Geller D A, Nguyen D, Shapiro R A, Nussler A, Di Silvio M, Freeswick P, Wang S C, Tweardy D J, Simmons R L, Billiar T R
Department of Surgery, University of Pittsburgh, PA 15261.
Surgery. 1993 Aug;114(2):235-42.
Interferon regulatory factor-1 (IRF-1) is a transcriptional factor originally cloned from fibroblasts that activates interferons and certain interferon-responsive genes. Because IRF-1 is an "early-immediate" nuclear protein, it can function acutely after trauma or septic stimuli. We have identified IRF-1 expression in hepatocytes in vivo in sepsis. The purpose of this study was to characterize the cytokine signals that up-regulate IRF-1 messenger RNA (mRNA) in cultured hepatocytes.
Rat hepatocytes were isolated by in situ collagenase perfusion and stimulated in vitro with cytokines. IRF-1 mRNA levels were determined by Northern blot hybridization with a DNA probe for hepatocyte IRF-1 generated with reverse transcription polymerase chain reaction with custom-designed oligonucleotide primers based on the known sequence for T-cell IRF-1.
Northern blot of hepatocyte RNA showed a single IRF-1 mRNA band at approximately 2.4 Kb. The mRNA levels were markedly up-regulated (vs control hepatocytes) 2 hours after in vitro stimulation with the cytokines interferon-gamma (17-fold), tumor necrosis factor-alpha (3-fold), and interleukin-1 beta (2-fold). Lipopolysaccharide had no direct effect.
The results showed that IRF-1 is up-regulated in hepatocytes primarily in response to interferon-gamma and to a lesser extent after tumor necrosis factor-alpha or interleukin-1 beta stimulation. This suggests that IRF-1 plays a role in regulating liver gene expression in sepsis; however, the specific genes controlled by IRF-1 remain to be determined.
干扰素调节因子-1（IRF-1）是一种最初从成纤维细胞中克隆出的转录因子，可激活干扰素及某些干扰素反应基因。由于IRF-1是一种“早期即刻”核蛋白，它可在创伤或脓毒症刺激后迅速发挥作用。我们已在脓毒症体内的肝细胞中鉴定出IRF-1的表达。本研究的目的是确定在培养的肝细胞中上调IRF-1信使核糖核酸（mRNA）的细胞因子信号。
通过原位胶原酶灌注分离大鼠肝细胞，并在体外使用细胞因子进行刺激。使用基于T细胞IRF-1已知序列的定制寡核苷酸引物，通过逆转录聚合酶链反应生成用于肝细胞IRF-1的DNA探针，通过Northern印迹杂交测定IRF-1 mRNA水平。
肝细胞RNA的Northern印迹显示在约2.4 kb处有一条单一的IRF-1 mRNA条带。在用细胞因子干扰素-γ（17倍）、肿瘤坏死因子-α（3倍）和白细胞介素-1β（2倍）体外刺激2小时后，mRNA水平显著上调（与对照肝细胞相比）。脂多糖无直接作用。
结果表明，IRF-1在肝细胞中主要因干扰素-γ而上调，在肿瘤坏死因子-α或白细胞介素-1β刺激后上调程度较小。这表明IRF-1在脓毒症中调节肝脏基因表达中起作用；然而，由IRF-1控制的具体基因仍有待确定。
