca2+-activated ion channels and connexin as a reconstituted Ca2+ clock model for the pacemaker activity. Biochem Biophys Res Commun 2019; 510:242-247. [DOI: 10.1016/j.bbrc.2019.01.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/16/2019] [Indexed: 01/27/2023]
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Abstract
Neuronal survival, electrical signaling and synaptic activity require a well-balanced micro-environment in the central nervous system. This is achieved by the blood-brain barrier (BBB), an endothelial barrier situated in the brain capillaries, that controls near-to-all passage in and out of the brain. The endothelial barrier function is highly dependent on signaling interactions with surrounding glial, neuronal and vascular cells, together forming the neuro-glio-vascular unit. Within this functional unit, connexin (Cx) channels are of utmost importance for intercellular communication between the different cellular compartments. Connexins are best known as the building blocks of gap junction (GJ) channels that enable direct cell-cell transfer of metabolic, biochemical and electric signals. In addition, beyond their role in direct intercellular communication, Cxs also form unapposed, non-junctional hemichannels in the plasma membrane that allow the passage of several paracrine messengers, complementing direct GJ communication. Within the NGVU, Cxs are expressed in vascular endothelial cells, including those that form the BBB, and are eminent in astrocytes, especially at their endfoot processes that wrap around cerebral vessels. However, despite the density of Cx channels at this so-called gliovascular interface, it remains unclear as to how Cx-based signaling between astrocytes and BBB endothelial cells may converge control over BBB permeability in health and disease. In this review we describe available evidence that supports a role for astroglial as well as endothelial Cxs in the regulation of BBB permeability during development as well as in disease states.
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Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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Yamamura H, Suzuki Y, Yamamura H, Asai K, Imaizumi Y. Hypoxic stress up-regulates Kir2.1 expression and facilitates cell proliferation in brain capillary endothelial cells. Biochem Biophys Res Commun 2016; 476:386-392. [DOI: 10.1016/j.bbrc.2016.05.131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 05/25/2016] [Indexed: 11/30/2022]
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14
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Abstract
There are nineteen different receptor proteins for adenosine, adenine and uridine nucleotides, and nucleotide sugars, belonging to three families of G protein-coupled adenosine and P2Y receptors, and ionotropic P2X receptors. The majority are functionally expressed in blood vessels, as purinergic receptors in perivascular nerves, smooth muscle and endothelial cells, and roles in regulation of vascular contractility, immune function and growth have been identified. The endogenous ligands for purine receptors, ATP, ADP, UTP, UDP and adenosine, can be released from different cell types within the vasculature, as well as from circulating blood cells, including erythrocytes and platelets. Many purine receptors can be activated by two or more of the endogenous ligands. Further complexity arises because of interconversion between ligands, notably adenosine formation from the metabolism of ATP, leading to complex integrated responses through activation of different subtypes of purine receptors. The enzymes responsible for this conversion, ectonucleotidases, are present on the surface of smooth muscle and endothelial cells, and may be coreleased with neurotransmitters from nerves. What selectivity there is for the actions of purines/pyrimidines comes from differential expression of their receptors within the vasculature. P2X1 receptors mediate the vasocontractile actions of ATP released as a neurotransmitter with noradrenaline (NA) from sympathetic perivascular nerves, and are located on the vascular smooth muscle adjacent to the nerve varicosities, the sites of neurotransmitter release. The relative contribution of ATP and NA as functional cotransmitters varies with species, type and size of blood vessel, neuronal firing pattern, the tone/pressure of the blood vessel, and in ageing and disease. ATP is also a neurotransmitter in non-adrenergic non-cholinergic perivascular nerves and mediates vasorelaxation via smooth muscle P2Y-like receptors. ATP and adenosine can act as neuromodulators, with the most robust evidence being for prejunctional inhibition of neurotransmission via A1 adenosine receptors, but also prejunctional excitation and inhibition of neurotransmission via P2X and P2Y receptors, respectively. P2Y2, P2Y4 and P2Y6 receptors expressed on the vascular smooth muscle are coupled to vasocontraction, and may have a role in pathophysiological conditions, when purines are released from damaged cells, or when there is damage to the protective barrier that is the endothelium. Adenosine is released during hypoxia to increase blood flow via vasodilator A2A and A2B receptors expressed on the endothelium and smooth muscle. ATP is released from endothelial cells during hypoxia and shear stress and can act at P2Y and P2X4 receptors expressed on the endothelium to increase local blood flow. Activation of endothelial purine receptors leads to the release of nitric oxide, hyperpolarising factors and prostacyclin, which inhibits platelet aggregation and thus ensures patent blood flow. Vascular purine receptors also regulate endothelial and smooth muscle growth, and inflammation, and thus are involved in the underlying processes of a number of cardiovascular diseases.
