Project description:Synovial sarcoma is a deadly soft-tissue malignancy with a predilection for adolescents and young adults. Mice recapitulate synovial sarcomagenesis from expression of SS18-SSX2 in certain cells. Concomitant expression of a stabilized form of beta-catenin enhances synovial sarcomagenesis and expands the potential cells of origin. Mice bearing conditional expression of SS18-SSX2 from the Rosa26 locus and conditional excision of the 3rd exon of beta-catenin, each activated in the leg by Cre-recombinase expressed from an adeno-associated viral vector, formed large tumors at brief latency.
Project description:Lee2003 - Roles of APC and Axin in Wnt
Pathway (without regulatory loop)
This model is described in the article:
The roles of APC and Axin
derived from experimental and theoretical analysis of the Wnt
Lee E, Salic A, Krüger R,
Heinrich R, Kirschner MW.
PLoS Biol. 2003 Oct; 1(1): E10
Wnt signaling plays an important role in both oncogenesis
and development. Activation of the Wnt pathway results in
stabilization of the transcriptional coactivator beta-catenin.
Recent studies have demonstrated that axin, which coordinates
beta-catenin degradation, is itself degraded. Although the key
molecules required for transducing a Wnt signal have been
identified, a quantitative understanding of this pathway has
been lacking. We have developed a mathematical model for the
canonical Wnt pathway that describes the interactions among the
core components: Wnt, Frizzled, Dishevelled, GSK3beta, APC,
axin, beta-catenin, and TCF. Using a system of differential
equations, the model incorporates the kinetics of
protein-protein interactions, protein synthesis/degradation,
and phosphorylation/dephosphorylation. We initially defined a
reference state of kinetic, thermodynamic, and flux data from
experiments using Xenopus extracts. Predictions based on the
analysis of the reference state were used iteratively to
develop a more refined model from which we analyzed the effects
of prolonged and transient Wnt stimulation on beta-catenin and
axin turnover. We predict several unusual features of the Wnt
pathway, some of which we tested experimentally. An insight
from our model, which we confirmed experimentally, is that the
two scaffold proteins axin and APC promote the formation of
degradation complexes in very different ways. We can also
explain the importance of axin degradation in amplifying and
sharpening the Wnt signal, and we show that the dependence of
axin degradation on APC is an essential part of an
unappreciated regulatory loop that prevents the accumulation of
beta-catenin at decreased APC concentrations. By applying
control analysis to our mathematical model, we demonstrate the
modular design, sensitivity, and robustness of the Wnt pathway
and derive an explicit expression for tumor suppression and
This model is hosted on
and identified by:
To cite BioModels Database, please use:
Chelliah V et al. BioModels: ten-year
anniversary. Nucl. Acids Res. 2015, 43(Database
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
Public Domain Dedication for more information.
Project description:Gene expression changes in mouse ventral dermal fibroblasts in response to Beta-Catenin stabilization in vitro Overall design: Goal of study was to examine gene expression changes upon stabilization of beta-catenin in P4 ventral mouse dermal fibroblasts in vitro
Project description:Deregulation of canonical Wnt/beta-catenin pathway is one of the earliest events in the pathogenesis of colon cancer. Mutations in APC or CTNNB1 (beta-catenin gene) are highly frequent in colon cancer and cause aberrant stabilization of b-catenin, which activates the transcription of Wnt target genes by binding to chromatin via the TCF/LEF transcription factors. Here we report an integrative analysis of genome-wide chromatin occupancy of b-catenin by chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) and gene expression profiling by microarray analysis upon RNAi-mediated knockdown of beta-catenin in colon cancer cells (GSE53656). Immunoprecipitated samples from human colon cancer SW480 cells with antibodies against beta-catenin and control IgG respectively were used for ChIP-seq experiments.
Project description:Gain-of-function mutations in exon 3 of beta-catenin (CTNNB1) are specific for Wilms' tumors that have lost WT1, but 50% of WT1-mutant cases lack such "hot spot" mutations. To ask whether stabilization of beta-catenin might be essential after WT1 loss, and to identify downstream target genes, we compared expression profiles in WT1-mutant versus WT1 wild-type Wilms' tumors. Supervised and nonsupervised hierarchical clustering of the expression data separated these two classes of Wilms' tumor. The WT1-mutant tumors overexpressed genes encoding myogenic and other transcription factors (MOX2, LBX1, SIM2), signaling molecules (TGFB2, FST, BMP2A), extracellular Wnt inhibitors (WIF1, SFRP4), and known beta-catenin/TCF targets (FST, CSPG2, CMYC). Beta-Catenin/TCF target genes were overexpressed in the WT1-mutant tumors even in the absence of CTNNB1 exon 3 mutations, and complete sequencing revealed gain-of-function mutations elsewhere in the CTNNB1 gene in some of these tumors, increasing the overall mutation frequency to 75%. Lastly, we identified and validated a novel direct beta-catenin target gene, GAD1, among the WT1-mutant signature genes. These data highlight two molecular classes of Wilms' tumor, and indicate strong selection for stabilization of beta-catenin in the WT1-mutant class. Beta-Catenin stabilization can initiate tumorigenesis in other systems, and this mechanism is likely critical in tumor formation after loss of WT1. Experiment Overall Design: Identification of WNT/Beta-Catenin or WT1 target genes. 39 individual samples.
Project description:Genome wide expression profiling to determine the overlap of Affymetrix-signals with SOLID sequencing RNA was extracted using the Qiagen RNeasy kit following the manufacturers guidelines, arrays were prepared and hybridized following the Affymetrix protocol. Overall design: Mus musculus samples from small intestine and colon, to be compared to transcript data aquired with other techniques
Project description:During Xenopus gastrulation, dorsal stabilization of β-Catenin at the earliest stage and subsequent target genes expression are critical for dorsal-ventral axis determination. However, many β-Catenin targets that mediate this process are still unkown. Here through RNA-seq analysis of β-Catenin knockdown embryos and self-regulating dorsal and ventral half embryos at early gastrula, we define an early β-Catenin gene signature that is downregulated by β-Catenin MO and enriched in dorsal gastrula tissues. This gene signature includes classic Spemann organizer genes, as well as other novel genes. Further analyses revealed that the early β-Catenin gene signature is positively correlated with LiCl treated, Wnt8 and Siamois mRNA-induced genes, consistent with their early role in dorsal-ventral axis formation. Our results also show that St 10.5 is the appropriate stage to uncover β-Catenin target genes that regulate dorsal-ventral patterning than St 9. Meanwhile, the multi-growth factor antagonist Cerberus inhibits part of the early β-Catenin gene signature and also controls the expression of a unique set of genes. Our findings provide new insight into the pivotal role of β-catenin in dorsal-ventral axis determination and can serve a fruitful resource for this field. Overall design: A genome-wide study of the effects of depleting the early dorsal b-Catenin signal which is responsible for the induction of the body axis.