Department of Pharmacology and BK21 Medical Science Education Center, School of Medicine, Pusan National University, Yangsan, Gyeongnam 626-870, Korea.
Cardiovasc Res. 2010 Nov 1;88(2):352-9. doi: 10.1093/cvr/cvq194. Epub 2010 Jun 15.
5-Lipoxygenase (5-LO) has been suggested to be a modulator of atherosclerotic plaque instability and co-exists with 4-hydroxynonenal (HNE) in macrophages in atherosclerotic lesions. To determine the potential role for HNE in 5-LO expression, the molecular mechanisms of 5-LO expression were evaluated in HNE-stimulated macrophages.
A genomic sequence of the promoter 2.0 kb upstream of the transcription initiation site was amplified, and a series of sequentially deleted fragments were then fused to a luciferase reporter gene. The promoter region 213 bp upstream of the transcription start site was responsible for the HNE-enhanced transcriptional activity of 5-LO. Site-directed mutagenesis of this region showed that the transcription factors, including stimulating protein 1 (Sp1) and nuclear factor-κB (NF-κB), were associated with up-regulation of HNE-induced 5-LO transcription. Moreover, the role of Sp1 and NF-κB in HNE-induced 5-LO expression was confirmed by siRNA knockdown of Sp1 and NF-κB. The HNE-enhanced Sp1 and NF-κB activities were attenuated by SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor, and PD98059, an extracellular signal-regulated kinase (ERK) inhibitor, respectively. In addition, the HNE-enhanced phosphorylation of p38 MAPK and ERK was inhibited by AG1478, an epidermal growth factor receptor (EGFR) antagonist, but not by AG1295, a platelet-derived growth factor receptor (PDGFR) antagonist.
5-LO expression by HNE was regulated at the transcriptional level by the EGFR-mediated activation of Sp1/p38 MAPK and NF-κB/ERK pathways in macrophages, which may lead to the development of therapeutic interventions for regulating 5-LO expression in atherosclerosis.
5-脂氧合酶（5-LO）被认为是动脉粥样硬化斑块不稳定的调节剂，并且与动脉粥样硬化病变中的巨噬细胞中的 4-羟基壬烯醛（HNE）共存。为了确定 HNE 在 5-LO 表达中的潜在作用，评估了 HNE 刺激的巨噬细胞中 5-LO 表达的分子机制。
扩增了转录起始位点上游 2.0kb 的启动子基因组序列，然后将一系列连续缺失的片段融合到荧光素酶报告基因中。转录起始位点上游 213bp 的启动子区域负责 HNE 增强 5-LO 的转录活性。该区域的定点突变显示，转录因子包括刺激蛋白 1（Sp1）和核因子-κB（NF-κB）与 HNE 诱导的 5-LO 转录上调有关。此外，通过 Sp1 和 NF-κB 的 siRNA 敲低证实了 Sp1 和 NF-κB 在 HNE 诱导的 5-LO 表达中的作用。SB203580，一种 p38 丝裂原活化蛋白激酶（MAPK）抑制剂和 PD98059，一种细胞外信号调节激酶（ERK）抑制剂，分别减弱了 HNE 增强的 Sp1 和 NF-κB 活性。此外，AG1478，一种表皮生长因子受体（EGFR）拮抗剂，抑制了 HNE 增强的 p38 MAPK 和 ERK 的磷酸化，但 AG1295，一种血小板衍生生长因子受体（PDGFR）拮抗剂则没有。
HNE 通过 EGFR 介导的 Sp1/p38 MAPK 和 NF-κB/ERK 途径激活调节巨噬细胞中 5-LO 的转录表达，这可能导致调节动脉粥样硬化中 5-LO 表达的治疗干预措施的发展。
