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GEO help: Mouse over screen elements for information. |
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| Status |
Public on Sep 25, 2019 |
| Title |
Chromatin Loop Extrusion Plays a Fundamental Mechanistic Role in Antibody Class Switching [3C-HTGTS] |
| Organism |
Mus musculus |
| Experiment type |
Genome variation profiling by high throughput sequencing
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| Summary |
In a B lymphocyte immunoglobulin heavy chain locus (IgH), a developmentally assembled V(D)J exon encoding an antibody variable region lies upstream of exons encoding a m constant region (Cm), allowing generation of mIgH chain transcripts and IgM-class antibodies1. Mouse IgH class switch recombination (CSR) replaces Cmwith one of 6 sets of constant region exons (CHs) that lie 100-200kb downstream1. Each CH is flanked upstream by a promoter, non-coding I-exon, and long repetitive switch (S) region1,2. Cytokines/activators induce specific I-promoter transcription and activation-induced cytidine deaminase (AID)2,3. AID is transcriptionally-targeted to initiate DNA breaks in Sm and activated downstream acceptor S regions, which are joined in deletional orientation to complete CSR4,5. 3’IgH regulatory region (3’IgHRR) enhancers control upstream I promoters and, thereby, CSR via linear competition involving I promoter/3’IgHRR interactions6-11. Here, we report that synapsis of regulatory elements, S regions and DSBs for CSR is achieved by chromatin loop extrusion. In naive B cells, 3’IgHRR enhancers and adjacent 3’IgH CTCF-binding elements (CBEs) interact via loop extrusion with the upstream Igh intronic enhancer (iEm)/Sm locale to generate dynamic 200kb 3’Igh basal loop. In CSR-activated B cells, induced transcription from I-promoters within this basal loop generates dynamic sub-loops that directionally align Sm and target S regions near the 3’IgHRR for CSR. In CH12F3 B lymphoma cells, inactivation of the constitutively active Ia-promoter abrogates looping and CSR to Sa, while activating transcription, looping, and CSR to upstream S regions. CBEs inserted upstream of Ia in convergent orientation with 3’IgH CBEs generate sub-loops that activate inversional Sa CSR. In I-promoter-deleted CH12F3 cells, this ectopic CBE-based sub-loop inactivates upstream S region CSR, while transcriptionally activating non-S region sequences adjacent to the inserted CBEs for S synapsis and CSR. Together, our findings implicate chromatin loop extrusion in the “unprecedented mechanism”5 by which Igh organization in cis promotes orientation-specific CSR DSB joining.
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| Overall design |
We performed CSR-HTGTS-Seq, 3C-HTGTS, GRO-Seq and ChIP-Seq in mature splenic B cells with different stimulation and different mutants of CH12F3 cells to study roles of cohesin-mediated chromatin loop extrusion in IgH class switch recombination.
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| Contributor(s) |
Zhang X, Alt FW |
| Citation(s) |
31666703 |
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| Submission date |
Apr 24, 2019 |
| Last update date |
Nov 15, 2019 |
| Contact name |
Frederick W Alt |
| E-mail(s) |
jianqiao.hu@childrens.harvard.edu
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| Organization name |
Boston Children's Hospital
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| Department |
PCMM
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| Lab |
Alt
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| Street address |
1 Blackfan Circle
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| City |
Boston |
| State/province |
MA |
| ZIP/Postal code |
02115 |
| Country |
USA |
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| Platforms (2) |
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| Samples (75)
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| This SubSeries is part of SuperSeries: |
| GSE130270 |
Chromatin Loop Extrusion Plays a Fundamental Mechanistic Role in Antibody Class Switching |
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| Relations |
| BioProject |
PRJNA534491 |
| SRA |
SRP193755 |
| Supplementary file |
Size |
Download |
File type/resource |
| GSE130263_RAW.tar |
88.7 Mb |
(http)(custom) |
TAR (of BEDGRAPH) |
SRA Run Selector |
| Raw data are available in SRA |
| Processed data provided as supplementary file |
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