State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China.
Guangxi Key Laboratory of Efficacy Study on Chinese Materia Medica, Guangxi Collaborative Innovation Center for Research on Functional Ingredients of Agricultural Residues, Guangxi University of Chinese Medicine, 13 Wuhe Avenue, Nanning 530200, China.
Nutrients. 2018 Sep 23;10(10):1366. doi: 10.3390/nu10101366.
Chlorogenic acid (CGA), a bioactive component in the human diet, is reported to exert beneficial effects on the regulation of glucose metabolism. This study was designed to investigate the specific target of CGA, and explore its underlying mechanisms. Beneficial effects of CGA in glucose metabolism were confirmed in insulin-treated human hepatocarcinoma HepG2 cells. Protein fishing, via CGA-modified functionalized magnetic microspheres, demonstrated the binding of CGA with protein kinase B (AKT). Immunofluorescence using a CGA molecular probe further demonstrated the co-localization of CGA with AKT. A competitive combination test and hampering of AKT membrane translocation showed that CGA might bind to the pleckstrin homology (PH) domain of AKT. The specific binding did not lead to the membrane translocation to phosphatidylinositol (3,4,5)-trisphosphate (PIP₃), but directly activated the phosphorylation of AKT on Ser-473, induced the phosphorylation of the downstream molecules, glycogen synthase kinase 3β (GSK3β) and forkhead box O1 (FOXO1), and improved glucose metabolism. Collectively, our data demonstrate that CGA exerts regulatory effects on glucose metabolism via direct targeting the PH domain of AKT. This study clarifies the mechanism of the potential benefits of nutrients containing CGA in the complementary therapy of glucose metabolism disorders.
绿原酸（CGA）是人类饮食中的一种生物活性成分，据报道其对调节葡萄糖代谢具有有益作用。本研究旨在探究 CGA 的特定靶标，并探讨其潜在机制。在胰岛素处理的人肝癌 HepG2 细胞中，证实了 CGA 对葡萄糖代谢的有益作用。通过 CGA 修饰的功能化磁性微球进行蛋白质钓取实验，证明了 CGA 与蛋白激酶 B（AKT）的结合。使用 CGA 分子探针进行免疫荧光实验进一步证明了 CGA 与 AKT 的共定位。竞争性结合试验和 AKT 膜易位的阻碍表明，CGA 可能与 AKT 的pleckstrin 同源（PH）结构域结合。这种特异性结合不会导致 AKT 向磷脂酰肌醇（3,4,5）-三磷酸（PIP₃）的膜易位，但直接激活 AKT 丝氨酸 473 的磷酸化，诱导下游分子糖原合成酶激酶 3β（GSK3β）和叉头框 O1（FOXO1）的磷酸化，从而改善葡萄糖代谢。总之，我们的数据表明，CGA 通过直接靶向 AKT 的 PH 结构域对葡萄糖代谢发挥调节作用。这项研究阐明了含 CGA 的营养物质在葡萄糖代谢紊乱的补充治疗中的潜在益处的作用机制。
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