1
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Perez-Zoghbi JF, Sajorda DR, Webb DA, Arnold LA, Emala CW, Yocum GT. Imidazobenzodiazepine PI320 Relaxes Mouse Peripheral Airways by Inhibiting Calcium Mobilization. Am J Respir Cell Mol Biol 2022; 67:482-490. [PMID: 35776523 PMCID: PMC9564932 DOI: 10.1165/rcmb.2022-0084oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Asthma is a common respiratory disease characterized, in part, by excessive airway smooth muscle (ASM) contraction (airway hyperresponsiveness). Various GABAAR (γ-aminobutyric acid type A receptor) activators, including benzodiazepines, relax ASM. The GABAAR is a ligand-operated Cl- channel best known for its role in inhibitory neurotransmission in the central nervous system. Although ASM cells express GABAARs, affording a seemingly logical site of action, the mechanism(s) by which GABAAR ligands relax ASM remains unclear. PI320, a novel imidazobenzodiazepine designed for tissue selectivity, is a promising asthma drug candidate. Here, we show that PI320 alleviates methacholine (MCh)-induced bronchoconstriction in vivo and relaxes peripheral airways preconstricted with MCh ex vivo using the forced oscillation technique and precision-cut lung slice experiments, respectively. Surprisingly, the peripheral airway relaxation demonstrated in precision-cut lung slices does not appear to be GABAAR-dependent, as it is not inhibited by the GABAAR antagonist picrotoxin or the benzodiazepine antagonist flumazenil. Furthermore, we demonstrate here that PI320 inhibits MCh-induced airway constriction in the absence of external Ca2, suggesting that PI320-mediated relaxation is not mediated by inhibition of Ca2+ influx in ASM. However, PI320 does inhibit MCh-induced intracellular Ca2+ oscillations in peripheral ASM, a key mediator of contraction that is dependent on sarcoplasmic reticulum Ca2+ mobilization. Furthermore, PI320 inhibits peripheral airway constriction induced by experimentally increasing the intracellular concentration of inositol triphosphate (IP3). These novel data suggest that PI320 relaxes murine peripheral airways by inhibiting intracellular Ca2+ mobilization in ASM, likely by inhibiting Ca2+ release through IP3Rs (IP3 receptors).
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Affiliation(s)
- Jose F. Perez-Zoghbi
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Dannah Rae Sajorda
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Daniel A. Webb
- Department of Chemistry and Biochemistry and,Milwaukee Institute for Drug Discovery, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin
| | - Leggy A. Arnold
- Department of Chemistry and Biochemistry and,Milwaukee Institute for Drug Discovery, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin
| | - Charles W. Emala
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Gene T. Yocum
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
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2
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Cholesterylation of Smoothened is a calcium-accelerated autoreaction involving an intramolecular ester intermediate. Cell Res 2022; 32:288-301. [PMID: 35121857 PMCID: PMC8888579 DOI: 10.1038/s41422-022-00622-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/10/2022] [Indexed: 12/16/2022] Open
Abstract
Hedgehog (Hh) is a morphogen that binds to its receptor Patched 1 and activates Smoothened (SMO), thereby governing embryonic development and postnatal tissue homeostasis. Cholesterol can bind and covalently conjugate to the luminal cysteine-rich domain (CRD) of human SMO at the D95 residue (D99 in mouse). The reaction mechanism and biological function of SMO cholesterylation have not been elucidated. Here, we show that the SMO-CRD undergoes auto-cholesterylation which is boosted by calcium and involves an intramolecular ester intermediate. In cells, Hh stimulation elevates local calcium concentration in the SMO-localized endosomes through store-operated calcium entry. In addition, we identify the signaling-incompetent SMO D95E mutation, and the D95E mutant SMO can bind cholesterol but cannot be modified or activated by cholesterol. The homozygous SmoD99E/D99E knockin mice are embryonic lethal with severe developmental delay, demonstrating that cholesterylation of CRD is required for full-length SMO activation. Our work reveals the unique autocatalytic mechanism of SMO cholesterylation and an unprecedented role of calcium in Hh signaling.
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Ngai TW, Elfar GA, Yeo P, Phua N, Hor JH, Chen S, Ho YS, Cheok CF. Nitro-Deficient Niclosamide Confers Reduced Genotoxicity and Retains Mitochondrial Uncoupling Activity for Cancer Therapy. Int J Mol Sci 2021; 22:10420. [PMID: 34638761 PMCID: PMC8508655 DOI: 10.3390/ijms221910420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/16/2021] [Accepted: 09/18/2021] [Indexed: 11/16/2022] Open
Abstract
Niclosamide is an oral anthelmintic drug, approved for use against tapeworm infections. Recent studies suggest however that niclosamide may have broader clinical applications in cancers, spurring increased interest in the functions and mechanisms of niclosamide. Previously, we reported that niclosamide targets a metabolic vulnerability in p53-deficient tumours, providing a basis for patient stratification and personalised treatment strategies. In the present study, we functionally characterised the contribution of the aniline 4'-NO2 group on niclosamide to its cellular activities. We demonstrated that niclosamide induces genome-wide DNA damage that is mechanistically uncoupled from its antitumour effects mediated through mitochondrial uncoupling. Elimination of the nitro group in ND-Nic analogue significantly reduced γH2AX signals and DNA breaks while preserving its antitumour mechanism mediated through a calcium signalling pathway and arachidonic acid metabolism. Lipidomics profiling further revealed that ND-Nic-treated cells retained a metabolite profile characteristic of niclosamide-treated cells. Notably, quantitative scoring of drug sensitivity suggests that elimination of its nitro group enhanced the target selectivity of niclosamide against p53 deficiency. Importantly, the results also raise concern that niclosamide may impose a pleiotropic genotoxic effect, which limits its clinical efficacy and warrants further investigation into alternative drug analogues that may ameliorate any potential unwanted side effects.
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Affiliation(s)
- Tsz Wai Ngai
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
| | - Gamal Ahmed Elfar
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore
| | - Pearlyn Yeo
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore
| | - Nicholas Phua
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
| | - Jin Hui Hor
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
| | - Shuwen Chen
- Analytical Science and Technology (Metabolomics), Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore; (S.C.); (Y.S.H.)
| | - Ying Swan Ho
- Analytical Science and Technology (Metabolomics), Bioprocessing Technology Institute, 20 Biopolis Way, Centros #06-01, Singapore 138668, Singapore; (S.C.); (Y.S.H.)
| | - Chit Fang Cheok
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore; (T.W.N.); (G.A.E.); (P.Y.); (N.P.); (J.H.H.)
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore
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4
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Imoto T, Minoshima M, Yokoyama T, Emery BP, Bull SD, Bito H, Kikuchi K. A Photodeactivatable Antagonist for Controlling CREB-Dependent Gene Expression. ACS CENTRAL SCIENCE 2020; 6:1813-1818. [PMID: 33145417 PMCID: PMC7596873 DOI: 10.1021/acscentsci.0c00736] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Indexed: 06/11/2023]
Abstract
A novel photodeactivation strategy for controlling gene expression has been developed based on light-induced activation of cAMP response element binding protein (CREB). Light-induced cleavage of the photoresponsive protecting group of an antagonist of CREB binding protein (CBP) results in photocleaved products with weak binding affinity for CBP. This photodissociation reaction enables protein-protein interactions between CBP and CREB that trigger the formation of a multiprotein transcription complex to turn gene expression "on". This enables irradiation of antagonist-treated HEK293T cells to be used to trigger temporal recovery of CREB-dependent transcriptional activity and endogenous gene expression under photolytic control.
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Affiliation(s)
- Takuma Imoto
- Division
of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masafumi Minoshima
- Division
of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tatsushi Yokoyama
- Department
of Neurochemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ben P. Emery
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Steven D. Bull
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Haruhiko Bito
- Department
of Neurochemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazuya Kikuchi
- Division
of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Immunology
Frontier Research Center, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Quantum
Information and Quantum Biology Division, Institute for Open and Transdisciplinary
Research Initiatives, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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5
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Siddon AJ, Tormey CA, Snyder EL. Platelet Transfusion Medicine. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00064-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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6
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Mitochondrial uncoupling reveals a novel therapeutic opportunity for p53-defective cancers. Nat Commun 2018; 9:3931. [PMID: 30258081 PMCID: PMC6158291 DOI: 10.1038/s41467-018-05805-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 05/10/2018] [Indexed: 12/11/2022] Open
Abstract
There are considerable challenges in directly targeting the mutant p53 protein, given the large heterogeneity of p53 mutations in the clinic. An alternative approach is to exploit the altered fitness of cells imposed by loss-of-wild-type p53. Here we identify niclosamide through a HTS screen for compounds selectively killing p53-deficient cells. Niclosamide impairs the growth of p53-deficient cells and of p53 mutant patient-derived ovarian xenografts. Metabolome profiling reveals that niclosamide induces mitochondrial uncoupling, which renders mutant p53 cells susceptible to mitochondrial-dependent apoptosis through preferential accumulation of arachidonic acid (AA), and represents a first-in-class inhibitor of p53 mutant tumors. Wild-type p53 evades the cytotoxicity by promoting the transcriptional induction of two key lipid oxygenation genes, ALOX5 and ALOX12B, which catalyzes the dioxygenation and breakdown of AA. Therefore, we propose a new paradigm for targeting cancers defective in the p53 pathway, by exploiting their vulnerability to niclosamide-induced mitochondrial uncoupling. Several challenges are involved in direct targeting of mutant p53, while targeting altered fitness of cells with loss of wild type p53 is an alternative approach. Here they identify niclosamide to be selectively toxic to p53 deficient cells through a previously unknown mitochondrial uncoupling mechanism.
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7
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Simons J, Fauci L. A Model for the Acrosome Reaction in Mammalian Sperm. Bull Math Biol 2018; 80:2481-2501. [PMID: 30094771 DOI: 10.1007/s11538-018-0478-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 07/23/2018] [Indexed: 12/31/2022]
Abstract
The acrosome reaction is a complex, calcium-dependent reaction that results in an exocytotic event required for successful fertilization of the egg. It has long been thought that the acrosome reaction occurs upon sperm binding to the zona pellucida, a viscoelastic layer surrounding the oocyte. Recent studies have suggested that the reaction may even occur before the sperm encounters the zona, perhaps mediated by progesterone or some other agonist. It has been particularly difficult to understand differences between progesterone-induced and zona-induced reactions experimentally and whether one substance is the more biologically relevant trigger. Until this present work, there has been little effort to mathematically model the acrosome reaction in sperm as a whole. Instead, attention has been paid to modeling portions of the pathways involved in other cell types. Here we present a base model for the acrosome reaction which characterizes the known biochemical reactions and behaviors of the system. Our model allows us to analyze several pathways that may act as a stabilizing mechanism for avoiding sustained oscillatory calcium responses often observed in other cell types. Such an oscillatory regime might otherwise prevent acrosomal exocytosis and therefore inhibit fertilization. Results indicate that the acrosome reaction may rely upon multiple redundant mechanisms to avoid entering an oscillatory state and instead maintain a high resting level of calcium, known to be required for successful acrosomal exocytosis and, ultimately, fertilization of the oocyte.
