Extended Data Fig. 4 |. Normal V(D)J recombination in DNA-PKcs^5A/5A mice and cells.

a, Flow cytometry analyses of lymphocyte development in DNAPKcs^5A/5ATp53^−/− and control mice. b, Frequency of B220⁺IgM⁺ naive mature B cells from spleen. c, Quantification of peripheral RBCs in DNA-PKcs^5A/5A mice with and without TP53 deficiency. Note that wild-type, DNA-PKcs^5A/5A and DNA-PKcs^−/− data from Fig. 2b are included here for comparison. d, e, Absolute counts of peripheral lymphocytes (d) and neutrophils (e) in DNA-PKcs^5A/5A mice with or without Tp53 or Ku70 deficiency. TP53-deficiency rescued both the lymphocytopaenia and the neutropaenia in DNA-PKcs^5A/5A mice. Notably, KU70 deficiency caused severe lymphocytopaenia by itself or with the DNA-PKcs^5A/5A mutation, but rescued the neutropaenia in DNA-PKcs^5A/5A mice. f–h, Chromosomal V(D)J recombination measured in v-ABL kinase-transformed B cells. f, Diagram of pMX-INV chromosomal V(D)J recombination substrate². Empty and filled triangles represent recombination signal sequences. RV, EcoRV, N, NcoI. Dashed line marks the C4 probe used for Southern blotting. g, Southern blotting reveals the accumulation of normal coding joins (CJ) and signal joins (SJ) and suggests successful V(D)J recombination in DNA-PKcs^5A/5A B cells. h, Successful V(D)J recombination places Gfp in the same orientation as the promoter and leads to GFP expression². Plots show the frequency of GFP⁺ cells after 4 days of STI571 (3 μM) treatment. i, Quantification of DN2 and DN3 cells out of all double-negative cells (left, reflecting TCRβ V(D)J recombination) and percentage of CD4⁺ or CD8⁺ single-positive (SP) cells (right, reflecting TCRα V(D)J recombination). b–e, i, Mean ± s.e.m.; two-sided unpaired Student’s t-test. ***P < 0.001, **P < 0.01, *P < 0.05, n.s. P > 0.05. Exact P values and defined sample sizes (n) are provided in Supplementary Data 1.