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Canonical Transient Receptor Potential (TRPC) Channels in Nociception and Pathological Pain. Neural Plast 2020; 2020:3764193. [PMID: 32273889 PMCID: PMC7115173 DOI: 10.1155/2020/3764193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 02/26/2020] [Accepted: 03/07/2020] [Indexed: 12/13/2022] Open
Abstract
Chronic pathological pain is one of the most intractable clinical problems faced by clinicians and can be devastating for patients. Despite much progress we have made in understanding chronic pain in the last decades, its underlying mechanisms remain elusive. It is assumed that abnormal increase of calcium levels in the cells is a key determinant in the transition from acute to chronic pain. Exploring molecular players mediating Ca2+ entry into cells and molecular mechanisms underlying activity-dependent changes in Ca2+ signaling in the somatosensory pain pathway is therefore helpful towards understanding the development of chronic, pathological pain. Canonical transient receptor potential (TRPC) channels form a subfamily of nonselective cation channels, which permit the permeability of Ca2+ and Na+ into the cells. Initiation of Ca2+ entry pathways by these channels triggers the development of many physiological and pathological functions. In this review, we will focus on the functional implication of TRPC channels in nociception with the elucidation of their role in the detection of external stimuli and nociceptive hypersensitivity.
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Noh J, Chung JM. Modulation of Dopaminergic Neuronal Excitability by Zinc through the Regulation of Calcium-related Channels. Exp Neurobiol 2019; 28:578-592. [PMID: 31698550 PMCID: PMC6844832 DOI: 10.5607/en.2019.28.5.578] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 10/28/2019] [Accepted: 10/28/2019] [Indexed: 11/19/2022] Open
Abstract
Depending on the intracellular buffering of calcium by chelation, zinc has the following two apparent effects on neuronal excitability: enhancement or reduction. Zinc increased tonic activity in the depolarized state when neurons were intracellularly dialyzed with EGTA but attenuated the neuronal activity when BAPTA was used as an intracellular calcium buffer. This suggests that neuronal excitability can be modulated by zinc, depending on the internal calcium buffering capacity. In this study, we elucidated the mechanisms of zinc-mediated alterations in neuronal excitability and determined the effect of calcium-related channels on zinc-mediated alterations in excitability. The zinc-induced augmentation of firing activity was mediated via the inhibition of small-conductance calcium-activated potassium (SK) channels with not only the contribution of voltage-gated L-type calcium channels (VGCCs) and ryanodine receptors (RyRs), but also through the activation of VGCCs via melastatin-like transient receptor potential channels. We suggest that zinc modulates the dopaminergic neuronal activity by regulating not only SK channels as calcium sensors, but also VGCCs or RyRs as calcium sources. Our results suggest that the cytosolic calcium-buffering capacity can tightly regulate zinc-induced neuronal firing patterns and that local calcium-signaling domains can determine the physiological and pathological state of synaptic activity in the dopaminergic system.
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Affiliation(s)
- Jihyun Noh
- Department of Science Education, Dankook University, Yongin 16890, Korea
| | - Jun-Mo Chung
- Department of Brain and Cognitive Sciences, Ewha Womans University, Seoul 03760, Korea
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Chow LWC, Cheng KS, Leong F, Cheung CW, Shiao LR, Leung YM, Wong KL. Enhancing tetrandrine cytotoxicity in human lung carcinoma A549 cells by suppressing mitochondrial ATP production. Naunyn Schmiedebergs Arch Pharmacol 2018; 392:427-436. [PMID: 30547225 DOI: 10.1007/s00210-018-01601-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/06/2018] [Indexed: 12/12/2022]
Abstract
ATP depletion induced by inhibiting glycolysis or mitochondrial ATP production has been demonstrated to cause cancer cell death. Whether ATP depletion can enhance the efficacy and potency of anti-cancer effects of herbal compounds is so far unknown. We examined the enhancing effect of ATP depletion on anti-cancer actions of tetrandrine (TET) in human lung carcinoma A549 cells. A 24-h incubation of A549 cells with tetrandrine caused a concentration-dependent cytotoxic effect (LC50 = 66.1 μM). Co-incubation with 20 mM 2-deoxyglucose (2-DG, glycolysis inhibitor) caused only a very slight enhancement of tetrandrine cytotoxicity. By contrast, inhibiting mitochondrial ATP production with oligomycin (10 μM, ATP synthase inhibitor) and FCCP (30 μM, uncoupling agent) (thus, oligo-FCCP) on its own caused only slight cell cytotoxicity but strongly potentiated tetrandrine cytotoxicity (tetrandrine LC50 = 15.6 μM). The stronger enhancing effect of oligo-FCCP than 2-DG on TET toxicity did not result from more severe overall ATP depletion, since both treatments caused a similar ATP level suppression. Neither oligo-FCCP nor 2-DG synergized with tetrandrine in decreasing mitochondrial membrane potential. TET on its own triggered reactive oxygen species (ROS) production, and oligo-FCCP, but not 2-DG, potentiated TET in causing ROS production. Taken together, our results suggest that inhibiting ATP production from mitochondria, but not from glycolysis, appears to be a very effective means in augmenting TET-triggered ROS production and hence toxicity in A549 cells.
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Affiliation(s)
- Louis W C Chow
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau, China
- UNIMED Medical Institute and Organisation for Oncology and Translational Research, Hong Kong, China
- Organisation for Oncology and Translational Research, Hong Kong, China
| | - Ka-Shun Cheng
- Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan
| | - Fai Leong
- Department of Anaesthesiology of Centro Hospitalar conde de Sao Januario, Macao Health Bureau, Macau, SAR, China
| | - Chi-Wai Cheung
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Lian-Ru Shiao
- Department of Physiology, China Medical University, No.91, Hsueh-Shih Road, Taichung, 40402, Taiwan, Republic of China
| | - Yuk-Man Leung
- Department of Physiology, China Medical University, No.91, Hsueh-Shih Road, Taichung, 40402, Taiwan, Republic of China.
| | - Kar-Lok Wong
- Department of Anesthesiology, China Medical University Hospital, Taichung, Taiwan.
- Laboratory and Clinical Research Institute for Pain, Department of Anaesthesiology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
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Abdoul-Azize S, Buquet C, Li H, Picquenot JM, Vannier JP. Integration of Ca 2+ signaling regulates the breast tumor cell response to simvastatin and doxorubicin. Oncogene 2018; 37:4979-4993. [PMID: 29795329 DOI: 10.1038/s41388-018-0329-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 04/30/2018] [Accepted: 05/01/2018] [Indexed: 02/06/2023]
Abstract
Recent studies have suggested that the lipid-lowering agent simvastatin holds great promise as a cancer therapeutic; it inhibits the growth of multiple tumors, including triple-negative breast cancer. Doxorubicin- and simvastatin-induced cytotoxicity has been associated with the modulation of Ca2+ signaling, but the underlying mechanisms remain incompletely understood. Here we identify how Ca2+ signaling regulates the breast tumor cell response to doxorubicin and simvastatin. These two drugs inhibit cell survival while increasing apoptosis in two human breast cancer cell lines and five primary breast tumor specimens through the modulation of Ca2+ signaling. Signal transduction and functional studies revealed that both simvastatin and doxorubicin trigger persistent cytosolic Ca2+ release, thereby stimulating the proapoptotic BIM pathway and mitochondrial Ca2+ overload, which are responsible for metabolic dysfunction and apoptosis induction. Simvastatin and doxorubicin suppress the prosurvival ERK1/2 pathway in a Ca2+-independent and Ca2+-dependent manner, respectively. In addition, reduction of the Ca2+ signal by chelation or pharmacological inhibition significantly prevents drug-mediated anticancer signaling. Unexpectedly, a scratch-wound assay indicated that these two drugs induce rapid cell migration, while inhibiting cell invasion and colony formation in a Ca2+-dependent manner. Further, the in vivo data for MDA-MB-231 xenografts demonstrate that upon chelation of Ca2+, the ability of both drugs to reduce the tumor burden was significantly reduced via caspase-3 deactivation. Our results establish a calcium-based mechanism as crucial for executing the cell death process triggered by simvastatin and doxorubicin, and suggest that combining simvastatin with doxorubicin may be an effective regimen for the treatment of breast cancer.
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Affiliation(s)
- Souleymane Abdoul-Azize
- Unité Inserm U1234/Université de Rouen/IRIB, Faculté de Médecine et Pharmacie, Rouen Cedex, 76183, France.
| | - Catherine Buquet
- Unité Inserm U1234/Université de Rouen/IRIB, Faculté de Médecine et Pharmacie, Rouen Cedex, 76183, France
| | - Hong Li
- Unité Inserm U1234/Université de Rouen/IRIB, Faculté de Médecine et Pharmacie, Rouen Cedex, 76183, France
| | - Jean-Michel Picquenot
- Service Anatomie et Cytologie pathologiques, Centre Henri Becquerel de Lutte Contre le Cancer (CLCC) de Normandie, Rouen Cedex 1, 76038, France
| | - Jean-Pierre Vannier
- Unité Inserm U1234/Université de Rouen/IRIB, Faculté de Médecine et Pharmacie, Rouen Cedex, 76183, France
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Pharmacological targeting of ion channels for cancer therapy: In vivo evidences. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1385-97. [DOI: 10.1016/j.bbamcr.2015.11.032] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 12/29/2022]
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6
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Jing Z, Sui X, Yao J, Xie J, Jiang L, Zhou Y, Pan H, Han W. SKF-96365 activates cytoprotective autophagy to delay apoptosis in colorectal cancer cells through inhibition of the calcium/CaMKIIγ/AKT-mediated pathway. Cancer Lett 2016; 372:226-38. [PMID: 26803057 DOI: 10.1016/j.canlet.2016.01.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/24/2015] [Accepted: 01/06/2016] [Indexed: 12/19/2022]
Abstract
Store-operated Ca(2+) entry (SOCE) inhibitors are emerging as an attractive new generation of anti-cancer drugs. Here, we report that SKF-96365, an SOCE inhibitor, exhibits potent anti-neoplastic activity by inducing cell-cycle arrest and apoptosis in colorectal cancer cells. In the meantime, SKF-96365 also induces cytoprotective autophagy to delay apoptosis by preventing the release of cytochrome c (cyt c) from the mitochondria into the cytoplasm. Mechanistically, SKF-96365 treatment inhibited the calcium/calmodulin-dependent protein kinase IIγ (CaMKIIγ)/AKT signaling cascade in vitro and in vivo. Overexpression of CaMKIIγ or AKT abolished the effects of SKF-96365 on cancer cells, suggesting a critical role of the CaMKIIγ/AKT signaling pathway in SFK-96365-induced biological effects. Moreover, Hydroxychloroquine (HCQ), an FDA-approved drug used to inhibit autophagy, could significantly augment the anti-cancer effect of SFK-96365 in a mouse xenograft model. To our best knowledge, this is the first report to demonstrate that calcium/CaMKIIγ/AKT signaling can regulate apoptosis and autophagy simultaneously in cancer cells, and the combination of the SOCE inhibitor SKF-96365 with autophagy inhibitors represents a promising strategy for treating patients with colorectal cancer.
