Correlative cryo-soft X-ray tomography and cryo-structured illumination microscopy reveal changes to lysosomes in amyloid-β-treated neurons

Protein misfolding is common to neurodegenerative diseases (NDs) including Alzheimer’s disease (AD), which is partly characterized by the self-assembly and accumulation of amyloid-beta in the brain. Lysosomes are a critical component of the proteostasis network required to degrade and recycle material from outside and within the cell and impaired proteostatic mechanisms have been implicated in NDs. We have previously established that toxic amyloid-beta oligomers are endocytosed, accumulate in lysosomes, and disrupt the endo-lysosomal system in neurons. Here, we use pioneering correlative cryo-structured illumination microscopy and cryo-soft X-ray tomography imaging techniques to reconstruct 3D cellular architecture in the native state revealing reduced X-ray density in lysosomes and increased carbon dense vesicles in oligomer treated neurons compared with untreated cells. This work provides unprecedented visual information on the changes to neuronal lysosomes inflicted by amyloid beta oligomers using advanced methods in structural cell biology. [Display omitted] •3D reconstructions of primary hippocampal neurons by correlative cryo-SXT and cryo-SIM•Lysosomes in neurons incubated with Aβ oligomers show decreased carbon density•Lysosomes containing Aβ oligomers are enlarged•Alterations to neuronal ultrastructure may represent abnormal lysosome function Lysosomes perform critical roles in cells and their dysfunction has been associated with neurodegenerative diseases. Here, Marshall et al. use correlative X-ray and fluorescence imaging to identify lysosomes in a neuronal model for Alzheimer’s disease, revealing ultrastructural changes that may have implications for the toxic effects of misfolded proteins.