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. 2021 Oct 13;13(10):2056. doi: 10.3390/v13102056

Figure 3.

Figure 3

Severe acute respiratory syndrome coronavirus 2 (SARS–CoV–2) spike protein impedes the recruitment of DNA damage repair checkpoint proteins. (A) Membrane fraction (MF), cytosolic fraction (CF), soluble nuclear fraction (SNF), and chromatin-bound fraction (CBF) from HEK293T cells transfected with SARS–CoV–2 spike protein were immunoblotted for His-tag spike and indicated proteins. (B) Left: Immunoblots of DNA damage marker γH2AX in empty vector (E.V)– and spike protein–expressing HEK293T cells after 10 Gy γ-irradiation. Right: corresponding quantification of immunoblots in left. The values represent the mean ± SD (n = 3). Statistical significance was determined using Student’s t-test. **** p < 0.0001. (C) Immunoblots of DNA damage repair related proteins in spike protein–expressing HEK293T cells. (D) Representative images of 53BP1 foci formation in E.V– and spike protein-expressing HEK293 cells exposed to 10 Gy γ–irradiation. Scale bar: 10 µm. (E) Quantitative analysis of 53BP1 foci per nucleus. The values represent the mean ± SEM, n = 50. (F) BRCA1 foci formation in empty vector- and spike protein-expressing HEK293 cells exposed to 10 Gy γ–irradiation. Scale bar: 10 µm. (G). Quantitative analysis of BRCA1 foci per nucleus. The values represent the mean ± SEM, n = 50. Statistical significance was determined using Student’s t-test. **** p < 0.0001.