Conclusions
Our results demonstrate alterations of striatal synaptic neurofilament pool in α-synucleinopathy models and open the way to further investigations evaluating a potential role of neurofilament dysregulation in explaining glutamatergic synaptic dysfunction observed in α-synucleinopathies such as Parkinson's disease.
Methods
We used confocal imaging and biochemical approaches to confirm NMDAR-NfL interaction at synapses. Western blotting in purified fractions and co-immunoprecipitation assays were then performed to assess synaptic neurofilament expression and GluN1-NfL interaction in (i) α-synuclein pre-formed fibrils (α-syn PFF)-treated hippocampal neuronal cultures and (ii) mice intrastriatally injected with α-syn-PFF.
Results
We identified the existence of a direct protein-protein interaction between NMDAR and NfL endogenously expressed in neurons. Our findings showed increased striatal GluN1-NfL interaction levels at early phases of α-syn PFF-treated mice compared to controls (NfL/GluN1 optical density: α-syn PFF 0.71 ± 0.04; controls 0.48 ± 0.03; t(9) = 4.67; p = 0.001). In agreement with this observation, we found that NfL levels are increased in striatal postsynaptic fractions of α-syn PFF-treated mice (normalized optical density: α-syn PFF 1.86 ± 0.14; controls 1.34 ± 0.13; t(18) = 2.70; p = 0.015). Conclusions: Our results demonstrate alterations of striatal synaptic neurofilament pool in α-synucleinopathy models and open the way to further investigations evaluating a potential role of neurofilament dysregulation in explaining glutamatergic synaptic dysfunction observed in α-synucleinopathies such as Parkinson's disease.