Abstract
Immunoglobulin (Ig) class switch recombination (CSR) is initiated by the transcription-coupled recruitment of activation-induced cytidine deaminase (AID) to Ig switch regions (S regions). During CSR, the IgH locus undergoes dynamic three-dimensional structural changes in which promoters, enhancers, and S regions are brought to close proximity. Nevertheless, little is known about the underlying mechanisms. In this study, we show that Med1 and Med12, two subunits of the mediator complex implicated in transcription initiation and long-range enhancer/promoter loop formation, are dynamically recruited to the IgH locus enhancers and the acceptor regions during CSR and that their knockdown in CH12 cells results in impaired CSR. Furthermore, we show that conditional inactivation of Med1 in B cells results in defective CSR and reduced acceptor S region transcription. Finally, we show that in B cells undergoing CSR, the dynamic long-range contacts between the IgH enhancers and the acceptor regions correlate with Med1 and Med12 binding and that they happen at a reduced frequency in Med1-deficient B cells. Our results implicate the mediator complex in the mechanism of CSR and are consistent with a model in which mediator facilitates the long-range contacts between S regions and the IgH locus enhancers during CSR and their transcriptional activation.
Original language | English (US) |
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Pages (from-to) | 303-312 |
Number of pages | 10 |
Journal | Journal of Experimental Medicine |
Volume | 213 |
Issue number | 3 |
DOIs | |
State | Published - Mar 7 2016 |
Funding
This work was supported by grants to B. Reina-San-Martin from the Agence Nationale pour la Recherche (ANR-Blanc) and the Association for Research on Cancer Foundation (Programme ARC). A.-S. Thomas-Claudepierre was supported by the Ministére de l''Enseignement Supérieur et de la Recherche and the Association for Research on Cancer Foundation. P.P. Rocha is supported by an American Society of Hematology fellowship. J.A. Skok is supported by National Institutes of Health grant R01 GM086852. J.A. Skok and R. Bonneau are supported by National Institutes of Health grant R01GM112192. This study was supported by the grant ANR-10-LABX- 0030-INRT, a French State fund managed by the Agence Nationale de la Recherche under the program Investissements d''Avenir labeled ANR-10-IDEX-0002-02.
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology