Cathepsin D in a Murine Model of Frontotemporal Dementia with Parkinsonism-Linked to Chromosome 17

Tauopathies, such as Alzheimer's disease (AD) and Frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17), are characterized by tau accumulation. This accumulation could result from alterations in tau degradation by either the ubiquitin-proteasome system or the autophagy–lysosomal pathway. To analyze a possible alteration of the autophagy–lysosomal pathway in transgenic mice expressing human tau with three FTDP-17 missense mutations (Tau^VLW mice), we studied the lysosomal enzyme Cathepsin D. The hippocampi of Tau^VLW mice, where the human mutant tau accumulates, showed both increased Cathepsin D and partial colocalization of Cathepsin D with human mutant tau. At the ultrastructural level, some multivesicular bodies showed human mutant tau-immunopositive vesicles. This finding could provide insights into the molecular mechanisms of tau degradation in human tauopathies.