title: Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells.
abstract: Crumbs 3 (CRB3) is a component of epithelial junctions, which has been implicated in apical-basal polarity, apical identity, apical stability, cell adhesion, and cell growth. CRB3 undergoes alternative splicing to yield two variants: CRB3a and CRB3b. Here, we describe novel data demonstrating that, as with previous studies on CRB3a, CRB3b also promotes the formation of tight junctions (TJs). However, significantly we demonstrate that the 4.1-ezrin-radixin-moesin-binding motif of CRB3b is required for CRB3b functionality and that ezrin binds to the FBM of CRB3b. Furthermore, we show that ezrin contributes to CRB3b functionality and the correct distribution of TJ proteins. We demonstrate that both CRB3 isoforms are required for the production of functionally mature TJs and also the localization of ezrin to the plasma membrane. Finally, we demonstrate that reduced CRB3b expression in head and neck squamous cell carcinoma (HNSCC) correlates with cytoplasmic ezrin, a biomarker for aggressive disease, and shows evidence that while CRB3a expression has no effect, low CRB3b and high cytoplasmic ezrin expression combined may be prognostic for HNSCC.
authors.affiliation: Medical and Biological Sciences Building, School of Biology, University of St Andrews, St Andrews, KY16 9TF, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Tilston-Lünel
authors.affiliation: Medical and Biological Sciences Building, School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Haley
authors.affiliation: Department of Epidemiology & Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Nicolas F
authors.initials: NF
authors.lastname: Schlecht
authors.affiliation: Department of Epidemiology & Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Medical and Biological Sciences Building, School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.
authors.forename: Abigail L D
authors.initials: ALD
authors.lastname: Chatterton
authors.affiliation: Medical and Biological Sciences Building, School of Biology, University of St Andrews, St Andrews, KY16 9TF, UK.|Medical and Biological Sciences Building, School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.|Present address: Scripps Research Institute, Jupiter, FL, USA.
authors.forename: Susana
authors.initials: S
authors.lastname: Moleirinho
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Ailsa
authors.initials: A
authors.lastname: Watson
authors.affiliation: Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Harinder S
authors.initials: HS
authors.lastname: Hundal
authors.affiliation: School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Prystowsky
authors.affiliation: Medical and Biological Sciences Building, School of Biology, University of St Andrews, St Andrews, KY16 9TF, UK.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Gunn-Moore
authors.affiliation: Medical and Biological Sciences Building, School of Medicine, University of St Andrews, St Andrews, KY16 9TF, UK.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Reynolds
keywords: CRB3; FBM; FERM proteins; crumbs; ezrin; tight junctions