Characterizing toxic protein aggregates quickly

Researchers from the Adolphe Merkle Institute’s BioPhysics group have developed a groundbreaking technique for analyzing the size and shape of α-synuclein (αSyn) oligomers —protein aggregates implicated in Parkinson's disease and other neurodegenerative disorders. Using nanopore technology, this new method promises to improve our understanding and potential treatment of these debilitating conditions.

Neurodegenerative diseases, including Parkinson's, dementia with Lewy bodies, and multiple system atrophy, share a common feature: the misfolding and aggregation of the αSyn protein. These aggregates, or oligomers, are thought to play a critical role in the progression of these diseases. However, studying these oligomers has proven difficult due to their small size, varied nature, and formation process.

In a study published in the journal ACS Nano, the AMI BioPhysics group introduced a method utilizing polymer-coated solid-state nanopores to measure resistive pulses. This innovative approach allows scientists to characterize individual αSyn oligomers in solution rapidly and with high resolution. "This technique provides unprecedented detail on the size and shape of αSyn oligomers, which are important for understanding their toxicity," explains the AMI Chair of BioPhysics, Prof. Michael Mayer. "It overcomes the limitations of previous methods, offering superior resolution and faster analysis."

The study reveals that this nanopore-based method can identify ten distinct subpopulations of αSyn oligomer sizes, ranging from small aggregates to larger structures. These findings were validated through comparison with traditional techniques such as transmission electron microscopy and mass photometry.  However, one advantage of this new approach is that the analysis occurs in the solution of oligomers and is, therefore, much faster.

Moreover, the new method can approximate the shapes of these oligomers, providing insights that align with previous estimates obtained through more labor-intensive methods like cryo-electron microscopy. This capability is significant because the shape and size of oligomers are linked to their ability to form toxic pores in cell membranes, a likely factor in their neurotoxicity.

Given the putative association between elevated levels of αSyn oligomers and the onset of neurodegenerative diseases, this method could become an enabling tool for early diagnosis. Traditional immunoassays often struggle to differentiate between oligomers and other forms of αSyn, but the nanopore technique's precise size and shape measurements could provide more reliable biomarkers.

"This technology could lead to more accurate and earlier diagnosis of diseases like Parkinson's," says Mayer. "It also opens new avenues for developing treatments that target specific oligomeric forms of αSyn, potentially halting or even reversing disease progression."

This approach could enhance our understanding of numerous neurodegenerative diseases beyond those caused by αSyn by enabling detailed, single-particle analysis of protein aggregates. "Our goal is to make this method widely accessible," adds Mayer. "With further development, it could become a standard tool in both research and clinical settings, providing critical data to help combat these devastating diseases."

Reference: Awasthi, S.; Ying, C.; Li, J.; Mayer, M. Simultaneous Determination of the Size and Shape of Single α-Synuclein Oligomers in Solution. ACS Nano 2023, 17 (13), 12325–12335.