title: Mechanism of inhibition of lipopolysaccharide-induced interferon-β production by 2-aminopurine.
abstract: 2-Aminopurine (2-AP) is widely used as an inhibitor for double stranded RNA-dependent protein kinase (PKR). Previously, we reported that 2-AP inhibits Toll-like receptor (TLR) ligand-induced nitric oxide production through the prevention of interferon (IFN)-β production. In this study, we investigated the mechanisms for 2-AP inhibition of lipopolysaccharide (LPS)-induced IFN-β production. A reporter gene assay showed that LPS-induced IFN-β promoter, but not nuclear factor (NF)-κB, activation was significantly inhibited by 2-AP. IFN-β promoter activation induced by the overexpression of Toll/interleukin-1 receptor domain-containing adaptor inducing IFN-β (TRIF) was significantly inhibited by 2-AP in a dose-dependent manner, while TRIF- or myeloid differentiation primary response gene 88-dependent NF-κB activation was not inhibited. IFN-β promoter activation induced by expression of the downstream signaling molecules, tumor necrosis factor receptor-associated factor family member-associated NF-κB activator-binding kinase 1, inhibitor of NF-κB kinase i and a constitutively active mutant of interferon regulatory factor (IRF)-3, was also inhibited by 2-AP. Another PKR inhibitor harboring the imidazolo-oxindole structure, however, did not affect TRIF signaling molecules-induced IFN-β promoter activation, suggesting that the inhibition of IFN-β transcription by 2-AP is independent of PKR inhibition. Further, we examined the effect of 2-AP on LPS-induced IRF-3 activation by immunoblotting. While 2-AP did not affect LPS-induced phosphorylation of IRF-3, nuclear translocation of IRF-3 was inhibited. Moreover, we revealed that LPS-induced phosphorylation of Akt, another key molecule involved in IRF-3 activation, was inhibited by 2-AP. These results suggest that 2-AP inhibits nuclear translocation of phosphorylated-IRF-3 by inhibiting Akt activation.
authors: Department of Biopharmaceutical Sciences, Laboratory of Microbiology, Gifu Pharmaceutical University, Gifu, Japan. sugiyama@gifu-pu.ac.jp
authors: Tsuyoshi
authors: T
authors: Sugiyama
authors: Takaki
authors: T
authors: Gotou
authors: Kazuya
authors: K
authors: Moriyama
authors: Nodoka
authors: N
authors: Kajiura
authors: Takuya
authors: T
authors: Hasegawa
authors: Junko
authors: J
authors: Tomida
authors: Keita
authors: K
authors: Takahashi
authors: Takayuki
authors: T
authors: Komatsu
authors: Hiroshi
authors: H
authors: Ueda
authors: Katsuya
authors: K
authors: Sato
authors: Shunji
authors: S
authors: Tokoro
authors: Paola
authors: P
authors: Neri
authors: Hiroshi
authors: H
authors: Mori
mesh_terms: D015075:2-Aminopurine / Q000494:pharmacology*; D016475:3T3 Cells; D033942:Adaptor Proteins, Vesicular Transport / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D000818:Animals; D002460:Cell Line; D017930:Genes, Reporter; D050838:Interferon Regulatory Factor-3 / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D016899:Interferon-beta / Q000096:biosynthesis* / Q000235:genetics; D007375:Interleukin-1 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000276:immunology*; D008264:Macrophages / Q000276:immunology; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000096:biosynthesis; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000096:biosynthesis
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D050838:Interferon Regulatory Factor-3; D007375:Interleukin-1; D008070:Lipopolysaccharides; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; C470409:TICAM1 protein, human; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D015075:2-Aminopurine; D016899:Interferon-beta; D051057:Proto-Oncogene Proteins c-akt