Ribosome biogenesis is a downstream effector of the oncogenic U2AF1-S34F mutation

Area of Science:

• Molecular Biology
• Cancer Biology
• Hematology

Background:

• U2 Small Nuclear RNA Auxiliary Factor 1 (U2AF1) forms a complex with U2AF2, essential for 3' splice site selection.
• U2AF1 mutations are common in cancers, especially Myelodysplastic Syndrome (MDS) and Acute Myeloid Leukemia (AML), with S34F being the most frequent.
• The U2AF heterodimer also plays a role in regulating mRNA translation.

Purpose of the Study:

• To investigate the functional consequences of the U2AF1-S34F mutation on translation and ribosome biogenesis.
• To identify specific molecular targets and pathways affected by the U2AF1-S34F mutation.
• To explore the relationship between U2AF1, NPM1, and ribosome biogenesis in myeloid malignancies.

Main Methods:

• Analysis of translation initiation and ribosome biogenesis machinery.
• Single-cell mRNA translation assays.
• Depletion studies of NPM1 in U2AF1-S34F mutant cells.
• Assessment of ribosomal RNA (rRNA) processing.

Main Results:

• The U2AF1-S34F mutation leads to misregulation of translation initiation and ribosome biogenesis.
• A significant increase in mRNA translation was observed at the single-cell level in cells with the U2AF1-S34F mutation.
• Nucleophosmin 1 (NPM1), a key driver of myeloid malignancy, was identified as a translationally upregulated target.
• NPM1 depletion in U2AF1-S34F mutant cells impaired cell viability and caused rRNA processing defects.

Conclusions:

• The U2AF1-S34F mutation establishes a unique molecular phenotype characterized by translational misregulation.
• This mutation impacts both translation and ribosome biogenesis, with implications for myeloid disease pathogenesis.
• An unexpected synthetic interaction exists between U2AF1, NPM1, and ribosome biogenesis in the context of myeloid malignancies.