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Lin S, Liu X, Sun A, Liang H, Li Z, Ye S, Ma H, Fan W, Shen C, Jin M, He Q. Qilong capsule alleviates ponatinib-induced ischemic stroke in a zebrafish model by regulating coagulation, inflammation and apoptosis. JOURNAL OF ETHNOPHARMACOLOGY 2023; 314:116397. [PMID: 37086871 DOI: 10.1016/j.jep.2023.116397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/23/2023] [Accepted: 03/14/2023] [Indexed: 05/03/2023]
Abstract
ETHOPHARMACOLOGICAL RELEVANCE Qilong capsule (QLC) is a compound traditional Chinese medicine commonly used to treat ischemic stroke (IS). QLC is made of eight kinds of medicinal materials. It has two kinds of monarch medicine and six kinds of minister medicine. However, the pharmacodynamic mechanism of QLC is still unknown. AIM OF THE STUDY The aim of this paper was to evaluate the pharmacology mechanism of QLC against ischemic stroke through coagulation, inflammation and apoptosis. MATERIALS AND METHODS We used an existing zebrafish model to explore the protective mechanism of QLC on IS. We treated normally-developing zebrafish larvae with QLC and ponatinib 2 days post fertilization (dpf), and used the area of cerebral vascular thrombosis, red blood cell staining intensity, and brain cell apoptosis to quantitate QLC efficacy against IS. Evaluation of brain inflammation in zebrafish by observing macrophage aggregation and migration. In addition, we also explored the effect of QLC on zebrafish angiogenesis. Quantitative polymerase chain reaction (qPCR) was used to detect changes in the expression of genes involved in coagulation, inflammation, vascular endothelium, and apoptosis. RESULTS We found that QLC reduced the area affected by ponatinib-induced cerebral vascular embolism, erythrocyte staining intensity, and the number of apoptotic brain cells. For inflammation, QLC can improve the aggregation and migration of macrophages. QLC can significantly promote the formation of blood vessels in zebrafish. qPCR showed that QLC inhibited the expression of genes related to coagulation, inflammation, and apoptosis. CONCLUSION Qilong capsule had a significant protective efficacy in ponatinib-induced IS.
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Affiliation(s)
- Shenghua Lin
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Xin Liu
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Aonan Sun
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Huiliang Liang
- Shandong Jining Huaneng Pharmaceutical Factory, Jining, China
| | - Zhen Li
- Shandong Jining Huaneng Pharmaceutical Factory, Jining, China
| | - Suyan Ye
- Shandong Jining Huaneng Pharmaceutical Factory, Jining, China
| | - Honglin Ma
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Wei Fan
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Chuanlin Shen
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Meng Jin
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Qiuxia He
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China; Science and Technology Service Platform, Qilu University of Technology (Shandong Academy of Sciences), China.
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De Silva E, Hong F, Falet H, Kim H. Filamin A in platelets: Bridging the (signaling) gap between the plasma membrane and the actin cytoskeleton. Front Mol Biosci 2022; 9:1060361. [PMID: 36605989 PMCID: PMC9808056 DOI: 10.3389/fmolb.2022.1060361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/30/2022] [Indexed: 12/24/2022] Open
Abstract
Platelets are anucleate cells that are essential for hemostasis and wound healing. Upon activation of the cell surface receptors by their corresponding extracellular ligands, platelets undergo rapid shape change driven by the actin cytoskeleton; this shape change reaction is modulated by a diverse array of actin-binding proteins. One actin-binding protein, filamin A (FLNA), cross-links and stabilizes subcortical actin filaments thus providing stability to the cell membrane. In addition, FLNA binds the intracellular portion of multiple cell surface receptors and acts as a critical intracellular signaling scaffold that integrates signals between the platelet's plasma membrane and the actin cytoskeleton. This mini-review summarizes how FLNA transduces critical cell signals to the platelet cytoskeleton.
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Affiliation(s)
- Enoli De Silva
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Felix Hong
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Hervé Falet
- Versiti Blood Research Institute, Milwaukee, WI, United States
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Hugh Kim
- Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
- Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, BC, Canada
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3
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Cardiovascular protection effect of a Northeastern Brazilian lyophilized red wine in spontaneously hypertensive rats. J Funct Foods 2022. [DOI: 10.1016/j.jff.2021.104868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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4
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Liao L, Zhou M, Wang J, Xue X, Deng Y, Zhao X, Peng C, Li Y. Identification of the Antithrombotic Mechanism of Leonurine in Adrenalin Hydrochloride-Induced Thrombosis in Zebrafish via Regulating Oxidative Stress and Coagulation Cascade. Front Pharmacol 2021; 12:742954. [PMID: 34803688 PMCID: PMC8600049 DOI: 10.3389/fphar.2021.742954] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 10/20/2021] [Indexed: 01/11/2023] Open
Abstract
Thrombosis is a general pathological phenomenon during severe disturbances to homeostasis, which plays an essential role in cardiovascular and cerebrovascular diseases. Leonurine (LEO), isolated from Leonurus japonicus Houtt, showes a crucial role in anticoagulation and vasodilatation. However, the properties and therapeutic mechanisms of this effect have not yet been systematically elucidated. Therefore, the antithrombotic effect of LEO was investigated in this study. Hematoxylin-Eosin staining was used to detect the thrombosis of zebrafish tail. Fluorescence probe was used to detect the reactive oxygen species. The biochemical indexes related to oxidative stress (lactate dehydrogenase, malondialdehyde, superoxide dismutase and glutathione) and vasodilator factor (endothelin-1 and nitric oxide) were analyzed by specific commercial assay kits. Besides, we detected the expression of related genes (fga, fgb, fgg, pkcα, pkcβ, vwf, f2) and proteins (PI3K, phospho-PI3K, Akt, phospho-Akt, ERK, phospho-ERK FIB) related to the anticoagulation and fibrinolytic system by quantitative reverse transcription and western blot. Beyond that, metabolomic analyses were carried out to identify the expressions of metabolites associated with the anti-thrombosis mechanism of LEO. Our in vivo experimental results showed that LEO could improve the oxidative stress injury, abnormal platelet aggregation and coagulation dysfunction induced by adrenalin hydrochloride. Moreover, LEO restored the modulation of amino acids and inositol metabolites which are reported to alleviate the thrombus formation. Collectively, LEO attenuates adrenalin hydrochloride-induced thrombosis partly via modulating oxidative stress, coagulation cascade and platelet activation and amino acid and inositol metabolites.
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Affiliation(s)
- Li Liao
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Mengting Zhou
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Jing Wang
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Xinyan Xue
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Ying Deng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Xingtao Zhao
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
| | - Yunxia Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu, China.,School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,National Key Laboratory Breeding Base of Systematic Research, Development and Utilization of Chinese Medicine Resources, Chengdu, China
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5
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Yin SJ, Luo YQ, Zhao CP, Chen H, Zhong ZF, Wang S, Wang YT, Yang FQ. Antithrombotic effect and action mechanism of Salvia miltiorrhiza and Panax notoginseng herbal pair on the zebrafish. Chin Med 2020; 15:35. [PMID: 32322295 PMCID: PMC7164150 DOI: 10.1186/s13020-020-00316-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/06/2020] [Indexed: 12/14/2022] Open
Abstract
Background Salvia miltiorrhiza (Danshen, DS) and Panax notoginseng (Sanqi, SQ) are famous traditional Chinese herbs, and their herbal pair (DS–SQ) has been popular used as anti-thrombotic medicines. However, there is still a lack of sufficient scientific evidence to illustrate the optimum combination ratio of these two herbs as well as its action mechanisms. The purpose of this study is to investigate the anti-thrombotic effects of DS–SQ on zebrafish and explore its possible action mechanism. Methods Firstly, the chemical components in DS–SQ extract were analyzed by LC–ESI–MS/MS. Then, a phenylhydrazine (PHZ)-induced zebrafish thrombosis model was developed for evaluating the anti-thrombotic effects of DS–SQ extracts with different combination ratios and their nine pure compounds. Followed, Real-time quantitative PCR (RT-qPCR) assays were performed to investigate the potential antithrombotic mechanisms of DS–SQ. Results Thirty-three components were tentatively identified by LC–MS analysis. DS–SQ at the ratio of 10:1 presented the best anti-thrombotic effect, and rosmarinic acid, lithospermic acid and salvianolic acid B of DS showed good anti-thrombotic activity on zebrafish thrombosis model. The RT-qPCR assays indicated that DS–SQ (10:1) could cure the PHZ-induced thrombosis by downregulating the expression of PKCα, PKCβ, fga, fgb, fgg and vWF in zebrafish. Conclusions DS–SQ with the combination ratio of 10:1 showed optimum anti-thrombotic effect on PHZ-induced zebrafish thrombosis model, which provided a reference for reasonable clinical applications of DS–SQ herbal pair.