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Affiliation(s)
- Zhao Jing
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xinbing Sui
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Junlin Yao
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jiansheng Xie
- Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Liming Jiang
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yubin Zhou
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA
| | - Hongming Pan
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Weidong Han
- Department of Medical Oncology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
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7
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Muscarinic receptor-mediated excitation of rat intracardiac ganglion neurons. Neuropharmacology 2015; 95:395-404. [DOI: 10.1016/j.neuropharm.2015.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 03/13/2015] [Accepted: 04/14/2015] [Indexed: 11/23/2022]
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Wilson PC, Fitzgibbon WR, Garrett SM, Jaffa AA, Luttrell LM, Brands MW, El-Shewy HM. Inhibition of Sphingosine Kinase 1 Ameliorates Angiotensin II-Induced Hypertension and Inhibits Transmembrane Calcium Entry via Store-Operated Calcium Channel. Mol Endocrinol 2015; 29:896-908. [PMID: 25871850 DOI: 10.1210/me.2014-1388] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Angiotensin II (AngII) plays a critical role in the regulation of vascular tone and blood pressure mainly via regulation of Ca(2+) mobilization. Several reports have implicated sphingosine kinase 1 (SK1)/sphingosine 1-phosphate (S1P) in the mobilization of intracellular Ca(2+) through a yet-undefined mechanism. Here we demonstrate that AngII-induces biphasic calcium entry in vascular smooth muscle cells, consisting of an immediate peak due to inositol tris-phosphate-dependent release of intracellular calcium, followed by a sustained transmembrane Ca(2+) influx through store-operated calcium channels (SOCs). Inhibition of SK1 attenuates the second phase of transmembrane Ca(2+) influx, suggesting a role for SK1 in AngII-dependent activation of SOC. Intracellular S1P triggers SOC-dependent Ca(2+) influx independent of S1P receptors, whereas external application of S1P stimulated S1P receptor-dependent Ca(2+) influx that is insensitive to inhibitors of SOCs, suggesting that the SK1/S1P axis regulates store-operated calcium entry via intracellular rather than extracellular actions. Genetic deletion of SK1 significantly inhibits both the acute hypertensive response to AngII in anaesthetized SK1 knockout mice and the sustained hypertensive response to continuous infusion of AngII in conscious animals. Collectively these data implicate SK1 as the missing link that connects the angiotensin AT1A receptor to transmembrane Ca(2+) influx and identify SOCs as a potential intracellular target for SK1.
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Affiliation(s)
- Parker C Wilson
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Wayne R Fitzgibbon
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Sara M Garrett
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Ayad A Jaffa
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Louis M Luttrell
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Michael W Brands
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
| | - Hesham M El-Shewy
- Department of Pathology (P.C.W.), Yale-New Haven Hospital, New Haven, Connecticut 06510; Departments of Medicine (W.R.F., S.M.G., A.A.J., L.M.L., H.M.E.) and Biochemistry and Molecular Biology (L.M.L.), Medical University of South Carolina, Charleston, South Carolina 29425; Department of Research Service (L.M.L.), Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401; Department of Physiology (M.W.B.), Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia 30912; and Department of Biochemistry and Molecular Genetics (A.A.J.), Faculty of Medicine, American University of Beirut, Beirut, Lebanon 113-6044
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Tiribuzi R, Tartacca F, Aisa MC, Cerulli GG, Palmerini CA. The impact of nitric oxide on calcium homeostasis in PE/CA-PJ15 cells. Arch Oral Biol 2014; 59:1377-83. [DOI: 10.1016/j.archoralbio.2014.07.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 11/27/2022]
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Borahay MA, Kilic GS, Yallampalli C, Snyder RR, Hankins GDV, Al-Hendy A, Boehning D. Simvastatin potently induces calcium-dependent apoptosis of human leiomyoma cells. J Biol Chem 2014; 289:35075-86. [PMID: 25359773 DOI: 10.1074/jbc.m114.583575] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Statins are drugs commonly used for the treatment of high plasma cholesterol levels. Beyond these well known lipid-lowering properties, they possess broad-reaching effects in vivo, including antitumor effects. Statins inhibit the growth of multiple tumors. However, the mechanisms remain incompletely understood. Here we show that simvastatin inhibits the proliferation of human leiomyoma cells. This was associated with decreased mitogen-activated protein kinase signaling and multiple changes in cell cycle progression. Simvastatin potently stimulated leiomyoma cell apoptosis in a manner mechanistically dependent upon apoptotic calcium release from voltage-gated calcium channels. Therefore, simvastatin possesses antitumor effects that are dependent upon the apoptotic calcium release machinery.
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Affiliation(s)
- Mostafa A Borahay
- From the Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555, the Department of Biochemistry and Molecular Biology, University of Texas Health Sciences Center at Houston, Houston, Texas 77030,
| | - Gokhan S Kilic
- From the Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Chandrasekha Yallampalli
- the Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030, and
| | - Russell R Snyder
- From the Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Gary D V Hankins
- From the Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Ayman Al-Hendy
- the Department of Obstetrics and Gynecology, Georgia Regents University, Augusta, Georgia 30912
| | - Darren Boehning
- the Department of Biochemistry and Molecular Biology, University of Texas Health Sciences Center at Houston, Houston, Texas 77030,
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Peng G, Ran P, Lu W, Zhong N, Wang J. Acute hypoxia activates store-operated Ca(2+) entry and increases intracellular Ca(2+) concentration in rat distal pulmonary venous smooth muscle cells. J Thorac Dis 2013; 5:605-12. [PMID: 24255773 DOI: 10.3978/j.issn.2072-1439.2013.08.68] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/27/2013] [Indexed: 11/14/2022]
Abstract
RATIONALE Exposure to acute hypoxia causes vasoconstriction in both pulmonary arteries (PA) and pulmonary veins (PV). The mechanisms on the arterial side have been studied extensively. However, bare attention has been paid to the venous side. OBJECTIVES To investigate if acute hypoxia caused the increase of intracellular Ca(2+) concentration ([Ca(2+)]i), and Ca(2+) influx through store-operated calcium channels (SOCC) in pulmonary venous smooth muscle cells (PVSMCs). METHODS Fluorescent microscopy and fura-2 were used to measure effects of 4% O2 on [Ca(2+)]i and store-operated Ca(2+) entry (SOCE) in isolated rat distal PVSMCs. MEASUREMENTS AND MAIN RESULTS In PVSMCs perfused with Ca(2+)-free Krebs Ringer bicarbonate solution (KRBS) containing cyclopiazonic acid to deplete Ca(2+) stores in the sarcoplasmic reticulum (SR) and nifedipine to prevent Ca(2+) entry through L-type voltage-depended Ca(2+) channels (VDCC), hypoxia markedly enhanced both the increase in [Ca(2+)]i caused by restoration of extracellular [Ca(2+)] and the rate at which extracellular Mn(2+) quenched fura-2 fluorescence. Moreover, the increased [Ca(2+)]i in PVSMCs perfused with normal salt solution was completely blocked by SOCC antagonists SKF-96365 and NiCl2 at concentrations that SOCE >85% was inhibited but [Ca(2+)]i responses to 60 mM KCl were not altered. On the contrary, L-type VDCC antagonist nifedipine inhibited increase in [Ca(2+)]i to hypoxia by only 50% at concentrations that completely blocked responses to KCl. The increased [Ca(2+)]i caused by hypoxia was completely abolished by perfusion with Ca(2+)-free KRBS. CONCLUSIONS These results suggest that acute hypoxia enhances SOCE via activating SOCCs, leading to increased [Ca(2+)]i in distal PVSMCs.
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Affiliation(s)
- Gongyong Peng
- Guangzhou Institute of Respiratory Disease, State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510120, China; ; Division of Pulmonary & Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21224, USA
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MCGAHON MARYK, MCKEE JONATHAN, DASH DURGAP, BROWN EOIN, SIMPSON DAVIDA, CURTIS TIMOTHYM, McGEOWN JAMESG, SCHOLFIELD CHARLESN. Pharmacological Profiling of Store-Operated Ca2+Entry in Retinal Arteriolar Smooth Muscle. Microcirculation 2012; 19:586-97. [DOI: 10.1111/j.1549-8719.2012.00192.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Inhibition of voltage-gated K+ channels and Ca2+ channels by diphenidol. Pharmacol Rep 2012; 64:739-44. [PMID: 22814027 DOI: 10.1016/s1734-1140(12)70869-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 01/05/2012] [Indexed: 11/24/2022]
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14
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Takada M, Noguchi A, Sayama Y, Kurohane Kaneko Y, Ishikawa T. Inositol 1,4,5-trisphosphate receptor-mediated initial Ca(2+) mobilization constitutes a triggering signal for hydrogen peroxide-induced apoptosis in INS-1 β-cells. Biol Pharm Bull 2011; 34:954-8. [PMID: 21719997 DOI: 10.1248/bpb.34.954] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Reactive oxygen species, including hydrogen peroxide (H(2)O(2)), are known to induce β-cell apoptosis. The present study investigated the role of Ca(2+) in H(2)O(2)-induced apoptosis of the β-cell line INS-1. Annexin V assay with flow cytometry and DNA ladder assay demonstrated that treatment of INS-1 cells with 100 µM H(2)O(2) for 18 h significantly increased apoptotic cells. A comparable level of apoptosis was also observed after 18 h when the cells were treated with 100 µM H(2)O(2) only for initial 30 min. The H(2)O(2)-induced apoptosis was abolished by 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester (BAPTA/AM), a chelator of intracellular Ca(2+), by 2-aminoethoxydiphenylborate (2-APB), a blocker of inositol 1,4,5-trisphosphate (IP(3)) receptors and cation channels, and by xestospongin D, a blocker of IP(3) receptors, and was partially blocked by SKF-96365, a non-selective cation channel blocker. However, nicardipine, an L-type voltage-dependent Ca(2+) channel blocker, or N-(p-amylcinnamoyl)anthranilic acid (ACA), a TRPM2 blocker, had little effect on the apoptosis. The inhibitory effect of BAPTA/AM or 2-APB on the H(2)O(2)-induced apoptosis was largely attenuated when the drug was added 30 min or 1 h after start of the treatment with H(2)O(2). These results suggest that the initial intracellular Ca(2+) elevation induced by H(2)O(2), which is mediated via IP(3) receptors and store-operated cation channels, plays an obligatory role in the induction of β-cell apoptosis.
