Research Day
DISTINCT ROLES OF COHESIN STAG1 AND STAG2 IN RECOMBINATION OF ANTIGEN RECEPTOR GENES
Document Type
Abstract
Date
2021
Abstract
Introduction: Mammalian genomes are folded into chromatin loops via cohesin-mediated dynamic extrusion of chromatin to direct genetic functions. Two variants of cohesin, cohesin-STAG1 and cohesin-STAG2, are thought to have distinct roles in the formation of chromatin loops. Previous studies from the lab indicated cohesin-mediated loop extrusion plays important roles in V(D)J recombination, a process critical for generation of highly diverse antigen receptor repertoires for immune defense. It is unknown, however, whether the two cohesin variants contribute differently to V(D)J recombination.
Purpose: We hypothesize that cohesin-STAG1 and cohesin-STAG2 have distinct functions in mediating V(D)J recombination. We will test it at mouse immunoglobulin heavy chain (IgH) locus, which undergoes ordered V(D)J recombination, with D to JH recombine before V to DJH recombination. Methods We utilized CRISPR/Cas9 to generate STAG1 and STAG2 homozygotic knockouts (KO) in mouse B cell lines that can be induced to undergo efficient D to JH recombination but not V to DJH recombination. We then analyzed IgH chromatin interactions and V(D)J recombination with ultra-sensitive assays in control and mutant cell lines.
Results: Loss of STAG2 largely rescues the V to DJH recombination defects in control cells but demonstrates defects in D to JH recombination. Loss of STAG1 shows no significant difference compared with control.
Conclusion: Our results clearly demonstrate distinct roles of cohesin-STAG1 and cohesin-STAG2 in V(D)J recombination, which likely reflects their ability to mediates chromatin loops of different length.