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O'Donoghue L, Smolenski A. Roles of G proteins and their GTPase-activating proteins in platelets. Biosci Rep 2024; 44:BSR20231420. [PMID: 38808367 PMCID: PMC11139668 DOI: 10.1042/bsr20231420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 04/30/2024] [Accepted: 05/02/2024] [Indexed: 05/30/2024] Open
Abstract
Platelets are small anucleate blood cells supporting vascular function. They circulate in a quiescent state monitoring the vasculature for injuries. Platelets adhere to injury sites and can be rapidly activated to secrete granules and to form platelet/platelet aggregates. These responses are controlled by signalling networks that include G proteins and their regulatory guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Recent proteomics studies have revealed the complete spectrum of G proteins, GEFs, and GAPs present in platelets. Some of these proteins are specific for platelets and very few have been characterised in detail. GEFs and GAPs play a major role in setting local levels of active GTP-bound G proteins in response to activating and inhibitory signals encountered by platelets. Thus, GEFs and GAPs are highly regulated themselves and appear to integrate G protein regulation with other cellular processes. This review focuses on GAPs of small G proteins of the Arf, Rab, Ras, and Rho families, as well as of heterotrimeric G proteins found in platelets.
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Affiliation(s)
- Lorna O'Donoghue
- UCD School of Medicine, University College Dublin, UCD Conway Institute, Belfield, Dublin 4, Ireland
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, 123 St. Stephen’s Green 123, Dublin 2, Ireland
| | - Albert Smolenski
- UCD School of Medicine, University College Dublin, UCD Conway Institute, Belfield, Dublin 4, Ireland
- Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, 123 St. Stephen’s Green 123, Dublin 2, Ireland
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2
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Dandamudi A, Akbar H, Cancelas J, Zheng Y. Rho GTPase Signaling in Platelet Regulation and Implication for Antiplatelet Therapies. Int J Mol Sci 2023; 24:ijms24032519. [PMID: 36768837 PMCID: PMC9917354 DOI: 10.3390/ijms24032519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/16/2023] [Accepted: 01/21/2023] [Indexed: 01/31/2023] Open
Abstract
Platelets play a vital role in regulating hemostasis and thrombosis. Rho GTPases are well known as molecular switches that control various cellular functions via a balanced GTP-binding/GTP-hydrolysis cycle and signaling cascade through downstream effectors. In platelets, Rho GTPases function as critical regulators by mediating signal transduction that drives platelet activation and aggregation. Mostly by gene targeting and pharmacological inhibition approaches, Rho GTPase family members RhoA, Rac1, and Cdc42 have been shown to be indispensable in regulating the actin cytoskeleton dynamics in platelets, affecting platelet shape change, spreading, secretion, and aggregation, leading to thrombus formation. Additionally, studies of Rho GTPase function using platelets as a non-transformed model due to their anucleated nature have revealed valuable information on cell signaling principles. This review provides an updated summary of recent advances in Rho GTPase signaling in platelet regulation. We also highlight pharmacological approaches that effectively inhibited platelet activation to explore their possible development into future antiplatelet therapies.
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Affiliation(s)
- Akhila Dandamudi
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
- Department of Pathology, University of Cincinnati Graduate School, Cincinnati, OH 45267, USA
| | - Huzoor Akbar
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA
| | - Jose Cancelas
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
- Hoxworth Blood Center, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
- Department of Pathology, University of Cincinnati Graduate School, Cincinnati, OH 45267, USA
- Correspondence: ; Tel.: +1-513-636-0595
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3
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Modulation of Glycoprotein VI and Its Downstream Signaling Pathways as an Antiplatelet Target. Int J Mol Sci 2022; 23:ijms23179882. [PMID: 36077280 PMCID: PMC9456422 DOI: 10.3390/ijms23179882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 07/06/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
Antiplatelet therapy aims to reduce the risk of thrombotic events while maintaining hemostasis. A promising current approach is the inhibition of platelet glycoprotein GPVI-mediated adhesion pathways; pathways that do not involve coagulation. GPVI is a signaling receptor integral for collagen-induced platelet activation and participates in the thrombus consolidation process, being a suitable target for thrombosis prevention. Considering this, the blocking or antibody-mediated depletion of GPVI is a promising antiplatelet therapy for the effective and safe treatment of thrombotic diseases without a significant risk of bleeding and impaired hemostatic plug formation. This review describes the current knowledge concerning pharmaceutical approaches to platelet GPVI modulation and its downstream signaling pathways in this context.
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4
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Comer SP. Turning Platelets Off and On: Role of RhoGAPs and RhoGEFs in Platelet Activity. Front Cardiovasc Med 2022; 8:820945. [PMID: 35071371 PMCID: PMC8770426 DOI: 10.3389/fcvm.2021.820945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/15/2021] [Indexed: 12/15/2022] Open
Abstract
Platelet cytoskeletal reorganisation is a critical component of platelet activation and thrombus formation in haemostasis. The Rho GTPases RhoA, Rac1 and Cdc42 are the primary drivers in the dynamic reorganisation process, leading to the development of filopodia and lamellipodia which dramatically increase platelet surface area upon activation. Rho GTPases cycle between their active (GTP-bound) and inactive (GDP-bound) states through tightly regulated processes, central to which are the guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). GEFs catalyse the dissociation of GDP by inducing changes in the nucleotide binding site, facilitating GTP binding and activating Rho GTPases. By contrast, while all GTPases possess intrinsic hydrolysing activity, this reaction is extremely slow. Therefore, GAPs catalyse the hydrolysis of GTP to GDP, reverting Rho GTPases to their inactive state. Our current knowledge of these proteins is constantly being updated but there is considerably less known about the functionality of Rho GTPase specific GAPs and GEFs in platelets. In the present review, we discuss GAP and GEF proteins for Rho GTPases identified in platelets, their regulation, biological function and present a case for their further study in platelets.