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Affiliation(s)
- Masahiro Takada
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52–1 Yada, Surugaku, Shizuoka, Shizuoka 422–8526, Japan
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15
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Harteneck C, Gollasch M. Pharmacological modulation of diacylglycerol-sensitive TRPC3/6/7 channels. Curr Pharm Biotechnol 2011; 12:35-41. [PMID: 20932261 PMCID: PMC3267170 DOI: 10.2174/138920111793937943] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 05/13/2010] [Indexed: 01/03/2023]
Abstract
Members of the classic type of transient receptor potential channels (TRPC) represent important molecules involved in hormonal signal transduction. TRPC3/6/7 channels are of particular interest as they are components of phospholipase C driven signalling pathways. Upon receptor-activation, G-protein-mediated stimulation of phospholipase C results in breakdown of phosphatidylinositides leading to increased intracellular diacylglycerol and inositol-trisphosphate levels. Diacylglycerol activates protein kinase C, but more interestingly diacylglycerol directly activates TRPC2/3/6/7 channels. Molecular cloning, expression and characterization of TRP channels enabled reassignment of traditional inhibitors of receptor-dependent calcium entry such as SKF-96365 and 2-APB as blockers of TRPC3/6/7 and several members of non-classic TRP channels. Furthermore, several enzyme inhibitors have also been identified as TRP channel blockers, such as ACA, a phospholipase A2 inhibitor, and W-7, a calmodulin antagonist. Finally, the naturally occurring secondary plant compound hyperforin has been identified as TRPC6-selective drug, providing an exciting proof of concept that it is possible to generate TRPC-selective channel modulators. The description of Pyr3 as the first TRPC3-selective inhibitor shows that not only nature but also man is able to generate TRP-selective modulators. The review sheds lights on the current knowledge and historical development of pharmacological modulators of TRPC3/6/7. Our analysis indicates that Pyr3 and hyperforin provide promising core structures for the development of new, selective and more potent modulators of TRPC3/6/7 activity.
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Affiliation(s)
- Christian Harteneck
- Institut für Pharmakologie & Toxikologie, Eberhard-Karls-Universitát, Wilhelmstraße 56, 72074 Tübingen, Germany.
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16
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Burgos RA, Conejeros I, Hidalgo MA, Werling D, Hermosilla C. Calcium influx, a new potential therapeutic target in the control of neutrophil-dependent inflammatory diseases in bovines. Vet Immunol Immunopathol 2011; 143:1-10. [PMID: 21764141 DOI: 10.1016/j.vetimm.2011.05.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/06/2011] [Accepted: 05/08/2011] [Indexed: 01/07/2023]
Abstract
Neutrophils are the first line of defense against pathogens in bovines; however, they are also one of the most aggressive cells during the inflammatory process, causing injury in surrounding tissues. At present, anti-inflammatory drugs are limited in acute diseases, such as pneumonia, mastitis and endometritis, because neutrophils are mostly insensitive. One of the earliest events during neutrophil activation is the increase in intracellular calcium concentration. The calcium movement is attributed to the release from intracellular stores and influx through the calcium channels in the plasma membrane, a process called store operated calcium entry (SOCE). Recently, several calcium influx blockers have been shown to have strong effects on bovine neutrophils, and this suggests that the manipulation of this pathway can be useful in the control of neutrophil functions during acute inflammatory processes. In this paper, we will review the role of calcium influx as a potential anti-inflammatory target and summarize the most recent evidences for this in bovine neutrophils.
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Affiliation(s)
- R A Burgos
- Laboratory of Molecular Pharmacology, Institute of Pharmacology and Morphophysiology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile.
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17
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Ng AN, Krogh M, Toresson H. Dendritic EGFP-STIM1 activation after type I metabotropic glutamate and muscarinic acetylcholine receptor stimulation in hippocampal neuron. J Neurosci Res 2011; 89:1235-44. [PMID: 21538465 DOI: 10.1002/jnr.22648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 02/01/2011] [Accepted: 02/21/2011] [Indexed: 11/08/2022]
Abstract
Several signaling pathways in neurons engage the endoplasmic reticulum (ER) calcium store by triggering calcium release. After release, ER calcium levels must be restored. In many non-neuronal cell types, this is mediated by store-operated calcium entry (SOCE), a cellular homeostatic mechanism that activates specialized store-operated calcium channels (SOC). Although much evidence supports the existence of SOCE in neurons, its importance has been difficult to determine because of the abundance of calcium channels expressed and the lack of SOC-specific pharmacological agents. We have explored the function of the SOCE-inducing protein STIM1 in neurons. In EGFP-STIM1-expressing hippocampal neurons, the sarco- and endoplasmic reticulum calcium ATPase (SERCA) inhibitor thapsigargin caused rapid aggregation (i.e., activation) of STIM1 in soma and dendrites. Upon STIM1 activation by thapsigargin, a dramatic reduction in STIM1 mobility was detected by fluorescence recovery after photobleaching (FRAP). By triggering release of ER calcium with 3,5-dihydroxyphenylglycine (DHPG) or carbachol (Cch), agonists of type I metabotropic glutamate receptors (mGluR) and muscarinic acetylcholine receptors (mAChR), respectively, STIM1 was activated, and calcium entry (likely to represent SOCE) occurred in dendrites. It is therefore possible that neuronal SOCE is activated by physiological stimuli, some of which may alter the postsynaptic calcium signaling properties.
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Affiliation(s)
- Ai Na Ng
- Laboratory for Experimental Brain Research, Wallenberg Neuroscience Centre, Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
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18
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Harteneck C, Klose C, Krautwurst D. Synthetic modulators of TRP channel activity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:87-106. [PMID: 21290290 DOI: 10.1007/978-94-007-0265-3_4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In humans, 27 TRP channels from 6 related families contribute to a broad spectrum of cellular functions, such as thermo-, pressure-, volume-, pain- and chemosensation. Pain and inflammation-inducing compounds represent potent plant and animal defense mechanisms explaining the great variety of the naturally occurring, TRPV1-, TRPM8-, and TRPA1-activating ligands. The discovery of the first vanilloid receptor (TRPV1) and its involvement in nociception triggered the euphoria and the hope in novel therapeutic strategies treating pain, and this clear-cut indication inspired the development of TRPV1-selective ligands. On the other hand the nescience in the physiological role and putative clinical indication hampered the development of a selective drug in the case of the other TRP channels. Therefore, currently only a handful of mostly un-selective blocker is available to target TRP channels. Nevertheless, there is an ongoing quest for new, natural or synthetic ligands and modulators. In this chapter, we will give an overview on available broad-range blocker, as well as first TRP channel-selective compounds.
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Affiliation(s)
- Christian Harteneck
- Institute for Pharmacology and Toxicology, Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICEPHA), Eberhard-Karls-University, Tübingen, Germany.
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19
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Treves S, Vukcevic M, Jeannet PY, Levano S, Girard T, Urwyler A, Fischer D, Voit T, Jungbluth H, Lillis S, Muntoni F, Quinlivan R, Sarkozy A, Bushby K, Zorzato F. Enhanced excitation-coupled Ca(2+) entry induces nuclear translocation of NFAT and contributes to IL-6 release from myotubes from patients with central core disease. Hum Mol Genet 2010; 20:589-600. [PMID: 21088110 DOI: 10.1093/hmg/ddq506] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Prolonged depolarization of skeletal muscle cells induces entry of extracellular calcium into muscle cells, an event referred to as excitation-coupled calcium entry. Skeletal muscle excitation-coupled calcium entry relies on the interaction between the 1,4-dihydropyridine receptor on the sarcolemma and the ryanodine receptor on the sarcoplasmic reticulum membrane. In this study, we directly measured excitation-coupled calcium entry by total internal reflection fluorescence microscopy in human skeletal muscle myotubes harbouring mutations in the RYR1 gene linked to malignant hyperthermia (MH) and central core disease (CCD). We found that excitation-coupled calcium entry is strongly enhanced in cells from patients with CCD compared with individuals with MH and controls. Furthermore, excitation-coupled calcium entry induces generation of reactive nitrogen species and enhances nuclear localization of NFATc1, which in turn may be responsible for the increased IL-6 released by myotubes from patients with CCD.
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Affiliation(s)
- Susan Treves
- Department of Anesthesia, Basel University Hospital, 4031 Basel, Switzerland.
