The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Harry Van Steeg - One of the best experts on this subject based on the ideXlab platform.
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comparison of Clastogen induced gene expression profiles in wild type and dna repair deficient rad54 rad54b cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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Comparison of Clastogen-induced gene expression profiles in wild-type and DNA repair-deficient Rad54/Rad54B cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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lacZ mouse embryonic fibroblasts detect both Clastogens and mutagens.
Mutation research, 2009Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Mirjam M Schaap, Coenraad F M Hendriksen, Edwin Zwart, Lya G Hernandez, Harry Van SteegAbstract:The Clastogenic effects of MMC and BLM and the mutagenic effects of B[a]P, N-ac-AAF and ENU were studied in mouse embryonic fibroblasts derived from wild-type (WT) and Rad54/Rad54B-deficient mice. Clastogens as well as mutagens showed a statistically significant induction of mutations in the lacZ reporter gene both in a WT and Rad54/Rad54B-deficient genetic background. Rad54/Rad54B MEFs appeared equally sensitive to the Clastogens compared to WT MEFs, except for MMC. The type of mutations induced by the different compounds was investigated further by hybridizing the mutant colonies with total mouse DNA. An obvious increased number of mouse DNA positive clones was observed after BLM and MMC exposure, indicating that after these treatments genome rearrangements/translocations had occurred. In this hybridization assay, Rad54/Rad54B MEFs did not show more rearrangements/translocations than WT MEFs. As expected, the mutagens used showed no increase in chromosomal rearrangements or transloctions in MEFs derived from both genotypes. These results show that WT MEFs carrying the lacZ reporter gene on a plasmid are capable to detect both Clastogenic as well as mutagenic effects of compounds in vitro. Deletion of the Rad54 and Rad54B genes did not further enhance the sensitivity of MEFs towards Clastogens.
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DNA-repair-deficient Rad54/Rad54B mice are more sensitive to Clastogens than wild-type mice.
Toxicology letters, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Coenraad F M Hendriksen, Mirjam Schaap, Peter Theunissen, Jeroen Essers, Harry Van SteegAbstract:The sensitivity of DNA-repair-deficient Rad54/Rad54B mice for Clastogens was studied and compared to that of wild-type mice. LacZ mutant frequencies (MF) in Rad54/Rad54B mice, after treatment with mitomycin C (MMC), bleomycin (BLM) and gamma-irradiation, were compared to those of the wild-type mice following the same treatments. While none of the Clastogens showed an induction of the lacZ MF in the wild-type mice, there was a significant increase of the lacZ MF in the bone marrow of the Rad54/Rad54B mice after treatment with BLM and gamma-irradiation and in the spleen after MMC treatment. As expected, the positive control ENU showed a significant increase in the lacZ MF in all tested organs in wild-type mice. Mutant colonies were hybridized with total mouse DNA in order to discriminate between small gene mutations and large DNA rearrangements and translocations (size-change mutations). The hybridization studies showed a significant increase in mouse DNA positive clones 4 days after treatment with MMC and BLM in the bone marrow of the wild-type mice, which is indicative for chromosomal rearrangements and translocations to occur. An even more pronounced increase was seen 28 days after treatment with the same compounds in the Rad54/Rad54B mice.
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Detecting genotoxic effects of potential Clastogens: An in vivo study using the transgenic lacZ plasmid and the Muta™Mouse model
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Hanneke Korsten, Anthony M. Lynch, Lorna Bailey, Annemieke De Vries, Coenradus F.m. Hendriksen, Harry Van SteegAbstract:In the present paper the capacity of the pUR288 plasmid mouse model and the Muta TM Mouse model to detect the Clastogens bleomycin, m-AMSA, o-AMSA and camptothecin, was investigated. Ethylnitrosourea (ENU) served as a positive control, methylcellulose as a negative control. Only bleomycin induced a slight but significant increase in lacZ mutant frequency (MF) in bone marrow of pUR288 plasmid mice. Exposure to the other compounds did not result in an increase in the MF in bone marrow and liver in both mouse models. For the Muta TM Mouse this result was expected, for the plasmid mouse an increase in MF after Clastogen exposure was expected. The positive control ENU induced statistically significant increases in MF compared with the negative control in both models and in both tissues analyzed. Hybridisation of DNA of mutant colonies derived from plasmid mice with labelled total mouse DNA (Hybridisation Assay) demonstrated an increase in the percentage of colonies hybridised with total mouse DNA as compared with the negative control, which suggests that there was indeed a biological response associated with treatment. The latter results indicate that the plasmid mouse assay may still be a promising model for the detection of Clastogens. © 2008 Elsevier B.V. All rights reserved.