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Affiliation(s)
- Shane P Comer
- ConwaySPHERE Research Group, UCD Conway Institute, University College Dublin, Dublin, Ireland.,School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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5
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Loss of the exocyst complex component EXOC3 promotes hemostasis and accelerates arterial thrombosis. Blood Adv 2021; 5:674-686. [PMID: 33560379 DOI: 10.1182/bloodadvances.2020002515] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 12/28/2020] [Indexed: 11/20/2022] Open
Abstract
The exocyst is an octameric complex comprising 8 distinct protein subunits, exocyst complex components (EXOC) 1 to 8. It has an established role in tethering secretory vesicles to the plasma membrane, but its relevance to platelet granule secretion and function remains to be determined. Here, EXOC3 conditional knockout (KO) mice in the megakaryocyte/platelet lineage were generated to assess exocyst function in platelets. Significant defects in platelet aggregation, integrin activation, α-granule (P-selectin and platelet factor 4), dense granule, and lysosomal granule secretion were detected in EXOC3 KO platelets after treatment with a glycoprotein VI (GPVI)-selective agonist, collagen-related peptide (CRP). Except for P-selectin exposure, these defects were completely recovered by maximal CRP concentrations. GPVI surface levels were also significantly decreased by 14.5% in KO platelets, whereas defects in proximal GPVI signaling responses, Syk and LAT phosphorylation, and calcium mobilization were also detected, implying an indirect mechanism for these recoverable defects due to decreased surface GPVI. Paradoxically, dense granule secretion, integrin activation, and changes in surface expression of integrin αIIb (CD41) were significantly increased in KO platelets after protease-activated receptor 4 activation, but calcium responses were unaltered. Elevated integrin activation responses were completely suppressed with a P2Y12 receptor antagonist, suggesting enhanced dense granule secretion of adenosine 5'-diphosphate as a critical mediator of these responses. Finally, arterial thrombosis was significantly accelerated in KO mice, which also displayed improved hemostasis determined by reduced tail bleeding times. These findings reveal a regulatory role for the exocyst in controlling critical aspects of platelet function pertinent to thrombosis and hemostasis.
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6
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Heib T, Hermanns HM, Manukjan G, Englert M, Kusch C, Becker IC, Gerber A, Wackerbarth LM, Burkard P, Dandekar T, Balkenhol J, Jahn D, Beck S, Meub M, Dütting S, Stigloher C, Sauer M, Cherpokova D, Schulze H, Brakebusch C, Nieswandt B, Nagy Z, Pleines I. RhoA/Cdc42 signaling drives cytoplasmic maturation but not endomitosis in megakaryocytes. Cell Rep 2021; 35:109102. [PMID: 33979620 DOI: 10.1016/j.celrep.2021.109102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 02/20/2021] [Accepted: 04/18/2021] [Indexed: 12/15/2022] Open
Abstract
Megakaryocytes (MKs), the precursors of blood platelets, are large, polyploid cells residing mainly in the bone marrow. We have previously shown that balanced signaling of the Rho GTPases RhoA and Cdc42 is critical for correct MK localization at bone marrow sinusoids in vivo. Using conditional RhoA/Cdc42 double-knockout (DKO) mice, we reveal here that RhoA/Cdc42 signaling is dispensable for the process of polyploidization in MKs but essential for cytoplasmic MK maturation. Proplatelet formation is virtually abrogated in the absence of RhoA/Cdc42 and leads to severe macrothrombocytopenia in DKO animals. The MK maturation defect is associated with downregulation of myosin light chain 2 (MLC2) and β1-tubulin, as well as an upregulation of LIM kinase 1 and cofilin-1 at both the mRNA and protein level and can be linked to impaired MKL1/SRF signaling. Our findings demonstrate that MK endomitosis and cytoplasmic maturation are separately regulated processes, and the latter is critically controlled by RhoA/Cdc42.
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Affiliation(s)
- Tobias Heib
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Heike M Hermanns
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Georgi Manukjan
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Maximilian Englert
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Charly Kusch
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Isabelle Carlotta Becker
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Annika Gerber
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Lou Martha Wackerbarth
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Philipp Burkard
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Thomas Dandekar
- Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Johannes Balkenhol
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Daniel Jahn
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Sarah Beck
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Mara Meub
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sebastian Dütting
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Deya Cherpokova
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Cord Brakebusch
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany.
| | - Zoltan Nagy
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Irina Pleines
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany.
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7
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RhoG deficiency abrogates cytotoxicity of human lymphocytes and causes hemophagocytic lymphohistiocytosis. Blood 2021; 137:2033-2045. [PMID: 33513601 DOI: 10.1182/blood.2020008738] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 01/11/2021] [Indexed: 11/20/2022] Open
Abstract
Exocytosis of cytotoxic granules (CG) by lymphocytes is required for the elimination of infected and malignant cells. Impairments in this process underly a group of diseases with dramatic hyperferritinemic inflammation termed hemophagocytic lymphohistiocytosis (HLH). Although genetic and functional studies of HLH have identified proteins controlling distinct steps of CG exocytosis, the molecular mechanisms that spatiotemporally coordinate CG release remain partially elusive. We studied a patient exhibiting characteristic clinical features of HLH associated with markedly impaired cytotoxic T lymphocyte (CTL) and natural killer (NK) cell exocytosis functions, who beared biallelic deleterious mutations in the gene encoding the small GTPase RhoG. Experimental ablation of RHOG in a model cell line and primary CTLs from healthy individuals uncovered a hitherto unappreciated role of RhoG in retaining CGs in the vicinity of the plasma membrane (PM), a fundamental prerequisite for CG exocytotic release. We discovered that RhoG engages in a protein-protein interaction with Munc13-4, an exocytosis protein essential for CG fusion with the PM. We show that this interaction is critical for docking of Munc13-4+ CGs to the PM and subsequent membrane fusion and release of CG content. Thus, our study illuminates RhoG as a novel essential regulator of human lymphocyte cytotoxicity and provides the molecular pathomechanism behind the identified here and previously unreported genetically determined form of HLH.
