Transcriptional activation in mammalian embryos occurs in a stepwise manner. In mice, it begins at the late one-cell stage, followed by a minor wave of activation at the early two-cell stage, and then the major genome activation (MGA) at the late two-cell stage. Cellular homeostasis, metabolism, cell cycle, and developmental events are orchestrated before MGA by time-dependent changes in the array of maternal transcripts being translated (i.e., the translatome). Despite the importance of maternal mRNA and its correct recruitment for development, neither the array of recruited mRNA nor the regulatory mechanisms operating have been well cheracterized. We present the first comprehensive analysis of changes in the maternal component of the zygotic translatome during the transition from oocyte to late one-cell stage embryo, revealing global transitions in the functional classes of translated maternal mRNAs, and apparent changes in the underlying cis-regulatory mechanisms.
Analysis of polysomal mRNA populations of mouse oocytes and zygotes: dynamic changes in maternal mRNA utilization and function.
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View SamplesThe aim of this study was to establish an in vitro model to investigate the initial stages of human implantation based on co-culture of a) immortalized cells representing the receptive (Ishikawa) or non-receptive (HEC-1-A) endometrial epithelium with b) spheroids of a trophoblastic cell line (JEG-3) modified to express green fluorescent protein. After co-culturing Ishikawa cells with trophoblast spheroids, 310 and 298 genes increased or decreased their expression compared to non-co-cultured Ishikawa control cells, respectively; only 9 genes (5 increased and 4 decreased) were differentially expressed in HEC-1-A upon co-culture with trophoblast spheroids. Compared to HEC-1-A, the trophoblast challenge to Ishikawa cells differentially regulated the expression of 495 genes. In summary, upon co-culture with the trophoblast spheroids, non-receptive epithelium is characterized by a muted transcriptional response which in turn fails to activate the full transcriptional response that trophoblast spheroids undergo when co-cultured with receptive epithelium. Overall design: GFP expressing JEG-3 spheroids were co-cultured with confluent monolayers of receptive Ishikawa or non-receptive HEC-1-A epithelia. After 48 hours of co-culture, GFP+ (trophoblast JEG-3 spheroid cells) and GFP- cell fractions (receptive Ishikawa or non-receptive HEC-1-A epithelial cells) were isolated by fluorescence-activated flow cytometry (FACS). The specific transcriptional changes of the isolated cell populations were analyzed by RNA-seq profiling. Statistical significance of gene expression differences was set at an absolute log2 fold change (log2FC) =1 and an adjusted p-value <0.05.
Transcriptomic analysis of the interaction of choriocarcinoma spheroids with receptive vs. non-receptive endometrial epithelium cell lines: an in vitro model for human implantation.
Specimen part, Subject
View SamplesCloned embryos produced by somatic cell nuclear transfer (SCNT) display a plethora of phenotypic characteristics that make them different from fertilized embryos, indicating defects in the process of nuclear reprogramming by the recipient ooplasm. To elucidate the extent and timing of nuclear reprogramming, we used microarrays to analyze the transcriptome of mouse SCNT embryos during the first two cell cycles. We identified a large number of genes mis-expressed in SCNT embryos. We found that genes involved in transcription and regulation of transcription are prominent among affected genes, and thus may be particularly difficult to reprogram, and these likely cause a ripple effect that alters the transcriptome of many other functions, including oxidative phosphorylation, transport across membrane, and mRNA transport and processing. Interestingly, we also uncovered widespread alterations in the maternal (i.e. non transcribed) mRNA population of SCNT embryos. We conclude that gene expression in early SCNT embryos is grossly abnormal, and that this is at least in part the result of incomplete reprogramming of transcription factor genes.
Tough beginnings: alterations in the transcriptome of cloned embryos during the first two cell cycles.
