Fig. 1

Expression of ER stress associated protein and autophagy related protein induced by Tm or RAPA in human chondrocyte. a C28I2 cells were incubated with 10 μg/ml tunicamycin (Tm), a typical ER stress inducer, with the time intervals (0, 4, 8, 12, 16, 20 h). ER stress related proteins and autophagy associated proteins were analysed by western blotting. b Qualitative analysis of related proteins. The values were normalized to β-actin (Bio-Rad), as indicated, data were expressed as means±S.D. n = 3). Every treatment group compared with control groups, respectively, *P < 0.05, **P < 0.01. c C28I2 cells were treated with TM after 12 h and 24 h. ER stress related proteins and autophagy proteins were analysed by western blotting. Similar method with before. d The levels of related proteins were normalized to β-actin, data were expressed as means ± S.D. n = 3). Every treatment group compared with control groups, respectively, *P < 0.05, **P < 0.01. e Determination the expression of PERK,Nrf2 and ATF4 by western blotting after infected with siPERK1/2/3, siNrf2–1/2/3 and siATF4–1/2 in C28I2 cells. f The levels of related proteins were normalized to β-actin, data were expressed as means±S.D. n = 3). Every treatment group compared with control groups, respectively, *P < 0.05, **P < 0.01. g Determination of autophagy proteins expression by western blotting after infected with siPERK1, siNrf2–1in C28I2 cells. h The levels of related proteins were normalized to β-actin, data were expressed as means±S.D. n = 3). Every treatment group compared with control groups, respectively, *P < 0.05, **P < 0.01. i C28I2 cells were incubated with rapamycin(RAPA) (25 μM), a typical autophagy inducer, after 12 h and 24 h. ER stress related protein PERK, p-PERK and Nrf2 were detected by western blotting. j The levels of related proteins were normalized to β-actin. Every treatment group compared with control groups, respectively. Values are means ± SD (n = 3), *P < 0.05, **P < 0.01. (1:TM 0 h; 2:TM 4 h;3:TM 8 h;4:TM 12 h;5:TM 16 h; 6:TM 20 h; 7:TM 24 h; 8:NC;9: Ad-RFP(siRNA control); 10:Ad-siPERK; 11:Ad-siNrf2; 12: siPERK+siNrf2;13:RAPA 0 h;14:RAPA 12 h;15:RAPA 24 h. 1′:Ad-RFP, 2′:Ad-siPERK1,3′:Ad-siPERK2,4′:Ad-siPERK3, 5′:Ad-siNrf2–1, 6′:Ad-siNrf2–2; 7′:Ad-siNrf2–3; 8′:Ad-siATF4–1; 9′: Ad-siATF4–2)