Investigating how changes in the levels of kinesins impact neuronal health in <i>Drosophila</i> and human iPSC-derived neurons AD model

Alzheimer's disease (AD) is the leading cause of dementia and the most common neurodegenerative disorder. Understanding the molecular pathology of AD may help identify new ways to reduce neuronal damage. In the past decades, Drosophila has become a powerful tool in modelling mechanisms underlying human diseases. Here, we investigate how the expression of the human 42-residue β-amyloid (Aβ) carrying the E22G pathogenic 'Arctic' mutation (Aβ42Arc) affects axonal health and behaviour in Drosophila. We find that Aβ42Arc flies present aberrant neurons, with altered axonal transport of mitochondria and aberrant terminal boutons at neuromuscular junctions. We demonstrate that the motor proteins kinesin-1 and kinesin-3 are essential for the correct development of neurons in Drosophila larvae and in human induced pluripotent stem cell-derived cortical neurons. We then show that the overexpression of kinesin-1 or kinesin-3 restores the correct number and morphology of boutons in Aβ42Arc-expressing neurons and rescues neuronal function measured by negative geotaxis locomotor behavioural assay. We therefore provide new evidence towards understanding the mechanisms of axonal transport defects in AD, and our results support the idea that kinesins should be considered as potential drug targets to help reduce dementia-associated disorders.