Cr(VI)-Induced Autophagy Protects L-02 Hepatocytes from Apoptosis Through the ROS-AKT-mTOR Pathway.
Cell Physiol Biochem
; 51(4): 1863-1878, 2018.
Article
em En
| MEDLINE
| ID: mdl-30504711
ABSTRACT
BACKGROUND/AIMS:
Hexavalent chromium [Cr(VI)] pollution has become a global concern for both ecosystems and human health. Our previous study revealed Cr(VI) could induce both apoptosis and autophagy in L-02 hepatocytes. Here, we sought to explore the underlying mechanism of Cr(VI)-induced autophagy and its exact role in cell death.METHODS:
Autophagy ultrastructure was observed under transmission electron microscope (TEM), autophagy flux was measured with double-tagged mCherry-green fluorescent protein (GFP)-microtubule-associated protein 1 light chain 3 (LC3) assay, long-lived protein degradation assay, and LC3II expression assay in the presence of lysosomal inhibitor, bafilomycin A1 (BafA1). Reactive oxygen species (ROS) level was determined using fluorescent probe dichloro-dihydrofluorescein diacetate (DCFH-DA). The expression levels of Beclin-1, LC3, p62/ SQSTM1, and AKT-mammalian target of rapamycin (mTOR) pathway-related molecules including phosphorylation (p)-AKT, AKT, p-mTOR, and mTOR were examined using real-time polymerase chain reaction (RT-PCR) and western blotting. Apoptosis was determined using Annexin V- fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining.RESULTS:
Our results demonstrated Cr(VI) exposure activated autophagy in L-02 hepatocytes, as evidenced by the accumulation of autophagosomes, the increase of LC3-II and degradation of p62/ SQSTM1, and the enhanced overall degradation of proteins. We also confirmed Cr(VI)-induced LC3-II elevation mainly came from autophagy induction rather than lysosomal degradation impairment. ROS-AKT-mTOR pathway was associated with Cr(VI)-induced autophagy, and ROS scavenger N-acetylcysteine (NAC) pretreatment inhibited Cr(VI)-induced autophagy by alleviating the inhibition of the AKT-mTOR pathway. Autophagy inhibitors 3-methyladenine (3-MA) and chloroquine diphosphate (CDP) promoted Cr(VI)-induced apoptotic death.CONCLUSION:
These findings indicated Cr(VI)-induced autophagy protected L-02 hepatocytes from apoptosis through the ROS-AKT-mTOR pathway.Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Autofagia
/
Transdução de Sinais
/
Cromo
/
Apoptose
/
Hepatócitos
Limite:
Humans
Idioma:
En
Revista:
Cell Physiol Biochem
Assunto da revista:
BIOQUIMICA
/
FARMACOLOGIA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
China