title: Intranuclear localization of apoptosis-inducing factor and endonuclease G involves in peroxynitrite-induced apoptosis of spiral ganglion neurons.
abstract: OBJECTIVE
  The present study was designed to determine whether or not the caspase-independent apoptotic pathway participated in the cellular death of spiral ganglion neurons (SGNs) after exposure to peroxynitrite (ONOO(-)), with particular attention given to the  intranuclear translocation of mitochondrial apoptosis-inducing factor (AIF) and endonuclease G (Endo G) in this process.
  
  
  METHODS
  The rat SGNs were isolated and primary cultured in vitro and were exposed to ONOO(-) with pre-treatment of pan-caspase inhibitor.  Morphological changes of SGNs were observed by acridine orange cytochemistry staining, and apoptosis was examined by flow cytometry. The translocation of mitochondrial AIF and Endo G was detected by immunocytochemistry and Western blot. The protein expressions of Bcl-2 family in SGNs exposed  to ONOO(-) were determined by Western blot.
  
  
  RESULTS
  Treatment of SGNs with ONOO(-) resulted in the occurrence of caspase-independent apoptosis as evidenced by acridine orange staining and flow cytometry analysis. The immunocytochemical analysis showed  that AIF and Endo G labeling were marked in neuronal nuclei, while the Western blot demonstrated the intranuclear localization of AIF and Endo G in SGNs treated with ONOO(-). Western blot analysis demonstrated that ONOO(-) increased the Bax expression while reducing  Bcl-2 expression, which was not prevented by pre-treatment with caspase inhibitor.
  
  
  CONCLUSIONS
  These data indicate that ONOO(-) can trigger caspase-independent apoptosis in SGNs associated with mitochondrial AIF and Endo G intranuclear localization.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, China.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Liu
authors.forename: Zhaomin
authors.initials: Z
authors.lastname: Fan
authors.forename: Yuechen
authors.initials: Y
authors.lastname: Han
authors.forename: Daogong
authors.initials: D
authors.lastname: Zhang
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D042581:Intranuclear Space / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000633:toxicity*; D061251:Primary Cell Culture; D051381:Rats; D013136:Spiral Ganglion / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D051033:Apoptosis Inducing Factor; D030421:Peroxynitrous Acid; D004706:Endodeoxyribonucleases; C052391:endonuclease G