Reprogrammed somatic cells offer a valuable source of pluripotent cells that have the potential to differentiate into many cells types and provide a new tool for regenerative medicine. In the present study we differentiated induced pluripotent stem cells (iPS cells) into hepatic cells. We first showed that mouse iPS cells could from a complete liver in mouse embryo (E14.5) including hepatocytes, endothelial cells, sinusoidal cells and resident macrophages. We then designed a highly efficient hepatocyte differentiation protocol using defined factors on human embryonic stem cells (ES cells). This protocol was found to generate more than 80% albumin expressing cells that show hepatic functions and express most of liver genes as shown by microarray analyses. Similar results were obtained when human iPS cells were induced to differentiate following the same procedure.
Highly efficient generation of human hepatocyte-like cells from induced pluripotent stem cells.
Specimen part, Cell line
View SamplesThe availability of pluripotent stem cells offers the possibility of using such cells to model hepatic disease and development. With this in mind, we previously established a protocol that facilitates the differentiation of both human embryonic stem cells and induced pluritpotent cells into cells with hepatocyte characteristics. The use of highly defined culture conditions and the avoidance of feeder cells or embryoid bodies allowed synchronous and reproducible differentiation to occur. The differentiation toward a hepatocytelike fate appeared to recapitulate many of the stages normally associated with the formation of hepatocytes in vivo. In the current study we addressed the feasibility of using human pluripotent stem cells to probe the molecular mechanisms underlying human hepatocyte differentiation. We demonstrate i) that human ES cells express a number of mRNAs that characterize each stage in the differentiation process, ii) that gene expression can be efficiently depleted throughout the differentiation time course using shRNAs expressed from lentiviruses, and iii) that the nuclear hormone receptor HNF4a is essential for specification of human hepatic progenitor cells by establishing expression of the network of transcription factors that control hepatocyte cell fate.
HNF4A is essential for specification of hepatic progenitors from human pluripotent stem cells.
Specimen part, Time
View SamplesMost differentiation protocols for generation of hepatocyte-like cells from iPS cells generate cells with heterogenous expression of hepatic markers, which confounds results from liver disease models involving complex traits and subtle phenotypes
Mapping the Cell-Surface N-Glycoproteome of Human Hepatocytes Reveals Markers for Selecting a Homogeneous Population of iPSC-Derived Hepatocytes.
Specimen part
View SamplesBackground and Aims: Although the zinc finger transcription factor GATA4 has been implicated in regulating jejunal gene expression, the contribution of GATA4 in controlling jejunal physiology has not been addressed. Methods: We generated mice in which the Gata4 gene was specifically deleted in the small intestinal epithelium. Measurements of plasma cholesterol and phospholipids, intestinal absorption of dietary fat and cholesterol, and gene expression were performed on these animals. Results: Mice lacking GATA4 in the intestine displayed a dramatic block in their ability to absorb cholesterol and dietary fat. Comparison of the global gene expression profiles of control jejunum, control ileum, and GATA4 null jejunum by gene array analysis demonstrated that GATA4 null jejunum lost expression of 53% of the jejunal-specific gene set and gained expression of 47% of the set of genes unique to the ileum. These alterations in gene expression included a decrease in mRNAs encoding lipid and cholesterol transporters as well as an increase in mRNAs encoding proteins involved in bile acid absorption. Conclusion: Our data demonstrate that GATA4 is essential for jejunal function including fat and cholesterol absorption and confirm that GATA4 plays a pivotal role in determining jejunal versus ileal identity.
GATA4 is essential for jejunal function in mice.
No sample metadata fields
View SamplesHepatocytes are polarized epithelial cells whose function depends upon their ability to distinguish between the apical and basolateral surfaces that are located at intercellular tight junctions. It has been proposed that the signaling cascades that originate at these junctions influence cellular activity by controlling gene expression in the cell nucleus. To assess the validity of this proposal with regard to hepatocytes, we depleted expression of the tight junction protein junctional adhesion molecule-A (JAM-A) in the HepG2 human hepatocellular carcinoma cell line. Reduction of JAM-A resulted in a striking change in cell morphology, with cells forming single-layered sheets instead of the normal multi-layered clusters. In the absence of JAM-A, other tight junction proteins were mislocalized, and canaliculi, which form the apical face of the hepatocyte, were consequently absent. While most changes in gene expression were modest, there was a strong transcriptional induction of the adherens junction protein E-cadherin in cells with reduced levels of JAM-A. This increase in E-cadherin was partially responsible for the observed alterations in cell morphology and mislocalization of tight junction proteins. We therefore propose that we have uncovered a novel mechanism for crosstalk between specific components of tight and adherens junctions that can be utilized to regulate adhesion between hepatic cells and to maintain hepatocyte cell polarity.
