Fig 2: FOSL1 inhibits IFN-I response through modification of signaling molecules upstream of TBK1. (A) Immunoassay of 293T cell extracts transfected with plasmids encoding F-RIG-I, F-MAVS, F-TRAF3, F-TBK1, F-IRF3, and F-TRIF as well as HA-FOSL1, followed by immunoprecipitation (IP) with anti-FLAG beads and immunoblot analysis with anti-HA antibody. (B) Immunoassay of 293T cell extracts transfected with plasmids encoding F-TRAF2, F-TRAF3, F-TRAF5, and F-TRAF6 as well as HA-FOSL1, followed by IP with anti-FLAG beads and immunoblot analysis with anti-HA antibody. (C) IP and immunoblot analysis of THP-1 cell extracts treated with poly(I:C) or medium overnight. (D) Real-time qPCR analysis of IFN-β and ISG56 expression in WT, FOSL1 KO, TRAF3 KO, and FOSL1/TRAF3 double-knockout BMDMs after stimulation with poly(I:C) for 16 h. *, P < 0.05; **, P < 0.01; ***, P < 0.001; NS, not significantly different from control group (Student’s t test). Data are representative of results of three independent experiments (means ± SD in panel D).

Fig 3: Validation of selected binding partners of FOSL1 and FOSL2 (A,B) FOSL1 (panel A) and FOSL2 (panel B) protein was immunoprecipitated from 72 h-cultured Th17 cells and western blotting was used to confirm their MS-identified interactions with SIRT-1, JUNB, RUNX1, and JUN. Blots depict lanes for total lysate (input), control IgG IP, and FOSL1/FOSL2 IP. Figures show representative blots for two or three biological replicates (see Figure S5 for all the replicates). (C,D) Volcano plots show selected binding partners of FOSL1 (panel C) and FOSL2 (panel D) that were validated by PRM-MS analysis. Data are representative of three biological replicates. The plots were extracted from Skyline.

Fig 4: Shared interacting partners of FOSL1 and FOSL2 in human Th17 cells. (A) Venn diagram shows the number of shared and unique interactors of FOSL1 and FOSL2 in human Th17 cells, as identified by LC-MS/MS analysis. (B) PPIs shared between FOSL1 and FOSL2 were mapped against the STRING database and visualized using Cytoscape (a medium confidence score of 0.4 was used to create the STRING network).

Fig 5: Molecular function networks enriched for FOSL1 and FOSL2 interactors. (A,B) FOSL1 (panel A) and FOSL2 (panel B) interactors were clustered based on their molecular functions and the resulting networks were visualized using ClueGO and CluePedia plugins built in Cytoscape (Bonferroni step-down corrected p values <0.05).