Reddy M A, Shukla S D
Department of Pharmacology, University of Missouri School of Medicine, Columbia 65212, USA.
Biochem Pharmacol. 1996 Mar 8;51(5):661-8. doi: 10.1016/s0006-2952(95)02239-2.
Ethanol modulates agonist responses in liver cells, which are the major site of ethanol metabolism. Mitogen-activated protein kinases (MAPKs) are involved in the integration of multiple signaling pathways leading to cellular responses. However, the effect of ethanol on liver MAPK is not known. To this end, we studied the activation of MAPK in a normal mouse embryonic liver cell line (BNLCL2) after acute and chronic exposure to ethanol. Acute exposure to ethanol (0-400 mM) for 1 hr had no effect on either basal or serum- and phorbol-12-myristate-13-acetate (PMA)-stimulated MAPK activity. Chronic exposure to ethanol (0-400 mM) for 24 hr potentiated the stimulation of MAPK by serum, PMA, or thrombin. Maximum potentiation was observed with 200 mM ethanol (2- to 3-fold higher than control cells). Chronic exposure had no significant effect on epidermal growth factor-stimulated MAPK activity. In-gel MAPK assay of cytosolic extracts and of immunoprecipitates obtained with MAPK antibody demonstrated that ethanol potentiated the activation of both p42 and p44 MAPKs. When cells were pretreated with pertussis toxin, the potentiation by ethanol was abolished. It is concluded that ethanol potentiates MAPK in fetal liver cells by a pertussis toxin-sensitive G-protein-dependent mechanism.
乙醇可调节肝细胞中的激动剂反应，肝细胞是乙醇代谢的主要场所。丝裂原活化蛋白激酶（MAPKs）参与导致细胞反应的多种信号通路的整合。然而，乙醇对肝脏MAPK的影响尚不清楚。为此，我们研究了正常小鼠胚胎肝细胞系（BNLCL2）在急性和慢性暴露于乙醇后MAPK的激活情况。急性暴露于乙醇（0 - 400 mM）1小时对基础或血清及佛波酯-12-肉豆蔻酸酯-13-乙酸酯（PMA）刺激的MAPK活性均无影响。慢性暴露于乙醇（0 - 400 mM）24小时可增强血清、PMA或凝血酶对MAPK的刺激作用。在200 mM乙醇时观察到最大增强作用（比对照细胞高2至3倍）。慢性暴露对表皮生长因子刺激的MAPK活性无显著影响。对细胞溶质提取物和用MAPK抗体获得的免疫沉淀物进行凝胶内MAPK测定表明，乙醇增强了p42和p44 MAPKs的激活。当细胞用百日咳毒素预处理时，乙醇的增强作用被消除。结论是，乙醇通过百日咳毒素敏感的G蛋白依赖性机制增强胎儿肝细胞中的MAPK。
