Lipopolysaccharide-induced transcription of the kappa immunoglobulin locus occurs on both alleles and is independent of methylation status

Abstract

The transcriptional activity of the kappa immunoglobulin genes in a B-cell lymphoma line, 7OZ/3 was measured before and after stimulation by lipopolysaccharide (LPS). Analyses of accumulated nuclear RNA components and of nascent transcripts showed that LPS induces transcription of both the productively rearranged (kappa+) and the unrearranged (kappa) allele in these cells. This pattern of transcriptional activation correlates well with the LPS induced appearance of a DNAase I hypersensitive site on both alleles in the vicinity of a putative enhancer element (Parslow and Granner, Nucl. Acids Res. 11, 4775, 1983). However, the transcriptional activation is not accompanied by detectable hypomethylation at Hha I and Hpa II sites which are normally undermethylated when kappa genes are constitutively expressed. These findings have enabled us to evaluate the relative importance of various structural parameters to the transcriptional competence of the kappa locus.