title: Dynamic changes in nuclear import of a nuclear localisation signal-bearing substrate in 8-cell stage porcine embryos.
abstract: Coordinated intracellular trafficking is critically important for proper timing of major cellular events during embryogenesis. Nuclear import mediated by the karyopherin α/β (importin α/β) heterodimer is perhaps the best characterised nuclear trafficking system in eukaryotic cells. Seven karyopherin α subtypes have been identified in the domestic pig, and although each karyopherin α subtype transports proteins bearing classical nuclear localisation signals (NLSs), individual karyopherin α subtypes have been shown to preferentially transport specific cargoes. The aim of the present study was to determine the mechanism by which BRN2, a transcription factor previously reported to be transported by the karyopherin α/β heterodimer, gains access to the nucleus in porcine oocytes and embryos. Using a combination of in vivo and in vitro assays, we tested the hypothesis that discrete karyopherin α subtypes transport BRN2 into the nuclei of porcine oocytes and cleavage stage embryos. Our results show that ectopically expressed BRN2 adopts a nuclear localisation in all nuclei through the 4-cell stage of development, whereas only a subset of blastomeres in 8-cell stage embryos possess nuclear BRN2. This pattern is unique to BRN2 because another ectopically expressed NLS-containing protein is able to adopt a nuclear localisation in all blastomeres of 8-cell stage embryos.
authors.affiliation: Department of Animal Sciences, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Animal Sciences, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA.
authors.forename: Ki-Eun
authors.initials: KE
authors.lastname: Park
authors.affiliation: Department of Animal Sciences, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA.
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Cabot
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000818:Animals; D002970:Cleavage Stage, Ovum / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D055785:Gene Knockdown Techniques; D005822:Genetic Vectors / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism*; D016014:Linear Models; D008845:Microinjections; D019913:Nuclear Localization Signals / Q000378:metabolism*; D050809:POU Domain Factors / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D034421:Sus scrofa / Q000196:embryology*; D028901:alpha Karyopherins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D018398:Homeodomain Proteins; D019913:Nuclear Localization Signals; D050809:POU Domain Factors; D028901:alpha Karyopherins; C085076:transcription factor Brn-2