Caspase-independent death of Leber's hereditary optic neuropathy cybrids is driven by energetic failure and mediated by AIF and Endonuclease G.
Leber's hereditary optic neuropathy (LHON) is associated with mitochondrial DNA point mutations affecting different subunits of complex I. By replacing glucose with galactose in the medium, cybrids harboring each of the three LHON pathogenic mutations (11778/ND4, 3460/ND1, 14484/ND6) suffered a profound ATP depletion over a few hours and underwent apoptotic cell death, which was caspase-independent. Control cybrids were unaffected. In addition to cytochrome c, apoptosis inducing factor (AIF) and endonuclease G (EndoG) were also released from the mitochondria into the cytosol in LHON cybrids, but not in control cells. Exposure of isolated nuclei to cytosolic fractions from LHON cybrids maintained in galactose medium caused nuclear fragmentation, which was strongly reduced by immuno-depletion with anti-AIF and anti-EndoG antibodies. In conclusion, the caspase-independent death of LHON cybrids incubated in galactose medium is triggered by rapid ATP depletion and mediated by AIF and EndoG.
Zanna
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C
Dipartimento di Biologia Ev. Sperimentale, Università di Bologna, Via Irnerio 42, Bologna 40126, Italy.
Ghelli
A
A
Porcelli
A M
AM
Martinuzzi
A
A
Carelli
V
V
Rugolo
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000502:physiology*; D002478:Cells, Cultured; D003470:Culture Media; D042967:Electron Transport Complex I / Q000235:genetics; D004706:Endodeoxyribonucleases / Q000502:physiology*; D005690:Galactose / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D006822:Hybrid Cells; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000166:cytology
D000590:Amino Acid Chloromethyl Ketones; D051033:Apoptosis Inducing Factor; D003470:Culture Media; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000255:Adenosine Triphosphate; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D042967:Electron Transport Complex I; D005690:Galactose