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Lovastatin induces VSMC differentiation through inhibition of Rheb and mTOR

Robert J Wagner1, Kathleen A Martin, Richard J Powell

  • 1Section of Vascular Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.

American Journal of Physiology. Cell Physiology
|April 9, 2010
PubMed

Insights

Lovastatin promotes cardiovascular health by inhibiting Rheb and mTORC1 signaling, leading to vascular smooth muscle cell (VSMC) differentiation. This mechanism enhances the cardioprotective effects of statins beyond cholesterol reduction.

Area of Science:

  • Cardiovascular Biology
  • Molecular Pharmacology
  • Cellular Signaling

Background:

  • Cholesterol-independent effects of statins contribute to cardioprotection, but mechanisms are unclear.
  • Mammalian target of rapamycin complex 1 (mTORC1) inhibition induces vascular smooth muscle cell (VSMC) differentiation.
  • Statins' effects on VSMC phenotype warrant investigation.

Purpose of the Study:

  • To investigate the effects of lovastatin on vascular smooth muscle cell (VSMC) phenotype.
  • To elucidate the role of mammalian target of rapamycin complex 1 (mTORC1) signaling in lovastatin-induced VSMC differentiation.
  • To identify upstream regulators of mTORC1 involved in lovastatin's actions.

Main Methods:

  • Investigated lovastatin's impact on VSMC phenotype and mTORC1 signaling.
  • Utilized Rheb overexpression and knockdown (small interfering RNA) to assess its role in mTORC1 regulation.
  • Examined mTORC1 activity and contractile protein expression in patient-derived cells and an ex vivo angioplasty model.

Main Results:

  • Lovastatin inhibits mTORC1 signaling, which is essential for VSMC differentiation.
  • Lovastatin's mTORC1 inhibition is dependent on farnesylation, implicating the G protein Rheb.
  • Rheb activity inversely correlates with contractile protein expression; Rheb knockdown mimics lovastatin's effects.
  • Elevated mTORC1 activity in intimal hyperplasia lesions was reduced by lovastatin treatment.
  • Lovastatin inhibited mTORC1 and preserved contractile proteins in an ex vivo angioplasty model.

Conclusions:

  • Lovastatin promotes a differentiated VSMC phenotype through Rheb and mTORC1 inhibition.
  • This mechanism contributes to the cardioprotective effects of statins, independent of cholesterol.
  • Targeting Rheb-mTORC1 signaling offers a potential therapeutic strategy for vascular diseases.

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