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Updated: Aug 9, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
TSC1/TSC2 and Rheb have different effects on TORC1 and TORC2 activity
Qian Yang1, Ken Inoki, Eunjung Kim
1Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
The Ras homology enriched in brain (Rheb) small GTPase inhibits TORC2 activity, potentially via a feedback loop involving TORC1 and S6K. Tuberous sclerosis complex 1/2 (TSC1/2) also differentially affects TORC1 and TORC2.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- The Target of Rapamycin (TOR) pathway is crucial for cell growth, integrating various signals.
- TOR exists in two complexes, TORC1 and TORC2, with distinct functions.
- Rheb is a known activator of TORC1, but its role in TORC2 regulation is unclear.
Purpose of the Study:
- To investigate the function of Rheb in TORC2 regulation.
- To elucidate the relationship between Rheb, TSC1/2, and the activities of TORC1 and TORC2.
Main Methods:
- Utilized Akt and S6K phosphorylation as functional assays for TORC1 and TORC2 activity.
- Conducted experiments in Drosophila S2 and human embryonic kidney 293 cells.
Main Results:
- dRheb demonstrated an inhibitory effect on dTORC2 activity in Drosophila S2 cells.
- Rheb did not activate TORC2 in human cells, though it stimulated TORC1.
- TSC1 and TSC2 exhibited opposing effects on TORC1 and TORC2 activity.
Conclusions:
- Rheb negatively regulates TORC2, possibly through a feedback mechanism involving TORC1 and S6K.
- TSC1/2 and Rheb display differential regulation of TORC1 and TORC2, highlighting pathway complexity.
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