Abstract
Background: Alternative splicing of amyloid precursor protein(APP) exon 7 generates the isoforms containing a Kunitz protease inhibitor (KPI) domain. APP-KPI levels in the brain are correlated with amyloid beta(Aβ) production. This study aimed to investigate the effect of tetrahydroxystilbene glucoside (TSG) on APP KPI inclusion in Alzheimer's disease (AD).
Methods: APP minigene comprising exon 7 and its flanking exons and introns was successfully generated by using the polymerase chain reaction (PCR). The splicing products of APP minigene or endogenous APP were detected using reverse transcription-PCR. In addition, the effect of TSG, LY294002 on the AKT-GSK3β pathway was determined by western blot and PCR. Co-immunoprecipitation and immunofluorescence were used to detect the interaction between glycogen synthase kinase-3β, GSK3β) and alternative splicing factor (ASF). TSG was intragastrically administered to 5-month-old APP/PS1 transgenic mice for 12 months. The brain tissue was subjected to biochemical evaluation.
Results: We found that GSK3β increased APP-KPI inclusion level, and promoted the inclusion of APP-KPI by interacting with ASF. TSG activated the AKT-GSK3β signaling pathway, and suppressed the activity of GSK3β in cultured cells and APP/PS1 mouse brain. Moreover, TSG treatment attenuated Aβ deposition in the brains of APP/PS1 mice.
Conclusions: This study demonstrates the neuroprotective effect of TSG on APP expression pattern, suggesting that TSG may be beneficial for AD prevention and treatment.
