Published online
doi:10.1083/jcb.200804154
The Journal of Cell Biology, Vol. 184, No. 5, 721-736
The Rockefeller University Press, 0021-9525 $30.00
© Rollason et al.
A CD317/tetherin–RICH2 complex plays a critical role in the organization of the subapical actin cytoskeleton in polarized epithelial cells
Ruth Rollason,
Viktor Korolchuk,
Clare Hamilton,
Mark Jepson, and
George Banting
Department of Biochemistry, University of Bristol, Bristol BS8 1TD, England, UK
Correspondence to George Banting: g.banting{at}bristol.ac.uk
CD317/tetherin is a lipid raft–associated integral membrane protein with a novel topology. It has a short N-terminal cytosolic domain, a conventional transmembrane domain, and a C-terminal glycosyl-phosphatidylinositol anchor. We now show that CD317 is expressed at the apical surface of polarized epithelial cells, where it interacts indirectly with the underlying actin cytoskeleton. CD317 is linked to the apical actin network via the proteins RICH2, EBP50, and ezrin. Knocking down expression of either CD317 or RICH2 gives rise to the same phenotype: a loss of the apical actin network with concomitant loss of apical microvilli, an increase in actin bundles at the basal surface, and a reduction in cell height without any loss of tight junctions, transepithelial resistance, or the polarized targeting of apical and basolateral membrane proteins. Thus, CD317 provides a physical link between lipid rafts and the apical actin network in polarized epithelial cells and is crucial for the maintenance of microvilli in such cells.
Abbreviations used in this paper: BAR, Bin/amphiphysin/Rvs; ERM, ezrin-radixin-moesin; GAP, GTPase-activating protein; GPI, glycosyl-phosphatidylinositol; LB, Luria Bertani; MLC, myosin light chain; PDZ, PSD-95/DlgA/ZO-1 like; ROCK, Rho kinase; SEM, scanning EM.
© 2009 Rollason et al.
This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

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