Robust DNA repair in PAXX‐deficient mammalian cells

To ensure genome stability, mammalian cells employ several DNA repair pathways. Nonhomologous DNA end joining (NHEJ) is the DNA repair process that fixes double‐strand breaks throughout the cell cycle. NHEJ is involved in the development of B and T lymphocytes through its function in V(D)J recombina...

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Main Authors: Alisa Dewan, Mengtan Xing, Marie Benner Lundbæk, Raquel Gago‐Fuentes, Carole Beck, Per Arne Aas, Nina‐Beate Liabakk, Siri Sæterstad, Khac Thanh Phong Chau, Bodil Merete Kavli, Valentyn Oksenych
Format: Article
Language:English
Published: Wiley 2018-03-01
Series:FEBS Open Bio
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Online Access:https://doi.org/10.1002/2211-5463.12380
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author Alisa Dewan
Mengtan Xing
Marie Benner Lundbæk
Raquel Gago‐Fuentes
Carole Beck
Per Arne Aas
Nina‐Beate Liabakk
Siri Sæterstad
Khac Thanh Phong Chau
Bodil Merete Kavli
Valentyn Oksenych
author_facet Alisa Dewan
Mengtan Xing
Marie Benner Lundbæk
Raquel Gago‐Fuentes
Carole Beck
Per Arne Aas
Nina‐Beate Liabakk
Siri Sæterstad
Khac Thanh Phong Chau
Bodil Merete Kavli
Valentyn Oksenych
author_sort Alisa Dewan
collection DOAJ
description To ensure genome stability, mammalian cells employ several DNA repair pathways. Nonhomologous DNA end joining (NHEJ) is the DNA repair process that fixes double‐strand breaks throughout the cell cycle. NHEJ is involved in the development of B and T lymphocytes through its function in V(D)J recombination and class switch recombination (CSR). NHEJ consists of several core and accessory factors, including Ku70, Ku80, XRCC4, DNA ligase 4, DNA‐PKcs, Artemis, and XLF. Paralog of XRCC4 and XLF (PAXX) is the recently described accessory NHEJ factor that structurally resembles XRCC4 and XLF and interacts with Ku70/Ku80. To determine the physiological role of PAXX in mammalian cells, we purchased and characterized a set of custom‐generated and commercially available NHEJ‐deficient human haploid HAP1 cells, PAXXΔ, XRCC4Δ, and XLFΔ. In our studies, HAP1 PAXXΔ cells demonstrated modest sensitivity to DNA damage, which was comparable to wild‐type controls. By contrast, XRCC4Δ and XLFΔ HAP1 cells possessed significant DNA repair defects measured as sensitivity to double‐strand break inducing agents and chromosomal breaks. To investigate the role of PAXX in CSR, we generated and characterized Paxx−/− and Aid−/− murine lymphoid CH12F3 cells. CSR to IgA was nearly at wild‐type levels in the Paxx−/− cells and completely ablated in the absence of activation‐induced cytidine deaminase (AID). In addition, Paxx−/− CH12F3 cells were hypersensitive to zeocin when compared to wild‐type controls. We concluded that Paxx‐deficient mammalian cells maintain robust NHEJ and CSR.
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spelling doaj-art-0f0d2ee0a04d40a2b098eebdd4c7dabf2025-08-20T01:57:24ZengWileyFEBS Open Bio2211-54632018-03-018344244810.1002/2211-5463.12380Robust DNA repair in PAXX‐deficient mammalian cellsAlisa Dewan0Mengtan Xing1Marie Benner Lundbæk2Raquel Gago‐Fuentes3Carole Beck4Per Arne Aas5Nina‐Beate Liabakk6Siri Sæterstad7Khac Thanh Phong Chau8Bodil Merete Kavli9Valentyn Oksenych10Department of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayDepartment of Clinical and Molecular Medicine (IKOM) Norwegian University of Science and Technology Trondheim NorwayTo ensure genome stability, mammalian cells employ several DNA repair pathways. Nonhomologous DNA end joining (NHEJ) is the DNA repair process that fixes double‐strand breaks throughout the cell cycle. NHEJ is involved in the development of B and T lymphocytes through its function in V(D)J recombination and class switch recombination (CSR). NHEJ consists of several core and accessory factors, including Ku70, Ku80, XRCC4, DNA ligase 4, DNA‐PKcs, Artemis, and XLF. Paralog of XRCC4 and XLF (PAXX) is the recently described accessory NHEJ factor that structurally resembles XRCC4 and XLF and interacts with Ku70/Ku80. To determine the physiological role of PAXX in mammalian cells, we purchased and characterized a set of custom‐generated and commercially available NHEJ‐deficient human haploid HAP1 cells, PAXXΔ, XRCC4Δ, and XLFΔ. In our studies, HAP1 PAXXΔ cells demonstrated modest sensitivity to DNA damage, which was comparable to wild‐type controls. By contrast, XRCC4Δ and XLFΔ HAP1 cells possessed significant DNA repair defects measured as sensitivity to double‐strand break inducing agents and chromosomal breaks. To investigate the role of PAXX in CSR, we generated and characterized Paxx−/− and Aid−/− murine lymphoid CH12F3 cells. CSR to IgA was nearly at wild‐type levels in the Paxx−/− cells and completely ablated in the absence of activation‐induced cytidine deaminase (AID). In addition, Paxx−/− CH12F3 cells were hypersensitive to zeocin when compared to wild‐type controls. We concluded that Paxx‐deficient mammalian cells maintain robust NHEJ and CSR.https://doi.org/10.1002/2211-5463.12380CH12F3class switch recombinationetoposideHAP1IgAzeocin
spellingShingle Alisa Dewan
Mengtan Xing
Marie Benner Lundbæk
Raquel Gago‐Fuentes
Carole Beck
Per Arne Aas
Nina‐Beate Liabakk
Siri Sæterstad
Khac Thanh Phong Chau
Bodil Merete Kavli
Valentyn Oksenych
Robust DNA repair in PAXX‐deficient mammalian cells
FEBS Open Bio
CH12F3
class switch recombination
etoposide
HAP1
IgA
zeocin
title Robust DNA repair in PAXX‐deficient mammalian cells
title_full Robust DNA repair in PAXX‐deficient mammalian cells
title_fullStr Robust DNA repair in PAXX‐deficient mammalian cells
title_full_unstemmed Robust DNA repair in PAXX‐deficient mammalian cells
title_short Robust DNA repair in PAXX‐deficient mammalian cells
title_sort robust dna repair in paxx deficient mammalian cells
topic CH12F3
class switch recombination
etoposide
HAP1
IgA
zeocin
url https://doi.org/10.1002/2211-5463.12380
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