Role of PI3K/Akt/mTOR Signaling Pathway in Autophagy of Rat Hepatic Stellate Cells Induced by Lipopolysaccharide
CUI Yongjia1, XU Junquan2*, WANG Meijiao2, WU Huiwen2, WANG Mingliang2, SONG Binyu2, LIU Xiaoliang2
This work was to investigate the role of phosphatidylinositol 3-kinase (PI3K)/protein kinase B(Akt)/mammalian target of rapamycin (mTOR) signaling pathway in the lipopolysaccharide (LPS)-induced autophagy of rat hepatic stellate cells. HSC-T6 cells were cultured in vitro and randomly divided into control group, LPS group, Rapa group, LPS+Rapa group, LY294002 group, LPS+LY294002 group, SC79 group and LPS+SC79 group. After treatment, the changes of autophagic lysosome were observed by mono-dansylcadaverine (MDC) staining; the expression of microtubule-associated protein light chain II (LC3 II) was detected by immunofluorescence assay; the expressions of p-Akt, p-mTOR, Akt, mTOR, LC3 II and Beclin1 in each group were detected by Western blot; the expressions of LC3 II and Beclin1 mRNA in each group were detected by qRT-PCR. The results showed that there were no significant differences in the levels of autophagic lysosome and LC3 II fluorescent spots in comparison between LPS group and LPS+Rapa group, or LPS+LY294002 group (P>0.05), but the levels of autophagic lysosome and LC3 II fluorescent spots particles in LPS+SC79 group were significantly lower than those in LPS group (P<0.05). Western blot showed that there were no significant differences in the levels of LC3 II, Beclin1, p-Akt and p-mTOR in comparison between LPS group and LPS+Rapa group, or LPS+LY294002 group (P>0.05), but the levels of LC3 II and Beclin1 in LPS+SC79 group were significantly lower than those in LPS group, and the levels of p-Akt and p-mTOR protein were significantly increased (P<0.05). qRT-PCR showed that there were no significant differences in the expressions of LC3 II and Beclin1 mRNA in comparison between LPS group and LPS+Rapa group, or LPS+LY294002 group (P>0.05), but the expressions of LC3 II and Beclin1 mRNA were significantly decreased in LPS+SC79 group compared with LPS group (P<0.05). It is possibly that LPS promote autophagy in HSC-T6 cells by inhibiting PI3K/Akt/mTOR signaling pathway.
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