Active lambda and kappa antibody gene rearrangement in Abelson murine leukemia virus-transformed pre-B cell lines.

Abstract

The two Abelson murine leukemia virus (A-MuLV)-transformed cell lines, BM18-4 and ABC-1, undergo immunoglobulin L-chain gene recombination during passage in tissue culture. BM18-4 cells are capable of kappa gene recombination, whereas ABC-1 cells are capable of both kappa and lambda gene recombination. The expression of H chains is apparently not necessary for continuing L chain gene recombination in either of these cells, although H-chain expression may have been involved in the initiation of L-chain gene recombination. All ABC-1 cells that have lambda gene rearrangements also display recombined kappa alleles, supporting the hypothesis that kappa and lambda gene recombination are initiated in an ordered, developmentally regulated manner in maturing B cells. However, analyses of the ABC-1 line indicate that pre-B cells that have initiated lambda gene recombination do not terminate kappa gene rearrangement. The lambda gene recombinations that occur in the ABC-1 cell line indicate that the germline order of lambda gene segments is: 5' ... V lambda 2 ... J lambda 2C lambda 2-J lambda 4C lambda 4 ... V lambda 1 ... J lambda 3C lambda 3-J lambda 1C lambda 1 ... 3'. In addition, the frequencies of lambda 1, lambda 2, and lambda 3 gene recombinations among ABC-1 cells are quite different than the frequencies of B cells producing lambda 1, lambda 2, and lambda 3 L-chains in the mouse. RS DNA recombinations also occur in the BM18-4 and ABC-1 cell lines, supporting the notion that Ig gene recombinases are involved in RS rearrangement. Recombined RS segments are infrequent among BM 18-4 cells but common among ABC-1 cells, suggesting that RS recombinational events often occur in maturing pre-B cells just before initiation of lambda gene rearrangements. This developmental timing is consistent with the hypothesis that RS recombination may be involved in the initiation of lambda gene assembly.

Ordered activation of the Ig lambda locus in Abelson B cell lines.

“…This order of rearrangement events is in accordance with the analysis of most mouse and human X-producing myeloma lines (9,11) although exceptions to the rule have been found (20,21). A correlation between X and RS rearrangements has also been described in the Abelson line ABC-1 (22) . RS rearrangements may be initiated only in x-pre-B cells since both VxJx complexes of BIP8-7b were unproductive .…”

“…Rearrangements of RS and VX segments may be controlled by the same factors that would in general first activate RS rearrangements, because during B cell development the Igx locus is "opened" earlier than the IgX locus (23) . A functional role of RS rearrangements was proposed in two alternative models, suggesting that either an activation signal would be generated by the product of an RS rearrangement or a repressing signal would be removed by the deletion of inhibitory sequences or genes lying between the Jx and RS elements (22) . The existence of a regulatory active VKRS protein seems unlikely because Vx and RS sequences are often joined in different reading frames (9), all of which are terminated soon after the VKRS junction (see also VKRS sequences of BIP8-7b-2 and BlP8-7b-3 in Fig.…”

The Eλ3–1 enhancer is essential for V(D)J recombination of the murine immunoglobulin lambda light chain locus

“…Thus, whilst each cluster of two JC genes has its own downstream enhancer, two enhancers surround V 1 -JC 3 -JC1. Consistent with a role of E [2][3][4] in stimulating rearrangement of V 1 -JC 1 and V 1 -JC 3 , these rearrangements occur at a higher frequency than that of V 2 -JC 2 [22]. These data also raise the possibility that cross talk between E 3-1 and E [2][3][4] , that map >100 kb apart, is required for full chromatin opening and activation of Ig recombination.…”

A novel enhancer in the immunoglobulin lambda locus is duplicated and functionally independent of NF kappa B.

“…Thus, each cluster of two JC genes has its own downstream enhancer. The fact that VI-JC3-]C1 is surrounded by two enhancers may explain why rearrangement of VI-]C3 and Vl-lC1 occurs at a much higher frequency than rearrangement of V2-JC2 (Persiani et al 1987). Finally, the expression of V2 to IC3 or IC1 rearranged genes is driven by E~.I, because E~.4 is deleted by this rearrangement (Storb et al 1989).…”