title: Assembly of an export-competent mRNP is needed for efficient release of the 3'-end processing complex after polyadenylation.
abstract: Before polyadenylated mRNA is exported from the nucleus, the 3'-end processing complex is removed by a poorly described mechanism. In this study, we asked whether factors involved in mRNP maturation and export are also required for disassembly of the cleavage and polyadenylation complex. An RNA immunoprecipitation assay monitoring the amount of the cleavage factor (CF) IA component Rna15p associated with poly(A)(+) RNA reveals defective removal of Rna15p in mutants of the nuclear export receptor Mex67p as well as other factors important for assembly of an export-competent mRNP. In contrast, Rna15p is not retained in mutants of export factors that function primarily on the cytoplasmic side of the nuclear pore. Consistent with a functional interaction between Mex67p and the 3'-end processing complex, a mex67 mutant accumulates unprocessed SSA4 transcripts and exhibits a severe growth defect when this mutation is combined with mutation of Rna15p or another CF IA subunit, Rna14p. RNAs that become processed in a mex67 mutant have longer poly(A) tails both in vivo and in vitro. This influence of Mex67p on 3'-end processing is conserved, as depletion of its human homolog, TAP/NXF1, triggers mRNA hyperadenylation. Our results indicate a function for nuclear mRNP assembly factors in releasing the 3'-end processing complex once polyadenylation is complete.
authors.affiliation: Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology, Aarhus University, DK-8000 Aarhus C., Denmark.
authors.forename: Xiangping
authors.initials: X
authors.lastname: Qu
authors.forename: Søren
authors.initials: S
authors.lastname: Lykke-Andersen
authors.forename: Tommy
authors.initials: T
authors.lastname: Nasser
authors.forename: Cyril
authors.initials: C
authors.lastname: Saguez
authors.forename: Edouard
authors.initials: E
authors.lastname: Bertrand
authors.forename: Torben Heick
authors.initials: TH
authors.lastname: Jensen
authors.forename: Claire
authors.initials: C
authors.lastname: Moore
mesh_terms: D021581:Active Transport, Cell Nucleus; D000483:Alleles; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D026723:Polyadenylation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D039221:mRNA Cleavage and Polyadenylation Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C106898:MEX67 protein, S cerevisiae; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; C026452:messenger ribonucleoprotein; C512638:RNA14 protein, S cerevisiae; C512635:RNA15 protein, S cerevisiae