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20
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Lee KH, Cho JH, Choi IS, Park HM, Lee MG, Choi BJ, Jang IS. Pregnenolone sulfate enhances spontaneous glutamate release by inducing presynaptic Ca2+-induced Ca2+ release. Neuroscience 2010; 171:106-16. [PMID: 20816925 DOI: 10.1016/j.neuroscience.2010.07.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Revised: 07/27/2010] [Accepted: 07/27/2010] [Indexed: 01/08/2023]
Abstract
Pregnenolone sulfate (PS) acts as an excitatory neuromodulator and has a variety of neuropharmacological actions, such as memory enhancement and convulsant effects. In the present study, we investigated the effect of PS on glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs) in acutely isolated dentate gyrus (DG) hilar neurons by use of a conventional whole-cell patch-clamp technique. PS significantly increased sEPSC frequency in a concentration-dependent manner without affecting the current amplitude, suggesting that PS acts presynaptically to increase the probability of spontaneous glutamate release. However, known molecular targets of PS, such as α7 nicotinic ACh, NMDA, σ1 receptors and voltage-dependent Ca(2+) channels, were not responsible for the PS-induced increase in sEPSC frequency. In contrast, the PS-induced increase in sEPSC frequency was completely occluded in a Ca(2+)-free external solution, and was significantly reduced by either the depletion of presynaptic Ca(2+) stores or the blockade of ryanodine receptors, suggesting that PS elicits Ca(2+)-induced Ca(2+) release (CICR) within glutamatergic nerve terminals. In addition, the PS-induced increase in sEPSC frequency was completely occluded by transient receptor potential (TRP) channel blockers. These data suggest that PS increases spontaneous glutamate release onto acutely isolated hilar neurons via presynaptic CICR, which was triggered by the influx of Ca(2+) through presynaptic TRP channels. The PS-induced modulation of excitatory transmission onto hilar neurons could have a broad impact on the excitability of hilar neurons and affect the pathophysiological functions mediated by the hippocampus.
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Affiliation(s)
- K H Lee
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
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Peng G, Lu W, Li X, Chen Y, Zhong N, Ran P, Wang J. Expression of store-operated Ca2+ entry and transient receptor potential canonical and vanilloid-related proteins in rat distal pulmonary venous smooth muscle. Am J Physiol Lung Cell Mol Physiol 2010; 299:L621-30. [PMID: 20693314 DOI: 10.1152/ajplung.00176.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic hypoxia causes remodeling and alters contractile responses in both pulmonary arteries and pulmonary veins. Although pulmonary arteries have been studied extensively in these disorders, the mechanisms by which pulmonary veins respond to hypoxia and whether these responses contribute to chronic hypoxic pulmonary hypertension remain poorly understood. In pulmonary arterial smooth muscle, we have previously demonstrated that influx of Ca(2+) through store-operated calcium channels (SOCC) thought to be composed of transient receptor potential (TRP) proteins is likely to play an important role in development of chronic hypoxic pulmonary hypertension. To determine whether this mechanism could also be operative in pulmonary venous smooth muscle, we measured intracellular Ca(2+) concentration ([Ca(2+)](i)) by fura-2 fluorescence microscopy in primary cultures of pulmonary venous smooth muscle cells (PVSMC) isolated from rat distal pulmonary veins. In cells perfused with Ca(2+)-free media containing cyclopiazonic acid (10 μM) and nifedipine (5 μM) to deplete sarcoplasmic reticulum Ca(2+) stores and block voltage-dependent Ca(2+) channels, restoration of extracellular Ca(2+) (2.5 mM) caused marked increases in [Ca(2+)](i), whereas MnCl(2) (200 μM) quenched fura-2 fluorescence, indicating store-operated Ca(2+) entry (SOCE). SKF-96365 and NiCl(2), antagonists of SOCC, blocked SOCE at concentrations that did not alter Ca(2+) responses to 60 mM KCl. Of the seven known canonical TRP (TRPC1-7) and six vanilloid-related TRP channels (TRPV1-6), real-time PCR revealed mRNA expression of TRPC1 > TRPC6 > TRPC4 > TRPC2 ≈ TRPC5 > TRPC3, TRPV2 > TRPV4 > TRPV1 in distal PVSMC, and TRPC1 > TRPC6 > TRPC3 > TRPC4 ≈ TRPC5, TRPV2 ≈ TRPV4 > TRPV1 in rat distal pulmonary vein (PV) smooth muscle. Western blotting confirmed protein expression of TRPC1, TRPC6, TRPV2, and TRPV4 in both PVSMC and PV. Our results suggest that SOCE through Ca(2+) channels composed of TRP proteins may contribute to Ca(2+) signaling in rat distal PV smooth muscle.
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Affiliation(s)
- Gongyong Peng
- Guangzhou Institute of Respiratory Diseases, State Key Laboratory of Respiratory Diseases, Guangzhou Medical University, China
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22
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Estève E, Eltit JM, Bannister RA, Liu K, Pessah IN, Beam KG, Allen PD, López JR. A malignant hyperthermia-inducing mutation in RYR1 (R163C): alterations in Ca2+ entry, release, and retrograde signaling to the DHPR. ACTA ACUST UNITED AC 2010; 135:619-28. [PMID: 20479110 PMCID: PMC2888056 DOI: 10.1085/jgp.200910328] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bidirectional signaling between the sarcolemmal L-type Ca(2+) channel (1,4-dihydropyridine receptor [DHPR]) and the sarcoplasmic reticulum (SR) Ca(2+) release channel (type 1 ryanodine receptor [RYR1]) of skeletal muscle is essential for excitation-contraction coupling (ECC) and is a well-understood prototype of conformational coupling. Mutations in either channel alter coupling fidelity and with an added pharmacologic stimulus or stress can trigger malignant hyperthermia (MH). In this study, we measured the response of wild-type (WT), heterozygous (Het), or homozygous (Hom) RYR1-R163C knock-in mouse myotubes to maintained K(+) depolarization. The new findings are: (a) For all three genotypes, Ca(2+) transients decay during prolonged depolarization, and this decay is not a consequence of SR depletion or RYR1 inactivation. (b) The R163C mutation retards the decay rate with a rank order WT > Het > Hom. (c) The removal of external Ca(2+) or the addition of Ca(2+) entry blockers (nifedipine, SKF96365, and Ni(2+)) enhanced the rate of decay in all genotypes. (d) When Ca(2+) entry is blocked, the decay rates are slower for Hom and Het than WT, indicating that the rate of inactivation of ECC is affected by the R163C mutation and is genotype dependent (WT > Het > Hom). (e) Reduced ECC inactivation in Het and Hom myotubes was shown directly using two identical K(+) depolarizations separated by varying time intervals. These data suggest that conformational changes induced by the R163C MH mutation alter the retrograde signal that is sent from RYR1 to the DHPR, delaying the inactivation of the DHPR voltage sensor.
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Affiliation(s)
- Eric Estève
- Department of Anesthesiology Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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23
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Ge R, Tai Y, Sun Y, Zhou K, Yang S, Cheng T, Zou Q, Shen F, Wang Y. Critical role of TRPC6 channels in VEGF-mediated angiogenesis. Cancer Lett 2009; 283:43-51. [PMID: 19394138 DOI: 10.1016/j.canlet.2009.03.023] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/15/2009] [Accepted: 03/16/2009] [Indexed: 12/21/2022]
Abstract
Intracellular Ca(2+) signaling plays critical roles in VEGF-mediated angiogenesis. Transient receptor potential canonical (TRPC) channel 6, a Ca(2+)-permeable non-selective cation channel, can be activated by VEGF. Here, we report that TRPC6 is important for VEGF-mediated angiogenesis. Inhibition of TRPC6 in human umbilical vein endothelial cells (HUVECs) by pharmacological or genetic approaches arrested HUVECs at G2/M phase and suppressed VEGF-induced HUVEC proliferation and tube formation. Furthermore, inhibition of TRPCs abolished VEGF-, but not FGF-induced angiogenesis in the chick embryo chorioallantoic membrane. These results suggest that TRPC6 plays an important role in VEGF-mediated angiogenesis.
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Affiliation(s)
- Ruiliang Ge
- Division of Comprehensive Treatment, Eastern Hepatobiliary Hospital, Second Military Medical University, Shanghai 200438, China
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24
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Launikonis BS, Stephenson DG, Friedrich O. Rapid Ca2+ flux through the transverse tubular membrane, activated by individual action potentials in mammalian skeletal muscle. J Physiol 2009; 587:2299-312. [PMID: 19332499 DOI: 10.1113/jphysiol.2009.168682] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Periods of low frequency stimulation are known to increase the net Ca(2+) uptake in skeletal muscle but the mechanism responsible for this Ca(2+) entry is not known. In this study a novel high-resolution fluorescence microscopy approach allowed the detection of an action potential-induced Ca(2+) flux across the tubular (t-) system of rat extensor digitorum longus muscle fibres that appears to be responsible for the net uptake of Ca(2+) in working muscle. Action potentials were triggered in the t-system of mechanically skinned fibres from rat by brief field stimulation and t-system [Ca(2+)] ([Ca(2+)](t-sys)) and cytoplasmic [Ca(2+)] ([Ca(2+)](cyto)) were simultaneously resolved on a confocal microscope. When initial [Ca(2+)](t-sys) was > or = 0.2 mM a Ca(2+) flux from t-system to the cytoplasm was observed following a single action potential. The action potential-induced Ca(2+) flux and associated t-system Ca(2+) permeability decayed exponentially and displayed inactivation characteristics such that further Ca(2+) entry across the t-system could not be observed after 2-3 action potentials at 10 Hz stimulation rate. When [Ca(2+)](t-sys) was closer to 0.1 mM, a transient rise in [Ca(2+)](t-sys) was observed almost concurrently with the increase in [Ca(2+)](cyto) following the action potential. The change in direction of Ca(2+) flux was consistent with changes in the direction of the driving force for Ca(2+). This is the first demonstration of a rapid t-system Ca(2+) flux associated with a single action potential in mammalian skeletal muscle. The properties of this channel are inconsistent with a flux through the L-type Ca(2+) channel suggesting that an as yet unidentified t-system protein is conducting this current. This action potential-activated Ca(2+) flux provides an explanation for the previously described Ca(2+) entry and accumulation observed with prolonged, intermittent muscle activity.
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Affiliation(s)
- Bradley S Launikonis
- School of Biomedical Sciences, University of Queensland, Brisbane, Qld 4072, Australia.
