Figure 1. UVB light causes mtROS dependent IFN responses accompanied by cytosolic Z-DNA release derived from mitochondria.

A. Experimental approach. B. Representative images from N/TERTs treated +/− mitoTEMPO (MT) +/− UVB irradiation stained with MitoSOXred and Hoechst33342. C. Quantification of MitoSOX intensity per cell using CellProfiler software. D. N/TERTs were treated with either rotenone, MT or UVB for 6h. Gene expression of IFNB1 (n=44) and IFNL3 (n=3) was determined by qPCR. E. Gene expression of IFNK, MX1 and OASL (n=3) +/− mitoTEMPO +/− UVB 24h after UVB exposure. F. Representative confocal microscopy from N/TERTs of TOMM20, Z-DNA, and DAPI without stimulation. G. Line scan analysis of the line in F. H. Representative confocal microscopy from N/TERTs of TOMM20 and Z-DNA 3h after UVB exposure. I. Line scan analysis of the dotted white line in H. J. Representative confocal images from N/TERTs of TOMM20, Z-DNA, DAPI +/− mitoTEMPO, pretreatment with IFNα or 3h after UVB. Scale bar 5μm. K-L. Quantification of Z-DNA puncta using CellProfiler software. M. Mitochondrial fragments (objects <1µm² with circularity > 0.6) using CellProfiler. Mean + SEM or violin plots with mean + quartiles of n≥3 independent experiments. P-values were calculated using ordinary one-way ANOVA followed by Sidak’s multiple comparison test. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.