Chen J Q, Ström A, Gustafsson J A, Morgan E T
Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Mol Pharmacol. 1995 May;47(5):940-7.
Hepatic expression of various members of the cytochrome P-450 (CYP) superfamily is suppressed during inflammatory responses. We have shown that the specific expression of P-450 2C11 in male rat liver is suppressed transcriptionally by endotoxin treatment. To investigate the molecular mechanisms underlying this phenomenon, we studied the effects of the inflammatory cytokines interleukin (IL)-1, IL-6, tumor necrosis factor-alpha (TNF), interferon (IFN)-alpha, and IFN-gamma on the expression of P-450 2C11 and the mRNAs of two typical acute-phase protein genes, alpha 1-acid glycoprotein (AGP) and fibrinogen, in primary hepatocyte cultures. IL-1, IL-6, TNF, and IFN-alpha all suppressed P-450 2C11 mRNA, whereas IFN-gamma had no effect. IL-1 and TNF were more effective than IL-6 in the suppression of P-450 2C11 mRNA. Whereas IL-1 and IL-6 effects on P-450 2C11 were accompanied by induction of AGP and fibrinogen mRNAs, IFN-alpha and TNF treatments had no effects on AGP. The suppression of P-450 2C11 and the induction of AGP by IL-1 showed similar time courses. The combination of IL-1 and IL-6 showed additivity in suppression of P-450 2C11, at maximally effective concentrations of cytokines. The effects of IL-1 on P-450 2C11 and AGP expression were blocked by IL-1 receptor antagonist protein. We also studied the effects of IL-1 and IL-6 on the transient expression of chloramphenicol acetyl-transferase reporter gene constructs containing 200 or 1287 base pairs of the 5' flanking region of the CYP2C11 gene, transfected into primary hepatocytes. The chloramphenicol acetyltransferase activities in cells transfected with the 200-base pair construct were reduced to about 33% and 58% of control levels by treatment with IL-1 or IL-6, respectively, suggesting that sequences important for cytokine down-regulation lie within the proximal promoter region of the CYP2C11 gene.
细胞色素P - 450（CYP）超家族各成员的肝脏表达在炎症反应期间受到抑制。我们已经表明，内毒素处理可在转录水平上抑制雄性大鼠肝脏中P - 450 2C11的特异性表达。为了研究这一现象背后的分子机制，我们在原代肝细胞培养物中研究了炎性细胞因子白细胞介素（IL）-1、IL - 6、肿瘤坏死因子 - α（TNF）、干扰素（IFN）-α和IFN - γ对P - 450 2C11表达以及两个典型急性期蛋白基因α1 - 酸性糖蛋白（AGP）和纤维蛋白原mRNA表达的影响。IL - 1、IL - 6、TNF和IFN - α均抑制P - 450 2C11 mRNA，而IFN - γ无此作用。在抑制P - 450 2C11 mRNA方面，IL - 1和TNF比IL - 6更有效。虽然IL - 1和IL - 6对P - 450 2C11的作用伴随着AGP和纤维蛋白原mRNA的诱导，但IFN - α和TNF处理对AGP无影响。IL - 1对P - 450 2C11的抑制和对AGP的诱导显示出相似的时间进程。在细胞因子的最大有效浓度下，IL - 1和IL - 6联合使用对P - 450 2C11的抑制具有相加作用。IL - 1受体拮抗剂蛋白可阻断IL - 1对P - 450 2C11和AGP表达的影响。我们还研究了IL - 1和IL - 6对转染到原代肝细胞中的含有CYP2C11基因5'侧翼区200或1287个碱基对的氯霉素乙酰转移酶报告基因构建体瞬时表达的影响。用IL - 1或IL - 6处理后，转染200碱基对构建体的细胞中的氯霉素乙酰转移酶活性分别降至对照水平的约33%和58%，这表明细胞因子下调的重要序列位于CYP2C11基因的近端启动子区域内。
