title: Association of the breast cancer protein MLN51 with the exon junction complex via its speckle localizer and RNA binding module.
abstract: MLN51 is a nucleocytoplasmic shuttling protein that is overexpressed in breast cancer. The function of MLN51 in mammals remains elusive. Its fly homolog, named barentsz, as well as the proteins mago nashi and tsunagi have been shown to be required for proper oskar mRNA localization to the posterior pole of the oocyte. Magoh and Y14, the human homologs of mago nashi and tsunagi, are core components of the exon junction complex (EJC). The EJC is assembled on spliced mRNAs and plays important roles in post-splicing events including mRNA export, nonsense-mediated mRNA decay, and translation. In the present study, we show that human MLN51 is an RNA-binding protein present in ribonucleo-protein complexes. By co-immunoprecipitation assays, endogenous MLN51 protein is found to be associated with EJC components, including Magoh, Y14, and NFX1/TAP, and subcellular localization studies indicate that MLN51 transiently co-localizes with Magoh in nuclear speckles. Moreover, we demonstrate that MLN51 specifically associates with spliced mRNAs in co-precipitation experiments, both in the nucleus and in the cytoplasm, at the position where the EJC is deposited. Most interesting, we have identified a region within MLN51 sufficient to bind RNA, to interact with Magoh and spliced mRNA, and to address the protein to nuclear speckles. This conserved region of MLN51 was therefore named SELOR for speckle localizer and RNA binding module. Altogether our data demonstrate that MLN51 associates with EJC in the nucleus and remains stably associated with mRNA in the cytoplasm, suggesting that its overexpression might alter mRNA metabolism in cancer.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département de Pathologie Moléculaire, UPR 6520 CNRS/U596 INSERM/Université Louis Pasteur, BP 10142, 67404 Illkirch, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Degot
authors.forename: Hervé
authors.initials: H
authors.lastname: Le Hir
authors.forename: Fabien
authors.initials: F
authors.lastname: Alpy
authors.forename: Valérie
authors.initials: V
authors.lastname: Kedinger
authors.forename: Isabelle
authors.initials: I
authors.lastname: Stoll
authors.forename: Corinne
authors.initials: C
authors.lastname: Wendling
authors.forename: Bertrand
authors.initials: B
authors.lastname: Seraphin
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Rio
authors.forename: Catherine
authors.initials: C
authors.lastname: Tomasetto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D017124:Conserved Sequence; D003593:Cytoplasm / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D005091:Exons; D005399:Fishes; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D007163:Immunosorbent Techniques; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection; D014981:Xenopus; D015027:Zebrafish
chemical_list: C459802:CASC3 protein, human; C491494:MAGOH protein, human; C491493:Magoh protein, mouse; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D012313:RNA