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Abstract
This article represents a republication of an article originally published in STH in 2005. This republication is to help celebrate 50 years of publishing for STH. The original abstract follows.Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, inflammation, tumor metastasis, wound healing, and host defense. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion and signaling molecules. This article gives an overview of the activation processes involved in primary and secondary hemostasis, for example, platelet adhesion, platelet secretion, platelet aggregation, microvesicle formation, and clot retraction/stabilization. In addition, activated platelets are predominantly involved in cross-talk to other blood and vascular cells. Stimulated "sticky" platelets enable recruitment of leukocytes at sites of vascular injury under high shear conditions. Platelet-derived microparticles as well as soluble adhesion molecules, sP-selectin and sCD40L, shed from the surface of activated platelets, are capable of activating, in turn, leukocytes and endothelial cells. This article focuses further on the new view of receptor-mediated thrombin generation of human platelets, necessary for the formation of a stable platelet-fibrin clot during secondary hemostasis. Finally, special emphasis is placed on important stimulatory and inhibitory signaling pathways that modulate platelet function.
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Affiliation(s)
- Kerstin Jurk
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University-Hospital Munster, Munster, Germany
| | - Beate E Kehrel
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University-Hospital Munster, Munster, Germany
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Rudran T, Antoniak S, Flick MJ, Ginsberg MH, Wolberg AS, Bergmeier W, Lee RH. Protease-activated receptors and glycoprotein VI cooperatively drive the platelet component in thromboelastography. J Thromb Haemost 2023; 21:2236-2247. [PMID: 37068592 PMCID: PMC10824270 DOI: 10.1016/j.jtha.2023.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/27/2023] [Accepted: 04/09/2023] [Indexed: 04/19/2023]
Abstract
BACKGROUND Thromboelastography (TEG) is used for real-time determination of hemostatic status in patients with acute risk of bleeding. Thrombin is thought to drive clotting in TEG through generation of polymerized fibrin and activation of platelets through protease-activated receptors (PARs). However, the specific role of platelet agonist receptors and signaling in TEG has not been reported. OBJECTIVES Here, we investigated the specific receptors and signaling pathways required for platelet function in TEG using genetic and pharmacologic inhibition of platelet proteins in mouse and human blood samples. METHODS Clotting parameters (R time, α-angle [α], and maximum amplitude [MA]), were determined in recalcified, kaolin-triggered citrated blood samples using a TEG 5000 analyzer. RESULTS We confirmed the requirement of platelets, platelet contraction, and αIIbβ3 integrin function for normal α and MA. Loss of the integrin adaptor Talin1 in megakaryocytes/platelets (Talin1mKO) also reduced α and MA, but only minimal defects were observed in samples from mice lacking Rap1 GTPase signaling. PAR4mKO samples showed impaired α but normal MA. However, impaired TEG traces similar to those in platelet-depleted samples were observed with samples from PAR4mKO mice depleted of glycoprotein VI on platelets or with addition of a Syk inhibitor. We reproduced these results in human blood with combined inhibition of PAR1, PAR4, and Syk. CONCLUSION Our results demonstrate that standard TEG is not sensitive to platelet signaling pathways critical for integrin inside-out activation and platelet hemostatic function. Furthermore, we provide the first evidence that PARs and glycoprotein VI play redundant roles in platelet-mediated clot contraction in TEG.
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Affiliation(s)
- Tanvi Rudran
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Silvio Antoniak
- UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Matthew J Flick
- UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Alisa S Wolberg
- UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Robert H Lee
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Blood Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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Molecular basis for integrin adhesion receptor binding to p21-activated kinase 4 (PAK4). Commun Biol 2022; 5:1257. [PMID: 36385162 PMCID: PMC9669019 DOI: 10.1038/s42003-022-04157-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 10/24/2022] [Indexed: 11/18/2022] Open
Abstract
AbstractIntegrin adhesion receptors provide links between extracellular ligands and cytoplasmic signaling. Multiple kinases have been found to directly engage with integrin β tails, but the molecular basis for these interactions remain unknown. Here, we assess the interaction between the kinase domain of p21-activated kinase 4 (PAK4) and the cytoplasmic tail of integrin β5. We determine three crystal structures of PAK4-β5 integrin complexes and identify the PAK-binding site. This is a region in the membrane-proximal half of the β5 tail and confirmed by site-directed mutagenesis. The β5 tail engages the kinase substrate-binding groove and positions the non-phosphorylatable integrin residue Glu767 at the phosphoacceptor site. Consistent with this, integrin β5 is poorly phosphorylated by PAK4, and in keeping with its ability to occlude the substrate-binding site, weakly inhibits kinase activity. These findings demonstrate the molecular basis for β5 integrin-PAK4 interactions but suggest modifications in understanding the potential cellular role of this interaction.
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De Simone I, Baaten CCFMJ, Jandrot-Perrus M, Gibbins JM, ten Cate H, Heemskerk JWM, Jones CI, van der Meijden PEJ. Coagulation Factor XIIIa and Activated Protein C Activate Platelets via GPVI and PAR1. Int J Mol Sci 2022; 23:ijms231810203. [PMID: 36142125 PMCID: PMC9499330 DOI: 10.3390/ijms231810203] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/24/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Platelet and coagulation activation are highly reciprocal processes driven by multi-molecular interactions. Activated platelets secrete several coagulation factors and expose phosphatidylserine, which supports the activation of coagulation factor proteins. On the other hand, the coagulation cascade generates known ligands for platelet receptors, such as thrombin and fibrin. Coagulation factor (F)Xa, (F)XIIIa and activated protein C (APC) can also bind to platelets, but the functional consequences are unclear. Here, we investigated the effects of the activated (anti)coagulation factors on platelets, other than thrombin. Multicolor flow cytometry and aggregation experiments revealed that the ‘supernatant of (hirudin-treated) coagulated plasma’ (SCP) enhanced CRP-XL-induced platelet responses, i.e., integrin αIIbβ3 activation, P-selectin exposure and aggregate formation. We demonstrated that FXIIIa in combination with APC enhanced platelet activation in solution, and separately immobilized FXIIIa and APC resulted in platelet spreading. Platelet activation by FXIIIa was inhibited by molecular blockade of glycoprotein VI (GPVI) or Syk kinase. In contrast, platelet spreading on immobilized APC was inhibited by PAR1 blockade. Immobilized, but not soluble, FXIIIa and APC also enhanced in vitro adhesion and aggregation under flow. In conclusion, in coagulation, factors other than thrombin or fibrin can induce platelet activation via GPVI and PAR receptors.
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Affiliation(s)
- Ilaria De Simone
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands
- School of Biological Sciences, Institute for Metabolic and Cardiovascular Research, University of Reading, Reading RG6 6AS, UK
| | - Constance C. F. M. J. Baaten
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands
- Institute for Molecular Cardiovascular Research, University Hospital Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Martine Jandrot-Perrus
- UMR_S1148, Laboratory for Vascular Translational Science, INSERM, University Paris Cité, F-75018 Paris, France
| | - Jonathan M. Gibbins
- School of Biological Sciences, Institute for Metabolic and Cardiovascular Research, University of Reading, Reading RG6 6AS, UK
| | - Hugo ten Cate
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands
- Thrombosis Expertise Center, Heart and Vascular Center, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
| | - Johan W. M. Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands
- Synapse Research Institute, 6217 KD Maastricht, The Netherlands
| | - Chris I. Jones
- School of Biological Sciences, Institute for Metabolic and Cardiovascular Research, University of Reading, Reading RG6 6AS, UK
- Correspondence: (C.I.J.); (P.E.J.v.d.M.); Tel.: +44-(0)-118-378-7047 (C.I.J.); +31-43-388-1684 (P.E.J.v.d.M.)
| | - Paola E. J. van der Meijden
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6200 MD Maastricht, The Netherlands
- Thrombosis Expertise Center, Heart and Vascular Center, Maastricht University Medical Center, 6229 HX Maastricht, The Netherlands
- Correspondence: (C.I.J.); (P.E.J.v.d.M.); Tel.: +44-(0)-118-378-7047 (C.I.J.); +31-43-388-1684 (P.E.J.v.d.M.)
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Abstract
Vascular smooth muscle cells (VSMC) are now considered important contributors to the pathophysiological and biophysical mechanisms underlying arterial stiffening in aging. Here, we review mechanisms whereby VSMC stiffening alters vascular function and contributes to the changes in vascular stiffening observed in aging and cardiovascular disease. Vascular stiffening in arterial aging was historically associated with changes in the extracellular matrix; however, new evidence suggests that endothelial and vascular smooth muscle cell stiffness also contribute to overall blood vessel stiffness. Furthermore, VSMC play an integral role in regulating matrix deposition and vessel wall contractility via interaction between the actomyosin contractile unit and adhesion structures that anchor the cell within the extracellular matrix. Aged-induce phenotypic modulation of VSMC from a contractile to a synthetic phenotype is associated with decreased cellular contractility and increased cell stiffness. Aged VSMC also display reduced mechanosensitivity and adaptation to mechanical signals from their microenvironment due to impaired intracellular signaling. Finally, evidence for decreased contractility in arteries from aged animals demonstrate that changes at the cellular level result in decreased functional properties at the tissue level.
