Fig. 4: S. aureus strain Newman drives the expression of proapoptotic factors trail and daxx in an IFN-I dependent manner.

BMDMs from WT or IFNAR^−/− mice were infected with S. aureus strains Newman or LAC USA300 at a MOI of 100 for 1 h. BMDMs were then incubated with gentamicin media for 1 h which was then replaced with antibiotic free media. 24 h post gentamicin treatment, cells were lysed for RNA extraction. Expression of the proapoptotic genes trail (A) and daxx (B) was assessed using RT-PCR in both WT and IFNAR^−/− mice. RT-PCR data was normalized using b2m as a housekeeping gene and analyzed using the ΔΔCT method. Protein lysates were collected 24 h post gentamicin treatment and analyzed using western blotting for Daxx (C) or caspase-3 (E) with β-actin serving as a loading control. Densitometry of Daxx (D) and cleaved caspase-3 (F) was determined using Bio-Rad’s Image Lab software, normalized to the loading control, & expressed as relative expression. Results are expressed as mean ± SD and statistically analyzed using a two-way ANOVA with a Šidák multiple comparisons posttest (P value * <0.05, ** <0.01, *** <0.001 and **** <0.0001) for n = 3–6 independent experiments.