Lys (K)63-linked polyubiquitination of IRAK-1 is required for IL-1 receptor- and Toll-like receptor-mediated NF-kappaB activation

Conze DB, Wu CJ, Thomas JA, Landstrom A, Ashwell JD
Source: Mol Cell Biol
Publication Date: (2008)
Issue: 28(10): 3538-47
Research Area:
Cancer Research/Cell Biology
Cells used in publication:
Embryonic fibroblast, mouse (MEF) immort
Species: mouse
Tissue Origin: embryo
Nucleofector® I/II/2b
Stimulation through the IL-1 receptor (IL-1R) and some Toll-like receptors (TLRs) induces ubiquitination of TRAF6 and IRAK-1, signaling components required for NF-kappa B and MAP kinase activation. Here we show that although TRAF6 and IRAK-1 acquired Lys (K)63-linked polyubiquitin chains upon IL-1 stimulation, only ubiquitinated IRAK-1 bound NEMO, the regulatory subunit of IkappaB kinase (IKK). The sites of IRAK-1 ubiquitination were mapped to Lys134 and Lys180, and arginine substitution of these residues impaired IL-1R/TLR-mediated IRAK-1 ubiquitination, NEMO binding, and NF-kappaB activation. K63-linked ubiquitination of IRAK-1 required enzymatically active TRAF6, indicating that it is the physiologically relevant E3. Thus, K63-linked polyubiquitination of proximal signaling proteins is a common mechanism used by diverse innate immune receptors for recruiting IKK and activating NF-kappaB.