Extended Data Fig. 2: BMI-1 expression in B cell subsets.

a, Schematic of NP⁻KLH in alum immunization and tamoxifen administration of Bmi1^CreERT2Rosa26^EYFP reporter mice. b, Flow cytometric representative plots EYFP expression in CD19⁺IgD^loCD95^hiCD38^lo (GC) and B220^loCD138^hi cells from immunized Bmi1Rosa26eYFP reporter mice. c, EYFP^- and EYFP⁺ frequencies within B220^loCD138^hi ASC of either IgG, IgA or IgM immunoglobulin isotypes were assessed by flow cytometry; n = 6 mice per group; data represent mean ± SEM; mLN: *P = 0.0411, Spleen: *P = 0.04152, **P = 0.0043 (Mann-Whitney U test, two-tailed p-value). d, Frequency of EYFP⁺ PB (B220^intCD138^hi) and PC (B220⁻CD138^hi) in mesenteric lymph nodes and spleen in immunized mice; n = 6 mice per group, combined from two independent experiments; data represent mean ± SEM; **P < 0.01 (Mann-Whitney U test, two-tailed p-value). e-i, Bmi1^CreERT2Rosa26^EYFP reporter mice and wild-type controls were infected with either LCMV-WE or LCMV-Docile as per schematic in Fig. 1. e, GC B cells were segregated into DZ and LZ subsets and assessed for EYFP⁺ frequency; WE: n = 5 mice, Docile: n = 3 mice; Data represent mean ± SEM. *P = 0.0357 (Mann-Whitney U test, two-tailed p-value). f-i, Assessment of Bmi1 by RT-qPCR in sort-purified populations as follows: f, EYFP⁻and EYFP⁺ lymphocytes in LCMV-Docile-infected mice (2^-𝜟𝜟Ct method relative to EYFP⁻); n = 7 mice per group; data represent mean ± SEM; ***P = 0.0006 (Mann-Whitney U test, two-tailed p-value). g, EYFP⁻and EYFP⁺ GC B cells responding to either LCMV-WE or LCMV-Docile (relative to acute EYFP⁻ GC B cells); n = 3 mice per group; data represent mean ± SEM; **P < 0.01 (Welch’s U test, two-tailed p-value). h, GC B cells from wild-type mice infected with either LCMV-WE or LCMV-Docile (relative to acute GC B cells), d14 post-infection; n = 10 mice per group; data represent mean ± SEM; ****P < 0.0001 (Mann-Whitney U test, two-tailed p-value). i, EYFP⁺ GC B cells and ASCs (relative to GC B cells); n = 3 mice per group; data represent mean ± SEM. *P = 0.0211 (Welch’s U test, two-tailed p-value). j-k, Kinetics of (j) Bmi1 and (k) BMI-1 expression in GC B cells isolated from wild-type mice infected with either LCMV-WE or LCMV-Docile. H3 loading control in bottom panel. RT-qPCR values for (j) combined from 1-3 experiments per timepoint (d7: WE n = 5, Docile n = 6; d14: n = 10 per group; d28: WE n = 4, Docile n = 3; d14 data also shown in h). Data represent mean ± SEM. **P < 0.01 (Mann-Whitney U test, two-tailed p-value). Gels and blots for (k) were processed in parallel, using the same samples.

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