Pellino 1 is required for interleukin-1 (IL-1)-mediated signaling through its interaction with the IL-1 receptor-associated kinase 4 (IRAK4)-IRAK-tumor necrosis factor receptor-associated factor 6 (TRAF6) complex.

The signaling pathway downstream of the mammalian interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) is evolutionally conserved with that mediated by the Drosophila Toll protein. Toll initiates its signal through the adapter molecule Tube and the serine-threonine kinase Pelle. Pelle is highly homologous to members of the IL-1R-associated kinase (IRAK) family in mammals. Recently, a novel Pelle-interacting protein called Pellino was identified in Drosophila. We now report a mammalian counterpart of Pellino, termed Pellino 1, which is required for NF kappa B activation and IL-8 gene expression in response to IL-1, probably through its signal-dependent interaction with IRAK4, IRAK, and the tumor necrosis factor receptor-associated factor 6 (TRAF6). The Pellino 1-IRAK-IRAK4-TRAF6 signaling complex is likely to be intermediate, located between the IL-1 receptor complex and the TAK1 complex in the IL-1 pathway.