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8
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Vainchenker W, Arkoun B, Basso-Valentina F, Lordier L, Debili N, Raslova H. Role of Rho-GTPases in megakaryopoiesis. Small GTPases 2021; 12:399-415. [PMID: 33570449 PMCID: PMC8583283 DOI: 10.1080/21541248.2021.1885134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Megakaryocytes (MKs) are the bone marrow (BM) cells that generate blood platelets by a process that requires: i) polyploidization responsible for the increased MK size and ii) cytoplasmic organization leading to extension of long pseudopods, called proplatelets, through the endothelial barrier to allow platelet release into blood. Low level of localized RHOA activation prevents actomyosin accumulation at the cleavage furrow and participates in MK polyploidization. In the platelet production, RHOA and CDC42 play opposite, but complementary roles. RHOA inhibits both proplatelet formation and MK exit from BM, whereas CDC42 drives the development of the demarcation membranes and MK migration in BM. Moreover, the RhoA or Cdc42 MK specific knock-out in mice and the genetic alterations in their down-stream effectors in human induce a thrombocytopenia demonstrating their key roles in platelet production. A better knowledge of Rho-GTPase signalling is thus necessary to develop therapies for diseases associated with platelet production defects. Abbreviations: AKT: Protein Kinase BARHGEF2: Rho/Rac Guanine Nucleotide Exchange Factor 2ARP2/3: Actin related protein 2/3BM: Bone marrowCDC42: Cell division control protein 42 homologCFU-MK: Colony-forming-unit megakaryocyteCIP4: Cdc42-interacting protein 4mDIA: DiaphanousDIAPH1; Protein diaphanous homolog 1ECT2: Epithelial Cell Transforming Sequence 2FLNA: Filamin AGAP: GTPase-activating proteins or GTPase-accelerating proteinsGDI: GDP Dissociation InhibitorGEF: Guanine nucleotide exchange factorHDAC: Histone deacetylaseLIMK: LIM KinaseMAL: Megakaryoblastic leukaemiaMARCKS: Myristoylated alanine-rich C-kinase substrateMKL: Megakaryoblastic leukaemiaMLC: Myosin light chainMRTF: Myocardin Related Transcription FactorOTT: One-Twenty Two ProteinPACSIN2: Protein Kinase C And Casein Kinase Substrate In Neurons 2PAK: P21-Activated KinasePDK: Pyruvate Dehydrogenase kinasePI3K: Phosphoinositide 3-kinasePKC: Protein kinase CPTPRJ: Protein tyrosine phosphatase receptor type JRAC: Ras-related C3 botulinum toxin substrate 1RBM15: RNA Binding Motif Protein 15RHO: Ras homologousROCK: Rho-associated protein kinaseSCAR: Suppressor of cAMP receptorSRF: Serum response factorSRC: SarcTAZ: Transcriptional coactivator with PDZ motifTUBB1: Tubulin β1VEGF: Vascular endothelial growth factorWAS: Wiskott Aldrich syndromeWASP: Wiskott Aldrich syndrome proteinWAVE: WASP-family verprolin-homologous proteinWIP: WASP-interacting proteinYAP: Yes-associated protein
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Affiliation(s)
- William Vainchenker
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,GrEX, Sorbonne Paris Cité, Paris, France
| | - Brahim Arkoun
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,GrEX, Sorbonne Paris Cité, Paris, France
| | - Francesca Basso-Valentina
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,Université Sorbonne Paris Cité/Université Paris Dideront, Paris, France
| | - Larissa Lordier
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
| | - Najet Debili
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
| | - Hana Raslova
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
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9
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Bacterial dormancy: A subpopulation of viable but non-culturable cells demonstrates better fitness for revival. PLoS Pathog 2021; 17:e1009194. [PMID: 33439894 PMCID: PMC7837498 DOI: 10.1371/journal.ppat.1009194] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/26/2021] [Accepted: 11/27/2020] [Indexed: 01/08/2023] Open
Abstract
The viable but non culturable (VBNC) state is a condition in which bacterial cells are viable and metabolically active, but resistant to cultivation using a routine growth medium. We investigated the ability of V. parahaemolyticus to form VBNC cells, and to subsequently become resuscitated. The ability to control VBNC cell formation in the laboratory allowed us to selectively isolate VBNC cells using fluorescence activated cell sorting, and to differentiate subpopulations based on their metabolic activity, cell shape and the ability to cause disease in Galleria mellonella. Our results showed that two subpopulations (P1 and P2) of V. parahaemolyticus VBNC cells exist and can remain dormant in the VBNC state for long periods. VBNC subpopulation P2, had a better fitness for survival under stressful conditions and showed 100% revival under favourable conditions. Proteomic analysis of these subpopulations (at two different time points: 12 days (T12) and 50 days (T50) post VBNC) revealed that the proteome of P2 was more similar to that of the starting microcosm culture (T0) than the proteome of P1. Proteins that were significantly up or down-regulated between the different VBNC populations were identified and differentially regulated proteins were assigned into 23 functional groups, the majority being assigned to metabolism functional categories. A lactate dehydrogenase (lldD) protein, responsible for converting lactate to pyruvate, was significantly upregulated in all subpopulations of VBNC cells. Deletion of the lactate dehydrogenase (RIMD2210633:ΔlldD) gene caused cells to enter the VBNC state significantly more quickly compared to the wild-type, and adding lactate to VBNC cells aided their resuscitation and extended the resuscitation window. Addition of pyruvate to the RIMD2210633:ΔlldD strain restored the wild-type VBNC formation profile. This study suggests that lactate dehydrogenase may play a role in regulating the VBNC state.
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10
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Vav2 catalysis-dependent pathways contribute to skeletal muscle growth and metabolic homeostasis. Nat Commun 2020; 11:5808. [PMID: 33199701 PMCID: PMC7669868 DOI: 10.1038/s41467-020-19489-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/16/2020] [Indexed: 12/17/2022] Open
Abstract
Skeletal muscle promotes metabolic balance by regulating glucose uptake and the stimulation of multiple interorgan crosstalk. We show here that the catalytic activity of Vav2, a Rho GTPase activator, modulates the signaling output of the IGF1- and insulin-stimulated phosphatidylinositol 3-kinase pathway in that tissue. Consistent with this, mice bearing a Vav2 protein with decreased catalytic activity exhibit reduced muscle mass, lack of proper insulin responsiveness and, at much later times, a metabolic syndrome-like condition. Conversely, mice expressing a catalytically hyperactive Vav2 develop muscle hypertrophy and increased insulin responsiveness. Of note, while hypoactive Vav2 predisposes to, hyperactive Vav2 protects against high fat diet-induced metabolic imbalance. These data unveil a regulatory layer affecting the signaling output of insulin family factors in muscle. Skeletal muscle plays a key role in regulating systemic glucose and metabolic homeostasis. Here, the authors show that the catalytic activity of Vav2, an activator of Rho GTPases, modulates those processes by favoring the responsiveness of this tissue to insulin and related factors.
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11
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Morcrette H, Kovacs-Simon A, Tennant RK, Love J, Wagley S, Yang ZR, Studholme DJ, Soyer OS, Champion OL, Butler CS, Titball RW. Campylobacter jejuni 11168H Exposed to Penicillin Forms Persister Cells and Cells With Altered Redox Protein Activity. Front Cell Infect Microbiol 2020; 10:565975. [PMID: 33194805 PMCID: PMC7641608 DOI: 10.3389/fcimb.2020.565975] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/11/2020] [Indexed: 12/13/2022] Open
Abstract
The formation of persister cells is one mechanism by which bacteria can survive exposure to environmental stresses. We show that Campylobacter jejuni 11168H forms persister cells at a frequency of 10−3 after exposure to 100 × MIC of penicillin G for 24 h. Staining the cell population with a redox sensitive fluorescent dye revealed that penicillin G treatment resulted in the appearance of a population of cells with increased fluorescence. We present evidence, to show this could be a consequence of increased redox protein activity in, or associated with, the electron transport chain. These data suggest that a population of penicillin G treated C. jejuni cells could undergo a remodeling of the electron transport chain in order to moderate membrane hyperpolarization and intracellular alkalization; thus reducing the antibiotic efficacy and potentially assisting in persister cell formation.