Anuska G. Mahabir - One of the best experts on this subject based on the ideXlab platform.
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comparison of Clastogen induced gene expression profiles in wild type and dna repair deficient rad54 rad54b cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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Comparison of Clastogen-induced gene expression profiles in wild-type and DNA repair-deficient Rad54/Rad54B cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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lacZ mouse embryonic fibroblasts detect both Clastogens and mutagens.
Mutation research, 2009Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Mirjam M Schaap, Coenraad F M Hendriksen, Edwin Zwart, Lya G Hernandez, Harry Van SteegAbstract:The Clastogenic effects of MMC and BLM and the mutagenic effects of B[a]P, N-ac-AAF and ENU were studied in mouse embryonic fibroblasts derived from wild-type (WT) and Rad54/Rad54B-deficient mice. Clastogens as well as mutagens showed a statistically significant induction of mutations in the lacZ reporter gene both in a WT and Rad54/Rad54B-deficient genetic background. Rad54/Rad54B MEFs appeared equally sensitive to the Clastogens compared to WT MEFs, except for MMC. The type of mutations induced by the different compounds was investigated further by hybridizing the mutant colonies with total mouse DNA. An obvious increased number of mouse DNA positive clones was observed after BLM and MMC exposure, indicating that after these treatments genome rearrangements/translocations had occurred. In this hybridization assay, Rad54/Rad54B MEFs did not show more rearrangements/translocations than WT MEFs. As expected, the mutagens used showed no increase in chromosomal rearrangements or transloctions in MEFs derived from both genotypes. These results show that WT MEFs carrying the lacZ reporter gene on a plasmid are capable to detect both Clastogenic as well as mutagenic effects of compounds in vitro. Deletion of the Rad54 and Rad54B genes did not further enhance the sensitivity of MEFs towards Clastogens.
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DNA-repair-deficient Rad54/Rad54B mice are more sensitive to Clastogens than wild-type mice.
Toxicology letters, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Coenraad F M Hendriksen, Mirjam Schaap, Peter Theunissen, Jeroen Essers, Harry Van SteegAbstract:The sensitivity of DNA-repair-deficient Rad54/Rad54B mice for Clastogens was studied and compared to that of wild-type mice. LacZ mutant frequencies (MF) in Rad54/Rad54B mice, after treatment with mitomycin C (MMC), bleomycin (BLM) and gamma-irradiation, were compared to those of the wild-type mice following the same treatments. While none of the Clastogens showed an induction of the lacZ MF in the wild-type mice, there was a significant increase of the lacZ MF in the bone marrow of the Rad54/Rad54B mice after treatment with BLM and gamma-irradiation and in the spleen after MMC treatment. As expected, the positive control ENU showed a significant increase in the lacZ MF in all tested organs in wild-type mice. Mutant colonies were hybridized with total mouse DNA in order to discriminate between small gene mutations and large DNA rearrangements and translocations (size-change mutations). The hybridization studies showed a significant increase in mouse DNA positive clones 4 days after treatment with MMC and BLM in the bone marrow of the wild-type mice, which is indicative for chromosomal rearrangements and translocations to occur. An even more pronounced increase was seen 28 days after treatment with the same compounds in the Rad54/Rad54B mice.
