Warner C M, Exley G E, McElhinny A S, Tang C
Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA.
J Exp Zool. 1998;282(1-2):272-9.
The preimplantation period of mammalian development is characterized by cleavage of a one-cell embryo to a blastocyst stage embryo. During preimplantation development, 15%-50% of the embryos die as a result of factors that are largely unknown. Two parameters of preimplantation development, a fast rate of development and a low degree of fragmentation, are indicative of good embryo quality. There is mounting evidence that genes control both rate of development and degree of fragmentation. We have discovered a gene, Ped (preimplantation embryo development), which controls the rate of preimplantation embryonic cleavage. The Ped gene is encoded by two similar genes, Q7 and Q9, in the Q region of the mouse major histocompatibility complex (MHC). The Ped gene product is an MHC class Ib protein, the Qa-2 antigen. The mechanisms by which the Ped gene controls rate of embryonic cleavage division are being explored. In order to understand genetic mechanisms underlying the second criterion of embryo quality, degree of fragmentation, we have begun to assess expression of the genes that could potentially regulate apoptosis in preimplantation embryos. We have shown that staurosporine can induce apoptosis in mouse blastocysts. By using RT-PCR, we have shown that genes encoding protein in the two major gene families that regulate apoptosis, the Bcl-2 and caspase gene families, are present in preimplantation embryos. We hypothesize that there is a homeostatic mechanism by which genes that regulate cell survival and those that regulate cell death determine the overall viability of preimplantation embryos.
哺乳动物发育的植入前期的特点是单细胞胚胎分裂为囊胚期胚胎。在植入前期发育过程中，15% - 50%的胚胎会因 largely unknown 的因素而死亡。植入前期发育的两个参数，即快速的发育速度和低程度的碎片化，表明胚胎质量良好。越来越多的证据表明基因控制着发育速度和碎片化程度。我们发现了一个基因 Ped（植入前胚胎发育基因），它控制着植入前胚胎的分裂速度。Ped 基因由小鼠主要组织相容性复合体（MHC）Q 区域的两个相似基因 Q7 和 Q9 编码。Ped 基因产物是一种 MHC Ib 类蛋白，即 Qa - 2 抗原。目前正在探索 Ped 基因控制胚胎分裂速度的机制。为了理解胚胎质量第二个标准（碎片化程度）背后的遗传机制，我们已经开始评估可能调节植入前胚胎凋亡的基因的表达。我们已经表明，星形孢菌素可以诱导小鼠囊胚凋亡。通过使用逆转录聚合酶链反应（RT - PCR），我们已经表明，在调节凋亡的两个主要基因家族中编码蛋白质的基因，即 Bcl - 2 和半胱天冬酶基因家族，存在于植入前胚胎中。我们假设存在一种稳态机制，通过该机制调节细胞存活的基因和调节细胞死亡的基因决定植入前胚胎的整体活力。
