TSC2 integrates Wnt and energy signals via a coordinated phosphorylation by AMPK and GSK3 to regulate cell growth.

Mutation in the TSC2 tumor suppressor causes tuberous sclerosis complex, a disease characterized by hamartoma formation in multiple tissues. TSC2 inhibits cell growth by acting as a GTPase-activating protein toward Rheb, thereby inhibiting mTOR, a central controller of cell growth. Here, we show that Wnt activates mTOR via inhibiting GSK3 ...
without involving beta-catenin-dependent transcription. GSK3 inhibits the mTOR pathway by phosphorylating TSC2 in a manner dependent on AMPK-priming phosphorylation. Inhibition of mTOR by rapamycin blocks Wnt-induced cell growth and tumor development, suggesting a potential therapeutic value of rapamycin for cancers with activated Wnt signaling. Our results show that, in addition to transcriptional activation, Wnt stimulates translation and cell growth by activating the TSC-mTOR pathway. Furthermore, the sequential phosphorylation of TSC2 by AMPK and GSK3 reveals a molecular mechanism of signal integration in cell growth regulation.
Mesh Terms:
AMP-Activated Protein Kinases, Animals, Antibiotics, Antineoplastic, Cell Line, Tumor, Cell Proliferation, Cell Transformation, Neoplastic, Glycogen Synthase Kinase 3, Humans, Mammary Neoplasms, Experimental, Mice, Multienzyme Complexes, Mutation, Phosphorylation, Protein Kinases, Protein-Serine-Threonine Kinases, Signal Transduction, Sirolimus, Transfection, Tumor Suppressor Proteins, Wnt Proteins
Cell
Date: Sep. 08, 2006
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