Nuclear localization signals of the BRCA2 protein.
BRCA2 is a tumor suppressor gene whose germline mutations increase the lifetime risk of breast cancer. BRCA2 encodes a large nuclear protein involved in DNA repair, but the location of its functional domain has been unclear. Here, we report nuclear localization signals (NLSs) of the BRCA2 protein. By expressing various portions of the BRCA2 protein tagged with enhanced green fluorescent protein in HeLa cells, we show that the C-terminal domain is necessary for nuclear localization. Two regions in the C-terminal domain were identified with functional NLSs by site-directed mutagenesis analyses. The NLSs locate between the germline mutation found in the most downstream position and the polymorphic stop codon, suggesting that defects in the proper nuclear transport of the BRCA2 protein are causative of carcinogenesis. Our data thus provide a possible explanation for the high frequency of frame-shift and nonsense mutations in BRCA2 of hereditary breast cancer patients.
Yano
K
K
Department of Molecular Diagnosis, Cancer Institute, Japanese Foundation for Cancer Research, 1-37-1 Kami-ikebukuro, Toshima-ku, Tokyo, 170-8455, Japan.
Morotomi
K
K
Saito
H
H
Kato
M
M
Matsuo
F
F
Miki
Y
Y
D024682:BRCA2 Protein; D001692:Biological Transport; D001943:Breast Neoplasms / Q000235:genetics; D002451:Cell Compartmentation; D005260:Female; D016147:Genes, Tumor Suppressor; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins; D009363:Neoplasm Proteins / Q000235:genetics / Q000302:isolation & purification*; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000235:genetics / Q000302:isolation & purification; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification*
D024682:BRCA2 Protein; D008164:Luminescent Proteins; D009363:Neoplasm Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins