Antisense intergenic transcription in V(D)J recombination

Abstract

Antigen receptor genes undergo variable, diversity and joining (V(D)J) recombination, which requires ordered large-scale chromatin remodeling. Here we show that antisense transcription, both genic and intergenic, occurs extensively in the V region of the immunoglobulin heavy chain locus. RNA fluorescence in situ hybridization demonstrates antisense transcription is strictly developmentally regulated and is initiated during the transition from DJ(H) to VDJ(H) recombination and terminates concomitantly with VDJ(H) recombination. Our data show antisense transcription is specific to the V region and suggest transcripts extend across several genes. We propose that antisense transcription remodels the V region to facilitate V(H)-to-DJ(H) recombination. These findings have wider implications for V(D)J recombination of other antigen receptor loci and developmental regulation of multigene loci.

Preparing Targets for V(D)J Recombinase: Transcription Paves the Way

“…Over the next decade, correlations between glt and recombination were broadened to encompass nearly all categories of AgR gene segments (6,15). This now even includes antisense transcription detected throughout large clusters of unrearranged gene segments, which may be a pioneering process that opens broad domains of chromatin (16). In this regard, many features of open chromatin, including RAG-nuclease sensitivity, DNA methylation status, and histone modifications, were connected to glt and accompanying recombination (17-21).…”

Variability and Exclusion in Host and Parasite: Epigenetic Regulation of Ig and var Expression

“…Another common feature of the mutually exclusive expression involves timely transcription of sterile transcripts. At the Ig loci, noncoding RNA is transcribed from both DNA strands, giving rise to germline transcripts and to antisense RNA (17,27). This sterile transcription is restricted to a time window just before rearrangement takes place (17,28).…”

“…At the Ig loci, noncoding RNA is transcribed from both DNA strands, giving rise to germline transcripts and to antisense RNA (17,27). This sterile transcription is restricted to a time window just before rearrangement takes place (17,28). In the var system, the assumed noncoding transcripts are generated from the so-called intronic promoters.…”

“…Following DJ rearrangement, genic and intergenic antisense transcripts are generated throughout the IgH V region on both alleles (17). These transcripts appear to be long, extending across several genes, and are rapidly lost from both alleles following VDJ recombination.…”

“…2). These cells are characterized by relocation of the IgH alleles to central nuclear positions (7), changes in histone modification (12)(13)(14)(15)(16), antisense transcription along the entire V H gene cluster (17), and long-range contraction of the IgH locus (18,19), which ultimately results in V H -DJ H recombination. Two different silencing processes are involved in directing an ordered monoallelic IgH rearrangement.…”