Immunoglobulin (Ig) class switch recombination (CSR) involves the breakage and subsequent repair of two DNAsequences, known as switch (S) regions, which flank IgH constant region exons. The resolution of CSR-associated breaks is thought to require the nonhomologous end-joining (NHEJ) DNA repair pathway, but the role of the NHEJ factor DNA-dependent protein kinase catalytic subunit (DNA-PKcs) in this process has been unclear. A new study, in which broken IgH-containing chromosomes in switching B cells were visualized directly, clearly demonstrated that DNA-PKcs and, unexpectedly, the nuclease Artemis are involved in the resolution of switchbreaks.
The Journal of Experimental Medicine, 205(3), 509-513.
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