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Carubbi C, Masselli E, Pozzi G, Mattioli M, Martini S, Goldoni M, Aloe R, Cervellin G, Vitale M, Gobbi G. Combination of Platelet expression of PKCepsilon and cardiac troponin-I for early diagnosis of chest pain patients in the emergency department. Sci Rep 2019; 9:2125. [PMID: 30765820 PMCID: PMC6375996 DOI: 10.1038/s41598-019-38624-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/28/2018] [Indexed: 01/02/2023] Open
Abstract
A rapid differential diagnosis of the clinical conditions underlying chest pain is a relevant clinical issue. Specifically, a fast rule-in or -out of acute myocardial infarction (AMI) is mandatory to improve diagnostic outcome and cost-effectiveness of patient management. We demonstrated that Protein Kinase C (PKC) epsilon is selectively expressed by platelets from AMI patients, accounting for increased platelet activation. Thus, we hypothesized that PKCepsilon-expressing platelets may represent a pathophysiological marker of AMI that could be utilized in combination with troponin-I, the conventional marker of cardiac injury, to add diagnostic information in chest pain workup. In 94 chest pain patients consecutively admitted to Parma University Hospital, we tested the diagnostic performance of flow-cytometric detection of PKCepsilon expressing platelets in discriminating AMI vs. non-AMI conditions. We demonstrated that PKCepsilon-expressing platelets were significantly higher in patients with AMI. Flow cytometry detection of PKCepsilon-expressing platelets showed high sensitivity and specificity (87.5% and 84.4%, respectively) and good diagnostic accuracy (AUC: 0.875). The combination of PKCepsilon expressing platelets and cardiac troponin clearly discriminates patients with 100% and 0% of probability to be affected by AMI. Overall, we highlighted a dual marker strategy potentially useful for a rapid rule-in or -out of myocardial infarction in chest pain patients.
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Affiliation(s)
- Cecilia Carubbi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Elena Masselli
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Giulia Pozzi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Maria Mattioli
- Division of Cardiology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, United Kingdom
| | - Matteo Goldoni
- Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Rosalia Aloe
- Dipartimento di Biochimica ad Elevata Automazione, Dipartimento Diagnostico, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | | | - Marco Vitale
- Department of Medicine and Surgery, University of Parma, Parma, Italy.
- Sport and exercise medicine center (SEM), University of Parma, Parma, Italy.
- CoreLab, Azienda Ospedaliero-Universitaria di Parma, University of Parma, Parma, Italy.
| | - Giuliana Gobbi
- Department of Medicine and Surgery, University of Parma, Parma, Italy
- Sport and exercise medicine center (SEM), University of Parma, Parma, Italy
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7
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Liu D, Cao Y, Zhang X, Peng C, Tian X, Yan C, Liu Y, Liu M, Han Y. Chemokine CC-motif ligand 2 participates in platelet function and arterial thrombosis by regulating PKCα-P38MAPK-HSP27 pathway. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2901-2912. [PMID: 29864522 DOI: 10.1016/j.bbadis.2018.05.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/10/2018] [Accepted: 05/30/2018] [Indexed: 12/22/2022]
Abstract
BACKGROUND Studies indicate that chemokine CC-motif ligand 2 (CCL2) is involved in inflammation and atherosclerosis. However, the roles and mechanisms of CCL2 on platelet function and arterial thrombosis are unknown. METHODS The expressions of CCL2 or CCR2 in the plasma, platelets and coronary thrombus of ST-elevated myocardial infarction (STEMI) patients were examined by ELISA, Western blot, immunohistochemistry and immunofluorescence. The roles of CCL2 on platelet aggregation, activation and secretion were examined by light transmission aggregometry, flow cytometry and ELISA. RESULTS The expressions of CCL2 or CCR2 in the plasma or platelets of STEMI patients with platelet high response were higher than those with platelet normal response; In vitro, exogenous recombinant human CCL2 markedly increased platelet aggregation, activation and granule secretion, which were abolished by CCL2 neutralizing antibody or CCR2 inhibiter. CCL2 increased the phosphorylation levels of PKCα (Thr638), P38MAPK (Thr180/Tyr182) and HSP27 (S78/S82) in human platelets, which were abrogated by PKCα inhibitor (RO 318220) or P38MAPK inhibitor (SB 203580). RO 318220 or SB 203580 diminished CCL2-induced platelet function. In CCL2-/- mice, platelet aggregation and secretion were attenuated; the phosphorylation of PKCα, P38MAPK and HSP27 were decreased. In a carotid arterial thrombus mouse model, CCL2-/- mice displayed a significantly extended carotid artery occlusion time compared with wild type. CONCLUSIONS CCL2 played important roles in regulating platelet function and arterial thrombosis through the PKCα-P38MAPK-HSP27 pathway, which might provide theoretical basis for searching new antiplatelet drugs and the treatment for cardiovascular diseases.
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Affiliation(s)
- Dan Liu
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Yu Cao
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Xiaolin Zhang
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Chengfei Peng
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Xiaoxiang Tian
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Chenghui Yan
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Yanxia Liu
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Meili Liu
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China
| | - Yaling Han
- Cardiovascular Research Institute and Department of Cardiology, General Hospital of Shenyang Military Region, Shenyang, China.
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Lin CS, Chen TH, Lin IH, Lee AR, Chou TC. The novel compound MP407 inhibits platelet aggregation through cyclic AMP-dependent processes. Eur J Pharmacol 2017; 815:324-331. [PMID: 28939294 DOI: 10.1016/j.ejphar.2017.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 11/27/2022]
Abstract
Platelet hyperactivity plays a critical role for initiating several vascular diseases such as atherothrombosis. Therefore, development of effective antiplatelet agents is necessary for ameliorating platelet-related diseases. In this study, we investigated the effects of the new synthesized compound, MP407 on platelet aggregation and further elucidated the underlying mechanisms. Our results demonstrated that MP407 dose-dependently inhibited collagen-induced platelet aggregation, thromboxane B2 (TXB2) production, intracellular Ca2+ mobilization, platelet membrane GPIIb/IIIa expression, and the phosphorylation of Akt, GSK3β, p38MAPK, and phospho (Ser) PKC substrate (p47). Moreover, MP407 is able to increase the cyclic AMP formation both in resting and activated platelets. However, blocking cyclic AMP formation with 2'5'-ddAdo, an inhibitor of adenylate cyclase, greatly reversed the antiplatelet activity of MP407 and related platelet-activating pathways. MP407 also enhanced VASP phosphorylation at Ser157 in collagen-stimulated platelets, which was attenuated by addition of 2'5'-ddAdo. Therefore, the antiplatelet activity of MP407 may be modulated by cyclic AMP-dependent regulation of Akt, GSK3β, p38MAPK and VASP phosphorylation. Notably, treatment with MP407 markedly reduced the pulmonary thrombosis and the numbers of paralysis and death in mice induced by ADP injection, but did not affect the bleeding time. Taken together, MP407 may be a potential candidate or lead compound for developing novel antiplatelet or antithrombotic agents for platelet hyperactivity-triggered disease therapy.
