Fig. 2

XPO1 abnormalities in murine B cells induce hematopoietic irregularities in significantly aged mice. a Schematic representing the Eμ-XPO1 transgenic mouse model, overexpressing either WT, E571K, or E571G XPO1 under immunoglobulin heavy chain (Eμ-) promoter/enhancer elements in c57bl/6 mice. For complete characterization, five founder lines were generated for each genotype. Artistic rendering created with Biorender.com. b A large cohort of Eμ-XPO1 transgenic mice were followed for overall survival (WT, n = 347; E571K, n = 578; E571G, n = 369) and compared with overall survival of C57BL/6 non-transgenic mice (n = 544) and Eμ-TCL1 transgenic mice (n = 246). Mice from all Eμ-XPO1 transgenic founder lines were combined for analysis. No significant changes in survival times between Eμ-XPO1 mice and C57BL/6 non-transgenic mice were observed, both extending past the median survival observed in Eμ-TCL1 mice. Statistical significance of Kaplan–Meier plot determined via log-rank (Mantel-Cox) test. c Automated CBC analysis of peripheral blood collected from aged Eμ-XPO1 mice (WT, n = 4; E571K, n = 7; E571G, n = 4) and age-matched C57BL/6 mice (n = 5). 12-month old Eμ-TCL1 mice (n = 5) were used for comparison. Mice from all Eμ-XPO1 groups were at an increased risk for elevated blood counts (in K/µL) compared to C57BL/6 mice, including total white blood cells (WBC), lymphocytes (LY), neutrophils (NE), and monocytes (MO). Dotted lines indicate the normal accepted range in each analysis. Bars represent mean ± SD. Missing bars indicate the SD exceeded the range determined by axis limits. Statistical significance determined via unpaired t test with Welch’s correction. d Immunophenotypic analysis of peripheral blood from aged (24–32 months) revealed an expansion of CD19 + /CD5 + or CD19 + /B22dim CLL-like cells in a subset of Eμ-XPO1 mice from each XPO1-WT, XPO1-E571K, and XPO1-E571G transgenic mice. This CLL-like expansion was similar to that commonly found in the Eμ-TCL1 mouse model. e Evaluation of a peripheral blood smear (40 × objective) from an Eμ-XPO1^E571G transgenic mouse reveals significant accumulation of lymphocytes in ratios similar to that of a human CLL patient with a blood count of 196. f Representative microscopic images from detailed histopathology analysis demonstrate a subset of aged Eμ-XPO1 mice display a higher incidence of hematopoietic cancer than non-transgenic mice. Seventy five percent (3/4) of analyzed mice from each group (XPO1-WT, XPO1-E571K, and XPO1-E571G) demonstrated hematopoietic neoplasia, consistent in morphology with histiocyte associated lymphoma. Neoplastic infiltrates were present in the livers and lymph nodes of all three mice, as well as the bone marrow (× 40) of a XPO1-E571G mouse. Lymph nodes (4x) and livers (40x) were significantly enlarged in Eμ-XPO1 due to accumulation of neoplastic lymphocytes. Most mice (3/4, 75%) from the C57BL/6 non-transgenic group showed no evidence of hematopoietic neoplasia. g Comparison of IGHV gene usage between splenic B cells from Eµ-XPO1 (XPO1-WT, XPO1-E571K, and XPO1-E571G) and C57BL/6 non-transgenic mice (n = 3 per group). Eµ-XPO1^E571K and Eµ-XPO1^E571G mice demonstrated a majority of BCR usage among the top 10 IGH genes, suggesting less diversity in the BCR repertoire compared to non-transgenic mice. Usage of BCR reads were binned by heavy chain V gene names, with each V gene normalized by the total number of heavy-chain reads. The top 10 most abundant genes are shown in triplicate mice with shared V genes maintaining the same color across all triplicates and samples. Genes not in the top 10 in terms of usage were grouped as “others” (bottom-most segment in each stacked-bar) and shown as a dark forest-green color (see label). Gene names of the top 10 V genes in order of abundance are presented in Additional file 4: Table S1