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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a screen for DNA repair-defective mutants in the fungus Ustilago maydis, a gene encoding a BRCA2 family member, designated here as Brh2, was identified. A brh2 null allele was found to be defective in allelic recombination, meiosis, and repair of gaps and ionizing radiation damage to the same extent as rad51. Frequent marker loss in meiosis and diploid formation suggested that genomic instability was associated with brh2. This notion was confirmed by molecular karyotype analysis, which revealed gross chromosomal alterations associated with brh2. Yeast two-hybrid analysis indicated interaction between Brh2 and Rad51. Recapitulation in U. maydis of defects in DNA repair and genome stability associated with brh2 means that the BRCA2 gene family is more widespread than previously thought.
Mol Cell 2002 Sep
PMID:BRCA2 homolog required for proficiency in DNA repair, recombination, and genome stability in Ustilago maydis. 1240 34

Mutations in the human BRCA2 breast cancer susceptibility gene are associated with increased risks of breast, ovarian, and other cancers. BRCA2 has been hypothesized to function in processes of DNA damage/breakage repair, cell proliferation, and apoptosis. These processes continually occur in the thymus during thymocyte development, and BRCA2 mRNA is highly expressed in thymus relative to most other organs. We therefore used the thymus as a model system to study BRCA2 expression and function. Quantitative reverse transcription polymerase chain reaction experiments showed that highly activated immature CD4(+) CD8(+) double-positive human thymocytes that exhibited high levels of proliferation and apoptosis had increased BRCA2 mRNA levels relative to other thymocyte subsets. BRCA2 mRNA levels were upregulated in thymocytes treated with the DNA-damaging agent etoposide. Only modest increases were associated with proliferation in human peripheral lymphocytes in response to concanavalin A (ConA) mitogen. Mice homozygous for a targeted mutation in Brca2 exon 27 (Brca2(Delta27/Delta27)) showed normal thymic architecture but had 18% decreased thymocyte cellularity compared with wild-type mice. Thymocytes from these Brca2(Delta27/Delta27) mice displayed decreased apoptosis in response to etoposide-induced DNA damage compared with wild-type thymocytes. These studies suggest that BRCA2 mRNA levels are modulated during DNA damage and may be important during apoptosis.
Mol Carcinog 2002 Nov
PMID:Thymic model for examining BRCA2 expression and function. 1241 May 62

Marriage between biological relatives is a social custom with a long history in many parts of the world. Today, hundreds of millions of individuals live in consanguineous families. The offspring of consanguineous parents are more likely to have the same two alleles (homozygosity) by descent. In consanguineous family with BRCA1/2 gene mutations, an offspring is more likely to be BRCA1/2 homozygous. The consequences of BRCA1/2 mutation homozygosity in humans are unknown. In knockout mice, BRCA1 or BRCA2 homozygotes die as embryos. Because tumor suppressor genes are conserved and less species-specific than other genes, human BRCA1/2 homozygotes are likely to be biologically non-viable and are unknown to exist. Among the conceptuses of consanguineous couples, there are excess deaths (abortions, stillbirths, perinatal and early-childhood deaths) as well as a decreased risk of breast cancer, especially in younger females. It has been suggested that, in part, the excess deaths are due to BRCA1/2 and other still undiscovered tumor gene homozygotes. To examine the consequences of the long-term practice of consanguineous marriage on the prevalence of lethal cancer genes, we simulated, by computer, the mating of non-consanguineous and consanguineous populations over 40 generations. The program was developed in Basic for a Macintosh computer. The input comprised the rates of consanguineous marriage types and the output parameter was the rate of heterozygotes (carriers) in each generation. The combined prevalence of BRCA1/2 mutation of 1% was used as a starting reference point. Absence of spontaneous mutations and gene flow were assumed. In a randomly mating population, the BRCA1/2 carrier rate decreases on average 0.0035% every 25 years. In a highly consanguineous population, the carrier rate decreases on average 0.022% every 25 years, or six times faster than in a non-consanguineous population. There is a worldwide trend of decreasing breast cancer incidence with an increasing consanguinity rate. In conclusion, the BRCA1/2 and possibly other undiscovered tumor gene carrier rates are significantly lower in consanguineous than in non-consanguineous populations. Gene frequency in a population depends on the rate of inbreeding and length of consanguineous practices. A drift phenomenon may exert a major effect on the carrier rate. Consanguinity may explain part of the worldwide variation of breast cancer incidence.
Int J Mol Med 2002 Dec
PMID:Breast cancer, consanguinity, and lethal tumor genes: simulation of BRCA1/2 prevalence over 40 generations. 1242 97

