Fig. 6: SMYD2 inhibits antiviral IFN-β production independent of its methyltransferase activity.

A–C Examination of IFN-β production in HEK293T cells co-transfected with wild-type Smyd2 or its mutants and RigI/N (A), Tbk1 (B), or Irf3/5D (C) by Luciferase activity assay. D Luciferase activity assay in lysates of HEK293T cells co-transfected with gradient doses of Smyd2 plasmid with or without Tbk1 plasmid (up panel); IB analysis of SMYD2 and TKB1 overexpressed in HEK293T cells (down panel). E Luciferase activity assay in lysates of HEK293T cells co-transfected with Tbk1 plasmid and wild-type and mutant plasmids of Smyd2 (up panel); IB analysis of SMYD2 and TKB1 overexpressed in HEK293T cells (down panel). F IB analysis of phosphorylation of TBK1, IRF3, and P65 in PMs pretreated without or with different doses of LYY507, a specific methyltransferase inhibitor of SMYD2, in response to VSV infection. G Autoradiogram of HMTase assay with recombinant GST, GST-SMYD2, GST-IRF3, and synthesized p53 peptide 362-380, left shows Coomassie staining of purified recombinant proteins and synthesized p53 peptide, and right shows autoradiogram with S-Adenosyl-L-[methyl-³H]. H CHIP assay of H3K4me2 and H3K36me2 modification at Ifnb promotor in Smyd2^−/− and Smyd2^+/+ PMs infected without or with VSV for the indicated time. I Luciferase activity assay in lysates of HEK293T cells co-transfected with Tbk1 plasmid and wild-type and truncated mutant plasmids of Smyd2 (up panel); IB analysis of SMYD2 and TKB1 overexpressed in HEK293T cells (down panel). Error bars represent s.d. Student’s t test. *p < 0.05, **p < 0.01, ***p < 0.001. Data are representative of three independent experiments (A–E, H, I; mean ± s.d.).