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Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells

Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Ce...

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Autores principales: Suzuki, Tetsuya, Yasui, Manabu, Honma, Masamitsu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Microbiology 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108877/
https://www.ncbi.nlm.nih.gov/pubmed/27601585
http://dx.doi.org/10.1128/MCB.00443-16
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author Suzuki, Tetsuya
Yasui, Manabu
Honma, Masamitsu
author_facet Suzuki, Tetsuya
Yasui, Manabu
Honma, Masamitsu
author_sort Suzuki, Tetsuya
collection PubMed
description Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS.
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spelling pubmed-51088772016-11-18 Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells Suzuki, Tetsuya Yasui, Manabu Honma, Masamitsu Mol Cell Biol Articles Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS. American Society for Microbiology 2016-11-14 /pmc/articles/PMC5108877/ /pubmed/27601585 http://dx.doi.org/10.1128/MCB.00443-16 Text en Copyright © 2016 Suzuki et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Articles
Suzuki, Tetsuya
Yasui, Manabu
Honma, Masamitsu
Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title_full Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title_fullStr Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title_full_unstemmed Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title_short Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells
title_sort mutator phenotype and dna double-strand break repair in blm helicase-deficient human cells
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108877/
https://www.ncbi.nlm.nih.gov/pubmed/27601585
http://dx.doi.org/10.1128/MCB.00443-16
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