Cytoplasmic expression of trans-active response DNA-binding protein-43 in aged mice display hippocampal sclerosis-like degeneration and neuronal loss with reduced lifespan.

Trans-active response DNA-binding protein-43 (TDP-43) is the major pathological protein in motor neuron disease and TDP-43 pathology has been described in the brains of up to 50% of patients with Alzheimer disease (AD). Hippocampal sclerosis of aging (HS-A), an age-related neuropathology characterized by severe neuronal loss and gliosis in CA1 and/or subiculum, is found in ∼80% of cases that are positive for phosphorylated TDP-43. HS-A is seen as a co-pathology in cases with AD, limbic-predominant age-related TDP-43 encephalopathy neuropathologic changes (LATE-NC), and frontotemporal degeneration. To understand the pathogenetic relationships between HS-A and LATE-NC, mice that selectively express human TDP-43 and TDP-43 with a defective nuclear localization signal (ΔNLS) in the hippocampus, alone or in an APP/PSEN1 background, were evaluated using histology, HALO software's object recognition algorithms, and protein expression assays. Twenty-four-month-old mice expressing cytosolic TDP-43 displayed marked neuronal loss and atrophy in the hippocampus, decreased β-amyloid plaque deposition and modulation of microglia and intermediate filament activation. TDP-43ΔNLS-expressing mice survived to only ∼24 months of age whether or not they had an APP/PSEN1 background. This HS-A-like model may provide insights into the pathogenesis of neurodegeneration seen in HS-A and in other TDP-43 proteinopathies.