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Affiliation(s)
- Vera Ralevic
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
| | - William R Dunn
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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Kito H, Yamamura H, Suzuki Y, Yamamura H, Ohya S, Asai K, Imaizumi Y. Regulation of store-operated Ca2+ entry activity by cell cycle dependent up-regulation of Orai2 in brain capillary endothelial cells. Biochem Biophys Res Commun 2015; 459:457-62. [DOI: 10.1016/j.bbrc.2015.02.127] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 02/22/2015] [Indexed: 12/30/2022]
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16
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Ohya S, Nakamura E, Horiba S, Kito H, Matsui M, Yamamura H, Imaizumi Y. Role of the K(Ca)3.1 K+ channel in auricular lymph node CD4+ T-lymphocyte function of the delayed-type hypersensitivity model. Br J Pharmacol 2015; 169:1011-23. [PMID: 23594188 DOI: 10.1111/bph.12215] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 02/18/2013] [Accepted: 03/01/2013] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND AND PURPOSE The intermediate-conductance Ca(2+)-activated K(+) channel (K(Ca)3.1) modulates the Ca(2+) response through the control of the membrane potential in the immune system. We investigated the role of K(Ca)3.1 on the pathogenesis of delayed-type hypersensitivity (DTH) in auricular lymph node (ALN) CD4(+) T-lymphocytes of oxazolone (Ox)-induced DTH model mice. EXPERIMENTAL APPROACH The expression patterns of K(Ca)3.1 and its possible transcriptional regulators were compared among ALN T-lymphocytes of three groups [non-sensitized (Ox-/-), Ox-sensitized, but non-challenged (Ox+/-) and Ox-sensitized and -challenged (Ox+/+)] using real-time polymerase chain reaction, Western blotting and flow cytometry. KCa 3.1 activity was measured by whole-cell patch clamp and the voltage-sensitive dye imaging. The effects of K(Ca)3.1 blockade were examined by the administration of selective K(Ca)3.1 blockers. KEY RESULTS Significant up-regulation of K(Ca)3.1a was observed in CD4(+) T-lymphocytes of Ox+/- and Ox+/+, without any evident changes in the expression of the dominant-negative form, K(Ca)3.1b. Negatively correlated with this, the repressor element-1 silencing transcription factor (REST) was significantly down-regulated. Pharmacological blockade of K(Ca)3.1 resulted in an accumulation of the CD4(+) T-lymphocytes of Ox+/+ at the G0/G1 phase of the cell cycle, and also significantly recovered not only the pathogenesis of DTH, but also the changes in the K(Ca)3.1 expression and activity in the CD4(+) T-lymphocytes of Ox+/- and Ox+/+. CONCLUSIONS AND IMPLICATIONS The up-regulation of K(Ca)3.1a in conjunction with the down-regulation of REST may be involved in CD4(+) T-lymphocyte proliferation in the ALNs of DTH model mice; and K(Ca)3.1 may be an important target for therapeutic intervention in allergy diseases such as DTH.