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Affiliation(s)
- Helen Morcrette
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Andrea Kovacs-Simon
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Richard K Tennant
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - John Love
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Sariqa Wagley
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Zheng R Yang
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - David J Studholme
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Orkun S Soyer
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Olivia L Champion
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Clive S Butler
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
| | - Richard W Titball
- College of Life and Environmental Sciences-Biosciences, University of Exeter, Exeter, United Kingdom
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12
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Sledz KM, Moore SF, Vijayaragavan V, Mallah S, Goudswaard LJ, Williams CM, Hunter RW, Hers I. Redundant role of ASK1-mediated p38MAPK activation in human platelet function. Cell Signal 2020; 68:109528. [PMID: 31917191 DOI: 10.1016/j.cellsig.2020.109528] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/20/2019] [Accepted: 01/03/2020] [Indexed: 10/25/2022]
Abstract
Apoptosis signal-regulating kinase 1 (ASK1) is a member of mitogen-activated protein kinase kinase kinase (MAP3K) family, which recently has been implicated in the regulation of p38 MAPK/PLA2/thromboxane (TxA2) generation, as well as P2Y12 signalling in murine platelets. ASK1 has therefore been proposed as a potential target for anti-thrombotic therapy. At present it is unknown whether ASK1 also contributes to TxA2 formation and platelet function in human. In this study we therefore examined the role of ASK1 using the ASK1 inhibitor selonsertib (GS-4997). We established that ASK1 is responsible for p38 phosphorylation and TxA2 formation in murine platelets, with both GS4997 and p38 inhibitors reducing TxA2 formation. Similar to murine platelets, activation of human platelets resulted in the rapid and transient phosphorylation of ASK1 and the MAP2Ks MMK3/4/6. In contrast, phosphorylation of p38 and its substrate; MAPKAP-kinase2 (MAPKAPK2) was much more sustained. In keeping with these findings, inhibition of ASK1 blocked early, but not later p38/MAPKAPK2 phosphorylation. The latter was dependent on non-canonical autophosphorylation as it was blocked by the p38 inhibitor; SB203580 and the SYK inhibitor; R406. Furthermore, ASK1 and p38 inhibitors had no effect on PLA2 phosphorylation, TxA2 formation and platelet aggregation, demonstrating that this pathway is redundant in human platelets. Together, these results demonstrate that ASK1 contributes to TxA2 formation in murine, but not human platelets and highlight the importance of confirming findings from genetic murine models in humans.
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Affiliation(s)
- Kamila M Sledz
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Samantha F Moore
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Vijayasameerah Vijayaragavan
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Shahida Mallah
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Lucy J Goudswaard
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Christopher M Williams
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Roger W Hunter
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Ingeborg Hers
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
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13
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Abstract
Phosphatidylinositol 3-kinase is an important signaling molecule that, once activated, leads to the generation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3). We performed a proteomic screen to identify PIP3-interacting proteins in human platelets. Among these proteins, we found engulfment and cell motility 1 (ELMO1), a scaffold protein with no catalytic activity. ELMO1 is expressed in platelets and interacts with active RhoG. However, the function of ELMO1 in platelets is not known. The focus of this study was to determine the function of ELMO1 in platelets utilizing ELMO1-/- mice. Platelet aggregation, granule secretion, integrin αIIbβ3 activation, and thromboxane generation were enhanced in ELMO1-/- platelets in response to glycoprotein VI (GPVI) agonists but unaltered when a protease-activated receptor 4 agonist was used. The kinetics of spreading on immobilized fibrinogen was enhanced in ELMO1-/- platelets compared with wild-type (WT) littermate controls. This suggests that ELMO1 plays a role downstream of the GPVI and integrin αIIbβ3 pathway. Furthermore, whole blood from ELMO1-/- mice perfused over collagen exhibited enhanced thrombus formation compared with WT littermate controls. ELMO1-/- mice showed reduced survival compared with control following pulmonary embolism. ELMO1-/- mice also exhibited a shorter time to occlusion using the ferric-chloride injury model and reduced bleeding times compared with WT littermate controls. These results indicate that ELMO1 plays an important role in hemostasis and thrombosis in vivo. RhoG activity was enhanced in ELMO1-/- murine platelets compared with WT littermate controls in response to GPVI agonist. Together, these data suggest that ELMO1 negatively regulates GPVI-mediated thrombus formation via RhoG.
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14
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Walsh TG, Wersäll A, Poole AW. Characterisation of the Ral GTPase inhibitor RBC8 in human and mouse platelets. Cell Signal 2019; 59:34-40. [PMID: 30880223 PMCID: PMC6510928 DOI: 10.1016/j.cellsig.2019.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 01/28/2023]
Abstract
The Ral GTPases, RalA and RalB, have been implicated in numerous cellular processes, but are most widely known for having regulatory roles in exocytosis. Recently, we demonstrated that deletion of both Ral genes in a platelet-specific mouse gene knockout caused a substantial defect in surface exposure of P-selectin, with only a relatively weak defect in platelet dense granule secretion that did not alter platelet functional responses such as aggregation or thrombus formation. We sought to investigate the function of Rals in human platelets using the recently described Ral inhibitor, RBC8. Initial studies in human platelets confirmed that RBC8 could effectively inhibit Ral GTPase activation, with an IC50 of 2.2 μM and 2.3 μM for RalA and RalB, respectively. Functional studies using RBC8 revealed significant, dose-dependent inhibition of platelet aggregation, secretion (α- and dense granule), integrin activation and thrombus formation, while α-granule release of platelet factor 4, Ca2+ signalling or phosphatidylserine exposure were unaltered. Subsequent studies in RalAB-null mouse platelets pretreated with RBC8 showed dose-dependent decreases in integrin activation and dense granule secretion, with significant inhibition of platelet aggregation and P-selectin exposure at 10 μM RBC8. This study strongly suggests therefore that although RBC8 is useful as a Ral inhibitor in platelets, it is likely also to have off-target effects in the same concentration range as for Ral inhibition. So, whilst clearly useful as a Ral inhibitor, interpretation of data needs to take this into account when assessing roles for Rals using RBC8.
