164 POTENTIAL REGULATION OF PERI-IMPLANTATION OVINE CONCEPTUS GROWTH AND DIFFERENTIATION BY THE WNT SIGNALING SYSTEM

2007 ◽  
Vol 19 (1) ◽  
pp. 199
Author(s):  
K. Hayashi ◽  
R. C. Burghardt ◽  
F. W. Bazer ◽  
T. E. Spencer
Keyword(s):  
Wnt Signaling ◽  
Cell Fate ◽  
Target Genes ◽  
Glycogen Synthase ◽  
Wnt Signaling Pathway ◽  
Density Lipoprotein ◽  
Cell Types ◽  
Negative Regulator ◽  
Beta Catenin ◽  
Canonical Wnt

In mice WNT signaling regulates cell fate, differentiation, and growth in the conceptus (embryo and associated extra-embryonic membranes), as well as implantation. We studied various components of the WNT signaling pathway in the ovine uterus during the estrous cycle (C) and pregnancy (P) and in the peri-implantation conceptus. Expression of WNT2, WNT2B, and WNT4 mRNAs was very low in endometria of C and P ewes from Days 10 to 16 and in conceptus trophectoderm (Tr). WNT5A/5B mRNAs were abundant in the stratum compactum stroma, whereas WNT11 mRNA was detected in endometrial epithelia of C and P ewes, but not in conceptus Tr. WNT7A mRNA was localized specifically to luminal (LE) and superficial glandular (sGE) epithelia of Day 10 C and P ewes, was undetectable by Day 12, and then increased up to Day 16 and was maximum on Day 20 only in P ewes. Frizzled receptor (FZD6/8) mRNAs were detected primarily in conceptus Tr and uterine LE and GE, whereas the co-receptor LRP5/6 (low density lipoprotein receptor-related protein) mRNAs were expressed in all uterine cell types and conceptus Tr. Dickkopf (DKK1), a negative regulator of WNT signaling, was detected in stratum compactum stroma after Day 14 in P ewes. CTNNB1 (beta-catenin), a key mediator of canonical WNT signaling, and GSK3B (glycogen synthase kinase-3 beta) and CHD1 (E-cadherin) mRNAs were abundant in endometrial epithelia and in conceptus Tr. Immunoreactive CTNNB1 protein was abundant in LE and GE, and present at lower levels in stroma and myometrium in uteri from C and P ewes. In the conceptus Tr, immunoreactive CTNNB1 protein was abundant in nuclei of the mononuclear and binuclear cells (BNC), as well as in cell adherens junctions. Nuclear CTNNB1 interacts with transcription factors, most notably LEF1/TCF7 (lymphoid enhancer-binding factor 1/transcription factor 7), to regulate gene transcription. LEF1 mRNA was detected in LE and sGE, whereas nuclear TCF7L2 protein was particularly abundant in trophoblast giant BNC. WNT/beta-catenin/TCF7 target genes were also studied. MSX2 mRNA was abundant in conceptus Tr, and MYC mRNA was abundant in BNC of conceptus Tr and endometrial epithelia. Next, ovine Tr (oTr) cells and endometrial stromal (oST) cells were used for mechanistic studies that revealed that transfection of mouse WNT7A stimulated a LEF/TCF-responsive reporter (TOPFLASH), and co-transfection of either dnTCF or SFRP2 (a secreted FZD inhibitor) inhibited WNT7A effects. WNT7A stimulated expression of MSX2 and MYC in oTr cells, and this effect was inhibited by SFRP2. These results implicate the canonical WNT system as a regulator of peri-implantation conceptus growth and differentiation in sheep. This work was supported by NIH HD38274 and 5 P30 ES09106 funding.

scholarly journals Caprin-2 enhances canonical Wnt signaling through regulating LRP5/6 phosphorylation