The proteins encoded by the breast-cancer-susceptibility genes, BRCA1 and BRCA2, have recently been implicated in DNA-repair processes, thereby improving our understanding of how the loss of these genes contributes to cancer initiation and progression. It appears that the role of BRCA1 in DNA repair, which could involve the integration of several pathways, is broader than that of BRCA2. BRCA1 functions in the signalling of DNA damage and its repair by homologous recombination, nucleotide-excision repair and possibly non-homologous end-joining. BRCA2 has a more specific role in DNA repair, regulating the activity of RAD51, which is required for homologous recombination. An improved understanding of the interactions of BRCA1 and BRCA2 with other proteins in large macromolecular complexes is helping to reveal their exact role in DNA repair.
Trends Mol Med 2002 Dec
PMID:The relationship between the roles of BRCA genes in DNA repair and cancer predisposition. 1247 Sep 90

The mechanistic link between the BRCA2 protein, homologous recombination, and genomic instability has become clearer as a result of recent work describing the structures of different BRCA2 domains bound to Rad51 and to single-stranded DNA.
Mol Cell 2002 Dec
PMID:BRCA2 keeps Rad51 in line. High-fidelity homologous recombination prevents breast and ovarian cancer? 1123 56

Inherited mutations of the BRCA1 and BRCA2 genes, whose protein products are necessary for the homology-directed DNA repair pathway, confer a dominant susceptibility to cancer. We have investigated whether mutations of genes encoding other components of the same DNA repair pathway can also affect cancer susceptibility. We have identified three novel non-synonymous substitutions in one such gene, encoding the RAD51-related protein XRCC3. One of these variants, D213N, occurs in a highly conserved ATP-binding domain and completely abrogates the ability of the transfected gene to correct the phenotype of XRCC3 deficient cells. The D213N variant was found in the heterozygous state in DNA from 3/1577 healthy individuals. However, we did not detect this variant at all amongst 187 breast cancer families and 1300 unrelated patients with common cancers. Thus we have no evidence that D213N increases the risk of cancer. We propose that not all components of the homologous recombination repair complex can act as cancer susceptibility genes.
Hum Mol Genet 2003 Apr 15
PMID:A naturally occurring mutation in an ATP-binding domain of the recombination repair gene XRCC3 ablates its function without causing cancer susceptibility. 1266 15

The recent identification of major genomic rearrangements in breast and breast/ovarian cancer families has widened the mutational spectrum of the BRCA1 gene, thus increasing the number of informative patients who can benefit from molecular screening. Numerous types of alterations have been identified in different populations with variable frequencies, probably due to both ethnic diversity and the technical approach employed. In fact, although several methods have been successfully used to detect large genomic deletions and insertions, most are laborious, time-consuming, and of variable sensitivity. In order to estimate the contribution of BRCA1 genomic rearrangements to breast/ovarian cancer predisposition in Italian families, we applied, for the first time as a diagnostic tool, the recently described multiplex ligation-dependent probe amplification (MLPA) methodology. Among the 37 hereditary breast/ovarian cancer (HBOC) families selected, all had a high prior probability of BRCA1 mutation, and 15 were previously shown to carry a mutation in either the BRCA2 (five families) or BRCA1 gene (10 families, including one genomic rearrangement). The application of BRCA1-MLPA to the remaining 22 uninformative families allowed the identification of five additional genomic rearrangements. Moreover, we observed that loss of constitutive heterozygosity of polymorphic markers in linkage disequilibrium is predictive of such BRCA1 alterations. By means of this approach, we demonstrate that BRCA1 genomic deletions account for more than one-third (6/15) of the pathogenic BRCA1 mutations in our series. We therefore propose to systematically include MLPA in the BRCA1 mutational analysis of breast/ovarian cancer families.
Hum Mol Genet 2003 May 01
PMID:Genomic rearrangements account for more than one-third of the BRCA1 mutations in northern Italian breast/ovarian cancer families. 1270 Jan 74

