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

These studies provide some clues into the pathway of TMV-RNA-induced autophagy. Once the TMV-RNA enters HeLa cells, it first synthesizes proteins in the ER, as evidenced by CP in the ER. With the accumulation of TMV proteins in the ER, cells Analysis of these micrographs revealed that most of the ER membranes in TMV-RNA-transfected cells were in a state of expansion, and numerous vacuoles, including nascent vacuoles and typical autophagosomes with double-membrane vacuolar structures containing visible cytoplasmic contents, appeared around the expanded ER. The distal end of the ER membrane expanded to resemble swollen fingers or forks, which was seldom observed in controls (a). As shown in the images, the distal end of the ER membrane expanded towards the anterior vacuole (b, box); An ER membrane that expanded to resemble swollen fingers might have just sequestered a vacuole (c, box, arrowheads); another distal ER membrane end expanded towards the anterior vacuole and appeared to encapsulate it (d, box). The other distal end of the expanded ER membrane just sequestered a vacuole (d, arrowheads), and the ER membrane was so extremely expanded that it might have produced more vacuoles (e, arrowheads). Nascent vacuoles emerging from the end point of expanded ER membranes (f, box, arrowheads) and fusion events might have occurred between lysosomes and autophagic vacuoles (f, box). Finally, a huge autolysosome was formed in the cytoplasm, partial ER membranes expanded to resemble forks (g, two small boxes), and one vacuole was just sequestered from other partial ER membranes (g, arrowheads) (scale bar: 2 μm). From these micrographs, we presume that ERS stimulated the expansion of the ER, resulting in the formation of autophagosomes.