Adenosine A1 receptor-mediated transactivation of the EGF receptor produces a neuroprotective effect on cortical neurons in vitro
Abstract
Aim: To understand the mechanism of the transactivation of the epidermal growth factor receptor (EGFR) mediated by the adenosine A1 receptor (A1R).
Methods: Primary cultured rat cortical neurons subjected to oxygen-glucose deprivation (OGD) and HEK293/A1R cells were treated with the A1R-specific agonist N6-cyclopentyladenosine (CPA). Phospho-EGFR, Akt, and ERK1/2 were observed by Western blot. An interaction between EGFR and A1R was detected using immunoprecipitation and immunocytochemistry.
Results: The A1R agonist CPA causes protein kinase B (Akt) activation and protects primary cortical neurons from oxygen-glucose deprivation (OGD) insult. A1R and EGFR co-localize in the membranes of neurons and form an immunocomplex. A1R stimulation induces significant EGFR phosphorylation via a PI3K and Src kinase signaling pathway; this stimulation provides a neuroprotective effect in cortical neurons. CPA leads to sustained phosphorylation of extracellularly regulated kinases 1 and 2 (ERK1/2) in cortical neurons, but only to transient phosphorylation in HEK 293/A1R cells. The response to the A1R agonist is mediated primarily through EGFR transactivation that is dependent on pertussis toxin (PTX)-sensitive Gi protein and metalloproteases in HEK 293/A1R.
Conclusion: A1R-mediated EGFR transactivation confers a neuroprotective effect in primary cortical neurons. PI3 kinase and Src kinase play pivotal roles in this response.
Keywords:
Methods: Primary cultured rat cortical neurons subjected to oxygen-glucose deprivation (OGD) and HEK293/A1R cells were treated with the A1R-specific agonist N6-cyclopentyladenosine (CPA). Phospho-EGFR, Akt, and ERK1/2 were observed by Western blot. An interaction between EGFR and A1R was detected using immunoprecipitation and immunocytochemistry.
Results: The A1R agonist CPA causes protein kinase B (Akt) activation and protects primary cortical neurons from oxygen-glucose deprivation (OGD) insult. A1R and EGFR co-localize in the membranes of neurons and form an immunocomplex. A1R stimulation induces significant EGFR phosphorylation via a PI3K and Src kinase signaling pathway; this stimulation provides a neuroprotective effect in cortical neurons. CPA leads to sustained phosphorylation of extracellularly regulated kinases 1 and 2 (ERK1/2) in cortical neurons, but only to transient phosphorylation in HEK 293/A1R cells. The response to the A1R agonist is mediated primarily through EGFR transactivation that is dependent on pertussis toxin (PTX)-sensitive Gi protein and metalloproteases in HEK 293/A1R.
Conclusion: A1R-mediated EGFR transactivation confers a neuroprotective effect in primary cortical neurons. PI3 kinase and Src kinase play pivotal roles in this response.