Identification of N-linked glycans as specific mediators of neuronal uptake of acetylated α-Synuclein

Cell-to-cell transmission of toxic forms of α-Synuclein (αS) is thought to underlie disease progression in Parkinson disease. αS in humans is constitutively N-terminally acetylated (αS(acetyl)), although the impact of this modification is relatively unexplored. Here, we report that αS(acetyl) is more effective at inducing intracellular aggregation in primary neurons than unmodified αS (αS(un)). We identify complex N-linked glycans as binding partners for αS(acetyl) and demonstrate that cellular internalization of αS(acetyl) is reduced significantly upon cleavage of extracellular N-linked glycans, but not other carbohydrates. We verify binding of αS(acetyl) to N-linked glycans in vitro, using both isolated glycans and cell-derived proteoliposomes. Finally, we identify neurexin 1β, a neuronal glycoprotein, as capable of driving glycan-dependent uptake of αS(acetyl). Importantly, our results are specific to αS(acetyl) because αS(un) does not demonstrate sensitivity for N-linked glycans in any of our assays. Our study identifies extracellular N-linked glycans—and the glycoprotein neurexin 1β specifically—as key modulators of neuronal uptake of αS(acetyl), drawing attention to the potential therapeutic value of αS(acetyl)-glycan interactions.