LPS regulates macrophage autophagy through PI3 K/Akt/mTOR path-way / 中国病理生理杂志

ABSTRACT

AIM:To detect the activation of macrophage autophagy caused by lipopolysaccharide ( LPS) and the possible related signaling pathways .METHODS:The macrophage cell line RAW264.7 cultured in vitro was divided into 5 groups according to the culture environment , including normal culture group , starvation-activated sautophagy group , LPS group, LPS+PI3K inhibitor (hVps34) group and LPS+mTOR inhibitor (rapamycin) group.Fluorescent expression vector pcDNA3.1-GFP-LC3 constructed in previous work was transfected into the macrophages .The fluorescence microscopy was used to detect the formation of autophagosome .The mRNA expression of autophagy-associated genes Atg5, Atg7, LC3-II and Bnip3 in the macrophages was detected by qRT-PCR.The protein levels of LC3-II, p-Akt and p-mTOR were deter-mined by Western blotting , so as to evaluate the molecular pathways of autophagy in LPS-activated macrophages .RE-SULTSThe macrophages stably expressing GFP-LC3 were successfully established , which were used to observe the auto-phagy under fluorescence microscope .Compared with normal culture group , the autophagy in starvation group , LPS +hVps34 group and LPS+rapamycin group was significantly increased .The mRNA expression levels of Atg5, LC3-II and Bnip3 were significantly increased in starvation group , LPS+hVps34 group and LPS +rapamycin group , while in LPS group, those decreased slightly .The protein level of p-Akt in starvation group , LPS group and LPS+rapamycin group was significantly increased , while p-mTOR in starvation group , LPS+hVps34 group and LPS+rapamycin group significantly declined .LC3-II expression level in starvation group , LPS+hVps34 group and LPS+rapamycin group was higher than that in control group and LPS group .CONCLUSION: LPS regulates macrophage autophagy , and its possible pathway is the PI3K/Akt/mTOR pathway, but there are some other effective regulatory pathways .