Fig. 4: Downregulation of general neurotransmission-related genes in early synucleinopathy.

a Diagram of the vesicular release process during neurotransmission, showing the docking, priming, fusion pore opening, and fusion stages. Proteins encoded by transcripts downregulated in early synucleinopathy are highlighted in green. b Fischer 344 rats received two intrastriatal injections of 4 µg/µL α-syn PFFs or PBS (Vehicle), SN was collected 2-months after PFF administration from flash-frozen tissue and processed for ddPCR. Graphs show mRNA from genes in the general vesicular release process normalized to Rpl13a mRNA and measured via ddPCR. Transcripts assessed were Rab3a (Ras-associated binding protein 3a), Rab3c (Ras-associated binding protein 3c), Rab27b (Ras-associated binding protein 27b), Vamp2 (synaptobrevin 2), Stx1b (syntaxin 1b), Syt1 (synaptotagmin 1), Syt2 (synaptotagmin 2), Syt3 (synaptotagmin 3), Snap25 (synaptosome associated protein 25), Stxbp1 (syntaxin binding protein 1, also known as MUNC18), Pclo (piccolo), Bsn (bassoon), Erc2 (ELKS/RAB6-interacting/CAST family member 2, also known as CAST1), Rims1 (regulating synaptic membrane exocytosis 1), Cplx1 (complexin 1), Cplx2 (complexin 2), and Nsf (N-ethylmaleimide sensitive factor, also known as vesicular fusion protein NSF). Columns indicate the group means, circles represent individual data points (n = 8 per group before outlier removal), and error bars represent ±1 standard error of the mean. An asterisk represents significance (p ≤ 0.05). Outliers were removed based on the absolute deviation from the median method. c Male Fischer 344 rats received two intrastriatal injections of 4 µg/µL α-syn PFFs, brains were removed 2-months after PFF administration and processed for fluorescent in situ hybridization (FISH). Panels show representative Syt1 FISH micrographs from the SNpc White box denotes the area of the higher magnification images, which show Syt1mRNA (red) and immunofluorescent staining for pSyn (green). White arrows denote neurons containing pSyn inclusions which show a qualitative decrease in Syt1 mRNA. Scale bars are 500 µm in the lower magnification image, and 10 µm in the higher magnification images.