ROLE OF PTG IN ADIPOCYTIC GLYCOGEN METABOLISM

PTG 在脂肪细胞糖原代谢中的作用

• 批准号: 7221223
• 负责人: Matthew J Brady
• 金额: $ 25.45万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7221223
• 关键词: Adipocytes; Binding; Binding Proteins; Binding Sites; Carbohydrates; Cell physiology; Cells; Chronic; Complex; Deoxyglucose; Deposition; Development; Dominant-Negative Mutation; Enzymes; Excision; Fasting; Gene Expression; Glucose; Glycogen; Glycogen (Starch) Synthase; Goals; Hyperglycemia; In Vitro; Infection; Insulin; Insulin Resistance; Insulin Signaling Pathway; Lipids; Mammals; Maps; Measures; Mediating; Metabolism; Microarray Analysis; Molecular; Mutagenesis; Non-Insulin-Dependent Diabetes Mellitus; Phosphoric Monoester Hydrolases; Phosphorylation Site; Play; Protein Dephosphorylation; Protein Overexpression; Protein phosphatase; Proteins; Regulation; Role; Satiation; Small Interfering RNA; Testing; adenoviral-mediated; adiponectin; basal insulin; blood glucose regulation; carbohydrate metabolism; cell type; deletion analysis; diabetic; extracellular; glucose disposal; glucose metabolism; glucose transport; glucose uptake; glycogen metabolism; in vivo; insulin sensitivity; insulin signaling; lipid metabolism; mutant; particle; protein activation; protein expression; research study; uptake

DESCRIPTION (provided by applicant): Activation of protein phosphatase-1 (PP1) plays a critical role in the regulation of glycogen metabolizing enzymes by insulin. Protein Targeting to Glycogen (PTG) binds to PP1 and glycogen, thus targeting the phosphatase to glycogen particles. Additionally, PTG binds specific PP1 substrates that regulate glycogen metabolism, discretely enhancing phosphatase activity against these enzymes. Overexpression of PTG in a variety of cell types causes a marked increase in glycogen synthase dephosphorylation and activation, resulting in enhanced glycogen accumulation. We will test the central hypothesis that the PTG: PP1 complex is the primary, insulin-sensitive enzymatic regulator of glycogen synthase activity in 3T3-L1 adipocytes. Further, since over 70% of insulin-stimulated glucose uptake was deposited as glycogen in 3T3-L1 adipocytes, we will investigate the role of cellular glycogen levels in adipocytic energy sensing and function. We have recently identified dominant negative and siRNA constructs that suppress cellular PTG function or expression. Thus, we can significantly modulate cellular glycogen stores in a bi-directional manner. We will use a panel of PTG mutant constructs to fully explore its mechanism of action in the regulation of PP1 activity against glycogen synthase. We will then examine the effects of decreasing PTG function on glycogen synthase dephosphorylation and activation by insulin. Finally, PTG overexpression results in the specific suppression of adiponectin levels, without reducing proximal insulin signaling pathways, 2-deoxyglucose transport, glucose storage as lipid or cellular ATP levels. We will examine the impact of modulating PTG function and glycogen levels in a bi-directional manner on the regulation of glucose and lipid uptake, metabolism, storage and mobilization in 3T3-L1 adipocytes. Then, the expression of a variety of adipocytic factors will be assessed in control, PTG over expressing and PTG-deficient cells using microarray analysis. Through these experiments, we will fully investigate the role of the PTG: PP1 complex in the regulation of glycogen synthase activity by insulin, and explore the intricate interplay between carbohydrate and lipid metabolism, energy sensing and the regulated secretion of adipocytic factors that influence insulin sensitivity in vivo.

描述（由申请方提供）：蛋白磷酸酶-1（PP 1）的激活在胰岛素调节糖原代谢酶中起关键作用。蛋白质靶向糖原（PTG）结合PP 1和糖原，从而将磷酸酶靶向糖原颗粒。此外，PTG结合调节糖原代谢的特异性PP 1底物，离散地增强针对这些酶的磷酸酶活性。PTG在多种细胞类型中的过表达导致糖原合成酶去磷酸化和活化的显著增加，从而导致糖原积累增强。我们将测试中心的假设，即PTG：PP 1复合物是主要的，胰岛素敏感的糖原合成酶活性在3 T3-L1脂肪细胞的酶调节剂。此外，由于超过70%的胰岛素刺激的葡萄糖摄取作为糖原沉积在3 T3-L1脂肪细胞中，我们将研究细胞糖原水平在脂肪细胞能量感知和功能中的作用。我们最近发现了抑制细胞PTG功能或表达的显性负调控和siRNA构建体。因此，我们可以以双向方式显著调节细胞糖原储存。我们将使用一组PTG突变体构建体来充分探索其在调节PP 1活性对抗糖原合酶中的作用机制。然后，我们将研究降低PTG功能对糖原合成酶去磷酸化和胰岛素激活的影响。最后，PTG过表达导致脂联素水平的特异性抑制，而不降低近端胰岛素信号传导途径、2-脱氧葡萄糖转运、葡萄糖储存为脂质或细胞ATP水平。我们将研究以双向方式调节PTG功能和糖原水平对3 T3-L1脂肪细胞中葡萄糖和脂质摄取、代谢、储存和动员的调节的影响。然后，使用微阵列分析在对照、PTG过表达和PTG缺陷细胞中评估多种脂肪细胞因子的表达。通过这些实验，我们将充分研究PTG：PP 1复合物在胰岛素调节糖原合成酶活性中的作用，并探索碳水化合物和脂质代谢，能量传感和体内影响胰岛素敏感性的脂肪细胞因子的调节分泌之间错综复杂的相互作用。