# Interrogating the minor spliceosome to understand and treat leukemia

> **NIH NIH R01** · SLOAN-KETTERING INST CAN RESEARCH · 2024 · $626,267

## Abstract

SUMMARY
Genes encoding RNA splicing factors are the most common class of mutations in patients with myelodysplastic
syndromes (MDS) and are also common across all other forms of myeloid malignancies. These leukemia-
associated “spliceosomal mutations” primarily occur in four genes: SF3B1, SRSF2, U2AF1, and ZRSR2. In
three of these four genes (SF3B1, SRSF2, and U2AF1), the mutations occur at specific amino acid residues in
a heterozygous manner (so-called “mutational hotspots”) and cause gain/alteration of function. In contrast,
mutations in ZRSR2 occur throughout the open reading frame and appear to confer loss of function. Moreover,
ZRSR2's normal function makes it unique amongst the commonly mutated RNA splicing factors in leukemias:
ZRSR2 is the only frequently mutated factor that primarily functions in the recognition of a rare class of introns
known as “minor introns.” Thus, ZRSR2 mutations are significantly enriched in leukemia and exhibit a unique
genetic spectrum and function amongst recurrent spliceosomal mutations, yet they are comparatively poorly
studied and understood compared to mutations in SF3B1, SRSF2, and U2AF1.
 Here, we propose to determine the mechanistic, functional, and therapeutic consequences of ZRSR2
mutations in leukemia. Our interdisciplinary team consists of a physician-scientist with expertise in leukemia
biology and patient care (Abdel-Wahab) and a basic scientist with expertise in RNA splicing and functional
genomics (Bradley). As minor introns are far more conserved than are most other introns, we hypothesize that
a cross-species comparisons of the effects of ZRSR2 loss will be particularly useful for understanding how
molecular alterations in splicing drive malignant transformation. In addition, we hypothesize that aberrant
splicing induced by ZRSR2 loss will enable novel therapeutic approaches. In preliminary experiments, we
generated a Zrsr2 conditional knockout (cKO) mouse, assembled a relevant patient cohort, characterized the
transcriptomes of our Zrsr2 cKO mouse and ZRSR2-mutant MDS, and performed a functional genomic screen
to model and prioritize ZRSR2-regulated splicing events. These studies revealed that ZRSR2 mutations cause
mis-splicing of a compact set of genes, that Zrsr2 loss promotes aberrant and increased hematopoietic stem
cell self-renewal, that simultaneous ZRSR2 and TET2 collaborate to drive malignancy, and that mis-splicing of
specific downstream targets of ZRSR2 promotes clonality. We propose to build on these preliminary studies as
follows: Aim 1, Determine how ZRSR2 mutations dysregulate the transcriptome and proteome in leukemia;
Aim 2, Determine how disruption of ZRSR2-regulated splicing events drives clonal advantage; Aim 3, Identify
the functional basis for the frequent co-occurrence of ZRSR2 and TET2 mutations in leukemia. The
significance of these studies is that they will elucidate mechanistic and functional connections between
ZRSR2 mutations, RNA mis-splicing, and the initiation ...

## Key facts

- **NIH application ID:** 10876993
- **Project number:** 5R01CA251138-05
- **Recipient organization:** SLOAN-KETTERING INST CAN RESEARCH
- **Principal Investigator:** Omar Abdel-Wahab
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $626,267
- **Award type:** 5
- **Project period:** 2020-07-03 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10876993

## Citation

> US National Institutes of Health, RePORTER application 10876993, Interrogating the minor spliceosome to understand and treat leukemia (5R01CA251138-05). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10876993. Licensed CC0.

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