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Kotova PD, Dymova EA, Lyamin OO, Rogachevskaja OA, Kolesnikov SS. PI3 kinase inhibitor PI828 uncouples aminergic GPCRs and Ca 2+ mobilization irrespectively of its primary target. Biochim Biophys Acta Gen Subj 2024; 1868:130649. [PMID: 38823731 DOI: 10.1016/j.bbagen.2024.130649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 04/20/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024]
Abstract
The phosphoinositide 3-kinase (PI3K) is involved in regulation of multiple intracellular processes. Although the inhibitory analysis is generally employed for validating a physiological role of PI3K, increasing body of evidence suggests that PI3K inhibitors can exhibit PI3K-unrelated activity as well. Here we studied Ca2+ signaling initiated by aminergic agonists in a variety of different cells and analyzed effects of the PI3K inhibitor PI828 on cell responsiveness. It turned out that PI828 inhibited Ca2+ transients elicited by acetylcholine (ACh), histamine, and serotonin, but did not affect Ca2+ responses to norepinephrine and ATP. Another PI3K inhibitor wortmannin negligibly affected Ca2+ signaling initiated by any one of the tested agonists. Using the genetically encoded PIP3 sensor PH(Akt)-Venus, we confirmed that both PI828 and wortmannin effectively inhibited PI3K and ascertained that this kinase negligibly contributed to ACh transduction. These findings suggested that PI828 inhibited Ca2+ responses to aminergic agonists tested, involving an unknown cellular mechanism unrelated to the PI3K inhibition. Complementary physiological experiments provided evidence that PI828 could inhibit Ca2+ signals induced by certain agonists, by acting extracellularly, presumably, through their surface receptors. For the muscarinic M3 receptor, this possibility was verified with molecular docking and molecular dynamics. As demonstrated with these tools, wortmannin could be bound in the extracellular vestibule at the muscarinic M3 receptor but this did not preclude binding of ACh to the M3 receptor followed by its activation. In contrast, PI828 could sterically block the passage of ACh into the allosteric site, preventing activation of the muscarinic M3 receptor.
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Affiliation(s)
- Polina D Kotova
- Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya Street 3, Pushchino, Russia.
| | - Ekaterina A Dymova
- Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya Street 3, Pushchino, Russia
| | - Oleg O Lyamin
- Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya Street 3, Pushchino, Russia
| | - Olga A Rogachevskaja
- Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya Street 3, Pushchino, Russia
| | - Stanislav S Kolesnikov
- Institute of Cell Biophysics of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Institutskaya Street 3, Pushchino, Russia
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Bai Y, Guedes AGP, Krishnan R, Ai X. CD38 plays an age-related role in cholinergic deregulation of airway smooth muscle contractility. J Allergy Clin Immunol 2022; 149:1643-1654.e8. [PMID: 34800431 PMCID: PMC9081122 DOI: 10.1016/j.jaci.2021.10.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/18/2021] [Accepted: 10/26/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Allergen-induced airway hyperresponsiveness in neonatal mice, but not adult mice, is caused by elevated innervation and consequent cholinergic hyperstimulation of airway smooth muscle (ASM). Whether this inflammation-independent mechanism contributes to ASM hypercontraction in childhood asthma warrants investigation. OBJECTIVE We aimed to establish the functional connection between cholinergic stimulation and ASM contractility in different human age groups. METHODS First, we used a neonatal mouse model of asthma to identify age-related mediators of cholinergic deregulation of ASM contractility. Next, we conducted validation and mechanistic studies in primary human ASM cells and precision-cut lung slices from young (<5 years old) and adult (>20 years old) donor lungs. Finally, we evaluated the therapeutic potential of the identified cholinergic signaling mediators using culture models of human ASM hypercontraction. RESULTS ASM hypercontraction due to cholinergic deregulation in early postnatal life requires CD38. Mechanistically, cholinergic signaling activates the phosphatidylinositol 3-kinase/protein kinase B pathway in immature ASM cells to upregulate CD38 levels, thereby augmenting the Ca2+ response to contractile agonists. Strikingly, this early-life, CD38-mediated ASM hypercontraction is not alleviated by the β-agonist formoterol. CONCLUSIONS The acetylcholine-phosphatidylinositol 3-kinase/protein kinase B-CD38 axis is a critical mechanism of airway hyperresponsiveness in early postnatal life. Targeting this axis may provide a tailored treatment for children at high risk for allergic asthma.
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Affiliation(s)
- Yan Bai
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Mass; Department of Pediatrics, Division of Neonatology and Newborn Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mass.
| | - Alonso G P Guedes
- Department of Veterinary Clinical Science, College of Veterinary Medicine, University of Minnesota, St Paul, Minn
| | - Ramaswamy Krishnan
- Department of Emergency Medicine, Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, Mass
| | - Xingbin Ai
- Department of Pediatrics, Division of Neonatology and Newborn Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Mass.
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Ventura E, Iannuzzi CA, Pentimalli F, Giordano A, Morrione A. RBL1/p107 Expression Levels Are Modulated by Multiple Signaling Pathways. Cancers (Basel) 2021; 13:cancers13195025. [PMID: 34638509 PMCID: PMC8507926 DOI: 10.3390/cancers13195025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 11/16/2022] Open
Abstract
The members of the retinoblastoma (RB) protein family, RB1/p105, retinoblastoma-like (RBL)1/p107 and RBL2/p130 are critical modulators of the cell cycle and their dysregulation has been associated with tumor initiation and progression. The activity of RB proteins is regulated by numerous pathways including oncogenic signaling, but the molecular mechanisms of these functional interactions are not fully defined. We previously demonstrated that RBL2/p130 is a direct target of AKT and it is a key mediator of the apoptotic process induced by AKT inhibition. Here we demonstrated that RBL1/p107 levels are only minorly modulated by the AKT signaling pathway. In contrast, we discovered that RBL1/p107 levels are regulated by multiple pathways linked directly or indirectly to Ca2+-dependent signaling. Inhibition of the multifunctional calcium/calmodulin-dependent kinases (CaMKs) significantly reduced RBL1/p107 expression levels and phosphorylation, increased RBL1/p107 nuclear localization and led to cell cycle arrest in G0/G1. Targeting the Ca2+-dependent endopeptidase calpain stabilized RBL1/p107 levels and counteracted the reduction of RBL1/p107 levels associated with CaMKs inhibition. Thus, these novel observations suggest a complex regulation of RBL1/p107 expression involving different components of signaling pathways controlled by Ca2+ levels, including CaMKs and calpain, pointing out a significant difference with the mechanisms modulating the close family member RBL2/p130.
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Affiliation(s)
- Elisa Ventura
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA; (E.V.); (A.G.)
| | - Carmelina Antonella Iannuzzi
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori, IRCCS, Fondazione G. Pascale, I-80131 Napoli, Italy; (C.A.I.); (F.P.)
| | - Francesca Pentimalli
- Cell Biology and Biotherapy Unit, Istituto Nazionale Tumori, IRCCS, Fondazione G. Pascale, I-80131 Napoli, Italy; (C.A.I.); (F.P.)
| | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA; (E.V.); (A.G.)
- Department of Medical Biotechnologies, University of Siena, I-53100 Siena, Italy
| | - Andrea Morrione
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA 19122, USA; (E.V.); (A.G.)
- Correspondence: ; Tel.: +215-204-2450
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Calcium signaling mediated by aminergic GPCRs is impaired by the PI3K inhibitor LY294002 and its analog LY303511 in a PI3K-independent manner. Eur J Pharmacol 2020; 880:173182. [PMID: 32416185 DOI: 10.1016/j.ejphar.2020.173182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 04/17/2020] [Accepted: 05/08/2020] [Indexed: 12/23/2022]
Abstract
The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (LY294) and its much less active analog LY303511 (LY303) constitute the paired probe that is commonly used to demonstrate the involvement of PI3K in intracellular signaling. We studied effects of LY294 and LY303 on Ca2+ signaling initiated by certain GPCR agonists in cells of several lines, including CHO cells expressing the recombinant serotonin receptor 5-HT2C and mesenchymal stromal cells derived from the human adipose tissue (AD-MSCs) and umbilical cord (UD-MSCs). The LY294/LY303 pair exerted apparently specific effects on responsiveness of AD-MSCs to ATP, suggesting the involvement of PI3K in ATP transduction. Surprisingly, LY303 inhibited Ca2+ transients elicited by histamine in the same cells, while LY294 was ineffective. This observation and other findings implicated a PI3K-unrelated mechanism in mediating effects of the LY compound on AD-MSC responsiveness to histamine. With LY303 in the bath, the dose dependence of histamine responses was shifted positively at the invariable number of responsive cells, as would be the case with a competitive antagonist of histamine receptors. Moreover, LY303 and LY294 inhibited Ca2+ transients elicited by acetylcholine and serotonin in UD-MSCs and CHO/5-HT2C cells, respectively. Our overall results argued for the possibility that LY294 and LY303 could directly affect activity of aminergic GPCRs. Thus, LY303511 and LY294002 should be used cautiously in studies of PI3K as a factor of GPCR signaling.
