title: Disruption of the vacuolar-type H+-ATPase complex in liver causes MTORC1-independent accumulation of autophagic vacuoles and lysosomes.
abstract: The vacuolar-type H+-translocating ATPase (v-H+-ATPase) has been implicated in the amino acid-dependent activation of the mechanistic target of rapamycin complex 1 (MTORC1), an important regulator of macroautophagy. To reveal the mechanistic links between the v-H+-ATPase and MTORC1, we destablilized v-H+-ATPase complexes in mouse liver cells by induced deletion of the essential chaperone ATP6AP2. ATP6AP2-mutants are characterized by massive accumulation of endocytic and autophagic vacuoles in hepatocytes. This cellular phenotype was not caused by a block in endocytic maturation or an impaired acidification. However, the degradation of LC3-II in the knockout hepatocytes appeared to be reduced. When v-H+-ATPase levels were decreased, we observed lysosome association of MTOR and normal signaling of MTORC1 despite an increase in autophagic marker proteins. To better understand why MTORC1 can be active when v-H+-ATPase is depleted, the activation of MTORC1 was analyzed in ATP6AP2-deficient fibroblasts. In these cells, very little amino acid-elicited activation of MTORC1 was observed. In contrast, insulin did induce MTORC1 activation, which still required intracellular amino acid stores. These results suggest that in vivo the regulation of macroautophagy depends not only on v-H+-ATPase-mediated regulation of MTORC1.
authors.affiliation: a Institut für Biochemie, Christian-Albrechts-Universität zu Kiel , Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Kissing
authors.affiliation: a Institut für Biochemie, Christian-Albrechts-Universität zu Kiel , Germany.
authors.forename: Sönke
authors.initials: S
authors.lastname: Rudnik
authors.affiliation: a Institut für Biochemie, Christian-Albrechts-Universität zu Kiel , Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Damme
authors.affiliation: b Anatomisches Institut, Christian-Albrechts-Universität zu Kiel , Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Lüllmann-Rauch
authors.affiliation: c Department of Medicine II , Tokyo Women´s Medical University , Japan.
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Ichihara
authors.affiliation: d Institut für Medizinische Genetik und Humangenetik, Charité-Universitaetsmedizin , Berlin , Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Kornak
authors.affiliation: e Department of Biosciences , Division of Biochemistry and Biotechnology, University of Helsinki , Finland.
authors.forename: Eeva-Liisa
authors.initials: EL
authors.lastname: Eskelinen
authors.affiliation: f Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC) , Berlin , Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Jabs
authors.affiliation: g Institut für Biochemie und Molekulare Zellbiologie, Zentrum für Experimentelle Medizin, Universitätsklinikum Hamburg-Eppendorf , Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Heeren
authors.affiliation: h Department of Biochemistry , University of Texas Southwestern Medical Center , Dallas , TX , USA.
authors.forename: Jef K
authors.initials: JK
authors.lastname: De Brabander
authors.affiliation: i Institut für Zellbiologie, Friedrich-Wilhelms Universität Bonn , Germany.
authors.forename: Albert
authors.initials: A
authors.lastname: Haas
authors.affiliation: a Institut für Biochemie, Christian-Albrechts-Universität zu Kiel , Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Saftig
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology; D007328:Insulin / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism*; D000076222:Mechanistic Target of Rapamycin Complex 1 / Q000378:metabolism*; D018345:Mice, Knockout; D006180:Proton-Translocating ATPases / Q000172:deficiency / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000378:metabolism*; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology*; D000093342:Prorenin Receptor
chemical_list: D000596:Amino Acids; D007328:Insulin; D000076222:Mechanistic Target of Rapamycin Complex 1; D006180:Proton-Translocating ATPases; D011956:Receptors, Cell Surface; C583530:ATP6AP2 protein, mouse; D000093342:Prorenin Receptor
keywords: ATP6AP2; MTORC1; autophagy; lysosome; ribosomal protein S6 kinase; transcription factor EB; v-H+-ATPase complex