Regulation of V(D)J Recombination by Transcriptional Promoters

AUTOR(ES)

Sikes, Michael L.

FONTE

American Society for Microbiology

RESUMO

Enhancer elements potentiate the rearrangement of antigen receptor loci via changes in the accessibility of gene segment clusters to V(D)J recombinase. Here, we show that enhancer activity per se is insufficient to target T-cell receptor β miniloci for DβJβ recombination. Instead, a promoter situated 5′ to Dβ1 (PDβ) was required for efficient rearrangement of chromosomal substrates. A critical function for promoters in regulating gene segment accessibility was further supported by the ability of heterologous promoters to direct rearrangement of enhancer-containing substrates. Importantly, activation of a synthetic tetracycline-inducible promoter (Ptet) positioned upstream from the Dβ gene segment was sufficient to target recombination of miniloci lacking a distal enhancer element. The latter result suggests that DNA loops, generated by interactions between flanking promoter and enhancer elements, are not required for efficient recognition of chromosomal gene segments by V(D)J recombinase. Unexpectedly, the Ptet substrate exhibited normal levels of rearrangement despite its retention of a hypermethylated DNA status within the DβJβ cluster. Together, our findings support a model in which promoter activation, rather than intrinsic properties of enhancers, is the primary determinant for regulating recombinational accessibility within antigen receptor loci.

Documentos Relacionados

• A V(D)J recombinase-inducible B-cell line: role of transcriptional enhancer elements in directing V(D)J recombination.
• Regulation of V(D)J recombination by nucleosome positioning at recombination signal sequences
• Sensing of intermediates in V(D)J recombination by ATM
• Cell cycle regulation of V(D)J recombination-activating protein RAG-2.
• Both V(D)J recombination and radioresistance require DNA-PK kinase activity, though minimal levels suffice for V(D)J recombination