Abd El Naby W S, Hagos T H, Hossain M M, Salilew-Wondim D, Gad A Y, Rings F, Cinar M U, Tholen E, Looft C, Schellander K, Hoelker M, Tesfaye D
Institute of Animal Science, Department of Animal Breeding and Husbandry, University of Bonn, Germany.
Zygote. 2013 Feb;21(1):31-51. doi: 10.1017/S0967199411000566. Epub 2011 Oct 11.
MicroRNAs (miRNAs) are small endogenous molecules that are involved in a diverse of cellular process. However, little is known about their abundance in bovine oocytes and their surrounding cumulus cells during oocyte development. To elucidate this situation, we investigated the relative expression pattern of sets of miRNAs between bovine oocyte and the surrounding cumulus cells during in vitro maturation using miRNA polymerase chain reaction (PCR) array. Results revealed that a total of 47 and 51 miRNAs were highly abundant in immature and matured oocytes, respectively, compared with their surrounding cumulus cells. Furthermore, expression analysis of six miRNAs enriched in oocyte miR-205, miR-150, miR-122, miR-96, miR-146a and miR-146b-5p at different maturation times showed a dramatic decrease in abundance from 0 h to 22 h of maturation. The expression of the same miRNAs in preimplantation stage embryos was found to be highly abundant in early stages of embryo development and decreased after the 8-cell stage to the blastocyst stage following a typical maternal transcript profile. Similar results were obtained by localization of miR-205 in preimplantation stage embryos, in which signals were higher up to the 4-cell stage and reduced thereafter. miR-205 and miR-210 were localized in situ in ovarian follicles and revealed a spatio-temporal expression during follicular development. Interestingly, the presence or absence of oocytes or cumulus cells during maturation was found to affect the expression of miRNAs in each of the two cell types. Hence, our results showed the presence of distinct sets of miRNAs in oocytes or cumulus cells and the presence of their dynamic degradation during bovine oocyte maturation.
微小RNA（miRNA）是参与多种细胞过程的内源性小分子。然而，关于它们在牛卵母细胞及其周围卵丘细胞在卵母细胞发育过程中的丰度情况，我们知之甚少。为了阐明这种情况，我们使用miRNA聚合酶链反应（PCR）芯片研究了牛卵母细胞及其周围卵丘细胞在体外成熟过程中几组miRNA的相对表达模式。结果显示，与周围卵丘细胞相比，未成熟和成熟卵母细胞中分别共有47种和51种miRNA高度丰富。此外，对在卵母细胞中富集的6种miRNA（miR-205、miR-150、miR-122、miR-96、miR-146a和miR-146b-5p）在不同成熟时间的表达分析表明，从成熟0小时到22小时，其丰度显著下降。发现在植入前阶段胚胎中，相同miRNA的表达在胚胎发育早期高度丰富，并在8细胞阶段后至囊胚阶段按照典型的母体转录本模式下降。通过在植入前阶段胚胎中定位miR-205也获得了类似结果，其中信号在4细胞阶段之前较高，之后降低。miR-205和miR-210在卵巢卵泡中进行原位定位，并显示在卵泡发育过程中的时空表达。有趣的是，发现在成熟过程中卵母细胞或卵丘细胞的存在与否会影响这两种细胞类型中miRNA的表达。因此，我们的结果表明在卵母细胞或卵丘细胞中存在不同组的miRNA，并且在牛卵母细胞成熟过程中存在它们的动态降解。
