Inhibition of geranylgeranyltransferase I decreases generation of vascular reactive oxygen species and increases vascular nitric oxide production.
BACKGROUND
Vascular injury with endothelial dysfunction results in an imbalance between the production of vasoprotective molecules such as nitric oxide (NO) and deleterious reactive oxygen species (ROS). The purpose of this work was to test the hypothesis that inhibition of geranylgeranyltransferase I (GG Tase I) reduces vascular injury by increasing vascular NO production while decreasing ROS generation.


RESULTS
GGTI-298 decreased the formation of intimal hyperplasia at 14 days following balloon injury. GGTI-298 (10 microm) inhibited activation of RhoA and Rac1 as well as inhibited SMC proliferation. GGTI increased SMC-inducible NO synthase (iNOS) levels and NO production in vitro. Additionally, the activation of NAD(P)H oxidase subunits was decreased by GGTI in vitro. This correlated with a decrease in TNF-alpha- or angiotensin-II-induced ROS production assayed by DCF fluorescence. In vivo, GGTI treatment increased endothelial NOS (eNOS) expression in uninjured arteries and iNOS expression in balloon-injured arteries. Furthermore, GGTI treatment attenuated balloon-injury-induced superoxide generation assayed by MCLA luminescence.


CONCLUSIONS
GGTI decreases the production of ROS and increases the production of NO both in vitro and in vivo. These effects may be mediated via the inhibition of activation of the small GTPases Rac1 and RhoA. Pharmacological inhibition of GGTase I may prove to be a useful clinical adjunct in the treatment of cardiovascular diseases.
Zuckerbraun
Brian S
BS
Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA. zuckerbraunbs@msx.upmc.edu
Barbato
Joel E
JE
Hamilton
Andrew
A
Sebti
Said
S
Tzeng
Edith
E
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000800:Angioplasty, Balloon / Q000009:adverse effects; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000293:injuries; D001549:Benzamides / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D019255:NADPH Oxidases / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010750:Phosphoproteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D017539:Tunica Intima / Q000201:enzymology / Q000293:injuries; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D001549:Benzamides; C493958:Cdkn1a protein, rat; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; C102521:GGTI 298; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D025521:Tumor Suppressor Proteins; C079789:neutrophil cytosol factor 67K; D050760:Cyclin-Dependent Kinase Inhibitor p27; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D019883:Alkyl and Aryl Transferases; C083291:geranylgeranyltransferase type-I; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein