The functional role of snoRNAs in NPM1 wildtype and mutant AML

• Applicant: Fengbiao Zhou, Ph.D.
• Subject Area: Hematology, Oncology ; Biochemistry ; Cell Biology
• Term: from 2019 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413674146

NPM1 mutations rank among the most frequent mutations in acute myeloid leukemia (AML). NPM1 is a multifunctional nucleolar chaperone involved in ribosome biogenesis and genomic stability. Mutations in NPM1 generate a novel nuclear export signal in the C-terminal domain and lead to aberrant cytoplasmic dislocation of mutated NPM1 (NPM1c). Based on its pleiotropic functions, several mechanisms have been proposed for the contribution of NPM1 gene alterations to leukemogenesis. However, the pathology of NPM1-mutated AML remains incompletely understood.Small non-coding RNAs (ncRNAs) including microRNA (miRNA) have been shown to impact onto various physiological and cellular processes. We previously identified C/D box small nucleolar RNAs (snoRNA) as crucial regulators of leukemia stem cell activity and essential mediator of AML1-ETO induced leukemogenesis. To evaluate a potential role of C/D box snoRNAs in other forms of AML, we profiled snoRNA expression by high throughput small RNA-Seq in two independent cohorts of patients. Our preliminary data shows that in both sets C/D box snoRNAs are highly expressed in NPM1 wildtype AML whereas expression are much lower in AML specimens with NPM1 mutations. Of note, our mass spectrometry data demonstrates a direct protein-protein interaction between wildtype NPM1 and the snoRNA expression regulators DDX21 and AES. Thus, our preliminary findings provide evidence for a regulatory role of NPM1 in snoRNA expression. To further explore the functional role of snoRNAs in NPM1 wildtype and mutant AML, we propose to 1) define the mechanistic role of NPM1 for snoRNA regulation and to identify the protein and RNA interactome of wildtype and mutant NPM1; 2) investigate the functional consequences of snoRNA deregulation on ribosome biogenesis and function in AML cells harboring NPM1 mutation versus wildtype; 3) evaluate the potential role of snoRNA downregulation in the favorable response of NPM1c AML to chemotherapy and the utility of snoRNA suppression in sensitizing AML to chemotherapy. Together these data will improve our understanding of pathology of NPM1-mutated AML, and further uncover the essential role of C/D box snoRNA pathway in aberrant hematopoiesis.

• DFG Programme: Research Grants