McKnight Kristen D, Hou Juan, Hoodless Pamela A
Genetics Graduate Program, University of British Columbia, Vancouver, British Columbia, Canada.
Dev Dyn. 2007 Oct;236(10):2909-17. doi: 10.1002/dvdy.21313.
Thyrotropin-releasing hormone (TRH) is a well-characterized regulator of the hypothalamic-pituitary-thyroid endocrine axis. Here, we describe the expression of Trh during early embryonic development in the mouse. We find Trh to be highly expressed during postimplantation stages in the mouse embryo, with expression first observed in the epiblast at embryonic day (E) 6.5. During gastrulation, Trh is expressed in the newly formed definitive endoderm cells, and at embryonic day (E) 7.75, marks the entire definitive endoderm. Subsequently, Trh mRNA levels rapidly decrease such that, by E9.0, expression in the definitive endoderm is no longer detected, after which neural expression predominates. Thus, Trh is expressed dynamically and specifically in the developing mouse definitive endoderm from E7.0 to E8.5. Trh is unique among definitive endoderm markers as it transiently marks the entire definitive endoderm population and is not expressed in the extraembryonic endoderm. Trh will be a valuable tool to study definitive endoderm formation in the mouse embryo.
促甲状腺激素释放激素（TRH）是下丘脑 - 垂体 - 甲状腺内分泌轴的一种特征明确的调节因子。在此，我们描述了Trh在小鼠胚胎早期发育过程中的表达情况。我们发现Trh在小鼠胚胎着床后阶段高度表达，最早在胚胎第（E）6.5天的上胚层中观察到其表达。在原肠胚形成过程中，Trh在新形成的定形内胚层细胞中表达，在胚胎第（E）7.75天，标记整个定形内胚层。随后，Trh mRNA水平迅速下降，以至于到E9.0时，在定形内胚层中的表达不再被检测到，此后神经表达占主导。因此，Trh在发育中的小鼠定形内胚层中从E7.0到E8.5动态且特异性地表达。Trh在定形内胚层标志物中是独特的，因为它短暂地标记整个定形内胚层群体，并且不在胚外内胚层中表达。Trh将成为研究小鼠胚胎定形内胚层形成的一个有价值的工具。
