EFFECTS OF LIVER SPECIFIC KNOCKOUT OF PEPCK ON GLUCOSE METABOLISM

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。通常，PEPCK被认为是糖异生最重要的控制点。然而，这一基本原则很难验证，因为它需要结合体内酶表达控制和测量完整组织中酶通量的能力。Magnuson和他的同事通过使用等位基因Cre/loxP策略，产生了PEPCK表达范围为0-100%的正常小鼠。我们正在与高级成像中心的Burgess博士合作，测量在Vanderbilt生成的具有PEPCK表达分级水平的小鼠的完整肝脏中的通量。这种安排为理解完整肝脏（最终是肾脏）中PEPCK对糖异生和其他外周通路（如脂肪酸氧化）的控制提供了独特而重要的机会。抑制PEPCK表达可诱导肝脂肪变性并导致某些中间池大小大幅增加，这一观察结果突出了PEPCK与糖异生之外的代谢途径之间的联系。PEPCK KO小鼠肝脂肪变性的发展似乎是矛盾的，因为？-氧化实际上是上调的。测量这些小鼠肝脏和肾脏代谢途径的通量将有助于我们更好地了解这种酶在糖异生途径中的控制地位。

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.