Citreoviridin Induces Autophagy-Dependent Apoptosis through Lysosomal-Mitochondrial Axis in Human Liver HepG2 Cells.

Yuexia Wang,Liping Jiang,Xiaofeng Yao,Qiujuan Li,Yanan Liu,Guang Yang,Xiaofang Liu,Xiance Sun,Min Chen,Chengyan Geng

doi:10.3390/toxins7083030

Abstract

Citreoviridin (CIT) is a mycotoxin derived from fungal species in moldy cereals. In our previous study, we reported that CIT stimulated autophagosome formation in human liver HepG2 cells. Here, we aimed to explore the relationship of autophagy with lysosomal membrane permeabilization and apoptosis in CIT-treated cells. Our data showed that CIT increased the expression of LC3-II, an autophagosome biomarker, from the early stage of treatment (6 h). After treatment with CIT for 12 h, lysosomal membrane permeabilization occurred, followed by the release of cathepsin D in HepG2 cells. Inhibition of autophagosome formation with siRNA against Atg5 attenuated CIT-induced lysosomal membrane permeabilization. In addition, CIT induced collapse of mitochondrial transmembrane potential as assessed by JC-1 staining. Furthermore, caspase-3 activity assay showed that CIT induced apoptosis in HepG2 cells. Inhibition of autophagosome formation attenuated CIT-induced apoptosis, indicating that CIT-induced apoptosis was autophagy-dependent. Cathepsin D inhibitor, pepstatin A, relieved CIT-induced apoptosis as well, suggesting the involvement of the lysosomal-mitochondrial axis in CIT-induced apoptosis. Taken together, our data demonstrated that CIT induced autophagy-dependent apoptosis through the lysosomal-mitochondrial axis in HepG2 cells. The study thus provides essential mechanistic insight, and suggests clues for the effective management and treatment of CIT-related diseases.

Highlights

Citreoviridin (CIT) is a toxic secondary metabolite derived from Penicillum citreonigrum, Aspergillus terreus and Eupenicillium ochrosalmoneum in moldy cereals, such as rice and corn [1].It has been shown that the consumption of CIT-contaminated yellow rice is associated with the occurrence of cardiac beriberi in Japan, and Keshan disease in China and South East Asian countries [2]
We reported that CIT stimulated autophagosome formation and caused autophagic cell death in HepG2 cells [5]
Autophagy blocks the induction of apoptosis, while apoptosis-associated caspase activation shuts off the autophagic process

Summary

Introduction

It has been shown that the consumption of CIT-contaminated yellow rice is associated with the occurrence of cardiac beriberi in Japan, and Keshan disease in China and South East Asian countries [2]. CIT interferes with nerve and muscle tissues metabolism by competitively inhibiting the absorption of vitamin B1, causing beriberi [3]. We reported that CIT stimulated autophagosome formation and caused autophagic cell death in HepG2 cells [5]. Autophagy and apoptosis regulate the turnover of organelles and proteins within cells. Autophagy blocks the induction of apoptosis, while apoptosis-associated caspase activation shuts off the autophagic process. In special cases, autophagy or autophagy-relevant proteins may induce apoptosis [6]. Autophagy and apoptosis can occur in the same cell, mostly in a sequence in which autophagy precedes apoptosis [7]

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