title: Interaction of the HOPS complex with Syntaxin 17 mediates autophagosome clearance in Drosophila.
abstract: Homotypic fusion and vacuole protein sorting (HOPS) is a tethering complex required for trafficking to the vacuole/lysosome in yeast. Specific interaction of HOPS with certain SNARE (soluble NSF attachment protein receptor) proteins ensures the fusion of appropriate vesicles. HOPS function is less well characterized in metazoans. We show that all six HOPS subunits (Vps11 [vacuolar protein sorting 11]/CG32350, Vps18/Dor, Vps16A, Vps33A/Car, Vps39/CG7146, and Vps41/Lt) are required for fusion of autophagosomes with lysosomes in Drosophila. Loss of these genes results in large-scale accumulation of autophagosomes and blocks autophagic degradation under basal, starvation-induced, and developmental conditions. We find that HOPS colocalizes and interacts with Syntaxin 17 (Syx17), the recently identified autophagosomal SNARE required for fusion in Drosophila and mammals, suggesting their association is critical during tethering and fusion of autophagosomes with lysosomes. HOPS, but not Syx17, is also required for endocytic down-regulation of Notch and Boss in developing eyes and for proper trafficking to lysosomes and eye pigment granules. We also show that the formation of autophagosomes and their fusion with lysosomes is largely unaffected in null mutants of Vps38/UVRAG (UV radiation resistance associated), a suggested binding partner of HOPS in mammals, while endocytic breakdown and lysosome biogenesis is perturbed. Our results establish the role of HOPS and its likely mechanism of action during autophagy in metazoans.
authors.affiliation: Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pazmany s. 1/C, H-1117 Budapest, Hungary Department of Neuroscience, Department of Cell Biology, University of Texas Southwestern Medical School, Dallas, TX 75390-9111.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Takáts
authors.forename: Karolina
authors.initials: K
authors.lastname: Pircs
authors.forename: Péter
authors.initials: P
authors.lastname: Nagy
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Varga
authors.forename: Manuéla
authors.initials: M
authors.lastname: Kárpáti
authors.forename: Krisztina
authors.initials: K
authors.lastname: Hegedűs
authors.forename: Helmut
authors.initials: H
authors.lastname: Kramer
authors.forename: Attila L
authors.initials: AL
authors.lastname: Kovács
authors.forename: Miklós
authors.initials: M
authors.lastname: Sass
authors.forename: Gábor
authors.initials: G
authors.lastname: Juhász
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology; D002460:Cell Line; D015536:Down-Regulation; D004330:Drosophila; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000196:embryology; D005136:Eye Proteins / Q000096:biosynthesis; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008561:Membrane Fusion; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D009154:Mutation; D010588:Phagosomes / Q000378:metabolism*; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D050765:Qa-SNARE Proteins / Q000378:metabolism*; D050683:R-SNARE Proteins / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering; D051880:Receptors, Notch / Q000096:biosynthesis; D018000:Receptors, Peptide / Q000096:biosynthesis; D025521:Tumor Suppressor Proteins / Q000235:genetics; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C527373:Atg8a protein, Drosophila; D029721:Drosophila Proteins; D005136:Eye Proteins; D052118:Lysosomal-Associated Membrane Protein 1; D008562:Membrane Glycoproteins; C497759:N protein, Drosophila; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D034741:RNA, Small Interfering; D051880:Receptors, Notch; D018000:Receptors, Peptide; D025521:Tumor Suppressor Proteins; C561319:UVRAG protein, Drosophila; C582207:VAMP7 protein, Drosophila; C507251:VPS16A protein, Drosophila; D033921:Vesicular Transport Proteins; C072141:boss protein, Drosophila