The Experts below are selected from a list of 6666 Experts worldwide ranked by ideXlab platform

Maria Jasin - One of the best experts on this subject based on the ideXlab platform.

  • Homology-Directed Repair and the Role of BRCA1, BRCA2, and Related Proteins in Genome Integrity and Cancer.
    Annual review of cancer biology, 2017
    Co-Authors: Chun-chin Chen, Pei Xin Lim, Elizabeth M. Kass, Weiran Feng, Maria Jasin
    Abstract:

    Germ-line and somatic mutations in genes that promote Homology-Directed Repair (HDR), especially BRCA1 and BRCA2, are frequently observed in several cancers, in particular, breast and ovary but also prostate and other cancers. HDR is critical for the error-free Repair of DNA double-strand breaks and other lesions, and HDR factors also protect stalled replication forks. As a result, loss of BRCA1 or BRCA2 poses significant risks to genome integrity, leading not only to cancer predisposition but also to sensitivity to DNA-damaging agents, affecting therapeutic approaches. Here we review recent advances in our understanding of BRCA1 and BRCA2, including how they genetically interact with other Repair factors, how they protect stalled replication forks, how they affect the response to aldehydes, and how loss of their functions links to mutation signatures. Importantly, given the recent advances with poly(ADP-ribose) polymerase inhibitors (PARPi) for the treatment of HDR-deficient tumors, we discuss mechanisms by which BRCA-deficient tumors acquire resistance to PARPi and other agents.

  • Generation of chromosomal translocations that lead to conditional fusion protein expression using CRISPR-Cas9 and Homology-Directed Repair.
    Methods, 2017
    Co-Authors: Fabio Vanoli, Maria Jasin
    Abstract:

    Recurrent chromosomal translocations often lead to expression of fusion proteins associated with oncogenic transformation. To study translocations and downstream events, genome editing techniques have been developed to generate chromosomal translocations through non-homologous end joining of DNA double-strand breaks introduced at the two participating endogenous loci. However, the frequencies at which these events occur is usually too low to efficiently clone cells carrying the translocation. This article provides a detailed method using CRISPR-Cas9 technology and Homology-Directed Repair to efficiently isolate cells harboring a chromosomal translocation. For an additional level of control, the resulting fusion protein is conditionally expressed to allow early events in oncogenic transformation to be studied. We focus on the generation of the EWSR1-WT1 fusion using human mesenchymal cells, which is associated with the translocation found in desmoplastic small round cell tumors.

  • Robust Homology-Directed Repair within mouse mammary tissue is not specifically affected by Brca2 mutation.
    Nature communications, 2016
    Co-Authors: Elizabeth M. Kass, Mary Ellen Moynahan, Pei Xin Lim, Hildur R. Helgadottir, Maria Jasin
    Abstract:

    The mammary gland undergoes significant proliferative stages after birth, but little is known about how the developmental changes impact DNA double-strand break (DSB) Repair. Mutations in multiple genes involved in Homology-Directed Repair (HDR), considered a particularly accurate pathway for Repairing DSBs, are linked to breast cancer susceptibility, including BRCA2. Using reporter mice that express an inducible endonuclease, we find that HDR is particularly robust in mammary tissue during puberty and pregnancy, accounting for 34–40% of detected Repair events, more than in other tissues examined. Brca2 hypomorphic mutation leads to HDR defects in mammary epithelium during puberty and pregnancy, including in different epithelial lineages. Notably, a similar dependence on Brca2 is observed in other proliferative tissues, including small intestine epithelium. Our results suggest that the greater reliance on HDR in the proliferating mammary gland, rather than a specific dependence on BRCA2, may increase its susceptibility to tumorigenesis incurred by BRCA2 mutation. Mutations in Homology-Directed Repair genes likeBRCA2are linked to breast cancer susceptibility. Here the authors generate mice with an inducible DNA break-reporter system and see high levels of Homology-Directed Repair in proliferative mammary tissue and a general reliance on BRCA2 in various tissues.