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Carroll DJ, Cao Y, Bochner BS, O’Sullivan JA. Siglec-8 Signals Through a Non-Canonical Pathway to Cause Human Eosinophil Death In Vitro. Front Immunol 2021; 12:737988. [PMID: 34721399 PMCID: PMC8549629 DOI: 10.3389/fimmu.2021.737988] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/14/2021] [Indexed: 12/19/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectin (Siglec)-8 is a glycan-binding receptor bearing immunoreceptor tyrosine-based inhibitory and switch motifs (ITIM and ITSM, respectively) that is selectively expressed on eosinophils, mast cells, and, to a lesser extent, basophils. Previous work has shown that engagement of Siglec-8 on IL-5-primed eosinophils causes cell death via CD11b/CD18 integrin-mediated adhesion and NADPH oxidase activity and identified signaling molecules linking adhesion, reactive oxygen species (ROS) production, and cell death. However, the proximal signaling cascade activated directly by Siglec-8 engagement has remained elusive. Most members of the Siglec family possess similar cytoplasmic signaling motifs and recruit the protein tyrosine phosphatases SHP-1/2, consistent with ITIM-mediated signaling, to dampen cellular activation. However, the dependence of Siglec-8 function in eosinophils on these phosphatases has not been studied. Using Siglec-8 antibody engagement and pharmacological inhibition in conjunction with assays to measure cell-surface upregulation and conformational activation of CD11b integrin, ROS production, and cell death, we sought to identify molecules involved in Siglec-8 signaling and determine the stage of the process in which each molecule plays a role. We demonstrate here that the enzymatic activities of Src family kinases (SFKs), Syk, SHIP1, PAK1, MEK1, ERK1/2, PLC, PKC, acid sphingomyelinase/ceramidase, and Btk are all necessary for Siglec-8-induced eosinophil cell death, with no apparent role for SHP-1/2, SHIP2, or c-Raf. While most of these signaling molecules are necessary for Siglec-8-induced upregulation of CD11b integrin at the eosinophil cell surface, Btk is phosphorylated and activated later in the signaling cascade and is instead necessary for CD11b activation. In contrast, SFKs and ERK1/2 are phosphorylated far earlier in the process, consistent with their role in augmenting cell-surface levels of CD11b. In addition, pretreatment of eosinophils with latrunculin B or jasplakinolide revealed that actin filament disassembly is necessary and sufficient for surface CD11b integrin upregulation and that actin polymerization is necessary for downstream ROS production. These results show that Siglec-8 signals through an unanticipated set of signaling molecules in IL-5-primed eosinophils to induce cell death and challenges the expectation that ITIM-bearing Siglecs signal through inhibitory pathways involving protein tyrosine phosphatases to achieve their downstream functions.
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Affiliation(s)
| | | | | | - Jeremy A. O’Sullivan
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, United States
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Bakthavatsalam D, Craft JW, Kazansky A, Nguyen N, Bae G, Caivano AR, Gundlach CW, Aslam A, Ali S, Gupta S, Lin SY, Parthiban HD, Vanderslice P, Stephan CC, Woodside DG. Identification of Inhibitors of Integrin Cytoplasmic Domain Interactions With Syk. Front Immunol 2021; 11:575085. [PMID: 33488575 PMCID: PMC7819857 DOI: 10.3389/fimmu.2020.575085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 11/20/2020] [Indexed: 11/13/2022] Open
Abstract
Leukocyte inflammatory responses require integrin cell-adhesion molecule signaling through spleen tyrosine kinase (Syk), a non-receptor kinase that binds directly to integrin β-chain cytoplasmic domains. Here, we developed a high-throughput screen to identify small molecule inhibitors of the Syk-integrin cytoplasmic domain interactions. Screening small molecule compound libraries identified the β-lactam antibiotics cefsulodin and ceftazidime, which inhibited integrin β-subunit cytoplasmic domain binding to the tandem SH2 domains of Syk (IC50 range, 1.02–4.9 µM). Modeling suggested antagonist binding to Syk outside the pITAM binding site. Ceftazidime inhibited integrin signaling via Syk, including inhibition of adhesion-dependent upregulation of interleukin-1β and monocyte chemoattractant protein-1, but did not inhibit ITAM-dependent phosphorylation of Syk mediated by FcγRI signaling. Our results demonstrate a novel means to target Syk independent of its kinase and pITAM binding sites such that integrin signaling via this kinase is abrogated but ITAM-dependent signaling remains intact. As integrin signaling through Syk is essential for leukocyte activation, this may represent a novel approach to target inflammation.
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Affiliation(s)
| | - John W Craft
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States.,Department of Biology and Chemistry, University of Houston, Houston, TX, United States
| | - Anna Kazansky
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Nghi Nguyen
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, United States
| | - Goeun Bae
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, United States
| | - Amy R Caivano
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - C William Gundlach
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Asra Aslam
- Department of Biology and Chemistry, University of Houston, Houston, TX, United States
| | - Safa Ali
- Department of Biology and Chemistry, University of Houston, Houston, TX, United States
| | - Shashikant Gupta
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Sophie Y Lin
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Hema D Parthiban
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Peter Vanderslice
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
| | - Clifford C Stephan
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX, United States
| | - Darren G Woodside
- Molecular Cardiology Research Laboratories, Texas Heart Institute, Houston, TX, United States
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Loureiro CA, Pinto FR, Barros P, Matos P, Jordan P. A SYK/SHC1 pathway regulates the amount of CFTR in the plasma membrane. Cell Mol Life Sci 2020; 77:4997-5015. [PMID: 31974654 PMCID: PMC11105000 DOI: 10.1007/s00018-020-03448-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 12/06/2019] [Accepted: 01/02/2020] [Indexed: 11/24/2022]
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the recessive genetic disease cystic fibrosis, where the chloride transport across the apical membrane of epithelial cells mediated by the CFTR protein is impaired. CFTR protein trafficking to the plasma membrane (PM) is the result of a complex interplay between the secretory and membrane recycling pathways that control the number of channels present at the membrane. In addition, the ion transport activity of CFTR at the PM is modulated through post-translational protein modifications. Previously we described that spleen tyrosine kinase (SYK) phosphorylates a specific tyrosine residue in the nucleotide-binding domain 1 domain and this modification can regulate the PM abundance of CFTR. Here we identified the underlying biochemical mechanism using peptide pull-down assays followed by mass spectrometry. We identified in bronchial epithelial cells that the adaptor protein SHC1 recognizes tyrosine-phosphorylated CFTR through its phosphotyrosine-binding domain and that the formation of a complex between SHC1 and CFTR is induced at the PM in the presence of activated SYK. The depletion of endogenous SHC1 expression was sufficient to promote an increase in CFTR at the PM of these cells. The results identify a SYK/SHC1 pathway that regulates the PM levels of CFTR channels, contributing to a better understanding of how CFTR-mediated chloride secretion is regulated.
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Affiliation(s)
- Cláudia Almeida Loureiro
- Department of Human Genetics, National Health Institute 'Dr. Ricardo Jorge', Avenida Padre Cruz, 1649-016, Lisbon, Portugal
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Francisco R Pinto
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Patrícia Barros
- Department of Human Genetics, National Health Institute 'Dr. Ricardo Jorge', Avenida Padre Cruz, 1649-016, Lisbon, Portugal
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Paulo Matos
- Department of Human Genetics, National Health Institute 'Dr. Ricardo Jorge', Avenida Padre Cruz, 1649-016, Lisbon, Portugal
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Peter Jordan
- Department of Human Genetics, National Health Institute 'Dr. Ricardo Jorge', Avenida Padre Cruz, 1649-016, Lisbon, Portugal.
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
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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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Singh RK, Haka AS, Asmal A, Barbosa-Lorenzi VC, Grosheva I, Chin HF, Xiong Y, Hla T, Maxfield FR. TLR4 (Toll-Like Receptor 4)-Dependent Signaling Drives Extracellular Catabolism of LDL (Low-Density Lipoprotein) Aggregates. Arterioscler Thromb Vasc Biol 2019; 40:86-102. [PMID: 31597445 DOI: 10.1161/atvbaha.119.313200] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Aggregation and modification of LDLs (low-density lipoproteins) promote their retention and accumulation in the arteries. This is a critical initiating factor during atherosclerosis. Macrophage catabolism of agLDL (aggregated LDL) occurs using a specialized extracellular, hydrolytic compartment, the lysosomal synapse. Compartment formation by local actin polymerization and delivery of lysosomal contents by exocytosis promotes acidification of the compartment and degradation of agLDL. Internalization of metabolites, such as cholesterol, promotes foam cell formation, a process that drives atherogenesis. Furthermore, there is accumulating evidence for the involvement of TLR4 (Toll-like receptor 4) and its adaptor protein MyD88 (myeloid differentiation primary response 88) in atherosclerosis. Here, we investigated the role of TLR4 in catabolism of agLDL using the lysosomal synapse and foam cell formation. Approach and Results: Using bone marrow-derived macrophages from knockout mice, we find that TLR4 and MyD88 regulate compartment formation, lysosome exocytosis, acidification of the compartment, and foam cell formation. Using siRNA (small interfering RNA), pharmacological inhibition and knockout bone marrow-derived macrophages, we implicate SYK (spleen tyrosine kinase), PI3K (phosphoinositide 3-kinase), and Akt in agLDL catabolism using the lysosomal synapse. Using bone marrow transplantation of LDL receptor knockout mice with TLR4 knockout bone marrow, we show that deficiency of TLR4 protects macrophages from lipid accumulation during atherosclerosis. Finally, we demonstrate that macrophages in vivo form an extracellular compartment and exocytose lysosome contents similar to that observed in vitro for degradation of agLDL. CONCLUSIONS We present a mechanism in which interaction of macrophages with agLDL initiates a TLR4 signaling pathway, resulting in formation of the lysosomal synapse, catabolism of agLDL, and lipid accumulation in vitro and in vivo.
