Class switch recombination: an emerging mechanism.
Class switch recombination (CSR) has been the least well understood of the Ig gene DNA rearrangements. The discovery that activation-induced deaminase (AID) is a pivotal player in CSR as well as somatic hypermutation (SHM) and its variant, gene conversion, represents a sea change in our understanding of these processes. The recognition that AID directly deaminates ssDNA has provided a springboard toward the emergence of a model that explains the initiation of these events. Nonhomologous end joining (NHEJ), the main pathway for the repair of double-strand breaks in mammalian cells plays a key role in the resolution of CSR transactions. Mediators of general double-strand break repair are also involved in CSR and are mutated in several immunodeficiency diseases. A global picture of the mechanism of CSR is emerging and is providing new insights toward understanding the genetic events that underlie B cell cancers.
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Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago 60612-7344, USA. star1@uic.edu
D000818:Animals; D003564:Cytidine Deaminase / Q000378:metabolism; D005803:Genes, Immunoglobulin; D006801:Humans; D017578:Immunoglobulin Class Switching; D007134:Immunoglobulin Switch Region / Q000235:genetics*; D051379:Mice; D011995:Recombination, Genetic; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase