Lysosomal dysfunction in neurodegenerative disease

Examination of genetic risk factors associated with neurodegenerative diseases has provided important mechanistic insights into the pathophysiology of these disorders, and it has implicated defects in lysosomal function as a key component of the neurodegenerative process. The lysosome has a primary role in mediating degradation of both intracellular contents and endocytosed material from the extracellular space. Aggregation of misfolded proteins is a pathological mechanism that is observed across neurodegenerative disorders, and aberrant lysosomal degradation of such proteins plays a pivotal part in driving neuronal dysfunction and cell loss. In addition to the crucial role of the endolysosomal system in degradation of intracellular constituents, lysosomes also serve as important nodes for intracellular signalling, participating in nutrient sensing, lipid metabolism, membrane repair and neuroinflammation. In this Review, we provide an overview of mechanisms of lysosomal dysfunction in neurodegenerative disease, with a particular focus on Parkinson disease, Alzheimer disease, frontotemporal dementia and amyotrophic lateral sclerosis.