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Affiliation(s)
- Rajesh K Singh
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Abigail S Haka
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Arky Asmal
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Valéria C Barbosa-Lorenzi
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Inna Grosheva
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Harvey F Chin
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
| | - Yuquan Xiong
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA (Y.X., T.H.).,Current address: Thoracic Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY (Y.X.)
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital and Department of Surgery, Harvard Medical School, Boston, MA (Y.X., T.H.)
| | - Frederick R Maxfield
- From the Department of Biochemistry, Weill Cornell Medical College, New York, NY (R.K.S., A.S.H., A.A., V.C.B.-L., I.G., H.F.C., F.R.M.)
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11
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Thome S, Begandt D, Pick R, Salvermoser M, Walzog B. Intracellular β 2 integrin (CD11/CD18) interacting partners in neutrophil trafficking. Eur J Clin Invest 2018; 48 Suppl 2:e12966. [PMID: 29896791 DOI: 10.1111/eci.12966] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 06/10/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Neutrophil recruitment during acute inflammation critically depends on the spatial and temporal regulation of β2 integrins (CD11/CD18). This regulation occurs by inside-out and outside-in signalling via interaction of cytoplasmic proteins with the intracellular domains of the integrin α- and β-subunits. The underlying molecular mechanisms regulating β2 integrins in neutrophils are still incompletely understood. AIM This review provides a comprehensive overview of our current knowledge on proteins interacting with the cytoplasmic tail of CD18, the conserved β-subunit of β2 integrins, their regulation and their functional importance for neutrophil trafficking during acute inflammation. RESULTS A total of 22 proteins including Talin, Kindlin 3 and Coronin 1A have been reported to interact with the CD18 cytoplasmic tail. Here, proteins binding to the cytoplasmic domain of CD18 in experiments using purified, recombinant proteins or peptides in, for example, pull-down assays, are defined as direct interactors. Proteins that have been shown to interact with the cytoplasmic domain of CD18 using whole cell lysates in, for example, pull-down experiments are claimed as interacting proteins without evidence for direct interaction. In summary, β2 integrin activation and signalling depend on a specific subset of proteins interacting with CD18 and their precise regulation. If disturbed, profound defects of neutrophil recruitment and activation become evident compromising the innate immune response. CONCLUSIONS The knowledge of proteins interacting with β2 integrins and their regulation during neutrophil trafficking does not only improve our basic understanding of innate immunity but may pave the way to novel therapeutic strategies in the treatment of inflammatory diseases.
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Affiliation(s)
- Sarah Thome
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Daniela Begandt
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Robert Pick
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Melanie Salvermoser
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Barbara Walzog
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Planegg-Martinsried, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
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12
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Song N, Li T. Regulation of NLRP3 Inflammasome by Phosphorylation. Front Immunol 2018; 9:2305. [PMID: 30349539 PMCID: PMC6186804 DOI: 10.3389/fimmu.2018.02305] [Citation(s) in RCA: 150] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 09/17/2018] [Indexed: 01/01/2023] Open
Abstract
The cytosolic pattern recognition receptor (PRR) NOD-like receptor family, pyrin domain containing 3 (NLRP3) senses a wide range of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Upon activation, NLRP3 triggers the assembly of inflammasome via the self-oligomerization and the recruitment of apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) and pro-caspase-1, facilitating the robust immune responses including the secretion of proinflammatory cytokines and pyroptosis. The NLRP3 inflammasome must be well orchestrated to prevent the aberrant activations under physiological and pathological conditions, because uncontrolled activation of NLRP3 inflammasome is one of the major causes of a variety of autoimmune diseases and metabolic disorders. Therefore, understanding the molecular mechanisms for controlling NLRP3 inflammasome activation may provide novel strategies for the treatment of NLRP3-related diseases. Although NLRP3 inflammasome can be regulated at the transcriptional level, the post-translational modification (PTM) of NLRP3 as well as other inflammasome components has also been showed to be critical for the regulation of its activation. Several kinases and phosphatases have been shown to control NLRP3 inflammasome activation in response to either exogenous pathogen infections or endogenous molecules, such as bile acids. In this review, we summarize our current knowledge of phosphorylation patterns and their functional role in the regulation of NLRP3 inflammasome, and suggest interesting areas for future research.
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Affiliation(s)
- Nan Song
- Beijing Tropical Medicine Research Institute, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,State Key Laboratory of Proteomics, Beijing Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing, China
| | - Tao Li
- State Key Laboratory of Proteomics, Beijing Institute of Basic Medical Sciences, National Center of Biomedical Analysis, Beijing, China.,State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
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13
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Antenucci L, Hytönen VP, Ylänne J. Phosphorylated immunoreceptor tyrosine-based activation motifs and integrin cytoplasmic domains activate spleen tyrosine kinase via distinct mechanisms. J Biol Chem 2018; 293:4591-4602. [PMID: 29440271 DOI: 10.1074/jbc.ra117.000660] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/07/2018] [Indexed: 11/06/2022] Open
Abstract
Spleen tyrosine kinase (Syk) is involved in cellular adhesion and also in the activation and development of hematopoietic cells. Syk activation induced by genomic rearrangement has been linked to certain T-cell lymphomas, and Syk inhibitors have been shown to prolong survival of patients with B-cell lineage malignancies. Syk is activated either by its interaction with a double-phosphorylated immunoreceptor tyrosine-based activation motif (pITAM), which induces rearrangements in the Syk structure, or by the phosphorylation of specific tyrosine residues. In addition to its immunoreceptor function, Syk is activated downstream of integrin pathways, and integrins bind to the same region in Syk as does pITAM. However, it is unknown whether integrins and pITAM use the same mechanism to activate Syk. Here, using purified Syk protein and fluorescence-based enzyme assay we investigated whether interaction of the integrin β3 cytoplasmic domain with the Syk regulatory domain causes changes in Syk activity similar to those induced by pITAM peptides. We observed no direct Syk activation by soluble integrin peptide, and integrin did not compete with pITAM-induced activation even though at high concentrations, the integrin cytoplasmic domain peptide competed with Syk's substrate. However, clustered integrin peptides induced Syk activation, presumably via a transphosphorylation mechanism. Moreover, the clustered integrins also activated a Syk variant in which tyrosines were replaced with phenylalanine (Y348F/Y352F), indicating that clustered integrin-induced Syk activation involved other phosphorylation sites. In conclusion, integrin cytoplasmic domains do not directly induce Syk conformational changes and do not activate Syk via the same mechanism as pITAM.
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Affiliation(s)
- Lina Antenucci
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Survontie 9 C, 40014 Jyväskylä, Finland.
| | - Vesa P Hytönen
- Faculty of Medicine and Life Sciences and BioMediTech, University of Tampere, and Fimlab Laboratories, Tampere 33014, Finland
| | - Jari Ylänne
- Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Survontie 9 C, 40014 Jyväskylä, Finland
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14
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Abstract
Integrin αIIbβ3 is a highly abundant heterodimeric platelet receptor that can transmit information bidirectionally across the plasma membrane, and plays a critical role in hemostasis and thrombosis. Upon platelet activation, inside-out signaling pathways increase the affinity of αIIbβ3 for fibrinogen and other ligands. Ligand binding and integrin clustering subsequently stimulate outside-in signaling, which initiates and amplifies a range of cellular events driving essential platelet processes such as spreading, thrombus consolidation, and clot retraction. Integrin αIIbβ3 has served as an excellent model for the study of integrin biology, and it has become clear that integrin outside-in signaling is highly complex and involves a vast array of enzymes, signaling adaptors, and cytoskeletal components. In this review, we provide a concise but comprehensive overview of αIIbβ3 outside-in signaling, focusing on the key players involved, and how they cooperate to orchestrate this critical aspect of platelet biology. We also discuss gaps in the current understanding of αIIbβ3 outside-in signaling and highlight avenues for future investigation.
