Regulation of the tumor necrosis factor-α promoter in the development of heart failure

（1）血管紧张素II（angiotensin II，ANGII）诱导肿瘤坏死因子-α（tumor necrosis factor-α，TNF-α）产生的分子机制我们研究了血管紧张素II（angiotensin II，ANGII）和脂多糖（lipopolysaccharide，LPS）上调TNF-α基因表达的分子机制。竞争分析电泳迁移率变动分析与无特异性抗体表明，LPS增加的Sp1和Sp3的Sp1结合位点，而Egr-1是不重要的。在ANGII中，ATF-2/c-jun与CRE位点的结合是TNF-α基因诱导所必需的; Ets和NF-κB都不是必需的。突变分析证实，对LPS的应答依赖于TNF-α启动子中的Sp1位点，而CRE结合位点是ANGII刺激所必需的。我们的结论是，由于TNF-α基因表达是由ANGII或LPS通过TNF-α启动子中不同的顺式作用序列和不同的转录因子转录激活的，因此诱导TNF产生的机制在心力衰竭或心脏肥大和感染性疾病之间是不同的。（2）人外周血单个核细胞产生TNF-α的机制ET-1可显著增加TNF-α mRNA的表达，并呈浓度和时间依赖性。因此，内皮素-1和/或血管紧张素Ⅱ激活单核细胞可能在心力衰竭和/或心肌肥厚的发生发展中起重要作用，我们认为，对心力衰竭和/或心肌肥厚中TNF-α产生的详细研究对于开发特异性药物是必要的。

(1)Molecular mechanisms of the tumor necrosis factor-α (TNF-α) production by angiotensin II (ANGII)We examined the molecular mechanisms by which ANGII and lipopolysaccharide (LPS) up-regulate TNF-α gene expression. Competition analysis by electrophoretic mobility shift assay with and without specific antibodies showed that LPS increased binding of Sp1 and Sp3 to the Sp1 binding site, while Egr-1 was unimportant. With ANGII, binding of ATF-2/c-jun to the CRE site was required for TNF-α gene induction ; neither Ets nor NF-κB was essential.Mutation analysis confirmed that response to LPS relied upon the Sp1 site in the TNF-α promoter, while the CRE binding site was essential to stimulation by ANGII. We concluded that since TNF-α gene expression is transcriptionaly activated by ANGII or LPS via different cis-acting sequences in the TNF-α promoter and different transcriptional factors, mechanisms inducing TNF production differ between heart failure or cardiac hypertrophy and infectious disease.(2)Mechanisms of the TNF-α production in the human preripheral mononuclear cellsWe examined the production of TNF-α by endothelin-1 in the human peripheral mononuclear cells. Endothelin-1 significantly increased the TNF-α mRNA expression by the concentration-and time-dependent manner. Thus, the activation of mononuclear cells by endothelin-1 and/or ANGII may be important for the development of heart failure and/or cardiac hypertrophy.We believe that these minute study for the TNF-α production in heart failure or cardiac hypertrophy are necessary for the development of specific drugs.