Normal development of mice lacking <scp>PAXX</scp>, the paralogue of <scp>XRCC</scp>4 and <scp>XLF</scp>

Gago-Fuentes, Raquel; Xing, Mengtan; Sæterstad, Siri; Sarno, Antonio; Dewan, Alisa E.; Beck, Carole; Bradamante, Stefano; Bjørås, Magnar; Oksenych, Valentyn

doi:10.1002/2211-5463.12381

Cited by 35 publications

(65 citation statements)

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“…Mri −/− , Mri +/− , and Mri +/+ mice possessed similar sizes of spleens and thymi, a similar number of splenocytes and thymocytes, and proportions of B and T cells (Figure 1). Similar to Mri-deficient mice, Paxx −/− mice did not have a detectable phenotype [8][9][10][11][12]. However, inactivation of other NHEJ factors resulted in a reduced number of B and T cells (Xlf −/− mice, [4][5][6][7]18,21,23]), and block in B and T cell development (e.g., Artemis −/− [35], Dna-pkcs −/− [36], Ku70 -/- [37], Ku80 −/− [38]; or even embryonic lethality in Xrcc4 −/− [39] and Lig4 −/− [40]).…”

Section: Discussionmentioning

confidence: 90%

“…Fluorescence-activated cell sorting (FACS) analysis was performed as previously described [11,32]. Briefly, spleens and thymi were isolated from 2-month-old mice, and splenocytes and thymocytes were counted using Countess™ Automated Cell Counter (Invitrogen, Carlsbad, CA, United States); the cell suspension was spun down and diluted with PBS to obtain a final cell concentration of 2.5 × 10 7 /mL.…”

Section: Fluorescence-activated Cell Sorting Splenocyte and Thymocymentioning

confidence: 99%

“…Class switch recombination (CSR) from IgM to IgG1 was performed as previously described [11]. Naïve B lymphocytes were purified from spleens of 2-month-old mice using EasySep™ mouse B cell enrichment kit (STEMCELL Technology, Vancouver, Canada; #19854), according to the manufacturers' instructions.…”

Section: Class Switch Recombinationmentioning

confidence: 99%

“…Mice lacking Ku70, Ku80, DNA-PKcs, or Artemis possess severe combined immunodeficient phenotype (SCID), while inactivation of both alleles of the Xlf gene results in 2-3-fold reduced B and T cell counts [1, [4][5][6][7]. Mice lacking PAXX or Mri possess no or very modest phenotype due to functional redundancy with XLF [8][9][10][11][12]. In contrast, mice lacking either XRCC4 or Lig4 demonstrate p53-and Ku-dependent embryonic lethality, which correlates with massive neuronal apoptosis in the central nervous system [1, [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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Generation of a Mouse Model Lacking the Non-Homologous End-Joining Factor Mri/Cyren

et al. 2019

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Classical non-homologous end joining (NHEJ) is a molecular pathway that detects, processes, and ligates DNA double-strand breaks (DSBs) throughout the cell cycle. Mutations in several NHEJ genes result in neurological abnormalities and immunodeficiency both in humans and mice. The NHEJ pathway is required for V(D)J recombination in developing B and T lymphocytes, and for class switch recombination in mature B cells. The Ku heterodimer formed by Ku70 and Ku80 recognizes DSBs and facilitates the recruitment of accessory factors (e.g., DNA-PKcs, Artemis, Paxx and Mri/Cyren) and downstream core factor subunits X-ray repair cross-complementing group 4 (XRCC4), XRCC4-like factor (XLF), and DNA ligase 4 (Lig4). Accessory factors might be dispensable for the process, depending on the genetic background and DNA lesion type. To determine the physiological role of Mri in DNA repair and development, we introduced a frame-shift mutation in the Mri gene in mice. We then analyzed the development of Mri-deficient mice as well as wild type and immunodeficient controls. Mice lacking Mri possessed reduced levels of class switch recombination in B lymphocytes and slow proliferation of neuronal progenitors when compared to wild type littermates. Human cell lines lacking Mri were as sensitive to DSBs as the wild type controls. Overall, we concluded that Mri/Cyren is largely dispensable for DNA repair and mouse development.