2008 ◽  
Vol 182 (5) ◽  
pp. 865-872 ◽  
Author(s):  
Yu Ding ◽  
Ying Xi ◽  
Ting Chen ◽  
Ji-yong Wang ◽  
Dong-lei Tao ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Mammalian Cells ◽  
Target Genes ◽  
Glycogen Synthase ◽  
Signal Transmission ◽  
Low Density Lipoprotein ◽  
Wnt Signaling Pathway ◽  
Density Lipoprotein ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt

The low-density lipoprotein receptor–related proteins 5 and 6 (LRP5/6) are coreceptors for Frizzled and transmit signals from the plasma membrane to the cytosol. However, the mechanism for LRP5/6 signal transmission remains undefined. Here, we identify cytoplasmic activation/proliferation-associated protein 2 (Caprin-2) as a LRP5/6-binding protein. Our data show that Caprin-2 stabilizes cytosolic β-catenin and enhances lymphoid enhancer-binding factor 1/T cell factor–dependent reporter gene activity as well as the expression of Wnt target genes in mammalian cells. Morpholino-mediated knockdown of Caprin-2 in zebrafish embryos inhibits Wnt/β-catenin signaling and results in a dorsalized phenotype. Moreover, Caprin-2 facilitates LRP5/6 phosphorylation by glycogen synthase kinase 3, and thus enhances the interaction between Axin and LRP5/6. Therefore, Caprin-2 promotes activation of the canonical Wnt signaling pathway by regulating LRP5/6 phosphorylation.

scholarly journals A divergent canonical WNT-signaling pathway regulates microtubule dynamics

2004 ◽  
Vol 164 (2) ◽  
pp. 243-253 ◽  
Author(s):  
Lorenza Ciani ◽  
Olga Krylova ◽  
Matthew J. Smalley ◽  
Trevor C. Dale ◽  
Patricia C. Salinas
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Transcriptional Activation ◽  
Glycogen Synthase ◽  
Wnt Signaling Pathway ◽  
Negative Regulator ◽  
Canonical Wnt Signaling ◽  
Microtubule Stability ◽  
Gsk 3Β ◽  
Canonical Wnt

Dishevelled (DVL) is associated with axonal microtubules and regulates microtubule stability through the inhibition of the serine/threonine kinase, glycogen synthase kinase 3β (GSK-3β). In the canonical WNT pathway, the negative regulator Axin forms a complex with β-catenin and GSK-3β, resulting in β-catenin degradation. Inhibition of GSK-3β by DVL increases β-catenin stability and TCF transcriptional activation. Here, we show that Axin associates with microtubules and unexpectedly stabilizes microtubules through DVL. In turn, DVL stabilizes microtubules by inhibiting GSK-3β through a transcription- and β-catenin–independent pathway. More importantly, axonal microtubules are stabilized after DVL localizes to axons. Increased microtubule stability is correlated with a decrease in GSK-3β–mediated phosphorylation of MAP-1B. We propose a model in which Axin, through DVL, stabilizes microtubules by inhibiting a pool of GSK-3β, resulting in local changes in the phosphorylation of cellular targets. Our data indicate a bifurcation in the so-called canonical WNT-signaling pathway to regulate microtubule stability.

scholarly journals Fas-associated factor 1 antagonizes Wnt signaling by promoting β-catenin degradation

2011 ◽  
Vol 22 (9) ◽  
pp. 1617-1624 ◽  
Author(s):  
Long Zhang ◽  
Fangfang Zhou ◽  
Theo van Laar ◽  
Juan Zhang ◽  
Hans van Dam ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Glycogen Synthase ◽  
Ectopic Expression ◽  
Wnt Signaling Pathway ◽  
Negative Regulator ◽  
Associated Factor ◽  
Functional Studies ◽  
Cell Proliferation And Differentiation ◽  
Canonical Wnt

