Cell-cell communication is critical for stem cell maintenance. Shoot apical meristem (SAM) located at the shoot tip harbors stem cells within the central zone (CZ). Their progeny differentiate in the adjacent peripheral zone (PZ). WUSCHEL (WUS) is a homeodomain transcription factor produced in a few cells of the organizing center (OC), located beneath the CZ. It has been shown to specify stem cell fate and also activate CLAVATA3 (CLV3) expression in cells of the CZ. CLV3 is a secreted peptide that activates a membrane bound receptor kinase-CLAVATA1 to restrict WUS transcription to the OC. It has been hypothesized that WUS activates CLV3 expression and stem cell fate in adjacent cells of the CZ by activating a non-cell autonomous signal. Contrary to this hypothesis, here we show that the WUS protein after being synthesized in cells of the OC, migrates into the superficial cell layers of the CZ where it activates CLV3 transcription by binding to its promoter elements. WUS also migrates laterally into the PZ to repress the expression of differentiation promoting transcription factors by binding to their regulatory regions. Migration of a stem cell inducing transcription factor into adjacent cells to activate a negative regulator, whereby restricting its own accumulation is unique to plant stem cell niches. While stem cell promoting transcription factor directly repressing differentiation promoting transcription factors to prevent premature differentiation of stem cell progenitors is conserved among diverse stem cell niches.
Plant stem cell maintenance involves direct transcriptional repression of differentiation program.
Treatment
View SamplesWe examined the gene expression profiles in ex vivo human CD4+ and CD8+ T cells from untreated HIV-infected individuals at different clinical stages and rates of disease progression. Profiles of pure CD4+ and CD8+ T cells subsets from HIV-infected nonprogressors who controlled viremia were indistinguishable from HIV-uninfected individuals. Similarly, no gene clusters could distinguish T cells from individuals with early from chronic progressive HIV infection, whereas differences were observed between uninfected or nonprogressors versus early or chronic progressors. In early/chronic HIV infection, three characteristic gene expression signatures were observed: (1) CD4+ and CD8+ T cells showed increased expression of interferon stimulated genes (ISGs). However, some ISGs including CXCL9, CXCL10, and CXCL11, and the IL15R in both CD4+ and CD8+ T cells and the anti-HIV ISG APOBEC3G in CD4+ T cells, were not upregulated. (2) CD4+ and CD8+ T cells showed a cluster similar to that observed in thymocytes, and (3) more genes were differentially regulated in CD8+ T cells than in CD4+ T cells, including a cluster of genes downregulated exclusively in CD8+ T cells. In conclusion, HIV infection induces a persistent T cell transcriptional profile, early in infection, characterized by a dramatic but potentially aberrant interferon response, and a profile suggesting an active thymic output.
Distinct transcriptional profiles in ex vivo CD4+ and CD8+ T cells are established early in human immunodeficiency virus type 1 infection and are characterized by a chronic interferon response as well as extensive transcriptional changes in CD8+ T cells.
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View SamplesThough obesity is a global epidemic, the physiological mechanisms involved are little understood. Recent advances reveal that susceptibility to obesity can be programmed by maternal and neonatal nutrition. Specifically, a maternal low protein diet during pregnancy causes decreased intrauterine growth, rapid postnatal catch-up growth and increased risk for diet-induced obesity. Given that the synthesis of the neurotransmitter 5-hydroxytryptamine (5-HT) is nutritionally regulated and 5-HT is a trophic factor, we hypothesized that maternal diet influences fetal 5-HT exposure, which then influences central appetite network development and the subsequent efficacy of 5-HT to control energy balance in later life. Consistent with our hypothesis, pregnant low protein fed rat mothers exhibited elevated serum 5-HT, which was also evident in the placenta and fetal brains at E16.5. This increase was associated with reduced hypothalamic expression of 5-HT2CR - the primary 5-HT receptor influencing appetite. As expected, reduced 5-HT2CR expression was associated with impaired sensitivity to 5-HT-mediated appetite suppression. 5-HT primarily achieves effects on appetite via 5-HT2CR stimulation of pro-opiomelanocortin (POMC) peptides within the arcuate nucleus of the hypothalamus (ARC). We reveal that 5-HT2ARs are also anatomically positioned to influence the activity of ARC POMC and that 5-HT2AR mRNA is increased in the hypothalamus of in utero growth restricted offspring that underwent rapid postnatal catch-up growth. Furthermore, these animals are more sensitive to 5-HT2AR agonist-induced appetite suppression. These findings may not only reveal a 5-HT-mediated mechanism underlying programming of obesity susceptibility but also provide a promising means to correct it, via a 5-HT2AR agonist treatment.
5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats.
Sex, Specimen part
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Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.
Specimen part
View SamplesIn gastrulation, distinct progenitor cell populations are induced and sorted into the three germ layers ectoderm, mesoderm and endoderm. In order to identify genes involved in germ layer specification and morphogenesis, we identified genes differentially expressed between ectodermal and mesendodermal progenitor cells. To do so, we first generated highly enriched pools of ectodermal and mesendodermal progenitor cells. Mesendodermal cells were generated by over-expressing the Nodal signal Cyclops in wild type embryos and ectodermal cells were taken from mz-one-eyed-pinhead (oep) mutant embryos. We then compared the transcriptome of ectodermal versus mesendodermal cells taken from embryos at 7 hours post fertilization (hpf). In wild type embryos at this stage (70% epiboly), the first ectodermal and mesendodermal progenitor cells have already been sorted into their respective germ layers and ingression of mesendodermal progenitors is still ongoing.
