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Yan R, Xia Y, Zhou K, Liu J, Sun Y, He C, Ge X, Yang M, Sun C, Yuan L, Li S, Yang B, Meng F, Cao L, Ruan C, Dai K. Essential role of glycoprotein Ibα in platelet activation. Blood Adv 2024; 8:3388-3401. [PMID: 38701351 PMCID: PMC11255362 DOI: 10.1182/bloodadvances.2023012308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 04/03/2024] [Accepted: 04/16/2024] [Indexed: 05/05/2024] Open
Abstract
ABSTRACT Glycoprotein Ibα (GPIbα), the ligand-binding subunit of platelet GPIb-IX complex, interacts with von Willebrand factor (VWF) exposed at the injured vessel wall, initiating platelet adhesion, activation, hemostasis, and thrombus formation. The cytoplasmic tail of GPIbα interacts with 14-3-3ζ, regulating the VWF-GPIbα-elicited signal transduction and VWF binding function of GPIbα. However, we unexpectedly found that the GPIbα-14-3-3ζ association, beyond VWF-dependent function, is essential for general platelet activation. We found that the myristoylated peptide of GPIbα C-terminus MPαC, a potential GPIbα inhibitor, by itself induced platelet aggregation, integrin αIIbβ3 activation, granule secretion, and phosphatidylserine (PS) exposure. Conversely, the deletion of the cytoplasmic tail of GPIbα in mouse platelets (10aa-/-) decreased platelet aggregation, integrin αIIbβ3 activation, granule secretion, and PS exposure induced by various physiological agonists. Phosphoproteome-based kinase activity profiling revealed significantly upregulated protein kinase C (PKC) activity in MPαC-treated platelets. MPαC-induced platelet activation was abolished by the pan-PKC inhibitor and PKCα deletion. Decreased PKC activity was observed in both resting and agonist-stimulated 10aa-/- platelets. GPIbα regulates PKCα activity by sequestering 14-3-3ζ from PKCα. In vivo, the deletion of the GPIbα cytoplasmic tail impaired mouse hemostasis and thrombus formation and protected against platelet-dependent pulmonary thromboembolism. Therefore, our findings demonstrate an essential role for the GPIbα cytoplasmic tail in regulating platelet general activation and thrombus formation beyond the VWF-GPIbα axis.
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Affiliation(s)
- Rong Yan
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Yue Xia
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Kangxi Zhou
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Jun Liu
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Yueyue Sun
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Chunyan He
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Xinxin Ge
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Mengnan Yang
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Chenglin Sun
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Liuxia Yuan
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Shujun Li
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Biao Yang
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Fanbi Meng
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Lijuan Cao
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Changgeng Ruan
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
| | - Kesheng Dai
- Jiangsu Institute of Hematology, Cyrus Tang Medical Institute, The First Affiliated Hospital and Collaborative Innovation Center of Hematology, Soochow University, Key Laboratory of Thrombosis and Hemostasis, Ministry of Health, National Clinical Research Center for Hematological Diseases, Suzhou, China
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Li X, Zhao K, Lu Y, Wang J, Yao W. Genetic Analysis of Platelet-Related Genes in Hepatocellular Carcinoma Reveals a Novel Prognostic Signature and Determines PRKCD as the Potential Molecular Bridge. Biol Proced Online 2022; 24:22. [PMID: 36463115 PMCID: PMC9719151 DOI: 10.1186/s12575-022-00185-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 11/23/2022] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Hepatocellular carcinoma (HCC) belongs to a representative lethality gastrointestinal malignancy, and comprehensive management of HCC remains intractable at present on account of its invasive biological feature that is easy to relapse and early metastasis. The intimate connection between platelets and tumor progression has been widely reported, and platelet-related indicators are also used in the clinical practice of carcinoma. This work is designed to investigate the significance of platelet-related genes in the prognostic prediction of patients with HCC and their potential role in the cross-talk between HCC cells and platelets in the tumor microenvironment. METHODS By integrating the RNA-seq data and clinicopathological information of HCC patients, we extracted prognosis-associated platelet-related genes based on the univariate cox analysis and further established a relevant prognostic signature via the lasso cox regression analysis, and two independent HCC cohorts were used as external validation. Multiple bioinformatics methods were utilized to explore the underlying functional discrepancy between different risk groups classified by the risk model. And in vitro proliferation, invasion, and migration assays were conducted to investigate the effect of platelet stimulation on HCC cells' viability and motility, and flow cytometric analysis was exerted to demonstrate the influence of HCC cells on platelet activation. RESULTS A novel platelet-related risk model was developed and patients both in the training and testing cohorts were divided into distinct risk subgroups according to the median risk score. It was observed that the high-risk status was closely associated with poor prognosis and worse clinicopathological parameters. Meanwhile, an obvious discrepancy in the constitution of the immune microenvironment also indicated that distinct immune status might be a potential determinant affecting prognosis as well as immunotherapy reactiveness. Moreover, in vitro experiments demonstrated that PRKCD could act as a molecular bridge between tumor cells and platelets, which could either participate in regulating tumor malignant phenotype or mediating platelet activation. CONCLUSIONS In brief, this work reveals a novel platelet-related risk signature for prognostic evaluation of HCC patients and confirms that PRKCD is a key messenger in HCC cell-platelet interaction and plays a crucial role in mediating platelet-induced tumor progression.
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Affiliation(s)
- Xiangyu Li
- Department of Biliary and Pancreatic Surgery/Cancer Research Center Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Kai Zhao
- Department of Biliary and Pancreatic Surgery/Cancer Research Center Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Yun Lu
- Department of Biliary and Pancreatic Surgery/Cancer Research Center Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China
| | - Jianming Wang
- Department of Biliary and Pancreatic Surgery/Cancer Research Center Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
- Affiliated Tianyou Hospital, Wuhan University of Science & Technology, Wuhan, 430064, China.
| | - Wei Yao
- Department of Oncology Affiliated Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei, China.
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Gu W, Qi J, Zhang S, Ding Y, Qiao J, Han Y. Inhibition of HIF prolyl hydroxylase modulates platelet function. Thromb Haemost 2022; 122:1693-1705. [PMID: 35477177 DOI: 10.1055/a-1837-7797] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hypoxia-inducible factors-1α (HIF-1α) involves in redox reaction. Considering the role of reactive oxygen species (ROS) in platelet function, whether it regulates platelet function remains unclear. Using an inhibitor of HIF prolyl hydroxylase IOX-2, we intend to investigate its effect on platelet function. Human platelets were treated with IOX-2 (0, 10, 25, and 50 M) followed by analysis of platelet aggregation, granule secretion, receptor expression, platelet spreading or clot retraction. Additionally, IOX-2 (10 mg/kg) was injected intraperitoneally into mice to measure tail bleeding time and arterial thrombosis. IOX-2 significantly inhibited collagen-related peptide (CRP, 0.25 μg/ml) or thrombin (0.03 U/ml)-induced platelet aggregation and ATP release dose dependently without affecting P-selectin expression and the surface levels of glycoprotein (GP)Ib, GPVI or IIb3. In addition, IOX-2-treated platelets presented significantly decreased spreading on fibrinogen or collagen and clot retraction. Moreover, IOX-2 administration into mice significantly impaired the in vivo hemostatic function of platelets and arterial thrombus formation without affecting the number of circulating platelets and coagulation factor (FVIII and FIX). Further, IOX-2 significantly upregulated HIF-1 in platelets, decreased ROS generation and downregulated NOX1 expression. Finally, IOX-2 increased the phosphorylation level of VASP (Ser157/239), and inhibited the phosphorylation of p38 (Thr180/Tyr182), ERK1/2 (Thr202/Tyr204), AKT (Thr308/Ser473) and PKC (Thr505) in CRP- or thrombin-stimulated platelets. In conclusion, inhibition of HIF prolyl hydroxylase modulates platelet function and arterial thrombus formation, possibly through upregulation of HIF-1α expression and subsequent inhibition of ROS generation, indicating that HIF-1α might be a novel target for the treatment of thrombotic disorders.
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Wang L, Liu G, Wu N, Dai B, Han S, Liu Q, Huang F, Chen Z, Xu W, Xia D, Gao C. mTOR regulates GPVI-mediated platelet activation. J Transl Med 2021; 19:201. [PMID: 33971888 PMCID: PMC8111939 DOI: 10.1186/s12967-021-02756-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/16/2021] [Indexed: 11/10/2022] Open
Abstract
Background Due to mTOR (mammalian/mechanistic target of rapamycin) gene-loss mice die during embryonic development, the role of mTOR in platelets has not been evaluated using gene knockout technology. Methods A mouse model with megakaryocyte/platelet-specific deletion of mTOR was established, and be used to evaluate the role of mTOR in platelet activation and thrombus formation. Results mTOR−/− platelets were deficient in thrombus formation when grown on low-concentration collagen-coated surfaces; however, no deficiency in thrombus formation was observed when mTOR−/− platelets were perfused on higher concentration collagen-coated surfaces. In FeCl3-induced mouse mesenteric arteriole thrombosis models, wild-type (WT) and mTOR−/− mice displayed significantly different responses to low-extent injury with respect to the ratio of occluded mice, especially within the first 40 min. Additionally, mTOR−/− platelets displayed reduced aggregation and dense granule secretion (ATP release) in response to low doses of the glycoprotein VI (GPVI) agonist collagen related peptide (CRP) and the protease-activated receptor-4 (PAR4) agonist GYPGKF-NH2; these deficiencies were overcame by stimulation with higher concentration agonists, suggesting dose dependence of the response. At low doses of GPVI or PAR agonist, the activation of αIIbβ3 in mTOR−/− platelets was reduced. Moreover, stimulation of mTOR−/− platelets with low-dose CRP attenuated the phosphorylation of S6K1, S6 and Akt Ser473, and increased the phosphorylation of PKCδ Thr505 and PKCε Ser729. Using isoform-specific inhibitors of PKCs (δ, ɛ, and α/β), we established that PKCδ/ɛ, and especially PKCδ but not PKCα/β or PKCθ, may be involved in low-dose GPVI-mediated/mTOR-dependent signaling. Conclusion These observations indicate that mTOR plays an important role in GPVI-dependent platelet activation and thrombus formation.
