CHOP Regulates Endoplasmic Reticulum Stress-Mediated Hepatoxicity Induced by Monocrotaline.

Yazhou Guo,Chen Yang,Baoyu Zhao,Shuai Wang,Yongxia Su,Ruijie Huang,Rong Guo,Chonghui Mo,Jianguo Wang,Yezi Kong,Chengjian Tan,Chenchen Wu

doi:10.3389/fphar.2021.685895

Abstract

Monocrotaline (MCT), a pyrrolizidine alkaloid, is the major toxin in Crotalaria, which causes cell apoptosis in humans and animals. It has been reported that the liver is a vulnerable target of MCT. However, the exact molecular mechanism of the interaction between endoplasmic reticulum (ER) stress and liver injury induced by MCT is still unclear. In this study, the cytotoxicity of MCT on primary rat hepatocytes was analyzed by a CCK-8 assay and Annexin V-FITC/PI assay. Protein expression was detected by western blotting and immunofluorescence staining. As a result, MCT significantly decreased the cell viability and mediated the apoptosis of primary rat hepatocytes. Meanwhile, MCT could also induce ER stress in hepatocytes, indicated by the expression of ER stress-related proteins, including GRP78, p-IRE1α, ATF6, p-eIF2α, ATF4, and CHOP. Pretreatment with 4-PBA, an inhibitor of ER stress, or knockdown of CHOP by siRNA could partly enhance cell viability and relieve the apoptosis. Our findings indicate that ER stress is involved in the hepatotoxicity induced by MCT, and CHOP plays an important role in this process.

Highlights

Pyrrolizidine alkaloids (PAs) are a common group of chemical constituents, and more than 660 PAs and PA N-oxides have been identified
Our findings indicate that endoplasmic reticulum (ER) stress is involved in the hepatotoxicity induced by MCT, and CHOP plays an important role in this process
While our previous study suggested that MCT could induce ER stress in rat livers (Guo et al, 2020), it is not known whether ER stress participates in MCT-induced hepatocyte apoptosis as well

Summary

INTRODUCTION

Pyrrolizidine alkaloids (PAs) are a common group of chemical constituents, and more than 660 PAs and PA N-oxides have been identified. Hepatotoxicity is a hallmark of PAs and about half of them are poisonous compounds affecting livestock, wildlife, and humans (Wiedenfeld, 2011; Xia et al, 2016). Numerous MCT poisoning cases have been reported in livestock and humans While our previous study suggested that MCT could induce ER stress in rat livers (Guo et al, 2020), it is not known whether ER stress participates in MCT-induced hepatocyte apoptosis as well. We confirmed that ER stress was involved in MCT-induced hepatotoxicity. We further demonstrated that CHOP was a vital factor for apoptosis when treating MCT

MATERIALS AND METHODS

RESULT

DISCUSSION

CONCLUSION

Findings

ETHICS STATEMENT