4E-T-bound mRNAs are stored in a silenced and deadenylated form

Abstract

Human 4E-T is an eIF4E-binding protein (4E-BP) present in processing (P)-bodies that represses translation and regulates decay of mRNAs destabilized by AU-rich elements and microRNAs (miRNAs). However, the underlying regulatory mechanisms are still unclear. Here, we show that upon mRNA binding 4E-T represses translation and promotes deadenylation via the recruitment of the CCR4-NOT deadenylase complex. The interaction with CCR4-NOT is mediated by previously uncharacterized sites in the middle region of 4E-T. Importantly, mRNA decapping and decay are inhibited by 4E-T and the deadenylated target is stored in a repressed form. Inhibition of mRNA decapping requires the interaction of 4E-T with the cap-binding proteins eIF4E/4EHP. We further show that regulation of decapping by 4E-T participates in mRNA repression by the miRNA effector protein TNRC6B and that 4E-T overexpression interferes with tristetraprolin (TTP)-and NOT1-mediated mRNA decay. Thus, we postulate that 4E-T modulates 5 ′-to-3 ′ decay by swapping the fate of a deadenylated mRNA from complete degradation to storage. Our results provide insight into the mechanism of mRNA storage that controls localized translation and mRNA stability in P-bodies.

Gene-level analysis of rare variants in 363,977 whole exome sequences identifies an association of GIGYF1 loss of function with type 2 diabetes

“…We uncovered novel associations with T2D and biomarkers of glycemic control for aggregated variants in GIGYF1, TNRC6B and PFAS. TNRC6B encodes trinucleotide repeat-containing gene 6B protein which is involved siRNA- and miRNA-mediated gene silencing [26-28]. As TNRC6B is highly constrained, one must view pLOF variants in this gene with suspicion as they may be sequencing errors or not result in a true loss of function.…”

Human Pumilio proteins directly bind the CCR4-NOT deadenylase complex to regulate the transcriptome

“…MALAT1 or Histone Stem Loop (Van Etten et al 2012)) suggests that there exists an additional facet to the repression mechanism. The fact that recruitment of the CNOT complex can elicit both deadenylation and deadenylation-independent translational repression is likely relevant (Cooke, Prigge, and Wickens 2010; Ozgur et al 2015; Waghray et al 2015; Kamenska et al 2016; Räsch et al 2020). Moreover, our data indicate that decapping contributes to repression by PUM1&2.…”

Cytoplasmic mRNPs revisited: Singletons and condensates

“…[ 76 ] Moreover, they are also closely associated with the CCR4‐NOT deadenylase and decapping complexes, [ 77,78 ] and 4E‐T protects the deadenylated target mRNAs from degradation via inhibition of decapping within the condensate. [ 79,80 ] This reservoir function is supported by recent data revealing that cytoplasmic mRNA decay pathways are widely linked to the translational apparatus in both yeast [ 81,82 ] and mammalian embryonic stem cells. [ 83 ]…”