Investigation of oocyte maturation inhibitory proteins from urine of pregnant women.

在哺乳动物中，卵泡包裹的卵母细胞的生发泡在减数分裂的分叉阶段保持停滞，直到出现促性腺激素激增。当卵母细胞从体外的卵泡中释放出来时，减数分裂过程恢复，导致自发性生发破裂，随后卵母细胞的第一极体形成，这表明卵母细胞成熟抑制剂(S)维持了卵母细胞减数分裂的停滞。在正常妊娠中，虽然绒毛膜促性腺激素和雌激素水平很高，但卵母细胞和卵泡不会在很长一段时间内显著成熟，这表明妊娠期间尿中卵母细胞成熟抑制物(S)的浓度可能会大幅增加。本研究的目的是利用体外培养的小鼠去卵母细胞，检测孕妇尿液中是否存在蛋白质抑制物(S)。结果表明，该蛋白具有核糖核酸酶活性，氨基酸末端序列分析表明该蛋白是一种非分泌型核糖核酸酶前体的特殊加工产物。这种蛋白只在孕妇的尿液中检测到，而在正常男性和女性中没有检测到。从孕妇尿液中用凝胶过滤法制备了含有GVBD多肽抑制剂(S)的相对分子质量小于2000道尔顿的组份。该组分的抑制活性在有效的阿片拮抗剂纳洛酮存在下被部分逆转。从妊娠尿液中获得的这一组分的活性显著高于从正常女性和男性中获得的相同组分。

In mammals, the germinal vesicle of follicle-enclosed oocytes remains arrested at the dictyate stage of meiosis until the occurrence of a gonadotropin surge. Upon releasing the oocytes from the follicles in vitro, the meiotic process resumes, leading to a spontaneous germinal breakdown(GVBD)followed by the first polar body formation(PBF)of the oocytes, suggesting that oocyte maturation inhibitor(s)sustain the meiotic arrest of oocytes. In normal pregnancy, although hormonal levels of chorionic gonadotropin and estrogen are high, significant maturation of the oocytes and follicles do not occur for a long period, suggesting the possibility of a considerable increase in concentration of oocyte maturation inhibitor(s)in urine during pregnancy. The purpose of this study was to determine protein inhibitor(s)using denuded mouse oocytes in culture, if such inhibitor(s)are present in urine of pregnant women.The results obtained from this study are as follows :1. A protein inhibitor of PBF was purified from a uine of pregnant women by Sephadex G-100 and reversed-phase chromatographies. It was revealed that this protein possessed an ribonuclease activity and amino terminal sequence analysis showed that this protein is a product of a peculiar processing of a nonsecretory ribonuclease precursor. This protein was detected only in urine of pregnant women but not of normal men and women.2. A fraction with molecular mass of less than 2, 000 daltons containing peptide inhibitor(s)of GVBD was prepared by gel filtration from pregnancy urine. The inhibitory activity of this fraction was partially reversed in the presence of naloxon, a potent opioid antagonist. Activity of this fraction obtained from pregnancy urine was significantly potent than same fractions obtained from normal women and men.