Mutations and multiplications in the SNCA gene encoding the alpha-synuclein protein are linked to an autosomal dominant form of Parkinson’s disease (PD). One such mutation is the alanine-to-threonine substitution at amino acid 53, leading to early onset PD, possibly through an increased propensity for the A53T alpha-synuclein to aggregate. To better understand the biology of this mutation and develop a model for PD, The Michael J. Fox Foundation for Parkinson’s Research developed a rat model in which CRISPR/Cas9 genome targeting strategies were used to insert humanized amino acids for the region spanning amino acids 53-122 in the rat SNCA gene to create a humanized A53T alpha-synuclein rat model with a non-functional rat SNCA gene (aSyn A53T KI). A rat SNCA KO model (aSyn KO) was also developed using CRISPR/Cas9 through the insertion of a single base pair to read a premature stop codon.
Here, we describe phenotypic characteristics of the aSyn A53T KI rat at 4, 8, and 12 months of age as well as biochemical characterization of aSyn KO rat at 6 and 12 months of age. aSyn A53T KI rats and their wildtype littermates (20 rats/genotype/timepoint, mixed gender) were subjected to a battery of behavior tests, including fine motor kinematic analysis, home cage motor activity, open field, tapered beam balance, nest building and GI motility. After the behavioral assessment, various tissue samples were collected from each age cohort for subsequent histological and biochemical analyses. Ex vivo outcome measures included expression of SNCA gene on different brain regions, immunohistochemical analysis of pS129 aSyn and total aSyn in the gut, and immunohistochemical analysis of the brains for proteinase K resistant aSyn, GFAP, Iba-1, AT8 pS202/pT205 Tau, pS129 aSyn, total aSyn, and tyrosine hydroxylase.