The U2AF1S34F mutation induces lineage-specific splicing alterations in myelodysplastic syndromes.

Bon Ham Yip,Amit Verma,Andrea Pellagatti,Richard N Armstrong,Paresh Vyas,Emmanouela Repapi,Luca Malcovati,Mario Cazzola,Hamid Dolatshad,Seishi Ogawa,Violetta Steeples,Miriam Llorian,Christopher W.J Smith,Jacqueline Shaw,Matthias Bartenstein,Stephen Taylor,Jacqueline Boultwood,Nicholas C P Cross ,Eva Hellström‐Lindberg ,S Roy

doi:10.1172/jci91363

Abstract

Mutations of the splicing factor–encoding gene U2AF1 are frequent in the myelodysplastic syndromes (MDS), a myeloid malignancy, and other cancers. Patients with MDS suffer from peripheral blood cytopenias, including anemia, and an increasing percentage of bone marrow myeloblasts. We studied the impact of the common U2AF1S34F mutation on cellular function and mRNA splicing in the main cell lineages affected in MDS. We demonstrated that U2AF1S34F expression in human hematopoietic progenitors impairs erythroid differentiation and skews granulomonocytic differentiation toward granulocytes. RNA sequencing of erythroid and granulomonocytic colonies revealed that U2AF1S34F induced a higher number of cassette exon splicing events in granulomonocytic cells than in erythroid cells. U2AF1S34F altered mRNA splicing of many transcripts that were expressed in both cell types in a lineage-specific manner. In hematopoietic progenitors, the introduction of isoform changes identified in the U2AF1S34F target genes H2AFY, encoding an H2A histone variant, and STRAP, encoding serine/threonine kinase receptor–associated protein, recapitulated phenotypes associated with U2AF1S34F expression in erythroid and granulomonocytic cells, suggesting a causal link. Furthermore, we showed that isoform modulation of H2AFY and STRAP rescues the erythroid differentiation defect in U2AF1S34F MDS cells, suggesting that splicing modulators could be used therapeutically. These data have critical implications for understanding MDS phenotypic heterogeneity and support the development of therapies targeting splicing abnormalities.

Highlights

The myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell malignancies characterized by ineffective hematopoiesis resulting in peripheral blood cytopenias of the myeloid lineage, including anemia and neutropenia
The gene expression levels of U2AF1S34F and U2AF1 WT (U2AF1WT) compared with levels in the empty vector (EV) control were confirmed by real-time quantitative PCR in transduced cells harvested on day 11 (Supplemental Figure 1B)
These in vitro results show that the presence of the U2AF1 mutation impairs human erythropoiesis and indicate that this mutation may play an important role in the development of anemia in MDS

Summary

Introduction

The myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell malignancies characterized by ineffective hematopoiesis resulting in peripheral blood cytopenias of the myeloid lineage, including anemia and neutropenia. Patients with MDS show increasing bone marrow myeloid blasts as the disease progresses, and approximately 40% of these patients develop acute myeloid leukemia (AML). MDS is as common as de novo AML, with an incidence of 4 per 100,000 per year [1,2,3,4]. Patients with the more advanced MDS subtypes (refractory anemia with excess blasts 1 and 2) have a median overall survival of less than 2 years, highlighting the severity of these diseases To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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