Transcriptomic Signature of Trophoblast Differentiation in a Human Embryonic Stem Cell Model
ABSTRACT Identification of genes involved in trophoblast differentiation is of great interest in understanding cellular and molecular mechanisms involved in placental development and is relevant clinically to fetal development, fertility, and maternal health. Herein, we investigated differentiation of human embryonic stem cells (hESCs) down the trophoblast lineage by culture with bone morphogenetic protein 4 (BMP4) over a 10-day period. Within 2 days, the stemness markers POU5F1 and NANOG were markedly down-regulated, followed temporally by up-regulation of the CDX2, KRT7, HLA-G, ID2, CGA, and CGB trophoblast markers. To understand, on a global scale, changes in the transcriptome during the differentiation of hESCs down the trophoblast lineage, a large-scale microarray analysis was performed. Through whole-genome analysis, more than 3800 genes displayed statistically significant and 2-fold or greater changes in expression during the time course. Of those genes that showed the largest increases, many were involved in processes associated with trophoblast biology; however, novel genes were also identified. Some of them are hypothesized to be associated mainly with extracellular matrix remodeling (e.g., NID2) and cell migration and invasion (e.g., RAB25). Using Ingenuity pathways analysis software to identify signaling pathways involved in trophoblast differentiation or function, we discovered that many genes are involved in WNT/beta-catenin, ERK/MAPK, NFKB, and calcium signaling pathways, suggesting potential roles for these families in trophoblast development. This work provides an in vitro functional genomic model with which to identify genes involved in trophoblast development.
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ABSTRACT: During human pre-implantation development the totipotent zygote divides and undergoes a number of changes that lead to the first lineage differentiation in the blastocyst displaying trophectoderm and inner cell mass on day 5. The trophectoderm is a differentiated epithelium needed for implantation and the inner cell mass (ICM) forms the embryo proper and serves as a source for pluripotent embryonic stem cells. The blastocyst implants around day 7. The second lineage differentiation occurs in the ICM after implantation resulting in specification of primitive endoderm and epiblast. Knowledge on human pre-implantation development is limited due to ethical and legal restrictions on embryo research and scarcity of materials. Studies in the human are mainly descriptive and lack functional evidence. Most information on embryo development is obtained from animal models and embryonic stem cell cultures and should be extrapolated with caution. This paper reviews totipotency and the molecular determinants and pathways involved in lineage segregation in the human embryo, as well as the role of embryonic genome activation, cell cycle features and epigenetic modifications.Molecular Human Reproduction 04/2014; DOI:10.1093/molehr/gau027 · 3.48 Impact Factor
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ABSTRACT: It is imperative to unveil the full range of differentiated cell-types into which human pluripotent stem cells (hPSCs) can develop. The need is twofold: it will delimit the therapeutic utility of these stem cells and is necessary to place their position accurately in the developmental hierarchy of lineage potential. Accumulated evidence suggested that hPSC could develop in vitro into an extraembryonic lineage (trophoblast) that is typically inaccessible to pluripotent embryonic cells during embryogenesis. However whether these differentiated cells are truly authentic trophoblast has been challenged. Here we present a case for and a case against trophoblast differentiation from hPSCs. By analogy to other differentiation systems, our debate is broadly applicable, as it articulates higher and more challenging standards for judging whether a given cell-type has been genuinely produced from hPSC differentiation.Reproduction 02/2014; 147(5). DOI:10.1530/REP-14-0080
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ABSTRACT: Abnormal trophoblast lineage proliferation and differentiation in early pregnancy have been associated with the pathogenesis of placenta diseases of pregnancy. However, there is still a gap in understanding the molecular mechanisms of early placental development due to the limited primary trophoblast cultures and fidelity of immortalized trophoblast lines. Trophoblasts stem (TS) cells, an in vitro model of trophectoderm that can differentiate into syncytiotrophoblasts and extravillous trophoblasts, can be an attractive tool for early pregnancy research. TS cells are well established in mouse but not in humans due to insufficient knowledge of which trophoblast lineage-specific transcription factors are involved in human trophectoderm (TE) proliferation and differentiation. Here, we applied induced pluripotent stem cell technique to investigate the human trophoblast lineage-specific transcription factors. We established human induced trophoblast progenitor (iTP) cells by direct reprogramming the fibroblasts with a pool of mouse trophoblast lineage-specific transcription factors consisting of CDX2, EOMES, and ELF5. The human iTP cells exhibit epithelial morphology and can be maintained in vitro for more than 2 months. Gene expression profile of these cells was tightly clustered with human trophectoderms but not with human neuron progenitor cells, mesenchymal stem cells, or endoderm cells. These cells are capable of differentiating into cells with an invasive capacity, suggesting extravillous trophoblasts. They also form multi-nucleated cells which secrete human chorionic gonadotropin and estradiol, suggesting syncytiotrophoblasts. Our results provide the evidence that transcription factors CDX2 and EOMES may play critical roles in human iTP cell generation.Biochemical and Biophysical Research Communications 01/2013; 431(2). DOI:10.1016/j.bbrc.2012.12.135 · 2.28 Impact Factor