title: Necroptosis-like Neuronal Cell Death Caused by Cellular Cholesterol Accumulation.
abstract: Aberrant cellular accumulation of cholesterol is associated with neuronal lysosomal storage disorders such as Niemann-Pick disease Type C (NPC). We have shown previously that l-norephedrine (l-Nor), a sympathomimetic amine, induces necrotic cell death associated with massive cytoplasmic vacuolation in SH-SY5Y human neuroblastoma cells. To reveal the molecular mechanism underling necrotic neuronal cell death caused by l-Nor, we examined alterations in the gene expression profile of cells during l-Nor exposure. DNA microarray analysis revealed that the gene levels for cholesterol transport (LDL receptor and NPC2) as well as cholesterol biosynthesis (mevalonate pathway enzymes) are increased after exposure to 3 mm l-Nor for ∼6 h. Concomitant with this observation, the master transcriptional regulator of cholesterol homeostasis, SREBP-2, is activated by l-Nor. The increase in cholesterol uptake as well as biosynthesis is not accompanied by an increase in cholesterol in the plasma membrane, but rather by aberrant accumulation in cytoplasmic compartments. We also found that cell death by l-Nor can be suppressed by nec-1s, an inhibitor of a regulated form of necrosis, necroptosis. Abrogation of SREBP-2 activation by the small molecule inhibitor betulin or by overexpression of dominant-negative SREBP-2 efficiently reduces cell death by l-Nor. The mobilization of cellular cholesterol in the presence of cyclodextrin also suppresses cell death. These results were also observed in primary culture of striatum neurons. Taken together, our results indicate that the excessive uptake as well as synthesis of cholesterol should underlie neuronal cell death by l-Nor exposure, and suggest a possible link between lysosomal cholesterol storage disorders and the regulated form of necrosis in neuronal cells.
authors.affiliation: From the Department of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Funakoshi
authors.affiliation: From the Department of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan aki.legm@tmd.ac.jp.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Aki
authors.affiliation: From the Department of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Tajiri
authors.affiliation: From the Department of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Unuma
authors.affiliation: From the Department of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Uemura
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D052556:Niemann-Pick Disease, Type C / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010665:Phenylpropanolamine / Q000494:pharmacology; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism*; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; C104585:NPC2 protein, human; D011973:Receptors, LDL; C497390:SREBF2 protein, human; D051782:Sterol Regulatory Element Binding Protein 2; D033921:Vesicular Transport Proteins; D010665:Phenylpropanolamine; D002784:Cholesterol
keywords: DNA microarray; SREBP-2; cell death; cholesterol; necroptosis; neuroblastoma; norephedrine; toxicology; transcription regulation