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Affiliation(s)
- Julie Simons
- Department of Sciences and Mathematics, California Maritime Academy, 200 Maritime Academy Dr., Vallejo, CA, 95490-8181, USA.
| | - Lisa Fauci
- Department of Mathematics and Center for Computational Science, Tulane University, 6823 St. Charles Ave., New Orleans, LA, 70118, USA
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8
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Koupenova M, Ravid K. Biology of Platelet Purinergic Receptors and Implications for Platelet Heterogeneity. Front Pharmacol 2018; 9:37. [PMID: 29441021 PMCID: PMC5797577 DOI: 10.3389/fphar.2018.00037] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/12/2018] [Indexed: 12/29/2022] Open
Abstract
Platelets are small anucleated cells present only in mammals. Platelets mediate intravascular hemostatic balance, prevent interstitial bleeding, and have a major role in thrombosis. Activation of platelet purinergic receptors is instrumental in initiation of hemostasis and formation of the hemostatic plug, although this activation process becomes problematic in pathological settings of thrombosis. This review briefly outlines the roles and function of currently known platelet purinergic receptors (P1 and P2) in the setting of hemostasis and thrombosis. Additionally, we discuss recent novel studies on purinergic receptor distribution according to heterogeneous platelet size, and the possible implication of this distribution on hemostatic function.
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Affiliation(s)
- Milka Koupenova
- Department of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, MA, United States
| | - Katya Ravid
- Departments of Medicine and Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, United States
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9
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Wu CY, Hsu WL, Tsai MH, Liang JL, Lu JH, Yen CJ, Yu HS, Noda M, Lu CY, Chen CH, Yan SJ, Yoshioka T. Hydrogen gas protects IP3Rs by reducing disulfide bridges in human keratinocytes under oxidative stress. Sci Rep 2017; 7:3606. [PMID: 28620198 PMCID: PMC5472599 DOI: 10.1038/s41598-017-03513-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Based on the oxidative stress theory, aging derives from the accumulation of oxidized proteins induced by reactive oxygen species (ROS) in the cytoplasm. Hydrogen peroxide (H2O2) elicits ROS that induces skin aging through oxidation of proteins, forming disulfide bridges with cysteine or methionine sulfhydryl groups. Decreased Ca2+ signaling is observed in aged cells, probably secondary to the formation of disulfide bonds among Ca2+ signaling-related proteins. Skin aging processes are modeled by treating keratinocytes with H2O2. In the present study, H2O2 dose-dependently impaired the adenosine triphosphate (ATP)-induced Ca2+ response, which was partially protected via co-treatment with β-mercaptoethanol, resulting in reduced disulfide bond formation in inositol 1, 4, 5-trisphosphate receptors (IP3Rs). Molecular hydrogen (H2) was found to be more effectively protected H2O2-induced IP3R1 dysfunction by reducing disulfide bonds, rather than quenching ROS. In conclusion, skin aging processes may involve ROS-induced protein dysfunction due to disulfide bond formation, and H2 can protect oxidation of this process.
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Affiliation(s)
- Ching-Ying Wu
- Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 68, Jhonghua 3rd Rd, Cianjin District, Kaohsiung, 80145, Taiwan.,Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Wen-Li Hsu
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Road, Tainan, 70101, Taiwan.,Lipid Science and Aging Research Center, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Ming-Hsien Tsai
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.,Lipid Science and Aging Research Center, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Jui-Lin Liang
- Chi Mei Medical Center, No. 201, Taikang, Taikang Vil., Liuying Dist., Tainan City, 736, Taiwan
| | - Jian-He Lu
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Chia-Jung Yen
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Hsin-Su Yu
- Department of Dermatology, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.,National Health Research Institutes, Distinguished Investigator, National Environmental Health Research Center, No. 35, Keyan Road, Zhunan Town, Miaoli County, 35053, Taiwan
| | - Mami Noda
- Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1Maidashi, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Chi-Yu Lu
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan
| | - Chu-Huang Chen
- Center for Lipid Biosciences, Kaohsiung Medical University Hospital, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.,Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.,Lipid Science and Aging Research Center, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.,Vascular and Medicinal Research, Texas Heart Institute, Houston, TX, USA.,New York Heart Research Foundation, Mineola, NY, USA
| | - Shian-Jang Yan
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, 1 University Road, Tainan, 70101, Taiwan. .,Department of Physiology, College of Medicine, National Cheng Kung University, 1 University Road, Tainan, 70101, Taiwan.
| | - Tohru Yoshioka
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan. .,Lipid Science and Aging Research Center, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.
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10
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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11
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ISOBE K, YOKOYAMA T, MORIGUCHI-MORI K, KUMAGAI M, SATOH YI, KUJI A, SAINO T. Role of pituitary adenylyl cyclase-activating polypeptide in intracellular calcium dynamics of neurons and satellite cells in rat superior cervical ganglia . Biomed Res 2017; 38:99-109. [DOI: 10.2220/biomedres.38.99] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Kanako ISOBE
- Department of Anatomy (Cell Biology), Iwate Medical University
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Takuya YOKOYAMA
- Department of Anatomy (Cell Biology), Iwate Medical University
| | - Kasumi MORIGUCHI-MORI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Miho KUMAGAI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Yoh-ichi SATOH
- Department of Anatomy (Cell Biology), Iwate Medical University
- Department of Medical Education, Iwate Medical University
| | - Akiyoshi KUJI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Tomoyuki SAINO
- Department of Anatomy (Cell Biology), Iwate Medical University
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12
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Hao Y, Chow AW, Yip WC, Li CH, Wan TF, Tong BC, Cheung KH, Chan WY, Chen Y, Cheng CH, Ko WH. G protein-coupled estrogen receptor inhibits the P2Y receptor-mediated Ca(2+) signaling pathway in human airway epithelia. Pflugers Arch 2016; 468:1489-503. [PMID: 27271044 PMCID: PMC4951515 DOI: 10.1007/s00424-016-1840-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/11/2016] [Accepted: 05/22/2016] [Indexed: 12/18/2022]
Abstract
P2Y receptor activation causes the release of inflammatory cytokines in the bronchial epithelium, whereas G protein-coupled estrogen receptor (GPER), a novel estrogen (E2) receptor, may play an anti-inflammatory role in this process. We investigated the cellular mechanisms underlying the inhibitory effect of GPER activation on the P2Y receptor-mediated Ca2+ signaling pathway and cytokine production in airway epithelia. Expression of GPER in primary human bronchial epithelial (HBE) or 16HBE14o- cells was confirmed on both the mRNA and protein levels. Stimulation of HBE or 16HBE14o- cells with E2 or G1, a specific agonist of GPER, attenuated the nucleotide-evoked increases in [Ca2+]i, whereas this effect was reversed by G15, a GPER-specific antagonist. G1 inhibited the secretion of two proinflammatory cytokines, interleukin (IL)-6 and IL-8, in cells stimulated by adenosine 5′-(γ-thio)triphosphate (ATPγS). G1 stimulated a real-time increase in cAMP levels in 16HBE14o- cells, which could be inhibited by adenylyl cyclase inhibitors. The inhibitory effects of E2 or G1 on P2Y receptor-induced increases in Ca2+ were reversed by treating the cells with a protein kinase A (PKA) inhibitor. These results demonstrated that the inhibitory effects of G1 or E2 on P2Y receptor-mediated Ca2+ mobilization and cytokine secretion were due to GPER-mediated activation of a cAMP-dependent PKA pathway. This study has reported, for the first time, the expression and function of GPER as an anti-inflammatory component in human bronchial epithelia, which may mediate through its opposing effects on the pro‐inflammatory pathway activated by the P2Y receptors in inflamed airway epithelia.
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Affiliation(s)
- Yuan Hao
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Alison W Chow
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Wallace C Yip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Chi H Li
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Tai F Wan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Benjamin C Tong
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - King H Cheung
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wood Y Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Yangchao Chen
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Christopher H Cheng
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong.
| | - Wing H Ko
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong.
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13
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Cuíñas A, García-Morales V, Viña D, Gil-Longo J, Campos-Toimil M. Activation of PKA and Epac proteins by cyclic AMP depletes intracellular calcium stores and reduces calcium availability for vasoconstriction. Life Sci 2016; 155:102-9. [PMID: 27142830 DOI: 10.1016/j.lfs.2016.03.059] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/23/2016] [Accepted: 03/03/2016] [Indexed: 12/15/2022]
Abstract
AIMS We investigated the implication of PKA and Epac proteins in the endothelium-independent vasorelaxant effects of cyclic AMP (cAMP). MAIN METHODS Cytosolic Ca(2+) concentration ([Ca(2+)]c) was measured by fura-2 imaging in rat aortic smooth muscle cells (RASMC). Contraction-relaxation experiments were performed in rat aortic rings deprived of endothelium. KEY FINDINGS In extracellular Ca(2+)-free solution, cAMP-elevating agents induced an increase in [Ca(2+)]c in RASMC that was reproduced by PKA and Epac activation and reduced after depletion of intracellular Ca(2+) reservoirs. Arginine-vasopressin (AVP)-evoked increase of [Ca(2+)]c and store-operated Ca(2+) entry (SOCE) were inhibited by cAMP-elevating agents, PKA or Epac activation in these cells. In aortic rings, the contractions induced by phenylephrine in absence of extracellular Ca(2+) were inhibited by cAMP-elevating agents, PKA or Epac activation. In these conditions, reintroduction of Ca(2+) induced a contraction that was inhibited by cAMP-elevating agents, an effect reduced by PKA inhibition and reproduced by PKA or Epac activators. SIGNIFICANCE Our results suggest that increased cAMP depletes intracellular, thapsigargin-sensitive Ca(2+) stores through activation of PKA and Epac in RASMC, thus reducing the amount of Ca(2+) released by IP3-generating agonists during the contraction of rat aorta. cAMP rise also inhibits the contraction induced by depletion of intracellular Ca(2+), an effect mediated by reduction of SOCE after PKA or Epac activation. Both effects participate in the cAMP-induced endothelium-independent vasorelaxation.