The rare hereditary disorder Fanconi anemia (FA) is characterized by progressive bone marrow failure, congenital skeletal abnormality, elevated susceptibility to cancer, and cellular hypersensitivity to DNA cross-linking chemicals and sometimes other DNA-damaging agents. Molecular cloning identified six causative genes (FANCA, -C, -D2, -E, -F, and -G) encoding a multiprotein complex whose precise biochemical function remains elusive. Recent studies implicate this complex in DNA damage responses that are linked to the breast cancer susceptibility proteins BRCA1 and BRCA2. Mutations in BRCA2, which participates in homologous recombination (HR), are the underlying cause in some FA patients. To elucidate the roles of FA genes in HR, we disrupted the FANCG/XRCC9 locus in the chicken B-cell line DT40. FANCG-deficient DT40 cells resemble mammalian fancg mutants in that they are sensitive to killing by cisplatin and mitomycin C (MMC) and exhibit increased MMC and radiation-induced chromosome breakage. We find that the repair of I-SceI-induced chromosomal double-strand breaks (DSBs) by HR is decreased approximately 9-fold in fancg cells compared with the parental and FANCG-complemented cells. In addition, the efficiency of gene targeting is mildly decreased in FANCG-deficient cells, but depends on the specific locus. We conclude that FANCG is required for efficient HR-mediated repair of at least some types of DSBs.
Mol Cell Biol 2003 Aug
PMID:Fanconi anemia FANCG protein in mitigating radiation- and enzyme-induced DNA double-strand breaks by homologous recombination in vertebrate cells. 1286 Oct 27

BRCA1 and BRCA2 germline mutations account for <5% of breast cancer cases. Less penetrant breast cancer susceptibility genes are likely to exist. Earlier studies have suggested involvement of the HLA region. The HLA region was genotyped with 24 microsatellite markers and markers for two single nucleotide polymorphisms (SNPs) in TNFalpha and TNFbeta, in germline DNA from 956 breast cancer patients and 1271 family-based controls. Association analyses and the haplotype sharing statistic (HSS) were used to search for differences in haplotype sharing between patients and controls. Based on criteria known to influence genetic breast cancer risk, patients were divided into groups of high, moderate and low risk. The HSS revealed a significant difference in mean haplotype sharing between patients and controls for four consecutive markers (D6S2671, TNFa, D6S2672 and MICA), the highest being at D6S2671 (P=0.017). Subgroup analyses showed that moderate-risk patients were responsible for this difference, with the strongest association for D6S2672 (P=0.0009). A single haplotype was more frequent and longer in moderate-risk patients than in controls. The results were confirmed with association analyses. Individuals homozygous for haplotype 110-184 (D6S2672-MICA) were observed in 9.0% of moderate-risk patients and 1.5% of controls [odds ratio (OR)=7.14], while heterozygotes were at a lower risk (OR=1.41), suggesting a recessive effect. No association was observed between the two SNPs in TNFalpha (-308) and TNFbeta (intron 1) and breast cancer risk. The results reveal a potential role of the HLA class III subregion in susceptibility to breast cancer in patients at moderate familial risk.
Hum Mol Genet 2003 Sep 15
PMID:The HLA class III subregion is responsible for an increased breast cancer risk. 1291 40

Fanconi anaemia (FA) is an autosomal recessive genetic disorder characterized by progressive bone marrow failure, multiple congenital abnormalities, and an increased risk of cancer. FA cells are characterized by chromosomal instability and hypersensitivity to DNA interstrand crosslinking agents. At least eight complementation groups exist (FA-A to G), and the genes for all of these except FA-B have been cloned. Functional linkage between the FA pathway and genes involved in susceptibility to breast cancer has been demonstrated by the interaction of the FANCA and FANCD2 proteins with BRCA1, and the discovery that the FANCD1 gene is identical to BRCA2. Here we have used the yeast two-hybrid system to test for direct interaction between BRCA2 or its effector RAD51 and the FANCA, FANCC and FANCG proteins. We found that FANCG was capable of binding to two separate sites in the BRCA2 protein, located either side of the BRC repeats. Furthermore, FANCG could be co-immunoprecipitated with BRCA2 from human cells, and FANCG co-localized in nuclear foci with both BRCA2 and RAD51 following DNA damage with mitomycin C. These results demonstrate that BRCA2 is directly connected to a pathway that is deficient in interstrand crosslink repair, and that at least one other FA protein is closely associated with the homologous recombination DNA repair machinery.
Hum Mol Genet 2003 Oct 01
PMID:Direct interaction of the Fanconi anaemia protein FANCG with BRCA2/FANCD1. 1291 60


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