Constitutive nuclear accumulation of endogenous alpha-synuclein in mice causes motor dysfunction and cortical atrophy, independent of protein aggregation

Abstract

Background A growing body of evidence suggests that nuclear alpha-synuclein (aSyn) plays a role in the pathogenesis of Parkinson's disease (PD). However, this question has been difficult to address as controlling the localization of aSyn in experimental systems often requires protein overexpression, which results in aggregation. Methods We engineered SncaNLS mice which localize endogenous aSyn to the nucleus. We characterized these mice on a behavioral, histological, and biochemical level to determine whether the increase of nuclear aSyn is sufficient to elicit disease phenotypes. Results SncaNLS mice exhibit age-dependent motor deficits and altered gastrointestinal function. We found that these phenotypes were not linked to aSyn aggregation or phosphorylation. Through histological analyses, we observed motor cortex atrophy in the absence of midbrain dopaminergic neurodegeneration. We sampled cortical proteomes of SncaNLS mice and controls to determine the molecular underpinnings of these pathologies. Interestingly, we found several dysregulated proteins involved in dopaminergic signaling, namely Darpp-32, which we further confirmed was decreased in cortical samples of the SncaNLS mice compared to controls via immunoblotting. Conclusions These results suggest that chronic endogenous nuclear aSyn can elicit toxic phenotypes in mice, independent of its aggregation. This model raises key questions related to the mechanism of aSyn toxicity in PD and provides a new model to study an underappreciated aspect of PD pathogenesis.

Genetic and pharmacological reduction of CDK14 mitigates synucleinopathy

“…Brain tissue of 5-month-old PAC α-Syn A53T TG mice was weighed and lysed 1:3 (w/v) in PEPI buffer (5 mM EDTA, protease inhibitor [GenDEPOT, P3100, Katy, TX, USA] and phosphatase inhibitor [GenDEPOT, P3200] in PBS) with a Dounce homogenizer. Samples were further lysed 1:6 (w/v) using the tissue weight in TSS Buffer (140 mM NaCl, 5 mM Tris-HCl), then TXS Buffer (140 mM NaCl, 5 mM Tris-HCl, 0.5 % Triton X-100), and SDS Buffer (140 mM NaCl, 5 mM Tris-HCl, 1 % SDS), as previously described (32).…”