No abstract

Regulation of gene transcription is an essential mechanism for differentiation and adaptation of organisms. A key actor in this regulation process is the repressor element 1 (RE1)-silencing transcription factor (REST), a transcriptional repressor that controls more than 2000 putative target genes, most of which are neuron-specific. With the purpose of modulating REST expression, we exploited synthetic, ad hoc designed, RNA binding proteins (RBPs) able to specifically target and dock to REST mRNA. Among the various families of RBPs, we focused on the Pumilio and FBF (PUF) proteins, present in all eukaryotic organisms and controlling a variety of cellular functions. Here, a combined experimental and computational approach was used to design and test 8-and 16-repeat PUF proteins specific for REST mRNA. We explored the conformational properties and atomic features of the PUF-RNA recognition code by Molecular Dynamics simulations. Biochemical assays revealed that the 8-and 16repeat PUF-based variants specifically bind the endogenous REST mRNA without affecting its translational regulation. The data also indicate a key role of stacking residues in determining the binding specificity. The newly characterized REST-specific PUF-based constructs act as excellent RNA-binding modules and represent a versatile and functional platform to specifically target REST mRNA and modulate its endogenous expression.

The synthesis of new bis‐deoxy‐coelenterazine (1) derivatives bearing ester protective groups (acetate, propionate and butyrate esters) was accomplished. Moreover, their hydrolytic stability at room temperature was evaluated in dimethylsulfoxide (DMSO) as solvent, using the nuclear magnetic resonance (NMR) spectra of the key products at different time intervals. The results showed an increasing hydrolysis rate according to longest aliphatic chain, with a half‐life of 24 days of the more stable acetate derivative (4a). Furthermore, the analysis of the experimental data revealed the greater stability of the enol tautomer in this aprotic polar solvent. This result was confirmed by theoretical calculations using the density functional theory (DFT) approach, which gave us the opportunity to propose a detailed decomposition mechanism. Additionally, the derivatives obtained were tested by bioluminescence luciferase assays to evaluate their potential use as extracellular pH‐sensitive reporter substrates of luciferase. The biological data support the idea that further structural modifications of these molecules may open promising perspectives in this field of research.