  • BARD1 participates with BRCA1 in Homology-Directed Repair of chromosome breaks.
    Molecular and cellular biology, 2003
    Co-Authors: Ulrica K. Westermark, Richard Baer, Maria Jasin, Marsha Reyngold, Adam B. Olshen, Mary Ellen Moynahan
    Abstract:

    The BRCA1 tumor suppressor has been implicated in the maintenance of chromosomal stability through Homology-Directed Repair of DNA double-strand breaks. Much of the BRCA1 in cells forms a heterodimeric complex with a structurally related protein BARD1. We report that expression of truncated mouse or human BARD1 peptides capable of interacting with Brca1 results in a homologous-Repair deficiency. Repair is mildly reduced in Brca1 wild-type cells and severely reduced in cells that harbor a Brca1 splice product deleted for exon 11. Nuclear localization of the Brca1 or BARD1 peptides is not compromised, implying that the Repair deficiency is caused by a more direct effect on Repair. The tumor suppressor activity of BRCA1 may require the participation of BARD1 to maintain chromosome integrity through the homologous-Repair pathway.

  • variant xrcc3 implicated in cancer is functional in Homology Directed Repair of double strand breaks
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks

Jeremy M Stark - One of the best experts on this subject based on the ideXlab platform.

  • suberoylanilide hydroxamic acid as a radiosensitizer through modulation of rad51 protein and inhibition of Homology Directed Repair in multiple myeloma
    Molecular Cancer Research, 2012
    Co-Authors: Xufeng Chen, Patty Wong, Eric H Radany, Jeremy M Stark, Corentin Laulier, Jeffrey Y C Wong
    Abstract:

    Histone deacetylase inhibitors (HDI) have shown promise as candidate radiosensitizers for many types of cancers. However, the mechanisms of action are not well understood, and whether they could sensitize multiple myeloma (MM) to radiation therapy is unclear. In this study, we show that suberoylanilide hydroxamic acid (SAHA) at low concentrations has minimal cytotoxic effects, yet can significantly increase radiosensitivity of MM cells. SAHA seems to block RAD51 protein response to ionizing radiation, consistent with an inhibitory effect on the formation of RAD51 focus in irradiated MM cells. These effects of SAHA on RAD51 focus are independent of cell-cycle distribution changes. Furthermore, we show that SAHA selectively inhibits the Homology-Directed Repair (HDR) pathway. The results of this study suggest that SAHA, a recently approved HDI in clinical trials for malignancies, at lower concentrations may act as a radiosensitizer via disruption of the RAD51-dependent HDR pathway.

  • The relative efficiency of Homology-Directed Repair has distinct effects on proper anaphase chromosome separation
    Nucleic acids research, 2011
    Co-Authors: Corentin Laulier, Anita Cheng, Jeremy M Stark
    Abstract:

    Homology-Directed Repair (HDR) is essential to limit mutagenesis, chromosomal instability (CIN) and tumorigenesis. We have characterized the consequences of HDR deficiency on anaphase, using markers for incomplete chromosome separation: DAPI-bridges and Ultra-fine bridges (UFBs). We show that multiple HDR factors (Rad51, Brca2 and Brca1) are critical for complete chromosome separation during anaphase, while another chromosome break Repair pathway, non-homologous end joining, does not affect chromosome segregation. We then examined the consequences of mild versus severe HDR disruption, using two different dominant-negative alleles of the strand exchange factor, Rad51. We show that mild HDR disruption is viable, but causes incomplete chromosome separation, as detected by DAPI-bridges and UFBs, while severe HDR disruption additionally results in multipolar anaphases and loss of clonogenic survival. We suggest that mild HDR disruption favors the proliferation of cells that are prone to CIN due to defective chromosome separation during anaphase, whereas, severe HDR deficiency leads to multipolar divisions that are prohibitive for cell proliferation.

  • variant xrcc3 implicated in cancer is functional in Homology Directed Repair of double strand breaks
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks

  • Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks.
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Polymorphisms in DNA Repair genes, including double-strand break (DSB) Repair genes, are postulated to confer increased cancer risk. A variant of the XRCC3 gene, which is involved in DSB Repair, has been associated with increased risk of malignant skin melanoma and bladder cancer. We tested the hypothesis that this variant, Thr241Met, may affect cancer risk by disrupting a critical function of XRCC3, i.e., promoting Homology-Directed Repair (HDR) of chromosomal DSBs. Using a quantitative fluorescence assay, we find that the variant XRCC3 protein is functionally active for HDR, complementing the HDR defects of an XRCC3 mutant cell line as well as the wild-type protein. We also examined cells expressing this variant for sensitivity to the interstrand cross-linking agent, mitomycin C (MMC), as HDR mutant cell lines, including the XRCC3 mutant, have been found to be hypersensitive to this DNA damaging agent. Cells expressing the variant protein were found to be no more sensitive than cells expressing the wild-type protein. These results suggest that the increased cancer risk associated with this variant may not be due to an intrinsic HDR defect.

