Monitoring Cell-to-cell Transmission of Prion-like Protein Aggregates in <em>Drosophila Melanogaster</em>

Abstract

Protein aggregation is a central feature of most neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). Protein aggregates are closely associated with neuropathology in these diseases, although the exact mechanism by which aberrant protein aggregation disrupts normal cellular homeostasis is not known. Emerging data provide strong support for the hypothesis that pathogenic aggregates in AD, PD, HD, and ALS have many similarities to prions, which are protein-only infectious agents responsible for the transmissible spongiform encephalopathies. Prions self-replicate by templating the conversion of natively-folded versions of the same protein, causing spread of the aggregation phenotype. How prions and prion-like proteins in AD, PD, HD, and ALS move from one cell to another is currently an area of intense investigation. Here, a Drosophila melanogaster model that permits monitoring of prion-like, cell-to-cell transmission of mutant huntingtin (Htt) aggregates associated with HD is described. This model takes advantage of powerful tools for manipulating transgene expression in many different Drosophila tissues and utilizes a fluorescently-tagged cytoplasmic protein to directly report prion-like transfer of mutant Htt aggregates. Importantly, the approach we describe here can be used to identify novel genes and pathways that mediate spreading of protein aggregates between diverse cell types in vivo. Information gained from these studies will expand the limited understanding of the pathogenic mechanisms that underlie neurodegenerative diseases and reveal new opportunities for therapeutic intervention.

Phagocytic glia are obligatory intermediates in transmission of mutant huntingtin aggregates across neuronal synapses

“…1A) accumulate in HD patient brains, are highly cytotoxic, and spread between cells in culture and in vivo (Babcock and Ganetzky, 2015; Costanzo et al, 2013; Pearce et al, 2015; Pecho-Vrieseling et al, 2014; Ren et al, 2009). We have previously established transgenic Drosophila that employ binary expression systems [e.g., Gal4-UAS, QF-QUAS, or LexA-LexAop (Riabinina and Potter, 2016)] to express fluorescent protein (FP) fusions of Htt ex1 in non-overlapping cell populations in order to monitor cell-to-cell transfer of mHtt ex1 aggregates in intact brains (Donnelly and Pearce, 2018; Pearce et al, 2015). Our experimental approach (Fig.…”

Prion-Like Mechanisms in Parkinson’s Disease

“…There have been recent studies on the methods that allow for monitoring prion-like propagation of the pathogenic protein between diverse cells in the Drosophila melanogaster model. This experimental paradigm can be useful for investigating and identifying molecular mechanisms underlying α-syn pathology in PD (McGurk et al, 2015; Donnelly and Pearce, 2018).…”