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25
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Zhang WB, Kwan CY. Unrepeatable extracellular Ca2+-dependent contractile effects of cyclopiazonic acid in rat vascular smooth muscle. Eur J Pharmacol 2009; 610:81-6. [PMID: 19292983 DOI: 10.1016/j.ejphar.2009.03.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2009] [Accepted: 03/09/2009] [Indexed: 11/16/2022]
Abstract
Cyclopiazonic acid (CPA), a specific reversible inhibitor of Ca(2+)-pumps in sarcoplasmic reticulum, causes a slowly developing and subsequently diminishing characteristic contraction in endothelium-denuded rat vascular smooth muscle. We recently found that CPA-induced contractions were not completely repeatable in endothelium-denuded rat aorta and superior mesenteric artery. 10 microM CPA-induced contractions expressed as a percentage of 80 mM KCl-induced contraction were significantly decreased from 51.4+/-5.7% to 11.8+/-2.6% (P<0.0001) upon the second application in endothelium-denuded rat aorta, and this was not due to any irreversible cytotoxic effects of CPA. The decrease of CPA-induced contractile responses upon the second application was dependent on both types of blood vessels and doses of CPA upon the first application. CPA upon the second application in Ca(2+)-containing solutions did induce its characteristic contractions in the rings pretreated with Ca(2+)-free solutions or Ca(2+) entry blockers before and during its first application, suggesting that capacitative mode of Ca(2+) influx during the application of CPA might be responsible for the diminishment of contractions upon the second application. These data suggest that CPA by inducing a transient rise in cytosolic Ca(2+) level might cause a long-lasting upregulation of Ca(2+) extrusion across the plasma membrane in vascular smooth muscle cells and thus accelerate Ca(2+) efflux over a prolonged period, leading to unrepeatable contractile effects of CPA. Such long-lasting upregulation of Ca(2+) extrusion may contribute to the regulation of excitability of vascular smooth muscle cells and protect the cells against excitotoxic injury.
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Affiliation(s)
- Wen-Bo Zhang
- Research Institute of Basic Medical Sciences and Vascular Biology Research Group, College of Medicine, China Medical University, 91 Hue-Shih Road, Taichung, 40402, Taiwan
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26
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Shideman CR, Reinardy JL, Thayer SA. gamma-Secretase activity modulates store-operated Ca2+ entry into rat sensory neurons. Neurosci Lett 2008; 451:124-8. [PMID: 19114088 DOI: 10.1016/j.neulet.2008.12.031] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/09/2008] [Accepted: 12/17/2008] [Indexed: 01/24/2023]
Abstract
Presenilin-1 is required for gamma-secretase activity, which participates in Notch receptor processing, the pathogenesis of Alzheimer's disease and the modulation of Ca(2+) signaling. We tested the hypothesis that gamma-secretase proteolytic activity modulates store-operated Ca(2+) entry (SOCE) in rat dorsal root ganglion (DRG) neurons. Depletion of intracellular Ca(2+) stores by blocking the endoplasmic reticulum (ER) Ca(2+) pump with cyclopiazonic acid (CPA) evoked a transient increase in [Ca(2+)](i) but no sustained Ca(2+) influx. However, in cells expressing a dominant negative presenilin-1 mutant (PS1-D257A), gamma-secretase activity was inhibited and treatment with CPA evoked sustained Ca(2+) influx. Similarly, pharmacologic inhibition of gamma-secretase with DAPT for 48h enhanced SOCE. SKF96365, an inhibitor of store-operated channels, blocked SOCE in cells expressing PS1-D257A. Thus, gamma-secretase proteolytic activity regulates a SOCE pathway in sensory neurons.
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Affiliation(s)
- Charles R Shideman
- Department of Pharmacology, University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455-0217, United States
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27
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Brown RC, Wu L, Hicks K, O'neil RG. Regulation of blood-brain barrier permeability by transient receptor potential type C and type v calcium-permeable channels. Microcirculation 2008; 15:359-71. [PMID: 18464164 DOI: 10.1080/10739680701762656] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To identify plasma membrane ion channels mediating calcium influx at the blood-brain barrier in response to disrupting stimuli. METHODS We examined the expression and function of candidate transient receptor potential channels using reverse transcriptase polymerase chain recation, Fura-2 calcium imaging, and permeability assays. RESULTS Immortalized mouse brain microvessel endothelial cells expressed multiple transient receptor potential isoforms: transient receptor potential C1, C2, C4, and C7, M2, M3, M4, and M7, and V2 and V4. Similar profiles were observed in freshly isolated cerebral microvessels and primary cultured rat brain endothelial cells. Thrombin-stimulated calcium influx in brain endothelial cells was blocked by transient receptor potential C inhibitors. Transient receptor potential V activating stimuli also increased intracellular calcium. This increase was inhibited by a transient receptor potential V blocker or by removal of extracellular calcium. Barrier integrity was compromised by thrombin, hypo-osmolar stress, and PMA treatment. The increase in barrier permeability induced by transient receptor potential V activators was blocked by transient receptor potential V inhibition, while thrombin effects were inhibited by transient receptor potential C inhibitors. CONCLUSIONS These results demonstrate that transient receptor potential C and transient receptor potential V channels mediate calcium influx at the blood-brain barrier, and as a consequence, may modulate barrier integrity.
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Affiliation(s)
- Rachel C Brown
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, USA
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29
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Palmerini CA, Mazzoni M, Saccardi C, Arienti G. The cytosolic calcium concentration is affected by S-nitrosocysteine in human lymphomonocytes. J Biochem Mol Toxicol 2008; 22:35-40. [PMID: 18273907 DOI: 10.1002/jbt.20211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The homeostasis of cytosolic calcium [Ca2+](c) in mammalian cells is a complex phenomenon, requiring the contribution of many cellular and extracellular systems. Nitric oxide (NO) acts on [Ca2+](c), although the mechanism of this action is unknown. We study the release and the uptake of Ca2+ in the endoplasmic reticulum and its capacitative entry in human lymphomonocytes in the presence of the NO donor S-nitrosocysteine (CysNO) at low (16 microM) and at high (160 microM) concentrations by measuring the [Ca2+](c) by the Fura 2-AM method. Thapsigargin (TG), which inhibits sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), and nifedipine (NIF), which blocks the Ca2+ release from intracellular stores, are used to clarify the effects of NO on calcium movements. In the absence of extracellular Ca2+, CysNO decreases basal [Ca2+](c), whereas TG increases it as the result of SERCA inhibition. This effect of TG diminishes in the presence of the NO donor. In the presence of extracellular Ca2+(capacitative entry conditions), CysNO does not influence Ca2+ entry but reduces the toxic effects of TG connected to the increase of [Ca2+](c) in these conditions. The effect of NIF is, up to a certain extent, similar to that of CysNO, although the mechanisms of action of the two agents do not seem related. We conclude that CysNO participates in [Ca2+](c) homeostasis by stimulating the movement of the ion from the cytosol to other compartments.
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Affiliation(s)
- Carlo A Palmerini
- Department of Internal Medicine, The Medical School, University of Perugia, Via del Giochetto, 06122 Perugia, Italy.
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30
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Sandoval AJ, Riquelme JP, Carretta MD, Hancke JL, Hidalgo MA, Burgos RA. Store-operated calcium entry mediates intracellular alkalinization, ERK1/2, and Akt/PKB phosphorylation in bovine neutrophils. J Leukoc Biol 2007; 82:1266-77. [PMID: 17684040 DOI: 10.1189/jlb.0307196] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Neutrophil's responses to G protein-coupled chemoattractants are highly dependent on store-operated calcium (Ca(2+)) entry (SOCE). Platelet-activating factor (PAF), a primary chemoattractant, simultaneously increases cytosolic-free Ca(2+), intracellular pH (pH(i)), ERK1/2, and Akt/protein kinase B (PKB) phosphorylation. In this study, we looked at the efficacy of several putative SOCE inhibitors and whether SOCE mediates intracellular alkalinization, ERK1/2, and Akt/PKB phosphorylation in bovine neutrophils. We demonstrated that the absence of external Ca(2+) and the presence of EGTA reduced the intracellular alkalinization and ERK1/2 phosphorylation induced by PAF, apparently via SOCE influx inhibition. Next, we tested the efficacy of several putative SOCE inhibitors such as 2-aminoethoxydiphenyl borate (2-APB), capsaicin, flufenamic acid, 1-{beta-[3-(4-methoxy-phenyl)propoxy]-4-methoxyphenethyl}-1H-imidazole hydrochloride (SK&F 96365), and N-(4-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl]phenyl)-4-methyl-1,2,3-thiadiazole-5-carboxamide (BTP2) on Ca(2+) entry induced by PAF or thapsigargin. 2-APB was the most potent SOCE inhibitor, followed by capsaicin and flufenamic acid. Conversely, SK&F 96365 reduced an intracellular calcium ([Ca(2+)](i)) peak but SOCE partially. BTP2 did not show an inhibitory effect on [Ca(2+)](i) following PAF stimuli. 2-APB strongly reduced the pH(i) recovery, whereas the effect of flufenamic acid and SK&F 96365 was partial. Capsaicin and BTP2 did not affect the pH(i) changes induced by PAF. Finally, we observed that 2-APB reduced the ERK1/2 and Akt phosphorylation completely, whereas the inhibition with flufenamic acid was partial. The results suggest that 2-APB is the most potent SOCE inhibitor and support a key role of SOCE in pH alkalinization and PI-3K-ERK1/2 pathway control. Finally, 2-APB could be an important tool to characterize Ca(2+) signaling in neutrophils.
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Affiliation(s)
- Alvaro J Sandoval
- Laboratory of Molecular Pharmacology, Institute of Pharmacology, Faculty of Veterinary Science, Universidad Austral de Chile, Valdivia, Chile
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Daniel EE, Willis A, Cho WJ, Boddy G. Comparisons of neural and pacing activities in intestinal segments from W/W++ and W/W(V) mice. Neurogastroenterol Motil 2005; 17:355-65. [PMID: 15916623 DOI: 10.1111/j.1365-2982.2005.00639.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We studied pacing and neurotransmission in longitudinal (LM) and circular muscle (CM) in intestine of W/W++ and W/W(V) mice. Electrical field-stimulation (EFS) of nerves in LM segments was more inhibitory in W/W(V) mice than in W/W++ mice. No inhibitory input to CM segments of W/W(V) mice was found. The EFS, after nerve block, entrained segments of both W/W++ and mutant mice with 10 ms pulses, and entrained those of mutant mice more readily at 1 and 3 ms pulses. Pacing with external electrodes did not depend on interstitial cells of Cajal in the myenteric plexus (ICC-MP). 2-Aminoethoxydiphenyl borate (2-APB), putative antagonist at IP3 receptors, store-operated channels and the Sacro-endoplasmic reticulum Ca2+ ATPase pump, reduced frequency and amplitudes of pacing of LM segments from W/W(V) mice as it did in BALB/c mice. Thus, its actions may not require ICC-MP. SKF 96365, a putative inhibitor of store-operated channels, reduced frequencies and amplitudes of intestinal segments in W/W++ mice at 10 or 30 micromol L-1. This resulted from blocking L-Ca2+-channels. Thus, no evidence was found that store-operated channels play a role in pacing. In LM segments of W/W(V), SKF 96365 had no effects on frequency of contractions. We conclude, results from models of severely reduced systems may not be applicable to intact ICC networks.