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Affiliation(s)
- Andrea Cuíñas
- Farmacología de las Enfermedades Crónicas (CDPHARMA), Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Verónica García-Morales
- Farmacología de las Enfermedades Crónicas (CDPHARMA), Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Dolores Viña
- Farmacología de las Enfermedades Crónicas (CDPHARMA), Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - José Gil-Longo
- Farmacología de las Enfermedades Crónicas (CDPHARMA), Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Manuel Campos-Toimil
- Farmacología de las Enfermedades Crónicas (CDPHARMA), Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
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Belleville-Rolland T, Sassi Y, Decouture B, Dreano E, Hulot JS, Gaussem P, Bachelot-Loza C. MRP4 (ABCC4) as a potential pharmacologic target for cardiovascular disease. Pharmacol Res 2016; 107:381-389. [PMID: 27063943 DOI: 10.1016/j.phrs.2016.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/02/2016] [Indexed: 01/13/2023]
Abstract
This review focuses on multidrug resistance protein 4 (MRP4 or ABCC4) that has recently been shown to play a role in cAMP homeostasis, a key-pathway in vascular biology and in platelet functions. In vascular system, recent data provide evidence that inhibition of MRP4 prevents human coronary artery smooth muscle cell proliferation in vitro and in vivo, as well as human pulmonary artery smooth muscle cell proliferation in vitro and pulmonary hypertension in mice in vivo. In the heart, MRP4 silencing in adult rat ventricular myocytes results in an increase in intracellular cAMP levels leading to enhanced cardiomyocyte contractility. However, a prolonged inhibition of MRP4 can promote cardiac hypertrophy. In addition, secreted cAMP, through its metabolite adenosine, prevents adrenergically induced cardiac hypertrophy and fibrosis. Finally, MRP4 inhibition in platelets induces a moderate thrombopathy. The localization of MRP4 underlines the emerging concept of cAMP compartmentalization in platelets, which is a major regulatory mechanism in other cells. cAMP storage in platelet dense granules might limit the cAMP cytosolic concentration upon adenylate cyclase activation, a necessary step to induce platelet activation. In this review, we discuss the therapeutic potential of direct pharmacological inhibition of MRP4 in atherothrombotic disease, via its vasodilating and antiplatelet effects.
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Affiliation(s)
- Tiphaine Belleville-Rolland
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; AP-HP, Hôpital Européen Georges Pompidou, Service dhématologie biologique, Paris, France
| | - Yassine Sassi
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Benoit Decouture
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Elise Dreano
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jean-Sébastien Hulot
- AP-HP, Institute of Cardiometabolism and Nutrition (ICAN), Pitié-Salpêtrière Hospital, F-75013 Paris, France; Sorbonne Universités, UPMC Univ. Paris 06, France
| | - Pascale Gaussem
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; AP-HP, Hôpital Européen Georges Pompidou, Service dhématologie biologique, Paris, France
| | - Christilla Bachelot-Loza
- Inserm UMR-S1140, Faculté de Pharmacie, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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15
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Tang J, Li J, Sikdar D, Kong B, Quan Y, Che S, Wang Y, Al-Enizi AM, Premaratne M, Zheng G. Plasmon-enhanced photoelectrochemical monitoring of Ca2+ from living cardiomyocytes. J Electroanal Chem (Lausanne) 2015. [DOI: 10.1016/j.jelechem.2015.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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16
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Tadevosyan A, Villeneuve LR, Fournier A, Chatenet D, Nattel S, Allen BG. Caged ligands to study the role of intracellular GPCRs. Methods 2015. [PMID: 26196333 DOI: 10.1016/j.ymeth.2015.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In addition to cell surface membranes, numerous G protein-coupled receptors (GPCRs) are located on intracellular membranes including the nuclear envelope. Although the role of numerous GPCRs at the cell surface has been well characterized, the physiological function of these same receptors located on intracellular membranes remains to be determined. Here, we employ a novel caged Ang-II analog, cAng-II, to compare the effects of the activation of cell surface versus intracellular angiotensin receptors in intact cardiomyocytes. When added extracellularly to HEK 293 cells, Ang-II and photolysed cAng-II increased ERK1/2 phosphorylation (via AT1R) and cGMP production (AT2R). In contrast unphotolysed cAng-II did not. Cellular uptake of cAng-II was 6-fold greater than that of Ang-II and comparable to the HIV TAT(48-60) peptide. Intracellular photolysis of cAng-II induced an increase in nucleoplasmic Ca(2+) ([Ca(2+)]n) that was greater than that induced by extracellular application of Ang-II. We conclude that cell-permeable ligands that can access intracellular GPCRs may evoke responses distinct from those with access restricted to the same receptor located on the cell surface.
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Affiliation(s)
- Artavazd Tadevosyan
- Department of Medicine, Université de Montréal, Canada; Montreal Heart Institute, Canada
| | | | - Alain Fournier
- INRS-Institut Armand-Frappier, Université du Québec, Canada; Laboratoire International Associé Samuel de Champlain, Canada
| | - David Chatenet
- INRS-Institut Armand-Frappier, Université du Québec, Canada; Laboratoire International Associé Samuel de Champlain, Canada
| | - Stanley Nattel
- Department of Medicine, Université de Montréal, Canada; Montreal Heart Institute, Canada; Department of Pharmacology and Therapeutics, McGill University, Canada.
| | - Bruce G Allen
- Department of Medicine, Université de Montréal, Canada; Montreal Heart Institute, Canada; Department of Pharmacology and Therapeutics, McGill University, Canada; Department of Biochemistry and Molecular Medicine, Université de Montréal, Canada.
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17
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Carbonic anhydrase-8 regulates inflammatory pain by inhibiting the ITPR1-cytosolic free calcium pathway. PLoS One 2015; 10:e0118273. [PMID: 25734498 PMCID: PMC4347988 DOI: 10.1371/journal.pone.0118273] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 01/12/2015] [Indexed: 01/01/2023] Open
Abstract
Calcium dysregulation is causally linked with various forms of neuropathology including seizure disorders, multiple sclerosis, Huntington’s disease, Alzheimer’s, spinal cerebellar ataxia (SCA) and chronic pain. Carbonic anhydrase-8 (Car8) is an allosteric inhibitor of inositol trisphosphate receptor-1 (ITPR1), which regulates intracellular calcium release fundamental to critical cellular functions including neuronal excitability, neurite outgrowth, neurotransmitter release, mitochondrial energy production and cell fate. In this report we test the hypothesis that Car8 regulation of ITPR1 and cytoplasmic free calcium release is critical to nociception and pain behaviors. We show Car8 null mutant mice (MT) exhibit mechanical allodynia and thermal hyperalgesia. Dorsal root ganglia (DRG) from MT also demonstrate increased steady-state ITPR1 phosphorylation (pITPR1) and cytoplasmic free calcium release. Overexpression of Car8 wildtype protein in MT nociceptors complements Car8 deficiency, down regulates pITPR1 and abolishes thermal and mechanical hypersensitivity. We also show that Car8 nociceptor overexpression alleviates chronic inflammatory pain. Finally, inflammation results in downregulation of DRG Car8 that is associated with increased pITPR1 expression relative to ITPR1, suggesting a possible mechanism of acute hypersensitivity. Our findings indicate Car8 regulates the ITPR1-cytosolic free calcium pathway that is critical to nociception, inflammatory pain and possibly other neuropathological states. Car8 and ITPR1 represent new therapeutic targets for chronic pain.
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18
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Tadevosyan A, Létourneau M, Folch B, Doucet N, Villeneuve LR, Mamarbachi AM, Pétrin D, Hébert TE, Fournier A, Chatenet D, Allen BG, Nattel S. Photoreleasable ligands to study intracrine angiotensin II signalling. J Physiol 2015; 593:521-39. [PMID: 25433071 DOI: 10.1113/jphysiol.2014.279109] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 11/20/2014] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS The renin-angiotensin system plays a key role in cardiovascular physiology and its overactivation has been implicated in the pathogenesis of several major cardiovascular diseases. There is growing evidence that angiotensin II (Ang-II) may function as an intracellular peptide to activate intracellular/nuclear receptors and their downstream signalling effectors independently of cell surface receptors. Current methods used to study intracrine Ang-II signalling are limited to indirect approaches because of a lack of selective intracellularly-acting probes. Here, we present novel photoreleasable Ang-II analogues used to probe intracellular actions with spatial and temporal precision. The photorelease of intracellular Ang-II causes nuclear and cytosolic calcium mobilization and initiates the de novo synthesis of RNA in cardiac cells, demonstrating the application of the method. ABSTRACT Several lines of evidence suggest that intracellular angiotensin II (Ang-II) contributes to the regulation of cardiac contractility, renal salt reabsorption, vascular tone and metabolism; however, work on intracrine Ang-II signalling has been limited to indirect approaches because of a lack of selective intracellularly-acting probes. Here, we aimed to synthesize and characterize cell-permeant Ang-II analogues that are inactive without uncaging, but release active Ang-II upon exposure to a flash of UV-light, and act as novel tools for use in the study of intracrine Ang-II physiology. We prepared three novel caged Ang-II analogues, [Tyr(DMNB)(4)]Ang-II, Ang-II-ODMNB and [Tyr(DMNB)(4)]Ang-II-ODMNB, based upon the incorporation of the photolabile moiety 4,5-dimethoxy-2-nitrobenzyl (DMNB). Compared to Ang-II, the caged Ang-II analogues showed 2-3 orders of magnitude reduced affinity toward both angiotensin type-1 (AT1R) and type-2 (AT2R) receptors in competition binding assays, and greatly-reduced potency in contraction assays of rat thoracic aorta. After receiving UV-irradiation, all three caged Ang-II analogues released Ang-II and potently induced the contraction of rat thoracic aorta. [Tyr(DMNB)(4)]Ang-II showed the most rapid photolysis upon UV-irradiation and was the focus of subsequent characterization. Whereas Ang-II and photolysed [Tyr(DMNB)(4)]Ang-II increased ERK1/2 phosphorylation (via AT1R) and cGMP production (AT2R), caged [Tyr(DMNB)(4)]Ang-II did not. Cellular uptake of [Tyr(DMNB)(4)]Ang-II was 4-fold greater than that of Ang-II and significantly greater than uptake driven by the positive-control HIV TAT(48-60) peptide. Intracellular photolysis of [Tyr(DMNB)(4)]Ang-II induced an increase in nucleoplasmic Ca(2+) ([Ca(2+)]n), and initiated 18S rRNA and nuclear factor kappa B mRNA synthesis in adult cardiac cells. We conclude that caged Ang-II analogues represent powerful new tools for use in the selective study of intracrine signalling via Ang-II.
