Mutant NPM1 marginally impacts ribosome footprint in acute myeloid leukemia cells

Background

NPM1-mutated acute myeloid leukemia (AML) is the most frequent AML subtype. As wild-type NPM1 is known to orchestrate ribosome biogenesis, it has been hypothesized that altered translation may contribute to leukemogenesis and leukemia maintenance in NPM1-mutated AML. However, this hypothesis has never been investigated. We reasoned that if mutant NPM1 (NPM1c) directly impacts translation in leukemic cells, loss of NPM1c would result in acute changes in the ribosome footprint.

Methods

Here, we performed ribosome footprint profiling (Ribo-seq) and bulk messenger RNA (mRNA) sequencing in two NPM1-mutated cell lines engineered to express endogenous NPM1c fused to the FKBP (F36V) degron tag (degron cells).

Results and discussion

Incubation of degron cells with the small compound dTAG-13 enables highly specific degradation of NPM1c within 4 hours. As expected, RNA-sequencing data showed early loss of homeobox gene expression following NPM1c degradation, confirming the reliability of our model. In contrast, Ribo-seq data showed negligible changes in the ribosome footprint in both cell lines, implying that the presence of NPM1c does not influence ribosome abundance and positioning on mRNA. While it is predictable that NPM1c exerts its leukemogenic activity at multiple levels, ribosome footprint does not seem influenced by the presence of mutant NPM1.