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Cerchiara AG, Imbrici P, Quarta R, Cristiano E, Boccanegra B, Caputo E, Wells DJ, Cappellari O, De Luca A. Ion channels as biomarkers of altered myogenesis in myofiber precursors of Duchenne muscular dystrophy. Ann N Y Acad Sci 2024; 1534:130-144. [PMID: 38517756 DOI: 10.1111/nyas.15124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/20/2024] [Accepted: 02/15/2024] [Indexed: 03/24/2024]
Abstract
Myogenesis is essential for skeletal muscle formation, growth, and regeneration and can be altered in Duchenne muscular dystrophy (DMD), an X-linked disorder due to the absence of the cytoskeletal protein dystrophin. Ion channels play a pivotal role in muscle differentiation and interact with the dystrophin complex. To investigate ion channel involvement in myogenesis in dystrophic settings, we performed electrophysiological characterization of two immortalized mouse cell lines, wild-type (WT) H2K-2B4 and the dystrophic (DYS) H2K-SF1, and measured gene expression of differentiation markers and ion channels. Inward and outward currents/density increased as differentiation progressed in both WT and DYS cells. However, day-11 DYS cells showed higher (27%) inward current density with an increased expression ratio of Scn5a/Scn4a and decreased (48%) barium-sensitive outward current compared to WT. Furthermore, day-11 DYS cells showed more positive resting membrane potential (+10 mV) and lower membrane capacitance (50%) compared to WT. DYS cells also had reduced Myog and Myf5 expression at days 6 and 11. Overall, ion channel profile and myogenesis appeared altered in DYS cells. These results are a first step in validating ion channels as potential drug targets to ameliorate muscle degeneration in DMD settings and as differentiation biomarkers in innovative platforms.
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Affiliation(s)
| | - Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Raffaella Quarta
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Enrica Cristiano
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Brigida Boccanegra
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Erika Caputo
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Dominic J Wells
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
| | - Ornella Cappellari
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
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Van NTH, Kim WK, Nam JH. Challenges in the Therapeutic Targeting of KCa Channels: From Basic Physiology to Clinical Applications. Int J Mol Sci 2024; 25:2965. [PMID: 38474212 PMCID: PMC10932353 DOI: 10.3390/ijms25052965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 03/14/2024] Open
Abstract
Calcium-activated potassium (KCa) channels are ubiquitously expressed throughout the body and are able to regulate membrane potential and intracellular calcium concentrations, thereby playing key roles in cellular physiology and signal transmission. Consequently, it is unsurprising that KCa channels have been implicated in various diseases, making them potential targets for pharmaceutical interventions. Over the past two decades, numerous studies have been conducted to develop KCa channel-targeting drugs, including those for disorders of the central and peripheral nervous, cardiovascular, and urinary systems and for cancer. In this review, we synthesize recent findings regarding the structure and activating mechanisms of KCa channels. We also discuss the role of KCa channel modulators in therapeutic medicine. Finally, we identify the major reasons behind the delay in bringing these modulators to the pharmaceutical market and propose new strategies to promote their application.
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Affiliation(s)
- Nhung Thi Hong Van
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
- Department of Internal Medicine, Graduate School of Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
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Gao X, Di X, Li J, Kang Y, Xie W, Sun L, Zhang J. Extracellular ATP-induced calcium oscillations regulating the differentiation of osteoblasts through aerobic oxidation metabolism pathways. J Bone Miner Metab 2023; 41:606-620. [PMID: 37418073 DOI: 10.1007/s00774-023-01449-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 06/08/2023] [Indexed: 07/08/2023]
Abstract
INTRODUCTION The increase of ATP concentration in the extracellular space represents one of the effective signals that stimulate the physiological activities of cells when the bone is exposed to external mechanical stimulation such as stretching and shear stress force throughout life. However, the effects of ATP on osteoblast differentiation and related mechanisms are not well understood. MATERIALS AND METHODS In this study, the roles of extracellular ATP on osteoblast differentiation, intracellular calcium ([Ca2+]i) levels, metabolomics, and the expression of proteins related to energy metabolism were investigated. RESULTS Our results showed that 100 μM extracellular ATP initiated intracellular calcium ([Ca2+]i) oscillations via the calcium-sensing receptor (P2R) and promoted the differentiation of MC3T3-E1 cells. Metabolomics analysis showed that the differentiation of MC3T3-E1 cells depended on aerobic oxidation, but little glycolysis. Moreover, the differentiation of MC3T3-E1 cells and aerobic oxidation were suppressed with the inhibition of AMP-activated protein kinase (AMPK). CONCLUSION These results indicate that calcium oscillations triggered by extracellular ATP can activate aerobic oxidation through AMPK-related signaling pathways and thus promote osteoblast differentiation.
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Affiliation(s)
- Xiaohang Gao
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China
| | - Xiaohui Di
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China
| | - Jingjing Li
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China
| | - Yiting Kang
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China
| | - Wenjun Xie
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China
| | - Lijun Sun
- Institute of Sports Biology, Shaanxi Normal University, Xi'an, 710119, China.
| | - Jianbao Zhang
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 711049, China.
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Ferguson CA, Santangelo C, Marramiero L, Farina M, Pietrangelo T, Cheng X. Broadband Electrical Spectroscopy to Distinguish Single-Cell Ca 2+ Changes Due to Ionomycin Treatment in a Skeletal Muscle Cell Line. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094358. [PMID: 37177559 PMCID: PMC10181519 DOI: 10.3390/s23094358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/22/2023] [Accepted: 04/26/2023] [Indexed: 05/15/2023]
Abstract
Many skeletal muscle diseases such as muscular dystrophy, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and sarcopenia share the dysregulation of calcium (Ca2+) as a key mechanism of disease at a cellular level. Cytosolic concentrations of Ca2+ can signal dysregulation in organelles including the mitochondria, nucleus, and sarcoplasmic reticulum in skeletal muscle. In this work, a treatment is applied to mimic the Ca2+ increase associated with these atrophy-related disease states, and broadband impedance measurements are taken for single cells with and without this treatment using a microfluidic device. The resulting impedance measurements are fitted using a single-shell circuit simulation to show calculated electrical dielectric property contributions based on these Ca2+ changes. From this, similar distributions were seen in the Ca2+ from fluorescence measurements and the distribution of the S-parameter at a single frequency, identifying Ca2+ as the main contributor to the electrical differences being identified. Extracted dielectric parameters also showed different distribution patterns between the untreated and ionomycin-treated groups; however, the overall electrical parameters suggest the impact of Ca2+-induced changes at a wider range of frequencies.
