DnaJC7 specifically regulates tau seeding

Neurodegenerative tauopathies are caused by the accumulation of toxic tau protein assemblies. This appears to involve template-based seeding events, whereby tau monomer changes conformation and is recruited to a growing aggregate. Several large families of chaperone proteins, including Hsp70s and J domain proteins (JDPs), cooperate to regulate the folding of intracellular proteins such as tau, but the factors that coordinate this activity are not well known. The JDP DnaJC7 binds tau and reduces its intracellular aggregation. However, it is unknown whether this is specific to DnaJC7 or if other JDPs might be similarly involved. We used proteomics within a cell model to determine that DnaJC7 co-purified with insoluble tau and colocalized with intracellular aggregates. We individually knocked out every possible JDP and tested the effect on intracellular aggregation and seeding. DnaJC7 knockout decreased aggregate clearance and increased intracellular tau seeding. This depended on the abili..., Identification of aggresome-associated proteins by mass spectrometry DS1 and DS10 cells were grown to confluency in two T300s per condition. Cells were harvested, pelleted, and washed prior to storage as 4x0.5 T300 pellets at -80°C. For each condition, three pellets were thawed on ice, and each was lysed by trituration in 1 mL ice-cold PBS with 0.25% Triton-X containing cOmplete™ mini EDTA-free protease inhibitor cocktail tablet (Roche) at a concentration of 10% w/vol, followed by a 15-minute incubation on ice. Aggresomes and nuclei were collected by centrifuging at 1000xg for 15 minutes, followed by resuspension in 400 μL lysis buffer. An Omni-Ruptor 250 probe sonicator was then used at 30% power for thirty 3-second pulses to partially dissolve the pellets. Samples were centrifuged at 250xg for 5 minutes, and the supernatant was set aside as Fraction B. Pellets were re-homogenized in an additional 400 μL lysis buffer, and sonication and centrifugation was repeated. The final supernatan..., , , # Data from: DnaJC7 specifically regulates tau seeding ## Description of the data and file structure **File: Source_Data_1_DS1_vs_DS10_proteomics.xlsx** Source Data 1 contains an Excel spreadsheet with the processed results of our mass spectrometry analysis, identifying proteins found in the sarkosyl-insoluble fraction of DS1 and DS10 cells. The dataset contains spreadsheets containing the raw and processed data for both the DS1 and DS10 cell lines, and a sheet with proteins that were only identified in the DS10 cell line. Spectral counts/indices for proteins that were not detected in a specific cell line/replicate are listed as “null” in the dataset. The raw mzxml data file is unfortunately not available due to a data storage issue that occurred after data collection. **File: Source_Data_2_GO_AllLists.csv** Source Data 2 contains a CSV file with the results of the Metascape analysis identifying the Gene Ontology (GO) and other pathway terms enriched in our DS1 vs DS10 datasets....,