Institute of Cardiovascular & Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
Br J Pharmacol. 2011 Jul;163(5):948-63. doi: 10.1111/j.1476-5381.2011.01305.x.
Increased pulmonary vascular remodelling, pulmonary arterial pressure and pulmonary vascular resistance characterize the development of pulmonary arterial hypertension (PAH). Activation of the Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)1/2 is thought to play an important role in PAH and Raf-1 kinase inhibitor protein (RKIP), negatively regulates this pathway. This study investigated whether genetic deletion of RKIP (and hence ERK1/2 up-regulation) resulted in a pulmonary hypertensive phenotype in mice and investigated a role for RKIP in mitogen-regulated proliferative responses in lung fibroblasts.
Pulmonary vascular haemodynamics and remodelling were assessed in mice genetically deficient in RKIP (RKIP-/-) after 2 weeks of either normoxia or hypoxia. Immunoblotting and immunohistochemistry were used to examine phosphorylation of Raf-1, RKIP and ERK1/2 in mouse pulmonary arteries. In vitro, RKIP inhibition of mitogen signalling was analysed in CCL39 hamster lung fibroblasts.
RKIP-/- mice demonstrated elevated indices of PAH and ERK1/2 phosphorylation compared with wild-type (WT) mice. Hypoxic RKIP-/- mice exhibited exaggerated PAH indices. Hypoxia increased phosphorylation of Raf-1, RKIP and ERK1/2 in WT mouse pulmonary arteries and Raf-1 phosphorylation in RKIP-/- mouse pulmonary arteries. In CCL39 cells, inhibition of RKIP potentiated mitogen-induced proliferation and phosphorylation of RKIP, and Raf-1.
The lack of RKIP protein resulted in a pulmonary hypertensive phenotype, exaggerated in hypoxia. Hypoxia induced phosphorylation of RKIP signalling elements in WT pulmonary arteries. RKIP inhibition potentiated mitogen-induced proliferation in lung fibroblasts. These results provide evidence for the involvement of RKIP in suppressing the development of hypoxia-induced PAH in mice.
肺血管重塑、肺动脉压和肺血管阻力的增加是肺动脉高压（PAH）发展的特征。Raf/丝裂原活化蛋白激酶/细胞外信号调节激酶（ERK）1/2 的激活被认为在 PAH 中起重要作用，而 Raf-1 激酶抑制剂蛋白（RKIP）负调节该途径。本研究旨在探讨 RKIP 缺失（从而导致 ERK1/2 上调）是否导致小鼠出现肺动脉高压表型，并研究 RKIP 在肺成纤维细胞中丝裂原调节的增殖反应中的作用。
在正常氧或缺氧 2 周后，评估 RKIP 基因缺失（RKIP-/-）小鼠的肺血管血液动力学和重塑。用免疫印迹和免疫组化检测小鼠肺动脉中 Raf-1、RKIP 和 ERK1/2 的磷酸化。在体外，分析 CCL39 仓鼠肺成纤维细胞中 RKIP 对丝裂原信号的抑制作用。
与野生型（WT）小鼠相比，RKIP-/-小鼠表现出更高的 PAH 指数和 ERK1/2 磷酸化。缺氧的 RKIP-/-小鼠表现出更明显的 PAH 指数。缺氧增加了 WT 小鼠肺血管中 Raf-1、RKIP 和 ERK1/2 的磷酸化以及 RKIP-/-小鼠肺血管中 Raf-1 的磷酸化。在 CCL39 细胞中，RKIP 抑制增强了丝裂原诱导的增殖和 RKIP、Raf-1 的磷酸化。
缺乏 RKIP 蛋白导致肺动脉高压表型，在缺氧时更为明显。缺氧诱导 WT 肺血管中 RKIP 信号元件的磷酸化。RKIP 抑制增强了肺成纤维细胞中丝裂原诱导的增殖。这些结果为 RKIP 参与抑制小鼠缺氧诱导的 PAH 发展提供了证据。
