title: Rotavirus NSP3 Is a Translational Surrogate of the Poly(A) Binding Protein-Poly(A) Complex.
abstract: Through its interaction with the 5' translation initiation factor eIF4G, poly(A) binding protein (PABP) facilitates the translation of 5'-capped and 3'-poly(A)-tailed mRNAs. Rotavirus mRNAs are capped but not polyadenylated, instead terminating in a 3' GACC motif that is recognized by the viral protein NSP3, which competes with PABP for eIF4G binding. Upon rotavirus infection, viral, GACC-tailed mRNAs are efficiently translated, while host poly(A)-tailed mRNA translation is, in contrast, severely impaired. To explore the roles of NSP3 in these two opposing events, the translational capabilities of three capped mRNAs, distinguished by either a GACC, a poly(A), or a non-GACC and nonpoly(A) 3' end, have been monitored after electroporation of cells expressing all rotavirus proteins (infected cells) or only NSP3 (stably or transiently transfected cells). In infected cells, we found that the magnitudes of translation induction (GACC-tailed mRNA) and translation reduction [poly(A)-tailed mRNA] both depended on the rotavirus strain used but that translation reduction not genetically linked to NSP3. In transfected cells, even a small amount of NSP3 was sufficient to dramatically enhance GACC-tailed mRNA translation and, surprisingly, to slightly favor the translation of both poly(A)- and nonpoly(A)-tailed mRNAs, likely by stabilizing the eIF4E-eIF4G interaction. These data suggest that NSP3 is a translational surrogate of the PABP-poly(A) complex; therefore, it cannot by itself be responsible for inhibiting the translation of host poly(A)-tailed mRNAs upon rotavirus infection.
  
  
  OBJECTIVE
  To control host cell physiology and to circumvent innate immunity, many viruses have evolved powerful mechanisms aimed at inhibiting host mRNA translation while stimulating translation of their own mRNAs. How rotavirus tackles this challenge is still a matter of debate. Using rotavirus-infected cells, we show that the magnitude of cellular poly(A) mRNA translation differs with respect to rotavirus strains but is not genetically linked to NSP3. Using cells expressing rotavirus NSP3, we show that NSP3 alone not only dramatically enhances rotavirus-like mRNA translation but also enhances poly(A) mRNA translation rather than inhibiting it, likely by stabilizing the eIF4E-eIF4G complex. Thus, the inhibition of cellular polyadenylated mRNA translation during rotavirus infection cannot be attributed solely to NSP3 and is more likely the result of global competition between viral and host mRNAs for the cellular translation machinery.
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Gratia
authors.affiliation: INSERM UMR-1037-Université de Toulouse III-Paul Sabatier, Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer (TOUCAN), Toulouse Cedex 1, France.
authors.forename: Emeline
authors.initials: E
authors.lastname: Sarot
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Vende
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France.
authors.forename: Annie
authors.initials: A
authors.lastname: Charpilienne
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France.
authors.forename: Carolina Hilma
authors.initials: CH
authors.lastname: Baron
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France Université d'Evry Val d'Essonne, Département de Biologie, Evry Cedex, France.
authors.forename: Mariela
authors.initials: M
authors.lastname: Duarte
authors.affiliation: INSERM UMR-1037-Université de Toulouse III-Paul Sabatier, Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer (TOUCAN), Toulouse Cedex 1, France stephane.pyronnet@inserm.fr didier.poncet@i2bc.paris-saclay.fr.
authors.forename: Stephane
authors.initials: S
authors.lastname: Pyronnet
authors.affiliation: Institut de Biologie Integrative de la Cellule (I2BC), UMR 9198, Département de Virologie, USC INRA 1358, Gif sur Yvette, France stephane.pyronnet@inserm.fr didier.poncet@i2bc.paris-saclay.fr.
authors.forename: Didier
authors.initials: D
authors.lastname: Poncet
mesh_terms: D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D018274:Electroporation; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008253:Macaca mulatta; D011061:Poly A / Q000235:genetics; D039102:Poly(A)-Binding Proteins / Q000378:metabolism*; D026723:Polyadenylation / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D014176:Protein Biosynthesis / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D012401:Rotavirus / Q000235:genetics; D012400:Rotavirus Infections / Q000821:virology; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; C082740:NSP3 protein, Rotavirus; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; D011061:Poly A