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Affiliation(s)
- Caroline A Ferguson
- Department of Bioengineering, P.C. Rossin College of Engineering and Applied Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Carmen Santangelo
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" Chieti-Pescara, 66100 Chieti, Italy
| | - Lorenzo Marramiero
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" Chieti-Pescara, 66100 Chieti, Italy
| | - Marco Farina
- Department of Engineering of Information, University Politecnica delle Marche, 60131 Ancona, Italy
| | - Tiziana Pietrangelo
- Department of Neuroscience, Imaging and Clinical Sciences, University "G. d'Annunzio" Chieti-Pescara, 66100 Chieti, Italy
| | - Xuanhong Cheng
- Department of Bioengineering, P.C. Rossin College of Engineering and Applied Sciences, Lehigh University, Bethlehem, PA 18015, USA
- Department of Materials Science and Engineering, P.C. Rossin College of Engineering and Applied Sciences, Lehigh University, Bethlehem, PA 18015, USA
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Takács R, Kovács P, Ebeid RA, Almássy J, Fodor J, Ducza L, Barrett-Jolley R, Lewis R, Matta C. Ca2+-Activated K+ Channels in Progenitor Cells of Musculoskeletal Tissues: A Narrative Review. Int J Mol Sci 2023; 24:ijms24076796. [PMID: 37047767 PMCID: PMC10095002 DOI: 10.3390/ijms24076796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/01/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023] Open
Abstract
Musculoskeletal disorders represent one of the main causes of disability worldwide, and their prevalence is predicted to increase in the coming decades. Stem cell therapy may be a promising option for the treatment of some of the musculoskeletal diseases. Although significant progress has been made in musculoskeletal stem cell research, osteoarthritis, the most-common musculoskeletal disorder, still lacks curative treatment. To fine-tune stem-cell-based therapy, it is necessary to focus on the underlying biological mechanisms. Ion channels and the bioelectric signals they generate control the proliferation, differentiation, and migration of musculoskeletal progenitor cells. Calcium- and voltage-activated potassium (KCa) channels are key players in cell physiology in cells of the musculoskeletal system. This review article focused on the big conductance (BK) KCa channels. The regulatory function of BK channels requires interactions with diverse sets of proteins that have different functions in tissue-resident stem cells. In this narrative review article, we discuss the main ion channels of musculoskeletal stem cells, with a focus on calcium-dependent potassium channels, especially on the large conductance BK channel. We review their expression and function in progenitor cell proliferation, differentiation, and migration and highlight gaps in current knowledge on their involvement in musculoskeletal diseases.
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Affiliation(s)
- Roland Takács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Patrik Kovács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Rana Abdelsattar Ebeid
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, Semmelweis University, H-1428 Budapest, Hungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - László Ducza
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Richard Barrett-Jolley
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Rebecca Lewis
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Csaba Matta
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
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Chen L, Hassani Nia F, Stauber T. Ion Channels and Transporters in Muscle Cell Differentiation. Int J Mol Sci 2021; 22:13615. [PMID: 34948411 PMCID: PMC8703453 DOI: 10.3390/ijms222413615] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/04/2021] [Accepted: 12/14/2021] [Indexed: 01/12/2023] Open
Abstract
Investigations on ion channels in muscle tissues have mainly focused on physiological muscle function and related disorders, but emerging evidence supports a critical role of ion channels and transporters in developmental processes, such as controlling the myogenic commitment of stem cells. In this review, we provide an overview of ion channels and transporters that influence skeletal muscle myoblast differentiation, cardiac differentiation from pluripotent stem cells, as well as vascular smooth muscle cell differentiation. We highlight examples of model organisms or patients with mutations in ion channels. Furthermore, a potential underlying molecular mechanism involving hyperpolarization of the resting membrane potential and a series of calcium signaling is discussed.
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Affiliation(s)
- Lingye Chen
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany;
- Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China
| | - Fatemeh Hassani Nia
- Institute for Molecular Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany;
| | - Tobias Stauber
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany;
- Institute for Molecular Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany;
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Iseki Y, Ono Y, Hibi C, Tanaka S, Takeshita S, Maejima Y, Kurokawa J, Murakawa M, Shimomura K, Sakamoto K. Opening of Intermediate Conductance Ca 2+-Activated K + Channels in C2C12 Skeletal Muscle Cells Increases the Myotube Diameter via the Akt/Mammalian Target of Rapamycin Pathway. J Pharmacol Exp Ther 2020; 376:454-462. [PMID: 33376149 DOI: 10.1124/jpet.120.000290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/23/2020] [Indexed: 11/22/2022] Open
Abstract
The activation of potassium channels and the ensuing hyperpolarization in skeletal myoblasts are essential for myogenic differentiation. However, the effects of K+ channel opening in myoblasts on skeletal muscle mass are unclear. Our previous study revealed that pharmacological activation of intermediate conductance Ca2+-activated K+ channels (IKCa channels) increases myotube formation. In this study, we investigated the effects of 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a Ca2+-activated K+ channel opener, on the mass of skeletal muscle. Application of DCEBIO to C2C12 cells during myogenesis increased the diameter of C2C12 myotubes in a concentration-dependent manner. This DCEBIO-induced hypertrophy was abolished by gene silencing of IKCa channels. However, it was resistant to 1 µM but sensitive to 10 µM TRAM-34, a specific IKCa channel blocker. Furthermore, DCEBIO reduced the mitochondrial membrane potential by opening IKCa channels. Therefore, DCEBIO should increase myotube mass by opening of IKCa channels distributed in mitochondria. Pharmacological studies revealed that mitochondrial reactive oxygen species (mitoROS), Akt, and mammalian target of rapamycin (mTOR) are involved in DCEBIO-induced myotube hypertrophy. An additional study demonstrated that DCEBIO-induced muscle hypertrophic effects are only observed when applied in the early stage of myogenic differentiation. In an in vitro myotube inflammatory atrophy experiment, DCEBIO attenuated the reduction of myotube diameter induced by endotoxin. Thus, we concluded that DCEBIO increases muscle mass by activating the IKCa channel/mitoROS/Akt/mTOR pathway. Our study suggests the potential of DCEBIO in the treatment of muscle wasting diseases. SIGNIFICANCE STATEMENT: Our study shows that 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a small molecule opener of Ca2+-activated K+ channel, increased muscle diameter via the mitochondrial reactive oxygen species/Akt/mammalian target of rapamycin pathway. And DCEBIO overwhelms C2C12 myotube atrophy induced by endotoxin challenge. Our report should inform novel role of K+ channel in muscle development and novel usage of K+ channel opener such as for the treatment of muscle wasting diseases.
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Affiliation(s)
- Yuzo Iseki
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Yuko Ono
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Chihiro Hibi
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Shoko Tanaka
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Shunya Takeshita
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Yuko Maejima
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Junko Kurokawa
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Masahiro Murakawa
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Kenju Shimomura
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
| | - Kazuho Sakamoto
- Departments of Bioregulation and Pharmacological Medicine (Y.I., Y.O., S.T., Y.M., K.Sh., K.Sa.) and Anesthesiology (Y.I., M.M.), Fukushima Medical University, School of Medicine, Fukushima, Japan; Department of Disaster and Emergency Medicine, Kobe University Graduate School of Medicine, Hyogo, Japan (Y.O.); and Department of Bio-Informational Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka-shi, Shizuoka, Japan (C.H., S.T., J.K., K.Sa.)
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Fine Tuning of Calcium Constitutive Entry by Optogenetically-Controlled Membrane Polarization: Impact on Cell Migration. Cells 2020; 9:cells9071684. [PMID: 32668787 PMCID: PMC7408270 DOI: 10.3390/cells9071684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 11/16/2022] Open
Abstract
Anomalies in constitutive calcium entry (CCE) have been commonly attributed to cell dysfunction in pathological conditions such as cancer. Calcium influxes of this type rely on channels, such as transient receptor potential (TRP) channels, to be constitutively opened and strongly depend on membrane potential and a calcium driving force. We developed an optogenetic approach based on the expression of the halorhodopsin chloride pump to study CCE in non-excitable cells. Using C2C12 cells, we found that halorhodopsin can be used to achieve a finely tuned control of membrane polarization. Escalating the membrane polarization by incremental changes in light led to a concomitant increase in CCE through transient receptor potential vanilloid 2 (TRPV2) channels. Moreover, light-induced calcium entry through TRPV2 channels promoted cell migration. Our study shows for the first time that by modulating CCE and related physiological responses, such as cell motility, halorhodopsin serves as a potentially powerful tool that could open new avenues for the study of CCE and associated cellular behaviors.
