title: Terminal deoxynucleotidyl transferase requires KU80 and XRCC4 to promote N-addition at non-V(D)J chromosomal breaks in non-lymphoid cells.
abstract: Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase that increases the repertoire of antigen receptors by adding non-templated nucleotides (N-addition) to V(D)J recombination junctions. Despite extensive in vitro studies on TdT catalytic activity, the partners of TdT that enable N-addition remain to be defined. Using an intrachromosomal substrate, we show here that, in Chinese hamter ovary (CHO) cells, ectopic expression of TdT efficiently promotes N-additions at the junction of chromosomal double-strand breaks (DSBs) generated by the meganuclease I-SceI and that the size of the N-additions is comparable with that at V(D)J junctions. Importantly, no N-addition was observed in KU80- or XRCC4-deficient cells. These data show that, in a chromosomal context of non-lymphoid cells, TdT is actually able to promote N-addition at non-V(D)J DSBs, through a process that strictly requires the components of the canonical non-homologous end-joining pathway, KU80 and XRCC4.
authors: Institut Pasteur, CNRS URA 2581, 25 rue du Dr. Roux 75724 Paris, France.
authors: Imenne
authors: I
authors: Boubakour-Azzouz
authors: Pascale
authors: P
authors: Bertrand
authors: Aurélie
authors: A
authors: Claes
authors: Bernard S
authors: BS
authors: Lopez
authors: François
authors: F
authors: Rougeon
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear / Q000502:physiology*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000502:physiology*; D000072200:Ku Autoantigen; D009711:Nucleotides / Q000378:metabolism; D060152:V(D)J Recombination
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009711:Nucleotides; D004253:DNA Nucleotidylexotransferase; D000072200:Ku Autoantigen