Home Pratik, Ray Soma, Dutta Debasree, Bronshteyn Illya, Larson Melissa, Paul Soumen
Institute of Maternal-Fetal Biology, Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
J Biol Chem. 2009 Oct 16;284(42):28729-37. doi: 10.1074/jbc.M109.016840. Epub 2009 Aug 21.
During early mammalian development, genesis of the first two cell lineages, inner cell mass (ICM) and trophectoderm (TE), is dependent upon functions of key transcription factors that are expressed in a regulated and spatially restricted fashion. In this study, we demonstrate that during early mouse development, mRNA expression of transcription factor GATA3 is induced at the 4-cell stage and is consistently present during pre-implantation embryonic development. Interestingly, at the blastocyst stage, Gata3 mRNA is selectively up-regulated within the TE lineage, and GATA3 protein is abundantly present only in the TE but not in the ICM. Using mouse trophoblast stem cells (TS cells) as a model, we found that, knockdown of GATA3 by RNA interference (RNAi) down-regulates expression of caudal-type homeobox 2 (CDX2), a key regulator of the TE lineage. Chromatin immunoprecipitation (ChIP) analyses revealed that, in TS cells, GATA3 directly regulates Cdx2 transcription from a conserved GATA motif at the intron 1 region of the Cdx2 locus. ChIP analyses with mouse blastocysts also detected GATA3 occupancy at intron 1 of the Cdx2 locus. In addition, down-regulation of GATA3 in pre-implantation mouse embryos reduces Cdx2 expression and inhibits morula to blastocyst transformation. Our results indicate a novel function of GATA3, in which it is selectively expressed in TE, regulates expression of key genes in TE lineage, and is involved in morula to blastocyst transformation.
在哺乳动物早期发育过程中，最初两个细胞谱系即内细胞团（ICM）和滋养外胚层（TE）的形成，依赖于以受调控且空间受限的方式表达的关键转录因子的功能。在本研究中，我们证明在小鼠早期发育过程中，转录因子GATA3的mRNA表达在4细胞阶段被诱导，并在植入前胚胎发育期间持续存在。有趣的是，在囊胚阶段，Gata3 mRNA在TE谱系中被选择性上调，并且GATA3蛋白仅在TE中大量存在，而在ICM中不存在。以小鼠滋养层干细胞（TS细胞）为模型，我们发现，通过RNA干扰（RNAi）敲低GATA3可下调尾型同源框2（CDX2）的表达，CDX2是TE谱系的关键调节因子。染色质免疫沉淀（ChIP）分析显示，在TS细胞中，GATA3直接从Cdx2基因座内含子1区域的保守GATA基序调控Cdx2转录。对小鼠囊胚的ChIP分析也检测到GATA3在Cdx2基因座内含子1处的占据。此外，在植入前小鼠胚胎中下调GATA3会降低Cdx2表达并抑制桑椹胚向囊胚的转化。我们的结果表明GATA3具有一种新功能，即它在TE中选择性表达，调节TE谱系中关键基因的表达，并参与桑椹胚向囊胚的转化。