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Manfroni G, Ragonese F, Monarca L, Astolfi A, Mancinelli L, Iannitti RG, Bastioli F, Barreca ML, Cecchetti V, Fioretti B. New Insights on KCa3.1 Channel Modulation. Curr Pharm Des 2020; 26:2096-2101. [PMID: 32175839 DOI: 10.2174/1381612826666200316152645] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 03/11/2020] [Indexed: 11/22/2022]
Abstract
The human intermediate conductance calcium-activated potassium channel, KCa3.1, is involved in several pathophysiological conditions playing a critical role in cell secretory machinery and calcium signalling. The recent cryo-EM analysis provides new insights for understanding the modulation by both endogenous and pharmacological agents. A typical feature of this channel is the low open probability in saturating calcium concentrations and its modulation by potassium channel openers (KCOs), such as benzo imidazolone 1-EBIO, without changing calcium-dependent activation. In this paper, we proposed a model of KCOs action in the modulation of channel activity. The KCa3.1 channel has a very rich pharmacological profile with several classes of molecules that selectively interact with different binding sites of the channel. Among them, benzo imidazolones can be openers (positive modulators such as 1-EBIO, DC-EBIO) or blockers (negative modulators such as NS1619). Through computation modelling techniques, we identified the 1,4-benzothiazin-3-one as a promising scaffold to develop new KCa3.1 channel modulators. Further studies are needed to explore the potential use of 1-4 benzothiazine- 3-one in KCa3.1 modulation and its pharmacological application.
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Affiliation(s)
- Giuseppe Manfroni
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Francesco Ragonese
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.,Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy
| | - Lorenzo Monarca
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.,Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy
| | - Andrea Astolfi
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Loretta Mancinelli
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | | | | | - Maria L Barreca
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Violetta Cecchetti
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Bernard Fioretti
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
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10
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Sakamoto K. [A Cellular Pharmacological Approach to the Development of Drugs to Treat Muscle Wasting]. YAKUGAKU ZASSHI 2018; 138:1271-1275. [PMID: 30270271 DOI: 10.1248/yakushi.18-00091-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle atrophy reduces quality of life and increases mortality. However, there are few available drugs for the treatment of muscle atrophy. Recently, cell signaling pathways involved in skeletal muscle atrophy or hypertrophy have been determined. To develop drugs for skeletal muscle atrophy, we have studied compounds which modulate pathways of myogenic differentiation, a pivotal step for the maintenance of skeletal muscle mass. First, we examined a K+ channel opener on myogenic differentiation, since hyperpolarization is a trigger for skeletal muscle differentiation. 5,6-Dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), an opener of the small/intermediate conductance Ca2+ activated K+ (SKCa/IKCa) channels, increases myogenic differentiation in C2C12 mouse skeletal myoblasts. This effect was inhibited by TRAM-34, an IKCa channel blocker. This suggests that K+ channels in skeletal muscle stem cells are potential targets for an anti-muscle atrophy drug. Next, we searched for drugs which prevent sepsis-induced muscle atrophy. Lipopolysaccharide (LPS), an inducer of sepsis, attenuates myogenic differentiation in C2C12 myoblasts. LPS also increases the protein expression of myostatin and activates NFκB during differentiation. The TLR4 signal inhibitor TAK-242, and an anti-TNFα neutralizing antibody, reduce these inflammatory responses. Our data suggest that LPS inhibits myogenic differentiation via the NFκB/TNFα pathway. This pathway may be involved in the development of muscle wasting caused by sepsis.
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Affiliation(s)
- Kazuho Sakamoto
- Department of Pharmacology, School of Medicine, Fukushima Medical University
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Sforna L, Megaro A, Pessia M, Franciolini F, Catacuzzeno L. Structure, Gating and Basic Functions of the Ca2+-activated K Channel of Intermediate Conductance. Curr Neuropharmacol 2018; 16:608-617. [PMID: 28875832 PMCID: PMC5997868 DOI: 10.2174/1570159x15666170830122402] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/21/2017] [Accepted: 07/22/2017] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND The KCa3.1 channel is the intermediate-conductance member of the Ca2+- activated K channel superfamily. It is widely expressed in excitable and non-excitable cells, where it plays a major role in a number of cell functions. This paper aims at illustrating the main structural, biophysical and modulatory properties of the KCa3.1 channel, and providing an account of experimental data on its role in volume regulation and Ca2+ signals. METHODS Research and online content related to the structure, structure/function relationship, and physiological role of the KCa3.1 channel are reviewed. RESULTS Expressed in excitable and non-excitable cells, the KCa3.1 channel is voltage independent, its opening being exclusively gated by the binding of intracellular Ca2+ to calmodulin, a Ca2+- binding protein constitutively associated with the C-terminus of each KCa3.1 channel α subunit. The KCa3.1 channel activates upon high affinity Ca2+ binding, and in highly coordinated fashion giving steep Hill functions and relatively low EC50 values (100-350 nM). This high Ca2+ sensitivity is physiologically modulated by closely associated kinases and phosphatases. The KCa3.1 channel is normally activated by global Ca2+ signals as resulting from Ca2+ released from intracellular stores, or by the refilling influx through store operated Ca2+ channels, but cases of strict functional coupling with Ca2+-selective channels are also found. KCa3.1 channels are highly expressed in many types of cells, where they play major roles in cell migration and death. The control of these complex cellular processes is achieved by KCa3.1 channel regulation of the driving force for Ca2+ entry from the extracellular medium, and by mediating the K+ efflux required for cell volume control. CONCLUSION Much work remains to be done to fully understand the structure/function relationship of the KCa3.1 channels. Hopefully, this effort will provide the basis for a beneficial modulation of channel activity under pathological conditions.
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Affiliation(s)
| | | | | | - Fabio Franciolini
- Address correspondence to these authors at the Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Pascoli, 8-06123, Perugia; Tel: 39.075.585.5751; E-mails: and
| | - Luigi Catacuzzeno
- Address correspondence to these authors at the Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Pascoli, 8-06123, Perugia; Tel: 39.075.585.5751; E-mails: and
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Pchelintseva E, Djamgoz MBA. Mesenchymal stem cell differentiation: Control by calcium-activated potassium channels. J Cell Physiol 2017; 233:3755-3768. [PMID: 28776687 DOI: 10.1002/jcp.26120] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 08/01/2017] [Indexed: 12/12/2022]
Abstract
Mesenchymal stem cells (MSCs) are widely used in modern medicine for which understanding the mechanisms controlling their differentiation is fundamental. Ion channels offer novel insights to this process because of their role in modulating membrane potential and intracellular milieu. Here, we evaluate the contribution of calcium-activated potassium (KCa ) channels to the three main components of MSC differentiation: initiation, proliferation, and migration. First, we demonstrate the importance of the membrane potential (Vm ) and the apparent association of hyperpolarization with differentiation. Of KCa subtypes, most evidence points to activity of big-conductance channels in inducing initiation. On the other hand, intermediate-conductance currents have been shown to promote progression through the cell cycle. While there is no information on the role of KCa channels in migration of MSCs, work from other stem cells and cancer cells suggest that intermediate-conductance and to a lesser extent big-conductance channels drive migration. In all cases, these effects depend on species, tissue origin and lineage. Finally, we present a conceptual model that demonstrates how KCa activity could influence differentiation by regulating Vm and intracellular Ca2+ oscillations. We conclude that KCa channels have significant involvement in MSC differentiation and could potentially enable novel tissue engineering approaches and therapies.
