Jurisicova A, Latham K E, Casper R F, Casper R F, Varmuza S L
Department of Zoology, University of Toronto, Ontario, Canada.
Mol Reprod Dev. 1998 Nov;51(3):243-53. doi: 10.1002/(SICI)1098-2795(199811)51:3<243::AID-MRD3>3.0.CO;2-P.
The newly fertilized preimplantation embryo depends entirely on maternal mRNAs and proteins deposited and stored in the oocyte prior to its ovulation. If the oocyte is not sufficiently equipped with maternally stored products, or if zygotic gene expression does not commence at the correct time, the embryo will die. One of the major abnormalities observed during early development is cellular fragmentation. We showed previously that cellular fragmentation in human embryos can be attributed to programmed cell death (PCD). Here, we demonstrate that the PCD that occurs during the 1-cell stage of mouse embryogenesis is likely to be regulated by many cell death genes either maternally inherited or transcribed from the embryonic genome. We have demonstrated for the first time the temporal expression patterns of nine cell death regulatory genes, and our preliminary experiments show that the expression of these genes is altered in embryos undergoing fragmentation. The expression of genes involved in cell death (MA-3, p53, Bad, and Bcl-xS) seems to be elevated, whereas the expression of genes involved in cell survival (Bcl-2) is reduced. We propose that PCD may occur by default in embryos that fail to execute essential developmental events during the first cell cycle.
新受精的植入前胚胎完全依赖于排卵前沉积和储存在卵母细胞中的母体mRNA和蛋白质。如果卵母细胞没有充分配备母体储存的产物，或者如果合子基因表达没有在正确的时间开始，胚胎将会死亡。在早期发育过程中观察到的主要异常之一是细胞碎片化。我们之前表明，人类胚胎中的细胞碎片化可归因于程序性细胞死亡（PCD）。在这里，我们证明在小鼠胚胎发生的1细胞阶段发生的PCD可能受许多母系遗传或从胚胎基因组转录的细胞死亡基因调控。我们首次展示了9个细胞死亡调节基因的时间表达模式，并且我们的初步实验表明这些基因的表达在发生碎片化的胚胎中发生了改变。参与细胞死亡的基因（MA-3、p53、Bad和Bcl-xS）的表达似乎升高，而参与细胞存活的基因（Bcl-2）的表达则降低。我们提出，在第一个细胞周期中未能执行基本发育事件的胚胎中，PCD可能会默认发生。