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Affiliation(s)
- Longsheng Wang
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Gang Liu
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China.,Department of Pharmacology, School of Basic Medical Sciences, Guizhou Medical University, Guiyang, Guizhou, China
| | - Nannan Wu
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Baiyun Dai
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Shuang Han
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Qiaoyun Liu
- Department of Toxicology, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Fang Huang
- Department of Toxicology, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Zhihua Chen
- Department of Respiratory Medicine, Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, China
| | - Weihong Xu
- Zhejiang Hospital, 12 Lingyin Road, Hangzhou, 310013, China
| | - Dajing Xia
- Department of Toxicology, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China
| | - Cunji Gao
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, 866 Yu-Hang-Tang Road, Hangzhou, 310058, China. .,Blood Research Institute, Blood Center of Wisconsin, Milwaukee, Milwaukee, WI, 53201, USA.
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5
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Kostyak JC, Mauri B, Patel A, Dangelmaier C, Reddy H, Kunapuli SP. Phosphorylation of protein kinase Cδ Tyr311 positively regulates thromboxane generation in platelets. J Biol Chem 2021; 296:100720. [PMID: 33932405 PMCID: PMC8164046 DOI: 10.1016/j.jbc.2021.100720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 11/19/2022] Open
Abstract
Platelets are key mediators of physiological hemostasis and pathological thrombosis, whose function must be carefully balanced by signaling downstream of receptors such as protease-activated receptor (PAR)4. Protein kinase C (PKC) is known to regulate various aspects of platelet function. For instance, PKCδ is known to regulate dense granule secretion, which is important for platelet activation. However, the mechanism by which PKCδ regulates this process as well as other facets of platelet activity is unknown. We speculated that the way PKCδ regulates platelet function may be because of the phosphorylation of tyrosine residues on PKCδ. We investigated phosphorylation of PKCδ following glycoprotein VI-mediated and PAR4-mediated platelet activation and found that Y311 is selectively phosphorylated when PAR4 is activated in human platelets. Therefore, we generated PKCδ Y311F knock-in mice, which are viable and have no gross abnormalities. However, PKCδY311F mice have significantly enhanced tail-bleeding times compared with WT littermate controls, which means hemostasis is interrupted. Furthermore, PKCδY311F mice exhibit longer time to carotid artery occlusion compared with WT control using a ferric chloride in vivo thrombosis model, indicating that the phosphorylation of PKCδ Y311 is prothrombotic. Washed platelets from PKCδY311F mice have reduced reactivity after stimulation with a PAR-4 agonist indicating its importance in platelet signaling. The phenotype observed in Y311F mouse platelets is because of reduced thromboxane generation, as an inhibitor of thromboxane generation equalizes the PKCδY311F platelet response to that of WT. Therefore, phosphorylation of PKCδ on Y311 is important for regulation of platelet function and specifically thromboxane generation, which reinforces platelet activation.
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Affiliation(s)
- John C Kostyak
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Benjamin Mauri
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Akruti Patel
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Carol Dangelmaier
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Haritha Reddy
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA; Department of Physiology, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA; Department of Pharmacology, Temple University School Lewis M Katz School of Medicine, Philadelphia, Pennsylvania, USA.
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6
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Zaid Y, Puhm F, Allaeys I, Naya A, Oudghiri M, Khalki L, Limami Y, Zaid N, Sadki K, Ben El Haj R, Mahir W, Belayachi L, Belefquih B, Benouda A, Cheikh A, Langlois MA, Cherrah Y, Flamand L, Guessous F, Boilard E. Platelets Can Associate with SARS-Cov-2 RNA and Are Hyperactivated in COVID-19. Circ Res 2020; 127:1404-1418. [PMID: 32938299 PMCID: PMC7641188 DOI: 10.1161/circresaha.120.317703] [Citation(s) in RCA: 349] [Impact Index Per Article: 87.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 12/15/2022]
Abstract
Rationale: In addition to the overwhelming lung inflammation that prevails in COVID-19, hypercoagulation and thrombosis contribute to the lethality of subjects infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Platelets are chiefly implicated in thrombosis. Moreover, they can interact with viruses and are an important source of inflammatory mediators. While a lower platelet count is associated with severity and mortality, little is known about platelet function during COVID-19. Objective: To evaluate the contribution of platelets to inflammation and thrombosis in COVID-19 patients. Methods and Results: Blood was collected from 115 consecutive COVID-19 patients presenting non-severe (n=71) and severe (n=44) respiratory symptoms. We document the presence of SARS-CoV-2 RNA associated with platelets of COVID-19 patients. Exhaustive assessment of cytokines in plasma and in platelets revealed the modulation of platelet-associated cytokine levels in both non-severe and severe COVID-19 patients, pointing to a direct contribution of platelets to the plasmatic cytokine load. Moreover, we demonstrate that platelets release their alpha- and dense-granule contents in both non-severe and severe forms of COVID-19. In comparison to concentrations measured in healthy volunteers, phosphatidylserine-exposing platelet extracellular vesicles were increased in non-severe, but not in severe cases of COVID-19. Levels of D-dimers, a marker of thrombosis, failed to correlate with any measured indicators of platelet activation. Functionally, platelets were hyperactivated in COVID-19 subjects presenting non-severe and severe symptoms, with aggregation occurring at suboptimal thrombin concentrations. Furthermore, platelets adhered more efficiently onto collagen-coated surfaces under flow conditions. Conclusions: Taken together, the data suggest that platelets are at the frontline of COVID-19 pathogenesis, as they release various sets of molecules through the different stages of the disease. Platelets may thus have the potential to contribute to the overwhelming thrombo-inflammation in COVID-19, and the inhibition of pathways related to platelet activation may improve the outcomes during COVID-19.
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Affiliation(s)
- Younes Zaid
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
- Biology, Faculty of Sciences, Mohammed V University, Rabat, Morocco (Y.Z., N.Z., K.S.)
- Immunology and Biodiversity Laboratory, Biology, Faculty of Sciences Ain Chock, Hassan II University, Casablanca, Morocco (Y.Z., A.N., M.O., Y.L.)
| | - Florian Puhm
- Centre de Recherche du Centre Hospitalier Universitaire de Québec- Université Laval, Canada (F.P., I.A., L.F., E.B.)
- Département de microbiologie-infectiologie et d’immunologie, Université Laval, QC, Canada (F.P., I.A., L.F., E.B.)
| | - Isabelle Allaeys
- Centre de Recherche du Centre Hospitalier Universitaire de Québec- Université Laval, Canada (F.P., I.A., L.F., E.B.)
- Département de microbiologie-infectiologie et d’immunologie, Université Laval, QC, Canada (F.P., I.A., L.F., E.B.)
| | - Abdallah Naya
- Immunology and Biodiversity Laboratory, Biology, Faculty of Sciences Ain Chock, Hassan II University, Casablanca, Morocco (Y.Z., A.N., M.O., Y.L.)
| | - Mounia Oudghiri
- Immunology and Biodiversity Laboratory, Biology, Faculty of Sciences Ain Chock, Hassan II University, Casablanca, Morocco (Y.Z., A.N., M.O., Y.L.)
| | - Loubna Khalki
- Faculty of Medicine, Mohammed VI University of Health Sciences (UM6SS), Casablanca, Morocco (L.K., F.G.)
| | - Youness Limami
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
- Immunology and Biodiversity Laboratory, Biology, Faculty of Sciences Ain Chock, Hassan II University, Casablanca, Morocco (Y.Z., A.N., M.O., Y.L.)
| | - Nabil Zaid
- Biology, Faculty of Sciences, Mohammed V University, Rabat, Morocco (Y.Z., N.Z., K.S.)
| | - Khalid Sadki
- Biology, Faculty of Sciences, Mohammed V University, Rabat, Morocco (Y.Z., N.Z., K.S.)
| | - Rafiqua Ben El Haj
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Wissal Mahir
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Lamiae Belayachi
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Bouchra Belefquih
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Amina Benouda
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Amine Cheikh
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Marc-André Langlois
- Biochemistry, Microbiology & Immunology, Faculty of Medicine, University of Ottawa, Canada (M.-A.L.)
| | - Yahia Cherrah
- Research Center of Abulcasis University of Health Sciences, Cheikh Zaïd Hospital, Rabat, Morocco (Y.Z., Y.L., R.B.E.H., W.M., L.B., B.B., A.B., A.C., Y.C.)
| | - Louis Flamand
- Centre de Recherche du Centre Hospitalier Universitaire de Québec- Université Laval, Canada (F.P., I.A., L.F., E.B.)
- Département de microbiologie-infectiologie et d’immunologie, Université Laval, QC, Canada (F.P., I.A., L.F., E.B.)
| | - Fadila Guessous
- Faculty of Medicine, Mohammed VI University of Health Sciences (UM6SS), Casablanca, Morocco (L.K., F.G.)
- Microbiology, Immunology and Cancer Biology, School of Medicine, University of Virginia, Charlottesville (F.G.)
| | - Eric Boilard
- Centre de Recherche du Centre Hospitalier Universitaire de Québec- Université Laval, Canada (F.P., I.A., L.F., E.B.)
- Département de microbiologie-infectiologie et d’immunologie, Université Laval, QC, Canada (F.P., I.A., L.F., E.B.)
