title: Preconditioning stimuli induce autophagy via sphingosine kinase 2 in mouse cortical neurons.
abstract: Sphingosine kinase 2 (SPK2) and autophagy are both involved in brain preconditioning, but whether preconditioning-induced SPK2 up-regulation and autophagy activation are linked mechanistically remains to be elucidated. In this study, we used in vitro and in vivo models to explore the role of SPK2-mediated autophagy in isoflurane and hypoxic preconditioning. In primary mouse cortical neurons, both isoflurane and hypoxic preconditioning induced autophagy. Isoflurane and hypoxic preconditioning protected against subsequent oxygen glucose deprivation or glutamate injury, whereas pretreatment with autophagy inhibitors (3-methyladenine or KU55933) abolished preconditioning-induced tolerance. Pretreatment with SPK2 inhibitors (ABC294640 and SKI-II) or SPK2 knockdown prevented preconditioning-induced autophagy. Isoflurane also induced autophagy in mouse in vivo as shown by Western blots for LC3 and p62, LC3 immunostaining, and electron microscopy. Isoflurane-induced autophagy in mice lacking the SPK1 isoform (SPK1(-/-)), but not in SPK2(-/-)mice. Sphingosine 1-phosphate and the sphingosine 1-phosphate receptor agonist FTY720 did not protect against oxygen glucose deprivation in cultured neurons and did not alter the expression of LC3 and p62, suggesting that SPK2-mediated autophagy and protections are not S1P-dependent. Beclin 1 knockdown abolished preconditioning-induced autophagy, and SPK2 inhibitors abolished isoflurane-induced disruption of the Beclin 1/Bcl-2 association. These results strongly indicate that autophagy is involved in isoflurane preconditioning both in vivo and in vitro and that SPK2 contributes to preconditioning-induced autophagy, possibly by disrupting the Beclin 1/Bcl-2 interaction.
authors.forename: Rui
authors.initials: R
authors.lastname: Sheng
authors.forename: Tong-Tong
authors.initials: TT
authors.lastname: Zhang
authors.forename: Valeria D
authors.initials: VD
authors.lastname: Felice
authors.forename: Tao
authors.initials: T
authors.lastname: Qin
authors.forename: Zheng-Hong
authors.initials: ZH
authors.lastname: Qin
authors.forename: Charles D
authors.initials: CD
authors.lastname: Smith
authors.forename: Ellen
authors.initials: E
authors.lastname: Sapp
authors.forename: Marian
authors.initials: M
authors.lastname: Difiglia
authors.forename: Christian
authors.initials: C
authors.lastname: Waeber
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy; D000071186:Beclin-1; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019194:Ischemic Preconditioning; D007530:Isoflurane / Q000494:pharmacology; D007790:Lactosylceramides / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009025:Morpholines / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099157:Sphingosine Kinase
chemical_list: D000218:Adamantane; D018685:Anesthetics, Inhalation; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D004791:Enzyme Inhibitors; D007530:Isoflurane; D007790:Lactosylceramides; D009025:Morpholines; D017853:Phosphotransferases (Alcohol Group Acceptor); D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; D011753:Pyrones; D051758:Transcription Factor TFIIH; D014157:Transcription Factors; D000099157:Sphingosine Kinase; C495818:2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one; C115010:Becn1 protein, mouse; C490981:Gtf2h1 protein, mouse; C025575:lactotriaosylceramide; C548780:3-(4-chlorophenyl)-adamantane-1-carboxylic acid (pyridin-4-ylmethyl)amide