Conserved function of p200 family proteins in the inhibition of type I IFNs responses.

(A) Schematic diagram of the domain structure of p200 family proteins. (B) Co-immunoprecipitation (IP, with anti-Flag) and immunoblot (IB, with anti-HA) analysis of HEK293T cells that were transfected with plasmids encoding Flag-IRF7 and HA-(IFI204, IFI205, IFI209, MNDA, IFI16, MNDAL, AIM2, IFI202 and IFI16β) for 24 hrs. Cell lysate was analyzed by immunoblot with anti-Flag and anti-HA antibodies. (C) Dual luciferase assays for analyzing the promoter activity of IFNβ or IFNα4 in Irf3^−/−Irf7^−/−MEFs co-transfected with IFNβ or IFNα4 promoter luciferase reporter plasmids and the indicated plasmids, respectively. The Renilla expression plasmid (pRL-TK, 10 ng) was co-transfected as an internal control (upper graphs). qRT-PCR analysis of Ifnb or Ifna4 in Irf3^−/−Irf7^−/− MEFs transfected with the indicated plasmids (lower graphs). 24 hrs post-transfection, cells were treated with SeV for 12 hrs. *P < 0.05, **P < 0.01 and ***P < 0.001. Data are representative of three independent experiments (mean ± SD in C).