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Affiliation(s)
- Ekaterina Pchelintseva
- Department of Life Sciences, Imperial College London, South Kensington Campus, Neuroscience Solution to Cancer Research Group, London, UK.,Department of Bioengineering, Imperial College London, South Kensington Campus, London, UK
| | - Mustafa B A Djamgoz
- Department of Life Sciences, Imperial College London, South Kensington Campus, Neuroscience Solution to Cancer Research Group, London, UK
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Tanaka S, Ono Y, Sakamoto K. DCEBIO facilitates myogenic differentiation via intermediate conductance Ca 2+ activated K + channel activation in C2C12 myoblasts. J Pharmacol Sci 2017; 133:276-279. [PMID: 28302447 DOI: 10.1016/j.jphs.2017.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/07/2017] [Accepted: 02/09/2017] [Indexed: 01/24/2023] Open
Abstract
Membrane hyperpolarization is suggested to be a trigger for skeletal muscle differentiation. We investigated whether DCEBIO, an opener of the small/intermediate conductance Ca2+ activated K+ (SKCa/IKCa) channels, increase myogenic differentiation in C2C12 skeletal myoblasts. DCEBIO significantly increased myotube formation, protein expression level of myosin heavy chain II, and mRNA expression level of myogenin in C2C12 myoblasts cultured in differentiation medium. DCEBIO induced myotube formation and hyperpolarization were reduced by the IKCa channel blocker TRAM-34, but not by the SKCa channel blocker apamin. These findings show that DCEBIO increases myogenic differentiation by activating IKCa channels.
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Affiliation(s)
- Shoko Tanaka
- Department of Pharmacology, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima, 960-1295, Japan
| | - Yuko Ono
- Department of Pharmacology, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima, 960-1295, Japan; Emergency and Critical Care Medical Center, Fukushima Medical University Hospital, 1 Hikarigaoka, Fukushima, Fukushima, 960-1295, Japan
| | - Kazuho Sakamoto
- Department of Pharmacology, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima, 960-1295, Japan.
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Zhang Y, Feng Y, Chen L, Zhu J. Effects of Intermediate-Conductance Ca(2+)-Activated K(+) Channels on Human Endometrial Carcinoma Cells. Cell Biochem Biophys 2017; 72:515-25. [PMID: 25608633 DOI: 10.1007/s12013-014-0497-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The objective of this study was to investigate the effect of intermediate-conductance Ca(2+)-activated K(+) (KCa3.1) channels on the cell proliferation, cell cycle, apoptosis, migration, and invasion in endometrial cancer (EC) cells. Human EC cell lines HEC-1-A and Ishikawa were cultured in vitro and transfected with recombinant plasmid containing KCa3.1-targeting shRNA. RT-qPCR and Western blot were used to examine the mRNA and protein expression levels of KCa3.1 channels in transfected cells. In addition, the specific inhibitor of KCa3.1, TRAM-34, was used to examine the effect of KCa3.1 blockage on migration capacity and invasiveness of EC cells using transwell assay. Proliferation and apoptotic rates of EC cells transfected with KCa3.1 shRNA or treated with TRAM-34 were analyzed using MTT, BrdU incorporation assay, and flow cytometry. Expression of cell cycle proteins and metalloproteinase-2 (MMP-2) was evaluated by RT-qPCR and Western blotting. TRAM-34 treatment and KCa3.1 silencing using shRNA dramatically suppressed both the mRNA and protein expression of KCa3.1 channels (P < 0.01) compared with control groups. Blockage of KCa3.1 by TRAM-34 treatment and KCa3.1 shRNA transfection exerted inhibitory effect on cell growth of both EC cell lines, as demonstrated by increased cell population at G0-G1 phase and decreased cell population at S phase. However, both the treatments did not result in significant changes in the apoptotic rate (P > 0.05) compared to controls. Protein expressions of cyclin D1, cyclin E, and survivin were significantly decreased in the experimental groups comparing to control. We showed that TRAM-34 treatment led to significantly inhibited migration, invasion, and MMP-2 expression in HEC-1-A and Ishikawa cells, compared with the control group (P < 0.01). Blockage of KCa3.1 channel activity or expression inhibits cell proliferation and cell cycle progression without inducing apoptosis in EC cells. Moreover, TRAM-34 could reduce the ability of EC cells to migrate and invade, which might be related to reduced expression of MMP-2.
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Affiliation(s)
- Yingli Zhang
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
| | - Youji Feng
- Shanghai Jiao Tong University Affiliated First People's Hospital, Shanghai, 200080, China
| | - Lu Chen
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China.
| | - Jianqing Zhu
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
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Díaz P, Wood AM, Sibley CP, Greenwood SL. Intermediate conductance Ca2+-activated K+ channels modulate human placental trophoblast syncytialization. PLoS One 2014; 9:e90961. [PMID: 24595308 PMCID: PMC3940956 DOI: 10.1371/journal.pone.0090961] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 02/05/2014] [Indexed: 12/31/2022] Open
Abstract
Regulation of human placental syncytiotrophoblast renewal by cytotrophoblast migration, aggregation/fusion and differentiation is essential for successful pregnancy. In several tissues, these events are regulated by intermediate conductance Ca2+-activated K+ channels (IKCa), in part through their ability to regulate cell volume. We used cytotrophoblasts in primary culture to test the hypotheses that IKCa participate in the formation of multinucleated syncytiotrophoblast and in syncytiotrophoblast volume homeostasis. Cytotrophoblasts were isolated from normal term placentas and cultured for 66 h. This preparation recreates syncytiotrophoblast formation in vivo, as mononucleate cells (15 h) fuse into multinucleate syncytia (66 h) concomitant with elevated secretion of human chorionic gonadotropin (hCG). Cells were treated with the IKCa inhibitor TRAM-34 (10 µM) or activator DCEBIO (100 µM). Culture medium was collected to measure hCG secretion and cells fixed for immunofluorescence with anti-IKCa and anti-desmoplakin antibodies to assess IKCa expression and multinucleation respectively. K+ channel activity was assessed by measuring 86Rb efflux at 66 h. IKCa immunostaining was evident in nucleus, cytoplasm and surface of mono- and multinucleate cells. DCEBIO increased 86Rb efflux 8.3-fold above control and this was inhibited by TRAM-34 (85%; p<0.0001). Cytotrophoblast multinucleation increased 12-fold (p<0.05) and hCG secretion 20-fold (p<0.05), between 15 and 66 h. Compared to controls, DCEBIO reduced multinucleation by 42% (p<0.05) and hCG secretion by 80% (p<0.05). TRAM-34 alone did not affect cytotrophoblast multinucleation or hCG secretion. Hyposmotic solution increased 86Rb efflux 3.8-fold (p<0.0001). This effect was dependent on extracellular Ca2+, inhibited by TRAM-34 and 100 nM charybdotoxin (85% (p<0.0001) and 43% respectively) but unaffected by 100 nM apamin. In conclusion, IKCa are expressed in cytotrophoblasts and their activation inhibits the formation of multinucleated cells in vitro. IKCa are stimulated by syncytiotrophoblast swelling implicating a role in syncytiotrophoblast volume homeostasis. Inappropriate activation of IKCa in pathophysiological conditions could compromise syncytiotrophoblast turnover and volume homeostasis in pregnancy disease.
