Homocysteine and copper induce cellular apoptosis via caspase activation and nuclear translocation of apoptosis-inducing factor in neuronal cell line SH-SY5Y

• Published in: Neuroscience research Vol. 67; no. 4; pp. 300 - 306
• Main Authors: Hirashima, Yoshimasa, Seshimo, So, Fujiki, Yoshika, Okabe, Masaaki, Nishiyama, Kazuo, Matsumoto, Mitsuharu, Kanouchi, Hiroaki, Oka, Tatsuzo
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.08.2010
• Subjects: Active Transport, Cell Nucleus - drug effects; Active Transport, Cell Nucleus - physiology; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Apoptosis Inducing Factor - physiology; Apoptosis-inducing factor; Caspase 3 - drug effects; Caspase 3 - physiology; Caspases - metabolism; Caspases - physiology; Catalase - pharmacology; Cell Line, Tumor; Copper; Copper - physiology; Copper - toxicity; Enzyme Activation - drug effects; Enzyme Activation - physiology; Homocysteine; Homocysteine - physiology; Homocysteine - toxicity; Humans; Hyperhomocysteinemia - enzymology; Hyperhomocysteinemia - metabolism; Hyperhomocysteinemia - pathology; Neurons - drug effects; Neurons - metabolism; Reactive oxygen species; Reactive oxygen species; Homocysteine; Copper; Apoptosis-inducing factor; Apoptosis
• ISSN: 0168-0102; 1872-8111
• DOI: 10.1016/j.neures.2010.04.013

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 250 μM homocysteine and 10 μM 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.