The canonical Wnt pathway plays an important role in the regulation of cell proliferation and differentiation. Activation of this signaling pathway causes disruption of the Axin/adenomatous polyposis coli/glycogen synthase kinase 3β complex, resulting in stabilization of β-catenin and its association with lymphoid enhancer factor/T-cell factor in the nucleus. Here, we identify Fas-associated factor 1 (FAF1) as a negative regulator of Wnt/β-catenin signaling. We found overexpression of FAF1 to strongly inhibit Wnt-induced transcriptional reporter activity and to counteract Wnt-induced β-catenin accumulation. Moreover, knockdown of FAF1 resulted in an increase in β-catenin levels and in activation of Wnt/β-catenin–induced transcription. FAF1 was found to interact with β-catenin upon inhibition of proteasome. Ectopic expression of FAF1 promoted β-catenin degradation by enhancing its polyubiquitination. Functional studies in C2C12 myoblasts and KS483 preosteoblastic cells showed that FAF1 depletion resulted in activation of endogenous Wnt-induced genes and enhanced osteoblast differentiation, whereas FAF1 overexpression had the opposite effect. These results identify FAF1 as a novel inhibitory factor of canonical Wnt signaling pathway.

scholarly journals The microRNA miR-8 is a conserved negative regulator of Wnt signaling

2008 ◽  
Vol 105 (40) ◽  
pp. 15417-15422 ◽  
Author(s):  
Jennifer A. Kennell ◽  
Isabelle Gerin ◽  
Ormond A. MacDougald ◽  
Ken M. Cadigan
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Target Genes ◽  
Wnt Signaling Pathway ◽  
Negative Regulator ◽  
Animal Development ◽  
Protein Levels ◽  
Evolutionarily Conserved ◽  
Multiple Levels

Wnt signaling plays many important roles in animal development. This evolutionarily conserved signaling pathway is highly regulated at all levels. To identify regulators of the Wnt/Wingless (Wg) pathway, we performed a genetic screen in Drosophila. We identified the microRNA miR-8 as an inhibitor of Wg signaling. Expression of miR-8 potently antagonizes Wg signaling in vivo, in part by directly targeting wntless, a gene required for Wg secretion. In addition, miR-8 inhibits the pathway downstream of the Wg signal by repressing TCF protein levels. Another positive regulator of the pathway, CG32767, is also targeted by miR-8. Our data suggest that miR-8 potently antagonizes the Wg pathway at multiple levels, from secretion of the ligand to transcription of target genes. In addition, mammalian homologues of miR-8 promote adipogenesis of marrow stromal cells by inhibiting Wnt signaling. These findings indicate that miR-8 family members play an evolutionarily conserved role in regulating the Wnt signaling pathway.

Anti-Tumor Activity of Novel Small Molecule Wnt Signaling Inhibitor, CWP232291, In Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3038-3038 ◽  
Author(s):  
Joo Young Cha ◽  
Ji-Eun Jung ◽  
Kwan-Hoo Lee ◽  
Isabelle Briaud ◽  
Fnu Tenzin ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Wnt Signaling ◽  
Caspase 3 ◽  
Target Genes ◽  
Plasma Cells ◽  
Wnt Signaling Pathway ◽  
Beta Catenin ◽  
Tumor Bearing ◽  
Induction Of Apoptosis ◽  
Rpmi 8226

