Genistein inhibits Ca2+ influx by extracellular ATP in PC12 pheochromocytoma cells
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O Kozawa1, J Shinoda, A Suzuki
1Department of Biochemistry, Institute for Development Research, Aichi, Japan.
Abstract:
We previously showed that extracellular ATP-induced Ca2+ influx is inhibited by self-activated protein kinase C in rat PC12 pheochromocytoma cells. In the present study, we examined whether tyrosine kinase is involved in the ATP-induced Ca2+ influx in PC12 cells. Genistein, an inhibitor of protein tyrosine kinases, which by itself had little effect on 45Ca2+ influx, significantly suppressed the ATP-induced 45Ca2+ influx in a dose-dependent manner in the range between 1 and 30 micrograms/ml. Tyrophostin, another inhibitor of tyrosine kinases chemically distinct from genistein, also inhibited the 45Ca2+ influx. Sodium orthovanadate, an inhibitor of protein tyrosine phosphatases, markedly enhanced the ATP-induced 45Ca2+ influx. These results suggest that tyrosine kinase regulates Ca2+ influx induced by extracellular ATP in PC12 pheochromocytoma cells.
Insights
Extracellular ATP-induced calcium (Ca2+) influx in PC12 cells is regulated by tyrosine kinase. Inhibiting tyrosine kinase suppressed Ca2+ influx, while inhibiting tyrosine phosphatases enhanced it.
Area of Science:
- Cellular biology
- Biochemistry
- Neuroscience
Background:
- Extracellular ATP triggers calcium influx in PC12 cells.
- Protein kinase C (PKC) was previously shown to inhibit this influx.
Purpose of the Study:
- To investigate the role of tyrosine kinase in ATP-induced calcium influx in PC12 cells.
Main Methods:
- PC12 cells were treated with genistein and tyrophostin (tyrosine kinase inhibitors).
- The effect of sodium orthovanadate (a tyrosine phosphatase inhibitor) on calcium influx was assessed.
- 45Ca2+ influx was measured to quantify calcium uptake.
Main Results:
- Genistein and tyrophostin significantly inhibited ATP-induced 45Ca2+ influx in a dose-dependent manner.
- Sodium orthovanadate markedly enhanced ATP-induced 45Ca2+ influx.
- Tyrosine kinase activity appears crucial for regulating calcium influx.
Conclusions:
- Tyrosine kinase plays a regulatory role in extracellular ATP-induced calcium influx in PC12 pheochromocytoma cells.
- This finding contributes to understanding calcium signaling pathways in neuronal cells.