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Affiliation(s)
- Artavazd Tadevosyan
- Department of Medicine, Université de Montréal, Montréal, Québec, Canada; Montreal Heart Institute, Montréal, Québec, Canada
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19
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Townsend EA, Zhang Y, Xu C, Wakita R, Emala CW. Active components of ginger potentiate β-agonist-induced relaxation of airway smooth muscle by modulating cytoskeletal regulatory proteins. Am J Respir Cell Mol Biol 2014; 50:115-24. [PMID: 23962082 PMCID: PMC3930933 DOI: 10.1165/rcmb.2013-0133oc] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 07/08/2013] [Indexed: 11/24/2022] Open
Abstract
β-Agonists are the first-line therapy to alleviate asthma symptoms by acutely relaxing the airway. Purified components of ginger relax airway smooth muscle (ASM), but the mechanisms are unclear. By elucidating these mechanisms, we can explore the use of phytotherapeutics in combination with traditional asthma therapies. The objectives of this study were to: (1) determine if 6-gingerol, 8-gingerol, or 6-shogaol potentiate β-agonist-induced ASM relaxation; and (2) define the mechanism(s) of action responsible for this potentiation. Human ASM was contracted in organ baths. Tissues were relaxed dose dependently with β-agonist, isoproterenol, in the presence of vehicle, 6-gingerol, 8-gingerol, or 6-shogaol (100 μM). Primary human ASM cells were used for cellular experiments. Purified phosphodiesterase (PDE) 4D or phospholipase C β enzyme was used to assess inhibitory activity of ginger components using fluorescent assays. A G-LISA assay was used to determine the effects of ginger constituents on Ras homolog gene family member A activation. Significant potentiation of isoproterenol-induced relaxation was observed with each of the ginger constituents. 6-Shogaol showed the largest shift in isoproterenol half-maximal effective concentration. 6-Gingerol, 8-gingerol, or 6-shogaol significantly inhibited PDE4D, whereas 8-gingerol and 6-shogaol also inhibited phospholipase C β activity. 6-Shogaol alone inhibited Ras homolog gene family member A activation. In human ASM cells, these constituents decreased phosphorylation of 17-kD protein kinase C-potentiated inhibitory protein of type 1 protein phosphatase and 8-gingerol decreased myosin light chain phosphorylation. Isolated components of ginger potentiate β-agonist-induced relaxation in human ASM. This potentiation involves PDE4D inhibition and cytoskeletal regulatory proteins. Together with β-agonists, 6-gingerol, 8-gingerol, or 6-shogaol may augment existing asthma therapy, resulting in relief of symptoms through complementary intracellular pathways.
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Affiliation(s)
| | - Yi Zhang
- Department of Anesthesiology, Columbia University, New York, New York; and
| | - Carrie Xu
- Department of Anesthesiology, Columbia University, New York, New York; and
| | - Ryo Wakita
- Department of Anesthesiology, Columbia University, New York, New York; and
- Section of Anesthesiology and Clinical Physiology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Charles W. Emala
- Department of Anesthesiology, Columbia University, New York, New York; and
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20
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Kim K, Lim KM, Shin HJ, Seo DB, Noh JY, Kang S, Chung HY, Shin S, Chung JH, Bae ON. Inhibitory effects of black soybean on platelet activation mediated through its active component of adenosine. Thromb Res 2013; 131:254-61. [PMID: 23332980 DOI: 10.1016/j.thromres.2013.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 11/26/2012] [Accepted: 01/02/2013] [Indexed: 11/17/2022]
Abstract
Owing to the beneficial health effects on human cardiovascular system, soybeans and soy-related products have been a focus of intensive research. Soy isoflavones are known to be primarily responsible for the soy-related biological effects including anti-platelet activity but its in vivo relevancy has not been fully verified. Here we compared the role of adenosine, an active ingredient abundant in black soybean (BB) extract, in the anti-platelet effects of BB, to that of soy isoflavones. At the concentrations existing in BB, isoflavones such as genistein and daidzein could not attenuate collagen-induced platelet aggregation, however, adenosine significantly inhibited platelet aggregation with an equivalent potency to BB, suggesting that adenosine may be the major bioactive component. Consistently, the anti-aggregatory effects of BB disappeared after treatment of adenosine receptor antagonists. The effects of BB are mediated by adenosine through intracellular cAMP and subsequent attenuation of calcium mobilization. Of note, adenosine and BB significantly reduced platelet fibrinogen binding and platelet adhesion, other critical events for platelet activation, which were not affected by isoflavones. Taken together, we demonstrated that adenosine might be the major active ingredient for BB-induced anti-platelet activity, which will shed new light on the roles of adenosine as a bioactive compound in soybeans and soy-related food.
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Affiliation(s)
- Keunyoung Kim
- College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
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21
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Platelet Transfusion Medicine. Platelets 2013. [DOI: 10.1016/b978-0-12-387837-3.00062-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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22
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Abstract
Ion channels are transmembrane proteins that play ubiquitous roles in cellular homeostasis and activation. In addition to their recognized role in the regulation of ionic permeability and thus membrane potential, some channel proteins possess intrinsic kinase activity, directly interact with integrins or are permeable to molecules up to ≈1000 Da. The small size and anuclear nature of the platelet has often hindered progress in understanding the role of specific ion channels in hemostasis, thrombosis and other platelet-dependent events. However, with the aid of transgenic mice and 'surrogate' patch clamp recordings from primary megakaryocytes, important unique contributions to platelet function have been identified for several classes of ion channel. Examples include ATP-gated P2X1 channels, Orai1 store-operated Ca2+ channels, voltage-gated Kv1.3 channels, AMPA and kainate glutamate receptors and connexin gap junction channels. Furthermore, evidence exists that some ion channels, such as NMDA glutamate receptors, contribute to megakaryocyte development. This review examines the evidence for expression of a range of ion channels in the platelet and its progenitor cell, and highlights the distinct roles that these proteins may play in health and disease.
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Affiliation(s)
- M P Mahaut-Smith
- Department of Cell Physiology & Pharmacology, University of Leicester, Leicester, UK.
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23
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Hsu WL, Tsai MH, Lin MW, Chiu YC, Lu JH, Chang CH, Yu HS, Yoshioka T. Differential effects of arsenic on calcium signaling in primary keratinocytes and malignant (HSC-1) cells. Cell Calcium 2012; 52:161-9. [PMID: 22695135 DOI: 10.1016/j.ceca.2012.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 05/09/2012] [Accepted: 05/10/2012] [Indexed: 01/04/2023]
Abstract
Arsenic is highly toxic to living cells, especially skin, and skin cancer is induced by drinking water containing arsenic. The molecular mechanisms of arsenic-induced cancer, however, are not well understood. To examine the initial processes in the development of arsenic-induced cancer, we analyzed calcium signaling at an early stage of arsenic treatment of human primary cells and compared the effects with those observed with arsenic treatment in carcinoma-derived cells. We found that arsenic inhibited inositol trisphosphate receptor (IP3R) function in the endoplasmic reticulum by inducing phosphorylation, which led to decreased intracellular calcium levels. Blockade of IP3R phosphorylation by the serine/threonine protein kinase Akt inhibitor wortmannin rescued calcium signaling. In contrast, arsenic treatment of cells derived from a carcinoma (human squamous carcinoma; HSC-1) for 1h had no obvious effect. Taken together, these results suggest that arsenic-induced reduction in calcium signaling is one of the initial mechanisms underlying the malignant transformation in the development of skin cancer.
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Affiliation(s)
- W L Hsu
- Graduate Institute of Medicine, School of Medicine, Kaohsiung Medical University, Taiwan
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24
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Platelet Ca(2+) responses coupled to glycoprotein VI and Toll-like receptors persist in the presence of endothelial-derived inhibitors: roles for secondary activation of P2X1 receptors and release from intracellular Ca(2+) stores. Blood 2012; 119:3613-21. [PMID: 22228626 DOI: 10.1182/blood-2011-10-386052] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inhibition of Ca(2+) mobilization by cyclic nucleotides is central to the mechanism whereby endothelial-derived prostacyclin and nitric oxide limit platelet activation in the intact circulation. However, we show that ∼ 50% of the Ca(2+) response after stimulation of glycoprotein VI (GPVI) by collagen, or of Toll-like 2/1 receptors by Pam(3)Cys-Ser-(Lys)(4) (Pam(3)CSK(4)), is resistant to prostacyclin. At low agonist concentrations, the prostacyclin-resistant Ca(2+) response was predominantly because of P2X1 receptors activated by ATP release via a phospholipase-C-coupled secretory pathway requiring both protein kinase C and cytosolic Ca(2+) elevation. At higher agonist concentrations, an additional pathway was observed because of intracellular Ca(2+) release that also depended on activation of phospholipase C and, for TLR 2/1, PI3-kinase. Secondary activation of P2X1-dependent Ca(2+) influx also persisted in the presence of nitric oxide, delivered from spermine NONOate, or increased ectonucleotidase levels (apyrase). Surprisingly, apyrase was more effective than prostacyclin and NO at limiting secondary P2X1 activation. Dilution of platelets reduced the average extracellular ATP level without affecting the percentage contribution of P2X1 receptors to collagen-evoked Ca(2+) responses, indicating a highly efficient activation mechanism by local ATP. In conclusion, platelets possess inhibitor-resistant Ca(2+) mobilization pathways, including P2X1 receptors, that may be particularly important during early thrombotic or immune-dependent platelet activation.
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25
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Tolhurst G, Carter RN, Miller N, Mahaut-Smith MP. Purification of native bone marrow megakaryocytes for studies of gene expression. Methods Mol Biol 2012; 788:259-273. [PMID: 22130713 DOI: 10.1007/978-1-61779-307-3_18] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Megakaryocytes constitute less than 1% of all marrow cells, therefore purification of these giant platelet precursor cells represents a challenge. We describe two methods to ultra-purify mature megakaryocytes from murine marrow for the purpose of extracting RNA suitable for studies of gene expression. In the first approach, unit velocity gradients are used to enrich for megakaryocytes, which are then selected by fluorescence-activated cell sorting based upon size and high surface expression of CD41. In the second method, individual megakaryocytes, identified by their distinct morphology, are extracted using glass suction pipettes. Despite the small numbers of cells that can be isolated via the latter technique, recent studies have demonstrated how this pure population can be used to detect mRNA transcripts encoding ion channels and other proteins in the native megakaryocyte.