Felipe D Araujo - One of the best experts on this subject based on the ideXlab platform.

  • variant xrcc3 implicated in cancer is functional in Homology Directed Repair of double strand breaks
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks

  • Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks.
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Polymorphisms in DNA Repair genes, including double-strand break (DSB) Repair genes, are postulated to confer increased cancer risk. A variant of the XRCC3 gene, which is involved in DSB Repair, has been associated with increased risk of malignant skin melanoma and bladder cancer. We tested the hypothesis that this variant, Thr241Met, may affect cancer risk by disrupting a critical function of XRCC3, i.e., promoting Homology-Directed Repair (HDR) of chromosomal DSBs. Using a quantitative fluorescence assay, we find that the variant XRCC3 protein is functionally active for HDR, complementing the HDR defects of an XRCC3 mutant cell line as well as the wild-type protein. We also examined cells expressing this variant for sensitivity to the interstrand cross-linking agent, mitomycin C (MMC), as HDR mutant cell lines, including the XRCC3 mutant, have been found to be hypersensitive to this DNA damaging agent. Cells expressing the variant protein were found to be no more sensitive than cells expressing the wild-type protein. These results suggest that the increased cancer risk associated with this variant may not be due to an intrinsic HDR defect.

Andrew J Pierce - One of the best experts on this subject based on the ideXlab platform.

  • variant xrcc3 implicated in cancer is functional in Homology Directed Repair of double strand breaks
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks

  • Variant XRCC3 implicated in cancer is functional in Homology-Directed Repair of double-strand breaks.
    Oncogene, 2002
    Co-Authors: Felipe D Araujo, Jeremy M Stark, Andrew J Pierce, Maria Jasin
    Abstract:

    Polymorphisms in DNA Repair genes, including double-strand break (DSB) Repair genes, are postulated to confer increased cancer risk. A variant of the XRCC3 gene, which is involved in DSB Repair, has been associated with increased risk of malignant skin melanoma and bladder cancer. We tested the hypothesis that this variant, Thr241Met, may affect cancer risk by disrupting a critical function of XRCC3, i.e., promoting Homology-Directed Repair (HDR) of chromosomal DSBs. Using a quantitative fluorescence assay, we find that the variant XRCC3 protein is functionally active for HDR, complementing the HDR defects of an XRCC3 mutant cell line as well as the wild-type protein. We also examined cells expressing this variant for sensitivity to the interstrand cross-linking agent, mitomycin C (MMC), as HDR mutant cell lines, including the XRCC3 mutant, have been found to be hypersensitive to this DNA damaging agent. Cells expressing the variant protein were found to be no more sensitive than cells expressing the wild-type protein. These results suggest that the increased cancer risk associated with this variant may not be due to an intrinsic HDR defect.

  • brca2 is required for Homology Directed Repair of chromosomal breaks
    Molecular Cell, 2001
    Co-Authors: Mary Ellen Moynahan, Andrew J Pierce, Maria Jasin
    Abstract:

    The BRCA2 tumor suppressor has been implicated in the maintenance of chromosomal stability through a function in DNA Repair. In this report, we examine human and mouse cell lines containing different BRCA2 mutations for their ability to Repair chromosomal breaks by homologous recombination. Using the I-SceI endonuclease to introduce a double-strand break at a specific chromosomal locus, we find that BRCA2 mutant cell lines are recombination deficient, such that Homology-Directed Repair is reduced 6- to >100-fold, depending on the cell line. Thus, BRCA2 is essential for efficient Homology-Directed Repair, presumably in conjunction with the Rad51 recombinase. We propose that impaired Homology-Directed Repair caused by BRCA2 deficiency leads to chromosomal instability and, possibly, tumorigenesis, through lack of Repair or misRepair of DNA damage.

