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Yang, Q., Inoki, K., Kim, E., Guan, K.L. (2006). TSC1/TSC2 and Rheb have different effects on TORC1 and TORC2 activity.  Proc. Natl. Acad. Sci. U.S.A. 103(18): 6811--6816.
FlyBase ID
FBrf0191466
Publication Type
Research paper
Abstract

Target of rapamycin (TOR) plays a central role in cell growth regulation by integrating signals from growth factors, nutrients, and cellular energy levels. TOR forms two distinct physical and functional complexes, termed TOR complex 1 (TORC1) and TOR complex 2 (TORC2). TORC1, which is sensitive to rapamycin, regulates translation and cell growth, whereas TORC2, which is insensitive to rapamycin, regulates cell morphology and cell growth. The Ras homology enriched in brain (Rheb) small GTPase is known to be a key upstream activator of TORC1, although the mechanism of Rheb in TORC1 activation remains to be determined. However, the function of Rheb in the TORC2 regulation has not been elucidated. By measuring Akt and S6K phosphorylation as a functional assay for TORC1 and -2, here, we report that dRheb has an inhibitory effect on dTORC2 activity in Drosophila S2 cells. This negative effect of dRheb on dTORC2 is possibly due to a feedback mechanism involving dTORC1 and dS6K. We also observed that Rheb does not activate TORC2 in human embryonic kidney 293 cells, although it potently stimulates TORC1. Furthermore, tuberous sclerosis complex 1 (TSC1) and TSC2, which are negative regulators of Rheb, have negative and positive effects on TORC1 and -2, respectively. Our observations suggest that TSC1/2 and Rheb have different effects on the activity of TORC1 and -2, further supporting the complexity of TOR regulation.

PubMed ID
PubMed Central ID
PMC1458976 (PMC) (EuropePMC)
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    Language of Publication
    English
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    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Proc. Natl. Acad. Sci. U.S.A.
    Title
    Proceedings of the National Academy of Sciences of the United States of America
    Publication Year
    1915-
    ISBN/ISSN
    0027-8424
    Data From Reference
    Gene Groups (1)
    Genes (12)