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bioRxiv · 10.1101/2024.05.29.596448

Negative regulation of Activation-Induced Cytidine Deaminase gene transcription in developing B cells by a PU.1-interacting intronic region

MacKenzie, A. C.·Sams, M. P.·Lin, J.·Batista, C. R.·Lim, M.·Riarh, C. K.·DeKoter, R. P.
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Abstract

Activation-induced cytidine deaminase (AID, encoded by Aicda) plays a key role in somatic hypermutation and class switch recombination in germinal center B cells. However, off-target effects of AID are implicated in human leukemia and lymphoma. A mouse model of precursor B cell acute lymphoblastic leukemia driven by deletion of the related transcription factors PU.1 and Spi-B revealed C->T transition mutations compatible with being induced by AID. Therefore, we hypothesized that PU.1 negatively regulates Aicda during B cell development. Aicda mRNA transcript levels were increased in leukemia cells and preleukemic bone marrow pre-B cells lacking PU.1 and/or Spi-B, relative to wild type cells. Using chromatin immunoprecipitation, PU.1 was found to interact with a negative regulatory region (R2-1) within the first intron of Aicda. CRISPR-Cas9-induced mutagenesis of R2-1 in cultured pre-B cells resulted in upregulation of Aicda in response to lipopolysaccharide stimulation. Mutation of the PU.1 interaction site and neighboring sequences resulted in reduced repressive ability of R2-1 in transient transfection analysis followed by luciferase assays. These results show that a PU.1-interacting intronic region negatively regulates Aicda transcription in developing B cells.

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MacKenzie, A. C., Sams, M. P., Lin, J., Batista, C. R., Lim, M., Riarh, C. K., DeKoter, R. P.. 2024-06-02. Negative regulation of Activation-Induced Cytidine Deaminase gene transcription in developing B cells by a PU.1-interacting intronic region. https://doi.org/10.1101/2024.05.29.596448

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