title: Zinc finger domain of Snail functions as a nuclear localization signal for importin beta-mediated nuclear import pathway.
abstract: Snail, a DNA-binding zinc finger protein, functions as a transcriptional repressor for genes including E-cadherin during development and the acquisition of tumor cell invasiveness. Human Snail is a 264-amino acid nuclear protein with an amino-terminal basic amino acid-rich domain (SNAG domain) and a carboxyl-terminal DNA-binding domain (zinc finger domain). A series of fusion proteins composed of green fluorescent protein (GFP) and portions of the Snail protein were generated, and their subcellular localization was examined. Fusion of the four zinc fingers to GFP led to the targeting of GFP to the nucleus, demonstrating that the zinc finger domain is sufficient for nuclear localization. Using an in vitro transport system, the nuclear import of Snail was reconstituted by importin (karyopherin) beta in the presence of Ran and NTF2. We further demonstrated that Snail binds directly to importin beta in a zinc finger domain-dependent manner. These results indicate that zinc finger domain of Snail functions as a nuclear localization signal and Snail can be transported into the nucleus in an importin beta-mediated manner.
authors.affiliation: Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8520, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamasaki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Sekimoto
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Douchi
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ozawa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism*; D004285:Dogs; D017930:Genes, Reporter; D006801:Humans; D021382:Protein Sorting Signals / Q000502:physiology*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D028961:beta Karyopherins / Q000378:metabolism*
chemical_list: D021382:Protein Sorting Signals; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D028961:beta Karyopherins