Hybridization signatures of gamma-irradiated murine fetal thymus organ culture (FTOC) reveal modulation of genes associated with T-cell receptor V(D)J recombination and DNA repair

In this study, we observed the occurrence of TRBV8.1-DB2.1 V(D)J recombination in murine fetal thymus organ culture (FTOC), in which the thymic microenvironment is mimicked. Since ionizing radiation affects T-cell development, we irradiated FTOCs with gamma rays to evaluate the modulation of genes implicated in TRBV8.1-BD2.1 rearrangements. The nylon cDNA microarray method was employed to monitor the expression of 9216 genes, which were organized in coexpression clusters. Clustering analysis showed similar expression profiling of genes implicated in the V(D)J recombination and DNA double strand break (DSB) repair processes such as XRCC4, RAG-2, Artemis and DNA-PK-cs, thus suggesting overlap between the two processes. The RUNX3 gene, whose coded protein binds to the enhancers of TR genes, was also modulated and the DNA cross-linking LR1 gene, which plays a role in the opening of hairpin DNA structures and whose expression pattern is similar to Artemis, may play a role in the control of V(D)J recombination. Furthermore, our data demonstrate that the FTOC model system and cDNA microarray method are useful tools to evidentiate genes that may play a role in both processes V(D)J recombination and DNA repair.