Chronic ethanol exposure enhances activating protein-1 transcriptional activity in human neuroblastoma cells.
This study demonstrates a method for studying the effects of ethanol on transcription mediated by activating protein-1 (AP-1). The effects of ethanol on AP-1 activity and on the signaling cascades in this process were investigated by using a reporter gene technique with secreted alkaline phosphatase as the reporter gene coupled to nine DNA AP-1-binding elements. Long-term ethanol exposure (48-72 h) dose dependently enhanced AP-1 transcriptional activity in SH-SY5Y cells. Shorter exposure periods with ethanol did not influence AP-1 transcriptional activity compared with findings for control cells. Inhibition of protein kinase C (PKC) dramatically decreased AP-1 activity in both control and ethanol-exposed cells and abolished the ethanol enhancement. This finding suggests a pivotal role for PKC-coupled signaling in AP-1 transcriptional activity. Phorbol ester stimulation of AP-1 transcriptional activity was not influenced by long-term ethanol exposure. This finding indicates that signaling events upstream of PKC are the targets for ethanol. Mitogen-activated protein kinases ERK and p38 may play a role in ethanol-enhanced AP-1 activity because inhibitors of both enzymes partly reduced the enhancement. The inhibitors also partly blocked phorbol ester-induced AP-1 activation, which demonstrates a function of these mitogen-activated protein kinases downstream of PKC.
Fried
U
U
Department of Medical Neurochemistry, Institute of Laboratory Medicine, Lund University Hospital, 221 85, Lund, Sweden. ulrik.fried@neurokemi.lu.se
Kotarsky
K
K
Alling
C
C
D002492:Central Nervous System Depressants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D017930:Genes, Reporter / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D009447:Neuroblastoma / Q000201:enzymology / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects* / Q000502:physiology; D014407:Tumor Cells, Cultured
D002492:Central Nervous System Depressants; D004791:Enzyme Inhibitors; D018808:Transcription Factor AP-1; D000431:Ethanol; D011493:Protein Kinase C; D020929:Mitogen-Activated Protein Kinase Kinases