Figure 1.

Effect of ADAR1-mediated A-to-I editing on endogenous and exogenous dsRNA. In the presence of ADAR1, endogenous dsRNA is edited (red square) and does not activate MDA5, RIG-I and PKR (homeostasis, normal tissues). In case of ADAR1 deficiency or mutation, endogenous dsRNA is not edited and recognized as non-self, as for exogenous microbial RNA, leading to IFN (IFN-I and -III) production, a strong ISG signature and uncontrolled immune response activation (chronic inflammation, autoimmune diseases). On the contrary, when ADAR1 is overexpressed, IFNs and their ISGs are dampened, limiting immune responses (tumor).