Ser59 phosphorylation of 14-3-3γ modulates α-synuclein aggregation and reshapes its interactome

14-3-3 constitute a highly conserved family of proteins that participate in the regulation of essential cellular processes by establishing extensive protein-protein interactions. Consequently, perturbation of the 14-3-3s interactome can be implicated in the pathogenesis of several diseases. Phosphorylation has emerged as a key mechanism by which 14-3-3s interactome is dynamically regulated, and aberrantly phosphorylated 14-3-3s have been observed in patients with neurological disorders, among which Parkinson’s disease. Here, we investigate the role of Ser59 phosphorylation in 14-3-3γ and its impact on α-Synuclein aggregation by employing both the phosphorylated protein and the S59D phosphomimetic. Consistent with observations reported for other 14-3-3 isoforms, we found that this modification reduces the protective abilities of 14-3-3γ both in vitro and in cellular models. Importantly, this effect is also evident in cerebrospinal fluid (CSF), suggesting that phosphorylation of 14-3-3γ may directly contribute to α-Synuclein aggregation in vivo and may be relevant to disease-associated mechanisms. Using bioinformatics approaches, we further examined how Ser59 phosphorylation reshapes the global 14-3-3γ interactome, revealing novel interaction networks and pathways potentially implicated in neurodegenerative disease pathogenesis.