Homocysteine and copper induce cellular apoptosis via caspase activation and nuclear translocation of apoptosis-inducing factor in neuronal cell line SH-SY5Y.
Hyperhomocysteinemia has been implicated in dementia and neurodegenerative disease. Physiological homocysteine concentrations did not result in apoptosis in SH-SY5Y cells in the present study. The apoptosis was recognized in millimolar level of homocysteine. However, SH-SY5Y cell death was observed following exposure to micromolar level of homocysteine in combination with copper. Exposure to 250microM homocysteine and 10microM CuCl(2) for one day decreased cell viability by 40%. Homocysteine and copper caused apoptosis, because hallmarks of apoptosis were recognized, such as loss of mitochondrial membrane potential, TUNEL-positive cells, release of cytochrome c from mitochondria, and caspase-3 activation, but not nucleosomal DNA fragmentation. Homocysteine and copper generated the intracellular reactive oxygen species, and homocysteine and copper-induced apoptosis was due to an accumulation of intracellular reactive oxygen species, which was inhibited by catalase. Pan-caspase inhibitor, z-VAD-fmk, could not completely inhibited homocysteine and copper-induced cell death. Homocysteine and copper also caused the nuclear translocation of apoptosis-inducing factor. These results suggested that homocysteine and copper induced not only caspase-dependent apoptosis but also caspase-independent apoptosis-inducing factor related apoptosis.
Hirashima
Yoshimasa
Y
Department of Veterinary Medicine, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan.
Seshimo
So
S
Fujiki
Yoshika
Y
Okabe
Masaaki
M
Nishiyama
Kazuo
K
Matsumoto
Mitsuharu
M
Kanouchi
Hiroaki
H
Oka
Tatsuzo
T
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor / Q000502:physiology*; D053148:Caspase 3 / Q000187:drug effects / Q000502:physiology; D020169:Caspases / Q000378:metabolism* / Q000502:physiology; D002374:Catalase / Q000494:pharmacology; D045744:Cell Line, Tumor; D003300:Copper / Q000502:physiology / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006710:Homocysteine / Q000502:physiology / Q000633:toxicity*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism
C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D006710:Homocysteine; D003300:Copper; D002374:Catalase; D053148:Caspase 3; D020169:Caspases