title: Extracellular signal-regulated kinase-dependent interstitial macrophage proliferation in the obstructed mouse kidney.
abstract: OBJECTIVE
  A number of growth factors have been shown to induce proliferation of renal cell types in animal models of kidney disease. In vitro studies suggest that many such growth factors induce renal cell proliferation through the extracellular signal-regulated kinase (ERK) pathway. The aim of this study was to determine the functional role of ERK signalling in cell proliferation in the obstructed kidney.
  
  
  METHODS
  Unilateral ureteric obstruction was induced in C57BL/6J mice which then received an ERK inhibitor drug (U0126 100 mg/kg t.i.d.), vehicle (DMSO) or no treatment, starting at day 2 after unilateral ureteric obstruction surgery and continuing until animals were killed on day 5. Cell proliferation was assessed by uptake of bromodeoxyuridine (BrdU).
  
  
  RESULTS
  In normal mice, phosphorylation (activation) of ERK (p-ERK) was restricted to collecting ducts. Western blotting identified a marked increase in p-ERK in the obstructed kidney in the no-treatment and vehicle-treated groups. Immunostaining showed strong p-ERK staining in many tubules and in interstitial cells. U0126 treatment inhibited ERK phosphorylation as assessed by western blot and immunostaining. The number of BrdU+ cortical tubular cells was reduced by vehicle treatment but was not further changed by U0126 treatment. In contrast, interstitial cell proliferation in the obstructed kidney was unaltered by vehicle treatment, but this was significantly inhibited by U0126. This was associated with a reduction in interstitial macrophage accumulation, but no effect was seen upon interstitial accumulation of alpha-SMA+ myofibroblasts. Renal fibrosis, as assessed by collagen deposition, was unaffected by U0126 or vehicle treatment.
  
  
  CONCLUSIONS
  These studies show that accumulation of interstitial macrophages in the obstructed kidney is, in part, dependent upon the ERK signalling pathway.
authors.affiliation: Department of Nephrology, Monash Medical Centre, Melbourne, Victoria, Australia.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Han
authors.forename: Takao
authors.initials: T
authors.lastname: Masaki
authors.forename: Lynette A
authors.initials: LA
authors.lastname: Hurst
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ikezumi
authors.forename: James M
authors.initials: JM
authors.lastname: Trzaskos
authors.forename: Robert C
authors.initials: RC
authors.lastname: Atkins
authors.forename: David J
authors.initials: DJ
authors.lastname: Nikolic-Paterson
mesh_terms: D000818:Animals; D002070:Butadienes / Q000008:administration & dosage / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D007674:Kidney Diseases / Q000201:enzymology*; D008264:Macrophages / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D009570:Nitriles / Q000008:administration & dosage / Q000494:pharmacology; D015398:Signal Transduction; D014517:Ureteral Obstruction / Q000601:surgery
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; C113580:U 0126; D020929:Mitogen-Activated Protein Kinase Kinases