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Affiliation(s)
- Susumu Ohya
- Department of Molecular & Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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17
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Matsuba S, Niwa S, Muraki K, Kanatsuka S, Nakazono Y, Hatano N, Fujii M, Zhan P, Suzuki T, Ohya S. Downregulation of Ca2+-activated Cl- channel TMEM16A by the inhibition of histone deacetylase in TMEM16A-expressing cancer cells. J Pharmacol Exp Ther 2014; 351:510-8. [PMID: 25232193 DOI: 10.1124/jpet.114.217315] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Ca(2+)-activated Cl(-) channel transmembrane proteins with unknown function 16 A (TMEM16A; also known as anoctamin 1 or discovered on gastrointestinal stromal tumor 1) plays an important role in facilitating the cell growth and metastasis of TMEM16A-expressing cancer cells. Histone deacetylase (HDAC) inhibitors (HDACi) are useful agents for cancer therapy, but it remains unclear whether ion channels are epigenetically regulated by them. Using real-time polymerase chain reaction, Western blot analysis, and whole-cell patch-clamp assays, we found a significant decrease in TMEM16A expression and its functional activity was induced by the vorinostat, a pan-HDACi in TMEM16A-expressing human cancer cell lines, the prostatic cancer cell line PC-3, and the breast cancer cell line YMB-1. TMEM16A downregulation was not induced by the chemotherapy drug paclitaxel in either cell type. Pharmacologic blockade of HDAC3 by 1 μM T247 [N-(2-aminophenyl)-4-[1-(2-thiophen-3-ylethyl)-1H-[1],[2],[3]triazol-4-yl]benzamide], a HDAC3-selective HDACi, elicited a large decrease in TMEM16A expression and functional activity in both cell types, and pharmacologic blockade of HDAC2 by AATB [4-(acetylamino)-N-[2-amino-5-(2-thienyl)phenyl]-benzamide; 300 nM] elicited partial inhibition of TMEM16A expression (∼40%) in both. Pharmacologic blockade of HDAC1 or HDAC6 did not elicit any significant change in TMEM16A expression, respectively. In addition, inhibition of HDAC3 induced by small interfering RNA elicited a large decrease in TMEM16A transcripts in both cell types. Taken together, in malignancies with a frequent gene amplification of TMEM16A, HDAC3 inhibition may exert suppressive effects on cancer cell viability via downregulation of TMEM16A.
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Affiliation(s)
- Sayo Matsuba
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Satomi Niwa
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Katsuhiko Muraki
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Saki Kanatsuka
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Yurika Nakazono
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Noriyuki Hatano
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Masanori Fujii
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Peng Zhan
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Takayoshi Suzuki
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
| | - Susumu Ohya
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto, Japan (S.M., S.N., S.K., Y.N., M.F., S.O.); Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan (K.M., N.H.); and Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan (P.Z., T.S.)
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18
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TREK-King the Blood–Brain-Barrier. J Neuroimmune Pharmacol 2014; 9:293-301. [DOI: 10.1007/s11481-014-9530-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022]
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19
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Kito H, Yamamura H, Suzuki Y, Ohya S, Asai K, Imaizumi Y. Membrane Hyperpolarization Induced by Endoplasmic Reticulum Stress Facilitates Ca2+ Influx to Regulate Cell Cycle Progression in Brain Capillary Endothelial Cells. J Pharmacol Sci 2014; 125:227-32. [DOI: 10.1254/jphs.14002sc] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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20
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Burnstock G, Ralevic V. Purinergic signaling and blood vessels in health and disease. Pharmacol Rev 2013; 66:102-92. [PMID: 24335194 DOI: 10.1124/pr.113.008029] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purinergic signaling plays important roles in control of vascular tone and remodeling. There is dual control of vascular tone by ATP released as a cotransmitter with noradrenaline from perivascular sympathetic nerves to cause vasoconstriction via P2X1 receptors, whereas ATP released from endothelial cells in response to changes in blood flow (producing shear stress) or hypoxia acts on P2X and P2Y receptors on endothelial cells to produce nitric oxide and endothelium-derived hyperpolarizing factor, which dilates vessels. ATP is also released from sensory-motor nerves during antidromic reflex activity to produce relaxation of some blood vessels. In this review, we stress the differences in neural and endothelial factors in purinergic control of different blood vessels. The long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides in promoting migration and proliferation of both vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis and vessel remodeling during restenosis after angioplasty are described. The pathophysiology of blood vessels and therapeutic potential of purinergic agents in diseases, including hypertension, atherosclerosis, ischemia, thrombosis and stroke, diabetes, and migraine, is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK; and Department of Pharmacology, The University of Melbourne, Australia.
