Dopaminochrome induces caspase-independent apoptosis in the mesencephalic cell line, MN9D
Article first published online: 9 MAY 2012
© 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry
Journal of Neurochemistry
Volume 122, Issue 1, pages 175–184, July 2012
How to Cite
Linsenbardt, A. J., Breckenridge, J. M., Wilken, G. H. and Macarthur, H. (2012), Dopaminochrome induces caspase-independent apoptosis in the mesencephalic cell line, MN9D. Journal of Neurochemistry, 122: 175–184. doi: 10.1111/j.1471-4159.2012.07756.x
- Issue published online: 11 JUN 2012
- Article first published online: 9 MAY 2012
- Accepted manuscript online: 9 APR 2012 01:07AM EST
- Received November 16, 2011; revised manuscript received February 16, 2012; accepted April 2, 2012.
- Parkinson’s disease;
J. Neurochem. (2012) 122, 175–184.
Parkinson’s disease is characterized by a deficiency in motor cortex modulation due to degeneration of pigmented dopaminergic neurons of the substantia nigra projecting to the striatum. These neurons are particularly susceptible to oxidative stress, perhaps because of their dopaminergic nature. Like all catecholamines, dopamine is easily oxidized, first to a quinone intermediate and then to dopaminochrome (DAC), a 5-dihydroxyindole tautomer, that is cytotoxic in an oxidative stress-dependent manner. Here we show, using the murine mesencephalic cell line MN9D, that DAC causes cell death by apoptosis, illustrated by membrane blebbing, Annexin V, and propidium iodide labeling within 3 h. In addition, DAC causes oxidative damage to DNA within 3 h, and positive terminal deoxynucleotidyl transferase dUTP nick end labeling fluorescence by 24 h. DAC, however, does not induce caspase 3 activation and its cytotoxic actions are not prevented by the pan-caspase inhibitor, Z-VAD-fmk. DAC-induced cytotoxicity is limited by the PARP1 inhibitor, 5-aminoisoquinolinone, supporting a role for apoptosis-inducing factor (AIF) in the apoptotic process. Indeed, AIF is detected in the nuclear fraction of MN9D cells 3 h after DAC exposure. Taken together these results demonstrate that DAC induces cytotoxicity in MN9D cells in a caspase-independent apoptotic manner, likely triggered by oxidative damage to DNA, and involving the translocation of AIF from the mitochondria to the nucleus.