Wang Guoliang, Liu Shenghua, Wang Li, Meng Liukun, Cui Chuanjue, Zhang Hao, Hu Shengshou, Ma Ning, Wei Yingjie
State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.; Beijing Children's Hospital, Capital Medical University, Beijing, China.
State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Int J Biol Sci. 2017 Jan 15;13(2):135-144. doi: 10.7150/ijbs.17758. eCollection 2017.
Endoplasmic reticulum (ER) stress, a feature of many conditions associated with pulmonary hypertension (PH), is increasingly recognized as a common response to promote proliferation in the walls of pulmonary arteries. Increased expression of Lipocalin-2 in PH led us to test the hypothesis that Lipocalin-2, a protein known to sequester iron and regulate it intracellularly, might facilitate the ER stress and proliferation in pulmonary arterial smooth muscle cells (PASMCs). In this study, we observed greatly increased Lcn2 expression accompanied with increased ATF6 cleavage in a standard rat model of pulmonary hypertension induced by monocrotaline. In cultured human PASMCs, Lcn2 significantly promoted ER stress (determined by augmented cleavage and nuclear localization of ATF6, up-regulated transcription of GRP78 and NOGO, increased expression of SOD2, and mild augmented mitochondrial membrane potential) and proliferation (assessed by Ki67 staining and BrdU incorporation). Lcn2 promoted ER stress accompanied with augmented intracellular iron levels in human PASMCs. Treatment human PASMCs with FeSO4 induced the similar ER stress and proliferation response and iron chelator (deferoxamine) abrogated the ER stress and proliferation induced by Lcn2 in cultured human PASMCs. In conclusion, Lcn2 significantly promoted human PASMC ER stress and proliferation by augmenting intracellular iron. The up-regulation of Lcn2 probably involved in the pathogenesis and progression of PH.
内质网（ER）应激是许多与肺动脉高压（PH）相关疾病的一个特征，越来越被认为是促进肺动脉壁增殖的常见反应。PH中脂质运载蛋白-2（Lipocalin-2）表达增加，这使我们测试这样一个假设：脂质运载蛋白-2，一种已知能螯合铁并在细胞内调节铁的蛋白质，可能会促进肺动脉平滑肌细胞（PASMCs）的内质网应激和增殖。在本研究中，我们在由野百合碱诱导的肺动脉高压标准大鼠模型中观察到Lcn2表达大幅增加，同时伴有ATF6裂解增加。在培养的人PASMCs中，Lcn2显著促进内质网应激（通过ATF6裂解增加和核定位、GRP78和NOGO转录上调、SOD2表达增加以及线粒体膜电位轻度增加来确定）和增殖（通过Ki67染色和BrdU掺入评估）。Lcn2促进内质网应激并伴有人PASMCs细胞内铁水平升高。用硫酸亚铁处理人PASMCs诱导出类似的内质网应激和增殖反应，而铁螯合剂（去铁胺）消除了培养的人PASMCs中Lcn2诱导的内质网应激和增殖。总之，Lcn2通过增加细胞内铁显著促进人PASMC内质网应激和增殖。Lcn2的上调可能参与了PH的发病机制和进展。
