Investigating the role of PHD3 in lipid homeostasis

项目摘要 细胞代谢的适应对于维持组织和全身的稳态是至关重要的。在 响应于低能量或应激，细胞激活AMP活化蛋白激酶（AMPK）以磷酸化 乙酰辅酶A羧化酶（ACC），增加线粒体脂肪酸氧化（FAO）和ATP 程度.然而，粮农组织如何在能源丰富的国家下调还不完全清楚。作为 驱动燃料成瘾的途径可能为个性化治疗提供新的治疗靶点或生物标志物。 因此，在治疗中，迫切需要鉴定调节代谢稳态的途径。我们有 发现了一种新的营养依赖性信号通路，通过少量研究控制脂肪氧化， 脯氨酰羟化酶结构域蛋白家族成员，PHD 3。PHD是β-酮戊二酸家族 羟基化底物脯氨酸残基并与燃料连接的依赖性双加氧酶 切换我们发现PHD 3通过羟化乙酰辅酶A羧化酶来调节脂肪酸代谢 （ACC 2），线粒体FAO的调节剂。响应营养丰富，PHD 3激活ACC 2 以抑制脂肪酸的分解。由于ACC 2和PHD 3在氧化组织中高度表达， 例如骨骼肌，该提议将检验骨骼肌中PHD 3的缺失 通过阻止ACC 2羟基化来解除能量稳态，从而引起组成性的 线粒体氧化代谢该提案将通过以下方式测试这些想法：1）定义动力学， 确定PHD 3介导的羟基化调节ACC 2的特异性，2）确定作用 PHD 3在骨骼肌细胞能量学营养信号传导中的作用，以及3）测试PHD 3在骨骼肌细胞能量学营养信号传导中的生理作用。 PHD 3在体内肌肉能量稳态中的相关性。首先，我们将利用重组纯化的 PHD 3来定量ACC 2相对于HIF 1 α的PHD 3羟基化的动力学参数。接下来我们将 检查PHD 1 -3对ACC 2羟基化的特异性（目的1）。我们还将研究 PHD 3对骨骼肌细胞中响应于营养线索的细胞代谢的影响。我们会研究 AMPK、ACC 2和HIF 1 α信号传导对PHD 3代谢作用的必要性（目的2）。最后我们将 检查PHD 3活性对静息状态和运动过程中骨骼肌生理学的影响。 急性能源挑战（目标3）。我们的首要目标是阐明PHD 3的分子元件 控制细胞代谢的信号，并利用这些发现最终发展 治疗策略，以促进改善肌肉功能和代谢健身。

Project Summary Adaptation of cellular metabolism is crucial for maintaining tissue and whole-body homeostasis. In response to low energy or stress, cells activate AMP-activated protein kinase (AMPK) to phosphorylate acetyl-CoA carboxylase (ACC), which increases mitochondrial fatty acid oxidation (FAO) and ATP levels. However, how FAO is downregulated in energy abundance states is not fully understood. As pathways that drive fuel addiction may provide new therapeutic targets or biomarkers for personalized therapy, there is a critical need to identify pathways that regulate metabolic homeostasis. We have discovered a new nutrient-dependent signaling pathway that controls fat oxidation via a little studied member of the prolyl hydroxylase domain protein family, PHD3. PHDs are a family of -ketoglutarate dependent dioxygenases that hydroxylate substrate proline residues and have been linked to fuel switching. We find that PHD3 regulates fatty acid metabolism by hydroxylating acetyl-CoA carboxylase (ACC2), a regulator of mitochondrial FAO. In response to nutrient abundance, PHD3 activates ACC2 to inhibit catabolism of fatty acids. Since ACC2 and PHD3 are highly expressed in oxidative tissues such as skeletal muscle, this proposal will test the hypothesis that the loss of PHD3 in skeletal muscle deregulates energy homeostasis by preventing ACC2 hydroxylation, hence causing constitutive mitochondrial oxidative metabolism. This proposal will test these ideas by: 1) defining the kinetics and determining the specificity by which PHD3-mediated hydroxylation regulates ACC2, 2) defining the role of PHD3 in nutrient signaling in skeletal muscle cell energetics, and 3) testing the physiological relevance of PHD3 in muscle energy homeostasis in vivo. First, we will utilize recombinant purified PHD3 to quantify the kinetic parameters of PHD3 hydroxylation of ACC2 versus HIF1. Next we will examine the specificity of ACC2 hydroxylation by PHD1-3 (Aim 1). We will also examine the effect of PHD3 on cellular metabolism in skeletal muscle cells in response to nutrient cues. We will examine the necessity of AMPK, ACC2, and HIF1 signaling on the metabolic roles of PHD3 (Aim 2). Finally, we will examine the consequences of PHD3 activity on skeletal muscle physiology in a resting state and during acute energy challenge (Aim 3). Our overarching goal is to elucidate the molecular elements of PHD3 signaling that control cellular metabolism and to leverage these findings to ultimately develop therapeutic strategies to promote improved muscle function and metabolic fitness.