The Inhibition Effect Of Dauricine On A?_1-42 Toxicity And Its Mechanism

Objective:To explore the effects of dauricine in cell and Caenorhabditis elegans models of Alzheimer's disease?AD?and its possible mechanism,and to explore the molecular mechanism of reducing A?_1-42neurotoxicity.Method:The APPsw cells that stably transfected the Swedish mutant form of human beta-amyloid precursor protein?APPsw?into the SH-SY5 Y cell as a Alzheimer's disease model,which was treated with dauricine solution of concentration?0.1,1,6.4,64?M?respectively,then CCK8 assay was applied to detect cell viabilities.A?_1-42secretion level was tested by ELISA assay.The A?_1-42-transgenic C.elegans strain CL2120 and wild type strain CL2122 were randomly assigned as control group and dauricine administrated groups?0.1,1,6.4?M?,then observed the effect of drug on nematode paralysis.Western blot was used to detect A?_1-42protein expression in worm CL2120.The levels of protein homeostasis associated gene expression in worm CL2120 were assayed by Quantitative RT-PCR and calculated by the 2^-??Ctmethod.RT-PCR was applied to verify whether the endoplasmic reticulum?ER?stress factor xbp-1 is activated.Fluorescence photography is used in transgenic C.elegans strain OP506 with xbp-1::EGFP to test the effect of dairicine on xbp-1 expression in protein level.Xbp-1 was knocked down by RNA interference,then further detected the paralysis rate and the protein level expression of A?_1-42to verify whether xbp-1 is the target factor for dauricine.Quantitative RT-PCR and western blot were also applied to analyze the effect of dauricine on ire-1/xbp-1arm of the unfolded protein response?UPR?in endoplasmic reticulum stress.Results:Through this study,we evaluated the anti-AD activity and ability of dauricine and explored the possible mechanisms.Results showed that dauricine can significantly reduce the secretion of A?_1-42in APPsw cells.Otherwise,we also found that the dauricine can delay the paralysis and lower the level of A?oligomeric protein in the A?_1-42-transgenic worm CL2120.We further found that xbp-1,the key factor in the ire-1 pathway of UPR,was activated and ER-associated protein degradation?ERAD?was enhanced by dauricine,interestingly,down-regulation of xbp-1 could counteract the positive effects of dauricine on paralysis and A?oligomers expression.Conclusions:?1?Dauricine has the pharmacological value of reducing A?_1-42 aggregation and preventing the progression of AD.?2?Dauricine reduced A?_1-42 aggregation and toxicity,which might be related with activing ire-1/xbp-1 pathway of UPR and enhancing endoplasmic reticulum associated degradation.?3?XBP-1S played a vital role in regulating the A?toxicity and delaying the progression of AD,which possibly become as a potential target for the development of AD drugs.