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Transcriptional response induced by Wnt signaling in Caenorhabditis elegans affects lateral and ventral hypodermal cell development

ABSTRACT: The evolutionarily conserved Wnt/?-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector ?-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/?-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type?specific "mRNA tagging" to enrich for VPC and seam cell?specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type?specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells.

ORGANISM(S): Caenorhabditis elegans

PROVIDER: GSE52747 | GEO | 2015/11/18

SECONDARY ACCESSION(S): PRJNA229965

REPOSITORIES: GEO

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Project description:The Wnt signaling pathway plays a fundamental role during the development of metazoans, where it functions in the regulation of diverse processes including cell fate specification, cell migration, and stem cell renewal. Activation of the beta-catenin dependent or canonical Wnt signaling pathway upregulates expression of Wnt target genes to mediate an appropriate cellular response. In the nematode C. elegans, a Wnt signaling pathway similar to the canonical pathway regulates several processes during larval development, however few target genes of this pathway have been identified. To address this deficit, we conditionally activated Wnt signaling in living animals during a defined stage of larval life by expressing a dominant, activated beta-catenin protein, then used microarray analysis to identify genes showing altered expression compared to control animals. In this way we identified 166 differentially expressed genes, of which 104 were upregulated. A subset of the upregulated genes were validated by qPCR and showed altered expression in Wnt pathway mutants with decreased or increased Wnt signaling; we consider these genes to be candidate Wnt pathway targets in the C. elegans hermaphrodite larva. Amongst these was a group of 6 genes, including the cuticular collagen genes, bli-1 col-38, col-49 and col-71, that show a peak of expression in the mid L4 stage during normal development. The L4 expression of these genes suggests they may be expressed for use in the adult cuticle, and consistent with this, reduction of function for several of the genes leads to phenotypes suggestive of defects in cuticle function or integrity. Therefore this work has identified a large number of putative Wnt pathway target genes during larval life, including a small subset of Wnt-regulated collagen genes that may function in synthesis of the adult cuticle. a single pulse heat shock, inducing over-activated signal transduction in the Exp. Three treatment with three control strains of the identical genetical background strains

Project description:Sivakumar2011_WntSignalingPathway The secreted protein Wnt activates the heptahelical receptor Frizzled on nieghboring cells. Activation of Frizzled causes the recruitment of additional membrane proteins which in turn result in 1) the activation of the protein Dishevelled via phosphorylation and 2) the activation of a heterotrimeric G protein of unknown type. Activation of Dishevelled results in the down-regulation of the Beta-Catenin destruction complex which causes ubiquitination of Beta-Catenin and its ultimate degradation via the proteasome. Inhibition of the Beta-Catenin destruction complex yields a higher cytosolic concentration of Beta-Catenin, which enters the nucleus, binds various transcriptional regulatory molecules including the TCF/LEF class of proteins, and results in the transcription of TCF/LEF target genes. Activation of the heterotrimeric G-protein pathway in turn activates Phospholipase C which in turn catalyzes the catalysis of PI(4,5)P2 into DAG and IP3. Reference: The Wnt signalling pathway. You Wnt some, you lose some: oncogenes in the Wnt signaling pathway. Wnt signaling pathway. This model is described in the article: A systems biology approach to model neural stem cell regulation by notch, shh, wnt, and EGF signaling pathways. Sivakumar KC, Dhanesh SB, Shobana S, James J, Mundayoor S. OMICS 2011 Oct; 15(10): 729-737 Abstract: The Notch, Sonic Hedgehog (Shh), Wnt, and EGF pathways have long been known to influence cell fate specification in the developing nervous system. Here we attempted to evaluate the contemporary knowledge about neural stem cell differentiation promoted by various drug-based regulations through a systems biology approach. Our model showed the phenomenon of DAPT-mediated antagonism of Enhancer of split [E(spl)] genes and enhancement of Shh target genes by a SAG agonist that were effectively demonstrated computationally and were consistent with experimental studies. However, in the case of model simulation of Wnt and EGF pathways, the model network did not supply any concurrent results with experimental data despite the fact that drugs were added at the appropriate positions. This paves insight into the potential of crosstalks between pathways considered in our study. Therefore, we manually developed a map of signaling crosstalk, which included the species connected by representatives from Notch, Shh, Wnt, and EGF pathways and highlighted the regulation of a single target gene, Hes-1, based on drug-induced simulations. These simulations provided results that matched with experimental studies. Therefore, these signaling crosstalk models complement as a tool toward the discovery of novel regulatory processes involved in neural stem cell maintenance, proliferation, and differentiation during mammalian central nervous system development. To our knowledge, this is the first report of a simple crosstalk map that highlights the differential regulation of neural stem cell differentiation and underscores the flow of positive and negative regulatory signals modulated by drugs. This model is hosted on BioModels Database and identified by: BIOMD0000000397. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Transcriptional response induced by Wnt signaling in Caenorhabditis elegans affects lateral and ventral hypodermal cell development

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