Fig. 6: Erythroid cell-restricted expression of ERFE⁺¹².

(A) May-Grünwald-Giemsa-stained cytospins of erythroid and granulocytic precursors obtained from liquid culture of BM SF3B1^WT or SF3B1^K700E CD34⁺ progenitors. (B) Quantification of ERFE^WT and ERFE⁺¹² in erythroid and granulocytic precursors by RT-qPCR. Results are expressed as NRQ ± SEM to ACTB and B2M housekeeping genes. (C) ERFE⁺¹² is absent in SF3B1^MUT CLL. BM MNCs from a patient with SF3B1^K700E CLL+MDS or PB MNCs from patients with SF3B1^T663I CLL, SF3B1^WT CLL, and SF3B1^K700E MDS were collected for analysis by capillary electrophoresis of ERFE and MAP3K7 fluorescent PCR products. ERFE⁺¹² was detected as a 162-nt fragment and MAP3K7⁺²⁰ as a 170-nt fragment. PB samples from one patient with an SF3B1^WT CLL and one patient with an SF3B1^MUT MDS are shown as controls. (D) ERFE⁺¹² expression is restricted to SF3B1^MUT myeloid lineage. CD19⁺CD5⁻ B cells, CD19⁺CD5⁺ B CLL cells, CD3⁺ T cells, and myeloid cells were sorted from the BM MNC fraction of a SF3B1^K700E CLL+MDS, a SF3B1^K700E MDS, and a SF3B1^WT MDS and from the PB MNCs of a SF3B1^T663I CLL ERFE and MAP3K7 transcripts were analyzed by fluorescent PCR. (E) The sequencing of SF3B1 was performed on cDNA of each cell fraction. +: mutated; WT: wild type; NA: not available.