The Common Genomic Locus Of Evl And Mir-342 Regulates Both Lymphopoiesis And Myelopoiesis

Hematopoietic stem cell (HSC) regulation is controlled by extrinsic and intrinsic factors adapting blood cell production to the need of the organism. To search for novel HSC regulatory genes, our group has established a unique screening approach. By systematically analyzing the entire integration site (IS) repertoire of ten Wiskott-Aldrich syndrome (WAS) patients enrolled in clinical gene therapy trials, we hypothesize to identify novel key regulatory genes in hematopoiesis. By applying our screening pipeline based on the number and distance of IS to the transcription start sites (TSS) of genes, we observed a statistically significant number of therapeutic vector insertions close to 32 single genes in nine out of ten WAS patients including the Evl/miR-342 gene locus which has not been linked to hematopoiesis so far. Common insertion sites close to Evl/miR-342 accounted for up to 1.2% of relative sequencing reads within the peripheral blood (PB) of patients and clones harboring such integrations contributed to hematopoiesis for up to six years. We therefore hypothesized that the protein-coding gene Evl and/or its intronic miR-342 - which share a common genomic locus - may regulate hematopoiesis. Evl has been shown to play a pivotal role in actin cytoskeleton remodeling, and to interact with RAD51 complexes within homologous recombination. MiR-342 is a direct target of the transcription factor PU.1, which drives myeloid differentiation, and accelerates all-trans retinoic acid (ATRA)-induced differentiation of APL blasts.