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Hussain T, Yuan D, Tan B, Murtaza G, Rahu N, Kalhoro MS, Kalhoro DH, Yin Y. Eucommia ulmoides flavones (EUF) abrogated enterocyte damage induced by LPS involved in NF-κB signaling pathway. Toxicol In Vitro 2019; 62:104674. [PMID: 31669396 DOI: 10.1016/j.tiv.2019.104674] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/28/2019] [Accepted: 10/01/2019] [Indexed: 01/22/2023]
Abstract
This study was conducted to explore the regulatory mechanism of Eucommia ulmoides flavones (EUF) using enterocyte damage model induced by lipopolysaccharide (LPS). Intestinal porcine epithelial cell line (IPEC-J2) cells were cultured in Dulbecco's modified eagle medium with high glucose (DMEM-H) medium containing 0 or 10 μg/mL EUF, 0 or 40 ng/mL LPS. The results showed that LPS impaired DNA synthesis, cell viability, mitochondrial function, arrested cell cycle and induced apoptosis, reduced SOD activity while the EUF treated cells provided beneficial effect on all these parameters (P < 0.05). The addition of EUF increased phosphorylated Akt, IκBα and phosphorylated IKKα/β, but decreased Bax and Caspase-3 protein expressions in LPS-treated cells (P < 0.05). For the second experiment, cells were treated by DMEM-H medium containing 10 μg/mL EUF+ 40 ng/mL LPS or 10 μg/mL EUF+ 40 ng/mL LPS+ 10 μmol/L LY29400. EUF + LPS + LY29400 treatment significantly reduced cell viability, proliferation, mitochondrial bioenergetics parameters, SOD activity, and decreased protein expressions of PI3K, p-Akt, p-IKKα/β, p-NFκB and Bax (P < 0.05). These findings revealed the cytoprotective effects of EUF in enterocyte, which may involve the PI3K-NFκB signaling pathway, and it provides a theoretical basis for exploration of EUF as a potential anti-inflammatory compound to intervene intestinal inflammatory diseases.
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Affiliation(s)
- Tarique Hussain
- Laboratory of Animal Nutritional Physiology and Metabolic Processes, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan, China; University of the Chinese Academy of Sciences, Beijing 10008, China; Animal Sciences Division, Nuclear Institute for Agriculture and Biology (NIAB), P.O.Box: 128, Jhang Road, Faisalabad, Pakistan
| | - Diaxiu Yuan
- Department of Medicine, Jishou University, Jishou, Hunan 416000, China.
| | - Bie Tan
- Laboratory of Animal Nutritional Physiology and Metabolic Processes, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan, China; University of the Chinese Academy of Sciences, Beijing 10008, China.
| | - Ghulam Murtaza
- Shaheed Benazir Bhutto University of Veterinary & Animal Sciences, Sakrand, Sindh 67210, Pakistan
| | - Najma Rahu
- Department of Veterinary Microbiology, Faculty of Animal Husbandry and Veterinary Sciences, Sindh Agriculture University, Tandojam, Sindh 70050, Pakistan
| | - Muhammed Saleem Kalhoro
- Department of Veterinary Microbiology, Faculty of Animal Husbandry and Veterinary Sciences, Sindh Agriculture University, Tandojam, Sindh 70050, Pakistan
| | - Dildar Hussain Kalhoro
- Shaheed Benazir Bhutto University of Veterinary & Animal Sciences, Sakrand, Sindh 67210, Pakistan
| | - Yulong Yin
- Laboratory of Animal Nutritional Physiology and Metabolic Processes, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, Hunan, China; University of the Chinese Academy of Sciences, Beijing 10008, China
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Lee TM, Chang NC, Lin SZ. Inhibition of infarction-induced sympathetic innervation with endothelin receptor antagonism via a PI3K/GSK-3β-dependent pathway. J Transl Med 2017; 97:243-255. [PMID: 27991911 DOI: 10.1038/labinvest.2016.138] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 11/09/2022] Open
Abstract
Although endothelin (ET)-1 has been shown to upregulate nerve growth factor (NGF) expression, the molecular mechanisms are largely unknown. Phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase (GSK)-3β signal has been implicated in the regulation of NGF. We investigated whether selective ET receptor blockers attenuated cardiac sympathetic reinnervation through restoring PI3K/Akt/GSK-3β activity. After ligation of the left anterior descending artery, male Wistar rats were randomized to either vehicle, atrasentan (an ETA receptor antagonist) or A-192621 (an ETB receptor antagonist) for 4 weeks. Sympathetic hyperinnervation after infarction was confirmed by myocardial norepinephrine measurement and immunofluorescent analysis. Post infarction was associated with increased reactive oxygen species (ROS), as measured by myocardial superoxide levels and dihydroethidine fluorescence staining. This was paralleled by a significant upregulation of NGF expression on mRNA and protein levels in the vehicle-treated rats, which reduced after administering atrasentan, not A-192621. Arrhythmic scores in the vehicle-treated rats were significantly higher than those treated with atrasentan. In an in vivo study atrasentan-induced decreased NGF was associated with activation of PI3K/Akt signaling pathway, which was further confirmed by the ex vivo study showing the restoration of NGF levels after coadministration of PI3K inhibitors (wortmannin and LY294002). Lithium chloride, an inhibitor of GSK-3β, did not provide additional attenuated NGF levels compared with atrasentan alone. Finally, atrasentan-attenuated NGF levels were reversed in the presence of peroxynitrite generator. ETA receptor antagonism is a mediator to attenuate sympathetic hyperinnervation probably through restoration of PI3K/Akt/GSK-3β/ROS signaling pathway, a potential pharmacological target for arrhythmias after infarction.
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Affiliation(s)
- T-M Lee
- Department of Medicine, Cardiology Section, China Medical University-An Nan Hospital, Tainan, Taiwan.,Department of Medicine, China Medical University, Taichung, Taiwan.,Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Nen-Chung Chang
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Shinn-Zong Lin
- Department of Neurosurgery, Bioinnovation Center, Tzu Chi foundation, Buddhist Tzu Chi General Hospital, Tzu Chi University, Hualien, Taiwan
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Khavandi K, Baylie RA, Sugden SA, Ahmed M, Csato V, Eaton P, Hill-Eubanks DC, Bonev AD, Nelson MT, Greenstein AS. Pressure-induced oxidative activation of PKG enables vasoregulation by Ca2+ sparks and BK channels. Sci Signal 2016; 9:ra100. [PMID: 27729550 DOI: 10.1126/scisignal.aaf6625] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Activation of Ca2+-sensitive, large-conductance potassium (BK) channels in vascular smooth muscle cells (VSMCs) by local, ryanodine receptor-mediated Ca2+ signals (Ca2+ sparks) acts as a brake on pressure-induced (myogenic) vasoconstriction-a fundamental mechanism that regulates blood flow in small resistance arteries. We report that physiological intraluminal pressure within resistance arteries activated cGMP-dependent protein kinase (PKG) in VSMCs through oxidant-induced formation of an intermolecular disulfide bond between cysteine residues. Oxidant-activated PKG was required to trigger Ca2+ sparks, BK channel activity, and vasodilation in response to pressure. VSMCs from arteries from mice expressing a form of PKG that could not be activated by oxidants showed reduced Ca2+ spark frequency, and arterial preparations from these mice had decreased pressure-induced activation of BK channels. Thus, the absence of oxidative activation of PKG disabled the BK channel-mediated negative feedback regulation of vasoconstriction. Our results support the concept of a negative feedback control mechanism that regulates arterial diameter through mechanosensitive production of oxidants to activate PKG and enhance Ca2+ sparks.