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Affiliation(s)
- Paula Díaz
- Maternal and Fetal Health Research Centre, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
- St. Mary’s Hospital, Central Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
- * E-mail:
| | - Amber M. Wood
- Maternal and Fetal Health Research Centre, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
- St. Mary’s Hospital, Central Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Colin P. Sibley
- Maternal and Fetal Health Research Centre, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
- St. Mary’s Hospital, Central Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Susan L. Greenwood
- Maternal and Fetal Health Research Centre, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
- St. Mary’s Hospital, Central Manchester University Hospitals National Health Service (NHS) Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom
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Up-regulation of KCa3.1 promotes human airway smooth muscle cell phenotypic modulation. Pharmacol Res 2013; 77:30-8. [PMID: 24055799 DOI: 10.1016/j.phrs.2013.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/26/2013] [Accepted: 09/08/2013] [Indexed: 02/06/2023]
Abstract
Airway smooth muscle (ASM) cell phenotype modulation, characterized by reversible switching between contractile and proliferative phenotypes, is considered to contribute to proliferative diseases such as allergic asthma and chronic obstructive pulmonary disease (COPD). KCa3.1 has been suggested to be involved in regulating ASM cell activation, proliferation, and migration. However, little is known regarding the exact role of KCa3.1 in ASM cell phenotypic modulation. To elucidate the role of KCa3.1 in regulating ASM cell phenotypic modulation, we investigated the effects of KCa3.1 channels on ASM contractile marker protein expression, proliferation and migration of primary human bronchial smooth muscle (BSM) cells. We found that PDGF increased KCa3.1 channel expression in BSM cells with a concomitant marked decrease in the expression of contractile phenotypic marker proteins including smooth muscle myosin heavy chain (SMMHC), smooth muscle α-actin (α-SMA), myocardin and KCa1.1. These changes were significantly attenuated by the KCa3.1 blocker, TRAM-34, or gene silencing of KCa3.1. Pharmacological blockade or gene silencing of KCa3.1 also suppressed PDGF-induced human BSM cell migration and proliferation accompanied by a decrease in intracellular free Ca(2+) levels as a consequence of membrane depolarization, resulting in a reduction in cyclin D1 level and cell cycle arrest at G0-G1 phase. Additionally, PDGF-induced up-regulation of KCa3.1 and down-regulation of BSM contractile marker proteins were regulated by the ERK inhibitor U0126 and the AKT inhibitor LY294002. These findings highlight a novel role for the KCa3.1 channel in human BSM cell phenotypic modulation and provide a potential target for therapeutic intervention for proliferative airway diseases.
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Wang T, Yang YQ, Karasawa T, Wang Q, Phillips A, Guan BC, Ma KT, Jiang M, Xie DH, Steyger PS, Jiang ZG. Bumetanide hyperpolarizes madin-darby canine kidney cells and enhances cellular gentamicin uptake by elevating cytosolic Ca(2+) thus facilitating intermediate conductance Ca(2+)--activated potassium channels. Cell Biochem Biophys 2013; 65:381-98. [PMID: 23109177 DOI: 10.1007/s12013-012-9442-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Loop diuretics such as bumetanide and furosemide enhance aminoglycoside ototoxicity when co-administered to patients and animal models. The underlying mechanism(s) is poorly understood. We investigated the effect of these diuretics on cellular uptake of aminoglycosides, using Texas Red-tagged gentamicin (GTTR), and intracellular/whole-cell recordings of Madin-Darby canine kidney (MDCK) cells. We found that bumetanide and furosemide dose-dependently enhanced cytoplasmic GTTR fluorescence by ~60 %. This enhancement was suppressed by La(3+), a non-selective cation channel (NSCC) blocker, and by K(+) channel blockers Ba(2+) and clotrimazole, but not by tetraethylammonium (TEA), 4-aminopyridine (4-AP) or glipizide, nor by Cl(-) channel blockers diphenylamine-2-carboxylic acid (DPC), niflumic acid (NFA), and CFTRinh-172. Bumetanide and furosemide hyperpolarized MDCK cells by ~14 mV, increased whole-cell I/V slope conductance; the bumetanide-induced net current I/V showed a reversal potential (V r) ~-80 mV. Bumetanide-induced hyperpolarization and I/V change was suppressed by Ba(2+) or clotrimazole, and absent in elevated [Ca(2+)]i, but was not affected by apamin, 4-AP, TEA, glipizide, DPC, NFA, or CFTRinh-172. Bumetanide and furosemide stimulated a surge of Fluo-4-indicated cytosolic Ca(2+). Ba(2+) and clotrimazole alone depolarized cells by ~18 mV and reduced I/V slope with a net current V r near -85 mV, and reduced GTTR uptake by ~20 %. La(3+) alone hyperpolarized the cells by ~-14 mV, reduced the I/V slope with a net current V r near -10 mV, and inhibited GTTR uptake by ~50 %. In the presence of La(3+), bumetanide-caused negligible change in potential or I/V. We conclude that NSCCs constitute a major cell entry pathway for cationic aminoglycosides; bumetanide enhances aminoglycoside uptake by hyperpolarizing cells that increases the cation influx driving force; and bumetanide-induced hyperpolarization is caused by elevating intracellular Ca(2+) and thus facilitating activation of the intermediate conductance Ca(2+)-activated K(+) channels.
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Affiliation(s)
- Tian Wang
- Oregon Hearing Research Center, NRC04, Department of Otolaryngology, Oregon Health & Science University, Portland, OR 97239, USA
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Wang LP, Wang Y, Zhao LM, Li GR, Deng XL. Angiotensin II upregulates K(Ca)3.1 channels and stimulates cell proliferation in rat cardiac fibroblasts. Biochem Pharmacol 2013; 85:1486-94. [PMID: 23500546 DOI: 10.1016/j.bcp.2013.02.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/20/2013] [Accepted: 02/27/2013] [Indexed: 12/01/2022]
Abstract
The proliferation of cardiac fibroblasts is implicated in the pathogenesis of myocardial remodeling and fibrosis. Intermediate-conductance calcium-activated K⁺ channels (K(Ca)3.1 channels) have important roles in cell proliferation. However, it is unknown whether angiotensin II (Ang II), a potent profibrotic molecule, would regulate K(Ca)3.1 channels in cardiac fibroblasts and participate in cell proliferation. In the present study, we investigated whether K(Ca)3.1 channels were regulated by Ang II, and how the channel activity mediated cell proliferation in cultured adult rat cardiac fibroblasts using electrophysiology and biochemical approaches. It was found that mRNA, protein, and current density of K(Ca)3.1 channels were greatly enhanced in cultured cardiac fibroblasts treated with 1 μM Ang II, and the effects were countered by the angiotensin type 1 receptor (AT₁R) blocker losartan, the p38-MAPK inhibitor SB203580, the ERK1/2 inhibitor PD98059, and the PI3K/Akt inhibitor LY294002. Ang II stimulated cell proliferation and the effect was antagonized by the K(Ca)3.1 blocker TRAM-34 and siRNA targeting K(Ca)3.1. In addition, Ang II-induced increase of K(Ca)3.1 expression was attenuated by transfection of activator protein-1 (AP-1) decoy oligodeoxynucleotides. These results demonstrate for the first time that Ang II stimulates cell proliferation mediated by upregulating K(Ca)3.1 channels via interacting with the AT₁R and activating AP-1 complex through ERK1/2, p38-MAPK and PI3K/Akt signaling pathways in cultured adult rat cardiac fibroblasts.
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Affiliation(s)
- Li-Ping Wang
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061 Shaanxi, China
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Iannotti FA, Barrese V, Formisano L, Miceli F, Taglialatela M. Specification of skeletal muscle differentiation by repressor element-1 silencing transcription factor (REST)-regulated Kv7.4 potassium channels. Mol Biol Cell 2012; 24:274-84. [PMID: 23242999 PMCID: PMC3564528 DOI: 10.1091/mbc.e11-12-1044] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Kv7.4-potassium channel expression plays a permissive role in skeletal muscle differentiation. The transcriptional repressor REST controls the changes in Kv7.4 levels during myogenesis by binding to regulatory regions in the Kv7.4 gene. This mechanism may be a target for intervention against abnormal repair and differentiation of skeletal muscle. Changes in the expression of potassium (K+) channels is a pivotal event during skeletal muscle differentiation. In mouse C2C12 cells, similarly to human skeletal muscle cells, myotube formation increased the expression of Kv7.1, Kv7.3, and Kv7.4, the last showing the highest degree of regulation. In C2C12 cells, Kv7.4 silencing by RNA interference reduced the expression levels of differentiation markers (myogenin, myosin heavy chain, troponinT-1, and Pax3) and impaired myotube formation and multinucleation. In Kv7.4-silenced cells, the differentiation-promoting effect of the Kv7 activator N-(2-amino-4-(4-fluorobenzylamino)-phenyl)-carbamic acid ethyl ester (retigabine) was abrogated. Expression levels for the repressor element-1 silencing transcription factor (REST) declined during myotube formation. Transcript levels for Kv7.4, as well as for myogenin, troponinT-1, and Pax3, were reduced by REST overexpression and enhanced upon REST suppression by RNA interference. Four regions containing potential REST-binding sites in the 5′ untranslated region and in the first intron of the Kv7.4 gene were identified by bioinformatic analysis. Chromatin immunoprecipitation assays showed that REST binds to these regions, exhibiting a higher efficiency in myoblasts than in myotubes. These data suggest that Kv7.4 plays a permissive role in skeletal muscle differentiation and highlight REST as a crucial transcriptional regulator for this K+ channel subunit.
