Purchase this article with an account.
C. L. von Zee, E. B. Stubbs, Jr.; Geranylgeranylation Limits Rho G-Protein Expression in Human Trabecular Meshwork Cells. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4874.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Statin-dependent changes in Rho G-protein function disrupt cytoskeletal organization in trabecular meshwork (TM) cells, leading to reduced aqueous humor outflow. The purpose of this study was to determine the mechanism by which statins alter Rho mRNA and protein expression in human TM cells.
SV40-transformed TM cells from a male glaucomatous patient were cultured for 24h in the presence of vehicle (0.01% ethanol) or chemically activated lovastatin (10 µM). Rho mRNA or protein expression was determined by qRT-PCR or Western blotting, respectively. In some experiments, isoprenoid pyrophosphate intermediates or inhibitors of isoprenoid transferases were used to determine mechanism of action.
Lovastatin, as compared to vehicle controls, elicited significant (p<0.05) increases in RhoA (2-fold) and RhoB (36-fold) mRNA expression. Supplementation of culture media with geranylgeranyl pyrophosphate (GGPP, 10 µM), but not farnesyl pyrophosphate (FPP, 10 µM), prevented lovastatin increases in Rho mRNA expression. Inhibition of geranylgeranyl transferase mimicked the effects of lovastatin on Rho mRNA content (p<0.01). Stability of RhoA and RhoB protein was increased in the presence of lovastatin, as compared to vehicle. Addition of GGPP, but not FPP, decreased Rho protein stability to levels similar to vehicle-treated controls.
Selective inhibition of Rho protein geranylgeranylation with lovastatin markedly increases de novo synthesis of Rho G-proteins in human TM cells. We postulate that post-translational geranylgeranylation facilitates Rho G-protein degradation while limiting Rho expression in human TM cells.
This PDF is available to Subscribers Only