Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

JNK pathway promotes hepatocyte apoptosis by inhibiting Bcl-2 and upregulating expressions of Bim, caspase-3 and caspase-9 after cardiopulmonary bypass

Haibin Yu¹, Haojie Zhang¹, Yan Cheng², Xian'en Fa¹ , Fangtao Zhu¹, Yachao Lin³, Weihua Huang¹

¹Department of Cardiac Surgery, The Second Affiliated Hospital of Zhengzhou University, 2 Jingba Rd; ²Department of Obstetrics and Gynecology, The First Affiliated Hospital of Zhengzhou University, 1 Jianshe East Rd, Zhengzhou 450014; ³Department of Interventional Radiology, The Second Affiliated Hospital of Zhengzhou University, 2 Jingba Rd, Zhengzhou 450014, China.

For correspondence:- Xian'en Fa Email: xianfan6022185@126.com

Accepted: 27 February 2020 Published: 31 March 2020

Citation: Yu H, Zhang H, Cheng Y, Fa X, Zhu F, Lin Y, et al. JNK pathway promotes hepatocyte apoptosis by inhibiting Bcl-2 and upregulating expressions of Bim, caspase-3 and caspase-9 after cardiopulmonary bypass. Trop J Pharm Res 2020; 19(3):519-524 doi: 10.4314/tjpr.v19i3.9

© 2020 The authors.
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Abstract

Purpose: To study the effect of Jun N-terminal kinase (JNK) signaling pathway on hepatocyte apoptosis in vivo and in vitro, and to elucidate the mechanism of action.

Methods: TdT-mediated dUTP Nick-End Labeling (TUNEL) method was used to determine apoptosis in control and cardiopulmonary bypass (CPB) groups at 0, 3 and 6 hours after rat surgery. The expressions of JNK and p-c-Jun in liver tissues at 0, 3 and 6 h after surgery, and the levels of p-c-Jun, Bcl-2 and Bim following overexpression of JNK, were determined using Western blot assay. Human liver cell line HL-7702 was cultured and transfected with over-expressed JNK plasmid and empty plasmid. Proliferation of HL-7702 cells after JNK over-expression was assessed by Cell Counting Kit-8 (CCK-8), while quantitative real-time polymerase chain reaction (RT-qPCR) was employed to evaluate mRNA expression levels of caspase-3 and caspase-9 mRNA after JNK over-expression. Apoptosis of the cells was determined by flow cytometry (FC) after JNK over-expression.

Results: FC results showed that the number of apoptotic hepatocytes increased after JNK over-expression in hepatocytes while TUNEL assay results demonstrated that hepatocyte apoptosis increased in CPB group, when compared to control group; furthermore, the number of apoptotic cells gradually increased within 6 h after surgery. The expressions of JNK and p-c-Jun were higher in CPB group than in control group, and increased gradually in both groups within 6 h after surgery. Overexpression of JNK decreased the proliferation of hepatocytes, and also lowered protein expression levels of p-c-Jun and Bim; on the other hand, the protein expression levels of Bcl-2 fell, while mRNA expression levels of caspase-3 and caspase-9 mRNA increased.

Conclusion: JNK pathway promotes hepatocyte apoptosis after cardiopulmonary bypass by inhibiting Bcl-2 pathway and promoting the expressions of Bim caspase-3 and caspase-9.

Keywords: Cardiopulmonary bypass, Apoptosis, JNK pathway, Bim, caspase-3 and caspase-9