Cyclopamine Modulates Gamma-Secretase Mediated Cleavage of Amyloid Precursor Protein by Altering its Subcellular Trafficking and Lysosomal Degradation [Cell Biology]

October 3rd, 2014 by Vorobyeva, A. G., Lee, R., Miller, S., Longen, C., Sharoni, M., Khandelwal, P. J., Kim, F. J., Marenda, D. R., Saunders, A. J.

Alzheimer's disease (AD) is a progressive neurodegenerative disease leading to memory loss. Numerous lines of evidence suggest that Aβ, a neurotoxic peptide, initiates a cascade that results in synaptic dysfunction, neuronal death and eventually cognitive deficits. Aβ is generated by the proteolytic processing of the amyloid precursor protein (APP) and alterations to this processing can result in AD. Using in vitro and in vivo models we identified cyclopamine as a novel regulator of γ-secretase mediated cleavage of APP. We demonstrate that cyclopamine decreases Aβ generation by altering APP retrograde trafficking. Specifically, cyclopamine treatment reduced APP-CTF delivery to the trans-Golgi network where γ-secretase cleavage occurs. Instead cyclopamine redirects APP-CTFs to the lysosome. These data demonstrate that cyclopamine treatment decreases γ-secretase mediated cleavage of APP. In addition, cyclopamine treatment decreases the rate of APP-CTF degradation. Together, our data demonstrate that cyclopamine alters APP processing and Aβ generation by inducing changes in APP subcellular trafficking and APP-CTF degradation.
  • Posted in Journal of Biological Chemistry, Publications
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