title: The GABABpositive allosteric modulators CGP7930 and GS39783 stimulate ERK1/2 signalling in cells lacking functional GABABreceptors.
abstract: The present study shows that the GABABpositive allosteric modulators (PAMs) CGP7930 and GS39783 stimulate extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) signalling in cells that do not express functional GABABreceptors. In human SH-SY5Y neuroblastoma cells, CGP7930 and GS39783 induced a time- and concentration-dependent increase in ERK1/2 phosphorylation with potencies similar to those displayed as GABABPAMs. Conversely, γ-aminobutyric acid and the GABABreceptor agonists (-)baclofen and SKF97541 were completely inactive. CGP7930 and GS39783 enhanced the nuclear localization of phospho-ERK1/2 and CGP7930 promoted the phosphorylation of the transcription factors Elk-1 and CREB. CGP7930-induced ERK1/2 stimulation was insensitive to pertussis toxin, the Gq/11antagonist YM254890 and the phospholipase C-β inhibitor U-73122, but was completely blocked by the MEK1/2 inhibitor PD98059. Inhibition of insulin-like growth factor-1, platelet--derived growth factor, phosphoinositide 3-kinase and Akt activities potentiated CGP7930-induced ERK1/2 phosphorylation. CGP7930 enhanced the phosphorylation of myristoylated alanine-rich protein kinase C (PKC) substrate and inhibition of PKC attenuated the ERK1/2 stimulation. Over-expression of N17Ras, a dominant negative mutant of c-Ras, or inhibition of c-Raf by GW5074 partially antagonized CGP7930-induced ERK1/2 activation. CGP7930 enhanced the phosphorylation of transforming growth factor-β-activated kinase 1 (TAK-1) and TAK-1 inhibition by 5Z-7-oxozeaenol reduced CGP7930-induced ERK1/2 phosphorylation. CGP7930 activated ERK1/2 in CHO-K1 fibroblasts, which lack endogenous GABABreceptors, but not in HEK-293 cells, indicating that the response displayed cell type specificity. These data demonstrate that CGP7930 and GS39783 can trigger ERK1/2 signalling, a critical modulator of mood and drug addiction, independently of an action on GABABreceptors.
authors.affiliation: Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy. Electronic address: molianas@unica.it.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Olianas
authors.affiliation: Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Dedoni
authors.affiliation: Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Onali
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003517:Cyclopentanes / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D018080:Receptors, GABA-B / Q000172:deficiency* / Q000378:metabolism*; D013997:Time Factors; D048490:raf Kinases / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D003517:Cyclopentanes; D020930:MAP Kinase Kinase Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010636:Phenols; D011493:Protein Kinase C; D011743:Pyrimidines; D018080:Receptors, GABA-B; D048490:raf Kinases; D018631:ras Proteins; D000099151:MAP Kinase Kinase Kinase 7; C438607:2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethylpropyl)phenol; C478058:N,N'-dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine
keywords: (-)-baclofen (PubChem CID: 44602); 5Z-7-oxozeaenol (PubChem CID: 9863776); CGP54626 (PubChem CID: 197584); CGP55845 (PubChem CID: 5311042); CGP7930 (PubChem CID: 5024764); Extracellular signal-regulated protein kinases 1 and 2; GABA(B) receptor; GS39783 (PubChem CID: 6604928); GW5074 (PubChem CID: 5924208); Go 6850 (PubChem CID: 2396); Human SH-SY5Y neuroblastoma cells; Positive allosteric modulators; SKF97541 (PubChem CID: 5230); phorbol 12-myristate 13 acetate (PubChem CID: 27924)