  • xrcc3 promotes Homology Directed Repair of dna damage in mammalian cells
    Genes & Development, 1999
    Co-Authors: Andrew J Pierce, Roger D Johnson, Larry H Thompson, Maria Jasin
    Abstract:

    Homology-Directed Repair of DNA damage has recently emerged as a major mechanism for the maintenance of genomic integrity in mammalian cells. The highly conserved strand transferase, Rad51, is expected to be critical for this process. XRCC3 possesses a limited sequence similarity to Rad51 and interacts with it. Using a novel fluorescence-based assay, we demonstrate here that error-free Homology-Directed Repair of DNA double-strand breaks is decreased 25-fold in an XRCC3-deficient hamster cell line and can be restored to wild-type levels through XRCC3 expression. These results establish that XRCC3-mediated homologous recombination can reverse DNA damage that would otherwise be mutagenic or lethal.

Mary Ellen Moynahan - One of the best experts on this subject based on the ideXlab platform.

  • Robust Homology-Directed Repair within mouse mammary tissue is not specifically affected by Brca2 mutation.
    Nature communications, 2016
    Co-Authors: Elizabeth M. Kass, Mary Ellen Moynahan, Pei Xin Lim, Hildur R. Helgadottir, Maria Jasin
    Abstract:

    The mammary gland undergoes significant proliferative stages after birth, but little is known about how the developmental changes impact DNA double-strand break (DSB) Repair. Mutations in multiple genes involved in Homology-Directed Repair (HDR), considered a particularly accurate pathway for Repairing DSBs, are linked to breast cancer susceptibility, including BRCA2. Using reporter mice that express an inducible endonuclease, we find that HDR is particularly robust in mammary tissue during puberty and pregnancy, accounting for 34–40% of detected Repair events, more than in other tissues examined. Brca2 hypomorphic mutation leads to HDR defects in mammary epithelium during puberty and pregnancy, including in different epithelial lineages. Notably, a similar dependence on Brca2 is observed in other proliferative tissues, including small intestine epithelium. Our results suggest that the greater reliance on HDR in the proliferating mammary gland, rather than a specific dependence on BRCA2, may increase its susceptibility to tumorigenesis incurred by BRCA2 mutation. Mutations in Homology-Directed Repair genes likeBRCA2are linked to breast cancer susceptibility. Here the authors generate mice with an inducible DNA break-reporter system and see high levels of Homology-Directed Repair in proliferative mammary tissue and a general reliance on BRCA2 in various tissues.

  • BARD1 participates with BRCA1 in Homology-Directed Repair of chromosome breaks.
    Molecular and cellular biology, 2003
    Co-Authors: Ulrica K. Westermark, Richard Baer, Maria Jasin, Marsha Reyngold, Adam B. Olshen, Mary Ellen Moynahan
    Abstract:

    The BRCA1 tumor suppressor has been implicated in the maintenance of chromosomal stability through Homology-Directed Repair of DNA double-strand breaks. Much of the BRCA1 in cells forms a heterodimeric complex with a structurally related protein BARD1. We report that expression of truncated mouse or human BARD1 peptides capable of interacting with Brca1 results in a homologous-Repair deficiency. Repair is mildly reduced in Brca1 wild-type cells and severely reduced in cells that harbor a Brca1 splice product deleted for exon 11. Nuclear localization of the Brca1 or BARD1 peptides is not compromised, implying that the Repair deficiency is caused by a more direct effect on Repair. The tumor suppressor activity of BRCA1 may require the participation of BARD1 to maintain chromosome integrity through the homologous-Repair pathway.

  • brca2 is required for Homology Directed Repair of chromosomal breaks
    Molecular Cell, 2001
    Co-Authors: Mary Ellen Moynahan, Andrew J Pierce, Maria Jasin
    Abstract:

    The BRCA2 tumor suppressor has been implicated in the maintenance of chromosomal stability through a function in DNA Repair. In this report, we examine human and mouse cell lines containing different BRCA2 mutations for their ability to Repair chromosomal breaks by homologous recombination. Using the I-SceI endonuclease to introduce a double-strand break at a specific chromosomal locus, we find that BRCA2 mutant cell lines are recombination deficient, such that Homology-Directed Repair is reduced 6- to >100-fold, depending on the cell line. Thus, BRCA2 is essential for efficient Homology-Directed Repair, presumably in conjunction with the Rad51 recombinase. We propose that impaired Homology-Directed Repair caused by BRCA2 deficiency leads to chromosomal instability and, possibly, tumorigenesis, through lack of Repair or misRepair of DNA damage.