Lopez-Pelaez Marta, Lamont Douglas J, Peggie Mark, Shpiro Natalia, Gray Nathanael S, Cohen Philip
Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, and.
College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom; and.
Proc Natl Acad Sci U S A. 2014 Dec 9;111(49):17432-7. doi: 10.1073/pnas.1418399111. Epub 2014 Oct 17.
The siRNA knockdown of IFN Regulatory Factor 5 (IRF5) in the human plasmacytoid dendritic cell line Gen2.2 prevented IFNβ production induced by compound CL097, a ligand for Toll-like receptor 7 (TLR7). CL097 also stimulated the phosphorylation of IRF5 at Ser462 and stimulated the nuclear translocation of wild-type IRF5, but not the IRF5[Ser462Ala] mutant. The CL097-stimulated phosphorylation of IRF5 at Ser462 and its nuclear translocation was prevented by the pharmacological inhibition of protein kinase IKKβ or the siRNA knockdown of IKKβ or its "upstream" activator, the protein kinase TAK1. Similar results were obtained in a murine macrophage cell line stimulated with the TLR7 agonist compound R848 or the nucleotide oligomerization domain 1 (NOD1) agonist KF-1B. IKKβ phosphorylated IRF5 at Ser462 in vitro and induced the dimerization of wild-type IRF5 but not the IRF5[S462A] mutant. These findings demonstrate that IKKβ activates two "master" transcription factors of the innate immune system, IRF5 and NF-κB.
在人浆细胞样树突状细胞系Gen2.2中，通过小干扰RNA（siRNA）敲低干扰素调节因子5（IRF5）可阻止由Toll样受体7（TLR7）配体化合物CL097诱导的IFNβ产生。CL097还刺激IRF5在Ser462位点的磷酸化，并刺激野生型IRF5的核转位，但不刺激IRF5[Ser462Ala]突变体的核转位。蛋白激酶IKKβ的药理学抑制或IKKβ或其“上游”激活剂蛋白激酶TAK1的siRNA敲低可阻止CL097刺激的IRF5在Ser462位点的磷酸化及其核转位。在用TLR7激动剂化合物R848或核苷酸寡聚化结构域1（NOD1）激动剂KF-1B刺激的小鼠巨噬细胞系中也获得了类似结果。IKKβ在体外使IRF5在Ser462位点磷酸化，并诱导野生型IRF5二聚化，但不诱导IRF5[S462A]突变体二聚化。这些发现表明IKKβ激活先天性免疫系统的两个“主要”转录因子，即IRF5和NF-κB。
