NFBD1/KIAA0170 is a novel nuclear transcriptional transactivator with BRCT domain.
The BRCT (BRCA1 C-terminus) superfamily includes a large number of nuclear proteins closely involved in DNA repair, recombination, and cell-cycle control. The human cDNA clone NFBD1 (previously designated KIAA0170) encodes a novel protein (2089 amino acids in length; calculated molecular mass 226,440 D) with possible BRCT domains at its carboxy terminus (amino acid residues 1894-2089). This gene product has been described as one of the BRCT superfamily proteins. However, its biological significance has been unclarified. Expression of green fluorescent protein (GFP)-tagged full-length NFBD1 or a series of deletion mutants indicated that NFBD1 was localized to the nucleus in various mammalian cells, and a 197-amino acid segment near the amino terminus (amino acid residues 142-338) contained a nuclear targeting signal. In vitro DNA-binding experiments showed that the highly basic region of NFBD1 (amino acid residues 1841-1893) possessed DNA-binding activity. The region encoding amino acids 508-995 of NFBD1 fused inframe with GAL4 DNA-binding domain activated transcription in both yeast and mammalian cells, while the possible BRCT domains of NFBD1 failed to induce transcription in mammalian cells. Overexpression of antisense NFBD1 RNA in a p53-deficient human osteogenic sarcoma cell line (SAOS-2) resulted in remarkable suppression of SAOS-2 colony formation. These results suggest that NFBD1 is a nuclear transcriptional transactivator with possible BRCT domains and may contribute to cell growth control.
Ozaki
T
T
Division of Biochemistry, Chiba Cancer Center Research Institute, Japan. tozaki@chiba-cc.pref.chiba.jp
Nagase
T
T
Ichimiya
S
S
Seki
N
N
Ohiri
M
M
Nomura
N
N
Takada
N
N
Sakiyama
S
S
Weber
B L
BL
Nakagawara
A
A
D048868:Adaptor Proteins, Signal Transducing; D019313:BRCA1 Protein / Q000235:genetics*; D002451:Cell Compartmentation; D018797:Cell Cycle Proteins; D002874:Chromosome Mapping; D002896:Chromosomes, Human, Pair 6; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009687:Nuclear Proteins / Q000235:genetics* / Q000302:isolation & purification; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D015534:Trans-Activators / Q000235:genetics* / Q000302:isolation & purification; D014407:Tumor Cells, Cultured
D048868:Adaptor Proteins, Signal Transducing; D019313:BRCA1 Protein; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C413163:MDC1 protein, human; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators