engleski

Effect of fumonisin B1 on calcium signalling and mitochondrial membrane potential in cells of neuronal origin

Fumonisin B1 (FB1) is mycotoxin that contaminates food and feed world-wide. Its adverse effect on animal and human health is well established. However, molecular mechanism underlying FB1 neurodegenerative potential is still not known. Calcium plays important role as a second messenger in the cell and within the cell mitochondria has a major role in maintaining calcium homeostasis. Therefore in this study we explored effect of FB1 on calcium signalling and mitochondrial membrane potential (Δψm) as an indicator of mitochondrial integrity in the cells of neuronal origin. Astrocytes and neuroblastoma cells were treated with FB1 (0.5, 5 and 50 µM). In the single cell intracellular calcium level [Ca2+]c was monitored with fura-2 AM and change in ψm with Rhodamine 123. Fluorescence measurements were done on an epifluorescent inverted microscope with excitation light set at 340, 380 and 490 nm and emitted fluorescence light was reflected through a 515 nm long-pass filter to a cooled CCD camera. All imaging data were collected and analyzed using software from Andor (Belfast, UK). Obtained data were statistically analysed with the aid of Origin 8 software (Microcal Software Inc., Northampton, MA, USA). In astrocytes and neuroblastoma cells FB1 produced mitochondrial membrane depolarisation, and the effect was dose-dependent. Calcium signal in both cell lines was induced with ATP (100 μM). In control cells ATP induced [Ca2+]c signal but the change in Δψm was not observed. However, in the cells pre-treated with FB1 the ATP-induced [Ca2+]c signal was significantly higher compared to control cells. Furthermore, in cells pre-treated with FB1 mitochondrial depolarisation was observed. These results indicate that FB1 causes irreversible damage to the mitochondrial membrane and that change of Δψm by FB1 renders cells vulnerable to physiological calcium signalling. Thus, mitochondria appear to be primary target of FB1 which leads to calcium deregulation and presumably cell death.

fumonisin B1; calcium signalling; mitochondrial membrane potential

nije evidentirano