Inhibition of small G proteins of the Rho family by statins orClostridium difficiletoxin B enhances cytokine-mediated induction of NO synthase II

6533b856fe1ef96bd12b269f

RESEARCH PRODUCT

Inhibition of small G proteins of the Rho family by statins orClostridium difficiletoxin B enhances cytokine-mediated induction of NO synthase II

Hartmut Kleinert Christian Von Eichel-streiber Andrea Witteck Ulrich Förstermann Fernando Rodríguez-pascual Michael Hausding

subject

rho GTP-Binding Proteins G protein Bacterial Toxins Mevalonic Acid Nitric Oxide Synthase Type II Small G Protein Clostridium difficile toxin B Biology Gene Expression Regulation Enzymologic Mice Geranylgeranylation Bacterial Proteins Polyisoprenyl Phosphates Prenylation GTP-Binding Proteins Gene expression Atorvastatin Tumor Cells Cultured Animals Humans Drug Interactions Pyrroles Lovastatin Promoter Regions Genetic Pharmacology 3T3 Cells Transfection Molecular biology Heptanoic Acids Enzyme Induction Papers Cytokines Hydroxymethylglutaryl-CoA Reductase Inhibitors Nitric Oxide Synthase Signal transduction

description

In order to investigate the involvement of Ras and/or Rho proteins in the induction of the inducible isoform of nitric oxide synthase (NOS II) we used HMG-CoA reductase inhibitors (statins) and Clostridium difficile toxin B (TcdB) as pharmacological tools. Statins indirectly inhibit small G proteins by preventing their essential farnesylation (Ras) and/or geranylgeranylation (Rho). In contrast, TcdB is a glucosyltransferase and inactivates Rho-proteins directly. Human A549/8- and DLD-1 cells as well as murine 3T3 fibroblasts were preincubated for 18 h with statins (1–100 μM) or TcdB (0.01–10 ng ml−1). Then NOS II expression was induced by cytokines. NOS II mRNA was measured after 4–8 h by RNase protection assay, and NO production were measured by the Griess assay after 24 h. Statins and TcdB markedly increased cytokine-induced NOS II mRNA expression and NO production. Statin-mediated enhancement of NOS II mRNA expression was reversed almost completely by cotreatment with mevalonate or geranylgeranylpyrophosphate. It was only slightly reduced by farnesylpyrophosphate. Therefore, small G proteins of the Rho family are likely to be involved in NOS II induction. In A549/8 cells stably transfected with a luciferase reporter gene under the control of a 16 kb fragment of the human NOS II promoter (pNOS2(16)Luc), statins produced only a small increase in cytokine-induced NOS II promoter activity. In contrast, statins had a considerable superinducing effect in DLD-1 cells stably transfected with pNOS2(16)Luc. In conclusion, our studies provide evidence that statins and TcdB potentiate cytokine-induced NOS II expression via inhibition of small G proteins of the Rho family. This in turn results in an enhanced NOS II promoter activity and/or a prolonged NOS II mRNA stability. British Journal of Pharmacology (2000) 131, 553–561; doi:10.1038/sj.bjp.0703607

year	journal	country	edition	language
2000-10-01	British Journal of Pharmacology

https://doi.org/10.1038/sj.bjp.0703607