title: The nucleoporin Nup214 sequesters CRM1 at the nuclear rim and modulates NFkappaB activation in Drosophila.
abstract: CRM1-mediated protein export is an important determinant of the nuclear accumulation of many gene regulators. Here, we show that the NFkappaB transcription factor Dorsal is a substrate of CRM1 and requires the nucleoporin Nup214 for its nuclear translocation upon signaling. Nup214 bound to CRM1 directly and anchored it to the nuclear envelope. In nup214 mutants CRM1 accumulated in the nucleus and NES-protein export was enhanced. Nup214 formed complexes with Nup88 and CRM1 in vivo and Nup214 protected Nup88 from degradation at the nuclear rim. In turn, Nup88 was sufficient for targeting the complex to the nuclear pores. Overexpression experiments indicated that Nup214 alone attracts a fraction of CRM1 to the nuclear envelope but does not interfere with NES-GFP export. By contrast, overexpression of the Nup214-Nup88 complex trapped CRM1 and Dorsal to cytoplasmic foci and inhibited protein export and immune response activation. We hypothesize that variation in levels of the Nup214-Nup88 complex at the pore changes the amount of NPC-bound CRM1 and influences the relative strength and duration of NFkappaB signaling responses.
authors.affiliation: Department of Developmental Biology, Wenner-Gren Institute, Stockholm University, S-10691, Stockholm, Sweden.
authors.forename: Nikos
authors.initials: N
authors.lastname: Xylourgidis
authors.forename: Peggy
authors.initials: P
authors.lastname: Roth
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Sabri
authors.forename: Vasilios
authors.initials: V
authors.lastname: Tsarouhas
authors.forename: Christos
authors.initials: C
authors.lastname: Samakovlis
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000378:metabolism; D047468:Immunoprecipitation; D028884:Karyopherins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000166:cytology / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009685:Nuclear Envelope / Q000378:metabolism; D019913:Nuclear Localization Signals; D022022:Nuclear Pore / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000097606:Exportin 1 Protein
chemical_list: D029721:Drosophila Proteins; D049452:Green Fluorescent Proteins; D028884:Karyopherins; D016328:NF-kappa B; D019913:Nuclear Localization Signals; D028861:Nuclear Pore Complex Proteins; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C490094:Nup214 protein, Drosophila; C491301:mbo protein, Drosophila