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Detecting genotoxic effects of potential Clastogens: An in vivo study using the transgenic lacZ plasmid and the Muta™Mouse model
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Hanneke Korsten, Anthony M. Lynch, Lorna Bailey, Annemieke De Vries, Coenradus F.m. Hendriksen, Harry Van SteegAbstract:In the present paper the capacity of the pUR288 plasmid mouse model and the Muta TM Mouse model to detect the Clastogens bleomycin, m-AMSA, o-AMSA and camptothecin, was investigated. Ethylnitrosourea (ENU) served as a positive control, methylcellulose as a negative control. Only bleomycin induced a slight but significant increase in lacZ mutant frequency (MF) in bone marrow of pUR288 plasmid mice. Exposure to the other compounds did not result in an increase in the MF in bone marrow and liver in both mouse models. For the Muta TM Mouse this result was expected, for the plasmid mouse an increase in MF after Clastogen exposure was expected. The positive control ENU induced statistically significant increases in MF compared with the negative control in both models and in both tissues analyzed. Hybridisation of DNA of mutant colonies derived from plasmid mice with labelled total mouse DNA (Hybridisation Assay) demonstrated an increase in the percentage of colonies hybridised with total mouse DNA as compared with the negative control, which suggests that there was indeed a biological response associated with treatment. The latter results indicate that the plasmid mouse assay may still be a promising model for the detection of Clastogens. © 2008 Elsevier B.V. All rights reserved.
Jan Van Benthem - One of the best experts on this subject based on the ideXlab platform.
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comparison of Clastogen induced gene expression profiles in wild type and dna repair deficient rad54 rad54b cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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Comparison of Clastogen-induced gene expression profiles in wild-type and DNA repair-deficient Rad54/Rad54B cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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lacZ mouse embryonic fibroblasts detect both Clastogens and mutagens.
Mutation research, 2009Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Mirjam M Schaap, Coenraad F M Hendriksen, Edwin Zwart, Lya G Hernandez, Harry Van SteegAbstract:The Clastogenic effects of MMC and BLM and the mutagenic effects of B[a]P, N-ac-AAF and ENU were studied in mouse embryonic fibroblasts derived from wild-type (WT) and Rad54/Rad54B-deficient mice. Clastogens as well as mutagens showed a statistically significant induction of mutations in the lacZ reporter gene both in a WT and Rad54/Rad54B-deficient genetic background. Rad54/Rad54B MEFs appeared equally sensitive to the Clastogens compared to WT MEFs, except for MMC. The type of mutations induced by the different compounds was investigated further by hybridizing the mutant colonies with total mouse DNA. An obvious increased number of mouse DNA positive clones was observed after BLM and MMC exposure, indicating that after these treatments genome rearrangements/translocations had occurred. In this hybridization assay, Rad54/Rad54B MEFs did not show more rearrangements/translocations than WT MEFs. As expected, the mutagens used showed no increase in chromosomal rearrangements or transloctions in MEFs derived from both genotypes. These results show that WT MEFs carrying the lacZ reporter gene on a plasmid are capable to detect both Clastogenic as well as mutagenic effects of compounds in vitro. Deletion of the Rad54 and Rad54B genes did not further enhance the sensitivity of MEFs towards Clastogens.
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DNA-repair-deficient Rad54/Rad54B mice are more sensitive to Clastogens than wild-type mice.
Toxicology letters, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Coenraad F M Hendriksen, Mirjam Schaap, Peter Theunissen, Jeroen Essers, Harry Van SteegAbstract:The sensitivity of DNA-repair-deficient Rad54/Rad54B mice for Clastogens was studied and compared to that of wild-type mice. LacZ mutant frequencies (MF) in Rad54/Rad54B mice, after treatment with mitomycin C (MMC), bleomycin (BLM) and gamma-irradiation, were compared to those of the wild-type mice following the same treatments. While none of the Clastogens showed an induction of the lacZ MF in the wild-type mice, there was a significant increase of the lacZ MF in the bone marrow of the Rad54/Rad54B mice after treatment with BLM and gamma-irradiation and in the spleen after MMC treatment. As expected, the positive control ENU showed a significant increase in the lacZ MF in all tested organs in wild-type mice. Mutant colonies were hybridized with total mouse DNA in order to discriminate between small gene mutations and large DNA rearrangements and translocations (size-change mutations). The hybridization studies showed a significant increase in mouse DNA positive clones 4 days after treatment with MMC and BLM in the bone marrow of the wild-type mice, which is indicative for chromosomal rearrangements and translocations to occur. An even more pronounced increase was seen 28 days after treatment with the same compounds in the Rad54/Rad54B mice.
