EP3 receptor isoforms are differentially expressed in subpopulations of primate granulosa cells and couple to unique G-proteins.
EP3 receptor isoforms are differentially expressed in subpopulations of primate granulosa cells and couple to unique G-proteins.
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DOI：
10.1530/rep-13-0274
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发表时间：
2013-12
期刊：
影响因子：
--
通讯作者：
Duffy DM
中科院分区：
文献类型：
--
作者：
Kim SO;Dozier BL;Kerry JA;Duffy DM
卵泡内产生的前列腺素E2是排卵所必需的。前列腺素E2由四种不同的G蛋白偶联受体识别。其中，PTGER 3（也称为EP 3）的独特之处在于mRNA剪接产生多种亚型。每个亚型在C-末端区域具有不同的氨基酸组成，其参与G-蛋白偶联。为了确定猴EP 3同种型是否与不同的G蛋白偶联，在中国仓鼠卵巢（CHO）细胞中表达每种EP 3同种型，并在用EP 3激动剂硫前列酮刺激后检查细胞内信号。刺激EP 3亚型5（EP 3 -5）以百日咳毒素敏感的方式减少环磷酸腺苷（cAMP），表明Gαi参与。刺激EP 3 -9可增加cAMP，而一般G蛋白抑制剂GDP-β-S可降低cAMP，刺激EP 3 - 9还可增加细胞内钙，而百日咳毒素和GDP-β-S可降低细胞内钙。因此，EP 3 -9可能与Gα和百日咳毒素敏感的G蛋白偶联，以调节细胞内信号。刺激EP 3 -14增加cAMP，其被百日咳毒素进一步增加，因此EP 3 -14可能通过多种G蛋白调节cAMP。所有EP 3亚型的颗粒细胞表达增加排卵剂量的hCG。两种EP 3亚型在颗粒细胞功能亚群中差异表达。EP 3 -5在卵泡顶端的颗粒细胞中表达较低，而EP 3 -9在卵丘颗粒细胞中表达较高。EP 3亚型的差异表达可能会产生不同的细胞内反应的颗粒细胞亚群中的前列腺素E2，颗粒细胞亚群在排卵过程中发挥不同的作用。
Prostaglandin E2 produced within the ovarian follicle is necessary for ovulation. Prostaglandin E2 is recognized by four distinct G-protein coupled receptors. Among them, PTGER3 (also known as EP3) is unique in that mRNA splicing generates multiple isoforms. Each isoform has a distinct amino acid composition in the C-terminal region, which is involved in G-protein coupling. To determine if monkey EP3 isoforms couple to different G-proteins, each EP3 isoform was expressed in Chinese hamster ovary (CHO) cells, and intracellular signals were examined after stimulation with the EP3 agonist sulprostone. Stimulation of EP3 isoform 5 (EP3-5) reduced cyclic adenosine monophosphate (cAMP) in a pertussis toxin-sensitive manner, indicating involvement of Gαi. Stimulation of EP3-9 increased cAMP, which was reduced by the general G-protein inhibitor GDP-β-S, and also increased intracellular calcium, which was reduced by pertussis toxin and GDP-β-S. So, EP3-9 likely couples to both Gαs and a pertussis toxin-sensitive G-protein to regulate intracellular signals. Stimulation of EP3-14 increased cAMP, which was further increased by pertussis toxin, so EP3-14 likely regulates cAMP via multiple G-proteins. Granulosa cell expression of all EP3 isoforms increased in response to an ovulatory dose of hCG. Two EP3 isoforms were differentially expressed in functional subpopulations of granulosa cells. EP3-5 was low in granulosa cells at the follicle apex while EP3-9 was high in cumulus granulosa cells. Differential expression of EP3 isoforms may yield different intracellular responses to prostaglandin E2 in granulosa cell subpopulations, contributing to the different roles played by granulosa cell subpopulations in the process of ovulation.