During gastrulation, epiblast cells are pluripotent and their fate is thought to be constrained principally by their position. Cell fate is progressively restricted by localised signalling cues from areas including the primitive streak (PS). However, it is unknown whether this restriction accompanies, at the single cell level, a reduction in potency. Investigation of these early transition events in vitro is possible via the use of Epiblast Stem Cells (EpiSCs), self-renewing pluripotent cell lines equivalent to the postimplantation epiblast. Strikingly, EpiSCs express various early lineage-specific markers in self-renewing conditions. However, it is unknown whether cells that express these markers are pluripotent, spontaneously differentiated, or biased towards specific lineages. Here we show that EpiSC are inherently heterogeneous and contain two major and mutually exclusive subpopulations with PS and neural characteristics respectively. Using differentiation assays and embryo grafting we demonstrate that PS-like EpiSCs are biased towards mesoderm and endoderm differentiation but they still retain their pluripotent character. The acquisition of a PS character by undifferentiated EpiSC is mediated by paracrine Wnt signalling. Elevation of Wnt activity promotes further restriction into PS-associated cell fates which occurs via the generation of distinct clonal mesendodermal and neuromesodermal precursors. Collectively, our data suggest that primed pluripotency encompasses a range of reversible lineage-biased states reflecting the birth of pioneer lineage precursors from a pool of uncommitted EpiSCs similar to the earliest cell fate restriction events taking place in the gastrula-stage epiblast.
Distinct Wnt-driven primitive streak-like populations reflect in vivo lineage precursors.
Sex, Specimen part
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The cohesin-associated protein Wapal is required for proper Polycomb-mediated gene silencing.
Specimen part
View SamplesThe cohesin offloading protein Wapal also acts as a polycomb factor in flies. We examined its role in transcriptional role in murine embryonic stem cells (ESCs)
The cohesin-associated protein Wapal is required for proper Polycomb-mediated gene silencing.
Specimen part
View SamplesHuman T-lymphotropic virus type 1 (HTLV-1) is associated with the development of Adult T-cell Leukemia, an aggressive CD4+ T-cells malignancy. Here, we have developed a new procedure to infect humanized mice with proviruses displaying specific mutations, such as one leading to the loss of the PDZ domain-binding motif (PBM) of Tax. In order to specifically analyze the in vivo role of the PBM of Tax, a comparative study of infected hu-mice was performed. We used next-generation sequencing to perform genome-wide transcriptomic analysis of T-cells infected with wild-type HTLV-1 virus or with virus bearing a mutated form of Tax lacking the PBM. Our results suggest that Tax PBM might be involved in the regulation of genes implicated in proliferation, apoptosis and cytoskeleton organization. Overall design: mRNA profiles of T-cells obtained from hu-Mice infected with wild-type or Tax-PBM HTLV-1 were generated by deep-sequencing in triplicates using Illumina's Hiseq3000 platform.
PDZ domain-binding motif of Tax sustains T-cell proliferation in HTLV-1-infected humanized mice.
Specimen part, Subject
View SamplesProgrammable nucleases have enabled rapid and accessible genome engineering in eukaryotic cells and living organisms. However, their delivery into target cells can be technically challenging when working with primary cells or in vivo. Using engineered murine leukemia virus-like particles loaded with Cas9/sgRNA ribonucleoproteins (“Nanoblades”), we were able to induce efficient genome-editing in cell lines and primary cells including human induced pluripotent stem cells, human hematopoietic stem cells and mouse bone-marrow cells. Transgene-free Nanoblades were also capable of in vivo genome-editing in mouse embryos and in the liver of injected mice. Nanoblades can be complexed with donor DNA for “all-in-one” homology-directed repair or programmed with modified Cas9 variants to mediate transcriptional up-regulation of target genes. Nanoblades preparation process is simple, relatively inexpensive and can be easily implemented in any laboratory equipped for cellular biology. Overall design: Virus-like particles were purified on a sucrose cushion. Total RNA was extracted using Trizol and fragmented to ~100 nucleotides and used as input for cDNA library preparation. PCR-amplified libraries were sequenced on the Hiseq2500 platform (Illumina)
Genome editing in primary cells and in vivo using viral-derived Nanoblades loaded with Cas9-sgRNA ribonucleoproteins.
Cell line, Subject
View SamplesGlucocorticoids are a well recognized and common cause of muscle atrophy. Glucocorticoid-induced atrophy can be prevented by testosterone, but the molecular mechanisms underlying such protection have not been described. Thus, the global effects of testosterone on dexamethasone-induced changes in gene expression were evaluated in rat gastrocnemius muscle using Affymetrix 230_2 DNA microarrays. Gene expression was analyzed after 7 days administration of dexamethasone, dexamethasone plus testosterone, or vehicle. Effects of these agents on weights of gastrocnemius muscles from these animals has been reported (1. Zhao W, Pan J, Zhao Z, Wu Y, Bauman WA, and Cardozo CP. Testosterone protects against dexamethasone-induced muscle atrophy, protein degradation and MAFbx upregulation. J Steroid Biochem Mol Biol 110: 125-129, 2008.) Dexamethasone changed expression of 876 probe sets by at least 2-fold, of which 474 probe sets were changed by at least two fold in the opposite direction in the dexamethasone plus testosterone group (genes in opposition). Major biological themes represented by genes in opposition included IGF-1 signaling, protein synthesis, myogenesis and muscle development, and ubiquitin conjugases and ligases. Testosterone blocked increased expression of DDIT4 and eIF4EBP1, FOXO1 and of the p85 regulatory subunit of the IGF-1 receptor, while preventing decreased expression of IRS-1. Testosterone blocked decreased expression of LXR and suppressed upregulation of C/EBP beta and delta. Testosterone prevented increase expression of Cdkn1A (p21) and decrease expression of cyclins B and D, as well as many other changes that would be expected to reduce cell cycle progression. Testosterone prevented increased expression of muscle development factors Csrp3 and Mbn1 and blocked reduced expression of Wnt4. These data suggest that testosterone blocks multiple changes in gene expression that, collectively, would otherwise downregulate molecular signals that promote protein synthesis and muscle hypertrophy and that stimulate muscle protein catabolism.
REDD1 is a major target of testosterone action in preventing dexamethasone-induced muscle loss.
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View SamplesHuman aging is associated with loss of function and regenerative capacity. Human bone marrow derived mesenchymal stromal cells (hMSCs) are involved in tissue regeneration, evidenced by their capacity to differentiate into several lineages and therefore are considered the gold standard for cell-based regeneration therapy. Tissue maintenance and regeneration is dependent on stem cells and declines with age and aging is thought to influence therapeutic efficacy, therefore, more insight in the process of aging of hMSCs is of high interest. We, therefore, hypothesized that hMSCs might reflect signs of aging. In order to find markers for donor age, early passage hMSCs were isolated from bone marrow of 61 donors, with ages varying from 17-84, and clinical parameters, in vitro characteristics and microarray analysis were assessed. Although clinical parameters and in vitro performance did not yield reliable markers for aging since large donor variations were present, genome-wide microarray analysis resulted in a considerable list of genes correlating with human age. By comparing the transcriptional profile of aging in human with the one from rat, we discovered follistatin as a common marker for aging in both species. The gene signature presented here could be a useful tool for drug testing to rejuvenate hMSCs or for the selection of more potent, hMSCs for cell-based therapy.
A mesenchymal stromal cell gene signature for donor age.
Sex, Age
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Wnt signaling potentiates nevogenesis.
Specimen part, Cell line
View SamplesMelanocytes within benign human nevi are the paradigm for tumor suppressive senescent cells in a pre-malignant neoplasm. These cells typically contain mutations in either the BRAF or N-RAS oncogene and express markers of senescence, including p16. However, a nevus can contain 10s to 100s of thousands of clonal melanocytes and approximately 20-30% of melanoma are thought to arise in association with a pre-existing nevus. Neither observation is indicative of fail-safe senescence-associated proliferation arrest and tumor suppression. We set out to better understand the status of nevus melanocytes. Proliferation-promoting Wnt target genes, such as cyclin D1 and c-myc, were repressed in oncogene-induced senescent melanocytes in vitro, and repression of Wnt signaling in these cells induced a senescent-like state. In contrast, cyclin D1 and c-myc were expressed in many melanocytes of human benign nevi. Specifically, activated Wnt signalling in nevi correlated inversely with nevus maturation, an established dermatopathological correlate of clinical benignancy. Single cell analyses of lone epidermal melanocytes and nevus melanocytes showed that expression of proliferation-promoting Wnt targets correlates with prior proliferative expansion of p16-expressing nevus melanocytes. In a mouse model, activation of Wnt signaling delayed, but did not bypass, senescence of oncogene-expressing melanocytes, leading to massive accumulation of proliferation-arrested, p16-positive non-malignant melanocytes. We conclude that clonal hyperproliferation of oncogene-expressing melanocytes to form a nevus is facilitated by transient delay of senescence due to activated Wnt signaling. The observation that activation of Wnt signaling correlates inversely with nevus maturation, an indicator of clinical benignancy, supports the notion that persistent destabilization of senescence by Wnt signaling contributes to the malignant potential of nevi.
Wnt signaling potentiates nevogenesis.
Specimen part
View SamplesWe evaluated transcriptional profiles in peripheral blood mononuclear cells (PBMCs) from 54 pregnant women in Kenya, 19 of whom delivered preterm.
Influenza-Induced Interferon Lambda Response Is Associated With Longer Time to Delivery Among Pregnant Kenyan Women.
Specimen part, Treatment
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