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Affiliation(s)
- Fabio Arturo Iannotti
- Division of Pharmacology, Department of Neuroscience, University of Naples Federico II, 80131 Naples, Italy
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Blaauw B, Del Piccolo P, Rodriguez L, Hernandez Gonzalez VH, Agatea L, Solagna F, Mammano F, Pozzan T, Schiaffino S. No evidence for inositol 1,4,5-trisphosphate-dependent Ca2+ release in isolated fibers of adult mouse skeletal muscle. ACTA ACUST UNITED AC 2012; 140:235-41. [PMID: 22802359 PMCID: PMC3409103 DOI: 10.1085/jgp.201110747] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The presence and role of functional inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) in adult skeletal muscle are controversial. The current consensus is that, in adult striated muscle, the relative amount of IP3Rs is too low and the kinetics of Ca2+ release from IP3R is too slow compared with ryanodine receptors to contribute to the Ca2+ transient during excitation–contraction coupling. However, it has been suggested that IP3-dependent Ca2+ release may be involved in signaling cascades leading to regulation of muscle gene expression. We have reinvestigated IP3-dependent Ca2+ release in isolated flexor digitorum brevis (FDB) muscle fibers from adult mice. Although Ca2+ transients were readily induced in cultured C2C12 muscle cells by (a) UTP stimulation, (b) direct injection of IP3, or (c) photolysis of membrane-permeant caged IP3, no statistically significant change in calcium signal was detected in adult FDB fibers. We conclude that the IP3–IP3R system does not appear to affect global calcium levels in adult mouse skeletal muscle.
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Affiliation(s)
- Bert Blaauw
- Venetian Institute of Molecular Medicine, 35129 Padova, Italy
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21
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Silva DF, Araújo IGA, Albuquerque JGF, Porto DL, Dias KLG, Cavalcante KVM, Veras RC, Nunes XP, Barbosa-Filho JM, Araújo DAM, Cruz JS, Correia NA, De Medeiros IA. Rotundifolone-induced relaxation is mediated by BK(Ca) channel activation and Ca(v) channel inactivation. Basic Clin Pharmacol Toxicol 2011; 109:465-75. [PMID: 21726408 DOI: 10.1111/j.1742-7843.2011.00749.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Rotundifolone is the major constituent of the essential oil of Mentha x villosa Hudson. In preliminary studies, rotundifolone induced significant hypotensive, bradycardic and vasorelaxant effects in rats. Thus, to gain more insight into the pharmacology of rotundifolone, the aim of this study was to characterize the molecular mechanism of action involved in relaxation produced by rotundifolone. The relaxant effect was investigated in rat superior mesenteric arteries by using isometric tension measurements and whole-cell patch-clamp techniques. Rotundifolone relaxed phenylephrine-induced contractions in a concentration-dependent manner. Pre-treatment with KCl (20 mM), charybdotoxin (10(-7) M) or tetraethylammonium (TEA 10(-3) or 3 × 10(-3) M) significantly attenuated the relaxation effect induced by rotundifolone. Additionally, whole-cell patch-clamp recordings were made in mesenteric smooth muscle cells and showed that rotundifolone significantly increased K(+) currents, and this effect was abolished by TEA (10(-3) M), suggesting the participation of BK(Ca) channels. Furthermore, rotundifolone inhibited the vasoconstriction induced by CaCl(2) in depolarizing nominally Ca(2+) -free medium and antagonized the contractions elicited by an L-type Ca(2+) channel agonist, S(-)-Bay K 8644 (2 × 10(-7) M), indicating that the vasodilatation involved inhibition of Ca(2+) influx through L-type voltage-dependent calcium channels (Ca(v) type-L). Additionally, rotundifolone inhibited L-type Ca(2+) currents (I(Ca) L), affecting the voltage-dependent activation of I(Ca) L and steady-state inactivation. Our findings suggest that rotundifolone induces vasodilatation through two distinct but complementary mechanisms that clearly depend on the concentration range used. Rotundifolone elicits an increase in the current density of BK(Ca) channels and causes a shift in the steady-state inactivation relationship for Ca(v) type-L towards more hyperpolarized membrane potentials.
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Affiliation(s)
- Darízy F Silva
- Laboratório de Tecnologia Farmacêutica (LTF), Universidade Federal da Paraíba - UFPB, João Pessoa, PB - Brazil.
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Cell membrane stretch activates intermediate-conductance Ca2+-activated K+ channels in arterial smooth muscle cells. Heart Vessels 2010; 26:91-100. [PMID: 21063882 DOI: 10.1007/s00380-010-0025-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 01/21/2010] [Indexed: 10/18/2022]
Abstract
The aim of this study is to determine the signal transduction of membrane stretch on intermediate-conductance Ca(2+)-activated K(+) (IKca) channels in rat aorta smooth muscle cells using the patch-clamp technique. To stretch the cell membrane, both suction to the rear end of patch pipette and hypotonic shock were used. In cell-attached and inside-out patch configurations, the open probability of IKca channels increased when 20- to 45-mmHg suction was applied. Hyposmotic swelling efficiently increased IKca channel current. When the Ca(2+)-free solution was superfused, the activation of IKca current by the hyposmotic swelling was reduced. Furthermore, gadolinium (Gd(3+)) attenuated the activation of IKca channels induced by hyposmotic swelling, whereas nicardipine did not. In the experiments with Ca(2+)-free bath solution, pretreatment with GF109203X, a protein kinase C (PKC) inhibitor, completely abolished the stretch-induced activation of IKca currents. The stretch-induced activation of IKca channels was strongly inhibited by cytochalasin D, indicating a role for the F-actin in modulation of IKca channels by changes in cell stretching. These data suggest that cell membrane stretch activates IKca channels. In addition, the activation is associated with extracellular Ca(2+) influx through stretch-activated nonselective cation channels, and is also modulated by the F-actin cytoskeleton and the activation of PKC.
