The toxicity of alpha-syn condensates in the presence and absence of metal ions

Abstract

Neurodegenerative diseases (NDDs), characterized by progressive neuronal death and misfolded protein aggregation, pose significant clinical, social, and personal challenges. Parkinson's Disease (PD), the second most common neurological disorder, is notably associated with the aggregation of alpha-synuclein (aSyn). Despite its prominence, the transition of monomeric aSyn to aggregates remains inadequately understood. Recent studies suggest that Liquid-Liquid Phase Separation (LLPS) and disease related metal ions involve the transition in the molecular pathogenesis of PD. LLPS involves the separation of biomolecules into distinct phases without a membrane, potentially facilitating aSyn aggregation through dynamic condensates that eventually form solid deposits. I aim to investigate LLPS of aSyn and macroscopy dynamics of its formed droplets over time, and examine how PD related metal ions, affect the dynamic process of LLPS and modulate its toxicity to neuroblastoma cells. These metal ions, prevalent in the brain and specifically interacting with aSyn are presumably modulating LLPS, toxicity and aggregation of aSyn, making it crucial to understand their roles in the molecular pathogenesis of PD I expressed α-synuclein (aSyn) proteins in E. coli and studied the biophysical properties and toxicities of aSyn-metal ion coacervates using various techniques, including a protein crystallization robotic dispenser and confocal microscopy. In the presence of metal ions such as CuCl₂, MnCl₂, ZnCl₂, and FeCl₃, the number of droplets significantly decreased. I found that CuCl₂ ions immobilize aSyn condensates and increase their toxicity. In contrast, MnCl₂, ZnCl₂, and FeCl₃ help maintain a longer metastable state of the condensates, reducing their toxicity This project highlights the crucial role of metal ions in modulating aSyn phase behavior, condensate toxicity and their potential involvement in the progression of PD.