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15
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Shapiro LP, Parsons RG, Koleske AJ, Gourley SL. Differential expression of cytoskeletal regulatory factors in the adolescent prefrontal cortex: Implications for cortical development. J Neurosci Res 2017; 95:1123-1143. [PMID: 27735056 PMCID: PMC5352542 DOI: 10.1002/jnr.23960] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 09/04/2016] [Accepted: 09/12/2016] [Indexed: 12/27/2022]
Abstract
The prevalence of depression, anxiety, schizophrenia, and drug and alcohol use disorders peaks during adolescence. Further, up to 50% of "adult" mental health disorders emerge in adolescence. During adolescence, the prefrontal cortex (PFC) undergoes dramatic structural reorganization, in which dendritic spines and synapses are refined, pruned, and stabilized. Understanding the molecular mechanisms that underlie these processes should help to identify factors that influence the development of psychiatric illness. Here we briefly discuss the anatomical connections of the medial and orbital prefrontal cortex (mPFC and OFC, respectively). We then present original findings suggesting that dendritic spines on deep-layer excitatory neurons in the mouse mPFC and OFC prune at different adolescent ages, with later pruning in the OFC. In parallel, we used Western blotting to define levels of several cytoskeletal regulatory proteins during early, mid-, and late adolescence, focusing on tropomyosin-related kinase receptor B (TrkB) and β1-integrin-containing receptors and select signaling partners. We identified regional differences in the levels of several proteins in early and midadolescence that then converged in early adulthood. We also observed age-related differences in TrkB levels, both full-length and truncated isoforms, Rho-kinase 2, and synaptophysin in both PFC subregions. Finally, we identified changes in protein levels in the dorsal and ventral hippocampus that were distinct from those in the PFC. We conclude with a general review of the manner in which TrkB- and β1-integrin-mediated signaling influences neuronal structure in the postnatal brain. Elucidating the role of cytoskeletal regulatory factors throughout adolescence may identify critical mechanisms of PFC development. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Lauren P Shapiro
- Molecular and Systems Pharmacology, Emory University, Atlanta, Georgia
- Departments of Pediatrics and Psychiatry and Behavioral Sciences, Emory University School of Medicine, and Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
| | - Ryan G Parsons
- Department of Psychology and Neuroscience Institute, Graduate Program in Integrative Neuroscience, Program in Neuroscience, Stony Brook University, Stony Brook, New York
| | - Anthony J Koleske
- Department of Molecular Biophysics and Biochemistry, Department of Neurobiology, Interdepartmental Neuroscience Program, Yale University, New Haven, Connecticut
| | - Shannon L Gourley
- Departments of Pediatrics and Psychiatry and Behavioral Sciences, Emory University School of Medicine, and Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
- Graduate Program in Neuroscience, Emory University, Atlanta, Georgia
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16
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Singh R. Central role of PI3K-SYK interaction in fibrinogen-induced lamellipodia and filopodia formation in platelets. FEBS Open Bio 2016; 6:1285-1296. [PMID: 28255536 PMCID: PMC5324771 DOI: 10.1002/2211-5463.12149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 10/05/2016] [Accepted: 10/18/2016] [Indexed: 12/27/2022] Open
Abstract
The WAVE complex‐1, a complex of WAVE, Abi1, NAP1, PIR121, HSPC300, RacGTP and Arp2/3 proteins, and WASP complex‐1, a complex of WASP, Cdc42, PIP2, and Arp2/3 proteins, are involved in lamellipodia and filopodia formation, respectively. It is known that the two complexes have opposite dynamics. Furthermore, Rac has two guanine nucleotide exchange factors, Vav and Sos, whose role in activating Rac is not well understood. In this work, by the construction of signaling network, analysis, and mathematical modeling, I show that Sos generates a pulse of WAVE complex‐1, decreasing the response time of WAVE complex‐1 formation upon the stimulation of platelets by fibrinogen. Furthermore, I also show that the dynamics of WAVE and WASP complexes depends on PI3K–SYK interaction. In the absence of this interaction, the WAVE complex‐1 does not form and the WASP complex‐1 remains at the initial, sustained level. Thus, I show the significance of the two protein/protein complexes: Sos and PI3K–SYK interaction, in fibrinogen‐induced lamellipodia and filopodia formation in platelets.
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Affiliation(s)
- Raghvendra Singh
- Department of Chemical Engineering Indian Institute of Technology Kanpur India
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17
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Zhou Y, Abraham S, Renna S, Edelstein LC, Dangelmaier CA, Tsygankov AY, Kunapuli SP, Bray PF, McKenzie SE. TULA-2 (T-Cell Ubiquitin Ligand-2) Inhibits the Platelet Fc Receptor for IgG IIA (FcγRIIA) Signaling Pathway and Heparin-Induced Thrombocytopenia in Mice. Arterioscler Thromb Vasc Biol 2016; 36:2315-2323. [PMID: 27765766 DOI: 10.1161/atvbaha.116.307979] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 10/04/2016] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The objective of this study is to investigate the role of T-cell ubiquitin ligand-2 (TULA-2) in the platelet Fc receptor for IgG IIA (FcγRIIA) pathway and in the pathogenesis of heparin-induced thrombocytopenia (HIT). APPROACH AND RESULTS HIT is a life-threatening thrombotic disease in which IgG antibodies against the heparin-platelet factor 4 complex activate platelets via FcγRIIA. We reported previously differential expression of TULA-2 in human population was linked to FcγRIIA responsiveness. In this study, we investigated the role of TULA-2, a protein phosphatase, in the FcγRIIA pathway and HIT pathogenesis by crossing TULA-2-/- mice with transgenic FcγRIIA +/+ mice. Ablation of TULA-2 resulted in hyperphosphorylation of spleen tyrosine kinase, linker for the activation of T cells, and phospholipase Cγ2 in platelets via FcγRIIA activation. Platelet integrin activation, granule secretion, phosphatidylserine exposure, and aggregation were also enhanced in TULA-2-/- murine platelets. Compared with wild-type mice, TULA-2-/- mice showed aggravated antibody-mediated thrombocytopenia, augmented thrombin generation, and shortened tail bleeding time. In contrast, there was no significant difference between TULA-2-/- and TULA-2+/+ platelets in platelet spreading and clot retraction. Of note, heterozygous TULA-2+/- mice, whose platelets contained 50% as much protein as the TULA-2+/+ platelets, showed significantly increased platelet reactivity and more severe thrombocytopenia in vivo compared with TULA-2+/+ mice. CONCLUSIONS Together, the data demonstrate that not only the absence of TULA-2 but also the relative level of TULA-2 expression modulates FcγRIIA-mediated platelet reactivity and HIT in vivo. TULA-2 expression could be a valuable marker for HIT and inhibiting TULA-2 may serve as a potential therapy to reverse the bleeding adverse effect of anticoagulants.
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Affiliation(s)
- Yuhang Zhou
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Shaji Abraham
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Stephanie Renna
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Leonard C Edelstein
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Carol A Dangelmaier
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Alexander Y Tsygankov
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Satya P Kunapuli
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Paul F Bray
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Steven E McKenzie
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.).
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18
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Fong KP, Zhu H, Span LM, Moore DT, Yoon K, Tamura R, Yin H, DeGrado WF, Bennett JS. Directly Activating the Integrin αIIbβ3 Initiates Outside-In Signaling by Causing αIIbβ3 Clustering. J Biol Chem 2016; 291:11706-16. [PMID: 27056329 DOI: 10.1074/jbc.m116.716613] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Indexed: 11/06/2022] Open
Abstract
αIIbβ3 activation in platelets is followed by activation of the tyrosine kinase c-Src associated with the carboxyl terminus of the β3 cytosolic tail. Exogenous peptides designed to interact with the αIIb transmembrane (TM) domain activate single αIIbβ3 molecules in platelets by binding to the αIIb TM domain and causing separation of the αIIbβ3 TM domain heterodimer. Here we asked whether directly activating single αIIbβ3 molecules in platelets using the designed peptide anti-αIIb TM also initiates αIIbβ3-mediated outside-in signaling by causing activation of β3-associated c-Src. Anti-αIIb TM caused activation of β3-associated c-Src and the kinase Syk, but not the kinase FAK, under conditions that precluded extracellular ligand binding to αIIbβ3. c-Src and Syk are activated by trans-autophosphorylation, suggesting that activation of individual αIIbβ3 molecules can initiate αIIbβ3 clustering in the absence of ligand binding. Consistent with this possibility, incubating platelets with anti-αIIb TM resulted in the redistribution of αIIbβ3 from a homogenous ring located at the periphery of discoid platelets into nodular densities consistent with clustered αIIbβ3. Thus, these studies indicate that not only is resting αIIbβ3 poised to undergo a conformational change that exposes its ligand-binding site, but it is poised to rapidly assemble into intracellular signal-generating complexes as well.
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Affiliation(s)
- Karen P Fong
- From the Hematology-Oncology Division, Department of Medicine, and
| | - Hua Zhu
- From the Hematology-Oncology Division, Department of Medicine, and
| | - Lisa M Span
- From the Hematology-Oncology Division, Department of Medicine, and
| | - David T Moore
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Kyungchul Yoon
- From the Hematology-Oncology Division, Department of Medicine, and
| | - Ryo Tamura
- the Department of Chemistry and Biochemistry and the BioFrontiers Institute, University of Colorado, Boulder, Colorado 80030, and
| | - Hang Yin
- the Department of Chemistry and Biochemistry and the BioFrontiers Institute, University of Colorado, Boulder, Colorado 80030, and
| | - William F DeGrado
- the Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158-9001
| | - Joel S Bennett
- From the Hematology-Oncology Division, Department of Medicine, and
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19
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αv Integrins combine with LC3 and atg5 to regulate Toll-like receptor signalling in B cells. Nat Commun 2016; 7:10917. [PMID: 26965188 PMCID: PMC4792966 DOI: 10.1038/ncomms10917] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 02/01/2016] [Indexed: 12/18/2022] Open
Abstract
Integrin signalling triggers cytoskeletal rearrangements, including endocytosis and exocytosis of integrins and other membrane proteins. In addition to recycling integrins, this trafficking can also regulate intracellular signalling pathways. Here we describe a role for αv integrins in regulating Toll-like receptor (TLR) signalling by modulating intracellular trafficking. We show that deletion of αv or β3 causes increased B-cell responses to TLR stimulation in vitro, and αv-conditional knockout mice have elevated antibody responses to TLR-ligand-associated antigens. αv regulates TLR signalling by promoting recruitment of the autophagy component LC3 (microtubule-associated proteins 1 light chain 3) to TLR-containing endosomes, which is essential for progression from NF-κB to IRF signalling, and ultimately for traffic to lysosomes where signalling is terminated. Disruption of LC3 recruitment leads to prolonged NF-κB signalling and increased B-cell proliferation and antibody production. This work identifies a previously unrecognized role for αv and the autophagy components LC3 and atg5 in regulating TLR signalling and B-cell immunity. Integrins can regulate antigen-specific and innate immune receptor signalling, thereby affecting immune cell function. Here the authors show that avß3 integrin controls Toll-like receptor (TLR) signalling by regulating its trafficking to limit TLR-mediated B-cell proliferation and antibody production.
