Cai Liquan, Zhang Jian, Duan Enkui
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People's Republic of China.
Cytokine. 2003 Sep 21;23(6):170-8. doi: 10.1016/s1043-4666(03)00222-9.
Embryo implantation depends on the synchronized development of the blastocyst and the endometrium. This process is highly controlled by the coordinated action of the steroid hormones: estrogen and progesterone. By autocrine, paracrine or juxtacrine routes, some growth factors or cytokines are involved in this steroidal regulation pathway. Here we report the effects of epidermal growth factor (EGF) on embryo implantation in the mouse, the expression and distribution patterns of EGF protein in the mouse blastocyst, ectoplacental cone (EPC) and peri-implantation uterus on days 1-8 of gestation. By RT-PCR and dot blot, we found that EGF and its receptor (EGFR) are co-expressed in the blastocyst and peri-implantational uteri of pregnant days 2-8 (D2-D8) mice. Injection of EGF antibody into a uterine horn on the third day of pregnancy (D3) significantly reduced the number of mouse embryos that implanted on D8, indicating EGF have a function in the mouse embryo implantation.Further investigation by using indirect immunofluorescence and confocal microscope was made to trace EGF and EGFR protein localization during the mouse embryo implantation. EGF and EGFR are co-localized in the blastocyst, and in the secondary trophoblastic giant cells (SGC) of the EPC. At the pre-implantation stage, the distribution of EGF protein in the mouse uterus changes from epithelium to stroma. On D1 of pregnancy, EGF is mainly distributed in uterine stroma and myometrium. On D2, it is present in the uterine epithelium. On D3, it changes again from the uterine epithelium to the stroma. By D4, EGF is predominantly in the stroma. This dynamic distribution correlates with the proliferation activity of uterine cells at each period. On D6-D8 of embryo implantation, EGF 3 protein accumulates at the uterine mesometrial pole, a region that contributes to the trophoblastic invasiveness and placentation. This temporal and spatial localization of EGF protein in the mouse uterus implicates the cytokine in the regulation of trophoblastic invasiveness and uterine receptiveness.
胚胎着床依赖于囊胚和子宫内膜的同步发育。这一过程受到类固醇激素（雌激素和孕激素）协同作用的高度调控。通过自分泌、旁分泌或近分泌途径，一些生长因子或细胞因子参与了这一甾体调节途径。在此，我们报告了表皮生长因子（EGF）对小鼠胚胎着床的影响，以及妊娠第1 - 8天小鼠囊胚、外胎盘锥（EPC）和着床期子宫中EGF蛋白的表达及分布模式。通过逆转录聚合酶链反应（RT-PCR）和斑点印迹法，我们发现EGF及其受体（EGFR）在妊娠第2 - 8天（D2 - D8）小鼠的囊胚和着床期子宫中共同表达。在妊娠第3天（D3）向子宫角注射EGF抗体，显著减少了在D8着床的小鼠胚胎数量，表明EGF在小鼠胚胎着床过程中发挥作用。通过间接免疫荧光和共聚焦显微镜进行进一步研究，以追踪小鼠胚胎着床过程中EGF和EGFR蛋白的定位。EGF和EGFR在囊胚以及EPC的次级滋养层巨细胞（SGC）中共定位。在着床前阶段，小鼠子宫中EGF蛋白的分布从上皮细胞转变为基质细胞。在妊娠第1天，EGF主要分布在子宫基质和肌层。在D2，它存在于子宫上皮细胞中。在D3，它再次从子宫上皮细胞转变为基质细胞。到D4时，EGF主要存在于基质细胞中。这种动态分布与每个时期子宫细胞的增殖活性相关。在胚胎着床的D6 - D8天，EGF蛋白在子宫系膜极积累，该区域有助于滋养层的侵袭和胎盘形成。EGF蛋白在小鼠子宫中的这种时空定位表明该细胞因子在调节滋养层侵袭和子宫接受性方面发挥作用。
