Hepatic insulin resistance and metabolic disease

描述（由申请方提供）：这是一项题为“肝脏胰岛素抵抗和代谢性疾病”的新提案，基于我们实验室在过去5年中对LDKO（肝脏特异性Irs 1-/-“Irs 2-/-）和LTKO（肝脏特异性Irs 1-/-“Irs 2-/-“FoxO 1-/-）小鼠进行的研究。LDKO小鼠表现出全身代谢失调，包括肝脏和外周胰岛素抵抗、高血糖症、中度高胰岛素血症和进行性NAFLD（非酒精性脂肪肝）。NAFLD的病因学根源于胰岛素抵抗、肥胖、高脂血症和糖尿病。由于LTKO小鼠显示正常的营养稳态，我们证实激活的肝脏FoxO 1，而不是仅仅肝脏甘油三酯的积累，促进炎症进展到危及生命的坏死/凋亡和再生周期，最终导致NAFLD进展为NASH（非酒精性脂肪性肝炎）和HCC（肝细胞癌）的损伤特征。为了研究潜在的病理生理学，我们专注于线粒体功能障碍，这是由于慢性激活FoxO 1增加数百个基因的表达，包括血红素加氧酶-1（Hmox 1编码）和亲环素D（Ppif编码）。为了探究分子机制，我们建议使用靶向siRNA的纳米颗粒递送来抑制NAFLD起始（10周龄）和进展（10月龄）期间肝脏FoxO 1、Hmox 1或Ppif的表达。为了在我们的实验室中实现这项技术，我们与东北大学药学院的Amiji集团达成了“联盟协议”。基于小鼠的实验将研究FoxO 1介导的肝线粒体功能障碍与全身性炎症和肌肉胰岛素作用导致糖尿病后进行性NAFLD/NASH之间的关系，具体目的如下：i）通过调节FoxO 1、Hmox 1或Ppif的表达以恢复线粒体功能并减弱肝脏炎症，研究LDKO-小鼠中FoxO 1介导的线粒体功能障碍，持续性肝脏胰岛素抵抗期间NASH及其向HCC的进展ii）研究LDKO-小鼠中的骨骼肌胰岛素抗性以建立肝脏炎症与失调的骨骼肌胰岛素作用和代谢之间的关系。iii）在通过抑制FoxO 1、Hmox 1或Ppif解决肝线粒体功能障碍和NAFLD之前和之后，使用磷酸位点特异性单克隆抗体文库定量LDKO小鼠肌肉中IRS 1的Ser/Thr磷酸化。 由于LDKO-小鼠不受ob/ob-小鼠所遇到的下丘脑性肥胖的显性效应的影响，我们的实验直接关注肝脏胰岛素抵抗和NAFLD之间的关系，以及其向全身性胰岛素抵抗和糖尿病的进展。

DESCRIPTION (provided by applicant): This is a new proposal entitled "Hepatic insulin resistance and metabolic disease" that is based upon work conducted in our laboratory during the past 5 years with LDKO (hepatic-specific Irs1-/-"Irs2-/-) and LTKO (hepatic-specific Irs1-/-"Irs2-/-"FoxO1-/-) mice. LDKO-mice display systemic metabolic dysregulation, including hepatic and peripheral insulin resistance, hyperglycemia, moderate hyperinsulinemia, and progressive NAFLD (nonalcoholic fatty liver disease). The etiology of NAFLD is rooted in insulin resistance, obesity, hyperlipidemia, and diabetes. As LTKO-mice display normal nutrient homeostasis, we posit that activated hepatic FoxO1, rather than the mere accumulation of hepatic triglyceride, promotes inflammation that progresses to life- threatening necrosis/apoptosis and cycles of regeneration that culminate with damage-characteristic of the progression of NAFLD to NASH (nonalcoholic steatohepatitis) and HCC (hepatocellular carcinoma). To investigate the underlying pathophysiology, we focus upon mitochondrial dysfunction that develops as a result of chronically activated FoxO1 that increases the expression of hundreds of genes, including hemeoxygenase- 1 (encoded by Hmox1) and cyclophilin D (encoded by Ppif). To interrogate the molecular mechanisms, we propose to use nanoparticle delivery of targeted siRNA to suppress the expression of hepatic FoxO1, Hmox1, or Ppif during initiation (10 weeks of age) and progression (10 months of age) of NAFLD. To enable this technology in our laboratory, we have formed a 'Consortium Agreement' with the Amiji group in the School of Pharmacy at Northeastern University. The mouse-based experiments will investigate the relation between FoxO1-mediated hepatic mitochondrial dysfunction and progressive NAFLD/NASH upon systemic inflammation and muscle insulin action that contributes to diabetes in the following Specific Aims: i) Investigate FoxO1-mediated mitochondrial dysfunction in LDKO-mice by modulating the expression of FoxO1, Hmox1 or Ppif to restore mitochondrial function and attenuate hepatic inflammation, NASH and its progression to HCC during persistent hepatic insulin resistance. ii) Investigate skeletal muscle insulin resistance in LDKO-mice to establish the relation between hepatic inflammation and dysregulated skeletal muscle insulin action and metabolism. iii) Quantify Ser/Thr-phosphorylation of IRS1 in muscle of LDKO-mice using a library of phosphosite-specific monoclonal antibodies before and after resolution of hepatic mitochondrial dysfunction and NAFLD by suppression of FoxO1, Hmox1 or Ppif. Since the LDKO-mice are uncomplicated by the dominant effects of hypothalamic-based obesity encountered with ob/ob-mice, our experiments focus squarely upon the relation between hepatic insulin resistance and NAFLD, and its progression to systemic insulin resistance and diabetes.