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20
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Buitrago L, Manne BK, Andre P, McKenzie S, Kunapuli S. Identification of novel Syk-independent functional roles of FcγRIIa in platelet outside-in signaling using transgenic mice expressing human FcγRIIa. Platelets 2016; 27:488-90. [PMID: 26809427 DOI: 10.3109/09537104.2015.1119813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Lorena Buitrago
- a Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.,b Sol Sherry Thrombosis Research Center , Temple University School of Medicine , Philadelphia , PA , USA
| | - Bhanu Kanth Manne
- a Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.,b Sol Sherry Thrombosis Research Center , Temple University School of Medicine , Philadelphia , PA , USA
| | - Pierrette Andre
- c Cardeza Foundation and Department of Medicine , Thomas Jefferson University , Philadelphia , PA , USA
| | - Steven McKenzie
- c Cardeza Foundation and Department of Medicine , Thomas Jefferson University , Philadelphia , PA , USA
| | - Satya Kunapuli
- a Department of Physiology , Temple University School of Medicine , Philadelphia , PA , USA.,b Sol Sherry Thrombosis Research Center , Temple University School of Medicine , Philadelphia , PA , USA
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21
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Lagarrigue F, Vikas Anekal P, Lee HS, Bachir AI, Ablack JN, Horwitz AF, Ginsberg MH. A RIAM/lamellipodin-talin-integrin complex forms the tip of sticky fingers that guide cell migration. Nat Commun 2015; 6:8492. [PMID: 26419705 PMCID: PMC4589889 DOI: 10.1038/ncomms9492] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/26/2015] [Indexed: 01/10/2023] Open
Abstract
The leading edge of migrating cells contains rapidly translocating activated integrins associated with growing actin filaments that form 'sticky fingers' to sense extracellular matrix and guide cell migration. Here we utilized indirect bimolecular fluorescence complementation to visualize a molecular complex containing a Mig-10/RIAM/lamellipodin (MRL) protein (Rap1-GTP-interacting adaptor molecule (RIAM) or lamellipodin), talin and activated integrins in living cells. This complex localizes at the tips of growing actin filaments in lamellipodial and filopodial protrusions, thus corresponding to the tips of the 'sticky fingers.' Formation of the complex requires talin to form a bridge between the MRL protein and the integrins. Moreover, disruption of the MRL protein-integrin-talin (MIT) complex markedly impairs cell protrusion. These data reveal the molecular basis of the formation of 'sticky fingers' at the leading edge of migrating cells and show that an MIT complex drives these protrusions.
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Affiliation(s)
- Frederic Lagarrigue
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Praju Vikas Anekal
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Ho-Sup Lee
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alexia I Bachir
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jailal N Ablack
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Alan F Horwitz
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Mark H Ginsberg
- Department of Medicine, University of California San Diego, La Jolla, California 92093, USA
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22
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Integrin αIIbβ3 transmembrane domain separation mediates bi-directional signaling across the plasma membrane. PLoS One 2015; 10:e0116208. [PMID: 25617834 PMCID: PMC4305291 DOI: 10.1371/journal.pone.0116208] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 12/06/2014] [Indexed: 11/19/2022] Open
Abstract
Integrins play an essential role in hemostasis, thrombosis, and cell migration, and they transmit bidirectional signals. Transmembrane/cytoplasmic domains are hypothesized to associate in the resting integrins; whereas, ligand binding and intracellular activating signals induce transmembrane domain separation. However, how this conformational change affects integrin outside-in signaling and whether the α subunit cytoplasmic domain is important for this signaling remain elusive. Using Chinese Hamster Ovary (CHO) cells that stably expressed different integrin αIIbβ3 constructs, we discovered that an αIIb cytoplasmic domain truncation led to integrin activation but not defective outside-in signaling. In contrast, preventing transmembrane domain separation abolished both inside-out and outside-in signaling regardless of removing the αIIb cytoplasmic tail. Truncation of the αIIb cytoplasmic tail did not obviously affect adhesion-induced outside-in signaling. Our research revealed that transmembrane domain separation is a downstream conformational change after the cytoplasmic domain dissociation in inside-out activation and indispensable for ligand-induced outside-in signaling. The result implicates that the β TM helix rearrangement after dissociation is essential for integrin transmembrane signaling. Furthermore, we discovered that the PI3K/Akt pathway is not essential for cell spreading but spreading-induced Erk1/2 activation is PI3K dependent implicating requirement of the kinase for cell survival in outside-in signaling.
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The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets. Blood 2014; 125:144-54. [PMID: 25352128 DOI: 10.1182/blood-2014-05-579375] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We have used a novel knockin mouse to investigate the effect of disruption of phosphotyrosine binding of the N-terminal SH2 domain of Syk on platelet activation by GPVI, CLEC-2, and integrin αIIbβ3. The Syk(R41Afl/fl) mouse was crossed to a PF4-Cre(+) mouse to induce expression of the Syk mutant in the megakaryocyte/platelet lineage. Syk(R41Afl/fl;PF4-Cre) mice are born at approximately 50% of the expected frequency and have a similar phenotype to Syk(fl/fl;PF4-Cre) mice, including blood-lymphatic mixing and chyloascites. Anastomosis of the venous and lymphatic vasculatures can be seen in the mesenteric circulation accounting for rapid and continuous mixing of the 2 vasculatures. Platelet activation by CLEC-2 and GPVI is abolished in Syk(R41Afl/fl;PF4-Cre) platelets. Syk phosphorylation on Tyr519/20 is blocked in CLEC-2-stimulated platelets, suggesting a model in which binding of Syk via its N-terminal SH2 domain regulates autophosphorylation. In contrast, outside-in signaling by integrin αIIbβ3 is not altered, but it is inhibited in the presence of inhibitors of Src and Syk tyrosine kinases. These results demonstrate that αIIbβ3 regulates Syk through an ITAM-independent pathway in mice and provide novel insight into the course of events underlying Syk activation and hemITAM phosphorylation by CLEC-2.
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24
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Sreenivasappa H, Chaki SP, Lim SM, Trzeciakowski JP, Davidson MW, Rivera GM, Trache A. Selective regulation of cytoskeletal tension and cell–matrix adhesion by RhoA and Src. Integr Biol (Camb) 2014; 6:743-54. [DOI: 10.1039/c4ib00019f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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25
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Fei B, Yu S, Geahlen RL. Modulation by Syk of Bcl-2, calcium and the calpain-calpastatin proteolytic system in human breast cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2153-64. [PMID: 23684705 DOI: 10.1016/j.bbamcr.2013.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/07/2013] [Accepted: 05/09/2013] [Indexed: 01/02/2023]
Abstract
Syk is a 72kDa non-receptor tyrosine kinase that is best characterized in hematopoietic cells. While Syk is pro-tumorigenic in some cancer cell types, it also has been reported as a negative regulator of metastatic cell growth in others. An examination of the RelA (p65) subunit of NF-κB expressed in MCF7 breast cancer cells indicated that either treatment with pervanadate or stable expression of Syk protected RelA from calpain-mediated proteolysis. Similar results were observed with the tyrosine phosphatase, PTP1B, another sensitive calpain substrate. The activity of calpain in MCF7 cell lysates was inhibited by both treatment with hydrogen peroxide and expression of Syk, the former due to oxidative inactivation of calpain and the latter to enhanced expression of calpastatin (CAST), the endogenous calpain inhibitor. The level of CAST was elevated in the cytosolic fraction of Syk-positive breast cancer cells resulting in more CAST present in complex with calpain in cell lysates. The high levels of CAST coincided with elevated basal levels of calcium-and of intracellular calpain activity-in Syk-expressing cells resulting from decreased levels of Bcl-2, an inhibitor of IP3-receptor-mediated calcium release. The inhibition of cellular calpain stimulated the Syk-mediated enhancement of NF-κB induced by TNF-α, enhanced tyrosine phosphorylation resulting from integrin crosslinking, and increased the localization of Syk to the plasma membrane.
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Affiliation(s)
- Bei Fei
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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26
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Boyle KB, Stephens LR, Hawkins PT. Activation of the neutrophil NADPH oxidase by Aspergillus fumigatus. Ann N Y Acad Sci 2013; 1273:68-73. [PMID: 23230839 DOI: 10.1111/j.1749-6632.2012.06821.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Upon infection of the respiratory system with the fungus Aspergillus fumigatus various leukoctytes, in particular neutrophils, are recruited to the lung to mount an immune response. Neutrophils respond by both phagocytosing conidia and mediating extracellular killing of germinated, invasive hyphae. Of paramount importance to an appropriate immune response is the neutrophil NADPH oxidase enzyme, which mediates the production of various reactive oxygen species (ROS). This is evidenced by the acute sensitivity of both oxidase-deficient humans and mice to invasive aspergillosis. Herein we briefly review the mechanisms and functions of oxidase activation and discuss our recent work identifying at least some of the important players in hyphal-induced oxidase activation and neutrophil function. Among these we define the phosphoinositide 3-kinase enzyme and the regulatory protein Vav to be of critical importance and allude to a kinase-independent role for Syk.
