title: Transcriptional regulation of aquaporins in the ischemic rat retina: upregulation of aquaporin-9.
abstract: OBJECTIVE
  To determine the transcriptional regulation of retinal aquaporins (AQPs) in rat models of transient and permanent retinal ischemia, and to prove the effects of chemical hypoxia, oxidative stress, glucose, and osmotic alterations on the expression of AQP9 in cultured human retinal pigment epithelium (RPE) cells.
  
  
  METHODS
  Transient retinal ischemia-reperfusion in rats was induced by elevation of the intraocular pressure for 1 hour. Permanent retinal ischemia was induced by argon laser-induced retinal vein occlusion. The mRNA levels were determined one day after ischemia.
  
  
  RESULTS
  Transient and permanent ischemia of the rat retina resulted in downregulation of AQPs 1, 3, 4, 5, 6, 8, and 11 in the RPE and/or neural retina. Pressure-induced transient retinal ischemia-induced upregulation of AQP9 in the neuroretina and RPE, and of AQ12 in the neuroretina. Retinal vein occlusion induced upregulation of AQP0 in the neuroretina and RPE, and of AQP9 and AQP12 in the neuroretina. In cultured human RPE cells, transcriptional expression of AQP9 was stimulated by chemical hypoxia, oxidative stress, VEGF, and high glucose.
  
  
  CONCLUSIONS
  The data may suggest that the expression of retinal AQP9 is regulated by metabolic and oxidative stress. Upregulation of AQP9 in RPE cells may prevent lactic acidosis and subretinal edema under ischemic and oxidative stress conditions.
authors.affiliation: Department of Ophthalmology and Eye Clinic, University of Leipzig, Leipzig, Germany. hollbm@medizin.uni-leipzig.de
authors.forename: Margrit
authors.initials: M
authors.lastname: Hollborn
authors.forename: Matus
authors.initials: M
authors.lastname: Rehak
authors.forename: Ianors
authors.initials: I
authors.lastname: Iandiev
authors.forename: Thomas
authors.initials: T
authors.lastname: Pannicke
authors.forename: Elke
authors.initials: E
authors.lastname: Ulbricht
authors.forename: Andreas
authors.initials: A
authors.lastname: Reichenbach
authors.forename: Peter
authors.initials: P
authors.lastname: Wiedemann
authors.forename: Andreas
authors.initials: A
authors.lastname: Bringmann
authors.forename: Leon
authors.initials: L
authors.lastname: Kohen
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology; D007429:Intraocular Pressure; D007511:Ischemia / Q000209:etiology / Q000235:genetics*; D008297:Male; D009798:Ocular Hypertension / Q000150:complications; D018384:Oxidative Stress; D051381:Rats; D020318:Rats, Long-Evans; D060888:Real-Time Polymerase Chain Reaction; D055213:Retinal Pigment Epithelium / Q000187:drug effects / Q000378:metabolism*; D012170:Retinal Vein Occlusion / Q000150:complications; D012171:Retinal Vessels / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
chemical_list: C491637:Aqp9 protein, rat; D020346:Aquaporins; D042461:Vascular Endothelial Growth Factor A; D005947:Glucose