The recruitment of activation induced cytidine deaminase to the immunoglobulin locus by a regulatory element

Activation induced cytidine deaminase (AID) is critical for the diversification of immunoglobulin (Ig). AID is generally thought to function by deaminating cytidines into uridines in the target DNA within the Ig loci, and the subsequent processing of the uridines, through DNA repair or replication, could lead to three different forms of Ig diversification events: class switch recombination, somatic hypermutation and gene conversion. Although AID is important for effective immunity, its mutagenic activity needs to be restricted to the Ig loci in order to avoid rampant mutations in the genome. In our previous studies, we have identified an Igλ regulatory element (Region A) that is important for AID mediated gene conversion in chicken B cells, but its mechanism of function was unclear. In this report, we provide evidence that the regulatory element plays a role in recruiting AID to the Igλ locus.