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Affiliation(s)
- Kaivan Khavandi
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | - Rachael A Baylie
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Sarah A Sugden
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Majid Ahmed
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Viktoria Csato
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Philip Eaton
- King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | | | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Mark T Nelson
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Adam S Greenstein
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
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Wang H, Zhuang X, Wang X, Law AHY, Zhao T, Du S, Loy MMT, Jiang L. A Distinct Pathway for Polar Exocytosis in Plant Cell Wall Formation. PLANT PHYSIOLOGY 2016; 172:1003-1018. [PMID: 27531442 PMCID: PMC5047090 DOI: 10.1104/pp.16.00754] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/08/2016] [Indexed: 05/02/2023]
Abstract
Post-Golgi protein sorting and trafficking to the plasma membrane (PM) is generally believed to occur via the trans-Golgi network (TGN). In this study using Nicotiana tabacum pectin methylesterase (NtPPME1) as a marker, we have identified a TGN-independent polar exocytosis pathway that mediates cell wall formation during cell expansion and cytokinesis. Confocal immunofluorescence and immunogold electron microscopy studies demonstrated that Golgi-derived secretory vesicles (GDSVs) labeled by NtPPME1-GFP are distinct from those organelles belonging to the conventional post-Golgi exocytosis pathway. In addition, pharmaceutical treatments, superresolution imaging, and dynamic studies suggest that NtPPME1 follows a polar exocytic process from Golgi-GDSV-PM/cell plate (CP), which is distinct from the conventional Golgi-TGN-PM/CP secretion pathway. Further studies show that ROP1 regulates this specific polar exocytic pathway. Taken together, we have demonstrated an alternative TGN-independent Golgi-to-PM polar exocytic route, which mediates secretion of NtPPME1 for cell wall formation during cell expansion and cytokinesis and is ROP1-dependent.
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Affiliation(s)
- Hao Wang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Xiaohong Zhuang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Xiangfeng Wang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Angus Ho Yin Law
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Teng Zhao
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Shengwang Du
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Michael M T Loy
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
| | - Liwen Jiang
- School of Life Sciences, Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China (H.W., X.Z., X.W., A.H.Y.L., L.J.);College of Life Sciences, South China Agricultural University, Guangzhou 510642, China (H.W.);Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (T.Z., S.D., M.M.T.L.);Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China (S.D.); andCUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China (L.J.)
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9
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Autophagy and liver ischemia-reperfusion injury. BIOMED RESEARCH INTERNATIONAL 2015; 2015:417590. [PMID: 25861623 PMCID: PMC4377441 DOI: 10.1155/2015/417590] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/21/2014] [Accepted: 09/07/2014] [Indexed: 12/12/2022]
Abstract
Liver ischemia-reperfusion (I-R) injury occurs during liver resection, liver transplantation, and hemorrhagic shock. The main mode of liver cell death after warm and/or cold liver I-R is necrosis, but other modes of cell death, as apoptosis and autophagy, are also involved. Autophagy is an intracellular self-digesting pathway responsible for removal of long-lived proteins, damaged organelles, and malformed proteins during biosynthesis by lysosomes. Autophagy is found in normal and diseased liver. Although depending on the type of ischemia, warm and/or cold, the dynamic process of liver I-R results mainly in adenosine triphosphate depletion and in production of reactive oxygen species (ROS), leads to both, a local ischemic insult and an acute inflammatory-mediated reperfusion injury, and results finally in cell death. This process can induce liver dysfunction and can increase patient morbidity and mortality after liver surgery and hemorrhagic shock. Whether autophagy protects from or promotes liver injury following warm and/or cold I-R remains to be elucidated. The present review aims to summarize the current knowledge in liver I-R injury focusing on both the beneficial and the detrimental effects of liver autophagy following warm and/or cold liver I-R.
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Garcia-Garcia A, Anandhan A, Burns M, Chen H, Zhou Y, Franco R. Impairment of Atg5-dependent autophagic flux promotes paraquat- and MPP⁺-induced apoptosis but not rotenone or 6-hydroxydopamine toxicity. Toxicol Sci 2013; 136:166-82. [PMID: 23997112 DOI: 10.1093/toxsci/kft188] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Controversial reports on the role of autophagy as a survival or cell death mechanism in dopaminergic cell death induced by parkinsonian toxins exist. We investigated the alterations in autophagic flux and the role of autophagy protein 5 (Atg5)-dependent autophagy in dopaminergic cell death induced by parkinsonian toxins. Dopaminergic cell death induced by the mitochondrial complex I inhibitors 1-methyl-4-phenylpyridinium (MPP⁺) and rotenone, the pesticide paraquat, and the dopamine analog 6-hydroxydopamine (6-OHDA) was paralleled by increased autophagosome accumulation. However, when compared with basal autophagy levels using chloroquine, autophagosome accumulation was a result of impaired autophagic flux. Only 6-OHDA induced an increase in autophagosome formation. Overexpression of a dominant negative form of Atg5 increased paraquat- and MPP⁺-induced cell death. Stimulation of mammalian target of rapamycin (mTOR)-dependent signaling protected against cell death induced by paraquat, whereas MPP⁺-induced toxicity was enhanced by wortmannin, a phosphoinositide 3-kinase class III inhibitor, rapamycin, and trehalose, an mTOR-independent autophagy activator. Modulation of autophagy by either pharmacological or genetic approaches had no effect on rotenone or 6-OHDA toxicity. Cell death induced by parkinsonian neurotoxins was inhibited by the pan caspase inhibitor (Z-VAD), but only caspase-3 inhibition was able to decrease MPP⁺-induced cell death. Finally, inhibition of the lysosomal hydrolases, cathepsins, increased the toxicity by paraquat and MPP⁺, supporting a protective role of Atg5-dependent autophagy and lysosomes degradation pathways on dopaminegic cell death. These results demonstrate that in dopaminergic cells, Atg5-dependent autophagy acts as a protective mechanism during apoptotic cell death induced by paraquat and MPP⁺ but not during rotenone or 6-OHDA toxicity.
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Yang YP, Hu LF, Zheng HF, Mao CJ, Hu WD, Xiong KP, Wang F, Liu CF. Application and interpretation of current autophagy inhibitors and activators. Acta Pharmacol Sin 2013; 34:625-35. [PMID: 23524572 DOI: 10.1038/aps.2013.5] [Citation(s) in RCA: 275] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Autophagy is the major intracellular degradation system, by which cytoplasmic materials are delivered to and degraded in the lysosome. As a quality control mechanism for cytoplasmic proteins and organelles, autophagy plays important roles in a variety of human diseases, including neurodegenerative diseases, cancer, cardiovascular disease, diabetes and infectious and inflammatory diseases. The discovery of ATG genes and the dissection of the signaling pathways involved in regulating autophagy have greatly enriched our knowledge on the occurrence and development of this lysosomal degradation pathway. In addition to its role in degradation, autophagy may also promote a type of programmed cell death that is different from apoptosis, termed type II programmed cell death. Owing to the dual roles of autophagy in cell death and the specificity of diseases, the exact mechanisms of autophagy in various diseases require more investigation. The application of autophagy inhibitors and activators will help us understand the regulation of autophagy in human diseases, and provide insight into the use of autophagy-targeted drugs. In this review, we summarize the latest research on autophagy inhibitors and activators and discuss the possibility of their application in human disease therapy.
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Wang Q, Franks HA, Lax SJ, El Refaee M, Malecka A, Shah S, Spendlove I, Gough MJ, Seedhouse C, Madhusudan S, Patel PM, Jackson AM. The ataxia telangiectasia mutated kinase pathway regulates IL-23 expression by human dendritic cells. THE JOURNAL OF IMMUNOLOGY 2013; 190:3246-55. [PMID: 23460736 DOI: 10.4049/jimmunol.1201484] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Little is known of the regulation of IL-23 secretion in dendritic cells (DC) despite its importance for human Th17 responses. In this study, we show for first time, to our knowledge, that the ataxia telangiectasia mutated (ATM) pathway, involved in DNA damage sensing, acts as an IL-23 repressor. Inhibition of ATM with the highly selective antagonist KU55933 markedly increased IL-23 secretion in human monocyte-derived DC and freshly isolated myeloid DC. In contrast, inhibiting the closely related mammalian target of rapamycin had no effect on IL-23. Priming naive CD4(+) T cells with ATM-inhibited DC increased Th17 responses over and above those obtained with mature DC. Although ATM blockade increased the abundance of p19, p35, and p40 mRNA, IL-12p70 secretion was unaffected. To further examine a role for ATM in IL-23 regulation, we exposed DC to low doses of ionizing radiation. Exposure of DC to x-rays resulted in ATM phosphorylation and a corresponding depression of IL-23. Importantly, ATM inhibition with KU55933 prevented radiation-induced ATM phosphorylation and abrogated the capacity of x-rays to suppress IL-23. To explore how ATM repressed IL-23, we examined a role for endoplasmic reticulum stress responses by measuring generation of the spliced form of X-box protein-1, a key endoplasmic reticulum stress transcription factor. Inhibition of ATM increased the abundance of X-box protein-1 mRNA, and this was followed 3 h later by increased peak p19 transcription and IL-23 release. In summary, ATM activation or inhibition, respectively, inhibited or augmented IL-23 release. This novel role of the ATM pathway represents a new therapeutic target in autoimmunity and vaccine development.
