Inhibition of small G proteins of the Rho family by statins or Clostridium difficile toxin B enhances cytokine‐mediated induction of NO synthase II
- 1 October 2000
- journal article
- Published by Wiley in British Journal of Pharmacology
- Vol. 131 (3), 553-561
- https://doi.org/10.1038/sj.bjp.0703607
Abstract
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 microM) 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.Keywords
This publication has 35 references indexed in Scilit:
- Platelet-derived growth factor and fibroblast growth factor differentially regulate interleukin 1beta- and cAMP-induced nitric oxide synthase expression in rat renal mesangial cells.JCI Insight, 1997
- Inhibition of Protein Geranylgeranylation Causes a Superinduction of Nitric-oxide Synthase-2 by Interleukin-1β in Vascular Smooth Muscle CellsPublished by Elsevier BV ,1997
- NITRIC OXIDE AND MACROPHAGE FUNCTIONAnnual Review of Immunology, 1997
- THE POTENTIAL OF FARNESYLTRANSFERASE INHIBITORS AS CANCER CHEMOTHERAPEUTICSAnnual Review of Pharmacology and Toxicology, 1997
- Regulation of Phosphorylation Pathways by p21 GTPasesJBIC Journal of Biological Inorganic Chemistry, 1996
- Large clostridial cytotoxins — a family of glycosyltransferases modifying small GTP-binding proteinsTrends in Microbiology, 1996
- Closing in on the toxic domain through analysis of a variant Clostridium difficile cytotoxin BMolecular Microbiology, 1995
- Nitric oxide synthases: Roles, tolls, and controlsCell, 1994
- ?Macrophage? nitric oxide synthase is a glucocorticoid-inhibitable primary response gene in 3T3 cellsJournal of Cellular Physiology, 1993
- Single-Step Method of RNA Isolation by Acid Guanidinium Thiocyanate–Phenol–Chloroform ExtractionAnalytical Biochemistry, 1987