Fig. 1. Efficient VK-JK rearrangements and long-range interactions across the Igk locus upon high Wapl expression in Wapl∆P1,2/∆P1,2 pre-B cells.
a Wapl expression in ex vivo sorted pre-B cells from the bone marrow of Wapl+/+ (black) and Wapl∆P1,2/∆P1,2 (green) mice, as determined by immunoblot analysis of threefold serially diluted whole-cell extracts with antibodies detecting Wapl or the TATA-binding protein (Tbp; loading control). Marker proteins of the indicated size (in kilodaltons, kDa) are shown to the right. The quantification of four independent immunoblot experiments is indicated to the right. Statistical data are shown as mean values with SEM and were analyzed with the Student’s t-test (unpaired and two-tailed). b, c VK gene recombination analysis of ex vivo sorted Wapl+/+ and Wapl∆P1,2/∆P1,2 pre-B cells, as determined by VDJ-seq experiments37. The VDJ-seq data obtained with Wapl+/+ (black) and Wapl∆P1,2/∆P1,2 (green) pre-B cells are shown in the upper and lower part, respectively. The recombination frequency of each VK gene is indicated as a percentage of all VK-JK (b) or only the VK-JK1 (c) rearrangements and is shown as mean value with SEM based on four independent VDJ-seq experiments for each pre-B cell type. The different VK genes (horizontal axis) are aligned according to their position in the Igk locus25 (Supplementary Data 1a). Statistical data were analyzed by multiple t-tests (unpaired and two-tailed) with Holm–Sidak correction; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. d Hi-C contact matrices of the Igk region on chromosome 6, which were determined for ex vivo sorted Wapl+/+, Wapl∆P1,2/∆P1,2, and IghB1-8hi/+ Rag2–/– pre-B cells. The orientation and annotation of the Igk locus are shown. The intensity of each pixel represents the normalized number of contacts between a pair of loci5. The maximum intensity is indicated in the lower left of each panel (red square). The following resolution of the Hi-C data was calculated as described in Methods; 6.65 kb (Wapl+/+ pre-B cells), 4.25 kb (Wapl∆P1,2/∆P1,2 pre-B cells), and 11.8 kb (IghB1-8hi/+ Rag2–/– pre-B cells). One of two Hi-C experiments performed with pre-B cells of each genotype is shown. The VDJ-seq and Hi-C-seq data are further described in Supplementary Data 3. Source data are provided in the Source Data file.