Functional ESCRT machinery is required for constitutive recycling of claudin-1 and maintenance of polarity in vertebrate epithelial cells
Authors: Paul Whitley
Andrew D Chalmers
Judith D Richardson
Elizabeth Blaikley
Christopher J Caunt
Samir Burns
Laura Fish
Joseph D Dukes
Journal: Molecular Biology of the Cell (2011)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: Genetic screens; Drosophila; endocytic trafficking; neoplastic tumor suppressor genes; ESCRT proteins
Affiliations: Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Bath BA2 7AY, United Kingdom., Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Bath BA2 7AY, United Kingdom

Abstract:  Genetic screens in Drosophila have identified regulators of endocytic trafficking as neoplastic tumor suppressor genes. For example, Drosophila endosomal sorting complex required for transport (ESCRT) mutants lose epithelial polarity and show increased cell proliferation, suggesting that ESCRT proteins could function as tumor suppressors. In this study, we show for the for the first time to our knowledge that ESCRT proteins are required to maintain polarity in mammalian epithelial cells. Inhibition of ESCRT function caused the tight junction protein claudin-1 to accumulate in intracellular vesicles. In contrast E-cadherin and occludin localization was unaffected. We investigated the cause of this accumulation and show that claudin-1 is constitutively recycled in kidney, colon, and lung epithelial cells, identifying claudin-1 recycling as a newly described feature of diverse epithelial cell types. This recycling requires ESCRT function, explaining the accumulation of intracellular claudin-1 when ESCRT function is inhibited. We further demonstrate that small interfering RNA knockdown of the ESCRT protein Tsg101 causes epithelial monolayers to lose their polarized organization and interferes with the establishment of a normal epithelial permeability barrier. ESCRT knockdown also reduces the formation of correctly polarized three-dimensional cysts. Thus, in mammalian epithelial cells, ESCRT function is required for claudin-1 trafficking and for epithelial cell polarity, supporting the hypothesis that ESCRT proteins function as tumor suppressors. 

Retracted: No

PubPeer comments:
 Correction, October 2017: https: www.molbiolcell.org doi 10.1091 mboc.25.16.2537  The authors of u201cFunctional ESCRT machinery is required for constitutive recycling of claudin-1 and maintenance of polarity in vertebrate epithelial cellsu201d (Mol. Biol. Cell [2011] 22, 3192u20133205; first published in MBoC In Press as 10.1091 mbc.E11-04-0343) wish to make a correction to Figure 4B in the article. In the original HTML and PDF versions, the panel of Western blots shown in 4C was mistakenly shown also for Figure 4B. The accompanying quantifications for 4B and 4C were correct in the original version, but the blots were duplicated. A correct version of the Western blots for Figure 4B (CaCo-2) is given in the corrected Figure 4 below. The authors regret the error and thank a reader for pointing out this mistake. The HTML and PDF versions were corrected on July 28, 2014. These corrections may not appear on copies of the article that reside on other websites. This issue was reported to the journal in April 2014. I thank the authors and journal for this correction. ,