Inhibition of small G proteins of the Rho family by statins or Clostridium difficile toxin B enhances cytokine-mediated induction of NO synthase II
Inhibition of small G proteins of the Rho family by statins or Clostridium difficile toxin B enhances cytokine-mediated induction of NO synthase II
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DOI：
10.1038/sj.bjp.0703607
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发表时间：
2000-10-01
影响因子：
7.3
通讯作者：
Kleinert, H
中科院分区：
文献类型：
--
作者：
Hausding, M;Witteck, A;Kleinert, H
1为了研究Ras和/或Rho蛋白在诱导型一氧化氮合酶(NOS II)诱导中的作用，我们以HMG-CoA还原酶抑制剂(他汀类)和艰难梭菌毒素B(TcdB)为药理工具。他汀类药物通过阻止小G蛋白的基本法尼化(RAS)和/或香叶基香叶化(RHO)来间接抑制小G蛋白。2人A549/8细胞和DLD-1细胞以及小鼠3T3成纤维细胞分别与他汀类药物(1-100mU/M)或TcDB(0.01-10ngml(-1))预育18h。细胞因子诱导一氧化氮合酶II表达。用核糖核酸酶保护法测定4~8h后，用Griess法测定NO生成量，用24 h他汀类药物和TcdB明显增加细胞因子诱导的NOS II mRNA表达和NO生成量。甲伐他汀类药物或焦磷酸香叶酯可完全逆转他汀类药物诱导的一氧化氮合酶II基因表达增强。金合欢基焦磷酸盐仅有轻微的抑制作用。因此，Rho家族的小G蛋白可能参与了NOS II的诱导。4在人NOS II启动子的16kb片段(pNOS2(16)Luc)控制下稳定转染荧光素酶报告基因的A549/8细胞中，他汀类药物仅产生细胞因子诱导的NOS II启动子活性的小幅增加。相反，他汀类药物在稳定表达pNOS2(16)Luc.5的DLD-1细胞中具有显著的超诱导作用。结论：我们的研究提供了证据，他汀类药物和TcdB通过抑制Rho家族的小G蛋白来增强细胞因子诱导的NOS II的表达。这反过来导致增强的NOS II启动子活性和/或延长了NOS II的mRNA稳定性。
1 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.2 Human A549/8- and DLD-1 cells as well as murine 3T3 fibroblasts were preincubated for 18 h with statins (1-100 mu M) 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.3 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.4 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.5 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.