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Affiliation(s)
- Gwen Tolhurst
- Department of Clinical Biochemistry, University of Cambridge, Cambridge, UK
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26
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Perez MF, Ford KA, Goussakov I, Stutzmann GE, Hu XT. Repeated cocaine exposure decreases dopamine D₂-like receptor modulation of Ca(2+) homeostasis in rat nucleus accumbens neurons. Synapse 2011; 65:168-80. [PMID: 20665696 DOI: 10.1002/syn.20831] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The nucleus accumbens (NAc) is a limbic structure in the forebrain that plays a critical role in cognitive function and addiction. Dopamine modulates activity of medium spiny neurons (MSNs) in the NAc. Both dopamine D₁-like and D₂-like receptors (including D1R or D(1,5)R and D2R or D(2,3,4)R, respectively) are thought to play critical roles in cocaine addiction. Our previous studies demonstrated that repeated cocaine exposure (which alters dopamine transmission) decreases excitability of NAc MSNs in cocaine-sensitized, withdrawn rats. This decrease is characterized by a reduction in voltage-sensitive Na(+) currents and high voltage-activated Ca(2+) currents, along with increased voltage-gated K(+) currents. These changes are associated with enhanced activity in the D1R/cAMP/PKA/protein phosphatase 1 pathway and diminished calcineurin function. Although D1R-mediated signaling is enhanced by repeated cocaine exposure, little is known whether and how the D2R is implicated in the cocaine-induced NAc dysfunction. Here, we performed a combined electrophysiological, biochemical, and neuroimaging study that reveals the cocaine-induced dysregulation of Ca(2+) homeostasis with involvement of D2R. Our novel findings reveal that D2R stimulation reduced Ca(2+) influx preferentially via the L-type Ca(2+) channels and evoked intracellular Ca(2+) release, likely via inhibiting the cAMP/PKA cascade, in the NAc MSNs of drug-free rats. However, repeated cocaine exposure abolished the D₂R effects on modulating Ca(2+) homeostasis with enhanced PKA activity and led to a decrease in whole-cell Ca(2+) influx. These adaptations, which persisted for 21 days during cocaine abstinence, may contribute to the mechanism of cocaine withdrawal.
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Affiliation(s)
- Mariela F Perez
- IFEC, CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende s/n, Ciudad Universitaria, 5000 Córdoba, Argentina
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27
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Sonic hedgehog signaling is decoded by calcium spike activity in the developing spinal cord. Proc Natl Acad Sci U S A 2011; 108:4482-7. [PMID: 21368195 DOI: 10.1073/pnas.1018217108] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Evolutionarily conserved hedgehog proteins orchestrate the patterning of embryonic tissues, and dysfunctions in their signaling can lead to tumorigenesis. In vertebrates, Sonic hedgehog (Shh) is essential for nervous system development, but the mechanisms underlying its action remain unclear. Early electrical activity is another developmental cue important for proliferation, migration, and differentiation of neurons. Here we demonstrate the interplay between Shh signaling and Ca(2+) dynamics in the developing spinal cord. Ca(2+) imaging of embryonic spinal cells shows that Shh acutely increases Ca(2+) spike activity through activation of the Shh coreceptor Smoothened (Smo) in neurons. Smo recruits a heterotrimeric GTP-binding protein-dependent pathway and engages both intracellular Ca(2+) stores and Ca(2+) influx. The dynamics of this signaling are manifested in synchronous Ca(2+) spikes and inositol triphosphate transients apparent at the neuronal primary cilium. Interaction of Shh and electrical activity modulates neurotransmitter phenotype expression in spinal neurons. These results indicate that electrical activity and second-messenger signaling mediate Shh action in embryonic spinal neurons.
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Abstract
Genetic and environmental factors contribute to a substantial variation in platelet function seen among normal persons. Candidate gene association studies represent a valiant effort to define the genetic component in an era where genetic tools were limited, but the single nucleotide polymorphisms identified in those studies need to be validated by more objective, comprehensive approaches, such as genome-wide association studies (GWASs) of quantitative functional traits in much larger cohorts of more carefully selected normal subjects. During the past year, platelet count and mean platelet volume, which indirectly affect platelet function, were the subjects of GWAS. The majority of the GWAS signals were located to noncoding regions, a consistent outcome of all GWAS to date, suggesting a major role for mechanisms that alter phenotype at the level of transcription or posttranscriptional modifications. Of 15 quantitative trait loci associated with mean platelet volume and platelet count, one located at 12q24 is also a risk locus for coronary artery disease. In most cases, the effect sizes of individual quantitative trait loci are admittedly small, but the results of these studies have led to new insight into regulators of hematopoiesis and megakaryopoiesis that would otherwise be unapparent and difficult to define.
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Yule DI, Betzenhauser MJ, Joseph SK. Linking structure to function: Recent lessons from inositol 1,4,5-trisphosphate receptor mutagenesis. Cell Calcium 2010; 47:469-79. [PMID: 20510450 DOI: 10.1016/j.ceca.2010.04.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 12/12/2022]
Abstract
Great insight has been gained into the structure and function of the inositol 1,4,5 trisphosphate receptor (InsP(3)R) by studies employing mutagenesis of the cDNA encoding the receptor. Notably, early studies using this approach defined the key constituents required for InsP(3) binding in the N-terminus and the membrane spanning regions in the C-terminal domain responsible for channel formation, targeting and function. In this article we evaluate recent studies which have used a similar approach to investigate key residues underlying the in vivo modulation by select regulatory factors. In addition, we review studies defining the structural requirements in the channel domain which comprise the conduction pathway and are suggested to be involved in the gating of the channel.
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Affiliation(s)
- David I Yule
- Department of Pharmacology and Physiology, University of Rochester, NY, United States.
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30
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Abstract
Agonist-induced elevation in cytosolic Ca2+ concentrations is essential for platelet activation in hemostasis and thrombosis. It occurs through Ca2+ release from intracellular stores and Ca2+ entry through the plasma membrane (PM). Ca2+ store release is a well-established process involving phospholipase (PL)C-mediated production of inositol-1,4,5-trisphosphate (IP3), which in turn releases Ca2+ from the intracellular stores through IP3 receptor channels. In contrast, the mechanisms controlling Ca2+ entry and the significance of this process for platelet activation have been elucidated only very recently. In platelets, as in other non-excitable cells, the major way of Ca2+ entry involves the agonist-induced release of cytosolic sequestered Ca2+ followed by Ca2+ influx through the PM, a process referred to as store-operated calcium entry (SOCE). It is now clear that stromal interaction molecule 1 (STIM1), a Ca2+ sensor molecule in intracellular stores, and the four transmembrane channel protein Orai1 are the key players in platelet SOCE. The other major Ca2+ entry mechanism is mediated by the direct receptor-operated calcium (ROC) channel, P2X1. Besides these, canonical transient receptor potential channel (TRPC) 6 mediates Ca2+ entry through the PM. This review summarizes the current knowledge of platelet Ca2+ homeostasis with a focus on the newly identified Ca2+ entry mechanisms.
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Affiliation(s)
- D Varga-Szabo
- Chair of Vascular Medicine and Rudolf Virchow Center, DFG Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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31
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Inhibitory effects of oligopeptides from hen egg white on both human platelet aggregation and blood coagulation. Arch Pharm Res 2009; 32:945-53. [PMID: 19557374 DOI: 10.1007/s12272-009-1618-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/21/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
Abstract
Egg white proteins have many biological functions and substantial nutritional benefits when used as a food source; however, they also contain allergens such as ovalbumin, ovomucoid, and ovotransferrin. We prepared oligopeptides without allergens from hen egg whites via the use of several proteases, and assessed their effects on platelet aggregation and blood coagulation, known to both of which are known to be major risk factors in thrombogenesis. Egg white oligopeptides (EWOP) inhibited collagen-induced human platelet aggregation in a dose-dependent manner. Additionally, we attempted to determine whether cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), aggregation-inhibiting intracellular molecules, regulate EWOP-inhibited platelet aggregation. EWOP caused an increase in cAMP levels, but did not affect cGMP levels, which suggests that the anti-platelet activity of EWOP operates in a cAMP-dependent manner, rather than via a cGMP-dependent process, in collagen-induced platelet aggregation. In addition, EWOP induced a significantly prolonged prothrombin time (PT) as compared with the controls. These data show that EWOP inhibits the conversion of fibrinogen to fibrin in a plasmatic atmosphere on an extrinsic pathway. Accordingly, these findings suggest that EWOP may be an excellent candidate as a crucial inhibitor of platelet activation, and its anti-platelet effects appear to involve the inhibition of both platelet aggregation and blood coagulation within the cardiovascular system.
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32
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Kwan HY, Huang Y, Yao XQ, Leung FP. Role of cyclic nucleotides in the control of cytosolic Ca2+ levels in vascular endothelial cells. Clin Exp Pharmacol Physiol 2009; 36:857-66. [PMID: 19413591 DOI: 10.1111/j.1440-1681.2009.05199.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
1. Endothelial cells have a key role in the cardiovascular system. Most endothelial cell functions depend on changes in cytosolic Ca(2+) concentrations ([Ca(2+)](i)) to some extent and Ca2+ signalling acts to link external stimuli with the synthesis and release of regulatory factors in endothelial cells. The [Ca(2+)](i) is maintained by a well-balanced Ca(2+) flux across the endoplasmic reticulum and plasma membrane. 2. Cyclic nucleotides, such as cAMP and cGMP, are very important second messengers. The cyclic nucleotides can affect [Ca(2+)](i) directly or indirectly (via the actions of protein kinase (PK) A or PKG-mediated phosphorylation) by regulating Ca(2+) mobilization and Ca(2+) influx. Fine-tuning of [Ca(2+)](i) is also fundamental to protect endothelial cells against damaged caused by the excessive accumulation of Ca(2+). 3. Therapeutic agents that control cAMP and cGMP levels have been used to treat various cardiovascular diseases. 4. The aim of the present review is to discuss: (i) the functions of endothelial cells; (ii) the importance of [Ca(2+)](i) in endothelial cells; (iii) the impact of excessive [Ca(2+)](i) in endothelial cells; and (iv) the balanced control of [Ca(2+)](i) in endothelial cells via involvement of cyclic nucleotides (cAMP and cGMP) and their general effectors.
