title: Down-regulation of Aquaporin1 (AQP1) by peptidoglycan via p38 MAPK pathways in primary rat pleural mesothelial cells.
abstract: OBJECTIVE
  This study was designed to investigate the p38 mitogen-activated protein kinase (MAPK) signaling pathway involved in Aquaporin1 (AQP1) expression caused by staphylococcal peptidoglycan (PGN) in cultured rat pleural mesothelial cells (rPMCs) in vitro.
  
  
  METHODS
  RT-PCR and immunoblot analysis were used to determine the relative mRNA and protein levels of AQP1 by PGN in rPMCs. P38 kinase inhibitor SB203580, JNK inhibitor SP600125, and ERK1/2 inhibitor PD98059 were used to determine the effects of PGN-induced AQP1 expression by immunoblot. Activation of p38 by PGN was reflected by detecting the phosphorylation constituent of p38, using immunoblot. The shift of localization after activation of p38 by PGN was investigated by immunofluorescence assay.
  
  
  RESULTS
  AQP1 transcription and protein expression were decreased by PGN in dose-dependent and time-dependent manners in rPMCs. Down-regulation of AQP1 by PGN was blocked only by SB203580, neither by SP600125 nor by PD98059. Furthermore, rPMCs exposed to PGN showed activation of p38 MAPK. Phospho-p38 protein production was increased by PGN stimulation in rPMCs. The localization of phospho-p38 was both in the cytosol and nuclei after PGN treatment, while its normal distribution is mainly in the cytosol in rPMCs.
  
  
  CONCLUSIONS
  AQP1 expression was decreased by PGN in both dose-dependent and time-dependent manners in rPMCs. This down-regulation by PGN-induced AQP1 in rPMCs may be mediated by the activation of p38 MARK pathway.
authors.affiliation: 1Department of Respiratory Disease, The First Affiliated Hospital of Guangxi Medical University, Nanning, China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Liu
authors.forename: Linlin
authors.initials: L
authors.lastname: Du
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Chen
authors.forename: Shouming
authors.initials: S
authors.lastname: Qin
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Liang
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zou
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Liang
authors.forename: Jing
authors.initials: J
authors.lastname: Jiang
authors.forename: Quanfang
authors.initials: Q
authors.lastname: Chen
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.forename: Canmao
authors.initials: C
authors.lastname: Xie
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D010457:Peptidoglycan; D010766:Phosphorylation; D010994:Pleura / Q000378:metabolism*; D017208:Rats, Wistar; D013211:Staphylococcus aureus
chemical_list: D010457:Peptidoglycan; D051398:Aquaporin 1