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 8

mTORC1 activity confers accelerated PC differentiation kinetics for follicular B cells.

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mTORC1 activity confers accelerated PC differentiation kinetics for foll...
Tsc1fl/fl.hCD20TamCre, Tsc1fl/+.hCD20TamCre, and Tsc1+/+.hCD20TamCre mice were fed tamoxifen in their diet for 14 or 28 days, at which point follicular B cells were CTV-labeled, sorted, then stimulated as indicated for 48 and 72 hours. (A) CD138 expression and CTV dilution for cultures from representative animals fed tamoxifen for 28 days are shown. (B) Data for cultures derived from 5 to 6 individuals per group are shown as individual points, mean and SEM. *P < 0.05, **P < 0.01, ***P < 0.001; 2-way ANOVA, Tukey’s multiple comparison test between genotypes. (C) CD138 surface expression as a function of division number at 72 hours illustrating mean and SEM for the percentage of viable CD138+ cells at the indicated division number. *P < 0.05, **P < 0.01; 2-way ANOVA, Tukey’s multiple comparison test between color- and letter-coded genotypes. (D) Cultures described in A were sorted into ELISpot assays to quantify functional ASCs. Shown are representative wells for each treatment and time point. For undivided and postdivision cells CD138+ cells were added at a dose of 300 per well. Paired wells are sorted +1 division, 0 division. (E) Summary of ELISpot data derived from 3 to 4 cultures per condition in D is shown as the individual values, mean and SEM. *P < 0.05, ***P < 0.001, 2-way ANOVA, Sidak’s multiple comparison test between antibody treatment groups.