title: Downregulation of miR-205 modulates cell susceptibility to oxidative and endoplasmic reticulum stresses in renal tubular cells.
abstract: BACKGROUND
  Oxidative stress and endoplasmic reticulum (ER) stress play a crucial role in tubular damage in both acute kidney injury (AKI) and chronic kidney disease (CKD). While the pathophysiological contribution of microRNAs (miRNA) to renal damage has also been highlighted, the effect of miRNA on renal damage under oxidative and ER stresses conditions remains elusive.
  
  
  METHODS
  We assessed changes in miRNA expression in the cultured renal tubular cell line HK-2 under hypoxia-reoxygenation-induced oxidative stress or ER stress using miRNA microarray assay and real-time RT-PCR. The pathophysiological effect of miRNA was evaluated by cell survival rate, intracellular reactive oxygen species (ROS) level, and anti-oxidant enzyme expression in miRNA-inhibited HK-2 or miRNA-overexpressed HK-2 under these stress conditions. The target gene of miRNA was identified by 3'-UTR-luciferase assay.
  
  
  RESULTS
  We identified 8 and 10 miRNAs whose expression was significantly altered by oxidative and ER stresses, respectively. Among these, expression of miR-205 was markedly decreased in both stress conditions. Functional analysis revealed that decreased miR-205 led to an increase in cell susceptibility to oxidative and ER stresses, and that this increase was associated with the induction of intracellular ROS and suppression of anti-oxidant enzymes. While increased miR-205 by itself made no change in cell growth or morphology, cell viability under oxidative or ER stress conditions was partially restored. Further, miR-205 bound to the 3'-UTR of the prolyl hydroxylase 1 (PHD1/EGLN2) gene and suppressed the transcription level of EGLN2, which modulates both intracellular ROS level and ER stress state.
  
  
  CONCLUSIONS
  miR-205 serves a protective role against both oxidative and ER stresses via the suppression of EGLN2 and subsequent decrease in intracellular ROS. miR-205 may represent a novel therapeutic target in AKI and CKD associated with oxidative or ER stress in tubules.
authors.affiliation: Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Tokyo, Japan.
authors.forename: Shiyo
authors.initials: S
authors.lastname: Muratsu-Ikeda
authors.forename: Masaomi
authors.initials: M
authors.lastname: Nangaku
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Takehiko
authors.initials: T
authors.lastname: Wada
authors.forename: Reiko
authors.initials: R
authors.lastname: Inagi
mesh_terms: D051701:Activating Transcription Factor 4 / Q000235:genetics / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D015687:Cell Hypoxia; D002460:Cell Line; D059865:Endoplasmic Reticulum Stress; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D007684:Kidney Tubules / Q000166:cytology*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D017422:Sequence Analysis, DNA; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology; D059467:Transcriptome; D014415:Tunicamycin / Q000494:pharmacology; D000099162:Endothelial PAS Domain-Containing Protein 1; D000099156:Superoxide Dismutase 2
chemical_list: D051701:Activating Transcription Factor 4; D051792:Basic Helix-Loop-Helix Proteins; D002374:Catalase; D051547:Heme Oxygenase-1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D035683:MicroRNAs; D009687:Nuclear Proteins; D011393:Procollagen-Proline Dioxygenase; D013482:Superoxide Dismutase; D019284:Thapsigargin; D014415:Tunicamycin; D000099162:Endothelial PAS Domain-Containing Protein 1; D000099156:Superoxide Dismutase 2; C497109:ATF4 protein, human; C497442:HIF1A protein, human; C534425:MIR205, human; C447780:EGLN2 protein, human; C496541:HMOX1 protein, human