Post-transcriptional regulation of human inducible nitric-oxide synthase expression by the Jun N-terminal kinase.
Human inducible nitric-oxide synthase (iNOS) expression is regulated both at transcriptional and post-transcriptional levels. In the present study, the effect of Jun N-terminal kinase (JNK) on human iNOS expression was investigated. In A549/8 human alveolar epithelial cells, both the inhibition of JNK by a pharmacological inhibitor anthra[1,9-cd]pyrazol-6(2H)-one1,9-pyrazoloanthrone (SP600125) and small interfering RNA (siRNA)-mediated down-regulation of JNK led to a reduction of iNOS mRNA and protein expression. iNOS promoter activity was not affected by these treatments. Hence, JNK seems to regulate iNOS expression through post-transcriptional mechanisms by stabilizing iNOS mRNA. Our laboratory has shown recently that a cytokine-induced RNA binding protein tristetraprolin (TTP) is a major positive regulator of human iNOS expression by stabilizing iNOS mRNA. Therefore, the effect of JNK inhibition by SP600125 or down-regulation by siRNA on TTP expression was investigated. Both SP600125 and siRNA targeted at JNK resulted in a reduction of TTP protein expression without affecting the amount of TTP mRNA. These data suggest a post-transcriptional control of TTP expression by JNK. Moreover, the modulation of JNK signaling by SP600125 or siRNA did not change p38 phosphorylation. In summary, the results suggest that JNK regulates human iNOS expression by stabilizing iNOS mRNA possibly by a TTP-dependent mechanism.
Korhonen
Riku
R
Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany.
Linker
Katrin
K
Pautz
Andrea
A
Förstermann
Ulrich
U
Moilanen
Eeva
E
Kleinert
Hartmut
H
D000873:Anthracenes / Q000494:pharmacology; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D020871:RNA Stability / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051816:Tristetraprolin / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000873:Anthracenes; D016207:Cytokines; D034741:RNA, Small Interfering; D051816:Tristetraprolin; C432165:pyrazolanthrone; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases