Biology subjects

Lundin, V.

Publications and source records attributed to Lundin, V..

3 recordsLinked to original sources

bioRxiv2025

RNA Editors Sculpt the Transcriptome During Terminal Erythropoiesis

Selective RNA degradation during terminal erythropoiesis results in a globin-rich transcriptome in mature erythrocytes, but the specific RNA decay pathways remain unknown. We found that deficiency of the terminal uridylyl transferase enzyme Zcchc6 and the 3-5 exoribonuclease Dis3l2 in mouse models led to fetal and perinatal reticulocytosis, an accumulation of RNA-rich precursors of terminal erythroid cells, suggesting their crucial roles in terminal red cell differentiation. Notably, knockout embryos exhibited persistent high-level expression of Hbb-bh1 globin, the ortholog of human fetal{gamma} -globin. Perturbation of the Zcchc6-Dis3l2 pathway in mice engineered to express the human {beta}-globin locus likewise increased{gamma} -globin levels in fetal erythroid cells, suggesting that globin switching entails post-transcriptional mechanisms of mRNA destabilization in addition to transcriptional down-regulation. We cultured human hematopoietic stem and progenitor cells (HSPCs), performed CRISPR/Cas9-mediated knockout of ZCCHC6 and DIS3L2, and observed accumulation of RNA and elevated {gamma}-globin levels in terminal erythroid cells. Our findings reveal a conserved role for the ZCCHC6/DIS3L2 RNA editors in terminal erythropoiesis and demonstrate a post-transcriptional mechanism for{gamma} -globin gene switching, advancing research into in vitro erythrocyte generation and{gamma} -globin stabilization to ameliorate hemoglobinopathies.

developmental biology↗

bioRxiv2024

SF3B1-mutant mis-splicing of UBA1 confers a targetable therapeutic vulnerability through UBA1 inhibition

SF3B1 mutation-driven myelodysplastic syndromes (MDS-SF3B1) arise due to somatic mutation in the splicing factor SF3B1 gene. SF3B1 mutations induce RNA mis-splicing and loss of expression of critical genes for erythropoiesis, leading to erythroid dysplasia and ultimately refractory anemia. The development of precision medicine approaches for MDS- SF3B1 is hampered by the complexity of the mis-splicing landscape and its evaluation in disease-accurate model systems. To identify novel RNA mis-splicing events, isogenic SF3B1K700E and SF3B1WT iPSC lines from an MDS-SF3B1 patient were differentiated into hematopoietic cells in vitro and subjected to unsupervised splicing event analysis using full-length RNA sequencing data. This revealed SF3B1K700E-specific mis-splicing of ubiquitin-like modifier activating enzyme 1 (UBA1) transcripts, which encode the essential E1 protein at the apex of the ubiquitination cascade. UBA1 mis-splicing (UBA1ms) preserved UBA1ms mRNA but not protein expression. Consequently, UBA1ms diminished the pool of functional UBA1, sensitizing SF3B1K700E cell lines to the small-molecule UBA1 inhibitor TAK-243. Finally, analysis of CD34+ RNA sequencing data from an MDS patient cohort confirmed unique and ubiquitous UBA1ms in MDS-SF3B1 patients, without detection in other splicing factor-mutated MDS patients, or in healthy individuals. TAK-243 selectively targeted MDS-SF3B1 primary CD34+ cells and reduced mutant cell number in colony-forming unit studies. In contrast, normal hematopoietic progenitor cells were unaffected. Altogether, we here define UBA1ms as a novel therapeutic vulnerability in SF3B1-mutant cells, introducing UBA1 inhibition as a potential avenue for future MDS-SF3B1 treatments.

cancer biology↗

bioRxiv2023

Erythroid differentiation intensifies RNA mis-splicing in SF3B1-mutant myelodysplastic syndromes with ring sideroblasts

Myelodysplastic syndromes with ring sideroblasts (MDS-RS) commonly originate from mutations in the splicing factor SF3B1 (SF3B1mt). SF3B1mt cause RNA mis-splicing, mechanistically established as the major driver of RS development. However, little is known about RS fate and biology after their initial formation in the human bone marrow. We here achieve isolation of viable RS from patient samples, enabling the first complete investigation of SF3B1mt development from stem cell to RS. We show that RS skew MACS-isolated CD34+ data towards erythroid features not recapitulated in single-cell RNAseq. We demonstrate that RS divide, differentiate, enucleate and actively respond to mis-splicing/oxidative stress, decreasing wildtype stem cell fitness via GDF15 overproduction. We identify circulating RS as a uniform clinical feature associated with disease burden. Finally, we establish that SF3B1mt mis-splicing intensifies during erythroid differentiation and demonstrate through combined transcriptomics/proteomics an uncoupling of RNA/protein biology in RS encompassing severe and dysfunctional mis-splicing of proapoptotic genes. Statement of significanceWe here combine a novel method for RS isolation with state-of-the-art multiomics to perform the first complete investigation of SF3B1mt MDS-RS hematopoiesis from stem cell to RS. We identify the survival mechanisms underlying SF3B1mt erythropoiesis and establish an active role for erythroid differentiation and RS themselves in SF3B1mt MDS-RS pathogenesis.

cancer biology↗