Fig. 3

PP1 is required for the RLRs activation, and its activity is modulated by MeV and α-CoVs. Upon dsRNA sensing, PP1 is recruited (by unknown RIPPOs) to dephosphorylate RIG-I/MDA5 and promote their activation. Recently, it was shown that as a consequence of the cytoskeleton disturbance, R12C recruits PP1 to dephosphorylate RIG-I and MDA5. In the early infection of dendritic cells, MeV interacts with the DC-SING receptor leading to the activation of Raf-1 kinase. Raf1 phosphorylate inhibitor 1 (I-1), a potent PP1 inhibitor, avoids RIG-I/MDA5 activation. In late MeV infection, protein V prevents MDA5 dephosphorylation by acting as a PP1-substrate. In α-CoV infections, the nsp7 binds to MDA5 N-terminus and blocks its dephosphorylation by PP1. Figure created with BioRender.com