NMR as a Powerful Tool for Identifying Natural Compounds Able to Interfere with ELAV-mRNA Complexes

RNA-protein interactions are the key to post-transcriptional gene expression and their regulation is a promising therapeutic modality for treating causative gene expression defect. In the late 20th century, RNA itself or its derivatives (anti-sense oligonucleotides, ribozymes, aptamers, siRNAs and miRNAs) have been proposed for inhibiting the expression of genes critical to the progression of several diseases. The functional forms of RNAs in cells are complexes formed by RNAs and specific proteins called RNA-binding proteins (RBPs). RNPs influence every aspect of the biogenesis and function of RNAs, accordingly the “RBP-RNA” complexes can be considered therapeutic targets. Small molecules able to perturb such complexes have the potential to selectively inhibit or enhance gene expression. Among RPBs, the Embryonic Lethal Abnormal Vision (ELAV) proteins are the best described and their dysregulation is involved in several pathologies, such as cancer, inflammation and neurodegenerative diseases.1 Recent studies have laid the foundation for the druggability assessment of ELAV proteins and STD-NMR was proposed as a useful tool for investigating the “protein-RNA” interaction. Particularly we have used advanced NMR techniques (Saturation transfer difference and Diffusion-Ordered spectroscopySpectroscopy) to gain insights into the ELAV-mRNA interaction mechanism, showing that appropriate fragments from conserved regions of ELAV effectively bind mRNAs and are able to interfere with their biological activity.2 Following our interest in ELAV-mimicking compounds we undertook an STD-NMR study on flavonoids3 in order to define the features of the “ideal ligand”. With this aim, we analyzed the interactions of a small library of such compounds with HuR. The information gained will be exploited to design new chemical entities able to interfere with ELAV-mRNA complexes. This study is a step towards the discovery of potent and selective compounds to act on “ELAV-RNA” complexes.