Fig. 6: Effect of the transcription factor Sp1 on ferroptosis during CVB3 infection.

A The mRNA level of Sp1 at different CVB3 infection times was detected via qPCR. B The protein level of Sp1 at different CVB3 infection times was recorded via western-blotting. C Measurement of the relative gray values of Sp1 in the WB analysis was conducted using ImageJ. D CVB3 fluorescence in the SP1 knockdown and overexpression groups was determined via IFA. Cell nuclei were stained with DAPI (blue) (scale bar = 50 μm). E Cell viability in the SP1 knockdown group was obviously increased at 48 h postinfection, based on CCK-8 assay results. F Cell viability in the Sp1 overexpression group was also decreased at 48 h postinfection. G MDA concentrations were determined with Lipid Peroxidation MDA Assay Kit in the Sp1 knockdown and overexpression groups. H, I Iron concentrations were measured in the SP1 knockdown and overexpression groups using an Iron Assay Kit. J The fluorescescence of lipid ROS in the SP1 knockdown group was detected using the BODIPY581/591C11 probe (scale bar = 100 μm). K Percentage of oxidized/non-oxidized cells were calculated by ImageJ software according to figure J. It suggested that siSP1 could decreased the oxidized lipid ROS significantly (p < 0.001). L, M The effect of Sp1 overexpression and knockdown on ACSL4 and GPX4 mRNA expression was determined by qPCR. N, O Relative gray value and images of western-blotting in the effect of knockdown Sp1 on ACSL4 and GPX4 protein expression. P, Q Images of western-blotting and relative gray values in the effect of overexpression Sp1 on ACSL4 and GPX4 protein expression. R Schematic illustrating the mechanism by which the Sp1/TFRC/Fe²⁺ cascade facilitates ferroptosis in CVB3-infected HeLa cells. All results are expressed as the mean ± SD. ANOVA was used for comparison between groups. *p < 0.05, **p < 0.01, ***p < 0.001.