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Affiliation(s)
- Tony G Walsh
- From the School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, United Kingdom.
| | - Andreas Wersäll
- From the School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Alastair W Poole
- From the School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol BS8 1TD, United Kingdom
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15
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Kovacs-Simon A, Hemsley CM, Scott AE, Prior JL, Titball RW. Burkholderia thailandensis strain E555 is a surrogate for the investigation of Burkholderia pseudomallei replication and survival in macrophages. BMC Microbiol 2019; 19:97. [PMID: 31092204 PMCID: PMC6521459 DOI: 10.1186/s12866-019-1469-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/30/2019] [Indexed: 02/02/2023] Open
Abstract
Background Burkholderia pseudomallei is a human pathogen causing severe infections in tropical and subtropical regions and is classified as a bio-threat agent. B. thailandensis strain E264 has been proposed as less pathogenic surrogate for understanding the interactions of B. pseudomallei with host cells. Results We show that, unlike B. thailandensis strain E264, the pattern of growth of B. thailandensis strain E555 in macrophages is similar to that of B. pseudomallei. We have genome sequenced B. thailandensis strain E555 and using the annotated sequence identified genes and proteins up-regulated during infection. Changes in gene expression identified more of the known B. pseudomallei virulence factors than changes in protein levels and used together we identified 16% of the currently known B. pseudomallei virulence factors. These findings demonstrate the utility of B. thailandensis strain E555 to study virulence of B. pseudomallei. Conclusions A weakness of studies using B. thailandensis as a surrogate for B. pseudomallei is that the strains used replicate at a slower rate in infected cells. We show that the pattern of growth of B. thailandensis strain E555 in macrophages closely mirrors that of B. pseudomallei. Using this infection model we have shown that virulence factors of B. pseudomallei can be identified as genes or proteins whose expression is elevated on the infection of macrophages. This finding confirms the utility of B. thailandensis strain E555 as a surrogate for B. pseudomallei and this strain should be used for future studies on virulence mechanisms. Electronic supplementary material The online version of this article (10.1186/s12866-019-1469-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- A Kovacs-Simon
- College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
| | - C M Hemsley
- College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK
| | - A E Scott
- CBR Division, Defence Science and Technology Laboratory, Porton Down, Salisbury, SP4 0JQ, UK
| | - J L Prior
- College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.,CBR Division, Defence Science and Technology Laboratory, Porton Down, Salisbury, SP4 0JQ, UK
| | - R W Titball
- College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK
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16
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Alterations in Platelet Alpha-Granule Secretion and Adhesion on Collagen under Flow in Mice Lacking the Atypical Rho GTPase RhoBTB3. Cells 2019; 8:cells8020149. [PMID: 30754723 PMCID: PMC6406922 DOI: 10.3390/cells8020149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 01/31/2019] [Accepted: 02/07/2019] [Indexed: 12/23/2022] Open
Abstract
Typical Rho GTPases, such as Rac1, Cdc42, and RhoA, act as molecular switches regulating various aspects of platelet cytoskeleton reorganization. The loss of these enzymes results in reduced platelet functionality. Atypical Rho GTPases of the RhoBTB subfamily are characterized by divergent domain architecture. One family member, RhoBTB3, is expressed in platelets, but its function is unclear. In the present study we examined the role of RhoBTB3 in platelet function using a knockout mouse model. We found the platelet count, size, numbers of both alpha and dense granules, and surface receptor profile in these mice were comparable to wild-type mice. Deletion of Rhobtb3 had no effect on aggregation and dense granule secretion in response to a range of agonists including thrombin, collagen, and adenosine diphosphate (ADP). By contrast, alpha-granule secretion increased in mice lacking RhoBTB3 in response to thrombin, collagen related peptide (CRP) and U46619/ADP. Integrin activation and spreading on fibrinogen and collagen under static conditions were also unimpaired; however, we observed reduced platelet accrual on collagen under flow conditions. These defects did not translate into alterations in tail bleeding time. We conclude that genetic deletion of Rhobtb3 leads to subtle alterations in alpha-granule secretion and adhesion to collagen without significant effects on hemostasis in vivo.
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17
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Loss of the mitochondrial kinase PINK1 does not alter platelet function. Sci Rep 2018; 8:14377. [PMID: 30258205 PMCID: PMC6158262 DOI: 10.1038/s41598-018-32716-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/07/2018] [Indexed: 11/24/2022] Open
Abstract
PTEN-induced putative kinase (PINK) 1 is regarded as a master regulator of cellular mitophagy such that loss of function mutations contribute to early onset Parkinson’s disease, through aberrant mitochondrial control and function. Mitochondrial function is key to platelet procoagulant activity, controlling the haemostatic response to vessel injury, but can also predispose blood vessels to thrombotic complications. Here, we sought to determine the role of PINK1 in platelet mitochondrial health and function using PINK1 knockout (KO) mice. The data largely show an absence of such a role. Haematological analysis of blood counts from KO mice was comparable to wild type. Quantification of mitochondrial mass by citrate synthase activity assay or expression of mitochondrial markers were comparable, suggesting normal mitophagy in KO platelets. Analysis of mitochondrial permeability transition pore opening, changes in mitochondrial membrane potential and calcium signalling to platelet activation were unaffected by loss of PINK1, whereas subtle enhancements of activation-induced reactive oxygen species were detected. Platelet aggregation, integrin activation, α- and dense granule secretion and phosphatidylserine exposure were unaltered in KO platelets while mouse tail bleeding responses were similar to wild type. Together these results demonstrate that PINK1 does not regulate basal platelet mitophagy and is dispensable for platelet function.
