title: WASH is required for lysosomal recycling and efficient autophagic and phagocytic digestion.
abstract: Wiskott-Aldrich syndrome protein and SCAR homologue (WASH) is an important regulator of vesicle trafficking. By generating actin on the surface of intracellular vesicles, WASH is able to directly regulate endosomal sorting and maturation. We report that, in Dictyostelium, WASH is also required for the lysosomal digestion of both phagocytic and autophagic cargo. Consequently, Dictyostelium cells lacking WASH are unable to grow on many bacteria or to digest their own cytoplasm to survive starvation. WASH is required for efficient phagosomal proteolysis, and proteomic analysis demonstrates that this is due to reduced delivery of lysosomal hydrolases. Both protease and lipase delivery are disrupted, and lipid catabolism is also perturbed. Starvation-induced autophagy therefore leads to phospholipid accumulation within WASH-null lysosomes. This causes the formation of multilamellar bodies typical of many lysosomal storage diseases. Mechanistically, we show that, in cells lacking WASH, cathepsin D becomes trapped in a late endosomal compartment, unable to be recycled to nascent phagosomes and autophagosomes. WASH is therefore required for the maturation of lysosomes to a stage at which hydrolases can be retrieved and reused.
authors.affiliation: Beatson Institute for Cancer Research, Bearsden, Glasgow G61 1BD, United Kingdom.
authors.forename: Jason S
authors.initials: JS
authors.lastname: King
authors.forename: Aurélie
authors.initials: A
authors.lastname: Gueho
authors.forename: Monica
authors.initials: M
authors.lastname: Hagedorn
authors.forename: Navin
authors.initials: N
authors.lastname: Gopaldass
authors.forename: Florence
authors.initials: F
authors.lastname: Leuba
authors.forename: Thierry
authors.initials: T
authors.lastname: Soldati
authors.forename: Robert H
authors.initials: RH
authors.lastname: Insall
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D001343:Autophagy; D002402:Cathepsin D / Q000378:metabolism; D004023:Dictyostelium / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D010587:Phagocytosis; D010588:Phagosomes / Q000502:physiology; D021381:Protein Transport; D040901:Proteomics; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D008840:Microfilament Proteins; D015800:Protozoan Proteins; D033921:Vesicular Transport Proteins; D001619:beta-N-Acetylhexosaminidases; D002402:Cathepsin D