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Ether lipid metabolism by AADACL1 regulates platelet function and thrombosis. Blood Adv 2020; 3:3818-3828. [PMID: 31770438 DOI: 10.1182/bloodadvances.2018030767] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 09/28/2019] [Indexed: 12/25/2022] Open
Abstract
We previously reported the discovery of a novel lipid deacetylase in platelets, arylacetamide deacetylase-like 1 (AADACL1/NCEH1), and that its inhibition impairs agonist-induced platelet aggregation, Rap1 GTP loading, protein kinase C (PKC) activation, and ex vivo thrombus growth. However, precise mechanisms by which AADACL1 impacts platelet signaling and function in vivo are currently unknown. Here, we demonstrate that AADACL1 regulates the accumulation of ether lipids that impact PKC signaling networks crucial for platelet activation in vitro and in vivo. Human platelets treated with the AADACL1 inhibitor JW480 or the AADACL1 substrate 1-O-hexadecyl-2-acetyl-sn-glycerol (HAG) exhibited decreased platelet aggregation, granule secretion, Ca2+ flux, and PKC phosphorylation. Decreased aggregation and secretion were rescued by exogenous adenosine 5'-diphosphate, indicating that AADACL1 likely functions to induce dense granule secretion. Experiments with P2Y12-/- and CalDAG GEFI-/- mice revealed that the P2Y12 pathway is the predominate target of HAG-mediated inhibition of platelet aggregation. HAG itself displayed weak agonist properties and likely mediates its inhibitory effects via conversion to a phosphorylated metabolite, HAGP, which directly interacted with the C1a domains of 2 distinct PKC isoforms and blocked PKC kinase activity in vitro. Finally, AADACL1 inhibition in rats reduced platelet aggregation, protected against FeCl3-induced arterial thrombosis, and delayed tail bleeding time. In summary, our data support a model whereby AADACL1 inhibition shifts the platelet ether lipidome to an inhibitory axis of HAGP accumulation that impairs PKC activation, granule secretion, and recruitment of platelets to sites of vascular damage.
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Chaudhary PK, Kim S, Jee Y, Lee SH, Kim S. Characterization of Integrin αIIbβ3-Mediated Outside-in Signaling by Protein Kinase Cδ in Platelets. Int J Mol Sci 2020; 21:ijms21186563. [PMID: 32911704 PMCID: PMC7555476 DOI: 10.3390/ijms21186563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/01/2020] [Accepted: 09/07/2020] [Indexed: 11/16/2022] Open
Abstract
Engagement of integrin αIIbβ3 promotes platelet-platelet interaction and stimulates outside-in signaling that amplifies activation. Protein kinase Cδ (PKCδ) is known to play an important role in platelet activation, but its role in outside-in signaling has not been established. In the present study, we determined the role of PKCδ and its signaling pathways in integrin αIIbβ3-mediated outside-in signaling in platelets using PKCδ-deficient platelets. Platelet spreading to immobilized fibrinogen resulted in PKCδ phosphorylation, suggesting that αIIbβ3 activation caused PKCδ activation. αIIbβ3-mediated phosphorylation of Akt was significantly inhibited in PKCδ -/- platelets, indicating a role of PKCδ in outside-in signaling. αIIbβ3-mediated PKCδ phosphorylation was inhibited by proline-rich tyrosine kinase 2 (Pyk2) selective inhibitor, suggesting that Pyk2 contributes to the regulation of PKCδ phosphorylation in outside-in signaling. Additionally, Src-family kinase inhibitor PP2 inhibited integrin-mediated Pyk2 and PKCδ phosphorylation. Lastly, platelet spreading was inhibited in PKCδ -/- platelets compared to the wild-type (WT) platelets, and clot retraction from PKCδ -/- platelets was markedly delayed, indicating that PKCδ is involved in the regulation of αIIbβ3-dependent interactivities with cytoskeleton elements. Together, these results provide evidence that PKCδ plays an important role in outside-in signaling, which is regulated by Pyk2 in platelets.
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Affiliation(s)
- Preeti Kumari Chaudhary
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.)
| | - Sanggu Kim
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.)
| | - Youngheun Jee
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea;
| | - Seung-Hun Lee
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.)
| | - Soochong Kim
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.)
- Correspondence: ; Tel.: +82-43-249-1846
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9
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Chaudhary PK, Kim S, Jee Y, Lee SH, Park KM, Kim S. Role of GRK6 in the Regulation of Platelet Activation through Selective G Protein-Coupled Receptor (GPCR) Desensitization. Int J Mol Sci 2020; 21:ijms21113932. [PMID: 32486261 PMCID: PMC7312169 DOI: 10.3390/ijms21113932] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 12/27/2022] Open
Abstract
Platelet G protein-coupled receptors (GPCRs) regulate platelet function by mediating the response to various agonists, including adenosine diphosphate (ADP), thromboxane A2, and thrombin. Although GPCR kinases (GRKs) are considered to have the crucial roles in most GPCR functions, little is known regarding the regulation of GPCR signaling and mechanisms of GPCR desensitization by GRKs in platelets. In this study, we investigated the functional role of GRK6 and the molecular basis for regulation of specific GPCR desensitization by GRK6 in platelets. We used GRK6 knockout mice to evaluate the functional role of GRK6 in platelet activation. Platelet aggregation, dense- and α-granule secretion, and fibrinogen receptor activation induced by 2-MeSADP, U46619, thrombin, and AYPGKF were significantly potentiated in GRK6−/− platelets compared to the wild-type (WT) platelets. However, collagen-related peptide (CRP)-induced platelet aggregation and secretion were not affected in GRK6−/− platelets. Interestingly, platelet aggregation induced by co-stimulation of serotonin and epinephrine which activate Gq-coupled 5HT2A and Gz-coupled α2A adrenergic receptors, respectively, was not affected in GRK6−/− platelets, suggesting that GRK6 was involved in specific GPCR regulation. In addition, platelet aggregation in response to the second challenge of ADP and AYPGKF was restored in GRK6−/− platelets whereas re-stimulation of the agonist failed to induce aggregation in WT platelets, indicating that GRK6 contributed to P2Y1, P2Y12, and PAR4 receptor desensitization. Furthermore, 2-MeSADP-induced Akt phosphorylation and AYPGKF-induced Akt, extracellular signal-related kinase (ERK), and protein kinase Cδ (PKCδ) phosphorylation were significantly potentiated in GRK6−/− platelets. Finally, GRK6−/− mice exhibited an enhanced and stable thrombus formation after FeCl3 injury to the carotid artery and shorter tail bleeding times, indicating that GRK6−/− mice were more susceptible to thrombosis and hemostasis. We conclude that GRK6 plays an important role in regulating platelet functional responses and thrombus formation through selective GPCR desensitization.
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Affiliation(s)
- Preeti Kumari Chaudhary
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.); (K.-M.P.)
| | - Sanggu Kim
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.); (K.-M.P.)
| | - Youngheun Jee
- College of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju 63243, Korea;
| | - Seung-Hun Lee
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.); (K.-M.P.)
| | - Kyung-Mee Park
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.); (K.-M.P.)
| | - Soochong Kim
- College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea; (P.K.C.); (S.K.); (S.-H.L.); (K.-M.P.)
- Correspondence: ; Tel.: +82-43-249-1846
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11
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Protein kinase C signaling dysfunction in von Willebrand disease (p.V1316M) type 2B platelets. Blood Adv 2018; 2:1417-1428. [PMID: 29925524 DOI: 10.1182/bloodadvances.2017014290] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/17/2018] [Indexed: 01/22/2023] Open
Abstract
von Willebrand disease (VWD) type 2B is characterized by gain-of-function mutations in von Willebrand factor (VWF), enhancing its binding affinity for the platelet receptor glycoprotein (GP)Ibα. VWD type 2B patients display a bleeding tendency associated with loss of high-molecular-weight VWF multimers and variable thrombocytopenia. We recently demonstrated that a marked defect in agonist-induced activation of the small GTPase, Rap1, and integrin αIIbβ3 in VWD (p.V1316M) type 2B platelets also contributes to the bleeding tendency. Here, we investigated the molecular mechanisms underlying impaired platelet Rap1 signaling in this disease. Two distinct pathways contribute to Rap1 activation in platelets: rapid activation mediated by the calcium-sensing guanine nucleotide exchange factor CalDAG-GEF-I (CDGI) and sustained activation that is dependent on signaling by protein kinase C (PKC) and the adenosine 5'-diphosphate receptor P2Y12. To investigate which Rap1 signaling pathway is affected, we expressed VWF/p.V1316M by hydrodynamic gene transfer in wild-type and Caldaggef1-/- mice. Using αIIbβ3 integrin activation as a read-out, we demonstrate that platelet dysfunction in VWD (p.V1316M) type 2B affects PKC-mediated, but not CDGI-mediated, activation of Rap1. Consistently, we observed decreased PKC substrate phosphorylation and impaired granule release in stimulated VWD type 2B platelets. Interestingly, the defect in PKC signaling was caused by a significant increase in baseline PKC substrate phosphorylation in circulating VWD (p.V1316M) type 2B platelets, suggesting that the VWF-GPIbα interaction leads to preactivation and exhaustion of the PKC pathway. Consistent with PKC preactivation, VWD (p.V1316M) type 2B mice also exhibited marked shedding of platelet GPIbα. In summary, our studies identify altered PKC signaling as the underlying cause of platelet hypofunction in p.V1316M-associated VWD type 2B.
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12
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Mitrugno A, Rigg RA, Laschober NB, Ngo AT, Pang J, Williams CD, Aslan JE, McCarty OJ. Potentiation of TRAP-6-induced platelet dense granule release by blockade of P2Y 12 signaling with MRS2395. Platelets 2018; 29:383-394. [PMID: 28523947 PMCID: PMC6155984 DOI: 10.1080/09537104.2017.1316482] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/06/2017] [Accepted: 03/24/2017] [Indexed: 12/30/2022]
Abstract
The release of ADP from platelet dense granules and its binding to platelet P2Y12 receptors is key to amplifying the initial hemostatic response and propagating thrombus formation. P2Y12 has thus emerged as a therapeutic target to safely and effectively prevent secondary thrombotic events in patients with acute coronary syndrome or a history of myocardial infarction. Pharmacological inhibition of P2Y12 receptors represents a useful approach to better understand the signaling mediated by these receptors and to elucidate the role of these receptors in a multitude of platelet hemostatic and thrombotic responses. The present work examined and compared the effects of four different P2Y12 inhibitors (MRS2395, ticagrelor, PSB 0739, and AR-C 66096) on platelet function in a series of in vitro studies of platelet dense granule secretion and trafficking, calcium generation, and protein phosphorylation. Our results show that in platelets activated with the PAR-1 agonist TRAP-6 (thrombin receptor-activating peptide), inhibition of P2Y12 with the antagonist MRS2395, but not ticagrelor, PSB 0739 or AR-C 66096, potentiated human platelet dense granule trafficking to the plasma membrane and release into the extracellular space, cytosolic Ca2+ influx, and phosphorylation of GSK3β-Ser9 through a PKC-dependent pathway. These results suggest that inhibition of P2Y12 with MRS2395 may act in concert with PAR-1 signaling and result in the aberrant release of ADP by platelet dense granules, thus reducing or counteracting the anticipated anti-platelet efficacy of this inhibitor.
