Corrective recombination of mouse immunoglobulin kappa alleles in Abelson murine leukemia virus-transformed pre-B cells.

Abstract

Previous characterization of mouse immunoglobulin K gene rearrangement products cloned from murine plasmacytomas has indicated that two recombination events can take place on a single K allele (R. M. Feddersen and B. G. Van Ness, Proc. Natl. Acad. Sci. USA 82:4792-4797, 1985; M. A. Shapiro and M. Weigert, J. Immunol. 139:3834-3839, 1987). To determine whether multiple recombinations on a single K allele can contribute to the formation of productive V-J genes through corrective recombinations, we have examined several Abelson murine leukemia virus-transformed pre-B-cell clones which rearrange the K locus during cell culture. Clonal cell lines which had rearranged one K allele nonproductively while maintaining the other allele in the germ line configuration were grown, and secondary subclones, which subsequently expressed K protein, were isolated and examined for further K rearrangement. A full spectrum of rearrangement patterns was observed in this sequential cloning, including productive and nonproductive recombinations of the germ line allele and secondary recombinations of the nonproductive allele. The results show that corrective V-J recombinations, with displacement of the nonproductive K gene, occur with a significant frequency (6 of 17 K-producing subclones). Both deletion and maintenance of the primary (nonfunctional) V-J join, as a reciprocal product, were observed.The expression of immunoglobulin by B cells is dependent on gene segment rearrangements which are unique to lymphoid development (41). Highly conserved, site-specific sequences flanking variable (V) and joining (J) gene segments of the kappa (K) light-chain locus direct the complex enzymology required for DNA cutting and ligation (2). In addition to the functional products generated from rearrangement of the K locus, many defective products have been observed (3,7,10,12,14,15,19,27,30,32,36,40,43,44). In fact, from both plasmacytomas and normal B cells it has been estimated that more than one-third of all K rearrangement events are aberrant (11). Collectively, these aberrant rearrangements have suggested that clonal selection may actually mask an otherwise inefficient rearrangement process.In addition to functional and nonfunctional K transcription units, Southern blot hybridization analyses, coupled with cloning and sequencing, have identified reciprocal products of VK-JK recombination (13, 21-23, 37, 39, 42). These byproducts of V-J joining events are characterized by the back-to-back fusion of the recombination signal sequences (the conserved heptamers and nonamers) that border the germ line gene segments. The characterization of reciprocal products supports the intrastrand DNA inversion mechanism of V-J recombination. We and others (12, 38) previously characterized additional products of K locus recombination in mouse plasmacytomas. These novel elements were shown to contain a VK-JK rearrangement followed by the reciprocal element of another VK-JK rearrangement. We designated these double recombination products (DRPs). Significantly, it a...

Preferential rearrangement of V kappa 4 gene segments in pre-B cell lines.

“…One possibility extends the suggestion by Shapiro and Weigert (27) that inversional rearrangements might provide a means by which more distal VK gene segments can be repositioned closer to Ja segments, thereby increasing their probability for recombination . This speculation is consistent with the findings that multiple, sequential VK rearrangements can occur on a single chromosome (26,27,30) . Considering the size of the Va4 family, its central position within the VK region, and the ability of at least some Vu4 genes to rearrange by inversion, the Vic4 family may play a special role in bringing JK segments and distal VK genes together for recombination .…”

B cell receptor editing in tolerance and autoimmunity

“…56,72 Productive V-J rearrangements have been recovered from both excision circles 73 and reciprocal products. 74,75 Single cell PCR studies showed that the frequency of + / + in individual B cells is approximately 10%. 76,77 Lambda L chain rearrangements in murine and human B cells were also frequently allelically included.…”

Lack of feedback inhibition of V kappa gene rearrangement by productively rearranged alleles.

“…Nevertheless, a transgenic K chain present in the cytoplasm did not shut offthe endogenous K gene rearrangement (5). It is also reported that corrective V -J recombinations, with displacement of the nonproductive K gene, occur with a significant frequency in clonal cell lines (7). This suggests that secondary recombinations of one allele may continue unless prevented by the feedback inhibition of a functional product.…”