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Affiliation(s)
- Chung-Shuen Lin
- School of Post-Baccalaureate Chinese Medicine, Tzu Chi University, Hualien, Taiwan
| | - Tso-Hsiao Chen
- Division of Nephrology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - I-Hsin Lin
- School of Post-Baccalaureate Chinese Medicine, Tzu Chi University, Hualien, Taiwan
| | - An-Rong Lee
- School of Pharmacy, National Defense Medical Center, Taipei, Taiwan
| | - Tz-Chong Chou
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; China Medical University Hospital, China Medical University, Taichung, Taiwan.
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Carubbi C, Masselli E, Martini S, Galli D, Aversa F, Mirandola P, Italiano JE, Gobbi G, Vitale M. Human thrombopoiesis depends on Protein kinase Cδ/protein kinase Cε functional couple. Haematologica 2016; 101:812-20. [PMID: 27081176 DOI: 10.3324/haematol.2015.137984] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 04/12/2016] [Indexed: 01/12/2023] Open
Abstract
A deeper understanding of the molecular events driving megakaryocytopoiesis and thrombopoiesis is essential to regulate in vitro and in vivo platelet production for clinical applications. We previously documented the crucial role of PKCε in the regulation of human and mouse megakaryocyte maturation and platelet release. However, since several data show that different PKC isoforms fulfill complementary functions, we targeted PKCε and PKCδ, which show functional and phenotypical reciprocity, at the same time as boosting platelet production in vitro. Results show that PKCδ, contrary to PKCε, is persistently expressed during megakaryocytic differentiation, and a forced PKCδ down-modulation impairs megakaryocyte maturation and platelet production. PKCδ and PKCε work as a functional couple with opposite roles on thrombopoiesis, and the modulation of their balance strongly impacts platelet production. Indeed, we show an imbalance of PKCδ/PKCε ratio both in primary myelofibrosis and essential thrombocythemia, featured by impaired megakaryocyte differentiation and increased platelet production, respectively. Finally, we demonstrate that concurrent molecular targeting of both PKCδ and PKCε represents a strategy for in vitro platelet factories.
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Affiliation(s)
- Cecilia Carubbi
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Elena Masselli
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Silvia Martini
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Daniela Galli
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Franco Aversa
- Department of Clinical and Experimental Medicine, University of Parma, Italy
| | - Prisco Mirandola
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Joseph E Italiano
- Hematology Division, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA, USA
| | - Giuliana Gobbi
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
| | - Marco Vitale
- Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Italy
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10
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Bhavanasi D, Badolia R, Manne BK, Janapati S, Dangelmaier CT, Mazharian A, Jin J, Kim S, Zhang X, Chen X, Senis YA, Kunapuli SP. Cross talk between serine/threonine and tyrosine kinases regulates ADP-induced thromboxane generation in platelets. Thromb Haemost 2015; 114:558-68. [PMID: 25947062 DOI: 10.1160/th14-09-0775] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 03/26/2015] [Indexed: 11/05/2022]
Abstract
ADP-induced thromboxane generation depends on Src family kinases (SFKs) and is enhanced with pan-protein kinase C (PKC) inhibitors, but it is not clear how these two events are linked. The aim of the current study is to investigate the role of Y311 phosphorylated PKCδ in regulating ADP-induced platelet activation. In the current study, we employed various inhibitors and murine platelets from mice deficient in specific molecules to evaluate the role of PKCδ in ADP-induced platelet responses. We show that, upon stimulation of platelets with 2MeSADP, Y311 on PKCδ is phosphorylated in a P2Y1/Gq and Lyn-dependent manner. By using PKCδ and Lyn knockout murine platelets, we also show that tyrosine phosphorylated PKCδ plays a functional role in mediating 2MeSADP-induced thromboxane generation. 2MeSADP-induced PKCδ Y311 phosphorylation and thromboxane generation were potentiated in human platelets pre-treated with either a pan-PKC inhibitor, GF109203X or a PKC α/β inhibitor and in PKC α or β knockout murine platelets compared to controls. Furthermore, we show that PKC α/β inhibition potentiates the activity of SFK, which further hyper-phosphorylates PKCδ and potentiates thromboxane generation. These results show for the first time that tyrosine phosphorylated PKCδ regulates ADP-induced thromboxane generation independent of its catalytic activity and that classical PKC isoforms α/β regulate the tyrosine phosphorylation on PKCδ and subsequent thromboxane generation through tyrosine kinase, Lyn, in platelets.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Satya P Kunapuli
- Satya P. Kunapuli PhD, Department of Physiology and Sol Sherry Thrombosis Center,, Temple University School of Medicine,, 3420 North Broad street, MRB 414, Philadelphia PA, 19140, USA, Tel.: +1 215 707 4615, Fax: +1 215 707 6944, E-mail:
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11
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Chou TC. New mechanisms of antiplatelet activity of nifedipine, an L-type calcium channel blocker. Biomedicine (Taipei) 2014; 4:24. [PMID: 25520937 PMCID: PMC4265014 DOI: 10.7603/s40681-014-0024-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 11/05/2014] [Indexed: 01/03/2023] Open
Abstract
Platelet hyperactivity often occursd in hypertensive patients and is a key factor in the development of cardiovascular diseases including thrombosis and atherosclerosis. Nifedipine, an L-type calcium channel blocker, is widely used for hypertension and coronary heart disease therapy. In addition, nifedipine is known to exhibit an antiplatelet activity, but the underlying mechanisms involved remain unclear. Several transcription factors such as peroxisome proliferator-activated receptors (PPARs) and nuclear factor kappa B (NF-κB) exist in platelets and have an ability to regulate platelet aggregation through a non-genomic mechanism. The present article focuses on describing the mechanisms of the antiplatelet activity of nifedipine via PPAR activation. It has been demonstrated that nifedipine treatment increases the activity and intracellular amount of PPAR-β/-γ in activated platelets. Moreover, the antiplatelet activity of nifedipine is mediated by PPAR-β/-γ-dependent upon the up-regulation of the PI3K/AKT/NO/cyclic GMP/PKG pathway, and inhibition of protein kinase Cα (PKCα) activity via an interaction between PPAR-β/-γ and PKCα. Furthermore, suppressing NF-κB activation by nifedipine through enhanced association of PPAR-β/-γ with NF-κB has also been observed in collagen-stimulated platelets. Blocking PPAR-β/-γ activity or increasing NF-κB activation greatly reverses the antiplatelet activity and inhibition of intracellular Ca2+ mobilization, PKCα activity, and surface glycoprotein IIb/IIIa expression caused by nifedipine. Thus, PPAR-β/-γ- dependent suppression of NF-κB activation also contributes to the antiplatelet activity of nifedipine. Consistently, administration of nifedipine markedly reduces fluorescein sodium-induced vessel thrombus formation in mice, which is considerably inhibited when the PPAR-β/-γ antagonists are administrated simultaneously. Collectively, these results provide important information regarding the mechanism by which nifedipine inhibits platelet aggregation and thrombus formation through activation of PPAR-β/-γ- mediated signaling pathways. These findings highlight that PPARs are novel therapeutic targets for preventing and treating platelet-hyperactivity-related vascular diseases.
