Asymmetrical forward and reverse developmental trajectories determine molecular programs of B cell antigen receptor editing

ABSTRACT: During B lymphopoiesis, B cell progenitors progress through alternating and mutually exclusive stages of clonal expansion and immunoglobulin (Ig) gene rearrangements. Great diversity is generated through the stochastic recombination of Ig gene segments encoding heavy and light chain variable domains. However, this commonly generates autoreactivity. Receptor editing is the predominant tolerance mechanism for self-reactive B cells in the bone marrow (BM). B cell receptor editing rescues autoreactive B cells from negative selection through renewed light chain recombination first at Igκ then Igλ loci. Receptor editing depends upon BM microenvironment cues and key transcription factors such as Nuclear factor kappa B, Forkhead box protein O and Transcription Factor 3. The specific BM factor required for receptor editing is unknown. Furthermore, how transcription factors coordinate these developmental programs to promote usage of the λ-chain remain poorly defined. Therefore, we utilized two mouse models that recapitulate pathways by which Igλ light chain positive B cells develop. The first possess deleted J kappa (Jκ) genes and, as such, models Igκ expression resulting from failed Igκ recombination (Igκdel). The second models autoreactivity by ubiquitous expression of a single-chain chimeric anti-Igκ antibody (κ-mac). Here, we demonstrated that autoreactive B cells transit asymmetric forward and reverse developmental trajectories. This imparted a unique epigenetic landscape on small pre-B cells, which opened chromatin to transcription factors essential for Igλ recombination. The consequences of this asymmetric developmental path were both amplified and complemented by CXCR4 signaling. These findings reveal how intrinsic molecular programs integrate with extrinsic signals to drive receptor editing.

ORGANISM(S): Mus musculus

PROVIDER: GSE173652 | GEO | 2022/07/06

REPOSITORIES: GEO