title: Platelet actin nodules are podosome-like structures dependent on Wiskott-Aldrich syndrome protein and ARP2/3 complex.
abstract: The actin nodule is a novel F-actin structure present in platelets during early spreading. However, only limited detail is known regarding nodule organization and function. Here we use electron microscopy, SIM and dSTORM super-resolution, and live-cell TIRF microscopy to characterize the structural organization and signalling pathways associated with nodule formation. Nodules are composed of up to four actin-rich structures linked together by actin bundles. They are enriched in the adhesion-related proteins talin and vinculin, have a central core of tyrosine phosphorylated proteins and are depleted of integrins at the plasma membrane. Nodule formation is dependent on Wiskott-Aldrich syndrome protein (WASp) and the ARP2/3 complex. WASp(-/-) mouse blood displays impaired platelet aggregate formation at arteriolar shear rates. We propose actin nodules are platelet podosome-related structures required for platelet-platelet interaction and their absence contributes to the bleeding diathesis of Wiskott-Aldrich syndrome.
authors.affiliation: Centre for Cardiovascular Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Natalie S
authors.initials: NS
authors.lastname: Poulter
authors.affiliation: Centre for Cardiovascular Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Pollitt
authors.affiliation: PSIBS doctoral training centre, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Davies
authors.affiliation: Molecular Immunology Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
authors.forename: Dessislava
authors.initials: D
authors.lastname: Malinova
authors.affiliation: Centre for Cardiovascular Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Gerard B
authors.initials: GB
authors.lastname: Nash
authors.affiliation: PSIBS doctoral training centre, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Mike J
authors.initials: MJ
authors.lastname: Hannon
authors.affiliation: School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Zoe
authors.initials: Z
authors.lastname: Pikramenou
authors.affiliation: The Center for Advanced Microscopy and Nikon Imaging Center, Morton 2-681, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, Illinois 60611, USA.
authors.forename: Joshua Z
authors.initials: JZ
authors.lastname: Rappoport
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Hartwig
authors.affiliation: Randall Division of Cell and Molecular Biophysics, New Hunt's House, King's College London, Guy's Campus, London SE1 1UL, UK.
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Owen
authors.affiliation: Molecular Immunology Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Thrasher
authors.affiliation: Centre for Cardiovascular Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Watson
authors.affiliation: Centre for Cardiovascular Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Steven G
authors.identifier: http://orcid.org/0000-0001-8733-7842
authors.initials: SG
authors.lastname: Thomas
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism*; D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D061848:Optical Imaging; D010974:Platelet Aggregation / Q000235:genetics*; D000069261:Podosomes / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D016608:Talin / Q000378:metabolism; D016596:Vinculin / Q000378:metabolism; D014923:Wiskott-Aldrich Syndrome / Q000097:blood / Q000235:genetics*; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D016608:Talin; C495767:WAS protein, human; C495768:Was protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D016596:Vinculin