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Affiliation(s)
- Tz-Chong Chou
- Institute of Medical Sciences, Tzu Chi University, 6F, Xie-Li Building, No. 707, Sec. 3, Zhongyang Rd.,, 970 Hualien, Taiwan
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12
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Zeiler M, Moser M, Mann M. Copy number analysis of the murine platelet proteome spanning the complete abundance range. Mol Cell Proteomics 2014; 13:3435-45. [PMID: 25205226 PMCID: PMC4256495 DOI: 10.1074/mcp.m114.038513] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Knowledge of the identity and quantity of expressed proteins of a cell type is a prerequisite for a complete understanding of its molecular functions. Mass-spectrometry-based proteomics has allowed the identification of the entire protein complement of yeast and the close-to-complete set of proteins expressed in mammalian cell lines. Using recent technological advances, we here characterized the proteome of murine platelets, key actors in mediating hemostasis and thrombosis. We accurately measured the absolute protein concentrations of 13 platelet proteins using SILAC-protein epitope signature tags and used them as reference points to estimate the copy numbers of all proteins of the platelet proteome. To distinguish contaminants such as plasma or erythrocyte proteins from true platelet proteins, we monitored protein abundance profiles across multiple purification steps. In total, we absolutely quantified 4,400 platelet proteins, with estimated copy numbers ranging from less than 10 to about a million per cell. Stoichiometries derived from our data correspond well with previous studies. Our study provides a close-to-complete reference map of platelet proteins that will be useful to the community, for instance, for interpreting mouse models of human platelet diseases.
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Affiliation(s)
- Marlis Zeiler
- From the ‡Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Markus Moser
- §Department of Molecular Medicine, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Matthias Mann
- From the ‡Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany;
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Calcium-dependent PKC isoforms have specialized roles in short-term synaptic plasticity. Neuron 2014; 82:859-71. [PMID: 24794094 DOI: 10.1016/j.neuron.2014.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2014] [Indexed: 01/04/2023]
Abstract
Posttetanic potentiation (PTP) is a widely observed form of short-term plasticity lasting for tens of seconds after high-frequency stimulation. Here we show that although protein kinase C (PKC) mediates PTP at the calyx of Held synapse in the auditory brainstem before and after hearing onset, PTP is produced primarily by an increased probability of release (p) before hearing onset, and by an increased readily releasable pool of vesicles (RRP) thereafter. We find that these mechanistic differences, which have distinct functional consequences, reflect unexpected differential actions of closely related calcium-dependent PKC isoforms. Prior to hearing onset, when PKCγ and PKCβ are both present, PKCγ mediates PTP by increasing p and partially suppressing PKCβ actions. After hearing onset, PKCγ is absent and PKCβ produces PTP by increasing RRP. In hearing animals, virally expressed PKCγ overrides PKCβ to produce PTP by increasing p. Thus, two similar PKC isoforms mediate PTP in distinctly different ways.
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van den Bosch MTJ, Poole AW, Hers I. Cytohesin-2 phosphorylation by protein kinase C relieves the constitutive suppression of platelet dense granule secretion by ADP-ribosylation factor 6. J Thromb Haemost 2014; 12:726-35. [PMID: 24581425 PMCID: PMC4238808 DOI: 10.1111/jth.12542] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/19/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND Protein kinase C (PKC) is a major regulator of platelet function and secretion. The underlying molecular pathway from PKC to secretion, however, is poorly understood. By a proteomics screen we identified the guanine nucleotide exchange factor cytohesin-2 as a candidate PKC substrate. OBJECTIVES We aimed to validate cytohesin-2 as a PKC substrate in platelets and to determine its role in granule secretion and other platelet responses. METHODS AND RESULTS Immunoprecipitation was performed with a phosphoserine PKC substrate antibody followed by mass spectrometry, leading to the identification of cytohesin-2. By western blotting we showed that different agonists induced cytohesin-2 phosphorylation by PKC. Protein function was investigated using a pharmacological approach. The cytohesin inhibitor SecinH3 significantly enhanced platelet dense granule secretion and aggregation, as measured by lumi-aggregometry. Flow cytometry data indicate that α-granule release and integrin αII b β3 activation were not affected by cytohesin-2 inhibition. Lysosome secretion was assessed by a colorimetric assay and was also unchanged. As shown by western blotting, ARF6 interacted with cytohesin-2 and was present in an active GTP-bound form under basal conditions. Upon platelet stimulation, this interaction was largely lost and ARF6 activation decreased, both of which could be rescued by PKC inhibition. CONCLUSIONS Cytohesin-2 constitutively suppresses platelet dense granule secretion and aggregation by keeping ARF6 in a GTP-bound state. PKC-mediated phosphorylation of cytohesin-2 relieves this inhibitory effect, thereby promoting platelet secretion and aggregation.
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15
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Carubbi C, Mirandola P, Mattioli M, Galli D, Marziliano N, Merlini PA, Lina D, Notarangelo F, Cozzi MR, Gesi M, Ardissino D, De Marco L, Vitale M, Gobbi G. Protein kinase C ε expression in platelets from patients with acute myocardial infarction. PLoS One 2012; 7:e46409. [PMID: 23071564 PMCID: PMC3465320 DOI: 10.1371/journal.pone.0046409] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/29/2012] [Indexed: 01/16/2023] Open
Abstract
Objective Platelets play crucial roles in the pathophysiology of thrombosis and myocardial infarction. Protein kinase C ε (PKCε) is virtually absent in human platelets and its expression is precisely regulated during human megakaryocytic differentiation. On the basis of what is known on the role of platelet PKCε in other species, we hypothesized that platelets from myocardial infarction patients might ectopically express PKCε with a pathophysiological role in the disease. Methods and Results We therefore studied platelet PKCε expression from 24 patients with myocardial infarction, 24 patients with stable coronary artery disease and 24 healthy subjects. Indeed, platelets from myocardial infarction patients expressed PKCε with a significant frequency as compared to both stable coronary artery disease and healthy subjects. PKCε returned negative during patient follow-up. The forced expression of PKCε in normal donor platelets significantly increased their response to adenosine diphosphate-induced activation and adhesion to subendothelial collagen. Conclusions Our data suggest that platelet generations produced before the acute event retain PKCε-mRNA that is not down-regulated during terminal megakaryocyte differentiation. Results are discussed in the perspective of peri-infarctual megakaryocytopoiesis as a critical component of myocardial infarction pathophysiology.
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Affiliation(s)
- Cecilia Carubbi
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Prisco Mirandola
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Maria Mattioli
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | - Daniela Galli
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
| | | | | | - Daniela Lina
- Division of Cardiology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | | | - Maria Rita Cozzi
- Department of Laboratory Medicine, CRO National Cancer Institute, Aviano, Italy
| | - Marco Gesi
- Department of Human Morphology and Applied Biology, University of Pisa, Pisa, Italy
| | - Diego Ardissino
- Division of Cardiology, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | - Luigi De Marco
- Department of Laboratory Medicine, CRO National Cancer Institute, Aviano, Italy
| | - Marco Vitale
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
- * E-mail:
| | - Giuliana Gobbi
- Department of Biomedical, Biotechnological and Translational Sciences, University of Parma, Parma, Italy
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16
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UNSWORTH AJ, FINNEY BA, NAVARRO-NUNEZ L, SEVERIN S, WATSON SP, PEARS CJ. Protein kinase Cε and protein kinase Cθ double-deficient mice have a bleeding diathesis. J Thromb Haemost 2012; 10:1887-94. [PMID: 22812584 PMCID: PMC3532618 DOI: 10.1111/j.1538-7836.2012.04857.x] [Citation(s) in RCA: 8] [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: 06/15/2012] [Accepted: 07/10/2012] [Indexed: 01/24/2023]
Abstract
BACKGROUND In comparison to the classical isoforms of protein kinase C (PKC), the novel isoforms are thought to play minor or inhibitory roles in the regulation of platelet activation and thrombosis. OBJECTIVES To measure the levels of PKCθ and PKCε and to investigate the phenotype of mice deficient in both novel PKC isoforms. METHODS Tail bleeding and platelet activation assays were monitored in mice and platelets from mice deficient in both PKCθ and PKCε. RESULTS PKCε plays a minor role in supporting aggregation and secretion following stimulation of the collagen receptor GPVI in mouse platelets but has no apparent role in spreading on fibrinogen. PKCθ, in contrast, plays a minor role in supporting adhesion and filopodial generation on fibrinogen but has no apparent role in aggregation and secretion induced by GPVI despite being expressed at over 10 times the level of PKCε. Platelets deficient in both novel isoforms have a similar pattern of aggregation downstream of GPVI and spreading on fibrinogen as the single null mutants. Strikingly, a marked reduction in aggregation on collagen under arteriolar shear conditions is observed in blood from the double but not single-deficient mice along with a significant increase in tail bleeding. CONCLUSIONS These results reveal a greater than additive role for PKCθ and PKCε in supporting platelet activation under shear conditions and demonstrate that, in combination, the two novel PKCs support platelet activation.