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Iannotti FA, Panza E, Barrese V, Viggiano D, Soldovieri MV, Taglialatela M. Expression, localization, and pharmacological role of Kv7 potassium channels in skeletal muscle proliferation, differentiation, and survival after myotoxic insults. J Pharmacol Exp Ther 2009; 332:811-20. [PMID: 20040580 DOI: 10.1124/jpet.109.162800] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Changes in the expression of potassium channels regulate skeletal muscle development. The purpose of this study was to investigate the expression profile and pharmacological role of K(v)7 voltage-gated potassium channels in skeletal muscle differentiation, proliferation, and survival after myotoxic insults. Transcripts for all K(v)7 genes (K(v)7.1-K(v)7.5) were detected by polymerase chain reaction (PCR) and/or real-time PCR in murine C(2)C(12) myoblasts; K(v)7.1, K(v)7.3, and K(v)7.4 transcripts were up-regulated after myotube formation. Western blot experiments confirmed K(v)7.2, K(v)7.3, and K(v)7.4 subunit expression, and the up-regulation of K(v)7.3 and K(v)7.4 subunits during in vitro differentiation. In adult skeletal muscles from mice and humans, K(v)7.2 and K(v)7.3 immunoreactivity was mainly localized at the level of intracellular striations positioned between ankyrinG-positive triads, whereas that of K(v)7.4 subunits was largely restricted to the sarcolemmal membrane. In C(2)C(12) cells, retigabine (10 microM), a specific activator of neuronally expressed K(v)7.2 to K(v)7.5 subunits, reduced proliferation, accelerated myogenin expression, and inhibited the myotoxic effect of mevastatin (IC(50) approximately 7 microM); all these effects of retigabine were prevented by the K(v)7 channel blocker 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone (XE-991) (10 muM). These data collectively highlight neural K(v)7 channels as significant pharmacological targets to regulate skeletal muscle proliferation, differentiation, and myotoxic effects of drugs.
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Affiliation(s)
- Fabio Arturo Iannotti
- Division of Pharmacology, Department of Neuroscience, University of Naples Federico II, Naples, Italy
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Sundelacruz S, Levin M, Kaplan DL. Role of membrane potential in the regulation of cell proliferation and differentiation. Stem Cell Rev Rep 2009; 5:231-46. [PMID: 19562527 PMCID: PMC10467564 DOI: 10.1007/s12015-009-9080-2] [Citation(s) in RCA: 325] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 06/07/2009] [Indexed: 12/11/2022]
Abstract
Biophysical signaling, an integral regulator of long-term cell behavior in both excitable and non-excitable cell types, offers enormous potential for modulation of important cell functions. Of particular interest to current regenerative medicine efforts, we review several examples that support the functional role of transmembrane potential (V(mem)) in the regulation of proliferation and differentiation. Interestingly, distinct V(mem) controls are found in many cancer cell and precursor cell systems, which are known for their proliferative and differentiation capacities, respectively. Collectively, the data demonstrate that bioelectric properties can serve as markers for cell characterization and can control cell mitotic activity, cell cycle progression, and differentiation. The ability to control cell functions by modulating bioelectric properties such as V(mem) would be an invaluable tool for directing stem cell behavior toward therapeutic goals. Biophysical properties of stem cells have only recently begun to be studied and are thus in need of further characterization. Understanding the molecular and mechanistic basis of biophysical regulation will point the way toward novel ways to rationally direct cell functions, allowing us to capitalize upon the potential of biophysical signaling for regenerative medicine and tissue engineering.
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Affiliation(s)
- Sarah Sundelacruz
- Department of Biomedical Engineering, Tufts University, 4 Colby St., Medford, MA 02155, USA
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Villalonga N, Martínez-Mármol R, Roura-Ferrer M, David M, Valenzuela C, Soler C, Felipe A. Cell cycle-dependent expression of Kv1.5 is involved in myoblast proliferation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:728-36. [DOI: 10.1016/j.bbamcr.2008.01.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 11/26/2007] [Accepted: 01/02/2008] [Indexed: 12/01/2022]
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Alvisi M, De Arcangelis V, Ciccone L, Palombi V, Alessandrini M, Nemoz G, Molinaro M, Adamo S, Naro F. V1a vasopressin receptor expression is modulated during myogenic differentiation. Differentiation 2007; 76:371-80. [PMID: 18021262 DOI: 10.1111/j.1432-0436.2007.00231.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Neurohypophyseal peptides potently stimulate myogenic differentiation by acting through different receptors of the same family. Here, we show that L6C5 myogenic cells express, at a high density, a single class of V1a Arg8-vasopressin (AVP) receptor. The expression of the vasopressin receptor of type 1a (V1aR) is significantly higher in proliferating myoblasts than in differentiated myotubes. The differentiation-related decrease of V1aR expression was evident both at the mRNA and at the protein level as shown by the reduction of [(3)H]-AVP binding. However, in L6C5 cells transfected with a synthetic construct containing the luciferase gene driven by the 2 kb upstream region of V1aR, we observed a stimulation of the activity of the promoter when the cells were cultured in differentiative medium. The down-regulation of the V1aR correlated with a decreased half-life of its mRNA (half-life 5.86+/-0.74 hr in 10% fetal bovine serum [FBS] versus 3.53+/-0.72 hr in 1% FBS). Cyclosporine A and dexamethasone, but not 5'-azacytidine, treatments of cells in differentiation medium restored the V1aR level to that measured in proliferating L6C5 cells, thus confirming the role of post-transcriptional mechanisms in the modulation of V1aR expression. Taken together, these data show that mRNA stability plays a role in modulating protein expression during the myogenic differentiation process.
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Affiliation(s)
- Monica Alvisi
- Dipartimento di Istologia ed Embriologia Medica Università di Roma La Sapienza Via Scarpa 16, 00161 Roma, Italy
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Huang CC, Hall AC, Lim PH. Characterisation of three pathways for osmolyte efflux in human erythroleukemia cells. Life Sci 2007; 81:732-9. [PMID: 17698149 DOI: 10.1016/j.lfs.2007.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 06/22/2007] [Accepted: 07/04/2007] [Indexed: 01/01/2023]
Abstract
Cell volume decrease is a key step during differentiation of erythroid cells. This could arise from membrane transporter activation leading to a loss of cell osmolytes; however, the pathways involved are poorly understood. We have characterised Cl(-)-independent K(+) and (3)H-taurine efflux from the erythroleukemia cell line, K562. K(+) efflux (measured using (86)Rb(+)) from pre-loaded cells subjected to hypo-osmotic challenge demonstrated two phases, a rapid increase in K(+) efflux followed by a smaller slower increase. Swelling-activated taurine efflux only demonstrated a single phase. Both phases of K(+) efflux were significantly (P<0.05) blocked by anion channel inhibitor 5-nitro-2-(3-phenypropylamino)-benzoic acid (NPPB). However the antiestrogen, tamoxifen, only inhibited the slow late phase. The initial rapid phase had a higher IC(50) for NPPB inhibition than the slow phase, and was insensitive to protein kinases inhibitors KN-62, wortmannin and PD98059. For the slow K(+) efflux phase, the IC(50) for NPPB inhibition and the inhibition by KN-62, wortmannin, genistein or PD98059, were very similar to those measured for the hypo-osmotically-activated taurine efflux. With NPPB (100 microM) present, the slow K(+) efflux phase was further significantly decreased by the Ca(2+) chelator BAPTA-AM or by the Ca(2+)-activated K(+) channel blockers clotrimazole and charybdotoxin but not by apamin. Thus, at least 3 Cl(-)-independent pathways are involved: (a) a tamoxifen-sensitive and taurine-permeable anion channel; (b) a tamoxifen-insensitive and taurine-impermeable K(+) efflux pathway; and (c) a subtype of Ca(2+)-activated K(+) channel. Any or all of these could be involved in the cell volume decrease associated with differentiation in K562 cells.
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Affiliation(s)
- Chiun-Chien Huang
- Department of Physiology, Chung Shan Medical University, Taichung 40203, Taiwan, ROC.
