Mutter G L, Grills G S, Wolgemuth D J
Center for Reproductive Sciences, Columbia University College of Physicians and Surgeons, New York, NY 10032.
EMBO J. 1988 Mar;7(3):683-9. doi: 10.1002/j.1460-2075.1988.tb02863.x.
The c-mos proto-oncogene exists as a maternal mRNA in mammalian oocytes, in that it has been shown to accumulate in mouse oocytes during the growth phase and to be present at high levels in fully grown oocytes. The function of c-mos during the subsequent development of the oocytes and embryos was examined by determining the fate of the oocyte c-mos mRNAs by in situ hybridization and Northern blot hybridization analysis. A substantial decrease in the levels of c-mos transcripts was observed in oocytes undergoing meiotic maturation. By the two-cell stage, levels of c-mos transcripts dropped to below the limits of detection using in situ hybridization. c-mos transcripts remained undectable through the blastocyst stage of embryogenesis. Analysis of meiotic maturation in vitro permitted finer temporal resolution of the initial drop in c-mos levels. Between approximately 7 and 17 h of culture, the amount of c-mos mRNA fell to 18-43% of the levels found in the fully grown oocyte. This interval corresponds to the progression of meiotic maturation from metaphase I to metaphase II. Our in vivo studies showed that ovulation per se is not the stimulus for the drop in c-mos transcript levels, since preovulatory metaphase II oocytes exhibited this decline to a degree comparable to that of ovulated metaphase II oocytes. The development specificity of c-mos transcript levels suggests a role of this putative serine kinase in the meiotic maturation of mammalian germ cells.
原癌基因c-mos作为母源mRNA存在于哺乳动物卵母细胞中，因为已证明它在小鼠卵母细胞生长阶段积累，并在完全成熟的卵母细胞中高水平存在。通过原位杂交和Northern印迹杂交分析确定卵母细胞c-mos mRNA的命运，来研究c-mos在卵母细胞和胚胎后续发育过程中的功能。在经历减数分裂成熟的卵母细胞中，观察到c-mos转录本水平大幅下降。到二细胞阶段，c-mos转录本水平降至原位杂交检测限以下。在胚胎发育的囊胚阶段，c-mos转录本仍无法检测到。体外减数分裂成熟分析允许对c-mos水平的初始下降进行更精细的时间分辨率分析。在培养约7至17小时之间，c-mos mRNA的量降至完全成熟卵母细胞中发现水平的18 - 43%。这个时间段对应于减数分裂成熟从减数第一次分裂中期到减数第二次分裂中期的进程。我们的体内研究表明，排卵本身不是c-mos转录本水平下降的刺激因素，因为排卵前的减数第二次分裂中期卵母细胞表现出的这种下降程度与排卵后的减数第二次分裂中期卵母细胞相当。c-mos转录本水平的发育特异性表明这种假定的丝氨酸激酶在哺乳动物生殖细胞的减数分裂成熟中起作用。
