Location-specific inhibition of Akt reveals regulation of mTORC1 activity in the nucleus

Xin Zhou1, Yanghao Zhong1,2, Olivia Molinar-Inglis1, Maya T Kunkel1, Mingyuan Chen3, Tengqian Sun1, Jiao Zhang4, John Y-J Shyy4, JoAnn Trejo1, Alexandra C Newton1, Jin Zhang5,6,7

  1. Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
  2. Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA, USA.
  3. Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
  4. Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
  5. Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA. jzhang32@ucsd.edu.
  6. Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA. jzhang32@ucsd.edu.
  7. Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, CA, USA. jzhang32@ucsd.edu.

Abstract

The mechanistic target of rapamycin complex 1 (mTORC1) integrates growth, nutrient and energy status cues to control cell growth and metabolism. While mTORC1 activation at the lysosome is well characterized, it is not clear how this complex is regulated at other subcellular locations. Here, we combine location-selective kinase inhibition, live-cell imaging and biochemical assays to probe the regulation of growth factor-induced mTORC1 activity in the nucleus. Using a nuclear targeted Akt Substrate-based Tandem Occupancy Peptide Sponge (Akt-STOPS) that we developed for specific inhibition of Akt, a critical upstream kinase, we show that growth factor-stimulated nuclear mTORC1 activity requires nuclear Akt activity. Further mechanistic dissection suggests that nuclear Akt activity mediates growth factor-induced nuclear translocation of Raptor, a regulatory scaffolding component in mTORC1, and localization of Raptor to the nucleus results in nuclear mTORC1 activity in the absence of growth factor stimulation. Taken together, these results reveal a mode of regulation of mTORC1 that is distinct from its lysosomal activation, which controls mTORC1 activity in the nuclear compartment.

Presented By Xin Zhou | ORCID iD

Biochemistry, Cell & Developmental BioNicholas Liao2020-11 (Nov)