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Affiliation(s)
- Annachiara Mitrugno
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
- Cell, Developmental & Cancer Biology, Oregon Health & Science University, Portland, OR, USA
- Division of Hematology & Medical Oncology and Oregon Health & Science University, Portland, OR,
USA
| | - Rachel A. Rigg
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
| | - Nicole B. Laschober
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
| | - Anh T.P. Ngo
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
| | - Jiaqing Pang
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
| | | | - Joseph E. Aslan
- Knight Cardiovascular Institute, School of Medicine, Oregon Health & Science University, Portland, OR,
USA
| | - Owen J.T. McCarty
- Department of Biomedical Engineering,Oregon Health & Science University, Portland, OR, USA
- Cell, Developmental & Cancer Biology, Oregon Health & Science University, Portland, OR, USA
- Division of Hematology & Medical Oncology and Oregon Health & Science University, Portland, OR,
USA
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13
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Sánchez G, Estrada O, Acha G, Cardozo A, Peña F, Ruiz MC, Michelangeli F, Alvarado-Castillo C. The norpurpureine alkaloid from Annona purpurea inhibits human platelet activation in vitro. Cell Mol Biol Lett 2018; 23:15. [PMID: 29713353 PMCID: PMC5905151 DOI: 10.1186/s11658-018-0082-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 04/09/2018] [Indexed: 01/01/2023] Open
Abstract
Background The leaves of Annona purpurea have yielded several alkaloids with anti-aggregation activities against rabbit platelets. This is promising in the search for agents that might act against platelets and reduce the incidence of cardiovascular diseases. Since significant differences in platelet function have been reported between human and animal platelets, a study focusing on the effect of A. purpurea extracts against human platelet activation is necessary. Methods The compounds in an A. purpurea ethanolic extract underwent bio-guided fractionation and were used for in vitro human platelet aggregation assays to isolate the compounds with anti-platelet activity. The bioactive compounds were identified by spectroscopic analysis. Additional platelet studies were performed to characterize their action as inhibitors of human platelet activation. Results The benzylisoquinoline alkaloid norpurpureine was identified as the major anti-platelet compound. The IC50 for norpurpureine was 80 μM against platelets when stimulated with adenosine 5′-diphosphate (ADP), collagen and thrombin. It was pharmacologically effective from 20 to 220 μM. Norpurpureine (220 μM) exhibited its in vitro effectiveness in samples from 30 healthy human donors who did not take any drugs during the 2 weeks prior to the collection. Norpurpureine also gradually inhibited granule secretion and adhesion of activated platelets to immobilized fibrinogen. At the intra-platelet level, norpurpureine prevented agonist-stimulated calcium mobilization and cAMP reduction. Structure–activity relationship analysis indicates that the lack of a methyl group at the nitrogen seems to be key in the ability of the compound to interact with its molecular target. Conclusion Norpurpureine displays a promising in vitro pharmacological profile as an inhibitor of human platelet activation. Its molecular target could be a common effector between Ca2+ and cAMP signaling, such as the PLC-PKC-Ca2+ pathway and PDEs. This needs further evaluation at the protein isoform level. Electronic supplementary material The online version of this article (10.1186/s11658-018-0082-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gabriela Sánchez
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Omar Estrada
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Giovana Acha
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Alfonso Cardozo
- 2Laboratorio de Botánica Sistemática, Facultad de Agronomía, Universidad Central de Venezuela (UCV), Maracay, Bolivarian Republic of Venezuela
| | - Franshelle Peña
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Marie Christine Ruiz
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Fabián Michelangeli
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela
| | - Claudia Alvarado-Castillo
- 1Centro de Biofísica y Bioquímica (CBB), Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Bolivarian Republic of Venezuela.,3Laboratorio de Hemostasia y Genética Vascular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, K11 de la Carretera Panamericana, Caracas, 1020-A Bolivarian Republic of Venezuela
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14
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Beck S, Leitges M, Stegner D. Protein kinase Cι/λ is dispensable for platelet function in thrombosis and hemostasis in mice. Cell Signal 2017; 38:223-229. [PMID: 28739484 DOI: 10.1016/j.cellsig.2017.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/05/2017] [Accepted: 07/20/2017] [Indexed: 11/17/2022]
Abstract
Platelet activation at sites of vascular injury is crucial for hemostasis, but it may also cause myocardial infarction or ischemic stroke. Upon platelet activation, cytoskeletal reorganization is essential for platelet secretion and thrombus formation. Members of the protein kinase C family, which includes 12 isoforms, are involved in most platelet responses required for thrombus formation. The atypical protein kinase Cι/λ (PKCι/λ) has been implicated as an important mediator of cell polarity, carcinogenesis and immune cell responses. PKCι/λ is known to be associated with the small GTPase Cdc42, an important mediator of multiple platelet functions; however, its exact function in platelets is not known. To study the role of PKCι/λ, we generated platelet- and megakaryocyte-specific PKCι/λ knockout mice (Prkcifl/fl, Pf4-Cre) and used them to investigate the function of PKCι/λ in platelet activation and aggregation in vitro and in vivo. Surprisingly, lack of PKCι/λ had no detectable effect on platelet spreading and function in vitro and in vivo under all tested conditions. These results indicate that PKCι/λ is dispensable for Cdc42-triggered processes and for thrombosis and hemostasis in mice.
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Affiliation(s)
- Sarah Beck
- Institute of Experimental Biomedicine, University Hospital and Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | | | - David Stegner
- Institute of Experimental Biomedicine, University Hospital and Rudolf Virchow Center, University of Würzburg, Würzburg, Germany.
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15
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Unsworth AJ, Bye AP, Gibbins JM. Platelet-Derived Inhibitors of Platelet Activation. PLATELETS IN THROMBOTIC AND NON-THROMBOTIC DISORDERS 2017. [PMCID: PMC7123044 DOI: 10.1007/978-3-319-47462-5_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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Labberton L, Long AT, Gendler SJ, Snozek CL, Stavrou EX, Nickel KF, Maas C, Blankenberg S, Hernandez JS, Renné T. A Flow Cytometry-Based Assay for Procoagulant Platelet Polyphosphate. CYTOMETRY PART B-CLINICAL CYTOMETRY 2016; 94:369-373. [PMID: 27813345 DOI: 10.1002/cyto.b.21492] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/26/2016] [Accepted: 11/01/2016] [Indexed: 01/13/2023]
Abstract
BACKGROUND Platelet polyphosphate is an inorganic procoagulant polymer of orthophosphate units that is stored in dense granules and is released upon platelet activation. Here, we describe an assay to measure polyphosphate on the surface of procoagulant human platelets. METHODS AND RESULTS Recombinant Escherichia coli-expressed exopolyphosphatase deletion mutant PPX_Δ12 labeled with fluorescent Alexa488 dye was used as a polyphosphate probe in flow cytometry. PPX_Δ12-Alexa488-signal dose-dependently increased with long-chain polyphosphate binding to platelets. In contrast, short-chain polyphosphate that is found in the supernatant of activated platelets, did not bind to the platelet surface. Both exopolyphosphatase treatment and polyphosphate pre-incubation abolished PPX_Δ12-Alexa488 binding to polyphosphate on platelets. Stimulation of platelets with thrombin receptor agonist Trap6, and P2Y12 receptor activator ADP increased polyphosphate accumulation on platelet surfaces and PPX_Δ12-Alexa488 signal in a dose-dependent manner. CONCLUSION This study indicates that long-chain polyphosphate binds to platelet plasma membranes and presents a promising diagnostic assay to measure this interaction on human platelets in platelet-rich plasma. Future investigations will aim to determine if polyphosphate can be used as a novel biomarker of thrombosis. © 2016 International Clinical Cytometry Society.
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Affiliation(s)
- Linda Labberton
- Clinical Chemistry, Department of Molecular Medicine and Surgery, Karolinska Institutet and University Hospital, Stockholm, Sweden.,The Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andy T Long
- The Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sandra J Gendler
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Mayo Clinic in Arizona, Scottsdale, Arizona
| | - Christine L Snozek
- Department of Laboratory Medicine and Pathology, Mayo Clinic in Arizona, Scottsdale, Arizona
| | - Evi X Stavrou
- Division of Hematology and Oncology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Medicine, Louis Stokes Veterans Administration Hospital, Cleveland, Ohio
| | - Katrin F Nickel
- Clinical Chemistry, Department of Molecular Medicine and Surgery, Karolinska Institutet and University Hospital, Stockholm, Sweden.,The Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Coen Maas
- Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Stefan Blankenberg
- Department of General and Interventional Cardiology, University Heart Center Hamburg-Eppendorf, Hamburg, Germany
| | - James S Hernandez
- Department of Laboratory Medicine and Pathology, Mayo Clinic in Arizona, Scottsdale, Arizona
| | - Thomas Renné
- Clinical Chemistry, Department of Molecular Medicine and Surgery, Karolinska Institutet and University Hospital, Stockholm, Sweden.,The Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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17
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Satoh K, Narita T, Katsumata-Kato O, Sugiya H, Seo Y. Involvement of myristoylated alanine-rich C kinase substrate phosphorylation and translocation in cholecystokinin-induced amylase release in rat pancreatic acini. Am J Physiol Gastrointest Liver Physiol 2016; 310:G399-409. [PMID: 26744470 DOI: 10.1152/ajpgi.00198.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 01/05/2016] [Indexed: 01/31/2023]
Abstract
Cholecystokinin (CCK) is a gastrointestinal hormone that induces exocytotic amylase release in pancreatic acinar cells. The activation of protein kinase C (PKC) is involved in the CCK-induced pancreatic amylase release. Myristoylated alanine-rich C kinase substrate (MARCKS) is a ubiquitously expressed substrate of PKC. MARCKS has been implicated in membrane trafficking in several cell types. The phosphorylation of MARCKS by PKC results in the translocation of MARCKS from the membrane to the cytosol. Here, we studied the involvement of MARCKS in the CCK-induced amylase release in rat pancreatic acini. Employing Western blotting, we detected MARCKS protein in the rat pancreatic acini. CCK induced MARCKS phosphorylation. A PKC-δ inhibitor, rottlerin, inhibited the CCK-induced MARCKS phosphorylation and amylase release. In the translocation assay, we also observed CCK-induced PKC-δ activation. An immunohistochemistry study showed that CCK induced MARCKS translocation from the membrane to the cytosol. When acini were lysed by a detergent, Triton X-100, CCK partially induced displacement of the MARCKS from the GM1a-rich detergent-resistant membrane fractions (DRMs) in which Syntaxin2 is distributed. A MARCKS-related peptide inhibited the CCK-induced amylase release. These findings suggest that MARCKS phosphorylation by PKC-δ and then MARCKS translocation from the GM1a-rich DRMs to the cytosol are involved in the CCK-induced amylase release in pancreatic acinar cells.
