title: Inhibition of protein geranylgeranylation and RhoA/RhoA kinase pathway induces apoptosis in human endothelial cells.
abstract: Geranylgeranylation of RhoA small G-protein is essential for its localization to cell membranes and for its biological functions. Many RhoA effects are mediated by its downstream effector RhoA kinase. The role of protein geranylgeranylation and the RhoA pathway in the regulation of endothelial cell survival has not been elucidated. The hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor lovastatin depletes cellular pools of geranylgeranyl pyrophosphate and farnesol pyrophosphate and thereby inhibits both geranylgeranylation and farnesylation. Human umbilical vein endothelial cells (HUVECs) were exposed to lovastatin (3 microm-30 microm) for 48 h, and cell death was quantitatively determined by cytoplasmic histone-associated DNA fragments as well as caspase-3 activity. The assays showed that lovastatin caused a dose-dependent endothelial cell death. The addition of geranylgeraniol, which restores geranylgeranylation, rescued HUVEC from apoptosis. The geranylgeranyltransferase inhibitor GGTI-298, but not the farnesyltransferase inhibitor FTI-277, induced apoptosis in HUVEC. Cell death was also induced by a blockade of RhoA function by exoenzyme C3. In addition, treatment of HUVEC with the RhoA kinase inhibitors Y-27632 and HA-1077 caused dose-dependent cell death. Y-27632 did not inhibit other well known survival pathways, such as NF-kappa B, ERK, and phosphatidylinositol 3-kinase/Akt. However, there was an increase in p53 protein level concomitant with Y-27632-induced cell death. Unlike the apoptosis induced by TNF-alpha, which occurs only with inhibition of new protein synthesis, apoptosis induced by inhibitors of HMG-CoA reductase, geranylgeranyltransferase, or RhoA kinase was blocked by cycloheximide. Our data indicate that inhibition of protein geranylgeranylation and RhoA pathways induce apoptosis in HUVEC and that induction of p53 or other proapoptotic proteins is required for this process.
authors.affiliation: Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Xianwu
authors.initials: X
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Joan C
authors.initials: JC
authors.lastname: Tupper
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Bannerman
authors.forename: Robert K
authors.initials: RK
authors.lastname: Winn
authors.forename: Said M
authors.initials: SM
authors.lastname: Sebti
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hamilton
authors.forename: John M
authors.initials: JM
authors.lastname: Harlan
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001549:Benzamides / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004224:Diterpenes / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008148:Lovastatin / Q000494:pharmacology*; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011106:Polyisoprenyl Phosphates; D017368:Protein Prenylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014471:Umbilical Veins; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D001549:Benzamides; D004224:Diterpenes; D004791:Enzyme Inhibitors; C096856:FTI 277; C102521:GGTI 298; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D011106:Polyisoprenyl Phosphates; D008148:Lovastatin; D008715:Methionine; C017338:geranylgeraniol; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D020742:rhoA GTP-Binding Protein; C002963:geranylgeranyl pyrophosphate