title: Polychlorinated biphenyls impair dibutyryl cAMP-induced astrocytic differentiation in rat C6 glial cell line.
abstract: In the central nervous system, alteration of glial cell differentiation can affect brain functions. Polychlorinated biphenyls (PCBs) are persistent environmental chemical contaminants that exert neurotoxic effects in glial and neuronal cells. We examined the effects of a commercial mixture of PCBs, Aroclor1254 (A1254) on astrocytic differentiation of glial cells, using the rat C6 cell line as in vitro model. The exposure for 24 h to sub-toxic concentrations of A1254 (3 or 9 μM) impaired dibutyryl cAMP-induced astrocytic differentiation as showed by the decrease of glial fibrillary acidic protein (GFAP) protein levels and inhibition in change of cell morphology toward an astrocytic phenotype. The A1254 inhibition was restored by the addition of a protein kinase C (PKC) inhibitor, bisindolylmaleimide (bis), therefore indicating that PCBs disturbed the cAMP-induced astrocytic differentiation of C6 cells via the PKC pathway. The phosphorylation of signal transducer and activator of transcription 3 (STAT3) is essential for cAMP-induced transcription of GFAP promoter in C6 cells. Our results indicated that the exposure to A1254 (3 or 9 μM) for 24 h suppressed cAMP-induced STAT3 phosphorylation. Moreover, A1254 reduced cAMP-dependent phosphorylation of STAT3 requires inhibition of PKC activity. Together, our results suggest that PCBs induce perturbation in cAMP/PKA and PKC signaling pathway during astrocytic differentiation of glial cells.
authors.affiliation: Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Via P. Bucci, Arcavacata di Rende, Cosenza (CS) 87036, Italy.
authors.forename: Annagrazia
authors.initials: A
authors.lastname: Adornetto
authors.forename: Valentina
authors.initials: V
authors.lastname: Pagliara
authors.forename: Gianfranco Di
authors.initials: GD
authors.lastname: Renzo
authors.forename: Rosaria
authors.initials: R
authors.lastname: Arcone
keywords: A1254, Aroclor 1254; Aroclor1254; Astrocytic differentiation; C6 glial cell line; CNS, central nervous system; CRE, cAMP responsive element; CREB, cAMP-response element binding protein; DAPI, 4′,6-diamidino-2-phenylindole; DMEM, Dulbecco’s Modified Eagle’s Medium; DMSO, dimethyl sulfoxide; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GFAP, glial fibrillary acidic protein; Glial fibrillary acidic protein (GFAP); MTT, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide; NMDA, N-methyl-d-aspartate; PCBs, polychlorinated biphenyls; PKA, protein kinase A; PKC, protein kinase C; Protein kinase C (PKC); ROS, reactive oxygen species; STAT3, signal transducer and activator of transcription 3; Signal transducer and activator of transcription 3 (STAT3); TRE, CRE transcriptional response element; bis, 2-[1-(3-dimethylamino-propyl)indol-3-yl]-3-(indol-3-yl) maleimide; dbcAMP, N6,2′-O-dibutyryl cAMP; nNOS, neuronal nitric oxide