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Affiliation(s)
- Keitaro Satoh
- Department of Regulatory Physiology, Dokkyo Medical University School of Medicine, Tochigi, Japan;
| | - Takanori Narita
- Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Kanagawa, Japan
| | - Osamu Katsumata-Kato
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan
| | - Hiroshi Sugiya
- Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Kanagawa, Japan
| | - Yoshiteru Seo
- Department of Regulatory Physiology, Dokkyo Medical University School of Medicine, Tochigi, Japan
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18
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Zaid Y, Senhaji N, Naya A, Fadainia C, Kojok K. PKCs in thrombus formation. ACTA ACUST UNITED AC 2015; 63:268-71. [PMID: 26476932 DOI: 10.1016/j.patbio.2015.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 09/01/2015] [Indexed: 10/22/2022]
Abstract
The protein kinase C (PKC) family has been implicated in several physiological processes regulating platelet activation. Each isoform of PKC expressed on platelets, may have a positive and/or negative role depending on the nature and concentration of the agonist. Mice lacking PKCα show much reduced thrombus formation in vivo, while PKCθ(-/-) showed inhibition of aggregation in response to PAR4. On the other hand, PKCδ by associating with Fyn, inhibits platelet aggregation. In addition, PKCβ by interacting with its receptor RACK1 has been implicated in the primary phases of signaling via the αIIbβ3 and finally PKCɛ appears to be involved in platelet function downstream GPVI. The present review discusses the latest observations relevant to the role of individual PKC isoforms in platelet activation and thrombus formation.
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Affiliation(s)
- Y Zaid
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, 5000 Belanger, Montreal, H1T 1C8 Quebec, Canada.
| | - N Senhaji
- Laboratory of Genetic and Molecular Pathology (LGPM), Medical School, Hassan II University, Casablanca, Morocco
| | - A Naya
- Laboratory of Physiology and Molecular Genetic, Faculty of Sciences, Hassan II University, Casablanca, Morocco
| | - C Fadainia
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, 5000 Belanger, Montreal, H1T 1C8 Quebec, Canada
| | - K Kojok
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, 5000 Belanger, Montreal, H1T 1C8 Quebec, Canada
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19
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Lever RA, Hussain A, Sun BB, Sage SO, Harper AGS. Conventional protein kinase C isoforms differentially regulate ADP- and thrombin-evoked Ca²⁺ signalling in human platelets. Cell Calcium 2015; 58:577-88. [PMID: 26434503 DOI: 10.1016/j.ceca.2015.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 11/15/2022]
Abstract
Rises in cytosolic Ca(2+) concentration ([Ca(2+)]cyt) are central in platelet activation, yet many aspects of the underlying mechanisms are poorly understood. Most studies examine how experimental manipulations affect agonist-evoked rises in [Ca(2+)]cyt, but these only monitor the net effect of manipulations on the processes controlling [Ca(2+)]cyt (Ca(2+) buffering, sequestration, release, entry and removal), and cannot resolve the source of the Ca(2+) or the transporters or channels affected. To investigate the effects of protein kinase C (PKC) on platelet Ca(2+) signalling, we here monitor Ca(2+) flux around the platelet by measuring net Ca(2+) fluxes to or from the extracellular space and the intracellular Ca(2+) stores, which act as the major sources and sinks for Ca(2+) influx into and efflux from the cytosol, as well as monitoring the cytosolic Na(+) concentration ([Na(+)]cyt), which influences platelet Ca(2+) fluxes via Na(+)/Ca(2+) exchange. The intracellular store Ca(2+) concentration ([Ca(2+)]st) was monitored using Fluo-5N, the extracellular Ca(2+) concentration ([Ca(2+)]ext) was monitored using Fluo-4 whilst [Ca(2+)]cyt and [Na(+)]cyt were monitored using Fura-2 and SFBI, respectively. PKC inhibition using Ro-31-8220 or bisindolylmaleimide I potentiated ADP- and thrombin-evoked rises in [Ca(2+)]cyt in the absence of extracellular Ca(2+). PKC inhibition potentiated ADP-evoked but reduced thrombin-evoked intracellular Ca(2+) release and Ca(2+) removal into the extracellular medium. SERCA inhibition using thapsigargin and 2,5-di(tert-butyl) l,4-benzohydroquinone abolished the effect of PKC inhibitors on ADP-evoked changes in [Ca(2+)]cyt but only reduced the effect on thrombin-evoked responses. Thrombin evokes substantial rises in [Na(+)]cyt which would be expected to reduce Ca(2+) removal via the Na(+)/Ca(2+) exchanger (NCX). Thrombin-evoked rises in [Na(+)]cyt were potentiated by PKC inhibition, an effect which was not due to altered changes in non-selective cation permeability of the plasma membrane as assessed by Mn(2+) quench of Fura-2 fluorescence. PKC inhibition was without effect on thrombin-evoked rises in [Ca(2+)]cyt following SERCA inhibition and either removal of extracellular Na(+) or inhibition of Na(+)/K(+)-ATPase activity by removal of extracellular K(+) or treatment with digoxin. These data suggest that PKC limits ADP-evoked rises in [Ca(2+)]cyt by acceleration of SERCA activity, whilst rises in [Ca(2+)]cyt evoked by the stronger platelet activator thrombin are limited by PKC through acceleration of both SERCA and Na(+)/K(+)-ATPase activity, with the latter limiting the effect of thrombin on rises in [Na(+)]cyt and so forward mode NCX activity. The use of selective PKC inhibitors indicated that conventional and not novel PKC isoforms are responsible for the inhibition of agonist-evoked Ca(2+) signalling.
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Affiliation(s)
- Robert A Lever
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Azhar Hussain
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Benjamin B Sun
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Stewart O Sage
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Alan G S Harper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom; Institute for Science and Technology in Medicine, Keele University, Guy Hilton Research Centre, Thornburrow Drive, Hartshill, Stoke-on-Trent ST4 7QB, United Kingdom.
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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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Abstract
Although psychological stress has long been known to alter cardiovascular function, there have been few studies on the effect of psychological stress on platelets, which play a pivotal role in cardiovascular disease. In the present study, we investigated the effects of acute and chronic psychological stress on the aggregation of platelets and platelet cytosolic free calcium concentration ([Ca(2+)]i). Mice were subjected to both transportation stress (exposure to novel environment, psychological stress) and restraint stress (psychological stress) for 2 h (acute stress) or 3 weeks (2 h/day) (chronic stress). In addition, adrenalectomized mice were subjected to similar chronic stress (both transportation and restraint stress for 3 weeks). The aggregation of platelets from mice and [Ca(2+)]i was determined by light transmission assay and fura-2 fluorescence assay, respectively. Although acute stress had no effect on agonist-induced platelet aggregation, chronic stress enhanced the ability of the platelet agonists thrombin and ADP to stimulate platelet aggregation. However, chronic stress failed to enhance agonist-induced increase in [Ca(2+)]i. Adrenalectomy blocked chronic stress-induced enhancement of platelet aggregation. These results suggest that chronic, but not acute, psychological stress enhances agonist-stimulated platelet aggregation independently of [Ca(2+)]i increase, and the enhancement may be mediated by stress hormones secreted from the adrenal glands.
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Affiliation(s)
- Fumikazu Matsuhisa
- Department of Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University , Gifu , Japan
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22
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Bhavanasi D, Kostyak JC, Swindle J, Kilpatrick LE, Kunapuli SP. CGX1037 is a novel PKC isoform delta selective inhibitor in platelets. Platelets 2014; 26:2-9. [PMID: 24433221 DOI: 10.3109/09537104.2013.868877] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Platelets upon activation change their shape, aggregate and secrete alpha and dense granule contents among which ADP acts as a feedback activator. Different Protein Kinase C (PKC) isoforms have specific non-redundant roles in mediating platelet responses including secretion and thrombus formation. Murine platelets lacking specific PKC isoforms have been used to evaluate the isoform specific functions. Novel PKC isoform δ has been shown to play an important role in some pathological processes. Lack of specific inhibitors for PKCδ has restricted analysis of its role in various cells. The current study was carried out to evaluate a novel small molecule PKCδ inhibitor, CGX1037 in platelets. Platelet aggregation, dense granule secretion and western blotting experiments were performed to evaluate CGX1037. In human platelets, CGX1037 inhibited PAR4-mediated phosphorylation on PKD2, a PKCδ-specific substrate. Pre-treatment of human or murine platelets with CGX1037 inhibited PAR4-mediated dense granule secretion whereas it potentiated GPVI-mediated dense granule secretion similar to the responses observed in murine platelets lacking PKCδ· Furthermore, pre-treatment of platelets from PKCδ(-/-) mice with CGX1037 had no significant additive effect on platelet responses suggesting the specificity of CGX1037. Hence, we show that CGX1037 is a selective small molecule inhibitor of PKCδ in platelets.
