[The role of PERK-eIF2α-ATF4-CHOP pathway in the apoptosis of TM4 cells induced by bisphenol A].

Objective: To investigate the effects of bisphenol A(BPA) on the proliferation and apoptosis of mouse testicular sertoli cells(TM4 cells) and the role of PERK-eIF2α-ATF4-CHOP pathway.

Methods: TM4 cells were treated with different concentrations of BPA(0, 25, 50, 100 μmol/L) and 100 μmol/L BPA combined with protein kinase R-like ER kinase(PERK) inhibitor GSK2656157 for 24 h, and the apoptosis of TM4 cells was observed by TUNEL staining. The expression levels of Bax, Bcl-2, cleaved Caspase-3, GRP78 and PERK-eIF2α-ATF4-CHOP pathway-related proteins were detected by Western blot.

Results: The apoptosis rate of TM4 cells in 25, 50 and 100 μmol/L BPA exposed groups was increased to 3.31%±0.34%, 7.51%±1.10% and 14.58%±0.91%, respectively, which was significantly higher than that in control group(0.73%±0.03%, P<0.05). Compared with the control group(1.00), cleaved Caspase-3 protein expression of TM4 cells in the 25, 50 and 100 μmol/L BPA exposed groups increased to 1.49±0.11, 1.59±0.12, 2.42±0.24, respectively; the ratio of Bax/Bcl-2 increased to 2.06±0.19, 3.94±0.034, 6.14±0.71, respectively; the protein expression of GRP78 increased to 1.29±0.06, 1.39±0.06, 1.92±0.17, respectively; the expression of p-PERK protein was increased to 1.64±0.03, 2.52±0.09, 2.80±0.11, respectively; the expression of p-eIF2α protein was increased to 1.79±0.05, 2.48±0.10, 4.77±0.32, respectively; ATF4 protein expression was increased to 2.51±0.03, 3.24±0.14 and 7.45±0.51, respectively; CHOP protein expression was increased to 1.44±0.01, 3.20±0.11 and 3.80±0.11, respectively, and all the differences were statistically significant(P<0.05). Compared to 100 μmol/L BPA group, the expression level of p-PERK, p-eIF2α, ATF4, CHOP, cleaved Caspase-3 protein and the ratio of Bax/Bcl-2 in 100 μmol/L BPA+10 μmol/L GSK2656157 group were decreased to 2.17±0.11, 1.81±0.13, 1.71±0.23, 2.18±0.22, 1.43±0.03, 2.22±0.13, respectively; the apoptosis rate of TM4 cells was also decreased to 7.28%±0.47%, all the differences were statistically significant(P<0.05).

Conclusion: BPA can induce apoptosis of TM4 cells by activating endoplasmic reticulum stress and regulating PERK-eIF2α-ATF4-CHOP pathway.