title: RNA and RNA binding proteins participate in early stages of cell spreading through spreading initiation centers.
abstract: Focal adhesions are specialized attachment and signaling centers that form at sites of cell-matrix contacts. We employed a quantitative mass spectrometry-based method called SILAC to identify and quantify proteins interacting in an attachment-dependent manner with focal adhesion proteins. Subsequent confocal microscopy revealed a previously undescribed structure, which we have termed a spreading initiation center (SIC), existing only in early stages of cell spreading. SICs contain focal adhesion markers, appear to be surrounded by an actin sheath, and, surprisingly, contain numerous RNA binding proteins, ribosomal RNA, and perhaps other RNAs. Interfering with the function of FUS/TLS, hnRNP K, and hnRNP E1 results in increased spreading. Spreading initiation centers are ribonucleoprotein complexes distinct from focal adhesions and demonstrate a role for RNA and RNA binding proteins in the initiation of cell spreading.
authors.affiliation: Center for Experimental BioInformatics (CEBI), Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: de Hoog
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Foster
authors.forename: Matthias
authors.initials: M
authors.lastname: Mann
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism; D051379:Mice; D020543:Proteome / Q000502:physiology; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000378:metabolism; D016596:Vinculin / Q000378:metabolism
chemical_list: D000199:Actins; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D020543:Proteome; D016601:RNA-Binding Proteins; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D016596:Vinculin; D012313:RNA