2D polarization imaging as a low-cost fluorescence method to detect α-synuclein aggregation ex vivo in models of Parkinson’s disease

A hallmark of Parkinson’s disease is the formation of large protein-rich aggregates in neurons, where α-synuclein is the most abundant protein. A standard approach to visualize aggregation is to fluorescently label the proteins of interest. Then, highly fluorescent regions are assumed to contain aggregated proteins. However, fluorescence brightness alone cannot discriminate micrometer-sized regions with high expression of non-aggregated proteins from regions where the proteins are aggregated on the molecular scale. Here, we demonstrate that 2-dimensional polarization imaging can discriminate between preformed non-aggregated and aggregated forms of α-synuclein, and detect increased aggregation in brain tissues of transgenic mice. This imaging method assesses homo-FRET between labels by measuring fluorescence polarization in excitation and emission simultaneously, which translates into higher contrast than fluorescence anisotropy imaging. Exploring earlier aggregation states of α-synuclein using such technically simple imaging method could lead to crucial improvements in our understanding of α-synuclein-mediated pathology in Parkinson’s Disease.
Camacho et al. show detection of non-aggregated and aggregated α-synuclein in brain tissue from a mouse model of Parkinson’s disease using 2-dimensional polarization imaging. This fluorescence imaging method will allow for early detection of pathogenic α-synuclein aggregates associated with neurodegenerative illnesses.