Generation of Alpha-Synuclein Conformation Specific Aptamers for In Vivo Bioimaging of Alpha-Synuclein Pathology
Critical Challenges in PD: Alpha-synuclein Neuroimaging, 2008
Alpha-synuclein is an abundant brain protein, whose misfolding has been associated to the development of Parkinson’s disease. Visualization of the different misfolded forms of alpha-synuclein in brain tissue by neuroimaging will ultimatively allows the monitoring of the disease development and response to treatments. This project will exploit a new technology to develop novel aptamer binders, engineered RNA molecules, which can discriminate between normal and disease associated forms and try to develop the binders into neuroimaging tools.
The disease associated misfolding of alpha-synuclein encompasses more steps from monomers via soluble misfolded oligomers to large insoluble filaments and are though to comprise specific toxic species. The nature of those species and their spatial and temporal distribution during disease development are largely unknown. Large libraries of synthetic RNA molecules, aptamers will be generated that hypothetically will be able to recognize almost all possible three dimensional structures. We will screen such libraries for aptamers that selectively bind to monomeric, oligomeric and filamentous forms of alpha-synuclein and validate their selectivity using appropriate controls, e.g. misfolded peptides found in Alzheimers disease. The purified aptamers will subsequently be analyzed bioinformatically whereafter optimal aptamers will be synthesized with a small tag that allows their visualization. The tagged aptamers will finally be investigated using human brain tissue affected by Parkinson’s disease to determine if they can highlight novel forms of early disease associated changes.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
The aptamer technology holds the potential of developing tools to identify novel forms of disease associated changes in alpha-synuclein that hitherto have been concealed due to insufficient imaging tools. The current project aims at providing such new imaging tools. When developed into neuroimaging tools such aptamers may allow earlier and more precise diagnosis and allow for the more precise determination of patient responses to future clinical trials of neuroprotective therapies.
The expected outcome of the project will be a limited number of aptamers that selectively are able to discriminate between different forms of misfolded alpha-synuclein species and successfully have been validated for their ability to demonstrate abnormal alpha-synuclein forms in brain tissue affected by Parkinson’s disease.
INTERIM PROGRESS REPORT
Alpha-synuclein is deposited in PD brain tissue in aggregated forms and it is hypothesized that soluble smaller aggregates (oligomers) represent the toxic species. At present, the ability to visualize aggregated forms in brain tissue and distinguish between the different forms (filaments and oligomers) is not very good. Our project aims to develop novel binding molecules based on RNA-aptamers (short RNA molecules) that selectively recognize filaments and oligomers in brain tissue and cells. Our data indicate that we can generate aggregate specific aptamers although work is still ongoing. The next step will be to test the most promising aptamers in human PD brain tissue.
Alpha-synuclein is in Parkinson’s disease (PD) brain tissue deposited in aggregated forms and it is hypothesized that soluble smaller aggregates (oligomers) represent the toxic species. At present the ability to visualize aggregated forms in brain tissue and distinguish between filamentous and oligomeric is not very good. The present project aims at developing novel binding molecules based on RNA-aptamers that selectively recognize filaments and oligomers in brain tissue and cells. Unfortunately we were unable to develop specific aptamers targeting filaments and oligomers. Ongoing work is aimed at identifying the reason for this failure.
Professor of Medical Biochemistry at Aarhus University
Location: , Denmark