Abu Shehab Majida, Biggar Kyle, Kakadia Jenica H, Dhruv Manthan, Jain Bhawani, Nandi Pinki, Nygard Karen, Jansson Thomas, Gupta Madhulika B
Department of Pediatrics, University of Western Ontario, London, ON, Canada.
Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada.
Mol Cell Endocrinol. 2020 Jul 15;512:110865. doi: 10.1016/j.mce.2020.110865. Epub 2020 Jun 5.
Decidual mechanistic target of rapamycin (mTOR) is inhibited, amino acid response (AAR) and protein kinase CK2 are activated, and IGF (insulin-like growth factor) binding protein (IGFBP)-1 is hyperphosphorylated in human intrauterine growth restriction (IUGR). Using decidualized human immortalized endometrial stromal cells (HIESC), we hypothesized that hypoxia and leucine deprivation causing inhibition of decidual IGF-1 signaling is mediated by mTOR, AAR, CK2 and IGFBP-1 phosphorylation. Mass spectrometry demonstrated that hypoxia (1% O) or rapamycin increased IGFBP-1 phosphorylation singly at Ser101/119/169 (confirmed using immunoblotting) and dually at pSer169 + 174. Hypoxia resulted in mTOR inhibition, AAR and CK2 activation, and decreased IGF-1 bioactivity, with no additional changes with rapamycin + hypoxia. Rapamycin and/or hypoxia promoted colocalization of IGFBP-1 and CK2 (dual-immunofluorescence and proximity ligation assay). Leucine deprivation showed similar outcomes. Changes in IGFBP-1 phosphorylation regulated by mTOR/AAR signaling and CK2 may represent a novel mechanism linking oxygen and nutrient availability to IGF-1 signaling in the decidua.
在人类宫内生长受限（IUGR）中，蜕膜中的雷帕霉素机制性靶标（mTOR）受到抑制，氨基酸反应（AAR）和蛋白激酶CK2被激活，胰岛素样生长因子（IGF）结合蛋白（IGFBP）-1发生过度磷酸化。我们使用人永生化子宫内膜基质细胞（HIESC）进行蜕膜化，推测缺氧和亮氨酸缺乏导致蜕膜IGF-1信号传导受抑制是由mTOR、AAR、CK2和IGFBP-1磷酸化介导的。质谱分析表明，缺氧（1% O）或雷帕霉素单独增加了IGFBP-1在Ser101/119/169位点的磷酸化（通过免疫印迹法证实）以及在pSer169 + 174位点的双重磷酸化。缺氧导致mTOR抑制、AAR和CK2激活，并降低了IGF-1生物活性，雷帕霉素 + 缺氧处理未产生额外变化。雷帕霉素和/或缺氧促进了IGFBP-1与CK2的共定位（双重免疫荧光和邻近连接分析）。亮氨酸缺乏显示出相似的结果。由mTOR/AAR信号传导和CK2调节的IGFBP-1磷酸化变化可能代表了一种将氧和营养物质可用性与蜕膜中IGF-1信号传导联系起来的新机制。
