Dynein mediates the localization and activation of mTOR in normal and human cytomegalovirus-infected cells

• Published in: Genes & development Vol. 26; no. 18; pp. 2015 - 2026
• Main Authors: Clippinger, Amy J, Alwine, James C
• Format: Journal Article
• Language: English
• Published: United States Cold Spring Harbor Laboratory Press 15.09.2012
• Subjects: Amino Acids - deficiency; Amino Acids - metabolism; Cell Line, Tumor; Cells, Cultured; Cytomegalovirus Infections - physiopathology; Dyneins - genetics; Dyneins - metabolism; Enzyme Activation; Humans; Immunoprecipitation; Protein Transport; Research Paper; RNA Interference; TOR Serine-Threonine Kinases - metabolism
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.196147.112

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.