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The TSC1-TSC2 complex is required for proper activation of mTOR complex 2
Jingxiang Huang1, Christian C Dibble, Mika Matsuzaki
1Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
Molecular and Cellular Biology
|April 16, 2008
Summary
The TSC1-TSC2 complex inhibits mTORC1 but activates mTORC2, impacting Akt activation. This complex physically associates with mTORC2, revealing a novel regulatory mechanism for cell signaling pathways.
Area of Science:
- Cellular signaling
- Molecular biology
- Biochemistry
Background:
- The mammalian target of rapamycin (mTOR) pathway regulates cell growth and metabolism through two complexes: mTORC1 and mTORC2.
- mTORC1 is inhibited by the TSC1-TSC2 complex, but mTORC2 regulation remains unclear.
Purpose of the Study:
- To investigate the role of the TSC1-TSC2 complex in regulating mTORC2 activity.
- To elucidate the mechanisms by which TSC1-TSC2 affects mTORC2 function.
Main Methods:
- Analysis of mTORC2 kinase activity in cells lacking functional TSC1-TSC2.
- Separation of mTORC2 defects from mTORC1 signaling and feedback mechanisms.
- Investigation of TSC1-TSC2 association with mTOR complexes.
Main Results:
- mTORC2 kinase activity toward Akt is impaired in cells lacking TSC1-TSC2.
- TSC1-TSC2 positively regulates mTORC2 independently of its Rheb GTPase-activating protein activity.
- TSC1-TSC2 physically associates with mTORC2, but not mTORC1.
Conclusions:
- The TSC1-TSC2 complex differentially regulates mTORC1 and mTORC2.
- TSC1-TSC2 activates mTORC2, promoting Akt activation through a novel mechanism.
- These findings reveal a dual role for TSC1-TSC2 in nutrient and growth factor signaling.
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