title: 3-Nitropropionic acid induces autophagy by forming mitochondrial permeability transition pores rather than activating the mitochondrial fission pathway.
abstract: OBJECTIVE
  Huntington's disease is a neurodegenerative process associated with mitochondrial alterations. Inhibitors of the electron-transport channel complex II, such as 3-nitropropionic acid (3NP), are used to study the molecular and cellular pathways involved in this disease. We studied the effect of 3NP on mitochondrial morphology and its involvement in macrophagy.
  
  
  METHODS
  Pharmacological and biochemical methods were used to characterize the effects of 3NP on autophagy and mitochondrial morphology. SH-SY5Y cells were transfected with GFP-LC3, GFP-Drp1 or GFP-Bax to ascertain their role and intracellular localization after 3NP treatment using confocal microscopy.
  
  
  RESULTS
  Untreated SH-SY5Y cells presented a long, tubular and filamentous net of mitochondria. After 3NP (5 mM) treatment, mitochondria became shorter and rounder. 3NP induced formation of mitochondrial permeability transition pores, both in cell cultures and in isolated liver mitochondria, and this process was inhibited by cyclosporin A. Participation of the mitochondrial fission pathway was excluded because 3NP did not induce translocation of the dynamin-related protein 1 (Drp1) to the mitochondria. The Drp1 inhibitor Mdivi-1 did not affect the observed changes in mitochondrial morphology. Finally, scavengers of reactive oxygen species failed to prevent mitochondrial alterations, while cyclosporin A, but not Mdivi-1, prevented the generation of ROS.
  
  
  CONCLUSIONS
  There was a direct correlation between formation of mitochondrial permeability transition pores and autophagy induced by 3NP treatment. Activation of autophagy preceded the apoptotic process and was mediated, at least partly, by formation of reactive oxygen species and mitochondrial permeability transition pores.
authors.affiliation: Unidad de Neuropsicofarmacología Traslacional, Complejo Hospitalario Universitario de Albacete, Spain.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Solesio
authors.forename: Sara
authors.initials: S
authors.lastname: Saez-Atienzar
authors.forename: Joaquin
authors.initials: J
authors.lastname: Jordan
authors.forename: Maria F
authors.initials: MF
authors.lastname: Galindo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D034281:Dynamins; D042963:Electron Transport Complex II / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000187:drug effects / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000187:drug effects / Q000235:genetics; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D063154:Mitochondrial Dynamics; D033681:Mitochondrial Membrane Transport Proteins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000187:drug effects* / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D024101:Mitochondrial Proteins / Q000187:drug effects / Q000235:genetics; D009574:Nitro Compounds / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D011422:Propionates / Q000494:pharmacology*; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D014178:Translocation, Genetic / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008869:Microtubule-Associated Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D024101:Mitochondrial Proteins; D009574:Nitro Compounds; D011422:Propionates; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D016572:Cyclosporine; D042963:Electron Transport Complex II; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; D034281:Dynamins; C015392:3-nitropropionic acid