Oxidative stress is the main cause of neuronal death in pathological conditions. Hydrogen peroxide (H2O2), one of the reactive oxygen species, activates many intracellular signaling cascades including src family and mitogen-activated protein kinases (MAPKs), some of which are critically involved in the induction of cellular damage. We previously showed that H2O2-induced cell death in astrocytes and adenosine 5′-triphosphate (ATP), acting on P2Y1 receptors, had a protective effect. Here, we examined the H2O2-induced changes in intracellular signaling cascades that promote cell death in astrocytes, showing the molecular mechanisms by which the activation of P2Y1 receptors counteracts such signals. Although H2O2 activated three MAPKs including ERK1/2, p38, and JNK, only the activation of ERK1/2 participated in the H2O2-evoked cell death. H2O2 induced a sustained activation of ERK1/2 mainly in the nucleus region, which was well in accordance with the H2O2-induced cell death. H2O2 also activated the src tyrosine kinase family, which was an upstream signal for ERK1/2. Activation of P2Y1 receptors by 2methylthio-ADP (2MeSADP) inhibited the H2O2-evoked activation of src tyrosine kinase, resulting in the inhibition of the phosphorylated-ERK1/2 accumulation in the nucleus. 2MeSADP enhanced the gene expression and activity of protein tyrosine phosphatase (PTP), which was responsible for the inhibition of src tyrosine kinase. Thioredoxin reductase, another cytoprotective gene we previously showed to be upregulated by 2MeSADP, also controlled the activity of PTP. Taken together, ATP, acting on P2Y 1 receptors, upregulates the PTP expression and its activity, which counteracts the H2O2-promoted death signaling cascades including ERK1/2 and its upstream signal src tyrosine kinase in astrocytes.
All Science Journal Classification (ASJC) codes
- Cellular and Molecular Neuroscience