The human formyl peptide receptor as model system for constitutively active G-protein-coupled receptors.
The human formyl peptide receptor as model system for constitutively active G-protein-coupled receptors.
复制标题
人甲酰肽受体作为组成型活性 G 蛋白偶联受体的模型系统。
DOI：
10.1016/s0024-3205(03)00654-4
复制
发表时间：
2003
期刊：
影响因子：
6.1
通讯作者：
Wenzel-Seifert,Katharina
中科院分区：
文献类型：
--
作者：
Seifert,Roland;Wenzel-Seifert,Katharina
根据 G 蛋白偶联受体 (GPCR) 激活的二态模型，GPCR 从非活性 (R) 状态异构化为活性 (R*) 状态。在 R* 状态下，GPCR 激活 G 蛋白。不依赖激动剂的 R/R* 异构化被称为组成型活性，导致基础 G 蛋白活性增加，即 GDP/GTP 交换。激动剂稳定 R* 状态并进一步增加基础 G 蛋白活性，而反向激动剂则稳定 R 状态并降低基础 G 蛋白活性。在许多野生型 GPCR 和组成活性增加的致病 GPCR 突变体中观察到组成活性。人甲酰肽受体 (FPR) 存在多种亚型（FPR-26、FPR-98 和 FPR-G6），并通过 Gi 蛋白激活吞噬细胞的趋化性和细胞毒性细胞功能。对 HL-60 白血病细胞膜的研究表明 Na+ 和百日咳毒素对基础 Gi 蛋白活性有抑制作用，表明 FPR 具有组成型活性。然而，由于 HL-60 细胞表达几种组成型活性趋化受体，因此分析组成型 FPR 活性很困难。 Sf9 昆虫细胞不表达趋化受体和 Gi 蛋白，并为 FPR/Gi 蛋白偶联提供敏感的重建系统。此类表达研究表明，通过 Na+ 和反激动剂环孢菌素 H 对基础 Gi 蛋白活性的相对抑制作用评估，FPR-26 比 FPR-98 和 FPR-G6 具有更高的组成型活性。定点诱变研究表明，C 末端的 E346A 交换关键决定 FPR 的二聚化和组成活性。此外，N 末端的 N-糖基化似乎对于组成型 FPR 活性很重要。最后，我们讨论了一些未来的研究方向。
According to the two-state model of G-protein-coupled receptor (GPCR) activation, GPCRs isomerize from an inactive (R) state to an active (R*) state. In the R* state, GPCRs activate G-proteins. Agonist-independent R/R* isomerization is referred to as constitutive activity and results in an increase in basal G-protein activity, i.e. GDP/GTP exchange. Agonists stabilize the R* state and further increase, whereas inverse agonists stabilize the R state and decrease, basal G-protein activity. Constitutive activity is observed in numerous wild-type GPCRs and disease-causing GPCR mutants with increased constitutive activity. The human formyl peptide receptor (FPR) exists in several isoforms (FPR-26, FPR-98 and FPR-G6) and activates chemotaxis and cytotoxic cell functions of phagocytes through Gi-proteins. Studies in HL-60 leukemia cell membranes demonstrated inhibitory effects of Na+and pertussis toxin on basal Gi-protein activity, suggesting that the FPR is constitutively active. However, since HL-60 cells express several constitutively active chemoattractant receptors, analysis of constitutive FPR activity was difficult. Sf9 insect cells do not express chemoattractant receptors and Gi-proteins and provide a sensitive reconstitution system for FPR/Gi-protein coupling. Such expression studies showed that FPR-26 is much more constitutively active than FPR-98 and FPR-G6 as assessed by the relative inhibitory effects of Na+and of the inverse agonist cyclosporin H on basal Gi-protein activity. Site-directed mutagenesis studies suggest that the E346A exchange in the C-terminus critically determines dimerization and constitutive activity of FPR. Moreover, N-glycosylation of the N-terminus seems to be important for constitutive FPR activity. Finally, we discuss some future directions of research.