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21
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Hydrogen sulfide augments the proliferation and survival of human induced pluripotent stem cell–derived mesenchymal stromal cells through inhibition of BKCa. Cytotherapy 2013; 15:1395-405. [DOI: 10.1016/j.jcyt.2013.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 05/09/2013] [Accepted: 06/16/2013] [Indexed: 01/01/2023]
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22
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Calcium influx through the TRPV1 channel of endothelial cells (ECs) correlates with a stronger adhesion between monocytes and ECs. Adv Med Sci 2013. [PMID: 23183769 DOI: 10.2478/v10039-012-0044-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Atherosclerosis is thought to be initiated by the transendothelial migration of monocytes. In the early stage of this process, the adhesion of monocytes to endothelial cells is supported by an increase in the intracellular concentration of calcium ion ([Ca(2+)]i) in endothelial cells. However, the main source of Ca(2+) has been unclear. In this study, the changes in ionic transmittance and [Ca(2+)]i due to the adhesion of monocytes were continuously measured by an electrophysiological technique and fluorescent imaging. Especially, we focused on transient receptor potential vanilloid channel 1 (TRPV1) as a Ca(2+) channel that could influence the adhesion of monocytes. MATERIAL AND METHODS Whole-cell current was continuously recorded in human umbilical vein endothelial cells (HUVECs) by a patch electrode. RESULTS The adhesion of monocytes (THP-1) induced a transient inward current in HUVECs, as well as an elevation of [Ca(2+)]i. This inward element was abolished by the application of 100 nM SB366,791, a selective antagonist of TRPV1 channel. Furthermore, SB366,791 significantly decreased the number of THP-1 cells that adhered to HUVECs (control: 231 ± 38, SB366,791: 96 ± 16 cells/mm2). CONCLUSION These results suggest that an inward calcium current via the TRPV1 channels of endothelial cells correlates with a stronger adhesion between monocytes and endothelial cells.
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23
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Kuiper EFE, Nelemans A, Luiten P, Nijholt I, Dolga A, Eisel U. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration. Front Pharmacol 2012; 3:107. [PMID: 22701424 PMCID: PMC3372087 DOI: 10.3389/fphar.2012.00107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/19/2012] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium (KCa) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of KCa channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of KCa channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) and the intermediate-conductance (KCa3.1) channel. These channels are activated by submicromolar intracellular Ca2+ concentrations and are voltage independent. Of all KCa channels only the KCa2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of KCa channel activation revealed new roles for KCa2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, KCa2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of KCa2 and KCa3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer’s disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and KCa channel activation.
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Affiliation(s)
- Els F E Kuiper
- Molecular Neurobiology, University of Groningen Groningen, Netherlands
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24
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Ohtani M, Ohura K, Oka T. Involvement of P2X receptors in the regulation of insulin secretion, proliferation and survival in mouse pancreatic β-cells. Cell Physiol Biochem 2011; 28:355-66. [PMID: 21865744 DOI: 10.1159/000331752] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2011] [Indexed: 12/18/2022] Open
Abstract
In order to clarify the functional role of ionotropic purinergic (P2X) receptors in pancreatic β-cells, we examined the effect of several P2 receptor agonists and antagonists on insulin secretion by mouse pancreatic islets, mouse Beta-TC6 cell proliferation and survival of dispersed islet cells in culture. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed the expression of mRNAs of P2X(4) receptor in mouse islets and P2X(1), P2X(2), P2X(3), P2X(4), P2X(5) and P2X(7) receptors in Beta-TC6 cells. The presence of P2X(4) receptor proteins in islets and Beta-TC6 cells was confirmed by immunofluorescent staining and Western blot analysis. We have previously found that the functional P2Y(1) receptor but not P2Y(2) and P2Y(4) receptors was present in islets. In this study we found that a nonspecific P2 receptor agonist, ATP (1 μM) stimulated insulin secretion by islets in the presence of high glucose (20 mM) in culture. The effect of ATP was partially inhibited by a P2 receptor antagonist PPADS as well as a P2Y(1) receptor antagonist MRS2179. In addition, a P2X(4) receptor potentiator ivermectin per se augmented glucose-induced insulin secretion and slightly potentiated the effect of ATP. These results suggested the involvement of P2Y(1)and P2X receptors. We also found that ATP inhibited proliferation of Beta-TC6 cells in a concentration-dependent manner during 72 h culture. The inhibitory effect of ATP was completely reversed by PPADS and partially by treating cells with small interfering RNA targeted for P2X(4) receptor mRNA. Furthermore, we found that the phosphorylation of the extracellular signal-regulated kinase 1 and 2 (ERK1/2) was suppressed by treatment with ATP in Beta-TC6 cells. In addition, we found that ATP reduced the cell viability and DNA synthesis of islet cells in culture. The effect of ATP on the cell viability was blocked by PPADS or MRS2179. These results suggested that P2X receptors as well as the P2Y(1) receptor played a role in the modulation of insulin secretion, proliferation and cell viability in mouse pancreatic β-cells.
