title: Epstein-Barr virus protein EB2 stimulates cytoplasmic mRNA accumulation by counteracting the deleterious effects of SRp20 on viral mRNAs.
abstract: The Epstein-Barr Virus (EBV) protein EB2 (also called Mta, SM and BMLF1), is an essential nuclear protein produced during the replicative cycle of EBV. EB2 is required for the efficient cytoplasmic accumulation of viral mRNAs derived from intronless genes. EB2 is an RNA-binding protein whose expression has been shown to influence RNA stability, splicing, nuclear export and translation. Using a yeast two-hybrid screen, we have identified three SR proteins, SF2/ASF, 9G8 and SRp20, as cellular partners of EB2. Then, by using siRNA to deplete cells of specific SR proteins, we found that SRp20 plays an essential role in the processing of several model mRNAs: the Renilla luciferase reporter mRNA, the human β-globin cDNA transcript and two EBV late mRNAs. These four mRNAs were previously found to be highly dependent on EB2 for their efficient cytoplasmic accumulation. Here, we show that SRp20 depletion results in an increase in the accumulation of these mRNAs, which correlates with an absence of additive effect of EB2, suggesting that EB2 functions by antagonizing SRp20. Moreover, by using RNA-immunoprecipitation assays we found that EB2 enhances the association of SRp20 with the β-globin transcript suggesting that EB2 acts by stabilizing SRp20's labile interactions with the RNA.
authors.affiliation: INSERM U758, Unité de Virologie Humaine, 69364 Lyon, France.
authors.forename: Franceline
authors.initials: F
authors.lastname: Juillard
authors.forename: Quentin
authors.initials: Q
authors.lastname: Bazot
authors.forename: Fabrice
authors.initials: F
authors.lastname: Mure
authors.forename: Lionel
authors.initials: L
authors.lastname: Tafforeau
authors.forename: Christophe
authors.initials: C
authors.lastname: Macri
authors.forename: Chantal
authors.initials: C
authors.lastname: Rabourdin-Combe
authors.forename: Vincent
authors.initials: V
authors.lastname: Lotteau
authors.forename: Evelyne
authors.initials: E
authors.lastname: Manet
authors.forename: Henri
authors.initials: H
authors.lastname: Gruffat
mesh_terms: D002467:Cell Nucleus / Q000821:virology; D003593:Cytoplasm / Q000378:metabolism / Q000821:virology; D015536:Down-Regulation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D049410:Luciferases, Renilla / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D012333:RNA, Messenger / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D055544:beta-Globins / Q000235:genetics
chemical_list: D009687:Nuclear Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; C090236:SM protein, Human herpesvirus 4; C491388:SRSF3 protein, human; D015534:Trans-Activators; D055544:beta-Globins; D000068103:Serine-Arginine Splicing Factors; D049410:Luciferases, Renilla