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Detecting genotoxic effects of potential Clastogens: An in vivo study using the transgenic lacZ plasmid and the Muta™Mouse model
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Hanneke Korsten, Anthony M. Lynch, Lorna Bailey, Annemieke De Vries, Coenradus F.m. Hendriksen, Harry Van SteegAbstract:In the present paper the capacity of the pUR288 plasmid mouse model and the Muta TM Mouse model to detect the Clastogens bleomycin, m-AMSA, o-AMSA and camptothecin, was investigated. Ethylnitrosourea (ENU) served as a positive control, methylcellulose as a negative control. Only bleomycin induced a slight but significant increase in lacZ mutant frequency (MF) in bone marrow of pUR288 plasmid mice. Exposure to the other compounds did not result in an increase in the MF in bone marrow and liver in both mouse models. For the Muta TM Mouse this result was expected, for the plasmid mouse an increase in MF after Clastogen exposure was expected. The positive control ENU induced statistically significant increases in MF compared with the negative control in both models and in both tissues analyzed. Hybridisation of DNA of mutant colonies derived from plasmid mice with labelled total mouse DNA (Hybridisation Assay) demonstrated an increase in the percentage of colonies hybridised with total mouse DNA as compared with the negative control, which suggests that there was indeed a biological response associated with treatment. The latter results indicate that the plasmid mouse assay may still be a promising model for the detection of Clastogens. © 2008 Elsevier B.V. All rights reserved.
Coenraad F M Hendriksen - One of the best experts on this subject based on the ideXlab platform.
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comparison of Clastogen induced gene expression profiles in wild type and dna repair deficient rad54 rad54b cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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Comparison of Clastogen-induced gene expression profiles in wild-type and DNA repair-deficient Rad54/Rad54B cells
BMC Genomics, 2010Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Mirjam M Schaap, Jeroen L A Pennings, Coenraad F M Hendriksen, Harry Van SteegAbstract:Previously we found that Rad54/Rad54B cells are more sensitive towards mitomycin C (MMC) as compared to wild-type (WT) cells. This difference in sensitivity was absent upon exposure to other Clastogens like bleomycin (BLM) and γ-radiation. In order to get further insight into possible underlying mechanisms, gene expression changes in WT and Rad54/Rad54B MEFs (mouse embryonic fibroblasts) after exposure to the Clastogens MMC and BLM were investigated. Exposures of these cells to mutagens (N-ac-AAF and ENU) and vehicle were taken as controls. Most exposures resulted in an induction of DNA damage signaling and apoptosis genes and a reduced expression of cell division genes in cells of both genotypes. As expected, responses to N-ac-AAF were very similar in both genotypes. ENU exposure did not lead to significant gene expression changes in cells of both genotypes, presumably due to its short half-life. Gene expression responses to Clastogens, however, showed a genotype-dependent effect for BLM and MMC. MMC treated Rad54/Rad54B MEFs showed no induction of p53-signaling, DNA damage response and apoptosis as seen for all the other treatments. These data support our finding that different types of Clastogens exist and that responses to these types depend on the DNA repair status of the cells.
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lacZ mouse embryonic fibroblasts detect both Clastogens and mutagens.
