Year-end Sale % OFF 
Abstract
Cytoplasmic poly(A)-binding proteins (PABPs) link mRNA 3′ termini to translation initiation factors, but they also play key roles in mRNA regulation and decay. Reports from mice, zebrafish and Drosophila further involved PABPs in microRNA (miRNA)-mediated silencing, but through seemingly distinct mechanisms. Here, we implicate the two Caenorhabditis elegans PABPs (PAB-1 and PAB-2) in miRNA-mediated silencing, and elucidate their mechanisms of action using concerted genetics, protein interaction analyses, and cell-free assays. We find that C. elegans PABPs are required for miRNA-mediated silencing in embryonic and larval developmental stages, where they act through a multi-faceted mechanism. Depletion of PAB-1 and PAB-2 results in loss of both poly(A)-dependent and -independent translational silencing. PABPs accelerate miRNA-mediated deadenylation, but this contribution can be modulated by 3′UTR sequences. While greater distances with the poly(A) tail exacerbate dependency on PABP for deadenylation, more potent miRNA-binding sites partially suppress this effect. Our results refine the roles of PABPs in miRNA-mediated silencing and support a model wherein they enable miRNA-binding sites by looping the 3′UTR poly(A) tail to the bound miRISC and deadenylase.
Highlights
MicroRNAs are 18- to 25-nucleotide-long RNAs that regulate gene expression and impact on a wide variety of biological functions ranging from development to disease [1]
We previously conducted a comparative proteomic analysis of miRNA-induced silencing complex (miRISC) captures using pull-down of 2 -O-methylated (2 -O-Me) oligonucleotide mimics of single target sites for maternal and zygotic miRNA families highly enriched in the embryo [9,28,29]
We performed miRISC capture using a mimic of a pair of miRNA-binding sites for the bantam and miR-3542 miRNAs, in a configuration that is highly active in deadenylation assays (Flamand et al, in preparation)
Summary
MicroRNAs (miRNAs) are 18- to 25-nucleotide-long RNAs that regulate gene expression and impact on a wide variety of biological functions ranging from development to disease [1]. The gene-silencing functions of miRNAs are orchestrated through interactions and activities of the miRNA-induced silencing complex (miRISC) and its associated co-factors. MiRISC functional architecture revolves around the core Argonaute and GW182 proteins. The GW182 proteins encode an Argonaute-binding domain characterized by GW/WG repeats [10], and a silencing domain (SD) which interacts with CNOT1, a scaffold protein of the multi-subunit CCR4/NOT1 deadenylase complex [8,11,12,13]. AIN-1 and AIN-2 interact with the Argonaute proteins ALG-1 and ALG-2 and are thought to be essential for miRNA-mediated silencing [14]. Recent data indicate that cross-species interactions are possible between Argonautes, GW182 proteins and CCR4/NOT1, when reconstituted in heterologous systems [15,16]
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
