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. 2021 Nov;27(11):1318–1329. doi: 10.1261/rna.078923.121

FIGURE 4.

FIGURE 4.

SARS-CoV-2 Nsp1 expression is sufficient for degradation of host basal mRNAs. (A) Schematic of Flag-tagged SARS-CoV-2 protein expression vector transfected into U2-OS cells. (B) Immunoblot for Flag confirmed expression of Flag-tagged Nsp1 and Nsp15 expression at expected size (Nsp1 ∼20 kDa; Nsp15 ∼40 kDa) in cells transfected with respective expression vectors but not empty vector (EV). Note, the unlabeled lanes between the EV and Nsp1/Nsp15 vectors are plasmid clones that did not express the proteins and were not used for subsequent experiments. (C) Immunofluorescence assay for Flag and smFISH for ACTB and GAPDH mRNAs in U-2 OS cells 24 h post-transfection with either pcDNA3.1+ (empty vector; EV), Flag-Nsp1, or Flag-Nsp15 expression vectors. (D) Quantification of ACTB and GAPDH mRNAs as represented in C. Dots represent individual cells. Between 10–22 cells analyzed per group. Statistical significance ([*] P < 0.05; [**] P < 0.005; [***] P < 0.0005) was determined by t-test.