Mechanisms of homologous and heterologous phosphorylation of FFA receptor 4 (GPR120): GRK6 and PKC mediate phosphorylation of Thr³⁴⁷, Ser³⁵⁰, and Ser³⁵⁷ in the C-terminal tail.
Mechanisms of homologous and heterologous phosphorylation of FFA receptor 4 (GPR120): GRK6 and PKC mediate phosphorylation of Thr³⁴⁷, Ser³⁵⁰, and Ser³⁵⁷ in the C-terminal tail.
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DOI：
10.1016/j.bcp.2013.12.016
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发表时间：
2014-02-15
影响因子：
5.8
通讯作者：
Moniri NH
中科院分区：
文献类型：
--
作者：
Burns RN;Singh M;Senatorov IS;Moniri NH
游离脂肪酸受体4（FFA 4），以前称为GPR 120，是一种G蛋白偶联受体，在长链不饱和脂肪酸的激动作用下促进多种抗炎和抗糖尿病作用。我们先前已经证明，用二十二碳六烯酸（DHA）和α-亚油酸（ALA）激动FFA 4促进HEK 293细胞表面异位表达的FFA 4的快速和瞬时磷酸化。然而，促进FFA 4磷酸化的确切机制仍然难以捉摸。在目前的研究中，我们研究了FFA 4的异源和同源磷酸化背后的机制，并着手确定FFA 4磷酸化的焦点。我们的研究结果表明，基础和异源磷酸化的FFA 4介导的蛋白激酶C（PKC），而G蛋白偶联受体激酶6（GRK 6）在DHA介导的磷酸化FFA 4中起着主导作用。此外，我们确定Thr 347，Ser 350和Ser 357在C-末端尾部作为FFA 4磷酸化的主要位点。这三个位点的同时突变导致FFA 4受体似乎以积极的方式影响Gαq/11信号传导，如DHA激动后细胞内Ca+2反应升高所示。重要的是，这种磷酸缺陷型FFA 4突变体缺乏促进β -arrestin-2募集到细胞膜的能力。由于FFA 4的许多功能上有益的生理作用被注意到是β -抑制蛋白介导的，这些发现可以提供对FFA 4功能的结构要求的深入了解。
Free fatty acid receptor 4 (FFA4), previously known as GPR120, is a G protein-coupled receptor that promotes numerous anti-inflammatory and antidiabetic effects upon its agonism by long chained unsaturated fatty acids. We have previously demonstrated that agonism of FFA4 with docosahexaenoic acid (DHA) and alpha-linoleic acid (ALA) facilitates rapid and transient phosphorylation of FFA4 expressed ectopically on the surface of HEK293 cells. However, the precise mechanisms that promote FFA4 phosphorylation remain elusive. In the current study, we examined the mechanisms behind both heterologous and homologous phosphorylation of FFA4 and set out to identify the foci of FFA4 phosphorylation. Our results demonstrate that basal and heterologous phosphorylation of FFA4 are mediated by protein kinase C (PKC), while G protein-coupled receptor kinase 6 (GRK6) plays the predominant role in DHA-mediated phosphorylation of FFA4. Furthermore, we identify Thr347, Ser350, and Ser357 in the C-terminal tail as major sites of FFA4 phosphorylation. Concurrent mutation of these three sites leads to a FFA4 receptor that seemingly affects Gαq/11 signaling in a positive manner as demonstrated by heightened intracellular Ca+2 responses following agonism with DHA. Importantly, this phosphodefective FFA4 mutant lacked the ability to promote β -arrestin-2 recruitment to the cell membrane. Since many of the functionally beneficial physiological effects of FFA4 are noted to be β -arrestin mediated, these findings could provide insight into the structural requirements for FFA4 function.