Determining the Cellular Mechanisms of Catecholamine Resistance in Obesity

项目摘要 肥胖是许多疾病的主要危险因素，并已达到流行病的程度 国际吧它伴随着脂肪细胞对肾上腺素的反应性降低， 去甲肾上腺素称为儿茶酚胺抵抗脂肪细胞中的儿茶酚胺信号传导受 肾上腺素能受体和肾上腺素能受体。在小鼠中，ADRB 3-肾上腺素能受体（ADRB 3）在 比其他ADRB高出数百倍，可以调节全身代谢。 随后，ADRB 3激动剂已在临床上被探索用于治疗肥胖症;然而，它们已经被证实是有效的。 由于其效果的持久性低，成功有限。有趣的是，ADRB 3对经典的 脱敏，但也可能通过调节其自身的表达而变得脱敏，我们假设 对于ADRB 3激动剂在肥胖患者中的有限作用是重要的。我的初步数据显示 炎症通路的激活或ADRB 3的直接激活显著下调了 脂肪细胞中ADRB 3 mRNA和蛋白。在这两种情况下，这种下调都依赖于EPAC， 小G蛋白RAP 1/2的鸟嘌呤交换因子。这个提议将调查这部小说 假设在肥胖期间生理性地产生对儿茶酚胺的抗性（异源的 脱敏）和在肾上腺素能激动剂给药期间（同源 脱敏）由ADRB 3的EPAC/RAP依赖性下调引起。我会利用 复杂的技术，包括质谱、RNAseq、脂肪细胞特异性敲除小鼠 模型，体外分化的原代前脂肪细胞，以及分子生物学，生物化学， 小分子/siRNA和生理学测定来测试这一总体假设。我会决定 负责ADRB 3下调的信号通路和转录调节因子 在脂肪细胞的同源和异源脱敏过程中。该项目代表了一个 对我来说，这是一个极好的培训机会，因为它不仅会让我接触到最前沿的想法， 技术在新陈代谢/脂肪细胞生物学，而且在职业发展（赠款写作， 沟通，实验室管理等），这将使我准备过渡到独立。

Project Summary Obesity is a major risk factor for numerous diseases and has reached epidemic proportions worldwide. It is accompanied by a reduction in adipocyte responsiveness to epinephrine and norepinephrine, termed catecholamine resistance. Catecholamine signaling in adipocytes is governed by - and -adrenergic receptors. In mice, the 3-adrenergic receptor (ADRB3) is expressed at hundred folds higher levels than other ADRBs and can regulate whole body metabolism. Subsequently, ADRB3 agonists have been explored clinically to treat obesity; however, they have had limited success due to low durability of their effects. Interestingly, ADRB3 is resistant to classical desensitization but may become desensitized by regulating its own expression, which we hypothesize is important for the limited effects of ADRB3 agonists in obese patients. My preliminary data suggest that activation of inflammatory pathways or direct activation of ADRB3 dramatically downregulates ADRB3 mRNA and protein in adipocytes. In both cases this downregulation is dependent on EPAC, a guanine exchange factor for the small G-proteins RAP1/2. This proposal will investigate the novel hypothesis that resistance to catecholamines produced physiologically during obesity (heterologous desensitization) and pharmacologically during adrenergic agonist administration (homologous desensitization) results from EPAC/RAP-dependent downregulation of ADRB3. I will utilize sophisticated techniques including mass spectroscopy, RNAseq, adipocyte-specific knockout mouse models, primary pre-adipocytes differentiated in vitro, as well as molecular biology, biochemistry, small molecule/siRNA, and physiological assays to test this overarching hypothesis. I will determine the signaling pathways and transcriptional regulators responsible for downregulation of ADRB3 during homologous and heterologous desensitization in adipocytes. This project represents an excellent training opportunity for me, because it will not only expose me to cutting edge ideas and technologies in metabolism/adipocyte biology, but also in career development (grant writing, communication, lab management, etc) that will prepare me for the transition to independence.