Two autophagy-related proteins, ATG5 and ATG7, from Eriocheir sinensis involved into Spiroplasma eriocheiris infection

Abstract

Autophagy-related proteins (ATGs) play an important role in the immune process by regulating autophagy. Eriocheir sinensis tremor disease (TD) is the most hazardous disease caused by Spiroplasma eriocheiris. However, it is unclear whether ATGs play a role in the development of TD. In this study, the function of autophagy and ATG (ATG5 and ATG7) was investigated. Both E. sinensis ATG5 and ATG7 (EsATG5 and EsATG7) were highly transcribed in hemocytes. After S. eriocheiris infection, the transcriptions of EsATG5 and EsATG7 were significantly up-regulated in crab hemocytes. After gene silencing and S. eriocheiris infection, the mortality rate of E. sinensis and the copy number of S. eriocheiris in hemocytes were remarkably increased. These results suggested that EsATG5 and EsATG7 played an important immune role in S. eriocheiris infection. According to the result of western blot using polyclonal antibody of EsATG7, EsATG7 protein expression was increased in S. eriocheiris infection. Meanwhile, EsATG7 protein expression was considerably changed after stimulation with autophagy activator (Rapamycin, RM) and autophagy inhibitor (3-methyladenine, 3-Ma). These results shown EsATG7 was involved in autophagy. After S. eriocheiris infection, the cell activity of the RM group was significantly increased, the copy number of S. eriocheiris in RM group was decreased, while the results in the 3-Ma group were completely opposite. In conclusion, the EsATG gene through regulated E. sinensis autophagy to improve the host's immune ability to resist S. eriocheiris infection.