TROPHOBLAST GENE EXPRESSION AND DIFFERENTIATION

胎盘以几种重要的方式促进胎儿发育， 发展 这个器官用于将发育中的胚胎植入 子宫;作为交换营养供应的管道， 母亲和胎儿之间排出的废物;作为防止 母体免疫系统对胎儿的攻击， 运输到胎儿循环的有害化合物， 金属;并作为分泌蛋白质的来源，调节母体 和胎儿生理学。 关于这最后一个作用，胎盘在 几个物种（包括啮齿动物，绵羊，奶牛和人类）是该网站 与脑垂体结构相关的蛋白质的合成 催乳素 这些激素调节母体卵巢类固醇的生成 （诱导孕酮产生以维持妊娠），肝脏 代谢（从储存形式中释放葡萄糖供胎儿使用）， 和乳房发育（为哺乳做准备）;这些激素还 进入胎儿室，在那里它们可能对胎儿产生直接影响。 例如肺的发育。 在小鼠中， 在胎盘中特异性合成的催乳素家族蛋白质 包括胎盘催乳素I、胎盘催乳素II、增殖素和 增殖相关蛋白 我们建议定义遗传元素 调节滋养层和颞叶特异性表达这些 小鼠的催乳素家族基因。 初期工作将侧重于 胎盘催乳素I和增殖素相关蛋白，由于活性 这些基因启动子中的一个在细胞培养中是滋养层特异性的 转染测定。 胎盘催乳素I提供了进一步的优势 在妊娠早期表达，因此可能代表 转录/分化因子的靶点作用于细胞的早期分化， 胎盘发育阶段;胎盘催乳素I基因启动子 因此也将用于产生永生化滋养层细胞 线 与此同时，增殖蛋白相关蛋白提供了一种独特的 处理小鼠滋养层分化，因为它表达在两个 滋养层细胞类型，不像催乳素家族的其他成员。 瞬时转染到啮齿动物绒毛膜癌细胞中和 将测定转基因小鼠中的体内表达以确定这些 监管要素。 定义后，这些元素将用于 确定负责以下事件的反式作用调节因子： 这些基因在滋养层细胞中的表达。 这种表达方式 在胎盘和胎儿发育过程中，以及在成人中， 将被调查。 鉴定和表征 因子将提供一种检测胎盘滋养层细胞的方法 分子水平上的差异。 由于滋养层细胞 与胚胎发育密切相关， 参与滋养层细胞分化的元素和因子， 功能将有助于检测、预防和治疗出生缺陷。

The placenta functions in several important ways in promoting fetal development. This organ serves to implant the developing embryo in the uterus; as a conduit for the exchange of nutritional supplies and excreted waste between the mother and the fetus; as a barrier preventing attack on the fetus by the maternal immune system, and preventing transport into the fetal circulation of hazardous compounds such as heavy metals; and as a source of secreted proteins that regulate both maternal and fetal physiology. In regard to this last role, the placenta in several species (including rodents, sheep, cows, and humans) is the site of synthesis of proteins that are structurally related to pituitary prolactin. These hormones regulate maternal ovarian steroidogenesis (inducing progesterone production to maintain pregnancy), liver metabolism (to release glucose from storage forms for use by the fetus), and mammary development (to prepare for lactation); these hormones also enter the fetal compartment, where they may have direct effects on fetal development, for example in lung development. In the mouse, the prolactin family of proteins synthesized specifically in the placenta includes placental lactogen I, placental lactogen II, proliferin, and proliferin-related protein. We propose to define the genetic elements that regulate the trophoblast- and temporal-specific expression of these prolactin family genes in the mouse. Initial efforts will focus on placental lactogen I and proliferin-related protein, since the activity of these gene promoters is trophoblast-specific in cell culture transfection assays. Placental lactogen I provides the further advantage of being expressed early during gestation, and therefore may represent a target for a transcription/differentiation factor acting at an early stage of placental development; the placental lactogen I gene promoter will therefore also be used to generate immortalized trophoblast cell lines. The proliferin-related protein, meanwhile, provides a unique handle on mouse trophoblast differentiation since it is expressed in two trophoblast cell types, unlike the other members of the prolactin family. Both transient transfections into rodent choriocarcinoma cells and in vivo expression in transgenic mice will be assayed to define these regulatory elements. Once defined, these elements will then be used to identify a trans-acting regulatory factor(s) responsible for the expression of these genes in trophoblast cells. The expression of this factor during placental and fetal development, as well as in the adult, will then be investigated. Identification and characterization of this factor(s) will provide a means to examine placental trophoblast cell differentiation on a molecular level. Since the trophoblast cells are intimately involved in embryonic development, identifying the genetic elements and factors involved in trophoblast cell differentiation and function will aid in detecting, preventing, and treating birth defects.