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The PI3K pathway plays a key role in B cell activation and is important for the differentiation of Ab producing plasma cells (PCs). Although much is known about the molecular mechanisms that modulate PI3K signaling in B cells, the transcriptional regulation of PI3K expression is poorly understood. In this study, we identify the zinc finger protein Zbtb18 as a transcriptional repressor that directly binds enhancer/promoter regions of genes encoding class I PI3K regulatory subunits, subsequently limiting their expression, dampening PI3K signaling and suppressing PC responses. Following activation, dividing B cells progressively downregulated Zbtb18, allowing gradual amplification of PI3K signals and enhanced development of PCs. Human Zbtb18 displayed similar expression patterns and function in human B cells, acting to inhibit development of PCs. Furthermore, a number of Zbtb18 mutants identified in cancer patients showed loss of suppressor activity, which was also accompanied by impaired regulation of PI3K genes. Taken together, our study identifies Zbtb18 as a repressor of PC differentiation and reveals its previously unappreciated function as a transcription modulator of the PI3K signaling pathway.

Original publication

DOI

10.4049/jimmunol.2000367

Type

Journal article

Journal

J Immunol

Publication Date

01/04/2021

Volume

206

Pages

1515 - 1527

Keywords

Animals, B-Lymphocytes, Cell Differentiation, Gene Expression Regulation, Humans, Immunity, Humoral, Lymphocyte Activation, Mice, Mice, Inbred C57BL, Mutation, Neoplasms, Phosphatidylinositol 3-Kinases, Plasma Cells, Repressor Proteins, Signal Transduction