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DNA polymerase eta is involved in hypermutation occurring during immunoglobulin class switch recombination.

Faili A., Aoufouchi S., Weller S., Vuillier F., Stary A., Sarasin A., Reynaud C.-A., Weill J.-C.

Base substitutions, deletions, and duplications are observed at the immunoglobulin locus in DNA sequences involved in class switch recombination (CSR). These mutations are dependent upon activation-induced cytidine deaminase (AID) and present all the characteristics of the ones observed during V gene somatic hypermutation, implying that they could be generated by the same mutational complex. It has been proposed, based on the V gene mutation pattern of patients with the cancer-prone xeroderma pigmentosum variant (XP-V) syndrome who are deficient in DNA polymerase eta (pol eta), that this enzyme could be responsible for a large part of the mutations occurring on A/T bases. Here we show, by analyzing switched memory B cells from two XP-V patients, that pol eta is also an A/T mutator during CSR, in both the switch region of tandem repeats as well as upstream of it, thus suggesting that the same error-prone translesional polymerases are involved, together with AID, in both processes.

J. Exp. Med. 199:265-270(2004) [PubMed] [Europe PMC]