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Affiliation(s)
- H Y Kwan
- School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong, China
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33
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A novel variant on chromosome 7q22.3 associated with mean platelet volume, counts, and function. Blood 2009; 113:3831-7. [PMID: 19221038 DOI: 10.1182/blood-2008-10-184234] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mean platelet volume (MPV) and platelet count (PLT) are highly heritable and tightly regulated traits. We performed a genome-wide association study for MPV and identified one SNP, rs342293, as having highly significant and reproducible association with MPV (per-G allele effect 0.016 +/- 0.001 log fL; P < 1.08 x 10(-24)) and PLT (per-G effect -4.55 +/- 0.80 10(9)/L; P < 7.19 x 10(-8)) in 8586 healthy subjects. Whole-genome expression analysis in the 1-MB region showed a significant association with platelet transcript levels for PIK3CG (n = 35; P = .047). The G allele at rs342293 was also associated with decreased binding of annexin V to platelets activated with collagen-related peptide (n = 84; P = .003). The region 7q22.3 identifies the first QTL influencing platelet volume, counts, and function in healthy subjects. Notably, the association signal maps to a chromosome region implicated in myeloid malignancies, indicating this site as an important regulatory site for hematopoiesis. The identification of loci regulating MPV by this and other studies will increase our insight in the processes of megakaryopoiesis and proplatelet formation, and it may aid the identification of genes that are somatically mutated in essential thrombocytosis.
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Magnone M, Basile G, Bruzzese D, Guida L, Signorello MG, Chothi MP, Bruzzone S, Millo E, Qi AD, Nicholas RA, Kassack MU, Leoncini G, Zocchi E. Adenylic dinucleotides produced by CD38 are negative endogenous modulators of platelet aggregation. J Biol Chem 2008; 283:24460-8. [PMID: 18606819 DOI: 10.1074/jbc.m710568200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Diadenosine 5',5'''-P1,P2-diphosphate (Ap2A) is one of the adenylic dinucleotides stored in platelet granules. Along with proaggregant ADP, it is released upon platelet activation and is known to stimulate myocyte proliferation. We have previously demonstrated synthesis of Ap2A and of two isomers thereof, called P18 and P24, from their high pressure liquid chromatography retention time, by the ADP-ribosyl cyclase CD38 in mammalian cells. Here we show that Ap2A and its isomers are present in resting human platelets and are released during thrombin-induced platelet activation. The three adenylic dinucleotides were identified by high pressure liquid chromatography through a comparison with the retention times and the absorption spectra of purified standards. Ap2A, P18, and P24 had no direct effect on platelet aggregation, but they inhibited platelet aggregation induced by physiological agonists (thrombin, ADP, and collagen), with mean IC50 values ranging between 5 and 15 microm. Moreover, the three dinucleotides did not modify the intracellular calcium concentration in resting platelets, whereas they significantly reduced the thrombin-induced intracellular calcium increase. Through binding to the purinergic receptor P2Y11, exogenously applied Ap2A, P18, and P24 increased the intracellular cAMP concentration and stimulated platelet production of nitric oxide, the most important endogenous antiaggregant. The presence of Ap2A, P18, and P24 in resting platelets and their release during thrombin-induced platelet activation at concentrations equal to or higher than the respective IC50 value on platelet aggregation suggest a role of these dinucleotides as endogenous negative modulators of aggregation.
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Affiliation(s)
- Mirko Magnone
- Department of Experimental Medicine, Section of Biochemistry and Center of Excellence for Biomedical Research, University of Genova, Viale Benedetto XV, 1 16132 Genova, Italy
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Schmidt R, Baumann O, Walz B. cAMP potentiates InsP3-induced Ca2+ release from the endoplasmic reticulum in blowfly salivary glands. BMC PHYSIOLOGY 2008; 8:10. [PMID: 18492257 PMCID: PMC2408587 DOI: 10.1186/1472-6793-8-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 05/20/2008] [Indexed: 01/09/2023]
Abstract
Background Serotonin induces fluid secretion from Calliphora salivary glands by the parallel activation of the InsP3/Ca2+ and cAMP signaling pathways. We investigated whether cAMP affects 5-HT-induced Ca2+ signaling and InsP3-induced Ca2+ release from the endoplasmic reticulum (ER). Results Increasing intracellular cAMP level by bath application of forskolin, IBMX or cAMP in the continuous presence of threshold 5-HT concentrations converted oscillatory [Ca2+]i changes into a sustained increase. Intraluminal Ca2+ measurements in the ER of β-escin-permeabilized glands with mag-fura-2 revealed that cAMP augmented InsP3-induced Ca2+ release in a concentration-dependent manner. This indicated that cAMP sensitized the InsP3 receptor Ca2+ channel for InsP3. By using cAMP analogs that activated either protein kinase A (PKA) or Epac and the application of PKA-inhibitors, we found that cAMP-induced augmentation of InsP3-induced Ca2+ release was mediated by PKA not by Epac. Recordings of the transepithelial potential of the glands suggested that cAMP sensitized the InsP3/Ca2+ signaling pathway for 5-HT, because IBMX potentiated Ca2+-dependent Cl- transport activated by a threshold 5-HT concentration. Conclusion This report shows, for the first time for an insect system, that cAMP can potentiate InsP3-induced Ca2+ release from the ER in a PKA-dependent manner, and that this crosstalk between cAMP and InsP3/Ca2+ signaling pathways enhances transepithelial electrolyte transport.
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Affiliation(s)
- Ruth Schmidt
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str, 24-25, 14476 Potsdam-Golm, Germany.
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36
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Platelet Storage and Transfusion. Platelets 2007. [DOI: 10.1016/b978-012369367-9/50831-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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37
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Antl M, von Brühl ML, Eiglsperger C, Werner M, Konrad I, Kocher T, Wilm M, Hofmann F, Massberg S, Schlossmann J. IRAG mediates NO/cGMP-dependent inhibition of platelet aggregation and thrombus formation. Blood 2006; 109:552-9. [PMID: 16990611 DOI: 10.1182/blood-2005-10-026294] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Defective regulation of platelet activation/aggregation is a predominant cause for arterial thrombosis, the major complication of atherosclerosis triggering myocardial infarction and stroke. A central regulatory pathway conveying inhibition of platelet activation/aggregation is nitric oxide (NO)/cyclic GMP (cGMP) signaling by cGMP-dependent protein kinase I (cGKI). However, the regulatory cascade downstream of cGKI mediating platelet inhibition is still unclear. Here, we show that the inositol-1,4,5-trisphosphate receptor-associated cGMP kinase substrate (IRAG) is abundantly expressed in platelets and assembled in a macrocomplex together with cGKIbeta and the inositol-1,4,5-trisphosphate receptor type I (InsP3RI). cGKI phosphorylates IRAG at Ser664 and Ser677 in intact platelets. Targeted deletion of the IRAG-InsP3RI interaction in IRAGDelta12/Delta12 mutant mice leads to a loss of NO/cGMP-dependent inhibition of fibrinogen-receptor activation and platelet aggregation. Intracellular calcium transients were not affected by DEA/NO or cGMP in mutant platelets. Furthermore, intravital microscopy shows that NO fails to prevent arterial thrombosis of the injured carotid artery in IRAGDelta12/Delta12 mutants. These findings reveal that interaction between IRAG and InsP3RI has a central role in NO/cGMP-dependent inhibition of platelet aggregation and in vivo thrombosis.
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Affiliation(s)
- Melanie Antl
- Institut für Pharmakologie und Toxikologie der Technischen Universität München, Germany
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38
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Paradkar PN, Roth JA. Nitric oxide transcriptionally down-regulates specific isoforms of divalent metal transporter (DMT1) via NF-?B. J Neurochem 2006; 96:1768-77. [PMID: 16539692 DOI: 10.1111/j.1471-4159.2006.03702.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies were performed to examine the affect of nitric oxide (NO) on expression of the divalent metal transporter (DMT1) in undifferentiated P19 embryonic carcinoma cells. DMT1 has four known isoforms which differ in both the N- and C-terminals. Results demonstrate that exposure of P19 cells to the NO precursor, sodium nitro-prusside (SNP), resulted in a decrease in expression of both positive (+) and negative (-) IRE isoforms of DMT1 with no change in the 1A species. Regulation was not as a result of decreased stability of message but was caused by reduction in transcription of the DMT1 1B isoforms. Similar results were observed in other cell lines, including PC12 and SH-SY5Y cells and rat primary sympathetic neurons. Nuclear NF-kappaB was decreased after SNP treatment, suggesting that NF-kappaB may mediate this response. Luciferase reporter assays with normal and NF-kappaB mutated constructs of the 1B promoter confirm that the NF-kappaB site between -23 to -19 upstream from the transcription start site was responsible for regulating expression. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assays further demonstrate that the p65 subunit of NF-kappaB and not p50 binding is specifically decreased by NO treatment. Results of these studies provide a general mechanism responsible for regulating DMT1 expression induced by stress-related signaling processes in vivo.
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Affiliation(s)
- Prasad N Paradkar
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA
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Bai Y, Sanderson MJ. Airway smooth muscle relaxation results from a reduction in the frequency of Ca2+ oscillations induced by a cAMP-mediated inhibition of the IP3 receptor. Respir Res 2006; 7:34. [PMID: 16504084 PMCID: PMC1459146 DOI: 10.1186/1465-9921-7-34] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 02/23/2006] [Indexed: 01/08/2023] Open
Abstract
Background It has been shown that the contractile state of airway smooth muscle cells (SMCs) in response to agonists is determined by the frequency of Ca2+ oscillations occurring within the SMCs. Therefore, we hypothesized that the relaxation of airway SMCs induced by agents that increase cAMP results from the down-regulation or slowing of the frequency of the Ca2+ oscillations. Methods The effects of isoproterenol (ISO), forskolin (FSK) and 8-bromo-cAMP on the relaxation and Ca2+ signaling of airway SMCs contracted with methacholine (MCh) was investigated in murine lung slices with phase-contrast and laser scanning microscopy. Results All three cAMP-elevating agents simultaneously induced a reduction in the frequency of Ca2+ oscillations within the SMCs and the relaxation of contracted airways. The decrease in the Ca2+ oscillation frequency correlated with the extent of airway relaxation and was concentration-dependent. The mechanism by which cAMP reduced the frequency of the Ca2+ oscillations was investigated. Elevated cAMP did not affect the re-filling rate of the internal Ca2+ stores after emptying by repetitive exposure to 20 mM caffeine. Neither did elevated cAMP limit the Ca2+ available to stimulate contraction because an elevation of intracellular Ca2+ concentration induced by exposure to a Ca2+ ionophore (ionomycin) or by photolysis of caged-Ca2+ did not reverse the effect of cAMP. Similar results were obtained with iberiotoxin, a blocker of Ca2+-activated K+ channels, which would be expected to increase Ca2+ influx and contraction. By contrast, the photolysis of caged-IP3 in the presence of agonist, to further elevate the intracellular IP3 concentration, reversed the slowing of the frequency of the Ca2+ oscillations and relaxation of the airway induced by FSK. This result implied that the sensitivity of the IP3R to IP3 was reduced by FSK and this was supported by the reduced ability of IP3 to release Ca2+ in SMCs in the presence of FSK. Conclusion These results indicate that the relaxant effect of cAMP-elevating agents on airway SMCs is achieved by decreasing the Ca2+ oscillation frequency by reducing internal Ca2+ release through IP3 receptors.