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Dong DL, Luan Y, Feng TM, Fan CL, Yue P, Sun ZJ, Gu RM, Yang BF. Chlorzoxazone inhibits contraction of rat thoracic aorta. Eur J Pharmacol 2006; 545:161-6. [PMID: 16859676 DOI: 10.1016/j.ejphar.2006.06.063] [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] [Received: 08/25/2005] [Revised: 05/29/2006] [Accepted: 06/20/2006] [Indexed: 11/18/2022]
Abstract
Chlorzoxazone has been reported to activate the intermediate-conductance, Ca(2+)-activated K(+) channels in aortic endothelial cells and to relax the artery. The aim of the present study was to characterize the chlorzoxazone-induced relaxation of rat thoracic artery. Chlorzoxazone did not affect the tension of the thoracic artery rings at rest, but relaxed the precontraction induced by 1 muM noradrenaline in an endothelium independent manner. Preincubation with chlorzoxazone also antagonized the contraction induced by 1 microM noradrenaline or 25 mM KCl. The chlorzoxazone-induced relaxation of the thoracic artery pre-contracted by noradrenaline was suppressed by 5 mM tetraethylammonium, 75 mM ethanol and 2 microM paxilline, but not by 2 microM clotrimazole. Chlorzoxazone relaxed the 4-aminopyridine-induced contraction. The pattern of chlorzoxazone-induced relaxation was different from that of verapamil, the L-type Ca(2+) channel blocker. The inhibition of the noradrenaline-induced contraction by chlorzoxazone was attenuated when chlorzoxazone treatment was prolonged to 4 h. No difference in the contraction-relaxation was found between the artery rings from normal rats and those from rats that received 100 mg/kg chlorzoxazone for 7 days. We conclude that chlorzoxazone abolishes the contraction of rat thoracic artery induced by noradrenaline and that the effect of chlorzoxazone is endothelium independent and also not mediated by intermediate-conductance, Ca(2+)-activated K(+) channels.
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Affiliation(s)
- De-Li Dong
- Department of Pharmacology, Harbin Medical University, Bio-pharmaceutical Key Laboratory of Heilongjiang Province, Baojian Road 157, Harbin 150086, Heilongjiang Province, PR China.
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Fioretti B, Castigli E, Micheli MR, Bova R, Sciaccaluga M, Harper A, Franciolini F, Catacuzzeno L. Expression and modulation of the intermediate- conductance Ca2+-activated K+ channel in glioblastoma GL-15 cells. Cell Physiol Biochem 2006; 18:47-56. [PMID: 16914889 DOI: 10.1159/000095135] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report here the expression and properties of the intermediate-conductance Ca(2+)-activated K(+) (IK(Ca)) channel in the GL-15 human glioblastoma cell line. Macroscopic IK(Ca) currents on GL-15 cells displayed a mean amplitude of 7.2+/-0.8 pA/pF at 0 mV, at day 1 after plating. The current was inhibited by clotrimazole (CTL, IC(50)=257 nM), TRAM-34 (IC(50)=55 nM), and charybdotoxin (CTX, IC(50)=10.3 nM). RT-PCR analysis demonstrated the expression of mRNA encoding the IK(Ca) channel in GL-15 cells. Unitary currents recorded using the inside-out configuration had a conductance of 25 pS, a K(D) for Ca(2+) of 188 nM at -100 mV, and no voltage dependence. We tested whether the IKCa channel expression in GL-15 cells could be the result of an increased ERK activity. Inhibition of the ERK pathway with the MEK antagonist PD98059 (25 muM, for 5 days) virtually suppressed the IK(Ca) current in GL-15 cells. PD98059 treatment also increased the length of cellular processes and up-regulated the astrocytic differentiative marker GFAP. A significant reduction of the IKCa current amplitude was also observed with time in culture, with mean currents of 7.17+/-0.75 pA/pF at 1-2 days, and 3.11+/-1.35 pA/pF at 5-6 days after plating. This time-dependent downregulation of the IK(Ca) current was not accompanied by changes in the ERK activity, as assessed by immunoblot analysis. Semiquantitative RT-PCR analysis demonstrated a ~35% reduction of the IK(Ca) channel mRNA resulting from ERK inhibition and a approximately 50% reduction with time in culture.
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Affiliation(s)
- Bernard Fioretti
- Dipartimento di Biologia Cellulare e Ambientale, Universita' di Perugia, CEMIN, Centro di Eccellenza "Materiali Innovativi Nanostrutturati", Universita' di Perugia, Italy.
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Pietrangelo T, Fioretti B, Mancinelli R, Catacuzzeno L, Franciolini F, Fanò G, Fulle S. Extracellular guanosine-5'-triphosphate modulates myogenesis via intermediate Ca(2+)-activated K+ currents in C2C12 mouse cells. J Physiol 2006; 572:721-33. [PMID: 16455689 PMCID: PMC1780011 DOI: 10.1113/jphysiol.2005.102194] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this study we investigated the role of extracellular 5'-guanosine-triphosphate (GTP) on early phases of skeletal muscle differentiation using the widely used C2C12 mouse cells as a myogenic model. We show that extracellular GTP binding to specific sites activates a metabotropic cascade that leads to a transient intracellular Ca2+ mobilization, consequent activation of the intermediate Ca(2+)-activated K+ channels (IK(Ca)), and hyperpolarization of the plasma membrane. We further show that in differentiating C2C12 myoblasts GTP induces a proliferative boost, and increases the number of cells positive for the myosin heavy chain (MyHC) proteins. These effects were shown to be mediated by the IK(Ca) channel-dependent hyperpolarization, as evidenced by their disappearance when myoblasts were incubated with the IK(Ca) channel inhibitor charybdotoxin. These data give new insights into nucleotide purinergic signalling pathways, and address the role of the GTP-dependent IK(Ca) channel activation and hyperpolarization in myogenesis.
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Affiliation(s)
- Tiziana Pietrangelo
- Dipartimento Scienze del Farmaco, Istituto Interuniversitario di Miologia, Ce.S.I. Centro di Scienze dell'Invecchiamento 'University G. d'Annunzio' Foundation, via dei Vestini, I-66013 Chieti, Italy.
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Abstract
We investigated the effects of 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one(DCEBIO) on the Cl- secretory response of the mouse jejunum using the Ussing short-circuit current (Isc) technique. DCEBIO stimulated a concentration-dependent, sustained increase in Isc (EC50 41 +/- 1 microM). Pretreating tissues with 0.25 microM forskolin reduced the concentration-dependent increase in Isc by DCEBIO and increased the EC50 (53 +/- 5 microM). Bumetanide blocked (82 +/- 5%) the DCEBIO-stimulated Isc consistent with Cl- secretion. DCEBIO was a more potent stimulator of Cl- secretion than its parent molecule, 1-ethyl-2-benzimidazolinone. Glibenclamide or NPPB reduced the DCEBIO-stimulated Isc by >80% indicating the participation of CFTR in the DCEBIO-stimulated Isc response. Clotrimazole reduced DCEBIO-stimulated Isc by 67 +/- 15%, suggesting the participation of the intermediate conductance Ca2+-activated K+ channel (IKCa) in the DCEBIO-activated Isc response. In the presence of maximum forskolin (10 microM), the DCEBIO response was reduced and biphasic, reaching a peak response of the change in Isc of 43 +/- 5 microA/cm2 and then falling to a steady-state response of 17 +/- 10 microA/cm2 compared with DCEBIO control tissues (61 +/- 6 microA/cm2). The forskolin-stimulated Isc in the presence of DCEBIO was reduced compared with forskolin control tissues. Similar results were observed with DCEBIO and 8-BrcAMP where adenylate cyclase was bypassed. H89, a PKA inhibitor, reduced the DCEBIO-activated Isc, providing evidence that DCEBIO increased Cl- secretion via a cAMP/PKA-dependent manner. These data suggest that DCEBIO stimulates Cl- secretion of the mouse jejunum and that DCEBIO targets components of the Cl- secretory mechanism.
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Affiliation(s)
- Kirk L Hamilton
- Dept. of Physiology, School of Medical Sciences, Univ. of Otago, PO Box 913, Dunedin, New Zealand.
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