title: Regulated assembly of vacuolar ATPase is increased during cluster disruption-induced maturation of dendritic cells through a phosphatidylinositol 3-kinase/mTOR-dependent pathway.
abstract: The vacuolar (H(+))-ATPases (V-ATPases) are ATP-driven proton pumps composed of a peripheral V1 domain and a membrane-embedded V0 domain. Regulated assembly of V1 and V0 represents an important regulatory mechanism for controlling V-ATPase activity in vivo. Previous work has shown that V-ATPase assembly increases during maturation of bone marrow-derived dendritic cells induced by activation of Toll-like receptors. This increased assembly is essential for antigen processing, which is dependent upon an acidic lysosomal pH. Cluster disruption of dendritic cells induces a semi-mature phenotype associated with immune tolerance. Thus, semi-mature dendritic cells are able to process and present self-peptides to suppress autoimmune responses. We have investigated V-ATPase assembly in bone marrow-derived, murine dendritic cells and observed an increase in assembly following cluster disruption. This increased assembly is not dependent upon new protein synthesis and is associated with an increase in concanamycin A-sensitive proton transport in FITC-loaded lysosomes. Inhibition of phosphatidylinositol 3-kinase with wortmannin or mTORC1 with rapamycin effectively inhibits the increased assembly observed upon cluster disruption. These results suggest that the phosphatidylinositol 3-kinase/mTOR pathway is involved in controlling V-ATPase assembly during dendritic cell maturation.
authors.affiliation: From the Departments of Developmental, Molecular, and Chemical Biology.
authors.forename: Rachel
authors.initials: R
authors.lastname: Liberman
authors.forename: Sarah
authors.initials: S
authors.lastname: Bond
authors.forename: Mara G
authors.initials: MG
authors.lastname: Shainheit
authors.forename: Miguel J
authors.initials: MJ
authors.lastname: Stadecker
authors.forename: Michael
authors.initials: M
authors.lastname: Forgac
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000201:enzymology*; D003713:Dendritic Cells / Q000166:cytology / Q000201:enzymology*; D005260:Female; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008247:Lysosomes / Q000201:enzymology; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008807:Mice, Inbred BALB C; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D007166:Immunosuppressive Agents; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; D025262:Vacuolar Proton-Translocating ATPases; D000077191:Wortmannin; C546843:mTOR protein, mouse
keywords: ATPases; Dendritic Cells; Proton Pumps; Regulated V-ATPase Assembly; Transport; Vacuolar ATPase; Vacuolar Acidification