title: p54nrb/NonO and PSF promote U snRNA nuclear export by accelerating its export complex assembly.
abstract: The assembly of spliceosomal U snRNPs in metazoans requires nuclear export of U snRNA precursors. Four factors, nuclear cap-binding complex (CBC), phosphorylated adaptor for RNA export (PHAX), the export receptor CRM1 and RanGTP, gather at the m(7)G-cap-proximal region and form the U snRNA export complex. Here we show that the multifunctional RNA-binding proteins p54nrb/NonO and PSF are U snRNA export stimulatory factors. These proteins, likely as a heterodimer, accelerate the recruitment of PHAX, and subsequently CRM1 and Ran onto the RNA substrates in vitro, which mediates efficient U snRNA export in vivo. Our results reveal a new layer of regulation for U snRNA export and, hence, spliceosomal U snRNP biogenesis.
authors.affiliation: Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan and RIKEN Center for Developmental Biology, Kobe, Hyogo 650-0047, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Izumi
authors.forename: Asako
authors.initials: A
authors.lastname: McCloskey
authors.forename: Kaori
authors.initials: K
authors.lastname: Shinmyozu
authors.forename: Mutsuhito
authors.initials: M
authors.lastname: Ohno
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000378:metabolism; D034521:Nuclear Matrix-Associated Proteins / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism*; D050810:Octamer Transcription Factors / Q000378:metabolism*; D000072670:PTB-Associated Splicing Factor; D010750:Phosphoproteins / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D014981:Xenopus; D020931:ran GTP-Binding Protein / Q000378:metabolism; D000097606:Exportin 1 Protein
chemical_list: D004268:DNA-Binding Proteins; D028884:Karyopherins; D034521:Nuclear Matrix-Associated Proteins; D029543:Nucleocytoplasmic Transport Proteins; D050810:Octamer Transcription Factors; D000072670:PTB-Associated Splicing Factor; D010750:Phosphoproteins; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D020931:ran GTP-Binding Protein; D000097606:Exportin 1 Protein; C083214:NONO protein, human; C498688:PHAX protein, human