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18
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Pleines I, Cherpokova D, Bender M. Rho GTPases and their downstream effectors in megakaryocyte biology. Platelets 2018; 30:9-16. [DOI: 10.1080/09537104.2018.1478071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Irina Pleines
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Deya Cherpokova
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Markus Bender
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
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19
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Affiliation(s)
- Joseph E. Aslan
- Knight Cardiovascular Institute, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
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20
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Hart JE, Clarke IJ, Risbridger GP, Ferneyhough B, Vega-Hernández M. Mysterious inhibitory cell regulator investigated and found likely to be secretogranin II related. PeerJ 2017; 5:e3833. [PMID: 29043108 PMCID: PMC5642266 DOI: 10.7717/peerj.3833] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/30/2017] [Indexed: 01/22/2023] Open
Abstract
In the context of a hunt for a postulated hormone that is tissue-mass inhibiting and reproductively associated, there is described probable relatedness to a granin protein. A 7–8 kDa polypeptide candidate (gels/MS) appeared in a bioassay-guided fractionation campaign involving sheep plasma. An N-terminal sequence of 14 amino acids was obtained for the polypeptide by Edman degradation. Bioinformatics and molecular biology failed to illuminate any ovine or non-ovine protein which might relate to this sequence. The N-terminal sequence was synthesized as the 14mer EPL001 peptide and surprisingly found to be inhibitory in an assay in vivo of compensatory renal growth in the rat and modulatory of nematode fecundity, in line with the inhibitory hormone hypothesis. Antibodies were raised to EPL001 and their deployment upheld the hypothesis that the EPL001 amino acid sequence is meaningful and relevant, notwithstanding bioinformatic obscurity. Immunohistochemistry (IHC) in sheep, rodents and humans yielded staining of seeming endocrine relevance (e.g. hypothalamus, gonads and neuroendocrine cells in diverse tissues), with apparent upregulation in certain human tumours (e.g. pheochromocytoma). Discrete IHC staining in Drosophila melanogaster embryo brain was seen in glia and in neuroendocrine cells, with staining likely in the corpus cardiacum. The search for the endogenous antigen involved immunoprecipitation (IP) followed by liquid chromatography and mass spectrometry (LC–MS). Feedstocks were PC12 conditioned medium and aqueous extract of rat hypothalamus—both of which had anti-proliferative and pro-apoptotic effects in an assay in vitro involving rat bone marrow cells, which inhibition was subject to prior immunodepletion with an anti-EPL001 antibody—together with fruit fly embryo material. It is concluded that the mammalian antigen is likely secretogranin II (SgII) related. The originally seen 7–8 kDa polypeptide is suggested to be a new proteoform of secretogranin II of ∼70 residues, SgII-70, with the anti-EPL001 antibody seeing a discontinuous epitope. The fly antigen is probably Q9W2X8 (UniProt), an uncharacterised protein newly disclosed as a granin and provisionally dubbed macrogranin I (MgI). SgII and Q9W2X8 merit further investigation in the context of tissue-mass inhibition.
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Affiliation(s)
- John E Hart
- Endocrine Pharmaceuticals, Tadley, Hampshire, UK
| | - Iain J Clarke
- Department of Physiology, Neuroscience Program, Monash Biomedical Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Gail P Risbridger
- Department of Anatomy and Developmental Biology, Biomedical Discovery Institute, Monash University, Clayton, VIC, Australia
| | | | - Mónica Vega-Hernández
- Department of Zoology, Lawrence Laboratory, University of Cambridge, Cambridge, Cambridgeshire, UK
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21
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BASP1 interacts with oestrogen receptor α and modifies the tamoxifen response. Cell Death Dis 2017; 8:e2771. [PMID: 28492543 PMCID: PMC5520704 DOI: 10.1038/cddis.2017.179] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/14/2017] [Accepted: 03/15/2017] [Indexed: 01/01/2023]
Abstract
Tamoxifen binds to oestrogen receptor α (ERα) to elicit distinct responses that vary by cell/tissue type and status, but the factors that determine these differential effects are unknown. Here we report that the transcriptional corepressor BASP1 interacts with ERα and in breast cancer cells, this interaction is enhanced by tamoxifen. We find that BASP1 acts as a major selectivity factor in the transcriptional response of breast cancer cells to tamoxifen. In all, 40% of the genes that are regulated by tamoxifen in breast cancer cells are BASP1 dependent, including several genes that are associated with tamoxifen resistance. BASP1 elicits tumour-suppressor activity in breast cancer cells and enhances the antitumourigenic effects of tamoxifen treatment. Moreover, BASP1 is expressed in breast cancer tissue and is associated with increased patient survival. Our data have identified BASP1 as an ERα cofactor that has a central role in the transcriptional and antitumourigenic effects of tamoxifen.
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22
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Receptor-interacting protein kinase 3 promotes platelet activation and thrombosis. Proc Natl Acad Sci U S A 2017; 114:2964-2969. [PMID: 28242694 DOI: 10.1073/pnas.1610963114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previous studies have shown that receptor-interacting protein kinase 3 (RIP3) is involved in many important biological processes, including necroptosis, apoptosis, and inflammation. Here we show that RIP3 plays a critical role in regulating platelet functions and in vivo thrombosis and hemostasis. Tail bleeding times were significantly longer in RIP3-knockout (RIP3-/-) mice compared with their wild-type (WT) littermates. In an in vivo model of arteriole thrombosis, mice lacking RIP3 exhibited prolonged occlusion times. WT mice repopulated with RIP3-/- bone marrow-derived cells had longer occlusion times than RIP3-/- mice repopulated with WT bone marrow-derived cells, suggesting a role for RIP3-deficient platelets in arterial thrombosis. Consistent with these findings, we observed that RIP3 was expressed in both human and mice platelets. Deletion of RIP3 in mouse platelets caused a marked defect in aggregation and attenuated dense granule secretion in response to low doses of thrombin or a thromboxane A2 analog, U46619. Phosphorylation of Akt induced by U46619 or thrombin was diminished in RIP3-/- platelets. Moreover, RIP3 interacted with Gα13 Platelet spreading on fibrinogen and clot retraction were impaired in the absence of RIP3. RIP3 inhibitor dose-dependently inhibited platelet aggregation in vitro and prevented arterial thrombus formation in vivo. These data demonstrate a role for RIP3 in promoting in vivo thrombosis and hemostasis by amplifying platelet activation. RIP3 may represent a novel promising therapeutic target for thrombotic diseases.
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23
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Battram AM, Durrant TN, Agbani EO, Heesom KJ, Paul DS, Piatt R, Poole AW, Cullen PJ, Bergmeier W, Moore SF, Hers I. The Phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) Binder Rasa3 Regulates Phosphoinositide 3-kinase (PI3K)-dependent Integrin αIIbβ3 Outside-in Signaling. J Biol Chem 2017; 292:1691-1704. [PMID: 27903653 PMCID: PMC5290945 DOI: 10.1074/jbc.m116.746867] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/14/2016] [Indexed: 11/16/2022] Open
Abstract
The class I PI3K family of lipid kinases plays an important role in integrin αIIbβ3 function, thereby supporting thrombus growth and consolidation. Here, we identify Ras/Rap1GAP Rasa3 (GAP1IP4BP) as a major phosphatidylinositol 3,4,5-trisphosphate-binding protein in human platelets and a key regulator of integrin αIIbβ3 outside-in signaling. We demonstrate that cytosolic Rasa3 translocates to the plasma membrane in a PI3K-dependent manner upon activation of human platelets. Expression of wild-type Rasa3 in integrin αIIbβ3-expressing CHO cells blocked Rap1 activity and integrin αIIbβ3-mediated spreading on fibrinogen. In contrast, Rap1GAP-deficient (P489V) and Ras/Rap1GAP-deficient (R371Q) Rasa3 had no effect. We furthermore show that two Rasa3 mutants (H794L and G125V), which are expressed in different mouse models of thrombocytopenia, lack both Ras and Rap1GAP activity and do not affect integrin αIIbβ3-mediated spreading of CHO cells on fibrinogen. Platelets from thrombocytopenic mice expressing GAP-deficient Rasa3 (H794L) show increased spreading on fibrinogen, which in contrast to wild-type platelets is insensitive to PI3K inhibitors. Together, these results support an important role for Rasa3 in PI3K-dependent integrin αIIbβ3-mediated outside-in signaling and cell spreading.
