title: Identification of importin α 7 specific transport cargoes using a proteomic screening approach.
abstract: The importin α:β complex is responsible for the nuclear import of proteins bearing classical nuclear localization signals. In mammals, several importin α subtypes are known to exist that are suggested to have individual functions. Importin α 7 was shown to play a crucial role in early embryonic development in mice. Embryos from importin α 7-depleted females stop at the two-cell stage and show disturbed zygotic genome activation. As there is evidence that individual importin α subtypes possess cargo specificities, we hypothesized that importin α 7 binds a unique set of intracellular proteins. With the use of a collection of in vitro and in vivo binding assays, importin α 7 interaction partners were identified that differed from proteins found to bind to importin α 2 and 3. One of the proteins preferentially binding importin α 7 was the maternal effect protein Brg1. However, Brg1 was localized in oocyte nuclei in importin α 7-deficient embryos, albeit in reduced amounts, suggesting additional modes of nuclear translocation of this factor. An additional SILAC-based screening approach identified Ash2l, Chd3, Mcm3, and Smarcc1, whose nuclear import seems to be disturbed in importin α 7-deficient fibroblasts.
authors.affiliation: Max Delbrück Center of Molecular Medicine, 13125 Berlin, Germany;
authors.forename: Stefanie
authors.initials: S
authors.lastname: Hügel
authors.forename: Reinhard
authors.initials: R
authors.lastname: Depping
authors.forename: Gunnar
authors.initials: G
authors.lastname: Dittmar
authors.forename: Franziska
authors.initials: F
authors.lastname: Rother
authors.forename: Ryan
authors.initials: R
authors.lastname: Cabot
authors.forename: Matthias D
authors.initials: MD
authors.lastname: Sury
authors.forename: Enno
authors.initials: E
authors.lastname: Hartmann
authors.forename: Michael
authors.initials: M
authors.lastname: Bader
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D018345:Mice, Knockout; D064126:Minichromosome Maintenance Complex Component 3 / Q000378:metabolism; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D028901:alpha Karyopherins / Q000235:genetics* / Q000378:metabolism*
chemical_list: C120115:Ash2l protein, mouse; D004268:DNA-Binding Proteins; C558725:KPNA6 protein, mouse; C513269:Mcm3 protein, mouse; D009687:Nuclear Proteins; C491090:Smarcc1 protein, mouse; D014157:Transcription Factors; D028901:alpha Karyopherins; C513194:Smarca4 protein, mouse; D004265:DNA Helicases; D064126:Minichromosome Maintenance Complex Component 3