Atlas stumbled: Kinesin light chain-1 variant E triggers a vicious cycle of axonal transport disruption and amyloid-β generation in Alzheimer's disease

Substantial evidence implicates fast axonal transport (FAT) defects in neurodegeneration. In Alzheimer's disease (AD), it is controversial whether transport defects cause or arise from amyloid-beta (A beta)-induced toxicity. Using a novel, unbiased genetic screen, Morihara et al. identified kinesin light chain-1 splice variant E (KLC1vE) as a modifier of A beta accumulation. Here, we propose three mechanisms to explain this causal role. First, KLC1vE reduces APP transport, leading to A beta accumulation. Second, reduced transport of APP by KLC1vE triggers an ER stress response that activates the amyloidogenic pathway. Third, KLC1vE impairs transport of other KLC1 cargos that regulate amyloidogenesis, promoting Ab retention within the secretory pathway. Collectively, KLC1vE perpetuates a vicious cycle of A beta generation, kinase dysregulation, and global FAT impairment that inevitably leads to cellular toxicity. These concepts implicate alternative splicing of KLC1 in AD and suggest that the reciprocal influence of transport mechanisms on disease states contributes to neurodegeneration.