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

(1)血管紧张素Ⅱ诱导肿瘤坏死因子-α产生的分子机制我们研究了血管紧张素Ⅱ和脂多糖上调肿瘤坏死因子-α基因表达的分子机制。有或没有特异性抗体的凝胶迁移率改变竞争分析表明，内毒素增加了Sp1和Sp3与Sp1结合部位的结合，而Egr-1则不重要。突变分析证实，对α的反应依赖于启动子中的Sp1位点，而Cre结合位点对AngiI的刺激作用是必不可少的，而Cre结合位点是激活-α基因的关键。我们的结论是，由于肿瘤坏死因子-α基因的表达是由血管紧张素Ⅱ或脂多糖通过肿瘤坏死因子-α启动子中不同的顺式作用序列和不同的转录因子而转录激活的，所以在心力衰竭或心肌肥厚与感染性疾病之间产生肿瘤坏死因子的机制不同。(2)人外周血单核细胞产生肿瘤坏死因子-α的机制。ET-1以浓度和时间依赖的方式显著增加肿瘤坏死因子-α的表达。因此，内皮素-1和/或血管紧张素Ⅱ对单个核细胞的激活可能在心力衰竭和/或心脏肥厚的发生发展中起重要作用。我们认为，这些关于心力衰竭或心肌肥厚中肿瘤坏死因子-α产生的微小研究对于开发特定的药物是必要的。

(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.