Authors: | Gan, KJ; Akram, A; Blasius, TL; Ramser, EM; Budaitis, BG; Gabrych, DR; Verhey, KJ; Silverman, MA |
Year: | 2020 |
Journal: | eNeuro 7 Article Link (DOI) PubMed |
Title: | GSK3 beta Impairs KIF1A Transport in a Cellular Model of Alzheimer's Disease but Does Not Regulate Motor Motility at S402 |
Abstract: | Impairment of axonal transport is an early pathologic event that precedes neurotoxicity in Alzheimer's disease (AD). Soluble amyloid-beta oligomers (A beta Os), a causative agent of AD, activate intracellular signaling cascades that trigger phosphorylation of many target proteins, including tau, resulting in microtubule destabilization and transport impairment. Here, we investigated how KIF1A, a kinesin-3 family motor protein required for the transport of neurotrophic factors, is impaired in mouse hippocampal neurons treated with A beta Os. By live cell imaging, we observed that A beta Os inhibit transport of KIF1A-GFP similarly in wild-type and tau knock-out neurons, indicating that tau is not required for this effect. Pharmacological inhibition of glycogen synthase kinase 3 beta (GSK3 beta), a kinase overactivated in AD, prevented the transport defects. By mass spectrometry on KIF1A immunoprecipitated from transgenic AD mouse brain, we detected phosphorylation at S402, which conforms to a highly conserved GSK3 beta consensus site. We confirmed that this site is phosphorylated by GSK3 beta in vitro. Finally, we tested whether a phosphomimic of S402 could modulate KIF1A motility in control and A beta O-treated mouse neurons and in a Golgi dispersion assay devoid of endogenous KIF1A. In both systems, transport driven by mutant motors was similar to that of WT motors. In conclusion, GSK3 beta impairs KIF1A transport but does not regulate motor motility at S402. Further studies are required to determine the specific phosphorylation sites on KIF1A that regulate its cargo binding and/or motility in physiological and disease states. |
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