Abstract
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.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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AMP-Activated Protein Kinases
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Animals
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Antibiotics, Antineoplastic / pharmacology
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Antibiotics, Antineoplastic / therapeutic use
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Cell Line, Tumor
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Cell Proliferation*
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Cell Transformation, Neoplastic / drug effects
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Cell Transformation, Neoplastic / metabolism
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Glycogen Synthase Kinase 3 / metabolism*
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Humans
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Mammary Neoplasms, Experimental / drug therapy
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Mammary Neoplasms, Experimental / metabolism
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Mammary Neoplasms, Experimental / pathology
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Mice
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Multienzyme Complexes / metabolism*
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Mutation
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Phosphorylation
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Protein Kinases / metabolism
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Protein Serine-Threonine Kinases / metabolism*
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Signal Transduction*
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Sirolimus / pharmacology
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Sirolimus / therapeutic use
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TOR Serine-Threonine Kinases
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Transfection
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Tuberous Sclerosis Complex 2 Protein
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism*
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Wnt Proteins / genetics
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Wnt Proteins / metabolism*
Substances
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Antibiotics, Antineoplastic
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Multienzyme Complexes
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TSC2 protein, human
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Tsc2 protein, mouse
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Tuberous Sclerosis Complex 2 Protein
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Tumor Suppressor Proteins
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Wnt Proteins
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Protein Kinases
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MTOR protein, human
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mTOR protein, mouse
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Protein Serine-Threonine Kinases
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TOR Serine-Threonine Kinases
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Glycogen Synthase Kinase 3
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AMP-Activated Protein Kinases
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Sirolimus