Inlay MA, Tian H, Lin T, Xu Y. Important roles for E protein binding sites within the immunoglobulin kappa chain intronic enhancer in activating Vkappa Jkappa rearrangement.
ACTA ACUST UNITED AC 2004;
200:1205-11. [PMID:
15504821 PMCID:
PMC2211861 DOI:
10.1084/jem.20041135]
[Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The immunoglobulin κ light chain intronic enhancer (iEκ) activates κ rearrangement and is required to maintain the earlier or more efficient rearrangement of κ versus lambda (λ). To understand the mechanism of how iEκ regulates κ rearrangement, we employed homologous recombination to mutate individual functional motifs within iEκ in the endogenous κ locus, including the NF-κB binding site (κB), as well as κE1, κE2, and κE3 E boxes. Analysis of the impacts of these mutations revealed that κE2 and to a lesser extent κE1, but not κE3, were important for activating κ rearrangement. Surprisingly, mutation of the κB site had no apparent effect on κ rearrangement. Comparable to the deletion of the entire iEκ, simultaneous mutation of κE1 and κE2 reduces the efficiency of κ rearrangement much more dramatically than either κE1 or κE2 mutation alone. Because E2A family proteins are the only known factors that bind to these E boxes, these findings provide unambiguous evidence that E2A is a key regulator of κ rearrangement.
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