title: Role of insulin in Cr(VI)-mediated genotoxicity in Neurospora crassa.
abstract: OBJECTIVE
  Chromium (III) is an insulinomimetic agent whose biological and/or environmental availability is frequently in the form of Cr(VI), which is known to be toxic. Wall-less mutant of Neurospora crassa (FGSC stock no. 4761) is known to possess insulin receptor in its cell membrane and hence is a good model for Cr toxicity studies. This study explores the toxicity of Cr(VI) and the possible consequences on simultaneous exposure to insulin in N. crassa.
  
  
  RESULTS
  Comet assay of N. crassa cells treated with 100 μmol l⁻¹ Cr(VI) showed up to 50% reduction in comet tail lengths when incubated simultaneously with 0.4 U insulin. Fluorescence measurement in Cr(VI)-treated cells using DCFH-DA showed six- to eightfold increase in free radical generation, which was reduced to fourfold by 0.4 U insulin. Annexin-V/PI Flow cytometry analysis indicated necrotic cell death up to 28.7 ± 3.6% and 68.6 ± 2.5% on Cr(VI) exposure at concentrations 100 and 500 μmol l⁻¹ which was reduced by 68.3 ± 3.2% and 48.9 ± 3.6%, respectively, upon addition of insulin.
  
  
  CONCLUSIONS
  Insulin-mediated protection from DNA damage by Cr(VI) is because of scavenging of free radicals liberated during exposure to Cr(VI).
  
  
  CONCLUSIONS
  Overall, Cr(VI) toxicity depends upon available insulin, indicating that Cr(VI) toxicity may be a serious issue in insulin-deficient individuals with diabetes.
authors.affiliation: Department of Biochemistry, Osmania University, Hyderabad, India.
authors.forename: R R
authors.initials: RR
authors.lastname: Gaddameedi
authors.forename: S
authors.initials: S
authors.lastname: Burgula
authors.forename: M
authors.initials: M
authors.lastname: Sairam
authors.forename: S S
authors.initials: SS
authors.lastname: Singh
mesh_terms: D002857:Chromium / Q000378:metabolism / Q000633:toxicity*; D020552:Comet Assay; D004249:DNA Damage; D005656:Fungal Proteins / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D009336:Necrosis; D009492:Neurospora crassa / Q000187:drug effects* / Q000378:metabolism*; D017382:Reactive Oxygen Species; D011972:Receptor, Insulin / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D007328:Insulin; D017382:Reactive Oxygen Species; D002857:Chromium; D011972:Receptor, Insulin