Shirazi Abolfazl, Heidari Mahbobeh, Shams-Esfandabadi Naser, Momeni Amir, Derafshian Zahra
Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, P.O. Box: 19615-1177, Tehran, Iran; Department of Gametes and Cloning, Research Institute of Animal Embryo Technology, Shahrekord University, P.O. Box: 115, Shahrekord, Iran.
Department of Gametes and Cloning, Research Institute of Animal Embryo Technology, Shahrekord University, P.O. Box: 115, Shahrekord, Iran.
Cryobiology. 2015 Jun;70(3):239-45. doi: 10.1016/j.cryobiol.2015.03.003. Epub 2015 Mar 18.
Vitrification apart from all drawbacks on oocyte ultra-structure can affect the oocyte mRNA content. Among those evaluated transcripts, no data is available regarding the effect of vitrification on signal transducer and activator of transcription (STAT3) expression in oocytes and the resulting preimplantation embryos. Considering the bidirectional relationship between E-cadherin (CDH1) and STAT3 and the adverse effect of cryopreservation on adherent junctions, we aimed to ascertain to what extent STAT3 and CDH1 genes expression is affected by vitrification in oocytes and the resulting embryos. The ovine vitrified-warmed and fresh GV oocytes were separately subjected to in vitro maturation and fertilization and cultured up to the blastocyst stage. The relative abundance of STAT3 and CDH1 transcripts were analysed by RT-PCR in both classes of fresh and vitrified GV and MII oocytes and the resulting embryos at 2-7 cells, 8-16 cells, morula, and blastocyst stages. Vitrified oocytes showed lower cleavage (37.8% vs. 95.9%, P<0.001) and blastocyst (8.1% vs. 52.7%, P<0.001) rates compared to control. The relative mRNA abundance of both genes was increased after oocyte maturation indicating their expression was started earlier than expected time proposed for embryonic genomic activation. In embryos derived from both fresh and vitrified oocytes, the maximum concentrations of STAT3 and CDH1 transcripts were observed at 2-7 cells and morula stages, respectively. Moreover, in contrast to CDH1 the relative expression of STAT3 in vitrified derived embryos was higher than embryos derived from fresh oocytes. The overexpression of STAT3 in embryos derived from vitrified oocytes might be the reason for the lower CDH1 expression and in turn the lower developmental competence of the resulting embryos.
除了对卵母细胞超微结构有诸多不利影响外，玻璃化冷冻还会影响卵母细胞的mRNA含量。在评估的转录本中，关于玻璃化冷冻对卵母细胞以及由此产生的植入前胚胎中信号转导和转录激活因子（STAT3）表达的影响，尚无相关数据。考虑到E-钙黏蛋白（CDH1）与STAT3之间的双向关系以及冷冻保存对黏附连接的不利影响，我们旨在确定玻璃化冷冻对卵母细胞及其所产生胚胎中STAT3和CDH1基因表达的影响程度。将经玻璃化冷冻-复温处理的绵羊生发泡（GV）期卵母细胞和新鲜的GV期卵母细胞分别进行体外成熟、受精，并培养至囊胚阶段。通过逆转录聚合酶链反应（RT-PCR）分析新鲜和玻璃化冷冻的GV期和第二次减数分裂中期（MII）期卵母细胞及其所产生的处于2-7细胞、8-16细胞、桑葚胚和囊胚阶段胚胎中STAT3和CDH1转录本的相对丰度。与对照组相比，玻璃化冷冻的卵母细胞显示出较低的卵裂率（37.8%对95.9%，P<0.001）和囊胚率（8.1%对52.7%，P<0.001）。卵母细胞成熟后，这两个基因的相对mRNA丰度均增加，表明它们的表达开始时间早于胚胎基因组激活的预期时间。在来自新鲜和玻璃化冷冻卵母细胞的胚胎中，STAT3和CDH1转录本的最大浓度分别出现在2-7细胞阶段和桑葚胚阶段。此外，与CDH1不同，玻璃化冷冻来源胚胎中STAT3的相对表达高于新鲜卵母细胞来源的胚胎。玻璃化冷冻卵母细胞来源胚胎中STAT3的过表达可能是导致CDH1表达降低以及由此产生的胚胎发育能力较低的原因。
