Expression of recombination-activating genes and T cell receptor gene recombination in the human T cell leukemia cell line

Background Recent studies have suggested that mature T cells can change their specificity through reexpression of recombination-activating genes (RAG) and RAG-mediated V(D)J recombination. This process is named receptor revision and has been observed in mature peripheral T cells from transgenic mice and human donors. However, whether the receptor revision in mature T cells is a random or orientated process remains poorly understood. Here we used the Jurkat human T cell line, which represents a mature stage of T cell development, as a model to investigate the regulation of T cell receptor (TCR) gene recombination. Methods TCR D beta-J beta signal joint T cell receptor excision DNA circles (sjTRECs) were determined by nested and seminested PCR. Double-strand DNA breaks at recombination signal sequences (RSSs) in the TCRV beta chain locus were detected by ligation-mediated-PCR. Further analysis of the complementarity-determining region 3 (CDR3) size of the TCRV beta chain was examined by the TCR GeneScan technique. Results RAG1, RAG2, and three crucial components of the nonhomologous DNA end-joining (NHEJ) pathway were readily detected in Jurkat. Characteristics of junctional diversity of D beta 2-J beta 2 signal joints and ds RSS breaks associated with the D beta 2 5' and D beta 2 3' sites were detected in DNA from Jurkat cells. CDR3 size and the gene sequences of the TCRV beta chain did not change during cell proliferation. Conclusions RAG1 and RAG2 and ongoing TCR gene recombination are coexpressed in Jurkat cells, but the ongoing recombination process may not play a role in modification of the TCR repertoire. However, the results suggest that Jurkat could be used as a model for studying the regulation of RAGs and V(D)J recombination and as a "special" model of the coexistence of TCR gene rearrangements and "negative" receptor revision.