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Affiliation(s)
- Masahiro Ohtani
- Department of Pharmacology, Osaka Dental University, Hirakata, Japan
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25
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Kito H, Yamazaki D, Ohya S, Yamamura H, Asai K, Imaizumi Y. Up-regulation of Kir2.1 by ER stress facilitates cell death of brain capillary endothelial cells. Biochem Biophys Res Commun 2011; 411:293-8. [DOI: 10.1016/j.bbrc.2011.06.128] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Accepted: 06/20/2011] [Indexed: 12/20/2022]
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26
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Florea A, Puică C, Vinţan M, Benga I, Crăciun C. Electrophysiological and structural aspects in the frontal cortex after the bee (Apis mellifera) venom experimental treatment. Cell Mol Neurobiol 2011; 31:701-14. [PMID: 21359542 DOI: 10.1007/s10571-011-9667-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 02/14/2011] [Indexed: 11/26/2022]
Abstract
The aim of this study is to evaluate the bioelectrical and structural-functional changes in frontal cortex after the bee venom (BV) experimental treatments simulating both an acute envenomation and a subchronic BV therapy. Wistar rats were subcutaneously injected once with three different BV doses: 700 μg/kg (T(1) group), 2100 μg/kg (T(3) group), and 62 mg/kg (sublethal dose-in T(SL) group), and repeated for 30 days with the lowest dose (700 μg/kg-in T(S) group). BV effects were assessed by electrophysiological, histological, histochemical, and ultrastructural methods. Single BV doses produced discharges of negative and biphasic sharp waves, and epileptiform spike-wave complexes. The increasing frequency of these elements suggested a dose-dependent neuronal hyperexcitation or irritation. As compared to the lower doses, the sublethal dose was responsible for a pronounced toxic effect, confirmed by ultrastructural data in both neurons and glial cells that underwent extensive, irreversible changes, triggering the cellular death. Subchronic BV treatment in T(S) group resulted in a slower frequency and increased amplitude of cortical activity suggesting neuronal loss. However, neurons were still stimulated by the last BV dose. Structural-functional data showed a reduced cellular density in frontal cortex of animals in this group, while the remaining neurons displayed both specific (stimulation of neuronal activity) and unspecific modifications (moderate alterations to necrotic phenomena). Molecular mechanisms involved in BV interactions with the nervous tissue are also discussed. We consider all these data very important for clinicians who manage patients with multiple bee stings, or who intend to set an appropriate BV therapy.
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Affiliation(s)
- Adrian Florea
- Department of Cell and Molecular Biology, "Iuliu Haţieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania.
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Yamazaki D, Kito H, Yamamoto S, Ohya S, Yamamura H, Asai K, Imaizumi Y. Contribution of K(ir)2 potassium channels to ATP-induced cell death in brain capillary endothelial cells and reconstructed HEK293 cell model. Am J Physiol Cell Physiol 2010; 300:C75-86. [PMID: 20980552 DOI: 10.1152/ajpcell.00135.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular turnover of brain capillary endothelial cells (BCECs) by the balance of cell proliferation and death is essential for maintaining the homeostasis of the blood-brain barrier. Stimulation of metabotropic ATP receptors (P2Y) transiently increased intracellular Ca²(+) concentration ([Ca²(+)](i)) in t-BBEC 117, a cell line derived from bovine BCECs. The [Ca²(+)](i) rise induced membrane hyperpolarization via the activation of apamin-sensitive small-conductance Ca²(+)-activated K(+) channels (SK2) and enhanced cell proliferation in t-BBEC 117. Here, we found anomalous membrane hyperpolarization lasting for over 10 min in response to ATP in ∼15% of t-BBEC 117, in which inward rectifier K(+) channel (K(ir)2.1) was extensively expressed. Once anomalous hyperpolarization was triggered by ATP, it was removed by Ba²(+) but not by apamin. Prolonged exposure to ATPγS increased the relative population of t-BBEC 117, in which the expression of K(ir)2.1 mRNAs was significantly higher and Ba²(+)-sensitive anomalous hyperpolarization was observed. The cultivation of t-BBEC 117 in serum-free medium also increased this population and reduced the cell number. The reduction of cell number was enhanced by the addition of ATPγS and the enhancement was antagonized by Ba²(+). In the human embryonic kidney 293 cell model, where SK2 and K(ir)2.1 were heterologously coexpressed, [Ca²(+)](i) rise by P2Y stimulation triggered anomalous hyperpolarization and cell death. In conclusion, P2Y stimulation in BCECs enhances cell proliferation by SK2 activation in the majority of cells but also triggers cell death in a certain population showing a substantial expression of K(ir)2.1. This dual action of P2Y stimulation may effectively facilitate BCEC turnover.
