Foot-and-Mouth Disease Virus Counteracts on Internal Ribosome Entry Site Suppression by G3BP1 and Inhibits G3BP1-Mediated Stress Granule Assembly via Post-Translational Mechanisms
Authors: Haixue Zheng
Liurong Fang
Huanchun Chen
Xinyu Zhu
Shaobo Xiao
Jun Ma
Keshan Zhang
Yanling Shi
Dang Wang
Xu Ye
Kui Li
Ting Pan
Journal: Frontiers in Immunology (2018)
Discipline: IMMUNOLOGY
Keywords: G3BP stress granule assembly factor 1; foot-and-mouth disease virus; innate immunity; internal ribosome entry site; phosphoproteomics.
Affiliations: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China., The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China., National Foot and Mouth Diseases Reference Laboratory, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China., Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, United States.

Abstract:  Foot-and-mouth disease (FMD) is a highly contagious, severe viral illness notifiable to the World Organization for Animal Health. The causative agent, FMD virus (FMDV), replicates rapidly and efficiently inhibits host translation and the innate immune response for it has developed multiple tactics to evade host defenses and takes over gene expression machinery in the host cell. Here, we report a systemic analysis of the proteome and phosphoproteome of FMDV-infected cells. Bioinformatics analysis suggested that FMDV infection shuts off host cap-dependent translation, but leaves intact internal ribosome entry site (IRES)-mediated translation for viral proteins. Interestingly, several FMDV IRES-transacting factors, including G3BP stress granule assembly factor 1 (G3BP1), were dephosphorylated during FMDV infection. Ectopic expression of G3BP1 inhibited FMDV IRES activity, promoted assembly of stress granules, and activated innate immune responses, collectively suppressing FMDV replication. To counteract these host protective responses, FMDV-induced dephosphorylation of G3BP1, compromising its inhibitory effect on viral IRES. In addition, FMDV also proteolytically cleaved G3BP1 by its 3C protease (3Cpro). G3BP1 was cleaved at glutamic acid-284 (E284) by FMDV 3Cpro, and this cleavage completely lost the abilities of G3BP1 to activate innate immunity and to inhibit FMDV replication. Together, these data provide new insights into the post-translational mechanisms by which FMDV limits host stress and antiviral responses and indicate that G3BP1 dephosphorylation and its proteolysis by viral protease are important factors in the failure of host defense against FMDV infection. 

Retracted: No

PubPeer comments:
 Figure 6: Western Blot with 5 lanes for G3BP1 and for beta-actin control ![file] , 
 Dear Heterochasta Lasioplaca, Thank you very much for pointing out this error in Fig 6A in our article. We checked the raw data and found that we accidentally cropped the control group, so there is a control group missing from the Western blot experiment for detecting Flag-G3BP1 (as shown in the raw data, and the edge of the membrane can be seen in the long exposure). As shown in the raw data, lane 1 was used to demonstrate that the specific bands detected by Western blot were the ectopic expression of Flag-G3BP1, as the same background noise was present in lane 1 as in lanes 2-6 (compared to blank lanes), but no specific bands were detected in lane 1. Although this error does not affect the conclusions of this article, we apologize for this careless error, which should have been found before submission. We have submitted a corrigendum to the journal. We would like to apologize once again for any confusion this unintentional mistake may have caused. Thank you again for raising this concern. Kind regards, Jun Ma The raw data: , 
 Dear Heterochasta Lasioplaca, Thank you very much for pointing out this error in Fig 6A in our article. We checked the raw data and found that we accidentally cropped the control group, so there is a control group missing from the Western blot experiment for detecting Flag-G3BP1 (as shown in the raw data, and the edge of the membrane can be seen in the long exposure). As shown in the raw data, lane 1 was used to demonstrate that the specific bands detected by Western blot were the ectopic expression of Flag-G3BP1, as the same background noise was present in lane 1 as in lanes 2-6 (compared to blank lanes), but no specific bands were detected in lane 1. Although this error does not affect the conclusions of this article, we apologize for this careless error, which should have been found before submission. We have submitted a corrigendum to the journal. We would like to apologize once again for any confusion this unintentional mistake may have caused. Thank you again for raising this concern. Kind regards, Jun Ma The raw data: ![file] The revised Fig.6A: ![file] ,