Fig 1: TRIM56 enhances the R. rickettsii-induced cGAS-STING signaling through ubiquitination of STING. (A–B) PMA-differentiated WT and trim56−/− THP-1 cells were infected by R. rickettsii, and then, the infected cells were collected at 0, 0.5, 2, 4, 6, and 12 hours post-infection for Western blotting analysis, followed by probing with anti-p-IRF3, anti-IRF3, and anti-GAPDH, respectively. (B) Densitometry of (A) was presented as a fold change between the ratios of p-IRF3/IRF3 (n = 3, mean ± SD). (C–D) PMA-differentiated WT and trim56–/− THP-1 cells were infected by R. rickettsii, and then, the infected cells were collected for Western blotting analysis, followed by probing with anti-p-STING, anti-STING, and GAPDH, respectively (C). Densitometry of (C) was presented as a fold change between the ratios of p-STING/STING (n = 3, mean ± SD) (D). (E–F) WT and trim56–/– HeLa cells transfected with STING-FLAG and HA-Ub plasmids were infected with R. rickettsii at an MOI of 1 for 2 days, and then, the protein complexes were extracted from the cell lysates with anti-FLAG M2 beads. The immunoprecipitation with FLAG lysates (E) and whole-cell lysates (F) was probed with FLAG and HA antibodies. Data presented were representative of at least three independent experiments. nsP ≥ 0.05; **P < 0.01; ****P < 0.0001.