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- Enervald, E, et al.
(author)
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A regulatory role for the cohesin loader NIPBL in nonhomologous end joining during immunoglobulin class switch recombination
- 2013
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In: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 210:12, s. 2503-2513
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Journal article (peer-reviewed)abstract
- DNA double strand breaks (DSBs) are mainly repaired via homologous recombination (HR) or nonhomologous end joining (NHEJ). These breaks pose severe threats to genome integrity but can also be necessary intermediates of normal cellular processes such as immunoglobulin class switch recombination (CSR). During CSR, DSBs are produced in the G1 phase of the cell cycle and are repaired by the classical NHEJ machinery. By studying B lymphocytes derived from patients with Cornelia de Lange Syndrome, we observed a strong correlation between heterozygous loss-of-function mutations in the gene encoding the cohesin loading protein NIPBL and a shift toward the use of an alternative, microhomology-based end joining during CSR. Furthermore, the early recruitment of 53BP1 to DSBs was reduced in the NIPBL-deficient patient cells. Association of NIPBL deficiency and impaired NHEJ was also observed in a plasmid-based end-joining assay and a yeast model system. Our results suggest that NIPBL plays an important and evolutionarily conserved role in NHEJ, in addition to its canonical function in sister chromatid cohesion and its recently suggested function in HR.
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- Peron, S, et al.
(author)
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A primary immunodeficiency characterized by defective immunoglobulin class switch recombination and impaired DNA repair
- 2007
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In: The Journal of experimental medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 204:5, s. 1207-1216
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Journal article (peer-reviewed)abstract
- Immunoglobulin class switch recombination (CSR) deficiencies are rare primary immunodeficiencies, characterized by a lack of switched isotype (IgG, IgA, or IgE) production, variably associated with abnormal somatic hypermutation (SHM). Deficiencies in CD40 ligand, CD40, activation-induced cytidine deaminase, and uracil-N-glycosylase may account for this syndrome. We previously described another Ig CSR deficiency condition, characterized by a defect in CSR downstream of the generation of double-stranded DNA breaks in switch (S) μ regions. Further analysis performed with the cells of five affected patients showed that the Ig CSR deficiency was associated with an abnormal formation of the S junctions characterized by microhomology and with increased cell radiosensitivity. In addition, SHM was skewed toward transitions at G/C residues. Overall, these findings suggest that a unique Ig CSR deficiency phenotype could be related to an as-yet-uncharacterized defect in a DNA repair pathway involved in both CSR and SHM events.
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