Date of Award
2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biochemistry
First Advisor
Jessica L. Heath
Abstract
The t(10;11)(p13;q14-21) chromosomal translocation fuses the Clathrin Assembly Lymphoid Myeloid (CALM) gene to the H3K79 Methyltransferase DOT1L Cofactor (AF10) gene, resulting in the abnormal expression of the CALM-AF10 oncoprotein. CALM-AF10 promotes the development of aggressive forms of both acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) and has a disproportionate effect on the pediatric population. While treatments for childhood leukemia have drastically improved in recent years, patients diagnosed with CALM-AF10 translocated leukemia experience poorer responses to chemotherapy and increased risks of relapse. There is a significant need, therefore, to identify the mechanisms by which CALM-AF10 promotes leukemogenesis. Wnt signaling plays a crucial role in the regulation of hematopoiesis, and its dysregulation is associated with the development and progression of several forms of leukemia. Recent studies in colorectal cancer cell lines have demonstrated AF10 to be a co-activator of canonical Wnt signaling that is required for the expression of Wnt target genes. β-catenin, the main effector protein of the canonical Wnt signaling pathway, has also been shown to interact with AF10. It is unknown, however, if CALM-AF10 maintains this interaction or if CALM-AF10 impacts Wnt signaling. Previous work in our lab has demonstrated that CALM-AF10 upregulates Wnt activity and increases β-catenin protein levels in a dose-dependent manner. To further examine the impact of CALM-AF10 on Wnt signaling, we used a variety of in vitro techniques in CALM-AF10 transformed murine embryonic fibroblasts (MEFs) to determine the impact of CALM-AF10 on β-catenin’s subcellular localization. We hypothesized that CALM-AF10 enhanced the nuclear localization of β-catenin to promote the transcription of Wnt target genes. We determined that CALM-AF10 maintains the ability to interact with β-catenin, that CALM-AF10 enhances the localization of β-catenin at both the plasma membrane and nucleus, and that the expression of CALM-AF10 promotes the transcription of Wnt target genes. These findings suggest that CALM-AF10 utilizes Wnt/β-catenin signaling to promote leukemogenesis, and that β-catenin may be a novel therapeutic target for the treatment of CALM-AF10 translocated leukemia.
Language
en
Number of Pages
57 p.
Recommended Citation
Cullen, John Matthew, "The Impact Of The Calm-Af10 Fusion Protein On Wnt Signaling In Leukemia" (2024). Graduate College Dissertations and Theses. 1830.
https://scholarworks.uvm.edu/graddis/1830