title: A nucleolar targeting sequence in the Werner syndrome protein resides within residues 949-1092.
abstract: Werner syndrome is a premature aging disorder caused by the lack of an active Werner syndrome protein (WRN). The patients suffer from many of the ailments seen at a much later stage in the life of normal individuals. WRN is a nuclear protein and contains a nuclear localization signal (NLS) in its C-terminal region. Inside the nucleus, WRN is mainly located in the nucleoli and in nuclear foci. To begin to understand the role of WRN in the nucleolus, we determined the specific regions of the protein that are responsible for this localization. We have cloned different WRN gene domains fused to enhanced green fluorescent protein (EGFP), and analyzed their intracellular distribution in living cells using confocal microscopy. The region encompassing amino acids 949-1092 of the human WRN, together with the NLS containing amino acids 1358-1432, provides the targeting to the nucleoli. This targeting is observed in three human and one mouse cell line. The NLS-containing region alone is unable to direct EGFP to the nucleoli. The results demonstrate that the human WRN contains a conserved nucleolar targeting sequence residing in a 144 amino acid region (aa 949-1092) and this provides new tools and insight into the biological function of WRN.
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging/NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
authors.forename: Cayetano
authors.initials: C
authors.lastname: von Kobbe
authors.forename: Vilhelm A
authors.initials: VA
authors.lastname: Bohr
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002466:Cell Nucleolus / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D005090:Exodeoxyribonucleases; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D009154:Mutation; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D053484:RecQ Helicases; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013045:Species Specificity; D014898:Werner Syndrome / Q000378:metabolism*; D000071657:Werner Syndrome Helicase
chemical_list: D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D005090:Exodeoxyribonucleases; D004265:DNA Helicases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase