Expression of the kappa immunoglobulin light chain gene requires developmental- and tissue-specific regulation by trans-acting factors which Interact with two distinct enhancer elements. A new protein - DNA Interaction has been Identified upstream of the intron enhancer, within the matrix-associated region of the J-C intron. The binding activity Is greatly Inducible in pre-B cells by bacterial lipopolysaccharide and lnterieukin-1 but specific complexes are found at all stages of B cell development tested. The footprinted binding site Is homologous to the consensus AP1 motif. The protein components of this complex are specifically competed by an AP1 consensus motif and were shown by supershlft to include c-Jun and c-Fos, suggesting that this binding site Is an AP1 motif and that the Jun and Fos families of transcription factors play a role In the regulation of the kappa light chain gene. Mutation of the AP1 motif in the context of the intron enhancer was shown to decrease enhancer-mediated activation of the promoter in both pre-B cells Induced with LPS and constitutive expression In mature B cells.
Bibliographical noteFunding Information:
This work was supported by grant GM37687 from the National Institutes of Health and a grant from the Minnesota Medical Foundation. J.S. was a recipient of an Immunology Training Grant from the National Institutes of Health.