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Affiliation(s)
- Keith B Boyle
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
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27
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Hung WS, Huang CL, Fan JT, Huang DY, Yeh CF, Cheng JC, Tseng CP. The endocytic adaptor protein Disabled-2 is required for cellular uptake of fibrinogen. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1778-88. [PMID: 22705885 DOI: 10.1016/j.bbamcr.2012.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Revised: 05/22/2012] [Accepted: 06/07/2012] [Indexed: 10/28/2022]
Abstract
Endocytosis is pivotal for uptake of fibrinogen from plasma into megakaryocytes and platelet α-granules. Due to the complex adaptor and cargo contents in endocytic vehicles, the underlying mechanism of fibrinogen uptake is not yet completely elucidated. In this study, we investigated whether the endocytic adaptor protein Disabled-2 (DAB2) mediates fibrinogen uptake in an adaptor-specific manner. By employing primary megakaryocytes and megakaryocytic differentiating human leukemic K562 cells as the study models, we found that fibrinogen uptake is associated with the expression of integrin αIIbβ3 and DAB2 and is mediated through clathrin-dependent manner. Accordingly, constitutive and inducible knockdown of DAB2 by small interfering RNA reduced fibrinogen uptake for 53.2 ± 9.8% and 59.0 ± 10.7%, respectively. Culturing the cells in hypertonic solution or in the presence of clathrin inhibitor chlorpromazine abrogated clathrin-dependent endocytosis and diminished the uptake of fibrinogen. Consistent with these findings, 72.2 ± 0.2% of cellular DAB2 was colocalized with clathrin, whereas 56.4±4.1% and 54.6 ± 2.0% of the internalized fibrinogen were colocalized with clathrin and DAB2, respectively. To delineate whether DAB2 mediates fibrinogen uptake in an adaptor-specific manner, K562 stable cell lines with knockdown of the adaptor protein-2 (AP-2) or double knockdown of AP-2/DAB2 were established. The AP-2 knockdown cells elicited normal fibrinogen uptake activity but the uptake of collagen was diminished. In addition, collagen uptake was further reduced in DAB2/AP-2 knockdown cells. These findings thereby define an adaptor-specific mechanism in the control of fibrinogen uptake and implicate that DAB2 is the key adaptor in the clathrin-associated endocytic complexes to mediate fibrinogen internalization.
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Affiliation(s)
- Wei-Shan Hung
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan, ROC
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28
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Horn M, Bertling A, Brodde MF, Müller A, Roth J, Van Aken H, Jurk K, Heilmann C, Peters G, Kehrel BE. Human neutrophil alpha-defensins induce formation of fibrinogen and thrombospondin-1 amyloid-like structures and activate platelets via glycoprotein IIb/IIIa. J Thromb Haemost 2012; 10:647-61. [PMID: 22268819 DOI: 10.1111/j.1538-7836.2012.04640.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Human neutrophil α-defensins (HNPs) are important constituents of the innate immune system. Beyond their antimicrobial properties, HNPs also have pro-inflammatory features. While HNPs in plasma from healthy individuals are barely detectable, their level is strongly elevated in septic plasma and plasma from patients with acute coronary syndromes. OBJECTIVES As thrombosis and inflammation are intertwined processes and activation of human polymorphonuclear leukocytes (PMNL) and subsequent degranulation is associated with full activation of surrounding platelets, we studied the effect of HNPs on platelet function. METHODS The effect of HNPs on platelet activation parameters and apoptosis was investigated via aggregometry, flow cytometry, confocal microscopy and the ELISA technique. RESULTS It was found that HNPs activate platelets in pathophysiologically relevant doses, inducing fibrinogen and thrombospondin-1 binding, aggregation, granule secretion, sCD40L shedding, and procoagulant activity. HNPs bound directly to the platelet membrane, induced membrane pore formation, microparticle formation, mitochondrial membrane depolarization and caspase-3-activity. Confocal microscopy revealed the HNP-induced formation of polymeric fibrinogen and thrombospondin-1 amyloid-like structures, which bound microorganisms. Platelets adhered to these structures and formed aggregates. Blocking of glycoprotein IIb/IIIa (GPIIb/IIIa) markedly inhibited HNP-induced platelet activation. In addition, heparin, heparinoid, serpins and α(2)-macroglobulin, which all bind to HNPs, blocked HNP-1-induced platelet activation in contrast to direct thrombin inhibitors such as hirudin. CONCLUSIONS HNPs activate platelets and induce platelet apoptosis by formation of amyloid-like proteins. As these structures entrapped bacteria and fungi, they might reflect an additional function of HNPs in host defense. The described mechanism links again thrombosis and infection.
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Affiliation(s)
- M Horn
- Department of Anaesthesiology and Intensive Care, Experimental and Clinical Haemostasis, University of Muenster, Muenster, Germany
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29
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Chao JT, Davis MJ. The roles of integrins in mediating the effects of mechanical force and growth factors on blood vessels in hypertension. Curr Hypertens Rep 2012; 13:421-9. [PMID: 21879361 DOI: 10.1007/s11906-011-0227-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Hypertension is characterized by a sustained increase in vasoconstriction and attenuated vasodilation in the face of elevated mechanical stress in the blood vessel wall. To adapt to the increased stress, the vascular smooth muscle cell and its surrounding environment undergo structural and functional changes known as vascular remodeling. Multiple mechanisms underlie the remodeling process, including increased expression of humoral factors and their receptors as well as adhesion molecules and their receptors, all of which appear to collaborate and interact in the response to pressure elevation. In this review, we focus on the interactions between integrin signaling pathways and the activation of growth factor receptors in the response to the increased mechanical stress experienced by blood vessels in hypertension.
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Affiliation(s)
- Jun-Tzu Chao
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, 1 Hospital Drive, Columbia, MO 65212, USA
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30
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Etulain J, Negrotto S, Carestia A, Pozner RG, Romaniuk MA, D'Atri LP, Klement GL, Schattner M. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets. Thromb Haemost 2011; 107:99-110. [PMID: 22159527 DOI: 10.1160/th11-06-0443] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 10/19/2011] [Indexed: 01/06/2023]
Abstract
Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.
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Affiliation(s)
- Julia Etulain
- Thrombosis I Laboratory, National Academy of Medicine, CONICET, Buenos Aires, Argentina
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31
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Wang W, Jiang Y, Wang C, Luo BH. Effects of the Association between the α-Subunit Thigh and the β-Subunit EGF2 Domains on Integrin Activation and Signaling. Biochemistry 2011; 50:9264-72. [DOI: 10.1021/bi200744g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Wei Wang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Yan Jiang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Chen Wang
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
| | - Bing-Hao Luo
- Department of Biological Sciences,
202 Life Sciences
Building, Louisiana State University, Baton
Rouge, Louisiana 70803, United States
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32
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Tyrosine phosphorylated c-Cbl regulates platelet functional responses mediated by outside-in signaling. Blood 2011; 118:5631-40. [PMID: 21967979 DOI: 10.1182/blood-2011-01-328807] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
c-Cbl protein functions as an E3 ligase and scaffolding protein, where 3 residues, Y700, Y731, and Y774, upon phosphorylation, have been shown to initiate several signaling cascades. In this study, we investigated the role of these phospho-tyrosine residues in the platelet functional responses after integrin engagement. We observed that c-Cbl Y700, Y731 and Y774 undergo phosphorylation upon platelet adhesion to immobilized fibrinogen, which was inhibited in the presence of PP2, a pan-src family kinase (SFK) inhibitor, suggesting that c-Cbl is phosphorylated downstream of SFKs. However, OXSI-2, a Syk inhibitor, significantly reduced c-Cbl phosphorylation at residues Y774 and Y700, without affecting Y731 phosphorylation. Interestingly, PP2 inhibited both platelet-spreading on fibrinogen as well as clot retraction, whereas OXSI-2 blocked only platelet-spreading, suggesting a differential role of these tyrosine residues. The physiologic role of c-Cbl and Y731 was studied using platelets from c-Cbl KO and c-Cbl(YF/YF) knock-in mice. c-Cbl KO and c-Cbl(YF/YF) platelets had a significantly reduced spreading over immobilized fibrinogen. Furthermore, clot retraction with c-Cbl KO and c-Cbl(YF/YF) platelets was drastically delayed. These results indicate that c-Cbl and particularly its phosphorylated residue Y731 plays an important role in platelet outside-in signaling contributing to platelet-spreading and clot retraction.
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33
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Scales TME, Parsons M. Spatial and temporal regulation of integrin signalling during cell migration. Curr Opin Cell Biol 2011; 23:562-8. [DOI: 10.1016/j.ceb.2011.05.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 05/29/2011] [Accepted: 05/30/2011] [Indexed: 11/26/2022]
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34
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Levaot N, Simoncic PD, Dimitriou ID, Scotter A, La Rose J, Ng AHM, Willett TL, Wang CJ, Janmohamed S, Grynpas M, Reichenberger E, Rottapel R. 3BP2-deficient mice are osteoporotic with impaired osteoblast and osteoclast functions. J Clin Invest 2011; 121:3244-57. [PMID: 21765218 DOI: 10.1172/jci45843] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 06/01/2011] [Indexed: 12/29/2022] Open
Abstract
A fine balance between bone resorption by osteoclasts and bone formation by osteoblasts maintains bone homeostasis. In patients with cherubism, gain-of-function mutations in 3BP2, which is encoded by SH3-domain binding protein 2 (SH3BP2), cause cystic lesions with activated osteoclasts that lead to craniofacial abnormalities. However, little is known about the function of wild-type 3BP2 in regulating bone homeostasis. Here we have shown that 3BP2 is required for the normal function of both osteoblasts and osteoclasts. Initial analysis showed that Sh3bp2-/-mice developed osteoporosis as a result of reduced bone formation despite the fact that bone resorption was impaired. We demonstrated using reciprocal bone marrow chimeras, a cell-intrinsic defect of the osteoblast and osteoclast compartments in vivo. Further, Sh3bp2-/- osteoblasts failed to mature and form mineralized nodules in vitro, while Sh3bp2-/- osteoclasts spread poorly and were unable to effectively degrade dentine matrix in vitro. Finally, we showed that 3BP2 was required for Abl activation in osteoblasts and Src activation in osteoclasts, and demonstrated that the in vitro defect of each cell type was restored by the respective expression of activated forms of these kinases. These findings reveal an unanticipated role for the 3BP2 adapter protein in osteoblast function and in coordinating bone homeostatic signals in both osteoclast and osteoblast lineages.
