TET3 Inhibits Type I IFN Production Independent of DNA Demethylation

Type I interferons (IFNs) play both beneficial and harmful roles in antiviral responses. Precise regulation of host type I IFNs is thus needed to prevent immune dysregulation. Here, we find that the DNA demethylase TET3 is a negative regulator of IFN-β in response to poly(I:C) stimulation or viral infection. Deletion of TET3 enhances antiviral responses, with elevated expression of IFN-β and IFN-stimulated genes. The catalytic domain of TET3 was critical for the suppression of IFN-β production, but TET3 enzymatic activity was dispensable. Instead, the catalytic domain of TET3 interacts with HDAC1 and SIN3A, thus enhancing their binding to the Ifnb1 promoter. Our study demonstrates that TET3 negatively regulates type I IFN production independent of DNA demethylation. This not only sheds light on TET3 as a signaling protein in immune cells for gene regulation but also will help to develop strategies to prevent type I IFN-related disease.