Biology subjects

Tsao, E.

Publications and source records attributed to Tsao, E..

4 recordsLinked to original sources

bioRxiv2025

Aberrant splicing of MBD1 reshapes the epigenome to drive convergent myeloerythroid defects in MDS

Myelodysplastic neoplasms (MDS) feature hematopoietic deficits driven in part by transcript splicing abnormalities. Thus far, such disease-driving transcripts have been identified in association with specific splicing factor mutations. However, it remains unclear whether there also exists a set of disease-wide conserved pathological transcripts, which drive MDS independently of mutational status. Here, we characterize an MDS-associated long isoform of MBD1 (MBD1-L) as the first described member of this class of transcripts. Overexpression of MBD1-L in healthy human HSPCs recapitulates archetypal defects of MDS including deficits in erythroid differentiation and reconstitution capacity. These defects arise from an isoform-specific switching of MBD1s binding behavior, refocusing its heterochromatin-promoting activity from methylated to unmethylated CpGs and enacting broad downregulation of CpG-rich promoters as well as secondary epigenetic effects mediated by its downstream target BCOR. Remarkably, we also find that directly reversing abnormal MBD1 splicing in primary human MDS using nanoparticle-encapsulated ASOs enhances erythroid differentiation. Key pointsO_LIGlobal mis-splicing of MBD1 represents a novel gain-of-function epigenetic axis driving erythropoietic and proliferative defects in MDS. C_LIO_LIASO based depletion of pathogenic MBD1 transcripts restores erythroid differentiation, advancing RNA-based therapies for MDS. C_LI

cancer biology↗

bioRxiv2025

CSDE1 promotes passenger strand cleavage of miR-486

Strand separation of the RNA duplex is a critical step in miRNA biogenesis, in which only the guide strand is retained to form the mature miRISC. The erythroid miRNA miR-486-5p uniquely requires AGO2 catalytic slicing of its passenger strand miR-486-3p, yet the factors regulating this process remain poorly understood. Here, we identify the RNA-binding protein CSDE1 as a key cofactor that promotes AGO2-dependent passenger-strand removal and miR-486-5p maturation. CSDE1 interacts with the N-terminal domain of AGO2, essential for strand release. Loss of CSDE1 increased the miR-486-3p/5p ratio, reduced cleavage efficiency, and derepressed miR-486 targets such as FOXO1 and PTEN. Restoring full-length CSDE1 expression restored AGO2-dependent passenger strand cleavage and this function requires the N-terminal cold-shock domain CSD1, which mediates CSDE1 interaction with AGO2. Together, these results demonstrate CSDE1 as a critical regulator of AGO2-mediated strand separation, potentiating miR-486-5p function in target gene silencing associated with in hematological malignancies.

molecular biology↗

bioRxiv2025

Stress Granules Underlie Acute Myeloid Leukemia Stem Cell Survival and Stress Adaptation

The link between cancer maintenance and an ability to sustain continued growth through stresses conferred by the cancer state itself is growing. However, there are significant gaps in our understanding of how this stress is managed, particularly at the level of cancer initiating cells. Here, we identify proteins comprising the dynamic, stress-adaptive ribonucleoprotein complexes known as stress granules (SG) to be enriched among the factors essential for leukemic stem cell (LSC)-driven leukemic propagation. Focusing on core SG nucleator G3BP1, we dissect the role of SGs in human acute myeloid leukemia (AML), their targetability, and the mechanisms they govern to uncover a novel propensity for AML, and in particular LSC-enriched fractions, to prime the expression of SG components, form SGs with greater fidelity and to be reliant on their establishment and continued integrity for LSC maintenance. We further unveil the transcript and protein interactome of G3BP1 in the AML context and show that consolidated control of innate immune signaling, and apoptosis repression is executed through regional binding specificity of G3BP1 to highly structured 3UTRs and cooperation with the RNA helicase UPF1 to mediate transcript decay in SGs. Altogether our findings advance novel fundamental principles of stress adaptation exploited in AML and LSCs that may extend to other cancers and uncover SGs as a novel axis for therapy development.

cancer biology↗

bioRxiv2022

A two-step in vivo CRISPR screen unveils pervasive RNA binding protein dependencies for leukemic stem cells and identifies ELAVL1 as a therapeutic target

Acute myeloid leukemia (AML) progression and relapse is fueled by self-renewing leukemic stem cells (LSCs) whose molecular determinants have been difficult to discern from normal hematopoietic stem cells (HSCs) or to uncover in screening approaches focused on general AML cell properties. We have identified a unique set of RNA binding proteins (RBPs) that are enriched in human AML LSCs but repressed in HSCs. Using an in vivo two step CRISPR-Cas9-mediated screening approach to specifically score for cancer stem cell functionality, we found 32 RBPs essential for LSC propagation and self-renewal in MLL-AF9 translocated AML. Using knockdown or small molecule approaches we show that targeting key hit RBP ELAVL1 impaired LSC-driven in vivo leukemic reconstitution and selectively depleted primitive AML cells vs. normal hematopoietic stem and progenitors. Importantly, knockdown of Elavl1 spared HSCs while significantly reducing LSC numbers across genetically diverse leukemias. Integrative RNA-seq and eCLIP-seq profiling revealed hematopoietic differentiation, RNA splicing and mitochondrial metabolism as key features defining the leukemic ELAVL1-mRNA interactome with the mitochondrial import protein TOMM34 being a direct ELAVL1-stabilized target whose inhibition impairs AML propagation. Altogether, through the use of a stem cell-adapted in vivo CRISPR dropout screening strategy, this work demonstrates that a wide variety of post-transcriptionally acting RBPs are important regulators of LSC-survival and self-renewal and, as exemplified by ELAVL1, highlights their potential as therapeutic targets in AML.

cancer biology↗