Aerts I, Grobben B, Van Ostade X, Slegers H. Cyclic AMP-dependent down regulation of ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) in rat C6 glioma.
Eur J Pharmacol 2010;
654:1-9. [PMID:
21168404 DOI:
10.1016/j.ejphar.2010.11.031]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 11/11/2010] [Accepted: 11/15/2010] [Indexed: 11/16/2022]
Abstract
In this communication, we demonstrate that an increase in intracellular cAMP by 1) addition of dibutyrylic cAMP (dbcAMP), a membrane-permeable cAMP-analogue, or 2) activation of the β-adrenoceptor with (-)-isoproterenol, down regulates the levels of ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) mRNA, NPP1 protein and ecto-NPPase activity in rat C6 glioma cells. DbcAMP and (-)-isoproterenol inhibit NPP1 expression in a time and dose-dependent manner. After 48h of stimulation, 1mM dbcAMP or 5μM (-)-isoproterenol decreases the amount of NPP1 protein by 75±3% and 81±1% respectively. Contrary to down regulation of NPP1, we observe an up regulation of glial fibrillary acidic protein (GFAP), a differentiation marker for astrocytic cells. Using specific inhibitors and activators, we have shown that Ca(2+), PKA, PI 3-K/PKB/GSK-3, Epac/Rap1/PP2A and MAP kinase modules are not involved in the inhibition of NPP1 gene expression. The transcription factor c-jun is significantly reduced while c-fos becomes up regulated after cAMP elevation. However an electrophoretic mobility shift assay with the activator protein-1 motif present in the promoter of the rat NPP1 gene indicates that this motif is not involved in the cAMP-dependent inhibition of NPP1 expression. In conclusion, these results indicate that intracellular cAMP levels regulate the expression of NPP1 in rat C6 glioma cells by a signalling pathway that is different from the GFAP signal transduction pathway.
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