Fig. 6. Role of Nsp15 EndoU activity in cGAS and STING downregulation.

(A-D) HEK293T cells were transfected with cGAS or STING plasmid along with wild-type and mutant SARS-CoV-2 Nsp15 plasmids for 48 h. RNA levels (A and B) and protein levels (C and D) of cGAS and STING were measured by RT-qPCR and western blot, respectively. RT-qPCR results are presented relative to the expression of 18S rRNA. Data are mean ± SD (n = 3) and analyzed by one-way ANOVA with Dunnett’s multiple comparison test. (E and F) HEK293T cells were transfected with cGAS or STING plasmid plus mCherry or HCoV Nsp15 plasmids for 48 h. Western blot performed to assess the expression of indicated proteins.