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. 2023 Jan 16;26(2):105995. doi: 10.1016/j.isci.2023.105995

Figure 2.

Figure 2

N protein delivers nucleic acids into cells

(A) N protein-RNA complex binding to the cell surface. Aliquots of 10 μg SARS-CoV-2 N protein were incubated with 1 μg of indicated RNAs for 1 h at 4°C, and added to A549 or HPAEpiC cultures. SARS-CoV-2 N protein only without RNA was used as a control. The samples were analyzed by flow cytometry and data are shown as mean fluorescence intensity (MFI). Data are shown as mean ± SEM. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001; t test.

(B) The observation of N protein-RNA enters into cells. HPAEpiC were seeded onto 8-well glass slides (40,000 cells/well). SARS-CoV-2 N protein 10 μg and 40 μg RNA-FAM (green) were mixed for 1 h at 4°C. cells were treated with SARS-CoV-2 N-RNA-FAM mixture for 1 h. The groups of non-treated cells and RNA-FAM only were as controls. After treatment, N protein was detected by anti-N antibody (Red). The localization of RNA-FAM was green. DAPI (blue) indicates cell nuclei. Scale bar: 15 μm.

(C) Lattice light sheet microscopy time lapse imaging of N protein-RNA complex entering into HPAEpiC cells. SARS-CoV-2 N protein 10 μg was mixed with 40 μg RNA-FAM (fluorescein) for 1 h at 4°C and then treated with ice-cooled alveolar cells. The signals of RNA-FAM and Hochest 33,342 were monitored by lattice light sheet microscopy at different time points.