d-α-Tocopherol Inhibition of Vascular Smooth Muscle Cell Proliferation Occurs at Physiological Concentrations, Correlates with Protein Kinase C Inhibition, and is Independent of Its Antioxidant Properties
Abstract
d-alpha-Tocopherol, but not d-beta-tocopherol, negatively regulates proliferation of vascular smooth muscle cells at physiological concentrations. d-alpha-Tocopherol inhibits protein kinase C (PKC) activity, whereas d-beta-tocopherol is ineffective. Furthermore d-beta-tocopherol prevents the inhibition of cell growth and of PKC activity caused by d-alpha-tocopherol. The negative regulation by d-alpha-tocopherol of PKC activity appears to be the cause and not the effect of smooth muscle cell growth inhibition. d-alpha-Tocopherol does not act by binding to PKC directly but presumably by preventing PKC activation. It is concluded that, in vascular smooth muscle cells, d-alpha-tocopherol acts specifically through a nonantioxidant mechanism and exerts a negative control on a signal transduction pathway regulating cell proliferation.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- December 1995
- DOI:
- 10.1073/pnas.92.26.12190
- Bibcode:
- 1995PNAS...9212190T