Junctional adhesion molecule-A is critical for the formation of pseudocanaliculi and modulates E-cadherin expression in hepatic cells.
No sample metadata fields
View SamplesTo study the role of hepatic nuclear factor alpha (HNF4a in hepatogenesis, we used loxP-Cre technology to eliminate it from developing mouse livers.
Hepatocyte nuclear factor 4alpha orchestrates expression of cell adhesion proteins during the epithelial transformation of the developing liver.
Specimen part
View SamplesSerum response factor (SRF) is a transcription factor that binds to the serum response element (SRE) of genes that are expressed in response to mitogens. SRF plays essential roles in muscle and nervous system development; however, little is known about the role of SRF during liver growth and function. To examine the function of SRF in the liver, we generated mice in which the Srf gene was specifically disrupted in hepatocytes. The survival of mice lacking hepatic SRF activity was lower than that of control mice; moreover, surviving mutant mice were smaller and had lower blood glucose and triglyceride levels compared with control mice. Srf-deficient livers were also smaller than control livers, hepatocyte morphology was abnormal, and liver-cell proliferation and viability was compromised. Gene array and quantitative RT-PCR analysis of SRF depleted livers revealed a reduction in mRNAs encoding components of the growth hormone/IGF1 pathway, cyclins, several metabolic regulators, and cytochrome p450 enzymes. Conclusion: SRF is essential for hepatocyte proliferation and survival, liver function, and control of postnatal body growth by regulating hepatocyte gene expression.
No associated publication
No sample metadata fields
View SamplesBackground and Aims: HNF4a is a nuclear hormone receptor transcription factor that has been shown to be required for hepatocyte differentiation and development of the liver. It has also been implicated in regulating expression of genes that act in the epithelium of the lower gastrointestinal tract. This implied that HNF4a might be required for development of the gut. Methods: We generated mouse embryos in which HNF4a was ablated in the epithelial cells of the fetal colon using Cre-loxP technology. Embryos were examined using a combination of histology, immunohistochemistry, gene array and RT-PCR, and chromatin immunoprecipitation analyses to define the consequence of loss of HNF4a on colon development. Results: Embryos could be generated until E18.5 that lacked HNF4a in their colon. Although, early stages of colonic development occurred, HNF4a null colons failed to form normal crypts. In addition, goblet cell maturation was perturbed and expression of an array of genes that encode proteins with diverse roles in colon function was disrupted. Several genes whose expression in the colon was dependent on HNF4a contained HNF4abinding sites sequences within putative transcriptional regulatory regions and a subset of these sites were occupied by HNF4a in vivo. Conclusion: HNF4a is a transcription factor that is essential for development of the mammalian colon, regulates goblet cell maturation and is required for expression of genes that control normal colon function and epithelial cell differentiation.
Hepatocyte nuclear factor 4alpha is essential for embryonic development of the mouse colon.
Specimen part
View SamplesTo define changes in gene expression resulting from loss of hnf4 in the small intestine.
No associated publication
Sex, Age, Specimen part
View SamplesRegulation of gene expression at the post-transcriptional level plays an indispensable role during TGFbeta-induced EMT and metastasis. This regulation involves a transcript-selective translational regulatory pathway in which a ribonucleoprotein (mRNP) complex, consisting of heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) and eukaryotic elongation factor 1A1 (eEF1A1), binds to a 3-UTR regulatory BAT (TGF activated translation) element and silences translation of Dab2 and ILEI mRNAs, two transcripts which are involved in mediating EMT. TGFbeta activates a kinase cascade terminating in the phosphorylation of hnRNP E1, by isoform-specific stimulation of protein kinase B/Akt2, inducing the release of the mRNP complex from the 3-UTR element, resulting in the reversal of translational silencing and increased expression of Dab2 and ILEI transcripts.
Establishment of a TGFβ-induced post-transcriptional EMT gene signature.
Specimen part
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