Non-immunoglobulin-associated DNA rearrangements in mouse plasmacytomas.

Abstract

A class of DNA rearrangements in plasmactyomas was characterized. These recombination events involve a DNA sequence whose origin is outside of the locus of the H chain constant region genes, CH. Therefore this sequence was referred to as non-Ig-associated rearranging DNA (NIARD). Two abortively rearranged C.alpha. genes, generated by NIARD events from the .alpha.-producing J558 myeloma, were found. Restriction endonuclease maps of these sequences reveal 2 possible recombination sites in NIARD that are separated Y .apprxeq. 6.5 kilobase pairs of DNA (defined as 5'' and 3'' sites). A NIARD rearrangement occurs in 15 out of 20 plasmacytomas tested, including .gamma.3-, .gamma.1-, .gamma.2b-, .gamma.2a-, and .alpha.-producers, but this event usually does not involve a CH switch (S) region. Only S.alpha. appears to accept NIARD. NIARD did not undergo a rearrangement in 8 IgA-producing hybridomas tested. One germ-line copy of NIARD (a 22-kilobase pair EcoRI fragment) is retained in all plasmacytomas. NIARD does not appear to possess repetitive DNA sequences homologous to S.mu. or S.alpha.. The possible role and implications of NIARD-like sequence rearrangements in allelic exclusion and chromosomal translocation events in plasmacytomas are discussed.