Induction of endoplasmic reticulum-derived oxidative stress by an occult infection related S surface antigen variant

Figure 3 Induction of endoplasmic reticulum stress and intracellular calcium levels by an occult infection related hepatitis B virus S surface antigen variant (KD). After transient transfection of plasmids (MOCK, NOR, and KD) into HuH-7 cells, up-regulation of the seven main endoplasmic reticulum (ER) stress-related proteins, namely, IRE1, ATF6, PERK, elF2, XBP1, CHOP, and GRP 78, was confirmed using Western blot in the absence (A) and presence (B) of 1 μmol/L thapsigargin (TG); C: Effect of the ER stress inhibitor salubrinal (70 μmol/L) on HBsAg variant-induced activation of ER stress-related proteins (IRE1, ATF6, and PERK). D: After transient transfection, Ca²⁺ was measured using Rhod-2-AM. The mean values are presented in the graphic (all data were confirmed using green fluorescent protein and Western blot to determine transfection efficiency). The relative intensity was determined, and all data are expressed as the mean ± SD within a group. Data from the three experiments were compared using Tukey’s multiple post-hoc test (^aP < 0.05, ^bP < 0.01 vs control).