Synphilin-1 and Obesity

描述（由申请人提供）：肥胖是最常见的代谢性疾病，由摄入的卡路里超过持续需求引起。肥胖患病率的增加导致肥胖相关疾病（如2型糖尿病和心血管疾病）的发病率迅速上升。肥胖的发病机制尚不完全清楚。在目前的应用中，我们建议研究synphilin-1在食物摄入和体重控制中的新作用。Synphilin-1是一种细胞质蛋白，可与α -突触核蛋白和帕金森氏蛋白相互作用，在帕金森氏病的发病机制中与蛋白质聚集有关。通过研究synphilin-1转基因小鼠（SP1）的表型，我们有证据表明synphilin-1过表达显著增加体重，并通过增加食物摄入量来实现。我们发现synphilin-1在参与能量平衡的下丘脑核神经元中高表达，提示synphilin-1可能通过调节下丘脑信号影响能量平衡。我们的初步数据表明，synphilin-1可能通过增加下丘脑神经元中供氧基因NPY和AgRP的表达来影响食物摄入和体重。近年来，研究表明AMPK是中枢神经元的能量传感器，在维持能量稳态中起重要作用。我们的初步数据显示，在培养的N1E-115细胞和PVN部位，人synphilin-1的表达增加了AMPK的磷酸化，并进一步表明synphilin-1与AMPK相互作用，如共免疫沉淀所示。因此，在本提案中，我们将验证synphilin-1调节下丘脑摄食相关基因表达和AMPK信号级联导致贪食和肥胖的假设。在Aim 1中，我们将描述食物摄入量、体重和下丘脑基因表达模式对突触蛋白-1过表达的反应。我们将通过测试SP1小鼠对中枢和外周肽的反应以及它们的口味偏好来具体评估其食用量增加的基础。在Aim 2中，我们将研究内源性下丘脑突触蛋白-1在代谢状态改变时的作用。在Aim 3中，我们将在体外细胞培养系统中验证synphilin-1改变AMPK信号级联及其相关细胞能量事件的假设。在Aim 4中，我们将使用过表达和siRNA敲低的方法来验证synphilin-1激活下丘脑AMPK信号导致体内贪食和肥胖的假设。这些研究将有助于深入了解synphilin-1诱导的暴饮暴食和肥胖的分子机制，扩大我们对synphilin-1生物学功能的认识，并可能为未来肥胖发病机制的研究提供独特的遗传肥胖模型。

DESCRIPTION (provided by applicant): Obesity is the most common metabolic disease, resulting from the ingestion of calories in excess of ongoing requirements. Increased prevalence of obesity has resulted in rapidly accelerating rates of obesity related disorders such as type 2 diabetes and cardiovascular disease. The pathogenesis of obesity remains incompletely understood. In the current application, we propose to investigate a novel role for synphilin-1 in food intake and body weight control. Synphilin-1, a cytoplasmic protein, interacts with alpha-synuclein and parkin and has implications in Parkinson's disease pathogenesis related to protein aggregation. Through work examining the phenotype of a synphillin-1 transgenic mouse (SP1), we have evidence that synphilin-1 over- expression significantly increases body weight and does so through increasing food intake. We have found that synphilin-1 is highly expressed in neurons of hypothalamic nuclei involved in energy balance, suggesting that synphilin-1 may be affecting energy balance by modulating hypothalamic signaling. Our preliminary data suggest that synphilin-1 may affect food intake and body weight through increases in orexigenic genes: NPY and AgRP expression in hypothalamic neurons. Recently, studies have suggested that AMP-activated kinase (AMPK) is a central neuronal energy sensor that plays a major role in maintaining energy homeostasis. Our preliminary data showed that expression of human synphilin-1 increased AMPK phosphorylation in cultured N1E-115 cells and at the PVN site, and further showed that synphilin-1 interacted with AMPK as indicated by co-immunoprecipitation. Thus, in this proposal, we will test the hypothesis that synphilin-1 modulates hypothalamic feeding related gene expression and AMPK signaling cascades resulting in hyperphagia and obesity. In Aim 1, we will characterize changes in food intake, body weight and patterns of hypothalamic gene expression in responses to overexpression of synphilin-1. We will specifically assess the bases for the increased meal size that characterizes the hyperphagia in SP1 mice by testing responses to central and peripheral peptide administration and characterizing their taste preferences. In Aim 2, we will investigate the role of endogenous hypothalamic synphilin-1 in response to alterations in metabolic status. In Aim 3, we will test the hypothesis that synphilin-1 alters AMPK signaling cascades and its related cell energy events in an in vitro cell culture system. In Aim 4, we will test the hypothesis that synphilin-1 activates AMPK signaling in hypothalamus resulting in hyperphagia and obesity in vivo using overexpression and siRNA knockdown approaches. These studies will provide insight into the molecular mechanisms underlying synphilin-1-induced hyperphagia and obesity, will enlarge our knowledge of the biological functions of synphilin-1, and may provide a unique genetic obesity model for future studies of the pathogenesis of obesity.