The role of TBK1 and IKKε in the expression and activation of Pellino 1

Hilary Louise Smith , Xin-Yu Liu , Liang Dai , Eddy Teck Hui Goh , Aye-Thu Chan , Jiajia Xi , Cheah-Chen Seh , Insaf A. Qureshi , Julien Lescar , Christiane Ruedl , Robert Gourlay , Simon Morton , Joanne Hough , Edward G Mciver , Philip Cohen (1) , Peter Cf Cheung

1 MRC Protein Phosphorylation Unit

Mammalian Pellino isoforms are phosphorylated by IRAK1/IRAK4 in vitro, converting them into active E3 ubiquitin ligases. Here we report a striking enhancement in both transcription of the gene encoding Pellino 1 and Pellino 1 protein expression when murine BMDM are stimulated with LPS or poly(I:C). This induction occurs via a TRIF-dependent, IRAK-independent pathway and is prevented by inhibition of the IKK-related protein kinases, TBK1 and IKKε. Pellino 1 is not induced in IRF3-/- BMDM, and is only reduced slightly in type 1 interferon receptor-/- BMDM, identifying Pellino 1 as a new IRF3-dependent gene. We also identify Pellino 1 in a two-hybrid screen using IKKε as bait, and show that IKKε/TBK1 activate Pellino 1 in vitro by phosphorylating Ser76, Thr288 and Ser293. Moreover, we show that the E3 ligase activity of endogenous Pellino 1 is activated in LPS or poly(I:C)-stimulated macrophages. This occurs more rapidly than the increase in Pellino 1 mRNA and protein expression, is prevented by inhibition of IKKε/TBK1 and is reversed by phosphatase treatment. Thus IKKε/TBK1 mediate the activation of Pellino 1's E3 ligase activity as well as inducing the transcription of its gene and protein expression in response to TLR3 and TLR4 agonists.

Mots clés: Life Sciences

Hilary Louise Smith, Xin-Yu Liu, Liang Dai, Eddy Teck Hui Goh, Aye-Thu Chan, et al.. The role of TBK1 and IKKε in the expression and activation of Pellino 1. Biochemical Journal, 2011, 434 (3), pp.537-548. ⟨10.1042/BJ20101421⟩. ⟨hal-00569404⟩