Identification of regulators of germ layer morphogenesis using proteomics in zebrafish.
Age, Specimen part, Subject, Time
View SamplesWe used an in vitro cardiomyocyte differentiation system with inducible Hey1 or Hey2 expression to study target gene regulation in cardiomyocytes (CM) generated from murine embryonic stem cells (ESC). The effects of Hey1 and Hey2 are largely redundant, but cell type specific. The number of regulated genes is comparable between ESC and CM, but the total number of binding sites is much higher, especially in ESC, targeting mainly genes involved in transcriptional regulation and developmental processes. Repression by Hey generally correlates with the extent of Hey-binding to target promoters, subsequent Hdac recruitment and lower histone acetylation. Functionally, treatment with the Hdac inhibitor TSA abolished Hey target gene regulation. However, in CM the repressive effect of Hey-binding is lost for a subset of genes. These lack Hey-dependent histone deacetylation in CM and are enriched for binding sites of cardiac specific activators like Srf, Nkx2-5, and Gata4.
Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.
No sample metadata fields
View SamplesWe used an in vitro cardiomyocyte differentiation system with inducible Hey1 or Hey2 expression to study target gene regulation in cardiomyocytes (CM) generated from murine embryonic stem cells (ESC). The effects of Hey1 and Hey2 are largely redundant, but cell type specific. The number of regulated genes is comparable between ESC and CM, but the total number of binding sites is much higher, especially in ESC, targeting mainly genes involved in transcriptional regulation and developmental processes. Repression by Hey generally correlates with the extent of Hey-binding to target promoters, subsequent Hdac recruitment and lower histone acetylation. Functionally, treatment with the Hdac inhibitor TSA abolished Hey target gene regulation. However, in CM the repressive effect of Hey-binding is lost for a subset of genes. These lack Hey-dependent histone deacetylation in CM and are enriched for binding sites of cardiac specific activators like Srf, Nkx2-5, and Gata4. Overall design: ES cells and cardiomyocytes with Hey1 or Hey2 overexpression were compared to control cells
Mechanisms of epigenetic and cell-type specific regulation of Hey target genes in ES cells and cardiomyocytes.
No sample metadata fields
View SamplesRNA-seq analysis of murine eGFP+ relbfl/flnfkb2fl/flCg1-Cre and Cg1-Cre splenic germinal center B cells identifies genes regulated by the transcription factors RELB and p52 (NF-kB2) in germinal center B cells. Overall design: Germinal center B cells from 12-week old relbfl/flnfkb2fl/flCg1-Cre and Cg1-Cre littermate mice immunized with sheep red blood cells (SRBC) were isolated at day 7 after immunization by flow cytometric sorting from splenic mononuclear cells. RNA was isolated, amplified and submitted for RNA-sequencing on an Illumina HiSeq2500 instrument for 35-40 million 2x50 paired-ended reads.
Transcription factors of the alternative NF-κB pathway are required for germinal center B-cell development.
Age, Specimen part, Subject
View SamplesInterleukin-1 receptor associated kinase 1 (IRAK1) is an important component of the IL-1R and TLR signaling pathways, which influence Th cell differentiation. Here, we show that IRAK1 promotes Th17 development by mediating IL-1 induced upregulation of IL-23R and subsequent STAT3 phosphorylation, thus enabling sustained IL-17 production. Moreover, we show that IRAK1 signaling fosters Th1 differentiation by mediating T-bet induction and counteracts Treg generation. Cotransfer experiments revealed that Irak1-deficient CD4+ T cells have a cell-intrinsic defect in generating Th1 and Th17 cells under inflammatory conditions in spleen, mesenteric lymph nodes and colon tissue. Furthermore, IRAK1 expression in T cells was shown to be essential for T cell accumulation in the inflamed intestine and mLNs. Transcriptome analysis ex vivo revealed that IRAK1 promotes T cell activation and induction of gut-homing molecules in a cell-intrinsic manner. Accordingly, Irak1-deficient T cells failed to upregulate surface expression of 47 integrin after transfer into Rag1-/- mice and their ability to induce colitis was greatly impaired. Lack of IRAK1 in recipient mice provided additional protection from colitis. Therefore, IRAK1 plays an important role in intestinal inflammation by mediating T cell activation, differentiation and their accumulation in the gut. Thus, IRAK1 is a promising novel target for therapy of inflammatory bowel diseases.
IRAK1 Drives Intestinal Inflammation by Promoting the Generation of Effector Th Cells with Optimal Gut-Homing Capacity.
No sample metadata fields
View SamplesRNAseq analysis of CD40 + IgM in vitro-stimulated (6 hours) murine relafl/flCD19-Cre (furtheron designated as RELA) and CD19-Cre (furtheron designated as WT) splenic B cells identifies genes regulated by the transcription factor RELA in activated B cells. Overall design: Splenic B cells from 12-week old relafl/flCD19-Cre and CD19-Cre littermate mice were isolated by magnetic cell separation from splenic mononuclear cells and stimulated in vitro for 6 hours with anti-CD40 and anti-IgM. RNA was isolated and submitted for RNA-sequencing on an Illumina HiSeq2000 instrument for 30 million single-ended reads.
Germinal center B cell maintenance and differentiation are controlled by distinct NF-κB transcription factor subunits.
No sample metadata fields
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