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Affiliation(s)
- Daiju Yamazaki
- Department of Molecular and Cellular Pharmacology, Nagoya City University, Japan
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28
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Funabashi K, Fujii M, Yamamura H, Ohya S, Imaizumi Y. Contribution of chloride channel conductance to the regulation of resting membrane potential in chondrocytes. J Pharmacol Sci 2010; 113:94-9. [PMID: 20453434 DOI: 10.1254/jphs.10026sc] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The contribution of Cl(-) conductance relative to that of K(+) in the regulation of membrane potential was examined using OUMS-27 cells, a model cell-line of human chondrocytes. Application of 100 microM niflumic acid (NFA) and other anion-channel blockers induced significant membrane hyperpolarization. The NFA-sensitive membrane current under voltage-clamp was predominantly Cl(-) current. Application of NFA induced small but significant increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) and markedly enhanced the late component of [Ca(2+)](i) rise induced by 1 microM histamine. In conclusion, Cl(-) conductance substantially contributes to the regulation of resting membrane potential and [Ca(2+)](i) in OUMS-27 cells.
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Affiliation(s)
- Kenji Funabashi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Japan
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Funabashi K, Ohya S, Yamamura H, Hatano N, Muraki K, Giles W, Imaizumi Y. Accelerated Ca2+ entry by membrane hyperpolarization due to Ca2+-activated K+ channel activation in response to histamine in chondrocytes. Am J Physiol Cell Physiol 2010; 298:C786-97. [DOI: 10.1152/ajpcell.00469.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In articular cartilage inflammation, histamine release from mast cells is a key event. It can enhance cytokine production and matrix synthesis and also promote cell proliferation by stimulating chondrocytes. In this study, the functional impact of Ca2+-activated K+ (KCa) channels in the regulation of intracellular Ca2+ concentration ([Ca2+]i) in chondrocytes in response to histamine was examined using OUMS-27 cells, as a model of chondrocytes derived from human chondrosarcoma. Application of histamine induced a significant [Ca2+]i rise and also membrane hyperpolarization, and both effects were mediated by the stimulation of H1 receptors. The histamine-induced membrane hyperpolarization was attenuated to ∼50% by large-conductance KCa (BK) channel blockers, and further reduced by intermediate (IK) and small conductance KCa (SK) channel blockers. The tonic component of histamine-induced [Ca2+]i rise strongly depended on the presence of extracellular Ca2+ ([Ca2+]o) and was markedly reduced by La3+ or Gd3+ but not by nifedipine. It was significantly attenuated by BK channel blockers, and further blocked by the cocktail of BK, IK, and SK channel blockers. The KCa blocker cocktail also significantly reduced the store-operated Ca2+ entry (SOCE), which was induced by Ca2+ addition after store-depletion by thapsigargin in [Ca2+]o free solution. Our results demonstrate that the histamine-induced membrane hyperpolarization in chondrocytes due to KCa channel activation contributes to sustained Ca2+ entry mainly through SOCE channels in OUMS-27 cells. Thus, KCa channels appear to play an important role in the positive feedback mechanism of [Ca2+]i regulation in chondrocytes in the presence of articular cartilage inflammation.
