title: Lung autophagic response following exposure of mice to whole body irradiation, with and without amifostine.
abstract: OBJECTIVE
  The effect of ionizing irradiation on the autophagic response of normal tissues is largely unexplored. Abnormal autophagic function may interfere the protein quality control leading to cell degeneration and dysfunction. This study investigates its effect on the autophagic machinery of normal mouse lung.
  
  
  METHODS
  Mice were exposed to 6 Gy of whole body γ-radiation and sacrificed at various time points. The expression of MAP1LC3A/LC3A/Atg8, beclin-1, p62/sequestosome-1 and of the Bnip3 proteins was analyzed.
  
  
  RESULTS
  Following irradiation, the LC3A-I and LC3A-II protein levels increased significantly at 72 h and 7 days. Strikingly, LC3A-II protein was increased (5.6-fold at 7 days; p<0.001) only in the cytosolic fraction, but remained unchanged in the membrane fraction. The p62 protein, was significantly increased in both supernatant and pellet fraction (p<0.001), suggesting an autophagosome turnover deregulation. These findings contrast the patterns of starvation-induced autophagy up-regulation. Beclin-1 levels remained unchanged. The Bnip3 protein was significantly increased at 8 h, but it sharply decreased at 72 h (p<0.05). Administration of amifostine (200 mg/kg), 30 min before irradiation, reversed all the LC3A and p62 findings on blots, suggesting restoration of the normal autophagic function. The LC3A and Beclin1 mRNA levels significantly declined following irradiation (p<0.01), whereas Bnip3 levels increased.
  
  
  CONCLUSIONS
  It is suggested that irradiation induces dysfunction of the autophagic machinery in normal lung, characterized by decreased transcription of the LC3A/Beclin-1 mRNA and accumulation of the LC3A, and p62 proteins. Whether this is due to defective maturation or to aberrant degradation of the autophagosomes requires further investigation.
authors.affiliation: Department of Radiotherapy-Oncology, Democritus University of Thrace, Alexandroupolis 68100, Greece.
authors.forename: Christos E
authors.initials: CE
authors.lastname: Zois
authors.forename: Alexandra
authors.initials: A
authors.lastname: Giatromanolaki
authors.forename: Heikki
authors.initials: H
authors.lastname: Kainulainen
authors.forename: Sotirios
authors.initials: S
authors.lastname: Botaitis
authors.forename: Sira
authors.initials: S
authors.lastname: Torvinen
authors.forename: Constantinos
authors.initials: C
authors.lastname: Simopoulos
authors.forename: Alexandros
authors.initials: A
authors.lastname: Kortsaris
authors.forename: Efthimios
authors.initials: E
authors.lastname: Sivridis
authors.forename: Michael I
authors.initials: MI
authors.lastname: Koukourakis
mesh_terms: D004999:Amifostine / Q000494:pharmacology*; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects / Q000528:radiation effects*; D000071186:Beclin-1; D005720:Gamma Rays; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D013217:Starvation / Q000503:physiopathology; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014916:Whole-Body Irradiation
chemical_list: D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; C490981:Gtf2h1 protein, mouse; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D011837:Radiation-Protective Agents; D014157:Transcription Factors; D051758:Transcription Factor TFIIH; D004999:Amifostine