title: Dynein mediates the localization and activation of mTOR in normal and human cytomegalovirus-infected cells.
abstract: Activation of stress signaling pathways normally leads to inhibition of the mammalian target of rapamycin complex 1 (mTORC1); however, human cytomegalovirus (HCMV) infection maintains mTORC1 activity in the presence of numerous types of stress. We previously demonstrated that HCMV infection maintains mTORC1 activity during amino acid deprivation through a Ras-related GTP-binding (Rag) protein-independent mechanism. This depends on the colocalization of mTOR and its activator, Rheb (Ras homology enriched in brain)-GTP, to a perinuclear position that corresponds to the viral cytoplasmic assembly compartment (AC). The data presented here show that the HCMV-induced, amino acid depletion-resistant perinuclear localization and activation of mTORC1 occurs as early as 8 h post-infection, prior to AC formation. We show that the molecular motor dynein is required for perinuclear localization of mTORC1 in both uninfected and HCMV-infected cells. Association between dynein and mTOR is shown by coimmunoprecipitation, and inhibition of dynein function using RNAi or the small molecule inhibitor ciliobrevin A inhibits mTORC1 activity in both uninfected and HCMV-infected cells. The data suggest that mTORC1 activation requires dynein-dependent transport to a position in the cell where it can be activated. Thus, the HCMV commandeers a cellular dynein-dependent mTORC1 activation mechanism to maintain stress-resistant mTORC1 activity during infection and to form the AC.
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Clippinger
authors.forename: James C
authors.initials: JC
authors.lastname: Alwine
mesh_terms: D000596:Amino Acids / Q000172:deficiency / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003586:Cytomegalovirus Infections / Q000503:physiopathology*; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D047468:Immunoprecipitation; D021381:Protein Transport; D034622:RNA Interference; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D000596:Amino Acids; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D004398:Dyneins