Caenorhabditis elegans screen reveals role of PAR-5 in RAB-11-recycling endosome positioning and api

Abstract

Apically enriched Rab11-positive recycling endosomes (Rab11-REs) are important for establishing and maintaining epithelial polarity. Yet, little is known about the molecules controlling trafficking of Rab11-REs in an epithelium in vivo. Here, we report a genome-wide, image-based RNA interference screen for regulators of Rab11-RE positioning and transport of an apical membrane protein (PEPT-1) in C. elegans intestine. Among the 356 screen hits was the 14-3-3 and partitioning defective protein PAR-5, which we found to be specifically required for Rab11-RE positioning and apicobasal polarity maintenance. Depletion of PAR-5 induced abnormal clustering of Rab11-REs to ectopic sites at the basolateral cortex containing F-actin and other apical domain components. This phenotype required key regulators of F-actin dynamics and polarity, such as Rho GTPases (RHO-1 and the Rac1 orthologue CED-10) and apical PAR proteins. Our data suggest that PAR-5 acts as a regulatory hub for a polarity-maintaining network required for apicobasal asymmetry of F-actin and proper Rab11-RE positioning. RAB-11-positive recycling endosomes participate in the establishment and maintenance of epithelial polarity. Zerial and colleagues carry out an in vivo image-based RNAi screen for factors that regulate recycling endosome positioning in Caenorhabditis elegans. They identify, among other candidates, PAR-5 as a key determinant of recycling endosome positioning and, thus, apicobasal polarity.

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Winter, J., Höpfner, S., Korn, K. et al. Caenorhabditis elegans screen reveals role of PAR-5 in RAB-11-recycling endosome positioning and apicobasal cell polarity. Nat Cell Biol 14, 666–676 (2012). https://doi.org/10.1038/ncb2508

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