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

Genes Dev. 2012 Sep 15;26(18):2015-26. doi: 10.1101/gad.196147.112.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acids / deficiency
  • Amino Acids / metabolism
  • Cell Line, Tumor
  • Cells, Cultured
  • Cytomegalovirus Infections / physiopathology*
  • Dyneins / genetics
  • Dyneins / metabolism*
  • Enzyme Activation
  • Humans
  • Immunoprecipitation
  • Protein Transport
  • RNA Interference
  • TOR Serine-Threonine Kinases / metabolism*

Substances

  • Amino Acids
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Dyneins