V(D)J recombination of immunoglobulin genes

We have constructed transgenic mice carrying an artificial substrate of V(D)J recombination. In this substrate, the only DNA fragments derived from Ig genes were short stretches of recombination signal sequences. This artificial substrate was rearranged at high frequency in lymphocytes, although in non-lymphoid cells no rearrangement was detected even by a sensitive PCR assay. This result indicates that the V(D)J recombination requires only the signal sequences and that a recombination similar to the V(D)J recombination does not occur in non-lymphoid tissues including the central nervous tissue. A protein binding to the V(D)J recombination signals was purified and its cDNA was cloned. This protein, termed RBP-J kappa, was initially considered to be involved in V(D)J recombination because of its DNA binding specificity and structural similarity to site-specific recombinases known as the integrase family. However, further study on the Drosophila homolog of RBP-J kappa indicated that RBP-J kappa probably functions as a transcription factor in the differentiation of the peripheral nervous tissues. The exact function of RBP-J kappa is still unknown. Analogous to the Drosophila gene, it is suggested that mouse RBP-J kappa participates in the regulation of differentiation of various tissues.