Mutations of the intronic IgH enhancer and its flanking sequences differentially affect accessibility of the JH locus.

摘要: To investigate the role of intronic immunoglobulin heavy chain (IgH) enhancer (E mu) in generating accessibility JH locus for VDJ recombination, we generated ES cells which E mu or its flanking sequences were mutated by replacement with insertion an expressed neor gene. Heterozygous mutant used to generate chimeric mice from pre-B cell lines derived transformation bone marrow Abelson murine leukemia virus (A-MuLV). Comparison rearrangement status normal and alleles individual allowed us assay cis-acting effects mutations. Replacement a 700 bp region immediately downstream core [which includes part 3' matrix associated (MAR) I exon] had no obvious effect on targeted allele, indicating that transcribed gene into JH-C intron does not affect accessibility. In contrast, overlapping 1 kb DNA fragment contains resulted dramatic inhibition rearrangement, demethylation germline transcription locus. Surprisingly, 5' MAR sequence approximately 100 upstream also dramatically decreased recombination linked locus; but, many lines, did prevent this We conclude integrity is required efficient locus, per se, necessarily make it good substrate recombination.