Involvement of annexin 5 in G protein mediated signal transduction

研究了一种新的G蛋白介导的信号转导机制。结果表明，Annexin 5参与了G蛋白偶联信号转导过程。膜联蛋白是一种新发现的钙-磷脂结合蛋白。结果概括如下：1.从GnRH受体到膜联蛋白5的合成在垂体促性腺激素中，MAPK系统位于GnRH受体和膜联蛋白5的mRNA合成之间。此外，还观察到Annexin 5在GnRH促进促性腺激素分泌的过程中是不可或缺的，并阐明Annexin 5是GnRH受体信号转导的一个新的信号因子。2.分析卵巢Annexin 5在卵巢中的变化。膜联蛋白5的合成在黄体化后开始，催乳素抑制膜联蛋白5的表达。结果表明，膜联蛋白5是通过抑制催乳素的分泌而出现在黄体中的，这些细胞处于凋亡状态。此外，GnRH还促进了Annexin 5的表达并诱导了细胞的凋亡。3.睾丸中的Annexin 5分布于多种睾丸细胞。结果表明，人绒毛膜促性腺激素可增加间质细胞膜联蛋白5的表达。这种作用是由局部的GnRH活动介导的，Annexin 5在垂体前叶促性腺激素、黄体细胞和间质细胞中受GnRH受体的控制。膜联蛋白5是促性腺激素释放激素受体的生物标志物。GnRH受体-膜联蛋白5系统似乎在多种细胞中被利用。

A new G protein mediated signal transduction mechanism was studied. It was clarified that annexin 5 took part in the G protein coupled signal transduction process. Annexin is a member of newly identified calcium-phospholipid binding proteins. The outline of the results is brought together as follows.1.From GnRH receptor to annexin 5 synthesisIt was clarified that the MAPK system lay between the GnRH receptor and annexin 5 mRNA synthesis in the pituitary gonadotropes. In addition, it was observed that annexin 5 was indispensable to the process that GnRH promotes the gonadotrophin secretion, and clarified that annexin 5 was a new signal factor of the GnRH receptor signal transduction.2.Annexin 5 in the ovaryChanges in ovarian annexin 5 were analyzed. The synthesis of annexin 5 was demonstrated to start after luteinization and the expression of annexin 5 was inhibited by prolactin. It was clarified that annexin 5 appeared in corpus luteum by the inhibition of prolactin secretion and those cells were in apoptosis. In addition, it was clarified that local GnRH enhanced annexin 5 expression and induced apoptosis.3.Annexin 5 in the testisAnnexin 5 was demonstrated to distribute to various testicular cells. Among these, endotherial cells and Leydig dells were intensely stained with anti-annexin 5. It was clarified that annexin 5 of Leydig cells was increased by the administration of human chorinic gonadotropin. This effect was shown to be mediated by the local GnRH action.Getting together, annexin 5 was shown to be under the control of GnRH receptor in the anterior pituitary gonadotropes, luteal cells and Leydig cells. Annexin 5 is a biomarker of GnRH receptor. GnRH receptor-annexin 5 system seems to be utilized in various cell species.