Davis T L, Sharif N A
Molecular Pharmacology Unit, Alcon Research, Ltd., (R2-19) 6201 South Freeway, Fort Worth, Texas, TX 76134, USA.
Br J Pharmacol. 2000 Aug;130(8):1919-26. doi: 10.1038/sj.bjp.0703525.
Prostaglandin (PG) E(2) (PGE(2)) is a potent prostanoid derived from arachidonic which can interact with EP(1), EP(2), EP(3) and EP(4) prostanoid receptor subtypes. Recombinant human EP(4) receptors expressed in human embryonic kidney (HEK-293) cells were evaluated for their binding characteristics using [(3)H]-PGE(2) and a broad panel of natural and synthetic prostanoids in order to define their pharmacological properties. [(3)H]-PGE(2) binding was optimal in 2-[N-Morpholino]ethanesulphonic acid (MES) buffer (pH 6.0) yielding 98+/-0.7% specific binding. The receptor displayed high affinity (K(d)=0.72+/-0.12 nM; n=3) for [(3)H]-PGE(2) and interacted with a saturable number of binding sites (B(max)=6.21+/-0.84 pmol mg(-1) protein). In competition studies, PGE(2) (K(i)=0.75+/-0.03 nM; n=12) and PGE(1) (K(i)=1.45+/-0.24 nM; n=3) displayed high affinities, as did two derivatives of PGE(1), namely 11-deoxy-PGE(1) (K(i)=1.36+/-0.34 nM) and 13,14-dihydro-PGE(1) (K(i)=3.07+/-0.29 nM). Interestingly, synthetic DP receptor-specific agonists such as BW245C (K(i)=64.7+/-1.0 nM; n=3) and ZK118182 (K(i)=425+/-42 nM; n=4), and the purported EP(3) receptor-specific ligand enprostil (K(i)=43.1+/-4.4 nM), also displayed high affinity for the EP(4) receptor. Two known EP(4) receptor antagonists were weak inhibitors of [(3)H]-PGE(2) binding akin to their known functional potencies, thus: AH23848 (K(i)=2690+/-232 nM); AH22921 (K(i)=31,800+/-4090 nM). These studies have provided a detailed pharmacological characterization of the recombinant human EP(4) receptor expressed in HEK-293 cells.
前列腺素（PG）E2（PGE2）是一种由花生四烯酸衍生而来的强效类前列腺素，它可与EP1、EP2、EP3和EP4类前列腺素受体亚型相互作用。利用[3H]-PGE2以及一系列天然和合成类前列腺素，对在人胚肾（HEK-293）细胞中表达的重组人EP4受体的结合特性进行了评估，以确定其药理学特性。[3H]-PGE2在2-[N-吗啉代]乙磺酸（MES）缓冲液（pH 6.0）中的结合最为理想，特异性结合率为98±0.7%。该受体对[3H]-PGE2表现出高亲和力（Kd = 0.72±0.12 nM；n = 3），并与可饱和数量的结合位点相互作用（Bmax = 6.21±0.84 pmol mg-1蛋白质）。在竞争研究中，PGE2（Ki = 0.75±0.03 nM；n = 12）和PGE1（Ki = 1.45±0.24 nM；n = 3）表现出高亲和力，PGE1的两种衍生物11-脱氧-PGE1（Ki = 1.36±0.34 nM）和13,14-二氢-PGE1（Ki = 3.07±0.29 nM）也是如此。有趣的是，合成的DP受体特异性激动剂如BW245C（Ki = 64.7±1.0 nM；n = 3）和ZK118182（Ki = 425±42 nM；n = 4），以及所谓的EP3受体特异性配体恩前列素（Ki = 43.1±4.4 nM），对EP4受体也表现出高亲和力。两种已知的EP4受体拮抗剂是[3H]-PGE2结合的弱抑制剂，与其已知的功能效力相似，即：AH23848（Ki = 2690±232 nM）；AH22921（Ki = 31,800±4090 nM）。这些研究提供了对在HEK-293细胞中表达的重组人EP4受体的详细药理学特征描述。