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Affiliation(s)
- Dheeraj Bhavanasi
- Department of Physiology, Temple University School of Medicine , Philadelphia, PA , USA
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23
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Golebiewska EM, Poole AW. Secrets of platelet exocytosis - what do we really know about platelet secretion mechanisms? Br J Haematol 2013; 165:204-216. [PMID: 24588354 PMCID: PMC4155865 DOI: 10.1111/bjh.12682] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Upon activation by extracellular matrix components or soluble agonists, platelets release in excess of 300 active molecules from intracellular granules. Those factors can both activate further platelets and mediate a range of responses in other cells. The complex microenvironment of a growing thrombus, as well as platelets' roles in both physiological and pathological processes, require platelet secretion to be highly spatially and temporally regulated to ensure appropriate responses to a range of stimuli. However, how this regulation is achieved remains incompletely understood. In this review we outline the importance of regulated secretion in thrombosis as well as in 'novel' scenarios beyond haemostasis and give a detailed summary of what is known about the molecular mechanisms of platelet exocytosis. We also discuss a number of theories of how different cargoes could be released in a tightly orchestrated manner, allowing complex interactions between platelets and their environment.
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Affiliation(s)
- Ewelina M Golebiewska
- School of Physiology and Pharmacology, Bristol Heart Institute, University of Bristol, Bristol, UK
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24
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Griffith GL, Russell RA, Kasus-Jacobi A, Thavathiru E, Gonzalez ML, Logan S, Pereira HA. CAP37 activation of PKC promotes human corneal epithelial cell chemotaxis. Invest Ophthalmol Vis Sci 2013; 54:6712-23. [PMID: 24008408 DOI: 10.1167/iovs.13-12054] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The objective of this study was to elucidate the signaling pathway through which cationic antimicrobial protein of 37 kDa (CAP37) mediates human corneal epithelial cell (HCEC) chemotaxis. METHODS Immortalized HCECs were treated with pertussis toxin (10 and 1000 ng/mL), protein kinase C (PKC) inhibitors (calphostin c, 50 nM and Ro-31-8220, 100 nM), phorbol esters (phorbol 12,13-dibutyrate, 200 nM and phorbol 12-myristate 13-acetate, 1 μM) known to deplete PKC isoforms, and siRNAs (400 nM) before a modified Boyden chamber assay was used to determine the effect of these inhibitors and siRNAs on CAP37-directed HCEC migration. PKCδ protein levels, PKCδ-Thr(505) phosphorylation, and PKCδ kinase activity was assessed in CAP37-treated HCECs using immunohistochemistry, Western blotting, and a kinase activity assay, respectively. RESULTS Chemotaxis studies revealed that treatment with pertussis toxin, PKC inhibitors, phorbol esters, and siRNAs significantly inhibited CAP37-mediated chemotaxis compared with untreated controls. CAP37 treatment increased PKCδ protein levels and led to PKCδ phosphorylation on residue Thr(505). Direct activation of PKCδ by CAP37 was demonstrated using a kinase activity assay. CONCLUSIONS These findings lead us to conclude that CAP37 is an important regulator of corneal epithelial cell migration and mediates its effects through PKCδ.
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Affiliation(s)
- Gina L Griffith
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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25
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Moncada de la Rosa C, Radziwon-Balicka A, El-Sikhry H, Seubert J, Ruvolo PP, Radomski MW, Jurasz P. Pharmacologic Protein Kinase CαInhibition Uncouples Human Platelet-Stimulated Angiogenesis from Collagen-Induced Aggregation. J Pharmacol Exp Ther 2013; 345:15-24. [DOI: 10.1124/jpet.112.200881] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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26
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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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27
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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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Cui L, Li J, Xie X. Rediocide A, an Insecticide, induces G-protein-coupled receptor desensitization via activation of conventional protein kinase C. JOURNAL OF NATURAL PRODUCTS 2012; 75:1058-1062. [PMID: 22650618 DOI: 10.1021/np3000359] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In order to identify small-molecule antagonists of Methuselah (Mth), a Drosophila G-protein-coupled receptor (GPCR) involved in life-span control, a library of natural compounds was screened, and it was found that rediocide A (1), a daphnane ester from the roots of Trigonostemon reidioides and used currently for flea control, potently inhibited calcium mobilization mediated by this receptor. Compound 1 inhibited calcium mobilization in GPCRs other than Mth, indicating that the inhibitory effect was not due to receptor antagonism but rather to a more general mechanism. It was found that 1 can induce GPCR desensitization and internalization, and such effects were mediated by the activation of conventional protein kinase C.
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Affiliation(s)
- Lixin Cui
- State Key Laboratory of Drug Research, National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China
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29
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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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30
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Passacquale G, Ferro A. Current concepts of platelet activation: possibilities for therapeutic modulation of heterotypic vs. homotypic aggregation. Br J Clin Pharmacol 2012; 72:604-18. [PMID: 21223359 DOI: 10.1111/j.1365-2125.2011.03906.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Thrombogenic and inflammatory activity are two distinct aspects of platelet biology, which are sustained by the ability of activated platelets to interact with each other (homotypic aggregation) and to adhere to circulating leucocytes (heterotypic aggregation). These two events are regulated by distinct biomolecular mechanisms that are selectively activated in different pathophysiological settings. They can occur simultaneously, for example, as part of a pro-thrombotic/pro-inflammatory response induced by vascular damage, or independently, as in certain clinical conditions in which abnormal heterotypic aggregation has been observed in the absence of intravascular thrombosis. Current antiplatelet drugs have been developed to target specific molecular signalling pathways mainly implicated in thrombus formation, and their ever increasing clinical use has resulted in clear benefits in the treatment and prevention of arterial thrombotic events. However, the efficacy of currently available antiplatelet drugs remains suboptimal, most likely because their therapeutic action is limited to only few of the signalling pathways involved in platelet homotypic aggregation. In this context, modulation of heterotypic aggregation, which is believed to contribute importantly to acute thrombotic events, as well to the pathophysiology of atherosclerosis itself, may offer benefits over and above the classical antiplatelet approach. This review will focus on the distinct biomolecular pathways that, following platelet activation, underlie homotypic and heterotypic aggregation, aiming potentially to identify novel therapeutic targets.
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Affiliation(s)
- Gabriella Passacquale
- Department of Clinical Pharmacology, Cardiovascular Division, King's College London, London, UK
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31
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Abstract
Three classes of inhibitors of platelet aggregation have demonstrated substantial clinical benfits. Aspirin acts by irreversibly inhibiting COX-1 and therefore blocking the synthesis of proaggregatory thromboxane A (2) (TxA(2)). The indirect acting (ticlopidine, clopidogrel, prasugrel) and the direct acting (ticagrelor) antagonists of P2Y(12) block the thrombus stabilizing activity of ADP. Parenteral GP IIb-IIIa inhibitors directly block platelet-platelet interactions. Despite well-established benefits, all antiplatelet agents have important limitations: increased bleeding and gastrointestinal toxicities (aspirin), high incidence of thrombotic thrombocytopenic purpura (ticlopidine), potentially nonresponders (clopidogrel), severe bleeding (prasugrel, GP IIb-IIIa antagonists) and "complicated" relationships with aspirin ticagrelor). In this chapter, we present the genetic and pharmacological evidence that supports the development and expectations associated with novel antiplatelet strategies directed at intrasignaling pathways.
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Affiliation(s)
- Patrick Andre
- Portola Pharmaceuticals Inc, 270 E. Grand Avenue, Suite 22 South, San Francisco, CA 94080, USA.
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32
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Protein kinase C-theta in platelet activation. FEBS Lett 2011; 585:3208-15. [DOI: 10.1016/j.febslet.2011.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/20/2011] [Accepted: 09/12/2011] [Indexed: 02/05/2023]
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Bhavanasi D, Kim S, Goldfinger LE, Kunapuli SP. Protein kinase Cδ mediates the activation of protein kinase D2 in platelets. Biochem Pharmacol 2011; 82:720-7. [PMID: 21736870 DOI: 10.1016/j.bcp.2011.06.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/17/2011] [Accepted: 06/20/2011] [Indexed: 01/25/2023]
Abstract
Protein kinase D (PKD) is a subfamily of serine/threonine specific family of kinases, comprised of PKD1, PKD2 and PKD3 (PKCμ, PKD2 and PKCv in humans). It is known that PKCs activate PKD, but the relative expression of isoforms of PKD or the specific PKC isoform/s responsible for its activation in platelets is not known. This study is aimed at investigating the pathway involved in activation of PKD in platelets. We show that PKD2 is the major isoform of PKD that is expressed in human as well as murine platelets but not PKD1 or PKD3. PKD2 activation induced by AYPGKF was abolished with a G(q) inhibitor YM-254890, but was not affected by Y-27632, a RhoA/p160ROCK inhibitor, indicating that PKD2 activation is G(q)-, but not G₁₂/₁₃-mediated Rho-kinase dependent. Calcium-mediated signals are also required for activation of PKD2 as dimethyl BAPTA inhibited its phosphorylation. GF109203X, a pan PKC inhibitor abolished PKD2 phosphorylation but Go6976, a classical PKC inhibitor had no effect suggesting that novel PKC isoforms are involved in PKD2 activation. Importantly, Rottlerin, a non-selective PKCδ inhibitor, inhibited AYPGKF-induced PKD2 activation in human platelets. Similarly, AYPGKF- and Convulxin-induced PKD2 phosphorylation was dramatically inhibited in PKCδ-deficient platelets, but not in PKCθ- or PKCɛ-deficient murine platelets compared to that of wild type platelets. Hence, we conclude that PKD2 is a common signaling target downstream of various agonist receptors in platelets and G(q)-mediated signals along with calcium and novel PKC isoforms, in particular, PKCδ activate PKD2 in platelets.
