title: CWC22 connects pre-mRNA splicing and exon junction complex assembly.
abstract: The exon junction complex (EJC) is a key regulator of posttranscriptional mRNA fate and binds to mRNA during splicing. Although the composition of EJCs is well understood, the mechanism mediating splicing-dependent EJC assembly and the factor(s) recruiting the EJC remain elusive. Here, we identify CWC22 as an essential splicing factor that is required for EJC assembly. In CWC22-depleted cells, pre-mRNA splicing is impaired but is rescued by a central fragment of CWC22. We show that the MIF4G domain of CWC22 initiates EJC assembly via a direct interaction with the EJC core protein eIF4A3, and we characterize mutations in eIF4A3 that abolish binding to CWC22. These eIF4A3 mutants efficiently nucleate splicing-independent recombinant EJC core complexes, but they fail to support splicing-dependent EJC deposition. Our work establishes a direct link between the splicing machinery and the EJC, hence uncovering a molecular interaction at the center of a posttranscriptional gene regulation network.
authors.affiliation: University of Cologne, Institute for Genetics, Cologne, Germany.
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Steckelberg
authors.forename: Volker
authors.initials: V
authors.lastname: Boehm
authors.forename: Agnieszka M
authors.initials: AM
authors.lastname: Gromadzka
authors.forename: Niels H
authors.initials: NH
authors.lastname: Gehring
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D039601:Eukaryotic Initiation Factor-4A / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins; D019696:Peptidylprolyl Isomerase; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C578086:CWC22 protein, human; D002352:Carrier Proteins; D009687:Nuclear Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D039601:Eukaryotic Initiation Factor-4A; C403493:EIF4A3 protein, human; D053487:DEAD-box RNA Helicases; D019696:Peptidylprolyl Isomerase