title: Signaling pathways involved in HSP32 induction by hyperbaric oxygen in rat spinal neurons.
abstract: Spinal cord injury (SCI) is a debilitating disease, effective prevention measures are in desperate need. Our previous work found that hyperbaric oxygen (HBO) preconditioning significantly protected rats from SCI after stimulated diving, and in vitro study further testified that HBO protected primary cultured rat spinal neurons from oxidative insult and oxygen glucose deprivation injury via heat shock protein (HSP) 32 induction. In this study, underlying molecular mechanisms were further investigated. The results showed that a single exposure to HBO significantly increased intracellular levels of reactive oxygen species (ROS) and nitric oxide (NO) and activated MEK1/2, ERK1/2, p38 MAPK, CREB, Bach1 and Nrf2. The induction of HSP32 by HBO was significantly reversed by pretreatment neurons with ROS scavenger N-Acetyl-L-cysteine, p38 MAPK inhibitor or Nrf2 gene knockdown, enhanced by MEK1/2 inhibitors or gene knockdown but not by ERK1/2 inhibitor. CREB knockdown did not change the expression of HSP32 induced by HBO. N-Acetyl-L-cysteine significantly inhibited the activation of MEK1/2, ERK1/2, p38 MAPK, and Nrf2. Activation of Nrf2 was significantly inhibited by p38 MAPK inhibitor and the nuclear export of Bach1 was significantly enhanced by MEK1/2 inhibitor. The results demonstrated that HBO induces HSP32 expression through a ROS/p38 MAPK/Nrf2 pathway and the MEK1/2/Bach1 pathway contributes to negative regulation in the process. More importantly, as we know, this is the first study to delineate that ERK1/2 is not the only physiological substrates of MEK1/2.
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China.
authors.forename: Guoyang
authors.initials: G
authors.lastname: Huang
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China.
authors.forename: Jiale
authors.initials: J
authors.lastname: Diao
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yi
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China.
authors.forename: Jiajun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Diving and Hyperbaric Medicine, The Second Military Medical University, 800 Xiangyin Road, Shanghai, PR China. Electronic address: wg_hsu@163.com.
authors.forename: Weigang
authors.initials: W
authors.lastname: Xu
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism*; D006931:Hyperbaric Oxygenation / Q000379:methods*; D020935:MAP Kinase Signaling System; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology* / Q000378:metabolism
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D051267:NF-E2-Related Factor 2; C495637:Nfe2l2 protein, rat; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D006419:Heme Oxygenase (Decyclizing); C491523:Hmox1 protein, rat
keywords: Heat shock protein 32; Hyperbaric oxygen; Negative regulation; Reactive oxygen species; Signal transduction