The tongue is a muscular organ in the vertebrate oral cavity that performs complex functions in daily life, including feeding and phonetic articulation. The tongue consists of mesenchyme cells of two distinct origins: the muscle cells are derived from occipital somites whereas the tendons and other connective tissues derived from the cranial neural crest. Cranial neural crest cells are important for the initiation of tongue swelling and proper patterning of intrinsic and extrinsic tongue muscle groups. However, little is known regarding the molecular and cellular mechanisms of tongue morphogenesis. We show that the odd-skipped related 1 (Osr1) transcription factor exhibits dynamic expression in the tongue mesenchyme during early tongue development. Tissue-specific inactivation of Osr1 in the early neural crest cells resulted in ectopic cartilage formation in the mouse tongue. We show that Sox9, the master regulator of chondrocyte differentiation, is initially widely expressed in the neural crest derived mesenchyme in the tongue and subsequently down-regulated concomitant by up-regulation of Osr1 expression. Osr1 mutant embryos exhibit persistent expression of Sox9 and chondrocyte differentiation from the neural crest derived tongue mesenchyme. Further biochemical analyses indicate that Osr1 may directly suppresses Sox9 gene expression in the tongue mesenchyme. These data reveal a novel mechanism in suppression of chondrogenic fate during tongue development. Remarkably, the ectopic cartilage in the Osr1 mutant mice resembles the entoglossal cartilage naturally develops in the avian tongue. These results suggest that modulation of expression of Osr1 may underline the evolutionary divergence in tongue cartilage formation. RNAs were isolated from microdissected E12 embryonic mouse tongue of Osr1f/-;Wnt1cre and control littermates and characterized by RNAseq Overall design: E12 mouse embryonic tongues were micro-dissceted, 3 pairs of control and mutant samples were pooled for the RNA extraction
Odd-skipped related-1 controls neural crest chondrogenesis during tongue development.
Specimen part, Cell line, Subject
View SamplesWe report the RNA profiles of both control and Kif3a f/f; Wnt1-Cre mandibular prominences of the murine face at embryonic day E11.5. We sought to determine the gene expression changes which occurr in the mandibular prominence when primary cilia are lost on neural crest cells. Overall design: The mandibular prominence from 10 control e11.5 embryos were collected and pooled, and 10 mutant e11.5 embryos were collected and pooled. RNA-seq was performed on these samples.
Cilia-dependent GLI processing in neural crest cells is required for tongue development.
Specimen part, Subject
View SamplesCombining an in vitro hNCC differentiation protocol with epigenomic profiling, we provide the first whole-genome characterization of cis-regulatory elements in this highly relevant cell type. With this data at hand, we have characterized the chromatin state and dynamics of all human gene promoters during the course of NCC in vitro differentiation. Most importantly, we have identified a large cohort of active and NCC-specific enhancers, which we showed to be functionally relevant in vivo, in the context of embryonic development. Finally, through sequence analysis of the identified NCC enhancers, we uncovered the orphan nuclear receptors NR2F1 and NR2F2 as novel hNCC transcriptional regulators both in vitro and in vivo. Overall design: RNA-seq experiments in human neural crest cells (hNCC)
Epigenomic annotation of enhancers predicts transcriptional regulators of human neural crest.
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View SamplesCanonical Wnt signalling regulates the self-renewal of most if not all stem cell systems. In the blood system, the role of Wnt signalling has been subject of much debate, with positive and negative roles of Wnt signalling proposed for hematopoietic stem cells (HSC). As we have shown previously, this controversy can be largely explained by the effects of different dosages of Wnt signalling. What remained unclear however, was why high Wnt signals would lead to loss of reconstituting capacity. To better understand this phenomenon, we have taken advantage of a series of hypomorphic mutant Apc alleles resulting in a broad range of Wnt dosages in HSCs, purified those HSCs and performed whole genome gene expression analyses. Gene expression profiling and functional studies show that HSCs with APC mutations lead to high Wnt levels , enhanced differentiation and diminished proliferation, but have no effect on apoptosis, collectively leading to loss of stemness. Thus, we provide mechanistic insight into the role of APC mutations and Wnt signalling in HSC biology. As Wnt signals are explored in various in vivo and ex vivo expansion protocols for HSCs, our findings also have clinical ramifications.
High Levels of Canonical Wnt Signaling Lead to Loss of Stemness and Increased Differentiation in Hematopoietic Stem Cells.
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View SamplesComparison of Mpl-/- mouse LSK cells, either treated with control (GFP) or Mpl lentivirus. Lineage negative bone marrow cells were isolated and transduced and transplanted into Mpl-/- recipient mice. After transplantation and follow up mice were sacrificed and LSK (lineage negative, Sca-1 positive, cKit positive) cells were isolated by FACS. RNA was isolated using RNeasy Micro Kit (Qiagen GmbH, Hilden, Germany) and RNA was amplified for microarray hybridization using the Nugen Ovation system (Nugen Technologies, AC Bemmel, Netherlands). The resulting material was hybridized to Affymetrix Mouse 430 2.0 arrays. RMA normalization and summarization was performed in R 2.10 using Bioconductor packages. The aim was to show the normalization of Mpl associated gene expression.
Lentiviral gene transfer regenerates hematopoietic stem cells in a mouse model for Mpl-deficient aplastic anemia.