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Affiliation(s)
- Anthony M Battram
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Tom N Durrant
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Ejaife O Agbani
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Kate J Heesom
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - David S Paul
- the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Raymond Piatt
- the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Alastair W Poole
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Peter J Cullen
- School of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Wolfgang Bergmeier
- the McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514
| | - Samantha F Moore
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom
| | - Ingeborg Hers
- From the School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, United Kingdom.
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24
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Ngo ATP, Thierheimer MLD, Babur Ö, Rocheleau AD, Huang T, Pang J, Rigg RA, Mitrugno A, Theodorescu D, Burchard J, Nan X, Demir E, McCarty OJT, Aslan JE. Assessment of roles for the Rho-specific guanine nucleotide dissociation inhibitor Ly-GDI in platelet function: a spatial systems approach. Am J Physiol Cell Physiol 2017; 312:C527-C536. [PMID: 28148498 PMCID: PMC5407014 DOI: 10.1152/ajpcell.00274.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/29/2022]
Abstract
On activation at sites of vascular injury, platelets undergo morphological alterations essential to hemostasis via cytoskeletal reorganizations driven by the Rho GTPases Rac1, Cdc42, and RhoA. Here we investigate roles for Rho-specific guanine nucleotide dissociation inhibitor proteins (RhoGDIs) in platelet function. We find that platelets express two RhoGDI family members, RhoGDI and Ly-GDI. Whereas RhoGDI localizes throughout platelets in a granule-like manner, Ly-GDI shows an asymmetric, polarized localization that largely overlaps with Rac1 and Cdc42 as well as microtubules and protein kinase C (PKC) in platelets adherent to fibrinogen. Antibody interference and platelet spreading experiments suggest a specific role for Ly-GDI in platelet function. Intracellular signaling studies based on interactome and pathways analyses also support a regulatory role for Ly-GDI, which is phosphorylated at PKC substrate motifs in a PKC-dependent manner in response to the platelet collagen receptor glycoprotein (GP) VI-specific agonist collagen-related peptide. Additionally, PKC inhibition diffuses the polarized organization of Ly-GDI in spread platelets relative to its colocalization with Rac1 and Cdc42. Together, our results suggest a role for Ly-GDI in the localized regulation of Rho GTPases in platelets and hypothesize a link between the PKC and Rho GTPase signaling systems in platelet function.
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Affiliation(s)
- Anh T P Ngo
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Marisa L D Thierheimer
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon.,School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon; and
| | - Özgün Babur
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon.,Computational Biology Program, Oregon Health & Science University, Portland, Oregon
| | - Anne D Rocheleau
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Tao Huang
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Jiaqing Pang
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Rachel A Rigg
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Annachiara Mitrugno
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Dan Theodorescu
- Department of Surgery, Department of Pharmacology, and Comprehensive Cancer Center University of Colorado, Aurora, Colorado
| | - Julja Burchard
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon
| | - Xiaolin Nan
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon
| | - Emek Demir
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon.,Computational Biology Program, Oregon Health & Science University, Portland, Oregon
| | - Owen J T McCarty
- Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon.,Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University, Portland, Oregon.,Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, Oregon
| | - Joseph E Aslan
- Knight Cardiovascular Institute, School of Medicine, Oregon Health & Science University, Portland, Oregon;
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25
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Akbar H, Duan X, Saleem S, Davis AK, Zheng Y. RhoA and Rac1 GTPases Differentially Regulate Agonist-Receptor Mediated Reactive Oxygen Species Generation in Platelets. PLoS One 2016; 11:e0163227. [PMID: 27681226 PMCID: PMC5040254 DOI: 10.1371/journal.pone.0163227] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 09/06/2016] [Indexed: 12/19/2022] Open
Abstract
Agonist induced generation of reactive oxygen species (ROS) by NADPH oxidases (NOX) enhances platelet aggregation and hence the risk of thrombosis. RhoA and Rac1 GTPases are involved in ROS generation by NOX in a variety of cells, but their roles in platelet ROS production remain unclear. In this study we used platelets from RhoA and Rac1 conditional knockout mice as well as human platelets treated with Rhosin and NSC23767, rationally designed small molecule inhibitors of RhoA and Rac GTPases, respectively, to better define the contributions of RhoA and Rac1 signaling to ROS generation and platelet activation. Treatment of platelets with Rhosin inhibited: (a) U46619 induced activation of RhoA; (b) phosphorylation of p47phox, a critical component of NOX; (c) U46619 or thrombin induced ROS generation; (d) phosphorylation of myosin light chain (MLC); (e) platelet shape change; (f) platelet spreading on immobilized fibrinogen; and (g) release of P-selectin, secretion of ATP and aggregation. Conditional deletion of RhoA or Rac1 gene inhibited thrombin induced ROS generation in platelets. Addition of Y27632, a RhoA inhibitor, NSC23766 or Phox-I, an inhibitor of Rac1-p67phox interaction, to human platelets blocked thrombin induced ROS generation. These data suggest that: (a) RhoA/ROCK/p47phox signaling axis promotes ROS production that, at least in part, contributes to platelet activation in conjunction with or independent of the RhoA/ROCK mediated phosphorylation of MLC; and (b) RhoA and Rac1 differentially regulate ROS generation by inhibiting phosphorylation of p47phox and Rac1-p67phox interaction, respectively.
