Dual mechanisms for ethanol-induced inhibition of monocyte chemotactic protein-3 mRNA expression in activated glial cells.
The differential display of mRNA technique was used to screen the expressed genes in control and 50 mM chronic ethanol-treated rat C6 glial cells, with and without activation by lipopolysaccharide (LPS) combined with phorbol 12-myristate 13-acetate (PMA). One differentially expressed transcript was identified as that corresponding to the chemokine monocyte chemotactic protein (MCP)-3. MCP-3 is a broadly active chemokine that functions in chemoattraction and activation of monocytes, T lymphocytes, eosinophils, basophils, natural killer cells, and dendritic cells. Steady-state MCP-3 mRNA levels were elevated 6-fold after 24-h stimulation of control cells but less than 3-fold after stimulation of 9-day chronic ethanol-exposed cells. One- and 5-day exposures to 50 mM ethanol were not effective at reducing steady-state MCP-3 mRNA levels in stimulated cells, whereas 1-day exposure to >150 mM ethanol was effective. Stimulation with tumor necrosis factor-alpha elevated MCP-3 mRNA in C6 glial cells to a lesser extent than with LPS plus PMA, but the effects of ethanol were consistent. To gain insight into possible mechanisms for ethanol-induced reductions in steady-state MCP-3 mRNA, additional studies examined nuclear MCP-3 RNA levels and MCP-3 mRNA degradation. MCP-3 RNA content was greatly reduced in isolated nuclei from acute and chronic ethanol-exposed cells, suggesting transcriptional inhibition. On the other hand, acute ethanol exposure enhanced degradation of preexisting MCP-3 mRNA, indicating message destabilization. Thus, the results are consistent with a dual mechanism for ethanol-induced reductions in steady-state MCP-3 mRNA levels.
Ren
Liqiang
L
Department of Pharmacology, Alcohol and Brain Research Laboratory, Texas Tech University Health Sciences Center, Lubbock 79430, USA.
Syapin
Peter J
PJ
D000818:Animals; D054410:Chemokine CCL7; D016207:Cytokines; D004926:Escherichia coli; D000431:Ethanol / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D005910:Glioma; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D018945:Monocyte Chemoattractant Proteins / Q000235:genetics*; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured
C515452:Ccl7 protein, rat; D054410:Chemokine CCL7; D016207:Cytokines; D008070:Lipopolysaccharides; D018945:Monocyte Chemoattractant Proteins; D012333:RNA, Messenger; D000431:Ethanol