The first steps of murine immunoglobulin heavy-chain (IgH) gene recombination take place within a chromosomal domain that contains diversity (DH) and joining (JH) gene segments, but not variable (VH) gene segments. Here we show that the chromatin state of this domain is markedly heterogeneous. Specifically, only 5′- and 3′-most DH gene segments carry active chromatin modifications, whereas intervening DHs are associated with heterochromatic marks that are maintained by ongoing histone deacetylation. The intervening DHs form part of a tandemly repeated sequence that expresses tissue-specific, antisense oriented transcripts. We propose that the intervening DH genes are actively suppressed by repeat-induced epigenetic silencing, which is reflected in their infrequent representation in DJH junctions compared to the flanking DH genes.
ASJC Scopus subject areas
- Molecular Biology