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EVIDENCE THAT CA2+ SIGNALING AND TRANSCRIPTION FACTOR (CREB) ACTIVITIES STIMULATED BY POLYCHLORINATED BIPHENYLS ARE LOCALIZED TO DEVELOPING NEURONS.
Citation:
Inglefield, J R., W R. Mundy, AND T J. Shafer. EVIDENCE THAT CA2+ SIGNALING AND TRANSCRIPTION FACTOR (CREB) ACTIVITIES STIMULATED BY POLYCHLORINATED BIPHENYLS ARE LOCALIZED TO DEVELOPING NEURONS. Presented at Experimental Biology, Orlando, FL, March 31-April 4, 2001.
Description:
Using a mixed culture of neonatal cortical cells, we have demonstrated that the polychlorinated biphenyl (PCB) mixture Aroclor 1254 (A1254) induces complex Ca2+i signals involving multiple receptors/channels (Inglefield and Shafer, J.Pharm.Exp.Ther. 295:105) and also activates/ phosphorylates cAMP response element binding protein (CREB; assessed globally with a Western blot). Cell death does not result from PCB exposure in these immature cells. We sought to determine the cell type(s) responding to PCB exposure with altered Ca2+ signaling activity and CREB phosphorylation. As positive controls, glutamate (100 mM) or pro-glutamatergic 0 Mg2+ solutions were utilized. With single cell fura-2 fluorescence imaging, the A1254 and glutamatergic treatments each dramatically increased Ca2+ signaling selectively in cells having a neuronal appearance. Like A1254 (10 mM), 30-40 min of the positive controls increased levels of phospho-CREB protein in Western blots of cultures maintained 6 days in vitro (DIV). As a follow-up to the Western blot studies, DIV6 cultures were immunostained for both phospho-CREB and the selective neuronal marker, MAP-2, to determine whether neurons alone or in combination with the supporting glia are activated by PCBs or the glutamatergic stimuli. There were constitutive levels of phospho-CREB in untreated developing neurons and glia. Compared to controls, the number of neurons containing activated CREB was increased (from ~37% to ~75% of the MAP2-positive cells) by 40 min of either 10 mM A1254 or 100 mM glutamate, while MAP2-negative (astro)glia did not undergo change. These results support CREB as a common mediator of neuronal signals that are initiated by different signaling stimuli, be they PCB- or glutamate-driven. This abstract does not necessarily reflect US EPA policy.