mRNA with a <20-nt poly(A) tail imparted by the poly(A)-limiting element is translated as efficiently in vivo as long poly(A) mRNA

Abstract

The poly(A)-limiting element (PLE) is a conserved sequence that restricts the length of the poly(A) tail to <20 nt. This study compared the translation of PLE-containing short poly(A) mRNA expressed in cells with translation in vitro of mRNAs with varying length poly(A) tails. In transfected cells, PLE-containing mRNA had a <20-nt poly(A) and accumulated to a level 20% higher than a matching control without a PLE. It was translated as well as the matching control mRNA with long poly(A) and showed equivalent binding to polysomes. Translation in a HeLa cell cytoplasmic extract was used to examine the impact of the PLE in the context of varying length poly(A) tails. Here the overall translation of +PLE mRNA was less than control mRNA with the same length poly(A), and the PLE did not overcome the effect of a short poly(A) tail. Because poly(A)-binding protein (PABP) is a dominant effector of poly(A)-dependent translation we reasoned excess PABP in our extract might overwhelm PLE regulation of translation. This was confirmed by experiments where PABP was inactivated with poly(rA) or Paip2, and the effect of both treatments was reversed by addition of recombinant PABP. These data indicate that the PLE functionally substitutes for bound PABP to stimulate translation of short poly(A) mRNA.

Separate cis-trans Pathways Post-transcriptionally Regulate Murine CD154 (CD40 Ligand) Expression

“…If this is eventually confirmed, then consideration of a separate pathway for efficient nuclear export must be considered, since the 3Ј-UTR CARE did not affect cytoplasmic mRNA levels. This activity parallels that reported for the poly(A)-limiting element, which reduced poly(A) tail length in the nucleus without affecting nuclear export or polysomal loading (38,39). The observation that the 3Ј-UTR CARE limits translation without altering polysomal loading is similar to that seen with other systems (33,34).…”

Target specificity among canonical nuclear poly(A) polymerases in plants modulates organ growth and pathogen response

“…However, the polyadenylation defect of SAUR mRNAs in paps1 mutants does not seem to destabilize the mRNAs, as indicated by the qRT-PCR experiments on random hexamer-primed cDNA (Fig. 3B), as reported for several previous examples of stable mRNAs with very short poly(A) tails (32)(33)(34). Consistent with this, introducing the dst2 mutant (35) into the paps1-1 background to alleviate the inherent instability of SAUR mRNAs did not rescue the paps1-1 phenotype (Fig.…”

Cytoplasmic Poly(A) Binding Protein C4 Serves a Critical Role in Erythroid Differentiation

“…Current explorations of miRNA content in the erythroid lineage can now be utilized to explore this model (54). It is worth noting that prior studies have identified sets of mRNAs that remain stable and efficiently translated despite having short (Ͻ20-nt) poly(A) tails under limiting PABP levels (55,56). Of note, these mRNAs contain AU-rich poly(A)-limiting elements (PLE) within their 3= UTRs.…”