Stimulation of p53-mediated Transcriptional Activation by the p53-binding Proteins, 53BP1 and 53BP2

• Published in: The Journal of biological chemistry Vol. 273; no. 40; pp. 26061 - 26068
• Main Authors: Iwabuchi, Kuniyoshi, Li, Bin, Massa, Hillary F., Trask, Barbara J., Date, Takayasu, Fields, Stanley
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02-10-1998; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Apoptosis Regulatory Proteins; Carrier Proteins - chemistry; Carrier Proteins - physiology; Chromosome Mapping; Chromosomes, Human, Pair 1 - genetics; Chromosomes, Human, Pair 15 - genetics; Cloning, Molecular; DNA-Binding Proteins - metabolism; Fluorescent Antibody Technique; Genes, ras - genetics; Humans; Intracellular Signaling Peptides and Proteins; Molecular Sequence Data; Phosphoproteins; Sequence Analysis, DNA; Suppression, Genetic - genetics; Transcriptional Activation - genetics; Transfection - genetics; Tumor Cells, Cultured; Tumor Suppressor p53-Binding Protein 1; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.273.40.26061

p53 is a tumor suppressor protein that controls cell proliferation by regulating the expression of growth control genes. In a previous study, we identified two proteins, 53BP1 and 53BP2, that are able to bind to wild type but not to mutant p53 via the DNA-binding domain of p53. We isolated cDNAs expressing a full-length human 53BP1 clone, which predicts a protein of 1972 residues that can be detected in the H358 human lung carcinoma cell line. The 53BP1 and 53BP2 genes were mapped to chromosomes 15q15–21 and 1q41–42, respectively. Immunofluorescence studies showed three types of staining patterns for 53BP1 as follows: both cytoplasmic and nuclear, homogeneous nuclear, and a nuclear dot pattern. In contrast, 53BP2 localized exclusively to the cytoplasm, and this pattern did not change upon coexpression of wild type p53. Although our previous study revealed that p53 is not able to bind simultaneously to either 53BP1 or 53BP2 and to DNA carrying a consensus binding site, both 53BP1 and 53BP2 enhanced p53-mediated transcriptional activation and induced the expression of a p53-dependent protein, suggesting that these proteins might function in signal transduction pathways to promote p53 activity.