Molecular Mechanisms of Prostaglandin Receptor-mediated Actions

本研究的目的是了解前列腺素诱导和前列腺素受体介导的生理作用的分子机制。(1)前列腺素E_2（PGE_2）在维持动脉导管（DA）通畅中起主要作用。然而，EP 4缺陷，矛盾的结果在小鼠中致命的专利DA。我们发现EP 4介导的信号通过透明质酸（HA）介导的内膜垫形成促进DA关闭。慢性刺激EP 4可增强DA平滑肌细胞的迁移和HA的产生，EP 4和蛋白激酶A的激活可增加HA合成酶（HAS）-2的转录。在未成熟的大鼠DA外植体，内膜垫的形成促进EP 4刺激。HAS 2基因转移足以诱导EP 4缺陷DA外植体中的内膜垫形成。因此，EP 4在DA发育中具有两个重要作用，即血管扩张和内膜垫形成。后一种作用可能促进管腔狭窄，导致粘连性闭塞， 关于我们 和永久性封闭血管腔。(2)PGE_2通过作用于脑视前区的EP_3受体而引起发热。然而，有很少的信息，在视前神经元的EP 3激活下游的分子事件。作为解决这个问题的第一步，我们研究了PGE_2诱导的基因表达的变化，在单细胞分辨率的视前神经元表达EP 3。EP 3阳性神经元的基因芯片分析表明，γ-氨基丁酸A型受体（GABA_A）的基因表达在注射PGE_2后降低。事实上，大多数视前区的EP 3阳性神经元对GABA_A呈阳性。PGE_2通过EP 3依赖性和百日咳毒素敏感性途径降低GABA_A视前区基因表达。PGE_2可抑制野生型小鼠GABA_A视前区蛋白的表达，但对EP 3缺陷型小鼠无影响。因此，PGE_2-EP_3信号通路引起视前温度中心神经元G_（i/o）激活和GABA_A表达的迅速下降可能参与了PGE_2所致的发热。少

The purpose of this study is to understand the molecular mechanisms underlying prostanoid-induced and prostanoid receptor-mediated physiological actions.(1) Prostaglandin E_2 (PGE_2) plays a primary role in maintaining the patency of the ductus arteriosus (DA). EP4 deficiency, however, paradoxically results in fatal patent DA in mice. We found that EP4-mediated signals promote DA closure by hyaluronic acid (HA)-mediated intimal cushion formation. Chronic EP4 stimulation enhanced migration and HA production in DA smooth muscle cell, and activation of EP4 and protein kinase A increased HA Synthase (HAS)-2 transcripts. In immature rat DA explants, intimal cushion formation was promoted by EP4 stimuli. HAS2 gene transfer was sufficient to induce intimal cushion formation in EP4-deficient DA explants. Thus, EP4 has two essential roles in DA development, vascular dilation and intimal cushion formation. The latter action presumably facilitates luminal narrowing leading to adhesive occlusion a … More nd permanent closure of the vascular lumen.(2) PGE_2 has been shown to produce fever by acting on EP3 receptors within preoptic area of the brain. However, there is little information about the molecular events downstream of EP3 activation in preoptic neurons. As a first step to approach this issue, we examined PGE_2-induced gene expression changes at single cell resolution in preoptic neurons expressing EP3. Microarray analysis of EP3-positive neurons indicated that gene expression of gamma-aminobutyric acid type A receptor (GABA_A) is decreased upon PGE_2 injection. Indeed, most EP3-positive neurons in the preoptic area are positive for the GABA_A. PGE_2 decreased the preoptic gene expression of GABA_A via EP3-dependent and pertussis toxin-sensitive pathway. PGE_2 attenuated the preoptic protein expression of GABA_A in wild-type but not in EP3-deficient mice. Thus, PGE_2-EP3 signaling elicits G_<i/o> activation in preoptic thermocenter neurons and a rapid decrease in preoptic GABA_A expression may be involved in PGE_2-induced fever. Less