The dsRBP Staufen2 governs RNP assembly of neuronal Argonaute proteins

Here, we have characterized the role of the RNA-binding protein Staufen2, a potential Ago interactor, in RNP assembly. Staufen2 depletion resulted in the upregulation of Ago1/2 and the RISC effector proteins Ddx6 and Dcp1a. This upregulation was accompanied by the displacement of Ago2 from processing bodies, large RNPs implicated in RNA storage, and subsequent association of Ago2 with translating polysomes. Analysis of miRNA expression levels did not reveal changes of global miRNA abundance. In parallel, Staufen2 deficiency yielded decreased global translation. As the observed phenotype can be rescued by Ago1/2 knockdown, we propose a working model in which both Staufen2 and Ago proteins critically depend on each other and contribute to neuronal homeostasis. 12 samples, including 4 biological replicates, were analyzed for miRNA expression levels in cortical neurons deficient for Stau2 or Pum2, the non-targeting control samples (shNTC) served as reference and shPum2 as additional control for shRNA-induced background changes.