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. 2020 Jul 16;11:1513. doi: 10.3389/fimmu.2020.01513

Figure 2.

Figure 2

Regulation of type I IFN due to the activation of IFN receptors. Upon activation of the IFNAR receptor induced by the cytokine IFN, three different pathways can be activated. One pathway involves the phosphorylation of the IFNAR cause by Janus Kinase 1 (JAK1) and Tyrosine Kinase 2 (TYK2), which generates the phosphorylation of both STAT1 and STAT2 that come together to form a heterodimer. This heterodimer interacts with IRF9, forming the ISGF3 complex that is translocated to the nucleus where it binds to DNA activating the regions of ISG and ISRES, promoting an antiviral response. An alternative pathway involves the phosphorylation of the IFNAR caused by JAK1 and JAK2, which produces the phosphorylation of STAT1 and two of them come together in order to form a homodimer. This homodimer is able to translocate to the nucleus where it binds to DNA, activating the regions of GAS, and promoting a pro-inflammatory response. Another alternative pathway involves the phosphorylation of the IFNAR, caused by JAK2, which generates the phosphorylation of STAT3, and two of these come together in order to form a homodimer. This homodimer is able to translocate to the nucleus where it binds to DNA, activating the regions of GAS and promoting the inhibition of the pro-inflammatory response.