Perez Valerie A, Sanders David W, Mendoza-Oliva Ayde, Stopschinski Barbara E, Mullapudi Vishruth, White Charles L, Joachimiak Lukasz A, Diamond Marc I
Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX.
Department of Pathology, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX.
bioRxiv. 2023 Mar 16:2023.03.16.532880. doi: 10.1101/2023.03.16.532880.
Neurodegenerative tauopathies are caused by 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 ability of the J domain (JD) of DnaJC7 to bind to Hsp70, as JD mutations that block binding to Hsp70 abrogated the protective activity. Disease-associated mutations in the JD and substrate binding site of DnaJC7 also abrogated its protective activity. DnaJC7 thus specifically regulates tau aggregation in cooperation with Hsp70.
神经退行性tau蛋白病是由有毒的tau蛋白聚集体积累引起的。这似乎涉及基于模板的种子事件，即tau单体改变构象并被招募到不断增长的聚集体中。几个大的伴侣蛋白家族，包括热休克蛋白70（Hsp70）和J结构域蛋白（JDP）协同调节细胞内蛋白如tau的折叠，但协调这种活性的因素尚不清楚。JDP DnaJC7与tau结合并减少其细胞内聚集。然而，尚不清楚这是否是DnaJC7特有的，或者其他JDP是否也可能有类似作用。我们在细胞模型中使用蛋白质组学来确定DnaJC7与不溶性tau共纯化并与细胞内聚集体共定位。我们逐个敲除了每一种可能的JDP，并测试其对细胞内聚集和种子形成的影响。敲除DnaJC7会降低聚集体清除率并增加细胞内tau种子形成。这取决于DnaJC7的J结构域（JD）与Hsp70结合的能力，因为阻断与Hsp70结合的JD突变消除了其保护活性。DnaJC7的JD和底物结合位点的疾病相关突变也消除了其保护活性。因此，DnaJC7与Hsp70协同特异性调节tau聚集。
