Effects of nitric oxide donors on cybrids harbouring the mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) A3243G mitochondrial DNA mutation.
Reactive nitrogen and oxygen species (O2*-, H2O2, NO* and ONOO-) have been strongly implicated in the pathophysiology of neurodegenerative and mitochondrial diseases. In the present study, we examined the effects of nitrosative and/or nitrative stress generated by DETA-NO {(Z)-1-[2-aminoethyl-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate}, SIN-1 (3-morpholinosydnonimine hydrochloride) and SNP (sodium nitroprusside) on U87MG glioblastoma cybrids carrying wt (wild-type) and mutant [A3243G (Ala3243-->Gly)] mtDNA (mitochondrial genome) from a patient suffering from MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes). The mutant cybrids had reduced activity of cytochrome c oxidase, significantly lower ATP level and decreased mitochondrial membrane potential. However, endogenous levels of reactive oxygen species were very similar in all cybrids regardless of whether they carried the mtDNA defects or not. Furthermore, the cybrids were insensitive to the nitrosative and/or nitrative stress produced by either DETA-NO or SIN-1 alone. Cytotoxicity, however, was observed in response to SNP treatment and a combination of SIN-1 and glucose-deprivation. The mutant cybrids were significantly more sensitive to these insults compared with the wt controls. Ultrastructural examination of dying cells revealed several characteristic features of autophagic cell death. We concluded that nitrosative and/or nitrative stress alone were insufficient to trigger cytotoxicity in these cells, but cell death was observed with a combination of metabolic and nitrative stress. The vulnerability of the cybrids to these types of injury correlated with the cellular energy status, which were compromised by the MELAS mutation.
Sandhu
Jagdeep K
JK
Neurogenesis and Brain Repair Group, M54, Institute for Biological Sciences, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, Canada K1A 0R6.
Sodja
Caroline
C
McRae
Kevan
K
Li
Yan
Y
Rippstein
Peter
P
Wei
Yau-Huei
YH
Lach
Boleslaw
B
Lee
Fay
F
Bucurescu
Septimiu
S
Harper
Mary-Ellen
ME
Sikorska
Marianna
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D006822:Hybrid Cells / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D017241:MELAS Syndrome / Q000235:genetics*; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009154:Mutation; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014226:Triazenes / Q000494:pharmacology
C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; D004272:DNA, Mitochondrial; D020030:Nitric Oxide Donors; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D014226:Triazenes; D009599:Nitroprusside; C002385:linsidomine; D000255:Adenosine Triphosphate; D008981:Molsidomine