A novel stable transgenic zebrafish line expressing mCherry-tagged human alpha-synuclein in the nervous system and exhibiting all the key features of Lewy body disorders at larval stage

Abstract

Lewy Bodies, proteinaceous inclusions containing α-Synuclein fibrillary aggregates, are defining neuropathological hallmarks of Parkinson's disease and Dementia with Lewy Bodies. Recently, zebrafish arose as a valuable model to study neurodegenerative diseases, but despite attempts to generate stable human α-Synuclein transgenic zebrafish lines recapitulating the main phenotypic characteristics of Lewy Body disorders, i.e., α-Synuclein fibrillary aggregate deposition, neurodegeneration and behavioral deficits, none of the models produced so far could develop all these features. Here, we describe the generation of a novel transgenic zebrafish line stably expressing human α-Synuclein in the nervous system and developing all the key Parkinson's Disease phenotypic traits during larval stage, named Tg(elavl3:mCherry-hsa.SNCA). By behavioral studies, molecular biology analysis, confocal and light-sheet fluorescence microscopy we found that Tg(elavl3:mCherry-hsa.SNCA) larvae developed basal motility deficits and anxiety traits as well as a significant increase of brain apoptotic cells in parallel with marked reduction of tyrosine hydroxylase-immunopositivity in forebrain regions at 5 days post fertilization. The Tg(elavl3:mCherry-hsa.SNCA) larvae accumulated Thioflavin-S-positive and high molecular weight serine-129-phosphorylated α-Synuclein. Furthermore, they displayed other typical pathologic alterations associated with Parkinson's Disease and Dementia with Lewy Bodies, such as accumulation of synapsins and changes in key autophagy markers. These findings, coupled with the suitability of larval zebrafish for high-throughput screening, support that the novel Tg(elavl3:mCherry-hsa.SNCA) line constitutes the first stable zebrafish experimental model for rapid and reliable studies addressing both the molecular basis of Lewy body disorders and the efficacy of new therapeutic approaches.

Keywords: Behavioral abnormalities; Neurodegeneration; Parkinson's disease; Zebrafish; Α-Synuclein.