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Affiliation(s)
- E E Daniel
- Department of Pharmacology, University of Alberta, Edmonton, Canada.
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Wang J, Shimoda LA, Weigand L, Wang W, Sun D, Sylvester JT. Acute hypoxia increases intracellular [Ca2+] in pulmonary arterial smooth muscle by enhancing capacitative Ca2+ entry. Am J Physiol Lung Cell Mol Physiol 2005; 288:L1059-69. [PMID: 15665040 DOI: 10.1152/ajplung.00448.2004] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypoxic pulmonary vasoconstriction (HPV) requires influx of extracellular Ca2+ in pulmonary arterial smooth muscle cells (PASMCs). To determine whether capacitative Ca2+ entry (CCE) through store-operated Ca2+ channels (SOCCs) contributes to this influx, we used fluorescent microscopy and the Ca2+-sensitive dye fura-2 to measure effects of 4% O2 on intracellular [Ca2+] ([Ca2+]i) and CCE in primary cultures of PASMCs from rat distal pulmonary arteries. In PASMCs perfused with Ca2+-free Krebs Ringer bicarbonate solution (KRBS) containing cyclopiazonic acid to deplete Ca2+ stores in sarcoplasmic reticulum and nifedipine to prevent Ca2+ entry through L-type voltage-operated Ca2+ channels (VOCCs), hypoxia markedly enhanced both the increase in [Ca2+]i caused by restoration of extracellular [Ca2+] and the rate at which extracellular Mn2+ quenched fura-2 fluorescence. These effects, as well as the increased [Ca2+]i caused by hypoxia in PASMCs perfused with normal salt solutions, were blocked by the SOCC antagonists SKF-96365, NiCl2, and LaCl3 at concentrations that inhibited CCE >80% but did not alter [Ca2+]i responses to 60 mM KCl. In contrast, the VOCC antagonist nifedipine inhibited [Ca2+]i responses to hypoxia by only 50% at concentrations that completely blocked responses to KCl. The increased [Ca2+]i caused by hypoxia was completely reversed by perfusion with Ca2+-free KRBS. LaCl3 increased basal [Ca2+]i during normoxia, indicating effects other than inhibition of SOCCs. Our results suggest that acute hypoxia enhances CCE through SOCCs in distal PASMCs, leading to depolarization, secondary activation of VOCCs, and increased [Ca2+]i. SOCCs and CCE may play important roles in HPV.
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Affiliation(s)
- Jian Wang
- Div. of Pulmonary & Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Weigand L, Foxson J, Wang J, Shimoda LA, Sylvester JT. Inhibition of hypoxic pulmonary vasoconstriction by antagonists of store-operated Ca2+ and nonselective cation channels. Am J Physiol Lung Cell Mol Physiol 2005; 289:L5-L13. [PMID: 15722380 DOI: 10.1152/ajplung.00044.2005] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies indicated that acute hypoxia increased intracellular Ca(2+) concentration ([Ca(2+)](i)), Ca(2+) influx, and capacitative Ca(2+) entry (CCE) through store-operated Ca(2+) channels (SOCC) in smooth muscle cells from distal pulmonary arteries (PASMC), which are thought to be a major locus of hypoxic pulmonary vasoconstriction (HPV). Moreover, these effects were blocked by Ca(2+)-free conditions and antagonists of SOCC and nonselective cation channels (NSCC). To test the hypothesis that in vivo HPV requires CCE, we measured the effects of SOCC/NSCC antagonists (SKF-96365, NiCl(2), and LaCl(3)) on pulmonary arterial pressor responses to 2% O(2) and high-KCl concentrations in isolated rat lungs. At concentrations that blocked CCE and [Ca(2+)](i) responses to hypoxia in PASMC, SKF-96365 and NiCl(2) prevented and reversed HPV but did not alter pressor responses to KCl. At 10 microM, LaCl(3) had similar effects, but higher concentrations (30 and 100 microM) caused vasoconstriction during normoxia and potentiated HPV, indicating actions other than SOCC blockade. Ca(2+)-free perfusate and the voltage-operated Ca(2+) channel (VOCC) antagonist nifedipine were potent inhibitors of pressor responses to both hypoxia and KCl. We conclude that HPV required influx of Ca(2+) through both SOCC and VOCC. This dual requirement and virtual abolition of HPV by either SOCC or VOCC antagonists suggests that neither channel provided enough Ca(2+) on its own to trigger PASMC contraction and/or that during hypoxia, SOCC-dependent depolarization caused secondary activation of VOCC.
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Affiliation(s)
- Letitia Weigand
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins Asthma and Allergy Center, Baltimore, Maryland 21224, USA
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Cherednichenko G, Hurne AM, Fessenden JD, Lee EH, Allen PD, Beam KG, Pessah IN. Conformational activation of Ca2+ entry by depolarization of skeletal myotubes. Proc Natl Acad Sci U S A 2004; 101:15793-8. [PMID: 15505226 PMCID: PMC524834 DOI: 10.1073/pnas.0403485101] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Store-operated Ca(2+) entry (SOCE) occurs in diverse cell types in response to depletion of Ca(2+) within the endoplasmic/sarcoplasmic reticulum and functions both to refill these stores and to shape cytoplasmic Ca(2+) transients. Here we report that in addition to conventional SOCE, skeletal myotubes display a physiological mechanism that we term excitation-coupled Ca(2+) entry (ECCE). ECCE is rapidly initiated by membrane depolarization. Like excitation-contraction coupling, ECCE is absent in both dyspedic myotubes that lack the skeletal muscle-type ryanodine receptor 1 and dysgenic myotubes that lack the dihydropyridine receptor (DHPR), and is independent of the DHPR l-type Ca(2+) current. Unlike classic SOCE, ECCE does not depend on sarcoplasmic reticulum Ca(2+) release. Indeed, ECCE produces a large Ca(2+) entry in response to physiological stimuli that do not produce substantial store depletion and depends on interactions among three different Ca(2+) channels: the DHPR, ryanodine receptor 1, and a Ca(2+) entry channel with properties corresponding to those of store-operated Ca(2+) channels. ECCE may provide a fundamental means to rapidly maintain Ca(2+) stores and control important aspects of Ca(2+) signaling in both muscle and nonmuscle cells.
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Affiliation(s)
- Gennady Cherednichenko
- Department of Molecular Biosciences and Center for Children's Environmental Health and Disease Prevention, University of California, Davis, CA 95616, USA
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Hanano T, Hara Y, Shi J, Morita H, Umebayashi C, Mori E, Sumimoto H, Ito Y, Mori Y, Inoue R. Involvement of TRPM7 in cell growth as a spontaneously activated Ca2+ entry pathway in human retinoblastoma cells. J Pharmacol Sci 2004; 95:403-19. [PMID: 15286426 DOI: 10.1254/jphs.fp0040273] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
We investigated the possible involvement of the melastatin family protein TRPM7 in Ca(2+)-mediated proliferative control of human retinoblastoma (RB) cells. The growth of RB cell was facilitated by elevating the extracellular Ca(2+) concentration with a parallel increase in the magnitude of spontaneous Ca(2+) influx. Under nystatin-perforated voltage-clamp, RB cells exhibited an outward-rectifying, spontaneous cation current (I(spont)) having Ca(2+)/Mg(2+)-inhibited but -permeating properties. Various cation channel blockers inhibiting I(spont) (Gd(3+), La(3+), LOE908, 2-APB) suppressed the spontaneous Ca(2+) influx and decelerated the growth of RB cells with similar efficacies. Excision of the RB cell membrane (inside-out) into MgATP-free solution induced a 70pS single channel activity, which was effectively inhibited by millimolar concentrations of Mg(2+) or MgATP. RT-PCR and immunocytochemical experiments revealed the expression of TRPM7 mRNA and protein in RB cells, and heterologous expression of TRPM7 in HEK293 cells reproduced the key features of I(spont). In contrast, elimination of this protein from RB cells by siRNA silencing markedly reduced I(spont) density and the magnitude of spontaneous Ca(2+) influx, which was paralleled by decreased TRPM7 immunoreactivity, decelerated cell proliferation, and retarded G(1)/S cell cycle progression. These results suggest a significant regulatory role of TRPM7 for RB cell proliferation as a spontaneously activated Ca(2+) influx pathway.
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Affiliation(s)
- Toyohisa Hanano
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Tozzi A, Bengtson CP, Longone P, Carignani C, Fusco FR, Bernardi G, Mercuri NB. Involvement of transient receptor potential-like channels in responses to mGluR-I activation in midbrain dopamine neurons. Eur J Neurosci 2003; 18:2133-45. [PMID: 14622174 DOI: 10.1046/j.1460-9568.2003.02936.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We investigated the involvement of store-operated channels (SOCs) and transient receptor potential (TRP) channels in the response to activation of the group I metabotropic glutamate receptor subtype 1 (mGluR1) with the agonist (S)-3,5-dihydroxyphenylglycine (DHPG, puff application) in dopamine neurons in rat brain slices. The mGluR1-induced conductance reversed polarity close to 0 mV and at more positive potentials when extracellular potassium concentrations were increased, indicating the involvement of a cationic channel. DHPG currents but not intracellular calcium responses were reduced by low extracellular sodium concentrations but were not affected by sodium channel blockers, tetrodotoxin and saxitoxin or by inhibition of the h-current with cesium. Abolition of calcium responses with intracellular BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; 10 mm) did not affect current responses, indicating they were not calcium activated. Extracellular application of non-selective SOCs and TRP channel blockers 2-aminoethoxydiphenylborane (2-APB), SKF96365, ruthenium red and flufenamic acid (but not gadolinium) reduced DHPG current and calcium responses. Intracellular application of ruthenium red and 2-APB did not affect DHPG currents, indicating that IP3 and ryanodine receptors did not mediate their actions. Single-cell PCR revealed the presence of TRPC1 and 5 mRNA in most dopamine neurons and subtypes 3, 4 and 6 in some. Store depletion evoked calcium entry indicative of SOCs, providing the first functional observation of such channels in native central neurons. Store depletion with either cyclopiazonic acid or ryanodine abolished calcium but not current responses to DHPG. The electrophysiological and pharmacological properties of the mGluR1-induced inward current are consistent with the involvement of TRP channels whereas calcium responses are dependent on the function of SOCs in voltage clamp recordings.
