Amyloid-β-derived diffusible ligands cause impaired axonal transport of mitochondria in neurons

Background: Alzheimer's disease (AD) is the most prevalent form of dementia predominantly affecting the elderly. It is believed that soluble amyloid-β (Aβ) oligomers are involved in the pathogenesis of AD, yet the underlying mechanisms remain elusive. Objectives: Emerging evidence suggests that mitochondrial dysfunction likely plays a critical role in Aβ-induced neuronal degeneration. Previously, we demonstrated that Aβ-derived diffusible ligands (ADDLs) induce reduced mitochondrial density in neurites, and we suspect that an impaired mitochondrial trafficking might be involved, which is tested in this study. Methods: Using live cell imaging, anterograde and retrograde transport of mitochondria in primary hippocampal neurons treated with sub-lethal doses of ADDLs was measured. Results: We found that ADDLs induced significant impairment in both anterograde and retrograde transport of mitochondria along axons. Conclusion: These results suggest that an impaired mitochondrial transport likely contributes to ADDL-induced abnormal mitochondrial distribution and dysfunction and also reinforce the idea that axonal transport is likely involved in AD pathogenesis.