Maternal Obesity affects AMP-Kinase in Muscle Cell Differentiation

母亲肥胖影响肌细胞分化中的 AMP 激酶

• 批准号: 8023008
• 负责人: MIN DU
• 金额: $ 23.49万
• 依托单位: UNIVERSITY OF WYOMING
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-27 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8023008
• 关键词: Maternal; Obesity; affects; AMP; Kinase

DESCRIPTION (provided by applicant): SIGNIFICANCE: 18-35% of pregnant American women are clinically obese, a condition which affects fetal development with long-term consequences for offspring health, including pre-disposition to obesity and type 2 diabetes (T2D). The underlying mechanisms remain poorly defined. RATIONALE: Skeletal muscle (SM) is a key tissue responsive to the oxidation of fatty acids and glucose, and its transition to insulin resistance (IR) precedes the onset of T2D. The fetal stage is crucial for SM development since there is no net increase in the number of SM fibers after birth. Our preliminary studies in fetal SM indicate that maternal obesity (MO) reduced AMP-activated protein kinase (AMPK) activity, and altered fetal SM development by enhancing intramuscular adipogenesis and fibrogenesis, both of which impair SM functions. Myocytes, adipocytes and fibroblasts in fetal SM are derived from mesenchymal stem cells (MSC). Our preliminary studies show that AMPK phosphorylates and enhances 2-catenin mediated signaling, a pathway promoting myogenesis. AMPK also phosphorylates p300, which is expected to impair its function as a co-activator, and p300 is a necessary co-activator for transcription factors regulating adipogenesis and fibrogenesis. AMPK catalytic subunit has two isoforms demonstrating slightly different roles in metabolism. CENTRAL HYPOTHESIS: MO inhibits AMPK, which reduces phosphorylation of 2-catenin and p300 by AMPK, leads to the down-regulation of 2-catenin but enhancement of p300 mediated signaling and a shift from myogenesis to adipogenesis/fibrogenesis during fetal SM development. We have three SPECIFIC AIMS: 1) Evaluate whether 2-catenin is the key mediator linking AMPK to myogenesis in fetal SM; 2) Examine the link between p300 phosphorylation by AMPK and adipogenesis/fibrogenesis in fetal SM; 3) Assess the isoform specific effect of AMPK on myogenesis, adipogenesis and fibrogenesis. APPROACH: We plan to use mouse mesenchymal C3H10T1/2 cells to assess whether p300 and 2-catenin are key mediators between AMPK and MSC differentiation in fetal SM. We will also use the well-established diet-induced obesity mouse model to induce MO and the available AMPK-isoform-specific knockout mice to evaluate the role of AMPK in fetal SM development. Important mediators of selected signaling pathways will be analyzed at both mRNA and protein levels, as well as their location by immunohistochemical staining in fetal SM. OBJECTIVE: The objective is to test the role of AMPK in fetal SM development due to MO and to further explore mechanisms. INNOVATION: We are pioneering studies to define the role of AMPK in fetal SM development. The proposed work is novel, because the effects of AMPK and its associated signaling pathways on fetal SM development due to MO are just becoming to be appreciated. ENVIRONMENT: All methodologies required are already established in our laboratory. The Developmental Biology Group and the Center for the Study of Fetal Programming provide excellent academic environment, and animal and laboratory facilities. IMPACT: Proposed studies will demonstrate AMPK as a key mediator of fetal SM development, which will make it possible to use numerous available anti- diabetic drugs, known activators of AMPK, to prevent impairment of fetal SM development due to MO. Data and knowledge obtained will also allow us to further explore mechanisms regulating fetal SM development due to other maternal physiological stresses. Given the importance of SM for lifelong activities and its close association with obesity and T2D, such intervention will help the increasing number of obese pregnant women in this country to deliver healthy children. PUBLIC HEALTH RELEVANCE: The United States is experiencing an obesity epidemic which increasingly involves women of child bearing years. 18-35% of pregnant American women are clinically obese, a condition which affects fetal development with long-term consequences for offspring health, including pre-disposition to obesity and Type 2 diabetes. The underlying mechanisms are poorly defined. The objectives of proposed studies are to explore mechanisms associated with impairment of fetal skeletal muscle development due to maternal obesity. Knowledge obtained will allow us to further explore fetal skeletal muscle development due to maternal obesity and other maternal physiological stresses. Molecular mediators identified are targets for interventions to ensure proper skeletal muscle development in fetuses of obese women. Due to the importance of skeletal muscle for lifelong activities and its close association with obesity and Type 2 diabetes, such intervention will help the increasing number of obese pregnant women in this country to deliver healthy children.

