Differentiation- dependent regulation of adhesion molecules in trophoblast cells

滋养层细胞是哺乳动物胎盘的重要组成部分，在维持妊娠过程中具有重要的生物学作用。首先，滋养细胞必须附着在子宫内膜上，然后它们必须侵入到存在血管网络的深度。在这里，我们利用人BeWo绒毛癌细胞研究了表皮生长因子(EGF)对a2整合素表达、与胶原的粘附性和侵袭活性的影响。Northern印迹、Western印迹和流式细胞仪检测显示，EGF可诱导细胞内a2整合素基因和蛋白的表达。加入EGF后，人绒毛膜促性腺激素(HCG)分泌增加，提示BeWo细胞功能分化类似于正常滋养层细胞。EGF还呈剂量依赖性地刺激BeWo细胞的侵袭性。针对a2整合素的抗体抑制了这一作用，提示它可能是通过细胞表面整合素的增加而介导的。表皮生长因子对…的粘附性无影响更多的BeWo细胞转化为胶原蛋白，而它以剂量依赖的方式刺激趋化活性。A2整合素抗体可抑制细胞趋化活性的增加。这些结果表明，EGF可诱导滋养层细胞表达a2整合素，从而增强滋养层细胞的趋化活性，从而增强其对子宫内膜的侵袭能力。结果如下：1)流式细胞仪分析表明，加入EGF后48h可诱导BeWo细胞a5整合素表达。2)将人a5整合素基因的5‘侧翼区与荧光素酶基因连接，以监测该基因在加入EGF后的调控情况。与基础水平相比，EGF使a5整合素启动子的转录活性增加5倍。3)加入MEK抑制剂(PD98059)不能抑制上述诱导作用，提示EGF的作用似乎利用了一条不同于真正的MAP激酶级联的信号通路。较少

The trophoblast, an important component of the mammalian placenta, has several essential biological roles in the maintenance of pregnancy. First, trophoblasts must attach to the uterine endometrium, and then they must invade to a depth at which the vascular network exists. Here, we investigated the effects of epidermal growth factor (EGF) on a2 integrin expression, adhesiveness to collagen, and invasive activity using human BeWo choriocarcinoma cells. EGF induced the expression of a2 integrin mRNA and protein, as shown by Northern blotting, Western blotting, and flow cytometry. Human chorionic gonadotropin (hCG) secretion was enhanced by the addition of EGF, which suggests that the BeWo cells functionally differentiated similarly to normal trophoblasts. EGF also dose-dependently stimulated the invasiveness of BeWo cells. Antibody against a2 integrin inhibited this effect, suggesting that it may be mediated by an increase of cell surface integrin. EGF had no effect on the adhesiveness o … More f BeWo cells to collagen, whereas it stimulated the chemokinetic activity in a dose-dependent manner. The increase of chemokinetic activity was suppressed by antibody against a2 integrin. These results suggest that EGF may induce a2 integrin expression in trophoblasts, thereby enhancing their invasiveness into the endometrium via an increase of their chemokinetic activity.Transcriptional regulation of a5 integrin, one of the adhesion molecules that are induced in accordance with invasive activity of trophoblast, was also investigated. The following results were obtained.1) Flow cytometry analysis indicated that a5 integrin on BeWo cells were induced by the addition of EGF at 48 hours.2) The 5'-flanking region of the human a5 integrin gene was linked to the luciferase gene to monitor how this gene was regulated by the addition of EGF. EGF increased the transcriptional activity of a5 integrin promoter as high as 5 times compared to the basal level.3) The induction mentioned above was not suppressed by the addition of a MEK inhibitor (PD98059), suggesting that the action of EGF seemed to utilize a signaling pathway other than authentic MAP kinase cascade. Less