Kavli Oxford researchers reveal differences in alpha-synuclein associated with neurodegenerative diseases
Kavli Oxford researchers reveal differences in alpha-synuclein associated with neurodegenerative diseases
Kavli Oxford researchers have identified differences in the way alpha-synuclein, a protein linked to Parkinson’s disease and other neurodegenerative conditions, is arranged on tiny particles, called extracellular vesicles, that are released by cells. Some of these differences could also be detected in blood, potentially offering a new way to diagnose diseases that can otherwise be difficult to tell apart. The research brought together members of the Tofaris and Kapanidis groups at Kavli Oxford, combining expertise in neurodegenerative disease with super-resolution microscopy (dSTORM).
The study, published in Brain, provides new insights into alpha-synuclein and how its arrangement may differ between Parkinson’s disease, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). Alpha-synuclein is found naturally in the brain, but in these conditions it can fold abnormally and clump together. Although all three diseases involve abnormal alpha-synuclein, they affect the brain in different ways and can progress differently. Particularly in the early stages, however, their symptoms can overlap. Showing that a disease-associated difference in the arrangement of alpha-synuclein can be detected in blood provides a potentially useful direction for further research into how these conditions might be distinguished and studied.
Professor George Tofaris, corresponding author of the study and Kavli Oxford Principal Investigator, said: ‘One of the major challenges in these disorders is that they share the accumulation of the same protein, alpha-synuclein, but differ considerably in how they affect the brain and progress clinically. Our findings in brain tissue and blood suggest that how alpha-synuclein is presented on extracellular vesicles could offer a means of distinguishing between related neurodegenerative conditions.’
Different patterns of protein organisation
The Kavli Oxford team studied alpha-synuclein associated with extracellular vesicles, microscopic packages released by cells that carry proteins and other biological material. Using dSTORM to examine these tiny vesicles at the nanoscale, the researchers looked at both how much alpha-synuclein was associated with them and how the protein was arranged. They found different patterns between the diseases.
In Parkinson’s disease and DLB, there was more alpha-synuclein associated with extracellular vesicles, including an increase in neuronal extracellular vesicles carrying aggregated, or clumped, forms of the protein. MSA showed a different pattern: the researchers did not see the same overall increase in alpha-synuclein. Rather, they found differences in how particular parts of the protein were exposed. Proteins are long chains that fold into particular shapes. Depending on how a protein folds or interacts with other proteins, some sections can be exposed while others are hidden. In MSA, a particular section of alpha-synuclein was more exposed on the surface of certain extracellular vesicles than it was in Parkinson’s disease. This suggests that it is not only the amount of abnormal alpha-synuclein that differs between these diseases, but also the way the protein is organised.
Representative three-colour dSTORM images of single L1CAM⁺ Evs isolated from substantia nigra, showing surface-exposed C-terminal (MJFR1, green) and N-terminal (A15110D, green) αSynepitopes in HC, DLB, PD and MSA. EVs are identified by TetraTrio (red) and L1CAM (blue). Scale bar: 200 nm. Image: Suman Dutta Molecular Neurodegeneration Research Group
A difference detectable in blood
The researchers first identified these differences by studying extracellular vesicles from brain tissue. They then investigated whether the MSA-associated pattern could also be detected in blood. They found a greater proportion of neuronal extracellular vesicles displaying this particular alpha-synuclein feature in blood samples from people with MSA than in samples from people with Parkinson’s disease or healthy controls.
The findings build on previous research by the Tofaris group that investigated extracellular vesicles in blood as a source of biomarkers for Parkinson’s disease and related conditions. By examining the cellular origin and molecular characteristics of alpha-synuclein associated with these particles, the study also establishes a link between disease-associated molecular signatures detected in blood and those found in the brain.
Interdisciplinary collaboration
The research builds on an interdisciplinary collaboration first supported through Kavli Oxford’s K.A.R.D seed-funding scheme, bringing together expertise in neuroscience, chemistry and physics to study neuronal extracellular vesicles. That collaboration has since also led to an ARUK-funded project investigating protein transport in brain extracellular vesicles.
First author Dr Suman Dutta said: ‘Combining our expertise in neurodegenerative diseases with super-resolution microscopy enabled us to look beyond bulk EV measurements and explore molecular differences at the level of individual vesicles with nanoscale resolution. The interdisciplinary environment at the Kavli Institute for Nanoscience Discovery, together with its seed funding, gave us the freedom to pursue challenging ideas and ultimately turn a new research direction into meaningful scientific findings.’
Dr Stelios Chatzimichail, co-author of the paper from the Kapanidis Group, now at the University of Cyprus, noted that: ‘Many of the next frontiers in science lie at the boundaries between disciplines. Working with Suman and the Tofaris Group was a rewarding example of this, bringing together our experience in super-resolution microscopy and a deep understanding of neurodegenerative disease to explore new questions. These collaborations grow through spending time together, sharing practical skills and learning how colleagues in other fields approach a problem. The Kavli Institute for Nanoscience Discovery provided both the environment and seed funding to make that exchange possible.’
Principal Investigator, Professor Achillefs Kapanidis, agreed: ‘We are excited to see that the toolbox we developed for super-resolution imaging of nano-assemblies and microbes could provide fresh insight on neurodegenerative disease. Working with our biological colleagues has been very enjoyable, and it is wonderful that the environment in our Kavli Institute for Nanoscience Discovery catalyses such interdisciplinary collaborations.’
Professor George Tofaris added: ‘This study highlights the power of single-molecule resolution microscopy to uncover disease-specific molecular signatures and, more broadly, the value of interdisciplinary collaborations fostered by the Kavli Institute for Nanoscience Discovery.’
Read the research: ‘Extracellular vesicle α-synuclein topology reveals disease-associated conformers in brain and blood’, published in Brain. Authors: Suman Dutta, Amin Atashgaran, Anis Sahoo, Stelios Chatzimichail, Achillefs N Kapanidis, George K Tofaris
