Neuro Endocrinol Lett. 2013 Aug 7; 34(5):
This research reports the expression of topoisomerase ?II in fetal sheep neuronal cells. The ? isoform of DNA topoisomerase II plays a role in DNA repair process in non proliferating cells as neurons and its expression tends to be downregulated with senescence.Cortical neurons from 60-day-old sheep embryos underwent two protocols: the former based on rising time of culture (10, 20 and 30 days); the latter based on the 72hrs exposure to 3-nitro-L-tyrosine (oxidative/nitrosative stressor) and/or testosterone.Our results showed an increase in ?-galactosidase activity and, in contrast, a reduction in topoisomerase ?II expression with time (first protocol). The exposure of sheep primary neurons to 3-nitro-L-tyrosine led to an upregulation of ?II topoisomerase expression to be likely seen as a reaction to nitrosative stress. Testosterone addition to 3-nitro-L-tyrosine-exposed cells results in topoisomerase ?II decrease possibly due to the neuroprotective properties of testosterone (second protocol). No significant variations in the marker of aging ?-galactosidase were observed in the cells exposed to 3-nitro-L-tyrosine and testosterone.The protocol based on time could be of some interest as a model of neuronal senescence in vitro. Topoisomerase ?II decrease with aging likely indicates a reduced ability to repair DNA during neuronal senescence. In contrast, the second protocol may not be seen as a reliable model of aging since 3-nitro-L-tyrosine does not lead to a topoisomerase ?II decrease. Testosterone was able to cope with oxidative/nitrosative damage, allowing cells to reduce their needs in DNA repair which in turn leads to a downregulation of topoisomerase II? expression.
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This research reports the expression of topoisomerase ?II in fetal sheep neuronal cells. The ? isoform of DNA topoisomerase II plays a role in DNA repair process in non proliferating cells as neurons and its expression tends to be downregulated with senescence.Cortical neurons from 60-day-old sheep embryos underwent two protocols: the former based on rising time of culture (10, 20 and 30 days); the latter based on the 72hrs exposure to 3-nitro-L-tyrosine (oxidative/nitrosative stressor) and/or testosterone.Our results showed an increase in ?-galactosidase activity and, in contrast, a reduction in topoisomerase ?II expression with time (first protocol). The exposure of sheep primary neurons to 3-nitro-L-tyrosine led to an upregulation of ?II topoisomerase expression to be likely seen as a reaction to nitrosative stress. Testosterone addition to 3-nitro-L-tyrosine-exposed cells results in topoisomerase ?II decrease possibly due to the neuroprotective properties of testosterone (second protocol). No significant variations in the marker of aging ?-galactosidase were observed in the cells exposed to 3-nitro-L-tyrosine and testosterone.The protocol based on time could be of some interest as a model of neuronal senescence in vitro. Topoisomerase ?II decrease with aging likely indicates a reduced ability to repair DNA during neuronal senescence. In contrast, the second protocol may not be seen as a reliable model of aging since 3-nitro-L-tyrosine does not lead to a topoisomerase ?II decrease. Testosterone was able to cope with oxidative/nitrosative damage, allowing cells to reduce their needs in DNA repair which in turn leads to a downregulation of topoisomerase II? expression.
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