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Affiliation(s)
- Yan Bai
- Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Michael J Sanderson
- Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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40
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Collison DJ, Tovell VE, Coombes LJ, Duncan G, Sanderson J. Potentiation of ATP-induced Ca2+ mobilisation in human retinal pigment epithelial cells. Exp Eye Res 2005; 80:465-75. [PMID: 15781274 DOI: 10.1016/j.exer.2004.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Accepted: 09/21/2004] [Indexed: 11/17/2022]
Abstract
Interaction of signalling pathways directs the functional output of many cells. This study investigated the consequences of activating adenosine and adrenergic receptors on ATP-induced Ca2+ responses in human retinal pigment epithelial (RPE) cells. Intracellular Ca2+ concentration ([Ca2+]i) of human RPE cells in primary culture was monitored using Fura-2. Cyclic adenosine monophosphate (cAMP) concentration was measured using an enzyme-linked immunosorbent assay. Both ATP and UTP (10 microM) increased [Ca2+]i in human RPE cells. Adenosine (10 nM-10 microM) had no effect on resting [Ca2+]i, but potentiated a sub-threshold response to ATP (100 nM) when ATP was added in the presence of adenosine. The potentiation occurred with other G-protein receptor agonists such as acetylcholine. Potentiation persisted in Ca-free medium, but was blocked by prior application of thapsigargin. The A1 and A2 adenosine receptor antagonists, DPCPX and MRS1706 (100 nM) respectively, inhibited potentiation in 76+/-7 and 23+/-12% of cells, respectively, but the A3 antagonist MRS1191 had no effect. Conversely, agents that activate the cAMP pathway, including isoproterenol (10 microM), forskolin (10 microM), and the protein kinase A (PKA) activator Sp-cBIMPS (1 microM), potentiated the ATP-induced response in the RPE cells. Agents that are known to inhibit the production of cAMP in other systems also caused potentiation, including clonidine (10 microM) and the Gi-activator mastoparan (10 microM). Under resting conditions, cAMP concentration in RPE cells was 7.1+/-0.5 pmol mg(-1) protein. Isoproterenol (10 microM) and forskolin (10 microM) increased levels to 104.6+/-5.2 and 113.7+/-4.2 pmol mg(-1) protein, respectively, while adenosine, clonidine, and mastoparan (all 10 microM) had no significant effect on cAMP levels. These data indicate that whilst activation of A1 and A2 adenosine receptors and alpha2 and beta adrenergic receptors does not influence basal Ca2+ levels, stimulation of these receptors can potentiate Ca2+ signalling by cAMP dependent and independent mechanisms in human RPE cells.
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Affiliation(s)
- David J Collison
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
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Hu XT, Ford K, White FJ. Repeated cocaine administration decreases calcineurin (PP2B) but enhances DARPP-32 modulation of sodium currents in rat nucleus accumbens neurons. Neuropsychopharmacology 2005; 30:916-26. [PMID: 15726118 DOI: 10.1038/sj.npp.1300654] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our previous studies have demonstrated that repeated cocaine (COC) administration reduces voltage-sensitive sodium and calcium currents (I(Na) or VSSCs and I(Ca) or VSCCs, respectively) in medium spiny nucleus accumbens (NAc) neurons of rats. The present findings further indicate that chronic COC-induced I(Na) reduction in NAc neurons is regulated by decreased dephosphorylation and enhanced phosphorylation of Na(+) channels. Whole-cell voltage-clamp recordings revealed that dephosphorylation of Na(+) channels by calcineurin (CaN) enhanced I(Na), while inhibition of protein phosphatase 1 (PP1) by phosphorylated dopamine- and cAMP-regulated phosphoprotein (M(r)=32 kDa) (DARPP-32) at the site of threonine 34 (p-Thr.34-DARPP-32) suppressed I(Na), in freshly dissociated NAc neurons of saline-pretreated rats. However, the effects of CaN on enhancing I(Na) were significantly attenuated, and the action of p-Thr.34-DARPP-32 to decrease I(Na) was mimicked, although not potentiated, by repeated COC pretreatment. Dephosphorylation of Na(+) channels by PP1 also enhanced I(Na), but this effect of PP1 on I(Na) was not apparently affected by repeated COC administration. Western blot analysis indicates that the protein levels of CaN and DARPP-32 were significantly decreased and increased, respectively, while the PP1 levels were unchanged, in the COC-withdrawn NAc as compared to saline-pretreated controls. Combined with previous findings, our results indicate that both CaN and PP1 modulate the increase in I(Na) via enhancing dephosphorylation, while p-Thr.34-DARPP-32 reduces I(Na) by inhibiting PP1-induced dephosphorylation, thereby stabilizing the phosphorylation state, of Na(+) channels in NAc neurons. They also suggest that chronic COC-induced I(Na) reduction may be attributed to a reduction in Ca(2+) signaling, which disrupts the physiological balance of phosphorylation and dephosphorylation of Na(+) channels.
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Affiliation(s)
- Xiu-Ti Hu
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
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Zielinski CE, Jacob SN, Bouzahzah F, Ehrlich BE, Craft J. Naive CD4+ T Cells from Lupus-Prone Fas-Intact MRL Mice Display TCR-Mediated Hyperproliferation Due to Intrinsic Threshold Defects in Activation. THE JOURNAL OF IMMUNOLOGY 2005; 174:5100-9. [PMID: 15814741 DOI: 10.4049/jimmunol.174.8.5100] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Autoreactive T cell activation is a consistent feature of murine lupus; however, the mechanism of such activation remains unclear. We hypothesized that naive CD4+ T cells in lupus have a lower threshold of activation through their TCR-CD3 complex that renders them more susceptible to stimulation with self-Ags. To test this hypothesis, we compared proliferation, IL-2 production, and single cell calcium signaling of naive CD4+ T cells isolated from Fas-intact MRL/+(Fas-lpr) mice with H-2k-matched B10.BR and CBA/CaJ controls, following anti-CD3 stimulation in the presence or absence of anti-CD28. We also assessed the responsiveness of naive CD4+ T cells isolated from Fas-intact MRL and control mice bearing a rearranged TCR specific for amino acids 88-104 of pigeon cytochrome c to cognate and low affinity peptide Ags presented by bone marrow-matured dendritic cells. TCR transgenic and wild-type CD4+ T cells from MRL mice displayed a lower threshold of activation than control cells, a response that was class II MHC dependent. The rise in intracellular calcium in MRL vs controls was enhanced and prolonged following anti-CD3 triggering, suggestive of proximal defects in TCR-engendered signaling as the mechanism for the observed hyperactivity. These findings were observed as early as 1-2 mo postweaning and, based on analysis of F1 T cells, appeared to be dominantly expressed. This genetically altered threshold for activation of MRL T cells, a consequence of a proximal defect in CD3-mediated signal transduction, may contribute to the abrogation of T cell tolerance to self-Ags in lupus.
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MESH Headings
- Animals
- Antigen Presentation
- Autoimmunity/genetics
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/pathology
- Calcium Signaling
- Cell Proliferation
- Columbidae
- Cytochromes c/chemistry
- Cytochromes c/immunology
- Dendritic Cells/immunology
- Dendritic Cells/pathology
- Genes, Dominant
- Interleukin-2/biosynthesis
- Lupus Erythematosus, Systemic/genetics
- Lupus Erythematosus, Systemic/immunology
- Lupus Erythematosus, Systemic/metabolism
- Lupus Erythematosus, Systemic/pathology
- Lymphocyte Activation
- Mice
- Mice, Inbred MRL lpr
- Mice, Inbred Strains
- Mice, Knockout
- Mice, Transgenic
- Phenotype
- Receptor-CD3 Complex, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- fas Receptor/metabolism
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Affiliation(s)
- Christina E Zielinski
- Section of Rheumatology, Department of Medicine, Yale University School of Medicine, New Haven, CT 06520-8031, USA
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43
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Nakamura E, Hashimoto A, Kito Y, Hashitani H, Mori T, Suzuki H. Inhibitory actions of cilostazol on electrical responses of smooth muscle isolated from the guinea-pig stomach antrum. J Smooth Muscle Res 2005; 40:111-24. [PMID: 15353865 DOI: 10.1540/jsmr.40.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have investigated the effects of cilostazol, a type III phosphodiesterase inhibitor, on the electrical responses of smooth muscle tissue isolated from the guinea-pig stomach antrum. Cilostazol (10(-5) M) inhibited slow waves recorded from circular muscle cells, but did not significantly alter the pacemaker potentials and follower potentials recorded from myenteric interstitial cells and longitudinal muscle cells respectively. Slow potentials generated in isolated circular muscle bundles without attached myenteric interstitial cells were inhibited by cilostazol (>10(-7) M), while all membrane activities were abolished by 10(-5) M cilostazol. In circular muscle bundles, the input resistance of smooth muscle cells and the refractory period for the generation of slow potentials were not altered during the inhibition of spontaneous activity with cilostazol. While cilostazol at 10(-7) and 10(-6) M did not elevate the tissue content of cyclic AMP, at 10(-5) M cyclic AMP was elevated by about 30%. A similar elevation was also produced by 10(-7) M forskolin. The content of cyclic AMP was not significantly increased in preparations stimulated with 10(-3) M caffeine. The potency for inhibiting slow waves was in the order caffeine (10(-3) M) > forskolin (10(-7) M) > cilostazol (10(-5) M). The frequency of slow waves was decreased by caffeine or forskolin but not by cilostazol, while the duration was reduced by caffeine but not by cilostazol or forskolin. Follower potentials were modulated by caffeine and forskolin, but not by cilostazol: the duration was reduced by caffeine, the frequency was reduced by caffeine or forskolin, and the amplitude was not significantly altered by any of them. The results indicate that cilostazol has high selectivity in inhibiting the activity of circular muscle much more than that of longitudinal muscle or pacemaker cells, with no causal relation to the tissue content of cyclic AMP as appears to be the case for the inhibitory actions of caffeine and forskolin.
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Affiliation(s)
- Eri Nakamura
- Department of Physiology, Nagoya City University Medical School, Mizuho-ku, Nagoya 467-8601, Japan
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Abstract
The platelet surface membrane possesses three P2 receptors activated by extracellular adenosine nucleotides; one member of the ionotropic receptor family (P2X(1)) and two members of the G-protein-coupled receptor family (P2Y(1) and P2Y(12)). P2Y(1) and P2Y(12) receptors have firmly established roles in platelet activation during thrombosis and haemostasis, whereas the importance of the P2X(1) receptor has been more controversial. However, recent studies have demonstrated that P2X(1) receptors can generate significant functional platelet responses alone and in synergy with other receptor pathways. In addition, studies in transgenic animals indicate an important role for P2X(1) receptors in platelet activation, particularly under conditions of shear stress and thus during arterial thrombosis. This review discusses the background behind discovery of P2X(1) receptors in platelets and their precursor cell, the megakaryocyte, and how signalling via these ion channels may participate in platelet activation.
