All antibodies were incubated with tissue overnight at 4C overnight in block solution (2% FBS in 0

All antibodies were incubated with tissue overnight at 4C overnight in block solution (2% FBS in 0.1 M Tris pH 7.6). syn fibrils through the use of cryo-electron microscopy and other techniques suggests that C-terminus truncation modifications can greatly alter syn fibril structure (9C11); consequent alterations in prion-like seeding as a result of these modifications may be important in explaining strain-like diversity in fibril structure and seeding capacity isolated from LBs (12, 13). Additionally, recent works have suggested that PFFs when introduced to healthy neurons are quickly trafficked for lysosomal processing where extensive truncation of exposed C-terminal regions on the PFFs can readily occur (2, 14C16); this indicates that initial seeding events in a neuron likely involve truncated syn fibrils. Indeed, various truncated forms of human syn have been recently investigated and it has been found that seeding activity can increase or decrease depending on the specific truncation (7, 8, 15). Herein, a subset of the most common C-truncated forms of syn Fabomotizole hydrochloride (7) are investigated Fabomotizole hydrochloride with mouse syn for compatibility with NTG mouse-based models of prion-like seeding to further characterize how C-truncation affects induction of pathology. Materials and Methods Antibodies Mouse monoclonal antibody 81A (RRID: AB_2819037) is mainly specific for phosphorylated Ser129 (pSer129) syn and is a common diagnostic marker of pathologic syn (17, 18); the antibody was used at a 1:3000 dilution for immunohistochemistry. Antibody 94-3A10 (RRID: AB_2819044) is a mouse monoclonal antibody specific for an epitope located at the last 10 C-terminal amino acid of syn (residues 130-140 syn) (19, 20); the antibody was used at a 1:10,000 dilution for immunohistochemistry and 1:1000 for western blotting. SNL-4 (RRID: AB_2819043) is a rabbit polyclonal antibody raised against residues 2-12 of syn (21); the antibody was used at a 1:1000 dilution for western blotting. Expression and purification of recombinant syn proteins QuikChange site-directed mutagenesis (Agilent Technologies, Santa Clara, CA) using mutant-specific oligonucleotides was used to generate various C-terminally truncated forms of mouse syn (residues 1-115, 1-119, 1-122, 1-124, 1-125, 1-129, 1-133, and 1-135) in cDNA encoding full-length (FL) mouse syn in both the pRK172 and pcDNA3.1 (+) plasmid as previously described (22). The pRK172 DNA construct expressing N-terminal truncated 21-140 mouse -syn (with a Met codon added before amino acid 21) was generated by PCR amplification and cloning in pRK172. All recombinant forms of syn were expressed in BL21 (DE3) and purified as previously described (7). All recombinant proteins were diluted in pH 7.4 sterile phosphate buffered saline (PBS), and concentrations were determined using the bicinchoninic acid assay (Pierce, Waltham, MA). In vitro aggregation of C-truncated mouse syn and preparation of fibrils For aggregation comparisons, FL and C-truncated mouse syn proteins were diluted to 100 M in Fabomotizole hydrochloride sterile PBS (Invitrogen) and assembled into amyloid fibrils with continuous shaking at 1050 rpm, 37C, for 0, 24, 48, and 96 hours with 4 replicates per form of syn protein at each time point. Amyloid formation for each tube (= 4) was assessed by determining the fraction of insoluble syn at each timepoint (40 L of solution) as previously described (7). Insoluble syn was measured by centrifugation at 100,000 g for 30 minutes in PBS to produce a soluble supernatant and insoluble pellet fraction; SDS-PAGE was conducted to determine the fraction of insoluble syn as described previously (7). For seeding experiments, all forms of mouse syn were individually assembled into pre-formed PRKAR2 mouse syn fibrils (mPFFs) by incubation at 37C at 5 mg/ml in sterile PBS with continuous shaking at 1,050 rpm. syn fibril formation was validated with K114 fluorometry as previously described (7). When combinations of 1-135 with C-truncated forms of syn were co-fibrillized, a 1:1 molar ratio was used at a 5 mg/ml total concentration. PFFs were diluted in sterile PBS and fragmented into an array of shortened fibrils by mild water bath sonication for one hour prior to seeding in cell culture or intra-hippocampal injection (23). HEK293T cell culture and transfection HEK293T cells were maintained in Dulbeccos Modified Eagles Medium (DMEM, Invitrogen, Carlsbad, CA) containing 2 mM L-glutamine, 10% fetal bovine serum (FBS), 100 U/ml penicillin, and 100 g/ml streptomycin, at 37C and 5% CO2. Cells were plated into 4 cm2 wells, and allowed to reach ~30% confluency; cells were transfected using a modified.