Mroh1, a lysosomal regulator localized by WASH-generated actin

Thomason, P. A., King, J. S. and Insall, R. H. (2017) Mroh1, a lysosomal regulator localized by WASH-generated actin. Journal of Cell Science, 130(10), pp. 1785-1795. (doi: 10.1242/jcs.197210) (PMID:28424231) (PMCID:PMC5450189)

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The steps leading to constitutive exocytosis are poorly understood. In Dictyostelium WASH complex mutants, exocytosis is blocked, so cells that take up fluorescent dextran from the medium retain it and remain fluorescent. Here, we establish a FACS-based method to select cells that retain fluorescent dextran, allowing identification of mutants with disrupted exocytosis. Screening a pool of random mutants identified members of the WASH complex, as expected, and multiple mutants in the conserved HEAT-repeat-containing protein Mroh1. In mroh1 mutants, endosomes develop normally until the stage where lysosomes neutralize to postlysosomes, but thereafter the WASH complex is recycled inefficiently, and subsequent exocytosis is substantially delayed. Mroh1 protein localizes to lysosomes in mammalian and Dictyostelium cells. In Dictyostelium, it accumulates on lysosomes as they mature and is removed, together with the WASH complex, shortly before the postlysosomes are exocytosed. WASH-generated F-actin is required for correct subcellular localization; in WASH complex mutants, and immediately after latrunculin treatment, Mroh1 relocalizes from the cytoplasm to small vesicles. Thus, Mroh1 is involved in a late and hitherto undefined actin-dependent step in exocytosis.

Item Type:Articles
Additional Information:The work was funded by Cancer Research UK core support (A15672 to RHI).
Glasgow Author(s) Enlighten ID:King, Dr Jason and Thomason, Dr Peter and Insall, Professor Robert
Authors: Thomason, P. A., King, J. S., and Insall, R. H.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Journal Name:Journal of Cell Science
Publisher:Company of Biologists
ISSN (Online):1477-9137
Published Online:19 April 2017
Copyright Holders:Copyright © 2017 The Company of Biologists Ltd
First Published:First published in Journal of Cell Science 130(10): 1785-1795
Publisher Policy:Reproduced under a Creative Commons License

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