Angiotensin II stimulates transcription of insulin-like growth factor I receptor in vascular smooth muscle cells:: Role of nuclear factor-κB
Angiotensin II stimulates transcription of insulin-like growth factor I receptor in vascular smooth muscle cells:: Role of nuclear factor-κB
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DOI：
10.1210/en.2005-0888
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发表时间：
2006-03-01
期刊：
影响因子：
4.8
通讯作者：
Du, J
中科院分区：
文献类型：
--
作者：
Ma, YW;Zhang, LP;Du, J
IGF-I 受体 (IGF-IR) 表达的增加与血管平滑肌细胞 (VSMC) 的增殖和存活相关。在培养的 VSMC 中，我们报道血管紧张素 II (Ang II) 增加 IGF-IR 的转录和表达。现在，我们发现注入 Ang II 的大鼠肠系膜动脉出现增厚并增加 IGF-IR 表达。为了确定 Ang II 如何转录调节 VSMC 中的 IGF-IR 表达，我们产生了 IGF-IR 启动子的 5' 端缺失，并测量了 VSMC 中 Ang II 诱导的启动子荧光素酶活性。这些启动子序列的活性表明Ang II 响应区位于IGF-IR 启动子的-270 和-135 之间。使用 DNase I 足迹分析，我们鉴定了位于 IGF-IR 启动子同一区域的两个假定的核因子 kappa B (NF-kappa B) 样序列。当我们突变这些 NF-κ B 样位点中的任何一个时，Ang II 诱导的 IGF-IR 启动子活性急剧下降。电泳迁移率凝胶位移、NF-kappa B 抗 p50 超位移和染色质免疫沉淀测定表明 NF-kappa B 的 p65 和 p50 亚基均会与 IGF-IR 启动子中的 Ang II 反应元件结合。当我们阻断Ras/MAPK激酶1通路或抑制性κB激酶通路时，Ang II诱导的IGF-IR启动子活性和IGF-IR蛋白表达均显着下降。我们的结果表明，Ang II 刺激 VSMC 中 IGF-IR 表达的机制涉及 NF-kappa B 与 IGF-IR 启动子中的 NF-kappa B 位点结合，从而通过 Ras/MAPK 激酶 1 和抑制性 kappa B 激酶依赖性途径导致 IGF-IR 表达。由于 IGF-IR 是与肠系膜血管增厚相关的主要因素，因此我们的结果提供了潜在的治疗靶点。
Increased expression of the IGF-I receptor (IGF-IR) is associated with proliferation and survival of vascular smooth muscle cells (VSMCs). In cultured VSMCs, we reported that angiotensin II (Ang II) increases transcription and expression of IGF-IR. Now, we show that mesenteric arteries of rats infused with Ang II develop thickening and increased IGF-IR expression. To determine how Ang II transcriptionally regulates IGF-IR expression in VSMCs, we generated 5'-end deletions of the IGF-IR promoter and measured Ang II-induced promoter-luciferase activity in VSMCs. Activities from these promoter sequences suggested that the Ang II-responsive region is located between -270 and -135 of the IGF-IR promoter. Using a DNase I foot printing analysis, we identified two putative nuclear factor-kappa B (NF-kappa B)-like sequences located in the same region of the IGF-IR promoter. When we mutated either of these NF-kappa B-like sites, Ang II-induced IGF-IR promoter activity decreased sharply. Electrophoretic mobility gel shift, anti-p50 of NF-kappa B supershift and chromatin immunoprecipitation assays demonstrated that both the p65 and p50 subunits of NF-kappa B will bind to this Ang II response element in the IGF-IR promoter. When we blocked the Ras/MAPK kinase 1 pathway or the inhibitory-kappa B kinase pathway, both Ang II-induced IGF-IR promoter activity and expression of IGF-IR protein significantly declined. Our results indicate that the mechanism by which Ang II stimulates IGF-IR expression in VSMCs involves NF-kappa B binding to NF-kappa B sites in the IGF-IR promoter, leading to expression of IGF-IR through both Ras/MAPK kinase 1-and inhibitory-kappa B kinase-dependent pathways. Because IGF- IR is a major factor associated with thickening of mesenteric vessels, our results provide potential therapeutic targets.