CUG-BP1/CELF1 requires UGU-rich sequences for high-affinity binding.

Julien Marquis (1) , Luc Paillard (2) , Yann Audic (2) , Bertrand Cosson (2) , Olivier Danos (1) , Christine Le Bec (1) , Howard Beverley Osborne (2)

1 CRATG - Centre de recherche et d'applications sur les thérapies géniques
2 IGDR - Institut de Génétique et Développement de Rennes

CUG-BP1 [CUG-binding protein 1 also called CELF (CUG-BP1 and ETR3 like factors) 1] is a human RNA-binding protein that has been implicated in the control of splicing and mRNA translation. The Xenopus homologue [EDEN-BP (embryo deadenylation element-binding protein)] is required for rapid deadenylation of certain maternal mRNAs just after fertilization. A variety of sequence elements have been described as target sites for these two proteins but their binding specificity is still controversial. Using a SELEX (systematic evolution of ligand by exponential enrichment) procedure and recombinant CUG-BP1 we selected two families of aptamers. Surface plasmon resonance and electrophoretic mobility-shift assays showed that these two families differed in their ability to bind CUG-BP1. Furthermore, the selected high-affinity aptamers form two complexes with CUG-BP1 in electrophoretic mobility assays whereas those that bind with low affinity only form one complex. The validity of the distinction between the two families of aptamers was confirmed by a functional in vivo deadenylation assay. Only those aptamers that bound CUG-BP1 with high affinity conferred deadenylation on a reporter mRNA. These high-affinity RNAs are characterized by a richness in UGU motifs. Using these binding site characteristics we identified the Xenopus maternal mRNA encoding the MAPK (mitogen-activated protein kinase) phosphatase (XCl100alpha) as a substrate for EDEN-BP. In conclusion, high-affinity CUG-BP1 binding sites are sequence elements at least 30 nucleotides in length that are enriched in combinations of U and G nucleotides and contain at least 4 UGU trinucleotide motifs. Such sequence elements are functionally competent to target an RNA for deadenylation in vivo.

Domaines: Biologie du développement

Julien Marquis, Luc Paillard, Yann Audic, Bertrand Cosson, Olivier Danos, et al.. CUG-BP1/CELF1 requires UGU-rich sequences for high-affinity binding.. Biochemical Journal, 2006, 400 (2), pp.291-301. ⟨10.1042/BJ20060490⟩. ⟨inserm-00292923⟩