Summary: Researchers report that the three-dimensional shapes of a specific set of proteins in cerebrospinal fluid differ between people with Parkinson’s disease and healthy individuals, suggesting a new class of structural biomarkers for the disease.
Source: ETH Zurich
ETH Zurich investigators have discovered that many proteins in the cerebrospinal fluid (CSF) adopt distinct structural forms in people with Parkinson’s disease compared with healthy controls. These structural differences may form the basis of a new type of biomarker for diagnosing and characterizing Parkinson’s disease.
Biomarkers found in blood and other body fluids play a central role in detecting and monitoring many illnesses. Parkinson’s disease, however, currently lacks reliable biomarkers in routine clinical use. The ETH Zurich team led by Professor Paola Picotti sought to address this gap by analyzing not just protein abundance but protein structure across the CSF proteome.
In a study published in Nature Structural and Molecular Biology, the researchers report 76 proteins whose structural states differ consistently between 50 people diagnosed with Parkinson’s disease and 50 healthy donors. Importantly, these proteins are present in both groups; what changes is their conformation—the specific arrangement of atoms and folding that determines protein function.
Structural differences as indicators
Traditional proteomics focuses on which proteins are present and in what amounts. This study applies a complementary perspective: because protein function is tightly coupled to structure, disease-related functional changes may be detectable as shifts in protein conformation even when overall abundance remains similar. The ETH Zurich team’s approach thus identifies structural alterations that may be linked to the pathophysiology of Parkinson’s disease.
This work represents the first demonstration that a global, in situ analysis of protein structure in a body fluid can point to candidate biomarkers for a neurodegenerative disease. The 76 structurally altered proteins reported in this study are enriched in biological processes known to be disrupted in Parkinson’s disease, and several of the same proteins also show structural changes in brain tissue from affected individuals.
Method: measuring structural changes with LiP‑MS
To detect structural differences, the researchers used limited proteolysis–mass spectrometry (LiP‑MS), a proteome-wide method that identifies conformational changes and maps the specific regions of proteins that are affected. Unlike conventional proteome analyses that emphasize abundance, LiP‑MS reveals proteolysis sensitivity patterns that reflect structural variation across the proteome.
Applying LiP‑MS to CSF samples from the study cohort allowed the team to detect structural signatures that distinguished Parkinson’s patients from healthy donors. Structural information from CSF outperformed abundance measurements alone in discriminating disease status and enhanced the diagnostic signal of established Parkinson’s markers such as α‑synuclein.
Next steps and clinical prospects
The findings are promising but preliminary. The identified structural biomarkers require validation in larger, independent patient cohorts before they can be considered for clinical use. The research team plans to refine the LiP‑MS technique to amplify these structural signals and improve sensitivity, and to test how specifically the markers distinguish Parkinson’s disease from other neurodegenerative disorders such as Alzheimer’s disease.
Longer term, structural biomarkers could enable subtype classification of Parkinson’s disease and improve prognosis by revealing distinct molecular disease mechanisms. One envisioned diagnostic route would use antibodies or other affinity reagents that discriminate between healthy and disease-associated protein conformations. While the routine use of mass spectrometry in clinical diagnostics is feasible in principle, broad implementation would face logistical and technical challenges.
About this Parkinson’s disease research news
Author: Press Office
Source: ETH Zurich
Contact: Press Office – ETH Zurich
Image: The image is in the public domain
Original Research: Closed access.
Title: “Global, in situ analysis of the structural proteome in individuals with Parkinson’s disease to identify a new class of biomarker” by Marie‑Therese Mackmull et al., published in Nature Structural and Molecular Biology.
Abstract
Global, in situ analysis of the structural proteome in individuals with Parkinson’s disease to identify a new class of biomarker
Parkinson’s disease (PD) is a common neurodegenerative disorder for which robust biomarkers are urgently needed. Because protein structure reflects function, the study tested whether a global, in situ analysis of protein structural changes could yield insight into PD pathophysiology and support a new concept of structural disease biomarkers.
Using limited proteolysis–mass spectrometry (LiP‑MS), the researchers identified 76 structurally altered proteins in cerebrospinal fluid from individuals with PD relative to healthy donors. These proteins were enriched in processes known to be misregulated in PD, and several also showed structural changes in PD brain samples.
Structural information from CSF outperformed abundance-based measures in distinguishing participants with PD from healthy individuals and improved the discriminatory performance of CSF measures of the hallmark PD protein α‑synuclein. The study also reports the first characterization of inter‑individual variability in the structural proteome of healthy people, revealing biophysical features of regions that vary between individuals.
Independent validation is required, but these data indicate that global analysis of the human structural proteome can guide development of novel structural biomarkers and generate hypotheses about underlying disease mechanisms, opening new avenues for diagnosis and research into Parkinson’s disease.