IGFBP-1 hyperphosphorylation in IUGR: Role of mTOR and CK2

IUGR 中 IGFBP-1 过度磷酸化：mTOR 和 CK2 的作用

• 批准号: 8991534
• 负责人: Madhulika Gupta
• 金额: $ 3.57万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8991534
• 关键词: IGFBP; hyperphosphorylation; IUGR; Role; mTOR

DESCRIPTION (provided by applicant): Intrauterine growth restriction (IUGR) increases the risk for perinatal complications and predisposes for adult disease. Insulin-like growth factor I (IGF-I) is a key regulator of fetal growth, and IGF-I bioavailability is modulated by binding to IG binding protein-1 (IGFBP-1). We and others have provided evidence that phosphorylation of IGFBP-1 markedly increases its affinity to bind IGF-I and that IGFBP-1 hyper phosphorylation may constitute an important mechanism by which growth is reduced in IUGR. However, the molecular mechanisms causing IGFBP-1 phosphorylation in IUGR are largely unknown. The central hypothesis in this mechanistic proposal is that inhibition of mTOR signaling and activation of protein kinase CK2 in the fetal liver constitutes a key molecular link between nutrient deprivation and increased IGFBP-1 secretion and phosphorylation in vitro and in IUGR in vivo. Our hypothesis has been formulated based on our compelling preliminary data including the demonstration that (1) mTOR inhibition induces marked IGFBP-1 phosphorylation and silencing of protein kinase CK2 abolishes IGFBP-1 hyper phosphorylation induced by mTOR inhibition in HepG2 cells and (2) mTOR activity is decreased whereas CK2 expression and IGFBP-1 phosphorylation are increased in the liver of IUGR baboons. To test our hypothesis, we will study HepG2 cells, primary fetal hepatocytes from baboons, and blood and liver tissue of control and IUGR baboon fetuses in two specific aims: In Aim 1 we will use gene silencing approaches and pharmacological inhibitors in HepG2 cells and fetal baboon primary hepatocytes to mechanistically link mTOR signaling to regulation of protein kinase CK2 and IGFBP-1 phosphorylation. In addition, we will test the hypothesis that the increased IGFBP-1 phosphorylation due to amino acid deprivation is mediated by inhibition of mTOR and activation of CK2. In Aim 2 we will use a well-established baboon model of IUGR involving maternal nutrient restriction. We will determine the activity of mTOR and CK2, IGFBP-1 expression and phosphorylation in fetal liver samples and IGFBP-1 serum concentrations and phosphorylation in control and IUGR baboon fetuses. Significance: This work has the potential to identify a novel molecular mechanism underlying the development of IUGR. Furthermore, we will utilize a highly relevant non-human primate model that provides unique access to fetal samples not available through human studies. Innovation: This work will provide an innovative mechanistic link between mTOR and IGF-I signaling, two critical pathways in the regulation of cell growth. The combination of mechanistic approaches in cultured HepG2 and primary fetal baboon hepatocytes with studies of liver tissue from a baboon IUGR model is translational and innovative.

描述（由申请人提供）：宫内生长受限（IUGR）会增加围产期并发症的风险并容易患成人疾病。胰岛素样生长因子 I (IGF-I) 是胎儿生长的关键调节因子，IGF-I 生物利用度通过与 IG 结合蛋白-1 (IGFBP-1) 结合来调节。我们和其他人提供的证据表明，IGFBP-1 的磷酸化显着增加了其与 IGF-I 结合的亲和力，并且 IGFBP-1 过度磷酸化可能构成 IUGR 中生长减少的重要机制。然而，引起 IUGR 中 IGFBP-1 磷酸化的分子机制尚不清楚。这一机制建议的中心假设是，胎儿肝脏中 mTOR 信号传导的抑制和蛋白激酶 CK2 的激活构成了营养缺乏与体外和 IUGR 体内 IGFBP-1 分泌和磷酸化增加之间的关键分子联系。我们的假设是基于令人信服的初步数据而制定的，包括证明 (1) mTOR 抑制会诱导显着的 IGFBP-1 磷酸化，而蛋白激酶 CK2 的沉默会消除 HepG2 细胞中由 mTOR 抑制诱导的 IGFBP-1 过度磷酸化，以及 (2) mTOR IUGR 狒狒肝脏中的 CK2 表达和 IGFBP-1 磷酸化活性降低，而 CK2 表达和 IGFBP-1 磷酸化增加。为了检验我们的假设，我们将研究 HepG2 细胞、来自狒狒的原代胎儿肝细胞以及对照和 IUGR 狒狒胎儿的血液和肝脏组织，有两个具体目标：在目标 1 中，我们将在 HepG2 细胞和胎儿中使用基因沉默方法和药物抑制剂。狒狒原代肝细胞将 mTOR 信号传导与蛋白激酶 CK2 和 IGFBP-1 磷酸化的调节机制连接起来。此外，我们将检验以下假设：氨基酸剥夺导致 IGFBP-1 磷酸化增加是通过抑制 mTOR 和激活 CK2 介导的。在目标 2 中，我们将使用一个完善的 IUGR 狒狒模型，涉及母体营养限制。我们将测定胎儿肝脏样本中 mTOR 和 CK2 的活性、IGFBP-1 表达和磷酸化，以及对照和 IUGR 狒狒胎儿中 IGFBP-1 血清浓度和磷酸化。意义：这项工作有可能确定 IUGR 发展的新分子机制。此外，我们将利用高度相关的非人类灵长类动物模型，该模型提供通过人类研究无法获得的胎儿样本的独特途径。创新：这项工作将提供 mTOR 和 IGF-I 信号传导（细胞生长调节的两个关键途径）之间的创新机制联系。将培养的 HepG2 和原代胎儿狒狒肝细胞的机械方法与狒狒 IUGR 模型肝组织的研究相结合，具有转化性和创新性。