title: Role for Rab7 in maturation of late autophagic vacuoles.
abstract: The small GTP binding protein Rab7 has a role in the late endocytic pathway and lysosome biogenesis. The role of mammalian Rab7 in autophagy is, however, unknown. We have addressed this by inhibiting Rab7 function with RNA interference and overexpression of dominant negative Rab7. We show here that Rab7 was needed for the formation of preferably perinuclear, large aggregates, where the autophagosome marker LC3 colocalised with Rab7 and late endosomal and lysosomal markers. By electron microscopy we showed that these large aggregates corresponded to autophagic vacuoles surrounding late endosomal or lysosomal vesicles. Our experiments with quantitative electron microscopy showed that Rab7 was not needed for the initial maturation of early autophagosomes to late autophagic vacuoles, but that it participated in the final maturation of late autophagic vacuoles. Finally, we showed that the recruitment of Rab7 to autophagic vacuoles was retarded in cells deficient in the lysosomal membrane proteins Lamp1 and Lamp2, which we have recently shown to accumulate late autophagic vacuoles during starvation. In conclusion, our results showed a role for Rab7 in the final maturation of late autophagic vacuoles.
authors.affiliation: Institute of Biochemistry, University of Kiel, Olshausenstr. 40, 24098 Kiel, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Jäger
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bucci
authors.forename: Isei
authors.initials: I
authors.lastname: Tanida
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueno
authors.forename: Eiki
authors.initials: E
authors.lastname: Kominami
authors.forename: Paul
authors.initials: P
authors.lastname: Saftig
authors.forename: Eeva-Liisa
authors.initials: EL
authors.lastname: Eskelinen
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D001343:Autophagy; D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D050178:Monoglycerides; D034622:RNA Interference; D011993:Recombinant Fusion Proteins; D014617:Vacuoles / Q000378:metabolism* / Q000648:ultrastructure; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; C489116:LAMP1 protein, human; C497811:LAMP2 protein, human; D008246:Lysophospholipids; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D050178:Monoglycerides; D011993:Recombinant Fusion Proteins; C012786:bis(monoacylglyceryl)phosphate; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; C000716465:rab7 GTP-binding proteins, mouse; D020691:rab GTP-Binding Proteins