title: Esterification of 24S-OHC induces formation of atypical lipid droplet-like structures, leading to neuronal cell death.
abstract: The 24(S)-hydroxycholesterol (24S-OHC), which plays an important role in maintaining brain cholesterol homeostasis, has been shown to possess neurotoxicity. We have previously reported that 24S-OHC esterification by ACAT1 and the resulting lipid droplet (LD) formation are responsible for 24S-OHC-induced cell death. In the present study, we investigate the functional roles of 24S-OHC esters and LD formation in 24S-OHC-induced cell death, and we identify four long-chain unsaturated fatty acids (oleic acid, linoleic acid, arachidonic acid, and DHA) with which 24S-OHC is esterified in human neuroblastoma SH-SY5Y cells treated with 24S-OHC. Here, we find that cotreatment of cells with 24S-OHC and each of these four unsaturated fatty acids increases prevalence of the corresponding 24S-OHC ester and exacerbates induction of cell death as compared with cell death induced by treatment with 24S-OHC alone. Using electron microscopy, we find in the present study that 24S-OHC induces formation of LD-like structures coupled with enlarged endoplasmic reticulum (ER) lumina, and that these effects are suppressed by treatment with ACAT inhibitor. Collectively, these results illustrate that ACAT1-catalyzed esterification of 24S-OHC with long-chain unsaturated fatty acid followed by formation of atypical LD-like structures at the ER membrane is a critical requirement for 24S-OHC-induced cell death.
authors.affiliation: Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan.
authors.forename: Wakako
authors.initials: W
authors.lastname: Takabe
authors.affiliation: Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan yurano@mail.doshisha.ac.jp nnoguchi@mail.doshisha.ac.jp.
authors.forename: Yasuomi
authors.initials: Y
authors.lastname: Urano
authors.affiliation: Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan.
authors.forename: Diep-Khanh Ho
authors.initials: DH
authors.lastname: Vo
authors.affiliation: Tokyo New Drug Research Laboratories, Pharmaceutical Division, Kowa Company, Ltd., Tokyo 189-0022, Japan.
authors.forename: Kimiyuki
authors.initials: K
authors.lastname: Shibuya
authors.affiliation: Department of Molecular Chemistry and Biochemistry, Faculty of Sciences and Technology, Doshisha University, Kyoto 610-0394, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanno
authors.affiliation: Department of Molecular Chemistry and Biochemistry, Faculty of Sciences and Technology, Doshisha University, Kyoto 610-0394, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kitagishi
authors.affiliation: Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
authors.forename: Toyoshi
authors.initials: T
authors.lastname: Fujimoto
authors.affiliation: Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394, Japan yurano@mail.doshisha.ac.jp nnoguchi@mail.doshisha.ac.jp.
authors.forename: Noriko
authors.initials: N
authors.lastname: Noguchi
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics*; D016718:Arachidonic Acid / Q000008:administration & dosage / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004951:Esterification / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006888:Hydroxycholesterols / Q000008:administration & dosage* / Q000378:metabolism; D019787:Linoleic Acid / Q000008:administration & dosage / Q000378:metabolism; D066292:Lipid Droplets / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D019301:Oleic Acid / Q000008:administration & dosage / Q000378:metabolism
chemical_list: D006888:Hydroxycholesterols; D016718:Arachidonic Acid; D019301:Oleic Acid; D019787:Linoleic Acid; C506639:ACAT1 protein, human; D000101:Acetyl-CoA C-Acetyltransferase
keywords: 24(S)-hydroxycholesterol; Alzheimer’s disease; acyl-CoA:cholesterol acyltransferase; electron microscopy; mass spectrometry; oxysterols