Hexavalent Chromium Induces Lysosomes Dysfunction And Curcumin Protection In Duck Hepatocytes Through The MTORC1/TFEB Pathway

In order to investigate the mechanism of hexavalent chromium Cr（Ⅵ）in inducing primary duck hepatocytes injury and the protective effect of curcumin（CUR）,potassium dichromate（K₂Cr₂O₇）was selected as the source of toxicity to construct an vitro duck hepatocyte injury model.Torin1,an inhibitor of mTOR,was selected to further investigate the role of mTORC1/TFEB and it mediated autophagy and lysosomes function in Cr（Ⅵ）-induced liver injury.Additionally,CUR with Cr（Ⅵ）was co-treated cells to analyze the protective effect of CUR.Firstly,the experiment established the control group,the 4μM Cr group（4μM Cr）,the 8μM Cr group（8μM Cr）,and exposed for 24 h,which preliminarily confirmed the effect of Cr（Ⅵ）on autophagy,lysosomes and hepatocytes.Then,the Cr+T group（8μM Cr+1 n M Torin1）,the Cr+CUR group（8μM Cr+20μM CUR）,the T group（1 n M Torin1）and the CUR group（20μM CUR）were subsequently added for 24 h.Hepatocytes morphology,lysosomal p H,TFEB nuclear translocation,LAMP1 and CTSD co-localization,LAMP2 and LC3 co-localization,and lysosomes and autophagy-related factors were observed.Results showed that Cr（Ⅵ）exposure reduced the expression levels of autophagy and lysosomal related factors in a concentration dependence,the levels of mTORC1 m RNA and p-mTOR protein increased significantly（P<0.01,P<0.001）,and the levels of TFEB m RNA and protein decreased markedly（P<0.05,P<0.01）.Then addition of Torin1 significantly reduced the increase of p-mTOR protein level and lysosomal p H by Cr（Ⅵ）（P<0.01）,and remarkably enhanced the levels of TFEB m RNA and protein,LAMP1 and CTSD co-localization,LAMP2 and LC3 co-localization,and autophagy and lysosomal correlated factors decreased by Cr（Ⅵ）（P<0.05,P<0.01,P<0.001）.Moreover,the addition of CUR is similar to the effect of Torin1 on Cr（Ⅵ）.In summary,Cr（Ⅵ）caused lysosomal dysfunction and autophagy inhibition in duck hepatocytes through the mTORC1/TFEB pathway.CUR can target mTORC1/TFEB to enhance lysosomal function and autophagy levels,thereby reducing Cr（Ⅵ） damage to duck hepatocytes.