Isolation of Positive Modulator of Glucagon-like Peptide-1 Signaling from Trigonella foenum-graecum (Fenugreek) Seed
Isolation of Positive Modulator of Glucagon-like Peptide-1 Signaling from Trigonella foenum-graecum (Fenugreek) Seed
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DOI：
10.1074/jbc.m115.672097
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发表时间：
2015-10-23
影响因子：
4.8
通讯作者：
Chein, Rong-Jie
中科院分区：
文献类型：
--
作者：
King, Klim;Lin, Nai-Pin;Chein, Rong-Jie
胰高血糖素样肽-1 受体 (GLP-1R) 在许多组织中表达，并与多种生理功能有关，例如能量稳态和认知。 GLP-1类似物已被批准用于治疗2型糖尿病，并且正在进行针对其他疾病（包括神经退行性疾病）的临床试验。 GLP-1 类似物疗法维持类似物的长期高血浆水平，并可能导致 GLP-1R 激活的时空控制丧失。为了避免与当前疗法相关的副作用，我们鉴定了 GLP-1R 信号传导的正调节剂。我们使用细胞内 cAMP 生物传感器和 GLP-1R 内吞测定法筛选可食用植物的提取物。胡芦巴种子的乙醇提取物增强了 GLP-1 信号传导。此前已发现这些种子可以降低人类的葡萄糖和糖化血红蛋白水平。从胡芦巴种子中纯化出具有新的 N-亚油酰基-2-氨基-γ-丁内酯结构的活性化合物 (N55)。 N55 以剂量依赖性和可饱和方式促进 GLP-1 依赖性 cAMP 产生和 GLP-1R 内吞作用。 N55 特异性地增强 GLP-1 的效力超过 40 倍，但不增强 exendin 4 的效力，以刺激 cAMP 的产生。与目前结合 GLP-1R 的变构调节剂相反，N55 结合 GLP-1 肽并促进胰蛋白酶介导的 GLP-1 失活。这些发现确定了一类新的 GLP-1R 信号调节剂，并表明 GLP-1 可能是药物发现的可行靶点。我们的结果还强调了筛选植物提取物生物活性的可行方法。
The glucagon-like peptide-1 receptor (GLP-1R) is expressed in many tissues and has been implicated in diverse physiological functions, such as energy homeostasis and cognition. GLP-1 analogs are approved for treatment of type 2 diabetes and are undergoing clinical trials for other disorders, including neurodegenerative diseases. GLP-1 analog therapies maintain chronically high plasma levels of the analog and can lead to loss of spatiotemporal control of GLP-1R activation. To avoid adverse effects associated with current therapies, we characterized positive modulators of GLP-1R signaling. We screened extracts from edible plants using an intracellular cAMP biosensor and GLP-1R endocytosis assays. Ethanol extracts from fenugreek seeds enhanced GLP-1 signaling. These seeds have previously been found to reduce glucose and glycated hemoglobin levels in humans. An active compound (N55) with a new N-linoleoyl-2-amino-gamma-butyrolactone structure was purified from fenugreek seeds. N55 promoted GLP-1-dependent cAMP production and GLP-1R endocytosis in a dose-dependent and saturable manner. N55 specifically enhanced GLP-1 potency more than 40-fold, but not that of exendin 4, to stimulate cAMP production. In contrast to the current allosteric modulators that bind to GLP-1R, N55 binds to GLP-1 peptide and facilitates trypsinmediated GLP-1 inactivation. These findings identify a new class of modulators of GLP-1R signaling and suggest that GLP-1 might be a viable target for drug discovery. Our results also highlight a feasible approach for screening bioactive activity of plant extracts.