The GABAB positive allosteric modulator (PAM) CGP7930 potentiates GABAB receptor signaling in transfected cells (Urwyler et al. Mol. Pharmacol. 60, 963971, 2001) and rat and human brain (Onali et al., Eur. J. Pharmacol. 471, 7784, 2003; Olianas et al., Neurochem. Int. 46, 149158, 2005). A number of behavioral studies have also shown that CGP7930 exerts anxiolytic effects and reduces selfadministration of drugs of abuse (Adams and Lawrence, CNS Drug Rev. 13, 308316, 2007). However, little is known on whether this drug can affect neuronal signaling independently of GABAB receptor activity. In the present study we report that in human SHSY5Y neuroblastoma cells, CGP7930 (30 μM) induced a rapid increase of dual phosphorylation (activation) of ERK1/2, which reached a maximum at 15 min and lasted for at least 60 min. CGP7930 also triggered CREB phosphorylation at Ser133 with a similar kinetic profile. Under the same experimental conditions, the GABAB receptor agonist () baclofen (100 μM) failed to affect ERK1/2 phosphorylation, and when combined with CGP7930, it did not elicit any further ERK1/2 stimulation. CGP7930induced ERK1/2 phosphorylation was not prevented by cell pretreatment with either the GABAB receptor antagonists CGP55845A and CGP54626, the Gi/oreceptor uncoupler pertussis toxin, the Gq/11 antagonist YM254890, or the tyrosine kinase inhibitor genistein. Conversely, it was completely blocked by the MEK inhibitor PD98059 and significantly attenuated by the protein kinase C inhibitors Go 6983 and bisindolylmaleimide I. CGP7930 (30 μM) was also found to stimulate ERK1/2 phosphorylation in CHOK1 cells, which do not express GABAB receptors. However, CGP7930 (1100 μM) had no effect in HEK293 cells, indicating that ERK1/2 activation was not a generalized cellular response to the PAM. These data indicate that CGP7930 can affect ERK1/2 signaling, which is known to be involved in the control of mood and drug addiction, independently of increased GABAB receptor activity.
Evidence that the GABAB positive allosteric modulator CGP7930 activates MAPK cascade independently of GABAB receptor
ONALI, PIER LUIGI;DEDONI, SIMONA;OLIANAS, MARIA CONCETTA
2015-01-01
Abstract
The GABAB positive allosteric modulator (PAM) CGP7930 potentiates GABAB receptor signaling in transfected cells (Urwyler et al. Mol. Pharmacol. 60, 963971, 2001) and rat and human brain (Onali et al., Eur. J. Pharmacol. 471, 7784, 2003; Olianas et al., Neurochem. Int. 46, 149158, 2005). A number of behavioral studies have also shown that CGP7930 exerts anxiolytic effects and reduces selfadministration of drugs of abuse (Adams and Lawrence, CNS Drug Rev. 13, 308316, 2007). However, little is known on whether this drug can affect neuronal signaling independently of GABAB receptor activity. In the present study we report that in human SHSY5Y neuroblastoma cells, CGP7930 (30 μM) induced a rapid increase of dual phosphorylation (activation) of ERK1/2, which reached a maximum at 15 min and lasted for at least 60 min. CGP7930 also triggered CREB phosphorylation at Ser133 with a similar kinetic profile. Under the same experimental conditions, the GABAB receptor agonist () baclofen (100 μM) failed to affect ERK1/2 phosphorylation, and when combined with CGP7930, it did not elicit any further ERK1/2 stimulation. CGP7930induced ERK1/2 phosphorylation was not prevented by cell pretreatment with either the GABAB receptor antagonists CGP55845A and CGP54626, the Gi/oreceptor uncoupler pertussis toxin, the Gq/11 antagonist YM254890, or the tyrosine kinase inhibitor genistein. Conversely, it was completely blocked by the MEK inhibitor PD98059 and significantly attenuated by the protein kinase C inhibitors Go 6983 and bisindolylmaleimide I. CGP7930 (30 μM) was also found to stimulate ERK1/2 phosphorylation in CHOK1 cells, which do not express GABAB receptors. However, CGP7930 (1100 μM) had no effect in HEK293 cells, indicating that ERK1/2 activation was not a generalized cellular response to the PAM. These data indicate that CGP7930 can affect ERK1/2 signaling, which is known to be involved in the control of mood and drug addiction, independently of increased GABAB receptor activity.
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