Excessive neuronal
iron has been proposed to contribute to the pathology of several
neurodegenerative diseases including Alzheimer's and Parkinson's diseases. This work characterized human
neuroblastoma IMR-32 cells exposure to
ferric ammonium citrate (FAC) as a model of neuronal
iron overload and neurodegeneration. The consequences of FAC treatment on neuronal oxidative stress and on the modulation of the
oxidant-sensitive
transcription factors AP-1 and NF-κB were investigated. Incubation with FAC (150μM) resulted in a time (3-72h)-dependent increase in cellular
iron content, and was associated with cell
oxidant increase. FAC caused a time-dependent (3-48h) increase in nuclear AP-1- and NF-κB-
DNA binding. This was associated with the upstream activation of the
mitogen activated
kinases ERK1/2, p38 and JNK and of IκBα phosphorylation and degradation. After 72h incubation with FAC, cell viability was 40% lower than in controls.
Iron overload caused apoptotic cell death. After 48-72h of incubation with FAC,
caspase 3 activity was increased, and
chromatin condensation and nuclear fragmentation were observed. In summary, the exposure of IMR-32 cells to FAC is associated with increased
oxidant cell levels, activation of redox-sensitive signals, and apoptosis.