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

To test this hypothesis, we assessed the expression of GRP78, a marker for ERS, in both whole-cell and ER fractions. Western blotting results indicate that, within 24 h, GRP78 accumulated both in the whole-cell and ER fractions, and its level markedly increased when the transfection time was extended to 72 h. In contrast, no accumulation of GRP78 was observed in HeLa cells not transfected with TMV-RNA ( Figure 6A ). These data indicate that TMV-RNA induces ERS; the accumulation of TMV protein in the ER induces ERS and activates GRP78 to bind to unfolded proteins (such as CP), thereby increasing their folding capacity. Once the abundance of these unfolded proteins exceeds the capacity of GRP78, ERS would further trigger a series of events, such as autophagy, to restore normal cell function.