The IκB kinase complex regulates the stability of cytokine-encoding mRNA induced by TLR-IL-1R by controlling degradation of regnase-1

Laboratory of Host Defense, World Premier International Immunology Frontier Research Center, Osaka University, Osaka, Japan.
Nature Immunology (Impact Factor: 24.97). 12/2011; 12(12):1167-75. DOI: 10.1038/ni.2137
Source: PubMed

ABSTRACT Toll-like receptor (TLR) signaling activates the inhibitor of transcription factor NF-κB (IκB) kinase (IKK) complex, which governs NF-κB-mediated transcription during inflammation. The RNase regnase-1 serves a critical role in preventing autoimmunity by controlling the stability of mRNAs that encode cytokines. Here we show that the IKK complex controlled the stability of mRNA for interleukin 6 (IL-6) by phosphorylating regnase-1 in response to stimulation via the IL-1 receptor (IL-1R) or TLR. Phosphorylated regnase-1 underwent ubiquitination and degradation. Regnase-1 was reexpressed in IL-1R- or TLR-activated cells after a period of lower expression. Regnase-1 mRNA was negatively regulated by regnase-1 itself via a stem-loop region present in the regnase-1 3' untranslated region. Our data demonstrate that the IKK complex phosphorylates not only IκBα, thereby activating transcription, but also regnase-1, thereby releasing a 'brake' on IL-6 mRNA expression.

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    • "Overexpression of Reg1 suppressed the luciferase activity in an RNase-activity dependent manner (Figure 1K). Consistent with a previous report (Iwasaki et al., 2011), overexpression of Reg1 suppressed Reg1 3′ UTR containing nucleotides 1-210, but not in the case where nucleotides 1-200, which contains the SL, were absent. Collectively, Reg1-bound mRNAs obtained by RIP-Seq are indeed targeted by Reg1 for degradation. "
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