title: Aβ peptide secretion is reduced by Radix Polygalae-induced autophagy via activation of the AMPK/mTOR pathway.
abstract: Radix Polygalae is a traditional Chinese medicine that has been used as a sedative and to improve memory for a number of years. The impact of Radix Polygalae in patients with Alzheimer's disease has been investigated. However the mechanisms underlying its effects remain unclear. In the current study, the toxicity of various doses (100, 40, 20, 10, 5 and 0 μg/ml) of Radix Polygalae was measured in the human neuroblastoma cell line (SH-SY5Y) using an MTT assay. Changes in amyloid β (Aβ) levels in the supernatant of Chinese hamster ovary (CHO) cells overexpressing β-amyloid pro-protein (APP) and BACE1 (CHO-APP/BACE1), were detected using an ELISA assay. In order to confirm that the Aβ reduction was associated with autophagy, the autophagy marker protein, light chain 3 (LC3), was measured by western blot analysis and autophagosomes were assessed using MDC staining. In addition, the mechanism underlying the autophagy induced by Radix Polygalae was analyzed using western blotting to measure the protein expression of mammalian target of rapamycin (mTOR), p70s6k, Raptor, protein kinase B and adenosine monophosphate-activated protein kinase (AMPK), in addition to the phosphorylated forms of these proteins. The results demonstrated no significant toxicity of Radix Polygalae in SH-SY5Y cells, at a dose of 100 μg/ml. The secretion of Aβ was markedly reduced following treatment with Radix Polygalae, and this reduction occurred in a dose-dependent manner. The autophagy levels were shown to be enhanced in the drug treatment group, using fluorescence microscopy. In addition, levels of LC3II/LC3I, the marker protein of autophagy, were also increased. The results of the current study suggest that Radix Polygalae may aid in the elimination of the Aβ peptide, via the induction of autophagy, by the AMPK/mTOR signaling pathway. These results may provide a basis for further kin vivo investigation.
authors.affiliation: Department of Histology and Embryology, Anhui Medical University, Hefei, Anhui 230032, P.R. China.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Laboratorial Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200071, P.R. China.
authors.forename: Zhi-Cheng
authors.initials: ZC
authors.lastname: Wang
authors.affiliation: Shanghai Genhouse Technology Co., Ltd., Shanghai 201203, P.R. China.
authors.forename: Kui-Feng
authors.initials: KF
authors.lastname: Wang
authors.affiliation: Department of Histology and Embryology, Anhui Medical University, Hefei, Anhui 230032, P.R. China.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Chen
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D006801:Humans; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D016229:Amyloid beta-Peptides; D004365:Drugs, Chinese Herbal; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C000592340:yuan zhi; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases