We used microarrays to study the effect of Chd1 loss of function in mouse ES cells.
Chd1 regulates open chromatin and pluripotency of embryonic stem cells.
Cell line
View SamplesHepatic fibrosis, the wound-healing response to repeated liver injury, ultimately leads to cirrhosis. There is an urgent need to develop effective antifibrotic therapies. Ghrelin (encoded by Ghrl) is an orexigenic hormone that has pleiotrophic functions including protection against cell death1. Here we investigate whether ghrelin modulates liver fibrosis and protects from acute liver injury. Recombinant ghrelin reduced the fibrogenic response to prolonged bile duct ligation in rats. This effect was associated with decreased liver injury and myofibroblast accumulation as well as attenuation of the altered gene expression profile. Ghrelin also reduced fibrogenic properties in cultured hepatic stellate cells. Moreover, Ghrl-/- mice developed exacerbated hepatic fibrosis and liver damage after chronic injury. Ghrelin also protected rat livers from acute liver injury and reduced the extent of oxidative stress and the inflammatory response. In patients with chronic liver diseases, ghrelin serum levels decreased in those with advanced fibrosis and hepatic expression of the ghrelin gene correlated with expression of fibrogenic genes. Finally, in patients with chronic hepatitis C, single nucleotide polymorphisms of the ghrelin gene (-994CT and 604GA) influenced the progression of liver fibrosis. We conclude that ghrelin exerts antifibrotic effects on the liver and may represent a novel antifibrotic therapy.
Ghrelin attenuates hepatocellular injury and liver fibrogenesis in rodents and influences fibrosis progression in humans.
No sample metadata fields
View SamplesUnderstanding the transcriptional regulation of pluripotent cells is of fundamental interest and will greatly inform efforts aimed at directing differentiation of embryonic stem (ES) cells or reprogramming somatic cells. We first analyzed the transcriptional profiles of mouse ES cells and primordial germ cell (PGCs) and identified genes up-regulated in pluripotent cells both in vitro and in vivo. These genes are enriched for roles in transcription, chromatin remodeling, cell cycle and DNA repair. We developed a novel computational algorithm, CompMoby, which combines analyses of sequences both aligned and non-aligned between different genomes with a probabilistic segmentation model to systematically predict short DNA motifs that regulate gene expression. CompMoby was used to identify conserved over-represented motifs in genes up-regulated in pluripotent cells. We show that the motifs are preferentially active in undifferentiated mouse ES and Embryonic Germ cells in a sequence-specific manner, and that they can act as enhancers in the context of an endogenous promoter. Importantly, the activity of the motifs is conserved in human ES cells. We further show that the transcription factor NF-Y specifically binds to one of the motifs, is differentially expressed during ES cell differentiation and is required for ES cell proliferation. This study provides novel insights into the transcriptional regulatory networks of pluripotent cells. Our results suggest that this systematic approach can be broadly applied to understanding transcriptional networks in mammalian species.
Systematic identification of cis-regulatory sequences active in mouse and human embryonic stem cells.
Age, Specimen part, Time
View SamplesThe eukaryotic genome is organized in a three-dimensional structure called chromatin, constituted by DNA and associated proteins, the majority of which are histones. Post-translational modifications of histone proteins greatly influence chromatin structure and regulate many DNA-based biological processes. Methylation of lysine 36 of histone 3 (H3K36) is a post-translational modification functionally relevant during early steps of DNA damage repair. Here, we show that the JMJD-5 regulates H3K36 di-methylation and it is required at late stages of double strand break repair mediated by homologous recombination. Loss of jmjd-5 results in hypersensitivity to ionizing radiation and in meiotic defects, and it is associated with aberrant retention of RAD-51 at sites of double strand breaks. Analyses of jmjd-5 genetic interactions with genes required for resolving recombination intermediates (rtel-1) or promoting the resolution of RAD-51 double stranded DNA filaments (rfs-1 and helq-1) suggest that jmjd-5 prevents the formation of stalled postsynaptic recombination intermediates and favors RAD-51 removal. As these phenotypes are all recapitulated by a catalytically inactive jmjd-5 mutant, we propose a novel role for H3K36me2 regulation during late steps of homologous recombination critical to preserve genome integrity. Overall design: RNA sequencing of N2 and jmjd-5(tm3735) at 20C and 25C at generation 1 (G1) and generation 6 (G6)
JMJD-5/KDM8 regulates H3K36me2 and is required for late steps of homologous recombination and genome integrity.
Subject
View SamplesPluripotent stem cells are derived from culture of early embryos or the germline, and can be induced by reprogramming of somatic cells. Barriers to reprogramming are expected to exist that stabilize the differentiated state and have tumor suppression functions. However, we have a limited understanding of what such barriers might be. To find novel barriers to reprogramming to pluripotency, we compared the transcriptional profiles of the mouse germline to pluripotent and somatic cells, in vivo and in vitro. There is a remarkable global expression of the transcriptional program for pluripotency in Primordial Germ Cells (PGCs). We identify parallels between PGCs reprogramming to pluripotency and human germ cell tumorigenesis, including the loss of LATS2, a tumor suppressor kinase of the Hippo pathway. We show that knockdown of LATS2 increases the efficiency of induction of pluripotency in human cells. LATS2 RNAi, unlike p53 RNAi, specifically enhances the generation of fully reprogrammed iPS cells without accelerating cell proliferation. We further show that LATS2 represses reprogramming in human cells by post-transcriptionally antagonizing TAZ but not YAP, two downstream effectors of the Hippo pathway. These results reveal transcriptional parallels between germ cell transformation and the generation of iPS cells, and indicate that the Hippo pathway constitutes a barrier to cellular reprogramming.
Transcriptional analysis of pluripotency reveals the Hippo pathway as a barrier to reprogramming.
Sex, Specimen part
View SamplesCultured pluripotent stem cells are a cornerstone of regenerative medicine due to their ability to give rise to all cell types of the body. While pluripotent stem cells can be propagated indefinitely in vitro, pluripotency is paradoxically a very transient state in vivo, lasting 2-3 days around the time of blastocyst implantation. The exception to this rule is embryonic diapause, a reversible state of suspended development triggered by unfavorable conditions. Diapause is a strategy widely employed across the animal kingdom, including in mammals, but its regulation remains poorly understood. Here we report that inhibition of mechanistic target of rapamycin (mTor), a major nutrient sensor and promoter of growth, induces reversible pausing of mouse blastocyst development and allows their prolonged culture ex vivo. Paused blastocysts remain pluripotent and competent to give rise to embryonic stem (ES) cells and mice. We show that both natural diapause blastocysts in vivo and paused blastocysts ex vivo display pronounced reductions in mTor activity, translation and transcription. In addition, pausing can be induced directly in cultured ES cells and sustained for weeks in the absence of cell death or deviations from cell cycle distributions. We show that paused ES cells remain pluripotent, display a remarkable global suppression of transcription, and maintain a gene expression signature of diapaused blastocysts. These results allow for the first time the sustained suspension of development of a mammalian embryo in the laboratory, and shed light on the regulation of diapause and the origins of ES cells. Our findings have important implications in the fields of assisted reproduction, regenerative medicine, cancer, metabolic disorders and aging. Overall design: Examination of RNA expression profiles of embryonic stem cells in serum, 2i and paused states by RNA-seq
Inhibition of mTOR induces a paused pluripotent state.
Specimen part, Cell line, Treatment, Subject
View SamplesTransposable elements make up nearly half of mammalian genomes, yet are generally described as 'junk DNA' or genome parasites. The LINE1 retrotransposon is the most abundant class and is thought to be deleterious for cells, but it is paradoxically expressed at high levels during early development. Here, we report that LINE1 plays essential roles in mouse embryonic stem (ES) cells and pre-implantation embryos. In ES cells, LINE1 acts as a nuclear RNA scaffold that recruits Nucleolin and Kap1/Trim28 to repress Dux, the master activator of a gene expression program specific to the 2-cell stage. In parallel, LINE1 RNA mediates binding of Nucleolin and Kap1 to rDNA, thereby promoting rRNA synthesis and ES cell self-renewal. In embryos, LINE1 RNA is required for silencing of Dux, proper synthesis of rRNA and exit from the 2-cell stage. These results reveal an essential partnership between nuclear LINE1 RNA and chromatin factors in the regulation of transcription, developmental potency and ES cell self-renewal. Overall design: 3 replicates each of E14 ES cells two days after nucleofection with Lissaminated ASOs - RC (control) or LINE1, purified according to Lissamine+ using flow cytometry then lysed for RNA extraction and library generation (6 samples total)
A LINE1-Nucleolin Partnership Regulates Early Development and ESC Identity.
Specimen part, Cell line, Subject
View SamplesThe pluripotent mammalian epiblast undergoes unusually fast cell proliferation. This rapid growth is expected to generate a high transcriptional demand, but the underlying mechanisms remain unknown. We report that the chromatin remodeler Chd1, which binds the activating histone mark H3K4me3 and is associated with transcription, is required for development of the mouse epiblast. Chd1-/- embryos exhibit proliferation defects and increased apoptosis, are smaller than controls by E5.5, and fail to grow, become patterned or gastrulate. We show that Chd1-/- ES cells have a self-renewal defect and a genome-wide reduction in transcriptional output that is associated with losses in RNA Pol II elongation at growth-promoting genes, including ribosomal proteins. We also report that Chd1 directly regulates ribosomal RNA transcription and that both Chd1-/- epiblast cells in vivo and ES cells in vitro express significantly lower levels of ribosomal RNA. Single cell analyses reveal abnormal nucleolar morphology in mutants in vivo and in vitro. These data indicate that Chd1 promotes a globally elevated transcriptional output required to sustain the distinct rapid growth of the mouse epiblast. Overall design: Cell-number normalized RNA-seq from wild-type and Chd1-/- mouse embryonic stem cells.
Chd1 is essential for the high transcriptional output and rapid growth of the mouse epiblast.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Vitamin C induces Tet-dependent DNA demethylation and a blastocyst-like state in ES cells.
Specimen part, Treatment, Time
View SamplesThe study tests the hypothesis that maternal mRNA translation in oocytes is sensitive to the environment in which the oocytes mature. Amphiregulin (AREG) is a critical signal for oocyte maturation but also for oocyte developmental competence. Here we have used a genome-wide approach to determine whether the oocyte translational program is affected when oocytes mature in vivo in the absence of AREG.
Somatic cells regulate maternal mRNA translation and developmental competence of mouse oocytes.
Specimen part
View Samples