부산대학교 도서관

Splicing defects are a characteristic feature of myelodysplastic syndromes (MDS) and typically associate with specific recurrent splicing factor mutations. However, a subset of transcripts exhibit abnormal splicing regardless of mutational background, occurring even in the absence of splicing-related mutations. These shared splicing events likely include common underlying drivers of MDS hematopoietic defects, yet the functions of the resulting transcripts remain unknown. We identified a long isoform of Methyl-CpG-Binding Domain 1 ( MBD1) as the product of one such mutation-independent splicing event. To understand whether altered MBD1splicing contributes to hematopoietic dysfunction, we overexpressed isoforms of MBD1in cord blood CD34+ cells and found that the MDS-associated full-length isoform (MBD1-L), containing MBD1's 3rd CXXC domain, impaired erythroid differentiation by stalling cell cycling and promoting apoptosis. In contrast, the MBD1-ΔCXXC3 isoform (MBD1-S), preferentially produced in healthy cells, did not induce these defects. Recapitulating these findings, the MBD1-L isoform uniquely impaired reconstitution capacity in vivo, particularly in the erythroid and myeloid lineages, and in addition produced an enrichment of the MDS transcriptomic signature on RNA-seq profiling.