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Affiliation(s)
- Alessandro Tozzi
- Experimental Neurology Laboratory, I.R.C.C.S. Fondazione Santa Lucia Via Ardeatina 306, Rome, Italy
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Wang J, Shimoda LA, Sylvester JT. Capacitative calcium entry and TRPC channel proteins are expressed in rat distal pulmonary arterial smooth muscle. Am J Physiol Lung Cell Mol Physiol 2003; 286:L848-58. [PMID: 14672922 DOI: 10.1152/ajplung.00319.2003] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammalian homologs of transient receptor potential (TRP) genes in Drosophila encode TRPC proteins, which make up cation channels that play several putative roles, including Ca2+ entry triggered by depletion of Ca2+ stores in endoplasmic reticulum (ER). This capacitative calcium entry (CCE) is thought to replenish Ca2+ stores and contribute to signaling in many tissues, including smooth muscle cells from main pulmonary artery (PASMCs); however, the roles of CCE and TRPC proteins in PASMCs from distal pulmonary arteries, which are thought to be the major site of pulmonary vasoreactivity, remain uncertain. As an initial test of the possibility that TRPC channels contribute to CCE and Ca2+ signaling in distal PASMCs, we measured [Ca2+]i by fura-2 fluorescence in primary cultures of myocytes isolated from rat intrapulmonary arteries (>4th generation). In cells perfused with Ca2+-free media containing cyclopiazonic acid (10 microM) and nifedipine (5 microM) to deplete ER Ca2+ stores and block voltage-dependent Ca2+ channels, restoration of extracellular Ca2+ (2.5 mM) caused marked increases in [Ca2+]i whereas MnCl2 (200 microM) quenched fura-2 fluorescence, indicating CCE. SKF-96365, LaCl3, and NiCl2, blocked CCE at concentrations that did not alter Ca2+ responses to 60 mM KCl (IC50 6.3, 40.4, and 191 microM, respectively). RT-PCR and Western blotting performed on RNA and protein isolated from distal intrapulmonary arteries and PASMCs revealed mRNA and protein expression for TRPC1, -4, and -6, but not TRPC2, -3, -5, or -7. Our results suggest that CCE through TRPC-encoded Ca2+ channels could contribute to Ca2+ signaling in myocytes from distal intrapulmonary arteries.
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Affiliation(s)
- Jian Wang
- Div. of Pulmonary & Critical Care Medicine, The Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Cir., Baltimore, MD 21224, USA
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Zhang WB, Chen CX, Sim SM, Kwan CY. In vitro vasodilator mechanisms of the indole alkaloids rhynchophylline and isorhynchophylline, isolated from the hook of Uncaria rhynchophylla (Miquel). Naunyn Schmiedebergs Arch Pharmacol 2003; 369:232-8. [PMID: 14668978 DOI: 10.1007/s00210-003-0854-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Accepted: 11/18/2003] [Indexed: 10/26/2022]
Abstract
Rhynchophylline (Rhy) and isorhynchophylline (Isorhy), indole alkaloids from Uncaria hooks, reportedly exert hypotensive and vasodilatory effects, but the mechanism of action is unclear. We therefore investigated the relaxant effects of these two isomeric alkaloids in rat arteries in vitro, in particular in respect of the various functional Ca2+ pathways. Both Rhy and Isorhy relaxed aortic rings precontracted with phenylephrine (PE, 1 microM) in a dose-dependent manner (3-300 microM). Removal of endothelium and preincubation with L-NAME (300 microM) slightly inhibited but did not prevent the relaxant response. These results indicate that Rhy and Isorhy act largely in an endothelium-independent manner. Unlike nicardipine, both alkaloids not only inhibited the contraction induced by 60 mM KCl (IC50 20-30 microM), but also that induced by PE and U46619, albeit to a lesser extent (IC50 100 and 200 microM, respectively). These results suggest that Rhy and Isorhy may act via multiple Ca2+ pathways. In contrast to their inhibitory effects on KCl-induced and receptor-mediated contractions, where both isomers were comparably potent, Rhy was more potent than Isorhy at higher concentrations (>100 microM) in inhibiting both caffeine (25 mM)- and cyclopiazonic acid (CPA, 30 microM)-induced contractions. Similar results observed with caffeine in Ca2+-containing medium were also observed in Ca2+-free medium. However, 0.1-0.3 microM nicardipine (which completely inhibited KCl-induced contraction) had no significant inhibitory effect on CPA-induced contractions. Taken together, these results indicate discrimination between these two isomers with respect to Ca2+-induced Ca2+ release and non-L-type Ca2+ channel, but not for IP3-induced Ca2+ release and L-type Ca2+ channels. Similar relaxant responses to KCl- and caffeine-induced contractions were seen when these two alkaloids were tested on the smaller mesenteric and renal arteries. In conclusion, the vasodilatory effects of Rhy and Isorhy are largely endothelium independent and are mediated by L-type Ca2+ channels. At higher concentrations, they also affect other Ca2+-handling pathways, although to a lesser extent. While there is no discrimination between the two isomers with respect to the contraction induced by KCl or agonists (PE and U46619), differential effects between Rhy and Isorhy were seen on caffeine- and CPA-induced contractions.
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Affiliation(s)
- Wen-Bo Zhang
- Department of Medicine, Faculty of Health Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5, Canada
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Abstract
The Ca2+ influx controlled by intracellular Ca2+ stores, called store-operated Ca2+ entry (SOC), occurs in various eukaryotic cells, but whether CNS neurons are endowed with SOC capability and how they may operate have been contentious issues. Using Ca2+ imaging, we present evidence for the presence of SOC in cultured hippocampal pyramidal neurons. Depletion of internal Ca2+ stores by thapsigargin caused intracellular Ca2+ elevation, which was prevented by SOC channel inhibitors 2-aminoethoxydiphenyl borate (2-APB), SKF96365, and La3+. Interestingly, these inhibitors also accelerated the decay of NMDA-induced Ca2+ transients without affecting their peak amplitude. In addition, SOC channel inhibitors attenuated tetanus-induced dendritic Ca2+ accumulation and long-term potentiation at Schaffer collateral-CA1 synapses in hippocampal slice preparations. These data suggest a novel link between ionotropic receptor-activated SOC and neuroplasticity.
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Vanden Abeele F, Shuba Y, Roudbaraki M, Lemonnier L, Vanoverberghe K, Mariot P, Skryma R, Prevarskaya N. Store-operated Ca2+ channels in prostate cancer epithelial cells: function, regulation, and role in carcinogenesis. Cell Calcium 2003; 33:357-73. [PMID: 12765682 DOI: 10.1016/s0143-4160(03)00049-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ca2+ homeostasis mechanisms, in which the Ca2+ entry pathways play a key role, are critically involved in both normal function and cancerous transformation of prostate epithelial cells. Here, using the lymph node carcinoma of the prostate (LNCaP) cell line as a major experimental model, we characterize prostate-specific store-operated Ca2+ channels (SOCs)--a primary Ca2+ entry pathway for non-excitable cells--for the first time. We show that prostate-specific SOCs share major store-dependent, kinetic, permeation, inwardly rectifying, and pharmacological (including dual, potentiation/inhibition concentration-dependent sensitivity to 2-APB) properties with "classical" Ca2+ release-activated Ca2+ channels (CRAC), but have a higher single channel conductance (3.2 and 12pS in Ca2+- and Na+-permeable modes, respectively). They are subject to feedback inhibition via Ca2+-dependent PKC, CaMK-II and CaM regulatory pathways and are functionally dependent on caveolae integrity. Caveolae also provide a scaffold for spatial co-localization of SOCs with volume-regulated anion channels (VRAC) and their Ca2+-mediated interaction. The TRPC1 and TRPV6 members of the transient receptor potential (TRP) channel family are the most likely molecular candidates for the formation of prostate-specific endogenous SOCs. Differentiation of LNCaP cells to an androgen-insensitive, apoptotic-resistant neuroendocrine phenotype downregulates SOC current. We conclude that prostate-specific SOCs are important determinants in the transition to androgen-independent prostate cancer.
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Affiliation(s)
- F Vanden Abeele
- Laboratoire de Physiologie Cellulaire, INSERM EMI 0228, Bâtiment SN3, USTL, 59655 Villeneuve d'Ascq, France
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Sekiguchi F, Kawata K, Komori M, Sunano S. Caffeine-induced contracture in oesophageal striated muscle of normotensive and hypertensive rats. Eur J Pharmacol 2003; 465:153-61. [PMID: 12650845 DOI: 10.1016/s0014-2999(03)01435-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To elucidate whether properties of the sarcoplasmic reticulum are altered, not only in vascular smooth muscle, but also in visceral striated muscle of spontaneously hypertensive rats (SHR), caffeine-induced contractures in oesophageal striated muscle of Wistar Kyoto rats (WKY) and stroke-prone SHR (SHRSP) were compared. In both preparations, 30 mM caffeine induced a contracture with two components. The second component, which was diminished by extracellular Ca(2+) removal or Ni(2+) but not by verapamil, was much smaller in SHRSP. Both components and differences between WKY and SHRSP coincided with changes in intracellular Ca(2+). Although membrane potential was identical between these preparations, caffeine induced slight depolarization only in WKY preparations. Similar depolarization was observed with 10 mM K(+), which induced no contraction. It is suggested that the first and the second components of caffeine-induced contracture were induced by Ca(2+) released from sarcoplasmic reticulum and by Ca(2+) that entered through channels activated by sarcoplasmic reticulum Ca(2+) depletion, respectively. In SHRSP preparations, Ca(2+) from the latter pathway was clearly decreased, although this change is thought not to be related to the initiation of hypertension. These results suggest that Ca(2+) handling properties of cell membrane and sarcoplasmic reticulum are generally altered in muscles of SHRSP.
