Project description:Understanding the biological potential of fetal stem/progenitor cells will help define mechanisms in liver development and homeostasis. We isolated epithelial fetal human liver cells and established phenotype-specific changes in gene expression during continuous culture conditions. Fetal human liver epithelial cells displayed stem cell properties with multilineage gene expression, extensive proliferation and generation of mesenchymal lineage cells, although the initial epithelial phenotype was rapidly supplanted by meso-endodermal phenotype in culture. This meso-endodermal phenotype was genetically regulated through cytokine signaling, including transforming growth factor-b, bone morphogenetic protein, fibroblast growth factors, and other signaling pathways. Reactivation of HNF-3a (FOXA1) transcription factor, a driver of hepatic specification in the primitive endoderm, indicated that the meso-endodermal phenotype represented an earlier developmental stage of cells. We found that fetal liver epithelial cells formed mature hepatocytes in vivo, including after genetic manipulation using lentiviral vectors, offering convenient assays for analysis of further cell differentiation and fate. Taken together, these studies demonstrated plasticity in fetal liver epithelial stem/progenitor cells, offered paradigms for defining mechanisms regulating lineage switching in stem/progenitor cells, and provided potential avenues for regulating cell phenotypes for applications of stem/progenitor cells, such as for cell therapy. Gene expression was analyzed
Project description:DNA methylation is an important epigenetic control mechanism that has been shown to be associated with gene silencing through the course of development, maturation and aging. However, only limited data are available regarding the relationship between methylation and gene expression in human development. We analyzed the methylomes and transcriptomes of three human fetal liver samples (gestational age 20-22 weeks) and three adult human liver samples. Genes whose expression differed between fetal and adult numbered 7,673. Adult overexpression was associated with metabolic pathways and, in particular, cytochrome P450 enzymes, while fetal overexpression reflected enrichment for DNA replication and repair. Analysis for DNA methylation using the Illumina Infinium 450K HumanMethylation BeadChip showed that 42% of the quality filtered 426,154 methylation sites differed significantly between adult and fetal tissue (q≤0.05). Differences were small; 69% of the significant sites differed in their mean methylation beta value by ≤0.2. There was a trend among all sites toward higher methylation in the adult samples with the most frequent difference in beta being 0.1. Characterization of the relationship between methylation and expression revealed a clear difference between fetus and adult. Methylation of genes overexpressed in fetal liver showed the same pattern as seen for genes that were similarly expressed in fetal and adult liver. In contrast, adult overexpressed genes showed fetal hypermethylation that differed from the similarly expressed genes. An examination of gene region-specific methylation showed that sites proximal to the transcription start site or within the first exon with a significant fetal-adult difference in beta (>0.2) showed an inverse relationship with gene expression. Nearly half of the CpGs in human liver show a significant difference in methylation comparing fetal and adult samples. Sites proximal to the transcription start site or within the first exon that show a transition from hypermethylation in the fetus to hypomethylation or intermediate methylation in the adult are associated with inverse changes in gene expression. In contrast, increases in methylation going from fetal to adult are not associated with fetal-to-adult decreased expression. These findings indicate fundamentally different roles for and/or regulation of DNA methylation in human fetal and adult liver.
Project description:Rb null embryos exhibit defective fetal liver erythropoiesis. We used microarrays to compare Wt and Rb null fetal livers and to analyse gene expression differences which accompany and may underlie Rb null fetal liver degeneration, erythroid failure, and erythropoietic island dissolution. We used microarrays to compare Wt and Rb null fetal livers and analyse gene expression changes which accompany and may underlie fetal liver. Keywords: retinoblastoma, fetal liver, erythroblast, macrophage, cell death
Project description:During embryogenesis, development of hematopoietic stem cells (HSC) occurs in the fetal liver and involves coordinate programs of transcription. Taspase1, a highly conserved threonine protease, directly cleaves and regulates the TFIIA families of transcription factors. We discovered that loss of Taspase1 (Tasp1-/-) or non-cleavage of TFIIAα−β (TFIIAα-βnc/nc) leads to a severe fetal liver developmental retardation that is associated with impaired HSC self-renewal and loss of HSC quiescence. We used microarray to elucidate the mechanism(s) by which TFIIA regulates fetal liver hematopoiesis, and expression of targets of HoxA9 was found to be altered by gene set enrichment analyses.
Project description:The fetal hemoglobin (HbF) levels were 95.4 ± 1.5% and 4.4 ± 0.2% in fetal liver-derived and adult blood derived-cultured erythrocytes (n=5), respectively. Following RNA isolation from the CD71 high/GPA positive erythroblasts, gene expression analyses were performed using Affymetrix Human Gene 2.0 ST Array. The Affymetrix raw data files of microarray were preprocessed using robust multi-array average method for background correction, log-transformation, and quantile normalization. Differential gene expression between fetal liver derived- and adult peripheral blood derived-erythroblasts was determined using moderated t-statistics implemented in the Limma package. We found the 1366 genes were upregulated by more than 1.5-fold change with adjusted p-value less than 0.05 in fetal liver derived-erythroblasts.
Project description:The oscillation status of the circadian clock during late gestation is not clear. To gain a better understanding on the oscillation state of the clock and possible influences by maternal cues, we performed transcriptome analyses on the fetal liver tissue during late gestation. Fetal liver transcriptome data were analyzed and compared to adult mouse data in the public database: GSE11923 and GSE13093 (only samples GSM327130 to GSM327141). Re-analyzed (gc-RMA) data from GSE11923 and GSE13093 linked below as supplementary files. Fetal mouse liver tissues were collected at four hours intervals across embryonic day 18 and day 19. Groups 1 and 2.
Project description:The oscillation status of the circadian clock during late gestation is not clear. To gain a better understanding on the oscillation state of the clock and possible influences by maternal cues, we performed transcriptome analyses on the fetal liver tissue during late gestation. Fetal liver transcriptome data were analyzed and compared to adult mouse data in the public database: GSE11923 and GSE13093 (only samples GSM327130 to GSM327141). Re-analyzed (gc-RMA) data from GSE11923 and GSE13093 linked below as supplementary files.