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Affiliation(s)
- Kenji Funabashi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Susumu Ohya
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Noriyuki Hatano
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan; and
| | - Katsuhiko Muraki
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya, Japan; and
| | - Wayne Giles
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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Murata H, Hotta S, Sawada E, Yamamura H, Ohya S, Kita S, Iwamoto T, Imaizumi Y. Cellular Ca2+ Dynamics in Urinary Bladder Smooth Muscle From Transgenic Mice Overexpressing Na+-Ca2+ Exchanger. J Pharmacol Sci 2010; 112:373-7. [DOI: 10.1254/jphs.09319sc] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Wei JF, Wei L, Zhou X, Lu ZY, Francis K, Hu XY, Liu Y, Xiong WC, Zhang X, Banik NL, Zheng SS, Yu SP. Formation of Kv2.1-FAK complex as a mechanism of FAK activation, cell polarization and enhanced motility. J Cell Physiol 2008; 217:544-57. [PMID: 18615577 DOI: 10.1002/jcp.21530] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Focal adhesion kinase (FAK) plays key roles in cell adhesion and migration. We now report that the delayed rectifier Kv2.1 potassium channel, through its LD-like motif in N-terminus, may interact with FAK and enhance phosphorylation of FAK(397) and FAK(576/577). Overlapping distribution of Kv2.1 and FAK was observed on soma and proximal dendrites of cortical neurons. FAK expression promotes a polarized membrane distribution of the Kv2.1 channel. In Kv2.1-transfected CHO cells, formation of the Kv2.1-FAK complex was stimulated by fibronectin/integrin and inhibited by the K(+) channel blocker tetraethylammonium (TEA). FAK phosphorylation was minimized by shRNA knockdown of the Kv2.1 channel, point mutations of the N-terminus, and TEA, respectively. Cell migration morphology was altered by Kv2.1 knockdown or TEA, hindering cell migration activity. In wound healing tests in vitro and a traumatic injury animal model, Kv2.1 expression and co-localization of Kv2.1 and FAK significantly enhanced directional cell migration and wound closure. It is suggested that the Kv2.1 channel may function as a promoting signal for FAK activation and cell motility.
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Affiliation(s)
- Jian-Feng Wei
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Health China, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Fiorio Pla A, Grange C, Antoniotti S, Tomatis C, Merlino A, Bussolati B, Munaron L. Arachidonic acid-induced Ca2+ entry is involved in early steps of tumor angiogenesis. Mol Cancer Res 2008; 6:535-45. [PMID: 18403634 DOI: 10.1158/1541-7786.mcr-07-0271] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Growth factor-induced intracellular calcium signals in endothelial cells regulate cytosolic and nuclear events involved in the angiogenic process. Among the intracellular messengers released after proangiogenic stimulation, arachidonic acid (AA) plays a key role and its effects are strictly related to calcium homeostasis and cell proliferation. Here, we studied AA-induced intracellular calcium signals in endothelial cells derived from human breast carcinomas (B-TEC). AA promotes B-TEC proliferation and organization of vessel-like structures in vitro. The effect is directly mediated by the fatty acid without a significant contribution of its metabolites. AA induces Ca(2+)(i) signals in the entire capillary-like structure during the early phases of tubulogenesis in vitro. No such responses are detectable in B-TECs organized in more structured tubules. In B-TECs growing in monolayer, AA induces two different signals: a Ca(2+)(i) increase due to Ca(2+) entry and an inhibition of store-dependent Ca(2+) entry induced by thapsigargin or ATP. An inhibitor of Ca(2+) entry and angiogenesis, carboxyamidotriazole, significantly and specifically decreases AA-induced B-TEC tubulogenesis, as well as AA-induced Ca(2+) signals in B-TECs. We conclude that (a) AA-activated Ca(2+) entry is associated with the progression through the early phases of angiogenesis, mainly involving proliferation and tubulogenesis, and it is down-regulated during the reorganization of tumor-derived endothelial cells in capillary-like structures; and (b) inhibition of AA-induced Ca(2+) entry may contribute to the antiangiogenic action of carboxyamidotriazole.
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Affiliation(s)
- Alessandra Fiorio Pla
- Department of Animal and Human Biology, University of Torino, Via Accademia Albertina 13, 10123 Turin, Italy.
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Ayus JC, Achinger SG, Arieff A. Brain cell volume regulation in hyponatremia: role of sex, age, vasopressin, and hypoxia. Am J Physiol Renal Physiol 2008; 295:F619-24. [PMID: 18448591 DOI: 10.1152/ajprenal.00502.2007] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Hyponatremia is the most common electrolyte abnormality in hospitalized patients. When symptomatic (hyponatremic encephalopathy), the overall morbidity is 34%. Individuals most susceptible to death or permanent brain damage are prepubescent children and menstruant women. Failure of the brain to adapt to the hyponatremia leads to brain damage. Major factors that can impair brain adaptation include hypoxia and peptide hormones. In children, physical factors--discrepancy between skull size and brain size--are important in the genesis of brain damage. In adults, certain hormones--estrogen and vasopressin (usually elevated in cases of hyponatremia)--have been shown to impair brain adaptation, decreasing both cerebral blood flow and oxygen utilization. Initially, hyponatremia leads to an influx of water into the brain, primarily through glial cells and largely via the water channel aquaporin (AQP)4. Water is thus shunted into astrocytes, which swell, largely preserving neuronal cell volume. The initial brain response to swelling is adaptation, utilizing the Na(+)-K(+)-ATPase system to extrude cellular Na(+). In menstruant women, estrogen + vasopressin inhibits the Na(+)-K(+)-ATPase system and decreases cerebral oxygen utilization, impairing brain adaptation. Cerebral edema compresses the respiratory centers and also forces blood out of the brain, both lowering arterial Po(2) and decreasing oxygen utilization. The hypoxemia further impairs brain adaptation. Hyponatremic encephalopathy leads to brain damage when brain adaptation is impaired and is a consequence of both cerebral hypoxia and peptide hormones.
