No description available.

Cancer cells exhibit genomic instability and are commonly defective in DNA damage signalling and/or DNA repair. There are many types of DNA damage inducing agents such as mechanical stress on chromosomes during recombination, chemotherapeutics, ionising and ultraviolet radiation and endogenously produced free radicals. These genetic lesions pose a serious threat to the cell and evoke a rapid and intricate DNA damage response signalling pathway involving many transducer and effector pathways including cell cycle arrest, DNA repair, chromatin remodelling, and apoptotic pathways. Genetic mutations within genes in this pathway often lead to genomic instability and cancer. The main effectors of the DNA damage response are the protein kinases ATM and ATR which are rapidly activated in response to DNA damage induction and phosphorylate a large and diverse number of targets including the checkpoint kinases Chk1, and Chk2, the tumour suppressors p53 and BRCA1 and chromatin associated proteins such as H2AX. BRCA1 is a key transducer molecule within the DNA damage response. This is evident from its loss, which leads to defects in many damage response processes such as cell cycle arrest and DNA repair. BRCA1s binding partner BARD1 has also been implicated in the DNA damage response and recent reports indicate that these proteins co-operate in this pathway. This study utilises a multifaceted approach to further characterise the function of the BRCA1/BARD1 complex within the DNA damage response. Firstly we have used shRNA to deplete the BRCA1/BARD1 complex and have shown that the BRCA1/BARD1 complex is required for ATM/ATR dependent phosphorylation of p53Ser-15 in response to IR and UV induced DNA damage. In contrast, we have shown that the phosphorylation of a number of other ATM/ATR dependent targets including H2AX, Chk2, and c-jun do not require the BRCA1/BARD1 complex. The study has also revealed that the prior phosphorylation of BRCA1 at Ser-1423 and Ser-1524 is required for the phosphorylation of p53 at Ser-15. Furthermore, we have shown that these phosphorylation events are required for IR induced G1/S cell cycle arrest via transcriptional induction of the cyclin dependent kinase inhibitor p21. The second part of this study involved the characterisation of a putative BRCA1 interacting protein – The KRAB associated protein 1 (Kap1). During this study we have been unable to confirm Kap1 as a bona fide BRCA1 interactor, however we have identified a clear role for Kap1 in the DNA damage response pathway. Using Mass spectrometric phospho amino acid mapping we have identified a novel Chk2 dependent phosphorylation site, Ser-473, within Kap1. Furthermore, we have shown that this phosphorylation event may regulate Histone H3-Lys-9 acetylation after DNA damage possibly regulating chromatin relaxation. This study has also identified a number of novel Kap1 interacting proteins, which appear to be regulated by Kap1 phosphorylation at Ser-473. These interactors may play an important role in the regulation of chromatin modification and/or structure after DNA damage. By studying the role of BRCA1 in the DNA damage response pathway we have not only uncovered a novel scaffolding function for BRCA1 in the G1/S checkpoint but have also identified a novel protein, Kap1, acting within the DNA damage response pathway. This study has identified a role for Kap-1 in the regulation of chromatin structure in response to DNA damage via the ATM – Chk2 pathway.

Cancer cells exhibit genomic instability and are commonly defective in DNA damage signalling and/or DNA repair. There are many types of DNA damage inducing agents such as mechanical stress on chromosomes during recombination, chemotherapeutics, ionising and ultraviolet radiation and endogenously produced free radicals. These genetic lesions pose a serious threat to the cell and evoke a rapid and intricate DNA damage response signalling pathway involving many transducer and effector pathways including cell cycle arrest, DNA repair, chromatin remodelling, and apoptotic pathways. Genetic mutations within genes in this pathway often lead to genomic instability and cancer. The main effectors of the DNA damage response are the protein kinases ATM and ATR which are rapidly activated in response to DNA damage induction and phosphorylate a large and diverse number of targets including the checkpoint kinases Chk1, and Chk2, the tumour suppressors p53 and BRCA1 and chromatin associated proteins such as H2AX. BRCA1 is a key transducer molecule within the DNA damage response. This is evident from its loss, which leads to defects in many damage response processes such as cell cycle arrest and DNA repair. BRCA1s binding partner BARD1 has also been implicated in the DNA damage response and recent reports indicate that these proteins co-operate in this pathway. This study utilises a multifaceted approach to further characterise the function of the BRCA1/BARD1 complex within the DNA damage response. Firstly we have used shRNA to deplete the BRCA1/BARD1 complex and have shown that the BRCA1/BARD1 complex is required for ATM/ATR dependent phosphorylation of p53Ser-15 in response to IR and UV induced DNA damage. In contrast, we have shown that the phosphorylation of a number of other ATM/ATR dependent targets including H2AX, Chk2, and c-jun do not require the BRCA1/BARD1 complex. The study has also revealed that the prior phosphorylation of BRCA1 at Ser-1423 and Ser-1524 is required for the phosphorylation of p53 at Ser-15. Furthermore, we have shown that these phosphorylation events are required for IR induced G1/S cell cycle arrest via transcriptional induction of the cyclin dependent kinase inhibitor p21. The second part of this study involved the characterisation of a putative BRCA1 interacting protein – The KRAB associated protein 1 (Kap1). During this study we have been unable to confirm Kap1 as a bona fide BRCA1 interactor, however we have identified a clear role for Kap1 in the DNA damage response pathway. Using Mass spectrometric phospho amino acid mapping we have identified a novel Chk2 dependent phosphorylation site, Ser-473, within Kap1. Furthermore, we have shown that this phosphorylation event may regulate Histone H3-Lys-9 acetylation after DNA damage possibly regulating chromatin relaxation. This study has also identified a number of novel Kap1 interacting proteins, which appear to be regulated by Kap1 phosphorylation at Ser-473. These interactors may play an important role in the regulation of chromatin modification and/or structure after DNA damage. By studying the role of BRCA1 in the DNA damage response pathway we have not only uncovered a novel scaffolding function for BRCA1 in the G1/S checkpoint but have also identified a novel protein, Kap1, acting within the DNA damage response pathway. This study has identified a role for Kap-1 in the regulation of chromatin structure in response to DNA damage via the ATM – Chk2 pathway.