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Affiliation(s)
- Qunwei Wang
- Host:Tumour Interactions Group, Academic Unit of Clinical Oncology, University of Nottingham, Nottingham NG5 1PB, United Kingdom
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Saini-Chohan HK, Hryshko L, Xu YJ, Dhalla NS. Modification of Ca(2+)-handling in cardiomyocytes by redox sensitive mechanisms in response to ouabain. Can J Physiol Pharmacol 2013; 91:45-55. [PMID: 23367872 DOI: 10.1139/cjpp-2012-0215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We examined the role of redox-sensitive signal transduction mechanisms in modifying the changes in [Ca(2+)](i) produced by ouabain upon incubating adult rat cardiomyocytes with antioxidants or inhibitors of different protein kinases and monitoring alterations in fura-2 fluorescence. Ouabain increased basal [Ca(2+)](i), augmented the KCl-induced increase in [Ca(2+)](i), and promoted oxyradical production in cardiomyocytes. These actions of ouabain were attenuated by an oxyradical scavenging mixture (superoxide dismutase plus catalase), and the antioxidants (N-acetyl-L-cysteine and N-(2-mercaptoproprionyl)glycine). An inhibitor of MAP kinase (PD98059) depressed the ouabain-induced increase in [Ca(2+)], whereas inhibitors of tyrosine kinase (tyrphostin and genistein) and PI3 kinase (Wortmannin and LV294002) enhanced the ouabain-induced increase in [Ca(2+)](i). Inhibitors of protein kinase C (calphostin and bisindolylmalaimide) augmented the ouabain-induced increase in [Ca(2+)](i), whereas stimulation of protein kinase C by a phorbol ester (phorbol 12-myristate 13-acetate) depressed the action of ouabain. These results suggest that ouabain-induced inhibition of Na (+)-K(+) ATPase may alter the redox status of cardiomyocytes through the production of oxyradicals, and increase the activities of various protein kinases. Thus, these redox-sensitive signal transduction mechanisms involving different protein kinases may modify Ca(2+)-handling sites in cardiomyocytes and determine the magnitude of net increase in [Ca(2+)](i) in response to ouabain.
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Affiliation(s)
- Harjot K Saini-Chohan
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research and Department of Physiology, Faculty of Medicine, University of Manitoba, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada
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Nauc V, De Lamirande E, Leclerc P, Gagnon C. Inhibitors of Phosphoinositide 3-Kinase, LY294002 and Wortmannin, Affect Sperm Capacitation and Associated Phosphorylation of Proteins Differently: Ca2+-Dependent Divergences. ACTA ACUST UNITED AC 2013; 25:573-85. [PMID: 15223846 DOI: 10.1002/j.1939-4640.2004.tb02828.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Sperm capacitation is regulated by multiple pathways that also control sperm motility and tyrosine (Tyr) phosphorylation of several sperm proteins. Among the reported pathways, phosphoinositide 3-kinase (PI3K) signaling and its role in modulating sperm postejaculatory changes and motility remain elusive. It was shown that wortmannin, a selective inhibitor of PI3K, prevents human sperm acrosome reaction. Using LY294002 (2-(4-morphlinyl)-8-phenyl-4H-1-benzopyran-4-one), another chemically different inhibitor of PI3K, it was suggested that this enzyme inhibits human sperm motility. In this study, we used the 2 known inhibitors of PI3K to investigate their effect on sperm capacitation and associated protein phosphorylation events. Our data show that sperm incubated with LY294002 undergo capacitation and increased Tyr phosphorylation of specific sperm proteins in a manner similar to that promoted by the capacitation inducer fetal cord serum ultrafiltrate (FCSu), as well as double phosphorylation of the threonine (Thr)-glutamine (Glu)-Tyr motif. Under similar conditions, wortmannin did not affect these sperm functions on its own, although it did prevent the effect induced by FCSu. Consistently, wortmannin decreased the phospho (P)-Tyr content of sperm proteins and prevented the phosphorylation of their Thr-Glu-Tyr motif. We also show by means of immunoblotting and cell fractionation experiments the presence of PI3K and its downstream effector Akt (protein kinase B) at the membrane level, as well as sperm heads and flagella. Our data show that human spermatozoa contain a consensus motif usually phosphorylated by Akt and that its P-serine (Ser)/Thr content is increased by both LY294002 and FCSu, while it is decreased by wortmannin. In addition, the 2 inhibitors differently affected the intracellular calcium concentration, [Ca(2+)](i). While LY294002 increased [Ca(2+)](i), wortmannin did not affect its content and did not prevent the LY294002 effect. Thus, we propose that the LY294002-promoted increase in [Ca(2+)](i) operates independently of PI3K. In conclusion, we suggest that special care be taken when using LY294002 to investigate the role that PI3K plays in a cellular phenomenon.
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Affiliation(s)
- Veronica Nauc
- Urology Research Laboratory, Royal Victoria Hospital and McGill University, Montréal, Canada
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15
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Zhao W, Qi J, Wang L, Zhang M, Wang P, Gao C. LY294002 inhibits TLR3/4-mediated IFN-β production via inhibition of IRF3 activation with a PI3K-independent mechanism. FEBS Lett 2012; 586:705-10. [PMID: 22285490 DOI: 10.1016/j.febslet.2012.01.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/06/2012] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
Abstract
TLR3 and TLR4 utilize adaptor TRIF to activate interferon regulatory factor 3 (IRF3), resulting in interferon β (IFN-β) production to mediate anti-viral infection. In this report, we analyzed the effect of two known phosphatidylinositol 3-kinase (PI3K) inhibitors LY294002 and wortmannin on LPS- and poly(I:C)-induced IFN-β production in peritoneal macrophages. LY294002 inhibited LPS- and poly(I:C)-induced IFN-β transcription and secretion. In contrast, wortmannin could not inhibit IFN-β production. Furthermore, IRF3 transcriptional activation and binding to IFN-β promoter were found to be inhibited by LY294002. Therefore, our findings demonstrate LY294002 negatively regulates LPS- and poly(I:C)-induced IFN-β production through inhibition of IRF3 activation in a PI3K-independent manner.
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Affiliation(s)
- Wei Zhao
- Department of Immunology, Shandong University Medical School, Jinan, Shandong 250012, PR China
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16
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Tsai KD, Chang WW, Lin CC, Hsu SC, Lee YJ, Chen W, Shieh JC, Lin TH. Differential effects of LY294002 and wortmannin on inducible nitric oxide synthase expression in glomerular mesangial cells. Int Immunopharmacol 2012; 12:471-80. [PMID: 22240122 DOI: 10.1016/j.intimp.2011.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 11/26/2011] [Accepted: 12/22/2011] [Indexed: 01/07/2023]
Abstract
Nitric oxide (NO) that is produced by inducible nitric oxide synthase (iNOS) is associated with the pathophysiology of glomerulonephritis. Numerous studies have focused on the regulation of NO production by iNOS to reduce NO-mediated cytotoxicity. In the present study, we demonstrated the differential effects of two phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin, on lipopolysaccharide- (LPS) and interferon (IFN)-γ-induced NO production in a glomerular mesangial cell line, MES-13 cells. At dosages without affecting cell viability of MES-13 cells, 5μM LY294002 showed a more-significant inhibitory effect on LPS/IFN-γ-induced NO production, and iNOS protein and gene expressions than did 1μM wortmannin. Akt phosphorylation in MES-13 cells declined upon the addition of wortmannin, but not upon treatment with LY294002. Suppression of PI3K expression by small interfering (si)RNA exhibited no effect on LPS/IFN-γ-stimulated NO production or iNOS protein expression in MES-13 cells. Neither LY294002 nor wortmannin reduced IFN-γ-induced STAT-1α phosphorylation. LY294002 exhibited a more-significant inhibitory effect on NF-κB luciferase activities than wortmannin in LPS/IFN-γ-stimulated MES-13 cells. Moreover, LY294002, but not wortmannin, accelerated iNOS protein degradation and reduced the iNOS dimer/monomer ratio in MES-13 cells. Although both LY294002 and wortmannin are known as PI3K inhibitors, their differential effects on iNOS expression in MES-13 cells indicate that the effects of LY294002 on inhibiting NF-κB activation and accelerating iNOS protein degradation are through a mechanism independent of PI3K.
