Fig. 1

SARS-CoV-2 infection induces mtDNA release and cGAS-dsDNA detection. a, b Representative confocal micrographs of ACE2-expressing A549 cells infected with SARS-CoV-2 (MOI = 0.1) for indicated time points, followed by labeling double-strand DNA (dsDNA, green) and SARS-CoV-2 N protein (red) (a). Scale bars indicated 10 μm. The number of dsDNA puncta per cell (b) were counted and analyzed from n = 20 cells. c, d Representative confocal micrographs of ACE2-expressing A549 cells infected with SARS-CoV-2 (MOI = 0.1) for indicated time points, followed by labeling mitochondria (TOM20, green) and double-strand DNA (dsDNA, red) (c). Scale bars indicated 10 μm. The proportion of dsDNA in mitochondria (d) were counted and analyzed from n = 10 cells. e Quantitative real-time PCR (qRT-PCR) of cytosolic mtDNA abundance of Calu3 cells infected with SARS-CoV-2 (MOI = 0.1) for indicated time points. f, g Representative confocal micrographs of ACE2-expressing A549 cells infected with SARS-CoV-2 (MOI = 0.1) for indicated time points, followed by labeling cGAS (green) and double-strand DNA (dsDNA, red) (f). Scale bars indicated 10 μm. The number of dsDNA-cGAS puncta per cell (g) were counted and analyzed from n = 20 cells. h Calu3 cells were infected with SARS-CoV-2 (MOI = 0.1) for indicated time points. Cell lysates were collected, immunoprecipitated with A + G beads together with cGAS antibody, followed by qRT-PCR analysis of extracted DNA to detect cGAS-bound mtDNA abundance. Data in b, g were expressed as mean ± SD of 20 cells for each condition. Data in d were expressed as mean ± SD of 10 cells for each condition. Data in e, h were expressed as mean ± SEM of 3 independent biological experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, ns not significant (unpaired two-tailed student’s t-test). Similar results were obtained for 3 independent biological experiments in (a, c, f)