Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein, which translocates to the nucleus during apoptosis and causes chromatin condensation and large scale DNA fragmentation. Here we report the biochemical characterization of AIF's redox activity. Natural AIF purified from mitochondria and recombinant AIF purified from bacteria (AIF⌬1-120) exhibit NADH oxidase activity, whereas superoxide anion (O 2 ؊ ) is formed. AIF⌬1-120 is a monomer of 57 kDa containing 1 mol of noncovalently bound FAD/mol of protein. ApoAIF⌬1-120, which lacks FAD, has no NADH oxidase activity. However, native AIF⌬1-120, apoAIF⌬1-120, and the reconstituted (FAD-containing) holoAIF⌬1-120 protein exhibit a similar apoptosis-inducing potential when microinjected into the cytoplasm of intact cells. Inhibition of the redox function, by external addition of superoxide dismutase or covalent derivatization of FAD with diphenyleneiodonium, failed to affect the apoptogenic function of AIF⌬1-120 assessed on purified nuclei in a cellfree system. Conversely, blockade of the apoptogenic function of AIF⌬1-120 with the thiol reagent parachloromercuriphenylsulfonic acid did not affect its NADH oxidase activity. Altogether, these data indicate that AIF has a marked oxidoreductase activity which can be dissociated from its apoptosis-inducing function.
Purpose: It is not clear that the published estimates of the breast and ovarian cancer penetrances of mutations in BRCA1 and BRCA2 can be used in genetic counseling in countries such as Spain, where the incidence of breast cancer in the general population is considerably lower, the prevalence of BRCA2 mutations seems to be higher, and a distinct spectrum of recurrent mutations exists for both genes. We aimed to estimate these penetrances for women attending genetic counseling units in Spain. Experimental Design: We collected phenotype and genotype data on 155 BRCA1 and 164 BRCA2 mutation carrier families from12 centers across the country. Average age-specific cumulative risks of breast cancer and ovarian cancer were estimated using a modified segregation analysis method. Results:The estimated average cumulative risk of breast cancer to age 70 years was estimated to be 52% [95% confidence interval (95% CI), 26-69%] for BRCA1 mutation carriers and 47% (95% CI, 29-60%) for BRCA2 mutation carriers. The corresponding estimates for ovarian cancer were 22% (95% CI, 0-40%) and 18% (95% CI, 0-35%), respectively. There was some evidence (two-sided P = 0.09) that 330A>G (R71G) in BRCA1 may have lower breast cancer penetrance. Conclusions: These results are consistent with those from a recent meta-analysis of practically all previous penetrance studies, suggesting that women with BRCA1 and BRCA2 mutations attending genetic counseling services in Spain have similar risks of breast and ovarian cancer to those published for other Caucasian populations. Carriers should be fully informed of their mutation-and age-specific risks to make appropriate decisions regarding prophylactic interventions such as oophorectomy.
It has been demonstrated that monoallelic PALB2 (Partner and Localizer of BRCA2) gene mutations predispose to familial breast cancer. Some of the families reported with germline PALB2 mutations presented male breast cancer as a characteristic clinical feature. Therefore, we wanted to investigate the contribution of germline PALB2 mutations in a set of 131 Spanish BRCA1/BRCA2-negative breast/ovarian cancer families with at least one male breast cancer case. The analysis included direct sequencing of all coding exons and intron/exon boundaries as well as a Multiplex Ligation-dependent Probe Amplification-based analysis of genomic rearrangements. For the first time we have identified a genomic rearrangement of PALB2 gene involving a large deletion from exon 7 to 11 in a breast cancer family. We have also identified several PALB2 variants, but no other obvious deleterious PALB2 mutation has been found. Thus, our study does not support an enrichment of PALB2 germline mutations in the subset of breast cancer families with male breast cancer cases. The identification of intronic and exonic variants indicates the necessity of assessing the implications of variants that do not lead to PALB2 truncation in the pathoghenicity of the PALB2 gene.
We screened BRCA1 and BRCA2 germline mutations in 60 high-risk breast and/or ovarian cancer patients and 20 relatives from Aragon (Spain) by DHPLC (Denaturing High Performance Liquid Chromatography) and direct sequencing of the entire coding sequence and the splicing sites of both genes. We have identified 17 different pathogenic mutations: 8 in BRCA1 and 9 in BRCA2 in 60 unrelated patients and 50% of relatives were carriers. The prevalence of pathogenic mutations in this study was 33.33%. Two truncating mutations are novel: c.5024_5025delGA in exon 16 of BRCA1 and c.2929delC in exon 11 of BRCA2 (numbered after GenBank U14680 and U43746). Multiplex Ligation Dependent Probe Amplification (MLPA) was performed for large mutational scanning of both genes and a large genomic deletion in BRCA1 was found (DelEx8-13). Furthermore, five mutations are described for the first time in Spanish population: c.1191delC, c.3478_3479delTT and c.6633_6637delCTTAA (BRCA1) and c.3972_3975delTGAG and 3908_3909delTG (BRCA2). Three mutations have been reported previously once in Spain: c.3600_3610del11 (BRCA1), c.5804_5807delTTAA (BRCA2) and c.9246C>A (BRCA2). The mutation c.5374_5377delTATG has been found before only in two unrelated families from Castilla-Leon, Spain (BRCA2). Frequent mutations described in Spanish population have also been present: c.187_188delAG, c.5242C>A and c.5385insC in BRCA1 and c.3492_3493insT and c.9254_9258delATCAT in BRCA2. c.5242C>A, 3972_3975delTGAG and c.5804_5807delTTAA were the recurrent mutations found. Fifteen different unclassified variants were identified (25% families). Although specific BRCA1 and BRCA2 mutations are recurrently reported as a result of genetic founder effects we conclude that heterogeneous ethnicity increases the variety of mutations that can be found in Spanish populations.
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