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Affiliation(s)
- Fumiko Sekiguchi
- Department of Anatomy and Physiology, Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Osaka Higashiosaka 577-8502, Japan
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Shen JZ, Zheng XF, Wei EQ, Kwan CY. Green tea catechins evoke a phasic contraction in rat aorta via H2O2-mediated multiple-signalling pathways. Clin Exp Pharmacol Physiol 2003; 30:88-95. [PMID: 12542460 DOI: 10.1046/j.1440-1681.2003.03796.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The contractile effects of tea polyphenols (TP) and its four principle catechins, namely (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), on rat aorta contractility were investigated using the isometric tension recording technique. 2. At concentrations of 5-100 mg/L, TP evoked phasic contraction of rat aorta in a concentration-dependent but endothelium-independent manner. Of the four catechins tested, EGCG and EGC (3-300 micromol/L), but not EC and ECG, mimicked the contractile response to TP, suggesting that the epigallol moiety in the B ring may be associated with the contractile effect. 3. Contractions in response to EGCG and EGC were not affected by several endogenous vasoconstrictor receptor antagonists, but could be abolished by 10 micro mol/L BAPTA-AM, a membrane-permeable Ca2+ chelator, or attenuated by removal of extracellular Ca2+, suggesting the involvement of both intracellular and extracellular Ca2+ in evoking the contraction. 4. Pretreatment with non-selective Ca2+ channel antagonists mefenamic acid (10 micro mol/L), tetrandrine (30 micro mol/L) and SKF 96365 (30 micromol/L), but not nifedipine (1 micromol/L), the selective inhibitor of voltage-dependent Ca2+ channels, inhibited the contractile responses to EGC and EGCG, indicating the involvement of Ca2+ influx via non-voltage dependent Ca2+ channels. 5. Several intracellular Ca2+ channel modulators, including procaine (5 mmol/L), dantrolene (30 micromol/L) and 2-amino ethoxydiphenyl borate (50 micromol/L; an inositol 1,4,5-trisphosphate receptor inhibitor), also inhibited EGCG- and EGC-induced contractions, thus suggesting a role of intracellular Ca2+ release in these contractions. 6. Both EGCG- and EGC-induced contractions were depressed, to different degrees, by inhibitors of several receptor-coupled enzymes, including phospholipase C, protein kinase C, phospholipase A2 and tyrosine kinase. Furthermore, both EGCG- and EGC-induced contractions were completely abolished by catalase, but not by superoxide dismutase or mannitol/dimethyl sulphoxide. 7. Taken together, these data show, for the first time, that TP and its related catechins that contain an epigallol structure in the B ring, as in EGCG and EGC, exert direct contractile effects on rat aortic smooth muscle via a H2O2-mediated pathway.
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Affiliation(s)
- Jian-Zhong Shen
- Department of Pharmacology, School of Medicine, Zhejiang University, Hubin Campus, Hangzhou, People's Republic of China
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Morita K, Sakakibara A, Kitayama S, Kumagai K, Tanne K, Dohi T. Pituitary adenylate cyclase-activating polypeptide induces a sustained increase in intracellular free Ca(2+) concentration and catechol amine release by activating Ca(2+) influx via receptor-stimulated Ca(2+) entry, independent of store-operated Ca(2+) channels, and voltage-dependent Ca(2+) channels in bovine adrenal medullary chromaffin cells. J Pharmacol Exp Ther 2002; 302:972-82. [PMID: 12183654 DOI: 10.1124/jpet.102.033456] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Characteristics of pituitary adenylate cyclase-activating polypeptide (PACAP)-induced increase of Ca(2+) entry and catecholamine (CA) release were studied in bovine adrenal medullary chromaffin cells. PACAP induced intracellular free Ca(2+) concentration ([Ca(2+)](i)), showing an initial transient [Ca(2+)](i) rise followed by a sustained rise and CA release, which were not blocked by the blocking agents for nicotinic acetylcholine receptor (nAChR) channel, the voltage-dependent Ca(2+) channel (VOC), or the Na(+) channel. The sarcoendoplasmic Ca(2+)-ATPase inhibitors thapsigargin and cyclopiazonic acid did not affect the PACAP-induced sustained rise of [Ca(2+)](i), but did inhibit the initial [Ca(2+)](i) rise. In cells pretreated with cyclopiazonic acid or membrane-permeable, low-affinity Ca(2+) chelator N',N',N',N'-tetrakis(2-pyridylmethyl)ethylenediamine, PACAP further stimulated the entry of Ca(2+) or Mn(2+), whereas these treatments masked [Ca(2+)](i) dynamics induced by bradykinin. PACAP-induced sustained [Ca(2+)](i) rise and Mn(2+) entry were enhanced by acidic extracellular solution and reduced by alkalinization, whereas thapsigargin-induced Mn(2+) entry was regulated by the opposite. PACAP-induced [Ca(2+)](i) rise and Mn(2+) entry were not affected by blockers of cAMP-dependent protein kinase, phospholipase C, or protein kinase C. All store-operated Ca(2+) channel (SOC) blocking agents tested inhibited thapsigargin-induced Mn(2+) entry. 1(beta-[3-(4-Methoxyphenyl)-propoxy]-4-methoxyphenylethyl)-1H-imidazole hydrochloride (SK&F 96365), (R,S)-(3,4-dihydro-6,7-dimethoxy-isoquinoline-1-yl)-2-phenyl-N,N-di-[2-(2,3,4-trimethoxyphenyl)ethyl]-acetamide, and econazole inhibited PACAP-induced Ca(2+) or Mn(2+) entry, whereas GdCl(3), 7,8-benzoflavone, nor-dihydroguaiaretic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid, fulfenamic acid, and niflumic acid did not. SK&F 96365 and econazole but not GdCl(3) inhibited PACAP-induced CA release. These results suggest that PACAP activates a novel Ca(2+) entry pathway associated with sustained CA release independent of the nAChR channel, VOC and SOC, activated by acid pH, with different sensitivity to blockers of SOC. This pathway may provide a useful model for the study of receptor-operated Ca(2+) entry.
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Affiliation(s)
- Katsuya Morita
- Department of Dental Pharmacology, Division of Integrated Medical Science, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553, Japan
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Davis MJ, Wu X, Nurkiewicz TR, Kawasaki J, Gui P, Hill MA, Wilson E. Regulation of ion channels by protein tyrosine phosphorylation. Am J Physiol Heart Circ Physiol 2001; 281:H1835-62. [PMID: 11668044 DOI: 10.1152/ajpheart.2001.281.5.h1835] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ion channels are regulated by protein phosphorylation and dephosphorylation of serine, threonine, and tyrosine residues. Evidence for the latter process, tyrosine phosphorylation, has increased substantially since this topic was last reviewed. In this review, we present a comprehensive summary and synthesis of the literature regarding the mechanism and function of ion channel regulation by protein tyrosine kinases and phosphatases. Coverage includes the majority of voltage-gated, ligand-gated, and second messenger-gated channels as well as several types of channels that have not yet been cloned, including store-operated Ca2+ channels, nonselective cation channels, and epithelial Na+ and Cl- channels. Additionally, we discuss the critical roles that channel-associated scaffolding proteins may play in localizing protein tyrosine kinases and phosphatases to the vicinity of ion channels.
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Affiliation(s)
- M J Davis
- Department of Medical Physiology, Cardiovascular Research Institute, Texas A&M University System Health Science Center, College Station, Texas 77845, USA.
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Jezior JR, Brady JD, Rosenstein DI, McCammon KA, Miner AS, Ratz PH. Dependency of detrusor contractions on calcium sensitization and calcium entry through LOE-908-sensitive channels. Br J Pharmacol 2001; 134:78-87. [PMID: 11522599 PMCID: PMC1572931 DOI: 10.1038/sj.bjp.0704241] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2001] [Revised: 06/14/2001] [Accepted: 06/21/2001] [Indexed: 11/09/2022] Open
Abstract
1. The subcellular mechanisms regulating stimulus-contraction coupling in detrusor remain to be determined. We used Ca(2+)-free solutions, Ca(2+) channel blockers, cyclopiazonic acid (CPA), and RhoA kinase (ROK) inhibitors to test the hypothesis that Ca(2+) influx and Ca(2+) sensitization play primary roles. 2. In rabbit detrusor, peak bethanechol (BE)-induced force was inhibited 90% by incubation for 3 min in a Ca(2+)-free solution. By comparison, a 20 min incubation of rabbit femoral artery in a Ca(2+)-free solution reduced receptor-induced force by only 5%. 3. In detrusor, inhibition of sarcoplasmic reticular (SR) Ca(2+) release by 2APB, or depletion of SR Ca(2+) by CPA, inhibited BE-induced force by only 27%. The CPA-insensitive force was abolished by LaCl3. By comparison, 2APB inhibited receptor-induced force in rabbit femoral artery by 71%. 4. In the presence of the non-selective cation channel (NSCC) inhibitor, LOE-908, BE did not produce an increase in [Ca(2+)]i but did produce weak increases in myosin phosphorylation and force. 5. Inhibitors of ROK-induced Ca(2+) sensitization, HA-1077 and Y-27632, inhibited BE-induced force by approximately 50%, and in combination with LOE-908, nearly abolished force. 6. These data suggest that two principal muscarinic receptor-stimulated detrusor contractile mechanisms include NSCC activation, that elevates [Ca(2+)]i and ROK activation, that sensitizes cross bridges to Ca(2+).
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Affiliation(s)
- James R Jezior
- Department of Urology, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
| | - Jeffrey D Brady
- Department of Urology, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
| | - Daniel I Rosenstein
- Department of Urology, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
| | - Kurt A McCammon
- Department of Urology, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
| | - Amy S Miner
- Department of Physiological Sciences, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
| | - Paul H Ratz
- Department of Physiological Sciences, Eastern Virginia Medical School, PO Box 1980, Norfolk, Virginia, VA 23501, U.S.A
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