Graduation Date

Fall 8-15-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Biochemistry & Molecular Biology

First Advisor

Ricia Katherine Hyde

Abstract

Acute myeloid leukemia (AML) is a neoplastic disease characterized by the uncontrolled proliferation and accumulation of immature and non-functional myeloid blast cells. One of the most frequently mutated transcription factors implicated in the pathogenesis of AML is Runt-related Transcription Factor 1 (RUNX1). RUNX1 is essential for definitive hematopoiesis and is a key hematopoietic regulator with well-known roles in leukemia. Previous work from our lab demonstrated that Histone Deacetylase 1 (HDAC1), a known RUNX1 partner, is unexpectedly required for active transcription of RUNX1 target genes in Acute Myeloid Leukemia (AML). This implies a non-histone role for HDAC1 in regulating components of the RUNX1 complex.

To decipher the role of HDAC1 in recruiting proteins to the RUNX1 complex, we immunoprecipitated RUNX1 in the presence of a HDAC1 inhibitor, entinostat, and performed mass spectrometry. We discovered that Polypyrimidine Tract Binding Protein 1 (PTBP1), a splicing regulator, interacts with RUNX1 in an HDAC1-dependent manner, where the interaction is significantly reduced in the presence of entinostat. This association was observed in a variety of leukemia subtypes as well as healthy hematopoietic stem cells. Chromatin profiling revealed extensive genome-wide overlap in sites occupied by RUNX1 and PTBP1, with significant enrichment at promoters of actively transcribed genes, specifically those involved in metabolism. Loss of PTBP1 in AML cells led to widespread alterations in RNA splicing and decreased expression of genes whose 3 promoters are bound by both factors, including metabolic genes. In agreement with these findings, we found that loss of PTBP1 reduced glycolytic output and glucose uptake, increased DNA damage, and ultimately caused leukemia cell death. Moreover, we showed that loss of PTBP1 sensitized leukemia cells to the chemotherapeutic agent, cytarabine. Finally, using entinostat to disrupt this interaction, we observed downregulation of metabolic proteins. Based on our data, we propose that the interaction between RUNX1 and PTBP1 facilitates expression of metabolic proteins essential for leukemia cell growth and survival.

Comments

2025 Copyright, the authors

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Available for download on Friday, July 23, 2027

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