Xing Yan, Gosden Roger, Lasko Paul, Clarke Hugh
Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada.
Reproduction. 2006 May;131(5):905-15. doi: 10.1530/rep.1.01046.
Mammalian homologues of genes that control oogenesis in other organisms may play similar roles in mammalian ovarian development. In Drosophila melanogaster, GUSTAVUS (GUS) protein physically interacts with and is necessary for the proper posterior localization of VASA protein, and thus is required for specification of germ cells. We identified two mouse genes, SSB-1 and SSB-4 (SPRY domain SOCS box protein), whose protein products share 75% identity and are each approximately 70% identical to Drosophila GUS. Both SSB-1 and SSB-4 mRNA were detectable in mouse ovaries by Northern blotting of total and poly(A) + RNA, but were expressed in few other tissues. SSB-1 was detectable in testes, although the 3'-untranslated region of the mRNA was considerably shorter than the ovarian mRNA. In situ hybridization and RT-PCR analysis of ovaries revealed that both genes were expressed in granulosa cells at all stages of follicular development. In contrast, expression was barely detectable in in oocytes. Immunoblotting analysis revealed that SSB-1 protein was present in follicles at different stages of growth, and immunocytochemistry confirmed that SSB-1 and SSB-4 were detectable in granulosa cells of primary and subsequent stage follicles and that they were present in both mural and cumulus granulosa cells of antral follicles. These results establish that GUS-related proteins, which in Drosophila are restricted to the germ cells, are in the mouse instead expressed in the granulosa cells and are present throughout folliculogenesis. Based on their tissue-restricted pattern of expression and apparent abundance in granulosa cells, we propose that SSB-1 and SSB-4 play key roles in regulating granulosa cell physiology.
在其他生物体中控制卵子发生的基因的哺乳动物同源物可能在哺乳动物卵巢发育中发挥类似作用。在黑腹果蝇中,古斯塔夫斯(GUSTAVUS,GUS)蛋白与VASA蛋白发生物理相互作用,并且是VASA蛋白正确定位到后部所必需的,因此是生殖细胞特化所必需的。我们鉴定出两个小鼠基因,SSB - 1和SSB - 4(SPRY结构域SOCS盒蛋白),它们的蛋白质产物具有75%的同一性,并且各自与果蝇GUS大约70%相同。通过对总RNA和聚腺苷酸加尾(poly(A)+)RNA进行Northern印迹分析,在小鼠卵巢中可检测到SSB - 1和SSB - 4的mRNA,但在其他很少的组织中表达。在睾丸中可检测到SSB - 1,尽管其mRNA的3'非翻译区比卵巢mRNA短得多。对卵巢进行原位杂交和逆转录聚合酶链反应(RT - PCR)分析表明,这两个基因在卵泡发育的所有阶段的颗粒细胞中均有表达。相反,在卵母细胞中几乎检测不到表达。免疫印迹分析表明,SSB - 1蛋白存在于不同生长阶段的卵泡中,免疫细胞化学证实,在初级及后续阶段卵泡的颗粒细胞中可检测到SSB - 1和SSB - 4,并且它们存在于窦状卵泡的壁颗粒细胞和卵丘颗粒细胞中。这些结果表明,在果蝇中局限于生殖细胞的GUS相关蛋白,在小鼠中却在颗粒细胞中表达,并且在整个卵泡发生过程中都存在。基于它们在组织中的限制性表达模式以及在颗粒细胞中的明显丰度,我们认为SSB - 1和SSB - 4在调节颗粒细胞生理功能中起关键作用。