title: Cilostazol Upregulates Autophagy via SIRT1 Activation: Reducing Amyloid-β Peptide and APP-CTFβ Levels in Neuronal Cells.
abstract: Autophagy is a vital pathway for the removal of β-amyloid peptide (Aβ) and the aggregated proteins that cause Alzheimer's disease (AD). We previously found that cilostazol induced SIRT1 expression and its activity in neuronal cells, and thus, we hypothesized that cilostazol might stimulate clearances of Aβ and C-terminal APP fragment β subunit (APP-CTFβ) by up-regulating autophagy.When N2a cells were exposed to soluble Aβ1-42, protein levels of beclin-1, autophagy-related protein5 (Atg5), and SIRT1 decreased significantly. Pretreatment with cilostazol (10-30 μM) or resveratrol (20 μM) prevented these Aβ1-42 evoked suppressions. LC3-II (a marker of mammalian autophagy) levels were significantly increased by cilostazol, and this increase was reduced by 3-methyladenine. To evoke endogenous Aβ overproduction, N2aSwe cells (N2a cells stably expressing human APP containing the Swedish mutation) were cultured in medium with or without tetracycline (Tet+ for 48 h and then placed in Tet- condition). Aβ and APP-CTFβ expressions were increased after 12~24 h in Tet- condition, and these increased expressions were significantly reduced by pretreating cilostazol. Cilostazol-induced reductions in the expressions of Aβ and APP-CTFβ were blocked by bafilomycin A1 (a blocker of autophagosome to lysosome fusion). After knockdown of the SIRT1 gene (to ~40% in SIRT1 protein), cilostazol failed to elevate the expressions of beclin-1, Atg5, and LC3-II, indicating that cilostazol increases these expressions by up-regulating SIRT1. Further, decreased cell viability induced by Aβ was prevented by cilostazol, and this inhibition was reversed by 3-methyladenine, indicating that the protective effect of cilostazol against Aβ induced neurotoxicity is, in part, ascribable to the induction of autophagy. In conclusion, cilostazol modulates autophagy by increasing the activation of SIRT1, and thereby enhances Aβ clearance and increases cell viability.
authors.affiliation: Gene & Cell Therapy Research Center for Vessel-associated Diseases, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Hye Rin
authors.initials: HR
authors.lastname: Lee
authors.affiliation: Division of Meridian and Structural Medicine, School of Korean Medicine, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Hwa Kyoung
authors.initials: HK
authors.lastname: Shin
authors.affiliation: Gene & Cell Therapy Research Center for Vessel-associated Diseases, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: So Youn
authors.initials: SY
authors.lastname: Park
authors.affiliation: Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Hye Young
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Department of Pharmacology, School of Medicine, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Gene & Cell Therapy Research Center for Vessel-associated Diseases, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Sun Sik
authors.initials: SS
authors.lastname: Bae
authors.affiliation: Department of Pharmacology, School of Medicine, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Won Suk
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Department of Pharmacology, School of Medicine, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Byung Yong
authors.initials: BY
authors.lastname: Rhim
authors.affiliation: Gene & Cell Therapy Research Center for Vessel-associated Diseases, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Ki Whan
authors.initials: KW
authors.lastname: Hong
authors.affiliation: Department of Pharmacology, School of Medicine, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Gene & Cell Therapy Research Center for Vessel-associated Diseases, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea; Medical Research Center for Ischemic Tissue Regeneration, Pusan National University, Yangsan-si, Gyeongsangnam-do, Republic of Korea.
authors.forename: Chi Dae
authors.initials: CD
authors.lastname: Kim
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism / Q000494:pharmacology; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000077407:Cilostazol; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology*; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D051017:Apoptosis Regulatory Proteins; C495773:Atg5 protein, mouse; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; C115010:Becn1 protein, mouse; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D013777:Tetrazoles; C075222:amyloid beta-protein (1-42); C470545:Sirt1 protein, mouse; D056564:Sirtuin 1; D000077407:Cilostazol