Figure 4.

Tunicamycin or thapsigargin treatment induces phenotypic switching in vascular smooth muscle cells (SMCs) independent of cholesterol. A and B, Exposure to 0.5 or 1 µg/mL tunicamycin (TM) for 5 h upregulates macrophage markers and Krüppel-like factor 4 (Klf4), and these increases are successfully reversed by ISRIB (integrated stress response inhibitor) treatment both at the mRNA (A) and protein (B) levels. C, TM treatment increases Klf4 transcriptional activity in a dose-dependent manner and this increase is reversed by ISRIB treatment. D, Treatment with 0.5 or 1µmol/L thapsigargin (TG) for 8 h induces phenotypic switching in SMCs but does not affect Klf4 expression. E, TG treatment causes a dose-dependent increase in the transcriptional activity of Klf4. Each result displayed here is representative of at least 3 independent biological replicates. P values were calculated using 2-way ANOVA followed by Tukey post hoc test. *P<0.05 or **P<0.01 vs no drug treatment (DMSO). #P<0.05 or ##P<0.01 for TM+ISRIB treatment vs TM treatment only. Lgals3 indicates lectin, galactoside-binding, soluble, 3.