DNA regions flanking the mouse Ig 3' alpha enhancer are differentially methylated and DNAase I hypersensitive during B cell differentiation
Giannini, S.L.; Singh, M.; Calvo, C.F.; Ding, G.; Birshtein, B.K.
Journal of Immunology 150(5): 1772-1780
1993
ISSN/ISBN: 0022-1767 PMID: 8436815 Document Number: 415207
Two B cell-specific enhancer elements are associated with the IgH gene cluster. One enhancer is located within the J-C-mu intron (E-mu), whereas a second enhancer (3'alpha-E) is approximately 12.5 kb 3' of the C-alpha membrane exon. In an attempt to understand the function of 3'alpha-E, we have characterized its surrounding structural milieu during various stages of B cell differentiation through analysis of methylation patterns and the identification of DNAse I-hypersensitive sites. We observed a correlation between the chromatin structure of this region and the differentiation state of the cell. Compared to liver and brain, the region 3' of alpha was hypermethylated in pre-B and T cell lines and became progressively demethylated as B cell differentiation continued. A DNAse I-hypersensitive site was present in pre-B cell lines about 17 kb 3' of 3'alpha-E. In fully differentiated myeloma cell lines, a second cluster of DNAse I-hypersensitive sites was present immediately 5' of 3'alpha. Our data indicate that the 3'alpha enhancer is relatively sequestered during early stages of B cell differentiation and becomes increasingly accessible at later stages.