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Affiliation(s)
- Juan Carlos Ayus
- Renal Consultants of Houston, 2412 Westgate Street, Houston, TX 77019, USA.
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Millar ID, Wang S, Brown PD, Barrand MA, Hladky SB. Kv1 and Kir2 potassium channels are expressed in rat brain endothelial cells. Pflugers Arch 2007; 456:379-91. [DOI: 10.1007/s00424-007-0377-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 10/23/2007] [Indexed: 12/01/2022]
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Yamazaki D, Ohya S, Asai K, Imaizumi Y. Characteristics of the ATP-induced Ca2+-entry pathway in the t-BBEC 117 cell line derived from bovine brain endothelial cells. J Pharmacol Sci 2007; 104:103-7. [PMID: 17485915 DOI: 10.1254/jphs.sc0070080] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
ATP-receptor (P2Y) stimulation induced sustained Ca2+-entry, which was essential for the enhanced cell-proliferation in t-BBEC117, an immortalized cell-line derived from bovine brain endothelial cells. Application of Ca2+ following store-depletion with thapsigargin in Ca2+-free solution induced Ca2+-entry through store-operated channels (SOCs). Ca2+-entry induced by ATP or 1-oleoyl-2-acetyl-sn-glycerol (OAG) together with Ca2+ was significantly larger than that by Ca2+ alone, suggesting the involvement of receptor-operated channels (ROCs) in the Ca2+-entry. Results obtained using pharmacological tools suggest that the contribution of Ca2+ sources to ATP-induced [Ca2+]i rise in t-BBEC117 is estimated as approximately 2:1:2 for Ca2+-release and Ca2+-entry though SOCs and ROCs, respectively.
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Affiliation(s)
- Daiju Yamazaki
- Department of Molecular & Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Japan
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Wang J, Xu YQ, Liang YY, Gongora R, Warnock DG, Ma HP. An intermediate-conductance Ca(2+)-activated K (+) channel mediates B lymphoma cell cycle progression induced by serum. Pflugers Arch 2007; 454:945-56. [PMID: 17429684 DOI: 10.1007/s00424-007-0258-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 03/18/2007] [Indexed: 01/12/2023]
Abstract
We have previously reported that Kv1.3 channel is expressed in Daudi cells. However, the present study demonstrates that Daudi cell cycle progression is not affected by margatoxin, a Kv1.3 channel blocker, but can be suppressed by tetraethylammonium (TEA) and 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34), a selective blocker of intermediate-conductance Ca(2+)-activated K(+) (IK) channels. Our patch-clamp data indicate that Daudi cells express an IK channel because it has a unit conductance of about 30 pS, is voltage-independent, and can be activated by submicromolar Ca(2+) and blocked by TRAM-34. Fetal bovine serum (FBS) elevated intracellular Ca(2+) concentration ([Ca(2+)](i)) and activated this IK channel. Conversely, Rituximab, a human-mouse chimeric monoclonal antibody of CD20, significantly decreased [Ca(2+)](i) and inhibited the channel. Furthermore, both FBS-induced IK channel expression and cell cycle progression were attenuated by the treatment with LY-294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. These data together suggest that a growth factor(s) in FBS triggers cell cycle progression by elevating both IK channel activity via CD20 and IK channel expression on the cell surface via PI3K. Thus, elevated IK channel activity and expression may account, in part, for Daudi cell malignant growth and proliferation.
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Affiliation(s)
- Jing Wang
- Department of Medicine, University of Alabama at Birmingham, 1530 Third Avenue South, Zeigler Research Building 510, Birmingham, AL, 35294-0017, USA
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