Resting innate-like B cells leverage sustained Notch2/mTORC1 signaling to achieve rapid and mitosis-independent plasma cell differentiation
Brian T. Gaudette, Carly J. Roman, Trini A. Ochoa, Daniela Gómez Atria, Derek D. Jones, Christian W. Siebel, Ivan Maillard, David Allman
Brian T. Gaudette, Carly J. Roman, Trini A. Ochoa, Daniela Gómez Atria, Derek D. Jones, Christian W. Siebel, Ivan Maillard, David Allman
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Research Article Immunology

Resting innate-like B cells leverage sustained Notch2/mTORC1 signaling to achieve rapid and mitosis-independent plasma cell differentiation

Abstract

Little is known about how cells regulate and integrate distinct biosynthetic pathways governing differentiation and cell division. For B lineage cells it is widely accepted that activated cells must complete several rounds of mitosis before yielding antibody-secreting plasma cells. However, we report that marginal zone (MZ) B cells, innate-like naive B cells known to generate plasma cells rapidly in response to blood-borne bacteria, generate functional plasma cells despite cell-cycle arrest. Further, short-term Notch2 blockade in vivo reversed division-independent differentiation potential and decreased transcript abundance for numerous mTORC1- and Myc-regulated genes. Myc loss compromised plasma cell differentiation for MZ B cells, and reciprocally induced ectopic mTORC1 signaling in follicular B cells enabled division-independent differentiation and plasma cell–affiliated gene expression. We conclude that ongoing in situ Notch2/mTORC1 signaling in MZ B cells establishes a unique cellular state that enables rapid division-independent plasma cell differentiation.

Authors

Brian T. Gaudette, Carly J. Roman, Trini A. Ochoa, Daniela Gómez Atria, Derek D. Jones, Christian W. Siebel, Ivan Maillard, David Allman

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Figure 4

Induction of a plasma cell transcriptome despite cell-cycle arrest.

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Induction of a plasma cell transcriptome despite cell-cycle arrest. RNAs...
RNAseq was performed on cells sorted as in Supplemental Figure 4. Division-inhibited cells were sorted from undiluted CTV gate. (A) Expression of UPR hallmark genes previously shown to be upregulated in follicular (FO) B cells treated with an activation stimulus only (CpG) (top) versus those upregulated only in follicular B cells given a plasma cell inductive stimulus (CpG plus IL-4/5) (bottom) shown as a heat map by Z score across each row (22). (B) GSEA for the Protein Secretion Hallmark gene-set (left) and B220– BM plasma cell signature versus follicular B cells (right) as defined by the top 250 genes upregulated in B220– BM plasma cells versus follicular B cells (22) in MZ B cells stimulated with CpG plus IL-4/5 compared with freshly isolated cells with and without cell-cycle inhibition by PD0332991 or rapamycin is shown. NES: Normalized Enrichment Score; Nom.p.val: Nominal P value; and FDR.q.val: FDR q value. FDR-q computed using 1000 gene-set permutations. (C) Log2 TPM for the indicated genes is shown as the mean (line), 75% CI (box) and 95% CI (whisker) together with individual data points (jitter). All RNAseq data shown are prepared from 4 to 5 animal replicates.