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Affiliation(s)
- Kuen-Daw Tsai
- Department of Internal Medicine, China Medical University Beigang Hospital, 123 Sinde Road, Beigang Township, Yunlin County 65152, Taiwan, ROC
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Avni D, Glucksam Y, Zor T. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 modulates cytokine expression in macrophages via p50 nuclear factor κB inhibition, in a PI3K-independent mechanism. Biochem Pharmacol 2011; 83:106-14. [PMID: 22005520 DOI: 10.1016/j.bcp.2011.09.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 09/26/2011] [Accepted: 09/28/2011] [Indexed: 02/05/2023]
Abstract
The Phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002 (LY2), has been previously reported to inhibit nuclear factor κB (NFκB) activity, in a PI3K-independent mechanism. The goals of the current research were to determine the specificity of LY2 regarding NFκB subunits, and to identify relevant modulation of cytokine expression in LPS-stimulated macrophages. We found that LY2 specifically diminished the level of p50, but not p65, NFκB in the nucleus of LPS-stimulated mouse RAW264.7 macrophages and human THP-1 monocytes. This activity of LY2 was mimicked by its PI3K-inert analog LY303511 (LY3), but not by another PI3K inhibitor - wortmannin. We further show that LY2 inhibited LPS-induced IL-10 expression by RAW264.7 macrophages, in a PI3K-independent mechanism. Moreover, using a deletion mutant of an IL-10 promoter reporter gene we demonstrate that the activity of the NFκB enhancer site at the IL-10 promoter is regulated by LY2 in a PI3K-independent manner. Finally, both LY2 and LY3 elevated TNFα production in the LPS tolerant state which is regulated by p50 NFκB homodimers, but not before tolerance development. The effects of LY2 and LY3 on p50 translocation and on cytokine production in LPS-stimulated macrophages are thus consistent with specific PI3K-independent inhibition of p50 NFκB homodimer activity by LY2.
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Affiliation(s)
- Dorit Avni
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, Tel-Aviv University, Israel.
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Wang Q, Franks HA, Porte J, El Refaee M, Shah S, Crooks J, Patel PM, Jackson AM. Novel approach for interleukin-23 up-regulation in human dendritic cells and the impact on T helper type 17 generation. Immunology 2011; 134:60-72. [PMID: 21718315 DOI: 10.1111/j.1365-2567.2011.03467.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Interleukin-23 (IL-23) is important for T helper type 17 (Th17) responses and strategies to regulate IL-23 in human dendritic cells (DC) are limited. This study describes a novel means to control IL-23 secretion by conditioning DC with a phosphatidyl inositol 3-kinase inhibitor Wortmannin (WM). Treatment of monocyte-derived DC with WM increased Toll-like receptor (TLR) -dependent IL-23 secretion 10-fold and IL-12p70 twofold, but IL-27 was unaffected. The effect of WM was restricted to TLR3/4 pathways, did not occur through TLR2, TLR7/8 or Dectin-1, and was characterized by increased p19, p35 and p40 transcription. These responses were not solely dependent on phosphatidyl inositol 3-kinase as the alternative inhibitor LY294002 did not modulate IL-23 production. The normal patterns of activation of mitogen-activated protein kinase pathways were unaffected by WM-conditioning but IL-23 secretion required p38, ERK and JNK pathways. Importantly, this effect was manifest in populations of blood DC. Conditioning freshly isolated myeloid DC with WM before TLR3 or TLR4 triggering resulted in high levels of IL-23 secretion and an absence of IL-12p70. These WM-conditioned myeloid DC were highly effective at priming Th17 responses from naive CD4(+) T cells. Our findings provide a novel means to generate IL-23-rich environments and Th17 responses and suggest as yet unidentified regulatory factors, identification of which will provide new approaches to control IL-23-dependent immunity in infectious disease, autoimmunity and malignancy.
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Affiliation(s)
- Qunwei Wang
- Academic Unit of Clinical Oncology, University of Nottingham, Nottingham, UK
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Bodenstine TM, Vaidya KS, Ismail A, Beck BH, Cook LM, Diers AR, Landar A, Welch DR. Homotypic gap junctional communication associated with metastasis suppression increases with PKA activity and is unaffected by PI3K inhibition. Cancer Res 2010; 70:10002-11. [PMID: 21098703 DOI: 10.1158/0008-5472.can-10-2606] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Loss of gap junctional intercellular communication (GJIC) between cancer cells is a common characteristic of malignant transformation. This communication is mediated by connexin proteins that make up the functional units of gap junctions. Connexins are highly regulated at the protein level and phosphorylation events play a key role in their trafficking and degradation. The metastasis suppressor breast cancer metastasis suppressor 1 (BRMS1) upregulates GJIC and decreases phosphoinositide-3-kinase (PI3K) signaling. On the basis of these observations, we set out to determine whether there was a link between PI3K and GJIC in tumorigenic and metastatic cell lines. Treatment of cells with the well-known PI3K inhibitor LY294002, and its structural analogue LY303511, which does not inhibit PI3K, increased homotypic GJIC; however, we found the effect to be independent of PI3K/AKT inhibition. We show in multiple cancer cell lines of varying metastatic capability that GJIC can be restored without enforced expression of a connexin gene. In addition, while levels of connexin 43 remained unchanged, its relocalization from the cytosol to the plasma membrane was observed. Both LY294002 and LY303511 increased the activity of protein kinase A (PKA). Moreover, PKA blockade by the small molecule inhibitor H89 decreased the LY294002/LY303511-mediated increase in GJIC. Collectively, our findings show a connection between PKA activity and GJIC mediated by PI3K-independent mechanisms of LY294002 and LY303511. Manipulation of these signaling pathways could prove useful for antimetastatic therapy.
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Affiliation(s)
- Thomas M Bodenstine
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Abstract
The sarcoplasmic reticulum (SR) of smooth muscles presents many intriguing facets and questions concerning its roles, especially as these change with development, disease, and modulation of physiological activity. The SR's function was originally perceived to be synthetic and then that of a Ca store for the contractile proteins, acting as a Ca amplification mechanism as it does in striated muscles. Gradually, as investigators have struggled to find a convincing role for Ca-induced Ca release in many smooth muscles, a role in controlling excitability has emerged. This is the Ca spark/spontaneous transient outward current coupling mechanism which reduces excitability and limits contraction. Release of SR Ca occurs in response to inositol 1,4,5-trisphosphate, Ca, and nicotinic acid adenine dinucleotide phosphate, and depletion of SR Ca can initiate Ca entry, the mechanism of which is being investigated but seems to involve Stim and Orai as found in nonexcitable cells. The contribution of the elemental Ca signals from the SR, sparks and puffs, to global Ca signals, i.e., Ca waves and oscillations, is becoming clearer but is far from established. The dynamics of SR Ca release and uptake mechanisms are reviewed along with the control of luminal Ca. We review the growing list of the SR's functions that still includes Ca storage, contraction, and relaxation but has been expanded to encompass Ca homeostasis, generating local and global Ca signals, and contributing to cellular microdomains and signaling in other organelles, including mitochondria, lysosomes, and the nucleus. For an integrated approach, a review of aspects of the SR in health and disease and during development and aging are also included. While the sheer versatility of smooth muscle makes it foolish to have a "one model fits all" approach to this subject, we have tried to synthesize conclusions wherever possible.
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Affiliation(s)
- Susan Wray
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Liverpool, Merseyside L69 3BX, United Kingdom.
