EFFECTS OF LIVER SPECIFIC KNOCKOUT OF PEPCK ON GLUCOSE METABOLISM

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。通常，PEPCK被认为是糖异生最重要的控制点。然而，这一基本教条很难检验，因为它需要体内控制酶表达和通过完整组织的酶测量通量的能力相结合。Magnuson和他的同事已经使用等位基因Cre/loxP策略培育出PEPCK表达从正常小鼠的0-100%不等的小鼠。我们正在与先进成像中心的Burgess博士合作，测量Vanderbilt公司生产的PEPCK表达水平分级的小鼠完整肝脏中的流量。这一安排为了解完整肝脏(最终是肾脏)中PEPCK对糖异生和其他外周途径(如脂肪酸氧化)的控制提供了一个独特而重要的机会。抑制PEPCK的表达会导致肝脏脂肪变性，并导致某些中间池大小的大幅增加，这突显了PEPCK与糖异生以外的代谢途径之间的联系。在PEPCK KO小鼠中，肝脏脂肪变性的发展似乎是自相矛盾的，因为？-氧化酶实际上是上调的。通过测量这些小鼠的肝和肾的代谢途径的通量将有助于我们更好地了解该酶在糖异生途径中所占的控制地位。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Commonly, PEPCK is considered the most important of the control points for gluconeogenesis. However, this fundamental dogma is difficult to test because it would require the combination of in vivo control of enzyme expression and the ability to measure flux through the enzymes of intact tissue. Magnuson and co-workers have generated mice with PEPCK expression ranging from 0-100% of normal mice by using an allelogenic Cre/loxP strategy. We are collaborating with Dr. Burgess in the Advanced Imaging Center to measure fluxes in the intact liver of mice generated at Vanderbilt with graded levels of PEPCK expression. This arrangement offers a unique and important opportunity to understand the control of PEPCK in the intact liver (and eventually kidney) on gluconeogenesis and other peripheral pathways such as fatty acid oxidation. The connection between PEPCK and metabolic pathways besides gluconeogenesis is highlighted by the observation that inhibiting PEPCK expression induces hepatic steatosis and causes large increases in certain intermediate pool sizes. The development of hepatic steatosis in the PEPCK KO mouse seems paradoxical in light of the fact that the enzymes of ?-oxidation are actually up-regulated. Measuring flux through these metabolic pathways of the liver and kidney of these mice will help us better understand the position of control this enzyme occupies in the gluconeogenic pathway.