title: Down-regulation of renal klotho expression by Shiga toxin 2.
abstract: OBJECTIVE
  Shiga toxin 2 may trigger classical hemolytic uremic syndrome (HUS) eventually leading to renal failure. Klotho, a transmembrane protein, protease and hormone mainly expressed in kidney is involved in the regulation of renal phosphate excretion and also retains renal protective effects. Renal failure is associated with renal depletion of klotho. The present study explored the influence of Shiga toxin 2 on renal klotho expression.
  
  
  METHODS
  Mice were injected with either solvent or Shiga toxin 2 and urinary flow rate and phosphate excretion were determined in metabolic cages. Renal transcript levels were measured by quantitative RT-PCR and renal protein abundance by Western blotting. Plasma concentrations of 1,25(OH)2D3 and FGF23 were determined by ELISA and plasma phosphate and urea concentrations by photometry.
  
  
  RESULTS
  Shiga toxin 2 treatment was followed by increase of plasma urea concentration, urinary flow rate and renal phosphate excretion but not of plasma phosphate concentration. Shiga toxin 2 treatment strongly decreased klotho mRNA expression and klotho protein abundance in renal tissue. Shiga toxin 2 treatment further increased tumor necrosis factor (Tnfα) mRNA levels, as well as protein abundance of phosphorylated p38 MAPK in renal tissue. The treatment significantly increased renal Cyp27b1 and decreased renal Cyp24a1 mRNA levels without significantly altering plasma 1,25(OH)2D3 levels. Shiga toxin 2 treatment was further followed by increase of plasma FGF23 concentrations.
  
  
  CONCLUSIONS
  Shiga toxin 2 treatment stimulated Tnfα transcription, down-regulated renal klotho expression and increased FGF23 formation, effects presumably contributing to renal tissue injury.
authors.affiliation: Department of Physiology, University of Tübingen, Tübingen, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Feger
authors.forename: Sobuj
authors.initials: S
authors.lastname: Mia
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Pakladok
authors.forename: Jan P
authors.initials: JP
authors.lastname: Nicolay
authors.forename: Ioana
authors.initials: I
authors.lastname: Alesutan
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Schneider
authors.forename: Jakob
authors.initials: J
authors.lastname: Voelkl
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D015536:Down-Regulation / Q000187:drug effects* / Q000502:physiology*; D000089703:Fibroblast Growth Factor-23; D005786:Gene Expression Regulation; D005966:Glucuronidase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis*; D000090265:Klotho Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D022641:Shiga Toxin 2 / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000652:urine
chemical_list: C000717428:Fgf23 protein, mouse; D022641:Shiga Toxin 2; D014409:Tumor Necrosis Factor-alpha; D000089703:Fibroblast Growth Factor-23; D005966:Glucuronidase; D000090265:Klotho Proteins