Fanconi anemia protein FANCD2 inhibits TRF1 polyADP-ribosylation through tankyrase1-dependent manner

Background: Fanconi anemia (FA) is a rare autosomal recessive syndrome characterized by developmental abnormalities, progressive bone marrow failure, and predisposition to cancer. The key FA protein FANCD2 crosstalks with members of DNA damage and repair pathways that also play a role at telomeres. Therefore, we investigated whether FANCD2 has a similar involvement at telomeres. Results: We reveal that FANCD2 may perform a novel function separate to the FANCD2/BRCA pathway. This function includes FANCD2 interaction with one of the telomere components, the PARP family member tankyrase-1. Moreover, FANCD2 inhibits tankyrase-1 activity in vitro. In turn, FANCD2 deficiency increases the polyADP-ribosylation of telomere binding factor TRF1. Conclusions: FANCD2 binding and inhibiting tankyrase-1PARsylation at telomeres may provide an additional step within the FA pathway for the regulation of genomic integrity

Savior siblings and Fanconi anemia : analysis of success rates from the family's perspective

Purpose:The current curative treatment of Fanconi anemia is hematopoietic stem cell transplantation; this treatment has a higher rate of successful outcome when donors are compatible siblings. Therefore some families opt to have a healthy and compatible baby after selecting an embryo using preimplantation genetic diagnosis with human leukocyte antigen (HLA) typing. This study aims to estimate the success rate of this procedure from the family's perspective.Methods:Genetic and embryology data were collected from genetic reports provided by the families.Results:A total of 524 oocytes (14.1 oocytes/cycle) and 299 embryos were generated (8.0 embryos/cycle) after 38 in vitro fertilization cycles. Sixteen embryos were transferred to the uterus because they were non-Fanconi anemia and HLA matched. One baby was born. A younger couple delivered a healthy and HLA-compatible baby after four cycles. Therefore, the success rate per cycle is less than 5% (two babies from 42 trials).Conclusion:While Fanconi anemia per se does not worsen the probability of success, a critical factor is advanced maternal age; a late diagnosis leads to few transferrable embryos and high rates of aneuploidy. Families should be informed in advance of the many trials that they will probably need to undergo even if a haploidentical younger relative is available as an oocyte donor

Epigenetic Alterations in Fanconi Anaemia: Role in Pathophysiology and Therapeutic Potential.

Fanconi anaemia (FA) is an inherited disorder characterized by chromosomal instability. The phenotype is variable, which raises the possibility that it may be affected by other factors, such as epigenetic modifications. These play an important role in oncogenesis and may be pharmacologically manipulated. Our aim was to explore whether the epigenetic profiles in FA differ from non-FA individuals and whether these could be manipulated to alter the disease phenotype. We compared expression of epigenetic genes and DNA methylation profile of tumour suppressor genes between FA and normal samples. FA samples exhibited decreased expression levels of genes involved in epigenetic regulation and hypomethylation in the promoter regions of tumour suppressor genes. Treatment of FA cells with histone deacetylase inhibitor Vorinostat increased the expression of DNM3Tβ and reduced the levels of CIITA and HDAC9, PAK1, USP16, all involved in different aspects of epigenetic and immune regulation. Given the ability of Vorinostat to modulate epigenetic genes in FA patients, we investigated its functional effects on the FA phenotype. This was assessed by incubating FA cells with Vorinostat and quantifying chromosomal breaks induced by DNA cross-linking agents. Treatment of FA cells with Vorinostat resulted in a significant reduction of aberrant cells (81% on average). Our results suggest that epigenetic mechanisms may play a role in oncogenesis in FA. Epigenetic agents may be helpful in improving the phenotype of FA patients, potentially reducing tumour incidence in this population

Biallelic germline BRCA1 mutations in a patient with early onset breast cancer, mild Fanconi anemia-like phenotype, and no chromosome fragility

Background Biallelic BRCA1 mutations are regarded either embryonically lethal or to cause Fanconi anemia (FA), a genomic instability syndrome characterized by bone marrow failure, developmental abnormalities, and cancer predisposition. We report biallelic BRCA1 mutations c.181T > G (p.Cys61Gly) and c.5096G > A (p.Arg1699Gln) in a woman with breast cancer diagnosed at the age of 30 years. The common European founder mutation p.Cys61Gly confers high cancer risk, whereas the deleterious p.Arg1699Gln is hypomorphic and was suggested to confer intermediate cancer risk. Methods and Results Aside from significant toxicity from chemotherapy, the patient showed mild FA-like features (e.g., short stature, microcephaly, skin hyperpigmentation). Chromosome fragility, a hallmark of FA patient cells, was not present in patient-derived peripheral blood lymphocytes. We demonstrated that the p.Arg1699Gln mutation impairs DNA double-strand break repair, elevates RAD51 foci levels at baseline, and compromises BRCA1 protein function in protecting from replication stress. Although the p.Arg1699Gln mutation compromises BRCA1 function, the residual activity of the p.Arg1699Gln allele likely prevents from chromosome fragility and a more severe FA phenotype. Conclusion Our data expand the clinical spectrum associated with biallelic BRCA1 mutations, ranging from embryonic lethality to a mild FA-like phenotype and no chromosome fragility

DNA methylation pattern on tumour suppressor genes in peripheral blood mononuclear cells of FA patients.

<p>PBMC from FA patients and healthy donor were isolated as in A, DNA was isolated and methylation profile was identified in 2 FA samples and 2 healthy donors samples using EpiTect Methyl II Complete PCR array (SABiosciences). Samples CTR1 and CTR2 represent control and FA1 and FA2 represent FA patients. Each row represents a tumour-supressor genes and each column represent a single DNA sample. The methylation degree are represented by the level of intensity of the square, red representing greater than 10% promoter hypermethylation, and green representing less than 10% promoter methylation (unmethylated) alleles for the tumour-suppressor gene.</p

Effect of vorinostat on DEB-induced chromosome fragility of FA lymphocytes.

<p>(<b>A</b>) Lymphocytes metaphase without treatment. (<b>B</b>) Lymphocyte metaphase treated with DEB. (<b>C</b>) Lymphocyte metaphase treated with DEB after Vorinostat treatment. The red arrows indicate aberrant chromosomes characteristic of FA cells. (<b>D</b>) Number of breaks per cell after treatment with Vorinostat. (<b>E</b>) Number of breaks per cell after treatment with Vorinostat on DEB-induced breaks. The p values are indicated.</p

Effect of vorinostat on epigenetic patterns on chromatin epigenetic modifications enzymes differentially expressed in FA mononuclear cells.

<p>PBMC from FA patients in culture were treated with 1μM vorinostat as indicated or vehicle (control) for 8h and gene expression quantified by qPCR.</p