Abstract
Cytoplasmic polyadenylation is a widespread mechanism to regulate mRNA translation. In vertebrates, this process requires two sequence elements in target 3′ UTRs: the U-rich cytoplasmic polyadenylation element and the AAUAAA hexanucleotide. In Drosophila melanogaster, cytoplasmic polyadenylation of Toll mRNA occurs independently of these canonical elements and requires a machinery that remains to be characterized. Here we identify Dicer-2 as a component of this machinery. Dicer-2, a factor previously involved in RNA interference (RNAi), interacts with the cytoplasmic poly(A) polymerase Wispy. Depletion of Dicer-2 from polyadenylation-competent embryo extracts and analysis of wispy mutants indicate that both factors are necessary for polyadenylation and translation of Toll mRNA. We further identify r2d2 mRNA, encoding a Dicer-2 partner in RNAi, as a Dicer-2 polyadenylation target. Our results uncover a novel function of Dicer-2 in activation of mRNA translation through cytoplasmic polyadenylation.
Highlights
Dynamic regulation of the mRNA poly(A) tail length allows rapid and accurate control of gene expression in time and space
We identify r2d2 mRNA as a novel substrate regulated by Dicer-2 in vitro and in vivo, suggesting the existence of a positive loop to reinforce RNA interference (RNAi) in the Drosophila early embryo
We focused on Orb2, Wispy, and Symplekin
Summary
Dynamic regulation of the mRNA poly(A) tail length allows rapid and accurate control of gene expression in time and space. Cytoplasmic poly(A) tail elongation stimulates mRNA translation and stability in a wide variety of biological situations, including oocyte maturation, early embryonic development, neuronal plasticity, cell proliferation and senescence, cell identity, inflammation, metabolism, circadian gene expression and hibernation (Kojima et al 2012; Weill et al 2012; Ivshina et al 2014; Elewa et al 2015; Grabek et al 2015). Together with the scaffolding protein Symplekin, these factors recruit the cytoplasmic poly(A) polymerase GLD-2 to elongate the adenosine tail at the 3′ end of the mRNA (for review, see Villalba et al 2011; Weill et al 2012; Ivshina et al 2014). The poly(A) tail is recognized by poly(A)-binding protein (PABP), which contacts the cap-binding complex at the 5′ end of the mRNA to stimulate translation initiation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