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Yin X, Li B, Chen H, Catt KJ. Differential signaling pathways in angiotensin II- and epidermal growth factor-stimulated hepatic C9 cells. Mol Pharmacol 2008; 74:1223-33. [PMID: 18687808 DOI: 10.1124/mol.108.048504] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Caveolin1 (Cav1) is an important component of the plasmamembrane microdomains, such as caveolae/lipid rafts, that are associated with angiotensin II type 1 (AT(1)) and epidermal growth factor (EGF) receptors in certain cell types. The interactions of Cav1 with other signaling molecules that mediate AT(1) receptor function were analyzed in angiotensin II (Ang II)- and EGF-stimulated hepatic C9 cells. This study demonstrated that cholesterol-rich domains mediate the actions of early upstream signaling molecules such as Src and intracellular Ca(2+) in cells stimulated by Ang II, but not by EGF, and that Cav1 has a scaffolding role in the process of mitogen-activated protein kinase activation. Furthermore, Cav1 phosphorylation by Ang II and EGF was regulated by intracellular Ca(2+) and Src, further indicating reciprocal interactions among Cav1, Src, and intracellular Ca(2+) through the AT(1) receptor. Phosphorylation of Cav1 and the EGF receptor by Ang II, but not of extracellular signal-regulated kinase 1/2, was dependent on intracellular Ca(2+). The phosphatidylinositol 3-kinase inhibitors, 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002) and wortmannin, differentially modulated both Cav1 and EGF receptor activation by Ang II through intracellular Ca(2+). These findings further demonstrate the importance of Cav1 in conjunction with the receptor-mediated signaling pathways involved in cell proliferation and survival. It is clear that differential signaling pathways are operative in Ang II- and EGF-stimulated C9 cells and that cholesterol-enriched microdomains are essential components in cellular signaling processes that are dependent on specific agonists and/or cell types.
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Affiliation(s)
- Xing Yin
- Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Sun H, Xu B, Sheveleva E, Chen QM. LY294002 inhibits glucocorticoid-induced COX-2 gene expression in cardiomyocytes through a phosphatidylinositol 3 kinase-independent mechanism. Toxicol Appl Pharmacol 2008; 232:25-32. [PMID: 18657281 DOI: 10.1016/j.taap.2008.05.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 05/19/2008] [Accepted: 05/27/2008] [Indexed: 01/08/2023]
Abstract
Glucocorticoids induce COX-2 expression in rat cardiomyocytes. While investigating whether phosphatidylinositol 3 kinase (PI3K) plays a role in corticosterone (CT)-induced COX-2, we found that LY294002 (LY29) but not wortmannin (WM) attenuates CT from inducing COX-2 gene expression. Expression of a dominant-negative mutant of p85 subunit of PI3K failed to inhibit CT from inducing COX-2 expression. CT did not activate PI3K/AKT signaling pathway whereas LY29 and WM decreased the activity of PI3K. LY303511 (LY30), a structural analogue and a negative control for PI3K inhibitory activity of LY29, also suppressed COX-2 induction. These data suggest PI3K-independent mechanisms in regulating CT-induced COX-2 expression. LY29 and LY30 do not inhibit glucocorticoid receptor transactivity. Both compounds have been reported to inhibit Casein Kinase 2 activity and modulate potassium and calcium levels independent of PI3K, while LY29 has been reported to inhibit mammalian Target of Rapamycin (mTOR), and DNA-dependent Protein Kinase (DNA-PK). Inhibitor of Casein Kinase 2 (CK2), mTOR or DNA-PK failed to prevent CT from inducing COX-2 expression. Tetraethylammonium (TEA), a potassium channel blocker, and nimodipine, a calcium channel blocker, both attenuated CT from inducing COX-2 gene expression. CT was found to increase intracellular Ca(2+) concentration, which can be inhibited by LY29, TEA or nimodipine. These data suggest a possible role of calcium instead of PI3K in CT-induced COX-2 expression in cardiomyocytes.
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Affiliation(s)
- Haipeng Sun
- Interdisciplinary Graduate Program of Pharmacology and Toxicology, University of Arizona, Tucson, AZ 85724, USA
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Mazza R, Mannarino C, Imbrogno S, Barbieri SF, Adamo C, Angelone T, Corti A, Tota B. Crucial role of cytoskeleton reorganization in the negative inotropic effect of chromogranin A-derived peptides in eel and frog hearts. ACTA ACUST UNITED AC 2007; 138:145-51. [PMID: 17056132 DOI: 10.1016/j.regpep.2006.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 09/11/2006] [Accepted: 09/12/2006] [Indexed: 10/24/2022]
Abstract
Vasostatins (VSs), i.e. the main biologically active peptides generated by the proteolytic processing of chromogranin A (CGA) N-terminus, exert negative inotropism in vertebrate hearts. Here, using isolated working eel (Anguilla anguilla) and frog (Rana esculenta) heart preparations, we have studied the role of the cytoskeleton in the VSs-mediated inotropic response. In both eel and frog hearts, VSs-mediated-negative inotropy was abolished by treatment with inhibitors of cytoskeleton reorganization, such as cytochalasin-D (eel: 10 nM; frog: 1 nM), an inhibitor of actin polymerisation, wortmannin (0.01 nM), an inhibitor of PI3-kinase (PI3-K)/protein kinase B (Akt) signal-transduction cascade, butanedione 2-monoxime (BDM) (eel: 100 nM; frog: 10 nM), an antagonist of myosin ATPase, and N-(6-aminohexil)-5-chloro-1-naphthalenesulfonamide (W7) (eel: 100 nM; frog: 1 nM), a calcium-calmodulin antagonist. These results demonstrate that changes in cytoskeletal dynamics play a crucial role in the negative inotropic influence of VSs on eel and frog hearts.
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Affiliation(s)
- Rosa Mazza
- Department of Cell Biology, University of Calabria, 87030 Arcavacata di Rende (CS), Italy.
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Ethier MF, Madison JM. Adenosine A1 receptors mediate mobilization of calcium in human bronchial smooth muscle cells. Am J Respir Cell Mol Biol 2006; 35:496-502. [PMID: 16709961 PMCID: PMC2065849 DOI: 10.1165/rcmb.2005-0290oc] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Adenosine stimulates contraction of airway smooth muscle, but the mechanism is widely considered indirect, depending on release of contractile agonists from mast cells and nerves. The goal was to determine whether adenosine, by itself, directly regulates calcium signaling in human bronchial smooth muscle cells (HBSMC). Primary cultures of HBSMC from normal subjects were loaded with fura 2-AM, and cytosolic calcium concentrations ([Ca(2+)](i)) were determined ratiometrically by imaging single cells. The nonselective adenosine receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA), and the adenosine A(1) receptor agonist, N(6)-cyclopentyladenosine (CPA), both stimulated rapid, transient increases in [Ca(2+)](i). In contrast, there were no calcium responses to 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido-adenosine (100 nM) or N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (100 nM), selective agonists at adenosine A(2A) receptors and adenosine A(3) receptors, respectively. Calcium responses to NECA and CPA were inhibited by 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A(1) receptor antagonist, and by pertussis toxin (PTX). In other experiments, NECA stimulated calcium transients in the absence of extracellular calcium, but not when cells were preincubated in cyclopiazonic acid or thapsigargin to empty intracellular calcium stores. Calcium responses were attenuated by xestospongin C and 2-aminoethoxydiphenylborane, inhibitors of inositol trisphosphate (IP(3)) receptors, and by U73122, an inhibitor of phospholipase C. It was concluded that stimulation of adenosine A(1) receptors on HBSMC rapidly mobilizes intracellular calcium stores by a mechanism dependent on PTX-sensitive G proteins, and IP(3) signaling. These findings suggest that, in addition to its well-established indirect effects on HBSMC, adenosine also has direct effects on contractile signaling pathways.
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Affiliation(s)
- Michael F Ethier
- Department of Medicine, 364 Plantation Street, LRB, Room 370A, University of Massachusetts Medical School, Worcester, 01605, USA.
