Role of Placental Transport In Fetal Growth

描述（由申请人提供）：本提案的总体目标是了解调节胎儿生长的胎盘营养机制。GLUT 3是一种特异性的促性葡萄糖转运蛋白，在胎盘的滋养层/滋养细胞中表达，并与GLUT 1一起协调介导经胎盘的葡萄糖转运到母体。正常发育(D)导致妊娠后期胎盘GLUT 3表达和浓度升高，与胎儿最大生长有关，而母体营养限制（MNR）或特异性生长因子缺乏（EGF）导致胎盘GLUT 3浓度下降，与胎儿生长限制有关。我们观察到GLUT 3在大鼠滋养细胞中受顺式元件结合去磷酸化Sp1/Sp3的转录调节（HRP.1）。为了在体内扩展这些新颖的体外观察，我们创建了GLUT 3-荧光素酶转基因小鼠和小鼠MNR模型。为了进一步研究滋养外胚层/胎盘GLUT 3的功能意义，我们创建了一只GLUT 3缺失的小鼠，其杂合子显示胎儿生长受限，这与细胞凋亡/坏死有关。为了确定胎盘GLUT 3在D期和MNR中的作用，本研究的主要目的是验证胎盘GLUT 3的表达对胎儿发育和MNR中的葡萄糖供应至关重要的假设，并且GLUT 3的缺乏易导致滋养细胞异常，从而导致胎儿细胞增殖、分化、凋亡和/或坏死。为了验证这一假设，我们提出了三个具体目标：1]确定机制(s)的3 D和MNR调节胎盘过剩表达式,我们计划采用过剩3-luciferase转基因小鼠行和调查的影响转录调控过剩3 D和MNR, 2]探索减少过剩的影响3浓度正常的胎盘和胎儿D MNR,我们将使用过剩3零杂合的鼠标线(50%),并确定影响胎盘和胎儿的表型和功能,[3]为了研究GLUT 3在正常胎盘和胎儿D以及MNR中的功能作用，我们将检测纯合子的无GLUT 3植入前胚胎，并在重组小鼠品系中使用Tet-Off系统抑制GLUT 3的表达，并检测其对胎盘和胎儿表型的影响。我们提出的研究将确定GLUT 3在正常和异常胎儿生长中的生物学作用。

DESCRIPTION (provided by applicant): The overall aim of this proposal is to understand the placental nutrient mechanisms that regulate fetal growth. GLUT 3, a specific facilitative glucose transporter is expressed in the trophoectoderm/trophoblasts of the placenta and along with GLUT 1 coordinately mediates trans-placental glucose transport to the conceptus. Normal development (D) causes an increase in placental GLUT 3 expression and concentrations in late gestation associated with maximal fetal growth, while maternal nutrient restriction (MNR) or specific growth factor deficiency (EGF) leads to a decline in placental GLUT 3 concentrations with fetal growth restriction. We have observed that GLUT 3 is transcriptionally regulated by cis elements that bind dephosphorylated Sp1/Sp3 in rat trophoblast cells (HRP.1). To pursue an in-vivo extension of these novel in-vitro observations, we have created a GLUT 3-luciferase transgenic mouse and a mouse model of MNR. Further to investigate the functional significance of trophoectoderm/placental GLUT 3 we created a GLUT 3 null mouse, the heterozygote demonstrates fetal growth restriction which is associated with cellular apoptosis/necrosis. To define the role of placental GLUT 3 during D and in response to MNR, the proximate goal of this proposal is to test the hypothesis that placental GLUT 3 expression is critical for fetal glucose supply through development and MNR, and the absence of GLUT 3 predisposes towards aberrant trophoblast and thereby fetal cellular proliferation, differentiation, apoptosis, and/or necrosis. To test this hypothesis, we propose three specific aims: 1] To determine the mechanism(s) by which D and MNR regulates placental GLUT 3 expression, we plan to employ the GLUT 3-luciferase transgenic mouse lines and investigate the effect of D and MNR on transcriptional regulation of GLUT 3, 2] To explore the effect of decreased GLUT 3 concentrations on normal placental and fetal D and in MNR, we will employ the GLUT 3 null heterozygous mouse line (50%), and determine the effect on placental and fetal phenotype and function, and 3] To investigate the functional role of GLUT 3 on normal placental and fetal D and in MNR, we will examine homozygous null GLUT 3 pre-implantation embryos, and employ the Tet-Off system to repress GLUT 3 expression in a recombinant mouse strain, and examine the effect on placental and fetal phenotype. Our proposed studies will define the biological role of GLUT 3 in normal and aberrant fetal growth.