[Intracellular seeded aggregation of TDP-43]

TAR-DNA binding protein of 43kDa(TDP-43) is the component protein of inclusions in brains of patients with frontotemporal lobar degeneration (FTLD-TDP) and amyotrophic lateral sclerosis (ALS). Here we report a seed-dependent TDP-43 aggregation model using SH-SY5Y cells into which detergent-insoluble TDP-43 from diseased brains is introduced to provide seeds for aggregation. When these seeds were introduced into cells expressing HA-tagged TDP-43, round aggregates composed of phosphorylated and ubiquitinated HA-tagged TDP-43 were formed. Biochemical fractionation revealed the presence of Sarkosyl-insoluble phosphorylated full-length TDP-43 as well as its C-terminal fragments. Cells bearing TDP-43 inclusions exhibited increased levels of cell death and proteasome dysfunction. This seeding model reproduces characteristic features of affected neurons in brains with TDP-43 proteinopathy.