G51D mutation of the endogenous ratSncagene disrupts synaptic localisation of α-synuclein priming for Lewy-like pathology

Abstract

AbstractPoint mutations in theSNCAgene, encoding α-synuclein (αSyn), are a known cause of familial Parkinson’s disease. The G51D mutation causes early onset neurodegeneration with complex pathology. We used CRISPR/Cas9 in rats to introduce the G51D mutation into the endogenousSncagene. Co-localisation immunostaining studies with synaptic proteins showed that αSynG51Dprotein is no longer efficiently localised to synapses. Furthermore, biochemical isolation of synaptosomes from rat cortex demonstrated a significant depletion of αSyn inSncaG51D/+andSncaG51D/G51Drats. Unbiased proteomic investigation of the cortex identified significant synaptic dysregulation inSncaG51D/G51Danimals. Finally, we compared the propensity for Lewy-like pathology ofSnca+/+andSncaG51D/G51Drats by stereotaxically delivering αSyn pre-formed fibrils (PFFs) into the pre-frontal cortex. At an early time-point, 6 weeks post-injection, we observed discrete Lewy-like structures positive for phosphoserine-129-αSyn (pS129-αSyn) only inSncaG51D/G51Dbrains. At 26 weeks post-injection of PFFsSncaG51D/G51Dbrains exhibited intense, discrete pS129-αSyn-positive structures, whileSnca+/+brains exhibited diffuse pS129-αSyn immunostaining. Quantification of discrete pS129-αSyn-positive structures revealed the striatum ofSncaG51D/G51Drats had significantly more Lewy-like pathology thanSnca+/+rats. In summary, this novelSncaG51Drat model exhibits molecular characteristics of early synaptic dysfunction and is primed for αSyn pathology.