Figure 2

Schematic of NOD1 signaling pathways. NOD1 activation by its specific ligand iE-DAP activates at least two distinct signaling pathways. On the one hand, activated NOD1 triggers IFN-β production through the consecutive activation of RICK, TRAF3, TBK1/IKKε and IRF7. IRF7-dependent IFN-β production leads to the expression of IP-10 and other Th1 cytokines via transactivation of ISGF3 (Stat1-Stat2-IRF9 complex). On the other hand, NOD1 activation triggers the RICK and IKK-α,β,γ complex-dependent activation of NF-κB and subsequent production of proinflammatory cytokines and chemokines such as IL-8. Whether NF-κB is indeed activated upon Nod1 ligation in all cell types, including epithelial cells, remains controversial and will be the subject of future experimentation. Adapted from [56] and [21].