INTERACTION OF GLUCOSE AND LIPID WITH CELL SURVIVAL IN LACTATION

葡萄糖和脂质与哺乳期细胞存活的相互作用

• 批准号: 7018025
• 负责人: MARGARET Cobb NEVILLE
• 金额: $ 23.42万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7018025
• 关键词: Krebs' cycle; apoptosis; cell differentiation; enzyme activity; fatty acid biosynthesis; gene expression; genetically modified animals; glucose 6 phosphate; glucose metabolism; glucose transporter; hexokinase; hormone regulation /control mechanism; intracellular transport; laboratory mouse; lactation; lactose; lipid biosynthesis; magnetic resonance imaging; mammary epithelium; membrane potentials; milk; mitochondrial membrane; prolactin

The differentiation of mammary epithelial cells into secretory cells for lactation is of great importance to survival of newborn mammals. Prolactin is critical in this process and the focus has been upon the regulation of milk protein gene transcription by prolactin. Characterizing mammary differentiation solely on the basis of the regulation of milk protein synthesis provides a one-dimensional view of this complex process. In addition to stimulating transcription of milk protein genes, prolactin provides a survival signal and may stimulate other physiologic processes including glucose transport and lipid biosynthesis. Our research with transgenic mice that express constitutively activated Akt1 in the mammary gland suggests that regulation of Akt and glucose levels in mammary epithelial cells may be necessary to 1) maintain "balanced aerobic glycolysis" which leads to the proper ratio of lipid and lactose in the milk, and 2) promote survival of mammary epithelial cells. The glucose transporter GLUT1 is the predominant transporter expressed in the lactating mammary gland. We hypothesize that activation of Akt by lactogenic hormones stimulates translocation of GLUT1 to the plasma membrane and increases hexokinase activity. These changes result in an increase in the cytosolic concentrations of glucose and glucose-6-phosphate. As a consequence the increase in glucose and glucose-6-phosphate stimulates fatty acid biosynthesis due to the increased production of pyruvate and NADPH via glycolysis; and maintains mitochondrial membrane potential thus promoting cell survival. We propose to use magnetic resonance spectroscopy to determine the metabolic basis for the increased lipid biosynthesis in MMTV-myr-Akt1 transgenic mice. We hypothesize that overexpression of activated Akt should increase the pyruvate concentration in mammary cells at the expense of intracellular glucose and glucose-6-phosphate, increase citrate levels, and decrease lactose synthesis relative to lipid synthesis. In the second aim we will determine whether there is a lactation defect in Akt1 null mice. In the third aim, we will generate transgenic mice in which the expression of hexokinase-I in the mammary gland is conditionally regulated using the Tet-On system, to test the hypothesis that overexpression of hexokinase during lactation will result in a lactation failure due to an imbalance in the synthesis of lipids versus lactose. In the fourth aim we will overexpress GLUT1 to determine whether this will suppress involution of the mammary gland. These aims address fundamental questions about the metabolic pathways regulating biosynthesis of lipids and lactose, and the role of glucose metabolism in regulating apoptosis using in vivo models.

将乳腺上皮细胞分化为分泌细胞以泌乳，对于新生儿哺乳动物的生存至关重要。催乳素在此过程中至关重要，重点是催乳素对牛奶蛋白基因转录的调节。仅根据牛奶蛋白合成的调节来表征乳腺分化，这为这一复杂过程提供了一维的视图。除了刺激牛奶蛋白基因的转录外，催乳素还提供了生存信号，并可能刺激其他生理过程，包括葡萄糖转运和脂质生物合成。我们对乳腺中组成型激活Akt1的转基因小鼠的研究表明，可能需要调节乳腺上皮细胞中Akt和葡萄糖水平的调节。1）维持“平衡” 有氧糖糖酵解”，导致牛奶中脂质和乳糖的适当比例，以及2）促进乳腺上皮细胞的存活。葡萄糖转运蛋白glut1是在乳腺癌中表达的主要转运蛋白。己糖酶活性。 葡萄糖和6-磷酸葡萄糖。因此，由于丙酮酸盐和NADPH的产生增加，葡萄糖和6-磷酸葡萄糖和6-磷酸的增加刺激了脂肪酸的生物合成。并保持线粒体膜电位，从而促进细胞存活。我们建议使用磁共振光谱来确定 MMTV-MYR-AKT1转基因小鼠中脂质生物合成增加的代谢基础。我们假设活化Akt的过表达应以乳腺细胞的丙酮酸浓度增加，而牺牲细胞内葡萄糖和6-磷酸葡萄糖，增加柠檬酸盐水平，并降低乳糖合成相对于脂质合成。在第二个目标中，我们将确定AKT1 NULL小鼠中是否存在泌乳缺陷。在第三个目的中，我们将生成转基因小鼠，其中使用Tet-On系统进行条件调节己糖酶-I的表达，以检验以下假设：哺乳期在泌乳过程中的过表达将导致乳酸失败导致乳脂的不平衡脂质乳胶的乳酸乳胶的乳酸。在第四个目标中，我们将过度表达GLUT1，以确定这是否会抑制乳腺的反应。这些目的解决了有关的基本问题 调节脂质和乳糖的生物合成的代谢途径，以及葡萄糖代谢在使用体内模型调节凋亡中的作用。