title: Dephosphorylated Ser985 of c-Met is associated with acquired resistance to rechallenge injury in rats that had recovered from uranyl acetate-induced subclinical renal damage.
abstract: BACKGROUND
  We previously reported that rats that had recovered from mild proximal tubule (PT) injury induced by a sub-toxic dose of uranyl acetate (UA) showed partial resistance to a subsequent nephrotoxic dose of UA in association with reduced renal dysfunction and accelerated PT proliferation. We demonstrated that this resistance may involve hepatocyte growth factor (HGF)/c-Met signaling. Here, we examined whether primary cultured tubular cells derived from this model had acquired sensitivity to HGF.
  
  
  METHODS
  Tubular cells were isolated by collagenase digestion from rat kidneys after recovery from UA-induced mild PT injury and were cultured for 48 h. Their survival and proliferation were examined using the MTS assay/5-bromo-2'-deoxyuridine labeling or MTS assay, respectively, and their migration was assayed using wound-healing and cell scattering assays, with/without HGF. HGF/c-Met signaling was assayed using phospho-specific antibodies.
  
  
  RESULTS
  HGF-stimulated cultured tubular cells from UA-treated rats showed better survival after UA exposure and higher proliferation and migration than cells from vehicle-treated rats. Furthermore, HGF induced higher phosphorylation of c-Met (Tyr1234/1235) and of its major downstream signals (AKT and extracellular signal-regulated kinase 1/2) with maintained dephosphorylation of Ser985 as a negative regulator of HGF/c-Met signaling in the tubular cells of UA-treated rats compared to those of vehicle-treated rats. Immunohistochemically, dephosphorylated Ser985 was confirmed in PT cells in vivo.
  
  
  CONCLUSIONS
  These results suggest that elevated sensitivity to HGF, via dephosphorylated Ser985 of c-Met of tubular cells that had recovered from mild tubular injury, may be associated with cytoprotection, accelerated proliferation and migration.
authors.affiliation: Internal Medicine 1, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashiku, Hamamatsu, Shizuoka, 431-3192, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Fujikura
authors.forename: Akashi
authors.initials: A
authors.lastname: Togawa
authors.forename: Yuan
authors.initials: Y
authors.lastname: Sun
authors.forename: Takamasa
authors.initials: T
authors.lastname: Iwakura
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasuda
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Fujigaki
mesh_terms: D000818:Animals; D060467:Disease Resistance; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D007674:Kidney Diseases / Q000139:chemically induced*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D009942:Organometallic Compounds / Q000633:toxicity*; D010766:Phosphorylation; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D051381:Rats; D012694:Serine / Q000378:metabolism
chemical_list: D009942:Organometallic Compounds; C005460:uranyl acetate; D012694:Serine; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met