KIF9 Ameliorates Neuropathology and Cognitive Dysfunction by Promoting Macroautophagy in a Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder affecting the elderly. The imbalance of protein production and degradation processes leads to the accumulation of misfolded and abnormally aggregated amyloid-beta (Aβ) in the extracellular space and forms senile plaques, which constitute one of the most critical pathological hallmarks of AD. KIF9, a member of the kinesin protein superfamily, mediates the anterograde transport of intracellular cargo along microtubules. However, the exact role of KIF9 in AD pathogenesis remains largely elusive. In this study, we reported that the expression of kinesin family member 9 (KIF9) in the hippocampus of APP23/PS45 double-transgenic AD model mice declined in an age-dependent manner, concurrent with macroautophagy dysfunction. Furthermore, we found that KIF9 mediated the transport of lysosomes through kinesin light chain 1 (KLC1), thereby participating in the degradation of amyloidogenic pathway-related proteins of Aβ precursor protein (APP) in AD model cells through promoting the macroautophagy pathway. Importantly, genetic upregulation of KIF9 via adeno-associated virus (AAV) diminished Aβ deposition and alleviated cognitive impairments in AD model mice by enhancing macroautophagy function. Collectively, our findings underscore the ability of KIF9 to promote macroautophagy through KLC1-mediated anterograde transport of lysosomes, effectively ameliorating cognitive dysfunction in AD model mice. These discoveries suggest that KIF9 may represent a novel therapeutic target for the treatment of AD.