Abstract Abstract 3038 Multiple myeloma (MM), one of the most incurable hematological malignancies in adults, is a disorder of plasma cells characterized by accumulation of clonal proliferation of malignant plasma cells in the bone marrow (BM). Overexpression of beta-catenin, the downstream effector of the canonical Wnt signaling pathway, has been reported in both MM cell lines and patient samples. Activated Wnt signaling pathway has also been reported to play a critical role in progression of MM cell proliferation, thus highlighting the need for new therapeutic approaches, particularly those targeting Wnt molecular pathway. Here we report the discovery of a novel inhibitor of Wnt signaling CWP232291, which promotes degradation of beta-catenin. CWP232291 exhibits potent growth inhibitory activity in several MM cell lines (RPMI-8226, OPM-2, NCI-H929, JJN3, and EJM) with IC50 values of 13 – 73 nM. The inhibitory activity of CWP232291 on Wnt signaling is demonstrated by reporter gene assay and by its effect in down-regulation of Wnt target genes. Using HEK293 cells, CWP232291 treatment dose dependently reduces promoter activity of TOPflash induced by Wnt-3a-Conditioned Media, at a calculated IC50 value of 273 nM. Furthermore, MM cells treated with CWP232291 show downregulated expression of Wnt target genes such as survivin by triggering degradation of beta-catenin. Treatment of these cells with CWP232291 results in activation of caspase-3 and PARP cleavage, indicating induction of apoptosis. To investigate the potential in vivo anti-tumor efficacy of CWP232291, we utilized two MM tumor bearing mice models. Daily or intermittent intravenous (i.v.) administration of CWP232291 led to significant tumor growth inhibition (TGI) in OPM-2 (50 mg/kg, qdx5: regression and 100 mg/kg, biw: 95% TGI) and RPMI-8226 (100 mg/kg, qdx5: regression and 100 mg/kg tiw: 80% TGI) xenograft model with no obvious change in body weight. The anti-tumor efficacies of CWP232291 were dose-dependent and had strong correlations with degradation of beta-catenin in the tumor samples. Potent induction of apoptosis through cleavage of Caspase-3 and PARP and significant decrease of plasma M protein levels in OPM-2 tumor bearing mice were detected as early as 2 and up to 24 hours after single i.v. administration of CWP232291. Taken together, these data clearly demonstrate the impressive anti-tumor profile of CWP232291 with a good therapeutic window and suggest a potential therapeutic application of CWP232291 for the treatment of MM. Disclosures: Cha: Choongwae Pharma Corp.: Employment. Jung:Choongwae Pharma Corp.: Employment. Lee:Choongwae Pharma Corp.: Employment. Briaud:Theriac Pharmaceutical Corp.: Employment. Tenzin:Theriac Pharmaceutical Corp.: Employment. Jung:Choongwae Pharma Corp.: Employment. Pyon:Choongwae Pharma Corp.: Employment. Lee:Choongwae Pharma Corp.: Employment. Chung:Choongwae Pharma Corp.: Employment. Lee:Choongwae Pharma Corp.: Employment. Oh:Choongwae Pharma Corp.: Employment. Jung:Choongwae Pharma Corp.: Employment. Pai:Choongwae Pharma Corp.: Employment. Emami:Theriac Pharmaceutical Corp.: Employment.

scholarly journals Targeting Wnt signaling in colorectal cancer. A Review in the Theme: Cell Signaling: Proteins, Pathways and Mechanisms

2015 ◽  
Vol 309 (8) ◽  
pp. C511-C521 ◽  
Author(s):  
Laura Novellasdemunt ◽  
Pedro Antas ◽  
Vivian S. W. Li
Keyword(s):  
Wnt Signaling ◽  
Cell Fate ◽  
Wnt Pathway ◽  
High Throughput Sequencing ◽  
Wnt Signaling Pathway ◽  
Negative Regulator ◽  
Cell Fate Decisions ◽  
Stem Cell Maintenance ◽  
Evolutionarily Conserved

The evolutionarily conserved Wnt signaling pathway plays essential roles during embryonic development and tissue homeostasis. Notably, comprehensive genetic studies in Drosophila and mice in the past decades have demonstrated the crucial role of Wnt signaling in intestinal stem cell maintenance by regulating proliferation, differentiation, and cell-fate decisions. Wnt signaling has also been implicated in a variety of cancers and other diseases. Loss of the Wnt pathway negative regulator adenomatous polyposis coli (APC) is the hallmark of human colorectal cancers (CRC). Recent advances in high-throughput sequencing further reveal many novel recurrent Wnt pathway mutations in addition to the well-characterized APC and β-catenin mutations in CRC. Despite attractive strategies to develop drugs for Wnt signaling, major hurdles in therapeutic intervention of the pathway persist. Here we discuss the Wnt-activating mechanisms in CRC and review the current advances and challenges in drug discovery.

scholarly journals The Wnt Signaling Antagonist Kremen1 is Required for Development of Thymic Architecture

