Figure 4. SGs dampen dsRNA-triggered apoptosis and the consequent negative feedback regulation of IRF3.

A-C. Cell death in WT vs. ΔG3BPs U2OS cells at 24 hr post-dsRNA as examined by (A) bright-field microscopy, (B) caspase-3/7 activity and (C) Sytox uptake.

D. Cell death in response to staurosporin (STS) and etoposide. U2OS cells were treated with STS (1 μM) or etoposide (20 μM) for 24 hrs before Sytox analysis.

E. Cell death in WT, ΔUBAP2L and ΔPKR U2OS cells at 24 hr post-dsRNA.

F. Comparison of cell death triggered by dsRNA, etoposide and a combination of caspase-8 inhibitor (Z-IETD-FMK, Casp-8i) and TNFα. Etoposide was used as a known trigger for apoptosis, while Casp-8i+TNFα was for necroptosis.

G. Analysis of PARP and caspase-3 (Casp-3) cleavage using samples from (F).

H. Apoptotic caspase cleavage in U2OS cells at 6 or 24 hr post-dsRNA.

I. Effect of pan-caspase inhibitor (Q-VD-OPh) on dsRNA-triggered cell death, as measured by Sytox uptake at 24 hr post-dsRNA. U2OS cells were treated with Q-VD-OPh (10 μM) 1 hr pre-dsRNA.

J. Effect of Q-VD-OPh (10 μM) on PARP cleavage in U2OSΔG3BPs cells at 24 hr post-dsRNA.

K. Effect of Q-VD-OPh on IRF3 phosphorylation and caspase-3 cleavage.

L. Effect of Q-VD-OPh on IFNβ mRNA induction in U2OSΔG3BPs cells. Data were normalized to 6 hr post-dsRNA in the absence of Q-VD-Oph.

M. Effect of Q-VD-OPh on IFNβ mRNA induction in A549 cells. Data were normalized to 6 hr post-dsRNA in WT A549 in the absence of Q-VD-Oph.

Data are presented in means ± SD. p values were calculated using two-tailed unpaired Student’s t test (ns, p>0.05). All data are representative of three independent experiments.