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Brown JK, Hollenberg MD, Jones CA. Tryptase activates phosphatidylinositol 3-kinases proteolytically independently from proteinase-activated receptor-2 in cultured dog airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2006; 290:L259-69. [PMID: 16155087 DOI: 10.1152/ajplung.00215.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mast cell tryptase is a potent mitogen for many cells in the airways and lung, but the cellular mechanisms for its growth stimulatory effects are poorly understood. Our major goal was to determine whether tryptase activates phosphatidylinositol 3-kinases (PI 3-kinases) in cultured dog tracheal smooth muscle cells to induce its mitogenic effects. After exposure to tryptase, cells were lysed. Immunocomplexes prepared from the lysates using an antibody to the p85 subunit of PI 3-kinase, but not using anti-phosphotyrosine antibodies, possessed increased capacity to phosphorylate inositol on its D3 hydroxyl group. Tryptase also increased phosphorylation of Akt, a downstream target of PI 3-kinases. This effect was abolished by one PI 3-kinase inhibitor, wortmannin, and attenuated by another, LY-294004, which also blocked tryptase's mitogenic effects. Treatment of tryptase with p-amidino phenylmethanesulfonyl fluoride, to abolish its proteolytic activity irreversibly, inhibited its stimulatory effects on Akt phosphorylation. Proteinase-activated receptor-2 (PAR-2)-activating peptides failed to increase Akt phosphorylation in cultured dog tracheal smooth muscle cells, but the PAR-2-activating peptides did induce brisk increases in Akt phosphorylation in Madin-Darby canine kidney cells. We concluded that tryptase activates PI 3-kinases in cultured dog tracheal smooth muscle cells to induce its potent mitogenic effects. These effects of tryptase on PI 3-kinases appear to occur via novel proteolytic mechanisms independent from PAR-2. Also, tryptase, although comparable in mitogenic potency to platelet-derived growth factor (PDGF), induces considerably less tyrosine phosphorylation on proteins than occur in response to PDGF.
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Affiliation(s)
- James K Brown
- Pulmonary and Critical Care Medicine Section, Dept. of Veterans Affairs Medical Center, and Department of Medicine, University of California San Francisco, CA 94121, USA.
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LY 294002 inhibits adenosine receptor activation by a mechanism independent of effects on PI-3 kinase or casein kinase II. Purinergic Signal 2005; 1:389-94. [PMID: 18404524 PMCID: PMC2096559 DOI: 10.1007/s11302-005-0778-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Revised: 07/11/2005] [Accepted: 07/12/2005] [Indexed: 01/23/2023] Open
Abstract
Adenosine reduces both evoked and spontaneous calcium-dependent acetylcholine (ACh) release through a mechanism downstream of calcium entry at amphibian motor nerve endings (Silinsky EM. J Physiol 1984; 346: 243-6). LY 294002 (2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one), an inhibitor of both phosphoinositide-3 kinase (PI-3 kinase) and casein kinase II, has been reported to increase spontaneous ACh release reflected in miniature endplate potential (MEPP) frequencies independently of intraterminal calcium at the frog neuromuscular junction (Rizzoli SO, Betz WJ. J Neurosci 2002; 22: 10680-). It has been suggested that the increase in MEPP frequency caused by LY 294002, is mediated through an action on synaptotagmins, vesicle associated calcium sensors believed to trigger synaptic vesicle exocytosis. We thus examined the effects of adenosine on MEPP frequencies and evoked ACh release reflected as endplate potentials (EPPs) in order to determine if the presumed calcium-independent ACh release is affected by adenosine. We also wanted to determine if PI-3 kinase or casein kinase II is involved in mediating or modulating the inhibitory effects of adenosine. To these ends, we examined the effects of adenosine in the presence of LY 294002, wortmannin (a highly selective the PI-3 kinase inhibitor), or DRB (5,6-dichlorobenzimidazole riboside, an inhibitor of casein kinase II). LY 294002 reduced the sensitivity of both MEPP frequencies and the nerve-evoked calcium dependent EPPs to adenosine. The occlusive effects of LY 294002 on the actions of adenosine on MEPPs and EPPs were overcome by increasing adenosine concentration. Neither wortmannin nor DRB had any effect on the sensitivity of the EPPs to adenosine indicating that neither PI-3 kinase nor casein kinase II inhibition mediates the reduction in motor-nerve terminal sensitivity to adenosine produced by LY 294002. The results indicate a competitive relationship between LY 294002 and adenosine at A1 receptors at the frog neuromuscular junction. This effect is independent of the previously described effects of LY 294002 on the exocytotic process, and is also independent of PI-3 kinase or casein kinase II.
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Schmidt R, Staats P, Groneberg DA, Wagner U. The cysteinyl-leukotriene-1 receptor antagonist zafirlukast is a potent secretagogue in rat and human airways. Eur J Pharmacol 2005; 527:150-6. [PMID: 16310765 DOI: 10.1016/j.ejphar.2005.08.064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 08/08/2005] [Indexed: 11/18/2022]
Abstract
Cysteinyl-leukotriene-1 receptor antagonists are important tools in the therapy of asthma. Although many studies have been performed concerning their effects on airway smooth muscle tone, there are no basic data on their effects on airway secretions. Therefore, we assessed the effects of zafirlukast and montelukast on rat tracheal secretion by quantification of secreted 35S04 labelled mucus macromolecules, and determined the influence of the arachidonic acid pathway using the modified Ussing chamber technique. Zafirlukast (432+/-89.99%) and montelukast (167+/-16.74%) stimulated rat tracheal secretion. This was abolished by application of eicosatetraenoic acid, an inhibitor of the arachidonic acid metabolism. Whereas inhibition of cyclooxygenase did not show any significant effect on zafirlukast induced secretion, blockade of the 5-lipoxygenase pathway markedly reduced the secretagogue effects. Furthermore, inhibition of phosphatidylinositol-3-kinase completely inhibited the effects elicited by zafirlukast. Additional experiments revealed secretagogue effects of zafirlukast also in human bronchial tissue. In conclusion, zafirlukast is a potent inducer of tracheal secretion. Obviously, these effects are induced by involvement of a phosphatidylinositol-3-kinase dependent pathway mediated by products of the arachidonic acid metabolism.
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Affiliation(s)
- Rene Schmidt
- Department of Anesthesiology, Albert-Ludwigs-University, Freiburg, Germany
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Alladina SJ, Song JH, Davidge ST, Hao C, Easton AS. TRAIL-Induced Apoptosis in Human Vascular Endothelium Is Regulated by Phosphatidylinositol 3-Kinase/Akt through the Short Form of Cellular FLIP and Bcl-2. J Vasc Res 2005; 42:337-47. [PMID: 15985761 DOI: 10.1159/000086599] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Accepted: 05/17/2005] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Apoptosis of vascular endothelial cells plays a central role in angiogenesis and atherosclerosis. This study investigates the molecular mechanisms of endothelial apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) following inhibition of phosphatidylinositol 3-kinase (PI3K). It examines downstream regulation and activation of the extrinsic and intrinsic pathways. METHODS AND RESULTS By flow cytometry, TRAIL receptors 2 and 3 were present to a greater extent than receptors 1 and 4. TRAIL reduced cell numbers in combination with the PI3K inhibitor LY 294002. TRAIL (100 ng/ml) with LY 294002 (20 micromol/l) activated the extrinsic pathway, causing progressive cleavage of caspase-8 and caspase-3. Activation of the intrinsic pathway proceeded by release of mitochondrial factors Smac/DIABLO and cytochrome c, and caspase-9 cleavage. LY 294002 reduced phosphorylated Akt (p-Akt), with early loss of the short form of cellular FLIP (c-FLIP(S)) and concurrent reduction of Bcl-2. Treatment with small interfering RNA against PI3K also reduced c-FLIP(S) and Bcl-2, and cotreatment with TRAIL triggered caspase-3 cleavage. CONCLUSIONS This study details the molecular regulation of TRAIL-induced apoptosis in vascular endothelium. Inhibition of PI3K reduces p-Akt, with concurrent reductions in c-FLIP(S) and Bcl-2, and so renders endothelium sensitive to TRAIL-induced apoptosis through the extrinsic and intrinsic pathways.
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Affiliation(s)
- Salima J Alladina
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Canada
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Laporte R, Hui A, Laher I. Pharmacological modulation of sarcoplasmic reticulum function in smooth muscle. Pharmacol Rev 2005; 56:439-513. [PMID: 15602008 DOI: 10.1124/pr.56.4.1] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The sarco/endoplasmic reticulum (SR/ER) is the primary storage and release site of intracellular calcium (Ca2+) in many excitable cells. The SR is a tubular network, which in smooth muscle (SM) cells distributes close to cellular periphery (superficial SR) and in deeper aspects of the cell (deep SR). Recent attention has focused on the regulation of cell function by the superficial SR, which can act as a buffer and also as a regulator of membrane channels and transporters. Ca2+ is released from the SR via two types of ionic channels [ryanodine- and inositol 1,4,5-trisphosphate-gated], whereas accumulation from thecytoplasm occurs exclusively by an energy-dependent sarco-endoplasmic reticulum Ca2+-ATPase pump (SERCA). Within the SR, Ca2+ is bound to various storage proteins. Emerging evidence also suggests that the perinuclear portion of the SR may play an important role in nuclear transcription. In this review, we detail the pharmacology of agents that alter the functions of Ca2+ release channels and of SERCA. We describe their use and selectivity and indicate the concentrations used in investigating various SM preparations. Important aspects of cell regulation and excitation-contractile activity coupling in SM have been uncovered through the use of such activators and inhibitors of processes that determine SR function. Likewise, they were instrumental in the recent finding of an interaction of the SR with other cellular organelles such as mitochondria. Thus, an appreciation of the pharmacology and selectivity of agents that interfere with SR function in SM has greatly assisted in unveiling the multifaceted nature of the SR.
