Figure 2. miR-19 plays a critical role in regulating B-cell central tolerance.

(a) Lentiviral vectors expressing the FL miR-17∼92, its deletion mutants and individual members. miRNAs sharing the same seed region belong to the same subfamily and are depicted in the same colour. (b) Northern blot analysis of miRNA expression in HeLa cells transduced with indicated lentiviruses. (c) Outline of experimental strategy. HSCs were enriched from WT donors to facilitate the transduction by lentiviruses encoding various combinations of miR-17∼92 miRNAs (LV-miRNAs). (d) Representative flow cytometry plots of lymphocytes from the spleen of recipient mice. It is noteworthy that lentiviruses encoding miR-17∼92 (FL) fully rescued the B-cell compartment, and that virus transduced cells (CD45.2⁺GFP⁺) outcompeted WT helper-derived cells (CD45.2⁻GFP⁻) and non-transduced cells (CD45.2⁺GFP⁻). (e) Numbers of splenic B cells in IgM^b-macroself recipient mice. B-cell number above the dash line indicates break of tolerance. Data are representative of 3 (b) or 8 (d) or pooled from 8 independent experiments (e) (mean±s.e.m. in e) with n=5 (Vector) or 14 (FL) in d, and n=5 (Vector and del18), 14 (FL), 10 (del17 and 4 × 19), 4 (del19 and del92) or 6 (4 × 17, 4 × 18 and 4 × 92) in e.