Fig. 2.

HCoV infection triggers HSF1 nuclear translocation in human lung cells. A Schematic representation of HSF1 intracellular localization under physiological (no stress) and stress conditions. B Immunoblot analysis of pHSF1-Ser326, HSF1 and viral spike (S) protein levels in cytoplasmic (Cyt) and nuclear (Nu) fractions of MRC-5 cells mock-infected (−) or infected (+) with HCoV-229E (0.1 TCID₅₀/cell) for 24 h. Antibodies against α-tubulin and histone H3 (Hist-H3) were used as loading controls for cytoplasmic and nuclear fractions, respectively. C Confocal images of pHSF1-Ser326 (red) and α-tubulin (green) intracellular localization in MRC-5 cells mock-infected or infected with HCoV-229E (1 TCID₅₀/cell) at 30 h p.i.. Nuclei are stained with Hoechst (blue). Merge and zoom images are shown. Scale bar, 20 μm (zoom, 5 μm). D Confocal 3D-reconstruction of pHSF1-Ser326 (red) intranuclear localization in MRC-5 cells mock-infected or infected as in C; α-tubulin is shown in green. Nuclei are stained with Hoechst (blue). The overlay of the fluorochromes is shown. E Confocal images of pHSF1-Ser326 (red) and α-tubulin (green) intracellular localization in MRC-5 cells mock-infected or infected with HCoV-OC43 (1 TCID₅₀/cell) at 30 h p.i.. Nuclei are stained with Hoechst (blue). Merge images are shown. Scale bar, 20 μm. F IB of pHSF1-Ser326, HSF1, N and β-actin protein levels in MRC-5 cells mock-infected or infected with HCoV-OC43 (0.1 TCID₅₀/cell) for 24 h (left panels). HSF1 monomers and trimers in the same samples are shown (right panel)