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DNA Replication Stress Due to Loss of R-Loops in Myelodysplastic Syndromes with SF3B1 Mutation

ABSTRACT: Myelodysplastic syndromes (MDS) with mutated SF3B1 gene have many features including a favorable outcome that are distinct from MDS with mutations in other splicing factor genes SRSF2 or U2AF1. Molecular bases of these divergences are poorly understood. Here we show that SF3B1-mutated MDS are characterized by a dramatically reduced R-loop formation predominating in gene bodies, which tightly associates with reduced retention of introns specifically found in SF3B1-mutated, but not in U2AF1- or SRSF2-mutated MDS. Compared to erythroblasts from SRSF2- or U2AF1-mutated patients, SF3B1-mutated erythroblasts exhibited augmented DNA synthesis, accelerated replication forks, and single-stranded DNA exposure upon differentiation, which were recapitulated in murine Sf3b1K700E/+ proerythroblasts. Importantly, R-loop formation was restored by histone deacetylase inhibition using SAHA/vorinostat, which improved Sf3b1K700E/+ erythroblast differentiation. In conclusion, loss of R-loops with associated DNA replication stress is a hallmark of SF3B1- mutated MDS ineffective erythropoiesis, which could be used as a new therapeutic target.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Blood Cell, Cell Culture

SUBMITTER: Marjorie Leduc

LAB HEAD: Michaela Fontenay

PROVIDER: PXD038700 | Pride | 2024-04-08

REPOSITORIES: Pride

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