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Rheb activates AMPK and reduces p27Kip1 levels in Tsc2-null cells via mTORC1-independent mechanisms: implications for

M D Lacher1, R Pincheira, Z Zhu

  • 1Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA, USA.

Oncogene
|September 7, 2010
PubMed

Insights

Tuberous sclerosis complex (TSC) and LAM involve the TSC2 gene. This study shows Rheb protein activates AMPK and reduces p27, inhibiting cell proliferation and tumor growth in TSC2-deficient cells, suggesting Rheb as a therapeutic target.

Area of Science:

  • Cell Biology
  • Genetics
  • Oncology

Background:

  • Tuberous sclerosis complex (TSC) and lymphangioleiomyomatosis (LAM) are linked to TSC2 gene mutations.
  • TSC2 deficiency disrupts Rheb GTPase regulation and mTORC1 signaling.
  • TSC2 deficiency is associated with elevated AMPK and altered p27Kip1 (p27) localization.

Purpose of the Study:

  • To investigate the role of Rheb in TSC2-deficient cells.
  • To elucidate the mechanism linking TSC2 deficiency, AMPK, and p27.
  • To explore Rheb as a potential therapeutic target for TSC and LAM.

Main Methods:

  • Studied Tsc2-null cells to assess Rheb's effects on AMPK and p27.
  • Investigated the relationship between Rheb, mTORC1, AMPK, and p27.
  • Evaluated the impact of Rheb modulation on cell proliferation and tumor formation in vitro and in vivo.

Main Results:

  • Rheb activates AMPK and reduces p27 levels in Tsc2-null cells, largely independent of mTORC1.
  • Rheb depletion increases p27 levels, decreasing Cdk2 activity and cell proliferation.
  • Inhibition of Rheb in Tsc2-null cells reduced tumor formation in vivo.

Conclusions:

  • Rheb controls proliferation in TSC2-deficient cells via AMPK and p27 regulation.
  • Rheb represents a potential therapeutic target for TSC and LAM.
  • The Rheb-AMPK-p27 axis offers new insights into TSC/LAM pathogenesis.

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