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Affiliation(s)
- Régent Laporte
- Ferring Research Institute, Inc., Ferring Pharmaceuticals, San Diego, California, USA
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Jacobs MD, Black J, Futer O, Swenson L, Hare B, Fleming M, Saxena K. Pim-1 Ligand-bound Structures Reveal the Mechanism of Serine/Threonine Kinase Inhibition by LY294002. J Biol Chem 2005; 280:13728-34. [PMID: 15657054 DOI: 10.1074/jbc.m413155200] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Pim-1 is an oncogene-encoded serine/threonine kinase primarily expressed in hematopoietic and germ cell lines. Pim-1 kinase was originally identified in Maloney murine leukemia virus-induced T-cell lymphomas and is associated with multiple cellular functions such as proliferation, survival, differentiation, apoptosis, and tumorigenesis (Wang, Z., Bhattacharya, N., Weaver, M., Petersen, K., Meyer, M., Gapter, L., and Magnuson, N. S. (2001) J. Vet. Sci. 2, 167-179). The crystal structures of Pim-1 complexed with staurosporine and adenosine were determined. Although a typical two-domain serine/threonine protein kinase fold is observed, the inter-domain hinge region is unusual in both sequence and conformation; a two-residue insertion causes the hinge to bulge away from the ATP-binding pocket, and a proline residue in the hinge removes a conserved main chain hydrogen bond donor. Without this hydrogen bond, van der Waals interactions with the hinge serve to position the ligand. The hinge region of Pim-1 resembles that of phosphatidylinositol 3-kinase more closely than it does other protein kinases. Although the phosphatidylinositol 3-kinase inhibitor LY294002 also inhibits Pim-1, the structure of the LY294002.Pim-1 complex reveals a new binding mode that may be general for Ser/Thr kinases.
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Affiliation(s)
- Marc D Jacobs
- Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139, USA.
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Ethier MF, Cappelluti E, Madison JM. Mechanisms of interleukin-4 effects on calcium signaling in airway smooth muscle cells. J Pharmacol Exp Ther 2005; 313:127-33. [PMID: 15634940 DOI: 10.1124/jpet.104.079343] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In airway smooth muscle cells, interleukin (IL)-4 inhibited both carbachol- and caffeine-induced calcium mobilization from the sarcoplasmic reticulum (SR). Because of the known signaling pathways for IL-4 and importance of calcium uptake in maintaining SR calcium stores shared by agonists and caffeine, it was hypothesized that this rapid inhibitory effect might depend on phosphatidylinositol 3-kinase (PI3K) and on inhibition of calcium uptake by the SR. Enzyme-dispersed bovine trachealis cells were loaded with Fura-2/acetoxymethyl ester, and changes in cytosolic calcium were imaged in single cells. Cells were pretreated with inhibitors of PI3K, either wortmannin (100 nM), LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one] (50 microM), or deguelin (100 nM). Calcium transients in response to carbachol (10 microM) were significantly decreased to 0.34 +/- 0.10 of control after 20-min treatment with IL-4 but were 1.10 +/- 0.26 and 1.08 +/- 0.23 when wortmannin or deguelin, respectively, was added along with IL-4. LY294002 alone had nonspecific effects on transients. In other experiments, cyclopiazonic acid (CPA) (5 microM), an inhibitor of SR calcium uptake, decreased carbachol-stimulated transients within 4 min to 0.83 +/- 0.08 of control (n = 6). However, for cells treated with IL-4 (50 ng/ml) plus CPA, transients decreased significantly more, to only 0.51 +/- 0.05 (n = 6; p < 0.05). Longer exposures to IL-4 and a higher concentration of CPA (30 microM) gave similar results. It was concluded that IL-4 did not inhibit transients in the presence of PI3K antagonists but that it did in the presence of CPA. This suggested that IL-4 inhibited calcium transients by mechanisms dependent upon a wortmannin-sensitive PI3K but not by inhibition of calcium uptake into the SR.
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Affiliation(s)
- Michael F Ethier
- Department of Medicine, LRB Room 319, University of Massachusetts Medical School, 364 Plantation St., Worcester, MA 01605, USA
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Ito S, Kume H, Honjo H, Kodama I, Katoh H, Hayashi H, Shimokata K. ML-9, a myosin light chain kinase inhibitor, reduces intracellular Ca2+ concentration in guinea pig trachealis. Eur J Pharmacol 2004; 486:325-33. [PMID: 14985055 DOI: 10.1016/j.ejphar.2004.01.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Revised: 01/09/2004] [Accepted: 01/13/2004] [Indexed: 11/15/2022]
Abstract
We investigated the effects of ML-9 [1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine], a myosin light chain kinase (MLCK) inhibitor, on intracellular Ca2+ concentration ([Ca2+]i), contraction induced by high K+ and an agonist, and capacitative Ca2+ entry in fura-2-loaded guinea pig tracheal smooth muscle. ML-9 inhibited both the increase in [Ca2+]i and the contraction induced by 60 mM K+, 1 microM methacholine or 1 microM thapsigargin, an inhibitor of the sarcoplasmic reticulum Ca2+-ATPase. However, another MLCK inhibitor, wortmannin (3 microM), inhibited the contraction elicited by these stimuli without affecting [Ca2+]i. Under the condition that the thapsigargin-induced contraction was fully suppressed by 3 microM wortmannin, 30 microM ML-9 caused a further decrease in [Ca2+]i. The inhibitory effects of ML-9 on [Ca2+]i and the contraction elicited by methacholine were similar to those of SKF-96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride), a Ca2+ channel blocker. These results indicate that ML-9 acts as a potent inhibitor of Ca2+-permeable channels independently of MLCK inhibition in tracheal smooth muscle.
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Affiliation(s)
- Satoru Ito
- Division of Respiratory Medicine, Department of Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa, Nagoya 466-8550, Japan
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El-Kholy W, Macdonald PE, Lin JH, Wang J, Fox JM, Light PE, Wang Q, Tsushima RG, Wheeler MB. The phosphatidylinositol 3-kinase inhibitor LY294002 potently blocks K(V) currents via a direct mechanism. FASEB J 2003; 17:720-2. [PMID: 12586735 DOI: 10.1096/fj.02-0802fje] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Voltage-dependent K+ (Kv) channels negatively regulate Ca2+ entry into pancreatic beta-cells by repolarizing glucose-stimulated action potentials. A role for phosphatidylinositol 3-kinase (PI3K) modulation of Kv channel function was investigated using the PI3K inhibitors wortmannin and LY294002, and LY303511, a negative control compound with respect to PI3K activity. In MIN6 insulinoma cells, wortmannin (100 nM) had no effect on whole-cell outward K+ currents, but LY294002 and LY303511 reversibly blocked currents in a dose-dependent manner (IC50=9.0+/-0.7 microM and 64.6+/-9.1 microM, respectively). Western blotting confirmed the specific inhibitory effects of LY294002 and wortmannin on insulin-stimulated PI3K activity. Kv currents in rat beta-cells at near physiological temperatures were inhibited 92% by 25 microM LY294002. Kv2.1 and Kv1.4 are highly expressed in beta-cells, and in Kv2.1-transfected tsA201 cells, 50 microM LY294002 and 100 microM LY303511 reversibly inhibited currents by 99% and 41%, respectively. In Kv1.4-transfected tsA201 cells, 50 microM LY294002 reduced the inactivation time constant from 73 to 18 ms. The insulinotropic properties of LY294002 and its effects in other excitable cells may be caused by inhibition of Kv currents rather than PI3K antagonism. Furthermore, LY294002 may represent a novel structure from which future Kv channel blockers may be developed.
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Affiliation(s)
- Wasim El-Kholy
- Department of Medicine, University of Toronto, Ontario, Canada
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