Specimen part
View SamplesArp2/3 complex assembles branched actin filaments key to many cellular processes, but its organismal roles remain poorly understood. Here we employed conditional arpc4 knockout mice to study the function of the Arp2/3 complex in the epidermis.We found that depletion of the Arp2/3 complex by knockout of arpc4 results in skin abnormalities at birth that evolve into a severe psoriasis-like disease hallmarked by hyperactivation of transcription factor Nrf2. Knockout of arpc4 in cultured keratinocytes was sufficient to induce nuclear accumulation of Nrf2, upregulation of Nrf2-target genes and decreased filamentous actin levels. Furthermore, pharmacological inhibition of the Arp2/3 complex unmasked the role of branched actin filaments in Nrf2 regulation. Consistently, we unveiled that Nrf2 associates with the actin cytoskeleton in cells and binds to filamentous actin in vitro Finally, we discovered that Arpc4 is downregulated in both human and mouse psoriatic epidermis. Thus, the Arp2/3 complex affects keratinocytes'' shape and transcriptome through an actin-based cell-autonomous mechanism that influences epidermal morphogenesis and homeostasis. Overall design: Gene expression profile of wt and ARPC4 ko epidermis
Knockout of the Arp2/3 complex in epidermis causes a psoriasis-like disease hallmarked by hyperactivation of transcription factor Nrf2.
Specimen part, Cell line, Subject
View SamplesArp2/3 complex assembles branched actin filaments key to many cellular processes, but its organismal roles remain poorly understood. Here we employed conditional arpc4 knockout mice to study the function of the Arp2/3 complex in the epidermis.We found that depletion of the Arp2/3 complex by knockout of arpc4 results in skin abnormalities at birth that evolve into a severe psoriasis-like disease hallmarked by hyperactivation of transcription factor Nrf2. Knockout of arpc4 in cultured keratinocytes was sufficient to induce nuclear accumulation of Nrf2, upregulation of Nrf2-target genes and decreased filamentous actin levels. Furthermore, pharmacological inhibition of the Arp2/3 complex unmasked the role of branched actin filaments in Nrf2 regulation. Consistently, we unveiled that Nrf2 associates with the actin cytoskeleton in cells and binds to filamentous actin in vitro Finally, we discovered that Arpc4 is downregulated in both human and mouse psoriatic epidermis. Thus, the Arp2/3 complex affects keratinocytes'' shape and transcriptome through an actin-based cell-autonomous mechanism that influences epidermal morphogenesis and homeostasis. Overall design: Gene expression profile of wt, ARPC4 ko and EGFP-Nrf2 expressing keratinocytes.
Knockout of the Arp2/3 complex in epidermis causes a psoriasis-like disease hallmarked by hyperactivation of transcription factor Nrf2.
Specimen part, Cell line, Subject
View SamplesMouse LT-HSC were sorted and cultured in mScf, mTpo, mFlt3L, hIGFBP2 and Angptl5 for 2 days. These expression values were related to insertions of gamma-retroviral, lentiviral or alpharetroviral vectors carrying GFP which were retrieved after serial murine BM transplantation. The relation between gene expression in the cells responsible for long-term hematopoiesis and location of vector integration was investigated.
Alpharetroviral self-inactivating vectors: long-term transgene expression in murine hematopoietic cells and low genotoxicity.
Specimen part
View SamplesThe HMG-box factor Tcf1 is required during T-cell development in the thymus and mediates the nuclear response to Wnt signals. Tcf1/ mice have previously been characterized and show developmental blocks at the CD4CD8 double negative (DN) to CD4+CD8+ double positive transition. Due to the blocks in T-cell development, Tcf1/ mice normally have a very small thymus. Unexpectedly, a large proportion of Tcf1/ mice spontaneously develop thymic lymphomas with 50% of mice developing a thymic lymphoma/leukemia at the age of 16 wk. These lymphomas are clonal, highly metastatic, and paradoxically show high Wnt signaling when crossed with Wnt reporter mice and have high expression of Wnt target genes Lef1 and Axin2. In wild-type thymocytes, Tcf1 is higher expressed than Lef1, with a predominance of Wnt inhibitory isoforms. Loss of Tcf1 as repressor of Lef1 leads to high Wnt activity and is the initiating event in lymphoma development, which is exacerbated by activating Notch1 mutations. Thus, Notch1 and loss of Tcf1 functionally act as collaborating oncogenic events. Tcf1 deficiency predisposes to the development of thymic lymphomas by ectopic up-regulation of Lef1 due to lack of Tcf1 repressive isoforms and frequently by cooperating activating mutations in Notch1. Tcf1 therefore functions as a T-cellspecific tumor suppressor gene, besides its established role as a Wnt responsive transcription factor. Thus, Tcf1 acts as a molecular switch between proliferative and repressive signals during T-lymphocyte development in the thymus.
The nuclear effector of Wnt-signaling, Tcf1, functions as a T-cell-specific tumor suppressor for development of lymphomas.
Specimen part
View SamplesThe transcription factor Evi1 is essential for the formation and maintenance of hematopoietic stem cells, and induces clonal dominance with malignant progression upon constitutive activation by chromosomal rearrangements or transgene integration events. To understand the immediate and adaptive response of primary murine hematopoietic cells to the transcriptional upregulation of Evi1, we developed an inducible lentiviral vector system with a robust expression switch. We found that Evi1 delays differentiation and promotes survival in myeloid culture conditions, orchestrating a battery of genes involved in stemness (Aldh1a1, Ly6a [Sca1], Abca1, Epcam, among others). Importantly, Evi1 suppresses Cyclins and Cyclin-dependent kinases (Cdk), while it upregulates Cdk inhibitors, inducing quiescence in various proliferation-inducing cytokine conditions and operating in a strictly dose-dependent manner. Hematopoietic cells with persisting Evi1-induction tend to adopt a relatively low expression level. We thus classify Evi1 as a dormancy-inducing oncogene, likely requiring epigenetic and genetic compensation for cell expansion and malignant progression.
Activation of Evi1 inhibits cell cycle progression and differentiation of hematopoietic progenitor cells.
Specimen part
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