2006 ◽  
Vol 13 (2-4) ◽  
pp. 299-319 ◽  
Author(s):  
Masako Osada ◽  
Emi Ito ◽  
Hector A. Fermin ◽  
Edwin Vazquez-Cintron ◽  
Tadmiri Venkatesh ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Wnt Signaling Pathway ◽  
Fold Increase ◽  
Negative Regulator ◽  
Thymic Epithelial Cells ◽  
Canonical Wnt Signaling ◽  
Thymocyte Proliferation ◽  
Elevated Expression ◽  
Wnt Inhibitor ◽  
Canonical Wnt

Wnt signaling has been reported to regulate thymocyte proliferation and selection at several stages during T cell ontogeny, as well as the expression ofFoxN1in thymic epithelial cells (TECs). Kremen1 (Krm1) is a negative regulator of the canonical Wnt signaling pathway, and functions together with the secreted Wnt inhibitor Dickkopf (Dkk) by competing for the lipoprotein receptor-related protein (LRP)-6 co-receptor for Wnts. Herekrm1knockout mice were used to examinekrm1expression in the thymus and its function in thymocyte and TEC development.krm1expression was detected in both cortical and medullary TEC subsets, as well as in immature thymocyte subsets, beginning at the CD25+CD44+ (DN2) stage and continuing until the CD4+CD8+(DP) stage. Neonatal mice show elevated expression ofkrm1in all TEC subsets.krm1− / −mice exhibit a severe defect in thymic cortical architecture, including large epithelial free regions. Much of the epithelial component remains at an immature Keratin 5+(K5) Keratin 8+(K8) stage, with a loss of defined cortical and medullary regions. A TOPFlash assay revealed a 2-fold increase in canonical Wnt signaling in TEC lines derived fromkrm1− / −mice, when compared withkrm1+ / +derived TEC lines. Fluorescence activated cell sorting (FACS) analysis of dissociated thymus revealed a reduced frequency of both cortical (BP1+EpCAM+) and medullary (UEA-1+EpCAMhi) epithelial subsets, within thekrm1− / −thymus. Surprisingly, no change in thymus size, total thymocyte number or the frequency of thymocyte subsets was detected inkrm1− / −mice. However, our data suggest that a loss of Krm1 leads to a severe defect in thymic architecture. Taken together, this study revealed a new role for Krm1 in proper development of thymic epithelium.

scholarly journals Axil, a Member of the Axin Family, Interacts with Both Glycogen Synthase Kinase 3β and β-Catenin and Inhibits Axis Formation ofXenopus Embryos

1998 ◽  
Vol 18 (5) ◽  
pp. 2867-2875 ◽  
Author(s):  
Hideki Yamamoto ◽  
Shosei Kishida ◽  
Takaaki Uochi ◽  
Satoshi Ikeda ◽  
Shinya Koyama ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Binding Site ◽  
Glycogen Synthase ◽  
Wnt Signaling Pathway ◽  
Amino Acid Identity ◽  
Negative Regulator ◽  
Glycogen Synthase Kinase ◽  
Axis Formation ◽  
Glycogen Synthase Kinase 3Β ◽  
Gsk 3Β

ABSTRACT Using a yeast two-hybrid method, we identified a novel protein which interacts with glycogen synthase kinase 3β (GSK-3β). This protein had 44% amino acid identity with Axin, a negative regulator of the Wnt signaling pathway.We designated this protein Axil for Axin like. Like Axin, Axil ventralized Xenopus embryos and inhibited Xwnt8-induced Xenopus axis duplication. Axil was phosphorylated by GSK-3β. Axil bound not only to GSK-3β but also to β-catenin, and the GSK-3β-binding site of Axil was distinct from the β-catenin-binding site. Furthermore, Axil enhanced GSK-3β-dependent phosphorylation of β-catenin. These results indicate that Axil negatively regulates the Wnt signaling pathway by mediating GSK-3β-dependent phosphorylation of β-catenin, thereby inhibiting axis formation.

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