Cancer cells exhibit genomic instability and are commonly defective in DNA damage signalling and/or DNA repair. There are many types of DNA damage inducing agents such as mechanical stress on chromosomes during recombination, chemotherapeutics, ionising and ultraviolet radiation and endogenously produced free radicals. These genetic lesions pose a serious threat to the cell and evoke a rapid and intricate DNA damage response signalling pathway involving many transducer and effector pathways including cell cycle arrest, DNA repair, chromatin remodelling, and apoptotic pathways. Genetic mutations within genes in this pathway often lead to genomic instability and cancer. The main effectors of the DNA damage response are the protein kinases ATM and ATR which are rapidly activated in response to DNA damage induction and phosphorylate a large and diverse number of targets including the checkpoint kinases Chk1, and Chk2, the tumour suppressors p53 and BRCA1 and chromatin associated proteins such as H2AX. BRCA1 is a key transducer molecule within the DNA damage response. This is evident from its loss, which leads to defects in many damage response processes such as cell cycle arrest and DNA repair. BRCA1s binding partner BARD1 has also been implicated in the DNA damage response and recent reports indicate that these proteins co-operate in this pathway. This study utilises a multifaceted approach to further characterise the function of the BRCA1/BARD1 complex within the DNA damage response. Firstly we have used shRNA to deplete the BRCA1/BARD1 complex and have shown that the BRCA1/BARD1 complex is required for ATM/ATR dependent phosphorylation of p53Ser-15 in response to IR and UV induced DNA damage. In contrast, we have shown that the phosphorylation of a number of other ATM/ATR dependent targets including H2AX, Chk2, and c-jun do not require the BRCA1/BARD1 complex. The study has also revealed that the prior phosphorylation of BRCA1 at Ser-1423 and Ser-1524 is required for the phosphorylation of p53 at Ser-15. Furthermore, we have shown that these phosphorylation events are required for IR induced G1/S cell cycle arrest via transcriptional induction of the cyclin dependent kinase inhibitor p21. The second part of this study involved the characterisation of a putative BRCA1 interacting protein – The KRAB associated protein 1 (Kap1). During this study we have been unable to confirm Kap1 as a bona fide BRCA1 interactor, however we have identified a clear role for Kap1 in the DNA damage response pathway. Using Mass spectrometric phospho amino acid mapping we have identified a novel Chk2 dependent phosphorylation site, Ser-473, within Kap1. Furthermore, we have shown that this phosphorylation event may regulate Histone H3-Lys-9 acetylation after DNA damage possibly regulating chromatin relaxation. This study has also identified a number of novel Kap1 interacting proteins, which appear to be regulated by Kap1 phosphorylation at Ser-473. These interactors may play an important role in the regulation of chromatin modification and/or structure after DNA damage. By studying the role of BRCA1 in the DNA damage response pathway we have not only uncovered a novel scaffolding function for BRCA1 in the G1/S checkpoint but have also identified a novel protein, Kap1, acting within the DNA damage response pathway. This study has identified a role for Kap-1 in the regulation of chromatin structure in response to DNA damage via the ATM – Chk2 pathway.

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Abstract Approximately 5–10% of all breast cancer cases are estimated to result from a hereditary predisposition to the disease. Currently no more than 25–30% of these familial cases can be explained by mutations in the known susceptibility genes, BRCA1 and BRCA2 being the major ones. Additional predisposing genes are therefore likely to be discovered. This study evaluates whether germline alterations in three BRCA1-associated genes, BACH1 (i.e. BRIP1/FANCJ), BARD1 and TOPBP1, contribute to familial breast cancer. Altogether 214 Finnish patients having breast and/or ovarian cancer were analysed for germline mutations in the BACH1 gene. Nine alterations were observed, four of which located in the protein-encoding region. The previously unidentified Pro1034Leu was considered a possible cancer-associated alteration as it appeared with two-fold higher frequency among cancer cases compared to controls. All the other observed alterations were classified as harmless polymorphisms. Mutation analysis of the BARD1 gene among 126 Finnish patients having family history of breast and/or ovarian cancer revealed seven alterations in the protein-encoding region. The Cys557Ser alteration was seen at an elevated frequency among familial cancer cases compared to controls (p = 0.005, odds ratio [OR] 4.2, 95% confidence interval [CI] 1.7–10.7). The other alterations appeared to be harmless polymorphisms. To evaluate further the possible effect of Cys557Ser on cancer risk, a large case-control study was performed, consisting of 3,956 cancer patients from the Nordic countries. The highest prevalence of Cys557Ser was found among breast and ovarian cancer patients from BRCA1/BRCA2 mutation-negative families (p < 0.001, OR 2.6, 95% CI 1.7–4.0). In contrast, no significant association with male breast cancer, ovarian, colorectal or prostate cancer was observed. The current study is the first evaluating the role of TOPBP1 mutations in familial cancer predisposition. The analysis of 125 Finnish patients having breast and/or ovarian cancer revealed one putative pathogenic alteration. The commonly occurring Arg309Cys allele was observed at a significantly higher frequency among familial cancer cases compared to controls (p = 0.002, OR 2.4, 95% CI 1.3–4.2). The other 18 alterations observed were classified as harmless polymorphisms.

No description available.