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Affiliation(s)
- Noam Levaot
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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Abstract
Liver X receptors (LXRs) are transcription factors involved in the regulation of cholesterol homeostasis. LXR ligands have athero-protective properties independent of their effects on cholesterol metabolism. Platelets are involved in the initiation of atherosclerosis and despite being anucleate express nuclear receptors. We hypothesized that the athero-protective effects of LXR ligands could be in part mediated through platelets and therefore explored the potential role of LXR in platelets. Our results show that LXR-β is present in human platelets and the LXR ligands, GW3965 and T0901317, modulated nongenomically platelet aggregation stimulated by a range of agonists. GW3965 caused LXR to associate with signaling components proximal to the collagen receptor, GPVI, suggesting a potential mechanism of LXR action in platelets that leads to diminished platelet responses. Activation of platelets at sites of atherosclerotic lesions results in thrombosis preceding myocardial infarction and stroke. Using an in vivo model of thrombosis in mice, we show that GW3965 has antithrombotic effects, reducing the size and the stability of thrombi. The athero-protective effects of GW3965, together with its novel antiplatelet/thrombotic effects, indicate LXR as a potential target for prevention of athero-thrombotic disease.
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36
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March ME, Long EO. β2 integrin induces TCRζ-Syk-phospholipase C-γ phosphorylation and paxillin-dependent granule polarization in human NK cells. THE JOURNAL OF IMMUNOLOGY 2011; 186:2998-3005. [PMID: 21270398 DOI: 10.4049/jimmunol.1002438] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cytotoxic lymphocytes kill target cells through polarized release of the content of lytic granules at the immunological synapse. In human NK cells, signals for granule polarization and for degranulation can be uncoupled: Binding of β(2) integrin LFA-1 to ICAM is sufficient to induce polarization but not degranulation, whereas CD16 binding to IgG triggers unpolarized degranulation. In this study, we investigated the basis for this difference. IL-2-expanded human NK cells were stimulated by incubation with plate-bound ligands of LFA-1 (ICAM-1) and CD16 (human IgG). Surprisingly, LFA-1 elicited signals similar to those induced by CD16, including tyrosine phosphorylation of the TCR ζ-chain, tyrosine kinase Syk, and phospholipase C-γ. Whereas CD16 activated Ca(2+) mobilization and LAT phosphorylation, LFA-1 did not, but induced strong Pyk2 and paxillin phosphorylation. LFA-1-dependent granule polarization was blocked by inhibition of Syk, phospholipase C-γ, and protein kinase C, as well as by paxillin knockdown. Therefore, common signals triggered by CD16 and LFA-1 bifurcate to provide independent control of Ca(2+)-dependent degranulation and paxillin-dependent granule polarization.
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Affiliation(s)
- Michael E March
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852
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37
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The integrin LFA-1 signals through ZAP-70 to regulate expression of high-affinity LFA-1 on T lymphocytes. Blood 2011; 117:3331-42. [PMID: 21200022 DOI: 10.1182/blood-2010-06-289140] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The integrin lymphocyte function-associated antigen 1 (LFA-1) controls many functions of T lymphocytes and is particularly essential during lymphocyte migration from blood into tissues. LFA-1 is considered to initiate "outside-in" signaling when bound to ligand intercellular adhesion molecule 1 (ICAM-1), but little is known about the proteins involved or where in the cell such LFA-1-mediated signaling might be operating. Here we show that LFA-1 is constitutively associated with the protein tyrosine kinases Lck and zeta chain-associated protein of 70 kDa (ZAP-70). When LFA-1 binds ICAM-1, both kinases become phosphorylated and the consequence of kinase activation is the conversion of intermediate- to high-affinity LFA-1 and an increase in close contact with ICAM-1. In the polarized T lymphocyte, phospho-ZAP-70 is concentrated within a region of high-affinity LFA-1 that includes talin and encompasses the lamella/lamellipodial interface as well as further back in the cell. Deficiency of ZAP-70 through inhibition or knockdown in T lymphocytes decreases the speed of migration on ICAM-1, as well as reducing firm adhesion under shear-flow conditions. Through its control of high-affinity LFA-1, the LFA-1/Lck/ZAP-70 complex is in position to initiate the rapid adhesion strengthening and migration necessary for T-lymphocyte responses when stimulated vasculature is encountered at sites of infection or injury.
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38
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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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39
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Mócsai A, Ruland J, Tybulewicz VLJ. The SYK tyrosine kinase: a crucial player in diverse biological functions. Nat Rev Immunol 2010; 10:387-402. [PMID: 20467426 PMCID: PMC4782221 DOI: 10.1038/nri2765] [Citation(s) in RCA: 925] [Impact Index Per Article: 66.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Spleen tyrosine kinase (SYK) is known to have a crucial role in adaptive immune receptor signalling. However, recent reports indicate that SYK also mediates other, unexpectedly diverse biological functions, including cellular adhesion, innate immune recognition, osteoclast maturation, platelet activation and vascular development. SYK is activated by C-type lectins and integrins, and activates new targets, including the CARD9-BCL-10-MALT1 pathway and the NLRP3 inflammasome. Studies using Drosophila melanogaster suggest that there is an evolutionarily ancient origin of SYK-mediated signalling. Moreover, SYK has a crucial role in autoimmune diseases and haematological malignancies. This Review summarizes our current understanding of the diverse functions of SYK and how this is being translated for therapeutic purposes.
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Affiliation(s)
- Attila Mócsai
- Department of Physiology, Semmelweis University School of Medicine, 1094 Budapest, Hungary.
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40
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Jordan MS, Koretzky GA. Coordination of receptor signaling in multiple hematopoietic cell lineages by the adaptor protein SLP-76. Cold Spring Harb Perspect Biol 2010; 2:a002501. [PMID: 20452948 DOI: 10.1101/cshperspect.a002501] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The adaptor protein SLP-76 is expressed in multiple hematopoietic lineages including T cells, platelets, and neutrophils. SLP-76 mediated signaling is dependent on its multiple protein interaction domains, as it creates a scaffold on which key signaling complexes are built. SLP-76 is critical for supporting signaling downstream of both immunoreceptors and integrins. The signaling molecules used both upstream and downstream of SLP-76 are similar among these receptors and across cell types; however, important differences exist. Appreciating how SLP-76 coordinates signal transduction across different cell and receptor types provides insights into the complex interplay of pathways critical for activation of cells of the immune system that are essential for host defense.
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Affiliation(s)
- Martha S Jordan
- Abramson Family Cancer Institute, University of Pennsylvania, Philadelphia, 19104, USA
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41
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Jones ML, Harper MT, Aitken EW, Williams CM, Poole AW. RGD-ligand mimetic antagonists of integrin alphaIIbbeta3 paradoxically enhance GPVI-induced human platelet activation. J Thromb Haemost 2010; 8:567-76. [PMID: 20002543 DOI: 10.1111/j.1538-7836.2009.03719.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The integrin alpha(IIb)beta(3) is the major mediator of platelet aggregation and has, therefore, become an important target of antithrombotic therapy. Antagonists of alpha(IIb)beta(3), for example abciximab, tirofiban and eptifibatide, are used in the treatment of acute coronary syndromes. However, in addition to effective blockade of the integrin, binding of can induce conformational changes in the integrin and can also induce integrin clustering. This class effect of RGD-ligand mimetics might, therefore, underlie paradoxical platelet activation and thrombosis previously reported. OBJECTIVES To examine the components of signaling pathways and functional responses in platelets that may underlie this phenomenon of paradoxical platelet activation. METHODS We assessed the effect of lotrafiban, and other alpha(IIb)beta(3) antagonists including the clinically used drug tirofiban, on tyrosine phosphorylation of key signaling proteins in platelets by immunoblotting and also platelet functional outputs such as cytosolic calcium responses, phosphatidylserine exposure (pro-coagulant activity) and dense granule release. RESULTS In all cases, no effect of alpha(IIb)beta(3) antagonists were observed on their own, but these integrin antagonists did lead to a marked potentiation of glycoprotein VI (GPVI)-associated FcR gamma-chain phosphorylation, activation of Src family kinases and Syk kinase. This correlated with increased dense granule secretion, cytosolic calcium response and exposure of phosphatidylserine on the platelet surface. P2Y(12) antagonism abolished the potentiated phosphatidylserine exposure and dense granule secretion but not the cytosolic calcium response. CONCLUSIONS These data provide a mechanism for enhancement of platelet activity by alpha(IIb)beta(3) inhibitors, but also reveal a potentially important signaling pathway operating from the integrin to GPVI signaling.