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Affiliation(s)
- A J UNSWORTH
- Department of Biochemistry, University of OxfordOxford
| | - B A FINNEY
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of BirminghamBirmingham, UK
| | - L NAVARRO-NUNEZ
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of BirminghamBirmingham, UK
| | - S SEVERIN
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of BirminghamBirmingham, UK
| | - S P WATSON
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of BirminghamBirmingham, UK
| | - C J PEARS
- Department of Biochemistry, University of OxfordOxford
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17
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Gundimeda U, McNeill TH, Elhiani AA, Schiffman JE, Hinton DR, Gopalakrishna R. Green tea polyphenols precondition against cell death induced by oxygen-glucose deprivation via stimulation of laminin receptor, generation of reactive oxygen species, and activation of protein kinase Cε. J Biol Chem 2012; 287:34694-708. [PMID: 22879598 DOI: 10.1074/jbc.m112.356899] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
As the development of synthetic drugs for the prevention of stroke has proven challenging, utilization of natural products capable of preconditioning neuronal cells against ischemia-induced cell death would be a highly useful complementary approach. In this study using an oxygen-glucose deprivation and reoxygenation (OGD/R) model in PC12 cells, we show that 2-day pretreatment with green tea polyphenols (GTPP) and their active ingredient, epigallocatechin-3-gallate (EGCG), protects cells from subsequent OGD/R-induced cell death. A synergistic interaction was observed between GTPP constituents, with unfractionated GTPP more potently preconditioning cells than EGCG. GTPP-induced preconditioning required the 67-kDa laminin receptor (67LR), to which EGCG binds with high affinity. 67LR also mediated the generation of reactive oxygen species (ROS) via activation of NADPH oxidase. An exogenous ROS-generating system bypassed 67LR to induce preconditioning, suggesting that sublethal levels of ROS are indeed an important mediator in GTPP-induced preconditioning. This role for ROS was further supported by the fact that antioxidants blocked GTPP-induced preconditioning. Additionally, ROS induced an activation and translocation of protein kinase C (PKC), particularly PKCε from the cytosol to the membrane/mitochondria, which was also blocked by antioxidants. The crucial role of PKC in GTPP-induced preconditioning was supported by use of its specific inhibitors. Preconditioning was increased by conditional overexpression of PKCε and decreased by its knock-out with siRNA. Collectively, these results suggest that GTPP stimulates 67LR and thereby induces NADPH oxidase-dependent generation of ROS, which in turn induces activation of PKC, particularly prosurvival isoenzyme PKCε, resulting in preconditioning against cell death induced by OGD/R.
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Affiliation(s)
- Usha Gundimeda
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA
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18
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Bynagari-Settipalli YS, Lakhani P, Jin J, Bhavaraju K, Rico MC, Kim S, Woulfe D, Kunapuli SP. Protein kinase C isoform ε negatively regulates ADP-induced calcium mobilization and thromboxane generation in platelets. Arterioscler Thromb Vasc Biol 2012; 32:1211-9. [PMID: 22362759 DOI: 10.1161/atvbaha.111.242388] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Members of the protein kinase C (PKC) family are shown to positively and negatively regulate platelet activation. Although positive regulatory roles are extensively studied, negative regulatory roles of PKCs are poorly understood. We investigated the mechanism and specific isoforms involved in PKC-mediated negative regulation of ADP-induced functional responses. METHODS AND RESULTS A pan-PKC inhibitor, GF109203X, potentiated ADP-induced cPLA(2) phosphorylation and thromboxane generation as well as ERK activation and intracellular calcium (Ca(2+)(i)) mobilization, 2 signaling molecules, upstream of cPLA(2) activation. Thus, PKCs inhibit cPLA(2) activation by inhibiting ERK and Ca(2+)(i) mobilization. Because the inhibitor of classic PKC isoforms, GO-6976, did not affect ADP-mediated thromboxane generation, we investigated the role of novel class of PKC isoforms. ADP-induced thromboxane generation, calcium mobilization, and ERK phosphorylation were potentiated in PKCε null murine platelets compared with platelets from wild-type littermates. Interestingly, when thromboxane release is blocked, ADP-induced aggregation in PKCε knockout and wild-type was similar, suggesting that PKCε does not affect ADP-induced aggregation directly. PKCε knockout mice exhibited shorter times to occlusion in an FeCl(3)-induced arterial injury model and shorter bleeding times in tail-bleeding experiments. CONCLUSIONS We conclude that PKCε negatively regulates ADP-induced thromboxane generation in platelets and offers protection against thrombosis.
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19
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Goggs R, Poole AW. Platelet signaling-a primer. J Vet Emerg Crit Care (San Antonio) 2012; 22:5-29. [PMID: 22316389 DOI: 10.1111/j.1476-4431.2011.00704.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 11/25/2011] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To review the receptors and signal transduction pathways involved in platelet plug formation and to highlight links between platelets, leukocytes, endothelium, and the coagulation system. DATA SOURCES Original studies, review articles, and book chapters in the human and veterinary medical fields. DATA SYNTHESIS Platelets express numerous surface receptors. Critical among these are glycoprotein VI, the glycoprotein Ib-IX-V complex, integrin α(IIb) β(3) , and the G-protein-coupled receptors for thrombin, ADP, and thromboxane. Activation of these receptors leads to various important functional events, in particular activation of the principal adhesion receptor α(IIb) β(3) . Integrin activation allows binding of ligands such as fibrinogen, mediating platelet-platelet interaction in the process of aggregation. Signals activated by these receptors also couple to 3 other important functional events, secretion of granule contents, change in cell shape through cytoskeletal rearrangement, and procoagulant membrane expression. These processes generate a stable thrombus to limit blood loss and promote restoration of endothelial integrity. CONCLUSIONS Improvements in our understanding of how platelets operate through their signaling networks are critical for diagnosis of unusual primary hemostatic disorders and for rational antithrombotic drug design.
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Affiliation(s)
- Robert Goggs
- School of Physiology and Pharmacology, Faculty of Medical and Veterinary Sciences, University of Bristol, UK.
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20
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Williams CM, Feng Y, Martin P, Poole AW. Protein kinase C alpha and beta are positive regulators of thrombus formation in vivo in a zebrafish (Danio rerio) model of thrombosis. J Thromb Haemost 2011; 9:2457-65. [PMID: 21951302 DOI: 10.1111/j.1538-7836.2011.04520.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND The zebrafish (Danio rerio) is becoming an attractive model organism for the assessment of gene function in thrombosis in vivo. Zebrafish, as a thrombosis model, have several advantages, with the capacity to follow thrombus formation at high resolution in real time using intravital microscopy, without the need for complex surgical techniques, and the capability to rapidly knockdown gene expression using morpholino antisense approaches. OBJECTIVES We have recently shown, in mouse models, that protein kinase C alpha (PKCα) plays a critical role in regulating thrombus formation in vivo. PKC beta (β) plays a non-redundant role also in platelet function in vitro, but the function of this gene had not yet been assessed in vivo. METHODS In the present study, we analyzed the function of both PKCα and PKCβ in the zebrafish model in vivo, by live imaging using a laser-induced injury of the main caudal artery in 3-day-old larvae. RESULTS We showed that D. rerio express orthologs of both the PKCα and PKCβ genes, with high sequence identity. Translation blocking and splice-blocking morpholinos effectively and specifically knockdown expression of these genes and knockdown with either morpholino leads to attenuated thrombus formation, as assessed by several quantitative parameters including time to initial adhesion and peak thrombus surface area. CONCLUSIONS Our data indicate that these two highly related genes play non-redundant roles in regulating thrombosis, an observation that supports our previous in vitro murine data, and suggests unique roles, and possibly unique regulation, for PKCα and PKCβ in controlling platelet function in vivo.
