Agonism with the omega-3 fatty acids α-linolenic acid and docosahexaenoic acid mediates phosphorylation of both the short and long isoforms of the human GPR120 receptor
Agonism with the omega-3 fatty acids α-linolenic acid and docosahexaenoic acid mediates phosphorylation of both the short and long isoforms of the human GPR120 receptor
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DOI：
10.1016/j.bbrc.2010.05.057
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发表时间：
2010-06-11
影响因子：
3.1
通讯作者：
Moniri, Nader H.
中科院分区：
文献类型：
--
作者：
Burns, Rebecca N.;Moniri, Nader H.
新发现的G蛋白偶联受体GPR 120最近被证明可以刺激肠道激素胰高血糖素样肽-1和胆囊收缩素在结合游离脂肪酸后的分泌，将其推到治疗2型糖尿病以及饱腹感和肥胖症的药物发现工作的最前沿。尽管已经报道了人GPR 120受体的两种选择性剪接变体的序列，但是还没有直接比较这些同种型的信号传导的研究。我们已经确定了一个额外的16个氨基酸的差距，含有四个磷酸不稳定的丝氨酸/苏氨酸残基，这是本地化的第三个细胞内环的GPR 120长（GPR 120-L）亚型。基于这一发现，我们假设这种亚型的激动剂刺激的磷酸化特征与短亚型（GPR 120-S）不同。使用克隆HEK 293细胞模型，我们检查了激动剂介导的GPR 120-S和GPR 120-L与ω-3脂肪酸α-亚麻酸（ALA）和二十二碳六烯酸（DHA）的磷酸化。我们的研究结果表明，无论是ALA或DHA激动后，这两种亚型的快速磷酸化。此外，我们显示，无论是ALA或DHA激动后，这两种亚型的磷酸化程度或速率没有显着差异，这表明在较长的变体中的额外的差距没有磷酸化。重要的是，我们的研究结果表明，较短的变体表现出显着更明显的基础磷酸化在激动剂的情况下，这表明在长的变体中的额外的差距可能有助于掩盖组成性磷酸化位点。这些是第一个证明在游离脂肪酸激动后GPR 120同种型特异性磷酸化的结果，也是第一个区分两种GPR 120同种型磷酸化特征的结果。(C)2010年爱思唯尔公司All rights reserved.
The newly discovered G protein-coupled receptor GPR120 has recently been shown to stimulate secretion of the gut hormones glucagon-like peptide-1 and cholecystokinin upon binding of free fatty acids, thrusting it to the forefront of drug discovery efforts for treatment of type 2 diabetes as well as satiety and obesity. Although sequences for two alternative splice variants of the human GPR120 receptor have been reported, there have been no studies which directly compare the signaling of these isoforms. We have identified an additional 16 amino acid gap containing four phospho-labile serine/threonine residues which is localized to the third intracellular loop of the GPR120-long (GPR120-L) isoform. Based on this finding, we hypothesized that the agonist-stimulated phosphorylation profiles of this isoform would be distinct from that of the short isoform (GPR120-S). Using a clonal HEK293 cell model, we examined agonist-mediated phosphorylation of GPR120-S and GPR120-L with the omega-3 fatty acids alpha-linolenic acid (ALA) and docosahexaenoic acid (DHA). Our results show rapid phosphorylation of both isoforms following agonism by either ALA or DHA. Moreover, we show no significant difference in the degree or rate of phosphorylation of both isoforms upon agonism with either ALA or DHA, suggesting that the additional gap in the longer variant is not phosphorylated. Importantly, our results demonstrate that the shorter variant exhibits significantly more pronounced basal phosphorylation in the absence of agonist, suggesting that the additional gap in the long variant may contribute to masking of constitutive phosphorylation sites. These are the first results which demonstrate specific phosphorylation of GPR120 isoforms upon agonism by free fatty acids and the first which distinguish the phosphorylation profiles of the two GPR120 isoforms. (C) 2010 Elsevier Inc. All rights reserved.