X1INH, an improved next-generation affinity-optimized hydrazonic ligand, attenuates abnormal copper()/copper()-α-Syn interactions and affects protein aggregation in a cellular model of synucleinopathy

• Published in: Dalton transactions : an international journal of inorganic chemistry 2020-11, Vol.49 (45), p.16252-16267
• Main Authors: Cukierman, Daphne S, Lázaro, Diana F, Sacco, Pamela, Ferreira, Patrícia R, Diniz, Renata, Fernández, Claudio O, Outeiro, Tiago F, Rey, Nicolás A
• Format: Article
• Language: English
• Subjects: Affinity; Agglomeration; Binding; Copper; Copper compounds; Crystallography; Hydrazones; Imidazole; Inclusions; Ligands; NMR; Nuclear magnetic resonance; Parkinson's disease; Proteins
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d0dt01138j

Although normal aging presents an accumulation of copper and iron in the brain, this becomes more relevant in neurodegeneration. α-Synuclein (α-Syn) misfolding has long been linked with the development of Parkinson's disease (PD). Copper binding promotes aggregation of α-Syn, as well as generalized oxidative stress. In this sense, the use of therapies that target metal dyshomeostasis has been in focus in the past years. Metal-Protein Attenuating Compounds (MPACs) are moderate chelators that aim at disrupting specific, abnormal metal-protein interactions. Our research group has now established that N -acylhydrazones compose a set of truly encouraging MPACs for the bioinorganic management of metal-enhanced aggregopathies. In the present work, a novel ligand, namely 1-methyl-1 H -imidazole-2-carboxaldehyde isonicotinoyl hydrazone (X1INH), is reported. We describe solution studies on the interaction and affinity of this compound for copper( ii ) ions showing that a fine tuning of metal-affinity was achieved. A series of in vitro biophysical NMR experiments were performed in order to assess the X1INH ability to compete with α-Syn monomers for the binding of both copper( i ) and copper( ii ) ions, which are central in PD pathology. A preference for copper( i ) has been observed. X1INH is less toxic to human neuroglioma (H4) cells in comparison to structure-related compounds. Finally, we show that treatment with X1INH results in a higher number of smaller, less compact inclusions in a well-established model of α-Syn aggregation. Thus, X1INH constitutes a promising MPAC for the treatment of Parkinson's disease. By tuning the copper( i )/copper( ii ) affinity of a novel N -acylhydrazone, a more soluble, hydrolysis resistant and less toxic improved Metal-Protein Attenuating Compound for the bioinorganic management of metal-enhanced aggregopathies was obtained.