Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells
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Crumbs3 (CRB3) is a component of epithelial junctions that 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. However, significantly we demonstrate that the 4.1-ezrin-radixin-moesin (FERM) binding motif (FBM) 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 tight junction proteins. We demonstrate that both CRB3 isoforms are required for the production of functionally mature tight junctions 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 show evidence that whilst CRB3a expression has no effect, low CRB3b and high cytoplasmic ezrin expression combined may be prognostic for HNSCC.
Tilston-Lunel , A M , Haley , K , Schlecht , N , Wang , Y , Chatterton , A L D , Moleirinho , S L , Watson , A , Hundal , H , Prystowsky , M , Gunn-Moore , F J & Reynolds , P A 2016 , ' Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells ' Journal of Molecular Cell Biology , vol 8 , no. 5 , pp. 439-455 . DOI: 10.1093/jmcb/MJW020
Journal of Molecular Cell Biology
© The Author (2016). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1093/jmcb/mjw020
AMT-L is supported by the School of Biology, University of St Andrews. AMT-L, PAR and FJGM were funded by the Anonymous Trust, University of St Andrews. PAR is supported by the Melville Trust for the Care and Cure of Cancer. The mass spectrometry work was supported by the Wellcome Trust [grant number 094476/Z/10/Z], which funded the purchase of the TripleTOF 5600 mass spectrometer at the BSRC Mass Spectrometry and Proteomics Facility, University of St Andrews. The clinical study was supported by the Department of Pathology, Albert Einstein College of Medicine/ Montefiore Medical Center.
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