title: Trichostatin A epigenetically increases calpastatin expression and inhibits calpain activity and calcium-induced SH-SY5Y neuronal cell toxicity.
abstract: Calpains are involved in calcium-induced neuronal cell toxicity, which is associated with the pathophysiology of Alzheimer's disease (AD). The activity of calpains is regulated by the inhibitor calpastatin, and increased activity of calpains and decreased calpastastin are often found in AD. Histone deacetylase (HDAC) inhibitors are implicated in AD treatment through the improvement of learning and memory but the underlying mechanism is yet to be understood. Here, using SH-SY5Y neuroblastoma cells and a calcium ionophore ionomycin, we examined whether and how HDAC inhibitor trichostatin A (TSA) inhibits calcium-induced neuronal cell death. TSA increased both the mRNA and protein levels of calpastatin, with no alterations in those of calpain 1 and calpain 2. Furthermore, TSA-stimulated increase of calpastatin was accompanied by a significant attenuation of ionomycin-induced autolysis of calpain 1, but not of calpain 2, and calpain-dependent 150 kDa αII spectrin cleavage. Under these conditions, however, caspase activity was unaltered. Moreover, ectopic expression of small interfering RNA of calpastatin reversed the inhibitory effect of TSA on ionomycin-induced calpain 1 autolysis and αII spectrin cleavage. Chromatin immunoprecipitation assay revealed the increased levels of acetylation at lysine 5 of histone H4 (H4K5-Ac), H3K9-Ac and H3K14-Ac within the calpastatin promoter region in TSA-treated cells relative to control cells. Finally, TSA significantly decreased ionomycin-induced cell toxicity. This study demonstrates that TSA attenuates calcium-induced neuronal cell death by the inhibition of calpain activity which is mediated in part by increased calpastatin expression via histone hyperacetylation within the calpastatin promoter region. Our study provides a novel mechanism for the neuroprotective effect of HDAC inhibitors on AD.
authors.affiliation: Department of Molecular Medicine, Ewha Womans University Medical School, Seoul, South Korea; Institute of Pharmaceutical Research and Development, College of Pharmacy, Wonkwang University, Iksan, South Korea.
authors.forename: Jungwon
authors.initials: J
authors.lastname: Seo
authors.forename: Sangmee Ahn
authors.initials: SA
authors.lastname: Jo
authors.forename: Soojin
authors.initials: S
authors.lastname: Hwang
authors.forename: Catherine Jeonghae
authors.initials: CJ
authors.lastname: Byun
authors.forename: Hyeon-Ju
authors.initials: HJ
authors.lastname: Lee
authors.forename: Du-Hyong
authors.initials: DH
authors.lastname: Cho
authors.forename: Dueon
authors.initials: D
authors.lastname: Kim
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Koh
authors.forename: Inho
authors.initials: I
authors.lastname: Jo
mesh_terms: D000107:Acetylation / Q000187:drug effects; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D002154:Calpain / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D057890:Epigenomics; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D008156:Luciferases / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D002135:Calcium-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C012589:trichostatin A; D015759:Ionomycin; C033668:calpastatin; D008156:Luciferases; D002154:Calpain; D002118:Calcium
keywords: Alzheimer's disease; calpain; calpastatin; histone acetylation; neurotoxicity; trichostatin A