Dephosphorylation of HuR Protein during Alphavirus Infection Is Associated with HuR Relocalization to the Cytoplasm |
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Authors: | Alexa M Dickson John R Anderson Michael D Barnhart Kevin J Sokoloski Lauren Oko Mateusz Opyrchal Evanthia Galanis Carol J Wilusz Thomas E Morrison Jeffrey Wilusz |
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Institution: | From the ‡Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80523.;the ¶Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado 80045.;the ‖Department of Oncology, Division of Medical Oncology, Mayo Clinic, Rochester, Minnesota 55905, and ;the §Department of Biology, Indiana University, Bloomington, Indiana 47405 |
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Abstract: | We have demonstrated previously that the cellular HuR protein binds U-rich elements in the 3′ untranslated region (UTR) of Sindbis virus RNA and relocalizes from the nucleus to the cytoplasm upon Sindbis virus infection in 293T cells. In this study, we show that two alphaviruses, Ross River virus and Chikungunya virus, lack the conserved high-affinity U-rich HuR binding element in their 3′ UTRs but still maintain the ability to interact with HuR with nanomolar affinities through alternative binding elements. The relocalization of HuR protein occurs during Sindbis infection of multiple mammalian cell types as well as during infections with three other alphaviruses. Interestingly, the relocalization of HuR is not a general cellular reaction to viral infection, as HuR protein remained largely nuclear during infections with dengue and measles virus. Relocalization of HuR in a Sindbis infection required viral gene expression, was independent of the presence of a high-affinity U-rich HuR binding site in the 3′ UTR of the virus, and was associated with an alteration in the phosphorylation state of HuR. Sindbis virus-induced HuR relocalization was mechanistically distinct from the movement of HuR observed during a cellular stress response, as there was no accumulation of caspase-mediated HuR cleavage products. Collectively, these data indicate that virus-induced HuR relocalization to the cytoplasm is specific to alphavirus infections and is associated with distinct posttranslational modifications of this RNA-binding protein. |
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Keywords: | Nuclear Transport RNA Binding Protein RNA Turnover RNA Viruses Virology Alphavirus Nuclear-Cytoplasmic Shuttling |
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