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

ERS [ER (endoplasmic reticulum) stress], which is one of the typical stress responses initiated in cells after viral infection, is important in maintaining the physiology of healthy cells and functions to down-regulate protein synthesis in response to the build-up of unfolded proteins. The build-up of unfolded proteins is monitored by many ER protein chaperones, including GRP78 [glucose-regulated protein of 78 kDa, also called BiP (immunoglobulin heavy-chain-binding protein)]. GRP78 is located in the lumen of the ER, and in unstressed cells it binds to the luminal domains of three ER membrane-bound proteins: eukaryotic translation initiation factor 2-α kinase 3 {PERK [PKR (doublestranded-RNA-dependent protein kinase)-like ER kinase]}, IRE1 (inositol-requiring protein-1) and ATF6 (activating transcription factor-6). GRP78 functions as a major chaperone during protein folding and controls the activity of three major signalling pathways that originate from different ER transmembrane proteins [22, 23] .