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Affiliation(s)
- C M Williams
- School of Physiology & Pharmacology, University Walk, Bristol, UK
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21
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Aktan Í, Dunkel B, Cunningham F. PKC isoenzymes in equine platelets and stimulus induced activation. Vet Immunol Immunopathol 2011; 141:276-82. [DOI: 10.1016/j.vetimm.2011.03.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 03/14/2011] [Accepted: 03/21/2011] [Indexed: 12/13/2022]
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22
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Unsworth AJ, Smith H, Gissen P, Watson SP, Pears CJ. Submaximal inhibition of protein kinase C restores ADP-induced dense granule secretion in platelets in the presence of Ca2+. J Biol Chem 2011; 286:21073-82. [PMID: 21489985 PMCID: PMC3122168 DOI: 10.1074/jbc.m110.187138] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Protein kinase C (PKC) is a family of serine/threonine kinases that play isoform-specific inhibitory and stimulatory roles in platelet activation. We show here that the pan-PKC inhibitor Ro31-8220 can be used to dissect these events following platelet activation by ADP. Submaximal concentrations of Ro31-8220 potentiated aggregation and dense granule secretion to ADP in plasma anticoagulated with citrate, in d-Phe-Pro-Arg-chloromethyl ketone-anticoagulated plasma, which has physiological levels of Ca2+, and in washed platelets. Potentiation was retained on inhibition of cyclooxygenase and was associated with an increase in intracellular Ca2+. Potentiation of aggregation and secretion was abolished by a maximally effective concentration of Ro31-8220, consistent with a critical role of PKC in secretion. ADP-induced secretion was potentiated in the presence of an inhibitor of PKCβ but not in the presence of available inhibitors of other PKC isoforms in human and mouse platelets. ADP-induced secretion was also potentiated in mouse platelets deficient in PKCϵ but not PKCθ. These results demonstrate that partial blockade of PKC potentiates aggregation and dense granule secretion by ADP in association with increased Ca2+. This provides a molecular explanation for the inability of ADP to induce secretion in plasma in the presence of physiological Ca2+ concentrations, and it reveals a novel role for PKC in inhibiting platelet activation by ADP in vivo. These results also demonstrate isoform-specific inhibitory effects of PKC in platelets.
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Affiliation(s)
- Amanda J Unsworth
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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23
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Getz TM, Mayanglambam A, Daniel JL, Kunapuli SP. Go6976 abrogates GPVI-mediated platelet functional responses in human platelets through inhibition of Syk. J Thromb Haemost 2011; 9:608-10. [PMID: 21251194 PMCID: PMC3057064 DOI: 10.1111/j.1538-7836.2011.04192.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Todd M. Getz
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, U.S.A
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, U.S.A
| | - Azad Mayanglambam
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, U.S.A
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, U.S.A
| | - James L. Daniel
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, U.S.A
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, U.S.A
| | - Satya P. Kunapuli
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, U.S.A
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, U.S.A
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, U.S.A
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Lai YS, Shih CY, Huang YF, Chou TC. Antiplatelet activity of alpha-lipoic acid. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:8596-8603. [PMID: 20681648 DOI: 10.1021/jf101518p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Alpha-lipoic acid (ALA) is often used as a dietary supplement to prevent and treat chronic diseases associated with excessive oxidative stress. The aim of this study was to investigate the mechanisms of the antiplatelet activity of ALA. ALA significantly inhibited collagen-induced platelet aggregation, thromboxane B(2) (TXB(2)) formation, Ca(2+) mobilization, and protein kinase Calpha (PKCalpha) activation, but ALA itself increased cyclic AMP formation in rabbit washed platelets. However, the effects of ALA on the above platelet responses were markedly reversed by the addition of 2'5'-ddAdo, an adenylate cyclase inhibitor. Additionally, increased reactive oxygen species (ROS) formation and cyclooxygenase-1 activity stimulated by arachidonic acid were inhibited by ALA. In conclusion, we demonstrated that ALA possesses an antiplatelet activity, which may be associated with an elevation of cyclic AMP formation, involving subsequent inhibition of TXA(2), Ca(2+) mobilization, and PKCalpha-mediated pathways. Moreover, inhibition of ROS formation and increase of platelet membrane fluidity may also involve its actions.
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Abstract
Abstract
The role of c-Jun NH2-terminal kinase 1 (JNK1) in hemostasis and thrombosis remains unclear. We show here, with JNK1-deficient (JNK1−/−) mice, that JNK1 plays an important role in platelet biology and thrombus formation. In tail-bleeding assays, JNK1−/− mice exhibited longer bleeding times than wild-type mice (396 ± 39 seconds vs 245 ± 32 seconds). We also carried out in vitro whole-blood perfusion assays on a collagen matrix under arterial shear conditions. Thrombus formation was significantly reduced for JNK1−/− platelets (51%). In an in vivo model of thrombosis induced by photochemical injury to cecum vessels, occlusion times were 4.3 times longer in JNK1−/− arterioles than in wild-type arterioles. Moreover, in vitro studies carried out in platelet aggregation conditions demonstrated that, at low doses of agonists, platelet secretion was impaired in JNK1−/− platelets, leading to altered integrin αIIbβ3 activation and reduced platelet aggregation, via a mechanism involving protein kinase C. JNK1 thus appears to be essential for platelet secretion in vitro, consistent with its role in thrombus growth in vivo. Finally, we showed that ERK2 and another isoform of JNK affect platelet aggregation through 2 pathways, one dependent and another independent of JNK1.
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Harper MT, Poole AW. Protein kinase Ctheta negatively regulates store-independent Ca2+ entry and phosphatidylserine exposure downstream of glycoprotein VI in platelets. J Biol Chem 2010; 285:19865-73. [PMID: 20388711 PMCID: PMC2888397 DOI: 10.1074/jbc.m109.085654] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Platelet activation must be tightly controlled to provide an effective, but not excessive, response to vascular injury. Cytosolic calcium is a critical regulator of platelet function, including granule secretion, integrin activation, and phosphatidylserine (PS) exposure. Here we report that the novel protein kinase C isoform, PKCtheta, plays an important role in negatively regulating Ca(2+) signaling downstream of the major collagen receptor, glycoprotein VI (GPVI). This limits PS exposure and so may prevent excessive platelet procoagulant activity. Stimulation of GPVI resulted in significantly higher and more sustained Ca(2+) signals in PKCtheta(-/-) platelets. PKCtheta acts at multiple distinct sites. PKCtheta limits secretion, reducing autocrine ADP signaling that enhances Ca(2+) release from intracellular Ca(2+) stores. PKCtheta thereby indirectly regulates activation of store-operated Ca(2+) entry. However, PKCtheta also directly and negatively regulates store-independent Ca(2+) entry. This pathway, activated by the diacylglycerol analogue, 1-oleoyl-2-acetyl-sn-glycerol, was enhanced in PKCtheta(-/-) platelets, independently of ADP secretion. Moreover, LOE-908, which blocks 1-oleoyl-2-acetyl-sn-glycerol-induced Ca(2+) entry but not store-operated Ca(2+) entry, blocked the enhanced GPVI-dependent Ca(2+) signaling and PS exposure seen in PKCtheta(-/-) platelets. We propose that PKCtheta normally acts to restrict store-independent Ca(2+) entry during GPVI signaling, which results in reduced PS exposure, limiting platelet procoagulant activity during thrombus formation.
