Figure 6.

Colony forming unit assay (CFU) assay with BM samples of Ctnnb1^BM-GOF and Ctnnb1^BM-CTL animals. (A) Isolated BM nucleated cells cultured in MethoCult medium including TPO and 4-OHT after 10 days of cultivation. Arrows point to cells with MK morphology. (B) Quantification of CFU types in BM cells from CTL (n = 6) and Ctnnb1BM-GOF^wt/fl (n = 5) based upon microscopically visible colonies (BFU-E/CFU-E, CFU-MK, -GEMM, -GM, -M, -EM, -G). (C) Comparison of BFU-E/CFU-E and CFU-MK downstream of MEP in BM cells from CTL (n = 6) and Ctnnb1BM-GOF^wt/fl (n = 5) mice. Scale bar: 100 μm. (D) Analysis of MK-specific Runx1 and Fli1 transcription factors (TFs) expression in FACS sorted MKPs of the spleen from CTL (n = 3) and Ctnnb1_BM-GOFwt/fl (n = 3). All expression levels were normalized to 18s. (E) Model of how β-catenin GOF might favor megakaryopoiesis and repress erythropoiesis. Constitutively activated Wnt/β-catenin signaling favors megakaryocytic cell-fate decision by increasing FLI1 and RUNX1 expression, which reinforces the inhibitory effect on erythropoiesis via inhibiting krueppel-like factor 1 (KLF1). Significance is indicated as follows: ***, p < 0.001.