Departments of Biotechnology Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan.
Reproduction. 2011 Feb;141(2):259-68. doi: 10.1530/REP-10-0355. Epub 2010 Nov 17.
The mouse Crxos gene encodes three structurally related homeoproteins, EGAM1, EGAM1N, and EGAM1C, as transcription and splicing variants. Recently, we identified the functions of EGAM1 and EGAM1N in the regulation of differentiation in mouse embryonic stem cells. However, the function of EGAM1C remains unknown. To explore the additional roles of these proteins, the ontogenic expression of the respective mRNAs in post implantation mouse embryos and extraembryonic tissues, particularly from embryonic day (E) 10.5 to E18.5, was analyzed. The expression of Egam1n mRNA was specifically detected in embryos throughout this period, whereas that of Egam1 was undetectable in any of the tissues examined. However, in the placenta, Egam1c mRNA and its encoded protein were detected after E16.5, and these expression levels increased by E18.5 immediately before partum. Quantitative RT-PCR and in situ hybridization analyses in placentae revealed that the spatial and temporal expression patterns of the Egam1c mRNA were related to some extent with those of Prl3a1 and Prl5a1 and partially overlapped that of Prl3b1, which are members of the placental prolactin (PRL) gene family. When EGAM1C was overexpressed moderately in mouse trophoblast stem cells as a model for undifferentiated and differentiating placental cell types, the expression levels of endogenous Prl3b1 and Prl5a1 were enhanced under both undifferentiated and differentiating culture conditions. These results indicated that EGAM1C may play a role in the expression of members of the placental PRL gene family, such as Prl3b1 and Prl5a1.
鼠 Crxos 基因编码三种结构相关的同源蛋白，即 EGAM1、EGAM1N 和 EGAM1C，它们是转录和剪接变体。最近，我们鉴定了 EGAM1 和 EGAM1N 在调控小鼠胚胎干细胞分化中的功能。然而，EGAM1C 的功能仍然未知。为了探索这些蛋白的其他作用，我们分析了各自的 mRNA 在植入后小鼠胚胎和胚外组织中的胚胎发生表达，特别是从胚胎日 (E) 10.5 到 E18.5。在此期间，特异性检测到 Egam1n mRNA 在胚胎中的表达，而在任何检查的组织中均未检测到 Egam1 的表达。然而，在胎盘组织中，Egam1c mRNA 及其编码的蛋白在 E16.5 后被检测到，其表达水平在 E18.5 时增加，并在分娩前立即增加。在胎盘组织中进行的定量 RT-PCR 和原位杂交分析表明，Egam1c mRNA 的时空表达模式在某种程度上与 Prl3a1 和 Prl5a1 相关，并且与 Prl3b1 的表达模式部分重叠，Prl3b1 是胎盘催乳素 (PRL) 基因家族的成员。当 EGAM1C 在小鼠滋养层干细胞中适度过表达时，作为未分化和分化胎盘细胞类型的模型，内源性 Prl3b1 和 Prl5a1 的表达水平在未分化和分化培养条件下均增强。这些结果表明，EGAM1C 可能在胎盘 PRL 基因家族成员（如 Prl3b1 和 Prl5a1）的表达中发挥作用。