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Affiliation(s)
- Dheeraj Bhavanasi
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA
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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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Differential dephosphorylation of the protein kinase C-zeta (PKCζ) in an integrin αIIbβ3-dependent manner in platelets. Biochem Pharmacol 2011; 82:505-13. [PMID: 21645497 DOI: 10.1016/j.bcp.2011.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 05/19/2011] [Accepted: 05/20/2011] [Indexed: 12/19/2022]
Abstract
Protein kinase C-zeta (PKCζ), an atypical isoform of the PKC family of protein serine/threonine kinases, is expressed in human platelets. However, the mechanisms of its activation and the regulation of its activity in platelets are not known. We have found that under basal resting conditions, PKCζ has a high phosphorylation status at the activation loop threonine 410 (T410) and the turn motif (autophosphorylation site) threonine 560 (T560), both of which have been shown to be important for its catalytic activity. After stimulation with agonist under stirring conditions, the T410 residue was dephosphorylated in a time- and concentration-dependent manner, while the T560 phosphorylation remained unaffected. The T410 dephosphorylation could be significantly prevented by blocking the binding of fibrinogen to integrin αIIbβ3 with an antagonist, SC-57101; or by okadaic acid used at concentrations that inhibits protein serine/threonine phosphatases PP1 and PP2A in vitro. The dephosphorylation of T410 residue on PKCζ was also observed in PP1cγ null murine platelets after agonist stimulation, suggesting that other isoforms of PP1c or another phosphatase could be responsible for this dephosphorylation event. We conclude that human platelets express PKCζ, and it may be constitutively phosphorylated at the activation loop threonine 410 and the turn motif threonine 560 under basal resting conditions, which are differentially dephosphorylated by outside-in signaling. This differential dephosphorylation of PKCζ might be an important regulatory mechanism for platelet functional responses.
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Heemskerk JW, Harper MT, Cosemans JM, Poole AW. Unravelling the different functions of protein kinase C isoforms in platelets. FEBS Lett 2011; 585:1711-6. [DOI: 10.1016/j.febslet.2011.05.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 04/28/2011] [Accepted: 05/04/2011] [Indexed: 11/17/2022]
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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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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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Abstract
Upon vascular injury, platelets are activated by adhesion to adhesive proteins, such as von Willebrand factor and collagen, or by soluble platelet agonists, such as ADP, thrombin, and thromboxane A(2). These adhesive proteins and soluble agonists induce signal transduction via their respective receptors. The various receptor-specific platelet activation signaling pathways converge into common signaling events that stimulate platelet shape change and granule secretion and ultimately induce the "inside-out" signaling process leading to activation of the ligand-binding function of integrin α(IIb)β(3). Ligand binding to integrin α(IIb)β(3) mediates platelet adhesion and aggregation and triggers "outside-in" signaling, resulting in platelet spreading, additional granule secretion, stabilization of platelet adhesion and aggregation, and clot retraction. It has become increasingly evident that agonist-induced platelet activation signals also cross talk with integrin outside-in signals to regulate platelet responses. Platelet activation involves a series of rapid positive feedback loops that greatly amplify initial activation signals and enable robust platelet recruitment and thrombus stabilization. Recent studies have provided novel insight into the molecular mechanisms of these processes.
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Affiliation(s)
- Zhenyu Li
- Department of Medicine, University of Kentucky
| | | | | | - Xiaoping Du
- Department of Pharmacology, University of Illinois at Chicago
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Harper MT, Poole AW. Diverse functions of protein kinase C isoforms in platelet activation and thrombus formation. J Thromb Haemost 2010; 8:454-62. [PMID: 20002545 DOI: 10.1111/j.1538-7836.2009.03722.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Platelet activation is a complex balance of positive and negative signaling pathways. The protein kinase C (PKC) family is a major regulator of platelet granule secretion, integrin activation, aggregation, spreading and procoagulant activity. As broad-spectrum PKC inhibitors reduce secretion and aggregation, the PKC family is generally considered to be a positive regulator of platelet activation. However, the individual members of the PKC family that are expressed in platelets are regulated in different ways, and an increasing body of evidence indicates that they have distinct, and often opposing, roles. Many of the recent advances in understanding the contributions of individual PKC isoforms have come from mouse gene knockout studies. PKCalpha, a classic isoform, is an essential positive regulator of granule secretion and thrombus formation, both in vitro and in vivo. Mice lacking PKCalpha show much reduced thrombus formation in vivo but do not have a bleeding defect, suggesting that PKCalpha could be an attractive antithrombotic target. Important, apparently non-redundant, roles, both positive and negative, for the novel PKC isoforms delta, theta and epsilon in granule secretion have also been proposed, indicating highly complex regulation of this essential process. Similarly, PKCbeta, PKCdelta and PKCtheta have non-redundant roles in platelet spreading, as absence of either PKCbeta or PKCtheta reduces spreading, whereas PKCdelta negatively regulates filopodial formation. This negative signaling by PKCdelta may reduce platelet aggregation and so restrict thrombus formation. In this review, we discuss the current understanding of the regulation and functions of individual PKC isoforms in platelet activation and thrombus formation.
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Affiliation(s)
- M T Harper
- Department of Physiology and Pharmacology, University of Bristol, Bristol, UK
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Unraveling a novel Rac1-mediated signaling pathway that regulates cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Blood 2009; 114:415-24. [DOI: 10.1182/blood-2008-10-183582] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Abstract
In platelets stimulated by thrombin to secrete and aggregate, cofilin is rapidly dephosphorylated leading to its activation. Cofilin by severing existing actin filaments and stimulating F-actin polymerization on newly created barbed ends dynamizes the actin cytoskeleton. We previously found that cofilin dephosphorylation is Ca2+-dependent and occurs upstream of degranulation in stimulated platelets. We report now in thrombin-stimulated platelets that Rac1 and class II PAKs (PAK4/5/6) were rapidly (within 5 seconds) activated, whereas PAK1/2 (class I PAKs) phosphorylation was slower. The Rac1-specific inhibitor NSC23766 blocked phosphorylation of class II PAKs, but not PAK1/2. Moreover, inhibition of the Ca2+/calmodulin-dependent phosphatase calcineurin inhibited Rac1 activation and class II PAKs phosphorylation. Prevention of Rac1 activation by calcineurin inhibition or NSC23766 also blocked cofilin dephosphorylation and platelet granule secretion indicating that a calcineurin/Rac1/class II PAKs pathway regulates cofilin dephosphorylation leading to secretion. We further found that PI3-kinases were activated downstream of Rac1, but were not involved in regulating cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Our study unravels a Ca2+-dependent pathway of secretion in stimulated platelets as a signaling pathway linking Rac1 activation to actin dynamics: calcineurin→Rac1→class II PAKs→cofilin activation. We further demonstrate that this pathway is separate and independent of the protein kinase C (PKC) pathway mediating secretion.
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Lyn, PKC-delta, SHIP-1 interactions regulate GPVI-mediated platelet-dense granule secretion. Blood 2009; 114:3056-63. [PMID: 19587372 DOI: 10.1182/blood-2008-11-188516] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein kinase C-delta (PKC-delta) is expressed in platelets and activated downstream of protease-activated receptors (PARs) and glycoprotein VI (GPVI) receptors. We have previously shown that PKC-delta positively regulates PAR-mediated dense granule secretion, whereas it negatively regulates GPVI-mediated dense granule secretion. We further investigated the mechanism of such differential regulation of dense granule release by PKC-delta in platelets. SH2 domain-containing inositol phosphatase-1 (SHIP-1) is phosphorylated on Y1020, a marker for its activation, upon stimulation of human platelets with PAR agonists SFLLRN and AYPGKF or GPVI agonist convulxin. GPVI-mediated SHIP-1 phosphorylation occurred rapidly at 15 seconds, whereas PAR-mediated phosphorylation was delayed, occurring at 1 minute. Lyn and SHIP-1, but not SHIP-2 or Shc, preferentially associated with PKC-delta on stimulation of platelets with a GPVI agonist, but not with a PAR agonist. In PKC-delta-null murine platelets, convulxin-induced SHIP-1 phosphorylation was inhibited. Furthermore, in Lyn null murine platelets, GPVI-mediated phosphorylations on Y-1020 of SHIP-1 and Y311 of PKC-delta were inhibited. In murine platelets lacking Lyn or SHIP-1, GPVI-mediated dense granule secretions are potentiated, whereas PAR-mediated dense granule secretions are inhibited. Therefore, we conclude that Lyn-mediated phosphorylations of PKC-delta and SHIP-1 and their associations negatively regulate GPVI-mediated dense granule secretion in platelets.
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Satoh K, Matsuki-Fukushima M, Qi B, Guo MY, Narita T, Fujita-Yoshigaki J, Sugiya H. Phosphorylation of myristoylated alanine-rich C kinase substrate is involved in the cAMP-dependent amylase release in parotid acinar cells. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1382-90. [PMID: 19372103 DOI: 10.1152/ajpgi.90536.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Myristoylated alanine-rich C kinase substrate (MARCKS) is known as a major cellular substrate for protein kinase C (PKC). MARCKS has been implicated in the regulation of brain development and postnatal survival, cellular migration and adhesion, as well as phagocytosis, endocytosis, and exocytosis. The involvement of MARCKS phosphorylation in secretory function has been reported in Ca(2+)-mediated exocytosis. In rat parotid acinar cells, the activation of beta-adrenergic receptors provokes exocytotic amylase release via accumulation of intracellular cAMP levels. Here, we studied the involvement of MARCKS phosphorylation in the cAMP-dependent amylase release in rat parotid acinar cells. MARCKS protein was detected in rat parotid acinar cells by Western blotting. The beta-adrenergic agonist isoproterenol (IPR) induced MARCKS phosphorylation in a time-dependent manner. Translocation of a part of phosphorylated MARCKS from the membrane to the cytosol and enhancement of MARCKS phosphorylation at the apical membrane site induced by IPR were observed by immunohistochemistry. H89, a cAMP-dependent protein kinase (PKA) inhibitor, inhibited the IPR-induced MARCKS phosphorylation. The PKCdelta inhibitor rottlerin inhibited the IPR-induced MARCKS phosphorylation and amylase release. IPR activated PKCdelta, and the effects of IPR were inhibited by the PKA inhibitors. A MARCKS-related peptide partially inhibited the IPR-induced amylase release. These findings suggest that MARCKS phosphorylation via the activation of PKCdelta, which is downstream of PKA activation, is involved in the cAMP-dependent amylase release in parotid acinar cells.
