title: Pharmacological activation of Sirt1 ameliorates polyglutamine-induced toxicity through the regulation of autophagy.
abstract: Intracellular accumulation of polyglutamine (polyQ)-expanded Huntingtin (Htt) protein is a hallmark of Huntington's disease (HD). This study evaluated whether activation of Sirt1 by the anti-cancer agent, β-lapachone (β-lap), induces autophagy in human neuroblastoma SH-SY5Y cells, thereby reducing intracellular levels of polyQ aggregates and their concomitant cytotoxicity. Treatment of cells with β-lap markedly diminished the cytotoxicity induced by forced expression of Htt exon 1 containing a pathogenic polyQ stretch fused to green fluorescent protein (HttEx1(97Q)-GFP). β-lap increased autophagy in SH-SY5Y cells, as evidenced by the increased formation of LC3-II and autolysosomes. Furthermore, β-lap reduced HttEx1(97Q)-GFP aggregation, which was significantly prevented by co-incubation with 3-methyladenine, an inhibitor of autophagy. β-lap increased Sirt1 activity, as shown by the increased deacetylation of the Sirt1 substrates, PARP-1 and Atg5, and the nuclear translocation of FOXO1. Both the induction of autophagy and attenuation of HttEx1(97Q)-GFP aggregation by β-lap were significantly prevented by co-incubation with sirtinol, a general sirtuin inhibitor or by co-transfection with shRNA against Sirt1. The pro-autophagic actions of β-lap were further investigated in a transgenic Caenorhabditis elegans (C. elegans) line that expressed Q67 fused to cyanine fluorescent protein (Q67). Notably, β-lap reduced the number of Q67 puncta and restored Q67-induced defects in motility, which were largely prevented by pre-treatment with RNAi against sir-2.1, the C. elegans orthologue of Sirt1. Collectively, these data suggest that β-lap induces autophagy through activation of Sirt1, which in turn leads to a reduction in polyQ aggregation and cellular toxicity. Thus, β-lap provides a novel therapeutic opportunity for the treatment of HD.
authors.affiliation: Global Research Laboratory, Gwangju Institute of Science and Technology-GIST, Gwangju, Korea.
authors.forename: Bae Hyun
authors.initials: BH
authors.lastname: Shin
authors.forename: Yunki
authors.initials: Y
authors.lastname: Lim
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Oh
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Park
authors.forename: Sun-Kyung
authors.initials: SK
authors.lastname: Lee
authors.forename: Joohong
authors.initials: J
authors.lastname: Ahnn
authors.forename: Do Han
authors.initials: DH
authors.lastname: Kim
authors.forename: Woo Keun
authors.initials: WK
authors.lastname: Song
authors.forename: Tae Hwan
authors.initials: TH
authors.lastname: Kwak
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Park
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000071058:Huntingtin Protein; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D008856:Microscopy, Fluorescence; D009285:Naphthoquinones / Q000494:pharmacology*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009285:Naphthoquinones; D009419:Nerve Tissue Proteins; D010455:Peptides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018894:Reverse Transcriptase Inhibitors; D049452:Green Fluorescent Proteins; C097188:polyglutamine; C025946:3-methyladenine; C014638:beta-lapachone; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D000225:Adenine