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c-Jun ARE targets mRNA deadenylation by an EDEN-BP (embryo deadenylation element-binding protein)-dependent pathway
Luc Paillard1, Vincent Legagneux, Dominique Maniey
1CNRS UMR 6061, Université de Rennes 1, Faculté de Médecine, 2 Avenue Léon Bernard, 35043 Rennes Cedex, France. Luc.Paillard@univ-rennes1.fr
Abstract:
In mammalian cells, certain mRNAs encoding cytokines or proto-oncogenes are especially unstable, because of the presence of a particular sequence element in their 3'-untranslated region named ARE (A/U-rich element). AREs cause this instability by provoking the rapid shortening of the poly(A) tail of the mRNA. The deadenylation of mRNAs mediated by AREs containing repeats of the AUUUA motif (class I/II AREs) is conserved in Xenopus embryos. Here, we first extend these observations by showing that c-Jun ARE, a representative of class III (non-AUUUA) AREs, also provokes the deadenylation of a reporter RNA in Xenopus embryos. Next, by immunodepletion and immunoneutralization experiments, we show that, in Xenopus, the rapid deadenylation of RNAs that contain the c-Jun ARE, but not an AUUUA ARE, requires EDEN-BP. This RNA-binding protein was previously shown to provoke the rapid deadenylation of certain Xenopus maternal RNAs. Finally, we show that CUG-BP, the human homologue of EDEN-BP, specifically binds to c-Jun ARE. Together, these results identify CUG-BP as a plausible deadenylation factor responsible for the post-transcriptional control of c-Jun proto-oncogene mRNA in mammalian cells.
Insights
A-U-rich elements (AREs) destabilize mRNA in mammalian cells by shortening the poly(A) tail. In Xenopus embryos, EDEN-BP protein mediates deadenylation of c-Jun ARE, identifying human CUG-BP as a key factor in mRNA decay.
Area of Science:
- Molecular Biology
- Gene Regulation
- RNA Metabolism
Background:
- Specific messenger RNAs (mRNAs) encoding cytokines and proto-oncogenes are highly unstable in mammalian cells.
- This instability is attributed to A/U-rich elements (AREs) in the 3'-untranslated region, which accelerate poly(A) tail shortening (deadenylation).
- AREs containing AUUUA motifs (class I/II) mediate deadenylation conserved in Xenopus embryos.
Purpose of the Study:
- To investigate if non-AUUUA AREs, like the c-Jun ARE (class III), also induce mRNA deadenylation in Xenopus embryos.
- To identify the protein factors involved in c-Jun ARE-mediated deadenylation in Xenopus.
- To determine if the identified Xenopus protein has a mammalian homologue involved in regulating c-Jun mRNA stability.
Main Methods:
- Reporter RNA assays in Xenopus embryos to assess deadenylation.
- Immunodepletion and immunoneutralization experiments to identify protein factors.
- RNA-binding assays to confirm interactions between proteins and ARE sequences.
Main Results:
- The c-Jun ARE, a class III ARE, induced reporter RNA deadenylation in Xenopus embryos.
- EDEN-BP was found to be essential for c-Jun ARE-mediated deadenylation, but not for AUUUA ARE-mediated deadenylation.
- The human homologue of EDEN-BP, CUG-BP, specifically binds to the c-Jun ARE.
Conclusions:
- Class III AREs, exemplified by the c-Jun ARE, also trigger mRNA deadenylation in Xenopus.
- EDEN-BP is a crucial deadenylation factor for c-Jun AREs in Xenopus.
- CUG-BP is identified as a likely protein responsible for the post-transcriptional control of c-Jun proto-oncogene mRNA stability in mammalian cells.