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Affiliation(s)
- M L Jones
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol, UK
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Cardoso MH, Morganti RP, Lilla S, Murad F, De Nucci G, Antunes E, Marcondes S. The role of superoxide anion in the inhibitory effect of SIN-1 in thrombin-activated human platelet adhesion. Eur J Pharmacol 2010; 627:229-34. [DOI: 10.1016/j.ejphar.2009.10.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 10/27/2009] [Indexed: 01/22/2023]
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Platelet integrin signaling: wherefore art thou? Blood 2009; 114:2571-2. [DOI: 10.1182/blood-2009-08-235283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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The adapter protein SLP-76 mediates "outside-in" integrin signaling and function in T cells. Mol Cell Biol 2009; 29:5578-89. [PMID: 19667077 DOI: 10.1128/mcb.00283-09] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adapter protein SH2 domain-containing leukocyte protein of 76 kDa (SLP-76) is an essential mediator of signaling from the T-cell antigen receptor (TCR). We report here that SLP-76 also mediates signaling downstream of integrins in T cells and that SLP-76-deficient T cells fail to support adhesion to integrin ligands. In response to both TCR and integrin stimulation, SLP-76 relocalizes to surface microclusters that colocalize with phosphorylated signaling proteins. Disruption of SLP-76 recruitment to the protein named LAT (linker for activation of T cells) inhibits SLP-76 clustering downstream of the TCR but not downstream of integrins. Conversely, an SLP-76 mutant unable to bind ADAP (adhesion and degranulation-promoting adapter protein) forms clusters following TCR but not integrin engagement and fails to support T-cell adhesion to integrin ligands. These findings demonstrate that SLP-76 relocalizes to integrin-initiated signaling complexes by a mechanism different from that employed during TCR signaling and that SLP-76 relocalization corresponds to SLP-76-dependent integrin function in T cells.
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Alghisi GC, Rüegg C. Vascular Integrins in Tumor Angiogenesis: Mediators and Therapeutic Targets. ACTA ACUST UNITED AC 2009; 13:113-35. [PMID: 16728329 DOI: 10.1080/10623320600698037] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The notion that tumor angiogenesis may have therapeutic implications in the control of tumor growth was introduced by Dr. Judah Folkman in 1971. The approval of Avastin in 2004 as the first antiangiogenic systemic drug to treat cancer patients came as a validation of this visionary concept and opened new perspectives to the treatment of cancer. In addition, this success boosted the field to the quest for new therapeutic targets and antiangiogenic drugs. Preclinical and clinical evidence indicate that vascular integrins may be valid therapeutic targets. In preclinical studies, pharmacological inhibition of integrin function efficiently suppressed angiogenesis and inhibited tumor progression. alphaVbeta3 and alphaVbeta5 were the first vascular integrins targeted to suppress tumor angiogenesis. Subsequent experiments revealed that at least four additional integrins (i.e., alpha1beta1, alpha2beta1, alpha5beta1, and alpha6beta4) might be potential therapeutic targets. In clinical studies low-molecular-weight integrin inhibitors and anti-integrin function-blocking antibodies demonstrated low toxicity and good tolerability and are now being tested in combination with radiotherapy and chemotherapy for anticancer activity in patients. In this article the authors review the role of integrins in angiogenesis, present recent development in the use of alphaVbeta3 and alpha5beta1 integrin antagonists as potential therapeutics in cancer, and discuss future perspectives.
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Affiliation(s)
- Gian Carlo Alghisi
- Centre Pluridisciplinaire d'Oncologie (CePO), Faculty of Biology and Medicine, University of Lausanne, Switzerland
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Reilly D, Larkin D, Devocelle M, Fitzgerald DJ, Moran N. Calreticulin-independent regulation of the platelet integrin αIIbβ3by the KVGFFKR αIIb-cytoplasmic motif. Platelets 2009; 15:43-54. [PMID: 14985176 DOI: 10.1080/09537100310001640055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The platelet integrin alphaIIbbeta3 alters conformation in response to platelet activation and ligand binding, although the molecular mechanisms involved are not known. We previously showed that a lipid modified peptide, corresponding to the membrane proximal 989KVGFFKR995 portion of the alphaIIb cytoplasmic tail, independently activates platelet alphaIIbbeta3. Calreticulin (CRT) is a potential integrin regulatory protein based on its interaction with the highly conserved alpha-integrin sequence KxGFFKR. We therefore examined the possible interaction of calreticulin and alphaIIbbeta3 in human platelets. We demonstrate that calreticulin in platelets is localised to the granulomere. In contrast, the known integrin-binding protein talin accumulates at the periphery of spreading platelets and colocalises with alphaIIbbeta3 during the process of adhesion. An interaction between calreticulin and alphaIIbbeta3 could not be demonstrated using co-immunoprecipitation techniques under various platelet activation states, even in the presence of covalent chemical crosslinkers. Thus, calreticulin does not functionally interact with the major integrin in human platelets. In order to identify proteins that interact with the integrin KVGFFKR motif we then used a peptide 'pull-down' assay from platelet lysates with biotinylated peptides and demonstrate that only the alphaIIb and beta3 subunits selectively and individually interact with this sequence. This interaction is divalent cation-dependent, has high-affinity, and occurs both with purified alphaIIbbeta3 complex and with electroeluted alpha and beta subunits. Thus, our data show that the conserved integrin KVGFFKR domain interacts primarily with the alpha and beta cytoplasmic tails and not with CRT in human platelets.
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Affiliation(s)
- Dermot Reilly
- Centre for Sythesis and Chemical Biology, Department of Chemistry, Royal College of Surgeons in Ireland, Dublin
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Huveneers S, Danen EHJ. Adhesion signaling - crosstalk between integrins, Src and Rho. J Cell Sci 2009; 122:1059-69. [PMID: 19339545 DOI: 10.1242/jcs.039446] [Citation(s) in RCA: 635] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Interactions between cells and the extracellular matrix coordinate signaling pathways that control various aspects of cellular behavior. Integrins sense the physical properties of the extracellular matrix and organize the cytoskeleton accordingly. In turn, this modulates signaling pathways that are triggered by various other transmembrane receptors and augments the cellular response to growth factors. Over the past years, it has become clear that there is extensive crosstalk between integrins, Src-family kinases and Rho-family GTPases at the heart of such adhesion signaling. In this Commentary, we discuss recent advances in our understanding of the dynamic regulation of the molecular connections between these three protein families. We also discuss how this signaling network can regulate a range of cellular processes that are important for normal tissue function and disease, including cell adhesion, spreading, migration and mechanotransduction.
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Affiliation(s)
- Stephan Huveneers
- Division of Toxicology, Leiden Amsterdam Center for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands.
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Kato A, Oshimi K. Ancient ubiquitous protein 1 and Syk link cytoplasmic tails of the integrin alpha(IIb)beta(3). Platelets 2009; 20:105-10. [PMID: 19235052 DOI: 10.1080/09537100802641507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
It is currently accepted that activity of the integrin alpha(IIb)beta(3) is modulated by direct interaction between its cytoplasmic tails (CTs) and association of cytoplasmic proteins with them, and disruption of the close linkage between CTs leads to activation of alpha(IIb)beta(3) (inside-out signaling). We previously reported that ancient ubiquitous protein (Aup1) binds to the membrane-proximal sequence of integrin alphaCTs that plays a pivotal role in the inside-out signaling. To explore biological function of Aup1, we examined in this study interaction of Aup1 with Src and Syk that are quickly activated in platelets before fibrinogen binding following thrombin stimulation. By immunoprecipitation assay with resting platelets, we first found that alpha(IIb)beta(3), Src, Syk, and Aup1 are constitutively complexed. In vitro binding study with recombinant Syk and glutathione (GSH) S-transferase (GST) - Src, -Aup1, and -alpha(IIb) and - beta(3) CTs that are immobilized to GSH- beads revealed direct binding of Syk to Aup1 as well as the beta(3) CT. Dot blot analysis with synthetic peptides for alpha(IIb) and beta(3) CTs, and GST-Aup1 and -Src immobilized to PVDF membrane exhibited concordant result with the GST pull-down assay. Immunoprecipitation of platelet lysates 10 seconds after thrombin stimulation, when activity and tyrosine phosphorylation of Syk are maimum, exhibited that active Syk does not coprecipitate with Aup1. In vitro kinase assay with GST-Syk and -Aup1 proteins at the presence or absence of active Src, a potent activator of Syk, revealed that Aup1 does not directly influence activation of Syk by autophosphorylation or tyrosine phosphorylation by Src. These results indicate that Aup1 is an adaptor recruiting Syk to the alpha(IIb) CT, and suggest that the alpha(IIb) -Aup1- Syk- beta(3) complex formation links alpha(IIb) and beta(3) CTs to sustain alpha(IIb)beta(3) in an inactive state and Syk dissociates from Aup1 after activation.
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Affiliation(s)
- Atsushi Kato
- Division of Hematology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
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Abstract
Integrins are cell surface heterodimers that bind adhesion molecules expressed on other cells or in the extracellular matrix. Integrin-mediated interactions are critical for T cell development in the thymus, migration of T cells in the periphery, and induction of T cell effector functions. In resting T cells, integrins are maintained in a low affinity state. Engagement of the T cell receptor or chemokine receptors increases integrin affinity, enabling integrins to bind their ligands and initiate a signaling cascade resulting in altered cell morphology and motility. Our laboratory is interested how adapter proteins, mediators of intracellular signal transduction, regulate both signals from the T cell receptor to integrins (inside-out signaling) and (outside-in) signals from integrins into the cell.
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50
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Endothelium–platelet interactions in inflammatory lung disease. Vascul Pharmacol 2008; 49:141-50. [DOI: 10.1016/j.vph.2008.06.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 04/21/2008] [Accepted: 06/13/2008] [Indexed: 01/15/2023]
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