Teshima Shigeru, Nakanishi Hideki, Nishizawa Mikio, Kitagawa Katsuhiko, Kaibori Masaki, Yamada Masanori, Habara Kozo, Kwon A-Hon, Kamiyama Yasuo, Ito Seiji, Okumura Tadayoshi
Department of Surgery, Kansai Medical University, Osaka 570-8506, Japan.
J Hepatol. 2004 Apr;40(4):616-23. doi: 10.1016/j.jhep.2003.12.018.
BACKGROUND/AIMS: Nuclear translocation and DNA binding of NF-kappaB is essential, as interleukin-1beta (IL-1beta) stimulates the induction of inducible nitric oxide synthase (iNOS) gene expression in hepatocytes. However, recent evidence indicates that the activation of NF-kappaB is not sufficient to induce the NF-kappaB-dependent transcription, and the existence of a second signaling is postulated.
Primary cultured hepatocytes were treated with IL-1beta, and the expression of iNOS and type 1 IL-1 receptor (IL-1R1) was analyzed in the presence of antisense of IL-1R1, phosphatidylinositol 3-kinase (PI3K) inhibitor, proteasome inhibitor and hypoxia. Moreover, the activities of Akt and NF-kappaB were recorded and the cotransfection was carried out.
Antisense experiment revealed that IL-1R1 was required for iNOS transcription. IL-1beta markedly stimulated the induction of IL-1R1, which preceded the induction of iNOS. The IL-1R1 induction was found to be PI3K/Akt-dependent but NF-kappaB-independent. The up-regulation of IL-1R1 was associated with the second activation of Akt, which accelerated the phosphorylation of NF-kappaB p65 subunit. Cotransfection experiments revealed that Akt increased the transcriptional activity of iNOS gene promoter.
These results indicate that the up-regulation of IL-1R1 in concert with the activation of NF-kappaB is required for the transcriptional activation of iNOS gene.
背景/目的：核因子-κB（NF-κB）的核转位和DNA结合至关重要，因为白细胞介素-1β（IL-1β）可刺激肝细胞中诱导型一氧化氮合酶（iNOS）基因表达的诱导。然而，最近的证据表明，NF-κB的激活不足以诱导依赖NF-κB的转录，因此推测存在第二种信号传导。
用IL-1β处理原代培养的肝细胞，并在存在IL-1受体1（IL-1R1）反义寡核苷酸、磷脂酰肌醇3-激酶（PI3K）抑制剂、蛋白酶体抑制剂和缺氧的情况下分析iNOS和1型IL-1受体（IL-1R1）的表达。此外，记录Akt和NF-κB的活性并进行共转染。
反义实验表明，iNOS转录需要IL-1R1。IL-1β显著刺激IL-1R1的诱导，这先于iNOS的诱导。发现IL-1R1的诱导是PI3K/Akt依赖性的，但与NF-κB无关。IL-1R1的上调与Akt的第二次激活相关，后者加速了NF-κB p65亚基的磷酸化。共转染实验表明，Akt增加了iNOS基因启动子的转录活性。
这些结果表明，iNOS基因的转录激活需要IL-1R1的上调与NF-κB的激活协同作用。
