The invasion of tobacco mosaic virus RNA induces endoplasmic reticulum stress-related autophagy in HeLa cells

Li, Li; Wang, Li; Xiao, Ruijing; Zhu, Guoguo; Li, Yan; Liu, Changxuan; Yang, Ru; Tang, Zhiqing; Li, Jie; Huang, Wei; Chen, Lang; Zheng, Xiaoling; He, Yuling; Tan, Jinquan

After we established a reliable transfection system, we monitored the morphological changes in HeLa cells after TMV-RNA transfection by light microscopy. At 24 h post-transfection, we found that some vacuoles were produced in the cytoplasm of the HeLa cells. After 72 h, the proportion of vacuoles was more than 50% per microscopic field of vision. To determine whether autophagy was triggered after transfection, the ultrastructure of HeLa cells transfected with TMV-RNA for 6, 24, 48 and 72 h was analysed by TEM. Numerous vacuoles and some membrane-bound vacuoles characteristic of autophagosomes (arrowheads) were observed in the cytoplasm of the transfected cells ( Figure 1C , T-6 h, T-24 h). Moreover, typical mature autophagosomes with double-membrane vacuolar structures containing visible cytoplasmic contents increased over time ( Figure 1C , T-48 h, T-72 h; Figure 1D ). Vacuoles were only rarely found in cells not transfected with TMV-RNA ( Figure 1C , Con), and only a few vacuoles were observed in cells incubated with liposomes only ( Figure 1C , Lipo). The latter result suggests that the quantity of liposomes administered was less toxic to cells.