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Affiliation(s)
- Martyn P Mahaut-Smith
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
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Hu XT, Dong Y, Zhang XF, White FJ. Dopamine D2 receptor-activated Ca2+ signaling modulates voltage-sensitive sodium currents in rat nucleus accumbens neurons. J Neurophysiol 2004; 93:1406-17. [PMID: 15590733 DOI: 10.1152/jn.00771.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Receptor-mediated dopamine (DA) modulation of neuronal excitability in the nucleus accumbens (NAc) has been shown to be critically involved in drug addiction and a variety of brain diseases. However, the mechanisms underlying the physiological or pathological molecular process of DA modulation remain largely elusive. Here, we demonstrate that stimulation of DA D2 class receptors (D2R) enhanced voltage-sensitive sodium currents (VSSCs, I(Na)) in freshly dissociated NAc neurons via suppressing tonic activity of the cyclic AMP/PKA cascade and facilitating intracellular Ca2+ signaling. D2R-mediated I(Na) enhancement depended on activation of G(i/o) proteins and was mimicked by direct inhibition of PKA. Furthermore, increasing free [Ca2+]in by activating inositol 1,4,5-triphosphate receptors (IP3Rs), blocking Ca2+ reuptake, or adding buffered Ca2+, all enhanced I(Na). Under these circumstances, D2R-mediated I(Na) enhancement was occluded. In contrast, D2R-mediated I(Na) enhancement was blocked by inhibition of IP3Rs, chelation of free Ca2+, or inhibition of Ca2(+)/calmodulin-activated calcineurin (CaN), but not by inhibition of phospholipase C (PLC). Although stimulation of muscarinic cholinergic receptors (mAChRs) also increased I(Na), this action was blocked by PLC inhibitors. Our findings indicate that D2Rs mediate an enhancement of VSSCs in NAc neurons, in which cytosolic free Ca2+ plays a crucial role. Our results also suggest that D2R-mediated reduction in tonic PKA activity may increase free [Ca2+]in, primarily via disinhibition of IP3Rs. IP3R activation then facilitates Ca2+ signaling and subsequently enhances VSSCs via decreasing PKA-induced phosphorylation and increasing CaN-induced dephosphorylation of Na+ channels. This study provides insight into the complex and dynamic role of D2Rs in the NAc.
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Affiliation(s)
- Xiu-Ti Hu
- Deptartment of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Rd., North Chicago, IL 60064-3095, USA.
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Abstract
An impressive array of cytosolic calcium ([Ca2+](i)) signals exert control over a broad range of physiological processes. The specificity and fidelity of these [Ca2+](i) signals is encoded by the frequency, amplitude, and sub-cellular localization of the response. It is believed that the distinct characteristics of [Ca2+](i) signals underlies the differential activation of effectors and ultimately cellular events. This "shaping" of [Ca2+](i) signals can be achieved by the influence of additional signaling pathways modulating the molecular machinery responsible for generating [Ca2+](i) signals. There is a particularly rich source of potential sites of crosstalk between the cAMP and the [Ca2+](i) signaling pathways. This review will focus on the predominant molecular loci at which these classical signaling systems interact to impact the spatio-temporal pattern of [Ca2+](i) signaling in non-excitable cells.
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Affiliation(s)
- Jason I E Bruce
- Department of Pharmacology & Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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Wagner LE, Li WH, Yule DI. Phosphorylation of type-1 inositol 1,4,5-trisphosphate receptors by cyclic nucleotide-dependent protein kinases: a mutational analysis of the functionally important sites in the S2+ and S2- splice variants. J Biol Chem 2003; 278:45811-7. [PMID: 12939273 DOI: 10.1074/jbc.m306270200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (InsP3R) are the major route of intracellular calcium release in eukaryotic cells and as such are pivotal for stimulation of Ca2+-dependent effectors important for numerous physiological processes. Modulation of this release has important consequences for defining the particular spatio-temporal characteristics of Ca2+ signals. In this study, regulation of Ca2+ release by phosphorylation of type-1 InsP3R (InsP3R-1) by cAMP (PKA)- and cGMP (PKG)-dependent protein kinases was investigated in the two major splice variants of InsP3R-1. InsP3R-1 was expressed in DT-40 cells devoid of endogenous InsP3R. In cells expressing the neuronal, S2+ splice variant of the InsP3R-1, Ca2+ release was markedly enhanced when either PKA or PKG was activated. The sites of phosphorylation were investigated by mutation of serine residues present in two canonical phosphorylation sites present in the protein. Potentiated Ca2+ release was abolished when serine 1755 was mutated to alanine (S1755A) but was unaffected by a similar mutation of serine 1589 (S1589A). These data demonstrate that Ser-1755 is the functionally important residue for phosphoregulation by PKA and PKG in the neuronal variant of the InsP3R-1. Activation of PKA also resulted in potentiated Ca2+ release in cells expressing the non-neuronal, S2- splice variant of the InsP3R-1. However, the PKA-induced potentiation was still evident in S1589A or S1755A InsP3R-1 mutants. The effect was abolished in the double (S1589A/S1755A) mutant, indicating both sites are phosphorylated and contribute to the functional effect. Activation of PKG had no effect on Ca2+ release in cells expressing the S2- variant of InsP3R-1. Collectively, these data indicate that phosphoregulation of InsP3R-1 has dramatic effects on Ca2+ release and defines the molecular sites phosphorylated in the major variants expressed in neuronal and peripheral tissues.
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Affiliation(s)
- Larry E Wagner
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York 14642, USA
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Tanyel FC, Ulusu NN, Tezcan EF, Büyükpamukçu N. Less calcium in cremaster muscles of boys with undescended testis supports a deficiency in sympathetic innervation. Urol Int 2002; 69:111-5. [PMID: 12187040 DOI: 10.1159/000065558] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In addition to an increase in contractility, contracted fibers and small and electron-dense mitochondria have suggested an increase of cytosolic Ca(2+) within the cremaster muscles (CM) associated with undescended testis. Therefore, the Ca(2+) content of CM associated with an undescended testis was determined and compared with the Ca(2+) content associated with inguinal hernia and hydrocele and in internal oblique muscles. CM samples from boys with undescended testis (n = 9), inguinal hernia (n = 15), and hydrocele (n = 7) and from girls with inguinal hernia (n = 8) were obtained. The calcium contents of these samples and of samples from internal oblique muscle (n = 6) were determined by atomic absorption spectrophotometry. While the Ca(2+) contents of CM from boys with undescended testis and from girls with inguinal hernia were similar (p > 0.05), the internal oblique muscle and the CM from boys with inguinal hernia and hydrocele contained more Ca(2+) than CM from boys with undescended testis (p < 0.05). Despite evidence of an increase in cytosolic calcium, the decrease in total calcium content suggests a decrease in the adenylyl cyclase activity, thus inhibition of influx of Ca(2+), but an increase in phospholipase C activity, and generation of more inositol 1,4,5-trisphosphate and mobilization of calcium from internal stores. Since the sympathetic system acts through adenylyl cyclase in striated muscles and is sexually dimorphic, similar Ca(2+) contents as encountered in girls suggest an alteration in the balance of autonomic innervation against the sympathetic system in boys with undescended testis.
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Affiliation(s)
- F Cahit Tanyel
- Department of Pediatric Surgery, Hacettepe University, Faculty of Medicine, Ankara, Turkey.
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DeSouza N, Reiken S, Ondrias K, Yang YM, Matkovich S, Marks AR. Protein kinase A and two phosphatases are components of the inositol 1,4,5-trisphosphate receptor macromolecular signaling complex. J Biol Chem 2002; 277:39397-400. [PMID: 12167631 DOI: 10.1074/jbc.m207059200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The inositol 1,4,5-trisphosphate receptor (IP3R) is a ubiquitously expressed intracellular calcium (Ca(2+)) release channel on the endoplasmic reticulum. IP3Rs play key roles in controlling Ca(2+) signals that activate numerous cellular functions including T cell activation, neurotransmitter release, oocyte fertilization and apoptosis. There are three forms of IP3R, all of which are ligand-gated channels activated by the second messenger inositol 1,4,5-trisphosphate. Channel function is modulated via cross-talk with other signaling pathways including those mediated by kinases and phosphatases. In particular IP3Rs are known to be regulated by cAMP-dependent protein kinase (PKA) phosphorylation. In the present study we show that PKA and the protein phosphatases PP1 and PP2A are components of the IP3R1 macromolecular signaling complex. PKA phosphorylation of IP3R1 increases channel activity in planar lipid bilayers. These studies indicate that regulation of IP3R1 function via PKA phosphorylation involves components of a macromolecular signaling complex.
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Affiliation(s)
- Nikhil DeSouza
- Center for Molecular Cardiology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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50
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den Dekker E, Gorter G, Heemskerk JWM, Akkerman JWN. Development of platelet inhibition by cAMP during megakaryocytopoiesis. J Biol Chem 2002; 277:29321-9. [PMID: 11997386 DOI: 10.1074/jbc.m111390200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prostacyclin is a potent inhibitor of agonist-induced Ca2+ increases in platelets, but in the megakaryocytic cell line MEG-01 this inhibition is absent. Using human megakaryocytic cell lines representing different stages in megakaryocyte (Mk) maturation as well as stem cells and immature and mature megakaryocytes, we show that the inhibition by prostacyclin develops at a late maturation stage shortly before platelets are formed. This late appearance is not caused by insufficient cAMP formation or absent protein kinase A (PKA) activity in immature cells. Instead, the appearance of Ca2+ inhibition by prostacyclin is accompanied by a sharp increase in the expression of the catalytic subunit of PKA (PKA-C) but not by changes in the expression of the PKA-regulatory subunits Ialpha/beta, IIalpha, and IIbeta. Overexpression of PKA-C in the megakaryocytic cell line CHRF-288-11 potentiates the Ca2+ inhibition by prostacyclin. Thus, up-regulation of PKA-C appears to be a key step in the development of Ca2+ inhibition by prostacyclin in platelets.
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Affiliation(s)
- Els den Dekker
- Laboratory for Thrombosis and Haemostasis, Department of Haematology, University Medical Center Utrecht, Utrecht University, 3508 GA Utrecht, The Netherlands
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