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Affiliation(s)
- Matthew T Harper
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, BS8 1TD Bristol, United Kingdom
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27
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Tseng WL, Huang CL, Chong KY, Liao CH, Stern A, Cheng JC, Tseng CP. Reelin is a platelet protein and functions as a positive regulator of platelet spreading on fibrinogen. Cell Mol Life Sci 2010; 67:641-53. [PMID: 19936619 PMCID: PMC11115871 DOI: 10.1007/s00018-009-0201-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 10/06/2009] [Accepted: 11/02/2009] [Indexed: 12/21/2022]
Abstract
Abnormalities of platelet functions have been linked to reelin-impaired neuronal disorders. However, little attention has been given to understanding the interplay between reelin and platelet. In this study, reelin was found to present in the human platelets and megakaryocyte-like leukemic cells. Reelin-binding assays revealed that extracellular reelin can interact with platelets through the receptor belonging to the low density lipoprotein receptor gene family. The reelin-to-platelet interactions enhance platelet spreading on fibrinogen concomitant with the augmentation of lamellipodia formation and F-actin bundling. In contrast, reelin has no effect on integrin alphaIIbbeta3 activation and agonist-induced platelet aggregation. Molecular analysis revealed that the up-regulation of Rac1 activity and the inhibition of protein kinase C delta-Thr505 phosphorylation are important for reelin-mediated enhancement of platelet spreading on fibrinogen. These findings demonstrate for the first time that reelin is present in platelets and the reelin-to-platelet interactions play a novel role in platelet signaling and functions.
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Affiliation(s)
- Wei-Lien Tseng
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kweishan, Taoyuan, 333 Taiwan, ROC
| | - Chien-Ling Huang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, 259 Wen-Hwa 1st Road, Kweishan, Taoyuan, 333 Taiwan, ROC
| | - Kowit-Yu Chong
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, 259 Wen-Hwa 1st Road, Kweishan, Taoyuan, 333 Taiwan, ROC
| | - Chang-Huei Liao
- Graduate Institute of Natural Products, Chang Gung University, Kweishan, Taoyuan, 333 Taiwan, ROC
| | - Arnold Stern
- Department of Pharmacology, New York University School of Medicine, New York, NY USA
| | - Ju-Chien Cheng
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, 404 Taiwan, ROC
| | - Ching-Ping Tseng
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kweishan, Taoyuan, 333 Taiwan, ROC
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, 259 Wen-Hwa 1st Road, Kweishan, Taoyuan, 333 Taiwan, ROC
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28
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Jackson SP, Schoenwaelder SM. PI 3-Kinase p110β regulation of platelet integrin α(IIb)β3. Curr Top Microbiol Immunol 2010; 346:203-24. [PMID: 20517720 DOI: 10.1007/82_2010_61] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hemopoietic cells express relatively high levels of the type I phosphoinositide (PI) 3-kinase isoforms, with p110δ and γ exhibiting specialized signaling functions in neutrophils, monocytes, mast cells, and lymphocytes. In platelets, p110β appears to be the dominant PI 3-kinase isoform regulating platelet activation, irrespective of the nature of the primary platelet activating stimulus. Based on findings with isoform-selective p110β pharmacological inhibitors and more recently with p110β-deficient platelets, p110β appears to primarily signal downstream of G(i)- and tyrosine kinase-coupled receptors. Functionally, inhibition of p110β kinase function leads to a marked defect in integrin α(IIb)β₃ adhesion and reduced platelet thrombus formation in vivo. This defect in platelet adhesive function is not associated with increased bleeding, suggesting that therapeutic targeting of p110β may represent a safe approach to reduce thrombotic complications in patients with cardiovascular disease.
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Affiliation(s)
- Shaun P Jackson
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, VIC, 3004, Australia.
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29
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Protein kinase Calpha: disease regulator and therapeutic target. Trends Pharmacol Sci 2009; 31:8-14. [PMID: 19969380 PMCID: PMC2809215 DOI: 10.1016/j.tips.2009.10.006] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 10/16/2009] [Accepted: 10/19/2009] [Indexed: 12/28/2022]
Abstract
Protein kinase Cα (PKCα) is a member of the AGC (which includes PKD, PKG and PKC) family of serine/threonine protein kinases that is widely expressed in mammalian tissues. It is closely related in structure, function and regulation to other members of the protein kinase C family, but has specific functions within the tissues in which it is expressed. There is substantial recent evidence, from gene knockout studies in particular, that PKCα activity regulates cardiac contractility, atherogenesis, cancer and arterial thrombosis. Selective targeting of PKCα therefore has potential therapeutic value in a wide variety of disease states, although will be technically complicated by the ubiquitous expression and multiple functions of the molecule.
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30
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Fortuño A, Bidegain J, Robador PA, Hermida J, López-Sagaseta J, Beloqui O, Díez J, Zalba G. Losartan metabolite EXP3179 blocks NADPH oxidase-mediated superoxide production by inhibiting protein kinase C: potential clinical implications in hypertension. Hypertension 2009; 54:744-50. [PMID: 19687351 DOI: 10.1161/hypertensionaha.109.129353] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Oxidative stress plays a critical role in the pathogenesis of hypertension. The NADPH oxidase constitutes a major source of superoxide anion in phagocytic cells, and its activation is associated with matrix metalloproteinase (MMP)-9 secretion by these cells. We investigated the effects of the angiotensin II type 1 receptor antagonist losartan and its metabolites (EXP3174 and EXP3179) on NADPH oxidase activity and MMP-9 secretion in human phagocytic cells. EXP3179, but not losartan and EXP3174, dose-dependently inhibited (P<0.05) phorbol myristate acetate and insulin-stimulated NADPH oxidase activity. EXP3179 also inhibited phorbol myristate acetate-induced NADPH oxidase in endothelial cells. In addition, EXP3179 inhibited (P<0.05) both phorbol myristate acetate-stimulated p47phox translocation from cytosol to membranes and protein kinase C activity. Affinity experiments and enzymatic assays confirmed that EXP3179 inhibited several protein kinase C isoforms. EXP3179 also inhibited (P<0.05) phorbol myristate acetate-stimulated MMP-9 secretion. In a study performed in 153 hypertensive patients, phagocytic NADPH oxidase activity was lower (P<0.05) in losartan-treated compared with untreated patients and in patients treated with other angiotensin II type 1 receptor antagonists or with angiotensin-converting enzyme inhibitors. Plasma levels of MMP-9 were lower (P<0.05) in losartan-treated hypertensives compared with the other group of patients. Thus, EXP3179 acts as a blocker of the NADPH oxidase in phagocytic cells by a potential mechanism that targets the protein kinase C signaling pathway. This effect can be involved in reduced MMP-9 secretion by these cells. It is proposed that the EXP3179 metabolite may confer to losartan the specific capacity to reduce oxidative stress mediated by phagocytic cells in hypertensive patients.
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Affiliation(s)
- Ana Fortuño
- Center for Applied Medical Research, Pio XII 55, Pamplona, Spain.
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31
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Brooks AC, Menzies-Gow NJ, Wheeler-Jones CPD, Bailey SR, Elliott J, Cunningham FM. Regulation of platelet activating factor-induced equine platelet activation by intracellular kinases. J Vet Pharmacol Ther 2009; 32:189-96. [PMID: 19290950 DOI: 10.1111/j.1365-2885.2008.01020.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Lipopolysaccharide (LPS) can activate equine platelets directly or indirectly, via leukocyte-derived platelet activating factor (PAF). Thromboxane (Tx) production by LPS-stimulated equine platelets requires p38 MAPK and this kinase has been suggested as a therapeutic target in endotoxaemia. The present study has utilised selective inhibitors to investigate the role of p38 MAPK and two other kinases, phosphatidylinositol-3 kinase (PI3K) and protein kinase C (PKC), in regulating PAF-induced Tx production, aggregation and 5-HT release in equine platelets, and the modification of these responses by LPS. LPS enhanced PAF-induced 5-HT release, an effect that was reduced by the p38 MAPK inhibitor, SB203580 (60 +/- 8% reduction; n = 6). SB203580 did not affect responses to PAF alone; whereas inhibition of PKC reduced PAF-induced 5-HT release, Tx production and aggregation (maximal inhibition by the PKCdelta inhibitor, rottlerin: 69 +/- 13%, 63 +/- 14% and 97 +/- 1%, respectively; n = 6). Wortmannin and LY249002, which inhibit PI3K, also caused significant inhibition of PAF-induced aggregation (maximal inhibition 78 +/- 3% and 88 +/- 2%, respectively; n = 6). These data suggest that inhibition of platelet p38 MAPK may be of benefit in equine endotoxaemia by counteracting some of the effects of LPS. However, detrimental effects of platelet activation mediated by PAF and not enhanced by LPS are unlikely to be markedly affected.
