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

We also have some evidence (Supplementary Figure S1 ) to support this potential relationship among TMV-RNA, autophagosomes and the ER. We observed the locations of TMV-RNA, autophagosomes and the ER in live cells with a Zeiss LSM 510 Inverted Live-Cell Confocal System. TMV-RNA was labelled with CTAB-QDs (red) [45] , autophagosomes were labelled with GFP-LC3 (green) and the ER was stained with ER tracker (blue). At 4 h post-transfection with TMV-RNA, we observed TMV-RNA as red dots and the ER as blue fluorescence. The formation of GFP-LC3-labelled structures (GFP-LC3 dots), representing autophagosomes was observed in cells, as was the conversion of LC3-I into LC3-II. Notably, the red dots co-localized with some punctate GFP-LC3 staining, and they also appeared in conjunction with the ER (blue) (Supplementary Figure S1B) , whereas the GFP-LC3 dots decreased in cells transfected with GFP-LC3 alone (Supplementary Figure S1A) . Hence TMV-RNA might colocalize with autophagosomes on the ER. This result indicates a direct connection among TMV-RNA, autophagosomes and the ER, a result that is also supported by the previous data showing that autophagosomes appear to originate from the ER membrane. Because the process occurred in a short period of time, we have to consider that autophagy might play a vital role in cellular innate immunity, especially against mutated viruses.