Differential translation of mRNA isoforms underlies oncogenic activation of cell cycle kinase Aurora A

Abstract

Aurora Kinase A (AURKA) is an oncogenic kinase with major roles in mitosis, but also exerts cell cycle- and kinase-independent functions linked to cancer. Therefore, control of its expression, as well as its activity, is crucial. A short and a long 3′UTR isoform exist for AURKA mRNA, resulting from alternative polyadenylation (APA). We initially observed that in triple-negative breast cancer, where AURKA is typically overexpressed, the short isoform is predominant and this correlates with faster relapse times of patients. The short isoform is characterized by higher translational efficiency since translation and decay rate of the long isoform are targeted by hsa-let-7a tumor-suppressor miRNA. Additionally, hsa-let-7a regulates the cell cycle periodicity of translation of the long isoform, whereas the short isoform is translated highly and constantly throughout interphase. Finally, disrupted production of the long isoform led to an increase in proliferation and migration rates of cells. In summary, we uncovered a new mechanism dependent on the cooperation between APA and miRNA targeting likely to be a route of oncogenic activation of human AURKA.

Immunoprecipitation of Reporter Nascent Chains from Active Ribosomes to Study Translation Efficiency

“…For each experiment, three technical replicates and three repeats of the experiment should be performed. Appropriate controls for the experiment should be used, like using an untagged reporter protein (see Cacioppo et al, 2023) or untransfected cells. • Perform procedures under a laminar flow hood.…”

“…Also, the requirement for sophisticated imaging platforms and complex data analysis are some other limitations of these recent methods. Here, we describe a simple yet effective alternative method that we recently introduced to assess TE of mRNAs of interest as dictated by UTRs (Cacioppo et al, 2023). Our assay is based on IP of Flag-tagged nascent chains, ensuring exclusion of non-translating mRNAs, which has already been proved an efficient approach (Raue et al, 2007;Aviner et al, 2013;Zhang et al, 2013).…”