Mutation research, 2009Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Mirjam M Schaap, Coenraad F M Hendriksen, Edwin Zwart, Lya G Hernandez, Harry Van SteegAbstract:The Clastogenic effects of MMC and BLM and the mutagenic effects of B[a]P, N-ac-AAF and ENU were studied in mouse embryonic fibroblasts derived from wild-type (WT) and Rad54/Rad54B-deficient mice. Clastogens as well as mutagens showed a statistically significant induction of mutations in the lacZ reporter gene both in a WT and Rad54/Rad54B-deficient genetic background. Rad54/Rad54B MEFs appeared equally sensitive to the Clastogens compared to WT MEFs, except for MMC. The type of mutations induced by the different compounds was investigated further by hybridizing the mutant colonies with total mouse DNA. An obvious increased number of mouse DNA positive clones was observed after BLM and MMC exposure, indicating that after these treatments genome rearrangements/translocations had occurred. In this hybridization assay, Rad54/Rad54B MEFs did not show more rearrangements/translocations than WT MEFs. As expected, the mutagens used showed no increase in chromosomal rearrangements or transloctions in MEFs derived from both genotypes. These results show that WT MEFs carrying the lacZ reporter gene on a plasmid are capable to detect both Clastogenic as well as mutagenic effects of compounds in vitro. Deletion of the Rad54 and Rad54B genes did not further enhance the sensitivity of MEFs towards Clastogens.
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DNA-repair-deficient Rad54/Rad54B mice are more sensitive to Clastogens than wild-type mice.
Toxicology letters, 2008Co-Authors: Anuska G. Mahabir, Jan Van Benthem, Annemieke De Vries, Coenraad F M Hendriksen, Mirjam Schaap, Peter Theunissen, Jeroen Essers, Harry Van SteegAbstract:The sensitivity of DNA-repair-deficient Rad54/Rad54B mice for Clastogens was studied and compared to that of wild-type mice. LacZ mutant frequencies (MF) in Rad54/Rad54B mice, after treatment with mitomycin C (MMC), bleomycin (BLM) and gamma-irradiation, were compared to those of the wild-type mice following the same treatments. While none of the Clastogens showed an induction of the lacZ MF in the wild-type mice, there was a significant increase of the lacZ MF in the bone marrow of the Rad54/Rad54B mice after treatment with BLM and gamma-irradiation and in the spleen after MMC treatment. As expected, the positive control ENU showed a significant increase in the lacZ MF in all tested organs in wild-type mice. Mutant colonies were hybridized with total mouse DNA in order to discriminate between small gene mutations and large DNA rearrangements and translocations (size-change mutations). The hybridization studies showed a significant increase in mouse DNA positive clones 4 days after treatment with MMC and BLM in the bone marrow of the wild-type mice, which is indicative for chromosomal rearrangements and translocations to occur. An even more pronounced increase was seen 28 days after treatment with the same compounds in the Rad54/Rad54B mice.
James M Parry - One of the best experts on this subject based on the ideXlab platform.
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comparative induction of micronuclei in repair deficient and proficient chinese hamster cell lines following Clastogen or aneugen exposures
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 1997Co-Authors: Thierry Hermine, Nigel J Jones, James M ParryAbstract:Abstract The Chinese hamster cell line V79-4 and two ionising radiation-sensitive mutants irs1 and irs3 , were used to assess the genotoxic effects of a Clastogen (X-rays), an aneugen (podophyllotoxin) and an agent having both activities (etoposide), using the cytokinesis-block micronucleus assay combined with kinetochore labelling. All three agents induced micronuclei in a dose-dependent manner. Between 70 and 90% of the micronuclei induced by X-rays were kinetochore-negative and indicative of Clastogenic activity, the relative frequencies of which were increased in the repair-deficient cell lines. In contrast, podophyllotoxin induced mainly kinetochore-positive micronuclei (up to 97%) and could be classified as an inducer of chromosome lagging and was essentially aneugenic in its activity. Micronuclei induced by etoposide were 61–84% kinetochore-negative and 26–39% kinetochore-positive, indicating both Clastogenic and aneugenic activity. In the case of both etoposide and podophyllotoxin, there were no observed differences in the induction of micronuclei between the wild-type and repair-deficient cell lines. The data demonstrate the effectiveness of the cytokinesis-block micronucleus/kinetochore assay in determining the mechanisms of action of both chemicals and radiations upon chromosome structure and number and the potential influences of repair upon micronuclei induction.