Shared Stabilization Functions of Pyrimidine-Rich Determinants in the Erythroid 15-lipoxygenase and α-globin mRNAs

Abstract

The poly(C)-binding proteins, ␣CPs, comprise a set of highly conserved KH-domain factors that participate in mRNA stabilization and translational controls in developmental and viral systems. Two prominent models of ␣CP function link these controls to late stages of erythroid differentiation: translational silencing of 15-lipoxygenase (Lox) mRNA and stabilization of ␣-globin mRNA. These two controls are mediated via association of ␣CPs with structurally related C-rich 3-untranslated region elements: the differentiation control elements (DICE) in Lox mRNA and the pyrimidine-rich motifs in ␣-globin mRNA. In the present report a set of mRNA translation and stability assays are used to determine how these two ␣CP-containing complexes, related in structure and position, mediate distinct posttranscriptional controls. While the previously reported translational silencing by the DICE is not evident in our studies, we find that the two determinants mediate similar levels of mRNA stabilization in erythroid cells. In both cases this stabilization is sensitive to interference by a nuclear-restricted ␣CP decoy but not by the same decoy restricted to the cytoplasm. These data support a general role for ␣CPs in stabilizing a subset of erythroid mRNAs. The findings also suggest that initial binding of ␣CP to target mRNAs occurs in the nucleus. Assembly of stabilizing mRNP complexes in the nucleus prior to export may maximize their impact on cytoplasmic events.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) in cellular processes: Focus on hnRNP E1's multifunctional regulatory roles

“…No modification of hnRNP E1 has been reported that attenuates its binding to the DICE. Of note, there has been one contrasting report in which translational silencing of DICE-containing reporter constructs was not observed in HeLa cells (Kong et al 2006), even though the cellular context was not well defined in the reported studies.…”

The Poly(C) Binding Protein Pcbp2 and Its Retrotransposed Derivative Pcbp1 Are Independently Essential to Mouse Development

“…Pcbp2 has been mechanistically linked to both nuclear and cytoplasmic posttranscriptional controls over globin gene expression (20,36,63). The in vivo role of Pcbp2 in hematopoiesis was facilitated by the fact that Pcbp2-null embryos remain uniformly viable at 12.5 dpc, a developmental time point where hematopoiesis is well established in the fetal liver.…”

RNA-binding protein PCBP2 modulates glioma growth by regulating FHL3

“…Real-time PCR confirmed the enrichment of the 9 RNA species in the BAP-PCBP2-associated population compared with the BAP-GFP control ( Figure 4C). In many cases, PCBP2 functions through binding to the 3′ untranslated region (UTR) or 5′ UTR of its target mRNAs (6,32). Defined PCBP2 binding sites contain short patches of C-or CU-rich sequences (25,33).…”