描述（由申请人提供）：意义：18-35%的美国孕妇患有临床肥胖症，这种疾病会影响胎儿发育，对后代健康产生长期影响，包括易患肥胖症和2型糖尿病（T2 D）。基本的机制仍然不明确。基本原理：骨骼肌（SM）是对脂肪酸和葡萄糖的氧化有反应的关键组织，并且其向胰岛素抵抗（IR）的转变先于T2 D的发作。胎儿期是SM发育的关键，因为出生后SM纤维的数量没有净增加。我们对胎儿SM的初步研究表明，母体肥胖（MO）降低了AMP活化蛋白激酶（AMPK）的活性，并通过增强肌内脂肪形成和纤维形成改变了胎儿SM的发育，这两者都损害了SM的功能。胎儿SM中的肌细胞、脂肪细胞和成纤维细胞来源于间充质干细胞（MSC）。我们的初步研究表明，AMPK磷酸化和增强2-连环蛋白介导的信号，促进肌生成的途径。AMPK还磷酸化p300，预期这会损害其作为共激活剂的功能，并且p300是调节脂肪形成和纤维形成的转录因子的必要共激活剂。AMPK催化亚基有两种亚型，在代谢中的作用略有不同。中心假设：MO抑制AMPK，这减少了AMPK对2-catenin和p300的磷酸化，导致2-catenin下调，但p300介导的信号转导增强，并在胎儿SM发育期间从肌生成转变为脂肪生成/纤维生成。我们有三个具体目标：1）评价2-连环蛋白是否是将AMPK与胎儿SM中的肌生成联系起来的关键介质; 2）检查AMPK的p300磷酸化与胎儿SM中的脂肪生成/纤维生成之间的联系; 3）评估AMPK对肌生成、脂肪生成和纤维生成的同种型特异性作用。方法：我们计划使用小鼠间充质C3 H10 T1/2细胞来评估p300和2-catenin是否是胎儿SM中AMPK和MSC分化之间的关键介质。我们还将使用完善的饮食诱导的肥胖小鼠模型来诱导MO和可用的AMPK亚型特异性敲除小鼠来评估AMPK在胎儿SM发育中的作用。将在mRNA和蛋白质水平上分析选定信号通路的重要介质，以及通过免疫组织化学染色在胎儿SM中的位置。目的：检测AMPK在MO所致胎儿SM发生中的作用，并进一步探讨其机制。创新：我们是确定AMPK在胎儿SM发育中作用的开创性研究。这项工作是新颖的，因为AMPK及其相关的信号通路对MO引起的胎儿SM发育的影响才刚刚得到重视。环境：我们的实验室已经建立了所需的所有方法。发育生物学小组和胎儿编程研究中心提供了良好的学术环境，以及动物和实验室设施。影响：提出的研究将证明AMPK是胎儿SM发育的关键介质，这将使得可以使用许多可用的抗糖尿病药物（已知的AMPK激活剂）来防止由于MO导致的胎儿SM发育受损。所获得的数据和知识也将使我们能够进一步探索由于其他母体生理应激而调节胎儿SM发育的机制。鉴于SM对终身活动的重要性及其与肥胖和T2 D的密切关联，这种干预将有助于该国越来越多的肥胖孕妇分娩健康的孩子。 公共卫生相关性：美国正在经历一场肥胖流行病，越来越多的育龄妇女参与其中。18-35%的美国孕妇患有临床肥胖症，这种情况会影响胎儿发育，对后代健康产生长期影响，包括易患肥胖症和2型糖尿病。基本机制定义不清。本研究的目的是探讨母体肥胖导致胎儿骨骼肌发育受损的相关机制。所获得的知识将使我们能够进一步探索由于母体肥胖和其他母体生理应激引起的胎儿骨骼肌发育。确定的分子介质是干预措施的目标，以确保肥胖妇女胎儿骨骼肌的正常发育。由于骨骼肌对终身活动的重要性及其与肥胖和2型糖尿病的密切联系，这种干预将有助于该国越来越多的肥胖孕妇分娩健康的孩子。