IRF5 is acetylated in vivo after NDV infection or coexpression with HATs. A, 2fTGH/IRF5-expressing cells were left uninfected, infected with NDV, or transiently transfected with PCAF, CBP, or p300 expression plasmids. Whole cell lysates were immunoprecipitated with either anti-acetyl lysine Abs or IRF5 Abs and acetylated IRF5 detected with the reciprocal Ab. Levels of transfected proteins are shown at the bottom. Results are representative of three independent experiments. B, NDV-induced acetylation of IRF5 occurs in both the amino- and C terminus. gfp-IRF5 fusion proteins were transiently transfected to 2fTGH cells and left uninfected or infected with NDV. Similar to A, whole cell lysates were immunoprecipitated with anti-acetyl lysine Abs and acetylated IRF5 detected with anti-gfp Abs. The same membrane was stripped and reprobed with anti-IRF3 Abs. Results are representative of three independent experiments. C, Treatment with TSA increases basal IRF5 acetylation. 2fTGH and 2fTGH/IRF5 expressing cells were left untreated or treated with TSA, immunoprecipitated with antiacetyl lysine Abs, and acetylated IRF5 detected with anti-IRF5. Results are representative of three independent experiments.