The transcription factor Oct2A enhances V(D)J recombination in fibroblasts

The influence of the transcription factor Oct2A on V(D)J recombination was investigated. It was found that co-transfection of Oct2A together with an artificial recombination substrate increased the rate of V(D)J recombination by a factor of 3.4 in the fibroblast cell line L4 which had been stably transfected with genomic DNA containing the rag-1 and rag-2 genes and their flanking regulatory sequences. This effect, however, was not observed in the pre-B-cell line 38B9. The effect of Oct2A depends on the presence of its transactivation domains indicating that Oct2A increase the transcription of genes that increase the rate of V(D)J recombination. This effect can be reversed by additional co-transfection of the glucocorticoid receptor. In contrast to L4 cells Oct2A and the glucocorticoid receptor had no effect in 38B9 cells. From these results one may conclude that the effect of Oct2A is masked in 38B9 cells by endogenous Oct2A and other redundant pre-B-cell-specific transcription factors and that it can only be seen in cells lacking these factors.