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Section: Discussionmentioning

confidence: 90%

Section: Fluorescence-activated Cell Sorting Splenocyte and Thymocymentioning

confidence: 99%

Section: Class Switch Recombinationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generation of a Mouse Model Lacking the Non-Homologous End-Joining Factor Mri/Cyren

et al. 2019

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“…Artemis is a nuclease that processes RAG-induced hairpin-sealed DNA ends, and DNA-PKcs is required to both structurally stabilize and phosphorylate Artemis [6,[19][20][21][22][23]. On the contrary, germline inactivation of XLF [24,25], PAXX [26][27][28][29], or Mri [12,13] had no or modest impact on the DNA repair and lymphocyte development in general, and the V(D)J recombination in particular. Combined inactivation of XLF and PAXX resulted in the V(D)J recombination defect in cells [30][31][32] and synthetic lethality in mice [26,28,29,33].…”

Section: Introductionmentioning

confidence: 99%

Mediator of DNA Damage Checkpoint Protein 1 Facilitates V(D)J Recombination in Cells Lacking DNA Repair Factor XLF

et al. 2019

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DNA double-strand breaks (DSBs) trigger the Ataxia telangiectasia mutated (ATM)-dependent DNA damage response (DDR), which consists of histone H2AX, MDC1, RNF168, 53BP1, PTIP, RIF1, Rev7, and Shieldin. Early stages of B and T lymphocyte development are dependent on recombination activating gene (RAG)-induced DSBs that form the basis for further V(D)J recombination. Non-homologous end joining (NHEJ) pathway factors recognize, process, and ligate DSBs. Based on numerous loss-of-function studies, DDR factors were thought to be dispensable for the V(D)J recombination. In particular, mice lacking Mediator of DNA Damage Checkpoint Protein 1 (MDC1) possessed nearly wild-type levels of mature B and T lymphocytes in the spleen, thymus, and bone marrow. NHEJ factor XRCC4-like factor (XLF)/Cernunnos is functionally redundant with ATM, histone H2AX, and p53-binding protein 1 (53BP1) during the lymphocyte development in mice. Here, we genetically inactivated MDC1, XLF, or both MDC1 and XLF in murine vAbl pro-B cell lines and, using chromosomally integrated substrates, demonstrated that MDC1 stimulates the V(D)J recombination in cells lacking XLF. Moreover, combined inactivation of MDC1 and XLF in mice resulted in synthetic lethality. Together, these findings suggest that MDC1 and XLF are functionally redundant during the mouse development, in general, and the V(D)J recombination, in particular.

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Robust DNA repair in PAXX‐deficient mammalian cells

et al. 2018

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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, XRCC 4, DNA ligase 4, DNA ‐ PK cs, Artemis, and XLF . Paralog of XRCC 4 and XLF ( PAXX ) is the recently described accessory NHEJ factor that structurally resembles XRCC 4 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 HAP 1 cells, PAXX Δ , XRCC 4 Δ , and XLF Δ . In our studies, HAP 1 PAXX Δ cells demonstrated modest sensitivity to DNA damage, which was comparable to wild‐type controls. By contrast, XRCC 4 Δ and XLF Δ HAP 1 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 CH 12F3 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 −/− CH 12F3 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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Normal development of mice lacking PAXX, the paralogue of XRCC4 and XLF

Cited by 35 publications

References 30 publications

Generation of a Mouse Model Lacking the Non-Homologous End-Joining Factor Mri/Cyren

Generation of a Mouse Model Lacking the Non-Homologous End-Joining Factor Mri/Cyren

Mediator of DNA Damage Checkpoint Protein 1 Facilitates V(D)J Recombination in Cells Lacking DNA Repair Factor XLF

Robust DNA repair in PAXX‐deficient mammalian cells

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