Physiological Roles of a Novel Calcium Phospholipid Binding Protein, Annexin V,in the Function of the Anterior Pituitary Gland and the Ovary ; A Molecular-Cellular Biological Approach

研究了一种新的钙磷脂结合蛋白--膜联蛋白V在垂体前叶和卵巢功能中的生理意义。用免疫细胞化学方法显示了膜联蛋白V在垂体前叶促性腺激素细胞上的特异性分布。摘除卵巢后，垂体前叶中该蛋白的含量增加。Northern印迹分析表明，卵巢切除也能促进膜联蛋白V的合成。这些结果使我们研究了GnRH对Annexin V合成的影响，我们发现GnRH对Annexin V的mRNA积累有刺激作用。因此，膜联蛋白V被认为是垂体促性腺激素细胞中促性腺激素释放激素的一种新的信号转导。据推测，Annexin V在卵巢中也是一种生理调节器。膜联蛋白V的分布仅限于黄体细胞。颗粒细胞既不表达膜联蛋白V，也不表达膜联蛋白V的mRNA，而且黄体膜联蛋白V的浓度随着假孕的不同而变化。这些结果表明，膜联蛋白V可能在黄体孕激素功能中发挥作用。我们还通过观察体外记录的下丘脑切片的单位活动(SUA)来检测Annexin V在神经系统中的作用。尽管我们只有初步数据，但膜联蛋白V被证明能显著抑制或刺激神经放电活动。目前关于膜联蛋白V的生理作用的项目提出了一种可能性，即膜联蛋白V在各种组织中局部发挥特定的活性。其中，其对促性腺激素细胞的信号转导作用是首次观察到其生理调节剂的活性。

Physiological importance of a novel calcium-phospholipid binding protein, annexin V,in functions of the anterior pituitary gland and the ovary was investigated. By immunocytochemical approach, the specific distribution of annexin V on gonadotrophs at the anterior pituitary gland was demonstrated. The amount of this protein in the anterior pituitary gland was revealed to increase after ovariectomy. It was shown that ovariectomy enhances annexin V synthesis also by Northern blot analysis. These results led us to examine the effect of GnRH on annexin V synthesis and we found a stimulating effect of GnRH on annexin V mRNA accumulation. In turn, annexin V increased LH beta mRNA.Getting together, annexin V is thought to be a novel signal transducer of GnRH at pituitary gonadotrophs. Annexin V is hypothesized to be a physiological modulator also at the ovary. The distribution of annexin V was shown to restricted to luteal cells. Granulosa cells showed neither annexin V nor its mRNA.Furthermore, luteal annexin V varies its concentration along with pseudopregnancy. These results suggest annexin V would play a role in luteal progestational function. We also examined the effect of annexin V in neural system by observing single unit activity (SUA) recorded with a section of hypothalamus in vitro. Even though we have only preliminary data, annexin V was shown to inhibit or stimulate significantly the neural firing activity. The present project on the physiological role of annexin V raises a possibility that annexin V exerts specific activity locally in various tissues. Among these, its signal transducing action at gonadotrophs is the first observation on its activity of physiological modulator.