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Affiliation(s)
- Keitaro Satoh
- Dept. of Physiology, Nihon Univ. School of Dentistry at Matsudo, 2-870-1 Sakaecho-nishi, Matsudo, Chiba 271-8587, Japan
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Bynagari YS, Nagy B, Tuluc F, Bhavaraju K, Kim S, Vijayan KV, Kunapuli SP. Mechanism of activation and functional role of protein kinase Ceta in human platelets. J Biol Chem 2009; 284:13413-13421. [PMID: 19286657 PMCID: PMC2679441 DOI: 10.1074/jbc.m808970200] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 03/06/2009] [Indexed: 11/06/2022] Open
Abstract
The novel class of protein kinase C (nPKC) isoform eta is expressed in platelets, but not much is known about its activation and function. In this study, we investigated the mechanism of activation and functional implications of nPKCeta using pharmacological and gene knock-out approaches. nPKCeta was phosphorylated (at Thr-512) in a time- and concentration-dependent manner by 2MeSADP. Pretreatment of platelets with MRS-2179, a P2Y1 receptor antagonist, or YM-254890, a G(q) blocker, abolished 2MeSADP-induced phosphorylation of nPKCeta. Similarly, ADP failed to activate nPKCeta in platelets isolated from P2Y1 and G(q) knock-out mice. However, pretreatment of platelets with P2Y12 receptor antagonist, AR-C69331MX did not interfere with ADP-induced nPKCeta phosphorylation. In addition, when platelets were activated with 2MeSADP under stirring conditions, although nPKCeta was phosphorylated within 30 s by ADP receptors, it was also dephosphorylated by activated integrin alpha(IIb)beta3 mediated outside-in signaling. Moreover, in the presence of SC-57101, a alpha(IIb)beta3 receptor antagonist, nPKCeta dephosphorylation was inhibited. Furthermore, in murine platelets lacking PP1cgamma, a catalytic subunit of serine/threonine phosphatase, alpha(IIb)beta3 failed to dephosphorylate nPKCeta. Thus, we conclude that ADP activates nPKCeta via P2Y1 receptor and is subsequently dephosphorylated by PP1gamma phosphatase activated by alpha(IIb)beta3 integrin. In addition, pretreatment of platelets with eta-RACK antagonistic peptides, a specific inhibitor of nPKCeta, inhibited ADP-induced thromboxane generation. However, these peptides had no affect on ADP-induced aggregation when thromboxane generation was blocked. In summary, nPKCeta positively regulates agonist-induced thromboxane generation with no effects on platelet aggregation.
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Affiliation(s)
- Yamini S Bynagari
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Bela Nagy
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Florin Tuluc
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Kamala Bhavaraju
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Soochong Kim
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - K Vinod Vijayan
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030
| | - Satya P Kunapuli
- Departments of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Pharmacology and the Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
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45
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Chari R, Getz T, Nagy B, Bhavaraju K, Mao Y, Bynagari YS, Murugappan S, Nakayama K, Kunapuli SP. Protein kinase C[delta] differentially regulates platelet functional responses. Arterioscler Thromb Vasc Biol 2009; 29:699-705. [PMID: 19213940 DOI: 10.1161/atvbaha.109.184010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Protein Kinase C delta (PKCdelta) is expressed in platelets and activated downstream of protease-activated receptors (PAR)s and glycoprotein VI (GPVI) receptors. The purpose of this study was to investigate the role of PKCdelta in platelets. METHODS AND RESULTS We evaluated the role of PKCdelta in platelets using two approaches--pharmacological and molecular genetic approach. In human platelets pretreated with isoform selective antagonistic RACK peptide (delta V1-1)TAT, and in the murine platelets lacking PKCdelta, PAR4-mediated dense granule secretion was inhibited, whereas GPVI-mediated dense granule secretion was potentiated. These effects were statistically significant in the absence and presence of thromboxane A2 (TXA2). Furthermore, TXA2 generation was differentially regulated by PKCdelta. However, PKCdelta had a small effect on platelet P-selectin expression. Calcium- and PKC-dependent pathways independently activate fibrinogen receptor in platelets. When calcium pathways are blocked by dimethyl-BAPTA, AYPGKF-induced aggregation in PKCdelta null mouse platelets and in human platelets pretreated with (delta V1-1)TAT, was inhibited. In a FeCl3-induced injury in vivo thrombosis model, PKCdelta-/- mice occluded similar to their wild-type littermates. CONCLUSIONS Hence, we conclude that PKCdelta differentially regulates platelet functional responses such as dense granule secretion and TXA2 generation downstream of PARs and GPVI receptors, but PKCdelta deficiency does not affect the thrombus formation in vivo.
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Affiliation(s)
- Ramya Chari
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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46
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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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47
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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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Differential regulation of threonine and tyrosine phosphorylations on protein kinase Cdelta by G-protein-mediated pathways in platelets. Biochem J 2009; 417:113-20. [PMID: 18652571 DOI: 10.1042/bj20080235] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Phosphorylation of activation loop threonine (Thr(505)) and regulatory domain tyrosine (Tyr(311)) residues are key regulators of PKC (protein kinase C) delta function in platelets. In the present study, we show that G(q) and G(12/13) pathways regulate the Thr(505) and Tyr(311) phosphorylation on PKCdelta in an interdependent manner. DiC8 (1,2-dioctanoylglycerol), a synthetic analogue of DAG (diacylglycerol), caused Thr(505), but not Tyr(311), phosphorylation on PKCdelta, whereas selective activation of G(12/13) pathways by the YFLLRNP peptide failed to cause phosphorylation of either residue. However, simultaneous activation by DiC8 and YFLLRNP resulted in Thr(505) and Tyr(311) phosphorylation on PKCdelta. In addition, we found that the activation of SFKs (Src family tyrosine kinases) is essential for G(12/13)-mediated Tyr(311) phosphorylation of PKCdelta. These results were confirmed using G(q)-deficient mouse platelets. Finally, we investigated whether Thr(505) phosphorylation is required for Tyr(311) phosphorylation. A T505A PKCdelta mutant failed to be phosphorylated at Tyr(311), even upon stimulation of both G(q) and G(12/13) pathways. We conclude that (i) PKCdelta binding to DAG, downstream of G(q) pathways, and its translocation results in Thr(505) phosphorylation, (ii) G(12/13) pathways activate SFKs required for the phosphorylation of Tyr(311) on Thr(505)-phosphorylated PKCdelta, and (iii) Thr(505) phosphorylation is a prerequisite for Tyr(311) phosphorylation on PKCdelta.
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He X, Fang L, Wang J, Yi Y, Zhang S, Xie X. Bryostatin-5 blocks stromal cell-derived factor-1 induced chemotaxis via desensitization and down-regulation of cell surface CXCR4 receptors. Cancer Res 2008; 68:8678-86. [PMID: 18974109 DOI: 10.1158/0008-5472.can-08-0294] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The chemokine receptor CXCR4 and its ligand, stromal cell-derived factor-1 (SDF-1), play important roles in hematopoiesis regulation, lymphocyte activation, and trafficking, as well as in developmental processes, including organogenesis, vascularization, and embryogenesis. The receptor is also involved in HIV infection and tumor growth and metastasis. Antagonists of CXCR4 have been widely evaluated for drugs against HIV and tumors. In an effort to identify novel CXCR4 antagonists, we screened a small library of compounds derived from marine organisms and found bryostatin-5, which potently inhibits chemotaxis induced by SDF-1 in Jurkat cells. Bryostatin-5 is a member of the macrolactones, and its analogue bryostatin-1 is currently being evaluated in clinical trials for its chemotherapeutic potential. The involvement of bryostatins in the SDF-1/CXCR4 signaling process has never been reported. In this study, we found that bryostatin-5 potently inhibits SDF-1-induced chemotaxis but does not affect serum-induced chemotaxis. Further studies indicate that this inhibitory effect is not due to receptor antagonism but rather to bryostatin-5-induced receptor desensitization and down-regulation of cell surface CXCR4. We also show that these effects are mediated by the activation of conventional protein kinase C.
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Affiliation(s)
- Xing He
- National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Graduate University of the Chinese Academy of Sciences, Shanghai, China
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50
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Jin J, Mao Y, Thomas D, Kim S, Daniel JL, Kunapuli SP. RhoA downstream of G(q) and G(12/13) pathways regulates protease-activated receptor-mediated dense granule release in platelets. Biochem Pharmacol 2008; 77:835-44. [PMID: 19073150 DOI: 10.1016/j.bcp.2008.11.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 11/13/2008] [Accepted: 11/14/2008] [Indexed: 11/17/2022]
Abstract
Platelet secretion is an important physiological event in hemostasis. The protease-activated receptors, PAR 1 and PAR 4, and the thromboxane receptor activate the G(12/13) pathways, in addition to the G(q) pathways. Here, we investigated the contribution of G(12/13) pathways to platelet dense granule release. 2MeSADP, which does not activate G(12/13) pathways, does not cause dense granule release in aspirin-treated platelets. However, supplementing 2MeSADP with YFLLRNP (60muM), as selective activator of G(12/13) pathways, resulted in dense granule release. Similarly, supplementing PLC activation with G(12/13) stimulation also leads to dense granule release. These results demonstrate that supplemental signaling from G(12/13) is required for G(q)-mediated dense granule release and that ADP fails to cause dense granule release because the platelet P2Y receptors, although activate PLC, do not activate G(12/13) pathways. When RhoA, downstream signaling molecule in G(12/13) pathways, is blocked, PAR-mediated dense granule release is inhibited. Furthermore, ADP activated RhoA downstream of G(q) and upstream of PLC. Finally, RhoA regulated PKCdelta T505 phosphorylation, suggesting that RhoA pathways contribute to platelet secretion through PKCdelta activation. We conclude that G(12/13) pathways, through RhoA, regulate dense granule release and fibrinogen receptor activation in platelets.
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Affiliation(s)
- Jianguo Jin
- Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA
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