Jin Y, Lu S Y, Fresnoza A, Detillieux K A, Duckworth M L, Cattini P A
Department of Physiology, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, Canada R3E 0J9.
Placenta. 2009 Mar;30(3):226-35. doi: 10.1016/j.placenta.2008.12.011. Epub 2009 Jan 24.
The human (h) growth hormone/chorionic somatomammotropin (GH/CS) gene locus presents a unique model to gain insight into the molecular mechanisms that have allowed a closely related family of genes to be expressed in two distinct cell lineages/tissues: pituitary somatotrophs and placental syncytiotrophoblasts. However, studies of external factors that regulate gene expression have been somewhat limited by (i) a lack of human cell lines expressing endogenous GH or CS appropriately; and (ii) the fact that the GH/CS locus is unique to primates and thus does not exist in rodents. In the current study, a transgenic (171 h GH/CS-TG) mouse was generated containing the intact hGH/CS gene cluster and hGH locus control region (LCR) in a 171-kilobase DNA fragment. Pituitary and placental-specific expression of hGH/CS RNA was detected at embryonic day (E) 18.5. Immunostaining of hGH was seen in somatotrophs of the anterior pituitary beginning in late gestation. The presence of hCS protein was detected in the placental labyrinth in trophoblasts functionally analogous to the syncytiotrophoblast of the chorionic villi. This pattern of gene expression is consistent with the presence of essential components of the hGH/CS LCR. Transcript levels for hCS-A, hCS-B and placental hGH-variant increased in 171 hGH/CS-TG placenta during gestation (E11.5-E18.5), as previously observed in human placental development. Throughout gestation, hCS-A RNA levels were proportionately higher, accounting for 91% of total CS RNA by E18.5, comparable to term human placenta. Finally, the previous correlation between the transcription factor AP-2alpha and hCS RNA expression observed in developing primary human cytotrophoblast cultures, was extended to pregnancy in the 171 hGH/CS-TG mouse. The 171 hGH/CS-TG mouse thus provides a model to investigate hGH/CS gene expression, including in pregnancy.
人类（h）生长激素/绒毛膜促生长催乳素（GH/CS）基因位点呈现出一个独特的模型，有助于深入了解使一个密切相关的基因家族在两种不同细胞谱系/组织中表达的分子机制，这两种细胞谱系/组织分别是垂体生长激素细胞和胎盘合体滋养层细胞。然而，对调节基因表达的外部因素的研究在一定程度上受到以下限制：（i）缺乏能适当表达内源性GH或CS的人类细胞系；（ii）GH/CS基因位点是灵长类动物所特有的，在啮齿动物中不存在。在当前研究中，构建了一种转基因（171 h GH/CS-TG）小鼠，其在一个171千碱基的DNA片段中包含完整的hGH/CS基因簇和hGH基因座控制区（LCR）。在胚胎第18.5天检测到hGH/CS RNA在垂体和胎盘的特异性表达。从妊娠晚期开始，在前脑垂体的生长激素细胞中可见hGH的免疫染色。在胎盘迷路中，在功能上类似于绒毛膜绒毛合体滋养层细胞的滋养层细胞中检测到hCS蛋白的存在。这种基因表达模式与hGH/CS LCR的必需成分的存在一致。在妊娠期间（胚胎第11.5天至18.5天），171 hGH/CS-TG胎盘内hCS-A、hCS-B和胎盘hGH变体的转录水平升高，这与之前在人类胎盘发育中观察到的情况一致。在整个妊娠期间，hCS-A RNA水平相对较高，到胚胎第18.5天时占CS RNA总量的91%，与足月人类胎盘相当。最后，之前在原代人类细胞滋养层细胞培养物发育过程中观察到的转录因子AP-2α与hCS RNA表达之间的相关性，在171 hGH/CS-TG小鼠妊娠过程中也得到了证实。因此，171 hGH/CS-TG小鼠提供了一个研究hGH/CS基因表达的模型，包括在妊娠期间的表达。
