title: Signal transducer and activator of transcription 3 involvement in the development of renal interstitial fibrosis after unilateral ureteral obstruction.
abstract: BACKGROUND
  In vitro studies suggest that the signal transducer and activator of transcription (STAT) plays a critical role in renal fibrosis. However, the process of STAT activation in vivo remains unclear. This study in rats aimed to localize STAT3 activation within the kidney and examine the in vivo relationship between STAT3 activation and renal fibrosis.
  
  
  METHODS
  Unilateral ureteral obstruction (UUO) was induced in the rats and the kidneys examined 3 or 7 days after obstruction. Activation of STAT3 in western blot and immunohistochemical analyses was identified by the phosphorylated form of STAT3 (pSTAT3).
  
  
  RESULTS
  Myofibroblasts were identified by alpha-smooth muscle actin expression and were upregulated in obstructed kidneys. pSTAT3 was localized mainly in tubular epithelial cells of collecting ducts in normal and obstructed kidneys and interstitial cells in obstructed kidneys. After UUO, western blotting showed a fourfold increase in pSTAT3, with a peak at day 7. Immunostaining showed a sixfold increase in pSTAT3 at day 7 in tubular epithelial cells and a 2500-fold increase at day 7 in interstitial cells.
  
  
  CONCLUSIONS
  STAT3 was activated in rat tubular epithelial cells and myofibroblasts after UUO, suggesting that STAT3 may contribute to the progression of interstitial fibrosis.
authors.affiliation: Department of Molecular and Internal Medicine, Graduate School of Medical Sciences, Hiroshima University, Hiroshima City, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kuratsune
authors.forename: Takao
authors.initials: T
authors.lastname: Masaki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hirai
authors.forename: Kei
authors.initials: K
authors.lastname: Kiribayashi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yokoyama
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Arakawa
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yorioka
authors.forename: Nobuoki
authors.initials: N
authors.lastname: Kohno
mesh_terms: D000818:Animals; D015153:Blotting, Western; D005355:Fibrosis; D007150:Immunohistochemistry; D007674:Kidney Diseases / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D050796:STAT3 Transcription Factor / Q000502:physiology*; D014517:Ureteral Obstruction / Q000150:complications*
chemical_list: D050796:STAT3 Transcription Factor