Abstract
MicroRNAs (miRNAs) exert a broad influence over gene expression by directing effector activities that impinge on translation and stability of mRNAs. We recently discovered that the cap-binding protein 4EHP is a key component of the mammalian miRNA-Induced Silencing Complex (miRISC), which mediates gene silencing. However, little is known about the mRNA repertoire that is controlled by the 4EHP/miRNA mechanism or its biological importance. Here, using ribosome profiling, we identify a subset of mRNAs that are translationally controlled by 4EHP. We show that the Dusp6 mRNA, which encodes an ERK1/2 phosphatase, is translationally repressed by 4EHP and a specific miRNA, miR-145. This promotes ERK1/2 phosphorylation, resulting in augmented cell growth and reduced apoptosis. Our findings thus empirically define the integral role of translational repression in miRNA-induced gene silencing and reveal a critical function for this process in the control of the ERK signaling cascade in mammalian cells.
Highlights
MRNA translation commences with the binding of the eukaryotic initiation factor 4F to the mRNA 5 ́ cap structure. eIF4F is a three-subunit complex composed of eIF4E, the m7GpppNinteracting factor; eIF4G, a scaffolding protein, and eIF4A, a DEAD-box RNA helicase (Sonenberg and Hinnebusch, 2009). eIF4G interacts with eIF3, through which it recruits the pre-initiation complex, comprised of the 40S ribosomal subunit and associated factors, to the mRNA
We discovered that Dusp6 mRNA translation is repressed by a 4EHP/miRNA-dependent mechanism, which impacts on ERK1/2 phosphorylation, cell proliferation, and apoptosis
To identify mRNAs that are translationally controlled by 4EHP, we carried out ribosome profiling (Ingolia et al, 2011) in wild-type (WT) and 4EHP knockout (4EHP-KO) mouse embryonic fibroblasts (MEFs) (Figure 1—figure Supplement 1A and B)
Summary
MRNA translation commences with the binding of the eukaryotic initiation factor 4F (eIF4F) to the mRNA 5 ́ cap structure. eIF4F is a three-subunit complex composed of eIF4E, the m7GpppN (cap)interacting factor; eIF4G, a scaffolding protein, and eIF4A, a DEAD-box RNA helicase (Sonenberg and Hinnebusch, 2009). eIF4G interacts with eIF3, through which it recruits the pre-initiation complex, comprised of the 40S ribosomal subunit and associated factors, to the mRNA. EIF4G interacts with eIF3, through which it recruits the pre-initiation complex, comprised of the 40S ribosomal subunit and associated factors, to the mRNA. Binding of the mRNA 5 ́ cap by the 4E Homologous Protein (4EHP, encoded by Eif4e2), in contrast to eIF4E, impairs translation initiation CCR4–NOT in turn recruits DDX6, 4E-T (eIF4E-Transporter; a conserved 4EHP/ eIF4E-binding protein) and 4EHP to suppress cap-dependent mRNA translation (Chapat et al, 2017; Jonas and Izaurralde, 2015; Kamenska et al, 2014; Kamenska et al, 2016; Ozgur et al, 2015). Which cellular mRNAs are targeted by 4EHP remains unknown
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 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.
