Optogenetic-mediated spatiotemporal control of α-synuclein aggregation mimics authentic Lewy body formation and triggers neurodegeneration

α-synuclein (α-syn) aggregation into insoluble deposits, referred to as Lewy bodies (LBs) is the paramount pathological hallmark of Parkinson’s disease (PD) and related α-synucleinopathies. However, how these aggregates affect neuronal homeostasis leading to neurodegeneration remains elusive. This gap in knowledge is mainly due to the lack of proper cellular and animal models to undertake such investigations.
AIMS
We have addressed this limitation by developing a light-inducible protein aggregation system (LIPA). This application is based on the use of a mutant form of the Arabidopsis thaliana photoreceptor cryptochrome 2 (CRY2), which when stimulated with blue light, mutant CRY2 undergoes rapid, reversible and robust protein clustering or aggregation. The use of this application allows for real-time induction of α-syn inclusions formation with remarkable spatial and temporal resolution in both cell culture and in vivo paradigms.
METHODS
We used a gene therapy approach, based on the use of adeno-associated virus (AAV), to overexpress our LIPA system directly into the brains of naive mice. For the delivery of the blue light necessary for the induction of the aggregation and propagation of α-syn, we used implantable micro-devices developed by Amuza Inc.
RESULTS
We report on the development of a light-inducible protein aggregation (LIPA) system that enables real-time induction of α-syn inclusion formation with remarkable spatial and temporal resolution in living cells. We demonstrate that LIPA-α-syn inclusions faithfully mimic key biochemical and ultrastructural features, as well as the seeding capacity of authentic LBs. In vivo, LIPA-α-syn aggregates compromised the nigrostriatal transmission, induced dopaminergic neuronal loss and PD-like behavioral impairment.
CONCLUSION
Our system provides a novel, dependable and invaluable tool to generate, visualize and dissect the role of protein aggregates in PD and possibly other neurodegenerative disorders.