Fig. 4: The assessment of the antagonist activity of SK-129 in ex vivo PD models.

a The demographic and clinical information of the human brain tissues. Neuromelanin (brown) and αS immunostaining (LBs-like structure, bluish/black, black arrows, inset) in substantia nigra neurons from control (b) and PD (c) post mortem brain. Degenerating neurons and the extracellular neuromelanin debris from dying neurons (red arrows) were also visible. The hollow spaces in the PD brain demarcate cell loss. (Inset) A zoom in view of LB-like structure. TEM images of the αS seeds extracted from the control (d) and PD brains (e). f The αS stained western blot of the PMCA sample from the fifth cycle of the control and PD brain extracts after treatment with PK in the absence and presence of SK-129. Confocal images of HEK cells after treatment with control (g), control (h), and PD (i) brain extracts from PMCA sample (fifth cycle) and in the presence of SK-129 (j) at an equimolar ratio (j). The number of inclusions (k) and relative viability (l) of HEK cells in the presence of PMCA samples (fifth cycle) from PD brain extracts under the indicated conditions. A total of 100 HEK cells were examined to count the number of inclusions at four different locations in the eight-well plate for each experiment and it was repeated in four independent experiments. The data (for k, l) were expressed as mean and the error bars report the s.e.m. (n = 4 independent HEK cells-based experiments and each n consisted of 4 technical replicates). m Confocal imaging of primary neurons treated with PMCA samples (fifth cycle) of control and PD brain extracts in the absence and presence of SK-129 at an equimolar ratio for 21 days. The primary neurons were stained with various markers, including LB biomarkers (pS129 and p62), mitochondria marker (TOM20), and aggregate staining ThS dye. n Under matched conditions (to m), the neurotoxicity of primary neurons was measured using the LDH assay. The data were expressed as mean and the error bars report the s.e.m. (n = 4 independent LDH experiments and each n consisted of four technical replicates). The data were expressed as mean and the error bars report the s.e.m. (n = 4 independent experiments and each n consisted of four technical replicates). The statistical analysis was performed using ANOVA with Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Source data are provided as a Source Data file.