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Affiliation(s)
- A C Brooks
- Department of Veterinary Basic Sciences, Royal Veterinary College, Hertfordshire, UK.
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32
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33
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Abstract
The importance of the second messengers calcium (Ca(2+)) and diacylglycerol (DAG) in platelet signal transduction was established more than 30 years ago. Whereas protein kinase C (PKC) family members were discovered as the targets of DAG, little is known about the molecular identity of the main Ca(2+) sensor(s). We here identify Ca(2+) and DAG-regulated guanine nucleotide exchange factor I (CalDAG-GEFI) as a critical molecule in Ca(2+)-dependent platelet activation. CalDAG-GEFI, through activation of the small GTPase Rap1, directly triggers integrin activation and extracellular signal-regulated kinase-dependent thromboxane A(2) (TxA(2)) release. CalDAG-GEFI-dependent TxA(2) generation provides crucial feedback for PKC activation and granule release, particularly at threshold agonist concentrations. PKC/P2Y12 signaling in turn mediates a second wave of Rap1 activation, necessary for sustained platelet activation and thrombus stabilization. Our results lead to a revised model for platelet activation that establishes one molecule, CalDAG-GEFI, at the nexus of Ca(2+)-induced integrin activation, TxA(2) generation, and granule release. The preferential activation of CalDAG-GEFI over PKC downstream of phospholipase C activation, and the different kinetics of CalDAG-GEFI- and PKC/P2Y12-mediated Rap1 activation demonstrate an unexpected complexity to the platelet activation process, and they challenge the current model that DAG/PKC-dependent signaling events are crucial for the initiation of platelet adhesion.
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34
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Abstract
Protein kinase C (PKC) isoforms have been implicated in several platelet functional responses, but the contribution of individual isoforms has not been thoroughly evaluated. Novel PKC isoform PKC-theta is activated by glycoprotein VI (GPVI) and protease-activated receptor (PAR) agonists, but not by adenosine diphosphate. In human platelets, PKC-theta-selective antagonistic (RACK; receptor for activated C kinase) peptide significantly inhibited GPVI and PAR-induced aggregation, dense and alpha-granule secretion at low agonist concentrations. Consistently, in murine platelets lacking PKC-theta, platelet aggregation and secretion were also impaired. PKC-mediated phosphorylation of tSNARE protein syntaxin-4 was strongly reduced in human platelets pretreated with PKC-theta RACK peptide, which may contribute to the lower levels of granule secretion when PKC-theta function is lost. Furthermore, the level of JON/A binding to activated alpha(IIb)beta(3) receptor was also significantly decreased in PKC-theta(-/-) mice compared with wild-type littermates. PKC-theta(-/-) murine platelets showed significantly lower agonist-induced thromboxane A(2) (TXA(2)) release through reduced extracellular signal-regulated kinase phosphorylation. Finally, PKC-theta(-/-) mice displayed unstable thrombus formation and prolonged arterial occlusion in the FeCl(3) in vivo thrombosis model compared with wild-type mice. In conclusion, PKC-theta isoform plays a significant role in platelet functional responses downstream of PAR and GPVI receptors.
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Konopatskaya O, Gilio K, Harper MT, Zhao Y, Cosemans JMEM, Karim ZA, Whiteheart SW, Molkentin JD, Verkade P, Watson SP, Heemskerk JWM, Poole AW. PKCalpha regulates platelet granule secretion and thrombus formation in mice. J Clin Invest 2009; 119:399-407. [PMID: 19147982 DOI: 10.1172/jci34665] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 12/03/2008] [Indexed: 12/21/2022] Open
Abstract
Platelets are central players in atherothrombosis development in coronary artery disease. The PKC family provides important intracellular mechanisms for regulating platelet activity, and platelets express several members of this family, including the classical isoforms PKCalpha and PKCbeta and novel isoforms PKCdelta and PKCtheta. Here, we used a genetic approach to definitively demonstrate the role played by PKCalpha in regulating thrombus formation and platelet function. Thrombus formation in vivo was attenuated in Prkca-/- mice, and PKCalpha was required for thrombus formation in vitro, although this PKC isoform did not regulate platelet adhesion to collagen. The ablation of in vitro thrombus formation in Prkca-/- platelets was rescued by the addition of ADP, consistent with the key mechanistic finding that dense-granule biogenesis and secretion depend upon PKCalpha expression. Furthermore, defective platelet aggregation in response to either collagen-related peptide or thrombin could be overcome by an increase in agonist concentration. Evidence of overt bleeding, including gastrointestinal and tail bleeding, was not seen in Prkca-/- mice. In summary, the effects of PKCalpha ablation on thrombus formation and granule secretion may implicate PKCalpha as a drug target for antithrombotic therapy.
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Affiliation(s)
- Olga Konopatskaya
- Department of Physiology & Pharmacology, School of Medical Sciences, University of Bristol, Bristol, United Kingdom
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36
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Hall KJ, Harper MT, Gilio K, Cosemans JM, Heemskerk JWM, Poole AW. Genetic analysis of the role of protein kinase Ctheta in platelet function and thrombus formation. PLoS One 2008; 3:e3277. [PMID: 18815612 PMCID: PMC2533697 DOI: 10.1371/journal.pone.0003277] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 09/05/2008] [Indexed: 12/12/2022] Open
Abstract
Background PKCθ is a novel protein kinase C isozyme, predominately expressed in T cells and platelets. PKCθ−/− T cells exhibit reduced activation and PKCθ−/− mice are resistant to autoimmune disease, making PKCθ an attractive therapeutic target for immune modulation. Collagen is a major agonist for platelets, operating through an immunoreceptor-like signalling pathway from its receptor GPVI. Although it has recently been shown that PKCθ positively regulates outside-in signalling through integrin αIIbβ3 in platelets, the role of PKCθ in GPVI-dependent signalling and functional activation of platelets has not been assessed. Methodology/Principal Findings In the present study we assessed static adhesion, cell spreading, granule secretion, integrin αIIbβ3 activation and platelet aggregation in washed mouse platelets lacking PKCθ. Thrombus formation on a collagen-coated surface was assessed in vitro under flow. PKCθ−/− platelets exhibited reduced static adhesion and filopodia generation on fibrinogen, suggesting that PKCθ positively regulates outside-in signalling, in agreement with a previous report. In contrast, PKCθ−/− platelets also exhibited markedly enhanced GPVI-dependent α-granule secretion, although dense granule secretion was unaffected, suggesting that PKCθ differentially regulates these two granules. Inside-out regulation of αIIbβ3 activation was also enhanced downstream of GPVI stimulation. Although this did not result in increased aggregation, importantly thrombus formation on collagen under high shear (1000 s−1) was enhanced. Conclusions/Significance These data suggest that PKCθ is an important negative regulator of thrombus formation on collagen, potentially mediated by α-granule secretion and αIIbβ3 activation. PKCθ therefore may act to restrict thrombus growth, a finding that has important implications for the development and safe clinical use of PKCθ inhibitors.
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Affiliation(s)
- Kellie J. Hall
- Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Matthew T. Harper
- Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Karen Gilio
- Department of Biochemistry, University of Maastricht, Maastricht, The Netherlands
| | - Judith M. Cosemans
- Department of Biochemistry, University of Maastricht, Maastricht, The Netherlands
| | | | - Alastair W. Poole
- Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- * E-mail:
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