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Affiliation(s)
- Huzoor Akbar
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, 45701, United States of America
- * E-mail:
| | - Xin Duan
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
| | - Saima Saleem
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, 45701, United States of America
| | - Ashley K. Davis
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, OH, 45229, United States of America
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Williams CM, Harper MT, Goggs R, Walsh TG, Offermanns S, Poole AW. Leukemia-associated Rho guanine-nucleotide exchange factor is not critical for RhoA regulation, yet is important for platelet activation and thrombosis in mice. J Thromb Haemost 2015; 13:2102-7. [PMID: 26334261 PMCID: PMC4755168 DOI: 10.1111/jth.13129] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/12/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND RhoA is an important regulator of platelet responses downstream of Gα13 , yet we still know little about its regulation in platelets. Leukemia-associated Rho guanine-nucleotide exchange factor (GEF [LARG]), a RhoA GEF, is highly expressed in platelets and may constitute a major upstream activator of RhoA. To this end, it is important to determine the role of LARG in platelet function and thrombosis. METHODS AND RESULTS Using a platelet-specific gene knockout, we show that the absence of LARG results in a marked reduction in aggregation and dense-granule secretion in response to the thromboxane mimetic U46619 and proteinase-activated receptor 4-activating peptide, AYPGKF, but not to adenosine diphosphate. In a ferric chloride thrombosis model in vivo, this translated into a defect, under mild injury conditions. Importantly, agonist-induced RhoA activation was not affected by the absence of LARG, although basal activity was reduced, suggesting that LARG may play a housekeeper role in regulating constitutive RhoA activity. CONCLUSIONS LARG plays an important role in platelet function and thrombosis in vivo. However, although LARG may have a role in regulating the resting activation state of RhoA, its role in regulating platelet function may principally be through RhoA-independent pathways, possibly through other Rho family members.
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Affiliation(s)
- C M Williams
- School of Physiology & Pharmacology, University of Bristol, Bristol, UK
| | - M T Harper
- School of Physiology & Pharmacology, University of Bristol, Bristol, UK
| | - R Goggs
- School of Physiology & Pharmacology, University of Bristol, Bristol, UK
| | - T G Walsh
- School of Physiology & Pharmacology, University of Bristol, Bristol, UK
| | - S Offermanns
- Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - A W Poole
- School of Physiology & Pharmacology, University of Bristol, Bristol, UK
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27
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Abstract
Rho GTPases are critical for platelet function. Although the roles of RhoA, Rac and Cdc42 are characterized, platelets express other Rho GTPases, whose activities are less well understood. This review summarizes our understanding of the roles of platelet Rho GTPases and focuses particularly on the functions of Rif and RhoG. In human platelets, Rif interacts with cytoskeleton regulators including formins mDia1 and mDia3, whereas RhoG binds SNARE-complex proteins and cytoskeletal regulators ELMO and DOCK1. Knockout mouse studies suggest that Rif plays no critical functions in platelets, likely due to functional overlap with other Rho GTPases. In contrast, RhoG is essential for normal granule secretion downstream of the collagen receptor GPVI. The central defect in RhoG-/- platelets is reduced dense granule secretion, which impedes integrin activation and aggregation and limits platelet recruitment to growing thrombi under shear, translating into reduced thrombus formation in vivo. Potential avenues for future work on Rho GTPases in platelets are also highlighted, including identification of the key regulator for platelet filopodia formation and investigation of the role of the many Rho GTPase regulators in platelet function in both health and disease.
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28
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Elvers M. RhoGAPs and Rho GTPases in platelets. Hamostaseologie 2015; 36:168-77. [PMID: 25639730 DOI: 10.5482/hamo-14-09-0046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/13/2015] [Indexed: 01/03/2023] Open
Abstract
Platelet cytoskeletal reorganization is essential for platelet adhesion and thrombus formation in hemostasis and thrombosis. The Rho GTPases RhoA, Rac1 and Cdc42 are the main players in cytoskeletal dynamics of platelets responsible for the formation of filopodia and lamellipodia to strongly increase the platelet surface upon activation. They are involved in platelet activation and aggregate formation including platelet secretion, integrin activation and arterial thrombus formation. The activity of Rho GTPases is tightly controlled by different proteins such as GTPase-activating proteins (GAPs). GAPs stimulate GTP hydrolysis to terminate Rho signaling. The role and impact of GAPs in platelets is not well-defined and many of the RhoGAPs identified are not known to be present in platelets or to have any function in platelets. The recently identified RhoGAPs Oligophrenin1 (OPHN1) and Nadrin regulate the activity of RhoA, Rac1 and Cdc42 and subsequent platelet cytoskeletal reorganization, platelet activation and thrombus formation. In the last years, the analysis of genetically modified mice helped to gain the understanding of Rho GTPases and their regulators in cytoskeletal rearrangements and other Rho mediated cellular processes in platelets.
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Affiliation(s)
- Margitta Elvers
- Margitta Elvers, Ph.D., Department of Clinical and Experimental Hemostasis, Hemotherapy and Transfusion Medicine, Heinrich-Heine-University Duesseldorf, Moorenstr. 5, 40225 Duesseldorf, Germany, Tel. +49/(0)211/81-08851, Fax -17498., E-mail:
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29
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Kim S, Dangelmaier C, Bhavanasi D, Meng S, Wang H, Goldfinger LE, Kunapuli SP. RhoG protein regulates glycoprotein VI-Fc receptor γ-chain complex-mediated platelet activation and thrombus formation. J Biol Chem 2013; 288:34230-34238. [PMID: 24106269 DOI: 10.1074/jbc.m113.504928] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We investigated the mechanism of activation and functional role of a hitherto uncharacterized signaling molecule, RhoG, in platelets. We demonstrate for the first time the expression and activation of RhoG in platelets. Platelet aggregation, integrin αIIbβ3 activation, and α-granule and dense granule secretion in response to the glycoprotein VI (GPVI) agonists collagen-related peptide (CRP) and convulxin were significantly inhibited in RhoG-deficient platelets. In contrast, 2-MeSADP- and AYPGKF-induced platelet aggregation and secretion were minimally affected in RhoG-deficient platelets, indicating that the function of RhoG in platelets is GPVI-specific. CRP-induced phosphorylation of Syk, Akt, and ERK, but not SFK (Src family kinase), was significantly reduced in RhoG-deficient platelets. CRP-induced RhoG activation was consistently abolished by a pan-SFK inhibitor but not by Syk or PI3K inhibitors. Interestingly, unlike CRP, platelet aggregation and Syk phosphorylation induced by fucoidan, a CLEC-2 agonist, were unaffected in RhoG-deficient platelets. Finally, RhoG(-/-) mice had a significant delay in time to thrombotic occlusion in cremaster arterioles compared with wild-type littermates, indicating the important in vivo functional role of RhoG in platelets. Our data demonstrate that RhoG is expressed and activated in platelets, plays an important role in GPVI-Fc receptor γ-chain complex-mediated platelet activation, and is critical for thrombus formation in vivo.
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Affiliation(s)
- Soochong Kim
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Carol Dangelmaier
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Dheeraj Bhavanasi
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Shu Meng
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Hong Wang
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Lawrence E Goldfinger
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
| | - Satya P Kunapuli
- Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140; Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
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