MicroRNAs (miRNAs, miRs) regulate cell fate decisions by post-transcriptionally tuning networks of mRNA targets. We used miRNA-directed pathway discovery to reveal a regulatory circuit that influences Ig class switch recombination (CSR). We developed a system to deplete mature, activated B cells of miRNAs, and performed a rescue screen that identified the miR-221/222 family as a positive regulator of CSR. Endogenous miR-221/222 regulated B cell CSR to IgE and IgG1 in vitro, and miR-221/222–deficient mice exhibited defective IgE production in allergic airway challenge and polyclonal B cell activation models in vivo. We combined comparative Ago2-HITS-CLIP and gene expression analyses to identify mRNAs bound and regulated by miR-221/222 in primary B cells. Interrogation of these putative direct targets uncovered functionally relevant downstream genes. Genetic depletion or pharmacological inhibition of Foxp1 and Arid1a confirmed their roles as key modulators of CSR to IgE and IgG1.
MicroRNA-directed pathway discovery elucidates an miR-221/222–mediated regulatory circuit in class switch recombination
Disclosures: The authors declare no competing interests exist.
- Award Id(s): T32AI007334,HL109102,HL107202,T32GM008361,T32AR069516,P30 AI27667,P30 DK063720,P30 AR048311
- Award Id(s): 170769
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Eric J. Wigton, Yohei Mikami, Ryan J. McMonigle, Carlos A. Castellanos, Adam K. Wade-Vallance, Simon K. Zhou, Robin Kageyama, Adam Litterman, Suparna Roy, Daisuke Kitamura, Emily C. Dykhuizen, Christopher D.C. Allen, Hui Hu, John J. O’Shea, K. Mark Ansel; MicroRNA-directed pathway discovery elucidates an miR-221/222–mediated regulatory circuit in class switch recombination. J Exp Med 1 November 2021; 218 (11): e20201422. doi: https://doi.org/10.1084/jem.20201422
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