MOLECULAR APPROACHES FOR FUNCTIONS AND PHYSIOLOGICAL SIGNIFICANCE OF PROSTAGLANDIN E RECEPTORS

前列腺素 E 受体功能和生理意义的分子方法

基本信息

批准号：
07672353
负责人：
NEGISHI Manabu
金额：
$ 1.66万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07672353/
关键词：
PROSTAGLANDINE2 SUBTYPE ISOFORM DESENSITIZATION NEURITE RETRACTION RHO G蛋白質中枢神経系 Gi活性

项目摘要

We previously identified three isoforms of the mouse prostaglandin (PG) E receptor EP3 subtype, EP3alpha, EP3beta and EP3gamma, with different COOH-terminal tails, produced through alternative splicing. We examined the Gi activities of these isoforms. The EP3alpha receptor showed marked agonist-independent constitutive Gi activity, the EP3beta receptor had no constitutive activity, and the EP3gamma receptor showed mostly full constitutive activity. Thus, the EP3 receptor isoforms differ in constitutive Gi activity.Among four PGE receptor subtypes, the EP2 and EP4 receptors are coupled to the same signal transduction pathway, stimulation of adenylate cyclase. However, the EP4 receptor underwent short term agonist-induced desensitization, but no such desensitization was observed for the EP2 receptor. On the other hand, PGE_2 is rapidly metabolized to 15-keto-PGE_2. The EP4 receptor markedly lost the response for the metabolite, but the EP2 receptor still had significant response. Therefore, the physiological significance of EP2 and EP4 receptors may lie in their different sensitivities to agonist-induced short term desensitization and their differential susceptibilities to the metabolic inactivation of the agonist.The EP3 receptor is widely distributed in the nervous system and is specifically localized to neurons. when the EP3 receptor was expressed in PC-12 cells, in the differentiated cells, an EP3 agonist caused neurite retraction in a pertussis toxin-insensitive manner. C3 exoenzyme completely inhibited the EP3 agonist-induced neurite retraction when microinjected into the cells, indicating that the morphological effect of the EP3 receptor is dependent on Rho activity.

我们之前鉴定了小鼠前列腺素 (PG) E 受体 EP3 亚型的三种亚型：EP3α、EP3β 和 EP3gamma，它们具有不同的 COOH 末端尾部，通过选择性剪接产生。我们检查了这些亚型的 Gi 活性。 EP3α受体显示出显着的不依赖激动剂的组成型Gi活性，EP3β受体没有组成型活性，而EP3γ受体则显示出大部分完全的组成型活性。因此，EP3受体亚型在组成性Gi活性方面有所不同。在四种PGE受体亚型中，EP2和EP4受体与相同的信号转导途径偶联，刺激腺苷酸环化酶。然而，EP4受体经历了短期激动剂诱导的脱敏，但EP2受体没有观察到这种脱敏。另一方面，PGE_2 快速代谢为 15-keto-PGE_2。 EP4受体明显失去了对代谢物的反应，但EP2受体仍然有显着的反应。因此，EP2和EP4受体的生理意义可能在于它们对激动剂引起的短期脱敏的不同敏感性以及对激动剂代谢失活的不同敏感性。 EP3受体广泛分布于神经系统中，并且特异性定位于神经元。当EP3受体在PC-12细胞中表达时，在分化的细胞中，EP3激动剂以百日咳毒素不敏感的方式引起神经突收缩。当显微注射到细胞中时，C3 外切酶完全抑制 EP3 激动剂诱导的神经突回缩，表明 EP3 受体的形态效应依赖于 Rho 活性。