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 6

Sustained Notch2 signaling maintains plasma cell priming.

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Sustained Notch2 signaling maintains plasma cell priming. C57BL/6 mice w...
C57BL/6 mice were treated with anti–Notch2 (αN2) or isotype control antibody for 48 hours, at which time splenocytes were harvested, CTV-labeled, and sorted MZ B cells stimulated in vitro with CpG plus IL-4/5 for 48 or 72 hours. (A) Cell division and CD138 expression for representative cultures at the indicated time points. (B) CD138 surface expression as a function of division number at 72 hours for stimulated MZ or FO B cells from the indicated treatment groups. Shown are mean and SEM for the percentage of all viable CD138+ cells at the indicated division number. **P < 0.01, ***P < 0.001. (C) Summary data cultures derived from 3 animals per treatment are shown as the mean and SEM for each given condition (individual values, ***P < 0.001, 2-way ANOVA, Sidak’s multiple comparison test between antibody treatment groups). (D) Graded numbers of CD138+ cells generated with the indicated stimuli were sorted into ELISpot assays to quantify functional ASCs using 3 to 4 wells/condition. PD indicates PD0332991. Shown are mean and SEM (individual values, *P < 0.05, 2-way ANOVA, Sidak’s multiple comparison test between antibody treatment groups). (E) Representative wells from D for undivided and cells versus cells that had experienced at least one division after stimulation with CpG plus IL-4/5 with or without PD. Data are compiled from 4 animal replicates per group and time point.