Fig. 3: Bile acids upregulate Sestrin2 expression via an ATF4- and C/EBP-β-dependent mechanism.

A, B HepG2 cells were treated with 200 µM CDCA or 750 µM CA for the indicated times. Cell lysates were immunoblotted with anti-p-eIF2α, anti-eIF2α, and anti-ATF4 antibodies. C Immunofluorescence staining of PDI (green) in HepG2 cells treated with 200 µM CDCA or 750 µM CA for 9 h (n = 3–4). Nuclei were stained with DAPI (blue). Scale bars, 10 μm. D, E Liver tissues were collected from mice 3 days after sham or BDL surgery (n = 4–5 mice per group) and analyzed by immunoblotting with the indicated antibodies. Band intensities were quantified and normalized to GAPDH or total protein intensities. F Immunohistochemical analysis of BiP in liver tissues from mice 3 days after sham or BDL surgery (n = 4–5 mice per group). The boxed areas are magnified in the bottom panels. Scale bars, 50 μm; 10 μm (insets). G, H HepG2 cells were infected with lentiviruses expressing shRNAs targeting luciferase (sh-Luc) or ATF4 (sh-ATF4) and treated with 200 µM CDCA or 750 µM CA for 9 h. Cell lysates were immunoblotted with anti-Sestrin2 and anti-ATF4 antibodies. I, J HepG2 cells were infected with lentiviral sh-Luc or sh-C/EBP-β and treated with 200 µM CDCA or 750 µM CA for 9 h. Cell lysates were immunoblotted with anti-Sestrin2 and anti-C/EBP-β antibodies. GAPDH or β-actin served as loading controls. Numbers below the immunoblot bands indicate fold changes normalized to the control band intensities. The data are representative of one (D–F) or at least three (A–C, G–J) independent experiments. *p < 0.05; **p < 0.01; ***p < 0.001 (Student’s t test).