Pirota, V.; Rey, F.; Fantini, V.; Esposito, L.; Pandini, C.; Di Gerlando, R.; Doria, F.; Mella, M.; Pansarasa, O.; Gandellini, P.; Freccero, M.; Carelli, S.; Cereda, C.

Alpha-synuclein, encoded by the SNCA gene, is a pivotal protein implicated in the pathogenesis of synucleinopathies, including Parkinson\'s disease. Current approaches for modulating alpha-synuclein levels involve antisense nucleotides, siRNAs, and small molecules targeting SNCA\'s 5\'-UTR mRNA. Here, we propose a groundbreaking strategy targeting G-quadruplex structures to effectively modulate SNCA gene expression and lowering alpha-synuclein amount. Novel G-quadruplex sequences, identified on the SNCA gene\'s transcription starting site and 5\'-UTR of SNCA mRNAs, were experimentally confirmed for their stability through biophysical assays and in vitro experiments on human genomic DNA. Biological validation in differentiated SH-SY5Y cells revealed that well-known G-quadruplex ligands remarkably stabilized these structures, inducing the modulation of SNCA mRNAs expression, and the effective decrease in alpha-synuclein amount. Besides, a novel peptide nucleic acid conjugate, designed to selectively disrupt of G-quadruplex within the SNCA gene promoter, caused a promising lowering of both SNCA mRNA and alpha-synuclein protein. Altogether our findings highlight G-quadruplexes\' key role as intriguing biological targets in achieving a notable and successful reduction in alpha-synuclein expression, pointing to a novel approach against synucleinopathies.