Role of Ceramide Regulated Fgf13 in AdiposeT issue Biology

项目摘要/摘要 血脂异常和胰岛素抵抗易患糖尿病、癌症、心肌梗死 脑梗塞和中风。大量证据表明，一类被称为神经酰胺的有毒脂质， 导致这些代谢损伤以及随后这些代谢紊乱的发展。 了解这些脂质在驱动代谢性疾病的事件中的作用对 开发新的疗法来治疗这些令人衰弱的疾病。我们进行了一系列研究，以消融 它们在不同的身体部位产生所需的酶，以辨别哪些组织对 神经酰胺。这些研究表明，这种脂肪在脂肪组织中具有强烈的、意想不到的影响。在……里面 丝氨酸的特定、全身、脂肪和棕色脂肪组织特异性抑制/缺失 棕榈酰基转移酶(Sptlc)是驱动鞘脂生物合成的酶系中的第一种酶，在 小鼠显著改变了脂肪的形态和代谢，尤其是皮下脂肪和棕色脂肪 组织。我们随后切除了该途径中的另一个基因(I.D.)。二氢神经酰胺脱饱和酶-1(Degs1)) 脂肪组织，确定它引起了类似的代谢改善谱。这些数据表明 神经酰胺作为营养过剩的信号，改变成熟脂肪细胞的代谢活动，并 随后，整个有机体。使用微阵列筛选，我们试图识别神经酰胺调节的基因在 脂肪组织。候选肥胖基因Fgf13是仅有的两个满足以下条件的转录本之一 标准：(A)小鼠皮下白色脂肪(SWAT)和附睾白脂肪(EWAT)增加。 (B)当使用SPT抑制剂myriocin处理小鼠时，这些仓库中的高脂肪喂养减少； (C)在Wat特异性Sptlc2耗尽后，这些储存库中的表达减少；以及，(D)在原代脂肪细胞中减少 在体外进行Myriocin治疗后。然后，我们在体外和体内研究了该蛋白的功能。 使用基因敲除或敲除方法的初步数据表明，Fgf13具有细胞自主性， 脂肪细胞特有的饮食调节对线粒体功能和产热的影响。此外，老鼠缺乏 脂肪细胞中的FGF13对肥胖具有抵抗力。这些数据支持我们的假设，即FGF13是神经酰胺 控制成熟脂肪细胞代谢活动的效应器。我们将通过以下具体实例来测试这一想法 目的：1]确定FGF13作为脂肪组织代谢和产热调节因子的作用。 活体；2]确定FGF13与脂肪细胞代谢的分子机制；3]确定 β-肾上腺素能激动剂调节神经酰胺生成和FGF13表达的分子机制 在原代脂肪细胞中。这些研究的结果可能揭示一种新的神经酰胺效应器 影响代谢率。

PROJECT SUMMARY/ABSTRACT Dyslipidemia and insulin resistance predispose individuals to development of diabetes, cancer, myocardial infarction, and stroke. A large body of evidence suggests that a class of toxic lipids, termed ceramides, contribute to these metabolic impairments and the ensuing development of these metabolic disorders. Understanding the role of these lipids in the events that drive metabolic diseases holds great promise for developing new therapies to treat these debilitating conditions. We conducted a series of studies ablating the enzymes required for their production in different body locales to discern which tissues were most sensitive to ceramides. These studies revealed that the lipid has strong and unanticipated effects in adipose tissue. In particular, whole-body, adipose and brown adipose tissue-specific inhibition/deletion of serine palmitoyltransferase (Sptlc), the first enzyme in the enzymatic cascade that drives sphingolipid biosynthesis, in mice markedly altered adipose morphology and metabolism, particularly in subcutaneous and brown adipose tissue. We subsequently excised another gene in the pathway (i.d. dihydroceramide desaturase-1 (Degs1)) from adipose tissue, determining that it elicited a similar spectrum of metabolic improvements. These data indicate that ceramides serve as signals of nutrient excess that alter the metabolic activity of mature adipocytes and subsequently the entire organism. Using microarray screens, we sought to identify ceramide-regulated genes in adipose tissue. The candidate obesity gene Fgf13 was one of the only two transcripts that met the following criteria: (a) increased in mouse subcutaneous white adipose (sWAT) and epididymal white adipose (eWAT) after high fat feeding (HFD); (b) decreased in these depots when the mice were treated with the SPT inhibitor myriocin; (c) decreased in these depots following WAT-specific Sptlc2 depletion; and, (d) decreased in primary adipocytes following myriocin treatment in vitro. We then investigated the function of this protein in vitro and in vivo. Preliminary data using knockdown or knockout approaches suggested that Fgf13 had cell-autonomous, adipocyte-specific, diet-regulated effects on mitochondrial function and thermogenesis. Moreover, mice lacking Fgf13 in adipocytes were resistant to obesity. These data support our hypothesis that FGF13 is a ceramide effector that controls the metabolic activity of mature adipocytes. We will test this idea with the following Specific Aims: 1] to determine the role of FGF13 as a modulator of adipose tissue metabolism and thermogenesis in vivo; 2] to determine the molecular mechanisms linking FGF13 to adipocyte metabolism; and 3] to determine the molecular mechanisms by which b-adrenergic agonists regulate ceramide production and FGF13 expression in primary adipocytes. The findings obtained from these studies could reveal a novel ceramide effector that influences metabolic rate.