Fig. 8: SARS-CoV-2 causes CHK1 and RRM2 loss and DDR activation in lungs and nasal mucosa of patients with COVID-19.
a, Immunofluorescence (IF) images of lungs of patients diagnosed (COVID, n = 17) or not (non-COVID, n = 9) with COVID-19, and nasal mucosa of patients with COVID-19 in which cells were detected as positive (FISH+, n = 18) and negative (FISH−, n = 11) for SARS-CoV-2. Tissues were stained for SARS-CoV-2 RNA, γH2AX and CK18 to label epithelial cells; nuclei were counter-stained with Hoechst. Scale bar, 10 μm. b, IF images of lung (n = 4) and nasal mucosa (n = 5) of patients with COVID-19 stained for SARS-CoV-2 N-protein, γH2AX and 53BP1. Sections (n = 6) of a lung treated ex vivo with 2 μM bleomycin were used as positive control for DDR activation. Nuclei were stained with Hoechst. Scale bar, 10 μm. c, Quantification of DDR determined in a. Histograms show the percentage of epithelial cells bearing γH2AX foci (>1). d, Quantification of 53BP1 recruitment at γH2AX sites determined in b. The histograms show the percentage of nuclei with 53BP1 foci (>1) among those positive for γH2AX. e, IHC images of tissues of patients with COVID-19 stained for the indicated markers. Virus presence was assessed by probing for N-protein. Nuclei were stained with haematoxylin (light blue). Conditions are as in a; scale bar, 50 μm. f, The histograms show the percentage of cells positive for the markers determined in e. pRPAS4/8: non-COVID (n = 5 patients); COVID (n = 10). CHK1: non-COVID (n = 7); COVID (n = 3); FISH− (n = 4); FISH+ (n = 4). Values are the mean ± s.e.m. g, IF images of tissues of patients with COVID-19 stained for RRM2; scale bar, 10 μm. h, The histograms show the average intensity of RRM2 signal as determined in g. Values are the mean ± s.e.m.; n = 3 individuals for lungs and n = 5 for nasal mucosa. i, Schematic model of the impact of SARS-CoV-2 infection on genome integrity and cellular senescence. Source numerical data are available in source data.