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View SamplesThe events regulating human preimplantation development are still largely unknown, due to scarcity of material, ethical and legal limitations, and lack of reliable techniques to faithfully amplify the transcriptome of a single cell. Nonetheless, knowledge in human embryology is gathering renewed interest due to its close relationship with both stem cell biology and epigenetic reprogramming to pluripotency, and their centrality to regenerative medicine. Using carefully timed genome-wide transcript analyses on single oocytes and embryos, the analysis of the data allowed us to uncover a series of successive waves of embryonic transcriptional initiation which start as early as the 2 cell stage. In addition, we identified hierarchical activation of genes involved in the regulation of pluripotency. Finally, we developed HumER, a free database of human preimplantation human development gene expression to serve the scientific community. Importantly, our work links early transcription in the human embryo with the correct execution of the pluripotency program later in development, and paves the way for the identification of factors to improve epigenetic reprogramming.
Waves of early transcriptional activation and pluripotency program initiation during human preimplantation development.
Specimen part, Cell line
View SamplesUsing bone marrow cells of GFP:Gfi1 knock in mice, we separated Gfi1-high and Gfi1-low expressing cells in the classical CD11b+, GR1-low monocytic cell fraction. We sorted CD11b+, GR1-low GFP:Gfi1-high and low cells as well as CD11b+, GR1-high granulocytes and CD11b-high, GR1-intermediate cells from Gfi1-knock-out mice for further analysis.
Growth factor independence 1 (Gfi1) regulates cell-fate decision of a bipotential granulocytic-monocytic precursor defined by expression of Gfi1 and CD48.
Age, Specimen part
View SamplesLineage negative, CD44 negative, CD25 positive thymocytes were isolated from wt mice or Miz1 POZ-domain knockout mice to analyze the effect of loss of Miz1 in the DN3 population of T-cells
Miz-1 is required to coordinate the expression of TCRbeta and p53 effector genes at the pre-TCR "beta-selection" checkpoint.
Specimen part
View SamplesAlthough it is well established that the ovarian reserve diminishes with increasing age, and that a womans age is correlated to lower oocyte quality, the interplay of a diminished reserve and age on oocyte developmental competence is not clear. After maturation, oocytes are mostly transcriptionally quiescent, and developmental competence prior to embryonic genome activation (EGA) relies on maternal RNA and proteins. Age and ovarian reserve both affects oocyte developmental competence, however, their relative importance in this process are difficult to tease out, as ageing is accompanied by a decrease in ovarian reserve. Oocytes store large quantities of RNA, including several noncoding transcripts (ncRNAs) involved in early development transcription and translation modulation. Despite the central role of ncRNAs in maternal to zygote transition, no characterization of the ncRNA transcriptome in human oocytes has been reported. This study aims at identifying how the human oocyte transcriptome changes across reproductive ages and ovarian reserve levels, with the goal of identifying candidate markers of developmental competence, and to assess the independent relevance of age and ovarian reserve in the changes of the transcriptome
The transcriptome of human oocytes is related to age and ovarian reserve.
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View SamplesParthenogenetic stem cells were derived from parthenotes, then differentiated to mesenchymal stem cells. These were further reprogrammed to induced pluripotent stem cells, which were finally differentiated to secondary mesenchymal stem cells.
Accumulation of instability in serial differentiation and reprogramming of parthenogenetic human cells.
Sex, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Growth factor independence 1b (gfi1b) is important for the maturation of erythroid cells and the regulation of embryonic globin expression.
Specimen part
View SamplesGrowth factor independence 1b (Gfi1b) is a DNA binding repressor of transcription with vital functions in hematopoiesis. Gfi1b-null embryos die at midgestation very likely due to defects in erythro- and megakaryopoiesis. To analyze the full functionality of Gfi1b in embryonic erythropoiesis, we used conditionally deficient mice that harbor floxed Gfi1b alleles and one EpoR-Cre knock-in allele.
Growth factor independence 1b (gfi1b) is important for the maturation of erythroid cells and the regulation of embryonic globin expression.
Specimen part
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